Transcript
Page 1: Floor Heating - Prof Olesen Lecture-2c-Dimensioning

15/02/2009 Bjarne W. Olesen, ICIEE-DTU 1

FLOOR HEATING ++Lecture 2c

• Bjarne W. Olesen, Ph.D.

• Professor,

• International Center for Indoor Environment and Energy

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RadiantRadiant surfacesurface heatingheatingand and coolingcooling systemssystems

FloorFloor WallWall

Thermo Active Building SystemsThermo Active Building Systems

CeilingCeiling

ReinforcementReinforcement

FloorFloor

ConcreteConcrete PipesPipes

RoomRoom

RoomRoom

WindowWindow

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Determination of Heating and Cooling Capacity

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STANDARDS• prEN 1264-2, 2007: Prove methods for the determination of the thermal

output of floor eating systems using calculation and test methods– EN 1264-1, 1999: Floor heating: Systems and components - Part 1 :

Definitions and symbols – EN 1264-3, 1999: Floor heating: Systems and components - Part 3 :

Dimensioning – EN 1264-4, 2001: Floor heating: Systems and components - Part 4:

Installation • prEN 1264-5, 2007: Heating and cooling surfaces embedded in floors,

ceilings and walls — Determination of thermal output and cooling output

• EN15377-1, 2007: Embedded water based surface heating and cooling systems: Determination of the design heating and cooling capacity

• EN15377-2, 2007: Embedded water based surface heating and cooling systems: Design, Dimensioning and Installation

• EN15377-3, 2007: Embedded water based surface heating and cooling systems: Optimizing for use of renewable energy sources

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SURFACE HEATING AND COOLING

Heat transfer coefficient

8,08,0

6,0

11,011,0

7,0

5,5

6,5

7,5

8,5

9,5

10,5

11,5

Floor

Ceiling

Wall

W/m2K

HeatingCooling

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Floor heating and Ceiling cooling: q = 8,92 (θS,m - θi)1,1

Wall heating and Wall cooling: q = 8 ( θS,m - θi )

Ceiling heating: q = 6 ( θS,m - θi )

Floor cooling q = 7 ( θS,m - θi )

Where q is the heat flux in W/m2θS,m is average surface temperature θi is room design temperature (operative)

SURFACE HEATING AND COOLING

Heat transfer coefficient

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SURFACE HEATING AND COOLING

Max. - Min. Surface temperature

40

17

27

17

35

20

29

20

15

20

25

30

35

40

45

Floor

CeilingWall

oC

HeatingCooling

Perimeter

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MAXIMUM HEATING AND COOLING CAPACITY

160

72

42

99

165

42

99

42

020406080100120140160180200

Floor

CeilingWall

HeatingCooling

Perimeter

W/m2

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• CALCULATION OF THE HEAT OUTPUT W/m²

• System factor B will depend on type of system and type of pipe

Universal single power function (EN1264)

FLOOR HEATING

System constant~ 6.5 - 6.7 Temperature difference(Room - water)

Factors

B a a a a tB Tm

Dm

um

wT D u

Floor covering Pipe spacing Pipe diameter Screed covering

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HEATING CAPACITY

• Floor covering aB, spacing aT, and covering aD factors in tables

• mT = 1- T/0.075 (T = Pipe spacing, m)

• mu = 100 ( 0.045 - su ) (su = covering thickness, m)

• mD= 250 ( D-0.020 ) (D = Pipe diameter, m )

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Table A.1 : Floor covering factor aB depending on the thermal resistance R,B of the floor coveringand the thermal conductivityE of the screed for type A and C systems

R,B(m2K/W) 0 0,05 0,10 0,15

E(W/(m.K)) aB

2,0 1,196 0,833 0,640 0,519

1,5 1,122 0,797 0,618 0,505

1,2 1,058 0,764 0,598 0,491

1,0 1,000 0,734 0,579 0,478

0,8 0,924 0,692 0,553 0,460

0,6 0,821 0,632 0,514 0,433

NOTE : The floor covering factor aB may be determined withthe following equation:

a

s

sR

B

u,0

u

u

EB

1

10

0

,

,,

where = 10,8 W/m2K;u,0 = 1 W/m.K; su,0 = 0,045 m

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HEATING CAPACITY

m2K/W

FACTOR FOR FLOOR COVERING, aB

Screed0.80

1.20

00.050.10.15

0.490.46

0.60

0.55

0.76

0.69

1.06

0.92

0.00

0.50

1.00

1.50

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COOLING CAPACITY

• Total factor for the following example• 17 mm pipe

• 45 mm concrete above pipes

• Concrete ~ 1,2 W/mK

75150

300

0,01

0,1

0,52

0,77

0,96

0,420,57 0,66

0

0,2

0,4

0,6

0,8

1

T, mm

Rb, m2K/W

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COOLING CAPACITY

• Cooling capacity in W/m²for the following example• 17 mm PEX-pipe

• 45 mm concrete above pipes

• Concrete ~ 1,2 W/mK

• Space temperature 26 °C

• Supply water temperature 14 °C

• Return water temperature 19 °C

75150

300

0,01

0,1

25

37

46

2027

32

0

10

20

30

40

50

W/m2

T mm

Rb m2K/W

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ALUMINUM HC device: Floor Heating & Cooling (type B), R=0.01~0.1, T=150 & 300

0

20

40

60

80

100

120

140

160

-15 -10 -5 0 5 10 15 20 25 30

Heating/cooling medium differential temperature ΔθH=θH-θi [°C]

He

at e

xc

ha

ng

e [

W/m

2]

T=150, R=0.01

T=150, R=0.1

T=300, R=0.01

T=300, R=0.1

Figure 4.17 Heat exchange between the surface (with ceramic tiles, wooden

parquets or carpet R?B=0.1 and no covering R?B=0) and the space when aluminium heat conductive device used

Heating/ cooling capacity, EN1264 and EN 15377

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Thermal resistance methods

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Pipes embedded in a massive concrete layer

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s1

s2

v

R2

Rt

R1

q1

q2

c

Thermal resistance method

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Capillar tubes

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c

v Rt

R1

R2

s2

Thermal resistancemethods

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Thermal resistance method

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Thermal resistance method

Ri

Re

RHC

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Thermal resistancemethods

Total thermal resistance between the heat source and the conducting layer

m² °C/W

CLUcon,RRHC RRT

RTRTR 2

W/m²

HHi ΔθKq

is the differential temperature of the heating/cooling medium

KH

H H i

equivalent coefficient of thermal conductivity

W/m²C

)/(1 iHCH RRK

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Finite Element Method

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Laboratory testing

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UNIFORMITY OF FLOOR SURFACE TEMPERATURE

Maximum

Minimum

Mean

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RADIANT FLOOR COOLING

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COOLING CAPACITY

107

129

148

15

35

55

75

95

115

135

155

25 20 15

W/2m

CALCULATED CAPACITY IN AN ATRIUMWITH DIRECT SUNSHINE ON THE FLOOR

Supply water temperature, oC

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ALUMINUM HC device: Floor Heating & Cooling (type B), R=0.01~0.1, T=150 & 300

0

20

40

60

80

100

120

140

160

-15 -10 -5 0 5 10 15 20 25 30

Heating/cooling medium differential temperature ΔθH=θH-θi [°C]

He

at e

xc

ha

ng

e [

W/m

2]

T=150, R=0.01

T=150, R=0.1

T=300, R=0.01

T=300, R=0.1

Figure 4.17 Heat exchange between the surface (with ceramic tiles, wooden

parquets or carpet R?B=0.1 and no covering R?B=0) and the space when aluminium heat conductive device used

Heating/ cooling capacity, EN1264 and EN 15377

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Hea

t su

pp

ly

Flo

o rsu

rfac

ete

mp

erat

ure

Flo

o rco

v eri

ng

Pipe distance

Twater-average – troom

Diagram for

17x2 mm pipe

45 mm screed

= 1,2 W/mK

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Wa t

er f

l ow

rat

e

Pressure drop

Water

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The design supply water temperature is determined

according to the room with the highest heat load or with the highest heat resistance of the floor covering.

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Calculation of the water supply temperature

Heat resistance of the floor covering R,B = 0,15 m2K/WPipe spacing 15 cmDesign heat loss 80 W/m2

From the dimensioning diagramDifference between average water temperature and room:

H = 28,9 K

Average water temperature:HM= 20°C + 28,9 K = 48,9 °C

Temperature difference (supply-return) for the critical room: EN1264 = 5 K

Design supply water temperature:

Vdim = HM + /2 = 48,9°C +2,5 K = 51,4 °C

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H = 28,9°C

HM = 48,9 °C

Vausl = 51,4 °C

80 W/m2

0,15m2K/W

FB= 27,3 °C

Boundaryconditions

Så = 45 mm å = 1,2 W/mK

Diagram fordimensioning

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DIMENSIONING AND DESIGN

• Pipe diameter

• Pipe spacing

• Pipe layout

• Water flow rate

• Pipe circuits

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RL

VL

Kombizone

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RLVLRLVL

Perimeter and occupied space

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RLVL

Occupied space

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Cover as much surface as possible

Possible solution

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VLRL

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RL

VL

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Joints in the concrete

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Example

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Floor area

Korrektur afNormvarmetabet

Største varmestrøm

Bad tages ikke med

Correction for coveredsurface

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Tilslutningsledninger

Total rørlængde

egen varmekreds

gennemgående

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Forbindelses rör

9

10

11

12

13

14

15

45 46 47 48 49 50 51 52 53 54 55 56 57 58

Dimensionerende fremlöbstemperatur [°C]

Var

mea

fgiv

else

[W

/m]

45 mm Beton, Ü = 1,2 W/mK

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Vandstrøm:

RFRFr TTTTc

q

86,0

qr: Vandstrøm l/h

c: Vands varmefylde Wh/kgC

Φ: Varmeydelse W

Water flow

Water flow

Specific heat capacity

Heat supply

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Tryktabsdiagramdiagramfor 17 x 2 mm rør

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Pressure drop 14 x 2 mm pipe

Pressure drop

WaterWat

er f

low

rat

e

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Valveposition

5 1/4

14

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Valve position

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INSTALLATION

• Floor systems

• Wall systems

• Ceiling systems

• TABS Thermo Active Building Systems

• Pre-fabrication

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1. Screed-concrete 2. Pipe3. Plastic foil4. Insulation 5. Acoustic insulation6. PE foil7. covering 8. Concrete slab

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Page 30: Floor Heating - Prof Olesen Lecture-2c-Dimensioning

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RadiantRadiant surfacesurface heatingheatingand and coolingcooling systemssystems

FloorFloor WallWall

Thermo Active Building SystemsThermo Active Building Systems

CeilingCeiling

ReinforcementReinforcement

FloorFloor

ConcreteConcrete PipesPipes

RoomRoom

RoomRoom

WindowWindow

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Page 31: Floor Heating - Prof Olesen Lecture-2c-Dimensioning

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Calculation methods

1. Rough sizing method based on a standard calculation of the cooling load (accuracy 20-30%). To be used based on the knowledge of the peakvalue for heat gains (section 5.1)

2. Simplified method using diagrams for sizingbased on 24 hours values of heat gains (accuracy15-20%, section 5.2).

3. Simplified model based on finite difference method (accuracy 10-15%). Detailed dynamic

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