Enhancing Melting-Solidification Performance of Latent Heat Thermal Energy Storage Units with Twisted Fins

To enhance the heat transfer efficiency of latent heat storage devices, this study proposed a novel composite fin structure and applied it to vertical shell-and-tube latent heat thermal energy storage (LHTES) units. The enthalpy-porosity method was used for numerical simulation of the phase change process, and the heat storage and release performance of different units was systematically evaluated. The results indicated that the novel configuration, combining longitudinal and twisted fins, significantly enhanced both natural convection and heat conduction, effectively compensating for the heat transfer limitations of traditional longitudinal and annular fins. Compared with conventional longitudinal fins, it reduced the complete melting and solidification time of the phase change material (PCM) by 32.57 % and 23.05 %. Although its complete solidification time was slightly longer than that of conventional annular fins, it achieved the highest heat storage and release rates. When the PCM reached a phase change fraction of 0.95, the heat storage and release capacities of this structure were 10.9 % and 3.4 % higher than those of annular fins, respectively. This study provides theoretical guidance for the design and development of new large-scale, high-efficiency latent heat storage devices.