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单选题
The temperature at which the air is saturated with water vapor and below which condensation of water vapor will occur is referred to as the（）.
A
precipitation point
B
vapor point
C
dew point
D
absolute humidity
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更多 “单选题The temperature at which the air is saturated with water vapor and below which condensation of water vapor will occur is referred to as the（）.A precipitation pointB vapor pointC dew pointD absolute humidity” 相关考题
考题
Which of the processes listed would be the most satisfactory method to use to lower the humidity of the air being circulated by an air conditioning system?A.Cooling the air to a temperature just above dew pointB.Heating the air to a point at which moisture will boil off ,then re-cooling itC.Cooling the air to a point below dew point, then reheating itD.Heating the air and then cooling it to a point below dew point
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The dew point is reached when the ______.A.temperature of the air equals the temperature of the seawaterB.atmospheric pressure is 14.7 lbs. per square inchC.relative humidity reaches 50%D.air becomes saturated with water vapor
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The moisture equilibrium chart can be used to determine the ______．A.Absolute moisture content of the air surrounding a hygroscopic cargo when moisture equilibrium existsB.Dew point temperature that the air surrounding a hygroscopic commodity will have when in moisture equilibrium with that commodityC.Enthalpy of the air surrounding a hydroscopic cargo which is in moisture equilibrium with the cargoD.Temperature at which moisture equilibrium will occur in a cargo hold containing a hygroscopic cargo
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While working in the server room a technician notices that water is forming on the walls of the serverroom. Which of the following is the BEST course of action to correct the problem？（）A、 Contact facilities staff to adjust the humidity levels.B、 Leave the temperature the same， after time it will evaporate on its own.C、 Lower the temperature， the cold air will help the water evaporate.D、 Contact facilities staff to raise the temperature of the room.
考题
单选题Water evaporates or steam condenses at the saturation temperature, which depends upon the pressure, the higher the pressure （） the saturation temperature.A
the moreB
the higherC
the lowerD
the highest
考题
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
考题
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While working in the server room a technician notices that water is forming on the walls of the serverroom. Which of the following is the BEST course of action to correct the problem？（）A
Contact facilities staff to adjust the humidity levels.B
Leave the temperature the same， after time it will evaporate on its own.C
Lower the temperature， the cold air will help the water evaporate.D
Contact facilities staff to raise the temperature of the room.
考题
单选题For the proper control of the air temperature in an air conditioning system using chilled water circulation, which of the listed conditions should remain constant regardless of load changes?（）A
Chilled water system supply temperatureB
Chilled water system return temperatureC
Compressor discharge temperatureD
Compressor suction pressure
考题
单选题请阅读 Passage 1，完成第 21~25小题。Passage 1These days，many large city buildings are equipped with their own air-conditioning systems.These systems help keep the buildings cool，but they can also damage the environment.Since they use a lot of electricity，for instance，they contribute indirectly to global warming.In addition，the water that flows through the systems is often cooled using chemicals called chlorofluorocarbons，or CFCs，that are believed to damage the Earth's ozone layer.Recently，though，a system has been built in the city of Toronto，Canada，that cools buildings with little damage to the environment. In the traditional air-conditioning systems found in most large buildings，water is pumped through the building in a continuous cycle.The water is first cooled to a temperature of 4℃ in machines called chillers.It is then sent to individual units that cool the air in each room.As the water flows through the building，it gradually becomes warmer.Finally，it reaches the roof ，where it is left to cool down naturally in a water tower.After that it is returned to the chillers，where the cycle begins again.Toronto lies on the shore of Lake Ontario，one of North America's Great Lakes，and the new system makes use of cold water taken from about 80 meters below the surface of the lake.At this depth，the water in the lake remains at 4℃ all year round.This is exactly the temperature to which the water in air-conditioning systems is cooled.However，the water from the lake is not pumped directly into the air-conditioning systems.Instead，it is used to cool the water that is already inside the air-conditioning systems.After that，the lake water is added to the city's ordinary water supply.Enwave，the company that developed this deep-lake cooling system，says that it uses 75 percent less energy than traditional air conditioning.And since no CFCs are used，no damage can be caused to the ozone layer.Not every city is located next to a large lake，but experts believe that systems like the one being used in Toronto could be built elsewhere by using other natural sources of cold water.What is the function of the chillers in a traditional air-conditioning system?A
They pump the air continuously to the units in each room.B
They lower the temperature of the water in the system.C
They help the water cool down naturally on the roof .D
They gradually clean the water as it flows through the building.
考题
单选题The dew point is reached when the（）.A
temperature of the air equals the temperature of the seawaterB
atmospheric pressure is 14.7 lbs. per square inchC
relative humidity reaches 50%D
air becomes saturated with water vapor
考题
单选题As the air passes through the charge air cooler, its temperature may be reduced and moisture condensed, with the condensate in danger of being carried into the engineSo a water separator should be mounted beneath the bottom part of the engine inlet manifoldA water separator is used in order to （）.A
keep the air from being carried into the engineB
keep the moisture from being condensedC
keep the danger from being carded into the engineD
take away the condensate from the air
考题
单选题The temperature at which water vapor in the atmosphere begins to condense is called the （）.A
dew point temperatureB
condensation temperatureC
psychometric temperatureD
absolute humidity temperature
考题
单选题Low cylinder compression pressure and a high exhaust temperature may indicate （）A
early fuel injection timingB
leaking valvesC
a continuously open scavenge air portD
low cooling water temperature
考题
单选题Fog forms when the air（）.A
is 50% water saturatedB
is 90% water saturatedC
temperature is greater than the dew point temperatureD
temperature is equal to，or below the dew point temperature
考题
单选题Which of the following problems can cause an above normal air temperature to develop in the intake manifold of a turbocharged and after-cooled diesel engine?（）A
Faulty turbocharger turbine diffuser ringB
Faulty turbocharger compressor ringC
Insufficient cooling water flowD
Clogged air intake filters
考题
单选题The amount of moisture in a given sample of air, when compared with the amount of moisture the air could hold if totally saturated at the existing temperature of the sample, is called （）.A
absolute humidityB
specific humidityC
effective humidityD
relative humidity
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
考题
单选题Which of the following methods is normally used to control the temperature of air distributed from individual cooling coils in an air conditioning system using a chilled water circulation system?（）A
A room thermostat activates an electric heater at each individual chilled air outlet when necessaryB
Varying the number of passes the air makes across the coilsC
Varying the temperature of the water through the coilsD
Varying the quantity of water flowing through the coils
考题
单选题Which of the following conditions can cause below normal air pressure in the intake manifold of a turbocharged diesel engine?（）A
Excessive piston blow-by to the manifoldB
Insufficient cooling water flowC
Accumulated water in the air boxesD
Clogged air intake filters
考题
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
考题
单选题Which of the processes listed would be the most satisfactory method to use to lower the humidity of the air being circulated by an air conditioning system?（）A
Cooling the air to a temperature just above dew pointB
Heating the air to a point at which moisture will boil off ,then re-cooling itC
Cooling the air to a point below dew point, then reheating itD
Heating the air and then cooling it to a point below dew point
考题
单选题Which of following functions is not one of the functions of air conditioner?（）A
refreshing the airB
making person upsetC
adjusting the air humidityD
adjusting the air temperature
考题
单选题请阅读 Passage 1，完成第 21~25小题。Passage 1These days，many large city buildings are equipped with their own air-conditioning systems.These systems help keep the buildings cool，but they can also damage the environment.Since they use a lot of electricity，for instance，they contribute indirectly to global warming.In addition，the water that flows through the systems is often cooled using chemicals called chlorofluorocarbons，or CFCs，that are believed to damage the Earth's ozone layer.Recently，though，a system has been built in the city of Toronto，Canada，that cools buildings with little damage to the environment. In the traditional air-conditioning systems found in most large buildings，water is pumped through the building in a continuous cycle.The water is first cooled to a temperature of 4℃ in machines called chillers.It is then sent to individual units that cool the air in each room.As the water flows through the building，it gradually becomes warmer.Finally，it reaches the roof ，where it is left to cool down naturally in a water tower.After that it is returned to the chillers，where the cycle begins again.Toronto lies on the shore of Lake Ontario，one of North America's Great Lakes，and the new system makes use of cold water taken from about 80 meters below the surface of the lake.At this depth，the water in the lake remains at 4℃ all year round.This is exactly the temperature to which the water in air-conditioning systems is cooled.However，the water from the lake is not pumped directly into the air-conditioning systems.Instead，it is used to cool the water that is already inside the air-conditioning systems.After that，the lake water is added to the city's ordinary water supply.Enwave，the company that developed this deep-lake cooling system，says that it uses 75 percent less energy than traditional air conditioning.And since no CFCs are used，no damage can be caused to the ozone layer.Not every city is located next to a large lake，but experts believe that systems like the one being used in Toronto could be built elsewhere by using other natural sources of cold water.Which of the following is true?A
Enwave's system is said to work only in cities located near the Great Lakes.B
The water deep in Lake Ontario always remains at the same temperature.C
Experts warn that the use of CFCs in Enwave' s system will add to global warming.D
Toronto is now searching for new natural sources of water to use in its water supply.
考题
单选题Which of the following conditions may need to be reduced when operating a large, low speed, main propulsion, diesel engine at low loads?（）A
Injection pressuresB
Control air supply pressureC
Cooling water flow through after-coolersD
Lube oil temperature
考题
单选题A
To transport water to high places.B
To provide air conditioning.C
To fertilize the soil.D
To adjust the soil temperature.
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