CRST CRST Refrigerants & Thermodynamics

Question 1

What is the boiling point of R-134a at atmospheric pressure (14.7 psia)?

Accepted Answer

-15.07°F (-26.15°C)

Answer

32°F (0°C)

Answer

-40°F (-40°C)

Answer

20°F (-6.7°C)

Question 2

Which refrigerant is classified as an A1 safety group per ASHRAE 34?

Accepted Answer

R-134a

Answer

R-290 (propane)

Answer

R-717 (ammonia)

Answer

R-1234yf

Question 3

What thermodynamic process occurs in the evaporator of a vapor-compression refrigeration cycle?

Accepted Answer

Refrigerant absorbs heat from the load and vaporizes at constant pressure

Answer

Refrigerant releases heat and condenses at constant pressure

Answer

Refrigerant is compressed from low to high pressure

Answer

Refrigerant expands from high to low pressure adiabatically

Question 4

What does the term 'subcooling' refer to in a refrigeration system?

Accepted Answer

Cooling liquid refrigerant below its condensing temperature at a given pressure

Answer

Cooling suction vapor below the evaporator saturation temperature

Answer

Reducing the temperature of the compressor discharge gas

Answer

Dropping the refrigerant temperature below 0°F

Question 5

What does the Global Warming Potential (GWP) of a refrigerant measure?

Accepted Answer

Its heat-trapping potential relative to CO2 over 100 years

Answer

Its toxicity level per ASHRAE 34 classification

Answer

The amount of ozone it depletes in the stratosphere

Answer

Its flammability rating per ASTM standards

Question 6

Which refrigerant has an Ozone Depletion Potential (ODP) of zero and is commonly used in new commercial refrigeration systems in the US?

Accepted Answer

R-404A

Answer

R-12

Answer

R-502

Answer

R-22