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Polyurethane aerogels were prepared via sol–gel synthesis and dried with supercritical carbon dioxide (CO 2 ) according to catalyst concentration. The influence of this parameter was investigated, first in order to modify the reaction kinetics, then to study its impact on several characteristics. It was observed that this parameter influences the global shrinkage and the bulk density of the resulting materials. The effect of catalyst concentration on the dry samples was then studied in terms of textural, thermal and mechanical properties, thanks to scanning electron microscopy (SEM), nitrogen (N 2 ) adsorption, non-intrusive mercury (Hg) porosimetry, thermal conductivity measurements and uniaxial compression tests. Results allowed us to identify correlations between these characteristics and to determine an optimal density range for thermal and mechanical compromise associated with a fine internal mesoporous texture. [ABSTRACT FROM AUTHOR]

Abstract: Light envelopes are more and more frequently used in modern buildings but they do not present sufficient thermal inertia. A solution to increase this inertia is to incorporate a phase change material (PCM) in this envelope. This paper presents the performance of a test-cell with a new structure of light wallboards containing PCMs submitted to climatic variation and a comparison is made with a test-cell without PCMs. To improve the wallboard efficiency a vacuum insulation panel (VIP) was associated to the PCM panel. This new structure allows the apparent heat capacity of the building to be increased, the solar energy transmitted by windows to be stored without raising the indoor cell temperature, and the thickness of the wallboard to be decreased compared with that of traditional wallboards. An experimental study was carried out by measuring temperature and heat fluxes on and through the wallboards. The indoor temperature, which has a special importance for occupants, was also measured. A numerical simulation with the TRNSYS software was carried out in adding a new module representing the new wallboard. It showed a good agreement with experimental results. This new tool will allow users to simulate the thermal behaviour of buildings having walls with PCMs. [Copyright &y& Elsevier]

Abstract: In the objective to define passive components for the light envelope of buildings, different types of wallboards containing a phase change material (PCM) were studied. The high storage capacity should enable the overall thickness of wallboards to be less than 5cm. To lower the investment costs, the wallboards were made from commercial panels after a first attempt of using gypsum walls. Three types of wallboards were studied: (i) a polycarbonate panel filled with paraffin granulates; (ii) a polycarbonate panel filled with polyethylene glycol PEG 600; (iii) a PVC panel filled with PEG 600 and coupled to a VIP. An experimental set-up was built to determine the thermal response of these wallboards to thermal solicitations. Experimental results were compared to those obtained by a numerical simulation in which an apparent heat capacity method was used. The final results show that the last studied wallboard could be used in the test cells under construction and then validate the concept. [Copyright &y& Elsevier]

This paper presents the first passive solar wall providing simultaneously super insulation, heat storage and daylighting to the inner space. The wall’s external layer is composed of a silica aerogels bed for high insulation and solar radiation transmission. The second layer, internal, is composed of glass bricks filled with a eutectic phase change material (PCM) for heat storage and restitution. The whole wall is translucent. The experimentations carried out to characterize thermal and optical properties of the materials used are described. Then results are given for a full scale comparative experimentation on a twin zones building located in the south of France for the solar wall and a standard opaque high thermal capacity wall. Results show the heat losses through the wall are very low while the heat and light gains are high: The U value of the solar wall is 0.59 W m −1 K −1 and 0.72 W m −1 K −1 respectively when the PCM is in liquid and solid state. With the test building in free floating condition, the temperature difference between the outdoor and indoor air provided by the wall is about 9 °C in winter. The wall can provide up to 500 lux to the inner environment, which is sufficient for conference rooms. The tested wall has proven more effective in winter and shoulder season, particularly for cold sunny climates, but may cause overheating in summer. [ABSTRACT FROM AUTHOR]

Monolithicpectin aerogels, aeropectins, were prepared via dissolution–gelation–coagulationand subsequent drying with supercritical CO2. Aeropectinhad pore sizes that varied from mesopores to small macropores andcompression moduli in the range from 4 to 18 MPa. Aeropectins showplastic deformation up to 60% strain before the pore walls collapse.Pectin aerogels have a thermal conductivity below that of air in ambientconditions, making them new thermal superinsulating fully biomass-basedmaterials. The contribution of gas and solid conduction plus radiativeheat transfer were determined and discussed. [ABSTRACT FROM AUTHOR]

Abstract: An experimental and numerical simulation study of the application of phase change materials (PCMs) in building components is presented for thermal management of a passive solar test-room. The experimental study was conducted in an outdoor test cell constituted of two small rooms separated with a wall containing PCM. A specific wall made of hollow glass bricks filled with PCM was studied. Three PCMs were tested: fatty acid, paraffin, and salt hydrate whose melting temperatures are 21°C, 25°C and 27.5°C respectively. Indoor and outdoor temperatures were measured with thermocouples. Ten fluxmeters located at the centre of each wall allowed us to measure the heat fluxes across the walls. Tests were carried out in real climatic conditions. A one-dimensional numerical model has been developed to simulate the transient heat transfer process in the walls. Reasonable agreement between the simulation and the experimental results was observed. [Copyright &y& Elsevier]

Abstract: The present paper deals with the thermal study of honeycomb panels for short-term heat storage. Using honeycomb panels filled with Phase Change Materials (PCMs) allowed us to fulfil two criteria: enhancement of thermal conductivity and containment to avoid possible leaks. Paraffin whose thermal properties have been measured has been chosen as PCM. The response of the PCM panel to temperature variations was studied with a specific test bench. Temperature and flux measurements clearly showed a significant thermal inertia increase compared to samples filled with air and water. Modelling and numerical simulation have been carried out and validated with the experimental results. [ABSTRACT FROM AUTHOR]