Effect of heat transfer structures on thermoeconomic performance of solid thermal storage

The performance of a regenerative solid TES (thermal energy storage) system with enhancement heat transfer structures is analyzed. Thermal energy is transferred from a hot heat transfer fluid to the storage unit core elements during charge, and from the core elements to the cold heat transfer fluid during discharge. Herein, concrete as the solid storage material, nitrate solar salt as the heat transfer fluid, and aluminum plates as the heat transfer structures are considered. The discharge process from uniform initial temperature is studied with different configurations (pure concrete and concrete enhanced by transfer structures), operation strategies (laminar versus turbulent flow regimes), and dimensions. The results show a significant decrease in the cost of the TES system when heat transfer structures are added, as well as higher discharge efficiency and lower discharge time period. The amount of solar salt needed for this configuration is also decreased by the use of the heat transfer structures and is five time less than that of a two-tank system.