Experimental Study on the Expansion Ratio of Single Screw Expanders under Variable Working Conditions

orc2019 Tracking Number 54

In the recovery utilization of medium and low temperature waste heat, the organic Rankine cycle(ORC) is regarded as the most potential technique. The expander plays an important role as the output power equipment of the ORC, and the single screw expander has a great prospect due to its unique structure and working characteristics. In addition to the expander efficiency, the expansion ratio is another important performance parameter of the expander, which has a great influence on the thermal efficiency of the ORC system. Based on the experimental study of the single screw expander in this laboratory, the change of the internal and external expansion ratio of single screw expander is analyzed. The experimental results show that the expansion ratio increases with the increase of rotational speed, and the external expansion ratio decreases gradually. The internal and external expansion ratio of single screw expander increases with the increase of inlet pressure. When the inlet pressure interval is 0.4~0.65 MPa, the external expansion ratio is 3.26~ 3.73, and the internal expansion ratio is 4.8~ 8.0. It can be found that the effects of internal expansion ratio of single screw expander on the working condition lager than external expansion ratio, while the latter is affected by the back pressure, but the variation is small.