period four
Expansion Devices
notes
TXV Operation
diaphragm
evaporator
spring
remote bulb
suction | external equalizer | distributor | |
line | |||
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Figure 45
In a typical TXV application, the outlet of the valve is connected to the distributor. A remote bulb is attached to the suction line, where it senses the refrigerant vapor temperature leaving the evaporator. This bulb is charged with refrigerant and as heat is transferred from the suction line to the bulb, the refrigerant inside the bulb vaporizes. The resulting refrigerant vapor pressure is transmitted through a tube to the space above a diaphragm in the TXV.
The pressure of the refrigerant vapor leaving the evaporator is transmitted to the space beneath the diaphragm through an external equalizing line that is tapped into the suction line downstream of the bulb.
Finally, the valve contains an adjustable spring that applies a force to the lower side of the diaphragm.
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