Parametric analysis and optimisation of porous volumetric solar receivers made of open-cell SiC ceramic foam

Abstract

In recent years, research on the usage of porous materials as volumetric thermal receivers in concentrated solar power plants is growing significantly. This interest is due to their capabilities to improve the efficiency of solar radiation conversion into thermal energy. In this work, detailed parametric analysis and optimisation of the thermal and hydrodynamic performance of porous volumetric receivers are performed using a detailed numerical model. The transport and absorption of solar radiation is modelled through a Monte Carlo Ray Tracing algorithm, while the governing equations of fluid flow and heat transfer are solved using a Computational Fluid Dynamics model. The mean temperature of the fluid at the outlet, thermal efficiency and pressure drop across the receiver are investigated through a parametric analysis and optimisation for different values of porosity, pores size and inlet fluid velocity. The receiver of choice should have high thermal efficiency without greatly increasing the pressure drop and not decreasing the mean fluid temperature at the outlet. Results show that these conditions are achieved for receivers with high porosity (0.8 - 0.9) and pores size (4.5 - 3 mm). For a given receiver porosity, there is a pores size value that maximises thermal efficiency, being this value lower for high porosity.