单选题Constant superheat is maintained at the evaporator outlet of a refrigeration coil by a（）Asolenoid valveBlow pressure cutout switchCking valveDthermal expansion valve
单选题
Constant superheat is maintained at the evaporator outlet of a refrigeration coil by a（）
A
solenoid valve
B
low pressure cutout switch
C
king valve
D
thermal expansion valve
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