Design and performance analysis of compressor and turbine in supercritical CO2 power cycle based on system-component coupled optimization

•A novel system-component coupled optimization for S-CO2 power cycle is implemented.•Th ree-dimensional modeling and CFD simulation of key components are conducted.•The unsteady CFD simulation of S-CO2 radial inflow turbine is carried out. Supercritical CO2 (S-CO2) power cycle has been widely applied in the field of nuclear energy, solar energy and waste heat recovery because of its high efficiency, compact structure and suitability for various heat sources. Compressor and turbine are the key components of the S-CO2 power cycle which significantly affect the cycle performance. Therefore, it is of great necessity to carry out the cycle optimization design and key components performance analysis. In this paper, a novel system-component coupled optimization method of S-CO2 power cycle, which fully considers the performance of compressor, turbine and the S-CO2 power cycle performance, is proposed for improving the accuracy of optimization design results and guarantee a good match between the optimal thermodynamic parameters of S-CO2 power cycle and the performance of key components. The system-component coupled optimization method is implemented by genetic algorithm based on the one-dimensional model of the S-CO2 centrifugal compressor and S-CO2 radial inflow turbine to obtain the accurate optimal cycle thermodynamic parameters and the key components design parameters. Using the obtained design parameters of S-CO2 centrifugal compressor and S-CO2 radial inflow turbine, three-dimensional modeling and CFD simulation of S-CO2 centrifugal compressor and S-CO2 radial inflow turbine are implemented. The results show that using system-component coupled optimization method can evaluate the cycle performance more reasonably and accurately. The optimized cycle thermal efficiency and the cycle net power output are 19.47% and 987.3 kW, respectively. The optimized turbine efficiency and compressor efficiency are 82.57% and 81.25%, respectively. Unsteady CFD simulation results show that the turbine total-to-total efficiency obtained by steady computation is 0.83% higher than the unsteady time-averaged value obtained by unsteady computation. The relative errors of one-dimensional design results and three-dimensional simulation results for both compressor and turbine are within 5%.