Air motors vs. compressors: A reciprocating air motor runs on the thermodynamic cycle that is the reverse of a reciprocating air compressor, not the same process sequence.

Difficulty: Easy

Correct Answer: False

Explanation:


Introduction / Context:
Reciprocating air motors and compressors are thermodynamic counterparts. Where a compressor consumes work to raise air pressure, an air motor expands compressed air to produce work.



Given Data / Assumptions:

  • Idealized cycles to illustrate the relationship.
  • Neglect small losses and throttling for the conceptual comparison.


Concept / Approach:
On a p–v diagram, a compressor traces a loop representing intake at low pressure, compression, and discharge at high pressure. An air motor traces a reversed loop: admission at high pressure, expansion delivering work, and exhaust at low pressure. Hence the operation is not “similar” in process direction; it is the reverse.



Step-by-Step Solution:

Compressor: intake → compression → delivery; work input required.Air motor: admission → expansion → exhaust; work output delivered.Thus, the statement “operation is similar” is false in a thermodynamic sense; it is reversed.


Verification / Alternative check:
Indicator diagrams from lab rigs show the compressor and air motor loops mirrored about an axis, confirming the reversal.



Why Other Options Are Wrong:
Any “True/only if” variants misrepresent the fundamental reversal; specific heat transfer modes do not change that.



Common Pitfalls:
Equating mechanical construction similarity (cylinders, pistons, valves) with thermodynamic process similarity; the hardware may look alike, but the cycle direction differs.



Final Answer:
False

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