Thermal energy storage using desert sand : a numerical study of the thermofluidic performances

Abstract

The Thermal Energy Storage (TES) enhances the availability of renewable energy plants. It reduces the mismatch between the production and the demand of the electric energy. However, the high cost of the TES leads to a high overall cost of the produced electric kWh. In the case of solar power plants built in Saharan regions, the use of sand as the storing medium in the TES is a priori a suitable technique that can solve this problem. In fact, the sand presents good physical and chemical properties and it is locally available with a very low cost. In this paper, a numerical study has been conducted to assess the thermal and fluidic performances of a fixed bed and of a fluidized bed by using sand as storing medium. The heat is transferred to, and from, the sand by air. 2D and 3D simulations are conducted. The temperature profiles of the bed are examined as well as the storing rates. Parametric studies with the air speed and the height of the bed were considered. The results gained in this paper indicate that it is very viable and promising to integrate sand as storing media in the solar thermal applications especially where this material is plentiful.