Comparison between modeling and experiments on a two-stage rotary vane expander for an HFC-410A air conditioning system

Substituting throttle valve with expander can effectively enhance the performance of a refrigeration system. A novel rotary vane expander with two-stage internal expansion was developed for HFC-410A air conditioning system. The structural characteristics and operating principle of the expander are presented. A simulation model including thermodynamic and dynamic calculations is established. An HFC-410A air conditioning system was built for the purposes of testing the prototype and verifying the model. Through the experimental results, the maximum volumetric efficiency was 55% at 1800 r/min and the maximum isentropic efficiency of the prototype was 31.5% at 1404 r/min. The maximum improvement in the system coefficient of performance was 10.3% at 1404 r/min, in comparison with the coefficient of performance without the expander. Higher rotational speed could reduce leakage time thus improve volumetric efficiency; however, it also generated more frictional loss that eventually deteriorated the expander performance. Properly increasing the condensation pressure could help reducing frictional loss at high speed, thus further improve the overall performance of the expander. The results also show that the expander has a better adaptability to variable operating conditions at high rotational speed.