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
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
相关考题：
tell us briefly about the working principles of the purifier ,the oil water seperator and air compressor .
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
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
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
单选题Excessive lube oil consumption by a reciprocating air compressor can be caused by （）.Ausing a slightly dirty air filterBusing oil having an excessive viscosityCintercooler or after-cooler leaksDcarrying the oil level higher than normal
单选题In an air conditioning system, low head pressure associated with a reciprocating compressor can be the result of （）Abroken valve springsBtight drive beltsChigh line voltageDair in the system
单选题Sludge may form in the crankcase of an air conditioning compressor as a result of （）.Abubbling refrigerantBoverheating and oxidationClowered operating temperaturesDreducing the cloud or flash point
单选题A re-heater, as used in an air conditioning system, is designed to control the （）Achilled water temperatureBdew point temperatureCprimary air temperatureDdry bulb temperature
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?（）AChilled water system supply temperatureBChilled water system return temperatureCCompressor discharge temperatureDCompressor suction pressure
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?AThey pump the air continuously to the units in each room.BThey lower the temperature of the water in the system.CThey help the water cool down naturally on the roof .DThey gradually clean the water as it flows through the building.
单选题（）are supplied by main switchboard directly.ASuez Canal searchlight, air compressor and air conditioning compressorBAir compressor, boiler blower and refrigeration plantCBoiler blower, Suez Canal searchlight and refrigeration plantDSuez canal searchlight, air compressor and boiler blower
单选题Which of the listed operating conditions would have the greatest effect on the volumetric efficiency of an operating reciprocating air compressor?（）AThe density of the air entering the compressorBThe temperature of the air entering the compressorCThe designed rotating speed of the compressorDA leaking head gasket
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 （）.Aincreasing refrigerant pressure in the coilBincreasing chilled water flow through the coolerCsub-cooling the refrigerant in the condenserDsuperheating the refrigerant in the compressor
单选题The purpose of an air compressor unloading device is to （）Adrain water from the air receiverBdrain water from the cylindersCdelay the compression process until the motor is up to speedDcheck pump alignment
单选题A reciprocating air compressor is running roughly and vibrating excessively, indicating that the （）.Acompressor is overloadedBmotor is overloadedCfoundation bolts are looseDbelts are too tight
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?AIt is used by the residents of Toronto.BIt is returned to a place deep in the lake.CIt is cooled down before being used again.DIt is added to the water inside air-conditioning systems.
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?（）AA room thermostat activates an electric heater at each individual chilled air outlet when necessaryBVarying the number of passes the air makes across the coilsCVarying the temperature of the water through the coilsDVarying the quantity of water flowing through the coils
单选题If a reciprocating air compressor has a knock occurring in frequency with its operating RPM, the cause is probably （）.Amisalignment or worn main bearingsBinsufficient cylinder lubricationCdefective or poorly fitted valvesDall of the above
单选题Sludge may form in the lubricating oil crankcase of a reciprocating air conditioning compressor as a result of （）.Awax precipitation in the lube oilBcontamination by dust, scale, or moistureCrefrigerant bubbles in the lube oilDrefrigerant reducing the lube oil viscosity
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 （）Aadmit only enough fresh outside air to provide proper ventilationBreduce the air reheating system loadClower the compressor head pressureDoperate the purge recovery unit continuously
单选题A centrifugal compressor’s purge recovery unit（）Areclaims waterBpurges air without losing refrigerantCpurges air with some loss of refrigerantDpurges lube oil from the refrigerant
单选题Sludge may be formed in the oil in the crankcase of a reciprocating air conditioning compressor as a result of （）Arefrigerant bubbles in the lube oilBrefrigerant reducing the lube oil viscosityCoxidation of the lube oil from overheatingDreducing the floc or cloud point of the oil
单选题Routine maintenance on a Central Control Room hermetically sealed air conditioning unit should include （）Achanging the air filterBrecharging the systemCchanging compressor lubricantDrenewing container vacuum
单选题Excessively low air pressure occurring in the intercooler of a reciprocating air compressor is caused by（）.Aleaky discharge valves on the LP cylinderBleaky discharge valves on the HP cylinderCinsufficient intercooler coolingDlow ambient air pressure
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?AEnwave's system is said to work only in cities located near the Great Lakes.BThe water deep in Lake Ontario always remains at the same temperature.CExperts warn that the use of CFCs in Enwave' s system will add to global warming.DToronto is now searching for new natural sources of water to use in its water supply.
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.AbalanceBnot balanceCbe more thanDbe less than
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?AIt keeps buildings much cooler than other methods.BIt can be used by large cities anywhere in the world.CIt is much more energy-efficient than traditional systems.DIt keeps water from being used for more than one purpose.