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单选题
Sludge may form in the crankcase of an air conditioning compressor as a result of （）.
A
bubbling refrigerant
B
overheating and oxidation
C
lowered operating temperatures
D
reducing the cloud or flash point
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Crankcase explosions in propulsion diesel engines result from ____.A.the splashing of lubrication oil by the crankshaftB.the dilution of crankcase oil with particles of combustionC.broken fuel lines spraying oil on the crankcaseD.the ignition of unburned fuel and air in the crankcase
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考题
Sludge may be formed in the oil in the crankcase of a reciprocating air conditioning compressor as a result of ______.A.refrigerant bubbles in the lube oilB.refrigerant reducing the lube oil viscosityC.oxidation(氧化) of the lube oil from overheatingD.reducing the floc or cloud point of the oil
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In an air conditioning system, moisture is removed from the air by ______.A.filtersB.separatorsC.ducted trapsD.dehumidifiers
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Sludge may form in the crankcase of an air conditioning compressor as a result of ______.A.bubbling refrigerantB.overheating and oxidationC.lowered operating temperaturesD.reducing the cloud or floc point
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According to this passage, which of the following statements is true?A.In boiler and machinery spaces, there is the air conditioning.B.In the boiler rooms the requirement of air volume should meet 25-50% of combustion requirement.C.To maintain the comfort zone in the separate control room the air conditioning plant should be fitted.D.The comfort conditions can be maintained in the engine room all the time.
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Due to the large amount of heat picked up by the air in boiler and engine rooms, it would be impracticable to maintain ambient conditions within the comfort zone by air conditioning or any other means. The normal practice is to provide copious mechanical ventilation; in boiler rooms, the quantity is equated to the combustion requirements, while in a motor ship engine room the supply may be 25-50% in excess of the requirements of the engines.The axial flow fan is particularly suited to handle these large air volumes at the moderate pressures required, while of course the “straight-through” flow feature places it at an advantage over the centrifugal fan.The increasing adoption of automation, with the provision of a separate control room makes less significant the fact that comfort conditions cannot be maintained in the engine room all the time. Which of the following devices should be taken to maintain ambient conditions of the boiler and machinery space?A.air compressorB.air coolerC.air-conditioning plantD.mechanical ventilation plant
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单选题Due to the large amount of heat picked up by the air in boiler and engine rooms, it would be （） to maintain ambient conditions within the comfort zone by air conditioning.A
possibleB
necessaryC
practicableD
impracticable
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单选题If plastic film insulation becomes damaged in air conditioning system, （） may form within the film.A
evaporationB
condensationC
liquefiesD
vaporization
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单选题In an air conditioning system, moisture is removed from the air by（）A
filersB
separatorsC
ducted trapsD
dehumidifiers
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单选题A re-heater in an air conditioning system functions to （）.A
control inlet air temperatureB
control inlet air volumeC
maintain relative humidity at 15%D
restore conditioned air temperature to a comfortable level
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单选题A re-heater, as used in an air conditioning system, is designed to control the （）A
chilled water temperatureB
dew point temperatureC
primary air temperatureD
dry bulb temperature
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单选题What function is provided by the crankcase ventilation system on some diesel engines?（）A
Increases the sludge forming tendency of lube oilB
Prevents the accumulation of combustible gasesC
Improves lube oil coolingD
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单选题Air conditioning is the process of treating air to control （） its temperature, humidity, cleanliness and distribution to meet the comfort requirements of the occupants of the conditioned space.A
instantaneousB
instantaneouslyC
simultaneousD
simultaneously
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单选题In reference to air conditioning, when air attains the maximum amount of moisture it can hold at a specific temperature, it is said to be （）.A
superheatedB
saturatedC
condensedD
convected
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单选题Most air conditioning units have （） for adjusting the ratio of recirculated fresh airCare must be taken not to reduce the fresh air so that stuffiness or smells arise.A
catch platesB
dampersC
regulating valvesD
fans
考题
单选题Crankcase explosions in propulsion diesel result from（）A
the splashing of lubrication oil by the crankshaftB
the dilution of crankcase oil with particles of combustionC
broken fuel lines spraying oil on the crankcaseD
the ignition of unburned fuel and air in the crankcase
考题
单选题With ducted air conditioning systems, the modern tendency is to use（）A
central air conditioning systemB
high velocity systemC
low velocity systemD
single duct system
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单选题If a crankcase explosion occurs in a diesel engine, you should stop the engine and（）A
immediately open all crankcase relief portsB
increase crankcase exhauster speed to draw cool air into the engineC
allow the engine to cool naturallyD
increase crank case scavenge air to remove unburned gases
考题
单选题Sludge may form in the lubricating oil crankcase of a reciprocating air conditioning compressor as a result of （）.A
wax precipitation in the lube oilB
contamination by dust, scale, or moistureC
refrigerant bubbles in the lube oilD
refrigerant reducing the lube oil viscosity
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单选题To prevent the unnecessary loading of an air conditioning system while maintaining the designed dry bulb temperature and relative humidity in an air conditioning system, you should （）A
admit only enough fresh outside air to provide proper ventilationB
reduce the air reheating system loadC
lower the compressor head pressureD
operate the purge recovery unit continuously
考题
单选题When fuel enters the crankcase of a diesel engine, it （）A
dilutes the lube oil and reduces its viscosityB
forms sulfuric acid in the lube oilC
causes pitting and failure of the bearingsD
causes sludge deposits on valve stems
考题
单选题Sludge may be formed in the oil in the crankcase of a reciprocating air conditioning compressor as a result of （）A
refrigerant bubbles in the lube oilB
refrigerant reducing the lube oil viscosityC
oxidation of the lube oil from overheatingD
reducing the floc or cloud point of the oil
考题
单选题Routine maintenance on a Central Control Room hermetically sealed air conditioning unit should include （）A
changing the air filterB
recharging the systemC
changing compressor lubricantD
renewing container vacuum
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单选题The main distribution duct in an air conditioning system which contains the cooling coils and filters is called the（）A
manifoldB
condenserC
chamberD
plenum
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单选题The quantity of cooled air delivered by an air conditioning unit should （） the sum of the quantity of air re-circulated to the unit and the quantity mechanically exhausted.A
balanceB
not balanceC
be more thanD
be less than
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