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单选题
Hot gas defrosting uses the hot gas from （） to defrost the evaporator.
A
starting air bottles
B
diesel engines
C
boilers
D
refrigeration compressors
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共用题干
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考题
Which of the following displays uses gas as a method for projecting an image?（）A、CRTB、PlasmaC、LEDD、LCD
考题
单选题The device, which is installed in the compressor suction line to prevent liquid from entering the compressor when hot gas defrosting, is called a（）A
re-evaporatorB
receiverC
dehydratorD
solenoid
考题
单选题Intake air flow from a diesel engine turbocharger is directly proportional to engine（）A
exhaust gas pressureB
exhaust gas temperatureC
speedD
load
考题
单选题The fresh air intake of the inert gas system（）.A
prevents the flue gas from falling below 3% content of oxygenB
allows the inert gas piping to be used for gas freeing the tanksC
opens when there is excessive vacuum on the deck water sealD
enables outside air to mix with and cool hot flue gasses
考题
单选题The hot expanding gas rotates the blades of the exhaust turbine, thus giving out large part of its power, which drives （）.A
the oil separatorB
the fresh water generatorC
the compressorD
fire pump
考题
单选题If a large difference exists between the compressor discharge pressure and the pressure corresponding to the existing condensing temperature in a refrigeration system, you should（）.A
increase the flow of the cooling water through the condenserB
adjust the high pressure cutout to maintain the desired pressureC
open the hot gas bypass temporarily to reduce capacityD
purge non-condensable gases to reduce the excess pressure
考题
单选题In the condenser, the hot, high pressure refrigerant gas is cooled by the sea water and becomes（）.A
fresh waterB
vaporC
mixtureD
liquid
考题
单选题Hot gas bypass is one of the methods used to （）A
relieve excessive compressor head pressureB
produce flash gas at the expansion valveC
reduce flooding of the receiver at low loadD
defrost the evaporator coils
考题
单选题Some chloronated flourocarbon refrigerants may decompose into a toxic irritating gas if it is （）.A
stored at temperatures below 60 degrees FahrenheitB
charged into a system having copper fittingsC
allowed to mix with compressor oilD
exposed to an open flame or hot surface
考题
单选题The term diesel engine scavenging means（）A
delivering more air into the cylinder than it would normally receive during an ordinary charging processB
forcing the products of combustion out of the cylinder with the fresh air chargeC
collecting the air charge at the cleanerD
combustion and expansion of hot gas
考题
单选题A refrigeration unit will tend to short cycle when operating （）.A
under heavy loadsB
during hot gas defrostC
under light loadsD
during starting conditions
考题
单选题A dry-type spark arrestor removes sparks from a diesel engine exhaust by（）A
increasing the linear velocity of the exhaust gasesB
changing directions of exhaust gas flowC
decreasing the temperature of the exhaust gasesD
accelerating the exhaust gas through a reduced size orifice
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Directional intake ports in diesel engines are used to （）.A
reduce air charge turbulenceB
induce air swirlC
deflect hot combustion gas away from the valvesD
oppose the effects of piston induced squish
考题
单选题Which method is used to supply inert gas from a flue gas system to the cargo tanks?（）A
Exhaust gas pressure from the stackB
High capacity fanC
Inert gas compressorD
Natural aspiration
考题
单选题The purpose of the deck seal in an inert gas system is to prevent（）.A
flammable vapors from entering machinery spaceB
flue gas escaping to atmosphereC
inert gas escaping to atmosphereD
air entering inert gas system
考题
单选题Gas turbines differ from steam turbines in that （）.A
steam rather than gas is used to turn a shaftB
vapor rather than gas is used to turn a shaftC
the former uses gas to turn a shaftD
the latter uses gas to turn a shaft
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