USCG Exam PracticeRefrigeration principles and systems
In the vapor-compression refrigeration cycle, what happens to the refrigerant as it passes through the metering (expansion) device?
- A. It is compressed from low pressure to high pressure, raising its temperature.
- ✓ It is throttled from high pressure to low pressure, chilling it so it can boil at low temperature.Correct
- C. It condenses from vapor to liquid by rejecting heat to the cooling medium.
- D. It absorbs latent heat from the refrigerated space and turns into low-pressure vapor.
Why B is correct
The metering device throttles the high-pressure liquid to low pressure; this sudden pressure drop chills the refrigerant and allows it to boil at low temperature as it re-enters the evaporator. Compression occurs at the compressor, condensation at the condenser, and heat absorption at the evaporator. (NAVEDTRA 14075 §6-1)
Cited:NAVEDTRA 14075 §6-1