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单选题
Refrigerant is normally sub-cooled in a refrigeration or air conditioning system condenser to （）.
A
maintain adequate coil back pressure
B
prohibit flashing in the liquid line
C
reduce refrigerant volume in the system
D
reduce compressor discharge line loading
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单选题Low compressor head pressure in a refrigeration system can be caused by（）.A
insufficient condenser cooling waterB
excessive condenser cooling waterC
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compressorC
condenserD
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sudden evaporation of wax crystals in the lubricantB
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单选题A refrigeration system compressor crankcase is sweating or unusually coldThis is an indication of（）.A
a shortage of refrigerant in the systemB
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compressorB
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单选题The heat removed from the refrigerant in the condenser of a refrigeration plant is the （）A
latent heat of expansionB
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heat of compressionD
all of the above
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单选题If a liquid sight flow indicator in a refrigeration system shows gas bubbles in motion passing inside of the glass, there is （）.A
too much refrigerant in the systemB
oil entrained in the refrigerantC
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ice crystals forming in the refrigerant
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单选题The only means of removing the latent heat of condensation from a refrigerant in the normal refrigeration cycle is by （）.A
passing it through the expansion valveB
condensing refrigerant in the system condenserC
passing the gaseous refrigerant through the heat interchanger on the suction side of the compressorD
maintaining a high pressure on the systems receiver
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单选题（）are supplied by main switchboard directly.A
Suez Canal searchlight, air compressor and air conditioning compressorB
Air compressor, boiler blower and refrigeration plantC
Boiler blower, Suez Canal searchlight and refrigeration plantD
Suez canal searchlight, air compressor and boiler blower
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单选题Before charging a refrigeration unit, the refrigerant charging lines should be（）A
flushed with clean refrigerant oilB
purged with the refrigerantC
washed with an ammonia and alcohol solutionD
grounded to compressor
考题
单选题Which of the fluids listed is normally used to condense the primary refrigerant in a shipboard central air conditioning system?（）A
Air or NitrogenB
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单选题Foaming of the oil in a refrigeration compressor crankcase is caused by （）.A
refrigerant boiling out of solution from the lube oilB
liquid refrigerant flooding the compressor and systemC
lube oil viscosity being reduced by refrigerant dilutionD
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单选题Refrigerant is circulated through a refrigeration system by the （）.A
compressorB
condenserC
expansion valveD
evaporator
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单选题In a chilled water air conditioning unit using a reciprocating compressor, the refrigerating effect of the primary refrigerant can be increased by （）.A
increasing refrigerant pressure in the coilB
increasing chilled water flow through the coolerC
sub-cooling the refrigerant in the condenserD
superheating the refrigerant in the compressor
考题
单选题An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.A
oil foaming in the compressorB
higher than normal suction and discharge pressures with a higher box temperatureC
higher than normal discharge pressure with a normal box temperatureD
the compressor to run continuously
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单选题Saltwater is typically provided to a refrigeration system to （）.A
cool the expansion valveB
prevent refrigerant superheatingC
condense the refrigerant gasD
prevent motor overheating
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单选题Under normal conditions, the refrigerant enters the compressor in an operating refrigeration system as a （）.A
liquidB
dry saturated gasC
wet saturated gasD
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单选题While troubleshooting a refrigeration system for low head pressure, liquid refrigerant flooding back from the evaporator is determined to be the causeIt may be necessary to （）.A
change the expansion valve adjustmentB
readjust the water regulating valve to increase the flow of waterC
purge air from the condenserD
clean the waterside of the condenser
考题
单选题When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.A
increase the amount of cooling water to the condenserB
decrease the amount of cooling water to the condenserC
add more refrigerant to the systemD
remove some refrigerant from the system
考题
单选题A purge recovery system is used in a centrifugal air conditioning or refrigeration system to （）A
purge lube oil from the liquid refrigerantB
recover water purged from the systemC
separate foul gases from the receiverD
purge non-condensable gases without losing refrigerant
考题
单选题Which of the listed refrigeration system components keeps the refrigerant circulating through the system?（）A
Expansion valveB
CondenserC
EvaporatorD
Compressor
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