Development of one-dimensional model for initial design and evaluation of oil-free Co2 turbo-compressor

A 1-dimenional tool for preliminary design and performance prediction of oil-free CO2 compressor is presented. The model describes high speed centrifugal compressor in a hermetic configuration supported on foil gas bearings. To give possibly comprehensive overview of the technology, a wide range of loss mechanisms is considered. The model predicts aerodynamic performance of the compressor as well as losses related to the windage of rotor and bearings and due to the internal cooling. Numerical investigation of different compressor stages was used to validate aerodynamic predictions of the 1D model. Maximal prediction discrepancy amounted 2% for efficiency and 5% for pressure ratio. The prediction of the total compressor efficiency was compared with test data from a 50 kW compressor published Sandia Laboratories. The predicted peak compressor efficiencies are between 66 and 67.5% while experimentally measured values are within 65–70% region.