A.The two objects must be in physical contact
B.The two objects must be the same size
C.There must be an existing temperature differential
D.There must be an existing weight differential
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A.insufficient lubrication
B.insufficient refrigerant
C.excess refrigerant
D.excessive opening of the expansion valve
A.increase compressor discharge pressure on demand
B.increase compressor operating speed as necessary
C.allow the motor to turn the compressor opposed only by friction
D.reduce the compressor frictional load when starting
A.Radiation
B.Conduction
C.Convection
D.Each of the above
A.Shortage of refrigerant oil
B.Slight shortage of refrigerant
C.Excessive condenser cooling water flow
D.Faulty expansion valve
A.vary their speed according to temperature and load
B.start and come up to speed before air compression begins
C.change speed according to overload demands
D.reduce compressed air charge density
最新試題
Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?（）
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On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is （）.
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.
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Thermostatic expansion valves can be adjusted for （）.
Who is responsible for ensuring that someone is assigned to close the watertight doors in an emergency?（）
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A gradual decrease in the discharge pressure of an operating hydraulic pump can be caused by （）.
The general purpose of a heat exchanger is to （）.