Study On Energy Saving Potential Of A Building Roof Incorporating Double Layers PCM In Hot-Summer And Cold-Winter Zone

With the increasing demand for energy consumption,phase change materials(PCM)have attracted extensive attention due to their advantages such as high energy storage density,heat absorption and heat release under approximately constant temperature.The combination of PCM and building envelope can effectively reduce indoor temperature fluctuations and building energy consumption.Most of the existing studies focus on the combination of PCM,building external walls and floors to explore the energy saving effect of phase change materials.In this paper,the effect of PCM on building roof is studied.The object of this paper is the double layers PCM roof structure.Double layers PCM are installed inside the roof of the building,and the low-temperature PCM are closer to the indoor side.Previous studies have shown that the double-layer PCM of this structure can better reduce building energy consumption,Compared with single-layer PCM,the combination of double layers PCM can reduce the total annual energy consumption of the building and achieve the effect of building energy conservation.In this paper,the optimal phase transition temperature of two kinds of PCMs was first explored.The optimal phase transition temperature of high-temperature PCM and lowtemperature PCM was determined by comparing the total indoor load of rooms with different roof structures through TRNSYS simulation software.In order to explore the energy saving potential of the double-layer PCM in building roof throughout the year,the simulation study was carried out under four different working conditions of opening air conditioning in summer,not opening air conditioning in summer,opening air conditioning in winter and not opening air conditioning in winter.By comparing the indoor air temperature of different roof structures and the heat flow on the inner surface of the roof,the influence of the two-layer PCM in building roof on the indoor thermal environment is studied.In this paper,the ability of the PCM to adjust the indoor thermal environment and the annual energy saving potential of two-layer PCM in building roof are studied,which provides a variety of possibilities for the combination of PCM and buildings,and promotes the application of PCM in real life.