Design of fin structures for phase change material (PCM) melting process in rectangular cavities

Abstract The objective of this work is to analyze the lauric acid PCM melting process in a finned rectangular cavity, keeping both the PCM mass and the total fin area constant, thus changing only the fin aspect ratio. The analysis was conducted through a parametric study of 78 different fin configurations. In order to maintain the thermal capacity, the cavity and fin areas were kept constant while fin dimensions were varied within a preset number of combinations of area fraction and width. The fins tested were combinations of 9 fin aspect ratios (RAf) and 9 fin-to-cavity area fractions (ϕ). A finite-volume numerical CFD method was used to obtain the results. Governing equations were the conservation of mass, momentum and energy while phase change was governed by an enthalpy-porosity model. The mathematical model was validated against reference experimental results and computational meshes were checked with GCI. For all tested cases, with an increase in the fin length and a consequent reduction in RAf, there was a reduction of the total time of the melting process. The RAf, which had shorter melting times, were defined as optimal aspect ratios (RAopt). Thus, each ϕ tested resulted in its own RAopt. For ϕ = 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.1, 0.2 and 0.3, RAopt = 0.013, 0.026, 0.052, 0.078, 0.104, 0.130, 0.260, 0.592 and 0.889, respectively. Future works could contemplate a greater number of fins, with the same total area of this study, other PCM and other temperature differences, for example.