High Flux Microscale Solar Thermal Receiver for Supercritical Carbon Dioxide Cycles

Characterization of a microchannel solar thermal receiver for a supercritical carbon dioxide (sCO₂) is presented. The receiver design is based on conjugate computational fluid dynamics and heat transfer simulations as well as thermo-mechanical stress analysis. Two receivers are fabricated and experimentally characterized — a parallel microchannel design and a microscale pin fin array design. Lab-scale experiments have been used to demonstrate the receiver integrity at the design pressure of 125 bar at 750°C surface temperature. A concentrated solar simulator was designed and assembled to characterize the thermal performance of the lab scale receiver test articles. Results indicate that, for a fixed exit fluid temperature of 650°C, increase in incident heat flux results in an increase in receiver and thermal efficiency. At a fixed heat flux, efficiency decreased with an increase in receiver surface temperature. The ability to absorb flux of up to 100 W/cm² at thermal efficiency in excess of 90 percent and exit fluid temperature of 650°C using the microchannel receiver is demonstrated. Pressure drop for the pin array at the maximum flow rate for heat transfer experiments is less than 0.64 percent of line pressure.