Dynamic Characteristics of Phase Change Material in a Square Cavity under Various Heating Modes

Phase change material (PCM) is particularly advantageous in developing low-carbon buildings. However, its melting efficiency is severely determined by the dynamics of the molten phase, which is greatly associated with the applied heating orientation. This work aims to describe the dynamic character in the melting process of paraffin under different heating modes. A total of four heating modes are considered for the paraffin enclosed in a square cavity, including side heating, top heating, bottom heating, and around heating. The around heating can be regarded as the combination of the first three heating modes along a single wall. A comparative study of numerical and experimental results of temperature is firstly performed for the side heating case to verify the computational model, which is then extended to study the dynamic state during the melting process of paraffin. The evolutions of the solid/liquid interface and the internal flow field show that the bottom heating can maximally activate the involvement of natural convection of the liquid paraffin and thus has the highest efficiency than the side and top heating. The contribution rate of the bottom heating is about 1.55 times over that of the top heating. This observation is useful to identify the contribution of each heating mode to the heat transfer in the paraffin and guide its practical application.