Numerical study on the discharging performance of a latent heat thermal energy storage system with fractal tree-shaped convergent fins

In this paper, an innovative fractal tree-shaped convergent fin (FTSCF) is embedded into a latent heat thermal energy storage system (LHTESS) to numerically investigate the parametric influences of FTSCF including FTSCF number N, maximum branching level m, length ratio alpha, branch convergence beta, level convergence gamma, rotation angle delta of the branch at the outermost level and branching angle theta u on the discharging performance of the LHTESS under the fixed total fin volume. The results imply that increasing N, m, and alpha significantly reduces the complete solidification time z of the phase change material (PCM). Further, the z of the PCM demonstrates a pattern of initial decrease followed by an increase under the influences of beta, gamma, and delta, indicating the presence of an optimal FTSCF structure maximizing the discharging efficiency of LHTESS. Compared to the fins without branch convergence, the minimum tau of PCM within the LHTESS reduces by 4.33 %, 5.03 %, and 12.42 % by the branch convergence beta when gamma = 0.5, 0.707, and 1. In addition, the minimum z of PCM monotonically decreases when theta 1 = theta 2 increases from 50 degrees to 90 degrees. The present work provides a technique to improve the discharging performance of the LHTESS by using fin convergence.