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Latent heat storage in concrete
Dipl.-Ing. Jens H. Dieckmann
University of KaiserslauternDepartment of Construction Physics and Technical Equipment
Prof. Dr. rer. nat. H. Heinrich
Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Principle effect
conclusion:In a small temperature range a lot of energy can be stored with small mass and volume of the material.
Latent heat storage
Latent heat storage
PCM products
Innovation
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Example water
The heat of fusion is nearly as much as energy can be stored in the liquid phase.
Latent heat storage
PCM products
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Phase change materials (PCM)
For applications in the building structure paraffins and salt hydrates are suitable.
Latent heat storage
PCM products
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Comparison of thermal masses
Comparison of the layer thicknesses of different building materials heat capacity: approx. 5700 kJ Temperature range: 10 K
Latent heat storage
PCM products
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
PCM as building product
PCM can't be used directly as building product because of their material properties (e.g. melting)!
At present there are three solutions to get PCM into common building products: - Macro encapsulation - Micro encapsulation - Storage in porous matrix structures
Latent heat storage
PCM products
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Macro encapsulation
Kissmann, Germany Christopia, France
TEAP, Australia
Latent heat storage
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Microencapsulation
Knauf KG Gypsum plasterboard
Maxit Group Climatic finery
Micronal,
BASF AG
Further one: Aerated concrete stones, loam plates…
Latent heat storage
PCM products
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
PCM in carrier structures
Advantage: - Better activating because of better heat conductivity - No problems by volume stretch - Inexpensive
Fiber boards (Rubitherm) clay/tone - granulates (Rubitherm)
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
The innovation
+In order to develop a kind of concrete which can be directly used in the construction elements with improved physical characteristics.
Latent heat storage
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We connect non capsulated paraffin with light weight rock granulations.
Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Advantages
Depending on Application!
• More effective heat storage• Possibly no need for other utilities• Smaller construction units • Constant room temperature • Higher thermal comfort • Protection from overheating• Smoothing of temperature peaks • Shift of the peak load times • Saving of fossil energies
Latent heat storage
PCM products
Innovation
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Development process
Phase 1: Selection of the suitable light rock granulation as PCM carrier matrix and the selection of the further concrete components
Phase 2: Choice of a suitable filling variant
Phase 3: Development of concrete recipe
Phase 4: Analysis of the improved thermal material properties
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Phase 1
Considered the characteristics of building material-technological and building physics aspects, e.g.
• Large PCM capacity
• High heat conductivity
• High firmness
in order to assure the suitability of the materials for our purposes.
Latent heat storage
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Phase 1
Micro copies:
Blowing glass: Wash pumice:
Large differences in surface texture, pore volume, pore size, pore distribution, pore type…
Latent heat storage
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Phase 1
Basis is the DIN 4226-2 and DIN EN 13055-1 • Bulk density according to DIN EN 1097-3 • Water absorption according to DIN EN 1097-6 • Gross density according to DIN EN 1097-6 • Pure density according to DIN 52102 • Overall porosity according to DIN 52102 • Water content according to DIN 1097-5 • Determination of the heat conductivity according to DIN 52612 • Grain pressure strength after appendix A of the DIN EN 13055-1…
Lab tests from the building material-technological and the building physics aspect:
Latent heat storage
PCM products
Innovation
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Result:Wash pumice, nature pumice, blowing glass, blowing slate
Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Phase 1
Lab tests from the building material-technological and the building physics aspect:
Basis is the DIN 4226-2 and DIN EN 13055-1 • Bulk density according to DIN EN 1097-3 • Water absorption according to DIN EN 1097-6 • Gross density according to DIN EN 1097-6 • Pure density according to DIN 52102 • Overall porosity according to DIN 52102 • Water content according to DIN 1097-5 • Determination of the heat conductivity according to DIN 52612 • Grain pressure strength after appendix A of the DIN EN 13055-1…
Latent heat storage
PCM products
Innovation
Development
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Result:Wash pumice, nature pumice, blowing glass, blowing slate
Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Phase 2In phase 2 different filling variants were examined.
•Melting
•Evacuation
•Splashing
Latent heat storage
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Result:
up to 100 M.% admission
Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Phase 3
Find a suitable concret recipe!
Consideration of the desired material properties such as minimum pressure firmness, Pump ability, and maximum PCM content
Challenges:
e.g. separation,
Heat of hydration
Latent heat storage
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
0
5
10
15
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22 24 26 28 30 32
C[k
J/(k
g²K
)]T [°C]
0
5
10
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22 24 26 28 30 32
T [°C]
C[k
J/(k
g²K)
]
Phase 4
PCM concrete PCM content: (wet): 26,8 V.% 16,4 M.%
Lightweight concrete More directly Composition without PCM
Theoretical, idealized result of the specific heat capacity
Latent heat storage
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Spec. Thermal capacity PCM concrete: 45,86 kJ/Kg Spec. Thermal capacity comparison concrete: 19,16 kJ/Kg
Increase about 139%
Phase 4 – heat capacity
0,00
5,00
10,00
15,00
20,00
25,00
30,00
35,00
40,00
45,00
50,00
21,00 23,00 25,00 27,00 29,00 31,00
T[°C]
Δc [k
J/kg
]
Result:Latent heat storage
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Phase 4 – intermittent heat transferLatent heat storage
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Wooden test wall between two climatic rooms
Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Two different test disks (50*50cm) in the test wall
Phase 4 – intermittent heat transferLatent heat storage
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Programmed temperature characteristics
Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
maxio ,ϑao,ϑ
ao,ϑΔ
ϑ
Mϑ
min ao,ϑ
ao,p
max ao,ϑ
io,ϑΔ
Mϑ io,p
max io,ϑ
min io,ϑ
Programmierte Temperaturverläufe
0
510
1520
25
3035
40
0 2 4 6 8 10 12 14 16 18 20 22 24
t [h]
T [
°C]
Außen (Klimaraum I) Innen (Klimaraum II)
Heat flow trough the test wall
Phase 4 – intermittent heat transferLatent heat storage
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Phase 4 – intermittent heat transfer
Intermittent heat transfer:
Latent heat storage
PCM products
Innovation
Development
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Phase 4 – intermittent heat transfer
Intermittent heat transfer:
Latent heat storage
PCM products
Innovation
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Phase 4 – intermittent heat transfer
Result:
Improvement: 78%
Improvement: 26 %
Latent heat storage
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Innovation
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Thermography cooling down behavior
Thermography image at beginning of the test
Thermography image after 2 hours
Thermography image after 4 hours
Cooling down behavior
Latent heat storage
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
• The PCM concrete can be designed for the requirements of application
• PCM concrete can support the building heat or protect from summer overheating
• the Implementation as active system increases the efficiency of the heat storage
Summary / ConclusionLatent heat storage
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
• Possible locations in the building structure are ground, walls, cover…
Summary / ConclusionLatent heat storage
PCM products
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Activated base plate for heater support
One example of useLatent heat storage
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Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
Thank you foryour attention
Latent heat storage in concreteDipl.-Ing. Jens H. Dieckmann
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