Thermal Storage in Smart PCM Walls
Transcript of Thermal Storage in Smart PCM Walls
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butikofer de oliveira vernay architectes
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Thermal Storage in Smart PCM Walls:An enhanced and controlled discharge power by forced convection
Presented by Antoine BossAuthors: J. Robadey, R. Wegmüller, A. Chiriatti, G. Magnin, E.L. Niederhauser15. Symposium Energieinnovation, February 16th 2018, TU Graz, Austria
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Outline
• Description of the active PCM concept• Testbed• Set-up• Measurements• Simulations
• Simulations of a reference building • PCM of 23°C and 26°C with day and night loading• Active and passive PCM
• Conclusion and outlook
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concept validation}
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Active PCM concept
• Electrical battery can be charged and discharged at every moment
• Standard PCM (Phase Change Material):• can be loaded on demand (heating)• discharged as soon as Tint < Tc
• NEW CONCEPT with on demand activation of the PCM discharge
• Solution
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Storage managementnot possible
Charge à Heating an insulated PCMStorage à PCM remains insulatedDischarge à Ventilation of the PCM
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• Heating with a water circuit
• Discharging with an air flow
• PCM:• micronal encapsulated paraffin with Tc = 23/26°C
• in «Lehmorange» plates
• Advantage:• discharge can be controlled
• wall can be furnished
Concept of a ventilated PCM wall
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opening
with grid
floor
cross-
sectionair flow
3-way
valve
heating system
between PCM
plates
air flow
insulation
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Testbed: PCM wall in the middle of two rooms
heating system
PCM-Plate
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Active discharge
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Smart PCM Walls : Simulation results External and box temperatures
ext
PCM
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TairTextTPCM
air
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Smart PCM Walls : Comparison Measures-SimulationsTwo days cycle
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+ 5°C
40mn
Text measuredTPCM measuredTair measuredT simulated
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Simulations of a reference building
bearing walls
PCM walls
22 m
8 m
3 x 3 3 x 5
2 x 22
Height 3m per floorBuilding has 2 floorsTotal volume: 1’000 m3
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administrative building(not occupied at night and during week-ends)
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Heating process with PCM walls
HeatPump
• Goal: increase the building autonomy and assure comfort temperature during building occupancy
• 4 states:• Loading: Heat pump on without ventilation• Storage: no heating and no ventilation• Discharge: Ventilation (heat pump off)• Heating: Heat pump on with ventilation
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6 12 18 24 6 Time:
Thermal state
comforttemperature
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Heating process with PCM walls
HeatPump
• Goal: increase the building autonomy and assure comfort temperature during building occupancy
• 4 states:• Loading: Heat pump on without ventilation• Storage: no heating and no ventilation• Discharge: Ventilation (heat pump off)• Heating: Heat pump on with ventilation
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6 12 18 24 6 Time:
Thermal state
comforttemperature
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Heating process with PCM walls
HeatPump
• Goal: increase the building autonomy and assure comfort temperature during building occupancy
• 4 states:• Loading: Heat pump on without ventilation• Storage: no heating and no ventilation• Discharge: Ventilation (heat pump off)• Heating: Heat pump on with ventilation
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Ventilation
6 12 18 24 6 Time:
Thermal state
comforttemperature
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Heating process with PCM walls
HeatPump
Ventilation• Goal: increase the building autonomy and assure comfort temperature during building occupancy
• 4 states:• Loading: Heat pump on without ventilation• Storage: no heating and no ventilation• Discharge: Ventilation (heat pump off)• Heating: Heat pump on with ventilation
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6 12 18 24 6 Time:
Thermal state
comforttemperature
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Simplified simulations• Text constant the whole day all around the building
• Solar heating inside the building and wind effect are neglected
• U-value = 0.15 W/m2K for the building envelope
• Comfort temperature of about 20.5°C between 06h and 17h30 • Air renewal: 0.5 Vol/hour from 7h to 18h with 90% heat recovery
• PCM loaded with 12kW either during the day or night
• day: from 9h30 to 16h
• night: before 6h
• Simulation performed from 6h to 6h the next day with goals:
• recover the same temperatures: Tint, Tconcrete, TPCM and the same PCM loading• in case of insufficient heating time à study the drops of Tint, Tconcrete, TPCM and PCM loading
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} but no more than 6h30
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Day loading:
PV panels à Heat pump: 12KW à PCM
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Tem
pera
ture
(°C)
Daytime (hour) 15
T PCM board
T air int
Tc = 23°CDay loadingsimulation results
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Daytime (hour) 16
T air int
PCM discharge:• Tc=23°C à comfort temperature
until Text = -10°C• Tc=26°C à comfort temperature
until Text = - 5°C
• superiority of 23°C PCM due to lower overnight discharge than 26°C PCM
Day loadingsimulation results
Tc = 26°CTc = 23°C
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Tem
pera
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(°C)
Daytime (hour)
Tc = 23°C
T PCM board
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Night loading:
Electricity Network à Heat pump: 12KWà PCM
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Tem
pera
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Daytime (hour)
T PCM board
T air int
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Night loadingsimulation results
Tc = 23°C
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Tem
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T PCM board
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Night loadingsimulation results
Tc = 26°CTc = 23°C
T air int
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Tem
pera
ture
(°C)
Daytime (hour)
Tc = 23°C
• Both PCM: Tc=23°C and Tc=26°C allow to maintain comfort temperature until Text = -5°C
• Night loading requires a larger storage capacity than day loading due to large time-lag between PCM charge and discharge
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Passive versus active PCMcomparison
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12kW: 4½ h
passive PCM 23°C
active PCM 23°C
day loading, Text = 0°C
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12kW: 4½ h
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Conclusion• Concept of active PCM walls for heating validated by lab tests and simulations:
• + 5°C in 40mn• Studied system suitable for outdoor temperatures between -5°C and +10°C
• PCM with Tc =23°C has higher performances compared to 26°C (due to lower overnight discharge) but requires ventilation• Day loading requires lower storage capacity than night loading (due to lower
heating-loading time-lag)• Active PCM has lower heat losses at night time than passive PCM (continuous
natural convection)
PERSPECTIVES and OUTLOOK• For very cold days: combination of day solar power
+ the necessary night loading defined after weather forecast• PCM with Tc of 23°C can also provide cooling• Integration in real building / demonstrator
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Thank you for your attention!
Questions?
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Back-up slides
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1rst élément central elements last element
ventilation
thermocouple
opening with grid
floor
floor
floor
sidecut
Air flow
3-wayvalve
Heating systembetween PCM plates
Modularelements ~ 25 cm
floor
heig
ht
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PCM loaded at 06:00 am / at 16:00 pm
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U = 0.15 W/Km2
U = 0.15 W/Km2
with latent heat in a single step
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PCM loaded at 06:00 am / at 16:00 pm
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