In the mechanical refrigeration cycle, the refrigerant leaving the evaporator is a ________.

• A. High-pressure liquid
• B. Low-pressure liquid
• C. High-temperature vapor
• D. Low-pressure, low-temperature vapor

Answer: (D)

In the evaporator, the refrigerant is allowed to absorb heat and boil at a low pressure. The expansion valve lowers the pressure before the fluid enters the evaporator, so the boiling point is very low. As heat is absorbed, the liquid refrigerant turns into vapor, and by the time it leaves the evaporator it is predominantly in the vapor phase at low pressure and low temperature. This vapor is then drawn into the compressor to continue the cycle.