Design strategy for inlet conditions of supercritical CO₂ centrifugal compressors

To improve the aerodynamic performance and suppress the condensation in supercritical CO₂ centrifugal compressors, a design strategy is proposed in this paper. The inlet compression factor and density are adopted to study the compressor performance and flow characteristics by solving three-dimensional Reynolds-averaged Navier-Stokes equations with condensable gas. The results indicate that in the range of operating conditions studied, increasing inlet compression factor or density, the condensation area will decrease. However, the pressure ratio will also decrease. By the means of decreasing inlet compression factor and increasing density, the inlet conditions alter from baseline conditions (7.69 MPa, 305.15 K) to optimization conditions (8.40 MPa, 305.54 K). The condensation area decreases by a large margin and the peak efficiency increases from 73.2% to 75.4%, while the pressure ratio remains unchanged. The design strategy provides a new idea for supercritical CO₂ compressors to improve the performance and suppress the condensation at impeller inlet.