LAUSR

Abstract Expansion power recovery in vapor compression refrigeration systems has attracted much interest in recent years due to its potential to improve the efficiency of these systems. In this study, a four-intersecting-vane rotary expander was developed and installed into an existing heat pump system to investigate how various parameters affect the system. In the experiments, temperatures and pressures were measured at 11 and 5 different locations in the system, respectively, with the power recovered by the expander measured through a dynamometer. The relationships between the rotational speed, condensing load and degree of sub-cooling and the output work and expander efficiency were investigated. Additionally, the thermodynamic behavior of the system fitted with either an expander or a throttle valve were compared and discussed. The experimental results indicated that the total expander efficiency of the expander prototype reached a maximum of 41.9% at the optimum rotational speed of 750 rpm. The expander increased the COP (Coefficient of Performance) by 4.16% compared to that of a conventional heat pump system with an expansion valve. The results demonstrated the feasibility of refurbishing existing vapor compression refrigeration systems with an expander to recover expansion power.