Thermal performance evaluation of a cavity receiver based on particle's radiation properties during the day time

A simulation method consisting of Monte Carlo Ray-Trace and Finite volume coupled model is proposed in the present work for simulation of complex photo-thermal conversion in the particle entrapped cavity receiver. The solar heat flux distribution in the cavity receiver was simulated by using the Monte Carlo ray tracing, while the convection-radiation-conduction process taking place in the cavity receiver was simulated by the Finite Volume Method. Solar heat flux was introduced as a source term in the energy equation for the Finite Volume Method part, and correlations for flow boiling heat transfer were chosen to calculate the surface temperature of the boiling tubes. Based on the simulation model, the thermal performance of the receiver, the temperature distribution and the mean square deviation of temperature at the outer surface of the boiling tubes were analyzed at varying albedo ω, diameter D and time (8:00–16:00). It was revealed that the temperature distribution on the outer surface of the boiling tubes can be uniformed by entrapping carbon particle sin the receiver. The results indicate that the collision between photon and carbon particles resulted in scattering and absorbing, with a tendency to decrease the maximum heat flux and temperature gradient at the surface of tubes. Although the thermal efficiency of the receiver decreases by 4.5%, the maximum temperature was reduced from 665 K to 630 K and the mean square deviation of temperature on the outer surface of backpanel was reduced from about 43 K to 26 K at noon. The results are useful for choosing suitable parameters for entrapped particles in cavity receivers to improve efficiency and operational safety.