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单选题
The expansion valve on a Freon system controls the ().
A
superheat of the gas leaving the compressor
B
back pressure in the evaporator
C
temperature of the icebox
D
superheat of the gas leaving the evaporator
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The expansion valve used in a refrigeration system regulates theA.superheat of the gas leaving the compressorB.back pressure in the evaporatorC.temperature in the refrigerated spaceD.degree of superheat of the gas leaving the evaporator
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A thermostatic expansion valve is properly controlling evaporator superheat. Adjusting this valve to lower the superheat will result in a/anA.evaporator pressure decreaseB.evaporator coil over-feedC.evaporator capacity increaseD.expansion valve diaphragm rupture
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Which of the problems listed could cause erosion of the expansion valve disks and seats?A.Overcharging the system with refrigerantB.Faulty compressor suction valveC.Failure of the high pressure cutoutD.Flash gas formed in the liquid line
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单选题The thermal expansion valve controls the amount of refrigerant that is allowed to flow to the ().A
compressorB
cooling coilsC
condenserD
receiver
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单选题If a refrigeration system compressor crankcase is sweating, you should ().A
add refrigerant to the systemB
adjust the thermal expansion valve to the proper settingC
adjust the float valve to the proper holding pressureD
open the hand expansion valve
考题
单选题In a centrifugal Freon refrigeration system, the overall capacity of the system is increased by()A
opening more bypass linesB
opening additional expansion valvesC
adding refrigerantD
speeding up the machine
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单选题If the operating element of a thermostatic valve installed in a diesel engine cooling system malfunctions, it may result in ()A
a low level in the engine expansion tankB
excessively high coolant pressureC
improper temperaturesD
malfunctioning of the jacket water heater
考题
单选题A ruptured diaphragm in a thermostatic expansion valve will cause the valve to ().A
openB
closeC
remain in its positionD
flood the evaporator with refrigerant
考题
单选题The scale trap is located between the ()A
king valve and the expansion valveB
solenoid valve and expansion valveC
evaporator and receiverD
compressor and evaporator
考题
单选题What is the function of thermostatic expansion valve in a compression refrigeration system?()A
nonexistentB
for controlling pressureC
for controlling superheatD
for controlling the solenoid valve
考题
单选题When a refrigeration compressor is in the ‘off’ cycle, the thermal expansion valve will().A
always be wide open when the compressor restartsB
continue to operate as if the system were in operationC
remain open until evaporator pressure equalizes, then close until the compressor restartsD
always be completely closed until the compressor restarts
考题
单选题Which of the following statements is correct concerning a typical shipboard multi-coil refrigeration system?()A
The liquid receiver functions to collect and remove non-condensable gasesB
A thermostatic expansion valve is used to control refrigerated space temperatureC
Refrigerant temperature in an evaporator is directly related to refrigerant pressureD
Dehydrators must be used continuously in a refrigeration system
考题
单选题What separate the high pressure side from the low pressure side in a refrigeration system?()A
Condenser and thermal expansion valveB
King and solenoid valvesC
Compressor and thermal expansion valveD
Condenser and solenoid valve
考题
单选题A thermostatic expansion valve is properly controlling evaporator superheatAdjusting this valve to lower the superheat will result in a/an ().A
evaporator pressure decreaseB
evaporator coil over-feedC
evaporator capacity increaseD
expansion valve diaphragm rupture
考题
单选题Moisture in a refrigeration system can cause ().A
freezing the expansion valve closedB
corrosion of system pipingC
improper temperature regulationD
all of the above
考题
单选题When the heat load begins to increase, the needle valve of an expansion valve will()A
move in an opening directionB
move in a closing directionC
either open or closeD
not move at all
考题
单选题A solenoid valve used in a refrigeration system should be installed ().A
with the axis of the solenoid horizontal, sensing temperature of the box, and upstream of the thermal expansion valveB
upright, sensing temperature of the box, and upstream of the thermal expansion valveC
upright, sensing temperature of the box, and downstream of the thermal expansion valveD
upright, sensing heat of the tail coil, and upstream of the thermal expansion valve
考题
单选题A cracked diaphragm in a thermostatic expansion valve will cause the valve to ().A
return to a neutral positionB
flood the evaporatorC
openD
close
考题
单选题When the refrigeration demand is small,()A
the expansion valve will move toward the wide open positionB
the expansion valve will move toward the closing positionC
the feeler bulb will conveys the high temperatureD
the superheat degree will raise
考题
单选题After passing through the expansion valve the refrigerant should be in the state of ().A
vaporB
liquidC
solidD
None of the above is tree
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To correct the condition of slugging and flooding back in a refrigeration system, it may be necessary to ().A
re-adjust the discharge pressureB
clean the expansion valve screenC
add refrigerantD
adjust the expansion valve
考题
单选题The low pressure side of a refrigeration system is considered to exist from the ().A
expansion valve to the compressorB
receiver to the expansion coilC
expansion valve to the evaporatorD
condenser to the expansion valve
考题
单选题The direct acting mechanical governor used with some small diesel engines, controls fuel flow to the engine by()A
governor flyweight action on a pilot valve which controls fuel injectionB
governor flyweight motion acting on fuel controls through suitable linkageC
positioning a butterfly valve in the fuel delivery system positioningD
a servomotor piston attached to the fuel controls
考题
单选题Which of the listed components is considered to separate the high pressure side of a refrigeration cycle from the low pressure side of the cycle?()A
The condenser and the expansion valveB
The king valve and the solenoid valveC
The compressor and the expansion valveD
The condenser and the solenoid valve
考题
单选题A pressure drop in the liquid line of a refrigeration system may cause()A
the solenoid valve to seizeB
the compressor to huntC
flash gas to form in the liquid lineD
the expansion valve to freeze open
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单选题The jacket water temperature in a diesel engine closed freshwater cooling system is normally controlled by ()A
regulating the level of corrosion inhibitor in the primary cooling systemB
the level of the freshwater expansion tankC
varying the engine load to meet temperature requirementsD
the operation of the thermostatic valve
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