Performance Predictions for a Super-Critical CO2 Compressor Operating Near the Liquid-Vapor Dome

Abstract A team led by GE Vernova Advanced Research, GE Aerospace Research and Southwest Research Institute (SwRI) designed, built and tested an advanced 4MW compressor operating near the liquid-vapor dome of Carbon Dioxide (CO2) under US Department of Energy (DoE) Solar Technologies Office (SETO) program DE-EE-0007109. The compressor was targeted towards a Concentrated Solar Power (CSP) plant where Super-Critical Carbon Dioxide (sCO2) cycles offer the potential to reduce power block size. The initial learning from the effort centered around the challenges of accurate performance measurements, and a gap in CFD predictive capability in conditions near the dome. An in-depth detailed CFD study was conducted in an attempt to improve upon the initial data-match, considering the impact of leakage flows at smaller impeller sizes, complex inlet and exit scroll geometries and/or choking effects arising from phase change. Additional data was collected in 2023, incorporating some of the recommendation from the initial test learning. In this paper, CFD predictions at inflow conditions near the critical point are compared with the recent measurements. Contributing factors to the mismatch between prediction and experiment are investigated using CFD models that include additional geometric details from the as-tested compressor, compression system steady and unsteady simulations. Future research to further improve CFD predictions is also discussed.