Two-stage reciprocating air compressors: find the incorrect statement (if any). Consider intercooling, minimum work allocation per stage, and the definition of volumetric efficiency. Determine which statement is wrong; if all are correct, select 'none of the above'.
Mechanical Engineering
Compressors, Gas Dynamics and Gas Turbines
Difficulty: Medium
Choose an option
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AIn a two-stage reciprocating air compressor with complete intercooling, maximum work is saved.
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BThe minimum work required for a two-stage compressor equals twice the work required for each stage.
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CThe ratio of free air delivered per stroke to the piston’s swept volume is called volumetric efficiency.
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Dnone of the above
Answer
Correct Answer: none of the above
Explanation
Given factsTwo-stage compression with perfect intercooling (and equal pressure ratios) minimizes total work. For minimum-work allocation, both stages do equal work, so total work = 2 × (work per stage). Volumetric efficiency is defined as (free air delivery per stroke)/(swept volume).
EvaluationA is correct: perfect intercooling gives the least work.B is correct: at the minimum-work condition, work is split equally; hence total is twice that per stage.C is the standard definition of volumetric efficiency.
ConclusionSince A, B, and C are correct, there is no wrong statement among them.
Final Answernone of the above.