Heat transfer mechanism and structure design of phase change materials to improve thermoelectric device performance

In recent years, the use of phase change materials (PCM) to improve the output performance of semiconductor thermoelectric generators (TEG) and maintain the long-term work of TEG has received widespread attention. Because of the lack of a unified understanding of the existing PCM-TEG combination mode and PCM structure design, this paper first established a PCM-TEG coupling mathematical model, the accuracy of which is proved by experimental data. Secondly, for the three most common combinations of PCM and TEG, namely cold-sided, hot-sided and dual-sided PCM-TEG, the effect of PCM on TEG, the effect of finned PCM on system performance, and the system anti-interference ability when the heat source is unstable are respectively studied from the heat transfer mechanism. The results show that 1) PCM's high heat storage characteristics can effectively protect TEG and avoid device failure due to excessive temperature; 2) Designs of metal fins within PCM can effectively maintain advantages of the PCM and significantly enhance the temperature difference between the hot and cold ends of TEG, thereby significantly improving the system performance; 3) The cold-sided PCM-TEG system has the best output but the worst anti-interference ability compared to the hot-sided or dual-sided design. On a comprehensive basis, the dual-sided design is recommended in practice; 4) The cooling capacity of the PCM-TEG system significantly affects the performance. Enhancing the heat transfer coefficient of the cold end of the TEG can significantly improve PCM-TEG systems' performance.