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

Abstract

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.