Thermal design of solar thermoelectric generator with phase change material for timely and efficient power generation

Solar thermoelectric energy-generation technology is being developed to mitigate the limitations of solar cells. Thermal management is essential to creating highly efficient and stable solar thermoelectric generators (STEGs). Phase change materials (PCMs) can be used to improve the performance of STEGs. In this study, we numerically investigate the heat transfer, thermal energy storage, and thermoelectric energy conversion in an STEG with PCMs (STEG-PCM). Based on a parametric study, we present thermal design guidelines for the configurations of an STEG-PCM and the thermal properties of PCMs by considering both the thermoelectric generation performance and thermal stability of the STEG-PCM. We also show that the PCM-impregnated structure is the most crucial component of the STEG-PCM in the thermal design based on a sensitivity analysis. To find the optimal design of a PCM-impregnated structure, topology optimization is performed for the STEG-PCM focused on daytime thermoelectric generation performance. The topology-optimized PCM-impregnated structure shows a thermoelectric generation performance close to that of an STEG-PCM whose PCM-impregnated structure is assumed to be an ideal mixture of PCM and framework material. This study explains how PCMs affect thermal energy transport and conversion in an STEG and sheds light on a highly efficient and stable STEG system.