Experimental Investigation of Leakage in the Modified Revolving Vane Expander

Abstract

This study focuses on the leakage characteristics of a modified revolving vane expander (M-RVE) using both static and dynamic leakage analysis. The no-expansion scenario showed a maximum volumetric efficiency of 18.7% was achieved at 5.5 bar(g) suction pressure, showing the severity of internal leakages. The blocker angle study demonstrated the importance of the correct opening-angle selection to avoid under or over-expansion. The maximum volumetric efficiencies for opening angles of 94 deg and 145 deg were 2.8% and 8.3%, respectively, at suction and discharge pressures of 6.5 bar(g) and 1 atm, respectively. The static leakage test demonstrated that the M-RVE housing was properly sealed, and the observed leakage in the dynamic test was mostly due to internal leakages. The results showed that the leakages through the radial clearance, endface, and vane side gaps make up 54%, 33%, and 8.5% of the overall leakage. Comparison between the theoretical and experimental data of the leakages through the radial clearance gap showed significant deviations at higher suction pressures. The reasons are thought to be due to the shafts' tilt, and the cylinder and rotor head deflections. It is believed that the deflection of the shaft created new leakage paths or changed the geometry of the current paths.