Numerical analysis of melting/solidification mechanism in a triple-pipe latent heat energy storage unit in the presence of a zig-zag shaped middle plate

This study evaluates the thermal performance of a triple-pipe latent heat energy storage system using numerical simulations, with a focus on the effects of a zig-zag shaped middle plate. It assesses the impact of various geometric configurations, phase change material (PCM) types, and heat transfer fluid (HTF) characteristics on the melting and solidification cycles. The zig-zag geometry significantly affects heat transfer rates, enhancing the efficiency of the phase change mechanism. RT-35 emerged as the most effective PCM, demonstrating its superior thermal properties and highlighting the importance of PCM selection. Additionally, optimal HTF parameters, such as higher inlet temperatures and Reynolds numbers, improved the melting process, while lower temperatures accelerated solidification. Specifically, Case 5 with a zig-zag amplitude of 7.5 mm not only excelled in melting efficiency by reducing melting time by 20.54 % and increasing heat storage to 92.48 W but also achieved the best solidification performance alongside configuration A5, with the shortest time of 4949 s and the highest heat release rate of 77.18 W. A Reynolds number of 1500 further improved both melting and solidification processes. Utilizing RT-35 as the PCM maximized the speed of phase transition and thermal storage efficiency. These findings illustrate the crucial interplay between geometric design, material properties, and operational parameters, enhancing the performance of latent heat energy storage systems. This analysis offers valuable insights for designing and operating more efficient thermal energy storage solutions, advancing renewable energy storage technologies to address intermittency and support sustainable energy transitions.