Research ArticleInfluence of Initial Moisture Content on Heat and MoistureTransfer in Firefightersrsquo Protective Clothing
Dongmei Huang12 and Song He3
1College of Quality and Safety Engineering China Jiliang University Hangzhou Zhejiang 310018 China2Key Laboratory of Furniture Inspection Technology of Zhejiang Province Hangzhou Zhejiang 310018 China3State Key Laboratory of Fire Science University of Science and Technology of China Hefei Anhui 230027 China
Correspondence should be addressed to Dongmei Huang 20021567163com
Received 12 September 2016 Revised 17 January 2017 Accepted 22 February 2017 Published 30 March 2017
Academic Editor Jianlei Niu
Copyright copy 2017 Dongmei Huang and Song He This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited
This paper presents amodel for heat andmoisture transfer through firefightersrsquo protective clothing (FPC) during radiation exposureThe model which accounts for air gaps in the FPC as well as heat transfer through human skin investigates the effect of differentinitial moisture contents on the thermal insulation performance of FPC Temperature water vapor density and the volume fractionof liquid water profiles were monitored during the simulation and the heat quantity absorbed by water evaporation was calculatedThen themaximumdurations of heat before thewearer acquires first- and second-degree burnswere calculated based on the bioheattransfer equation and the Henriques equation The results show that both the moisture weight in each layer and the total moistureweight increase linearly within a given environmental humidity level The initial moisture content in FPC samples significantlyinfluenced the maximum water vapor density The first- and second-degree burn injury time increase 16 sec and 18 sec when theRH increases from 0 to 90 The total quantity of heat accounted for by water evaporation was about 10 when the relativehumidity (RH) is 80 Finally a linear relationship was identified between initial moisture content and the human skin burn injurytime before suffering first- and second-degree burn injuries
1 Introduction
Firefightersrsquo protective clothing (FPC) constitutes criticallyimportant equipment in firefighting Typical FPC consists oftwo parts an outer shell and an inner linear [1 2] In generalthe moisture content in FPC material significantly affects thewearerrsquos thermal and moisture comfort These effects havesparked considerable interest in researching the mechanismsof heat and moisture transfer in FPC materials [3ndash5]
Moisture contained in FPC material usually results fromhuman sweat penetration of outside water during a rescueor moisture in the settled environment [6ndash8] With sufficientheat liquid moisture in the fabric undergoes an endothermicprocess and transforms into steam [9] In addition moisturein the fabric increases the heat capacity of the material suchthat moist materials absorb more heat Therefore moisturein the fabric can limit the amount of energy transferred tohuman skin Recent research has examined the effects of
moisture that comes from human sweat and outside water[10ndash12]
The initial moisture content of FPC material is deter-mined by the relative humidity (RH) of the storage environ-ment and moisture generally settles in the pores of the fabricbefore heating Moisture evaporation mainly occurs duringthe early stage of heating which is of critical importancein determining heat and moisture transfer In this paperwe describe a simulation approach that can characterize theinfluence of initial moisture content on the heat insulationperformance of multilayer FPC materials with air gapsbetween each layer The intention of this study is to describemoisture absorption desorption and evaporation during theearly stage of heating In order to explain the mechanism bywhich initial moisture content acts to influence the thermalprotective performance of these materials we also estimatethe maximum duration of the temperature before the wearersuffers first- and second-degree burn injuries
Hindawie Scientific World JournalVolume 2017 Article ID 9365814 13 pageshttpsdoiorg10115520179365814
2 The Scientific World Journal
Figure 1 Schematic diagram and view of experimental chamber
Figure 2 Thermocouples and sample holder
2 Experimental Methods
The experimental equipment used in this study consisted of aradiation source test chamber constant temperature systemand data acquisition system as shown in Figure 1 A detailedintroduction to the experimental equipment can be found inHe et alrsquos paper [13]
The samples were cut from the FPC currently in use inChina The FPC material is composed of four layers theouter shell (OS) the moisture barrier layer (MB) the thermalbarrier layer (TB) and the comfort layer (CL) The materialscomprising the layers are XDB602 aramid fabric coatedwith PTFE film aramid insulation and cotton shirtingrespectively The dimension of the samples was 230mmtimes 230mm First eight samples were set in a drying oven(ZK-1000A Shanghai Hong Yun experimental equipmentfactory China) at a temperature of 100∘C for 24 h to removeinternal moisture Then two of the samples were put intoprogrammable constant temperature and humidity testers(PCTHC) for 24 hThe temperature of the PCTHC was set at20∘C and the humiditywas set at 30plusmn5 50plusmn5 65plusmn5 and80 plusmn 5 to achieve different initial moisture contents amongthe samples The humidity allowed moisture to be wickedinto layered samples and held in the fiber pores [14] leadingto an increase in moisture content The moisture weight ineach fiber layer was determined after the sample was placed
into different relative humidity situations using an electronicbalance with an accuracy of 0001 g over threemeasurements
The thermocouples usedwere identical to those describedin He et alrsquos paper [13] and we named them thermocoupleat the outer shell layer (TCO) thermocouple at the moisturebarrier layer (TCM) thermocouple at the thermal linerlayer (TCH) thermocouple at the comfort layer (TCC) andthermocouple at the wearer skin surface (TCW) as shownin Figure 2 The samples were fixed in the test chamberusing a sample holder on the sample trolley According toLawsonrsquos report [15] the radiation intensity on the corridorfloor decreases as the distance from the fire source increasesand the radiation intensity is about 18minus10 kWmminus2 In thisexperiment the radiation intensity was set at a constant valueof 5 kWmminus2 We measured the temperature at the outersurface of the outer shell layer which increased graduallyThe radiation source was turned off after 120 sec because theFPC material began combustion and totally lost its thermalinsulation performance after 120 sec under 10 kWmminus2
3 Theoretical Models
This study developed a model for coupled heat and mois-ture transmission in FPC materials during the radiationheating process The effects of both initial moisture content
The Scientific World Journal 3
Radi
atio
n so
urce
Out
er sh
ell
Moi
sture
bar
rier l
ayer
Ther
mal
line
r lay
er
Com
fort
laye
r
Epi
derm
is
Der
mis
Subc
utan
eous
0Thickness
Basal layer TCOTCMTCHTCC
Figure 3 Sketch of heat and moisture transfer in FPC materials and heat transport in human skin
as determined by RH and the temperature of the storageenvironment on the FPC samplesrsquo insulation performancewere investigated The burn injury times for human skinunder different conditions were also determined Figure 3shows a sketch of heat andmoisture transfer in FPCmaterialsas well as heat transfer through human skin The structureandmaterials of each layer were simulated in the experimentIn practice air gaps (AG) exist between each fabric layer ofFPC material because the four fabric layers are separated bya small amount of spaceTherefore our computer simulationincorporated an AG of 05mm between each fabric layerThere is also an air gap between the comfort layer and thewearerrsquos skin which has a thickness of 1mm The humanskin consists of three layers from outermost to innermostepidermis dermis and subcutaneous
We based our simulation model on Chitrphiromsrirsquosmodel [10 16 17] which can simulate heat and moisturetransfer in multilayer fabricThis simulation is built upon theequations for mass momentum and energy conservationThe conservation equations in each fabric layer are as follows
Energy equation is as follows
(120588119888119901)eff120597119879120597119905 + (120588119888119901)119897 V119897
120597119879120597119909
= 120597120597119909 (119896eff 120597119879120597119909) + Δℎvap (V119897 + V119887)+ Δℎtrans (119897119887 + V119887) + 120574 119902rad119890minus120574119909 + 119894119894
(1)
Mass equations are as follows
solid 120597120597119905 (120588119887120576119887) = V119887 + 119897119887
liquid 120597120597119905 (120588119897120576119897) +
120597120597119909 (120588119897V119897) = V119897 minus 119897119887
gas 120597120597119905 (120588V120576119892) = 120597
120597119909 (119863eff120597120588V120597119909 ) minus V119897 minus V119887
(2)
Momentum equation for liquid water is as follows
V119897 = minus119904 sdot 119870119897120583119897
120597120597119909 (119875119888) (3)
In (1) 119894119894 is the radiation heat flux between each fabriclayer defined as follows
119894119894 = 120574 119902minus119894119894119890minus120574(119909minussum119894119894minus1
0119871 119894 119894) + 120574 119902+119894119894119890minus120574(sum
119894119894
0119871 119894 119894minus119909)
119894119894 = 1 2 3 4(4)
where 119894119894 is the layer number For example 119894119894 = 1 representsthe outer shell layer so 119902minus119894119894 and 119902+119894119894 are the heat flux on the backand front surfaces respectively In this case
119902minus119894119894 = 120575120576 (1198794119894119894minus1 minus 1198794119894119894) 119894119894 = 1 2 3 4119902+119894119894 = 120575120576 (1198794119894119894 minus 1198794119894119894+1) 119894119894 = 1 2 3 4
(5)
The conservation equations for each air gap are as follows
Energy equation is as follows
(120588119888119901)eff120597119879120597119905 = 120597
120597119909 (119896eff 120597119879120597119909) + ΔℎvapV119897 (6)
Mass equation is as follows
120597120597119905 (120588V) =
120597120597119909 (119863eff
120597120588V120597119909 ) minus V119897 (7)
The heat transfer in each skin layer was estimated usingPennesrsquo model as follows [18]
(120588119862119875)skin 120597119879120597119905 = nabla (119896skinnabla119879)
+ (120588119862119901)blood 119908119887 (119879art minus 119879) (8)
4 The Scientific World Journal
05 10 15 20 25 30 35
Distance (times10minus3 m)
10minus310minus2 10minus4
10minus5
30
40
50
60
70
80
90
100Te
mpe
ratu
re (∘
C)
(a) Results of time independence test
0 20 40 60 80 100 120
Time (s)
40
60
80
100
120
140
160
180
Tem
pera
ture
(∘C)
10minus3
10minus410minus5
10minus6
(b) Results of grid step independence test
Figure 4 Temperature distributions for time and grid independence tests
Initial conditions are as follows119879 (119909 0) = 293119870120588V (119909 0) = 120588V0120576119897 (119909 0) = 1205761198970120576119887 (119909 0) = 1205761198870V119897 (119909 0) = V1198970
(9)
Boundary conditions for the fabric are as follows
119879|119909=0 = minus345713119890minus119905391541 + 6582739minus119863eff
120597120588V120597119909
10038161003816100381610038161003816100381610038161003816119909=0 = ℎ119898amb (120588Vamb minus 120588V|119909=0) V1198971003816100381610038161003816119909=0 = 0
1205761198971003816100381610038161003816119909=0 = 120576119897left1205761198871003816100381610038161003816119909=0 = 0119879|119909=119871 = 40∘C120588V1003816100381610038161003816119909=119871 = 0V1198971003816100381610038161003816119909=119871 = 0
1205761198971003816100381610038161003816119909=119871 = 01205761198871003816100381610038161003816119909=119871 = 0
(10)
The temperature of the boundary conditions for the fabricis the fitting curve of the average temperature asmeasured bythe thermocouples under radiation of 5 kwmminus2
We used Henriquesrsquo tissue burn injury model [19] todetermine the thermal damage to human skin under the radi-ation heating processThe thermal damage ratewas estimatedusing the first-order Arrhenius rate equation Human skinsustains a burn injury when the temperature of the basal layer(see Figure 3) rises above 44∘C In this case
119889Ω119889119905 =
0 119879 lt 44∘C119875 exp (minusΔ119864
119877119879) 119879 ge 44∘C (11)
Equation (11) can be expressed as an integral equationnamely
Ω = int119905119900119875 exp(minusΔ119864
119877119879)119889119905 (12)
In this work differential equations (1)-(2) and (6)ndash(8)were solved using the finite volume method and time-stepping was carried out according to the well-knownCrank-Nicholson method [20] This process yielded a system ofnonlinear algebraic equations which was resolved by thegoal chasing method The conductivity and diffusivity onthe interface between the air gap and the fabric layer wereestimated using the harmonic mean The under relaxationprocedure with a parameter of 06 was utilized to preventdivergence of the iteration method The iterations wererepeated until the changes in the solutions became smallerthan 10minus6
Time and step independence are illustrated graphicallyin Figure 4 Figure 4(a) shows the temperature distributionin the fabric layers at 10 sec and Figure 4(b) shows thetemperature distribution at the mid thickness of the fabriclayers The data show that after a 10minus3 time step the resultsdo not change significantly CPU time increases from about600 sec to 3600 sec in an Intel i7-2600 processor when
The Scientific World Journal 5
450
400
350
300
250
200
150
100
50
Tem
pera
ture
(∘C)
0 20 40 60 80 100 120
Time (s)
TCONo1TCMNo1TCHNo1TCCNo1TCWNo1
TCONo2TCMNo2TCHNo2
TCWNo2TCCNo2
Figure 5 Temperature change with time at different locations
the time step increases from 10minus3 to 10minus5 The temperaturedistribution when the grid size exceeds 10minus4m is muchdifferent from that when the grid size is smaller than 10minus5mThe maximum temperature difference using a grid size of10minus5m and 10minus6m is about 6∘C CPU time increases fromabout 3600 sec to 21600 sec in an Intel i7-2600 processorwhen the grid step decreases from 10minus3 to 10minus6 To summarizethe time and space step are 10minus3 sec and 10minus5m respectively
4 Results and Discussion
41 Experimental Results To ensure the accuracy of theexperimental results we first analyzed experimental re-peatability The radiation intensity of the experiment was5 kWmminus2 The sample was dry the AG thickness betweenthe back surface of the fabric layer and human skin was zeroOther conditions were set as described above The results areshown in Figure 5Thedata demonstrate that the repeatabilityof experiment results is good
In the simulation the temperature measured at the outersurface and at the back surface of the fabric layer undera radiation intensity of 5 kWmminus2 was set as the T0 and119879119871 boundary temperatures respectively The temperatureequation was obtained by liner fitting using Origin softwareas seen in Figure 6
42 Simulation Results The thermal physical properties ofthe fabric samples used in the simulations can be reviewedin Chitrphiromsri et al [17 21] The parameters for specificheat capacity viscosity density and thermal conductivity ofair at different temperatures are in Taorsquos paper [22] Table 1shows the thermophysical and geometrical properties of thefabric and Table 2 provides the properties of human skinTheparameters of the Henriques equations were set identically to
0 20 40 60 80 100 120
Time (s)
50
100
150
200
250
300
350
400
Tem
pera
ture
(∘C)
TLTR
TL fittingTR fitting
Figure 6 Temperature profiles at outer surface and back surfaceof fabric layer The fitting equations for 119879119871 and 119879119877 are 119879119871 =minus345713 exp(minus119905391541) + 6582739 and 119879119877 = 31196812 +164134119905 minus 0077611199052 minus 0077611199053 + 0002031199054 minus 197183 times 10minus5 +646652 times 10minus81199055
Moi
sture
cont
ent (times10
minus3
kg)
20
16
12
08
04
000 10 20 30 40 50 60 70 80
RH ()
Outer shellMoisture barrier
Thermal barrierTotal
Figure 7Moisture weight in each fiber layer against RHwith fittingline
those in Liu et alrsquos paper [23] The thickness of each samplewas determined by measuring with a caliper three timesTheinitial moisture content is shown in Figure 7
The correlation coefficients of the fitting lines for theexperimental data describing the outer shell moisture bar-rier thermal linear and total multilayer material are 099205097086 099226 and 099700 respectively These resultsdemonstrate that the moisture weight in each layer as wellas the total moisture weight increases linearly with settledenvironmental RH as expected The moisture absorbed bywicking into the thermal barrier is about four times that inthe outer shell layer and two times that in themoisture barrier
6 The Scientific World Journal
Table 1 Thermophysical and geometrical properties of fabric [17 21 22]
Property Outer shell Moisture barrier Thermal barrier Comfort layerThickness of the material119871119894119894 [m] 031 times 10minus3 05 times 10minus3 11 times 10minus3 029 times 10minus3
Material of composition XDB602 Aramid fabric coatedwith PTFE film Aramid insulation Cotton shirting
Density 120588119891 [kgmminus3] 67742 21000 7727 41379Thermal conductivity (119896)119891[Wmminus1 Kminus1]
0075 0052 005 0053
Volume fraction 120576119891 0334 0186 0115 015Fibre curl 120591 15 125 1 1Diffusivity of the gas phasein the fabric119863119891 [m2 secminus1] 0 times 10minus14 0 times 10minus14 0 times 10minus14 0 times 10minus14
Fiber radius 119889119891 [m] 16 times 10minus5 16 times 10minus5 16 times 10minus5 16 times 10minus5
Darcian permeabilitycoefficient m2119870119897sat [m2] 10 times 10minus16 10 times 10minus16 10 times 10minus16 10 times 10minus16
Saturation of the fabric 119904119894119903 01 01 01 01Proportional constant ofliquid water absorption 120574119897119904[kgmminus3]
0 times 10minus4 0 times 10minus4 0 times 10minus4 0 times 10minus4
Table 2 Thermophysical and geometrical properties assigned to skin layers [14 15 25ndash28]
Property Epidermis Dermis Subcutaneous tissue BloodDensity 120588skin [kgmminus3] 1200 1200 1000 1060Thermal conductivity(119896)skin [Wmminus1 ∘Cminus1] 023 045 019 mdash
119871 skin [m] 008 times 10minus3 2 times 10minus3 10 times 10minus3 mdash119888119901skin [J kgminus1 ∘Cminus1] 3600 3300 2300 3770120596119887 [m3 secminus1mminus3 tissue] 0 000125 000125 mdash
layer The samples also felt obviously moist when touchedafter remaining for 24 h in circumstances with RH valuesexceeding 65
We designed an apparatus to simulate the process of heattransfer in FPC samples with different initial moisture con-tentsThe experimental setup and the samples were describedin Section 2 To ensure simulation accuracy we comparedthe simulation results with the experimental measurementswhich were corrected before analysis for radiation lossThe comparison model did not consider human skin Theboundary conditions were set identically to the experimentalmeasurements Figure 8 shows the simulated (continuouslines) and experimental (discrete points) temperature profilesat RH = 65 In the figure TCO TCM TCH and TCCrepresent the measurement results at different locations (asseen in Figure 3) while labels preceded by ldquo119878rdquo representthe simulation results The data show that the simulationresults are in good agreement with the experimental resultsThe mechanism for heat and moisture transfer in a systemconsisting of FPC materials air layers and human skinwith different initial moisture content conditions were thenanalyzed using the validated model combined with Pennesrsquo
model The first and second human injury burn times wereestimated using the Henriquesrsquo tissue burn injury model
Figure 9 shows the temperature profiles in different layersat particular moments in time The origin of the 119909-axis isat the outer shell surface as shown in Figure 3 Figure 9(a)shows that the temperatures in the fabric layers decreasesignificantly with distance at different moments in time buttemperatures decrease slowly in the skin layer A clean breakis identifiable between the fabric layer and the skin layerThismay be because heat transfer in fabric layers occurs throughheat conduction radiation and water evaporation and heatabsorption while the only heat transfer model in the skinlayer is heat conduction The temperature difference in skinunder different initial moisture contents is larger at 100 secthan at 10 sec as shown in Figure 9(b) This is because lessinitial moisture content in the samples leads to more heataccumulated in the fabric and the air gap during radiation
We then analyzed the temperature differences underdifferent initial moisture conditions in the fabric and skinlayers with the results shown in Figures 9(c) and 9(d) Thetemperature difference in the fabric under different initialmoisture contents is higher at 10 s than at 100 s These results
The Scientific World Journal 7
0 20 40 60 80 100 120
Time (s)
Tem
pera
ture
(∘C)
400
350
300
250
200
150
100
50
0
Test-TCOTest-TCMTest-TCHTest-TCC
Simulation-TCOSimulation-TCMSimulation-TCHSimulation-TCC
(a) Temperature versus time
00 05 10 15 25 25 30 35 40
Thickness (times10minus3 m)
400
360
280
200
240
320
120
160
80
40
0
Tem
pera
ture
(∘C)
Test-10 secTest-20 secTest-40 secTest-60 secTest-80 secTest-100 secTest-120 sec
Simulation-20 secSimulation-10 sec
Simulation-40 secSimulation-60 secSimulation-80 secSimulation-100 secSimulation-120 sec
(b) Temperature versus thickness
Figure 8 Simulated (continuous lines) and experimental (discrete points) temperature profiles when RH = 65
are in agreement with the accepted point of view that theinitial moisture content of a sample affects heat transfer inthe fabric primarily at the beginning of heating The humanskin begins at 000388m The skin surface temperatureincreases from 309∘C at 10 sec to around 324∘C at 100 secunder different initial moisture contents The skin temper-ature increases as the initial moisture content of the fabricdecreases
Figure 10 shows the profiles for water vapor density in thefabric and air gap layers at different times The data indicatethat the water vapor density decreases as distance from theouter surface increases this occurs because the water vapordensity decreases with temperature which decreases withdistance Higher temperatures providemore energy for waterevaporation The maximum water vapor density in eachlayer increases very rapidly with t reaching a maximum atabout 20 sec under the conditions outlined in this paper asshown in Figure 11 The curve follows a normal distributionbetween about 10 sec and 35 sec After 35 sec the water vapordensity decreases more slowly with time In other words theactuation duration of the initial moisture of FPC samples wasless than 35 sec in this experimental situation
In our experiment the temperature increased whenthe outer shell of the FPC sample was exposed to heatradiation which caused the desorption and evaporationof bound water as well as the evaporation of free liquidwater located in the fabric pores To examine further themechanism of moisture transformation during heating weanalyzed the liquid water volume fraction in the fabricpores at different times as shown in Figure 12 The datashow that the distribution of liquid water in the fabric
unlike that of water vapor is completely noncontinuous Theinitial liquid water volume fraction in each fabric layer isuniform and it increases noticeably with increasing initialmoisture content As the temperature increases the liquidwater volume fraction decreases and the water vapor densityincreases
Figure 13 plots the heat absorbed by water evaporationagainst RH with a fitting line According to the conser-vation equations moisture in the fabric consists of boundliquid and gaseous water Under high temperatures thebound water transfers to a liquid state and the liquid waterevaporates to a gaseous state The enthalpy of the transitionfrom bound water to free liquid water is about 2509 J gminus1under relative humidity of 65 The enthalpy of evaporationper unit mass is about 2400 J gminus1 The bound water andliquid water volume fractions in each fabric layer can bederived from the simulationThen the heat absorbed throughwater evaporation can be determined based on differentinitial moisture conditions as shown in Figure 13 The datademonstrate that the heat absorbed by water evaporationincreases linearly with increasing RH
Figure 12 shows that the time required for the moistureto evaporate completely is about 70 s The heat flux on thematerial surface is 5 kWmminus2 and the dimension of thesample is 230 cm times 230 cmThe total quantity of heat appliedto the surface of the material is about 18515 J Figure 13 showsthat at the RH level of 80 the heat absorbed through waterevaporation is about 2000 J which constitutesmore than 10of the total heat
We also investigated the effect of the initial fabric mois-ture content on the maximum duration of heat radiation
8 The Scientific World Journal
350
300
250
200
150
100
50
0
Tem
pera
ture
(∘C)
100 sec
50 sec
10 sec
0 1 2 3 4 5
Distance (times10minus3 m)
Fabric layer Skin layer
HR = 30 10 secHR = 65 10 secHR = 30 50 secHR = 65 50 sec
HR = 50 10 secHR = 80 10 secHR = 50 50 secHR = 80 50 sec
HR = 30 100 secHR = 65 100 sec
HR = 50 100 secHR = 80 100 sec
(a) Temperature profile in both fabric and skin layers
100 sec
50 sec
10 sec
Fabric layerSkin layer
Distance (times10minus3 m)385 390 395
40
50
60
Tem
pera
ture
(∘C)
HR = 30 10 secHR = 65 10 secHR = 30 50 secHR = 65 50 sec
HR = 50 10 secHR = 80 10 secHR = 50 50 secHR = 80 50 sec
HR = 30 100 secHR = 65 100 sec
HR = 50 100 secHR = 80 100 sec
(b) Temperature profile at fabric-skin interface
00 05 10 15 20 25 30 35
HR = 30HR = 50
HR = 65HR = 80
100 sec
10 sec
Distance (times10minus3 m)
30
40
50
60
70
80
90
100
110
Tem
pera
ture
(∘C)
50
100
150
200
250
300
Tem
pera
ture
(∘C)
(c) Temperature profile in fabric
400 425 450 475 500 525 550 575
HR = 30HR = 50
HR = 65HR = 80
Distance (times10minus3 m)
100 sec
50 sec
10 sec
32
36
40
44
48
52
56
Tem
pera
ture
(∘C)
(d) Temperature profile in skin
Figure 9 Temperature profiles in different layers at specific moments in time
before the wearer sustains first- and second-degree burninjuries The tissue burn injury model is based on work byHenriques [19] and it is calculated according to (11) Takatarsquos[24] criterion was used to determine that first- and second-degree burn injuries occur whenΩ = 053 and 1 respectivelyon the basal layer of the skin (the interface of the epidermisand dermis) Figure 14 shows human skin burn injury timeversus RH The data show that as the initial moisturecontent in the fabric increases the maximum duration ofheat radiation before acquiring first- and second-degree burninjuries increases linearly This occurs because higher initialmoisture in fabric pores allows more energy to be absorbed
by water phase transfers during the heating process Thefirst- and second-degree burn injury time increases 16 secand 18 sec when the RH increases from 0 to 90 Theheat absorbed through water evaporation is 10 of thetotal quantity of heat applied to the surface of the materialHowever the comfort of clothing is usually very low whenthe clothing is set at the environment in which the RH ismore than 80 Therefore the RH is usually less than 80The temperature at the skin surface at different moment isshown in Figure 15We can see that the temperature decreaseswith increasing the initial moisture content The maximumtemperature difference between the RH of 30 and 80
The Scientific World Journal 9
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
120 sec
006
005
004
003
002
001
00000 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec21 sec32 sec50 sec
16 sec25 sec35 sec80 sec
20 sec30 sec40 sec
(a) RH = 30
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
009
008
007
006
005
004
003
002
001
00000 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec20 sec32 sec50 sec
10 sec25 sec35 sec80 sec
16 sec
120 sec
30 sec40 sec
(b) RH = 50
012
010
008
006
004
002
000
OSAL
MB
AL
TB
AL
CL AL휌
(kg
mminus3)
00 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec11 sec15 sec30 sec
5 sec12 sec16 sec50 sec
10 sec13 sec20 sec120 sec
(c) RH = 65
012
010
008
006
004
002
000
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
00 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec21 sec32 sec50 sec
16 sec25 sec35 sec80 sec
20 sec30 sec40 sec
(d) RH = 80
Figure 10 Distributions of water vapor density at different times
condition is about 1 K which is really slight But the effect ofenergy on the skin injury is an accumulation behavior whichleads to the second-degree burn injury time increasing about8 sec
5 Conclusion
We developed a numerical model to investigate the effectsof initial moisture content at each fabric layer on heat andmoisture transfer in FPCmaterialsWe estimated burn injurytimes under different initial moisture contents using our
model combined with Pennesrsquo model and Henriquesrsquo tissueburn injury model We can draw the following conclusions
(1) Initial moisture content in each FPC fabric layerincreases linearly as the RH of the storage locationincreases
(2) We developed a comprehensive model to simulateheat andmoisture transfer in FPC and the simulationresults show fairly good agreement with the experi-mental results
10 The Scientific World Journal
024
022
020
018
016
014
012
010
008
006
004
002
0000 20 40 60 80 100 120
Time (s)
HR = 30HR = 50
HR = 65HR = 80
휌
(kg
mminus3)
Figure 11 Profiles of water vapor density versus time at a distance of 056 times 10minus3m
(3) Water vapor is distributed both in the fabric layersand in the air layer while free liquid water dispersesonly in the fabric layers Water vapor density ismainly due to evaporation from free liquid waterduring the experiment and it decreases as initialmoisture content increases The total amount of heatabsorption attributable to water evaporation is about10 when the RH is 80
(4) A linear relationship exists between the initial mois-ture content and the maximum duration of heatradiation before causing first- and second-degreeburn injuries
Symbols
119888119901 Specific heat at constant pressureJ kgminus1 ∘Cminus1119863 Diffusivity of the gas phase in the fabricm2 secminus1
119889119891 Fiber radius mℎ119898 Convective heat transfer coefficient
Wmminus2 ∘Cminus1
Δℎ Enthalpy per unit mass J kgminus1119894119894 Fabric layer119896 Thermal conductivity Wmminus1 ∘Cminus1
119870 Darcian permeability coefficient m2119871 Thickness of the material mV119897 Mass transfer rate from the gaseous phase
to the liquid phase kgmminus3 secminus1V119887 Mass transfer rate from the gaseous phase
to the solid phase kgmminus3 secminus1119897119887 Mass transfer rate from the liquid phase to
the solid phase kgmminus3 secminus1119875119888 Pressure of liquid water Pa
119902rad Incident radiation heat flux from theradiation onto the outer fabric surfaceWmminus2119902minus119894119894 Radiation heat flux from the 119894119894 + 1 fabriclayer to the 119894119894 fabric layer Wmminus2119902+119894119894 Radiation heat flux from the 119894119894 minus 1 fabriclayer to the 119894119894 fabric layer Wmminus2
119894119894 Total radiation heat flux of the 119894119894 fabriclayer Wmminus2
119904 Saturation of the fabric119905 Time s119879 Temperature ∘CV Velocity of liquid water m secminus1119909 Distance m
Greek Symbols
120591 Transmissivity of the fabric120591 Fiber curl120588 Density kgmminus3120576 Absorption coefficient120576119887 Volume fraction120574 Radiative extinction coefficient of the
fabric mminus1120583119897 Dynamic viscosity kgmminus1 secminus1120590 Stefan-Boltzmann constant
120575 = 56705 times 10minus8W ∘Cminus4mminus2120596119887 Blood perfusion [000125m3 secminus1mminus3
tissue]Ω Quantitative measure of the burn damage
at the basal layer of human skin119875 Frequency factor or preexponential factor
secminus1Δ119864 Activation energy for skin119877 Universal gas constant
8315 times 103 J kmolminus1 ∘Cminus1
The Scientific World Journal 11
0007
0006
0005
0004
0003
0002
0001
휀l
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
20 sec25 sec30 sec35 sec40 sec
45 sec50 sec55 sec60 sec70 sec
(a) RH = 30
0007
0006
0005
0004
0003
0002
0001
휀l
0012
0011
0010
0009
0008
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
15 sec18 sec20 sec25 sec30 sec
35 sec40 sec50 sec60 sec70 sec
(b) RH = 50
휀l
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(c) RH = 65
휀l
0018
0016
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(d) RH = 80
Figure 12 Liquid water volume fraction distributions at different times
Subscripts
0 Initial stateeff Effective119897 Liquid water119887 Bound waterV Water vaporskin Skinblood Bloodamb Ambient air
vap Evaporationtrans Transferart Human core119871 Left boundary119877 Right boundary
Conflicts of Interest
The authors declare that they have no conflicts of interest
12 The Scientific World JournalH
eat a
bsor
bed
wat
er ev
apor
atio
n (J
)
3000
2500
2000
1500
1000
500
030 40 50 60 70 80
RH ()
Outer shellMoisture barrier
Thermal barrierTotal
Figure 13 Heat absorbed by water evaporation against RH withfitting line
First-degree burn injury timeSecond-degree burn injury time
Burn
inju
ry ti
me (
s)
136
132
128
124
120
116
112
RH ()minus10 0 10 20 30 40 50 60 70 80 90 100
Figure 14 Burning injury time versus RH
Authorsrsquo Contributions
Dongmei Huang carried out the experiment and numericalsimulation and drafted and revised the manuscript Song Heparticipated in the design of the study and performed thestatistical analysis and helped to draft the manuscript Allauthors read and approved the final manuscript
Acknowledgments
This work was supported by Natural Science Foundationof China (no 51306168) and Zhejiang Provincial NaturalScience Foundation of China under Grant no LY17E060004
Tem
pera
ture
(∘C)
Tem
pera
ture
(∘C)
52
51
50
49
48
47
46
45
44
43
42
41
RH ()20 30 40 50 60 70 80 90
360
359
358
357
356
355
354
353
352
351
350
100 sec50 sec10 sec
Figure 15 Temperature at skin surface
References
[1] L D Xu Y L Xy and M Jiang ldquoProtective clothing for fire-fighter GA10-2014rdquo in GA10-2002 China Standards PressBeijing China 2002
[2] D Huang H Yang Z Qi et al ldquoQuestionnaire on firefightersrsquoprotective clothing in Chinardquo Fire Technology vol 48 no 2 pp255ndash268 2012
[3] C C Guerth-Schacher Evaluation of the Effects of Moisture onthe Thermal Protective Performance of Fire Protective Clothingin Low Level Heat Exposures Fire and Polymer Science NorthCarolina State University Raleigh NC USA 2007
[4] R L Barker C Guerth-Schacher R V Grimes and H Hamou-da ldquoEffects of moisture on the thermal protective performanceof firefighter protective clothing in low-level radiant heatexposuresrdquo Textile Research Journal vol 76 no 1 pp 27ndash312006
[5] Y M Lee and R L Barker ldquoEffect of moisture on the thermalprotective performance of heat-resistant fabricsrdquo Journal of FireSciences vol 4 no 5 pp 315ndash331 1986
[6] J O Stull ldquoThe effect of moisture on firefighter protectiveclothing thermal insulation a review of industry researchrdquoin Performance of Protective Clothing Issues and Priorities forthe 21st Century vol 7th ASTM International West Con-shohocken Pa USA 2000
[7] C Keiser C Becker and R M Rossi ldquoMoisture transport andabsorption in multilayer protective clothing fabricsrdquo TextileResearch Journal vol 78 no 7 pp 604ndash613 2008
[8] Y Y Wang Y J Zong J Li and M M Zhao ldquoEvaluating themoisture transfer property of the multi-layered fabric system infirefighter turnout clothingrdquo Fibres amp Textiles in Eastern Europevol 19 no 6 article 89 pp 101ndash105 2011
[9] Y-Y Wang Y-H Lu J Li and J-H Pan ldquoEffects of airgap entrapped in multilayer fabrics and moisture on thermalprotective performancerdquo Fibers and Polymers vol 13 no 5 pp647ndash652 2012
[10] P Chitrphiromsri and A V Kuznetsov ldquoModeling heat andmoisture transport in firefighter protective clothing during flashfire exposurerdquo Heat and Mass Transfer vol 41 no 3 pp 206ndash215 2005
The Scientific World Journal 13
[11] J Fan X Cheng X Wen and W Sun ldquoAn improved modelof heat and moisture transfer with phase change and mobilecondensates in fibrous insulation and comparison with experi-mental resultsrdquo International Journal of Heat andMass Transfervol 47 no 10-11 pp 2343ndash2352 2004
[12] X Cheng and J Fan ldquoSimulation of heat and moisture transferwith phase change and mobile condensates in fibrous insula-tionrdquo International Journal of Thermal Sciences vol 43 no 7pp 665ndash676 2004
[13] SHeDHuang ZQiH Yang YHu andHZhang ldquoThe effectof air gap thickness on heat transfer in firefightersrsquo protectiveclothing under conditions of short exposure to heatrdquo HeatTransfer Research vol 43 no 8 pp 749ndash765 2012
[14] P Andersson and G Holmstedt ldquoHeat sensing manikin testproberdquo Fire and Materials vol 24 no 4 pp 195ndash199 2000
[15] J R Lawson Fire Fighterrsquos Protective Clothing and ThermalEnvironments of Structural Fire Fighting US Department ofCommerce Technology Administration National Institute ofStandards and Technology 1996
[16] P Chitrphiromsri and A V Kuznetsov ldquoPorous mediummodelfor investigating transient heat and moisture transport infirefighter protective clothing under high-intensity thermalexposurerdquo Journal of Porous Media vol 8 no 5 pp 511ndash5282005
[17] P Chitrphiromsri Modeling of Thermal Performance of Fire-fighter Protective Clothing during the Intense Heat ExposureNorth Carolina State University Raleigh NC USA 2004
[18] H P Harry ldquoAnalysis of tissue and arterial blood temperaturesin the resting human forearmrdquo Journal of Applied Physiologyvol 1 no 2 pp 93ndash122 1948
[19] F C Henriques ldquoStudies of thermal injury the predictabilityand the significance of thermally induced rate processes leadingto irreversible epidermal injuryrdquo Archives of pathology vol 43no 5 pp 489ndash502 1947
[20] S A Teukolsky ldquoStability of the iterated Crank-Nicholsonmethod in numerical relativityrdquo Physical Review DmdashParticlesFields Gravitation and Cosmology vol 61 no 8 Article ID087501 2000
[21] F-L Zhu and W-Y Zhang ldquoModeling heat transfer for heat-resistant fabrics considering pyrolysis effect under an externalheat fluxrdquo Journal of Fire Sciences vol 27 no 1 pp 81ndash96 2009
[22] W Q Tao Heat Transfer Northwestern Polytechnical Univer-sity Press Xirsquoan China 2006
[23] J Liu X Chen andL X Xu ldquoNew thermalwave aspects on bumevaluation of skin subjected to instantaneous heatingrdquo IEEETransactions on Biomedical Engineering vol 46 no 4 pp 420ndash428 1999
[24] A N Takata ldquoDevelopment of criterion for skin burnsrdquo Aero-space Medicine vol 45 no 6 pp 634ndash637 1974
[25] T R Gowrishankar D A Stewart G T Martin and J CWeaver ldquoTransport lattice models of heat transport in skinwith spatially heterogeneous temperature-dependent perfu-sionrdquo BioMedical Engineering Online vol 3 article no 42 2004
[26] D A Torvi and J D Dale ldquoA finite element model of skinsubjected to a flash firerdquo Journal of Biomechanical Engineeringvol 116 no 3 pp 250ndash255 1994
[27] A M Stoll and L C Greene ldquoRelationship between pain andtissue damage due to thermal radiationrdquo Journal of AppliedPhysiology vol 14 no 3 pp 373ndash382 1959
[28] MGasperin andD Juricic ldquoThe uncertainty in burn predictionas a result of variable skin parameters an experimental evalu-ation of burn-protective outfitsrdquo Burns vol 35 no 7 pp 970ndash982 2009
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Renewable Energy
Submit your manuscripts athttpswwwhindawicom
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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Volume 201Hindawi Publishing Corporation httpwwwhindawicom Volume 201
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The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
2 The Scientific World Journal
Figure 1 Schematic diagram and view of experimental chamber
Figure 2 Thermocouples and sample holder
2 Experimental Methods
The experimental equipment used in this study consisted of aradiation source test chamber constant temperature systemand data acquisition system as shown in Figure 1 A detailedintroduction to the experimental equipment can be found inHe et alrsquos paper [13]
The samples were cut from the FPC currently in use inChina The FPC material is composed of four layers theouter shell (OS) the moisture barrier layer (MB) the thermalbarrier layer (TB) and the comfort layer (CL) The materialscomprising the layers are XDB602 aramid fabric coatedwith PTFE film aramid insulation and cotton shirtingrespectively The dimension of the samples was 230mmtimes 230mm First eight samples were set in a drying oven(ZK-1000A Shanghai Hong Yun experimental equipmentfactory China) at a temperature of 100∘C for 24 h to removeinternal moisture Then two of the samples were put intoprogrammable constant temperature and humidity testers(PCTHC) for 24 hThe temperature of the PCTHC was set at20∘C and the humiditywas set at 30plusmn5 50plusmn5 65plusmn5 and80 plusmn 5 to achieve different initial moisture contents amongthe samples The humidity allowed moisture to be wickedinto layered samples and held in the fiber pores [14] leadingto an increase in moisture content The moisture weight ineach fiber layer was determined after the sample was placed
into different relative humidity situations using an electronicbalance with an accuracy of 0001 g over threemeasurements
The thermocouples usedwere identical to those describedin He et alrsquos paper [13] and we named them thermocoupleat the outer shell layer (TCO) thermocouple at the moisturebarrier layer (TCM) thermocouple at the thermal linerlayer (TCH) thermocouple at the comfort layer (TCC) andthermocouple at the wearer skin surface (TCW) as shownin Figure 2 The samples were fixed in the test chamberusing a sample holder on the sample trolley According toLawsonrsquos report [15] the radiation intensity on the corridorfloor decreases as the distance from the fire source increasesand the radiation intensity is about 18minus10 kWmminus2 In thisexperiment the radiation intensity was set at a constant valueof 5 kWmminus2 We measured the temperature at the outersurface of the outer shell layer which increased graduallyThe radiation source was turned off after 120 sec because theFPC material began combustion and totally lost its thermalinsulation performance after 120 sec under 10 kWmminus2
3 Theoretical Models
This study developed a model for coupled heat and mois-ture transmission in FPC materials during the radiationheating process The effects of both initial moisture content
The Scientific World Journal 3
Radi
atio
n so
urce
Out
er sh
ell
Moi
sture
bar
rier l
ayer
Ther
mal
line
r lay
er
Com
fort
laye
r
Epi
derm
is
Der
mis
Subc
utan
eous
0Thickness
Basal layer TCOTCMTCHTCC
Figure 3 Sketch of heat and moisture transfer in FPC materials and heat transport in human skin
as determined by RH and the temperature of the storageenvironment on the FPC samplesrsquo insulation performancewere investigated The burn injury times for human skinunder different conditions were also determined Figure 3shows a sketch of heat andmoisture transfer in FPCmaterialsas well as heat transfer through human skin The structureandmaterials of each layer were simulated in the experimentIn practice air gaps (AG) exist between each fabric layer ofFPC material because the four fabric layers are separated bya small amount of spaceTherefore our computer simulationincorporated an AG of 05mm between each fabric layerThere is also an air gap between the comfort layer and thewearerrsquos skin which has a thickness of 1mm The humanskin consists of three layers from outermost to innermostepidermis dermis and subcutaneous
We based our simulation model on Chitrphiromsrirsquosmodel [10 16 17] which can simulate heat and moisturetransfer in multilayer fabricThis simulation is built upon theequations for mass momentum and energy conservationThe conservation equations in each fabric layer are as follows
Energy equation is as follows
(120588119888119901)eff120597119879120597119905 + (120588119888119901)119897 V119897
120597119879120597119909
= 120597120597119909 (119896eff 120597119879120597119909) + Δℎvap (V119897 + V119887)+ Δℎtrans (119897119887 + V119887) + 120574 119902rad119890minus120574119909 + 119894119894
(1)
Mass equations are as follows
solid 120597120597119905 (120588119887120576119887) = V119887 + 119897119887
liquid 120597120597119905 (120588119897120576119897) +
120597120597119909 (120588119897V119897) = V119897 minus 119897119887
gas 120597120597119905 (120588V120576119892) = 120597
120597119909 (119863eff120597120588V120597119909 ) minus V119897 minus V119887
(2)
Momentum equation for liquid water is as follows
V119897 = minus119904 sdot 119870119897120583119897
120597120597119909 (119875119888) (3)
In (1) 119894119894 is the radiation heat flux between each fabriclayer defined as follows
119894119894 = 120574 119902minus119894119894119890minus120574(119909minussum119894119894minus1
0119871 119894 119894) + 120574 119902+119894119894119890minus120574(sum
119894119894
0119871 119894 119894minus119909)
119894119894 = 1 2 3 4(4)
where 119894119894 is the layer number For example 119894119894 = 1 representsthe outer shell layer so 119902minus119894119894 and 119902+119894119894 are the heat flux on the backand front surfaces respectively In this case
119902minus119894119894 = 120575120576 (1198794119894119894minus1 minus 1198794119894119894) 119894119894 = 1 2 3 4119902+119894119894 = 120575120576 (1198794119894119894 minus 1198794119894119894+1) 119894119894 = 1 2 3 4
(5)
The conservation equations for each air gap are as follows
Energy equation is as follows
(120588119888119901)eff120597119879120597119905 = 120597
120597119909 (119896eff 120597119879120597119909) + ΔℎvapV119897 (6)
Mass equation is as follows
120597120597119905 (120588V) =
120597120597119909 (119863eff
120597120588V120597119909 ) minus V119897 (7)
The heat transfer in each skin layer was estimated usingPennesrsquo model as follows [18]
(120588119862119875)skin 120597119879120597119905 = nabla (119896skinnabla119879)
+ (120588119862119901)blood 119908119887 (119879art minus 119879) (8)
4 The Scientific World Journal
05 10 15 20 25 30 35
Distance (times10minus3 m)
10minus310minus2 10minus4
10minus5
30
40
50
60
70
80
90
100Te
mpe
ratu
re (∘
C)
(a) Results of time independence test
0 20 40 60 80 100 120
Time (s)
40
60
80
100
120
140
160
180
Tem
pera
ture
(∘C)
10minus3
10minus410minus5
10minus6
(b) Results of grid step independence test
Figure 4 Temperature distributions for time and grid independence tests
Initial conditions are as follows119879 (119909 0) = 293119870120588V (119909 0) = 120588V0120576119897 (119909 0) = 1205761198970120576119887 (119909 0) = 1205761198870V119897 (119909 0) = V1198970
(9)
Boundary conditions for the fabric are as follows
119879|119909=0 = minus345713119890minus119905391541 + 6582739minus119863eff
120597120588V120597119909
10038161003816100381610038161003816100381610038161003816119909=0 = ℎ119898amb (120588Vamb minus 120588V|119909=0) V1198971003816100381610038161003816119909=0 = 0
1205761198971003816100381610038161003816119909=0 = 120576119897left1205761198871003816100381610038161003816119909=0 = 0119879|119909=119871 = 40∘C120588V1003816100381610038161003816119909=119871 = 0V1198971003816100381610038161003816119909=119871 = 0
1205761198971003816100381610038161003816119909=119871 = 01205761198871003816100381610038161003816119909=119871 = 0
(10)
The temperature of the boundary conditions for the fabricis the fitting curve of the average temperature asmeasured bythe thermocouples under radiation of 5 kwmminus2
We used Henriquesrsquo tissue burn injury model [19] todetermine the thermal damage to human skin under the radi-ation heating processThe thermal damage ratewas estimatedusing the first-order Arrhenius rate equation Human skinsustains a burn injury when the temperature of the basal layer(see Figure 3) rises above 44∘C In this case
119889Ω119889119905 =
0 119879 lt 44∘C119875 exp (minusΔ119864
119877119879) 119879 ge 44∘C (11)
Equation (11) can be expressed as an integral equationnamely
Ω = int119905119900119875 exp(minusΔ119864
119877119879)119889119905 (12)
In this work differential equations (1)-(2) and (6)ndash(8)were solved using the finite volume method and time-stepping was carried out according to the well-knownCrank-Nicholson method [20] This process yielded a system ofnonlinear algebraic equations which was resolved by thegoal chasing method The conductivity and diffusivity onthe interface between the air gap and the fabric layer wereestimated using the harmonic mean The under relaxationprocedure with a parameter of 06 was utilized to preventdivergence of the iteration method The iterations wererepeated until the changes in the solutions became smallerthan 10minus6
Time and step independence are illustrated graphicallyin Figure 4 Figure 4(a) shows the temperature distributionin the fabric layers at 10 sec and Figure 4(b) shows thetemperature distribution at the mid thickness of the fabriclayers The data show that after a 10minus3 time step the resultsdo not change significantly CPU time increases from about600 sec to 3600 sec in an Intel i7-2600 processor when
The Scientific World Journal 5
450
400
350
300
250
200
150
100
50
Tem
pera
ture
(∘C)
0 20 40 60 80 100 120
Time (s)
TCONo1TCMNo1TCHNo1TCCNo1TCWNo1
TCONo2TCMNo2TCHNo2
TCWNo2TCCNo2
Figure 5 Temperature change with time at different locations
the time step increases from 10minus3 to 10minus5 The temperaturedistribution when the grid size exceeds 10minus4m is muchdifferent from that when the grid size is smaller than 10minus5mThe maximum temperature difference using a grid size of10minus5m and 10minus6m is about 6∘C CPU time increases fromabout 3600 sec to 21600 sec in an Intel i7-2600 processorwhen the grid step decreases from 10minus3 to 10minus6 To summarizethe time and space step are 10minus3 sec and 10minus5m respectively
4 Results and Discussion
41 Experimental Results To ensure the accuracy of theexperimental results we first analyzed experimental re-peatability The radiation intensity of the experiment was5 kWmminus2 The sample was dry the AG thickness betweenthe back surface of the fabric layer and human skin was zeroOther conditions were set as described above The results areshown in Figure 5Thedata demonstrate that the repeatabilityof experiment results is good
In the simulation the temperature measured at the outersurface and at the back surface of the fabric layer undera radiation intensity of 5 kWmminus2 was set as the T0 and119879119871 boundary temperatures respectively The temperatureequation was obtained by liner fitting using Origin softwareas seen in Figure 6
42 Simulation Results The thermal physical properties ofthe fabric samples used in the simulations can be reviewedin Chitrphiromsri et al [17 21] The parameters for specificheat capacity viscosity density and thermal conductivity ofair at different temperatures are in Taorsquos paper [22] Table 1shows the thermophysical and geometrical properties of thefabric and Table 2 provides the properties of human skinTheparameters of the Henriques equations were set identically to
0 20 40 60 80 100 120
Time (s)
50
100
150
200
250
300
350
400
Tem
pera
ture
(∘C)
TLTR
TL fittingTR fitting
Figure 6 Temperature profiles at outer surface and back surfaceof fabric layer The fitting equations for 119879119871 and 119879119877 are 119879119871 =minus345713 exp(minus119905391541) + 6582739 and 119879119877 = 31196812 +164134119905 minus 0077611199052 minus 0077611199053 + 0002031199054 minus 197183 times 10minus5 +646652 times 10minus81199055
Moi
sture
cont
ent (times10
minus3
kg)
20
16
12
08
04
000 10 20 30 40 50 60 70 80
RH ()
Outer shellMoisture barrier
Thermal barrierTotal
Figure 7Moisture weight in each fiber layer against RHwith fittingline
those in Liu et alrsquos paper [23] The thickness of each samplewas determined by measuring with a caliper three timesTheinitial moisture content is shown in Figure 7
The correlation coefficients of the fitting lines for theexperimental data describing the outer shell moisture bar-rier thermal linear and total multilayer material are 099205097086 099226 and 099700 respectively These resultsdemonstrate that the moisture weight in each layer as wellas the total moisture weight increases linearly with settledenvironmental RH as expected The moisture absorbed bywicking into the thermal barrier is about four times that inthe outer shell layer and two times that in themoisture barrier
6 The Scientific World Journal
Table 1 Thermophysical and geometrical properties of fabric [17 21 22]
Property Outer shell Moisture barrier Thermal barrier Comfort layerThickness of the material119871119894119894 [m] 031 times 10minus3 05 times 10minus3 11 times 10minus3 029 times 10minus3
Material of composition XDB602 Aramid fabric coatedwith PTFE film Aramid insulation Cotton shirting
Density 120588119891 [kgmminus3] 67742 21000 7727 41379Thermal conductivity (119896)119891[Wmminus1 Kminus1]
0075 0052 005 0053
Volume fraction 120576119891 0334 0186 0115 015Fibre curl 120591 15 125 1 1Diffusivity of the gas phasein the fabric119863119891 [m2 secminus1] 0 times 10minus14 0 times 10minus14 0 times 10minus14 0 times 10minus14
Fiber radius 119889119891 [m] 16 times 10minus5 16 times 10minus5 16 times 10minus5 16 times 10minus5
Darcian permeabilitycoefficient m2119870119897sat [m2] 10 times 10minus16 10 times 10minus16 10 times 10minus16 10 times 10minus16
Saturation of the fabric 119904119894119903 01 01 01 01Proportional constant ofliquid water absorption 120574119897119904[kgmminus3]
0 times 10minus4 0 times 10minus4 0 times 10minus4 0 times 10minus4
Table 2 Thermophysical and geometrical properties assigned to skin layers [14 15 25ndash28]
Property Epidermis Dermis Subcutaneous tissue BloodDensity 120588skin [kgmminus3] 1200 1200 1000 1060Thermal conductivity(119896)skin [Wmminus1 ∘Cminus1] 023 045 019 mdash
119871 skin [m] 008 times 10minus3 2 times 10minus3 10 times 10minus3 mdash119888119901skin [J kgminus1 ∘Cminus1] 3600 3300 2300 3770120596119887 [m3 secminus1mminus3 tissue] 0 000125 000125 mdash
layer The samples also felt obviously moist when touchedafter remaining for 24 h in circumstances with RH valuesexceeding 65
We designed an apparatus to simulate the process of heattransfer in FPC samples with different initial moisture con-tentsThe experimental setup and the samples were describedin Section 2 To ensure simulation accuracy we comparedthe simulation results with the experimental measurementswhich were corrected before analysis for radiation lossThe comparison model did not consider human skin Theboundary conditions were set identically to the experimentalmeasurements Figure 8 shows the simulated (continuouslines) and experimental (discrete points) temperature profilesat RH = 65 In the figure TCO TCM TCH and TCCrepresent the measurement results at different locations (asseen in Figure 3) while labels preceded by ldquo119878rdquo representthe simulation results The data show that the simulationresults are in good agreement with the experimental resultsThe mechanism for heat and moisture transfer in a systemconsisting of FPC materials air layers and human skinwith different initial moisture content conditions were thenanalyzed using the validated model combined with Pennesrsquo
model The first and second human injury burn times wereestimated using the Henriquesrsquo tissue burn injury model
Figure 9 shows the temperature profiles in different layersat particular moments in time The origin of the 119909-axis isat the outer shell surface as shown in Figure 3 Figure 9(a)shows that the temperatures in the fabric layers decreasesignificantly with distance at different moments in time buttemperatures decrease slowly in the skin layer A clean breakis identifiable between the fabric layer and the skin layerThismay be because heat transfer in fabric layers occurs throughheat conduction radiation and water evaporation and heatabsorption while the only heat transfer model in the skinlayer is heat conduction The temperature difference in skinunder different initial moisture contents is larger at 100 secthan at 10 sec as shown in Figure 9(b) This is because lessinitial moisture content in the samples leads to more heataccumulated in the fabric and the air gap during radiation
We then analyzed the temperature differences underdifferent initial moisture conditions in the fabric and skinlayers with the results shown in Figures 9(c) and 9(d) Thetemperature difference in the fabric under different initialmoisture contents is higher at 10 s than at 100 s These results
The Scientific World Journal 7
0 20 40 60 80 100 120
Time (s)
Tem
pera
ture
(∘C)
400
350
300
250
200
150
100
50
0
Test-TCOTest-TCMTest-TCHTest-TCC
Simulation-TCOSimulation-TCMSimulation-TCHSimulation-TCC
(a) Temperature versus time
00 05 10 15 25 25 30 35 40
Thickness (times10minus3 m)
400
360
280
200
240
320
120
160
80
40
0
Tem
pera
ture
(∘C)
Test-10 secTest-20 secTest-40 secTest-60 secTest-80 secTest-100 secTest-120 sec
Simulation-20 secSimulation-10 sec
Simulation-40 secSimulation-60 secSimulation-80 secSimulation-100 secSimulation-120 sec
(b) Temperature versus thickness
Figure 8 Simulated (continuous lines) and experimental (discrete points) temperature profiles when RH = 65
are in agreement with the accepted point of view that theinitial moisture content of a sample affects heat transfer inthe fabric primarily at the beginning of heating The humanskin begins at 000388m The skin surface temperatureincreases from 309∘C at 10 sec to around 324∘C at 100 secunder different initial moisture contents The skin temper-ature increases as the initial moisture content of the fabricdecreases
Figure 10 shows the profiles for water vapor density in thefabric and air gap layers at different times The data indicatethat the water vapor density decreases as distance from theouter surface increases this occurs because the water vapordensity decreases with temperature which decreases withdistance Higher temperatures providemore energy for waterevaporation The maximum water vapor density in eachlayer increases very rapidly with t reaching a maximum atabout 20 sec under the conditions outlined in this paper asshown in Figure 11 The curve follows a normal distributionbetween about 10 sec and 35 sec After 35 sec the water vapordensity decreases more slowly with time In other words theactuation duration of the initial moisture of FPC samples wasless than 35 sec in this experimental situation
In our experiment the temperature increased whenthe outer shell of the FPC sample was exposed to heatradiation which caused the desorption and evaporationof bound water as well as the evaporation of free liquidwater located in the fabric pores To examine further themechanism of moisture transformation during heating weanalyzed the liquid water volume fraction in the fabricpores at different times as shown in Figure 12 The datashow that the distribution of liquid water in the fabric
unlike that of water vapor is completely noncontinuous Theinitial liquid water volume fraction in each fabric layer isuniform and it increases noticeably with increasing initialmoisture content As the temperature increases the liquidwater volume fraction decreases and the water vapor densityincreases
Figure 13 plots the heat absorbed by water evaporationagainst RH with a fitting line According to the conser-vation equations moisture in the fabric consists of boundliquid and gaseous water Under high temperatures thebound water transfers to a liquid state and the liquid waterevaporates to a gaseous state The enthalpy of the transitionfrom bound water to free liquid water is about 2509 J gminus1under relative humidity of 65 The enthalpy of evaporationper unit mass is about 2400 J gminus1 The bound water andliquid water volume fractions in each fabric layer can bederived from the simulationThen the heat absorbed throughwater evaporation can be determined based on differentinitial moisture conditions as shown in Figure 13 The datademonstrate that the heat absorbed by water evaporationincreases linearly with increasing RH
Figure 12 shows that the time required for the moistureto evaporate completely is about 70 s The heat flux on thematerial surface is 5 kWmminus2 and the dimension of thesample is 230 cm times 230 cmThe total quantity of heat appliedto the surface of the material is about 18515 J Figure 13 showsthat at the RH level of 80 the heat absorbed through waterevaporation is about 2000 J which constitutesmore than 10of the total heat
We also investigated the effect of the initial fabric mois-ture content on the maximum duration of heat radiation
8 The Scientific World Journal
350
300
250
200
150
100
50
0
Tem
pera
ture
(∘C)
100 sec
50 sec
10 sec
0 1 2 3 4 5
Distance (times10minus3 m)
Fabric layer Skin layer
HR = 30 10 secHR = 65 10 secHR = 30 50 secHR = 65 50 sec
HR = 50 10 secHR = 80 10 secHR = 50 50 secHR = 80 50 sec
HR = 30 100 secHR = 65 100 sec
HR = 50 100 secHR = 80 100 sec
(a) Temperature profile in both fabric and skin layers
100 sec
50 sec
10 sec
Fabric layerSkin layer
Distance (times10minus3 m)385 390 395
40
50
60
Tem
pera
ture
(∘C)
HR = 30 10 secHR = 65 10 secHR = 30 50 secHR = 65 50 sec
HR = 50 10 secHR = 80 10 secHR = 50 50 secHR = 80 50 sec
HR = 30 100 secHR = 65 100 sec
HR = 50 100 secHR = 80 100 sec
(b) Temperature profile at fabric-skin interface
00 05 10 15 20 25 30 35
HR = 30HR = 50
HR = 65HR = 80
100 sec
10 sec
Distance (times10minus3 m)
30
40
50
60
70
80
90
100
110
Tem
pera
ture
(∘C)
50
100
150
200
250
300
Tem
pera
ture
(∘C)
(c) Temperature profile in fabric
400 425 450 475 500 525 550 575
HR = 30HR = 50
HR = 65HR = 80
Distance (times10minus3 m)
100 sec
50 sec
10 sec
32
36
40
44
48
52
56
Tem
pera
ture
(∘C)
(d) Temperature profile in skin
Figure 9 Temperature profiles in different layers at specific moments in time
before the wearer sustains first- and second-degree burninjuries The tissue burn injury model is based on work byHenriques [19] and it is calculated according to (11) Takatarsquos[24] criterion was used to determine that first- and second-degree burn injuries occur whenΩ = 053 and 1 respectivelyon the basal layer of the skin (the interface of the epidermisand dermis) Figure 14 shows human skin burn injury timeversus RH The data show that as the initial moisturecontent in the fabric increases the maximum duration ofheat radiation before acquiring first- and second-degree burninjuries increases linearly This occurs because higher initialmoisture in fabric pores allows more energy to be absorbed
by water phase transfers during the heating process Thefirst- and second-degree burn injury time increases 16 secand 18 sec when the RH increases from 0 to 90 Theheat absorbed through water evaporation is 10 of thetotal quantity of heat applied to the surface of the materialHowever the comfort of clothing is usually very low whenthe clothing is set at the environment in which the RH ismore than 80 Therefore the RH is usually less than 80The temperature at the skin surface at different moment isshown in Figure 15We can see that the temperature decreaseswith increasing the initial moisture content The maximumtemperature difference between the RH of 30 and 80
The Scientific World Journal 9
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
120 sec
006
005
004
003
002
001
00000 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec21 sec32 sec50 sec
16 sec25 sec35 sec80 sec
20 sec30 sec40 sec
(a) RH = 30
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
009
008
007
006
005
004
003
002
001
00000 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec20 sec32 sec50 sec
10 sec25 sec35 sec80 sec
16 sec
120 sec
30 sec40 sec
(b) RH = 50
012
010
008
006
004
002
000
OSAL
MB
AL
TB
AL
CL AL휌
(kg
mminus3)
00 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec11 sec15 sec30 sec
5 sec12 sec16 sec50 sec
10 sec13 sec20 sec120 sec
(c) RH = 65
012
010
008
006
004
002
000
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
00 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec21 sec32 sec50 sec
16 sec25 sec35 sec80 sec
20 sec30 sec40 sec
(d) RH = 80
Figure 10 Distributions of water vapor density at different times
condition is about 1 K which is really slight But the effect ofenergy on the skin injury is an accumulation behavior whichleads to the second-degree burn injury time increasing about8 sec
5 Conclusion
We developed a numerical model to investigate the effectsof initial moisture content at each fabric layer on heat andmoisture transfer in FPCmaterialsWe estimated burn injurytimes under different initial moisture contents using our
model combined with Pennesrsquo model and Henriquesrsquo tissueburn injury model We can draw the following conclusions
(1) Initial moisture content in each FPC fabric layerincreases linearly as the RH of the storage locationincreases
(2) We developed a comprehensive model to simulateheat andmoisture transfer in FPC and the simulationresults show fairly good agreement with the experi-mental results
10 The Scientific World Journal
024
022
020
018
016
014
012
010
008
006
004
002
0000 20 40 60 80 100 120
Time (s)
HR = 30HR = 50
HR = 65HR = 80
휌
(kg
mminus3)
Figure 11 Profiles of water vapor density versus time at a distance of 056 times 10minus3m
(3) Water vapor is distributed both in the fabric layersand in the air layer while free liquid water dispersesonly in the fabric layers Water vapor density ismainly due to evaporation from free liquid waterduring the experiment and it decreases as initialmoisture content increases The total amount of heatabsorption attributable to water evaporation is about10 when the RH is 80
(4) A linear relationship exists between the initial mois-ture content and the maximum duration of heatradiation before causing first- and second-degreeburn injuries
Symbols
119888119901 Specific heat at constant pressureJ kgminus1 ∘Cminus1119863 Diffusivity of the gas phase in the fabricm2 secminus1
119889119891 Fiber radius mℎ119898 Convective heat transfer coefficient
Wmminus2 ∘Cminus1
Δℎ Enthalpy per unit mass J kgminus1119894119894 Fabric layer119896 Thermal conductivity Wmminus1 ∘Cminus1
119870 Darcian permeability coefficient m2119871 Thickness of the material mV119897 Mass transfer rate from the gaseous phase
to the liquid phase kgmminus3 secminus1V119887 Mass transfer rate from the gaseous phase
to the solid phase kgmminus3 secminus1119897119887 Mass transfer rate from the liquid phase to
the solid phase kgmminus3 secminus1119875119888 Pressure of liquid water Pa
119902rad Incident radiation heat flux from theradiation onto the outer fabric surfaceWmminus2119902minus119894119894 Radiation heat flux from the 119894119894 + 1 fabriclayer to the 119894119894 fabric layer Wmminus2119902+119894119894 Radiation heat flux from the 119894119894 minus 1 fabriclayer to the 119894119894 fabric layer Wmminus2
119894119894 Total radiation heat flux of the 119894119894 fabriclayer Wmminus2
119904 Saturation of the fabric119905 Time s119879 Temperature ∘CV Velocity of liquid water m secminus1119909 Distance m
Greek Symbols
120591 Transmissivity of the fabric120591 Fiber curl120588 Density kgmminus3120576 Absorption coefficient120576119887 Volume fraction120574 Radiative extinction coefficient of the
fabric mminus1120583119897 Dynamic viscosity kgmminus1 secminus1120590 Stefan-Boltzmann constant
120575 = 56705 times 10minus8W ∘Cminus4mminus2120596119887 Blood perfusion [000125m3 secminus1mminus3
tissue]Ω Quantitative measure of the burn damage
at the basal layer of human skin119875 Frequency factor or preexponential factor
secminus1Δ119864 Activation energy for skin119877 Universal gas constant
8315 times 103 J kmolminus1 ∘Cminus1
The Scientific World Journal 11
0007
0006
0005
0004
0003
0002
0001
휀l
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
20 sec25 sec30 sec35 sec40 sec
45 sec50 sec55 sec60 sec70 sec
(a) RH = 30
0007
0006
0005
0004
0003
0002
0001
휀l
0012
0011
0010
0009
0008
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
15 sec18 sec20 sec25 sec30 sec
35 sec40 sec50 sec60 sec70 sec
(b) RH = 50
휀l
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(c) RH = 65
휀l
0018
0016
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(d) RH = 80
Figure 12 Liquid water volume fraction distributions at different times
Subscripts
0 Initial stateeff Effective119897 Liquid water119887 Bound waterV Water vaporskin Skinblood Bloodamb Ambient air
vap Evaporationtrans Transferart Human core119871 Left boundary119877 Right boundary
Conflicts of Interest
The authors declare that they have no conflicts of interest
12 The Scientific World JournalH
eat a
bsor
bed
wat
er ev
apor
atio
n (J
)
3000
2500
2000
1500
1000
500
030 40 50 60 70 80
RH ()
Outer shellMoisture barrier
Thermal barrierTotal
Figure 13 Heat absorbed by water evaporation against RH withfitting line
First-degree burn injury timeSecond-degree burn injury time
Burn
inju
ry ti
me (
s)
136
132
128
124
120
116
112
RH ()minus10 0 10 20 30 40 50 60 70 80 90 100
Figure 14 Burning injury time versus RH
Authorsrsquo Contributions
Dongmei Huang carried out the experiment and numericalsimulation and drafted and revised the manuscript Song Heparticipated in the design of the study and performed thestatistical analysis and helped to draft the manuscript Allauthors read and approved the final manuscript
Acknowledgments
This work was supported by Natural Science Foundationof China (no 51306168) and Zhejiang Provincial NaturalScience Foundation of China under Grant no LY17E060004
Tem
pera
ture
(∘C)
Tem
pera
ture
(∘C)
52
51
50
49
48
47
46
45
44
43
42
41
RH ()20 30 40 50 60 70 80 90
360
359
358
357
356
355
354
353
352
351
350
100 sec50 sec10 sec
Figure 15 Temperature at skin surface
References
[1] L D Xu Y L Xy and M Jiang ldquoProtective clothing for fire-fighter GA10-2014rdquo in GA10-2002 China Standards PressBeijing China 2002
[2] D Huang H Yang Z Qi et al ldquoQuestionnaire on firefightersrsquoprotective clothing in Chinardquo Fire Technology vol 48 no 2 pp255ndash268 2012
[3] C C Guerth-Schacher Evaluation of the Effects of Moisture onthe Thermal Protective Performance of Fire Protective Clothingin Low Level Heat Exposures Fire and Polymer Science NorthCarolina State University Raleigh NC USA 2007
[4] R L Barker C Guerth-Schacher R V Grimes and H Hamou-da ldquoEffects of moisture on the thermal protective performanceof firefighter protective clothing in low-level radiant heatexposuresrdquo Textile Research Journal vol 76 no 1 pp 27ndash312006
[5] Y M Lee and R L Barker ldquoEffect of moisture on the thermalprotective performance of heat-resistant fabricsrdquo Journal of FireSciences vol 4 no 5 pp 315ndash331 1986
[6] J O Stull ldquoThe effect of moisture on firefighter protectiveclothing thermal insulation a review of industry researchrdquoin Performance of Protective Clothing Issues and Priorities forthe 21st Century vol 7th ASTM International West Con-shohocken Pa USA 2000
[7] C Keiser C Becker and R M Rossi ldquoMoisture transport andabsorption in multilayer protective clothing fabricsrdquo TextileResearch Journal vol 78 no 7 pp 604ndash613 2008
[8] Y Y Wang Y J Zong J Li and M M Zhao ldquoEvaluating themoisture transfer property of the multi-layered fabric system infirefighter turnout clothingrdquo Fibres amp Textiles in Eastern Europevol 19 no 6 article 89 pp 101ndash105 2011
[9] Y-Y Wang Y-H Lu J Li and J-H Pan ldquoEffects of airgap entrapped in multilayer fabrics and moisture on thermalprotective performancerdquo Fibers and Polymers vol 13 no 5 pp647ndash652 2012
[10] P Chitrphiromsri and A V Kuznetsov ldquoModeling heat andmoisture transport in firefighter protective clothing during flashfire exposurerdquo Heat and Mass Transfer vol 41 no 3 pp 206ndash215 2005
The Scientific World Journal 13
[11] J Fan X Cheng X Wen and W Sun ldquoAn improved modelof heat and moisture transfer with phase change and mobilecondensates in fibrous insulation and comparison with experi-mental resultsrdquo International Journal of Heat andMass Transfervol 47 no 10-11 pp 2343ndash2352 2004
[12] X Cheng and J Fan ldquoSimulation of heat and moisture transferwith phase change and mobile condensates in fibrous insula-tionrdquo International Journal of Thermal Sciences vol 43 no 7pp 665ndash676 2004
[13] SHeDHuang ZQiH Yang YHu andHZhang ldquoThe effectof air gap thickness on heat transfer in firefightersrsquo protectiveclothing under conditions of short exposure to heatrdquo HeatTransfer Research vol 43 no 8 pp 749ndash765 2012
[14] P Andersson and G Holmstedt ldquoHeat sensing manikin testproberdquo Fire and Materials vol 24 no 4 pp 195ndash199 2000
[15] J R Lawson Fire Fighterrsquos Protective Clothing and ThermalEnvironments of Structural Fire Fighting US Department ofCommerce Technology Administration National Institute ofStandards and Technology 1996
[16] P Chitrphiromsri and A V Kuznetsov ldquoPorous mediummodelfor investigating transient heat and moisture transport infirefighter protective clothing under high-intensity thermalexposurerdquo Journal of Porous Media vol 8 no 5 pp 511ndash5282005
[17] P Chitrphiromsri Modeling of Thermal Performance of Fire-fighter Protective Clothing during the Intense Heat ExposureNorth Carolina State University Raleigh NC USA 2004
[18] H P Harry ldquoAnalysis of tissue and arterial blood temperaturesin the resting human forearmrdquo Journal of Applied Physiologyvol 1 no 2 pp 93ndash122 1948
[19] F C Henriques ldquoStudies of thermal injury the predictabilityand the significance of thermally induced rate processes leadingto irreversible epidermal injuryrdquo Archives of pathology vol 43no 5 pp 489ndash502 1947
[20] S A Teukolsky ldquoStability of the iterated Crank-Nicholsonmethod in numerical relativityrdquo Physical Review DmdashParticlesFields Gravitation and Cosmology vol 61 no 8 Article ID087501 2000
[21] F-L Zhu and W-Y Zhang ldquoModeling heat transfer for heat-resistant fabrics considering pyrolysis effect under an externalheat fluxrdquo Journal of Fire Sciences vol 27 no 1 pp 81ndash96 2009
[22] W Q Tao Heat Transfer Northwestern Polytechnical Univer-sity Press Xirsquoan China 2006
[23] J Liu X Chen andL X Xu ldquoNew thermalwave aspects on bumevaluation of skin subjected to instantaneous heatingrdquo IEEETransactions on Biomedical Engineering vol 46 no 4 pp 420ndash428 1999
[24] A N Takata ldquoDevelopment of criterion for skin burnsrdquo Aero-space Medicine vol 45 no 6 pp 634ndash637 1974
[25] T R Gowrishankar D A Stewart G T Martin and J CWeaver ldquoTransport lattice models of heat transport in skinwith spatially heterogeneous temperature-dependent perfu-sionrdquo BioMedical Engineering Online vol 3 article no 42 2004
[26] D A Torvi and J D Dale ldquoA finite element model of skinsubjected to a flash firerdquo Journal of Biomechanical Engineeringvol 116 no 3 pp 250ndash255 1994
[27] A M Stoll and L C Greene ldquoRelationship between pain andtissue damage due to thermal radiationrdquo Journal of AppliedPhysiology vol 14 no 3 pp 373ndash382 1959
[28] MGasperin andD Juricic ldquoThe uncertainty in burn predictionas a result of variable skin parameters an experimental evalu-ation of burn-protective outfitsrdquo Burns vol 35 no 7 pp 970ndash982 2009
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Submit your manuscripts athttpswwwhindawicom
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Volume 201Hindawi Publishing Corporation httpwwwhindawicom Volume 201
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The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
The Scientific World Journal 3
Radi
atio
n so
urce
Out
er sh
ell
Moi
sture
bar
rier l
ayer
Ther
mal
line
r lay
er
Com
fort
laye
r
Epi
derm
is
Der
mis
Subc
utan
eous
0Thickness
Basal layer TCOTCMTCHTCC
Figure 3 Sketch of heat and moisture transfer in FPC materials and heat transport in human skin
as determined by RH and the temperature of the storageenvironment on the FPC samplesrsquo insulation performancewere investigated The burn injury times for human skinunder different conditions were also determined Figure 3shows a sketch of heat andmoisture transfer in FPCmaterialsas well as heat transfer through human skin The structureandmaterials of each layer were simulated in the experimentIn practice air gaps (AG) exist between each fabric layer ofFPC material because the four fabric layers are separated bya small amount of spaceTherefore our computer simulationincorporated an AG of 05mm between each fabric layerThere is also an air gap between the comfort layer and thewearerrsquos skin which has a thickness of 1mm The humanskin consists of three layers from outermost to innermostepidermis dermis and subcutaneous
We based our simulation model on Chitrphiromsrirsquosmodel [10 16 17] which can simulate heat and moisturetransfer in multilayer fabricThis simulation is built upon theequations for mass momentum and energy conservationThe conservation equations in each fabric layer are as follows
Energy equation is as follows
(120588119888119901)eff120597119879120597119905 + (120588119888119901)119897 V119897
120597119879120597119909
= 120597120597119909 (119896eff 120597119879120597119909) + Δℎvap (V119897 + V119887)+ Δℎtrans (119897119887 + V119887) + 120574 119902rad119890minus120574119909 + 119894119894
(1)
Mass equations are as follows
solid 120597120597119905 (120588119887120576119887) = V119887 + 119897119887
liquid 120597120597119905 (120588119897120576119897) +
120597120597119909 (120588119897V119897) = V119897 minus 119897119887
gas 120597120597119905 (120588V120576119892) = 120597
120597119909 (119863eff120597120588V120597119909 ) minus V119897 minus V119887
(2)
Momentum equation for liquid water is as follows
V119897 = minus119904 sdot 119870119897120583119897
120597120597119909 (119875119888) (3)
In (1) 119894119894 is the radiation heat flux between each fabriclayer defined as follows
119894119894 = 120574 119902minus119894119894119890minus120574(119909minussum119894119894minus1
0119871 119894 119894) + 120574 119902+119894119894119890minus120574(sum
119894119894
0119871 119894 119894minus119909)
119894119894 = 1 2 3 4(4)
where 119894119894 is the layer number For example 119894119894 = 1 representsthe outer shell layer so 119902minus119894119894 and 119902+119894119894 are the heat flux on the backand front surfaces respectively In this case
119902minus119894119894 = 120575120576 (1198794119894119894minus1 minus 1198794119894119894) 119894119894 = 1 2 3 4119902+119894119894 = 120575120576 (1198794119894119894 minus 1198794119894119894+1) 119894119894 = 1 2 3 4
(5)
The conservation equations for each air gap are as follows
Energy equation is as follows
(120588119888119901)eff120597119879120597119905 = 120597
120597119909 (119896eff 120597119879120597119909) + ΔℎvapV119897 (6)
Mass equation is as follows
120597120597119905 (120588V) =
120597120597119909 (119863eff
120597120588V120597119909 ) minus V119897 (7)
The heat transfer in each skin layer was estimated usingPennesrsquo model as follows [18]
(120588119862119875)skin 120597119879120597119905 = nabla (119896skinnabla119879)
+ (120588119862119901)blood 119908119887 (119879art minus 119879) (8)
4 The Scientific World Journal
05 10 15 20 25 30 35
Distance (times10minus3 m)
10minus310minus2 10minus4
10minus5
30
40
50
60
70
80
90
100Te
mpe
ratu
re (∘
C)
(a) Results of time independence test
0 20 40 60 80 100 120
Time (s)
40
60
80
100
120
140
160
180
Tem
pera
ture
(∘C)
10minus3
10minus410minus5
10minus6
(b) Results of grid step independence test
Figure 4 Temperature distributions for time and grid independence tests
Initial conditions are as follows119879 (119909 0) = 293119870120588V (119909 0) = 120588V0120576119897 (119909 0) = 1205761198970120576119887 (119909 0) = 1205761198870V119897 (119909 0) = V1198970
(9)
Boundary conditions for the fabric are as follows
119879|119909=0 = minus345713119890minus119905391541 + 6582739minus119863eff
120597120588V120597119909
10038161003816100381610038161003816100381610038161003816119909=0 = ℎ119898amb (120588Vamb minus 120588V|119909=0) V1198971003816100381610038161003816119909=0 = 0
1205761198971003816100381610038161003816119909=0 = 120576119897left1205761198871003816100381610038161003816119909=0 = 0119879|119909=119871 = 40∘C120588V1003816100381610038161003816119909=119871 = 0V1198971003816100381610038161003816119909=119871 = 0
1205761198971003816100381610038161003816119909=119871 = 01205761198871003816100381610038161003816119909=119871 = 0
(10)
The temperature of the boundary conditions for the fabricis the fitting curve of the average temperature asmeasured bythe thermocouples under radiation of 5 kwmminus2
We used Henriquesrsquo tissue burn injury model [19] todetermine the thermal damage to human skin under the radi-ation heating processThe thermal damage ratewas estimatedusing the first-order Arrhenius rate equation Human skinsustains a burn injury when the temperature of the basal layer(see Figure 3) rises above 44∘C In this case
119889Ω119889119905 =
0 119879 lt 44∘C119875 exp (minusΔ119864
119877119879) 119879 ge 44∘C (11)
Equation (11) can be expressed as an integral equationnamely
Ω = int119905119900119875 exp(minusΔ119864
119877119879)119889119905 (12)
In this work differential equations (1)-(2) and (6)ndash(8)were solved using the finite volume method and time-stepping was carried out according to the well-knownCrank-Nicholson method [20] This process yielded a system ofnonlinear algebraic equations which was resolved by thegoal chasing method The conductivity and diffusivity onthe interface between the air gap and the fabric layer wereestimated using the harmonic mean The under relaxationprocedure with a parameter of 06 was utilized to preventdivergence of the iteration method The iterations wererepeated until the changes in the solutions became smallerthan 10minus6
Time and step independence are illustrated graphicallyin Figure 4 Figure 4(a) shows the temperature distributionin the fabric layers at 10 sec and Figure 4(b) shows thetemperature distribution at the mid thickness of the fabriclayers The data show that after a 10minus3 time step the resultsdo not change significantly CPU time increases from about600 sec to 3600 sec in an Intel i7-2600 processor when
The Scientific World Journal 5
450
400
350
300
250
200
150
100
50
Tem
pera
ture
(∘C)
0 20 40 60 80 100 120
Time (s)
TCONo1TCMNo1TCHNo1TCCNo1TCWNo1
TCONo2TCMNo2TCHNo2
TCWNo2TCCNo2
Figure 5 Temperature change with time at different locations
the time step increases from 10minus3 to 10minus5 The temperaturedistribution when the grid size exceeds 10minus4m is muchdifferent from that when the grid size is smaller than 10minus5mThe maximum temperature difference using a grid size of10minus5m and 10minus6m is about 6∘C CPU time increases fromabout 3600 sec to 21600 sec in an Intel i7-2600 processorwhen the grid step decreases from 10minus3 to 10minus6 To summarizethe time and space step are 10minus3 sec and 10minus5m respectively
4 Results and Discussion
41 Experimental Results To ensure the accuracy of theexperimental results we first analyzed experimental re-peatability The radiation intensity of the experiment was5 kWmminus2 The sample was dry the AG thickness betweenthe back surface of the fabric layer and human skin was zeroOther conditions were set as described above The results areshown in Figure 5Thedata demonstrate that the repeatabilityof experiment results is good
In the simulation the temperature measured at the outersurface and at the back surface of the fabric layer undera radiation intensity of 5 kWmminus2 was set as the T0 and119879119871 boundary temperatures respectively The temperatureequation was obtained by liner fitting using Origin softwareas seen in Figure 6
42 Simulation Results The thermal physical properties ofthe fabric samples used in the simulations can be reviewedin Chitrphiromsri et al [17 21] The parameters for specificheat capacity viscosity density and thermal conductivity ofair at different temperatures are in Taorsquos paper [22] Table 1shows the thermophysical and geometrical properties of thefabric and Table 2 provides the properties of human skinTheparameters of the Henriques equations were set identically to
0 20 40 60 80 100 120
Time (s)
50
100
150
200
250
300
350
400
Tem
pera
ture
(∘C)
TLTR
TL fittingTR fitting
Figure 6 Temperature profiles at outer surface and back surfaceof fabric layer The fitting equations for 119879119871 and 119879119877 are 119879119871 =minus345713 exp(minus119905391541) + 6582739 and 119879119877 = 31196812 +164134119905 minus 0077611199052 minus 0077611199053 + 0002031199054 minus 197183 times 10minus5 +646652 times 10minus81199055
Moi
sture
cont
ent (times10
minus3
kg)
20
16
12
08
04
000 10 20 30 40 50 60 70 80
RH ()
Outer shellMoisture barrier
Thermal barrierTotal
Figure 7Moisture weight in each fiber layer against RHwith fittingline
those in Liu et alrsquos paper [23] The thickness of each samplewas determined by measuring with a caliper three timesTheinitial moisture content is shown in Figure 7
The correlation coefficients of the fitting lines for theexperimental data describing the outer shell moisture bar-rier thermal linear and total multilayer material are 099205097086 099226 and 099700 respectively These resultsdemonstrate that the moisture weight in each layer as wellas the total moisture weight increases linearly with settledenvironmental RH as expected The moisture absorbed bywicking into the thermal barrier is about four times that inthe outer shell layer and two times that in themoisture barrier
6 The Scientific World Journal
Table 1 Thermophysical and geometrical properties of fabric [17 21 22]
Property Outer shell Moisture barrier Thermal barrier Comfort layerThickness of the material119871119894119894 [m] 031 times 10minus3 05 times 10minus3 11 times 10minus3 029 times 10minus3
Material of composition XDB602 Aramid fabric coatedwith PTFE film Aramid insulation Cotton shirting
Density 120588119891 [kgmminus3] 67742 21000 7727 41379Thermal conductivity (119896)119891[Wmminus1 Kminus1]
0075 0052 005 0053
Volume fraction 120576119891 0334 0186 0115 015Fibre curl 120591 15 125 1 1Diffusivity of the gas phasein the fabric119863119891 [m2 secminus1] 0 times 10minus14 0 times 10minus14 0 times 10minus14 0 times 10minus14
Fiber radius 119889119891 [m] 16 times 10minus5 16 times 10minus5 16 times 10minus5 16 times 10minus5
Darcian permeabilitycoefficient m2119870119897sat [m2] 10 times 10minus16 10 times 10minus16 10 times 10minus16 10 times 10minus16
Saturation of the fabric 119904119894119903 01 01 01 01Proportional constant ofliquid water absorption 120574119897119904[kgmminus3]
0 times 10minus4 0 times 10minus4 0 times 10minus4 0 times 10minus4
Table 2 Thermophysical and geometrical properties assigned to skin layers [14 15 25ndash28]
Property Epidermis Dermis Subcutaneous tissue BloodDensity 120588skin [kgmminus3] 1200 1200 1000 1060Thermal conductivity(119896)skin [Wmminus1 ∘Cminus1] 023 045 019 mdash
119871 skin [m] 008 times 10minus3 2 times 10minus3 10 times 10minus3 mdash119888119901skin [J kgminus1 ∘Cminus1] 3600 3300 2300 3770120596119887 [m3 secminus1mminus3 tissue] 0 000125 000125 mdash
layer The samples also felt obviously moist when touchedafter remaining for 24 h in circumstances with RH valuesexceeding 65
We designed an apparatus to simulate the process of heattransfer in FPC samples with different initial moisture con-tentsThe experimental setup and the samples were describedin Section 2 To ensure simulation accuracy we comparedthe simulation results with the experimental measurementswhich were corrected before analysis for radiation lossThe comparison model did not consider human skin Theboundary conditions were set identically to the experimentalmeasurements Figure 8 shows the simulated (continuouslines) and experimental (discrete points) temperature profilesat RH = 65 In the figure TCO TCM TCH and TCCrepresent the measurement results at different locations (asseen in Figure 3) while labels preceded by ldquo119878rdquo representthe simulation results The data show that the simulationresults are in good agreement with the experimental resultsThe mechanism for heat and moisture transfer in a systemconsisting of FPC materials air layers and human skinwith different initial moisture content conditions were thenanalyzed using the validated model combined with Pennesrsquo
model The first and second human injury burn times wereestimated using the Henriquesrsquo tissue burn injury model
Figure 9 shows the temperature profiles in different layersat particular moments in time The origin of the 119909-axis isat the outer shell surface as shown in Figure 3 Figure 9(a)shows that the temperatures in the fabric layers decreasesignificantly with distance at different moments in time buttemperatures decrease slowly in the skin layer A clean breakis identifiable between the fabric layer and the skin layerThismay be because heat transfer in fabric layers occurs throughheat conduction radiation and water evaporation and heatabsorption while the only heat transfer model in the skinlayer is heat conduction The temperature difference in skinunder different initial moisture contents is larger at 100 secthan at 10 sec as shown in Figure 9(b) This is because lessinitial moisture content in the samples leads to more heataccumulated in the fabric and the air gap during radiation
We then analyzed the temperature differences underdifferent initial moisture conditions in the fabric and skinlayers with the results shown in Figures 9(c) and 9(d) Thetemperature difference in the fabric under different initialmoisture contents is higher at 10 s than at 100 s These results
The Scientific World Journal 7
0 20 40 60 80 100 120
Time (s)
Tem
pera
ture
(∘C)
400
350
300
250
200
150
100
50
0
Test-TCOTest-TCMTest-TCHTest-TCC
Simulation-TCOSimulation-TCMSimulation-TCHSimulation-TCC
(a) Temperature versus time
00 05 10 15 25 25 30 35 40
Thickness (times10minus3 m)
400
360
280
200
240
320
120
160
80
40
0
Tem
pera
ture
(∘C)
Test-10 secTest-20 secTest-40 secTest-60 secTest-80 secTest-100 secTest-120 sec
Simulation-20 secSimulation-10 sec
Simulation-40 secSimulation-60 secSimulation-80 secSimulation-100 secSimulation-120 sec
(b) Temperature versus thickness
Figure 8 Simulated (continuous lines) and experimental (discrete points) temperature profiles when RH = 65
are in agreement with the accepted point of view that theinitial moisture content of a sample affects heat transfer inthe fabric primarily at the beginning of heating The humanskin begins at 000388m The skin surface temperatureincreases from 309∘C at 10 sec to around 324∘C at 100 secunder different initial moisture contents The skin temper-ature increases as the initial moisture content of the fabricdecreases
Figure 10 shows the profiles for water vapor density in thefabric and air gap layers at different times The data indicatethat the water vapor density decreases as distance from theouter surface increases this occurs because the water vapordensity decreases with temperature which decreases withdistance Higher temperatures providemore energy for waterevaporation The maximum water vapor density in eachlayer increases very rapidly with t reaching a maximum atabout 20 sec under the conditions outlined in this paper asshown in Figure 11 The curve follows a normal distributionbetween about 10 sec and 35 sec After 35 sec the water vapordensity decreases more slowly with time In other words theactuation duration of the initial moisture of FPC samples wasless than 35 sec in this experimental situation
In our experiment the temperature increased whenthe outer shell of the FPC sample was exposed to heatradiation which caused the desorption and evaporationof bound water as well as the evaporation of free liquidwater located in the fabric pores To examine further themechanism of moisture transformation during heating weanalyzed the liquid water volume fraction in the fabricpores at different times as shown in Figure 12 The datashow that the distribution of liquid water in the fabric
unlike that of water vapor is completely noncontinuous Theinitial liquid water volume fraction in each fabric layer isuniform and it increases noticeably with increasing initialmoisture content As the temperature increases the liquidwater volume fraction decreases and the water vapor densityincreases
Figure 13 plots the heat absorbed by water evaporationagainst RH with a fitting line According to the conser-vation equations moisture in the fabric consists of boundliquid and gaseous water Under high temperatures thebound water transfers to a liquid state and the liquid waterevaporates to a gaseous state The enthalpy of the transitionfrom bound water to free liquid water is about 2509 J gminus1under relative humidity of 65 The enthalpy of evaporationper unit mass is about 2400 J gminus1 The bound water andliquid water volume fractions in each fabric layer can bederived from the simulationThen the heat absorbed throughwater evaporation can be determined based on differentinitial moisture conditions as shown in Figure 13 The datademonstrate that the heat absorbed by water evaporationincreases linearly with increasing RH
Figure 12 shows that the time required for the moistureto evaporate completely is about 70 s The heat flux on thematerial surface is 5 kWmminus2 and the dimension of thesample is 230 cm times 230 cmThe total quantity of heat appliedto the surface of the material is about 18515 J Figure 13 showsthat at the RH level of 80 the heat absorbed through waterevaporation is about 2000 J which constitutesmore than 10of the total heat
We also investigated the effect of the initial fabric mois-ture content on the maximum duration of heat radiation
8 The Scientific World Journal
350
300
250
200
150
100
50
0
Tem
pera
ture
(∘C)
100 sec
50 sec
10 sec
0 1 2 3 4 5
Distance (times10minus3 m)
Fabric layer Skin layer
HR = 30 10 secHR = 65 10 secHR = 30 50 secHR = 65 50 sec
HR = 50 10 secHR = 80 10 secHR = 50 50 secHR = 80 50 sec
HR = 30 100 secHR = 65 100 sec
HR = 50 100 secHR = 80 100 sec
(a) Temperature profile in both fabric and skin layers
100 sec
50 sec
10 sec
Fabric layerSkin layer
Distance (times10minus3 m)385 390 395
40
50
60
Tem
pera
ture
(∘C)
HR = 30 10 secHR = 65 10 secHR = 30 50 secHR = 65 50 sec
HR = 50 10 secHR = 80 10 secHR = 50 50 secHR = 80 50 sec
HR = 30 100 secHR = 65 100 sec
HR = 50 100 secHR = 80 100 sec
(b) Temperature profile at fabric-skin interface
00 05 10 15 20 25 30 35
HR = 30HR = 50
HR = 65HR = 80
100 sec
10 sec
Distance (times10minus3 m)
30
40
50
60
70
80
90
100
110
Tem
pera
ture
(∘C)
50
100
150
200
250
300
Tem
pera
ture
(∘C)
(c) Temperature profile in fabric
400 425 450 475 500 525 550 575
HR = 30HR = 50
HR = 65HR = 80
Distance (times10minus3 m)
100 sec
50 sec
10 sec
32
36
40
44
48
52
56
Tem
pera
ture
(∘C)
(d) Temperature profile in skin
Figure 9 Temperature profiles in different layers at specific moments in time
before the wearer sustains first- and second-degree burninjuries The tissue burn injury model is based on work byHenriques [19] and it is calculated according to (11) Takatarsquos[24] criterion was used to determine that first- and second-degree burn injuries occur whenΩ = 053 and 1 respectivelyon the basal layer of the skin (the interface of the epidermisand dermis) Figure 14 shows human skin burn injury timeversus RH The data show that as the initial moisturecontent in the fabric increases the maximum duration ofheat radiation before acquiring first- and second-degree burninjuries increases linearly This occurs because higher initialmoisture in fabric pores allows more energy to be absorbed
by water phase transfers during the heating process Thefirst- and second-degree burn injury time increases 16 secand 18 sec when the RH increases from 0 to 90 Theheat absorbed through water evaporation is 10 of thetotal quantity of heat applied to the surface of the materialHowever the comfort of clothing is usually very low whenthe clothing is set at the environment in which the RH ismore than 80 Therefore the RH is usually less than 80The temperature at the skin surface at different moment isshown in Figure 15We can see that the temperature decreaseswith increasing the initial moisture content The maximumtemperature difference between the RH of 30 and 80
The Scientific World Journal 9
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
120 sec
006
005
004
003
002
001
00000 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec21 sec32 sec50 sec
16 sec25 sec35 sec80 sec
20 sec30 sec40 sec
(a) RH = 30
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
009
008
007
006
005
004
003
002
001
00000 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec20 sec32 sec50 sec
10 sec25 sec35 sec80 sec
16 sec
120 sec
30 sec40 sec
(b) RH = 50
012
010
008
006
004
002
000
OSAL
MB
AL
TB
AL
CL AL휌
(kg
mminus3)
00 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec11 sec15 sec30 sec
5 sec12 sec16 sec50 sec
10 sec13 sec20 sec120 sec
(c) RH = 65
012
010
008
006
004
002
000
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
00 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec21 sec32 sec50 sec
16 sec25 sec35 sec80 sec
20 sec30 sec40 sec
(d) RH = 80
Figure 10 Distributions of water vapor density at different times
condition is about 1 K which is really slight But the effect ofenergy on the skin injury is an accumulation behavior whichleads to the second-degree burn injury time increasing about8 sec
5 Conclusion
We developed a numerical model to investigate the effectsof initial moisture content at each fabric layer on heat andmoisture transfer in FPCmaterialsWe estimated burn injurytimes under different initial moisture contents using our
model combined with Pennesrsquo model and Henriquesrsquo tissueburn injury model We can draw the following conclusions
(1) Initial moisture content in each FPC fabric layerincreases linearly as the RH of the storage locationincreases
(2) We developed a comprehensive model to simulateheat andmoisture transfer in FPC and the simulationresults show fairly good agreement with the experi-mental results
10 The Scientific World Journal
024
022
020
018
016
014
012
010
008
006
004
002
0000 20 40 60 80 100 120
Time (s)
HR = 30HR = 50
HR = 65HR = 80
휌
(kg
mminus3)
Figure 11 Profiles of water vapor density versus time at a distance of 056 times 10minus3m
(3) Water vapor is distributed both in the fabric layersand in the air layer while free liquid water dispersesonly in the fabric layers Water vapor density ismainly due to evaporation from free liquid waterduring the experiment and it decreases as initialmoisture content increases The total amount of heatabsorption attributable to water evaporation is about10 when the RH is 80
(4) A linear relationship exists between the initial mois-ture content and the maximum duration of heatradiation before causing first- and second-degreeburn injuries
Symbols
119888119901 Specific heat at constant pressureJ kgminus1 ∘Cminus1119863 Diffusivity of the gas phase in the fabricm2 secminus1
119889119891 Fiber radius mℎ119898 Convective heat transfer coefficient
Wmminus2 ∘Cminus1
Δℎ Enthalpy per unit mass J kgminus1119894119894 Fabric layer119896 Thermal conductivity Wmminus1 ∘Cminus1
119870 Darcian permeability coefficient m2119871 Thickness of the material mV119897 Mass transfer rate from the gaseous phase
to the liquid phase kgmminus3 secminus1V119887 Mass transfer rate from the gaseous phase
to the solid phase kgmminus3 secminus1119897119887 Mass transfer rate from the liquid phase to
the solid phase kgmminus3 secminus1119875119888 Pressure of liquid water Pa
119902rad Incident radiation heat flux from theradiation onto the outer fabric surfaceWmminus2119902minus119894119894 Radiation heat flux from the 119894119894 + 1 fabriclayer to the 119894119894 fabric layer Wmminus2119902+119894119894 Radiation heat flux from the 119894119894 minus 1 fabriclayer to the 119894119894 fabric layer Wmminus2
119894119894 Total radiation heat flux of the 119894119894 fabriclayer Wmminus2
119904 Saturation of the fabric119905 Time s119879 Temperature ∘CV Velocity of liquid water m secminus1119909 Distance m
Greek Symbols
120591 Transmissivity of the fabric120591 Fiber curl120588 Density kgmminus3120576 Absorption coefficient120576119887 Volume fraction120574 Radiative extinction coefficient of the
fabric mminus1120583119897 Dynamic viscosity kgmminus1 secminus1120590 Stefan-Boltzmann constant
120575 = 56705 times 10minus8W ∘Cminus4mminus2120596119887 Blood perfusion [000125m3 secminus1mminus3
tissue]Ω Quantitative measure of the burn damage
at the basal layer of human skin119875 Frequency factor or preexponential factor
secminus1Δ119864 Activation energy for skin119877 Universal gas constant
8315 times 103 J kmolminus1 ∘Cminus1
The Scientific World Journal 11
0007
0006
0005
0004
0003
0002
0001
휀l
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
20 sec25 sec30 sec35 sec40 sec
45 sec50 sec55 sec60 sec70 sec
(a) RH = 30
0007
0006
0005
0004
0003
0002
0001
휀l
0012
0011
0010
0009
0008
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
15 sec18 sec20 sec25 sec30 sec
35 sec40 sec50 sec60 sec70 sec
(b) RH = 50
휀l
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(c) RH = 65
휀l
0018
0016
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(d) RH = 80
Figure 12 Liquid water volume fraction distributions at different times
Subscripts
0 Initial stateeff Effective119897 Liquid water119887 Bound waterV Water vaporskin Skinblood Bloodamb Ambient air
vap Evaporationtrans Transferart Human core119871 Left boundary119877 Right boundary
Conflicts of Interest
The authors declare that they have no conflicts of interest
12 The Scientific World JournalH
eat a
bsor
bed
wat
er ev
apor
atio
n (J
)
3000
2500
2000
1500
1000
500
030 40 50 60 70 80
RH ()
Outer shellMoisture barrier
Thermal barrierTotal
Figure 13 Heat absorbed by water evaporation against RH withfitting line
First-degree burn injury timeSecond-degree burn injury time
Burn
inju
ry ti
me (
s)
136
132
128
124
120
116
112
RH ()minus10 0 10 20 30 40 50 60 70 80 90 100
Figure 14 Burning injury time versus RH
Authorsrsquo Contributions
Dongmei Huang carried out the experiment and numericalsimulation and drafted and revised the manuscript Song Heparticipated in the design of the study and performed thestatistical analysis and helped to draft the manuscript Allauthors read and approved the final manuscript
Acknowledgments
This work was supported by Natural Science Foundationof China (no 51306168) and Zhejiang Provincial NaturalScience Foundation of China under Grant no LY17E060004
Tem
pera
ture
(∘C)
Tem
pera
ture
(∘C)
52
51
50
49
48
47
46
45
44
43
42
41
RH ()20 30 40 50 60 70 80 90
360
359
358
357
356
355
354
353
352
351
350
100 sec50 sec10 sec
Figure 15 Temperature at skin surface
References
[1] L D Xu Y L Xy and M Jiang ldquoProtective clothing for fire-fighter GA10-2014rdquo in GA10-2002 China Standards PressBeijing China 2002
[2] D Huang H Yang Z Qi et al ldquoQuestionnaire on firefightersrsquoprotective clothing in Chinardquo Fire Technology vol 48 no 2 pp255ndash268 2012
[3] C C Guerth-Schacher Evaluation of the Effects of Moisture onthe Thermal Protective Performance of Fire Protective Clothingin Low Level Heat Exposures Fire and Polymer Science NorthCarolina State University Raleigh NC USA 2007
[4] R L Barker C Guerth-Schacher R V Grimes and H Hamou-da ldquoEffects of moisture on the thermal protective performanceof firefighter protective clothing in low-level radiant heatexposuresrdquo Textile Research Journal vol 76 no 1 pp 27ndash312006
[5] Y M Lee and R L Barker ldquoEffect of moisture on the thermalprotective performance of heat-resistant fabricsrdquo Journal of FireSciences vol 4 no 5 pp 315ndash331 1986
[6] J O Stull ldquoThe effect of moisture on firefighter protectiveclothing thermal insulation a review of industry researchrdquoin Performance of Protective Clothing Issues and Priorities forthe 21st Century vol 7th ASTM International West Con-shohocken Pa USA 2000
[7] C Keiser C Becker and R M Rossi ldquoMoisture transport andabsorption in multilayer protective clothing fabricsrdquo TextileResearch Journal vol 78 no 7 pp 604ndash613 2008
[8] Y Y Wang Y J Zong J Li and M M Zhao ldquoEvaluating themoisture transfer property of the multi-layered fabric system infirefighter turnout clothingrdquo Fibres amp Textiles in Eastern Europevol 19 no 6 article 89 pp 101ndash105 2011
[9] Y-Y Wang Y-H Lu J Li and J-H Pan ldquoEffects of airgap entrapped in multilayer fabrics and moisture on thermalprotective performancerdquo Fibers and Polymers vol 13 no 5 pp647ndash652 2012
[10] P Chitrphiromsri and A V Kuznetsov ldquoModeling heat andmoisture transport in firefighter protective clothing during flashfire exposurerdquo Heat and Mass Transfer vol 41 no 3 pp 206ndash215 2005
The Scientific World Journal 13
[11] J Fan X Cheng X Wen and W Sun ldquoAn improved modelof heat and moisture transfer with phase change and mobilecondensates in fibrous insulation and comparison with experi-mental resultsrdquo International Journal of Heat andMass Transfervol 47 no 10-11 pp 2343ndash2352 2004
[12] X Cheng and J Fan ldquoSimulation of heat and moisture transferwith phase change and mobile condensates in fibrous insula-tionrdquo International Journal of Thermal Sciences vol 43 no 7pp 665ndash676 2004
[13] SHeDHuang ZQiH Yang YHu andHZhang ldquoThe effectof air gap thickness on heat transfer in firefightersrsquo protectiveclothing under conditions of short exposure to heatrdquo HeatTransfer Research vol 43 no 8 pp 749ndash765 2012
[14] P Andersson and G Holmstedt ldquoHeat sensing manikin testproberdquo Fire and Materials vol 24 no 4 pp 195ndash199 2000
[15] J R Lawson Fire Fighterrsquos Protective Clothing and ThermalEnvironments of Structural Fire Fighting US Department ofCommerce Technology Administration National Institute ofStandards and Technology 1996
[16] P Chitrphiromsri and A V Kuznetsov ldquoPorous mediummodelfor investigating transient heat and moisture transport infirefighter protective clothing under high-intensity thermalexposurerdquo Journal of Porous Media vol 8 no 5 pp 511ndash5282005
[17] P Chitrphiromsri Modeling of Thermal Performance of Fire-fighter Protective Clothing during the Intense Heat ExposureNorth Carolina State University Raleigh NC USA 2004
[18] H P Harry ldquoAnalysis of tissue and arterial blood temperaturesin the resting human forearmrdquo Journal of Applied Physiologyvol 1 no 2 pp 93ndash122 1948
[19] F C Henriques ldquoStudies of thermal injury the predictabilityand the significance of thermally induced rate processes leadingto irreversible epidermal injuryrdquo Archives of pathology vol 43no 5 pp 489ndash502 1947
[20] S A Teukolsky ldquoStability of the iterated Crank-Nicholsonmethod in numerical relativityrdquo Physical Review DmdashParticlesFields Gravitation and Cosmology vol 61 no 8 Article ID087501 2000
[21] F-L Zhu and W-Y Zhang ldquoModeling heat transfer for heat-resistant fabrics considering pyrolysis effect under an externalheat fluxrdquo Journal of Fire Sciences vol 27 no 1 pp 81ndash96 2009
[22] W Q Tao Heat Transfer Northwestern Polytechnical Univer-sity Press Xirsquoan China 2006
[23] J Liu X Chen andL X Xu ldquoNew thermalwave aspects on bumevaluation of skin subjected to instantaneous heatingrdquo IEEETransactions on Biomedical Engineering vol 46 no 4 pp 420ndash428 1999
[24] A N Takata ldquoDevelopment of criterion for skin burnsrdquo Aero-space Medicine vol 45 no 6 pp 634ndash637 1974
[25] T R Gowrishankar D A Stewart G T Martin and J CWeaver ldquoTransport lattice models of heat transport in skinwith spatially heterogeneous temperature-dependent perfu-sionrdquo BioMedical Engineering Online vol 3 article no 42 2004
[26] D A Torvi and J D Dale ldquoA finite element model of skinsubjected to a flash firerdquo Journal of Biomechanical Engineeringvol 116 no 3 pp 250ndash255 1994
[27] A M Stoll and L C Greene ldquoRelationship between pain andtissue damage due to thermal radiationrdquo Journal of AppliedPhysiology vol 14 no 3 pp 373ndash382 1959
[28] MGasperin andD Juricic ldquoThe uncertainty in burn predictionas a result of variable skin parameters an experimental evalu-ation of burn-protective outfitsrdquo Burns vol 35 no 7 pp 970ndash982 2009
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The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
4 The Scientific World Journal
05 10 15 20 25 30 35
Distance (times10minus3 m)
10minus310minus2 10minus4
10minus5
30
40
50
60
70
80
90
100Te
mpe
ratu
re (∘
C)
(a) Results of time independence test
0 20 40 60 80 100 120
Time (s)
40
60
80
100
120
140
160
180
Tem
pera
ture
(∘C)
10minus3
10minus410minus5
10minus6
(b) Results of grid step independence test
Figure 4 Temperature distributions for time and grid independence tests
Initial conditions are as follows119879 (119909 0) = 293119870120588V (119909 0) = 120588V0120576119897 (119909 0) = 1205761198970120576119887 (119909 0) = 1205761198870V119897 (119909 0) = V1198970
(9)
Boundary conditions for the fabric are as follows
119879|119909=0 = minus345713119890minus119905391541 + 6582739minus119863eff
120597120588V120597119909
10038161003816100381610038161003816100381610038161003816119909=0 = ℎ119898amb (120588Vamb minus 120588V|119909=0) V1198971003816100381610038161003816119909=0 = 0
1205761198971003816100381610038161003816119909=0 = 120576119897left1205761198871003816100381610038161003816119909=0 = 0119879|119909=119871 = 40∘C120588V1003816100381610038161003816119909=119871 = 0V1198971003816100381610038161003816119909=119871 = 0
1205761198971003816100381610038161003816119909=119871 = 01205761198871003816100381610038161003816119909=119871 = 0
(10)
The temperature of the boundary conditions for the fabricis the fitting curve of the average temperature asmeasured bythe thermocouples under radiation of 5 kwmminus2
We used Henriquesrsquo tissue burn injury model [19] todetermine the thermal damage to human skin under the radi-ation heating processThe thermal damage ratewas estimatedusing the first-order Arrhenius rate equation Human skinsustains a burn injury when the temperature of the basal layer(see Figure 3) rises above 44∘C In this case
119889Ω119889119905 =
0 119879 lt 44∘C119875 exp (minusΔ119864
119877119879) 119879 ge 44∘C (11)
Equation (11) can be expressed as an integral equationnamely
Ω = int119905119900119875 exp(minusΔ119864
119877119879)119889119905 (12)
In this work differential equations (1)-(2) and (6)ndash(8)were solved using the finite volume method and time-stepping was carried out according to the well-knownCrank-Nicholson method [20] This process yielded a system ofnonlinear algebraic equations which was resolved by thegoal chasing method The conductivity and diffusivity onthe interface between the air gap and the fabric layer wereestimated using the harmonic mean The under relaxationprocedure with a parameter of 06 was utilized to preventdivergence of the iteration method The iterations wererepeated until the changes in the solutions became smallerthan 10minus6
Time and step independence are illustrated graphicallyin Figure 4 Figure 4(a) shows the temperature distributionin the fabric layers at 10 sec and Figure 4(b) shows thetemperature distribution at the mid thickness of the fabriclayers The data show that after a 10minus3 time step the resultsdo not change significantly CPU time increases from about600 sec to 3600 sec in an Intel i7-2600 processor when
The Scientific World Journal 5
450
400
350
300
250
200
150
100
50
Tem
pera
ture
(∘C)
0 20 40 60 80 100 120
Time (s)
TCONo1TCMNo1TCHNo1TCCNo1TCWNo1
TCONo2TCMNo2TCHNo2
TCWNo2TCCNo2
Figure 5 Temperature change with time at different locations
the time step increases from 10minus3 to 10minus5 The temperaturedistribution when the grid size exceeds 10minus4m is muchdifferent from that when the grid size is smaller than 10minus5mThe maximum temperature difference using a grid size of10minus5m and 10minus6m is about 6∘C CPU time increases fromabout 3600 sec to 21600 sec in an Intel i7-2600 processorwhen the grid step decreases from 10minus3 to 10minus6 To summarizethe time and space step are 10minus3 sec and 10minus5m respectively
4 Results and Discussion
41 Experimental Results To ensure the accuracy of theexperimental results we first analyzed experimental re-peatability The radiation intensity of the experiment was5 kWmminus2 The sample was dry the AG thickness betweenthe back surface of the fabric layer and human skin was zeroOther conditions were set as described above The results areshown in Figure 5Thedata demonstrate that the repeatabilityof experiment results is good
In the simulation the temperature measured at the outersurface and at the back surface of the fabric layer undera radiation intensity of 5 kWmminus2 was set as the T0 and119879119871 boundary temperatures respectively The temperatureequation was obtained by liner fitting using Origin softwareas seen in Figure 6
42 Simulation Results The thermal physical properties ofthe fabric samples used in the simulations can be reviewedin Chitrphiromsri et al [17 21] The parameters for specificheat capacity viscosity density and thermal conductivity ofair at different temperatures are in Taorsquos paper [22] Table 1shows the thermophysical and geometrical properties of thefabric and Table 2 provides the properties of human skinTheparameters of the Henriques equations were set identically to
0 20 40 60 80 100 120
Time (s)
50
100
150
200
250
300
350
400
Tem
pera
ture
(∘C)
TLTR
TL fittingTR fitting
Figure 6 Temperature profiles at outer surface and back surfaceof fabric layer The fitting equations for 119879119871 and 119879119877 are 119879119871 =minus345713 exp(minus119905391541) + 6582739 and 119879119877 = 31196812 +164134119905 minus 0077611199052 minus 0077611199053 + 0002031199054 minus 197183 times 10minus5 +646652 times 10minus81199055
Moi
sture
cont
ent (times10
minus3
kg)
20
16
12
08
04
000 10 20 30 40 50 60 70 80
RH ()
Outer shellMoisture barrier
Thermal barrierTotal
Figure 7Moisture weight in each fiber layer against RHwith fittingline
those in Liu et alrsquos paper [23] The thickness of each samplewas determined by measuring with a caliper three timesTheinitial moisture content is shown in Figure 7
The correlation coefficients of the fitting lines for theexperimental data describing the outer shell moisture bar-rier thermal linear and total multilayer material are 099205097086 099226 and 099700 respectively These resultsdemonstrate that the moisture weight in each layer as wellas the total moisture weight increases linearly with settledenvironmental RH as expected The moisture absorbed bywicking into the thermal barrier is about four times that inthe outer shell layer and two times that in themoisture barrier
6 The Scientific World Journal
Table 1 Thermophysical and geometrical properties of fabric [17 21 22]
Property Outer shell Moisture barrier Thermal barrier Comfort layerThickness of the material119871119894119894 [m] 031 times 10minus3 05 times 10minus3 11 times 10minus3 029 times 10minus3
Material of composition XDB602 Aramid fabric coatedwith PTFE film Aramid insulation Cotton shirting
Density 120588119891 [kgmminus3] 67742 21000 7727 41379Thermal conductivity (119896)119891[Wmminus1 Kminus1]
0075 0052 005 0053
Volume fraction 120576119891 0334 0186 0115 015Fibre curl 120591 15 125 1 1Diffusivity of the gas phasein the fabric119863119891 [m2 secminus1] 0 times 10minus14 0 times 10minus14 0 times 10minus14 0 times 10minus14
Fiber radius 119889119891 [m] 16 times 10minus5 16 times 10minus5 16 times 10minus5 16 times 10minus5
Darcian permeabilitycoefficient m2119870119897sat [m2] 10 times 10minus16 10 times 10minus16 10 times 10minus16 10 times 10minus16
Saturation of the fabric 119904119894119903 01 01 01 01Proportional constant ofliquid water absorption 120574119897119904[kgmminus3]
0 times 10minus4 0 times 10minus4 0 times 10minus4 0 times 10minus4
Table 2 Thermophysical and geometrical properties assigned to skin layers [14 15 25ndash28]
Property Epidermis Dermis Subcutaneous tissue BloodDensity 120588skin [kgmminus3] 1200 1200 1000 1060Thermal conductivity(119896)skin [Wmminus1 ∘Cminus1] 023 045 019 mdash
119871 skin [m] 008 times 10minus3 2 times 10minus3 10 times 10minus3 mdash119888119901skin [J kgminus1 ∘Cminus1] 3600 3300 2300 3770120596119887 [m3 secminus1mminus3 tissue] 0 000125 000125 mdash
layer The samples also felt obviously moist when touchedafter remaining for 24 h in circumstances with RH valuesexceeding 65
We designed an apparatus to simulate the process of heattransfer in FPC samples with different initial moisture con-tentsThe experimental setup and the samples were describedin Section 2 To ensure simulation accuracy we comparedthe simulation results with the experimental measurementswhich were corrected before analysis for radiation lossThe comparison model did not consider human skin Theboundary conditions were set identically to the experimentalmeasurements Figure 8 shows the simulated (continuouslines) and experimental (discrete points) temperature profilesat RH = 65 In the figure TCO TCM TCH and TCCrepresent the measurement results at different locations (asseen in Figure 3) while labels preceded by ldquo119878rdquo representthe simulation results The data show that the simulationresults are in good agreement with the experimental resultsThe mechanism for heat and moisture transfer in a systemconsisting of FPC materials air layers and human skinwith different initial moisture content conditions were thenanalyzed using the validated model combined with Pennesrsquo
model The first and second human injury burn times wereestimated using the Henriquesrsquo tissue burn injury model
Figure 9 shows the temperature profiles in different layersat particular moments in time The origin of the 119909-axis isat the outer shell surface as shown in Figure 3 Figure 9(a)shows that the temperatures in the fabric layers decreasesignificantly with distance at different moments in time buttemperatures decrease slowly in the skin layer A clean breakis identifiable between the fabric layer and the skin layerThismay be because heat transfer in fabric layers occurs throughheat conduction radiation and water evaporation and heatabsorption while the only heat transfer model in the skinlayer is heat conduction The temperature difference in skinunder different initial moisture contents is larger at 100 secthan at 10 sec as shown in Figure 9(b) This is because lessinitial moisture content in the samples leads to more heataccumulated in the fabric and the air gap during radiation
We then analyzed the temperature differences underdifferent initial moisture conditions in the fabric and skinlayers with the results shown in Figures 9(c) and 9(d) Thetemperature difference in the fabric under different initialmoisture contents is higher at 10 s than at 100 s These results
The Scientific World Journal 7
0 20 40 60 80 100 120
Time (s)
Tem
pera
ture
(∘C)
400
350
300
250
200
150
100
50
0
Test-TCOTest-TCMTest-TCHTest-TCC
Simulation-TCOSimulation-TCMSimulation-TCHSimulation-TCC
(a) Temperature versus time
00 05 10 15 25 25 30 35 40
Thickness (times10minus3 m)
400
360
280
200
240
320
120
160
80
40
0
Tem
pera
ture
(∘C)
Test-10 secTest-20 secTest-40 secTest-60 secTest-80 secTest-100 secTest-120 sec
Simulation-20 secSimulation-10 sec
Simulation-40 secSimulation-60 secSimulation-80 secSimulation-100 secSimulation-120 sec
(b) Temperature versus thickness
Figure 8 Simulated (continuous lines) and experimental (discrete points) temperature profiles when RH = 65
are in agreement with the accepted point of view that theinitial moisture content of a sample affects heat transfer inthe fabric primarily at the beginning of heating The humanskin begins at 000388m The skin surface temperatureincreases from 309∘C at 10 sec to around 324∘C at 100 secunder different initial moisture contents The skin temper-ature increases as the initial moisture content of the fabricdecreases
Figure 10 shows the profiles for water vapor density in thefabric and air gap layers at different times The data indicatethat the water vapor density decreases as distance from theouter surface increases this occurs because the water vapordensity decreases with temperature which decreases withdistance Higher temperatures providemore energy for waterevaporation The maximum water vapor density in eachlayer increases very rapidly with t reaching a maximum atabout 20 sec under the conditions outlined in this paper asshown in Figure 11 The curve follows a normal distributionbetween about 10 sec and 35 sec After 35 sec the water vapordensity decreases more slowly with time In other words theactuation duration of the initial moisture of FPC samples wasless than 35 sec in this experimental situation
In our experiment the temperature increased whenthe outer shell of the FPC sample was exposed to heatradiation which caused the desorption and evaporationof bound water as well as the evaporation of free liquidwater located in the fabric pores To examine further themechanism of moisture transformation during heating weanalyzed the liquid water volume fraction in the fabricpores at different times as shown in Figure 12 The datashow that the distribution of liquid water in the fabric
unlike that of water vapor is completely noncontinuous Theinitial liquid water volume fraction in each fabric layer isuniform and it increases noticeably with increasing initialmoisture content As the temperature increases the liquidwater volume fraction decreases and the water vapor densityincreases
Figure 13 plots the heat absorbed by water evaporationagainst RH with a fitting line According to the conser-vation equations moisture in the fabric consists of boundliquid and gaseous water Under high temperatures thebound water transfers to a liquid state and the liquid waterevaporates to a gaseous state The enthalpy of the transitionfrom bound water to free liquid water is about 2509 J gminus1under relative humidity of 65 The enthalpy of evaporationper unit mass is about 2400 J gminus1 The bound water andliquid water volume fractions in each fabric layer can bederived from the simulationThen the heat absorbed throughwater evaporation can be determined based on differentinitial moisture conditions as shown in Figure 13 The datademonstrate that the heat absorbed by water evaporationincreases linearly with increasing RH
Figure 12 shows that the time required for the moistureto evaporate completely is about 70 s The heat flux on thematerial surface is 5 kWmminus2 and the dimension of thesample is 230 cm times 230 cmThe total quantity of heat appliedto the surface of the material is about 18515 J Figure 13 showsthat at the RH level of 80 the heat absorbed through waterevaporation is about 2000 J which constitutesmore than 10of the total heat
We also investigated the effect of the initial fabric mois-ture content on the maximum duration of heat radiation
8 The Scientific World Journal
350
300
250
200
150
100
50
0
Tem
pera
ture
(∘C)
100 sec
50 sec
10 sec
0 1 2 3 4 5
Distance (times10minus3 m)
Fabric layer Skin layer
HR = 30 10 secHR = 65 10 secHR = 30 50 secHR = 65 50 sec
HR = 50 10 secHR = 80 10 secHR = 50 50 secHR = 80 50 sec
HR = 30 100 secHR = 65 100 sec
HR = 50 100 secHR = 80 100 sec
(a) Temperature profile in both fabric and skin layers
100 sec
50 sec
10 sec
Fabric layerSkin layer
Distance (times10minus3 m)385 390 395
40
50
60
Tem
pera
ture
(∘C)
HR = 30 10 secHR = 65 10 secHR = 30 50 secHR = 65 50 sec
HR = 50 10 secHR = 80 10 secHR = 50 50 secHR = 80 50 sec
HR = 30 100 secHR = 65 100 sec
HR = 50 100 secHR = 80 100 sec
(b) Temperature profile at fabric-skin interface
00 05 10 15 20 25 30 35
HR = 30HR = 50
HR = 65HR = 80
100 sec
10 sec
Distance (times10minus3 m)
30
40
50
60
70
80
90
100
110
Tem
pera
ture
(∘C)
50
100
150
200
250
300
Tem
pera
ture
(∘C)
(c) Temperature profile in fabric
400 425 450 475 500 525 550 575
HR = 30HR = 50
HR = 65HR = 80
Distance (times10minus3 m)
100 sec
50 sec
10 sec
32
36
40
44
48
52
56
Tem
pera
ture
(∘C)
(d) Temperature profile in skin
Figure 9 Temperature profiles in different layers at specific moments in time
before the wearer sustains first- and second-degree burninjuries The tissue burn injury model is based on work byHenriques [19] and it is calculated according to (11) Takatarsquos[24] criterion was used to determine that first- and second-degree burn injuries occur whenΩ = 053 and 1 respectivelyon the basal layer of the skin (the interface of the epidermisand dermis) Figure 14 shows human skin burn injury timeversus RH The data show that as the initial moisturecontent in the fabric increases the maximum duration ofheat radiation before acquiring first- and second-degree burninjuries increases linearly This occurs because higher initialmoisture in fabric pores allows more energy to be absorbed
by water phase transfers during the heating process Thefirst- and second-degree burn injury time increases 16 secand 18 sec when the RH increases from 0 to 90 Theheat absorbed through water evaporation is 10 of thetotal quantity of heat applied to the surface of the materialHowever the comfort of clothing is usually very low whenthe clothing is set at the environment in which the RH ismore than 80 Therefore the RH is usually less than 80The temperature at the skin surface at different moment isshown in Figure 15We can see that the temperature decreaseswith increasing the initial moisture content The maximumtemperature difference between the RH of 30 and 80
The Scientific World Journal 9
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
120 sec
006
005
004
003
002
001
00000 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec21 sec32 sec50 sec
16 sec25 sec35 sec80 sec
20 sec30 sec40 sec
(a) RH = 30
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
009
008
007
006
005
004
003
002
001
00000 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec20 sec32 sec50 sec
10 sec25 sec35 sec80 sec
16 sec
120 sec
30 sec40 sec
(b) RH = 50
012
010
008
006
004
002
000
OSAL
MB
AL
TB
AL
CL AL휌
(kg
mminus3)
00 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec11 sec15 sec30 sec
5 sec12 sec16 sec50 sec
10 sec13 sec20 sec120 sec
(c) RH = 65
012
010
008
006
004
002
000
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
00 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec21 sec32 sec50 sec
16 sec25 sec35 sec80 sec
20 sec30 sec40 sec
(d) RH = 80
Figure 10 Distributions of water vapor density at different times
condition is about 1 K which is really slight But the effect ofenergy on the skin injury is an accumulation behavior whichleads to the second-degree burn injury time increasing about8 sec
5 Conclusion
We developed a numerical model to investigate the effectsof initial moisture content at each fabric layer on heat andmoisture transfer in FPCmaterialsWe estimated burn injurytimes under different initial moisture contents using our
model combined with Pennesrsquo model and Henriquesrsquo tissueburn injury model We can draw the following conclusions
(1) Initial moisture content in each FPC fabric layerincreases linearly as the RH of the storage locationincreases
(2) We developed a comprehensive model to simulateheat andmoisture transfer in FPC and the simulationresults show fairly good agreement with the experi-mental results
10 The Scientific World Journal
024
022
020
018
016
014
012
010
008
006
004
002
0000 20 40 60 80 100 120
Time (s)
HR = 30HR = 50
HR = 65HR = 80
휌
(kg
mminus3)
Figure 11 Profiles of water vapor density versus time at a distance of 056 times 10minus3m
(3) Water vapor is distributed both in the fabric layersand in the air layer while free liquid water dispersesonly in the fabric layers Water vapor density ismainly due to evaporation from free liquid waterduring the experiment and it decreases as initialmoisture content increases The total amount of heatabsorption attributable to water evaporation is about10 when the RH is 80
(4) A linear relationship exists between the initial mois-ture content and the maximum duration of heatradiation before causing first- and second-degreeburn injuries
Symbols
119888119901 Specific heat at constant pressureJ kgminus1 ∘Cminus1119863 Diffusivity of the gas phase in the fabricm2 secminus1
119889119891 Fiber radius mℎ119898 Convective heat transfer coefficient
Wmminus2 ∘Cminus1
Δℎ Enthalpy per unit mass J kgminus1119894119894 Fabric layer119896 Thermal conductivity Wmminus1 ∘Cminus1
119870 Darcian permeability coefficient m2119871 Thickness of the material mV119897 Mass transfer rate from the gaseous phase
to the liquid phase kgmminus3 secminus1V119887 Mass transfer rate from the gaseous phase
to the solid phase kgmminus3 secminus1119897119887 Mass transfer rate from the liquid phase to
the solid phase kgmminus3 secminus1119875119888 Pressure of liquid water Pa
119902rad Incident radiation heat flux from theradiation onto the outer fabric surfaceWmminus2119902minus119894119894 Radiation heat flux from the 119894119894 + 1 fabriclayer to the 119894119894 fabric layer Wmminus2119902+119894119894 Radiation heat flux from the 119894119894 minus 1 fabriclayer to the 119894119894 fabric layer Wmminus2
119894119894 Total radiation heat flux of the 119894119894 fabriclayer Wmminus2
119904 Saturation of the fabric119905 Time s119879 Temperature ∘CV Velocity of liquid water m secminus1119909 Distance m
Greek Symbols
120591 Transmissivity of the fabric120591 Fiber curl120588 Density kgmminus3120576 Absorption coefficient120576119887 Volume fraction120574 Radiative extinction coefficient of the
fabric mminus1120583119897 Dynamic viscosity kgmminus1 secminus1120590 Stefan-Boltzmann constant
120575 = 56705 times 10minus8W ∘Cminus4mminus2120596119887 Blood perfusion [000125m3 secminus1mminus3
tissue]Ω Quantitative measure of the burn damage
at the basal layer of human skin119875 Frequency factor or preexponential factor
secminus1Δ119864 Activation energy for skin119877 Universal gas constant
8315 times 103 J kmolminus1 ∘Cminus1
The Scientific World Journal 11
0007
0006
0005
0004
0003
0002
0001
휀l
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
20 sec25 sec30 sec35 sec40 sec
45 sec50 sec55 sec60 sec70 sec
(a) RH = 30
0007
0006
0005
0004
0003
0002
0001
휀l
0012
0011
0010
0009
0008
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
15 sec18 sec20 sec25 sec30 sec
35 sec40 sec50 sec60 sec70 sec
(b) RH = 50
휀l
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(c) RH = 65
휀l
0018
0016
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(d) RH = 80
Figure 12 Liquid water volume fraction distributions at different times
Subscripts
0 Initial stateeff Effective119897 Liquid water119887 Bound waterV Water vaporskin Skinblood Bloodamb Ambient air
vap Evaporationtrans Transferart Human core119871 Left boundary119877 Right boundary
Conflicts of Interest
The authors declare that they have no conflicts of interest
12 The Scientific World JournalH
eat a
bsor
bed
wat
er ev
apor
atio
n (J
)
3000
2500
2000
1500
1000
500
030 40 50 60 70 80
RH ()
Outer shellMoisture barrier
Thermal barrierTotal
Figure 13 Heat absorbed by water evaporation against RH withfitting line
First-degree burn injury timeSecond-degree burn injury time
Burn
inju
ry ti
me (
s)
136
132
128
124
120
116
112
RH ()minus10 0 10 20 30 40 50 60 70 80 90 100
Figure 14 Burning injury time versus RH
Authorsrsquo Contributions
Dongmei Huang carried out the experiment and numericalsimulation and drafted and revised the manuscript Song Heparticipated in the design of the study and performed thestatistical analysis and helped to draft the manuscript Allauthors read and approved the final manuscript
Acknowledgments
This work was supported by Natural Science Foundationof China (no 51306168) and Zhejiang Provincial NaturalScience Foundation of China under Grant no LY17E060004
Tem
pera
ture
(∘C)
Tem
pera
ture
(∘C)
52
51
50
49
48
47
46
45
44
43
42
41
RH ()20 30 40 50 60 70 80 90
360
359
358
357
356
355
354
353
352
351
350
100 sec50 sec10 sec
Figure 15 Temperature at skin surface
References
[1] L D Xu Y L Xy and M Jiang ldquoProtective clothing for fire-fighter GA10-2014rdquo in GA10-2002 China Standards PressBeijing China 2002
[2] D Huang H Yang Z Qi et al ldquoQuestionnaire on firefightersrsquoprotective clothing in Chinardquo Fire Technology vol 48 no 2 pp255ndash268 2012
[3] C C Guerth-Schacher Evaluation of the Effects of Moisture onthe Thermal Protective Performance of Fire Protective Clothingin Low Level Heat Exposures Fire and Polymer Science NorthCarolina State University Raleigh NC USA 2007
[4] R L Barker C Guerth-Schacher R V Grimes and H Hamou-da ldquoEffects of moisture on the thermal protective performanceof firefighter protective clothing in low-level radiant heatexposuresrdquo Textile Research Journal vol 76 no 1 pp 27ndash312006
[5] Y M Lee and R L Barker ldquoEffect of moisture on the thermalprotective performance of heat-resistant fabricsrdquo Journal of FireSciences vol 4 no 5 pp 315ndash331 1986
[6] J O Stull ldquoThe effect of moisture on firefighter protectiveclothing thermal insulation a review of industry researchrdquoin Performance of Protective Clothing Issues and Priorities forthe 21st Century vol 7th ASTM International West Con-shohocken Pa USA 2000
[7] C Keiser C Becker and R M Rossi ldquoMoisture transport andabsorption in multilayer protective clothing fabricsrdquo TextileResearch Journal vol 78 no 7 pp 604ndash613 2008
[8] Y Y Wang Y J Zong J Li and M M Zhao ldquoEvaluating themoisture transfer property of the multi-layered fabric system infirefighter turnout clothingrdquo Fibres amp Textiles in Eastern Europevol 19 no 6 article 89 pp 101ndash105 2011
[9] Y-Y Wang Y-H Lu J Li and J-H Pan ldquoEffects of airgap entrapped in multilayer fabrics and moisture on thermalprotective performancerdquo Fibers and Polymers vol 13 no 5 pp647ndash652 2012
[10] P Chitrphiromsri and A V Kuznetsov ldquoModeling heat andmoisture transport in firefighter protective clothing during flashfire exposurerdquo Heat and Mass Transfer vol 41 no 3 pp 206ndash215 2005
The Scientific World Journal 13
[11] J Fan X Cheng X Wen and W Sun ldquoAn improved modelof heat and moisture transfer with phase change and mobilecondensates in fibrous insulation and comparison with experi-mental resultsrdquo International Journal of Heat andMass Transfervol 47 no 10-11 pp 2343ndash2352 2004
[12] X Cheng and J Fan ldquoSimulation of heat and moisture transferwith phase change and mobile condensates in fibrous insula-tionrdquo International Journal of Thermal Sciences vol 43 no 7pp 665ndash676 2004
[13] SHeDHuang ZQiH Yang YHu andHZhang ldquoThe effectof air gap thickness on heat transfer in firefightersrsquo protectiveclothing under conditions of short exposure to heatrdquo HeatTransfer Research vol 43 no 8 pp 749ndash765 2012
[14] P Andersson and G Holmstedt ldquoHeat sensing manikin testproberdquo Fire and Materials vol 24 no 4 pp 195ndash199 2000
[15] J R Lawson Fire Fighterrsquos Protective Clothing and ThermalEnvironments of Structural Fire Fighting US Department ofCommerce Technology Administration National Institute ofStandards and Technology 1996
[16] P Chitrphiromsri and A V Kuznetsov ldquoPorous mediummodelfor investigating transient heat and moisture transport infirefighter protective clothing under high-intensity thermalexposurerdquo Journal of Porous Media vol 8 no 5 pp 511ndash5282005
[17] P Chitrphiromsri Modeling of Thermal Performance of Fire-fighter Protective Clothing during the Intense Heat ExposureNorth Carolina State University Raleigh NC USA 2004
[18] H P Harry ldquoAnalysis of tissue and arterial blood temperaturesin the resting human forearmrdquo Journal of Applied Physiologyvol 1 no 2 pp 93ndash122 1948
[19] F C Henriques ldquoStudies of thermal injury the predictabilityand the significance of thermally induced rate processes leadingto irreversible epidermal injuryrdquo Archives of pathology vol 43no 5 pp 489ndash502 1947
[20] S A Teukolsky ldquoStability of the iterated Crank-Nicholsonmethod in numerical relativityrdquo Physical Review DmdashParticlesFields Gravitation and Cosmology vol 61 no 8 Article ID087501 2000
[21] F-L Zhu and W-Y Zhang ldquoModeling heat transfer for heat-resistant fabrics considering pyrolysis effect under an externalheat fluxrdquo Journal of Fire Sciences vol 27 no 1 pp 81ndash96 2009
[22] W Q Tao Heat Transfer Northwestern Polytechnical Univer-sity Press Xirsquoan China 2006
[23] J Liu X Chen andL X Xu ldquoNew thermalwave aspects on bumevaluation of skin subjected to instantaneous heatingrdquo IEEETransactions on Biomedical Engineering vol 46 no 4 pp 420ndash428 1999
[24] A N Takata ldquoDevelopment of criterion for skin burnsrdquo Aero-space Medicine vol 45 no 6 pp 634ndash637 1974
[25] T R Gowrishankar D A Stewart G T Martin and J CWeaver ldquoTransport lattice models of heat transport in skinwith spatially heterogeneous temperature-dependent perfu-sionrdquo BioMedical Engineering Online vol 3 article no 42 2004
[26] D A Torvi and J D Dale ldquoA finite element model of skinsubjected to a flash firerdquo Journal of Biomechanical Engineeringvol 116 no 3 pp 250ndash255 1994
[27] A M Stoll and L C Greene ldquoRelationship between pain andtissue damage due to thermal radiationrdquo Journal of AppliedPhysiology vol 14 no 3 pp 373ndash382 1959
[28] MGasperin andD Juricic ldquoThe uncertainty in burn predictionas a result of variable skin parameters an experimental evalu-ation of burn-protective outfitsrdquo Burns vol 35 no 7 pp 970ndash982 2009
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The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
The Scientific World Journal 5
450
400
350
300
250
200
150
100
50
Tem
pera
ture
(∘C)
0 20 40 60 80 100 120
Time (s)
TCONo1TCMNo1TCHNo1TCCNo1TCWNo1
TCONo2TCMNo2TCHNo2
TCWNo2TCCNo2
Figure 5 Temperature change with time at different locations
the time step increases from 10minus3 to 10minus5 The temperaturedistribution when the grid size exceeds 10minus4m is muchdifferent from that when the grid size is smaller than 10minus5mThe maximum temperature difference using a grid size of10minus5m and 10minus6m is about 6∘C CPU time increases fromabout 3600 sec to 21600 sec in an Intel i7-2600 processorwhen the grid step decreases from 10minus3 to 10minus6 To summarizethe time and space step are 10minus3 sec and 10minus5m respectively
4 Results and Discussion
41 Experimental Results To ensure the accuracy of theexperimental results we first analyzed experimental re-peatability The radiation intensity of the experiment was5 kWmminus2 The sample was dry the AG thickness betweenthe back surface of the fabric layer and human skin was zeroOther conditions were set as described above The results areshown in Figure 5Thedata demonstrate that the repeatabilityof experiment results is good
In the simulation the temperature measured at the outersurface and at the back surface of the fabric layer undera radiation intensity of 5 kWmminus2 was set as the T0 and119879119871 boundary temperatures respectively The temperatureequation was obtained by liner fitting using Origin softwareas seen in Figure 6
42 Simulation Results The thermal physical properties ofthe fabric samples used in the simulations can be reviewedin Chitrphiromsri et al [17 21] The parameters for specificheat capacity viscosity density and thermal conductivity ofair at different temperatures are in Taorsquos paper [22] Table 1shows the thermophysical and geometrical properties of thefabric and Table 2 provides the properties of human skinTheparameters of the Henriques equations were set identically to
0 20 40 60 80 100 120
Time (s)
50
100
150
200
250
300
350
400
Tem
pera
ture
(∘C)
TLTR
TL fittingTR fitting
Figure 6 Temperature profiles at outer surface and back surfaceof fabric layer The fitting equations for 119879119871 and 119879119877 are 119879119871 =minus345713 exp(minus119905391541) + 6582739 and 119879119877 = 31196812 +164134119905 minus 0077611199052 minus 0077611199053 + 0002031199054 minus 197183 times 10minus5 +646652 times 10minus81199055
Moi
sture
cont
ent (times10
minus3
kg)
20
16
12
08
04
000 10 20 30 40 50 60 70 80
RH ()
Outer shellMoisture barrier
Thermal barrierTotal
Figure 7Moisture weight in each fiber layer against RHwith fittingline
those in Liu et alrsquos paper [23] The thickness of each samplewas determined by measuring with a caliper three timesTheinitial moisture content is shown in Figure 7
The correlation coefficients of the fitting lines for theexperimental data describing the outer shell moisture bar-rier thermal linear and total multilayer material are 099205097086 099226 and 099700 respectively These resultsdemonstrate that the moisture weight in each layer as wellas the total moisture weight increases linearly with settledenvironmental RH as expected The moisture absorbed bywicking into the thermal barrier is about four times that inthe outer shell layer and two times that in themoisture barrier
6 The Scientific World Journal
Table 1 Thermophysical and geometrical properties of fabric [17 21 22]
Property Outer shell Moisture barrier Thermal barrier Comfort layerThickness of the material119871119894119894 [m] 031 times 10minus3 05 times 10minus3 11 times 10minus3 029 times 10minus3
Material of composition XDB602 Aramid fabric coatedwith PTFE film Aramid insulation Cotton shirting
Density 120588119891 [kgmminus3] 67742 21000 7727 41379Thermal conductivity (119896)119891[Wmminus1 Kminus1]
0075 0052 005 0053
Volume fraction 120576119891 0334 0186 0115 015Fibre curl 120591 15 125 1 1Diffusivity of the gas phasein the fabric119863119891 [m2 secminus1] 0 times 10minus14 0 times 10minus14 0 times 10minus14 0 times 10minus14
Fiber radius 119889119891 [m] 16 times 10minus5 16 times 10minus5 16 times 10minus5 16 times 10minus5
Darcian permeabilitycoefficient m2119870119897sat [m2] 10 times 10minus16 10 times 10minus16 10 times 10minus16 10 times 10minus16
Saturation of the fabric 119904119894119903 01 01 01 01Proportional constant ofliquid water absorption 120574119897119904[kgmminus3]
0 times 10minus4 0 times 10minus4 0 times 10minus4 0 times 10minus4
Table 2 Thermophysical and geometrical properties assigned to skin layers [14 15 25ndash28]
Property Epidermis Dermis Subcutaneous tissue BloodDensity 120588skin [kgmminus3] 1200 1200 1000 1060Thermal conductivity(119896)skin [Wmminus1 ∘Cminus1] 023 045 019 mdash
119871 skin [m] 008 times 10minus3 2 times 10minus3 10 times 10minus3 mdash119888119901skin [J kgminus1 ∘Cminus1] 3600 3300 2300 3770120596119887 [m3 secminus1mminus3 tissue] 0 000125 000125 mdash
layer The samples also felt obviously moist when touchedafter remaining for 24 h in circumstances with RH valuesexceeding 65
We designed an apparatus to simulate the process of heattransfer in FPC samples with different initial moisture con-tentsThe experimental setup and the samples were describedin Section 2 To ensure simulation accuracy we comparedthe simulation results with the experimental measurementswhich were corrected before analysis for radiation lossThe comparison model did not consider human skin Theboundary conditions were set identically to the experimentalmeasurements Figure 8 shows the simulated (continuouslines) and experimental (discrete points) temperature profilesat RH = 65 In the figure TCO TCM TCH and TCCrepresent the measurement results at different locations (asseen in Figure 3) while labels preceded by ldquo119878rdquo representthe simulation results The data show that the simulationresults are in good agreement with the experimental resultsThe mechanism for heat and moisture transfer in a systemconsisting of FPC materials air layers and human skinwith different initial moisture content conditions were thenanalyzed using the validated model combined with Pennesrsquo
model The first and second human injury burn times wereestimated using the Henriquesrsquo tissue burn injury model
Figure 9 shows the temperature profiles in different layersat particular moments in time The origin of the 119909-axis isat the outer shell surface as shown in Figure 3 Figure 9(a)shows that the temperatures in the fabric layers decreasesignificantly with distance at different moments in time buttemperatures decrease slowly in the skin layer A clean breakis identifiable between the fabric layer and the skin layerThismay be because heat transfer in fabric layers occurs throughheat conduction radiation and water evaporation and heatabsorption while the only heat transfer model in the skinlayer is heat conduction The temperature difference in skinunder different initial moisture contents is larger at 100 secthan at 10 sec as shown in Figure 9(b) This is because lessinitial moisture content in the samples leads to more heataccumulated in the fabric and the air gap during radiation
We then analyzed the temperature differences underdifferent initial moisture conditions in the fabric and skinlayers with the results shown in Figures 9(c) and 9(d) Thetemperature difference in the fabric under different initialmoisture contents is higher at 10 s than at 100 s These results
The Scientific World Journal 7
0 20 40 60 80 100 120
Time (s)
Tem
pera
ture
(∘C)
400
350
300
250
200
150
100
50
0
Test-TCOTest-TCMTest-TCHTest-TCC
Simulation-TCOSimulation-TCMSimulation-TCHSimulation-TCC
(a) Temperature versus time
00 05 10 15 25 25 30 35 40
Thickness (times10minus3 m)
400
360
280
200
240
320
120
160
80
40
0
Tem
pera
ture
(∘C)
Test-10 secTest-20 secTest-40 secTest-60 secTest-80 secTest-100 secTest-120 sec
Simulation-20 secSimulation-10 sec
Simulation-40 secSimulation-60 secSimulation-80 secSimulation-100 secSimulation-120 sec
(b) Temperature versus thickness
Figure 8 Simulated (continuous lines) and experimental (discrete points) temperature profiles when RH = 65
are in agreement with the accepted point of view that theinitial moisture content of a sample affects heat transfer inthe fabric primarily at the beginning of heating The humanskin begins at 000388m The skin surface temperatureincreases from 309∘C at 10 sec to around 324∘C at 100 secunder different initial moisture contents The skin temper-ature increases as the initial moisture content of the fabricdecreases
Figure 10 shows the profiles for water vapor density in thefabric and air gap layers at different times The data indicatethat the water vapor density decreases as distance from theouter surface increases this occurs because the water vapordensity decreases with temperature which decreases withdistance Higher temperatures providemore energy for waterevaporation The maximum water vapor density in eachlayer increases very rapidly with t reaching a maximum atabout 20 sec under the conditions outlined in this paper asshown in Figure 11 The curve follows a normal distributionbetween about 10 sec and 35 sec After 35 sec the water vapordensity decreases more slowly with time In other words theactuation duration of the initial moisture of FPC samples wasless than 35 sec in this experimental situation
In our experiment the temperature increased whenthe outer shell of the FPC sample was exposed to heatradiation which caused the desorption and evaporationof bound water as well as the evaporation of free liquidwater located in the fabric pores To examine further themechanism of moisture transformation during heating weanalyzed the liquid water volume fraction in the fabricpores at different times as shown in Figure 12 The datashow that the distribution of liquid water in the fabric
unlike that of water vapor is completely noncontinuous Theinitial liquid water volume fraction in each fabric layer isuniform and it increases noticeably with increasing initialmoisture content As the temperature increases the liquidwater volume fraction decreases and the water vapor densityincreases
Figure 13 plots the heat absorbed by water evaporationagainst RH with a fitting line According to the conser-vation equations moisture in the fabric consists of boundliquid and gaseous water Under high temperatures thebound water transfers to a liquid state and the liquid waterevaporates to a gaseous state The enthalpy of the transitionfrom bound water to free liquid water is about 2509 J gminus1under relative humidity of 65 The enthalpy of evaporationper unit mass is about 2400 J gminus1 The bound water andliquid water volume fractions in each fabric layer can bederived from the simulationThen the heat absorbed throughwater evaporation can be determined based on differentinitial moisture conditions as shown in Figure 13 The datademonstrate that the heat absorbed by water evaporationincreases linearly with increasing RH
Figure 12 shows that the time required for the moistureto evaporate completely is about 70 s The heat flux on thematerial surface is 5 kWmminus2 and the dimension of thesample is 230 cm times 230 cmThe total quantity of heat appliedto the surface of the material is about 18515 J Figure 13 showsthat at the RH level of 80 the heat absorbed through waterevaporation is about 2000 J which constitutesmore than 10of the total heat
We also investigated the effect of the initial fabric mois-ture content on the maximum duration of heat radiation
8 The Scientific World Journal
350
300
250
200
150
100
50
0
Tem
pera
ture
(∘C)
100 sec
50 sec
10 sec
0 1 2 3 4 5
Distance (times10minus3 m)
Fabric layer Skin layer
HR = 30 10 secHR = 65 10 secHR = 30 50 secHR = 65 50 sec
HR = 50 10 secHR = 80 10 secHR = 50 50 secHR = 80 50 sec
HR = 30 100 secHR = 65 100 sec
HR = 50 100 secHR = 80 100 sec
(a) Temperature profile in both fabric and skin layers
100 sec
50 sec
10 sec
Fabric layerSkin layer
Distance (times10minus3 m)385 390 395
40
50
60
Tem
pera
ture
(∘C)
HR = 30 10 secHR = 65 10 secHR = 30 50 secHR = 65 50 sec
HR = 50 10 secHR = 80 10 secHR = 50 50 secHR = 80 50 sec
HR = 30 100 secHR = 65 100 sec
HR = 50 100 secHR = 80 100 sec
(b) Temperature profile at fabric-skin interface
00 05 10 15 20 25 30 35
HR = 30HR = 50
HR = 65HR = 80
100 sec
10 sec
Distance (times10minus3 m)
30
40
50
60
70
80
90
100
110
Tem
pera
ture
(∘C)
50
100
150
200
250
300
Tem
pera
ture
(∘C)
(c) Temperature profile in fabric
400 425 450 475 500 525 550 575
HR = 30HR = 50
HR = 65HR = 80
Distance (times10minus3 m)
100 sec
50 sec
10 sec
32
36
40
44
48
52
56
Tem
pera
ture
(∘C)
(d) Temperature profile in skin
Figure 9 Temperature profiles in different layers at specific moments in time
before the wearer sustains first- and second-degree burninjuries The tissue burn injury model is based on work byHenriques [19] and it is calculated according to (11) Takatarsquos[24] criterion was used to determine that first- and second-degree burn injuries occur whenΩ = 053 and 1 respectivelyon the basal layer of the skin (the interface of the epidermisand dermis) Figure 14 shows human skin burn injury timeversus RH The data show that as the initial moisturecontent in the fabric increases the maximum duration ofheat radiation before acquiring first- and second-degree burninjuries increases linearly This occurs because higher initialmoisture in fabric pores allows more energy to be absorbed
by water phase transfers during the heating process Thefirst- and second-degree burn injury time increases 16 secand 18 sec when the RH increases from 0 to 90 Theheat absorbed through water evaporation is 10 of thetotal quantity of heat applied to the surface of the materialHowever the comfort of clothing is usually very low whenthe clothing is set at the environment in which the RH ismore than 80 Therefore the RH is usually less than 80The temperature at the skin surface at different moment isshown in Figure 15We can see that the temperature decreaseswith increasing the initial moisture content The maximumtemperature difference between the RH of 30 and 80
The Scientific World Journal 9
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
120 sec
006
005
004
003
002
001
00000 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec21 sec32 sec50 sec
16 sec25 sec35 sec80 sec
20 sec30 sec40 sec
(a) RH = 30
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
009
008
007
006
005
004
003
002
001
00000 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec20 sec32 sec50 sec
10 sec25 sec35 sec80 sec
16 sec
120 sec
30 sec40 sec
(b) RH = 50
012
010
008
006
004
002
000
OSAL
MB
AL
TB
AL
CL AL휌
(kg
mminus3)
00 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec11 sec15 sec30 sec
5 sec12 sec16 sec50 sec
10 sec13 sec20 sec120 sec
(c) RH = 65
012
010
008
006
004
002
000
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
00 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec21 sec32 sec50 sec
16 sec25 sec35 sec80 sec
20 sec30 sec40 sec
(d) RH = 80
Figure 10 Distributions of water vapor density at different times
condition is about 1 K which is really slight But the effect ofenergy on the skin injury is an accumulation behavior whichleads to the second-degree burn injury time increasing about8 sec
5 Conclusion
We developed a numerical model to investigate the effectsof initial moisture content at each fabric layer on heat andmoisture transfer in FPCmaterialsWe estimated burn injurytimes under different initial moisture contents using our
model combined with Pennesrsquo model and Henriquesrsquo tissueburn injury model We can draw the following conclusions
(1) Initial moisture content in each FPC fabric layerincreases linearly as the RH of the storage locationincreases
(2) We developed a comprehensive model to simulateheat andmoisture transfer in FPC and the simulationresults show fairly good agreement with the experi-mental results
10 The Scientific World Journal
024
022
020
018
016
014
012
010
008
006
004
002
0000 20 40 60 80 100 120
Time (s)
HR = 30HR = 50
HR = 65HR = 80
휌
(kg
mminus3)
Figure 11 Profiles of water vapor density versus time at a distance of 056 times 10minus3m
(3) Water vapor is distributed both in the fabric layersand in the air layer while free liquid water dispersesonly in the fabric layers Water vapor density ismainly due to evaporation from free liquid waterduring the experiment and it decreases as initialmoisture content increases The total amount of heatabsorption attributable to water evaporation is about10 when the RH is 80
(4) A linear relationship exists between the initial mois-ture content and the maximum duration of heatradiation before causing first- and second-degreeburn injuries
Symbols
119888119901 Specific heat at constant pressureJ kgminus1 ∘Cminus1119863 Diffusivity of the gas phase in the fabricm2 secminus1
119889119891 Fiber radius mℎ119898 Convective heat transfer coefficient
Wmminus2 ∘Cminus1
Δℎ Enthalpy per unit mass J kgminus1119894119894 Fabric layer119896 Thermal conductivity Wmminus1 ∘Cminus1
119870 Darcian permeability coefficient m2119871 Thickness of the material mV119897 Mass transfer rate from the gaseous phase
to the liquid phase kgmminus3 secminus1V119887 Mass transfer rate from the gaseous phase
to the solid phase kgmminus3 secminus1119897119887 Mass transfer rate from the liquid phase to
the solid phase kgmminus3 secminus1119875119888 Pressure of liquid water Pa
119902rad Incident radiation heat flux from theradiation onto the outer fabric surfaceWmminus2119902minus119894119894 Radiation heat flux from the 119894119894 + 1 fabriclayer to the 119894119894 fabric layer Wmminus2119902+119894119894 Radiation heat flux from the 119894119894 minus 1 fabriclayer to the 119894119894 fabric layer Wmminus2
119894119894 Total radiation heat flux of the 119894119894 fabriclayer Wmminus2
119904 Saturation of the fabric119905 Time s119879 Temperature ∘CV Velocity of liquid water m secminus1119909 Distance m
Greek Symbols
120591 Transmissivity of the fabric120591 Fiber curl120588 Density kgmminus3120576 Absorption coefficient120576119887 Volume fraction120574 Radiative extinction coefficient of the
fabric mminus1120583119897 Dynamic viscosity kgmminus1 secminus1120590 Stefan-Boltzmann constant
120575 = 56705 times 10minus8W ∘Cminus4mminus2120596119887 Blood perfusion [000125m3 secminus1mminus3
tissue]Ω Quantitative measure of the burn damage
at the basal layer of human skin119875 Frequency factor or preexponential factor
secminus1Δ119864 Activation energy for skin119877 Universal gas constant
8315 times 103 J kmolminus1 ∘Cminus1
The Scientific World Journal 11
0007
0006
0005
0004
0003
0002
0001
휀l
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
20 sec25 sec30 sec35 sec40 sec
45 sec50 sec55 sec60 sec70 sec
(a) RH = 30
0007
0006
0005
0004
0003
0002
0001
휀l
0012
0011
0010
0009
0008
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
15 sec18 sec20 sec25 sec30 sec
35 sec40 sec50 sec60 sec70 sec
(b) RH = 50
휀l
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(c) RH = 65
휀l
0018
0016
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(d) RH = 80
Figure 12 Liquid water volume fraction distributions at different times
Subscripts
0 Initial stateeff Effective119897 Liquid water119887 Bound waterV Water vaporskin Skinblood Bloodamb Ambient air
vap Evaporationtrans Transferart Human core119871 Left boundary119877 Right boundary
Conflicts of Interest
The authors declare that they have no conflicts of interest
12 The Scientific World JournalH
eat a
bsor
bed
wat
er ev
apor
atio
n (J
)
3000
2500
2000
1500
1000
500
030 40 50 60 70 80
RH ()
Outer shellMoisture barrier
Thermal barrierTotal
Figure 13 Heat absorbed by water evaporation against RH withfitting line
First-degree burn injury timeSecond-degree burn injury time
Burn
inju
ry ti
me (
s)
136
132
128
124
120
116
112
RH ()minus10 0 10 20 30 40 50 60 70 80 90 100
Figure 14 Burning injury time versus RH
Authorsrsquo Contributions
Dongmei Huang carried out the experiment and numericalsimulation and drafted and revised the manuscript Song Heparticipated in the design of the study and performed thestatistical analysis and helped to draft the manuscript Allauthors read and approved the final manuscript
Acknowledgments
This work was supported by Natural Science Foundationof China (no 51306168) and Zhejiang Provincial NaturalScience Foundation of China under Grant no LY17E060004
Tem
pera
ture
(∘C)
Tem
pera
ture
(∘C)
52
51
50
49
48
47
46
45
44
43
42
41
RH ()20 30 40 50 60 70 80 90
360
359
358
357
356
355
354
353
352
351
350
100 sec50 sec10 sec
Figure 15 Temperature at skin surface
References
[1] L D Xu Y L Xy and M Jiang ldquoProtective clothing for fire-fighter GA10-2014rdquo in GA10-2002 China Standards PressBeijing China 2002
[2] D Huang H Yang Z Qi et al ldquoQuestionnaire on firefightersrsquoprotective clothing in Chinardquo Fire Technology vol 48 no 2 pp255ndash268 2012
[3] C C Guerth-Schacher Evaluation of the Effects of Moisture onthe Thermal Protective Performance of Fire Protective Clothingin Low Level Heat Exposures Fire and Polymer Science NorthCarolina State University Raleigh NC USA 2007
[4] R L Barker C Guerth-Schacher R V Grimes and H Hamou-da ldquoEffects of moisture on the thermal protective performanceof firefighter protective clothing in low-level radiant heatexposuresrdquo Textile Research Journal vol 76 no 1 pp 27ndash312006
[5] Y M Lee and R L Barker ldquoEffect of moisture on the thermalprotective performance of heat-resistant fabricsrdquo Journal of FireSciences vol 4 no 5 pp 315ndash331 1986
[6] J O Stull ldquoThe effect of moisture on firefighter protectiveclothing thermal insulation a review of industry researchrdquoin Performance of Protective Clothing Issues and Priorities forthe 21st Century vol 7th ASTM International West Con-shohocken Pa USA 2000
[7] C Keiser C Becker and R M Rossi ldquoMoisture transport andabsorption in multilayer protective clothing fabricsrdquo TextileResearch Journal vol 78 no 7 pp 604ndash613 2008
[8] Y Y Wang Y J Zong J Li and M M Zhao ldquoEvaluating themoisture transfer property of the multi-layered fabric system infirefighter turnout clothingrdquo Fibres amp Textiles in Eastern Europevol 19 no 6 article 89 pp 101ndash105 2011
[9] Y-Y Wang Y-H Lu J Li and J-H Pan ldquoEffects of airgap entrapped in multilayer fabrics and moisture on thermalprotective performancerdquo Fibers and Polymers vol 13 no 5 pp647ndash652 2012
[10] P Chitrphiromsri and A V Kuznetsov ldquoModeling heat andmoisture transport in firefighter protective clothing during flashfire exposurerdquo Heat and Mass Transfer vol 41 no 3 pp 206ndash215 2005
The Scientific World Journal 13
[11] J Fan X Cheng X Wen and W Sun ldquoAn improved modelof heat and moisture transfer with phase change and mobilecondensates in fibrous insulation and comparison with experi-mental resultsrdquo International Journal of Heat andMass Transfervol 47 no 10-11 pp 2343ndash2352 2004
[12] X Cheng and J Fan ldquoSimulation of heat and moisture transferwith phase change and mobile condensates in fibrous insula-tionrdquo International Journal of Thermal Sciences vol 43 no 7pp 665ndash676 2004
[13] SHeDHuang ZQiH Yang YHu andHZhang ldquoThe effectof air gap thickness on heat transfer in firefightersrsquo protectiveclothing under conditions of short exposure to heatrdquo HeatTransfer Research vol 43 no 8 pp 749ndash765 2012
[14] P Andersson and G Holmstedt ldquoHeat sensing manikin testproberdquo Fire and Materials vol 24 no 4 pp 195ndash199 2000
[15] J R Lawson Fire Fighterrsquos Protective Clothing and ThermalEnvironments of Structural Fire Fighting US Department ofCommerce Technology Administration National Institute ofStandards and Technology 1996
[16] P Chitrphiromsri and A V Kuznetsov ldquoPorous mediummodelfor investigating transient heat and moisture transport infirefighter protective clothing under high-intensity thermalexposurerdquo Journal of Porous Media vol 8 no 5 pp 511ndash5282005
[17] P Chitrphiromsri Modeling of Thermal Performance of Fire-fighter Protective Clothing during the Intense Heat ExposureNorth Carolina State University Raleigh NC USA 2004
[18] H P Harry ldquoAnalysis of tissue and arterial blood temperaturesin the resting human forearmrdquo Journal of Applied Physiologyvol 1 no 2 pp 93ndash122 1948
[19] F C Henriques ldquoStudies of thermal injury the predictabilityand the significance of thermally induced rate processes leadingto irreversible epidermal injuryrdquo Archives of pathology vol 43no 5 pp 489ndash502 1947
[20] S A Teukolsky ldquoStability of the iterated Crank-Nicholsonmethod in numerical relativityrdquo Physical Review DmdashParticlesFields Gravitation and Cosmology vol 61 no 8 Article ID087501 2000
[21] F-L Zhu and W-Y Zhang ldquoModeling heat transfer for heat-resistant fabrics considering pyrolysis effect under an externalheat fluxrdquo Journal of Fire Sciences vol 27 no 1 pp 81ndash96 2009
[22] W Q Tao Heat Transfer Northwestern Polytechnical Univer-sity Press Xirsquoan China 2006
[23] J Liu X Chen andL X Xu ldquoNew thermalwave aspects on bumevaluation of skin subjected to instantaneous heatingrdquo IEEETransactions on Biomedical Engineering vol 46 no 4 pp 420ndash428 1999
[24] A N Takata ldquoDevelopment of criterion for skin burnsrdquo Aero-space Medicine vol 45 no 6 pp 634ndash637 1974
[25] T R Gowrishankar D A Stewart G T Martin and J CWeaver ldquoTransport lattice models of heat transport in skinwith spatially heterogeneous temperature-dependent perfu-sionrdquo BioMedical Engineering Online vol 3 article no 42 2004
[26] D A Torvi and J D Dale ldquoA finite element model of skinsubjected to a flash firerdquo Journal of Biomechanical Engineeringvol 116 no 3 pp 250ndash255 1994
[27] A M Stoll and L C Greene ldquoRelationship between pain andtissue damage due to thermal radiationrdquo Journal of AppliedPhysiology vol 14 no 3 pp 373ndash382 1959
[28] MGasperin andD Juricic ldquoThe uncertainty in burn predictionas a result of variable skin parameters an experimental evalu-ation of burn-protective outfitsrdquo Burns vol 35 no 7 pp 970ndash982 2009
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The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
6 The Scientific World Journal
Table 1 Thermophysical and geometrical properties of fabric [17 21 22]
Property Outer shell Moisture barrier Thermal barrier Comfort layerThickness of the material119871119894119894 [m] 031 times 10minus3 05 times 10minus3 11 times 10minus3 029 times 10minus3
Material of composition XDB602 Aramid fabric coatedwith PTFE film Aramid insulation Cotton shirting
Density 120588119891 [kgmminus3] 67742 21000 7727 41379Thermal conductivity (119896)119891[Wmminus1 Kminus1]
0075 0052 005 0053
Volume fraction 120576119891 0334 0186 0115 015Fibre curl 120591 15 125 1 1Diffusivity of the gas phasein the fabric119863119891 [m2 secminus1] 0 times 10minus14 0 times 10minus14 0 times 10minus14 0 times 10minus14
Fiber radius 119889119891 [m] 16 times 10minus5 16 times 10minus5 16 times 10minus5 16 times 10minus5
Darcian permeabilitycoefficient m2119870119897sat [m2] 10 times 10minus16 10 times 10minus16 10 times 10minus16 10 times 10minus16
Saturation of the fabric 119904119894119903 01 01 01 01Proportional constant ofliquid water absorption 120574119897119904[kgmminus3]
0 times 10minus4 0 times 10minus4 0 times 10minus4 0 times 10minus4
Table 2 Thermophysical and geometrical properties assigned to skin layers [14 15 25ndash28]
Property Epidermis Dermis Subcutaneous tissue BloodDensity 120588skin [kgmminus3] 1200 1200 1000 1060Thermal conductivity(119896)skin [Wmminus1 ∘Cminus1] 023 045 019 mdash
119871 skin [m] 008 times 10minus3 2 times 10minus3 10 times 10minus3 mdash119888119901skin [J kgminus1 ∘Cminus1] 3600 3300 2300 3770120596119887 [m3 secminus1mminus3 tissue] 0 000125 000125 mdash
layer The samples also felt obviously moist when touchedafter remaining for 24 h in circumstances with RH valuesexceeding 65
We designed an apparatus to simulate the process of heattransfer in FPC samples with different initial moisture con-tentsThe experimental setup and the samples were describedin Section 2 To ensure simulation accuracy we comparedthe simulation results with the experimental measurementswhich were corrected before analysis for radiation lossThe comparison model did not consider human skin Theboundary conditions were set identically to the experimentalmeasurements Figure 8 shows the simulated (continuouslines) and experimental (discrete points) temperature profilesat RH = 65 In the figure TCO TCM TCH and TCCrepresent the measurement results at different locations (asseen in Figure 3) while labels preceded by ldquo119878rdquo representthe simulation results The data show that the simulationresults are in good agreement with the experimental resultsThe mechanism for heat and moisture transfer in a systemconsisting of FPC materials air layers and human skinwith different initial moisture content conditions were thenanalyzed using the validated model combined with Pennesrsquo
model The first and second human injury burn times wereestimated using the Henriquesrsquo tissue burn injury model
Figure 9 shows the temperature profiles in different layersat particular moments in time The origin of the 119909-axis isat the outer shell surface as shown in Figure 3 Figure 9(a)shows that the temperatures in the fabric layers decreasesignificantly with distance at different moments in time buttemperatures decrease slowly in the skin layer A clean breakis identifiable between the fabric layer and the skin layerThismay be because heat transfer in fabric layers occurs throughheat conduction radiation and water evaporation and heatabsorption while the only heat transfer model in the skinlayer is heat conduction The temperature difference in skinunder different initial moisture contents is larger at 100 secthan at 10 sec as shown in Figure 9(b) This is because lessinitial moisture content in the samples leads to more heataccumulated in the fabric and the air gap during radiation
We then analyzed the temperature differences underdifferent initial moisture conditions in the fabric and skinlayers with the results shown in Figures 9(c) and 9(d) Thetemperature difference in the fabric under different initialmoisture contents is higher at 10 s than at 100 s These results
The Scientific World Journal 7
0 20 40 60 80 100 120
Time (s)
Tem
pera
ture
(∘C)
400
350
300
250
200
150
100
50
0
Test-TCOTest-TCMTest-TCHTest-TCC
Simulation-TCOSimulation-TCMSimulation-TCHSimulation-TCC
(a) Temperature versus time
00 05 10 15 25 25 30 35 40
Thickness (times10minus3 m)
400
360
280
200
240
320
120
160
80
40
0
Tem
pera
ture
(∘C)
Test-10 secTest-20 secTest-40 secTest-60 secTest-80 secTest-100 secTest-120 sec
Simulation-20 secSimulation-10 sec
Simulation-40 secSimulation-60 secSimulation-80 secSimulation-100 secSimulation-120 sec
(b) Temperature versus thickness
Figure 8 Simulated (continuous lines) and experimental (discrete points) temperature profiles when RH = 65
are in agreement with the accepted point of view that theinitial moisture content of a sample affects heat transfer inthe fabric primarily at the beginning of heating The humanskin begins at 000388m The skin surface temperatureincreases from 309∘C at 10 sec to around 324∘C at 100 secunder different initial moisture contents The skin temper-ature increases as the initial moisture content of the fabricdecreases
Figure 10 shows the profiles for water vapor density in thefabric and air gap layers at different times The data indicatethat the water vapor density decreases as distance from theouter surface increases this occurs because the water vapordensity decreases with temperature which decreases withdistance Higher temperatures providemore energy for waterevaporation The maximum water vapor density in eachlayer increases very rapidly with t reaching a maximum atabout 20 sec under the conditions outlined in this paper asshown in Figure 11 The curve follows a normal distributionbetween about 10 sec and 35 sec After 35 sec the water vapordensity decreases more slowly with time In other words theactuation duration of the initial moisture of FPC samples wasless than 35 sec in this experimental situation
In our experiment the temperature increased whenthe outer shell of the FPC sample was exposed to heatradiation which caused the desorption and evaporationof bound water as well as the evaporation of free liquidwater located in the fabric pores To examine further themechanism of moisture transformation during heating weanalyzed the liquid water volume fraction in the fabricpores at different times as shown in Figure 12 The datashow that the distribution of liquid water in the fabric
unlike that of water vapor is completely noncontinuous Theinitial liquid water volume fraction in each fabric layer isuniform and it increases noticeably with increasing initialmoisture content As the temperature increases the liquidwater volume fraction decreases and the water vapor densityincreases
Figure 13 plots the heat absorbed by water evaporationagainst RH with a fitting line According to the conser-vation equations moisture in the fabric consists of boundliquid and gaseous water Under high temperatures thebound water transfers to a liquid state and the liquid waterevaporates to a gaseous state The enthalpy of the transitionfrom bound water to free liquid water is about 2509 J gminus1under relative humidity of 65 The enthalpy of evaporationper unit mass is about 2400 J gminus1 The bound water andliquid water volume fractions in each fabric layer can bederived from the simulationThen the heat absorbed throughwater evaporation can be determined based on differentinitial moisture conditions as shown in Figure 13 The datademonstrate that the heat absorbed by water evaporationincreases linearly with increasing RH
Figure 12 shows that the time required for the moistureto evaporate completely is about 70 s The heat flux on thematerial surface is 5 kWmminus2 and the dimension of thesample is 230 cm times 230 cmThe total quantity of heat appliedto the surface of the material is about 18515 J Figure 13 showsthat at the RH level of 80 the heat absorbed through waterevaporation is about 2000 J which constitutesmore than 10of the total heat
We also investigated the effect of the initial fabric mois-ture content on the maximum duration of heat radiation
8 The Scientific World Journal
350
300
250
200
150
100
50
0
Tem
pera
ture
(∘C)
100 sec
50 sec
10 sec
0 1 2 3 4 5
Distance (times10minus3 m)
Fabric layer Skin layer
HR = 30 10 secHR = 65 10 secHR = 30 50 secHR = 65 50 sec
HR = 50 10 secHR = 80 10 secHR = 50 50 secHR = 80 50 sec
HR = 30 100 secHR = 65 100 sec
HR = 50 100 secHR = 80 100 sec
(a) Temperature profile in both fabric and skin layers
100 sec
50 sec
10 sec
Fabric layerSkin layer
Distance (times10minus3 m)385 390 395
40
50
60
Tem
pera
ture
(∘C)
HR = 30 10 secHR = 65 10 secHR = 30 50 secHR = 65 50 sec
HR = 50 10 secHR = 80 10 secHR = 50 50 secHR = 80 50 sec
HR = 30 100 secHR = 65 100 sec
HR = 50 100 secHR = 80 100 sec
(b) Temperature profile at fabric-skin interface
00 05 10 15 20 25 30 35
HR = 30HR = 50
HR = 65HR = 80
100 sec
10 sec
Distance (times10minus3 m)
30
40
50
60
70
80
90
100
110
Tem
pera
ture
(∘C)
50
100
150
200
250
300
Tem
pera
ture
(∘C)
(c) Temperature profile in fabric
400 425 450 475 500 525 550 575
HR = 30HR = 50
HR = 65HR = 80
Distance (times10minus3 m)
100 sec
50 sec
10 sec
32
36
40
44
48
52
56
Tem
pera
ture
(∘C)
(d) Temperature profile in skin
Figure 9 Temperature profiles in different layers at specific moments in time
before the wearer sustains first- and second-degree burninjuries The tissue burn injury model is based on work byHenriques [19] and it is calculated according to (11) Takatarsquos[24] criterion was used to determine that first- and second-degree burn injuries occur whenΩ = 053 and 1 respectivelyon the basal layer of the skin (the interface of the epidermisand dermis) Figure 14 shows human skin burn injury timeversus RH The data show that as the initial moisturecontent in the fabric increases the maximum duration ofheat radiation before acquiring first- and second-degree burninjuries increases linearly This occurs because higher initialmoisture in fabric pores allows more energy to be absorbed
by water phase transfers during the heating process Thefirst- and second-degree burn injury time increases 16 secand 18 sec when the RH increases from 0 to 90 Theheat absorbed through water evaporation is 10 of thetotal quantity of heat applied to the surface of the materialHowever the comfort of clothing is usually very low whenthe clothing is set at the environment in which the RH ismore than 80 Therefore the RH is usually less than 80The temperature at the skin surface at different moment isshown in Figure 15We can see that the temperature decreaseswith increasing the initial moisture content The maximumtemperature difference between the RH of 30 and 80
The Scientific World Journal 9
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
120 sec
006
005
004
003
002
001
00000 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec21 sec32 sec50 sec
16 sec25 sec35 sec80 sec
20 sec30 sec40 sec
(a) RH = 30
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
009
008
007
006
005
004
003
002
001
00000 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec20 sec32 sec50 sec
10 sec25 sec35 sec80 sec
16 sec
120 sec
30 sec40 sec
(b) RH = 50
012
010
008
006
004
002
000
OSAL
MB
AL
TB
AL
CL AL휌
(kg
mminus3)
00 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec11 sec15 sec30 sec
5 sec12 sec16 sec50 sec
10 sec13 sec20 sec120 sec
(c) RH = 65
012
010
008
006
004
002
000
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
00 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec21 sec32 sec50 sec
16 sec25 sec35 sec80 sec
20 sec30 sec40 sec
(d) RH = 80
Figure 10 Distributions of water vapor density at different times
condition is about 1 K which is really slight But the effect ofenergy on the skin injury is an accumulation behavior whichleads to the second-degree burn injury time increasing about8 sec
5 Conclusion
We developed a numerical model to investigate the effectsof initial moisture content at each fabric layer on heat andmoisture transfer in FPCmaterialsWe estimated burn injurytimes under different initial moisture contents using our
model combined with Pennesrsquo model and Henriquesrsquo tissueburn injury model We can draw the following conclusions
(1) Initial moisture content in each FPC fabric layerincreases linearly as the RH of the storage locationincreases
(2) We developed a comprehensive model to simulateheat andmoisture transfer in FPC and the simulationresults show fairly good agreement with the experi-mental results
10 The Scientific World Journal
024
022
020
018
016
014
012
010
008
006
004
002
0000 20 40 60 80 100 120
Time (s)
HR = 30HR = 50
HR = 65HR = 80
휌
(kg
mminus3)
Figure 11 Profiles of water vapor density versus time at a distance of 056 times 10minus3m
(3) Water vapor is distributed both in the fabric layersand in the air layer while free liquid water dispersesonly in the fabric layers Water vapor density ismainly due to evaporation from free liquid waterduring the experiment and it decreases as initialmoisture content increases The total amount of heatabsorption attributable to water evaporation is about10 when the RH is 80
(4) A linear relationship exists between the initial mois-ture content and the maximum duration of heatradiation before causing first- and second-degreeburn injuries
Symbols
119888119901 Specific heat at constant pressureJ kgminus1 ∘Cminus1119863 Diffusivity of the gas phase in the fabricm2 secminus1
119889119891 Fiber radius mℎ119898 Convective heat transfer coefficient
Wmminus2 ∘Cminus1
Δℎ Enthalpy per unit mass J kgminus1119894119894 Fabric layer119896 Thermal conductivity Wmminus1 ∘Cminus1
119870 Darcian permeability coefficient m2119871 Thickness of the material mV119897 Mass transfer rate from the gaseous phase
to the liquid phase kgmminus3 secminus1V119887 Mass transfer rate from the gaseous phase
to the solid phase kgmminus3 secminus1119897119887 Mass transfer rate from the liquid phase to
the solid phase kgmminus3 secminus1119875119888 Pressure of liquid water Pa
119902rad Incident radiation heat flux from theradiation onto the outer fabric surfaceWmminus2119902minus119894119894 Radiation heat flux from the 119894119894 + 1 fabriclayer to the 119894119894 fabric layer Wmminus2119902+119894119894 Radiation heat flux from the 119894119894 minus 1 fabriclayer to the 119894119894 fabric layer Wmminus2
119894119894 Total radiation heat flux of the 119894119894 fabriclayer Wmminus2
119904 Saturation of the fabric119905 Time s119879 Temperature ∘CV Velocity of liquid water m secminus1119909 Distance m
Greek Symbols
120591 Transmissivity of the fabric120591 Fiber curl120588 Density kgmminus3120576 Absorption coefficient120576119887 Volume fraction120574 Radiative extinction coefficient of the
fabric mminus1120583119897 Dynamic viscosity kgmminus1 secminus1120590 Stefan-Boltzmann constant
120575 = 56705 times 10minus8W ∘Cminus4mminus2120596119887 Blood perfusion [000125m3 secminus1mminus3
tissue]Ω Quantitative measure of the burn damage
at the basal layer of human skin119875 Frequency factor or preexponential factor
secminus1Δ119864 Activation energy for skin119877 Universal gas constant
8315 times 103 J kmolminus1 ∘Cminus1
The Scientific World Journal 11
0007
0006
0005
0004
0003
0002
0001
휀l
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
20 sec25 sec30 sec35 sec40 sec
45 sec50 sec55 sec60 sec70 sec
(a) RH = 30
0007
0006
0005
0004
0003
0002
0001
휀l
0012
0011
0010
0009
0008
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
15 sec18 sec20 sec25 sec30 sec
35 sec40 sec50 sec60 sec70 sec
(b) RH = 50
휀l
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(c) RH = 65
휀l
0018
0016
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(d) RH = 80
Figure 12 Liquid water volume fraction distributions at different times
Subscripts
0 Initial stateeff Effective119897 Liquid water119887 Bound waterV Water vaporskin Skinblood Bloodamb Ambient air
vap Evaporationtrans Transferart Human core119871 Left boundary119877 Right boundary
Conflicts of Interest
The authors declare that they have no conflicts of interest
12 The Scientific World JournalH
eat a
bsor
bed
wat
er ev
apor
atio
n (J
)
3000
2500
2000
1500
1000
500
030 40 50 60 70 80
RH ()
Outer shellMoisture barrier
Thermal barrierTotal
Figure 13 Heat absorbed by water evaporation against RH withfitting line
First-degree burn injury timeSecond-degree burn injury time
Burn
inju
ry ti
me (
s)
136
132
128
124
120
116
112
RH ()minus10 0 10 20 30 40 50 60 70 80 90 100
Figure 14 Burning injury time versus RH
Authorsrsquo Contributions
Dongmei Huang carried out the experiment and numericalsimulation and drafted and revised the manuscript Song Heparticipated in the design of the study and performed thestatistical analysis and helped to draft the manuscript Allauthors read and approved the final manuscript
Acknowledgments
This work was supported by Natural Science Foundationof China (no 51306168) and Zhejiang Provincial NaturalScience Foundation of China under Grant no LY17E060004
Tem
pera
ture
(∘C)
Tem
pera
ture
(∘C)
52
51
50
49
48
47
46
45
44
43
42
41
RH ()20 30 40 50 60 70 80 90
360
359
358
357
356
355
354
353
352
351
350
100 sec50 sec10 sec
Figure 15 Temperature at skin surface
References
[1] L D Xu Y L Xy and M Jiang ldquoProtective clothing for fire-fighter GA10-2014rdquo in GA10-2002 China Standards PressBeijing China 2002
[2] D Huang H Yang Z Qi et al ldquoQuestionnaire on firefightersrsquoprotective clothing in Chinardquo Fire Technology vol 48 no 2 pp255ndash268 2012
[3] C C Guerth-Schacher Evaluation of the Effects of Moisture onthe Thermal Protective Performance of Fire Protective Clothingin Low Level Heat Exposures Fire and Polymer Science NorthCarolina State University Raleigh NC USA 2007
[4] R L Barker C Guerth-Schacher R V Grimes and H Hamou-da ldquoEffects of moisture on the thermal protective performanceof firefighter protective clothing in low-level radiant heatexposuresrdquo Textile Research Journal vol 76 no 1 pp 27ndash312006
[5] Y M Lee and R L Barker ldquoEffect of moisture on the thermalprotective performance of heat-resistant fabricsrdquo Journal of FireSciences vol 4 no 5 pp 315ndash331 1986
[6] J O Stull ldquoThe effect of moisture on firefighter protectiveclothing thermal insulation a review of industry researchrdquoin Performance of Protective Clothing Issues and Priorities forthe 21st Century vol 7th ASTM International West Con-shohocken Pa USA 2000
[7] C Keiser C Becker and R M Rossi ldquoMoisture transport andabsorption in multilayer protective clothing fabricsrdquo TextileResearch Journal vol 78 no 7 pp 604ndash613 2008
[8] Y Y Wang Y J Zong J Li and M M Zhao ldquoEvaluating themoisture transfer property of the multi-layered fabric system infirefighter turnout clothingrdquo Fibres amp Textiles in Eastern Europevol 19 no 6 article 89 pp 101ndash105 2011
[9] Y-Y Wang Y-H Lu J Li and J-H Pan ldquoEffects of airgap entrapped in multilayer fabrics and moisture on thermalprotective performancerdquo Fibers and Polymers vol 13 no 5 pp647ndash652 2012
[10] P Chitrphiromsri and A V Kuznetsov ldquoModeling heat andmoisture transport in firefighter protective clothing during flashfire exposurerdquo Heat and Mass Transfer vol 41 no 3 pp 206ndash215 2005
The Scientific World Journal 13
[11] J Fan X Cheng X Wen and W Sun ldquoAn improved modelof heat and moisture transfer with phase change and mobilecondensates in fibrous insulation and comparison with experi-mental resultsrdquo International Journal of Heat andMass Transfervol 47 no 10-11 pp 2343ndash2352 2004
[12] X Cheng and J Fan ldquoSimulation of heat and moisture transferwith phase change and mobile condensates in fibrous insula-tionrdquo International Journal of Thermal Sciences vol 43 no 7pp 665ndash676 2004
[13] SHeDHuang ZQiH Yang YHu andHZhang ldquoThe effectof air gap thickness on heat transfer in firefightersrsquo protectiveclothing under conditions of short exposure to heatrdquo HeatTransfer Research vol 43 no 8 pp 749ndash765 2012
[14] P Andersson and G Holmstedt ldquoHeat sensing manikin testproberdquo Fire and Materials vol 24 no 4 pp 195ndash199 2000
[15] J R Lawson Fire Fighterrsquos Protective Clothing and ThermalEnvironments of Structural Fire Fighting US Department ofCommerce Technology Administration National Institute ofStandards and Technology 1996
[16] P Chitrphiromsri and A V Kuznetsov ldquoPorous mediummodelfor investigating transient heat and moisture transport infirefighter protective clothing under high-intensity thermalexposurerdquo Journal of Porous Media vol 8 no 5 pp 511ndash5282005
[17] P Chitrphiromsri Modeling of Thermal Performance of Fire-fighter Protective Clothing during the Intense Heat ExposureNorth Carolina State University Raleigh NC USA 2004
[18] H P Harry ldquoAnalysis of tissue and arterial blood temperaturesin the resting human forearmrdquo Journal of Applied Physiologyvol 1 no 2 pp 93ndash122 1948
[19] F C Henriques ldquoStudies of thermal injury the predictabilityand the significance of thermally induced rate processes leadingto irreversible epidermal injuryrdquo Archives of pathology vol 43no 5 pp 489ndash502 1947
[20] S A Teukolsky ldquoStability of the iterated Crank-Nicholsonmethod in numerical relativityrdquo Physical Review DmdashParticlesFields Gravitation and Cosmology vol 61 no 8 Article ID087501 2000
[21] F-L Zhu and W-Y Zhang ldquoModeling heat transfer for heat-resistant fabrics considering pyrolysis effect under an externalheat fluxrdquo Journal of Fire Sciences vol 27 no 1 pp 81ndash96 2009
[22] W Q Tao Heat Transfer Northwestern Polytechnical Univer-sity Press Xirsquoan China 2006
[23] J Liu X Chen andL X Xu ldquoNew thermalwave aspects on bumevaluation of skin subjected to instantaneous heatingrdquo IEEETransactions on Biomedical Engineering vol 46 no 4 pp 420ndash428 1999
[24] A N Takata ldquoDevelopment of criterion for skin burnsrdquo Aero-space Medicine vol 45 no 6 pp 634ndash637 1974
[25] T R Gowrishankar D A Stewart G T Martin and J CWeaver ldquoTransport lattice models of heat transport in skinwith spatially heterogeneous temperature-dependent perfu-sionrdquo BioMedical Engineering Online vol 3 article no 42 2004
[26] D A Torvi and J D Dale ldquoA finite element model of skinsubjected to a flash firerdquo Journal of Biomechanical Engineeringvol 116 no 3 pp 250ndash255 1994
[27] A M Stoll and L C Greene ldquoRelationship between pain andtissue damage due to thermal radiationrdquo Journal of AppliedPhysiology vol 14 no 3 pp 373ndash382 1959
[28] MGasperin andD Juricic ldquoThe uncertainty in burn predictionas a result of variable skin parameters an experimental evalu-ation of burn-protective outfitsrdquo Burns vol 35 no 7 pp 970ndash982 2009
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Renewable Energy
Submit your manuscripts athttpswwwhindawicom
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Volume 201Hindawi Publishing Corporation httpwwwhindawicom Volume 201
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High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
The Scientific World Journal 7
0 20 40 60 80 100 120
Time (s)
Tem
pera
ture
(∘C)
400
350
300
250
200
150
100
50
0
Test-TCOTest-TCMTest-TCHTest-TCC
Simulation-TCOSimulation-TCMSimulation-TCHSimulation-TCC
(a) Temperature versus time
00 05 10 15 25 25 30 35 40
Thickness (times10minus3 m)
400
360
280
200
240
320
120
160
80
40
0
Tem
pera
ture
(∘C)
Test-10 secTest-20 secTest-40 secTest-60 secTest-80 secTest-100 secTest-120 sec
Simulation-20 secSimulation-10 sec
Simulation-40 secSimulation-60 secSimulation-80 secSimulation-100 secSimulation-120 sec
(b) Temperature versus thickness
Figure 8 Simulated (continuous lines) and experimental (discrete points) temperature profiles when RH = 65
are in agreement with the accepted point of view that theinitial moisture content of a sample affects heat transfer inthe fabric primarily at the beginning of heating The humanskin begins at 000388m The skin surface temperatureincreases from 309∘C at 10 sec to around 324∘C at 100 secunder different initial moisture contents The skin temper-ature increases as the initial moisture content of the fabricdecreases
Figure 10 shows the profiles for water vapor density in thefabric and air gap layers at different times The data indicatethat the water vapor density decreases as distance from theouter surface increases this occurs because the water vapordensity decreases with temperature which decreases withdistance Higher temperatures providemore energy for waterevaporation The maximum water vapor density in eachlayer increases very rapidly with t reaching a maximum atabout 20 sec under the conditions outlined in this paper asshown in Figure 11 The curve follows a normal distributionbetween about 10 sec and 35 sec After 35 sec the water vapordensity decreases more slowly with time In other words theactuation duration of the initial moisture of FPC samples wasless than 35 sec in this experimental situation
In our experiment the temperature increased whenthe outer shell of the FPC sample was exposed to heatradiation which caused the desorption and evaporationof bound water as well as the evaporation of free liquidwater located in the fabric pores To examine further themechanism of moisture transformation during heating weanalyzed the liquid water volume fraction in the fabricpores at different times as shown in Figure 12 The datashow that the distribution of liquid water in the fabric
unlike that of water vapor is completely noncontinuous Theinitial liquid water volume fraction in each fabric layer isuniform and it increases noticeably with increasing initialmoisture content As the temperature increases the liquidwater volume fraction decreases and the water vapor densityincreases
Figure 13 plots the heat absorbed by water evaporationagainst RH with a fitting line According to the conser-vation equations moisture in the fabric consists of boundliquid and gaseous water Under high temperatures thebound water transfers to a liquid state and the liquid waterevaporates to a gaseous state The enthalpy of the transitionfrom bound water to free liquid water is about 2509 J gminus1under relative humidity of 65 The enthalpy of evaporationper unit mass is about 2400 J gminus1 The bound water andliquid water volume fractions in each fabric layer can bederived from the simulationThen the heat absorbed throughwater evaporation can be determined based on differentinitial moisture conditions as shown in Figure 13 The datademonstrate that the heat absorbed by water evaporationincreases linearly with increasing RH
Figure 12 shows that the time required for the moistureto evaporate completely is about 70 s The heat flux on thematerial surface is 5 kWmminus2 and the dimension of thesample is 230 cm times 230 cmThe total quantity of heat appliedto the surface of the material is about 18515 J Figure 13 showsthat at the RH level of 80 the heat absorbed through waterevaporation is about 2000 J which constitutesmore than 10of the total heat
We also investigated the effect of the initial fabric mois-ture content on the maximum duration of heat radiation
8 The Scientific World Journal
350
300
250
200
150
100
50
0
Tem
pera
ture
(∘C)
100 sec
50 sec
10 sec
0 1 2 3 4 5
Distance (times10minus3 m)
Fabric layer Skin layer
HR = 30 10 secHR = 65 10 secHR = 30 50 secHR = 65 50 sec
HR = 50 10 secHR = 80 10 secHR = 50 50 secHR = 80 50 sec
HR = 30 100 secHR = 65 100 sec
HR = 50 100 secHR = 80 100 sec
(a) Temperature profile in both fabric and skin layers
100 sec
50 sec
10 sec
Fabric layerSkin layer
Distance (times10minus3 m)385 390 395
40
50
60
Tem
pera
ture
(∘C)
HR = 30 10 secHR = 65 10 secHR = 30 50 secHR = 65 50 sec
HR = 50 10 secHR = 80 10 secHR = 50 50 secHR = 80 50 sec
HR = 30 100 secHR = 65 100 sec
HR = 50 100 secHR = 80 100 sec
(b) Temperature profile at fabric-skin interface
00 05 10 15 20 25 30 35
HR = 30HR = 50
HR = 65HR = 80
100 sec
10 sec
Distance (times10minus3 m)
30
40
50
60
70
80
90
100
110
Tem
pera
ture
(∘C)
50
100
150
200
250
300
Tem
pera
ture
(∘C)
(c) Temperature profile in fabric
400 425 450 475 500 525 550 575
HR = 30HR = 50
HR = 65HR = 80
Distance (times10minus3 m)
100 sec
50 sec
10 sec
32
36
40
44
48
52
56
Tem
pera
ture
(∘C)
(d) Temperature profile in skin
Figure 9 Temperature profiles in different layers at specific moments in time
before the wearer sustains first- and second-degree burninjuries The tissue burn injury model is based on work byHenriques [19] and it is calculated according to (11) Takatarsquos[24] criterion was used to determine that first- and second-degree burn injuries occur whenΩ = 053 and 1 respectivelyon the basal layer of the skin (the interface of the epidermisand dermis) Figure 14 shows human skin burn injury timeversus RH The data show that as the initial moisturecontent in the fabric increases the maximum duration ofheat radiation before acquiring first- and second-degree burninjuries increases linearly This occurs because higher initialmoisture in fabric pores allows more energy to be absorbed
by water phase transfers during the heating process Thefirst- and second-degree burn injury time increases 16 secand 18 sec when the RH increases from 0 to 90 Theheat absorbed through water evaporation is 10 of thetotal quantity of heat applied to the surface of the materialHowever the comfort of clothing is usually very low whenthe clothing is set at the environment in which the RH ismore than 80 Therefore the RH is usually less than 80The temperature at the skin surface at different moment isshown in Figure 15We can see that the temperature decreaseswith increasing the initial moisture content The maximumtemperature difference between the RH of 30 and 80
The Scientific World Journal 9
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
120 sec
006
005
004
003
002
001
00000 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec21 sec32 sec50 sec
16 sec25 sec35 sec80 sec
20 sec30 sec40 sec
(a) RH = 30
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
009
008
007
006
005
004
003
002
001
00000 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec20 sec32 sec50 sec
10 sec25 sec35 sec80 sec
16 sec
120 sec
30 sec40 sec
(b) RH = 50
012
010
008
006
004
002
000
OSAL
MB
AL
TB
AL
CL AL휌
(kg
mminus3)
00 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec11 sec15 sec30 sec
5 sec12 sec16 sec50 sec
10 sec13 sec20 sec120 sec
(c) RH = 65
012
010
008
006
004
002
000
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
00 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec21 sec32 sec50 sec
16 sec25 sec35 sec80 sec
20 sec30 sec40 sec
(d) RH = 80
Figure 10 Distributions of water vapor density at different times
condition is about 1 K which is really slight But the effect ofenergy on the skin injury is an accumulation behavior whichleads to the second-degree burn injury time increasing about8 sec
5 Conclusion
We developed a numerical model to investigate the effectsof initial moisture content at each fabric layer on heat andmoisture transfer in FPCmaterialsWe estimated burn injurytimes under different initial moisture contents using our
model combined with Pennesrsquo model and Henriquesrsquo tissueburn injury model We can draw the following conclusions
(1) Initial moisture content in each FPC fabric layerincreases linearly as the RH of the storage locationincreases
(2) We developed a comprehensive model to simulateheat andmoisture transfer in FPC and the simulationresults show fairly good agreement with the experi-mental results
10 The Scientific World Journal
024
022
020
018
016
014
012
010
008
006
004
002
0000 20 40 60 80 100 120
Time (s)
HR = 30HR = 50
HR = 65HR = 80
휌
(kg
mminus3)
Figure 11 Profiles of water vapor density versus time at a distance of 056 times 10minus3m
(3) Water vapor is distributed both in the fabric layersand in the air layer while free liquid water dispersesonly in the fabric layers Water vapor density ismainly due to evaporation from free liquid waterduring the experiment and it decreases as initialmoisture content increases The total amount of heatabsorption attributable to water evaporation is about10 when the RH is 80
(4) A linear relationship exists between the initial mois-ture content and the maximum duration of heatradiation before causing first- and second-degreeburn injuries
Symbols
119888119901 Specific heat at constant pressureJ kgminus1 ∘Cminus1119863 Diffusivity of the gas phase in the fabricm2 secminus1
119889119891 Fiber radius mℎ119898 Convective heat transfer coefficient
Wmminus2 ∘Cminus1
Δℎ Enthalpy per unit mass J kgminus1119894119894 Fabric layer119896 Thermal conductivity Wmminus1 ∘Cminus1
119870 Darcian permeability coefficient m2119871 Thickness of the material mV119897 Mass transfer rate from the gaseous phase
to the liquid phase kgmminus3 secminus1V119887 Mass transfer rate from the gaseous phase
to the solid phase kgmminus3 secminus1119897119887 Mass transfer rate from the liquid phase to
the solid phase kgmminus3 secminus1119875119888 Pressure of liquid water Pa
119902rad Incident radiation heat flux from theradiation onto the outer fabric surfaceWmminus2119902minus119894119894 Radiation heat flux from the 119894119894 + 1 fabriclayer to the 119894119894 fabric layer Wmminus2119902+119894119894 Radiation heat flux from the 119894119894 minus 1 fabriclayer to the 119894119894 fabric layer Wmminus2
119894119894 Total radiation heat flux of the 119894119894 fabriclayer Wmminus2
119904 Saturation of the fabric119905 Time s119879 Temperature ∘CV Velocity of liquid water m secminus1119909 Distance m
Greek Symbols
120591 Transmissivity of the fabric120591 Fiber curl120588 Density kgmminus3120576 Absorption coefficient120576119887 Volume fraction120574 Radiative extinction coefficient of the
fabric mminus1120583119897 Dynamic viscosity kgmminus1 secminus1120590 Stefan-Boltzmann constant
120575 = 56705 times 10minus8W ∘Cminus4mminus2120596119887 Blood perfusion [000125m3 secminus1mminus3
tissue]Ω Quantitative measure of the burn damage
at the basal layer of human skin119875 Frequency factor or preexponential factor
secminus1Δ119864 Activation energy for skin119877 Universal gas constant
8315 times 103 J kmolminus1 ∘Cminus1
The Scientific World Journal 11
0007
0006
0005
0004
0003
0002
0001
휀l
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
20 sec25 sec30 sec35 sec40 sec
45 sec50 sec55 sec60 sec70 sec
(a) RH = 30
0007
0006
0005
0004
0003
0002
0001
휀l
0012
0011
0010
0009
0008
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
15 sec18 sec20 sec25 sec30 sec
35 sec40 sec50 sec60 sec70 sec
(b) RH = 50
휀l
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(c) RH = 65
휀l
0018
0016
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(d) RH = 80
Figure 12 Liquid water volume fraction distributions at different times
Subscripts
0 Initial stateeff Effective119897 Liquid water119887 Bound waterV Water vaporskin Skinblood Bloodamb Ambient air
vap Evaporationtrans Transferart Human core119871 Left boundary119877 Right boundary
Conflicts of Interest
The authors declare that they have no conflicts of interest
12 The Scientific World JournalH
eat a
bsor
bed
wat
er ev
apor
atio
n (J
)
3000
2500
2000
1500
1000
500
030 40 50 60 70 80
RH ()
Outer shellMoisture barrier
Thermal barrierTotal
Figure 13 Heat absorbed by water evaporation against RH withfitting line
First-degree burn injury timeSecond-degree burn injury time
Burn
inju
ry ti
me (
s)
136
132
128
124
120
116
112
RH ()minus10 0 10 20 30 40 50 60 70 80 90 100
Figure 14 Burning injury time versus RH
Authorsrsquo Contributions
Dongmei Huang carried out the experiment and numericalsimulation and drafted and revised the manuscript Song Heparticipated in the design of the study and performed thestatistical analysis and helped to draft the manuscript Allauthors read and approved the final manuscript
Acknowledgments
This work was supported by Natural Science Foundationof China (no 51306168) and Zhejiang Provincial NaturalScience Foundation of China under Grant no LY17E060004
Tem
pera
ture
(∘C)
Tem
pera
ture
(∘C)
52
51
50
49
48
47
46
45
44
43
42
41
RH ()20 30 40 50 60 70 80 90
360
359
358
357
356
355
354
353
352
351
350
100 sec50 sec10 sec
Figure 15 Temperature at skin surface
References
[1] L D Xu Y L Xy and M Jiang ldquoProtective clothing for fire-fighter GA10-2014rdquo in GA10-2002 China Standards PressBeijing China 2002
[2] D Huang H Yang Z Qi et al ldquoQuestionnaire on firefightersrsquoprotective clothing in Chinardquo Fire Technology vol 48 no 2 pp255ndash268 2012
[3] C C Guerth-Schacher Evaluation of the Effects of Moisture onthe Thermal Protective Performance of Fire Protective Clothingin Low Level Heat Exposures Fire and Polymer Science NorthCarolina State University Raleigh NC USA 2007
[4] R L Barker C Guerth-Schacher R V Grimes and H Hamou-da ldquoEffects of moisture on the thermal protective performanceof firefighter protective clothing in low-level radiant heatexposuresrdquo Textile Research Journal vol 76 no 1 pp 27ndash312006
[5] Y M Lee and R L Barker ldquoEffect of moisture on the thermalprotective performance of heat-resistant fabricsrdquo Journal of FireSciences vol 4 no 5 pp 315ndash331 1986
[6] J O Stull ldquoThe effect of moisture on firefighter protectiveclothing thermal insulation a review of industry researchrdquoin Performance of Protective Clothing Issues and Priorities forthe 21st Century vol 7th ASTM International West Con-shohocken Pa USA 2000
[7] C Keiser C Becker and R M Rossi ldquoMoisture transport andabsorption in multilayer protective clothing fabricsrdquo TextileResearch Journal vol 78 no 7 pp 604ndash613 2008
[8] Y Y Wang Y J Zong J Li and M M Zhao ldquoEvaluating themoisture transfer property of the multi-layered fabric system infirefighter turnout clothingrdquo Fibres amp Textiles in Eastern Europevol 19 no 6 article 89 pp 101ndash105 2011
[9] Y-Y Wang Y-H Lu J Li and J-H Pan ldquoEffects of airgap entrapped in multilayer fabrics and moisture on thermalprotective performancerdquo Fibers and Polymers vol 13 no 5 pp647ndash652 2012
[10] P Chitrphiromsri and A V Kuznetsov ldquoModeling heat andmoisture transport in firefighter protective clothing during flashfire exposurerdquo Heat and Mass Transfer vol 41 no 3 pp 206ndash215 2005
The Scientific World Journal 13
[11] J Fan X Cheng X Wen and W Sun ldquoAn improved modelof heat and moisture transfer with phase change and mobilecondensates in fibrous insulation and comparison with experi-mental resultsrdquo International Journal of Heat andMass Transfervol 47 no 10-11 pp 2343ndash2352 2004
[12] X Cheng and J Fan ldquoSimulation of heat and moisture transferwith phase change and mobile condensates in fibrous insula-tionrdquo International Journal of Thermal Sciences vol 43 no 7pp 665ndash676 2004
[13] SHeDHuang ZQiH Yang YHu andHZhang ldquoThe effectof air gap thickness on heat transfer in firefightersrsquo protectiveclothing under conditions of short exposure to heatrdquo HeatTransfer Research vol 43 no 8 pp 749ndash765 2012
[14] P Andersson and G Holmstedt ldquoHeat sensing manikin testproberdquo Fire and Materials vol 24 no 4 pp 195ndash199 2000
[15] J R Lawson Fire Fighterrsquos Protective Clothing and ThermalEnvironments of Structural Fire Fighting US Department ofCommerce Technology Administration National Institute ofStandards and Technology 1996
[16] P Chitrphiromsri and A V Kuznetsov ldquoPorous mediummodelfor investigating transient heat and moisture transport infirefighter protective clothing under high-intensity thermalexposurerdquo Journal of Porous Media vol 8 no 5 pp 511ndash5282005
[17] P Chitrphiromsri Modeling of Thermal Performance of Fire-fighter Protective Clothing during the Intense Heat ExposureNorth Carolina State University Raleigh NC USA 2004
[18] H P Harry ldquoAnalysis of tissue and arterial blood temperaturesin the resting human forearmrdquo Journal of Applied Physiologyvol 1 no 2 pp 93ndash122 1948
[19] F C Henriques ldquoStudies of thermal injury the predictabilityand the significance of thermally induced rate processes leadingto irreversible epidermal injuryrdquo Archives of pathology vol 43no 5 pp 489ndash502 1947
[20] S A Teukolsky ldquoStability of the iterated Crank-Nicholsonmethod in numerical relativityrdquo Physical Review DmdashParticlesFields Gravitation and Cosmology vol 61 no 8 Article ID087501 2000
[21] F-L Zhu and W-Y Zhang ldquoModeling heat transfer for heat-resistant fabrics considering pyrolysis effect under an externalheat fluxrdquo Journal of Fire Sciences vol 27 no 1 pp 81ndash96 2009
[22] W Q Tao Heat Transfer Northwestern Polytechnical Univer-sity Press Xirsquoan China 2006
[23] J Liu X Chen andL X Xu ldquoNew thermalwave aspects on bumevaluation of skin subjected to instantaneous heatingrdquo IEEETransactions on Biomedical Engineering vol 46 no 4 pp 420ndash428 1999
[24] A N Takata ldquoDevelopment of criterion for skin burnsrdquo Aero-space Medicine vol 45 no 6 pp 634ndash637 1974
[25] T R Gowrishankar D A Stewart G T Martin and J CWeaver ldquoTransport lattice models of heat transport in skinwith spatially heterogeneous temperature-dependent perfu-sionrdquo BioMedical Engineering Online vol 3 article no 42 2004
[26] D A Torvi and J D Dale ldquoA finite element model of skinsubjected to a flash firerdquo Journal of Biomechanical Engineeringvol 116 no 3 pp 250ndash255 1994
[27] A M Stoll and L C Greene ldquoRelationship between pain andtissue damage due to thermal radiationrdquo Journal of AppliedPhysiology vol 14 no 3 pp 373ndash382 1959
[28] MGasperin andD Juricic ldquoThe uncertainty in burn predictionas a result of variable skin parameters an experimental evalu-ation of burn-protective outfitsrdquo Burns vol 35 no 7 pp 970ndash982 2009
TribologyAdvances in
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Journal ofPetroleum Engineering
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
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Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Renewable Energy
Submit your manuscripts athttpswwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
StructuresJournal of
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal of
Volume 201Hindawi Publishing Corporation httpwwwhindawicom Volume 201
International Journal ofInternational Journal of
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Nuclear InstallationsScience and Technology of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solar EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Wind EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nuclear EnergyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
8 The Scientific World Journal
350
300
250
200
150
100
50
0
Tem
pera
ture
(∘C)
100 sec
50 sec
10 sec
0 1 2 3 4 5
Distance (times10minus3 m)
Fabric layer Skin layer
HR = 30 10 secHR = 65 10 secHR = 30 50 secHR = 65 50 sec
HR = 50 10 secHR = 80 10 secHR = 50 50 secHR = 80 50 sec
HR = 30 100 secHR = 65 100 sec
HR = 50 100 secHR = 80 100 sec
(a) Temperature profile in both fabric and skin layers
100 sec
50 sec
10 sec
Fabric layerSkin layer
Distance (times10minus3 m)385 390 395
40
50
60
Tem
pera
ture
(∘C)
HR = 30 10 secHR = 65 10 secHR = 30 50 secHR = 65 50 sec
HR = 50 10 secHR = 80 10 secHR = 50 50 secHR = 80 50 sec
HR = 30 100 secHR = 65 100 sec
HR = 50 100 secHR = 80 100 sec
(b) Temperature profile at fabric-skin interface
00 05 10 15 20 25 30 35
HR = 30HR = 50
HR = 65HR = 80
100 sec
10 sec
Distance (times10minus3 m)
30
40
50
60
70
80
90
100
110
Tem
pera
ture
(∘C)
50
100
150
200
250
300
Tem
pera
ture
(∘C)
(c) Temperature profile in fabric
400 425 450 475 500 525 550 575
HR = 30HR = 50
HR = 65HR = 80
Distance (times10minus3 m)
100 sec
50 sec
10 sec
32
36
40
44
48
52
56
Tem
pera
ture
(∘C)
(d) Temperature profile in skin
Figure 9 Temperature profiles in different layers at specific moments in time
before the wearer sustains first- and second-degree burninjuries The tissue burn injury model is based on work byHenriques [19] and it is calculated according to (11) Takatarsquos[24] criterion was used to determine that first- and second-degree burn injuries occur whenΩ = 053 and 1 respectivelyon the basal layer of the skin (the interface of the epidermisand dermis) Figure 14 shows human skin burn injury timeversus RH The data show that as the initial moisturecontent in the fabric increases the maximum duration ofheat radiation before acquiring first- and second-degree burninjuries increases linearly This occurs because higher initialmoisture in fabric pores allows more energy to be absorbed
by water phase transfers during the heating process Thefirst- and second-degree burn injury time increases 16 secand 18 sec when the RH increases from 0 to 90 Theheat absorbed through water evaporation is 10 of thetotal quantity of heat applied to the surface of the materialHowever the comfort of clothing is usually very low whenthe clothing is set at the environment in which the RH ismore than 80 Therefore the RH is usually less than 80The temperature at the skin surface at different moment isshown in Figure 15We can see that the temperature decreaseswith increasing the initial moisture content The maximumtemperature difference between the RH of 30 and 80
The Scientific World Journal 9
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
120 sec
006
005
004
003
002
001
00000 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec21 sec32 sec50 sec
16 sec25 sec35 sec80 sec
20 sec30 sec40 sec
(a) RH = 30
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
009
008
007
006
005
004
003
002
001
00000 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec20 sec32 sec50 sec
10 sec25 sec35 sec80 sec
16 sec
120 sec
30 sec40 sec
(b) RH = 50
012
010
008
006
004
002
000
OSAL
MB
AL
TB
AL
CL AL휌
(kg
mminus3)
00 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec11 sec15 sec30 sec
5 sec12 sec16 sec50 sec
10 sec13 sec20 sec120 sec
(c) RH = 65
012
010
008
006
004
002
000
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
00 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec21 sec32 sec50 sec
16 sec25 sec35 sec80 sec
20 sec30 sec40 sec
(d) RH = 80
Figure 10 Distributions of water vapor density at different times
condition is about 1 K which is really slight But the effect ofenergy on the skin injury is an accumulation behavior whichleads to the second-degree burn injury time increasing about8 sec
5 Conclusion
We developed a numerical model to investigate the effectsof initial moisture content at each fabric layer on heat andmoisture transfer in FPCmaterialsWe estimated burn injurytimes under different initial moisture contents using our
model combined with Pennesrsquo model and Henriquesrsquo tissueburn injury model We can draw the following conclusions
(1) Initial moisture content in each FPC fabric layerincreases linearly as the RH of the storage locationincreases
(2) We developed a comprehensive model to simulateheat andmoisture transfer in FPC and the simulationresults show fairly good agreement with the experi-mental results
10 The Scientific World Journal
024
022
020
018
016
014
012
010
008
006
004
002
0000 20 40 60 80 100 120
Time (s)
HR = 30HR = 50
HR = 65HR = 80
휌
(kg
mminus3)
Figure 11 Profiles of water vapor density versus time at a distance of 056 times 10minus3m
(3) Water vapor is distributed both in the fabric layersand in the air layer while free liquid water dispersesonly in the fabric layers Water vapor density ismainly due to evaporation from free liquid waterduring the experiment and it decreases as initialmoisture content increases The total amount of heatabsorption attributable to water evaporation is about10 when the RH is 80
(4) A linear relationship exists between the initial mois-ture content and the maximum duration of heatradiation before causing first- and second-degreeburn injuries
Symbols
119888119901 Specific heat at constant pressureJ kgminus1 ∘Cminus1119863 Diffusivity of the gas phase in the fabricm2 secminus1
119889119891 Fiber radius mℎ119898 Convective heat transfer coefficient
Wmminus2 ∘Cminus1
Δℎ Enthalpy per unit mass J kgminus1119894119894 Fabric layer119896 Thermal conductivity Wmminus1 ∘Cminus1
119870 Darcian permeability coefficient m2119871 Thickness of the material mV119897 Mass transfer rate from the gaseous phase
to the liquid phase kgmminus3 secminus1V119887 Mass transfer rate from the gaseous phase
to the solid phase kgmminus3 secminus1119897119887 Mass transfer rate from the liquid phase to
the solid phase kgmminus3 secminus1119875119888 Pressure of liquid water Pa
119902rad Incident radiation heat flux from theradiation onto the outer fabric surfaceWmminus2119902minus119894119894 Radiation heat flux from the 119894119894 + 1 fabriclayer to the 119894119894 fabric layer Wmminus2119902+119894119894 Radiation heat flux from the 119894119894 minus 1 fabriclayer to the 119894119894 fabric layer Wmminus2
119894119894 Total radiation heat flux of the 119894119894 fabriclayer Wmminus2
119904 Saturation of the fabric119905 Time s119879 Temperature ∘CV Velocity of liquid water m secminus1119909 Distance m
Greek Symbols
120591 Transmissivity of the fabric120591 Fiber curl120588 Density kgmminus3120576 Absorption coefficient120576119887 Volume fraction120574 Radiative extinction coefficient of the
fabric mminus1120583119897 Dynamic viscosity kgmminus1 secminus1120590 Stefan-Boltzmann constant
120575 = 56705 times 10minus8W ∘Cminus4mminus2120596119887 Blood perfusion [000125m3 secminus1mminus3
tissue]Ω Quantitative measure of the burn damage
at the basal layer of human skin119875 Frequency factor or preexponential factor
secminus1Δ119864 Activation energy for skin119877 Universal gas constant
8315 times 103 J kmolminus1 ∘Cminus1
The Scientific World Journal 11
0007
0006
0005
0004
0003
0002
0001
휀l
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
20 sec25 sec30 sec35 sec40 sec
45 sec50 sec55 sec60 sec70 sec
(a) RH = 30
0007
0006
0005
0004
0003
0002
0001
휀l
0012
0011
0010
0009
0008
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
15 sec18 sec20 sec25 sec30 sec
35 sec40 sec50 sec60 sec70 sec
(b) RH = 50
휀l
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(c) RH = 65
휀l
0018
0016
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(d) RH = 80
Figure 12 Liquid water volume fraction distributions at different times
Subscripts
0 Initial stateeff Effective119897 Liquid water119887 Bound waterV Water vaporskin Skinblood Bloodamb Ambient air
vap Evaporationtrans Transferart Human core119871 Left boundary119877 Right boundary
Conflicts of Interest
The authors declare that they have no conflicts of interest
12 The Scientific World JournalH
eat a
bsor
bed
wat
er ev
apor
atio
n (J
)
3000
2500
2000
1500
1000
500
030 40 50 60 70 80
RH ()
Outer shellMoisture barrier
Thermal barrierTotal
Figure 13 Heat absorbed by water evaporation against RH withfitting line
First-degree burn injury timeSecond-degree burn injury time
Burn
inju
ry ti
me (
s)
136
132
128
124
120
116
112
RH ()minus10 0 10 20 30 40 50 60 70 80 90 100
Figure 14 Burning injury time versus RH
Authorsrsquo Contributions
Dongmei Huang carried out the experiment and numericalsimulation and drafted and revised the manuscript Song Heparticipated in the design of the study and performed thestatistical analysis and helped to draft the manuscript Allauthors read and approved the final manuscript
Acknowledgments
This work was supported by Natural Science Foundationof China (no 51306168) and Zhejiang Provincial NaturalScience Foundation of China under Grant no LY17E060004
Tem
pera
ture
(∘C)
Tem
pera
ture
(∘C)
52
51
50
49
48
47
46
45
44
43
42
41
RH ()20 30 40 50 60 70 80 90
360
359
358
357
356
355
354
353
352
351
350
100 sec50 sec10 sec
Figure 15 Temperature at skin surface
References
[1] L D Xu Y L Xy and M Jiang ldquoProtective clothing for fire-fighter GA10-2014rdquo in GA10-2002 China Standards PressBeijing China 2002
[2] D Huang H Yang Z Qi et al ldquoQuestionnaire on firefightersrsquoprotective clothing in Chinardquo Fire Technology vol 48 no 2 pp255ndash268 2012
[3] C C Guerth-Schacher Evaluation of the Effects of Moisture onthe Thermal Protective Performance of Fire Protective Clothingin Low Level Heat Exposures Fire and Polymer Science NorthCarolina State University Raleigh NC USA 2007
[4] R L Barker C Guerth-Schacher R V Grimes and H Hamou-da ldquoEffects of moisture on the thermal protective performanceof firefighter protective clothing in low-level radiant heatexposuresrdquo Textile Research Journal vol 76 no 1 pp 27ndash312006
[5] Y M Lee and R L Barker ldquoEffect of moisture on the thermalprotective performance of heat-resistant fabricsrdquo Journal of FireSciences vol 4 no 5 pp 315ndash331 1986
[6] J O Stull ldquoThe effect of moisture on firefighter protectiveclothing thermal insulation a review of industry researchrdquoin Performance of Protective Clothing Issues and Priorities forthe 21st Century vol 7th ASTM International West Con-shohocken Pa USA 2000
[7] C Keiser C Becker and R M Rossi ldquoMoisture transport andabsorption in multilayer protective clothing fabricsrdquo TextileResearch Journal vol 78 no 7 pp 604ndash613 2008
[8] Y Y Wang Y J Zong J Li and M M Zhao ldquoEvaluating themoisture transfer property of the multi-layered fabric system infirefighter turnout clothingrdquo Fibres amp Textiles in Eastern Europevol 19 no 6 article 89 pp 101ndash105 2011
[9] Y-Y Wang Y-H Lu J Li and J-H Pan ldquoEffects of airgap entrapped in multilayer fabrics and moisture on thermalprotective performancerdquo Fibers and Polymers vol 13 no 5 pp647ndash652 2012
[10] P Chitrphiromsri and A V Kuznetsov ldquoModeling heat andmoisture transport in firefighter protective clothing during flashfire exposurerdquo Heat and Mass Transfer vol 41 no 3 pp 206ndash215 2005
The Scientific World Journal 13
[11] J Fan X Cheng X Wen and W Sun ldquoAn improved modelof heat and moisture transfer with phase change and mobilecondensates in fibrous insulation and comparison with experi-mental resultsrdquo International Journal of Heat andMass Transfervol 47 no 10-11 pp 2343ndash2352 2004
[12] X Cheng and J Fan ldquoSimulation of heat and moisture transferwith phase change and mobile condensates in fibrous insula-tionrdquo International Journal of Thermal Sciences vol 43 no 7pp 665ndash676 2004
[13] SHeDHuang ZQiH Yang YHu andHZhang ldquoThe effectof air gap thickness on heat transfer in firefightersrsquo protectiveclothing under conditions of short exposure to heatrdquo HeatTransfer Research vol 43 no 8 pp 749ndash765 2012
[14] P Andersson and G Holmstedt ldquoHeat sensing manikin testproberdquo Fire and Materials vol 24 no 4 pp 195ndash199 2000
[15] J R Lawson Fire Fighterrsquos Protective Clothing and ThermalEnvironments of Structural Fire Fighting US Department ofCommerce Technology Administration National Institute ofStandards and Technology 1996
[16] P Chitrphiromsri and A V Kuznetsov ldquoPorous mediummodelfor investigating transient heat and moisture transport infirefighter protective clothing under high-intensity thermalexposurerdquo Journal of Porous Media vol 8 no 5 pp 511ndash5282005
[17] P Chitrphiromsri Modeling of Thermal Performance of Fire-fighter Protective Clothing during the Intense Heat ExposureNorth Carolina State University Raleigh NC USA 2004
[18] H P Harry ldquoAnalysis of tissue and arterial blood temperaturesin the resting human forearmrdquo Journal of Applied Physiologyvol 1 no 2 pp 93ndash122 1948
[19] F C Henriques ldquoStudies of thermal injury the predictabilityand the significance of thermally induced rate processes leadingto irreversible epidermal injuryrdquo Archives of pathology vol 43no 5 pp 489ndash502 1947
[20] S A Teukolsky ldquoStability of the iterated Crank-Nicholsonmethod in numerical relativityrdquo Physical Review DmdashParticlesFields Gravitation and Cosmology vol 61 no 8 Article ID087501 2000
[21] F-L Zhu and W-Y Zhang ldquoModeling heat transfer for heat-resistant fabrics considering pyrolysis effect under an externalheat fluxrdquo Journal of Fire Sciences vol 27 no 1 pp 81ndash96 2009
[22] W Q Tao Heat Transfer Northwestern Polytechnical Univer-sity Press Xirsquoan China 2006
[23] J Liu X Chen andL X Xu ldquoNew thermalwave aspects on bumevaluation of skin subjected to instantaneous heatingrdquo IEEETransactions on Biomedical Engineering vol 46 no 4 pp 420ndash428 1999
[24] A N Takata ldquoDevelopment of criterion for skin burnsrdquo Aero-space Medicine vol 45 no 6 pp 634ndash637 1974
[25] T R Gowrishankar D A Stewart G T Martin and J CWeaver ldquoTransport lattice models of heat transport in skinwith spatially heterogeneous temperature-dependent perfu-sionrdquo BioMedical Engineering Online vol 3 article no 42 2004
[26] D A Torvi and J D Dale ldquoA finite element model of skinsubjected to a flash firerdquo Journal of Biomechanical Engineeringvol 116 no 3 pp 250ndash255 1994
[27] A M Stoll and L C Greene ldquoRelationship between pain andtissue damage due to thermal radiationrdquo Journal of AppliedPhysiology vol 14 no 3 pp 373ndash382 1959
[28] MGasperin andD Juricic ldquoThe uncertainty in burn predictionas a result of variable skin parameters an experimental evalu-ation of burn-protective outfitsrdquo Burns vol 35 no 7 pp 970ndash982 2009
TribologyAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FuelsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofPetroleum Engineering
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Industrial EngineeringJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
CombustionJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Renewable Energy
Submit your manuscripts athttpswwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
StructuresJournal of
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal of
Volume 201Hindawi Publishing Corporation httpwwwhindawicom Volume 201
International Journal ofInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nuclear InstallationsScience and Technology of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solar EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Wind EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nuclear EnergyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
The Scientific World Journal 9
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
120 sec
006
005
004
003
002
001
00000 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec21 sec32 sec50 sec
16 sec25 sec35 sec80 sec
20 sec30 sec40 sec
(a) RH = 30
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
009
008
007
006
005
004
003
002
001
00000 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec20 sec32 sec50 sec
10 sec25 sec35 sec80 sec
16 sec
120 sec
30 sec40 sec
(b) RH = 50
012
010
008
006
004
002
000
OSAL
MB
AL
TB
AL
CL AL휌
(kg
mminus3)
00 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec11 sec15 sec30 sec
5 sec12 sec16 sec50 sec
10 sec13 sec20 sec120 sec
(c) RH = 65
012
010
008
006
004
002
000
OSAL
MB
AL
TB
AL
CLAL
휌
(kg
mminus3)
00 05 10 15 20 25 35 35
Distance (times10minus3 m)
0 sec21 sec32 sec50 sec
16 sec25 sec35 sec80 sec
20 sec30 sec40 sec
(d) RH = 80
Figure 10 Distributions of water vapor density at different times
condition is about 1 K which is really slight But the effect ofenergy on the skin injury is an accumulation behavior whichleads to the second-degree burn injury time increasing about8 sec
5 Conclusion
We developed a numerical model to investigate the effectsof initial moisture content at each fabric layer on heat andmoisture transfer in FPCmaterialsWe estimated burn injurytimes under different initial moisture contents using our
model combined with Pennesrsquo model and Henriquesrsquo tissueburn injury model We can draw the following conclusions
(1) Initial moisture content in each FPC fabric layerincreases linearly as the RH of the storage locationincreases
(2) We developed a comprehensive model to simulateheat andmoisture transfer in FPC and the simulationresults show fairly good agreement with the experi-mental results
10 The Scientific World Journal
024
022
020
018
016
014
012
010
008
006
004
002
0000 20 40 60 80 100 120
Time (s)
HR = 30HR = 50
HR = 65HR = 80
휌
(kg
mminus3)
Figure 11 Profiles of water vapor density versus time at a distance of 056 times 10minus3m
(3) Water vapor is distributed both in the fabric layersand in the air layer while free liquid water dispersesonly in the fabric layers Water vapor density ismainly due to evaporation from free liquid waterduring the experiment and it decreases as initialmoisture content increases The total amount of heatabsorption attributable to water evaporation is about10 when the RH is 80
(4) A linear relationship exists between the initial mois-ture content and the maximum duration of heatradiation before causing first- and second-degreeburn injuries
Symbols
119888119901 Specific heat at constant pressureJ kgminus1 ∘Cminus1119863 Diffusivity of the gas phase in the fabricm2 secminus1
119889119891 Fiber radius mℎ119898 Convective heat transfer coefficient
Wmminus2 ∘Cminus1
Δℎ Enthalpy per unit mass J kgminus1119894119894 Fabric layer119896 Thermal conductivity Wmminus1 ∘Cminus1
119870 Darcian permeability coefficient m2119871 Thickness of the material mV119897 Mass transfer rate from the gaseous phase
to the liquid phase kgmminus3 secminus1V119887 Mass transfer rate from the gaseous phase
to the solid phase kgmminus3 secminus1119897119887 Mass transfer rate from the liquid phase to
the solid phase kgmminus3 secminus1119875119888 Pressure of liquid water Pa
119902rad Incident radiation heat flux from theradiation onto the outer fabric surfaceWmminus2119902minus119894119894 Radiation heat flux from the 119894119894 + 1 fabriclayer to the 119894119894 fabric layer Wmminus2119902+119894119894 Radiation heat flux from the 119894119894 minus 1 fabriclayer to the 119894119894 fabric layer Wmminus2
119894119894 Total radiation heat flux of the 119894119894 fabriclayer Wmminus2
119904 Saturation of the fabric119905 Time s119879 Temperature ∘CV Velocity of liquid water m secminus1119909 Distance m
Greek Symbols
120591 Transmissivity of the fabric120591 Fiber curl120588 Density kgmminus3120576 Absorption coefficient120576119887 Volume fraction120574 Radiative extinction coefficient of the
fabric mminus1120583119897 Dynamic viscosity kgmminus1 secminus1120590 Stefan-Boltzmann constant
120575 = 56705 times 10minus8W ∘Cminus4mminus2120596119887 Blood perfusion [000125m3 secminus1mminus3
tissue]Ω Quantitative measure of the burn damage
at the basal layer of human skin119875 Frequency factor or preexponential factor
secminus1Δ119864 Activation energy for skin119877 Universal gas constant
8315 times 103 J kmolminus1 ∘Cminus1
The Scientific World Journal 11
0007
0006
0005
0004
0003
0002
0001
휀l
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
20 sec25 sec30 sec35 sec40 sec
45 sec50 sec55 sec60 sec70 sec
(a) RH = 30
0007
0006
0005
0004
0003
0002
0001
휀l
0012
0011
0010
0009
0008
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
15 sec18 sec20 sec25 sec30 sec
35 sec40 sec50 sec60 sec70 sec
(b) RH = 50
휀l
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(c) RH = 65
휀l
0018
0016
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(d) RH = 80
Figure 12 Liquid water volume fraction distributions at different times
Subscripts
0 Initial stateeff Effective119897 Liquid water119887 Bound waterV Water vaporskin Skinblood Bloodamb Ambient air
vap Evaporationtrans Transferart Human core119871 Left boundary119877 Right boundary
Conflicts of Interest
The authors declare that they have no conflicts of interest
12 The Scientific World JournalH
eat a
bsor
bed
wat
er ev
apor
atio
n (J
)
3000
2500
2000
1500
1000
500
030 40 50 60 70 80
RH ()
Outer shellMoisture barrier
Thermal barrierTotal
Figure 13 Heat absorbed by water evaporation against RH withfitting line
First-degree burn injury timeSecond-degree burn injury time
Burn
inju
ry ti
me (
s)
136
132
128
124
120
116
112
RH ()minus10 0 10 20 30 40 50 60 70 80 90 100
Figure 14 Burning injury time versus RH
Authorsrsquo Contributions
Dongmei Huang carried out the experiment and numericalsimulation and drafted and revised the manuscript Song Heparticipated in the design of the study and performed thestatistical analysis and helped to draft the manuscript Allauthors read and approved the final manuscript
Acknowledgments
This work was supported by Natural Science Foundationof China (no 51306168) and Zhejiang Provincial NaturalScience Foundation of China under Grant no LY17E060004
Tem
pera
ture
(∘C)
Tem
pera
ture
(∘C)
52
51
50
49
48
47
46
45
44
43
42
41
RH ()20 30 40 50 60 70 80 90
360
359
358
357
356
355
354
353
352
351
350
100 sec50 sec10 sec
Figure 15 Temperature at skin surface
References
[1] L D Xu Y L Xy and M Jiang ldquoProtective clothing for fire-fighter GA10-2014rdquo in GA10-2002 China Standards PressBeijing China 2002
[2] D Huang H Yang Z Qi et al ldquoQuestionnaire on firefightersrsquoprotective clothing in Chinardquo Fire Technology vol 48 no 2 pp255ndash268 2012
[3] C C Guerth-Schacher Evaluation of the Effects of Moisture onthe Thermal Protective Performance of Fire Protective Clothingin Low Level Heat Exposures Fire and Polymer Science NorthCarolina State University Raleigh NC USA 2007
[4] R L Barker C Guerth-Schacher R V Grimes and H Hamou-da ldquoEffects of moisture on the thermal protective performanceof firefighter protective clothing in low-level radiant heatexposuresrdquo Textile Research Journal vol 76 no 1 pp 27ndash312006
[5] Y M Lee and R L Barker ldquoEffect of moisture on the thermalprotective performance of heat-resistant fabricsrdquo Journal of FireSciences vol 4 no 5 pp 315ndash331 1986
[6] J O Stull ldquoThe effect of moisture on firefighter protectiveclothing thermal insulation a review of industry researchrdquoin Performance of Protective Clothing Issues and Priorities forthe 21st Century vol 7th ASTM International West Con-shohocken Pa USA 2000
[7] C Keiser C Becker and R M Rossi ldquoMoisture transport andabsorption in multilayer protective clothing fabricsrdquo TextileResearch Journal vol 78 no 7 pp 604ndash613 2008
[8] Y Y Wang Y J Zong J Li and M M Zhao ldquoEvaluating themoisture transfer property of the multi-layered fabric system infirefighter turnout clothingrdquo Fibres amp Textiles in Eastern Europevol 19 no 6 article 89 pp 101ndash105 2011
[9] Y-Y Wang Y-H Lu J Li and J-H Pan ldquoEffects of airgap entrapped in multilayer fabrics and moisture on thermalprotective performancerdquo Fibers and Polymers vol 13 no 5 pp647ndash652 2012
[10] P Chitrphiromsri and A V Kuznetsov ldquoModeling heat andmoisture transport in firefighter protective clothing during flashfire exposurerdquo Heat and Mass Transfer vol 41 no 3 pp 206ndash215 2005
The Scientific World Journal 13
[11] J Fan X Cheng X Wen and W Sun ldquoAn improved modelof heat and moisture transfer with phase change and mobilecondensates in fibrous insulation and comparison with experi-mental resultsrdquo International Journal of Heat andMass Transfervol 47 no 10-11 pp 2343ndash2352 2004
[12] X Cheng and J Fan ldquoSimulation of heat and moisture transferwith phase change and mobile condensates in fibrous insula-tionrdquo International Journal of Thermal Sciences vol 43 no 7pp 665ndash676 2004
[13] SHeDHuang ZQiH Yang YHu andHZhang ldquoThe effectof air gap thickness on heat transfer in firefightersrsquo protectiveclothing under conditions of short exposure to heatrdquo HeatTransfer Research vol 43 no 8 pp 749ndash765 2012
[14] P Andersson and G Holmstedt ldquoHeat sensing manikin testproberdquo Fire and Materials vol 24 no 4 pp 195ndash199 2000
[15] J R Lawson Fire Fighterrsquos Protective Clothing and ThermalEnvironments of Structural Fire Fighting US Department ofCommerce Technology Administration National Institute ofStandards and Technology 1996
[16] P Chitrphiromsri and A V Kuznetsov ldquoPorous mediummodelfor investigating transient heat and moisture transport infirefighter protective clothing under high-intensity thermalexposurerdquo Journal of Porous Media vol 8 no 5 pp 511ndash5282005
[17] P Chitrphiromsri Modeling of Thermal Performance of Fire-fighter Protective Clothing during the Intense Heat ExposureNorth Carolina State University Raleigh NC USA 2004
[18] H P Harry ldquoAnalysis of tissue and arterial blood temperaturesin the resting human forearmrdquo Journal of Applied Physiologyvol 1 no 2 pp 93ndash122 1948
[19] F C Henriques ldquoStudies of thermal injury the predictabilityand the significance of thermally induced rate processes leadingto irreversible epidermal injuryrdquo Archives of pathology vol 43no 5 pp 489ndash502 1947
[20] S A Teukolsky ldquoStability of the iterated Crank-Nicholsonmethod in numerical relativityrdquo Physical Review DmdashParticlesFields Gravitation and Cosmology vol 61 no 8 Article ID087501 2000
[21] F-L Zhu and W-Y Zhang ldquoModeling heat transfer for heat-resistant fabrics considering pyrolysis effect under an externalheat fluxrdquo Journal of Fire Sciences vol 27 no 1 pp 81ndash96 2009
[22] W Q Tao Heat Transfer Northwestern Polytechnical Univer-sity Press Xirsquoan China 2006
[23] J Liu X Chen andL X Xu ldquoNew thermalwave aspects on bumevaluation of skin subjected to instantaneous heatingrdquo IEEETransactions on Biomedical Engineering vol 46 no 4 pp 420ndash428 1999
[24] A N Takata ldquoDevelopment of criterion for skin burnsrdquo Aero-space Medicine vol 45 no 6 pp 634ndash637 1974
[25] T R Gowrishankar D A Stewart G T Martin and J CWeaver ldquoTransport lattice models of heat transport in skinwith spatially heterogeneous temperature-dependent perfu-sionrdquo BioMedical Engineering Online vol 3 article no 42 2004
[26] D A Torvi and J D Dale ldquoA finite element model of skinsubjected to a flash firerdquo Journal of Biomechanical Engineeringvol 116 no 3 pp 250ndash255 1994
[27] A M Stoll and L C Greene ldquoRelationship between pain andtissue damage due to thermal radiationrdquo Journal of AppliedPhysiology vol 14 no 3 pp 373ndash382 1959
[28] MGasperin andD Juricic ldquoThe uncertainty in burn predictionas a result of variable skin parameters an experimental evalu-ation of burn-protective outfitsrdquo Burns vol 35 no 7 pp 970ndash982 2009
TribologyAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FuelsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofPetroleum Engineering
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Industrial EngineeringJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
CombustionJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Renewable Energy
Submit your manuscripts athttpswwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
StructuresJournal of
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal of
Volume 201Hindawi Publishing Corporation httpwwwhindawicom Volume 201
International Journal ofInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nuclear InstallationsScience and Technology of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solar EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Wind EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nuclear EnergyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
10 The Scientific World Journal
024
022
020
018
016
014
012
010
008
006
004
002
0000 20 40 60 80 100 120
Time (s)
HR = 30HR = 50
HR = 65HR = 80
휌
(kg
mminus3)
Figure 11 Profiles of water vapor density versus time at a distance of 056 times 10minus3m
(3) Water vapor is distributed both in the fabric layersand in the air layer while free liquid water dispersesonly in the fabric layers Water vapor density ismainly due to evaporation from free liquid waterduring the experiment and it decreases as initialmoisture content increases The total amount of heatabsorption attributable to water evaporation is about10 when the RH is 80
(4) A linear relationship exists between the initial mois-ture content and the maximum duration of heatradiation before causing first- and second-degreeburn injuries
Symbols
119888119901 Specific heat at constant pressureJ kgminus1 ∘Cminus1119863 Diffusivity of the gas phase in the fabricm2 secminus1
119889119891 Fiber radius mℎ119898 Convective heat transfer coefficient
Wmminus2 ∘Cminus1
Δℎ Enthalpy per unit mass J kgminus1119894119894 Fabric layer119896 Thermal conductivity Wmminus1 ∘Cminus1
119870 Darcian permeability coefficient m2119871 Thickness of the material mV119897 Mass transfer rate from the gaseous phase
to the liquid phase kgmminus3 secminus1V119887 Mass transfer rate from the gaseous phase
to the solid phase kgmminus3 secminus1119897119887 Mass transfer rate from the liquid phase to
the solid phase kgmminus3 secminus1119875119888 Pressure of liquid water Pa
119902rad Incident radiation heat flux from theradiation onto the outer fabric surfaceWmminus2119902minus119894119894 Radiation heat flux from the 119894119894 + 1 fabriclayer to the 119894119894 fabric layer Wmminus2119902+119894119894 Radiation heat flux from the 119894119894 minus 1 fabriclayer to the 119894119894 fabric layer Wmminus2
119894119894 Total radiation heat flux of the 119894119894 fabriclayer Wmminus2
119904 Saturation of the fabric119905 Time s119879 Temperature ∘CV Velocity of liquid water m secminus1119909 Distance m
Greek Symbols
120591 Transmissivity of the fabric120591 Fiber curl120588 Density kgmminus3120576 Absorption coefficient120576119887 Volume fraction120574 Radiative extinction coefficient of the
fabric mminus1120583119897 Dynamic viscosity kgmminus1 secminus1120590 Stefan-Boltzmann constant
120575 = 56705 times 10minus8W ∘Cminus4mminus2120596119887 Blood perfusion [000125m3 secminus1mminus3
tissue]Ω Quantitative measure of the burn damage
at the basal layer of human skin119875 Frequency factor or preexponential factor
secminus1Δ119864 Activation energy for skin119877 Universal gas constant
8315 times 103 J kmolminus1 ∘Cminus1
The Scientific World Journal 11
0007
0006
0005
0004
0003
0002
0001
휀l
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
20 sec25 sec30 sec35 sec40 sec
45 sec50 sec55 sec60 sec70 sec
(a) RH = 30
0007
0006
0005
0004
0003
0002
0001
휀l
0012
0011
0010
0009
0008
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
15 sec18 sec20 sec25 sec30 sec
35 sec40 sec50 sec60 sec70 sec
(b) RH = 50
휀l
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(c) RH = 65
휀l
0018
0016
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(d) RH = 80
Figure 12 Liquid water volume fraction distributions at different times
Subscripts
0 Initial stateeff Effective119897 Liquid water119887 Bound waterV Water vaporskin Skinblood Bloodamb Ambient air
vap Evaporationtrans Transferart Human core119871 Left boundary119877 Right boundary
Conflicts of Interest
The authors declare that they have no conflicts of interest
12 The Scientific World JournalH
eat a
bsor
bed
wat
er ev
apor
atio
n (J
)
3000
2500
2000
1500
1000
500
030 40 50 60 70 80
RH ()
Outer shellMoisture barrier
Thermal barrierTotal
Figure 13 Heat absorbed by water evaporation against RH withfitting line
First-degree burn injury timeSecond-degree burn injury time
Burn
inju
ry ti
me (
s)
136
132
128
124
120
116
112
RH ()minus10 0 10 20 30 40 50 60 70 80 90 100
Figure 14 Burning injury time versus RH
Authorsrsquo Contributions
Dongmei Huang carried out the experiment and numericalsimulation and drafted and revised the manuscript Song Heparticipated in the design of the study and performed thestatistical analysis and helped to draft the manuscript Allauthors read and approved the final manuscript
Acknowledgments
This work was supported by Natural Science Foundationof China (no 51306168) and Zhejiang Provincial NaturalScience Foundation of China under Grant no LY17E060004
Tem
pera
ture
(∘C)
Tem
pera
ture
(∘C)
52
51
50
49
48
47
46
45
44
43
42
41
RH ()20 30 40 50 60 70 80 90
360
359
358
357
356
355
354
353
352
351
350
100 sec50 sec10 sec
Figure 15 Temperature at skin surface
References
[1] L D Xu Y L Xy and M Jiang ldquoProtective clothing for fire-fighter GA10-2014rdquo in GA10-2002 China Standards PressBeijing China 2002
[2] D Huang H Yang Z Qi et al ldquoQuestionnaire on firefightersrsquoprotective clothing in Chinardquo Fire Technology vol 48 no 2 pp255ndash268 2012
[3] C C Guerth-Schacher Evaluation of the Effects of Moisture onthe Thermal Protective Performance of Fire Protective Clothingin Low Level Heat Exposures Fire and Polymer Science NorthCarolina State University Raleigh NC USA 2007
[4] R L Barker C Guerth-Schacher R V Grimes and H Hamou-da ldquoEffects of moisture on the thermal protective performanceof firefighter protective clothing in low-level radiant heatexposuresrdquo Textile Research Journal vol 76 no 1 pp 27ndash312006
[5] Y M Lee and R L Barker ldquoEffect of moisture on the thermalprotective performance of heat-resistant fabricsrdquo Journal of FireSciences vol 4 no 5 pp 315ndash331 1986
[6] J O Stull ldquoThe effect of moisture on firefighter protectiveclothing thermal insulation a review of industry researchrdquoin Performance of Protective Clothing Issues and Priorities forthe 21st Century vol 7th ASTM International West Con-shohocken Pa USA 2000
[7] C Keiser C Becker and R M Rossi ldquoMoisture transport andabsorption in multilayer protective clothing fabricsrdquo TextileResearch Journal vol 78 no 7 pp 604ndash613 2008
[8] Y Y Wang Y J Zong J Li and M M Zhao ldquoEvaluating themoisture transfer property of the multi-layered fabric system infirefighter turnout clothingrdquo Fibres amp Textiles in Eastern Europevol 19 no 6 article 89 pp 101ndash105 2011
[9] Y-Y Wang Y-H Lu J Li and J-H Pan ldquoEffects of airgap entrapped in multilayer fabrics and moisture on thermalprotective performancerdquo Fibers and Polymers vol 13 no 5 pp647ndash652 2012
[10] P Chitrphiromsri and A V Kuznetsov ldquoModeling heat andmoisture transport in firefighter protective clothing during flashfire exposurerdquo Heat and Mass Transfer vol 41 no 3 pp 206ndash215 2005
The Scientific World Journal 13
[11] J Fan X Cheng X Wen and W Sun ldquoAn improved modelof heat and moisture transfer with phase change and mobilecondensates in fibrous insulation and comparison with experi-mental resultsrdquo International Journal of Heat andMass Transfervol 47 no 10-11 pp 2343ndash2352 2004
[12] X Cheng and J Fan ldquoSimulation of heat and moisture transferwith phase change and mobile condensates in fibrous insula-tionrdquo International Journal of Thermal Sciences vol 43 no 7pp 665ndash676 2004
[13] SHeDHuang ZQiH Yang YHu andHZhang ldquoThe effectof air gap thickness on heat transfer in firefightersrsquo protectiveclothing under conditions of short exposure to heatrdquo HeatTransfer Research vol 43 no 8 pp 749ndash765 2012
[14] P Andersson and G Holmstedt ldquoHeat sensing manikin testproberdquo Fire and Materials vol 24 no 4 pp 195ndash199 2000
[15] J R Lawson Fire Fighterrsquos Protective Clothing and ThermalEnvironments of Structural Fire Fighting US Department ofCommerce Technology Administration National Institute ofStandards and Technology 1996
[16] P Chitrphiromsri and A V Kuznetsov ldquoPorous mediummodelfor investigating transient heat and moisture transport infirefighter protective clothing under high-intensity thermalexposurerdquo Journal of Porous Media vol 8 no 5 pp 511ndash5282005
[17] P Chitrphiromsri Modeling of Thermal Performance of Fire-fighter Protective Clothing during the Intense Heat ExposureNorth Carolina State University Raleigh NC USA 2004
[18] H P Harry ldquoAnalysis of tissue and arterial blood temperaturesin the resting human forearmrdquo Journal of Applied Physiologyvol 1 no 2 pp 93ndash122 1948
[19] F C Henriques ldquoStudies of thermal injury the predictabilityand the significance of thermally induced rate processes leadingto irreversible epidermal injuryrdquo Archives of pathology vol 43no 5 pp 489ndash502 1947
[20] S A Teukolsky ldquoStability of the iterated Crank-Nicholsonmethod in numerical relativityrdquo Physical Review DmdashParticlesFields Gravitation and Cosmology vol 61 no 8 Article ID087501 2000
[21] F-L Zhu and W-Y Zhang ldquoModeling heat transfer for heat-resistant fabrics considering pyrolysis effect under an externalheat fluxrdquo Journal of Fire Sciences vol 27 no 1 pp 81ndash96 2009
[22] W Q Tao Heat Transfer Northwestern Polytechnical Univer-sity Press Xirsquoan China 2006
[23] J Liu X Chen andL X Xu ldquoNew thermalwave aspects on bumevaluation of skin subjected to instantaneous heatingrdquo IEEETransactions on Biomedical Engineering vol 46 no 4 pp 420ndash428 1999
[24] A N Takata ldquoDevelopment of criterion for skin burnsrdquo Aero-space Medicine vol 45 no 6 pp 634ndash637 1974
[25] T R Gowrishankar D A Stewart G T Martin and J CWeaver ldquoTransport lattice models of heat transport in skinwith spatially heterogeneous temperature-dependent perfu-sionrdquo BioMedical Engineering Online vol 3 article no 42 2004
[26] D A Torvi and J D Dale ldquoA finite element model of skinsubjected to a flash firerdquo Journal of Biomechanical Engineeringvol 116 no 3 pp 250ndash255 1994
[27] A M Stoll and L C Greene ldquoRelationship between pain andtissue damage due to thermal radiationrdquo Journal of AppliedPhysiology vol 14 no 3 pp 373ndash382 1959
[28] MGasperin andD Juricic ldquoThe uncertainty in burn predictionas a result of variable skin parameters an experimental evalu-ation of burn-protective outfitsrdquo Burns vol 35 no 7 pp 970ndash982 2009
TribologyAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FuelsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofPetroleum Engineering
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Industrial EngineeringJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
CombustionJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Renewable Energy
Submit your manuscripts athttpswwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
StructuresJournal of
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal of
Volume 201Hindawi Publishing Corporation httpwwwhindawicom Volume 201
International Journal ofInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nuclear InstallationsScience and Technology of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solar EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Wind EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nuclear EnergyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
The Scientific World Journal 11
0007
0006
0005
0004
0003
0002
0001
휀l
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
20 sec25 sec30 sec35 sec40 sec
45 sec50 sec55 sec60 sec70 sec
(a) RH = 30
0007
0006
0005
0004
0003
0002
0001
휀l
0012
0011
0010
0009
0008
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
15 sec18 sec20 sec25 sec30 sec
35 sec40 sec50 sec60 sec70 sec
(b) RH = 50
휀l
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(c) RH = 65
휀l
0018
0016
0014
0012
0010
0008
0006
0004
0002
00 05 10 15 20 25 30 35
Thickness (times10minus3 m)
0 sec10 sec15 sec18 sec20 sec25 sec
30 sec35 sec40 sec50 sec60 sec70 sec
(d) RH = 80
Figure 12 Liquid water volume fraction distributions at different times
Subscripts
0 Initial stateeff Effective119897 Liquid water119887 Bound waterV Water vaporskin Skinblood Bloodamb Ambient air
vap Evaporationtrans Transferart Human core119871 Left boundary119877 Right boundary
Conflicts of Interest
The authors declare that they have no conflicts of interest
12 The Scientific World JournalH
eat a
bsor
bed
wat
er ev
apor
atio
n (J
)
3000
2500
2000
1500
1000
500
030 40 50 60 70 80
RH ()
Outer shellMoisture barrier
Thermal barrierTotal
Figure 13 Heat absorbed by water evaporation against RH withfitting line
First-degree burn injury timeSecond-degree burn injury time
Burn
inju
ry ti
me (
s)
136
132
128
124
120
116
112
RH ()minus10 0 10 20 30 40 50 60 70 80 90 100
Figure 14 Burning injury time versus RH
Authorsrsquo Contributions
Dongmei Huang carried out the experiment and numericalsimulation and drafted and revised the manuscript Song Heparticipated in the design of the study and performed thestatistical analysis and helped to draft the manuscript Allauthors read and approved the final manuscript
Acknowledgments
This work was supported by Natural Science Foundationof China (no 51306168) and Zhejiang Provincial NaturalScience Foundation of China under Grant no LY17E060004
Tem
pera
ture
(∘C)
Tem
pera
ture
(∘C)
52
51
50
49
48
47
46
45
44
43
42
41
RH ()20 30 40 50 60 70 80 90
360
359
358
357
356
355
354
353
352
351
350
100 sec50 sec10 sec
Figure 15 Temperature at skin surface
References
[1] L D Xu Y L Xy and M Jiang ldquoProtective clothing for fire-fighter GA10-2014rdquo in GA10-2002 China Standards PressBeijing China 2002
[2] D Huang H Yang Z Qi et al ldquoQuestionnaire on firefightersrsquoprotective clothing in Chinardquo Fire Technology vol 48 no 2 pp255ndash268 2012
[3] C C Guerth-Schacher Evaluation of the Effects of Moisture onthe Thermal Protective Performance of Fire Protective Clothingin Low Level Heat Exposures Fire and Polymer Science NorthCarolina State University Raleigh NC USA 2007
[4] R L Barker C Guerth-Schacher R V Grimes and H Hamou-da ldquoEffects of moisture on the thermal protective performanceof firefighter protective clothing in low-level radiant heatexposuresrdquo Textile Research Journal vol 76 no 1 pp 27ndash312006
[5] Y M Lee and R L Barker ldquoEffect of moisture on the thermalprotective performance of heat-resistant fabricsrdquo Journal of FireSciences vol 4 no 5 pp 315ndash331 1986
[6] J O Stull ldquoThe effect of moisture on firefighter protectiveclothing thermal insulation a review of industry researchrdquoin Performance of Protective Clothing Issues and Priorities forthe 21st Century vol 7th ASTM International West Con-shohocken Pa USA 2000
[7] C Keiser C Becker and R M Rossi ldquoMoisture transport andabsorption in multilayer protective clothing fabricsrdquo TextileResearch Journal vol 78 no 7 pp 604ndash613 2008
[8] Y Y Wang Y J Zong J Li and M M Zhao ldquoEvaluating themoisture transfer property of the multi-layered fabric system infirefighter turnout clothingrdquo Fibres amp Textiles in Eastern Europevol 19 no 6 article 89 pp 101ndash105 2011
[9] Y-Y Wang Y-H Lu J Li and J-H Pan ldquoEffects of airgap entrapped in multilayer fabrics and moisture on thermalprotective performancerdquo Fibers and Polymers vol 13 no 5 pp647ndash652 2012
[10] P Chitrphiromsri and A V Kuznetsov ldquoModeling heat andmoisture transport in firefighter protective clothing during flashfire exposurerdquo Heat and Mass Transfer vol 41 no 3 pp 206ndash215 2005
The Scientific World Journal 13
[11] J Fan X Cheng X Wen and W Sun ldquoAn improved modelof heat and moisture transfer with phase change and mobilecondensates in fibrous insulation and comparison with experi-mental resultsrdquo International Journal of Heat andMass Transfervol 47 no 10-11 pp 2343ndash2352 2004
[12] X Cheng and J Fan ldquoSimulation of heat and moisture transferwith phase change and mobile condensates in fibrous insula-tionrdquo International Journal of Thermal Sciences vol 43 no 7pp 665ndash676 2004
[13] SHeDHuang ZQiH Yang YHu andHZhang ldquoThe effectof air gap thickness on heat transfer in firefightersrsquo protectiveclothing under conditions of short exposure to heatrdquo HeatTransfer Research vol 43 no 8 pp 749ndash765 2012
[14] P Andersson and G Holmstedt ldquoHeat sensing manikin testproberdquo Fire and Materials vol 24 no 4 pp 195ndash199 2000
[15] J R Lawson Fire Fighterrsquos Protective Clothing and ThermalEnvironments of Structural Fire Fighting US Department ofCommerce Technology Administration National Institute ofStandards and Technology 1996
[16] P Chitrphiromsri and A V Kuznetsov ldquoPorous mediummodelfor investigating transient heat and moisture transport infirefighter protective clothing under high-intensity thermalexposurerdquo Journal of Porous Media vol 8 no 5 pp 511ndash5282005
[17] P Chitrphiromsri Modeling of Thermal Performance of Fire-fighter Protective Clothing during the Intense Heat ExposureNorth Carolina State University Raleigh NC USA 2004
[18] H P Harry ldquoAnalysis of tissue and arterial blood temperaturesin the resting human forearmrdquo Journal of Applied Physiologyvol 1 no 2 pp 93ndash122 1948
[19] F C Henriques ldquoStudies of thermal injury the predictabilityand the significance of thermally induced rate processes leadingto irreversible epidermal injuryrdquo Archives of pathology vol 43no 5 pp 489ndash502 1947
[20] S A Teukolsky ldquoStability of the iterated Crank-Nicholsonmethod in numerical relativityrdquo Physical Review DmdashParticlesFields Gravitation and Cosmology vol 61 no 8 Article ID087501 2000
[21] F-L Zhu and W-Y Zhang ldquoModeling heat transfer for heat-resistant fabrics considering pyrolysis effect under an externalheat fluxrdquo Journal of Fire Sciences vol 27 no 1 pp 81ndash96 2009
[22] W Q Tao Heat Transfer Northwestern Polytechnical Univer-sity Press Xirsquoan China 2006
[23] J Liu X Chen andL X Xu ldquoNew thermalwave aspects on bumevaluation of skin subjected to instantaneous heatingrdquo IEEETransactions on Biomedical Engineering vol 46 no 4 pp 420ndash428 1999
[24] A N Takata ldquoDevelopment of criterion for skin burnsrdquo Aero-space Medicine vol 45 no 6 pp 634ndash637 1974
[25] T R Gowrishankar D A Stewart G T Martin and J CWeaver ldquoTransport lattice models of heat transport in skinwith spatially heterogeneous temperature-dependent perfu-sionrdquo BioMedical Engineering Online vol 3 article no 42 2004
[26] D A Torvi and J D Dale ldquoA finite element model of skinsubjected to a flash firerdquo Journal of Biomechanical Engineeringvol 116 no 3 pp 250ndash255 1994
[27] A M Stoll and L C Greene ldquoRelationship between pain andtissue damage due to thermal radiationrdquo Journal of AppliedPhysiology vol 14 no 3 pp 373ndash382 1959
[28] MGasperin andD Juricic ldquoThe uncertainty in burn predictionas a result of variable skin parameters an experimental evalu-ation of burn-protective outfitsrdquo Burns vol 35 no 7 pp 970ndash982 2009
TribologyAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FuelsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofPetroleum Engineering
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Industrial EngineeringJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
CombustionJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Renewable Energy
Submit your manuscripts athttpswwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
StructuresJournal of
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal of
Volume 201Hindawi Publishing Corporation httpwwwhindawicom Volume 201
International Journal ofInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nuclear InstallationsScience and Technology of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solar EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Wind EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nuclear EnergyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
12 The Scientific World JournalH
eat a
bsor
bed
wat
er ev
apor
atio
n (J
)
3000
2500
2000
1500
1000
500
030 40 50 60 70 80
RH ()
Outer shellMoisture barrier
Thermal barrierTotal
Figure 13 Heat absorbed by water evaporation against RH withfitting line
First-degree burn injury timeSecond-degree burn injury time
Burn
inju
ry ti
me (
s)
136
132
128
124
120
116
112
RH ()minus10 0 10 20 30 40 50 60 70 80 90 100
Figure 14 Burning injury time versus RH
Authorsrsquo Contributions
Dongmei Huang carried out the experiment and numericalsimulation and drafted and revised the manuscript Song Heparticipated in the design of the study and performed thestatistical analysis and helped to draft the manuscript Allauthors read and approved the final manuscript
Acknowledgments
This work was supported by Natural Science Foundationof China (no 51306168) and Zhejiang Provincial NaturalScience Foundation of China under Grant no LY17E060004
Tem
pera
ture
(∘C)
Tem
pera
ture
(∘C)
52
51
50
49
48
47
46
45
44
43
42
41
RH ()20 30 40 50 60 70 80 90
360
359
358
357
356
355
354
353
352
351
350
100 sec50 sec10 sec
Figure 15 Temperature at skin surface
References
[1] L D Xu Y L Xy and M Jiang ldquoProtective clothing for fire-fighter GA10-2014rdquo in GA10-2002 China Standards PressBeijing China 2002
[2] D Huang H Yang Z Qi et al ldquoQuestionnaire on firefightersrsquoprotective clothing in Chinardquo Fire Technology vol 48 no 2 pp255ndash268 2012
[3] C C Guerth-Schacher Evaluation of the Effects of Moisture onthe Thermal Protective Performance of Fire Protective Clothingin Low Level Heat Exposures Fire and Polymer Science NorthCarolina State University Raleigh NC USA 2007
[4] R L Barker C Guerth-Schacher R V Grimes and H Hamou-da ldquoEffects of moisture on the thermal protective performanceof firefighter protective clothing in low-level radiant heatexposuresrdquo Textile Research Journal vol 76 no 1 pp 27ndash312006
[5] Y M Lee and R L Barker ldquoEffect of moisture on the thermalprotective performance of heat-resistant fabricsrdquo Journal of FireSciences vol 4 no 5 pp 315ndash331 1986
[6] J O Stull ldquoThe effect of moisture on firefighter protectiveclothing thermal insulation a review of industry researchrdquoin Performance of Protective Clothing Issues and Priorities forthe 21st Century vol 7th ASTM International West Con-shohocken Pa USA 2000
[7] C Keiser C Becker and R M Rossi ldquoMoisture transport andabsorption in multilayer protective clothing fabricsrdquo TextileResearch Journal vol 78 no 7 pp 604ndash613 2008
[8] Y Y Wang Y J Zong J Li and M M Zhao ldquoEvaluating themoisture transfer property of the multi-layered fabric system infirefighter turnout clothingrdquo Fibres amp Textiles in Eastern Europevol 19 no 6 article 89 pp 101ndash105 2011
[9] Y-Y Wang Y-H Lu J Li and J-H Pan ldquoEffects of airgap entrapped in multilayer fabrics and moisture on thermalprotective performancerdquo Fibers and Polymers vol 13 no 5 pp647ndash652 2012
[10] P Chitrphiromsri and A V Kuznetsov ldquoModeling heat andmoisture transport in firefighter protective clothing during flashfire exposurerdquo Heat and Mass Transfer vol 41 no 3 pp 206ndash215 2005
The Scientific World Journal 13
[11] J Fan X Cheng X Wen and W Sun ldquoAn improved modelof heat and moisture transfer with phase change and mobilecondensates in fibrous insulation and comparison with experi-mental resultsrdquo International Journal of Heat andMass Transfervol 47 no 10-11 pp 2343ndash2352 2004
[12] X Cheng and J Fan ldquoSimulation of heat and moisture transferwith phase change and mobile condensates in fibrous insula-tionrdquo International Journal of Thermal Sciences vol 43 no 7pp 665ndash676 2004
[13] SHeDHuang ZQiH Yang YHu andHZhang ldquoThe effectof air gap thickness on heat transfer in firefightersrsquo protectiveclothing under conditions of short exposure to heatrdquo HeatTransfer Research vol 43 no 8 pp 749ndash765 2012
[14] P Andersson and G Holmstedt ldquoHeat sensing manikin testproberdquo Fire and Materials vol 24 no 4 pp 195ndash199 2000
[15] J R Lawson Fire Fighterrsquos Protective Clothing and ThermalEnvironments of Structural Fire Fighting US Department ofCommerce Technology Administration National Institute ofStandards and Technology 1996
[16] P Chitrphiromsri and A V Kuznetsov ldquoPorous mediummodelfor investigating transient heat and moisture transport infirefighter protective clothing under high-intensity thermalexposurerdquo Journal of Porous Media vol 8 no 5 pp 511ndash5282005
[17] P Chitrphiromsri Modeling of Thermal Performance of Fire-fighter Protective Clothing during the Intense Heat ExposureNorth Carolina State University Raleigh NC USA 2004
[18] H P Harry ldquoAnalysis of tissue and arterial blood temperaturesin the resting human forearmrdquo Journal of Applied Physiologyvol 1 no 2 pp 93ndash122 1948
[19] F C Henriques ldquoStudies of thermal injury the predictabilityand the significance of thermally induced rate processes leadingto irreversible epidermal injuryrdquo Archives of pathology vol 43no 5 pp 489ndash502 1947
[20] S A Teukolsky ldquoStability of the iterated Crank-Nicholsonmethod in numerical relativityrdquo Physical Review DmdashParticlesFields Gravitation and Cosmology vol 61 no 8 Article ID087501 2000
[21] F-L Zhu and W-Y Zhang ldquoModeling heat transfer for heat-resistant fabrics considering pyrolysis effect under an externalheat fluxrdquo Journal of Fire Sciences vol 27 no 1 pp 81ndash96 2009
[22] W Q Tao Heat Transfer Northwestern Polytechnical Univer-sity Press Xirsquoan China 2006
[23] J Liu X Chen andL X Xu ldquoNew thermalwave aspects on bumevaluation of skin subjected to instantaneous heatingrdquo IEEETransactions on Biomedical Engineering vol 46 no 4 pp 420ndash428 1999
[24] A N Takata ldquoDevelopment of criterion for skin burnsrdquo Aero-space Medicine vol 45 no 6 pp 634ndash637 1974
[25] T R Gowrishankar D A Stewart G T Martin and J CWeaver ldquoTransport lattice models of heat transport in skinwith spatially heterogeneous temperature-dependent perfu-sionrdquo BioMedical Engineering Online vol 3 article no 42 2004
[26] D A Torvi and J D Dale ldquoA finite element model of skinsubjected to a flash firerdquo Journal of Biomechanical Engineeringvol 116 no 3 pp 250ndash255 1994
[27] A M Stoll and L C Greene ldquoRelationship between pain andtissue damage due to thermal radiationrdquo Journal of AppliedPhysiology vol 14 no 3 pp 373ndash382 1959
[28] MGasperin andD Juricic ldquoThe uncertainty in burn predictionas a result of variable skin parameters an experimental evalu-ation of burn-protective outfitsrdquo Burns vol 35 no 7 pp 970ndash982 2009
TribologyAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FuelsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofPetroleum Engineering
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Industrial EngineeringJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
CombustionJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Renewable Energy
Submit your manuscripts athttpswwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
StructuresJournal of
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal of
Volume 201Hindawi Publishing Corporation httpwwwhindawicom Volume 201
International Journal ofInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nuclear InstallationsScience and Technology of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solar EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Wind EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nuclear EnergyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
The Scientific World Journal 13
[11] J Fan X Cheng X Wen and W Sun ldquoAn improved modelof heat and moisture transfer with phase change and mobilecondensates in fibrous insulation and comparison with experi-mental resultsrdquo International Journal of Heat andMass Transfervol 47 no 10-11 pp 2343ndash2352 2004
[12] X Cheng and J Fan ldquoSimulation of heat and moisture transferwith phase change and mobile condensates in fibrous insula-tionrdquo International Journal of Thermal Sciences vol 43 no 7pp 665ndash676 2004
[13] SHeDHuang ZQiH Yang YHu andHZhang ldquoThe effectof air gap thickness on heat transfer in firefightersrsquo protectiveclothing under conditions of short exposure to heatrdquo HeatTransfer Research vol 43 no 8 pp 749ndash765 2012
[14] P Andersson and G Holmstedt ldquoHeat sensing manikin testproberdquo Fire and Materials vol 24 no 4 pp 195ndash199 2000
[15] J R Lawson Fire Fighterrsquos Protective Clothing and ThermalEnvironments of Structural Fire Fighting US Department ofCommerce Technology Administration National Institute ofStandards and Technology 1996
[16] P Chitrphiromsri and A V Kuznetsov ldquoPorous mediummodelfor investigating transient heat and moisture transport infirefighter protective clothing under high-intensity thermalexposurerdquo Journal of Porous Media vol 8 no 5 pp 511ndash5282005
[17] P Chitrphiromsri Modeling of Thermal Performance of Fire-fighter Protective Clothing during the Intense Heat ExposureNorth Carolina State University Raleigh NC USA 2004
[18] H P Harry ldquoAnalysis of tissue and arterial blood temperaturesin the resting human forearmrdquo Journal of Applied Physiologyvol 1 no 2 pp 93ndash122 1948
[19] F C Henriques ldquoStudies of thermal injury the predictabilityand the significance of thermally induced rate processes leadingto irreversible epidermal injuryrdquo Archives of pathology vol 43no 5 pp 489ndash502 1947
[20] S A Teukolsky ldquoStability of the iterated Crank-Nicholsonmethod in numerical relativityrdquo Physical Review DmdashParticlesFields Gravitation and Cosmology vol 61 no 8 Article ID087501 2000
[21] F-L Zhu and W-Y Zhang ldquoModeling heat transfer for heat-resistant fabrics considering pyrolysis effect under an externalheat fluxrdquo Journal of Fire Sciences vol 27 no 1 pp 81ndash96 2009
[22] W Q Tao Heat Transfer Northwestern Polytechnical Univer-sity Press Xirsquoan China 2006
[23] J Liu X Chen andL X Xu ldquoNew thermalwave aspects on bumevaluation of skin subjected to instantaneous heatingrdquo IEEETransactions on Biomedical Engineering vol 46 no 4 pp 420ndash428 1999
[24] A N Takata ldquoDevelopment of criterion for skin burnsrdquo Aero-space Medicine vol 45 no 6 pp 634ndash637 1974
[25] T R Gowrishankar D A Stewart G T Martin and J CWeaver ldquoTransport lattice models of heat transport in skinwith spatially heterogeneous temperature-dependent perfu-sionrdquo BioMedical Engineering Online vol 3 article no 42 2004
[26] D A Torvi and J D Dale ldquoA finite element model of skinsubjected to a flash firerdquo Journal of Biomechanical Engineeringvol 116 no 3 pp 250ndash255 1994
[27] A M Stoll and L C Greene ldquoRelationship between pain andtissue damage due to thermal radiationrdquo Journal of AppliedPhysiology vol 14 no 3 pp 373ndash382 1959
[28] MGasperin andD Juricic ldquoThe uncertainty in burn predictionas a result of variable skin parameters an experimental evalu-ation of burn-protective outfitsrdquo Burns vol 35 no 7 pp 970ndash982 2009
TribologyAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FuelsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofPetroleum Engineering
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Industrial EngineeringJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
CombustionJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Renewable Energy
Submit your manuscripts athttpswwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
StructuresJournal of
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal of
Volume 201Hindawi Publishing Corporation httpwwwhindawicom Volume 201
International Journal ofInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nuclear InstallationsScience and Technology of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solar EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Wind EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nuclear EnergyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
TribologyAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FuelsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofPetroleum Engineering
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Industrial EngineeringJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
CombustionJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Renewable Energy
Submit your manuscripts athttpswwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
StructuresJournal of
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal of
Volume 201Hindawi Publishing Corporation httpwwwhindawicom Volume 201
International Journal ofInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nuclear InstallationsScience and Technology of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solar EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Wind EnergyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nuclear EnergyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014