Synergistic enhancement of triplex-tube thermal storage performance using PCM radial cascade and fins

Ten 3D models are created to examine the impacts of PCM radial cascade and adding fins to improve the heat storage capacity of horizontal triplex-tube storage systems. The thermal storage performance is assessed by calculating key indicators such as heat storage time, heat storage capacity, liquid fraction, average melting enhancement ratio during the thermal storage process. In comparison to the single-PCM triplex-tube (Case 0), the results show that the PCM radial cascaded triple tube structure (Case 1) has respectively increased the stored energy, heat storage rate by 19.3%, 19.4%, and shortens complete melting time by 22.1% lower full melting time. In addition, for finned inner tube and finned outer tube configurations, Case 2 (symmetric finned inner tube and PCM cascade) significantly reduces the charging time, while Case 5 (asymmetric finned outer tube with PCM cascade) effectively accelerates the melting process of the bottom of outer tube. Moreover, compared to Case 1, Case 6–9, increase melting enhancement ratios more than 54%, 35%, 53%, and 51%, respectively. It is observed that Case 6 has the highest thermal storage efficiency. This study offers important references for enhancing thermal storage performance in triplex-tube storage systems used in industry.