A novel multi-vane expander with rolling piston: Numerical simulation and performance parameter analysis

Volumetric expanders have emerged as favorable components for micro compressed air energy storage systems. A novel multi-vane expander with rolling piston is proposed. It is characterized by multiple sliding vanes that are installed in the stator rather than the rolling piston. The vane tip contacts the rolling piston rather than the stator. A 3D numerical simulation method based on moving meshes is employed to investigate the transient variations in parameters such as the intake flowrate and indicated power of an expander with respect to rotation angle. The indicated power, intake flowrate, adiabatic efficiency, and volumetric efficiency of an expander at different rotation speeds were obtained. A specific chamber was selected to investigate the variation patterns of parameters such as internal pressure and temperature with respect to rotation angle. Finally, the evolution of internal flow field characteristics and clearance leakage flow with rotation angle was analyzed. The results indicate that the transient performance parameters of the expander, the evolution of the flow field in the chamber, and the vane tip leakage flow all exhibit periodic fluctuations. The leakage direction through the vane tip clearance reverses with changes in the rotation angle. Mass and energy losses due to radial leakage are found to dominate those caused by the vane tip and radial clearances. The high-speed jets occurred in the intake-stage chamber and near the vane tip and radial clearances. The maximum indicated power of the expander reaches 12.64 kW, with the isentropic efficiency peaking at 68.17% at 1500 rpm.