Enhancing latent heat thermal energy storage in triplex tube heat exchangers using tree-shaped fin structures with novel branching methods

In the current research, five tree-shaped fin structures (TSFS) with novel branching methods have been developed to improve thermal energy storage performance. These TSFSs are embedded in the middle layer of a triplex tube heat exchanger (TTHE) containing RT82 phase change material (PCM). The novel designed structures have been compared with the conventional type of TSFS in melting and solidification processes. Validated numerical simulations have been used to carry out these investigations. Among the designed TSFSs, case c demonstrates superior performance compared to the other structures, reducing the completed melting/solidification time (CMT/CST) by 7.36 %/23.70 % compared to the conventional TSFS with Y-shaped branching, case a. Additionally, the liquid fraction contours indicate that, unlike case a, case c could prevent the formation of large and concentrated masses of unchanged PCM. This reduction in bulky masses leads to a similarity in temperature behavior between TSFS and PCM, resulting in a uniform and faster phase transition. Moreover, it is observed that the novel branching method in case c has a more pronounced impact on the solidification process due to the diminished role of natural convection, which typically aids in changing the phase of large and concentrated masses in case a.