PRELIMINARY STUDY ON OPTIMIZATION OF DRY AIR-COOLED SUPERCRITICAL CO2 CYCLE WITH ENVIRONMENT TEMPERATURE FOR SMALL MODULAR REACTOR APPLICATION

Abstract

An air-cooled supercritical CO2 Brayton cycle (SCO2) has been considered as an advanced power conversion system suitable for small modular reactors (SMR) for its advantages of compact system components, high efficiency, and air-cooling feasibility. However, a satisfactory thermodynamic efficiency of the SCO2 cycle only can be achieved by integrated system optimization. In this study, we optimized system parameters to find the maximum thermodynamic efficiency of the air-cooled SCO2 cycle for the ambient temperature range of 20°C to 45°C. A natural draft dry cooling tower (NDDCT) was selected for the air-cooling system of this preliminary optimization study. A validated computational code was developed to evaluate aircooled SCO2 cycle performance for 450MWt SMR cases. The turbine inlet temperatures were given of 310°C, 550°C, and 650°C for the cycle. They represented pressurized water reactors and advanced reactor types under development, respectively. The optimized efficiency of the cycle coupled with the 100m NDDCT were 29.61%, 46.06%, and 49.91%, respectively. This efficiency decreased linearly to 23.39%, 40.77%, and 45.11% as the ambient temperature increased to 45°C. Optimized design parameters including the recuperators were presented for each case.