Thermal performance of cascaded latent heat thermal energy storage units constructed based on solid-liquid interface information

A novel approach to constructing cascaded latent heat thermal energy storage units is proposed to enhance the thermal performance of horizontally placed shell-and-tube phase change heat storage systems. This method is based on the solid-liquid interface variation patterns during the solidification and melting processes. It creates interfaces between different phase change materials within the cascaded latent heat thermal energy storage unit to shorten melting time and increase thermal performance by optimizing the unit's internal structure to balance heat transfer rates across all areas. The enthalpy-porosity method was used to numerically study the phase change phenomenon. The inner tube of the units was set as an isothermal boundary, and the outer shell was insulated. Findings from this cascaded latent heat thermal energy storage system demonstrate that, compared to single-latent heat thermal energy storage units, the average heat transfer rates during solidification and melting increased by 27.3% and 36.7%, respectively. The average heat transfer rate during solidification improved by 11.7% compared to traditional concentric circular cascaded latent heat thermal energy storage units. These results indicate that this method can significantly enhance the thermal performance of latent heat thermal energy storage units, providing valuable insights for future structural optimization. • A new method for optimizing the structure of CLHTES units is proposed. • The optimized CLHTES units notably improve the thermal performance of energy storage. • This method can be flexibly extended to optimize the design of other LHTES units.