Impact of relative positioning of heat source and thermoelectric generator on performance of phase change material - thermoelectric system

Applying phase change materials to thermoelectric generators can alleviate the issue of output instability caused by fluctuations in heat sources. In this study, a three-dimensional model of phase change material - thermoelectric generator was established to investigate the influence of the relative positioning of thermoelectric generator and heat sources on the solid-liquid phase change of phase change material and the performance of thermoelectric generator. The results indicate that, compared to conventional thermoelectric generator, the incorporation of phase change material, while extending operational duration, leads to a reduction of 23.4 % and 23.2 % in total output power and average efficiency, resulting in values of 1493.1 J and 1.29 %, respectively. When thermoelectric generator is arranged parallel to the heating surface, the phase change material melting is rapid during the heating stage but with lower electricity generation, whereas during the non-heating stage, the electricity generation is higher due to the energy storage capability of phase change material. The effective operating time is related to the minimum operating voltage, and when the minimum operating voltage reaches 80 % of the peak operating voltage, the effective operating time is lower than that of traditional TEGs. Changing the installation position results in a 7.2 % difference in total electricity generation during the heating stage, with an even larger disparity of 18 % during the non-heating stage. These findings have significant implications for the construction of efficient phase change material - thermoelectric system.