A study on frost and high-temperature resistance performance of supercooled phase change material-based flat panel solar collector

Abstract

Easy freezing and overheating of the flat panel solar collector (FPSC) limits its large-scale application. In addition to the characteristics of high heat storage density and low price, inorganic supercooling phase change materials (PCMs) also have a large difference between their melting and freezing points, which fully meets the needs of FPSCs. In this paper, a new type of supercooled PCM as an FPSC was designed and studied, and a computational fluid dynamics (CFD) model was verified by experiments. Simulations were done to analyze the effects of different structures and PCM properties on the thermal efficiency and cooling rate of the collector. The results showed that the efficiency increase rate of the absorber plate was about 15% when the absorber plate was in direct contact with the PCM under neutralization. For the PCM with a melting point of 323.15 K and a supercooling degree of 30 K, the increase rate of the cooling time can reach more than 15% compared with that of a non-supercooled PCM. The structure of FPSC was optimized, and the thickness of PCM was studied in typical geographic areas. Except for Chengdu, the reliability index of the supercooled phase change material FPSC (SPCM-FPSC) in winter and summer was found to increase to more than 0.5 compared with 0.1 for ordinary FPSCs. It was found that the SPCM-FPSC significantly improved the freezing and high-temperature resistance of collectors in various regions. These results provide a strategy for the promotion and application of FPSCs in harsh outdoor environments.