OSI模型有7层结构，是一个开放性的系统互联参考模型，其最底下两层是()。

A cracked diaphragm in a thermostatic expansion valve will cause the valve to _____.

A.return to a neutral position

B.flood the evaporator

C.open

D.close

Thermostatic expansion valve are _____.

A.either all the way open or all the way closed

B.normally open

C.throttled depending on load

D.controlled by suction pressure

A.around the engine

B.around the cooler

C.to the expansion tank

D.overboard

A.open

B.close

C.remain in its position

D.flood the evaporator with refrigerant

When replacing a thermostatic expansion valve sensing bulb, it is necessary to

A.apply a light film of oil to increase heat transfer

B.apply a light film of oil to prevent oxidation

C.apply a heavy coating of grease to function as a heat sink

D.carefully coat the device with silicone sealant to reduce the effects of convective cooling

A.nonexistent

B.for controlling pressure

C.for controlling superheat

D.for controlling the solenoid valve

When you adjust a thermostatic expansion valve, _____.

A.refrigerant must be bled off the sensing line before adjustments are made

B.all refrigerant must be pumped into the receiver before adjustments are made

C.time must be allowed for conditions to stabilize in the evaporator before further adjustments are made

D.all refrigerant must be routed through the dehydrator while changing the superheat setting

If the superheat value of a thermostatic expansion valve is set too low, the _.

A.the suction line will be abnormally cold and liquid may slug back to the compressor

B.the suction line will be hot due to a reduced amount of refrigerant returning to the compressor

C.the temperature of the refrigerant within the condenser will remain the same

D.the temperature of the refrigerant passing through the sub-cooler will decrease

A.The liquid receiver functions to collect and remove non-condensable gases

B.A thermostatic expansion valve is used to control refrigerated space temperature

C.Refrigerant temperature in an evaporator is directly related to refrigerant pressure

D.Dehydrators must be used continuously in a refrigeration system

A.either all the way open or all the way closed

B.normally fully open

C.throttled depending on load

D.controlled by liquefied pressure