The diesel engine exhaust gas bypass, as fitted with some waste heat boilers, is installed to ()
A . prevent engine back pressure at heavy loads
B . increase total engine efficiency at low loads
C . prevent boiler corrosion at low engine loads
D . improve engine fuel consumption at any load
相似题目
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The color of the exhaust from a diesel engine should be ()
A . clear
B . hazy light brown
C . hazy light blue
D . hazy light grey
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During the valve overlap period, the exhaust pressure of a turbochargers, four-stroke/cycle diesel engine must be less than the intake manifold pressure to ensure ()
A . effective cylinder scavenging and cooling
B . constant pressure from the turbochargers
C . cooler operation of the exhaust system
D . effective constant pressure for turbocharger operatio
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If a diesel engines exhaust temperature is abnormally high, the cause could be()
A . too light of a load
B . injection timing is too early
C . overloading of the engine
D . too low of a compression ratio
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A two-stroke diesel engine exhaust temperature will be lower than a four-stroke diesel engine of the same displacement because the () (1) MEP is lower and the scavenging air is cooling the exhaust gases (2) valve overlap in a four-stroke
A . (1) only is correct
B . (2) only is correct
C . both (1) and (2) are correct
D . Neither (1) or (2) are correct
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Exhaust gases are generally removed from the cylinders of a two-stroke/cycle diesel engine by()
A . natural aspiration
B . masked intake valves
C . air cells
D . scavenging air
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The exhaust gases in a supercharged two-stroke/cycle diesel engine are expelled from the cylinder by ()
A . pumping action of the piston
B . pressure of the fuel charge
C . vacuum developed in the manifold
D . pressure of the fresh air charge
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A diesel engine is warmed up and white vapor is in the exhaust,this could indicate ()
A . excessive cylinder lubrication
B . a lugging engine
C . a leaking cylinder liner
D . overloading of one cylinder
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One of the purposes for water cooling the exhaust manifold in marine diesel engine is to ()
A . reduce lube oil temperature
B . raise exhaust temperature reduce
C . excessive heating of engine room
D . reduce load on cooling water pum
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A two-stroke diesel engine exhaust temperature will be lower than a four-stroke diesel engine of the same displacement because the () (1) scavenging air is cooling the exhaust gases (2) exhaust cycle time is longer
A . (1) only
B . (2) only
C . both (1) and (2)
D . neither (1) nor (2)
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A water jacket is placed around the exhaust manifolds of propulsion diesel engines to()
A . reduce heat radiation to the engine room
B . aid in preventing turbocharger overheating
C . condense and drain moisture from exhaust gases
D . dampen exhaust gas pulsations in the manifold
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The working cycle of a four-stroke diesel engine consists of four events:() (1) compression (2) expansion (3) exhaust (4) suctionThe correct sequence is
A . (4)-(2)-(3)-(1)
B . (4)-(3)-(1)-(2)
C . (4)-(3)-(2)-(1)
D . (4)-(1)-(2)-(3)
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The satisfactory operation of diesel engine exhaust valves usually depends on()
A . the proper back pressure
B . the cooling water temperature
C . correct timing and proper seating
D . accurate metering and the exhaust temperature
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The opening of an exhaust valve on a modem, large, low-speed, main propulsion diesel engine may be actuated by ().
A . direct action of cam shaft
B . compressed air pressure
C . hydraulic “push rods”
D . direct action of the main piston moving dow
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How would the exhaust of a properly operating diesel engine appear?().
A . Light blue haze
B . Light brown haze
C . Light gray haze
D . Perfectly clear
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In a diesel engine exhaust system, the cooling of the exhaust gases below their dew point, will result in ()
A . increased engine back pressure
B . sulfuric acid corrosion
C . surface pitting of the turbocharger
D . moisture impingement on the turbocharger compressor blade
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For an ordinary four-stroke diesel engine the exhaust valves close ().
A . after TDC
B . before TDC
C . after BDC
D . before BDC
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Forcing the exhaust gases form the cylinder of an operating diesel engine with the aid of a blower is known as ()
A . scavenging
B . forced draft
C . turbo-charging
D . aspiratio
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In a diesel engine, exhaust valves open before the intake ports are uncovered to () Ⅰ.reduce pumping losses Ⅱ.reduce back pressure
A . Ⅰonly
B . Ⅱonly
C . bothⅠand Ⅱ
D . neitherⅠnor Ⅱ
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The most common instrument used to measure diesel engine exhaust pressure is the ()
A . pyrometer
B . bourdon gauge
C . pneumercator
D . manometer
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Diesel engine mufflers or silencers reduce the engine exhaust noise by ()
A . passing the exhaust through long head pipes
B . diffusing exhaust vibrations through activated carbon baffles
C . increasing the exhaust gas velocity
D . reducing the exhaust gas velocity
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The operating diesel generators will have their exhaust temperatures, cooling water and lubricating oil temperatures and pressures () in much the same way as for the main engine.
A . to be kept
B . logged
C . changed
D . has remained
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In a two-stroke/cycle diesel engine, the exhaust gases are expelled from the cylinder by the()
A . exhaust manifold
B . valve bridge
C . pressure of the fresh air charge
D . valve adjusting gear
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A diesel engine experiences a sudden loss in speed, accompanied by black exhaust smoke, with the fuel rack at maximum, and speed remaining below normal the probable()
A . engine overload
B . leaky valves
C . stuck or broken piston rings
D . low air injection pressure
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The four strokes of a four-stroke diesel engine according to their sequence are :suction,compression,expansion and exhaust.()
此题为判断题(对,错)。