Refrigeration Flashcards
6 cards from real NATE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Refrigeration flashcards as text
What is the refrigeration effect and how is it calculated?
Answer: Heat absorbed in the evaporator; calculated as evaporator outlet enthalpy minus evaporator inlet enthalpy
The refrigeration effect is the heat absorbed per pound of refrigerant in the evaporator, equal to the enthalpy difference across the evaporator.
What refrigerant is commonly used in medium-temperature commercial refrigeration cases in the US?
Answer: R-404A / R-448A
R-404A has been the standard for medium-temperature commercial refrigeration, and R-448A is the common lower-GWP replacement.
What does a suction line accumulator protect in a refrigeration system?
Answer: Compressor from liquid refrigerant slugging
The accumulator traps liquid refrigerant on the suction line, boiling it off slowly rather than allowing it to enter and damage the compressor.
At what temperature range does a medium-temperature refrigeration system typically maintain a reach-in display case?
Answer: 28°F to 40°F
Medium-temperature refrigeration maintains product temperatures between 28°F and 40°F for dairy, deli, and produce applications.
What is the purpose of a filter-drier in a refrigeration system?
Answer: Remove moisture and contaminants from the refrigerant circuit
The filter-drier contains desiccant that absorbs moisture and a filter screen that traps particulates to protect the metering device and compressor.
What does a high discharge temperature on a refrigeration compressor typically indicate?
Answer: High compression ratio due to high head pressure, low suction pressure, or high superheat
High discharge temperature (above 225°F for most systems) results from high compression ratios or excessive superheat entering the compressor.