Heat transfer analysis of a volumetric solar receiver with composite porous structure

Highlights: • A volumetric solar receiver with composite porous structure is numerically studied. • The LTNE model combined with P1 approximation is used to solve temperature field. • Pore parameters in inlet near-wall region significantly affect the thermal behavior. • Using low porosity and small mean cell size shows improved thermal performance. - Abstract: A volumetric solar receiver with composite porous structure is proposed, where a porous foam with different pore parameters from that in the other region of receiver is placed in the inlet near-wall region. Thermal performance of the solar receiver is numerically investigated. The local thermal non-equilibrium model is utilized to represent the energy transport within the porous foam. Radiative transfer in the porous foam due to high temperature combined with the transport of concentrated solar radiation inside the receiver is solved using the P1 approximation. Thermal behavior comparison is made between the receiver with composite porous structure and that with single porous layer. The effects of different pore parameter designs are discussed. The results indicate that there exists a large temperature gradient in the solid phase for a solar receiver with single porous layer. Using low porosity and small mean cell size in the inlet near-wall region for the receiver with composite porous structure can reduce the solid temperature gradient and increase the mean fluid outlet temperature.