CO Refrigeration Contractor Exam
Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A|
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1. What is the primary purpose of a refrigeration system?
A. To generate heat inside the conditioned space
B. To increase atmospheric pressure
C. To remove heat from a designated space or substance
D. To increase humidity
Rationale: A refrigeration system operates by transferring heat from a
low-temperature region to a higher-temperature sink. The
fundamental purpose is to remove unwanted heat from a space,
product, or process.
2. Which component of a refrigeration system normally rejects heat
to the surrounding environment?
,A. Evaporator
B. Expansion valve
C. Compressor
D. Condenser
Rationale: The condenser receives high-pressure refrigerant vapor
from the compressor and removes heat from it. As heat is rejected, the
refrigerant changes from vapor to liquid.
3. What is the primary function of the compressor in a vapor-
compression refrigeration system?
A. Reduce refrigerant pressure
B. Remove moisture from refrigerant
C. Raise refrigerant vapor pressure and circulate refrigerant
D. Convert liquid refrigerant directly into ice
Rationale: The compressor draws in low-pressure vapor from the
evaporator and compresses it into a high-pressure vapor. It also
provides the pressure difference needed to move refrigerant through
the system.
4. What occurs in the evaporator?
A. Refrigerant rejects heat and condenses
B. Refrigerant is compressed
,C. Refrigerant absorbs heat and evaporates
D. Refrigerant is stored permanently
Rationale: The evaporator is the heat-absorbing component. Low-
pressure refrigerant absorbs heat from the refrigerated space or
product and changes from liquid or liquid-vapor mixture into vapor.
5. What is the purpose of an expansion valve?
A. Increase compressor horsepower
B. Increase condenser pressure
C. Meter refrigerant into the evaporator and reduce its pressure
D. Remove oil from the compressor
Rationale: The expansion device controls refrigerant flow into the
evaporator while producing a pressure drop. This allows the
refrigerant to enter the evaporator at the appropriate low pressure
and temperature.
6. What is superheat?
A. Heat added to liquid below its boiling point
B. Heat added to a vapor after it has reached its saturation
temperature
C. Heat removed from a saturated liquid
D. Heat contained only in the condenser
, Rationale: Superheat is the temperature of a vapor above its
saturation temperature at a given pressure. Measuring superheat
helps determine whether liquid refrigerant is returning to the
compressor.
7. What is subcooling?
A. Heating vapor above saturation
B. Cooling a liquid below its saturation temperature
C. Increasing suction pressure
D. Heating refrigerant before compression
Rationale: Subcooling occurs when liquid refrigerant is cooled below
its condensing or saturation temperature. Adequate subcooling helps
ensure that solid liquid refrigerant reaches the metering device.
8. What condition can occur if liquid refrigerant enters a
reciprocating compressor?
A. Improved compressor lubrication
B. Lower electrical demand in all cases
C. Liquid slugging and possible compressor damage
D. Increased evaporator superheat
Rationale: Compressors are designed primarily to compress vapor.
Because liquid is essentially incompressible, liquid entering the
Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A|
Instant Download Pdf
1. What is the primary purpose of a refrigeration system?
A. To generate heat inside the conditioned space
B. To increase atmospheric pressure
C. To remove heat from a designated space or substance
D. To increase humidity
Rationale: A refrigeration system operates by transferring heat from a
low-temperature region to a higher-temperature sink. The
fundamental purpose is to remove unwanted heat from a space,
product, or process.
2. Which component of a refrigeration system normally rejects heat
to the surrounding environment?
,A. Evaporator
B. Expansion valve
C. Compressor
D. Condenser
Rationale: The condenser receives high-pressure refrigerant vapor
from the compressor and removes heat from it. As heat is rejected, the
refrigerant changes from vapor to liquid.
3. What is the primary function of the compressor in a vapor-
compression refrigeration system?
A. Reduce refrigerant pressure
B. Remove moisture from refrigerant
C. Raise refrigerant vapor pressure and circulate refrigerant
D. Convert liquid refrigerant directly into ice
Rationale: The compressor draws in low-pressure vapor from the
evaporator and compresses it into a high-pressure vapor. It also
provides the pressure difference needed to move refrigerant through
the system.
4. What occurs in the evaporator?
A. Refrigerant rejects heat and condenses
B. Refrigerant is compressed
,C. Refrigerant absorbs heat and evaporates
D. Refrigerant is stored permanently
Rationale: The evaporator is the heat-absorbing component. Low-
pressure refrigerant absorbs heat from the refrigerated space or
product and changes from liquid or liquid-vapor mixture into vapor.
5. What is the purpose of an expansion valve?
A. Increase compressor horsepower
B. Increase condenser pressure
C. Meter refrigerant into the evaporator and reduce its pressure
D. Remove oil from the compressor
Rationale: The expansion device controls refrigerant flow into the
evaporator while producing a pressure drop. This allows the
refrigerant to enter the evaporator at the appropriate low pressure
and temperature.
6. What is superheat?
A. Heat added to liquid below its boiling point
B. Heat added to a vapor after it has reached its saturation
temperature
C. Heat removed from a saturated liquid
D. Heat contained only in the condenser
, Rationale: Superheat is the temperature of a vapor above its
saturation temperature at a given pressure. Measuring superheat
helps determine whether liquid refrigerant is returning to the
compressor.
7. What is subcooling?
A. Heating vapor above saturation
B. Cooling a liquid below its saturation temperature
C. Increasing suction pressure
D. Heating refrigerant before compression
Rationale: Subcooling occurs when liquid refrigerant is cooled below
its condensing or saturation temperature. Adequate subcooling helps
ensure that solid liquid refrigerant reaches the metering device.
8. What condition can occur if liquid refrigerant enters a
reciprocating compressor?
A. Improved compressor lubrication
B. Lower electrical demand in all cases
C. Liquid slugging and possible compressor damage
D. Increased evaporator superheat
Rationale: Compressors are designed primarily to compress vapor.
Because liquid is essentially incompressible, liquid entering the
