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
The usual symptoms of cavitation in a centrifugal pump is （）.
If the relief valve on the discharge side of a hydraulic pump lifts, the cause could be （）.
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?（）
A gradual decrease in the discharge pressure of an operating hydraulic pump can be caused by （）.
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.
If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.
The rate of heat transfer from a hot region to a cold region is affected most by the （）.
The output volume of a positive fixed displacement pump can be changed only by （）.
Thermostatic expansion valves can be adjusted for （）.
The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its （）.