单项选择题
Excessive circulation of the lubricating oil with the refrigerant in a refrigeration system will cause （）.
A.carbon deposits on the compressor suction valves
B.the evaporator temperature to increase
C.rapid corrosion of the thermal expansion valve
D.no operating problems
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相关考题
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单项选择题
Scale accumulation on evaporator heat exchange surfaces （）.
A.increases brine density
B.increases distillate salinity
C.reduces metal corrosion
D.reduces heat transfer -
单项选择题
In order to properly remove air from the casing of a centrifugal pump when starting, the pump should have a （）.
A.positive head
B.negative suction head
C.mechanical seal
D.vent valve attached to the casing at the top of the volute -
单项选择题
The valve best suited for throttling gas or liquid flow in a pipeline is the（）.
A.gate valve
B.globe valve
C.check valve
D.plug cock
