Axial and centrifugal fans are the two primary types of air-moving devices in the industry, which are designed to move air in large volumes in general ventilation at lower resistance.
Whether to choose centrifugal fans or axial fans, will be easier once you understand the difference between these two types of fans.
What is a Centrifugal Fan?
A centrifugal fan, also referred to as a radial fan, draws air along the line of the motor and blows it out at 90 degrees.
The rotating impeller blades have aerodynamic mechanisms that generate strong and effective air that can be used in the ventilation and industrial process.
What is an Axial Fan?
An axial fan is a mechanical engine that causes the flow of air parallel to its rotating shaft.
The in and out air move as well as the fun creates the pressure that is required to generate a steady and efficient stream of air to cool or ventilate any given space.
Difference between Centrifugal Fan and Axial Fan
· Air Flow Direction
Axial fans can transport air in a straight and parallel direction to the fan axis hence resulting in high airflow rates with low-pressure-suited application in HVAC ventilation ducts and condenser cooling.
Centrifugal fans, on the other hand, operate on a lower flow rate and produce high pressure at the center-radial direction of the air handling units, dust collection, and filtration systems.
· How the Fan Works
The axial fans have angled rotating blades that rotate along a central shaft by pulling in air and forcing it in the same direction, which is effective in maintaining a constant air flow.
However, centrifugal fans involve a rotating fan that draws air in and expels it out in a 90-degree rotation, which generates increased pressure in the systems that handle air and control dust.
· Fan Design
Design-wise, axial fans are designed with a compact, skewed blade construction and are placed on a central hub, and push air to flow parallel to the shaft.
This is perfect in condensers and exhaust, and cooling tower applications.
Centrifugal fans on the other hand have a rotating impeller in a scroll-shaped housing and redirect airflow at 90 degrees.
· Pressure Capability
Centrifugal fans transport air well via filters, long ducts, and heat exchangers in high static pressure without much of their efficiency being lost.
Axial fans work best in low to medium pressure including; cooling large areas, ventilating equipment, cooling large spaces, or passing air directly through walls and open buildings.
· Efficiency
At low-resistance, an axial fan achieves efficiency ratio that is high, but with increased static pressure, they decline in efficiency very quickly.
These centrifugal fans, with backward-curved or airfoil blades, on the other hand, are more effective at overcoming resistance.
For a greater pressure differential demanding system, they use mechanical energy to convert it into a static pressure.
· Noise Level
Axial fans tend to be less noisy when operating in free-air environments, as the air moves through them without any problems.
In contrast to centrifugal fans which are noisier due to the air rotation in the scroll housing that increases pressure.
The noise levels are higher when the pressure or velocity is high, hence the greater the turbulence.
However, this problem has been mitigated by contemporary designs that use backward-curved blades and sound absorbing casings.
· Size and Space Requirement
It is very easy to integrate axial fans with other systems due to their linear architecture. They have small depth dimensions which you can install in-line or as wall mounts with minimal space.
Centrifugal fans have a higher installation area due to the scroll housing and the 90 degrees airflow direction.
They tend to get heavier and bulkier, and therefore, you need to be securely mounted with inlet and outlet ducts that take up more space.
· Cost
On cost grounds, the axial fans are cheaper to produce and set into place. Their minimalist construction implies fewer materials are used, less time is spent on construction, and less money is spent on shipping because of lightweight construction.
On the other hand, centrifugal types are more costly at the beginning, but may be more economical in the long run in harsh applications.
· Specific Uses
The uses of centrifugal fans are most common in challenging environments where air has to penetrate the systems of higher resistance or barriers. Like; dust collection, air handling units, fume extraction, industrial dryers, and HVAC systems of high-rise buildings.
While axial fans are used when moving large amounts of air under low pressure in condenser cooling, cooling warehouses, recirculating air in data centers, and heat dissipation in electrical enclosures.
Conclusion
The difference between centrifugal and axial fans is in the direction of airflow, the pressure work, and the compatibility of the system.
To achieve more efficiency, durability, and the best performance, consider matching the type of fun to the system requirements.
FAQ
1. Which are better, axial fans or centrifugal fans?
Neither of the two fans is better than the other; the type of system you have will determine the type of fan to go for.
Axial fans are designed to deal with large airflow at a low resistance, whereas centrifugal fans are more effective in dealing with high static pressure.
2. What are the disadvantages of centrifugal fans?
Centrifugal types of fans are bigger, heavier, noisier, and more expensive than axial fans.
They are also complicated to maintain because of their intricate construction.
3. What are the disadvantages of axial fans?
Axial fans drop off in efficiency in high-resistance settings, they are very noisy when operating at high speed, and are also less efficient in ducted systems.
4. What are the similarities between centrifugal fans and axial fans?
They both circulate air by transforming mechanical energy into the movement of air.
They have blades, bearings, and a motor as their common major parts and neither can be used effectively without proper matching to the system resistance.
