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

考题 tell us briefly about the working principles of the purifier ,the oil water seperator and air compressor .

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考题 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(氧化) of the lube oil from overheatingD.reducing the floc or cloud point of the oil

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考题 Sludge may form in the crankcase of an air conditioning compressor as a result of ______.A.bubbling refrigerantB.overheating and oxidationC.lowered operating temperaturesD.reducing the cloud or floc point

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考题 What is the most probable cause of reduced capacity in a reciprocating air compressor ________．A.Carbon on cylinder headsB.Faulty unloaderC.Leaking air valvesD.Plugged air cooler

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考题单选题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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考题单选题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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考题单选题Sludge may form in the crankcase of an air conditioning compressor as a result of （）.A bubbling refrigerantB overheating and oxidationC lowered operating temperaturesD reducing the cloud or flash point

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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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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

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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.

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考题单选题（）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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考题单选题Which of the listed operating conditions would have the greatest effect on the volumetric efficiency of an operating reciprocating air compressor?（）A The density of the air entering the compressorB The temperature of the air entering the compressorC The designed rotating speed of the compressorD A leaking head gasket

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考题单选题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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考题单选题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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考题单选题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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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 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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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

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考题单选题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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考题单选题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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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

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考题单选题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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考题单选题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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考题单选题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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考题单选题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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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.

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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

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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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