In a standard vapor-compression refrigeration cycle, the highest refrigerant temperature occurs at which point of the cycle?

Introduction / Context:
Understanding state points in a vapor-compression cycle is foundational in refrigeration and air-conditioning. Identifying where the refrigerant reaches its highest temperature helps with diagnosing discharge overheating, sizing condensers, and ensuring compressor safety.

Given Data / Assumptions:

• Cycle components: evaporator → compressor → condenser → expansion device.
• Compression is non-isothermal; it raises both pressure and temperature.
• No abnormal subcooling/flash-gas issues overriding basic trends.

Concept / Approach:
The compressor takes low-pressure vapor from the evaporator and compresses it to a high-pressure, high-temperature superheated vapor. This discharge state is the cycle’s maximum temperature. The condenser then rejects heat, decreasing refrigerant temperature toward saturation and subcooling levels.

Step-by-Step Solution:

Verification / Alternative check:
On a T–s diagram, the peak temperature is at the end of the compression line (compressor discharge) before the condensation curve.

Why Other Options Are Wrong:

• (a) Evaporator outlet is the coolest vapor state, not the hottest.
• (c) In the condenser, temperature is dropping as heat is rejected.
• (d) After throttling, temperature decreases substantially.
• (e) Temperature varies throughout the cycle.

Common Pitfalls:
Confusing “after evaporation” with “after compression.” The maximum temperature is not at evaporator exit; it is at compressor discharge.

Final Answer:
Immediately after the compressor (compressor discharge, before the condenser)