Investigation of flow losses and characteristics in volute and collector of sCO2 centrifugal compressors for advanced brayton cycles

The sCO2 Brayton cycle is one of the most promising power systems used to replace conventional Rankine power systems for power generation. Although sCO2 Brayton cycles were extensively investigated in previous research, the sCO2 centrifugal compressors' performance and flow losses have not been studied comprehensively. In this paper, it was found that the exhaust chamber could significantly influence the performance of the whole sCO2 compressor, while flow characteristics and losses in the chamber remained poorly understood due to the complex structure and flow phenomenon in previous studies. Based on the presented sCO2 centrifugal compressor, flow losses in the collector and volute were compared by the increment of the compressor's efficiency and the distribution of entropy production. Results of the comparison showed that the volute could improve the isentropic efficiency of the sCO2 centrifugal compressor by up to 37.84%; the average flow losses in the volute could be reduced by 24.02%; the internal flow in the volute is more uniform and has low energy dissipation, while vortices with high intensity and significant entropy production zones could be found in the collector. This study could provide theoretical guides for designing efficient discharge chambers for sCO2 centrifugal compressors.