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The effective temperature of air is dependent upon ______. I. relative humidity II. air velocity
A.I only
B.II only
C.Both I and II
D.Neither I nor II
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更多 “ The effective temperature of air is dependent upon ______. I. relative humidity II. air velocityA.I onlyB.II onlyC.Both I and IID.Neither I nor II ” 相关考题
考题
If air at 95°Cdry bulb temperature and 50%relative humidity is conditioned to 75°Cdry bulb temperature and 50%relative humidity, it is an example of()
A.cooling onlyB.cooling and humidifyingC.cooling and dehumidifyingD.adiabatic(绝热的)cooling
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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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As the temperature for an air mass decreases, the ______.A.absolute humidity increasesB.relative humidity increasesC.specific humidity increasesD.dew point rises
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As the temperature for a given mass of air increases, the ______.A.dew point increasesB.dew point decreasesC.relative humidity increasesD.relative humidity decreases
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Cloud formations are minimal when the ______.A.surface temperature and temperature aloft are equalB.surface temperature and temperature aloft differ greatlyC.barometric pressure is very lowD.relative humidity is very high
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Fog is likely to occur when there is little difference between the dew point and the ______.A.relative humidityB.air temperatureC.barometric pressureD.absolute humidity
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单选题The expression THE AIR IS SATURATED means（）.A
the relative humidity is 100%B
the vapor pressure is at its minimum for the prevailing temperatureC
precipitation has commencedD
cloud cover is 100%
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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Compared to a low pressure system，generally the air in a high is（）.A
warmer，less dense，and less stableB
cool，more dense，and drierC
muggy and cloudyD
extremely moist with high relative humidity
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问答题Practice 1 Heat loss by sweating depends on the fact that when a liquid evaporates, it absorbs an enormous quantity of heat from its surroundings. Therefore, when I am of sweat evaporate, a great deal of heat is absorbed from the surface of the body in contact with it. 1______ 2______ The first is the amount of movement of air surrounding the body. The second is the amount of water vapor in the air that surrounds the body. 3______ For this reason, sweat evaporates very rapidly on windy days, and the rate of heat loss by sweating is much more than on a still day. This accounts for the fact that hot still days are much less comfortable than hot windy days. In contrast, the sweat evaporates very rapidly on hot windy days, and cools the body quickly and effectively. 4______ When air is carrying the maximum amount of water vapor that it can hold, it is said to be 100% saturated with water vapor. The relative humidity of the air is said to be 100%. Under these conditions the air cannot carry any water, so no water can evaporate. When the relative humidity is high, therefore, sweat cannot evaporate. Instead, it forms large drops and runs off your skin without cooling you. 5______ It is obvious that under these conditions, evaporation will be much more rapid. Therefore, sweating will be much more effective as a method of losing heat from the body. On a hot dry day, sweat evaporates as soon as it is formed, and you feel reasonably cool even though the temperature of your environment is very high.[A] When the air is very dry and carries no water at all, the relative humidity is said to be 0%.[B] The second factor is the amount of water vapor in the air－the humidity.[C] Hot windy days are much more comfortable than hot still days.[D] This heat transfer occurs even if the environment is hotter than the body.[E] When air moves over the surface of water, the amount of evaporation is greatly increased.[F] You might expect the highest incidence of a heat stroke when the maximum temperature is 100 and humidity is 50%.[G] Two factors affect the rate of evaporation of sweat, and therefore the effectiveness of sweating as a method of cooling the body.
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单选题When air is at its dew point it is at its（）A
lowest absolute humidityB
lowest relative humidityC
highest absolute humidityD
highest relative humidity
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单选题Air conditioning is the process of treating air to control （） its temperature, humidity, cleanliness and distribution to meet the comfort requirements of the occupants of the conditioned space.A
instantaneousB
instantaneouslyC
simultaneousD
simultaneously
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单选题As the temperature of an air mass decreases，the（）.A
absolute humidity decreasesB
relative humidity increasesC
specific humidity decreasesD
dew point rises
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单选题Which instrument is used to measure the relative humidity of air?（）A
HydrometerB
HygrometerC
SpectrometerD
Barometer
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单选题If air at 95℃ dry bulb temperature and 50% relative humidity is conditioned to 75℃ dry bulb temperature and 50% relative humidity, it is an example of （）.A
cooling onlyB
cooling and humidifyingC
cooling and dehumidifyingD
adiabatic cooling
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A cargo hold has been determined to have a relative humidity of 80% and a dry bulb temperature of 80 ℃ and a dry bulb temperature of 85℃.When the hold is sealed and the dry bulb temperature decreases, the relative humidity in the space will （）A
decreaseB
increaseC
decrease to zeroD
remain unchanged
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单选题When comparing the air with 50% of relative humidity with the air with 100% of relative humidity, which one will hold more water?（）A
the formerB
the latterC
not for sureD
same each other
考题
单选题（） is the control of temperature and humidity in a space together with the circulation, filtering and refreshing of the air.A
RefrigerationB
Air conditioningC
VentilationD
Heating
考题
单选题To prevent the unnecessary loading of an air conditioning system while maintaining the designed dry bulb temperature and relative humidity in an air conditioning system, you should （）A
admit only enough fresh outside air to provide proper ventilationB
reduce the air reheating system loadC
lower the compressor head pressureD
operate the purge recovery unit continuously
考题
单选题Relative humidity is the percentage of water vapor that is in the air as compared to the maximum amount it can hold at（）.A
a specific barometric pressureB
a specific temperatureC
a specific wind speedD
any time
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单选题A lower thermostatic temperature setting will provide a desired degree of comfort in a room where （）A
low relative humidity is maintainedB
triple banded squirrel cage fans are usedC
air circulation is a maximumD
high relative humidity is maintained
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单选题As the temperature for a given mass of air increases，the（）.A
dew point increasesB
dew point decreasesC
relative humidity increasesD
relative humidity decreases
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单选题The latent heat of water vapor in air is dependent upon the （）A
dry bulb temperatureB
wet bulb temperatureC
dew pointD
dry point
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单选题The sensible heat of air is dependent upon the （）.A
dry bulb temperatureB
wet bulb temperatureC
saturation temperatureD
water vapor superheat
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单选题When compared to air temperature,which factor is most useful in predicting fog?（）A
Vapor pressureB
Dew pointC
Barometric pressureD
Absolute humidity
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单选题The effective temperature of air is dependent upon（） Ⅰ.relative humidity Ⅱ.air velocityA
ⅠonlyB
ⅡonlyC
Both Ⅰand ⅡD
NeitherⅠnor Ⅱ
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