DRY AIR COOLING AND THE sCO2 BRAYTON CYCLE

Commercially available and cost effective finned tube air coolers are an enabling technology that makes practical dry air cooling for the supercritical carbon dioxide (sCO(2)) Brayton cycle by which heat is directly rejected from CO2 to the air atmospheric heat sink. With dry air cooling, sCO(2) Brayton cycle conditions need to be re-optimized to increase the main compressor inlet temperature and pressure (e.g., 35 degrees C and 8.2 MPa) relative to water cooling to limit the air cooler size to a practical value, and to increase the compressor outlet pressure (e.g., 25 MPa) to maintain a high efficiency. With re optimization, the plant efficiency for the AFR-100 S odium Cooled Fast Reactor Nuclear Power Plant (NPP) is similar to that with once-through water cooling, while the NPP capital cost per unit output electrical power ($/kWe) is roughly estimated to be only 2 % greater. For the AFR-100 application, no unique benefit is identified for the sCO(2) Brayton cycle relative to the superheated steam cycle with respect to the capability to use dry air cooling.