high temperatures
low temperatures
wet
dirty
第1题:
If the engine does start on air, but combustion does not immediately begin, the cause may be _____.
A.failure of the fuel pumps
B.starting air pressure too low
C.stop valve in air line closed
D.the turning gear still engaged
第2题:
How does combustion air enter the cylinder of a two-cycle diesel engine ? Through _______.
A.Cylinder head valves
B.Ports
C.Turbo chargers
D.Bleeder valves
第3题:
第一组: The Wartsila 50DF operates on the lean-bum principle: the mixture of air and gas in the cylinder has more air than is needed for complete combustion. Lean combustion reduces peak temperatures and therefore NOx emissions. Efficiency is increased and higher output is reached while avoiding knocking. Combustion of the lean air-fuel mixture is initiated by injecting a small amount of LFO (pilot fuel) into the cylinder. The pilot fuel is ignited in a conventional diesel process, providing a high-energy ignition source for the main engine. To obtain the best efficiency and lowest emissions, every cylinder is individually controlled to ensure operation at the correct air-fuel ratio and with the correct amount and timing of pilot fuel rejection. Wartsila has developed a special electronic control system to cope with the demanding task of controlling the combustion in each cylinder, and to ensure optimal performance in terms of efficiency and emissions under all conditions by keeping each cylinder within the operating window. Stable and well-controlled combustion also contributes to less mechanical and thermal load on the engine components. Current stringent emission regulations demand the reduction of NOx emissions. In an internal combustion engine this means controlling peak temperature and residence time, which are the main parameters governing NOx formations. In the Wartsila 50DF engine, the air-fuel ratio is very high (typically 2.2). Since the same specific heat quantity released by combustion is used to heat up a larger mass of air, the maximum temperature and consequently NOx formation are lower. The mixture is uniform. throughout the cylinder since the fuel and air are premixed before introduction into the cylinders, which helps to avoid local NOx formation points within the cylinder. Benefiting from this unique feature, NOx emissions from the Wartsila 50DF are extremely and comply with the most stringent existing legislation.
What is the combustion feature of the Wartsila 50DF?
A.Lean air in the cylinder
B.Excessive fuel in the cylinder
C.Excessive air in the cylinder
D.Spark ignition
第4题:
a cracked liner
burning lube oil
an overloaded engine
insufficient combustion air
第5题:
exhaust gas pressure
exhaust gas temperature
speed
load
第6题:
题干材料: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.
问题:Which of the following devices should be taken to maintain ambient conditions of the boiler and machinery space?
A.air compressor
B.air cooler
C.air-conditioning plant
D.mechanical ventilation plant
In a motor vessel, the air quantity which the engine room need is_______ of the requirements of the engines.A.less than 25-50%
B.more than 125-150%
C.more than 25-50%
D.less than 125-150%
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
At the middle pressure and large air quantity,_________ is more suitable.A.an axial flow fan
B.a radial flow blower
C.a centrifugal fan
D.an auxiliary blower
请帮忙给出每个问题的正确答案和分析,谢谢!
第7题:
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 compressor
B.air cooler
C.air-conditioning plant
D.mechanical ventilation plant
第8题:
Which of the following problems should be taken when cleaning the air filter on a diesel engine equipped with a turbocharger? .
A.Reduce engine speed to idle before removing the filter
B.Soak the dirty filter in kerosene only
C.Blow out the air inlet with compressed air
D.Cover the air inlet after removing the filter
第9题:
water in the fuel
insufficient fuel for combustion
clogged air intake passages
burning lubricating oil
第10题:
injection lag
ignition delay
compression
turbulence lag