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Abstract

The objective of this paper is to study the solidification problem of the phase change materials (PCM) in a thick-walled cylindrical container. Through varying each controlling parameter such as the thermophysical properties of wall (mold), wall thickness, aspect ratio of the container, initial temperature of PCM and the external cooling conditions, etc., the effect of each parameter on the solidification process is shown clearly. By knowing how a thick wall interacts with such a phase change phenomenon, it is therefore possible to well control the solidification process and also to improve the solid structure formed. In this study, convective boundary conditions are imposed on the outer and bottom boundaries for simulating real ambient cooling conditions. The top surface is kept insulated. The mathematical model of this study is based on the enthalpy formulation. An alternating-direction-implicit (ADI) scheme is employed to solve the pertinet governing equations along with the boundary conditions. Due to the fact that the PCM thermal properties are different from the thermal properties of the wall, the well-known harmonic mean method is used to resolve the discontinuity of the conductivity across the interface. It is demonstrated in this study that the effects of the thermal properties of the wall and the external cooling conditions on the solidification process are quite significant. Furthermore, it is found that the controlling parameters which include the wall thickness, container aspect ratio and the initial temperature for PCM have a direct influence on the solidification rate. The results extracted from this investigation can be applied for many similar solidification problems.

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