Performance enhancement of latent heat storage via combined multi-tube configuration and a novel circumferential fin

Growing global energy demand and the intermittency of renewable sources highlight the importance of efficient latent heat thermal energy storage (LHTES). Phase change materials (PCMs) offer high energy density but suffer from low thermal conductivity, limiting charging and discharging performance. Conventional enhancement methods, especially radial fins, accelerate melting but obstruct natural convection and complicate fabrication. To address these issues, this study performs a comprehensive numerical analysis of a shell-and-tube LHTES system filled with PCM, considering 23 configurations of single, double, triangular, and quadruple tube arrangements. Each case is examined with finless, radial, multi-circumferential, and a novel shared circumferential fin design. A new performance index, the Phase Change Response Efficiency (PRE), is introduced to evaluate charging and discharging simultaneously against a single-tube finless baseline. Results show that the quadruple tube layout with the single circular fin delivers the best performance, cutting total melting and solidification times by over 92% and achieving a PRE of 8.23%. Conversely, the upper-upward oriented triangular layout with multiple fins performed worst (PRE > 100%) due to suppressed convection. Overall, the shared circumferential fin consistently outperforms conventional designs, offering both superior thermal response and easier manufacturability, making it a promising solution for advancing LHTES in solar and renewable energy applications.