State of refrigerant in the basic vapour-compression cycle In an ideal analysis, the refrigerant is a dry saturated vapour at which location in the cycle?

Difficulty: Easy

Correct Answer: Before entering the compressor (compressor suction)

Explanation:


Introduction / Context:
Idealized vapour-compression cycle analysis often assumes specific refrigerant states at key nodes to avoid complexities like wet compression or excessive superheat.



Given Data / Assumptions:

  • Ideal single-stage cycle with isentropic compression and throttling expansion.
  • Negligible pressure drops in lines and heat exchangers.
  • Compressor handles vapour only (no liquid).


Concept / Approach:
To avoid wet compression, the suction condition is set as dry saturated vapour (or slightly superheated in practice). After compression the vapour is superheated; the condenser then desuperheats and condenses it to saturated liquid.



Step-by-Step Solution:
Compressor suction: dry saturated vapour (ideal) → safe for compression.Compressor discharge: superheated vapour at high pressure.Condenser outlet: saturated or subcooled liquid.Expansion device outlet: low-quality mixture entering evaporator.



Verification / Alternative check:
p–h and T–s diagrams in textbooks show state 1 at the saturated vapour line (or slightly to the right if superheated) for an idealized cycle.



Why Other Options Are Wrong:
Before the condenser the fluid is generally superheated; after the condenser it is liquid; after the expansion device it is a low-quality mixture, not dry vapour.



Common Pitfalls:
Assuming “before the condenser” equals saturated vapour; remember compression adds superheat that must be rejected before condensation begins.



Final Answer:
Before entering the compressor (compressor suction)


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