c ombustion p rof. s eung w ook b aek d epartment of a erospace e ngineering, kaist, in korea r oom...
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COMBUSTION
PROF. SEUNG WOOK BAEK DEPARTMENT OF AEROSPACE ENGINEERING, KAIST, IN KOREA
ROOM: Building N7-2 #3304 TELEPHONE : 3714 Cellphone : 010 – 5302 - 5934 [email protected] http://procom.kaist.ac.kr
TA : Bonchan Gu ROOM: Building N7-2 # 3315 TELEPHONE : 3754 Cellphone : 010 – 3823 - 7775 [email protected]
PROF. SEUNG WOOK BAEK DEPARTMENT OF AEROSPACE ENGINEERING, KAIST, IN KOREA
ROOM: Building N7-2 #3304 TELEPHONE : 3714 Cellphone : 010 – 5302 - 5934 [email protected] http://procom.kaist.ac.kr
TA : Bonchan Gu ROOM: Building N7-2 # 3315 TELEPHONE : 3754 Cellphone : 010 – 3823 - 7775 [email protected]
COURSE CODE : MAE 415
COURSE NAME : COMBUSTION ENGINEERING
PROFESSOR : SEUNG WOOK BAEK (Rm #3304, Ext. 3714)
GRADING SYSTEM
1 Final Exam ( June 11th, 2015 )
Homework
SYLLABUS (1/4)
How to efficiently mix fuel and oxidizer Convection and diffusion
How to efficiently burn fuel and oxidizer: energy saving
How to reduce pollutant emission such as CO,CO2 and NOx
How to improve safety and reduce impact on environment
To develop green, sustainable and alternative energy
ISSUES IN COMBUSTION SCIENCE
REFERENCES
F.A.Williams, “Combustion Theory,” Addison Wesley, 2nd Ed.
D.B.Spalding, “Combustion and Mass Transfer,” Pergamon
Press
I.Glassman, “Combustion,” Academic Press, 2nd Ed.
M.Kanury, “Introduction to Combustion Phenomena,” Gordon
and Breach Science Publishers
P.A.Libby and F.A.Williams (Editors), “Turbulent Reacting
Flows,” Springer Verlag
L.A.Kennedy (Editor), “Turbulent Combustion,” Progress in
Astronautics and Aeronautics, Vol.58
SYLLABUS (2/4)
K.K.Kuo, “Principles of Combustion,” Wiley
V.R.Kuznetsoz and V.A.Sabelnikov, “Turbulence and
Combustion,” Hemisphere Publishing Corporation
JOURNALS
Combustion and Flame
Combustion Science and Technology
Symposium (International) on Combustion
Combustion Theory and Modeling
AIAA Journal
Progress in Energy and Combustion Science
SYLLABUS (3/4)
Combustion, Explosion and Shock Waves
Progress in Astronautics and Aeronautics
Fire Safety Journal
International Journal of Heat and Mass Transfer
Journal of Heat Transfer
Journal of Thermophysics and Heat Transfer
Journal of Propulsion and Power
SYLLABUS (4/4)
Thermochemistry
Combustion- high temperature, moderate or high pressure, perfect gas, real gas effects for high pressure environment
Thermodynamic properties of a single perfect gas
Equation of state :
TRCTW
Rp
: Universal gas constant R
PROPULSION AND COMBUSTION LABORATORY
Kmole
energy
: Molecular weight W
mole
mass
: Concentration C
volumeunit
mole
Combustion Engineering
PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
Internal Energy
u : per unit mass
dTTcuuT
T V0
0
0u : Internal energy of formation
Vc : Specific heat
K mass
energy
Enthalpy
W
TRdTcu
W
TRu
puh
T
T V 0
0or
W
TR
W
TRdT
W
Rc
W
TRuh
T
T P
00
00
= T
T P dTTch0
0
0h : Enthalpy of formation
PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
Only change in or is important (not the absolute level)h
0u0hNeed a convention for and
1) Prescribe a standard state, i.e., 0T and 0p
2) The formation enthalpy of the chemical elements in their natural phase at and will be zero.
0T 0p
3) , atmp 10 KT 16.2980
0h for, gH 2 : 00 h gOH 2 : 00 h sC : 00 h
gN 2 : 00 h lH 2 : 00 h
u
PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
Entropy
T
T
P
p
p
W
RdT
T
css
00
0 ln
Let = Entropy at and any temperature .0s 0p T
0
0 lnp
p
W
Rss
Gibbs Free Energy
Tshf per unit mass basis
0000 TshTshf 0
0
0
0 ln)ln(p
p
W
TRf
p
p
W
RsThf
p
dp
W
R
T
dhds
dh vdpTds dh vdp ds
T T
PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
On a molar basis
0
0 lnp
pTRFFWf
F : Molar basis
Helmholtz Free Energy
Tsua
0
0
lnRT p
f fW p
PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
TC : Total number of moles per unit volume
KC : Total number of moles of species K per unit volume
KX : Mole fraction of species K
K
KT CCT
KK C
CX
KKX 1
Mixture of perfect gases ;
222 cNbOaH
PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
: Density of the mixture
K : Partial density of species K
KY : Mass fraction of species K
KW : Molecular weight of species K
K
KKK
K CW
K
KY ,
1K
KY
KKK
KK Y
WWC
PROPULSION AND COMBUSTION LABORATORY Combustion Engineering
jK KT K
K K jK K j
YYC C
W W W
K
/, Y
/K K K K K K K K
KT j j j j j j
j j j
C Y W W C W XX
C Y W W C W X
W : Mean molecular weight of the mixture
K
jjj
jjj
K K
KK
KK WYWY
W
YW
XWW/
1
/
K K K j jK K j
W C W C KKK
KK Y
WWC
KKK
KK
K
KK
K WXW
YW
W
Y
W1)(,
1
EQUATION OF STATE
Partial pressure exerted by species K if it occupiesthe whole volume at temperature T.
TRCp KK
PROPULSION AND COMBUSTION LABORATORY
Dalton’s Law
K K T TK K
p p RT C C RT C WRT RT but
,KT
K K
YC
W W
K K
K TW
R
W
YTRp
Internal Energy
K
KKYuu
PROPULSION AND COMBUSTION LABORATORY
T
T VKK dTTcuuK
00
0
0K
T
K K K K K VTK K
u Y u Y u Y c T dT
T
T V dTcuu0
0 where K
KK uYu00
T
TK
T
T VVK
T
T VK
K dTcdTcYdTcYKK
0 00
K
VKV KcYc
PROPULSION AND COMBUSTION LABORATORY
Enthalpy
K
KK hYh
T
T P dTchh0
0 when is fixed KY
K
KK hYh00
KPKP K
cYc
Entropy
K
KK sYs
PROPULSION AND COMBUSTION LABORATORY
T
T
K
K
PKK p
p
W
RdT
T
css K
00
0
ln
00
0
lnKK PT
K K KK K K K T
K K K K
Y cY p
s Y s Y s dT RT W p
K
K
K
KT
T
P
p
p
p
p
W
YRdT
T
cs
00 lnln
0
PROPULSION AND COMBUSTION LABORATORY
T
T
P
p
p
W
RdT
T
css
00
0 ln
K
KK
KT
T
P XW
YR
p
p
W
RdT
T
css lnln
00
0
00
0
1
ln ln
PK
TP K
KTK K
Entropy increases due to mixingEntropy that a perfect gas of W and cX so that positive termwould have for p and T
c YR ps s dT R X
T W p W
K
KK fYf0
0 lnp
p
W
TRff K
KKK
0
0 lnp
p
W
YTRff K
K K
K
PROPULSION AND COMBUSTION LABORATORY
00
0
ln lnT
P K K
TK K
c Y p ps s dT R
T W p p
lnK KK
RX X
W
KY K K K K
j jj
W X W X
W X W
K
K
K
K XW
YTR
p
p
W
TRff lnln
0
0
p
KP T
hc
K
Caution ;
When there is reaction p
P T
hc
K
KK hYhp
K
KK
p
K
KK
p T
Yh
T
hY
T
h
p
K
KK
p
P T
Yh
T
hc
PROPULSION AND COMBUSTION LABORATORY
K
KKXX
W
TRln
0 0
0 0
ln (ln ln )K K K K
K KK K
Y p Y ppf f RT f RT
W p W p p
KK
K
XYW W
Problem for notes
Binary mixture of 422 HeH
,1
2
2
2
2
H
HH Y
YX
2
2
1
1
H
H
He Y
YX
,12 HeH YY
HeH PHPHPcYcYc
2221
Specification of Composition
,TRnVp KK TRnpV T For same TV ,
PROPULSION AND COMBUSTION LABORATORY
jj
j
K
K
K
WYW
Y
X
KK
KKKK
W
WY
Wm
Wm
n
n
p
p
/
/
,TW
RmpV
KKK T
W
RmpV
For same P and T, partial volume of species K
T
K
KT
KK
K
KK
n
n
W
W
Wn
Wn
W
W
m
m
V
V
Here, is not so thatV KV .KK Y
m
m
PROPULSION AND COMBUSTION LABORATORY
Material Balance for Chemical ReactionsEx) Combustion of Octane with Air
Air: 2222
176.379.021.0 Oof mole perNof molesNO Molecular Weight: 298.282879.03221.0
For complete combustion (stoichiometric)
22222188 21
79
2
2598
21
79
2
25
2
25NOHCONOHC
Stoichiometric Coefficients: 1188 HC
,2/252O
21
79
2
252 N
PROPULSION AND COMBUSTION LABORATORY
On a mass basis,
2821
79
2
25
2
189
2
448
2
)(1831
2821
79
2
25
2
322
25
2
114
188 21
79
2
2598
21
79
2
25
2
25
NOHCONOHC
gmsorlbs
or 15.1 kg of air/ 1 kg of octane
For reactants
0165.052.60
1
21
79
2
25
2
251
1188
HCX
,2065.052.60
2/252
OX 7769.052.60
21/792/252
NX
PROPULSION AND COMBUSTION LABORATORY
PROPULSION AND COMBUSTION LABORATORY
0623.01831
114188
HCY
W
: MEAN MOLECULAR WEIGHT OF REACTANTS
3.3052.60
1831
MASS OF PRODUCTS = 1831
125.0
2179
225
98
82
CO
X RP nn
2821
79
2
25
2
189
2
448
2
)(1831
2821
79
2
25
2
322
25
2
114
188 21
79
2
2598
21
79
2
25
2
25
NOHCONOHC
gmsorlbs
PROPULSION AND COMBUSTION LABORATORY
EQUIVALENCE RATIO :
tricstoichiomeoxidizerofmass
fuelofmass
oxidizerofmassfuelofmass
FOR 1
222224 76.32276.322 NOHCONOCH
PROPULSION AND COMBUSTION LABORATORY
1
1
1
: STOICHIOMETRIC
: FUEL LEAN
: FUEL RICH
FOR 9.0 224 76.3229.0 NOCH
FOR 1 differentCH 4
ENERGY Eq. FOR CHEMICAL REACTION
CONSTANT VOLUME SYSTEM – NO MOTION
PROPULSION AND COMBUSTION LABORATORY
1st LAW : WdEQ
Q
dE
W
: HEAT TRANSFER
(POSITIVE WHEN ADDED TO THE SYSTEM)
: INTERNAL ENERGY
: WORK DONE BY THE SYSTEM
1221 EEQ 1: REACTANT STATE
2: PRODUCT STATE
ONLY IMPORTANCE IS , NOT THE ABSOLUTE VALUES.
PROPULSION AND COMBUSTION LABORATORY
E
BT
C25: REFERENCE OR BASIC TEMPERATURE
BE: INTERNAL ENERGY OF REACTION, DETERMINED IN A BOMB CALORIMETER
PROPULSION AND COMBUSTION LABORATORY
11122212 EEEEEEEEQ BBBB
ncompositiofixed
B
tabulated
B
ncompositiofixed
B EEEEE
11
22
FOR CONSTANT PRESSURE PROCESS;
VdpdHpdVdEWdEQ
1 2 2 1 2 2 2 1 1 1
B
B B B B
H
Q H H H H H H H H
PROPULSION AND COMBUSTION LABORATORY
BH
BE
: ENTHALPY OF REACTION
BBBBBB VpVpEH 1122
:INTERNAL ENERGY OF
REACTION AT BTFOR PERFECT GASES;
constpBconstVB EE
2 1B B BH H H
PROPULSION AND COMBUSTION LABORATORY
BBBBBBB TRnTRnTRnVpVp 121122
12 nnn BBB TRnEH
2 2 1 1
2 1 2 2 2 1 1 1
B B B B B B
B B B B
H E p V p V
Q H H H H H H H H
ENTHALPY OF FORMATION AND ENTHALPY OF COMBUSTION
ENTHALPY OF FORMATION -THAT CHANGE OF ENTHALPY WHICH OCCURS WHEN A COMPOUND IS FORMED FROM THE ELEMENTS, WHICH ARE IN THEIR STABLE STATE, AT SAME STANDARD TEMPERATURE AND PRESSURE.
PROPULSION AND COMBUSTION LABORATORY
gCOgOsC 22 GIVES OFF 94052 cal :exothermic reaction
2
0294052 /f CO
H cal gmole of CO
HEAT OF FORMATION =0
294052 /fH cal gmole of CO ALSO A COMBUSTION PROCESS
ENTHALPY OF COMBUSTION 0 0
294052 /c fH H cal gmole of CO
2/94052 COofgmolecal
HEAT OF COMBUSTION OF
HEAT OF COMBUSTION
)(/12
94052)( sCof gcalsC
PROPULSION AND COMBUSTION LABORATORY
gNOgOgNEx 2222
1)
20 /8091
2NOofgmolecalH
NOf
HEATING VALUES; FOR C+O2 REACTION,
BB EH ,BECAUSE THERE IS NO WORKS.pdV
IN GENERAL,
HIGHER HEATING VALUES AND LOWER HEATING VALUES DEPEND ON STATE OF PRODUCTS.
BB EH
ENDOTHERMIC REACTION
BBB TRnEH
PROPULSION AND COMBUSTION LABORATORY
IMPORTANT CASE IS vs. gOH 2 lOH 2
OHOH 222 2
1
IF IS LIQUID,
LHV DIFFERS FROM HHV BY HEAT OF VAPORIZATION.
OH 2 22 /32.34 HofgkcalOHHHV
22
22 /9.28
9/602.0 Hofgkcal
Hofg
OHofgOHofgkcalHHVLHV
PROPULSION AND COMBUSTION LABORATORY
REFERENCES FOR THERMOCHEMICAL DATA
1. NBS, “Tables of Selected Values of Chemical Thermal Properties”, Circular Letter 500
2. JANAF Thermo-Chemical Tables (1993)3. Penner’s Book4. Van Wylen & Sonntag (SI units)5. CHEMKIN: Software package for the analysis of gas-
phase chemical and plasma kinetics (2000)
EXAMPLE
10g OF H2 (g) BURN IN AIR (=1) AT CONSTANT
PRESSURE. INITIAL TEMPERATURE IS 298K AND FINAL TEMPERATURE IS 2000K SO THAT H2O IS GASEOUS. CALCULATE THE HEAT LIBERATED ;
PROPULSION AND COMBUSTION LABORATORY
12 HHQ
molesHofg 5102
)(4.9)(5)()76.3(2
5)(
2
5)(5 22222 gNgOHgNgOgH
KgNKgOH HHH 2000),(2000),(2 224.95
KgNKgOKgH HHHH 298),(298),(298),(1 2224.9
2
55
molecal
HHHH KgOHfKKKgOH
7.40535577987.236719630
298),(,29820002000),( 22
KgNfKgN HH 298),(,2000),( 22
3.20728.15494
PROPULSION AND COMBUSTION LABORATORY
MINUS INDICATES THAT HEAT WAS
TRANSFERRED OUT OF THE SYSTEM. IN OTHER
WORDS, THE FLAME TEMPERATURE, IF ADIABATIC,
WOULD BE HIGHER THAN 2000 K.
IF THE PROBLEM WERE AT CONSTANT VOLUME,
0298),(298),(298),( 222 KgNKgOKgH HHH
calQ 76512
12 EEQ TRnHpVHE
etc. calcal
TRnHEKgOHKgOH
,20009807.15)7.40535(5
552000),(2000),( 22
PROPULSION AND COMBUSTION LABORATORY
CALCULATION OF ENTHALPY OF REACTION FROM
THE ENTHALPY OF FORMATION
REACTION ;
ReactantsProductsReaction
RfPfR HHH
nNmMbBaA
Na
nM
a
mB
a
bA ro
AfBfNfMfAofmoleR HH
a
bH
a
nH
a
mH
PROPULSION AND COMBUSTION LABORATORY
EX) GASEOUS CH4 + O2 REACT TO YIELD H2O(l)+CO2(g).
CALCULATE PER MOLE OF CH4 RH
kcal
HHHHHgOfgCHflOHfgCOfCHR
8.2129.1732.68205.94
22)()()()( 24224
)(2)()(2)(2224
lOHgCOgOgCH
EXOTHERMIC PER MOLE OF CH4
PROPULSION AND COMBUSTION LABORATORY
CONSIDER A CHEMICAL SYSTEM OF CONSTANT MASS
EITHER HOMOGENEOUS OR HETEROGENEOUS IN
MECHANICAL AND THERMAL EQUILIBRIUM BUT NOT IN
CHEMICAL EQUILIBRIUM. THE SYSTEM IS IN CONTACT
WITH A RESERVOIR AT TEMPERATURE T AND
UNDERGOES AN INFINITESIMAL IRREVERSIBLE
EXCHANGE OF HEAT, Q, TO THE RESERVOIR. PROCESS
MAY INVOLVE CHEMICAL REACTION AND TRANSPORT
BETWEEN PHASES.
PROPULSION AND COMBUSTION LABORATORY
FROM SYSTEM
dS: ENTROPY CHANGE OF THE SYSTEM
sQQ
0 dST
Qs
dSO: ENTROPY CHANGE OF THE RESERVOIR
dS+dSo: ENTROPY CHANGE OF THE UNIVERSE
0 dSdSO
T
QdS
O
0 dS
T
Q
PROPULSION AND COMBUSTION LABORATORY
FROM SYSTEM
1ST LAW sQ dE pdV
0 dST
Qs
0dE pdV TdS VARIOUS CONSTRAINTS
CASE A ; HOLD E AND V CONSTANT
ISOLATED SYSTEM0dS
CASE B ; HOLD p AND T CONSTANT
0d E pV TS d H TS dF GIBBS FREE ENERGY DECREASES
PROPULSION AND COMBUSTION LABORATORY
WHEN ; HAVE CHEMICAL EQUILIBRIUM
AT EQUILIBRIUM ;
0, TPF
CASE C ; HOLD V AND T CONSTANT
0 dATSEd
0, TVA
-
PROPULSION AND COMBUSTION LABORATORY
EQUILBRIUM OF A MIXTURE OF PERFECT GASES
UNDERGOING CHEMICAL REACTION
CONSIDER THE REACTION,
dDcCbBaA WE KNOW GIBBS FREE ENERGY FOR
AND ANY TEMPERATURE T PER MOLE.
AF atmP 10
AT ANY T AND P ;
0ln ppTRFF AAA
0ln ppTRFF BBB
, ETC
AF
0
0
0 0
0 0
ln
ln ln
KK K
K
K KK K K K K K
pRTf f
W p
p pW f F W f RT F RT
p p
PROPULSION AND COMBUSTION LABORATORY
LET
BADC bFaFdFcFF
0 0
0 0
lnc d
C Da b
A B
p p p pF F RT
p p p p
0 1 P atm
lnc dC Da bA B
p pF F RT
p p
BADC bFaFdFcFF
0 0 0 0
ln ln ln lnC D A BC D A B
p p p pc F RT d F RT a F RT b F RT
p p p p
0
0
ln KK K
pF F RT
p
PROPULSION AND COMBUSTION LABORATORY
NOTE THAT
AT EQUILIBRIUM
DEFINE equilibrium constant based on pressurec dC D
P a bA B
p pK
p p
0F
PKTRF ln
TRFP eK
)(TfF
)(TgKP A
A
pX mole fraction
p
B Bp pX C Cp pX D Dp pX
PROPULSION AND COMBUSTION LABORATORY
EFFECT OF T ON EQUILIBRIUM COMPOSITION IS GIVEN IN Kp
EFFECTS OF p ON THE TERM.
FOR THE CASE OF , IE. C + D = A + BNO PRESSURE EFFECT
EQUILIBRIUM CONSTANT BASED ON CONCENTRATION ;
WHERE
( )c d c d
c d a b nC D C DP a b a b
A B A B
X X X XK p p
X X X X
)()( badcn
np
0n
CK
volumeunit
moleionConcentratC
PROPULSION AND COMBUSTION LABORATORY
VALUES OF KP ARE TABULATED FOR SPECIFIC
CHEMICAL REACTION.
bB
aA
dD
cC
C CC
CCK C Cp C RT , ETC
c d n nC D
C pa bA B
p pK RT K RT
p p
EX) DISSOCIATION OF CO2
22 2
1OCOCO 2
2
1 2
1CO O
PCO
p pK
p (1)
PROPULSION AND COMBUSTION LABORATORY
EX) 100% WATER VAPOR, INITIALLY AT 1 atm AND
2200 K DISSOCIATES INTO H2 (g) AND O2 (g).
ASSUMING PERFECT GASES THROUGHOUT,
DETERMINE THE EQUILIBRIUM COMPOSITION
EQUILIBRIUM COMPOSITION
(2)222
1COOCO 2
2
1
2 11/2
COP P
CO O
pK K
p p
22 22 COOCO (3) 212
2
3
2
2 POCO
COP K
pp
pK
PROPULSION AND COMBUSTION LABORATORY
CHEMICAL REACTION )(2
1)()(
222gOgHgOH
2 2 2 2
2 2
1 2 1 21 2H O H O
PH O H O
p p X XK p
p X
2222 cObHOaHOH EQUILIBRIUM COMPOSITION
caO
baH
21:
222:
2)1(
1
ac
ab
2222 2
)1(1 O
aHaOaHOH
2
3
2
)1()1(
aaaanT
PROPULSION AND COMBUSTION LABORATORY
2
31
2 aa
X H
2
32
1
2 a
a
X O
2
32 aa
X OH
1 2
1 2
11 23 3
2 2 ,
32
P
aaa a
K pa
a
3 2 1 23
1 2
11.145 10
3P
a PK
a a
2222 2
0137.00137.09863.0 OHOHOH
EQUILIBRIUM
COMPOSITION
PROPULSION AND COMBUSTION LABORATORY
EXAMINE LIMITING CONDITIONS
CASE I - LOW TEMPERATURES
; VERY LITTLE DISSOCIATION
LET 1a 1
21
2123
2
PKP
32
312
PKP
OR
A) HIGHER PRESSURE ; LOWER ; GREATER LESS DISSOCIATION
B) HIGHER TEMPERATURE ; HIGHER KP GREATER ; SMALLER MORE DISSOCIATION
a
a
3 2 1 2
1 2
1
3P
a pK
a a
2222 cObHOaHOH
2222 2
)1(1 O
aHaOaHOH
PROPULSION AND COMBUSTION LABORATORY
CASE II - HIGH TEMPERATURES ; HIGH DISSOCIATION
OR
A) HIGHER PRESSURE ; HIGHER ; HIGHER LESS DISSOCIATION
B) HIGHER TEMPERATURE ; HIGHER KP ; LOWER = MORE DISSOCIATION
a 1
21
21
3P
KP PK
P 1
3
21
a
a
3 2 1 2
1 2
1
3P
a pK
a a
2222 2
)1(1 O
aHaOaHOH
PROPULSION AND COMBUSTION LABORATORY
EQUILIBRIUM WHEN SIMULTANEOUS REACTIONS
OCCURRING
THE NUMBER OF INDEPENDENT REACTIONS, WHICH MUST BE CONSIDERED IN EQUILIBRIUM CALCULATIONS, IS EQUAL TO THE LEAST NUMBER OF EQUATIONS WHICH INCLUDE ANY REACTANT AND PRODUCT WHICH ARE PRESENT TO AN APPRECIABLE DEGREE IN THE EQUILIBRIUM MIXTURE.
EX) CALCULATE THE COMPOSITION OF THE EQUILIBRIUM
MIXTURE OBTAINED WHEN 5 MOLES OF STEAM, H2O
(g) REACT WITH 1 MOLE OF CH4 AT ELEVATED
TEMPERATURE AND SOME ARBITRARY PRESSURE
PROPULSION AND COMBUSTION LABORATORY
MECHANISM FOR REACTION ;2 ACTUAL REACTIONS ARE ;
C : 1 = a + c + eH : 14 = 4a + 2b + 2dO : 5 = b + c + 2e
2224245 eCOdHcCOObHaCHOHCH
2224
24
42723
5
CObaHbaCObaObHaCH
OHCH
PROPULSION AND COMBUSTION LABORATORY
03 224 RHHCOOHCH
0222 RHHCOOHCO
(1)
(2)
2
4 2
3
1CO H
PCH H O
p pK
p p 2 2
2
2CO H
PCO H O
p pK
p p
aedcbanT 28
3 2
1 2
3 2 7 2
8 2P
a b a b pK
ab a
bba
babaKP
23
2742
2224
24
42723
5
CObaHbaCObaObHaCH
OHCH
3 2
8 2.
CO CO
a bp X p p
aetc
PROPULSION AND COMBUSTION LABORATORY
(1)
(2)
eEcCaA dDbBeE
dDcCbBaA ADD (3)
1
c eC E
P aA
p pK
p 2
dD
P e bE B
pK
p p 3 1 2
c dC D
P P Pa bA B
p pK K K
p p
PRODUCT RULE FOR KP’s
PROPULSION AND COMBUSTION LABORATORY
ADIABATIC FLAME TEMPERATURE 0Q
POINT (2) FINAL TEMPERATURE AND H AFTER A NON-ADIABATIC REACTION
POINT (2i) ISOTHERMAL REACTIONPOINT (c) ADIABATIC FLAME TEMPERATURE ; H2=H1
PROPULSION AND COMBUSTION LABORATORY
CONSTANT PRESSURE REACTION – GENERAL CASE
0Q
P
n
iii
R
m
iii BbAa
DETERMINE TC FROM H2=H1
H2 DEPENDS ON THE bi WHICH DEPENDS ON Tc WHICH
DEPENDS ON THE bi.
m
iTATi
n
iTBTi iiCiC
HaHb1,,,,
PROPULSION AND COMBUSTION LABORATORY
FOR PERFECT GASES
WHERE
TO CALCULATE Tc
m
i
T
T PAfTi
n
i
T
T PBfTiBi
C
BiCdTCHadTCHb
1
1,,
r
m
iAfTi
n
iBfTi
HHaHbiiC
1,,
1. ASSUME TC FOR GIVEN PRESSURE
2. CALCULATE THE bi FROM THE KP’s
3. SUBSTITUTE INTO H2=H1
4. ITERATE UNTIL H2=H1
PROPULSION AND COMBUSTION LABORATORY
CALCULATE THE ADIABATIC FLAME TEMPERATURE
OF A = 0.8 METHANE – O2 MIXTURE AT p = 10 atm,
TAKING INTO ACCOUNT THE DISSOCIATION OF CO2
AND H2O
2 UNKNOWNS
OHCOOCH2224
220.1
222224 28.08.0 eOdHcCOObHaCOOCH
2222
24
5.05.06.16.18.0
28.0
ObaHbCOaObHaCO
OCH
baedcbanT 5.05.04
TCO n
aX
2
TO n
eX
2etc.
Dissociation Reactions
22 2
1OCOCO 2 2
2 2
1 12 2
12
1CO O CO O
PCO CO
p p X XK p
p X
222 2
1OHOH 2 2 2 2
2 2
1 12 2
12
2H O H O
PH O H O
p p X XK p
p X
12 HH
12142222
28.0TOTCHTOTHTCOTOHTCO HHHeHdHcHbHa
CCCCC
Combustion EngineeringPROPULSION AND COMBUSTION LABORATORY
Procedure ; assume Tc; Calculate a,b,c,d,eSubstitute into H2=H1 (from Energy Equation)
If Tc=3000K
Combustion EngineeringPROPULSION AND COMBUSTION LABORATORY
a[-94.05 kcal/mole + 38.94-2.24]+b[-57.8+32.16-2.37]
+c[-26.42+24.43-2.07]+d[0+23.19-2.02]
+e[0+25.52-2.07] = 0.8[-17.89]+2[0]
Hco2HH20
Hco HH2
Ho2 HCH4 Ho2
Combustion EngineeringPROPULSION AND COMBUSTION LABORATORY
Tables of Thermodynamic Properties
Combustion EngineeringPROPULSION AND COMBUSTION LABORATORY
Combustion EngineeringPROPULSION AND COMBUSTION LABORATORY
Combustion EngineeringPROPULSION AND COMBUSTION LABORATORY
Combustion EngineeringPROPULSION AND COMBUSTION LABORATORY
Combustion EngineeringPROPULSION AND COMBUSTION LABORATORY
Combustion EngineeringPROPULSION AND COMBUSTION LABORATORY
Combustion EngineeringPROPULSION AND COMBUSTION LABORATORY
Combustion EngineeringPROPULSION AND COMBUSTION LABORATORY
Combustion EngineeringPROPULSION AND COMBUSTION LABORATORY
Combustion EngineeringPROPULSION AND COMBUSTION LABORATORY
Combustion EngineeringPROPULSION AND COMBUSTION LABORATORY
Combustion EngineeringPROPULSION AND COMBUSTION LABORATORY
Combustion EngineeringPROPULSION AND COMBUSTION LABORATORY