| Building energy consumption plays a decisive role in total energy consumption in China, if the energy efficiency in buildings are truely improved, the shortage of energy will be greatly alleviated and the construction and development of our national economy will be promoted. Phase change materials can store and release energy during phase change process, so applying phase change materials to the constructions can reduce the room temperature fluctuations, realize the room temperature adjustment, and improve the room comfort and energy utilization.This paper used the liquid paraffin and 52 # paraffin wax as a mixture of phase change materials and the mixture was sucked into the expanded perlite and ceramic sand through a high temperature adsorption process, after soaked in the potassium silicate solution and CaCl2 solution, two kinds of phase change materials were prepared.The pore structure of expanded perlite and ceramic sand was characterized by the method of mercury intrusion, the results showed that: the expanded perlite's pore size was mainly within 20 microns or so, the pore ratio was 74.43%, while the pore size of ceramic sand was mainly distributed in about 100 nm, the pore ratio was 40.97%. The liquid paraffin wax can enter into the pores whose size was above 20 microns and 25 nm in expanded perlite and ceramic sand,separately, considering the pore sizes and their distribution, the liquid paraffin wax can fill the most pore structure of expanded perlite and ceramic sand.Based on the analysis of DSC, the phase change temperature of paraffin wax mixtures was found at 28.47℃and its latent heat was 112.42J/g, while the phase change temperature and the latent heat of the two kinds shape-stabilized phase change materials was 24.58℃,23.67℃and 88.57J/g,24.43J/g, separately.Their phase change temperature had a slight decline and latent heat was also reduced closed to the quality percentage of the phase change material in matrix.The stability analysis of the two kinds shape-stabilized phase change materials indicated that after 50 times, 100 times and 150 times phase change cycle, not only their loss of quality, but also the loss of their phase change temperature and phase change latent heat was very small, the loss rate was no more than 3%, which showed that the shape-stabilized phase change materials were stable in thermal physical performance.As the increase of the amount of the phase change material, the compressive strength, bulk density and thermal conductivity of the energy storage mortar were gradually reduced, while the heat capacity was increase gradually, for the expanded perlite, ceramic sand and their composite, the coefficient of thermal conductivity was reduced from 1.348W/m·K to 0.254W/m·K, 0.275W/m·K and 0.188W/m·K respectively, while their heat capacity was increased from 1.11kJ/kg·K to 2.31kJ/kg·K, 1.54kJ/kg·K to 2.44kJ/kg·K and 2.14 kJ/kg·K to 2.29kJ/kg·K respectively, and the heat storage coefficient of the mortar was between 11.38W/m~2·K and 23.48W/m~2·K. As heating and cooling the phase change board and the normal board, it is found that the cooling and warming rate of the phase change board were lower than the normal one, there was a large temperature and time differences between them, the biggest temperature and time difference can be reached to 26.1℃and 42min,separately. |
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