Solve this multiple-choice question and choose the correct option.

Concept/ApproachCheck each statement against standard definitions and thermodynamic results for gas compression. Analysis of optionsA: The ratio p2/p1 is the compression ratio, not efficiency → false.B: For a compressor, discharge pressure p2 > inlet pressure p1, so p2/p1 > 1 → true.C: Work per cycle divided by stroke volume defines mean effective pressure, not capacity → false.D: For a given pressure ratio, isothermal compression requires the minimum work; polytropic/adiabatic require more → false. Final AnswerThe compression ratio for a compressor is always greater than unity.

Compressor fundamentals: select the correct statement among the following. Evaluate each statement about definitions and work in air compression, and choose the only correct one.

Mechanical Engineering Compressors, Gas Dynamics and Gas Turbines Difficulty: Easy

Choose an option

A

The ratio of discharge pressure to inlet pressure is called compressor efficiency.
B

The compression ratio for a compressor is always greater than unity.
C

Compressor capacity is the ratio of workdone per cycle to the stroke volume.
D

During isothermal compression, the workdone in a compressor is maximum.

Answer

Correct Answer: The compression ratio for a compressor is always greater than unity.

Explanation

Concept/ApproachCheck each statement against standard definitions and thermodynamic results for gas compression.

Analysis of optionsA: The ratio p₂/p₁ is the compression ratio, not efficiency → false.B: For a compressor, discharge pressure p₂ > inlet pressure p₁, so p₂/p₁ > 1 → true.C: Work per cycle divided by stroke volume defines mean effective pressure, not capacity → false.D: For a given pressure ratio, isothermal compression requires the minimum work; polytropic/adiabatic require more → false.

Final AnswerThe compression ratio for a compressor is always greater than unity.