Mixed Flow Fan VS Axial Fan VS Centrifugal Fan
At home or in the workplace, extractor fans are pretty important. They make it easier to get rid of odors and stale air in rooms. Extractor fans can be mounted on a window or a wall and come in various shapes and sizes. They differ in size, low voltage capability, and regulating capabilities. Bathroom fans that use low voltage electricity are excellent. Some extractor fans have built-in systems that turn on when particular humidity levels are reached in specific rooms. Although most extractor fans are mounted on windows and walls, the optimal placement is immediate across from the air source. Generally, most fans or blowers are categorized into one of four fundamental types, which are named in relation to the direction of flow through the impeller:
- Axial flow fans
- Centrifugal Fans
- Mixed Flow Fans
- Crossflow fans
Below is the introduction and description of some common fans in the HVAC system.
Mixed Flow Fan
In relation to the shaft, mixed flow fans allow airflow in radial and axial directions. In the fan’s impeller, the airflow direction is between the axial flow and the flow along the cone, so it can be called a mixed flow fan. On a central shaft, mixed flow fans feature two different types of blades. One of these blades is a rotor blade, while the other produces a beam of air rather than the cone form seen in centrifugal fans.
Furthermore, these fans include two distinct design strategies to improve efficiency: A pressure differential is one way to move air. The blades hit the air in the second approach, forcing it to travel in a specific direction. Bathrooms and kitchens are common places to find these types of fans. They’re commonly found on duct systems known for their high pressure, excellent air circulation, and low noise. These fans can be installed at the start, middle, and end of the duct system. The installation and uninstallation of this sort of fan are both straightforward.
Axial Fan
Axial fans may be traced back to Europe’s Middle Ages horizontally oriented windmills. Axial fans were the first electrically driven fans launched in the 1880s. After the axial flow into the fan impeller, the flow in the rotating blade flow along the axial direction of the fan that is axial fans. As a result, the axial fans are named from the direction of their airflow. Blades revolving around an axis suck air parallel to it and thrust it out in the same direction.
Some people choose to put axial extractor fans on ceiling boards or walls, while others mount them on windows. The blowing out of compressed air through ducts linked to wall caps is easier with those fixed on the wall. Through the wall caps, the moistened air is ejected into the environment. There is frequently considerable resistance to the flow of air when ducts are employed, which slows down the fan’s performance. The ducting should be straightened out and kept at a consistent level for the axial fan to work correctly. It’s also a good idea to have the fan aperture, ducts, and wall cover all the same size. A considerable loss of efficiency occurs when consistency is not maintained at any stage.
Axial fans provide high-flow airflow, which means they move a lot of air. However, they do produce low-pressure airflows. Their functioning needs a low-power input. There are three types of axial extractors: Class C, Class A, and Class K. Class A fan blades can only be adjusted when the fan is not active; however, Class C fans can be adjusted while the fan is operational. The blades of Class K fans, on the other hand, cannot be adjusted. Because of their compactness and low cost, axial extractor fans are the most frequent of the three types listed above.
Centrifugal Fan/Radial Fan
Lieutenant General Alexander Sablukov of the Imperial Russian Army of the Russian Empire created the centrifugal fan in 1832. Centrifugal fans are also known as radial fans; they are commonly referred to as blowers. Centrifugal fans have many of the same capabilities and features as centrifugal pumps. According to the intake air flow, and the compressed air, the air is compressed and flows in a radius direction under the centrifugal force; such running ways are centrifugal fans. Centrifugal fans move air radially, which means that the direction of the outgoing air differs from that of the inflow air. A fan wheel, which consists of a set of blades fixed on a circular hub, increases the pressure of an incoming airstream. The forward multi-vatic, straight steel plate paddle wheel and backward turbo blade are the three types of centrifugal extractor fans.
Radial fans differ from axial fans in many ways. They’re attached to the ceiling, are more powerful than axial fans, and can run at peak efficiency even when there is a lot of air pressure resistance in the ducts. The centrifugal extractor fan allows you to set up a system to remove damp air from many rooms. They can readily function in big spaces due to their high capacities. It is unnecessary to install one for an ample space; for example, three units may be installed to cover the toilet, shower, and bathtub independently in a large bathroom.
The airflow produced by centrifugal fans is channeled through a ducting or tube system. Compared to axial fans, this helps provide a more significant pressure airflow. Despite their lower flow rate, Centrifugal fans create a more consistent airflow than axial fans. Centrifugal fans, on the other hand, need a larger power input. The fan is long-lasting and makes little noise when in use.
Below are: Centrifugal, axial and mixed flow type
Comparison
|
Items |
Axial Fan |
Mixed Flow Fan |
Centrifugal Fan |
|
Features |
High flow rates and low-pressure flow parallel to the fan’s axis. |
Combine the features of Axial and Centrifugal Fans, higher pressure than axial fans and a higher flow than centrifugal fans. |
Low flow rates and high pressures with flow perpendicular to the blower axis. |
|
Pressure |
Axial fan < Mixed Flow Fan<Centrifugal Fan |
||
|
Air Volume |
Axial fan> Mixed Flow Fan> Centrifugal Fan |
||
|
Noise |
Axial fan < Mixed Flow Fan<Centrifugal Fan |
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|
Blade Shapes |
Aerofoil, Sickle, Paddle, and Variable pitch |
Combine the features of Axial and Centrifugal Fans |
Paddle, Radial, Backward curved, and Forward curved |
Crossflow fan
In a crossflow fan, air flows inwards then outwards radially. Crossflow fans, which have a long, rectangular design, are appropriate for regions with limited space. They come in DC, AC, and high-efficiency EC varieties and a wide range of sizes and efficiencies to suit any purpose. Crossflow fans are frequently used in the HVAC and electronics sectors to provide an equal laminar airflow that prevents components from overheating. Crossflow fans, positioned vertically or horizontally, provide a two-dimensional flow.
This type of fan may be found in a wide range of industrial and commercial settings. They have a variety of benefits over other sorts of fans, such as higher efficiency despite lower pressure and placement, a more compact design with a long, shallow front, and long-throw direct ventilation. Crossflow fans have advantages of controllability adaptability, low load needs when throttled, reduced speed, and minimal noise.
Main fan parameters
The capacity in volume, pressure, efficiency, and rotational speed of a fan are all essential characteristics in its operation. The capacity is the volume of fluid pushed by the fan in a unit of time, and it is commonly measured in m3/h, m3/min., and m3/sec. The efficiency of a fan is the ratio of the energy it produces to the power it takes to drive it. The number of rotations the fan impeller must make to achieve the performance criteria is the rotational speed. The total pressure equals the sum of the static pressure, which is the energy necessary to sustain the system’s opposing frictions: the dynamic force or kinetic energy given to the flowing fluid. The dynamic pressure is determined by the fluid speed and the specific gravity. This article is very good to teach you HOW TO CALCULATE REQUIRED CFM FOR A GROW TENT
Applications
Mixed Flow Fan: very popular in kitchens and bathrooms, as they produce high airflow rates needed for kitchens. Furthermore, they are ideal for short to medium duct runs in toilets and smaller utility rooms.
Axial Fan: They have higher pressure capabilities and medium flow capacity. The more efficient uses include heat, smoke and fume removal, process drying, comfort and process cooling, and general HVAC ventilation.
Centrifugal Fan: The capability to generate low to medium flow rates at medium to high pressures makes centrifugal fans ideal for applications with higher system pressure losses such as cooling and heating systems, dust control, etc.
In Conclusion
These fan types differ from each other in design and functionality; depending on the amount of airflow, pressure, and efficiency required for the process, you can pretty easily figure out which type of fan is the most appropriate choice for you.
If you still need help deciding between fan types, contact us and let our experts help you out!