Using pin fins arrangements to improve melting heat and mass transfer in a cylindrical enclosure

This study presents a numerical investigation of the melting behavior of RT35 phase change material (PCM) in latent heat thermal energy storage (LHTES) in the presence of pin fins. The influence of specific 3D arrangement of the pin fins on the heat and mass transfer and natural convection flows was addressed in a full 3D model of the enclosure including the phase change effects. The primary motivation for using cylindrical fins was to allow molten PCM to flow more freely through fin rows, enhancing natural convection. Results reveal that increasing the number of fin rows enhances conduction heat transfer but can obstruct natural convection flow in molten PCM, reducing convection and hindering overall efficiency. Optimizing the number of fin rows is critical to balancing these effects, achieving significant improvements in the heat transfer and energy storage performance. To mitigate the negative impact of increased fin rows on natural convection, staggered fin arrangements were introduced, leading to a 27.9 % reduction in melting time compared to the base case without fins. Additionally, the inline configuration provided a 29 % acceleration in heat transfer and PCM melting time compared to a base case. Cylindrical fins were 10.2 % better than disk fins. Thermal energy storage in cylindrical fins in a shell-tube cylindrical cylinder energy storage unit.