A study of real-gas effect on SCO2 compressor performance using similitude method

The drastic property changes of supercritical CO2 (SCO2) make the performance of SCO2 compressors different from that of conventional compressors. This study deals with the real-gas effect on the SCO2 compressor performance by theoretical analysis and numerical validation. A set of similitude parameters are firstly deduced by dimensional analysis. Then keeping these parameters unchanged, the performance variation of a SCO2 compressor is analyzed when the inlet flow condition changes in a certain temperature and pressure range. Results show that the proposed similitude method could accurately reflect the variation trend of SCO2 compressor performance under different inflow conditions. The real-gas effect enables the compressor to obtain higher pressure ratio with lower temperature rise. It is recommended that the inlet temperature of SCO2 compressor should be as close as possible to the critical temperature and the pressure should be about 150 kPa higher than the corresponding pseudo-critical pressure at the same temperature.