is the ratio of actual capacity to piston displacement, stated as a percentage.
Volumetric efficiency of a compressor is defined as the ratio of actual volume sucked by the compressor at the inlet to the swept volume.
Where C is clearance ratio, it is the ratio of clearance volume to swept volume.
P2 is the delivery pressure and P1 is the suction pressure.
With an increase in clearance ratio and pressure ratio, the volumetric efficiency is decreased.
Volumetric efficiency decreases when
- Outlet pressure increases
- Clearance ratio increases
Volumetric efficiency increases when
- Inlet temperature increases
- As the pressure ratio decreases
In general, as the compression ratio increases, the volumetric efficiency decreases. This is because a higher compression ratio often results in higher intake temperatures and pressures, which can cause the gas to expand, reducing the actual volume that can be sucked into the compressor for a given piston displacement.