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In a chilled(冷的) water air conditioning unit using a reciprocating compressor, the refrigerating effect of the primary refrigerant can be increased by ______.
A.increasing refrigerant pressure in the coil
B.increasing chilled water flow through the cooler
C.sub-cooling the refrigerant in the condenser
D.superheating the refrigerant in the compressor
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更多 “ In a chilled(冷的) water air conditioning unit using a reciprocating compressor, the refrigerating effect of the primary refrigerant can be increased by ______.A.increasing refrigerant pressure in the coilB.increasing chilled water flow through the coolerC.sub-cooling the refrigerant in the condenserD.superheating the refrigerant in the compressor ” 相关考题
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单选题Excessive lube oil consumption by a reciprocating air compressor can be caused by ().A
using a slightly dirty air filterB
using oil having an excessive viscosityC
intercooler or after-cooler leaksD
carrying the oil level higher than normal
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单选题In an air conditioning system, low head pressure associated with a reciprocating compressor can be the result of ()A
broken valve springsB
tight drive beltsC
high line voltageD
air in the system
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单选题Sludge may form in the crankcase of an air conditioning compressor as a result of ().A
bubbling refrigerantB
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lowered operating temperaturesD
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dew point temperatureC
primary air temperatureD
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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
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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.
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单选题()are supplied by main switchboard directly.A
Suez Canal searchlight, air compressor and air conditioning compressorB
Air compressor, boiler blower and refrigeration plantC
Boiler blower, Suez Canal searchlight and refrigeration plantD
Suez canal searchlight, air compressor and boiler blower
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单选题In a chilled water air conditioning unit using a reciprocating compressor, the refrigerating effect of the primary refrigerant can be increased by ().A
increasing refrigerant pressure in the coilB
increasing chilled water flow through the coolerC
sub-cooling the refrigerant in the condenserD
superheating the refrigerant in the compressor
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单选题The purpose of an air compressor unloading device is to ()A
drain water from the air receiverB
drain water from the cylindersC
delay the compression process until the motor is up to speedD
check pump alignment
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单选题A reciprocating air compressor is running roughly and vibrating excessively, indicating that the ().A
compressor is overloadedB
motor is overloadedC
foundation bolts are looseD
belts are too tight
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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 happens in the end to the water from Lake Ontario?A
It is used by the residents of Toronto.B
It is returned to a place deep in the lake.C
It is cooled down before being used again.D
It is added to the water inside air-conditioning systems.
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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
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单选题If a reciprocating air compressor has a knock occurring in frequency with its operating RPM, the cause is probably ().A
misalignment or worn main bearingsB
insufficient cylinder lubricationC
defective or poorly fitted valvesD
all of the above
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单选题Sludge may form in the lubricating oil crankcase of a reciprocating air conditioning compressor as a result of ().A
wax precipitation in the lube oilB
contamination by dust, scale, or moistureC
refrigerant bubbles in the lube oilD
refrigerant reducing the lube oil viscosity
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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
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单选题A centrifugal compressor’s purge recovery unit()A
reclaims waterB
purges air without losing refrigerantC
purges air with some loss of refrigerantD
purges lube oil from the refrigerant
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单选题Sludge may be formed in the oil in the crankcase of a reciprocating air conditioning compressor as a result of ()A
refrigerant bubbles in the lube oilB
refrigerant reducing the lube oil viscosityC
oxidation of the lube oil from overheatingD
reducing the floc or cloud point of the oil
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单选题Routine maintenance on a Central Control Room hermetically sealed air conditioning unit should include ()A
changing the air filterB
recharging the systemC
changing compressor lubricantD
renewing container vacuum
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单选题Excessively low air pressure occurring in the intercooler of a reciprocating air compressor is caused by().A
leaky discharge valves on the LP cylinderB
leaky discharge valves on the HP cylinderC
insufficient intercooler coolingD
low ambient air pressure
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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The quantity of cooled air delivered by an air conditioning unit should () the sum of the quantity of air re-circulated to the unit and the quantity mechanically exhausted.A
balanceB
not balanceC
be more thanD
be less than
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 one advantage of Enwave 's new system?A
It keeps buildings much cooler than other methods.B
It can be used by large cities anywhere in the world.C
It is much more energy-efficient than traditional systems.D
It keeps water from being used for more than one purpose.
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