Optimization design of CSP particle receiver based on multi scale modeling: Comprehensive numerical and experimental study of photothermal performance

The particle receiver using solid particles as the heat transfer medium is considered the most critical energy conversion component in supercritical carbon dioxide solar thermal power generation systems, with its performance directly affects the efficiency of the system. Firstly, this study used Monte Carlo ray tracing method to establish a three-dimensional radiation convection coupling model, successfully predicting particle temperature dynamics, and revealing the variation of heat transfer efficiency with direct normal irradiance. Secondly, based on the coupled simulation of discrete element method and computational fluid dynamics, it was found that there is a significant low-speed region near the wall. The research results show that the direct normal irradiance >600W/m2, the heat transfer efficiency at 68%, and the optimal flow velocity range was determined through response surface optimization, which can improve the system efficiency by 28%. Finally, in order to verify the accuracy of the model, the outlet temperature of the particles was validated through a single tube free fall experiment. The results showed that the particle outlet temperature significantly increased with the decrease of flow rate, and the max error is 2.52 °C. These findings provide valuable theoretical guidance for the optimization design of tower power stations.