Numerical study on melting performance improvement with fractal tree-shaped fins

Abstract

In this paper, the melting performance improvement of phase change material (PCM) in latent heat thermal energy storage (LHTES) systems with fractal tree-shaped fins has been discussed via lattice Boltzmann simulation. The abundant melting phenomena are comprehensive results of the heat conduction and convection. Based on the numerical results, it is found that the existence of tree-shaped fins significantly improves the melting performance, compared with the radical-fin LHTES unit. More specifically, the stretched tree-shaped fins uniform the temperature field and make great contributions for heat transfer enhancement at the early stage of melting process and thereby accelerating the generation of convection with the increase in the liquid phase. Moreover, it is observed that the melting efficiency improves with the increase in branch level ( k) of tree-shaped fins, and this tendency reverses when k exceeds a critical value. The results also indicate both the length ratio and width ratio of tree-shaped fin have a significant influence on melting performance, and the optimal values for the ratios of length and width are 1.0 and 4/9, respectively. Additionally, different arrangements of tree-shaped fins are also considered to reveal the relationships between heat conduction and convection for melting performance improvement.