Scroll Carbon Dioxide Refrigerant Expander for Energy Recovery

The analysis and design study of the Phase 1 work shows that a proposed scroll carbon dioxide expander for refrigerant energy recovery in transcritical carbon dioxide cooling systems will be viable. The analysis also shows that the expander will improve efficiency of a carbon dioxide cooling system by more than 15%. A proof of concept prototype will be designed, fabricated, and tested. Then, in collaboration with Tecumseh Products Company, the prototype will be integrated with a hermetic two-stage rotary CO2 compressor. Via a common crankshaft, the mechanical power recovered by the expander will provide part of the shaft power needed to drive the compressor. The hermetic expander/compressor will be delivered to the Army for integration in ECU prototypes which are based on the carbon dioxide cycle to allow the full system benefits of the expander to be demonstrated.