Efficiency enhancement in solar energy storage: Impact of oval inner tube geometries on phase change material units

Abstract

This comprehensive study systematically investigates the melting and solidification processes in phase change material (PCM) units, specifically comparing different inner tube geometries, including horizontal oval, inclined oval (45°), and vertical oval, against the circular inner tube. Through meticulous analysis, the study reveals that the vertical oval inner tube demonstrates superior efficiency, achieving complete melting and solidification in significantly shorter times compared to other geometries. In the melting process, the unit with a circular inner tube completes melting at 7560 s, the horizontal oval and inclined oval units complete at 7500 s, and the vertical oval unit completes at 7260 s. Notably, the reduction in melting time for horizontal oval and inclined oval units is approximately 0.8%, while for vertical oval unit, it is notably greater at 3.96%. Similarly, in the solidification process, the unit with the circular inner tube completes solidification at 17760 s; the horizontal oval completes at 17160 s, the inclined oval unit completes at 16080 s, whereas the vertical oval unit completes at 14400 s. The reduction in solidification time for the horizontal oval and inclined oval is 3.37% and 9.46%, respectively, whereas for the vertical oval, it is notably greater at 18.91%. These findings underscore the profound influence of inner tube design on heat absorption, temperature profiles, and overall PCM unit performance. The substantial reductions in both melting and solidification times, particularly for the unit with a vertical oval inner tube, highlight the critical role of inner tube geometry in optimizing PCM efficiency and responsiveness to thermal changes.