1. Q: What is the primary purpose of a refrigeration system? ANSWER
To remove heat from a space or substance and transfer it to another location
where it can be rejected to the environment.
2. Q: What are the four basic components of a vapor-compression
refrigeration system? ANSWER Compressor, condenser, expansion device,
and evaporator.
3. Q: What happens to refrigerant in the evaporator? ANSWER The
refrigerant absorbs heat and changes from liquid to vapor at low pressure and
temperature.
4. Q: What is the function of the compressor in a refrigeration system?
ANSWER To compress the low-pressure refrigerant vapor and raise its
pressure and temperature before sending it to the condenser.
5. Q: What occurs in the condenser? ANSWER The high-pressure, high-
temperature refrigerant vapor releases heat to the environment and condenses
into a liquid.
6. Q: What is the purpose of the expansion device? ANSWER To reduce
the pressure and temperature of the liquid refrigerant before it enters the
evaporator.
7. Q: What is superheat? ANSWER The temperature of vapor above its
saturation temperature at a given pressure.
8. Q: What is subcooling? ANSWER The temperature of liquid below its
saturation temperature at a given pressure.
9. Q: What is the saturation temperature? ANSWER The temperature at
which a substance changes phase (liquid to vapor or vapor to liquid) at a given
pressure.
,10. Q: What is latent heat? ANSWER The amount of heat required to change
the phase of a substance without changing its temperature.
11. Q: What is sensible heat? ANSWER Heat that causes a temperature
change in a substance without changing its phase.
12. Q: What is the relationship between pressure and boiling point?
ANSWER As pressure increases, the boiling point increases; as pressure
decreases, the boiling point decreases.
13. Q: What is a BTU? ANSWER British Thermal Unit - the amount of heat
required to raise the temperature of one pound of water by one degree
Fahrenheit.
14. Q: What is a ton of refrigeration? ANSWER The amount of cooling
required to freeze one ton (2,000 pounds) of water at 32°F in 24 hours,
equivalent to 12,000 BTU/hr.
15. Q: What is the difference between R-22 and R-410A refrigerants?
ANSWER R-22 is an HCFC refrigerant being phased out, while R-410A is an
HFC blend that operates at higher pressures and is more environmentally
friendly.
16. Q: What is the purpose of refrigerant oil? ANSWER To lubricate the
compressor's moving parts and create seals between components.
17. Q: What is a P-H diagram? ANSWER A pressure-enthalpy diagram used
to analyze refrigeration cycles and determine system performance.
18. Q: What is the coefficient of performance (COP)? ANSWER The ratio
of useful cooling or heating provided to the energy consumed by the system.
19. Q: What is the ideal refrigeration cycle called? ANSWER The reverse
Carnot cycle.
20. Q: What is the actual refrigeration cycle called? ANSWER The vapor-
compression cycle.
21. Q: What causes refrigerant to flow through the system? ANSWER
Pressure differences created by the compressor and expansion device.
22. Q: What is the purpose of a receiver tank? ANSWER To store liquid
refrigerant and accommodate variations in system charge.
23. Q: What is a liquid line? ANSWER The piping that carries high-pressure
liquid refrigerant from the condenser to the expansion device.
, 24. Q: What is a suction line? ANSWER The piping that carries low-pressure
vapor refrigerant from the evaporator to the compressor.
25. Q: What is a discharge line? ANSWER The piping that carries high-
pressure, high-temperature vapor from the compressor to the condenser.
26. Q: What is refrigerant migration? ANSWER The movement of
refrigerant to the coldest part of the system when not operating.
27. Q: What is a crankcase heater used for? ANSWER To prevent
refrigerant from condensing in the compressor crankcase during off cycles.
28. Q: What is the purpose of insulation on suction lines? ANSWER To
prevent heat gain and condensation on the cold refrigerant vapor.
29. Q: What is flash gas? ANSWER Refrigerant that vaporizes immediately
when pressure drops across the expansion device.
30. Q: What is wet compression? ANSWER Compression of refrigerant
vapor that contains liquid droplets, which can damage the compressor.
31. Q: What is dry compression? ANSWER Compression of refrigerant
vapor that is completely in the gaseous state.
32. Q: What is the critical temperature of a refrigerant? ANSWER The
temperature above which the refrigerant cannot be condensed regardless of
pressure.
33. Q: What is the critical pressure of a refrigerant? ANSWER The
pressure at the critical temperature above which liquid and vapor phases cannot
exist separately.
34. Q: What is refrigerant quality? ANSWER The percentage of vapor in a
liquid-vapor mixture by weight.
35. Q: What is specific volume? ANSWER The volume occupied by a unit
mass of substance, typically measured in cubic feet per pound.
36. Q: What is enthalpy? ANSWER The total heat content of a substance,
measured in BTU per pound.
37. Q: What is entropy? ANSWER A measure of the molecular disorder or
randomness in a substance.
38. Q: What is the difference between absolute pressure and gauge
pressure? ANSWER Absolute pressure includes atmospheric pressure (14.7
To remove heat from a space or substance and transfer it to another location
where it can be rejected to the environment.
2. Q: What are the four basic components of a vapor-compression
refrigeration system? ANSWER Compressor, condenser, expansion device,
and evaporator.
3. Q: What happens to refrigerant in the evaporator? ANSWER The
refrigerant absorbs heat and changes from liquid to vapor at low pressure and
temperature.
4. Q: What is the function of the compressor in a refrigeration system?
ANSWER To compress the low-pressure refrigerant vapor and raise its
pressure and temperature before sending it to the condenser.
5. Q: What occurs in the condenser? ANSWER The high-pressure, high-
temperature refrigerant vapor releases heat to the environment and condenses
into a liquid.
6. Q: What is the purpose of the expansion device? ANSWER To reduce
the pressure and temperature of the liquid refrigerant before it enters the
evaporator.
7. Q: What is superheat? ANSWER The temperature of vapor above its
saturation temperature at a given pressure.
8. Q: What is subcooling? ANSWER The temperature of liquid below its
saturation temperature at a given pressure.
9. Q: What is the saturation temperature? ANSWER The temperature at
which a substance changes phase (liquid to vapor or vapor to liquid) at a given
pressure.
,10. Q: What is latent heat? ANSWER The amount of heat required to change
the phase of a substance without changing its temperature.
11. Q: What is sensible heat? ANSWER Heat that causes a temperature
change in a substance without changing its phase.
12. Q: What is the relationship between pressure and boiling point?
ANSWER As pressure increases, the boiling point increases; as pressure
decreases, the boiling point decreases.
13. Q: What is a BTU? ANSWER British Thermal Unit - the amount of heat
required to raise the temperature of one pound of water by one degree
Fahrenheit.
14. Q: What is a ton of refrigeration? ANSWER The amount of cooling
required to freeze one ton (2,000 pounds) of water at 32°F in 24 hours,
equivalent to 12,000 BTU/hr.
15. Q: What is the difference between R-22 and R-410A refrigerants?
ANSWER R-22 is an HCFC refrigerant being phased out, while R-410A is an
HFC blend that operates at higher pressures and is more environmentally
friendly.
16. Q: What is the purpose of refrigerant oil? ANSWER To lubricate the
compressor's moving parts and create seals between components.
17. Q: What is a P-H diagram? ANSWER A pressure-enthalpy diagram used
to analyze refrigeration cycles and determine system performance.
18. Q: What is the coefficient of performance (COP)? ANSWER The ratio
of useful cooling or heating provided to the energy consumed by the system.
19. Q: What is the ideal refrigeration cycle called? ANSWER The reverse
Carnot cycle.
20. Q: What is the actual refrigeration cycle called? ANSWER The vapor-
compression cycle.
21. Q: What causes refrigerant to flow through the system? ANSWER
Pressure differences created by the compressor and expansion device.
22. Q: What is the purpose of a receiver tank? ANSWER To store liquid
refrigerant and accommodate variations in system charge.
23. Q: What is a liquid line? ANSWER The piping that carries high-pressure
liquid refrigerant from the condenser to the expansion device.
, 24. Q: What is a suction line? ANSWER The piping that carries low-pressure
vapor refrigerant from the evaporator to the compressor.
25. Q: What is a discharge line? ANSWER The piping that carries high-
pressure, high-temperature vapor from the compressor to the condenser.
26. Q: What is refrigerant migration? ANSWER The movement of
refrigerant to the coldest part of the system when not operating.
27. Q: What is a crankcase heater used for? ANSWER To prevent
refrigerant from condensing in the compressor crankcase during off cycles.
28. Q: What is the purpose of insulation on suction lines? ANSWER To
prevent heat gain and condensation on the cold refrigerant vapor.
29. Q: What is flash gas? ANSWER Refrigerant that vaporizes immediately
when pressure drops across the expansion device.
30. Q: What is wet compression? ANSWER Compression of refrigerant
vapor that contains liquid droplets, which can damage the compressor.
31. Q: What is dry compression? ANSWER Compression of refrigerant
vapor that is completely in the gaseous state.
32. Q: What is the critical temperature of a refrigerant? ANSWER The
temperature above which the refrigerant cannot be condensed regardless of
pressure.
33. Q: What is the critical pressure of a refrigerant? ANSWER The
pressure at the critical temperature above which liquid and vapor phases cannot
exist separately.
34. Q: What is refrigerant quality? ANSWER The percentage of vapor in a
liquid-vapor mixture by weight.
35. Q: What is specific volume? ANSWER The volume occupied by a unit
mass of substance, typically measured in cubic feet per pound.
36. Q: What is enthalpy? ANSWER The total heat content of a substance,
measured in BTU per pound.
37. Q: What is entropy? ANSWER A measure of the molecular disorder or
randomness in a substance.
38. Q: What is the difference between absolute pressure and gauge
pressure? ANSWER Absolute pressure includes atmospheric pressure (14.7
