Find out how expansion valve works!
Expansion Valve – It controls the flow of the refrigerant. The high pressure, high temperature liquid refrigerant coming from the condenser is turn into a low pressure, low temperature liquid refrigerant before entering the evaporator.
Most house-hold air conditioners, refrigerators, and freezers, uses small copper tubing called capillary tube to limit the liquid refrigerant flow. This capillary copper tube is a liquid refrigerant limiting device.
It is necessary that the liquid refrigerant enters the evaporator coil in a state of a low pressure liquid refrigerant. When heat is absorbed the liquid refrigerant boils and turns into gas.
Only gas refrigerant is allowed to enter into the compressor. Because gas can be compressed and liquid cannot.
There are five types of expansion valves. The capillary tube type, the automatic expansion type, the thermostatic expansion type, the low side float expansion type, and the high side float expansion type.
The capillary tube type is made up of a small copper tubing with hole diameter ranging from 1 mm to 3 mm.
Their length could be 8 to 12 feet, and it serves as a constant limiting valve to the refrigerant flow from condenser to the evaporator.
It is soldered or wrap around the suction copper tube from the outlet of the evaporator to the compressor. Heat exchange is taking place here.
The automatic expansion type or AEV, control the flow of the liquid refrigerant by opening and closing of a low pressure control valve. A mist of refrigerant is sprayed into the evaporator.
The thermostatic expansion type or TXV or TX, is a refrigeration component that controls the amount of refrigerant flow by the signal sent by the sensing bulb that is attached to the outlet of the evaporator, and give instructions to opening and closing the valve in the inlet of the evaporator.
The low side float expansion type uses a finned cooling coil to control the valve inside the valve. It maintains constant level of refrigerant into the evaporator.
The high side float expansion type is very much the same with the low side float type except it keeps the evaporator flooded with liquid refrigerant.
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