Thermal characteristics of grid flat-plate heat receiver in a solar power-tower system

Thermal stress caused by the uneven temperature of the heating surface is a key factor leading to the failure of heat receiver in a solar power-tower system, and other thermal characteristics would also affect the ability of the system. Therefore, the thermal characteristics of a novel flat-plate heat receiver that uses the recirculation grid to form many micro heat pipe cycles are experimentally studied in this paper. The results indicate that the grid flat-plate heat receiver can be successfully started-up within 456 s, the compressed air outlet temperature can exceed 790.4 °C, and the efficiency of the grid flat-plate heat receiver can reach 83.8%, demonstrating the outstanding heat transfer performance of the grid flat-plate heat receiver. Moreover, the heating surface exhibits the excellent isothermal performance (<41.64 °C) with the maximum temperature reduced by approximately 76.04 °C. Flowing “sodium pool” is formed in each micro cycle when the heat receiver is working, generating a positive effect on the isothermal performance and maximum temperature reduction of the heating surface. Additionally, the isothermal performance is influenced by the synthetic effects of heat flux and air mass flow. This work will contribute to the further development of the heat receiver used in a solar power-tower system.