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Something About Centrifugal Fan

2021-06-07 hqt

With the development of the industrial sector, a large number of technological processes required forced air supply. The domestic sphere did not stand aside either. Some types of communications require a regular supply of fresh air.

An elegant solution to this problem has become a centrifugal fan, which is capable of pumping the required amount of air mass in an autonomous mode. But how does it work and how does it work? It is these questions that we will analyze in detail in our article.

The essence of air injection and rarefaction by a fan

The fan is a mechanical structure that is able to process the flow of a gas-air mixture by increasing its specific energy for subsequent movement.

Such an architecture of the unit makes it possible to create the effect of pumping or rarefying the working gas in space through an increase or decrease in pressure, respectively (energy conversion mechanism).

Gas pressure is understood as an endless process of chaotic movement of gas molecules, which, hitting the walls of a closed space, create pressure on them.

Therefore, the higher the speed of these molecules, the more impacts and the higher the pressure. Gas pressure is one of the main characteristics of gas.

On the other hand, any gas has two more parameters: volume and temperature. Volume - the amount of space that the gas has filled. Gas temperature is a thermodynamic characteristic that links the speed of molecules and the pressure they generate.

These “three pillars” are based on the molecular kinetic theory, which is the basis for describing all the processes associated with the processing of gases and gas mixtures.

The injection process is a forced concentration of molecules in a closed space above a certain norm. For example, the generally accepted air pressure at the earth's surface is approximately 100 kPa (105 kilo Pascals) or 760 mm Hg. Art. (millimeters of mercury).

With an increase in height above the surface of the Earth, the pressure becomes less, the air becomes rarefied.

Vacuum is the reverse process to pumping, during which the molecules leave the closed system. The volume remains the same, but the number of molecules decreases several times, therefore, the pressure decreases.

The pumping effect is necessary for the forced movement of air. A variant of air movement through the rarefaction effect is possible: to restore the pressure balance in the entire system, molecules move from a more concentrated area of molecules to a less concentrated one.

In this way, the movement of gas molecules occurs.

There are a variety of layouts of ventilation systems, but they can be conditionally divided into several classes according to certain parameters:

By appointment. There are general and special-purpose fans. Fans are used for normal gas movement. Special fans are used for pneumatic conveying, transportation of aggressive and explosive gas mixtures.

By speed. There are low, medium and high specific rotational speed of a wheel with blades.

By pressure range. There are systems for generating low (up to 1 kPa), medium (1-3 kPa), and high (more than 3 kPa) pressure.

Some industrial and domestic processes using blowers take place in extreme environmental conditions, so the corresponding requirements are put forward for the equipment.

Thus, we can talk about dust, moisture-proof, heat-resistant, corrosion-resistant, spark-proof units and devices for removing smoke and conventional fans.

Centrifugal fan design

The centrifugal design system is a radial architecture delivery mechanism that is capable of generating pressures of any range.

Предназначен для транспортировки одно- и многоатомных газов, в том числе химически “агрессивных” соединений.

The design is “clothed” with a metal / plastic case, which is called a protective casing. The jacket protects the inner chamber from dust, moisture and other substances that can negatively affect the operation of the unit.

There are several known options for transferring rotational motion from the motor to the impeller:

  • Elastic coupling;
  • V-belt transmission;
  • Infinitely variable transmission (hydraulic or inductive slip clutch).

Considering the existence of a huge number of manufacturers that create unique systems with a wide variety of dynamic parameters, consumers have at their disposal a fairly extensive range of fans.

As a result of the intensive work of the developers, we have a wide range of applications for such machines, including:

  • Ventilation and heating systems in private and multi-story buildings;
  • Air supply and purification for non-residential buildings;
  • Filtration systems in agriculture;
  • Execution of technological processes in light and heavy industry of various directions.

There are also options for using blowers in fire extinguishing systems and ultra-fast air change in confined spaces.

The proven and simple design of the centrifugal mechanism has several distinct advantages:

  • High reliability and unsurpassed performance;
  • Ease and availability of equipment maintenance;
  • Safety of integration and operation of units;
  • Minimum costs for energy resources and repairs in case of failure.

In addition, the blowers have a fairly low noise floor, which makes them suitable for domestic use. Centrifugal fans also have an exceptionally long service life due to the absence of direct contact between the working parts of the mechanism in the working chamber.