Heat transfer enhancement in solidification process by change of fins arrangements in a heat exchanger containing phase-change materials

Purpose Reducing discrepancy between energy demand and supply has been a controversial issue among researchers. Thermal energy storage is a technique to decrease this difference to increase the thermal efficiency of systems. Latent heat thermal energy storage has interested many researchers over the past few decades because of its high thermal energy density and constant operating temperature. The purpose of this paper is to provide a numerical study of the solidification process in a triplex tube heat exchanger containing phase change material (PCM) RT82. Design/methodology/approach A two-dimensional transient model was generated using finite volume method and regarding enthalpy-porosity technique. After that, a detailed and systematic approach has been presented to modify longitudinal fins' configuration to enhance heat transfer rate in PCMs and reducing solidification time. The numerical results of this study have been validated by reference experimental results. Findings The ultimate model reduced solidification time up to 21.1 per cent of the Reference model which is a substantial improvement. Moreover, after testing different arrangements of rectangular fins and studying the flow pattern of liquid PCM during solidification, two general criteria was introduced so that engineers can reach the highest rate of heat transfer for a specified value of total surface area of fins. Finally, the effect of considering natural convection during solidification was studied, and the results showed that disregarding natural convection slows down the solidification process remarkably in comparison with experimental results and in fact, this assumption generates non-real estimation of solidification process. Originality/value The arrangement of the fins to have the best possible solidification time is the novelty in this paper.