A.Energy can be created or destroyed
B.Energy may not be transformed
C.The total quantity of energy in the universe is always the same
D.None of the above
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A.evaporator
B.compressor
C.expansion valve
D.condenser
A.has continuously for a long period
B.suction pressure is below normal
C.oil level is below normal
D.starts after a long idle period
A.protect the pump from fine soluble contaminants
B.prevent solid particles from entering the pump
C.prevent solid particles from entering the filter
D.protect the directional control valves
A.Feed-water heater internal tube surfaces
B.Internal distillate cooler tubes
C.Flash chamber vertical surfaces
D.Distilling condenser tubes
A.Reduction of friction
B.Insulation of hot surfaces
C.Lubrication of moving parts
D.Elevation of cooler outlet temperatures
最新試題
Which of the following statements is correct concerning heat transfer?（）
The control mode in which the final control element is moved from one of two flexed positions to the other is known as （）.
The temperature differential occurring between the inlet temperature of the fluid to be cooled and the outlet temperature of the cooling medium in a shell-and-tube heat exchanger is greatest in which of the flow designs listed?（）
The output volume of a positive fixed displacement pump can be changed only by （）.
The major source of chemical contaminants in hydraulic fluid is （）.
If the relief valve on the discharge side of a hydraulic pump lifts, the cause could be （）.
The rate of heat transfer from a hot region to a cold region is affected most by the （）.
Heavy wear in a particular area of the inner circumference of a packing ring may be caused by （）.
The general purpose of a heat exchanger is to （）.
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.