Compressor discharge state: In a vapor-compression cycle, what is the most accurate description of the refrigerant state as it leaves the compressor and enters the condenser?

Introduction / Context:
The compressor raises both pressure and temperature of the refrigerant vapor. Recognizing the discharge state helps in setting condenser controls and evaluating superheat levels for energy efficiency and reliability.

Given Data / Assumptions:

• Compressor inlet is superheated to protect against liquid slugging.
• Compression is non-isentropic but raises temperature above saturation at the discharge pressure.
• No desuperheating occurs inside the compressor.

Concept / Approach:
Because the compressor adds work, the outlet temperature exceeds the saturation temperature at the condenser pressure. Hence, the discharge is superheated vapor. Desuperheating and condensation then occur in the condenser at nearly constant pressure.

Step-by-Step Solution:

Verification / Alternative check:
On a pressure–enthalpy or temperature–entropy diagram, the compression path ends to the right of the saturated vapor line at condenser pressure.

Why Other Options Are Wrong:

• Saturated liquid: occurs at condenser outlet, not compressor outlet.
• Wet vapor: would risk liquid carryover; compressors are designed to avoid this.
• Dry saturated vapor: rarely exact; discharge superheat is typical and measurable.

Common Pitfalls:
Assuming “just saturated” at discharge; in practice, some superheat is always present.

Final Answer:
Superheated vapour