There are several types of expansion valves available in the Singapore Aircon market, but in this article, we will discuss five different types of expansion valves.
1. Electronic Expansion Valve (EEV):
The electronic expansion valve is a newer type of expansion valve that operates on the principle of electronic control. It consists of a stepper motor, a valve body, and an electronic controller. The electronic controller receives signals from a temperature sensor and a pressure sensor, and based on these signals, it sends commands to the stepper motor to adjust the valve opening.
The electronic expansion valve provides more precise and faster control of refrigerant flow than the thermostatic expansion valve. It can adjust the refrigerant flow rate in real-time to match the changing load conditions of the system. This results in improved system performance and energy efficiency.
· Advantages:
The main advantage of the electronic expansion valve is its high level of precision and accuracy. It can provide precise and stable superheat control even under rapidly changing operating conditions. Another advantage is its ability to respond quickly to changes in operating conditions, resulting in improved system performance and energy efficiency.
2. Thermostatic Expansion Valve:
The thermostatic expansion valve is a more complex type of expansion valve. It consists of a valve body, a sensing bulb, and a power element. The valve body contains the valve seat, which controls the flow of refrigerant into the evaporator.
The sensing bulb is attached to the suction line of the evaporator and measures the temperature of the refrigerant. The power element consists of a diaphragm or bellows and a spring, which provides the force to open or close the valve.
When the temperature of the refrigerant leaving the evaporator rises, the pressure in the sensing bulb increases, which causes the diaphragm to move the needle valve, reducing the flow of refrigerant into the evaporator.
Similarly, when the temperature of the refrigerant leaving the evaporator falls, the pressure in the sensing bulb decreases, causing the diaphragm to move the needle valve, increasing the flow of refrigerant into the evaporator.
· Advantages:
The thermostatic expansion valve provides precise control over the refrigerant flow based on the temperature of the refrigerant at the outlet of the evaporator. This results in better energy efficiency and improved system performance.
3. Multi-Orifice Expansion Valve:
The multi-orifice expansion valve is a type of expansion valve that uses multiple orifices to regulate the refrigerant flow. It consists of a valve body, multiple orifices, and a power element. The valve body contains the valve seat, which controls the flow of refrigerant into the evaporator.
The multiple orifices are small holes or slots that are arranged in a circular pattern around the valve seat. The power element consists of a diaphragm or bellows and a spring, which provides the force to open or close the valve.
· Advantages:
The multi-orifice expansion valve provides precise control over the refrigerant flow, which helps maintain the desired pressure and temperature within the system. This results in better energy efficiency and improved system performance.
The multi-orifice expansion valve is suitable for a wide range of refrigerants, including R-22, R-134a, and R-410a. The multi-orifice expansion valve provides a high level of efficiency and reduces the risk of evaporator flooding, which can cause a system failure.
4. Constant Pressure Expansion Valve:
The constant pressure expansion valve, also known as the capillary tube, is a simple and inexpensive type of expansion valve. It consists of a long, narrow tube that is coiled or spiraled to fit into a small space. The tube is made of copper or aluminum and has a small diameter, usually between 0.5 to 2.5 mm.
The capillary tube works on the principle of pressure drop across the tube, which causes the refrigerant to expand and evaporate. The pressure drop is created by the restriction in the tube, which slows down the flow of refrigerant.
· Advantages:
By maintaining a constant pressure and flow rate of refrigerant into the evaporator, the constant pressure expansion valve ensures that the evaporator operates at optimal efficiency, reducing energy consumption and operating costs.
The design of the constant pressure expansion valve is simple and durable, with few moving parts that are less prone to wear and tear, making it a reliable and long-lasting component of a refrigeration system.
5. Automatic Expansion Valve:
The automatic expansion valve, also known as the float valve, is a type of expansion valve that uses a float to regulate the refrigerant flow. It consists of a valve body, a float, and a needle valve. The float is a hollow ball or cylinder that is attached to the valve stem. The valve body contains the valve seat, which controls the flow of refrigerant into the evaporator.
In air conditioning systems, it is used to regulate the flow of refrigerant into the evaporator coil. As the refrigerant level changes in the evaporator, the float moves up or down, which opens or closes the valve to adjust the flow of refrigerant.
Overall, the use of a float expansion valve in air conditioning systems provides precise control of refrigerant flow, resulting in improved system efficiency and performance. This makes it a reliable and effective component in air conditioning systems.
· Advantages:
The key advantage of using a float expansion valve in air conditioning systems is its ability to maintain a constant evaporator temperature, regardless of the load requirements of the system. This results in improved system efficiency and better performance, as the valve adjusts the refrigerant flow rate to match the heat load on the system.
The automatic expansion valve is a simple and reliable device that requires minimal maintenance. It has no moving parts and does not require any external power source.