Numerical investigation on heat transfer characteristics during melting of lauric acid in a slender rectangular cavity with flow boundary condition

This paper is devoted to numerically investigating the melting mechanism and thermal behavior of phase change material (PCM) in a slender rectangular cavity with heat transfer fluid (HTF) flowing over one side and the other sides thermally insulated. Hot air and lauric acid are selected as the HTF and PCM in current work, respectively. A parametric study is performed by varying the velocity of the HTF in a range of 2, 3, 4, 5 m/s and temperature of 70, 75, 80 degrees C. Dimensionless analysis for the melting process is conducted by introducing a group of dimensionless numbers. The results show that despite the declining heat transfer rate from bottom up along the wall, the melting rate is relatively large in upper part of the cavity due to the dominance of natural convection. Different from the tube flow situation, increasing the Reynolds number or the Stefan number both have significant positive effects on the melting process, and the variations of relevant parameters are described quantitatively. Furthermore, an analogy analysis of dimension is carried out by dividing the whole process into three stages reasonably, based on which a series of new correlations are developed to predict the instantaneous melting fraction and heat transfer intensity during the melting process. (C) 2020 Elsevier Ltd. All rights reserved.