Numerical Modelling of Natural Convection Driven Melting for an Inclined/Finned Rectangular Enclosure

摘要

This paper presents a numerical study aimed at understanding the impact of the mushy zone constant, A_(mush), on simulated phase change heat transfer with varying geometries (inclination angles, and fin additions). This parameter is found in the Carman-Koseny equation, which is used in the modified heat capacity-porosity formulation for modeling phase change; this approach models fluid flow within the mushy region as flow through a porous medium. The melting of dodecanoic acid inside a rectangular thermal storage unit was simulated in COMSOL Multiphysics 4.4 with A_(mush) being varied for each geometry. The predicted numerical melt front positions were directly compared to published experimental results. Results have shown that the influence of A_(mush) on the melting rate of the PCM is reduced with increasing inclination angles of the enclosure; where the melt interface is perpendicular to the direction of gravity. This has been attributed to the reduced velocity magnitudes that appear near the melt interface in such geometries. The addition of the fins showed that near the fin region A_(mush) does not play an important role. However, it was observed that the model over predicts the velocity near the fin in the one fin model, which caused a mismatch between numerical and experimental results.