COMMERCIAL REFRIGERATION FINAL TEST WITH ALL
QUESTIONS ANSWERED CORRECTLY!!
How is the cooling effect in a mechanical refrigeration system produced?
answers: Evaporation of liquid refrigerant into vapor
What is the primary purpose of a compressor?
answers: It circulates and pressurizes the refrigerant vapor before the vapor Is
condensed for re use
Name another function that must be performed by the compressor
answers: Is raise the pressure and temperature of the refrigerant vapor. This allows
the refrigerant to condense into a liquid as it circulates through the condenser
What characteristic defines an "open" type compressor?
answers: Has a drive shaft protruding from the compressor
What are the two main disadvantages of a hermetic compressor?
answers: If either the motor or compressor malfunctions, the entire unit must be
replaced. The motor is actually a part of the refrigerant circulation system. This
means that a burnout can contaminate the entire system
In a reciprocating compressor, the piston is connected to the crankshaft by a _____
answers: Connecting rod
Name the three elements of performance that are the major factors in evaluating a
compressor
, answers: Efficiency, capacity, and economy of operation
If the suction gas superheat is too low, What could be the result?
answers: Liquid refrigerant might enter the compressor. This causes stress on the
compressor valves, wrist pins, rods, shaft, etc. It also causes excessive foaming of
the oil in the crankcase and other damaging effects. The compressor will not reach
its rated capacity
What will happen if the suction gas temperature is too high?
answers: Will cause the compressor to run hot
How is compressor efficiency often judged?
answers: Btu per cubic foot (Btu/ft^3) of displacement
When the same model of open type compressor is used with both air cooled and
water cooled condensing units, which is usually run at a slightly higher rpm?
answers: Water cooled
What is the equation for ratio of compression?
answers: The absolute discharge pressure (psig plus 14.7) divided by the absolute
suction pressure (psig plus 14.7)
What type of compressor is found in large applications up to 10000 tons?
answers: Centrifugal compressors
QUESTIONS ANSWERED CORRECTLY!!
How is the cooling effect in a mechanical refrigeration system produced?
answers: Evaporation of liquid refrigerant into vapor
What is the primary purpose of a compressor?
answers: It circulates and pressurizes the refrigerant vapor before the vapor Is
condensed for re use
Name another function that must be performed by the compressor
answers: Is raise the pressure and temperature of the refrigerant vapor. This allows
the refrigerant to condense into a liquid as it circulates through the condenser
What characteristic defines an "open" type compressor?
answers: Has a drive shaft protruding from the compressor
What are the two main disadvantages of a hermetic compressor?
answers: If either the motor or compressor malfunctions, the entire unit must be
replaced. The motor is actually a part of the refrigerant circulation system. This
means that a burnout can contaminate the entire system
In a reciprocating compressor, the piston is connected to the crankshaft by a _____
answers: Connecting rod
Name the three elements of performance that are the major factors in evaluating a
compressor
, answers: Efficiency, capacity, and economy of operation
If the suction gas superheat is too low, What could be the result?
answers: Liquid refrigerant might enter the compressor. This causes stress on the
compressor valves, wrist pins, rods, shaft, etc. It also causes excessive foaming of
the oil in the crankcase and other damaging effects. The compressor will not reach
its rated capacity
What will happen if the suction gas temperature is too high?
answers: Will cause the compressor to run hot
How is compressor efficiency often judged?
answers: Btu per cubic foot (Btu/ft^3) of displacement
When the same model of open type compressor is used with both air cooled and
water cooled condensing units, which is usually run at a slightly higher rpm?
answers: Water cooled
What is the equation for ratio of compression?
answers: The absolute discharge pressure (psig plus 14.7) divided by the absolute
suction pressure (psig plus 14.7)
What type of compressor is found in large applications up to 10000 tons?
answers: Centrifugal compressors
