Theoretical and experimental analyses of the internal leakage in single-screw expanders

A single-screw expander (SSE) is a type of volumetric expander that can be applied to power generation, which is beneficial for energy conservation and environment protection. Investigating the SSE leakage characteristics is necessary because leakage has a significant influence on the SSE performance. This study provides theoretical and experimental analyses of the SSE internal leakage with compressed air as the working fluid. Both mathematical model of different leakage paths and leakage model have been established. The simulation model was verified by experimental data at internal volume ratios of 2.95 and shows a maximum deviation of 3.63%. Results show that fitting clearance height and rotational speed could clearly influence the volumetric efficiency and power output. The diameters of both the screw and the gate rotor could also significantly influence the volumetric efficiency. The volumetric efficiency decreased with the increase in internal volume ratio.