Experimental Research on a Solar Energy Phase Change Heat Storage Heating System Applied in the Rural Area

Abstract

Thermal energy storage technology can effectively promote the clean heating policy in northern China. Therefore, phase-change heat storage heating technology has been widely studied, both theoretically and experimentally, but there is still a lack of engineering application research. According to the characteristics of heating load in northern rural areas, a kind of solar heating system using phase-change materials (PCMs) for heat storage is proposed. Furthermore, a farmhouse is used to demonstrate the practical engineering applications of the heating system. The heating system consists of the phase-change heat storage device (PCHSD), solar thermal panels, and a floor radiant heating terminal, which can realize the effective utilization of solar energy. Considering solar power generation capacity, heating load characteristics of farm buildings, and the local electricity price model, four potential operation modes of the heating system are established. Then, the corresponding control strategies are proposed for the four operating modes. The actual operation data of the heating system under different operating modes were collected continuously, and the application effect of the heating system was evaluated from the aspects of thermal efficiency of the device, the renewable energy efficiency, thermal comfort level, and economy. The experimental results show that: (1) The thermal efficiency of the device is mainly affected by the heating load, which can reach more than 80% during the test period; (2) the renewable energy efficiency of the system is positively correlated with the solar radiation intensity, and the maximum can reach 100% when the solar radiation is sufficient; (3) the system maintains excellent thermal comfort in all conditions, with the average and the highest thermal comfort time accounting for 80% and 100%, respectively; (4) compared with the average level of existing clean heating technology, the annual operating cost of the system is reduced by 27.3%, and the economy is significant. The results show that the system achieves effective performance during the test period.