Buoyancy-driven melting and heat transfer around a horizontal cylinder in square enclosure filled with phase change material

Abstract

This work primarily focuses on designing a cost effective method yielding high rate of heat transfer from a heated object to ensure the faster melting of the phase change material (PCM). A numerical investigation has been performed on the laminar natural convection from a two-dimensional heated circular cylinder confined in a square enclosure filled with a phase change material, namely, the lauric acid. In particular, the coupled momentum and energy equations are solved to delineate the influence of the geometric position of the cylinder within the square enclosure on the melt and heat transfer characteristics of the phase change material. The solid-liquid phase change is formulated using the enthalpy–porosity technique. The detailed velocity and temperature fields are visualized in terms of velocity vectors, isotherm contours, melt fraction contours, melting rate, energy storage and surface averaged Nusselt number. The results reported herein are restricted to the six distinct geometrical positions (i.e., four symmetric and two asymmetric) of the cylinder within the enclosure. The rate of convective heat transport and hence the melt fraction is found to decrease with the increasing distance of the cylinder from the base of the enclosure. In addition, the influence of the mushy zone parameter (Amush) on the melting behaviour has also been explored. The reported numerical results for the melt fraction have been correlated as a function of the melting time and the geometric positions of the heated cylinder. Finally, one can conclude that it is possible to realize an enhanced rate of melting and energy storage simply by adjusting the location of the cylinder under confinement and thus the performance of a thermal energy storage (TES) system can remarkably be improved.