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

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 (RA(f)) and 9 fin to-cavity area fractions (phi). 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 RA(f), there was a reduction of the total time of the melting process. The RA(f), which had shorter melting times, were defined as optimal aspect ratios (RA(opt)). Thus, each phi tested resulted in its own RA(opt). For phi = 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.1, 0.2 and 0.3, RA(opt) = 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.