Influence of the storage orientation and shell shape on the melting dynamics of shell and tube-type cascade latent heat storage

Latent heat storage is one of the cost-competitive storage solutions for various temperature applications (paraffin having a melting temperature of -30 & DEG;C used for ultra-low temperature applications (cold storage) to the molten salts having a melting temperature of 996 & DEG;C used for very high-temperature application (power generation)). In this work, an enthalpy porosity method-based approach is being implemented for the comparative assessment of various storage configurations such as 1-stage NaNO3 storage, 1-stage NaNO2 storage, and their 2-stage cascaded storage configurations. All the tested storages are designed for the latent energy accumulation capacity of 1 MJ. The existing research works on the performance enhancement of latent heat storage by changing the orientation of the storage system have highlighted contradictory observations. Efforts are made to underline the impact of the various geometric orientations and shell shapes on the melting behavior of the cascade latent heat storage. It is concluded that the horizontal cylindrical cascade storage completes the charging in 39.04 %, 15.78 %, 24.70 %, and 5.9 % less charging time than the other storage configurations, i.e., 1-stage NaNO3 storage, 1-stage NaNO2 storage, vertical frustum cascade storage, and vertical cylindrical cascade storage, respectively. In vertical cascade storages, the frustum shell increases the energy accumulation cycle time by 25 % as compared to the cylindrical shell. Furthermore, it is observed that horizontal cylindrical cascade storage takes 13.33 % less time to achieve the 50 % of the charging as compared to the vertical cylindrical cascade storage, but this difference reduces to 5.9 % for achieving 100 % of the charging state, which makes it more suited for part load charging conditions.