Discharging shape influence on the performance of a latent heat thermal energy storage

Due to the mismatching between the renewable energy source and the energy demand, the energy storage devices have attracted the attention of the scientific community in order to maximize their performance. Several technologies have been developed and applied in laboratory scale and prototypes in the last decades. The energy storage devices can be mainly defined according to the average working temperature, the storage material, and the geometrical configuration. This work is focused on the 2D axisymmetric finite volume multiphase numerical simulations of the fluid flow and heat transfer within a shell-and-tube type latent heat thermal energy storage (LHTES). The effect of the geometrical parameters on the thermal performance of such systems is investigated. The influence of the LHTES shape is highlighted keeping constant the heat exchange area, the total storable heat and the heated surface temperature. Detailed description of the liquid fraction and temperature distribution during the solidification phase are reported. The solidification phase appears strongly influenced by the geometry. The geometries have been chosen according to fixed volume and heat exchange area condition. The ratio between the external and the internal radius (r_e/r_i) has been changed and its effect on the thermal performance of the thermal storage device is considered. Thus, according to the application requirement, particular care should be taken in the design of the shape of the LHTES device.