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单选题
The principal purpose of sub-cooling liquid refrigerant prior to its entering the expansion valve is to （）.
A
increase the refrigerating effect, by decreasing the amount of flash gas
B
allow the refrigerant to enter the throttling device in a saturated condition
C
increase the refrigerating effect by increasing the amount of flash gas
D
minimize the temperature drop of the liquid as it passes through the solenoid valve to the outlet side
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更多 “单选题The principal purpose of sub-cooling liquid refrigerant prior to its entering the expansion valve is to （）.A increase the refrigerating effect, by decreasing the amount of flash gasB allow the refrigerant to enter the throttling device in a saturated conditionC increase the refrigerating effect by increasing the amount of flash gasD minimize the temperature drop of the liquid as it passes through the solenoid valve to the outlet side” 相关考题
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If the refrigeration compressor crankcase is sweating, the cause may be due toA.a shortage of refrigerantB.the compressor running continuouslyC.liquid refrigerant returning to the compressorD.the compressor short cycling on the high pressure cutout
考题
To add refrigerant to the low side of an air conditioning system, the refrigerant should be introduced through the_______ .A.suction service valve as a vaporB.suction service valve as a liquidC.discharge service valve as a vaporD.charging valve as a liquid
考题
If the superheat value of a thermostatic expansion valve is set too low, the _.A.the suction line will be abnormally cold and liquid may slug back to the compressorB.the suction line will be hot due to a reduced amount of refrigerant returning to the compressorC.the temperature of the refrigerant within the condenser will remain the sameD.the temperature of the refrigerant passing through the sub-cooler will decrease
考题
If liquid refrigerant accidentally comes in contact with the eyes, _____ immediately.A.rub the eyesB.irritate the eyesC.wash the eyes with a heavy boric acid solutionD.obtain medical help
考题
Sub-cooling is a method of reducing the temperature of the liquid refrigerant below its ______.A.freezing pointB.floc point(浊点)C.condensing temperatureD.compression temperature
考题
单选题Which of the problems listed could be indicated if a sight glass in the refrigerant liquid line is full of bubbles?（）A
Proper refrigerant chargeB
Faulty expansion valveC
Insufficient refrigerantD
Solenoid valve stuck open
考题
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
air in the systemC
an accumulation of liquid refrigerant in the crankcaseD
a shortage of oil in the crankcase
考题
单选题An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by （）.A
restriction in refrigerant pipingB
air and non-condensable gases in the condenserC
water in the refrigerantD
flooding back of liquid refrigerant from the evaporator
考题
单选题Refrigerant is normally sub-cooled in a refrigeration or air conditioning system condenser to （）.A
maintain adequate coil back pressureB
prohibit flashing in the liquid lineC
reduce refrigerant volume in the systemD
reduce compressor discharge line loading
考题
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
less than a full charge of refrigerant in the systemD
ice crystals forming in the refrigerant
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
考题
单选题In a compression refrigeration cycle, the temperature of the liquid refrigerant experiences its greatest decrease in the（）.A
evaporatorB
compressorC
expansion valveD
condenser
考题
单选题The temperature of the refrigerant in the evaporator coil depends mostly upon the （）.A
refrigerant pressure in the evaporatorB
cooling water temperature to the condenserC
heat load in the refrigerator compartmentD
solenoid valve in the liquid line
考题
单选题One cause of high head pressure occurring in a refrigeration system can be （）.A
insufficient cooling water flow to the condenserB
a low refrigerant charge in the systemC
the liquid valve is open too muchD
high evaporator superheat
考题
单选题Moisture in the refrigerant may （）.A
freeze on the expansion valve seat and reduce the flow of liquid refrigerantB
emulsify the oil in the condenserC
freeze in the king valveD
clog the oil trap
考题
单选题In a compression refrigeration plant the hot, high pressure refrigerant gas is cooled by the sea water and becomes liquid in the （）.A
compressorB
condenserC
throttle valveD
evaporator
考题
单选题The principal purpose of magnetic compass adjustment is to（）.A
reduce the variation as much as possibleB
reduce the deviation as much as possibleC
reduce the magnetic dip as much as possibleD
allow the compass bowl to swing freely on its gimbals
考题
单选题To add refrigerant to the low side of an air conditioning system, the refrigerant should be introduced through the （）A
suction service valve as a vaporB
suction service valve as a liquidC
discharge service valve as a vaporD
charging valve as a liquid
考题
单选题“Flooding back” is a condition where the liquid refrigerant （）.A
vaporizes in the condenserB
reaches the compressor through the suction lineC
flashes in the liquid lineD
condenses in the receiver
考题
单选题Which of the listed statements is a characteristic of the liquid charged power element used with thermostatic expansion valves?（）A
At the designed operating temperature, the liquid refrigerant charge has changed to a vaporB
The liquid refrigerant tends to collect at the bellows or diaphragm and reduces the valve sensitivityC
The sensing bulb is empty of liquid refrigerant charge at the designed operating temperatureD
The sensing bulb is never emptied of liquid refrigerant under normal operating conditions
考题
单选题The principal purpose of sub-cooling liquid refrigerant prior to its entering the expansion valve is to （）.A
increase the refrigerating effect, by decreasing the amount of flash gasB
allow the refrigerant to enter the throttling device in a saturated conditionC
increase the refrigerating effect by increasing the amount of flash gasD
minimize the temperature drop of the liquid as it passes through the solenoid valve to the outlet side
考题
单选题Sub-cooling is a method of reducing the temperature of the liquid refrigerant below its （）.A
freezing pointB
floc pointC
condensing temperatureD
compression temperature
考题
单选题The principal purpose of adjustment of the magnetic compass is to eliminate（）as far as possible.A
variationB
compass errorC
deviationD
earth's magnetic force
考题
单选题What is the principal danger from the liquid in a half full tank onboard a vessel?（）A
Corrosion from the shifting liquidB
Rupturing of bulkheads from the shifting liquidC
Loss of stability from free surface effectD
Holing of the tank bottom from the weight of the shifting liquid
考题
单选题Of a kind of liquid is used to cool the diesel engine, it is invariably called （）A
lubricantB
coolantC
combustion productD
second refrigerant
考题
单选题The purpose of the low pressure cut-out switch is to （）.A
maintain liquid refrigerant at the suction of the compressorB
maintain a preset suction pressure to the compressorC
start and stop the compressor at preset operating pressuresD
operate at minimum efficiency
考题
单选题If liquid refrigerant accidentally comes in contact with the eyes, （） immediately.A
rub the eyesB
irritate the eyesC
wash the eyes with a heavy boric acid solutionD
obtain medical help
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
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