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单选题
Moisture in the refrigerant may （）.
A
freeze on the expansion valve seat and reduce the flow of liquid refrigerant
B
emulsify the oil in the condenser
C
freeze in the king valve
D
clog the oil trap
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The moisture equilibrium chart can be used to determine the ______．A.Absolute moisture content of the air surrounding a hygroscopic cargo when moisture equilibrium existsB.Dew point temperature that the air surrounding a hygroscopic commodity will have when in moisture equilibrium with that commodityC.Enthalpy of the air surrounding a hydroscopic cargo which is in moisture equilibrium with the cargoD.Temperature at which moisture equilibrium will occur in a cargo hold containing a hygroscopic cargo
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单选题If the moisture content of the cargo sample is（）the Transportable Moisture Limit,then the cargo should be safe to load.A
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belowC
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单选题As the refrigerant passes through the valve orifice, its pressure is reduced and part of the refrigerant turns into （）.A
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单选题Insufficient refrigerant in a refrigeration plant may result in （）.A
high discharge pressureB
frosting of the crankcaseC
high temperature of the overboard waterD
low suction pressure of compressor
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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
考题
单选题Moisture is removed from a refrigeration system by（）.A
bleeding refrigerant from the condenserB
opening a drain petcock on the oil separatorC
condensing the water in the heat exchangerD
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考题
单选题A pressure drop through the refrigerant liquid line may cause （）.A
solenoid valve to seizeB
compressor to huntC
formation of flash gas in the liquid lineD
expansion valve to freeze open
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单选题As the air passes through the charge air cooler, its temperature may be reduced and moisture condensed, with the condensate in danger of being carried into the engineSo a water separator should be mounted beneath the bottom part of the engine inlet manifoldA water separator is used in order to （）.A
keep the air from being carried into the engineB
keep the moisture from being condensedC
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单选题Clouds form（）.A
as a mass of warm，humid air rises into the atmosphere and cools，condensing moisture into small dropletsB
as winds blow across bodies of water，the sun causes the moisture to be absorbed and move upward forming cloudsC
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when the relative humidity of the atmosphere is low
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单选题If the refrigeration compressor crankcase is sweating, the cause may be due to （）.A
a shortage of refrigerantB
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单选题The purpose of the purge valve at the top of the condenser in a refrigerating system is to（）A
remove any air that may accumulate in the systemB
take out unpleasant fumes from the refrigerantC
vent off excess refrigerant in an emergencyD
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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
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考题
单选题Excessively warm water leaving condenser may be caused by（）A
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air or non-condensable gas in systemD
overcharge of refrigerant
考题
单选题The moisture equilibrium chart can be used to determine the（）.A
Absolute moisture content of the air surrounding a hygroscopic cargo when moisture equilibrium existsB
Dew point temperature that the air surrounding a hygroscopic commodity will have when in moisture equilibrium with that commodityC
Enthalpy of the air surrounding a hydroscopic cargo which is in moisture equilibrium with the cargoD
Temperature at which moisture equilibrium will occur in a cargo hold containing a hygroscopic cargo
考题
单选题Which of the following may cause that the compressor cuts off on high pressure cutout in a refrigeration plant? （） (1) faulty condensing (2) too few refrigerant (3) high discharge pressureA
any of (1) and (3)B
any of (1) and (2)C
any of (2) and (3)D
any of (1), (2) and (3)
考题
单选题Separation cloths may be used to（）.A
absorb moisture from hygroscopic cargoesB
fill gaps between layers of cargoC
wrap cargo that leaks from packagingD
keep bagged cargo leakage from contacting the deck
考题
单选题The thermostatic valve has a throttling action, that is to say the valve can（）A
stop the refrigerant from flowingB
force the refrigerant to flowC
cause the refrigerant pressure to riseD
cause the refrigerant pressure to fall
考题
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Hot air can hold（）.A
less moisture than cold airB
more moisture than cold airC
the same amount of moisture as cold airD
moisture independent of air temperature
考题
单选题A sight glass is installed in the liquid line to indicate the condition of the refrigerant charge and may also indicate the （）.A
condition of the expansion valveB
moisture in the systemC
condition of the compressor suction valvesD
condenser temperature
考题
单选题The presence of bubbles in a refrigeration system liquid line may （）.A
promote refrigerant dehydrationB
be absorbed in the receiverC
cause low condensing pressureD
carry moisture and lead to corrosion
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