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Présentation sur les matériaux à changement de phase par Prof. C. Völker TU Kaiserslautern
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www.bauphysik-kl.de
Department of Civil Engineering
Simulations and measurements of
Phase Change Materials (PCM)
in buildings
Jun.-Prof. Dr.-Ing. Conrad Völker
Modelling in Building Physics
Civil Engineering
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Department of Civil Engineering
Motivation § overheating in summer due to
§ climate change
§ glass façades
§ light-weight construction
§ Phase Change Material increase heat capacity
23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 2
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Department of Civil Engineering
Phase Change Materials
23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 3
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Department of Civil Engineering
Phase Change Materials § salt hydrates
§ low material costs § high storage density
§ paraffin § chemical stability § no supercooling
§ alcohols
§ fatty acids
23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 4
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Department of Civil Engineering
Phase Change Materials § specific heat capacity with ΔT=20°C
23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 5
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Gypsum plaster with PCM § PCM
§ micro-encapsulated paraffin § BASF micronal § plastic capsule (5 - 20 µm) § θmelt = 25°C - 28°C (90%)
18°C - 28°C (100%) § gypsum plaster
§ maxit clima 26 § 20 % paraffin § 1 cm layer ~80 kg in test room § latent heat = 16.5 kJ/kg
23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 6
Microscope (ESEM)
Gypsum plaster
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Gypsum plaster with PCM § Differential scanning calorimetry
23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 7
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Salt mixture § composition
§ 96,5 % CaCl2·6H2O § 2 % KCl § 0,5 % NaCl § 1 % Ba(OH)2·8H2O
§ θmelt = 30°C
§ disadvantage § phase separation § hygroscopic
23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 8
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Department of Civil Engineering
Measurements
23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 9
Picture: Franke
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Department of Civil Engineering
Measurements
23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 10
www.bauphysik-kl.de
Department of Civil Engineering
Measurements
23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 11
www.bauphysik-kl.de
Department of Civil Engineering
Measurements
23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 12
www.bauphysik-kl.de
Department of Civil Engineering
Measurements
23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 13
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Department of Civil Engineering
∑Φ=Θρ kiRLL Vc !
[ ])t()t(AhV)(c WiPCM,WiWWWWW Θ−Θ=ΘΘρ !
[ ])t()t(AU iAAWAW Θ−Θ=
[ ])t()t(AU iAFF Θ−Θ+
)t(lzAgr F ⋅⋅⋅⋅+
[ ])t()t(nVc iARLL Θ−Θρ+
)t(iΦ+
[ ])t()t(Ah WiPCM,Wi Θ−Θ−
indoor air
exterior wall
window
solar
ventilation
internal gains
PCM
Simulation – Simplified model
23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 14
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Simulation – Simplified model
23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 15
0
5
10
15
20
25
30
35
40
18/09 19/09 20/09 21/09 22/09 23/09 24/09 25/09 date
θ [°C]
0
5
10
15
20
25
30
35
40
18/09 19/09 20/09 21/09 22/09 23/09 24/09 25/09 date
θ [°C]
simulation vs. measurement
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Simulation – Simplified model
Reasons for differences:
§ simplified model
§ simplified walls: § adiabatic
§ heat capacity of walls
§ temperature gradient in wall
§ solar reflection as a constant
§ …
23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 16
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Department of Civil Engineering
Simulation – ESP-r
23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 17
10121416182022242628303234363840
14.9. 16.9. 18.9. 20.9. 22.9. 24.9. 26.9.10121416182022242628303234363840
14.9. 16.9. 18.9. 20.9. 22.9. 24.9. 26.9.
θ
[°C]
measurement simulation
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Simulation – ESP-r § Optimization of θmelt
§ Optimum means minimal overheating
100
200
300
400
500
600
22 23 24 25 26 27 28 29 30
100
200
300
400
500
600
22 23 24 25 26 27 28 29 30
θlimit = 25°C θlimit = 26°C θlimit = 27°C θlimit = 28°C
over
heat
ing
[h]
θmelt [°C]
1 cm
3 cm
θmelt [°C] 23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 18
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Department of Civil Engineering
§ Optimization of layer thickness
§ For l = 16.5 kJ/kg: layer thickness up to 3 cm useful
1 cm
ohn
e P
CM
1 cm
PC
M2
cm P
CM
3 cm
PC
M4
cm P
CM
5 cm
PC
M
0
100
200
300
400
500
600
θlimit
over
heat
ing
[h]
25°C 26°C 27°C 28°C
1 cm
with
out P
CM
Simulation – ESP-r
23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 19
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Simulation – ESP-r § Optimization of heat conductivity
22
24
26
28
30
32
3.6 4.6 5.6 6.6 7.6 8.6 9.6 10.6
wal
l tem
pera
ture
[
°C]
d = 2 cm
λ = 0.21 W/mK
23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 20
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Department of Civil Engineering
wal
l tem
pera
ture
[
°C]
§ Optimization of heat conductivity § d ≤ 3 cm and l = 16.5 kJ/kg no impact
22
24
26
28
30
32
3.6 4.6 5.6 6.6 7.6 8.6 9.6 10.6
d = 2 cm
λ = 0.42 W/mK
Simulation – ESP-r
23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 21
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Department of Civil Engineering
§ Optimization of heat conductivity § d ≤ 3 cm and l = 16.5 kJ/kg no impact
22
24
26
28
30
32
3.6 4.6 5.6 6.6 7.6 8.6 9.6 10.6
λ = 0.63 W/mK
d = 2 cm
Simulation – ESP-r
wal
l tem
pera
ture
[
°C]
23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 22
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Department of Civil Engineering
§ Optimization of heat conductivity § d ≤ 3 cm and l = 16.5 kJ/kg no impact § thicker layers: higher λ neccessary
22
24
26
28
30
32
3.6 4.6 5.6 6.6 7.6 8.6 9.6 10.622
24
26
28
30
32
3.6 4.6 5.6 6.6 7.6 8.6 9.6 10.6
d = 2 cm d = 6 cm
Simulation – ESP-r
wal
l tem
pera
ture
[
°C]
date date 23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 23
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Department of Civil Engineering
Conclusion § Within experimental measurements a reduction of
room temperatures of 2 K - 5 K was found
§ numerical models were developed & validated
§ phase change temperature range between 23°C and 26°C is recommended
§ For the investigated PCM-plaster, s ≤ 3 cm is recommended
23/05/14 Jun.-Prof. Dr.-Ing. Conrad Voelker 24
