Study of the usability of sinusoidal function heat flux based on enthalpy-porosity technique for PCM-related applications

The present study summarizes a two-dimensional (2D) numerical simulation of a phase change material (PCM) melting/solidification processes in a square cavity. The objectives of this study are to study and compare the effect of the application of different applied thermal boundary conditions such as constant or variable thermal flux during the melting and solidification processes of a PCM. Here, the convective heat transfer is taken into account according to the Boussinesq approximation. The commercial code COMSOL Multiphysics is used, and the "Voller model" based on the enthalpy-porosity technique is applied on a fixed computational grid. Results presented in terms of solid-liquid fraction, flow structure, isotherms, and stored and released thermal energy have shown that the melting time for the applied variable heat flux is reduced compared to that of constant heat applied flux. In addition, it was found that the PCM melting time was shorter than the solidification time. Therefore, the use of variable (sinusoidal) heat flux conditions can be useful in engineering applications such as thermal energy storage applications (PCM life cycle test, solar energy where a variable heat flow is involved due to the change of day).