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單項(xiàng)選擇題

If a refrigeration compressor is running continuously without lowering the temperature in the refrigerated space, the trouble may be （）.

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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單項(xiàng)選擇題

In the design of hydraulic piping and equipment consideration is given to minimize turbulence in the hydraulic fluid, as this will cause （）.

A.molecular fluid vibration
B.energy losses
C.wide pressure variations
D.mechanical damage to control valves

單項(xiàng)選擇題

Which of the conditions listed represents the greatest effect of excess frost accumulation on the evaporator coils?（）

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