A.a shortage of compressor oil
B.warm food in the refrigerator
C.excessive condenser cooling water
D.a shortage of refrigerant
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A.molecular fluid vibration
B.energy losses
C.wide pressure variations
D.mechanical damage to control valves
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
最新試題
Low compressor head pressure in a refrigeration system can be caused by（）.
If the head pressure of a reciprocating refrigeration compressor is excessive, （）.
An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.
The major source of chemical contaminants in hydraulic fluid is （）.
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.
Heavy wear in a particular area of the inner circumference of a packing ring may be caused by （）.
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.
If you are given the job of adding hydraulic fluid to a mooring winch, and are not certain as to the type of fluid to use, you should （）.
If the relief valve on the discharge side of a hydraulic pump lifts, the cause could be （）.
One cause of high head pressure occurring in a refrigeration system can be （）.