Performance Characteristics of Scroll Expander for CO2 Refrigeration Cycles

To help lesser the effects of global warming, C0 2 refrigeration cycles are required in refrigeration and airconditioning applications. Work-output expansion devices (expanders) are needed to improve the system performances, but their efficiencies are still too low to make the systems practical. The improvement in the COP of a C0 2 refrigeration cycle is highly dependent on expander efficiency. To solve this problem, we developed a prototype of a scroll expander for C02 refrigeration cycles and studied its performance characteristics. The experimental parameters are rotational speed, inlet pressure and temperature, exit pressure, and C02 mass fl ow rate of the scroll expander. The test results show that our scroll expander had maximum measured isentropic efficiencies greater than 70%. We confirmed that our scroll expander has a high potential for making C02 refrigeration systems practical.