Where is the Expansion Valve Located?

Figure 1: An expansion valve.

Expansion valve, also known as Throttle valve, is an important automatic control component of refrigeration system. It is generally installed between liquid reservoir and evaporator. The temperature change of the sensing bulb is used as a signal to adjust the valve opening and change the refrigerant flow. The refrigerant with medium temperature and high pressure is throttled into wet steam with low temperature and low pressure, and then the refrigerant absorbs heat in the evaporator to achieve the refrigeration effect.

The thermal expansion valve shall be installed as close to the evaporator as possible. Because if the thermal expansion valve is far from the evaporator, the diameter of the pipeline from the thermal expansion valve to the evaporator needs to be appropriately increased and wrapped with thermal insulation materials. Therefore, the thermal expansion valve should be installed as close to the evaporator as possible. It is best not to have any accessories with large resistance between them, so as not to affect the flow regulation.

Figure 2: Structure of the expansion valve.

1. Where is the AC Expansion Valve Located

The ac expansion valve on the pipeline of the air conditioning refrigeration system is between the condensing radiator and the evaporator. It is close to the inlet of the evaporator.

The refrigeration system does not necessarily use the thermal expansion valve as the throttling element, but also can use the capillary tube and throttling short tube (CCOT) as the throttling element, which has low cost and good reliability. Electronic expansion valve can also be used to make the control more accurate. However, due to the use of sensors, control circuit boards and actuators with stepping motors the manufacturing become more complex and the cost is increased.

Figure 3: A blue air conditioner expansion valve

2.Installation Position of the Expansion Valve Used in Household Air Conditioner

The expansion valve on the pipeline of the air conditioning refrigeration system is on the pipeline between the condensing radiator and the evaporator, close to the inlet of the evaporator. It is recommended to follow the refrigeration system pipeline. The expansion valve is a small part of the pipeline with a slender tail next to it.

In general household wall hanging machine or cabinet machine, only variable frequency air conditioner use expansion valve. There is no expansion valve if it is fixed frequency machine. The expansion valve is generally installed in the outdoor unit, and the shape is a brass column. There are two right angle copper tubes in the middle and end of the column.

3. Installation Position of Expansion Valve Used in Automobile Air Conditioner

The expansion valve used in automobile air conditioning system is temperature controlled expansion valve, so it is also called thermal expansion valve. As shown in the figure, the installation positions of expansion valve, evaporator, blower and heater core of Santana 2000 series car air conditioning system are shown

Figure 4: A evaporator on car.

1 - Blower 2 - Vacuum valve 3 - Heater core 4 - Water outlet 5 - Water inlet
6 - Refrigerant inlet (from reservoir) 7 - Refrigerant outlet (to compressor)
8 - Expansion valve 9 - Evaporator core 10 - Thermostat 11 - Inlet hood filter screen 12 - Inlet hood 13 - Compartment temperature switch

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