Types of fans: the criteria for selecting the best varieties

Fan - the basis of any type of artificial ventilation system. The device is widely used in everyday life and is irreplaceable in many spheres of human activity. When planning the purchase of ventilation equipment, it is necessary to understand the specifics of its structure and operation.

In the present article for the inspection are detailed views of fans, their design features, the operating principles and the purpose of each unit. We'll tell you about the priorities of selecting a suitable model. You will learn how to pick up the device, depending on the operating conditions.

Classification fan General Settings

Fans - mechanical devices for moving, feeding or suction of air and gas masses. Air circulation is due to the pressure difference between the entrance channel and the exit of the ventilation installation.

Fans are used everywhere. Are indispensable instruments in the regeneration supply and exhaust ventilation Complex building, blowing the working elements in air conditioning and heating devices.

General classification of air handling units based on different parameters.

Among the main criteria for grading are:

• design and principle of operation of the device;
• the purpose and conditions of functioning of the fan;
• installation method;
• Methods device connected to the motor;
• Technical features: the degree of protection IP generated pressure, power consumption, speed, efficiency and level of acoustic pressure.

By type of construction are five versions of fans: axial, centrifugal, diagonal, diametrical and without paddles.

Based on the operating conditions, the following types of shared gazoduvnyh machines:

• general use instruments;
• Fans of special purpose.

The first group includes units designed for operation with the air and inactive gas flows, whose temperature does not exceed + 50 ° C. The second group includes special equipment: heat-resistant, explosion-proof, dust, corrosion-resistant and smoke-removing.

By way of installation are distinguished:

• standard - installing on a support;
• Roof - mounted on the roof of the building;
• channel - posted inside the ventilation duct;
• multispectral - model designed for connection to a plurality of air channels.

The electric motors are used as drive the air handling unit.

There are several possible ways of coupling the engine to the propeller:

• direct connection;
• V-belt drive;
• continuously variable coupling.

After determining suitable ventilator species selected model with optimal characteristics.

The principle of operation of different types of devices

The main criterion for selecting the fan - its structure and operation principle. Design features and technical details determine the effectiveness of the device, the noise level, efficiency of operation and the possibility of its application in certain circumstances.

Axial machine - classic fan

Axial (axial) fan is widely exploited in the household ventilation systems of private homesIn extracts of toilets in exhaust varintah complex, as different element cooling appliances and electronics, as well as in wind tunnels and turbofan engines for aviation.

The design of models is characterized by simplicity of performance and small size. The basic elements: a cylindrical body, the wheel paddle and the drive. The inner diameter of the cylinder must provide unimpeded revolutions of the impeller. The interval between the blades and the housing is limited to 1.5% of a rotating blade length.

Principle: rotating blades capture the air and push it along the impeller axis. Moving air flows in the radial direction is almost absent. Productivity of the equipment is adjusted by rotating blades.

Distinctive features of the axial models:

• It does not require a large space for installation;
• economical consumption of electric power;
• low noise levels;
• ease of operation and maintenance;
• low cost.

Advantages of work and the use of axial fans led to their widespread popularity in the home. Mass housing model used for cooling appliances and portable units with axial bars.

Centrifugal model - strength and high power

Centrifugal (radial) fans are highly efficient - units are capable of generating high pressures and operated in harsh environments. hardware design includes the following elements.

Housing. Diffuser casing made of sheet metal riveted or welded. The hollow body has a spiral shape of the cochlea in the construction provide the suction and discharge pipes. To stiffen the casing reinforced ribbing or transverse stripes.

Working wheel. A blade rotor consists of two disks, the blades and the hub.

wheel design determines the conditions for the use of the fan:

• diskless - transport streams with solid components;
• single disc - moving air environments with low content of solids;
• double disc - the circulation of clean air masses at different pressures;
• Three-disk - ensuring double inlet.

Fixing the wheel to the shaft occurs by means of hubs. By the disc and the hub are fixed blades.

Shoulder blades. Performance and efficiency of the unit as a whole is largely dependent on the shape of the blades:

• aerodynamic wing - noiselessness provides good performance metric, the device resistance to high temperatures;
• curved back - prevent accumulation of dust inside the fan, suitable for operation in environments with high depression;
• bent forward - fans "front" edges are designed to operate with a large air volume and high pressure, are resistant to erosion;
• Radial - installation of compact size with the average efficiency of the rotor guides processed protective structure from erosion.

In wheels with "rear" blades difference indicators static and total pressure is not large, therefore a high level of efficiency. The efficiency of as high as 80%.

The centrifugal air installations enters axially pushed - radially. Air masses move in the cylindrical body by centrifugal force.

The whole process can be divided into several stages:

1. When rotating the wheel air rushes to the edge of the rotor between vanes space.
2. As a consequence, it is formed with a low pressure zone in the wheel center. This leads to suction air mass from the outside.
3. In the center of the chamber air flow to change direction axial to radial, acting in the compartments between the vanes.
4. Due to the rapid rotation of air masses flock to the inner wall of the housing.
5. Kinetic energy is partially transformed into the energy of compression and velocity of the air decreases - within the "snail" going volumetric airflow and an excessive pressure.
6. The gaseous mass rushes to the outlet conduit enters the pipe, and then - in the working area.

Centrifugal units are used in supply and exhaust of large complexes, garages, shopping centers and buildings that require continuous ventilation powerful.

Diagonal - a combination of axial and radial fan

Diagonal model - a synthesis of the two types of fans: axial and centrifugal. Impeller device has a special shape - impeller structure resembles the drum device in a radial fan. The blades of the impeller are arranged parallel to the rotation axis.

Combined fans have a cylindrical body and looks more like the axial model. However, the principle of operation they have different due to the design features of the impeller. The air moves along the first axis and then changes its direction by 45 °.

The main advantage of mixed type fan - to achieve a compromise between the values ​​of the noise characteristics, performance, and device dimensions.

More often axial-centrifugal machines are used as channel fans in small and medium-sized ventilation systems with long ducts. Use as handling units and in the pressure supply pritochniki type systems.

Tangential installation - uniform airflow

Tangential (diametral) fan includes elongated body equipped with a cone and socket, and a drum type impeller with inclined blades. Implemented double air cylinder moving perpendicular to the axis of rotation.

Otherness diametrical devices:

• high aerodynamic performance;
• the ability to supply a uniform flow;
• for expanding the fan, choosing the direction of air flow;
• quiet operation;
• highest efficiency - up to 60-70%.

Scope: creating air curtains, fan coil units and the use of split-systems.

Bladeless fan - innovative technology

Household lipless fans not so long ago appeared on the Russian market of ventilation systems. Their operating principle is fundamentally different from the modifications discussed above.

device components:

• frame round or oval shape designed for retraction and release of air mass;
• a base for fixing the frame;
• mini-turbine, mounted in the fan base;
• motor.

Innovative fan works on the following principle:

1. After switching on the motor is operated turbine.
2. Rotating turbine pulls air through perforations in the housing base.
3. the air is accelerated by the turbulence 15 times in and out through outlet slits, located on the perimeter of the frame.

Air currents envelop surface of the ring, and move in the desired direction.

In comparison with traditional models fans without blades They have a number of advantages:

• continuous adjustment of the intensity of the air flow;
• convenience and absolute safety of use;
• change the air direction by adjusting the position of the ring;
• efficiency - energy consumption by 20% compared with axial models.

The main disadvantages of the device: the high cost and high noise levels.

Depending on the operating conditions

When choosing a fan is important to consider the conditions for its use. For use in corrosive environments developed highly specialized installation.

The units to be used in normal conditions

General purpose fans are made of carbon steel.

Devices are allowed to be installed in compliance with the mandatory conditions:

• the dust content in the air for radial aggregates - no more than 0.01 g / m, for axial devices - up to 0.01 g / m;
• media temperature - to + 50 ° C;
• in the absence of air, chemically aggressive, explosive components, fibers and stickies particles.

Gazoparovozdushnaya medium must not provoke accelerated corrosion processes, metal fracture permissible speed - 0.1 mm. If the operating temperature rises above the limit value, the operation of the engine deteriorates, which is usually located in a stream of air masses moved.

utility model is used in systems air heating and ventilation of public, residential and industrial buildings, as well as other sanitary purposes.

Ventilation systems for special purposes

Fans of special purpose can be subdivided into five groups:

• dust;
• heat-resistant;
• explosion-proof;
• corrosion-resistant;
• smoke-removing.

Dust aggregates used for cleaning air masses of dust and dirt particles: wood and metal filings, welding slag, grain waste. The flow of air passing through the nozzles, changes its direction from axial to radial. By centrifugal force and changes the speed of the airflow.

Radial dust of low power fans are installed on vehicles transporting grain compositions. High-pressure devices are used in large industrial plants.

Resistant units are designed to move air whose temperature exceeds + 80 ° C.

Due to severe operating conditions the fans must have special characteristics:

• insulation of the motor and its removal outside the airflow;
• High level of engine protection - IP44 and above;
• manufacturing structural elements of heat-resistant material (a heat-resistant polyamide, aluminum alloy, stainless steel or carbon steel);
• wide operating temperature range.

Heat-resistant fans are used in the regeneration ventilation system baths and saunas, discharge of high temperature exhaust air from the fireplace or furnace the removal of combustion products from the production sites.

Explosion ventilating equipment is designed for removing explosive gas mixtures. This category includes compounds in which the smallest particles in fire ignites the remainder of the gas volume.

to the explosion-proof electrical equipment requirements are regulated by directives ATEX EC. Depending on the extent of hazardous areas ventilation systems can be protected:

• quartz or oil filling shells of conductive parts;
• Encapsulation - a polymeric material;
• flameproof coating.

Input collector material fabrication, impellers, casing serves as stainless steel, aluminum alloys and dissimilar materials group: stainless steel, brass, bronze, electrically conductive plastic.

Corrosion fans are designed for transporting aggressive non-explosive the air-gas mixture with a low content of dust and lack of fiber and stickies components.

Materials of manufacture of the device parts: titanium alloys, polypropylene, vinyl liner. Alternatively, the operating elements are deposited corrosion resistant coating - grade stainless steel or titanium alloy 08H13.

Scope "protivorzhaveyuschih" fans:

• ferrous metallurgy;
• technological lines for the production of mineral fertilizers;
• carbon production;
• air supply to the fluidized composition with boilers;
• organizing the circulation of water vapor impurities of phenol, alkali and hydrogen sulfide;
• line by-product coke plants.

Smoke fans - powerful refractory installation, built into the ventilation system of the building and working on blowing the smoke out of the room. For units to meet high technical requirements.

Scope - smoke ventilation systems of buildings for different purposes. "Sucker" are installed on the roof of the premises with the help of a mounting flange and connected to the smoke-removing ducts.

Regardless of the fan design may be two- or four-sided emission of smoke in the horizontal or vertical direction. There is a possibility of functioning units in the general ventilation mode at home.

Types of fan mounting method

As indicated above, the method of mounting the ventilation devices are divided into 4 groups: standard, roof, and multispectral channel.

Conventional fans, usually come with the supporting frame or holder. Their installation does not cause any problems.

Rooftop units are installed on the roof of the buildings and perform the final link in the ventilation system of the building. Such fans are exposed to adverse environmental factors (rain, snow, wind gusts), and therefore are made of high-strength materials. Almost all models are equipped with a protective cone, warning clogging the body.

When choosing a roof fans consider the specifics equip premises. For example, for kindergarten, hospital or school selected a model with low noise. For the production hall will be a priority of equipment capacity.

Duct ventilation systems placed in the air ducts and carry the hood and air flow through the duct system. The construction of the channel of fans usually diagonal or radial type, at least - axial.

Device selection is performed with reference to the shape of the duct. Produced units for round, square and rectangular shafts.

Multi-zone air handling units are equipped with the body, allowing to connect several suction ducts, which come from different bands. Such fans are indispensable in areas where it is required to equip the hood in different rooms, and a discharge duct only one.

An additional advantage - simpler operation. You must serve the one, and not a few fans.

Variety of domestic ventilation models

Domestic fans further classified according to the installation site.

Window. The device is mounted in the window or the wall near the window, there is no ductwork. Such equipment is mainly used in public places: cafes, hairdressers, etc. Self tie-in installed PVC windows problematic.

Kitchen. Display the various pairs and odors generated during cooking. The fan is mounted directly in the exhaust hood. On the basis of their construction flat, dome and built-in hood. Kitchen fans should be heat-resistant and have an outer protective net.

Equipment for bathrooms. To improve the efficiency fume toilet and bathroom ventilation used false wall, and ceiling fans. Compact units are economical and easy to install.

Regardless of the type of fan, special attention should be paid to the marking device - namely, the degree of IP protection. IP standard describes the security equipment in the non-aggressive environment.

Level of protection against moisture entering the inside of the second housing indicates the number of marking.

Conclusions and useful videos on the topic

Video # 1. The principle of operation and the competitive advantages of bladeless fan:

Video # 2. The device is a centrifugal fan VTSUN:

Video # 3. The construction of the channel of the round form of the fan:

Model performance and technical-operational characteristics of the fan allows to choose the most suitable equipment for both domestic and industrial applications. The design of ventilation systems are constantly improving, adapting to the needs of customers.

There were questions in the process of familiarization with the article? Want to report useful in the selection of the nuances of the equipment? Please write comments in the block, located below.