CFD Modeling of a Scroll Work Recovery Expander for Trans-critical CO2 Refrigeration System

Fluid flow characteristics of CO2, as a refrigerant in a scroll work recovery expander is investigated using CFD approach. A 2D simulation is carried out, adopting dynamic mesh in Ansys environment (FLUENT) and turbulent flow in the scroll expander is modeled using PISO algorithm. Changing behavior of CO2 during suction, expansion and exhaust process in a scroll involute are captured at four rotation angles. Study is carried out for a commercially available geometry. Pressure and velocity distribution of CO2 along the involute profile for the trans-critical expansion process is presented. It is observed that the leakage space can be further optimized to reduce the internal leakage of CO2 which can increase the overall efficiency of the scroll expander.