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 to high pressure and its temperature rises.
- ✓ It is throttled to low pressure, which chills it and allows it to boil at low temperature.Correct
- C. It condenses from vapor to liquid by rejecting heat to seawater.
- D. It absorbs latent heat from the refrigerated space and becomes superheated vapor.
Why B is correct
The metering device throttles high-pressure liquid to low pressure; this sudden pressure drop chills the refrigerant and allows it to re-enter the evaporator and boil at low temperature. Compression occurs at the compressor, condensation at the condenser, and heat absorption at the evaporator.
Cited:NAVEDTRA 14075 §6-1