Permanent Magnet for Electronic Expansion Valve (EEV)
electronic expansion valves are designed for use in air conditioning and refrigeration systems or in heat pumps. The valve controls the automatic adjustment of refrigerant flow rate and makes the system work under optimized conditions for the purpose of fast cooling or heating, precise temperature control and energy saving. The valve can also be used e.g. for suction line pressure controls. These valves provide bidirectional operation to control the refrigerant flow rate in heating or cooling mode.
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Electronic Expansion Valve (EEV)
The electronic expansion valve is a device that is used to control the refrigerant flow into the evaporator in precise amounts. Therefore, they can be found in air conditioners, heat pumps, and other equipment that follow the refrigeration cycle.
You can find what you are looking for regarding your HVAC requirements here at Linquip, and we encourage you to read along to get to know an important component of your cooling system.
The role of expansion valves
An expansion valve is a flow regulator that is intended to decrease the pressure of the fluid reaching to it by partially vaporizing it, which leads to lowering the temperature of the refrigerant in the case of cooling systems due to increase of heat transfer surface area. Not only does it regulate the fluid temperature, but also it regulates the flow rate to entering the evaporator.
Refrigerant flow rate regulation is a sensitive task. If the refrigerant flow is too little, then evaporation would take place at a fast pace, leading to a consequent rise of temperature due to further heat transfer. This means that the evaporator efficiency would decrease as a result of refrigerant warm-up and overheating. Moreover, excessive refrigerant transmission leads to insufficient evaporation, which could damage the compressor.
It is, therefore, desired to avoid any excessive refrigerant flow passage and adjust the amount of the fluid transferred to the evaporator by monitoring the level of overheating.
The amount of overheating can be calculated by subtracting the compressor’s suction side temperature from the evaporation temperature. A temperature sensor is installed on the expansion valve, and another temperature sensor is placed at the exit of the evaporator (which is the suction temperature of the compressor) to provide the values for overheating calculation.Permanent Magnet for Electronic Expansion Valve (EEV)
Now, expansion valves come in two different types. The first type is the thermostatic or thermal expansion valve, aka TXV, and the second one is the electronic expansion valve, or EEV.
Advantages of the electronic expansion valve
Despite the fact that an EEV costs more than a TXV, it has many benefits that could make it the better solution for your needs. To begin with, the electronic expansion valve is highly reliable, quickly installed, and can be integrated with a centralized controlling unit to automate and optimize the control of the refrigerant throughout the entire refrigeration circuit. Moreover, it is quite flexible in terms of the refrigerant type.
In addition to the aforementioned, it can deliver a good performance at low condensing pressures where the pressure difference across the evaporator is very low due to better overheating control. Now, the strength of the electronic expansion valve here is that it maintains the compressor’s performance at similar levels, no matter how much the evaporator load is. It would more precisely control the amount of evaporation and save energy consumption as much as 15%.
Main parts of an EEV
Although there are different designs for an electronic expansion valve, the general design would include a permanent magnet and a copper coil inside the stepper motor body, placed at the top, by which an electromagnetic field is generated. The stepper motor is coupled with a shaft that is connected to a thread. When energized, the shaft pushes the thread and then the needle onto the valve seat, and this is how an electronic expansion valve controls the refrigerant flow rate.