Design of a composite receiver for solar-driven supercritical CO2 Brayton cycle

In recent years, a great amount of attention has been focused on the study of combining the concentrating solar power (CSP) and supercritical CO2 (s-CO2) Brayton cycle, for it is a very promising way for clean energy utilization in the future. But its development is somewhat hindered by the lack of efficient solar receiver for s-CO2 heating. The surface absorption of solar energy in current miniature tube receiver is becoming the main obstacle to further improve solar-thermal efficiency. In this work, efforts have been made to design a composite solar receiver by elaborating the advantages of high solar absorption of a volumetric receiver and the ability of withstanding high pressure of a miniature surface receiver. Meanwhile, the circulating air flow is used for regulating temperature of the whole absorber. This proposed receiver is constructed by porous media blocks and plate fin tubes layer by layer like a sandwich. Thus, the proposed solar receiver possesses the ability to accommodate high temperature, pressure, and solar flux. The calculated solar-thermal efficiency amounts to 93.7%, which is mainly attributed to the highly efficient capture of solar energy via volumetric absorption and reasonable temperature regulation by circulating airflow. This proposed receiver is expected to achieve high-efficiency heating of s-CO2 and greatly boost the development of CSP and s-CO2 Brayton cycle.