A numerical study of phase change material melting enhancement in a horizontal rectangular enclosure with vertical triple fins

Abstract

In renewable energy systems, energy storage with phase change materials (PCM) is important, but these materials have poor thermal conductivity; therefore, approaches for improving the performance of these storage systems have become required. This research investigates numerically whether fins affect thermal energy storage (TES) units' behavior during phase changes. Three conductive fins at different positions were attached to the heated bottom wall to enhance the PCM melting process. Different dimensionless fin lengths (a/H = 0.25, 0.50, and 0.75) and dimensionless fin positions (b/L = 0.15, 0.25, 0.35, and 0.75) were considered as parameters to investigate their effect on melting rate. The main objective is to detect the best lengths of the fins and the optimum distance between them to achieve the highest storage performance. The enthalpy-based lattice Boltzmann technique is used to solve velocity and temperature fields for simulations. The results from other researchers validate the numerical predictions. It is found that significant enhancement in the heat transfer is shared between thermal conduction and convection at the initial and final stages of melting, respectively. Increasing the ratios fin lengths of a/H from 0.25 to 0.75, the whole melting period is shortened by 15.1%, 40.7%, and 70.1%, respectively. The best compromise positions ratio for short fins at a/H = 0.25 is b/L = 0.48 till the complete melting of PCM, while its b/L = 0.35 when the fine longer than a/H > 0.50.