Effects of novel fins on PCM melting/solidification in triplex tube heat exchangers

This study compares different triplex tube heat exchanger (TTHE) designs using PCM RT82 as a latent heat storage (LHS) unit. Twelve scenarios were analyzed based on three fin parameters: 1. Shape, 2. Arrangement, and 3. Count. The efficiency of phase change is influenced not only by the geometric shape and number of fins, but also by their arrangement and attachment to the side walls. Therefore, the purpose of this study was to identify the optimal fin design and arrangement that would enhance the LHS unit performance through a comprehensive analysis of multiple factors simultaneously. Anchor-shaped fins (ASFs) and tree-shaped fins (TSFs) were evaluated alongside traditional radial fins (RFs), with both unidirectional, inner -> outer, and bidirectional, inner <leftwards harpoon over rightwards harpoon> outer, arrangements. In the bidirectional arrangement, fins are alternately connected to the inner and outer walls. TTHEs were tested with 6 or 8 fins, and performance was analyzed during both the charging and discharging processes. The results show that the bidirectional inner <leftwards harpoon over rightwards harpoon> outer arrangement improves heat transfer within the LHS unit by reducing phase-change-resistant masses between fin branches. Bidirectional TSFs reduced melting/solidification time by 11.45 %/12.45 % compared to unidirectional TSFs. Additionally, the 8-fin bidirectional TSF design achieved the best performance, reducing the melting/solidification time by 5.37 %/11.75 % compared to ASFs.