Numerical investigation on the melting delay of PCM top heated with a constant heat flux

Abstract

When heated with a constant power, melting delay occurs at the initial stage of the phase change material (PCM) melting process. This phenomenon is particularly pronounced in enclosures equipped with fins, where the delay prolongs the overall melting time. In order to quantify the fin effect on the melting delay and to explore methods for reducing its duration, a numerical work was conducted to simulate the melting process of PCM under a top heated condition. By varying the quantity and the length of the fins, a dimensionless equation was proposed to elucidate the relationship between fin configuration and the duration of the melting delay. Its predictive accuracy for the melting delay was found to be within an error of 5 %. After that, innovative designs were proposed by relocating the fins from the heating surface to the base of the container. This rearrangement effectively mitigated the melting delay and was accompanied with higher heating temperature. The best performance was achieved by the fin design of non-attachment arrangement, and this design led to a reduction in the overall melting duration by 8.2 %. Moreover, the effectiveness of the non-attachment arrangement was further enhanced by increasing the number and decreasing the length of fins. The findings in this study will provide new ideas for the fin design to enhance the rate of latent heat thermal energy storage operating under a constant heat flux.