Preface
One of the more common questions related to the selection process is how to choose the right type of fan among the two most popular fan types: the radial and the axial fan. Both fans have their distinct characteristics, advantages and apply in a variety of sectors including HVAC, dust collection systems or fume extraction in more industrial settings. It is equally important with regard to these conversations to understand how important fans are to these applications as well as the axial fan vs radial fan differences.
Ahead of this article, this paper concentrates on axial vs radial fans and their concepts, great and useful features as well as use recommendations that will assist you in identifying the ideal option for your fan specific requirements.
Understanding Radial and Axial Fans
What are Radial and Axial Fans?
Centrifugal fans, otherwise known as radial fans, are unique in that they have a wheel shaped design. These fans have blades which are constructed at an angle to the flow of air and then revolves around a stub. This design of such fans enables them to produce high pressure. In contrast, an axial fan is one that has its blades affixed to a rotating shaft which is parallel to the air flow such that they look like a propeller; hence they are effective in moving large volumes of air but with low pressure.
How Radial and Axial Fans Work
In terms of basic working principles, radial and axial fans work differently. With a radial fan, air enters the fan at a right angle to the shaft and is then accelerated around the turning blades. Air is flung outward due to centrifugal force faster than a comfort zone permits and is drawn out into a scroll casing that leads to the discharge. This type is well suited for industrial ventilation systems that require the high pressure that this type of fan can provide. Axial fans, on the other hand, bring air from parallel to the shaft and are able to expel air in the axial direction which is drawn into them. In this regard, the thorough airflow of an axial fan has to do with the configuration of the chord cut so that the air flows along the direction set by the pressure generated difference across the fan blades.
Why Choose Between the Two?
Knowing the distinction between axial vs radial fans is important because they have different applications and are found in different industries. Radial fans are popular for their high-pressure-generating capabilities, which make them suitable for ductwork of considerable distance, installations of industrial filtration systems, and industrial ventilation. In addition, they also possess a compact design that lets them be mounted in tight spaces. Axial fans, on the other hand, are quite powerful at producing large amounts of air as well but at low pressures hence suitable for general ventilation and cooling & exhaust systems.
In fact, research done by ASHRAE shows that an axial fan can deliver up to 20 times the volume of air of the same size radial fan under the same conditions but in an open area.
In the end, the correct types of fans are determined by the functional, airflow, application and spatial requirements.
Key Differences Between Radial and Axial Fans
Airflow Pattern
The radial versus axial fan comparison becomes easier when you examine the airflow patterns produced by the two. Radial fans operate in a manner where the generation of airflow is angled ninety degrees to the direction of the fan’s inlet. This means that air enters the unit from the vertical sides and exits the unit from the radial surface. Such a pattern compels the radial fan to exhibit high fan pressure which performs better against resistances posed by ducts or a filter system. Axial fans, in contrast, produce airflow in the direction of the fan’s axis. Air is pulled from one end and discharged from the other, allowing axial fans to efficiently handle considerable flow volumes.
Pressure and Volume
An important difference comes into place as axial fan vs radial fan configurations as far their pressure and volume characteristics. Radial fans are made to produce high pressure and so are useful in instances when a large resistance needs to be overcome such as in industrial processes and long duct systems. A maximum fan pressure differential of 1,000 mmWC (millimeters of water column) can be achieved by them. In contrast, the superiority of axial fans is in delivering a large amount of air, at a lower pressure. Under such conditions, where high volume flow is the most important requirement, for general ventilation, cooling, and exhaust systems, for instance, they are the preferred choice.
Efficiency and Energy Use
Do the axial vs radial fans perform differently on the energy efficiency and the energy consumption matrices? Yes they do and quite significantly. In high pressure low volume flow applications, radial fans are highly efficient, up to 80% efficiency under perfect conditions; in low pressure applications, they make the best choice. However, when high volume airflow rate is required, axial fans perform much better. Their power requirement for operation is much lower allowing them to be recommended for high airflow applications.
| Characteristic | Axial Fans | Radial Fans |
| Airflow Direction | Parallel to fan axis | Perpendicular to fan inlet |
| Pressure | Low | High |
| Airflow Volume | Large | Small |
| Energy Efficiency | High efficiency at high airflow | High efficiency at high pressure and low airflow |
| Suitable Applications | Large space ventilation, cooling towers, exhaust systems, etc. | Long distance ductwork, industrial filtration, dust collection systems, etc. |
Application Suitability and Selection
Ideal Situations for Radial Fans
Applications that need high pressure but allow for lower rates of flow are best met by the use of centrifugal or radial fans. In most cases, these fans are used for specific applications where the emphasis is placed on pressure instead of the volume of airflow. A few of the common use case scenarios include:
HVAC systems with extensive ducting where such pressures are needed to transport air through long or intricate networks of ducts.
Industrial processes that require pressure for material moving or handling and are in use for heavy industrial requirements.
Dust extraction and filter systems that need the motor of the fan to counter and surpass the pressure presented by any filter medium.
Applications such as drying and curing, require good and consistent pressures.
Pneumatic systems for the transportation of materials in pipes through the use of air pressure.
When selecting a radial fan, specify the desired pressure and airflow requirements, area available for the intake and manual constraints related to area available for installation. Also, specify the type of airstream containing particulates or corrosive agents as radial fans are designed for such airstream conditions.
Ideal Situations for Axial Fans
Axial fans are primarily developed for application with large air flows and low operating pressure. They are perfect when there’s a need to move large volumes of air in an efficient manner. Examples include:
General ventilating and air movement, which mainly involves refreshing air in big open areas
Cooled towers and heat exchangers that require massive volume of airstream to remove heat
Exhaust systems of massive places where the fan is to evacuate air fast
Ventilation in agriculture construction such as green houses and livestock buildings demands high air exchange
Automotive and transportation ventilation systems operating in small place but for high air flow applications
Whenever one needs to select a particular axial fan, several parameters should be taken into account, such as target application, size of the ventilated space, size of the inlet and outlet sections, noise pollution acceptability, and energy consumption – all relevant to the fans. Axial fans are commonly selected to be used in situations when there is little installation space available as they are more space saving than radial type fans and still give a high volume of air, leading to better performance.
Conclusion
In the radial vs axial fan’s battle meanwhile, there exists no complete correct answer. The choice exists solely in accordance with the specific requirements of the application. Radial fans or blowers can be used for high pressure systems, as these can operate at lower air volume. In contrast, there are axial fans which are efficient in moving large amounts of air at moderate pressure. In this context, familiarizing oneself with the main points of axial fan vs radial fan’s strength including their airflow types, pressure volume and efficiency, will enable one to make the correct choice of fan. A fan is an essential aspect when designing any of these three mechanical processes, for an air conditioning system, industrial process or ventilation schema because it optimizes performance and energy efficiency for the fan selected.
In case you need any additional direction in choosing the most appropriate axial or radial fan for your needs, get in touch with ACDCFAN. Being a registered fan manufacturer, Our focus is to supply quality products and efficient customer service to enable you get the best results in ventilation.
