Impact of tube shapes on the energy storage and thermal-hydraulic performances of finned latent heat energy storage systems

The imbalance between the demand and supply of intermittent renewable energy can be mitigated by latent heat thermal energy storage (LHTES) devices. This study suggests a novel polygonal tube LHTES system that combines the fins and tube wall into a single structure in order to increase the heat storage power, improve the system's heat transfer efficiency, and effectively enhance thermal conductivity to better meet the needs of industrial production. The effects of fins' maximum vertical height ( L max ) and tube shapes on the LHTES performance are investigated statistically. The results demonstrate that compared to the traditional circular tube LHTES system, employing the polygonal LHTES system can increase average integral heat flux by up to 14.53 %, enhance power by up to 21.21 %, and reduce average integral thermal entropy generation by up to 23.97 %, which effectively reduces the energy consumption of the system. Moreover, increasing L max from 15 mm to 21 mm enables a maximum enhancement of 186.85 % in the mean integral heat flux, a maximum boost of 191.36 % in the power, and a maximum increase of 148.52 % in the mean integral thermal entropy generation. This work can provide theoretical guidance for further research on enhanced heat transfer in polygonal double-tube LHTES systems.