High-Temperature Receiver Designs for Supercritical CO₂ Closed-Loop Brayton Cycles

High-temperature receiver designs for solar powered supercritical CO₂ Brayton cycles that can produce ∼1 MW of electricity are being investigated. Advantages of a supercritical CO₂ closed-loop Brayton cycle with recuperation include high efficiency (∼50%) and a small footprint relative to equivalent systems employing steam Rankine power cycles. Heating for the supercritical CO₂ system occurs in a high-temperature solar receiver that can produce temperatures of at least 700 °C. Depending on whether the CO₂ is heated directly or indirectly, the receiver may need to withstand pressures up to 20 MPa (200 bar). This paper reviews several high-temperature receiver designs that have been investigated as part of the SERIIUS program. Designs for direct heating of CO₂ include volumetric receivers and tubular receivers, while designs for indirect heating include volumetric air receivers, molten-salt and liquid-metal tubular receivers, and falling particle receivers. Indirect receiver designs also allow storage of thermal energy for dispatchable electricity generation. Advantages and disadvantages of alternative designs are presented. Current results show that the most viable options include tubular receiver designs for direct and indirect heating of CO₂ and falling particle receiver designs for indirect heating and storage.