Solar multi-mode heating system based on latent heat thermal energy storage and its application

To overcome the discontinuity and instability of solar energy and achieve energy supply and demand regulation and all-weather continuous heating supply of a solar heating system, a solar multi-mode heating method based on latent heat thermal energy storage is proposed. A solar heating system combining integrating vacuum-tube collectors with a latent heat thermal energy storage device is established in a building in Linzhi city, Tibet. The system can perform automatic control and operation of solar multi-mode heating according to the operating condition of solar collectors and external heating demand. Experimental studies show that the vacuum-tube solar collectors can work collaboratively with the latent heat thermal energy storage device. During the daytime, the latent heat thermal energy storage device performs a heat storage with an average charging power of 10.63 kW and a storage capacity of 92.67 kW·h, and the temperature platform of phase change can be apparently observed. At night, the thermal energy storage device can provide a 10-hour continuous discharging process with a total heat output of 85.23 kW·h at a stable discharging power and temperature. The charging-discharging efficiency of the storage device is 92%, and its heat storage density can reach 3.6 times that of a traditional hot-water storage tank. The results indicate that the solar heating system can achieve all-weather continuous heating supply. The present study can provide guidelines for implementation of solar heating in Tibet.