Heat transfer enhancement by changing the wall position of latent heat thermal energy storage units: Continuous and simultaneous charge and discharge

With the depletion of fossil fuels and environmental problems, the utilization of renewable is crucial. Latent heat thermal energy storage (LHTES) technology can effectively alleviate the mismatch between the supply and demand of renewable energy. However, the low thermal conductivity of phase change materials (PCMs) severely limits the operational efficiency of LHTES units. In this study, the thermal performance of the LHTES unit is enhanced by proposing a novel design that changes the positions of the walls of the cubic LHTES unit. A phase change experiment is conducted to verify the accuracy of the numerical model, and the results show good agreement between the numerical simulations and the experiments, confirming the reliability of the numerical model. Considering the continuous and simultaneous charge and discharge processes, a series of key evaluation metrics are proposed to comprehensively evaluate the thermal performance of the LHTES units. The results indicate that wall position significantly affects heat transfer: bottom heating enhances natural convection , while side cooling improves additional thermal conductivity . Additionally, entropy analysis reveals that Model IV, despite achieving the best performance, also exhibits the highest entropy generation , indicating a trade-off between heat transfer efficiency and system irreversibility . • A novel latent heat thermal energy storage unit was proposed. • Continuous and simultaneous charge and discharge processes were comprehensively considered to evaluate LHTES unit. • The relative position of hot and cold walls determined the intensity of natural convection . • Reasonable arrangement of walls effectively improved operational flexibility and efficiency. • The novel design does not occupy space to ensure maximum energy storage.