Numerical Simulation of Natural Convection-Dominated Melting and Solidification From a Finned Vertical Wall

A numerical study has been conducted of natural convection-dominated melting and solidification of a phase change material (PCM) from a finned vertical wall This work was motivated by the need to accelerate the charge and the discharge processes in latent heat thermal energy storage systems. A fixed-grid enthalpy approach is retained for modeling combined convection-diffusion phase change. The numerical model is validated with experimental data. Solutions are obtained for a cavity of height H = 0.2 m; widths W = 0.04 and 0.02 m; with 0, 4, 9, and 19 horizontal fins of length L = 0.01 and 0.03 m; a heated wall temperature set at 13-53 K above the melting temperature (1.6 x 109 ⩽ RaH ⩽ 8.08 X 109); and cooled wall temperature set at 16 K below the melting point. Results indicate that the presence of long fins embedded in the PCM significantly accelerates the melting process. On the other hand, the effect of short fins is much less significant. Despite the fact that their augmented heat transfer area is smaller, it is found that a few long fins are far more efficient in promoting melting than several short fins. Since the rate of solidification is governed by heat conduction, it increases significantly as the number of long fins is augmented.