Investigation of thermal energy storage systems in concentrated solar power

Abstract

This study presents computational fluid dynamics (CFD) modelling results obtained for the first cycle on a sensible thermal energy storage system based on rocks and pebbles freely poured into a mild steel tank. This study is primarily focused on proposing a plan to find an optimized particle size for the packed bed storage using various heat transfer fluids namely water, therminol-vp1, and air. The computational domain consists of an axisymmetric tank of cylindrical shape filled with a porous bed coupled with the wall. The governing equations have been solved for incompressible turbulent flow and fully developed forced convection, based on the two-phase transient model equation (SSTKW) to calculate the temperature of the fluid and solid phases. The porosity has been considered as 0.28 for the packed bed while the thermodynamic properties of both phases are temperature-dependent. The influence of the thermal dispersion within the porous bed, as well as the effective conductivity between the beads, were considered. The heat transfer coefficient was calculated according to the correlation for forced convection within porous media. Experimental temperature profile at the inlet of the bed is applied as a boundary condition in the simulation. Simulation results showed a good agreement with experimental data.