Numerical study on melting and heat transfer characteristics of vertical cylindrical PCM with a focus on the solid-liquid interface heat transfer rate

Abstract

In this paper, a two-dimensional symmetric transient numerical heat transfer model for the melting of PCM was established based on a vertical cylindrical energy storage device filled with lauric acid. Based on the enthalpy method, the phase transition process of a vertically placed cylindrical PCM container was numerically solved, with constant side/all surface wall temperature. A new evaluation index, namely the solid-liquid interface heat transfer rate, was established to further clarify the melting and heat transfer characteristics of cylindrical containers under different structural parameters and boundary conditions. The results showed that when the aspect ratio changed from 1 to 2, the melting and heat transfer effects of side surface heating changed most obviously, the average solid-liquid interface heat transfer rate qave increased by 8.04 %, and the total melting time was shorten by 8.52 %; the melting and heat transfer effects of all surfaces heating had the weakest change, with only a 5.20 % decrease in qave and a 5.48 % increase in total melting time. This study reveals the essence of characteristic structure optimization of cylindrical energy storage devices under different thermal boundary conditions, which improves energy storage efficiency.