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


RadiantRadiant surfacesurface heatingheatingand and coolingcooling systemssystems

FloorFloor WallWall

Thermo Active Building SystemsThermo Active Building Systems

CeilingCeiling

ReinforcementReinforcement

FloorFloor

ConcreteConcrete PipesPipes

RoomRoom

RoomRoom

WindowWindow


Determination of Heating and Cooling Capacity


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


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


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)


Heat transfer coefficient



Max. - Min. Surface temperature

40

17

27

17

35

20

29

20

15

20

25

30

35

40

45

Floor

CeilingWall

oC

HeatingCooling

Perimeter


MAXIMUM HEATING AND COOLING CAPACITY

160

72

42

99

165

42

99

42

020406080100120140160180200

Floor

CeilingWall

HeatingCooling

Perimeter

W/m2


• 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


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 )


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



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


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


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


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


Thermal resistance methods


Pipes embedded in a massive concrete layer


s1

s2

v

R2

Rt

R1

q1

q2

c

Thermal resistance method


Capillar tubes


c

v Rt

R1

R2

s2

Thermal resistancemethods





Ri

Re

RHC


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



Finite Element Method


Laboratory testing


UNIFORMITY OF FLOOR SURFACE TEMPERATURE

Maximum

Minimum

Mean


RADIANT FLOOR COOLING


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


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


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


Wa t

er f

l ow

rat

e

Pressure drop

Water


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.


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


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


DIMENSIONING AND DESIGN

• Pipe diameter

• Pipe spacing

• Pipe layout

• Water flow rate

• Pipe circuits


RL

VL

Kombizone


RLVLRLVL

Perimeter and occupied space


RLVL

Occupied space


Cover as much surface as possible

Possible solution


VLRL


RL

VL


Joints in the concrete


Example


Floor area

Korrektur afNormvarmetabet

Største varmestrøm

Bad tages ikke med

Correction for coveredsurface


Tilslutningsledninger

Total rørlængde

egen varmekreds

gennemgående


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


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


Tryktabsdiagramdiagramfor 17 x 2 mm rør


Pressure drop 14 x 2 mm pipe

Pressure drop

WaterWat

er f

low

rat

e


Valveposition

5 1/4

14


Valve position


INSTALLATION

• Floor systems

• Wall systems

• Ceiling systems

• TABS Thermo Active Building Systems

• Pre-fabrication


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





RadiantRadiant surfacesurface heatingheatingand and coolingcooling systemssystems

FloorFloor WallWall

Thermo Active Building SystemsThermo Active Building Systems

CeilingCeiling

ReinforcementReinforcement

FloorFloor

ConcreteConcrete PipesPipes

RoomRoom

RoomRoom

WindowWindow



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



Documents

Floor Heating - Prof Olesen Lecture-2c-Dimensioning