Design and optimization of a bionic-lotus root inspired shell-and-tube latent heat thermal energy storage unit

Thermal energy storage (TES) is crucial in the efficient utilization and stable supply of renewable energy. This study aims to enhance the performance of shell-and-tube latent heat thermal energy storage (LHTES) units, particularly addressing the issue of the significant melting dead zones at the bottom, which are responsible for the long charging time. This paper proposed a new heat transfer enhancement technique inspired by the air channel distribution inside the root of the lotus. Numerical simulations are used to explore its melting behavior and heat storage performance, and a comparison is made with conventional shell-and-tube TES units. The results indicate that compared to the single-tube type, the bionic-lotus root type reduced the total melting time by 89.1 %, increased the average temperature by 13.2 °C, and enhanced the average effective power density by 7.6 times. Subsequently, multi-objective optimization was conducted based on response surface methodology, and an industrial standard type was constructed according to existing pipeline products to meet the manufacturing standards for mass production. The melting time was further decreased by 5.8 %, and the average effective power density increased by 6.6 %. The results of this study provide a promising and prospective solution for enhancing shell-and-tube LHTES units, with the potential to increase the efficiency, reduce the footprint and manufacturing costs of energy systems equipped with TES.