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
您可能感興趣的試卷
你可能感興趣的試題
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
On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is （）.
Low compressor head pressure in a refrigeration system can be caused by（）.
A salinity indicator is used to determine the （）.
One cause of high head pressure occurring in a refrigeration system can be （）.
Which of the listed pumps is NOT a positive displacement pump?（）
The usual symptoms of cavitation in a centrifugal pump is （）.
A pressure drop through the refrigerant liquid line may cause （）.
An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by （）.
If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.
The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its （）.