EPA Section 608 Universal Certification ExamType III (Low-Pressure Appliances)Easy
Which of the following describes the condition of the refrigerant in a low-pressure chiller's evaporator during normal operation?
- ALow-pressure, saturated liquid/vapor mixture
- BLow-pressure, subcooled liquid
- CHigh-pressure, saturated liquid
- DHigh-pressure, superheated vapor
Show answer & explanationAnswer & explanation
Correct answer: A. Low-pressure, saturated liquid/vapor mixture
In the evaporator of a refrigeration system, the refrigerant absorbs heat from the space being cooled, causing it to boil. This results in a low-pressure, saturated liquid/vapor mixture, which then ideally leaves as a superheated vapor.
Why the other options are wrong
- B. This describes the refrigerant leaving the condenser or entering the expansion valve.
- C. This describes the refrigerant leaving the condenser before the expansion valve.
- D. This describes the refrigerant leaving the compressor.
Evaporator Refrigerant State
The thermodynamic state of refrigerant as it passes through the evaporator coil, absorbing heat and undergoing a phase change.
- Low pressure.
- Absorbs latent heat (boiling).
- Mixture of liquid and vapor.
- Exits as superheated vapor (ideally).
Memory trick: Evaporator low, a mix you'll see, liquid and vapor, wild and free.