Optimization Research on the Multilayer Wall Integrated with a PCM Layer

The phase change material (PCM) used in a building wall can reduce building energy consumption and improve the living comfort level. However, only when the temperature of the PCM layer is between phase transition temperature ranges can it have the maximum effect to increase the thermal inertia. How to select the suitable PCM according to the local weather and building wall always troubles building engineers and affects the wide use of PCM on building energy efficiency. Aiming at present situation, this paper numerically analyzed the energy conservation of building multilayer wall integrated with a PCM layer to optimize PCM thermophysical properties and wall structure under the Chengdu typical climates of winter, summer and transition seasons. The numerical simulation used the heat transfer model of the enthalpy-porosity technique, which was verified by the experiment. The results show that the PCM layer can decrease the building annual load, increase the time lag, decrease the decrement factor and improve occupants' comfort. When the phase change occurs under the suitable temperature conditions, high latent heat is conducive to decreasing the heat flow fluctuation, increasing the time lag and improving inner surface temperature stability. It is more efficient that the PCM layer is located next to the internal surface and under this condition, the optimum solidus and liquidus temperatures are 14°C and 26°C respectively, under the Chengdu climates. And the annual inner surface heat flow can be reduced up to 13.36% for the PCM layer of 30mm and 9.64% for the PCM layer of 20mm compared with no the PCM layer.