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单选题
The temperature differential occurring between the inlet temperature of the fluid to be cooled and the outlet temperature of the cooling medium in a shell-and-tube heat exchanger is greatest in which of the flow designs listed?（）
A
Cross
B
Parallel
C
Counter
D
Circular
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If the exhaust gas temperature of the incinerator is too high, or if sparks are developed, What should you do?
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第二组The only attention that heat exchanger should require is to ensure that the heat transfer surfaces remain substantially clean and the flow passages generally clear of obstruction. Indication that undue fouling is occurring is given by a progressive increase in the temperature difference between the two fluids, over a period of time, usually accompanied by a noticeable rise in pressure loss at a given flow.Fouling on the sea-water side is the most usual cause of deterioration in performance. The method of cleaning the sea water-side surfaces depends on the type of heat exchanger. With shell-and-tube heat exchangers, the removal of the header covers or, m the case of the smaller heat exchangers, the headers themselves, will provide access to the tubes. Obstructions, dirt, scale etc., can then be removed, using the tools provided by the heat exchanger manufacturer. Flushing through with fresh water is recommended before a heat exchanger is returned to service. In some applications, such as piston oil cooling, progressive fouling may take place on the outside of the tubes. Most manufactures recommend a chemical flushing pr6cess to remove this in situ~ without dismantling the heat exchanger.Plate heat exchangers may be cleaned by unclamping the stack of plates and mechanically cleaning the surface of each plate as recommended by the manufacturers. The plate seals may require replacement from time to time and here the manufacturers instructions should be closely followedBy which of the following indication, can we conclude that the lube oil-sea water heat exchanger is unduly fouled?A.the heat exchanger lube oil inlet temperature loweringB.the heat exchanger sea-water outlet pressure riseC.the heat exchanger temperature difference between lube oil and sea water increasingD.the heat exchanger pressure difference between sea water inlet and outlet decreasing
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根据移动基站验收规范，在OMT定义的外告警，Inlet（ID）Class8所对应的告警为（）。A、THUNDERBOLT ALARMB、FIRE ALARMC、TEMPERATURE ALARMD、HUMIDITY ALARM
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Which of the following BEST describes the difference between differential and incremental backups？（）A、 An incremental backup requires fewer tapes for restoration than a differential backup. B、 A differential backup tape takes less time than an incremental backup tape.C、 A differential backup requires fewer tapes for restoration than an incremental backup.D、 An incremental backup tape costs less than a differential backup tape.
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单选题The purpose of an after-cooler is to（）A
reduce the turbocharger operating temperatureB
increase the pressure of the inlet airC
increase the density of the inter airD
reduce the blower operating temperature
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单选题Which of the following statements is not true concerning symptom of a fire in the scavenge air box?（）A
an increase in the exhaust temperature of the affected cylinderB
the turbocharger may surgeC
the explosion pressure in all cylinders will rise violentlyD
smoke from the turbocharger air inlet filter will be seen
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单选题An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by （）.A
restriction in refrigerant pipingB
air and non-condensable gases in the condenserC
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flooding back of liquid refrigerant from the evaporator
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单选题The dew point temperature is（）.A
always higher than the air temperatureB
always lower than the air temperatureC
equal to the difference between the wet and dry bulb temperaturesD
the temperature at which the air is saturated with water vapor
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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An increased differential between the inlet and outlet of a strainer usually indicates the strainer is （）A
holedB
fouledC
cleanD
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单选题Which of the following BEST describes the difference between differential and incremental backups？（）A
An incremental backup requires fewer tapes for restoration than a differential backup. B
A differential backup tape takes less time than an incremental backup tape.C
A differential backup requires fewer tapes for restoration than an incremental backup.D
An incremental backup tape costs less than a differential backup tape.
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单选题（）can cause oil flow from water outlet of a separator.A
Oil inlet valve opening too quicklyB
Oil temperature too highC
Diameter of gravity disc too smallD
Viscosity of oil too low
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单选题The temperature difference between the inlet and outlet temperature of the lube oil cooler in the lubricating system for the diesel engine is generally between （）.A
8-10℃B
10-12℃C
10-15℃D
10-20℃
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单选题An after-cooler installed between the turbocharger and the cylinder air inlet （）A
increases the density of the airB
decrease the density of the airC
increases the specific heat of the airD
decreases the specific heat of the exhaust
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单选题An increased pressure differential between the inlet and outlet of a strainer usually indicates the strainer is （）A
holedB
fouledC
cleanD
dry
考题
单选题The greater the pressure difference between a high and a low pressure center，the（）.A
dryer the air mass will beB
cooler the temperature will beC
greater the force of the wind will beD
warmer the temperature will be
考题
单选题In an engine with air inlet valve and exhaust valve on its cylinder heads the fresh air will enter into the cylinder （） and the gases exhaust （）, there being an adequate overlap between the inlet opening and the exhaust closing.A
downwards；upwardsB
upwards；downwardsC
downwards；downwardsD
upwards；upwards
考题
单选题Which condition indicates the air side fouling of an after-cooler on a turbocharged diesel engine?（）A
An increased air temperature differential between the cooler inlet and outletB
A decrease in the air pressure differential across the coolerC
Excessive condensate forming in the air boxD
A decrease in the air temperature differential between the cooler inlet and outlet
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单选题The principle of separation by which all commercially available oily water separators function is （） differential between oil and water.A
the temperatureB
the viscosityC
the gravityD
the size
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单选题（）is a type of fog occurring close to the sea surface when the air is dry and cold-probably at least 9℃ below the sea surface temperature.A
MIXING FOGB
ADVECTION FOGC
RADIATION FOGD
ARCTIC SEA SMOKE
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单选题On what do you depend having the air cooler of main engine chemically washed?（）A
increased air pressure differenced before and aft air coolerB
reduced exhaust temperature in all cylindersC
reduced temperature difference between water inlet and outletD
both A and C
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单选题Movement of the diaphragm or bellows is （） by a linkage to a needle or pointer display to indicate the differential pressure between two sides of the diaphragm or bellows.A
measuredB
recordedC
transferredD
controlled
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单选题An electric heater built into some smaller diesel engines is used to （）.A
raise lube oil viscosity for easier starting in cold weatherB
increase air inlet temperatureC
increase compression ratioD
increase jacket water temperature for easier starting in cold weather
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单选题Which of the following statements describes the relationship between flash point and ignition temperature?（）A
Both are higher than normal burning temperaturesB
The flash point is always higherC
The ignition temperature is always higherD
They are not necessarily related
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单选题The area of strong westerly winds occurring between 40°S and 60°S latitude is called the（）.A
polar easterliesB
prevailing westerliesC
roaring fortiesD
jet streams
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