Abstract

To satisfy the needs of space heating and domestic hot water, the use of renewable energies and particularly solar energy stands out for its technical feasibility and competitiveness. However, in order to mitigate the variations on the availability of the resource and fully meet the thermal loads, storage systems are commonly used. In those systems, water is usually used as heat transfer fluid, due to its low cost and thermophysical parameters that facilitate the stratification. Aiming to further this phenomenon, different geometries of inlet diffuser were proposed and assessed through computational simulations of the charging and discharging process. CFD simulations were carried out using ANSYS Fluent, aiming to compare the temperature profiles, and considering the stratification efficiency as a figure of merit. The results of the CFD simulations show that the use of the diffusers and the inlet flow through the upper zone of the tank generate the best stratification efficiencies, reducing unexpected mixing in the storage tank.