Thermal behaviors of sensible high temperature thermal energy storages with porous media in air concentrated solar systems

In this paper a sensible thermal storage component of a high temperature solar energy system is numerically simulated. The difference is defined by the different type of porous medium employed in the storage. Three different porous media are considered: spheres, square cells, and foams. In all cases a ceramic material is considered. In the formulation of the model it is assumed that the system geometry is cylindrical, the fluid and the solid thermophysical properties are temperature independents, the radiation heat transfer mechanism is neglected. The commercial CFD Fluent code is used to solve the governing equations in transient regime and in local thermal non-equilibrium (LTNE). Numerical simulations are carried out at different mass flow rates of the heat-carrying fluid. The results show the effects of the porosity, the working fluid mass flow rate and the type of porous medium on the stored thermal energy and on the storage time and efficiency.