Heat transfer and fluid flow in a PCM-filled enclosure: Effect of heated wall configuration

Abstract

A detailed numerical investigation was conducted to scrutinize the impact of heated wall configurations, serving as a primary heat source, on the melting process of phase change materials (PCM) within a rectangular cavity. The study explored various configurations, including square, rectangular, trapezoidal, and curvy, to understand their influence on the liquid fraction, melting time, and stored energy. Through employing the enthalpy-porosity method for the phase change, the analysis revealed that wall geometry significantly affects the melting process, where formation of local enclosed regions acting as heat sources enhance both conduction and convection heat transfer mechanisms. The investigation showed that the curvy wall configuration, by facilitating more effective free convection due to its smooth and continuous surface, markedly improves the melting process. This configuration minimizes flow separation and promotes uniform fluid motion, thereby enhancing convective heat transfer efficiency, particularly in the latter melting stages. The results underscore the superiority of the curvy configuration, with a 57.6 % decrease in melting time and a 16.3 % increase in energy storage capacity compared to the baseline case. These findings highlight the critical role of heated wall geometry in advancing the efficiency of PCM-based energy storage solutions.