Compressor efficiencies: identify the ratio IP/BP For a compressor driven by a prime mover, consider the ratio of indicated power (IP) to the shaft/brake power (BP) supplied to the compressor. What is this efficiency called? Choose the correct term.

Concept/Approach
Mechanical efficiency of a compressor quantifies how effectively the input shaft (brake) power is converted into indicated power within the cylinder, i.e., η_mech = IP / BP.

Notes

• Volumetric efficiency relates to the mass (or volume) actually inducted vs. swept volume.
• Isothermal efficiency compares actual compression work to ideal isothermal work.
• Overall/compressor efficiency aggregates multiple effects; it is not simply IP/BP.

Final Answer
Mechanical efficiency