Analysis on Cascade Heat Utilization of Solar Energy in Building Heating Based on Phase Change Thermal Storage

Solar energy is a clean and renewable energy for building heating, it is an environmentally friendly technology which can effectively reduce building energy consumption. However, so-lar energy has the characteristics of low distribution density, discontinuity and instability due to the changeable weather condition, moreover, there is a contradiction in time between the building heating demand in night and the solar energy collection in day. Therefore, a cascade utilization of solar energy with solar heat collection process, phase change heat storage process and capillary radiation heating process is presented in this study. Firstly, a low temperature phase change material is tested and used as an energy storage pool, secondly, the capillary radiation heating is adopted as the terminal heating mode due to its features of low temperature operation mode, large heat transfer area and higher thermal comfort, finally, the performance of the system is calculated and analyzed. The results show that the cascade utilization of solar energy system can store and transfer solar energy from day to night, and it has higher efficiency compared with traditional heat sink mode.