Thermal optimization of PCM-based storage systems using L-shaped fins: A numerical and RSM-based approach

This study comprehensively investigates the impact of incorporating L-shaped longitudinal fins into a rectangular thermal energy storage (TES) enclosure filled with phase change material (PCM), aiming to enhance melting performance and energy delivery efficiency. A three-dimensional numerical model was developed using the finite volume method coupled with the enthalpy-porosity approach to simulate the phase change process accurately. Four configurations were analyzed, varying from no fins to the inclusion of one, two, and three fins. Case 04, which includes three fins, demonstrated the highest thermal responsiveness, achieving complete melting in just 1480 s a reduction of approximately 86.6 % compared to the baseline Case 01 (11,040 s). Although Case 01 stored the highest total energy (191.5 kJ), this was primarily due to its prolonged melting duration and slightly larger PCM volume. In contrast, the finned cases (particularly Case 04) exhibited slightly lower TES capacities (184.42 kJ) but offered faster energy delivery and superior thermal performance. The novelty of this work lies in systematically optimizing the number and geometry of longitudinal fins within a rectangular PCM enclosure, which has not been previously explored in such detail. The Response Surface Methodology (RSM) optimization validated the significance of the numerical model, with strong R² values confirming reliability. Optimization plots further indicated that increasing the fin number and optimizing fin thickness effectively reduced melting time and enhanced mean power output. The mean power (P_m) analysis reinforced these findings, with three-fin configurations achieving up to 0.12488 kW, nearly double the output of single-fin designs. However, a trade-off was observed between rapid melting and marginal TES capacity loss due to reduced PCM volume. Overall, the study confirms that careful design and optimization of fin geometry can significantly improve PCM-based TES systems, offering faster thermal response and enhanced energy delivery with minimal compromise on storage capacity.