Investigation on enhancing thermal energy storage performance of a phase change material in triplex tube heat exchangers with novel fins configuration

Phase change materials (PCMs), which are used in this study as thermal energy storage (TES) media, play a vital role in TES systems by enhancing heat absorption. The aim of this research is to enhance the thermal performance of a triplex tube heat exchanger (TTHXs) by investigating the effect of novel fin configurations on PCM melting behavior. This analysis investigates the triplex tube heat exchanger design for improved PCM-based TES performance through novel fin configurations. Four design cases are investigated. Case 01 serves as the baseline, featuring longitudinal fins with the highest thickness. Case 02 introduces small arcs at the fin bottom and tips while reducing fin thickness. Case 03 extends the arc length and further reduces fin thickness, promoting better heat penetration. Case 04 optimizes heat transfer by elongating the fins, incorporating large semi-circular arcs, and minimizing thickness. A comprehensive analysis is conducted; examining thermal and liquid fraction contours, melting time, heat flux variations, energy storage density, and specific energy storage rate. The Finite volume method was used to compute the design model results in ANYS-Fluent 2024R1. The outcomes designate a significant reduction in melting time, with Case 02 achieving a 3.57 % decrease (10,240 s), Case 03 a 13.37 % decrease (9200 s), and Case 04 a 71.75 % decrease (3000 s) compared to Case 01 (10,620 s). Case 04 also exhibits the highest energy storage density (290.6 kJ/kg) compared to Case 01 (283.22 kJ/kg). Furthermore, the specific energy storage rate in Case 04 reaches 0.095, significantly surpassing Case 01 (0.026). The novelty of this work lies in the use of semi-circular arc-shaped fins, which have not been previously analyzed in this configuration. These results highlight the efficiency of fin geometry modifications in optimizing thermal energy storage performance, making a valuable contribution to the design of compact and high-performance TES systems for renewable energy applications.