Présentation PowerPointMICRO-NANO POROUS MATERIALS
FOR HIGH PERFORMANCE
Daniel QUENARD – Hébert SALLEE Centre Scientifique et Technique du Bâtiment – CSTB – French Building Research Institute Envelope & Coverings Department - Material Physics Division Tel : 33 4 76 76 25 46 – Email : quenard@cstb.fr
2nd International Symposium on NANOTECHNOLOGY in CONSTRUCTION BILBA0 – 13-16 nov. 2005
Date | SERVICE OU DEPARTEMENT | PAGE 2
From Energy Wasting …
"Almost half of Europe’s energy is consumed in its 160 million buildings.”
ENERGY END-USE EFFICIENCY By Andrew Warren METERING INTERNATIONAL ISSUE 1 2005
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Green Paper on Energy Efficiency or Doing More with Less
FINAL ENERGY DEMAND Europe 2002 Buildings Industry Transport Total
Residential/Tertiary Unit 437.8 306 338.9 1083 Mtep 40.4 28.3 31.3 %
France 46 25 29 %
Electricity 12 %
… to Energy Saving
Among the different measures (efficient boilers, thermal & PV solar collectors) to reduce energy consumption, for both residential and non-residential buildings,
Improvement of building envelopes is by far the most reliable and most cost-effective way to reduce both energy use and CO2 emissions
Thermal Insulation (roofs, walls, windows)Thermal Insulation (roofs, walls, windows), Airtightness & Solar gains
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Thermal Insulation
Source : http://perso.wanadoo.fr/rbm
Source : http://arcticinuit.free.fr
Insulating Materials
Airtight Foil
VIP λVIP = 5 - 10 mW.mK
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Fumed Silica
SiCl4 + 2 H2 + O2 → SiO2 + 4 HCl
Burner SiCl4 + 2 H2 + O2 SiO2
SiO2SiO2
SiO2
SiO2
Source : WACKER Ceramic
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Wacker HDK® PYROGENIC SILICA TAMPED DENSITY
Fumed silica appears as a fluffy white powder characterized by an extremly low tamped density down to ~ 50 kg/m3.
Density of SiO2 : ~ 2200 kg/m3
Primary particles do not exist as individual units outside the flame
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Hygrothermal Properties of Micro-Nano Porous Silica
Porosity Porosity –– Density Density –– Specific AreaSpecific Area
Pore Size DistributionPore Size Distribution
Water Vapor AdsorptionWater Vapor Adsorption
Thermal Conductivity vs Pressure, Moisture & TemperatureThermal Conductivity vs Pressure, Moisture & Temperature
VIP : Vacuum Insulation PanelVIP : Vacuum Insulation Panel
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Density, Porosity & Specific area
MW or EPS : 13 to 40 kg/m3
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Thermal Conductivity in Porous Materials
rgsrgse λ+λ=λ+λ+λ=λ +
1 : solid conduction (phonons) 2 : gas conduction (molecules) 3 : radiation (photons)
( ) sggs 1 λ⋅ε−+λ⋅ε=λ +
ε : porosity > 90 %
Thermal Conductivity vs Total Pressure & Pore Size
1E-3 0.01 0.1 1 10 100 1000
4
8
12
16
20
24
28
Pressure hPa
Fumed Silica 1 CSTB Fumed Silica 2 CSTB Precipitated Silica CSTB Fumed Silica ZAE PU Foam
T he
rm al
c on
du ct
iv ity
1 0-3
W /m
.K δ
100 µm
0.1 µm
Thermal Probe
Gas Thermal Conductivity vs Total Pressure & Pore Size
g
1 : Low Pressure Pg
2 : Confinement / Knudsen Effect : pore size δ < lm mean free path - δ ∼ 0,1 µm (air)
source : www.empa.ch
Humid Air
CO2 0,03 % Xe, Kr, Ne, He 0,01 %
Dry Air
Water Molecule – Molecular Adsorption
Capillary Condensation Kelvin-Laplace Law
0.1 µm 99 % RH
Molecular Adsorption & Capillary Condensation
0.05
0.10
0.15
0.20
0.25 Fumed Silica 1 CSTB Fumed Silica 2 CSTB Fumed Silica NRC Fumed Silica ZAE
W at
er c
on te
nt k
g/ kg
Relative humidity
Molecular Adsorption
Capillary Condensation
Thermal Conductivity vs Water Content
0 5 10 15 20
20
30
40
50
60
T he
rm al
C on
du ct
iv ity
1 0-3
W /m
u : Water Content
uBeu ⋅+λ=λ
Thermal Conductivity vs Vapor Pressure
0 5 10 15 20 25 30
20
30
40
50
60
T he
rm al
C on
du ct
iv ity
1 0-3
W /m
T=23°C – HR = 70 % Pv = 20 hPa
PV = RH.Pvs(T)
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Thermal Conductivity vs Total Pressure & Water Content
0.01 0.1 1 10 100 1000
5
10
15
20
25
30
35
40
Fumed Silica 2 CSTB dry 30% RH 54% RH 70% RH 80% RH
T he
rm al
C on
du ct
iv ity
100 28,08
Salt Solution
Sample Probe
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Thermal Conductivity vs Temperature
280 300 320 340 360 380 400 420 440 460 480 500 520 2
3
4
5
6
7
8
Fumed Silica 1 CSTB Fumed Silica 2 CSTB Fumed Silica ZAE Precipitated Silica ZAE Fumed Silica 1 NRC
T he
rm al
c on
du ct
iv ity
Simplified Model
Solid + Water
Conclusion
MicroMicro--Nano Porous Silica are good candidates to make VIPNano Porous Silica are good candidates to make VIP’’ss
The Thermal Conductivity is close to The Thermal Conductivity is close to 5 mW/m.K5 mW/m.K at a presssure at a presssure of 10 hPa (0,01 bar).of 10 hPa (0,01 bar).
Due to their high specific area and the microDue to their high specific area and the micro--nano size of their nano size of their pores, porous silica are very sensitive to moisture. Protection pores, porous silica are very sensitive to moisture. Protection against water molecules penetration are essential.against water molecules penetration are essential.
With an initial pressure of 0,01 hPa, there is a safety margin oWith an initial pressure of 0,01 hPa, there is a safety margin of f 3 order of magnitude 3 order of magnitude …… but durability will strongly depend on but durability will strongly depend on the airtightness of the envelope (foil + welding).the airtightness of the envelope (foil + welding).
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Supports & Acknowledgements
The results presented in this paper have been obtained within the framework of 3 projects : > Characteristion of Nanoporous Silica - ADEME-EDF-CSTB > European Project VIP-PSS
> Vacuum Insulation Panel – Product & Service System
> Annexe 39 IEA (International Energy Agency ) > HIPTI : High Performance Thermal Insulation
Acknowledgements : > B. Yrieix : EDF - S. Kherrouf : ADEME – Peter Randel : WACKER > H. Sallée - C. Pompéo - FD. Menneteau : CSTB
From Energy Wasting …
… to Energy Saving
Hygrothermal Properties of Micro-Nano Porous Silica
Density, Porosity & Specific area
Thermal Conductivityvs Total Pressure & Pore Size
Gas Thermal Conductivity vs Total Pressure & Pore Size
Humid Air
Thermal Conductivity vs Total Pressure& Water Content
Thermal Conductivity vs Temperature