Heat transfer analysis of a volumetric solar receiver by coupling the solar radiation transport and internal heat transfer

Volumetric receivers have become a promising technology for the solar thermal conversion. The absorption of concentrated solar radiation and the heat transfer to the working fluid are the two dominant processes. To effectively investigate the thermal performance of receiver, a numerical model coupling the solar radiation transport and the internal heat transfer is presented. Solar radiation transport from the dish concentrator to the interior of receiver is simulated with the Monte Carlo ray tracing method. Combining the distribution of absorbed solar energy in the receiver, the local thermal non-equilibrium model with P1 approximation is used to solve the internal heat transfer. Two other treatment approaches for the concentrated solar radiation are compared. One considers the solar radiation on the front surface of receiver as thermal boundary condition (TBC) and the other as a collimated incident radiation (CIR) beam. The results show that the porosity and mean cell size have a great effect on the distribution of absorbed solar radiation. Compared with the coupling approach, the TBC approach overestimates the solid temperature near the front surface with a deviation up to 76.4%, while the CIR approach provides acceptable temperature field with a deviation less than 3.4%. In addition, the fluid and solid temperatures both decrease as the slope error of concentrator increases.