Exam Question

### (a) Explanation of 'Volumetric Efficiency' in Air Compressors
Volumetric efficiency ($$\eta_v$$) in an air compressor is a critical performance parameter that quantifies the effectiveness with which the compressor draws in and delivers air. It is defined as the ratio of the actual volume of atmospheric air drawn into the compressor cylinder per stroke (or per unit time) to the theoretical (or swept) volume of the compressor cylinder per stroke (or per unit time).
In an ideal scenario, the compressor cylinder would be completely filled with atmospheric air at each suction stroke, and all of this air would be delivered. However, in reality, several factors prevent this ideal condition:
* **Clearance Volume (V_c)**: This is the residual volume remaining in the cylinder at the end of the compression stroke, even when the piston is at Top Dead Centre (TDC). The compressed air in this clearance volume must re-expand to a pressure below the suction pressure before the inlet valve can open and new atmospheric air can be drawn in. This re-expansion effectively reduces the actual volume available for intake air.