A.molecular fluid vibration
B.energy losses
C.wide pressure variations
D.mechanical damage to control valves
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A.Keeps the refrigerated space cooler
B.Reduces the efficiency of the plant
C.Takes the load off the compressor
D.Has no affect on the system
A.proportional band
B.the error signal
C.the reset signal
D.feedback
A.Dehydrators must be used continuously in a refrigeration system
B.A 25 ton refrigeration system has the same cooling effect as melting 25 tons of ice in 24 hours
C.A thermostatic expansion valve is used to control refrigerated space temperature
D.The liquid receiver functions to collect and remove non- condensable gases
A.Hydraulic
B.Mechanical
C.Pneumatic
D.Electrical
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
最新試題
Who is responsible for ensuring that someone is assigned to close the watertight doors in an emergency?（）
A pressure drop through the refrigerant liquid line may cause （）.
When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.
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（）.
The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will （）.
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 amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its （）.
One cause of high head pressure occurring in a refrigeration system can be （）.
The output volume of a positive fixed displacement pump can be changed only by （）.