Question

In an ideal air-conditioning cycle shown below, which of the following statement(s) is/are true in the segments P, Q, R, S? 

• A. P: Vapour at low pressure
• B. Q: Vapour at low pressure
• C. R: Liquid at high pressure
• D. S: Liquid--Vapour mixture at low pressure

Hint:

In the vapour-compression cycle: Low-pressure vapour → compressor → high-pressure vapour → condenser → high-pressure liquid → expansion → low-pressure mixture.

Answer 1

The Correct Option is A, C, D

In an ideal vapour-compression air-conditioning (refrigeration) cycle:

Segment P (Evaporator outlet → Compressor inlet)
The refrigerant leaving the evaporator is saturated vapour at low pressure, ready to enter the compressor. Thus, statement (A) is TRUE.

Segment Q (Compressor outlet → Condenser inlet)
After compression, the refrigerant is high-pressure, high-temperature vapour. Hence the statement "vapour at low pressure'' is false, so (B) is FALSE.

Segment R (Condenser outlet → Expansion valve inlet)
The condenser converts the high-pressure vapour into high-pressure liquid. Thus, (C) is TRUE.

Segment S (Expansion valve outlet → Evaporator inlet)
The expansion valve produces a sudden drop in pressure, causing flash evaporation → the refrigerant becomes a low-pressure liquid–vapour mixture. Thus, (D) is TRUE.

Final Answer: (A), (C), (D)