Exergy analysis and novel topological optimization of fin structures in latent heat thermal energy storage system: Experimental study

This study presents a novel approach for optimizing fin structures in a latent heat thermal energy storage (LHTES) system to enhance the thermal performance of phase change materials (PCM). The methodology combines topology optimization and exergy analysis alongside comprehensive experimental validation and computational fluid dynamics (CFD) simulations. The CFD model achieved robust validation, with a minimal relative deviation of only 4 % compared to experimental data. However, exergetic analysis revealed significant variations in efficiency (peak of 75 %) and entropy generation (peak of 180 W) during the PCM's phase change process. These losses were primarily attributed to thermal irreversibilities, as indicated by the Bejan number. Besides, experiments further showed that increasing the flow rate from 100 kg/h to 300 kg/h led to greater exergy destruction, from 145 W to 180 W, due to higher pressure drops and system design limitations. In this regard, to mitigate these performance-limiting factors, an innovative topological optimization methodology was developed, using exergy efficiency as an objective function to determine the optimal fin distribution, considering both the quantity and quality of energy. The results demonstrate that the incorporation of fins leads to enhanced heat transfer and reduced entropy generation, resulting in a 14 % improvement in exergy efficiency compared to the baseline configuration. Furthermore, the topologically optimized fin (TOF) design achieved even greater performance enhancements, including improved temperature uniformity, faster solidification rates, and a remarkable 88-min reduction in charging time, alongside a 35 % increase in exergy efficiency compared to the initial configuration.