Types of ventilation systems: supply, exhaust and others. Types of ventilation

Ventilation is one of the main engineering systems modern buildings. If in residential buildings it is not yet as popular as the norms require, then in public and industrial buildings it is designed and arranged almost everywhere.

Let us consider in more detail what types of ventilation are, how are these systems classified and how do they differ?

Modern ventilation systems are of different types and, depending on their purpose, are divided into several subgroups. This division is carried out according to several parameters: the direction of air movement, the method of setting the air masses in motion, the service area.

Ventilation in the house

What is the ventilation in the rooms in the direction of air movement? According to this parameter, the systems are divided into two large groups:

• supply;
• exhaust.

There is also ventilation and its classification according to the factor that sets the air in motion. According to this parameter, they are divided into:

• with a natural impulse (natural);
• with mechanical motivation (mechanical, forced).

There is also a division of ventilation and the types of which vary, depending on the serviced area. According to this principle, ventilation systems are divided into:

• general exchange:
• local (local).

All considered types of ventilation systems can be used both separately and together in one building or even a room.

Systems can also be classified into ducted and non-ducted, depending on whether they use ducts or move air through holes in the walls or fans without pipes connected.

Let us analyze in more detail all types and subtypes of room ventilation systems, how they differ and what their tasks are.

natural ventilation

As already mentioned, natural ventilation is one of the popular varieties of modern systems. This type of room ventilation means that the air is set in motion by natural factors. More precisely, it is the pressure difference between the internal volume and the external atmosphere. For its operation, it is necessary that the pressure outside is slightly less than indoors. If such a factor occurs, the movement of air begins through specially arranged ventilation ducts.

natural ventilation

A striking example of such ventilation is the installation of exhaust ducts in the walls of multi-storey and private houses. The main positive factor in the use of natural ventilation is low cost. There is no need to use expensive equipment and organize a connection to electricity. Air exchange takes place on its own. But you need to keep in mind that there are also negative aspects of using such a system. First of all, it depends on the parameters of the atmosphere.

Every building must be equipped with an efficient ventilation system, because constant air exchange is as important as good system heating or quality water. Scientists have long established a connection between the development of a number of negative phenomena in homes and improper ventilation. Thus, good indoor air exchange is necessary not only to extend the life of the building, but also to maintain our health.

Why is ventilation needed?

The main purpose of ventilation is an organized supply to the room fresh air and subsequent replacement (or removal) of polluted air. Air exchange should be carried out with a certain frequency. In buildings with poor ventilation, a lot of dust, microscopic chemicals accumulate (regular use of products household chemicals). high humidity contributes to the formation of mold, and in the air there is a high concentration of fungal spores.

A person working or living in such a building may complain of burning eyes, headaches, trouble concentrating, and fatigue. High humidity in buildings and poor ventilation indoors leads to condensation and the formation of moisture droplets on ceilings and walls.

Such conditions become ideal for the development of fungi that negatively affect human health and lead to the gradual destruction of the building. Also, these factors are very often the cause of most respiratory diseases, and for people prone to allergies, they pose a serious threat to their health.

Classification of ventilation systems

Ventilation systems are classified in four main ways:

1. According to the method of creating an air flow for circulation:

• artificial ventilation;
• with natural drive.

2. By appointment:

• exhaust systems;
• supply.

3. By service area:

• general exchange systems;
• local.

4. By design:

• channelless systems;
• channel.

The main types of ventilation

There are the following main types of ventilation systems:

1. Natural.
2. Mechanical.
3. Exhaust.
4. Supply.
5. Supply and exhaust.
6. Local.
7. General exchange.

natural ventilation

As you might guess, such ventilation is created naturally, without the use of ventilation units, but only through natural air exchange, wind flows and the temperature difference between the street and the room, as well as due to fluctuations in atmospheric pressure. Such types of ventilation are relatively inexpensive in cost, and most importantly, they are easy to install. However, such systems are directly dependent on climatic conditions, therefore they are not able to cope with all problems.

Mechanical

When the forced replacement of the exhaust air with a fresh stream is carried out, this is mechanical ventilation. AT this case special equipment is used that allows you to remove and supply air to the room in the required volume, regardless of changing climatic conditions.

In such systems, the air, if necessary, is subjected to various types processing (humidification, dehumidification, cooling, heating, cleaning and much more), which is almost impossible to organize in natural ventilation systems.

In practice, mixed types of ventilation are often used, which simultaneously combine mechanical and natural systems. For each specific case, the most optimal method of ventilation is selected in terms of sanitary and hygienic terms, and also so that it is technically and economically rational. The mechanical system can be installed both for the entire room (general exchange), and at a specific workplace (local ventilation).

Supply

Through the supply systems, a clean air flow is supplied to the ventilated premises, which replaces the polluted one. If necessary, the supply air is subjected to special treatment (humidification, heating, cleaning, etc.).

exhaust

Such a system is designed to remove polluted air from the premises. In most cases, the premises provide for both exhaust and supply types of ventilation. It is important that their performance is balanced, taking into account the possibility of air flow from adjacent rooms or into adjacent rooms.

Also, only supply air or only exhaust system. In this case, the air enters the room from adjacent rooms or outside through special openings, or flows into adjacent rooms, or is removed from this room to the outside.

local ventilation

This is a system in which the air flow is directed to a certain place (local supply system), and polluted air is removed from the places of accumulation of harmful emissions - local exhaust (ventilation).

Local supply system

Air showers (concentrated air flow with increased speed) are local supply ventilation systems. Their main task is to supply clean air to permanent workplaces, reduce the air temperature in their area, and blow air to workers who are exposed to intense thermal radiation.

Air curtains (at stoves, gates, etc.) are also local ventilation systems, they change direction or create air barriers. Such a ventilation system, in contrast to the general exchange, requires lower costs. In industrial premises, when emitting harmful substances (heat, moisture, gases, etc.), it is usually used mixed scheme ventilation: local (inflow and local suction) - for and general - to eliminate harmful air in the entire volume of the room.

Local exhaust system

When hazards (dust, gas, smoke) and heat are emitted locally, for example, from a stove in a kitchen or a machine in production, a local exhaust ventilation system is used. It captures and removes harmful emissions, preventing their subsequent spread throughout the entire volume of the room.

These systems include local and onboard suction, and much more. Also referred to as local exhaust ventilation air curtains- air barriers that prevent air flow from the street into the room or from one room to another.

General ventilation

Such a system is designed to ventilate the room as a whole or a significant part of it. The general exchange exhaust ventilation scheme provides for the removal of air from the entire serviced premises evenly, and the general exchange supply system supplies the air flow and distributes it throughout the volume of the premises.

Natural or mechanical system: which one to choose?

For a comfortable existence, a person needs not only heat, but also clean, fresh air. Moreover, a person needs fresh air constantly and in large quantities. The volumetric velocity of the air flow in the room is also important. With a natural system, the speed is much lower than with mechanical ventilation.

But the air exchange, which is achieved through a mechanical system, is much higher than with natural ventilation.

In addition, with a mechanical system, compared to natural ventilation, they are smaller. This is due to the normalized speed of air flow in ventilation systems. According to SNiP "Heating, ventilation and air conditioning", for a mechanical system, the air velocity should be from 3 to 5 m / s, for natural ventilation - 1 m / s. In other words, in order to pass the same volume of air through the system, natural ventilation will have duct sizes 3-5 times larger.

Very often, when building buildings, there is simply no way to skip such large channels. In addition, with a natural system, the length of the air ducts cannot be large, since the pressure created by the difference in air densities is very small. In this regard, when large areas simply can not do without mechanical ventilation.

Room ventilation - the main components

The composition of heating, ventilation and air conditioning includes a mass of units that provide highly efficient circulation of air masses in the room. It is important that the ventilation project, as well as the placement of devices, be carried out in accordance with the current rules and regulations (TKP, SNiP).

Ventilation systems can be equipped with channels or not have them - it all depends on the design features of the room.

It is important to remember that ventilation is a serious and significant element, so both the design and selection of equipment must be approached competently. It is also worth noting that universal and a wide variety of units are used to organize controlled air exchange. Fans are considered the most affordable and simple - they can be radial, axial and diametrical.

In addition, ventilation units can be installed indoors, which are mounted in special channels - air ducts, or on the roof of buildings. It also involves the installation of air valves, dampers, distribution elements and gratings, which make it possible to make the movement of air flow in the room as efficient as possible.

Main parameters of ventilation systems

1. Performance. When calculating this parameter, it is necessary to take into account the number household appliances, the number of people living in the house, as well as the area of ​​\u200b\u200bthe premises. It should be calculated how much time and how much volume the ventilation system will need to remove polluted air and then fill it with clean air. For cottages, the most optimal value of air exchange is considered to be from 1000 to 2000 m 3 / h. To calculate the area of ​​\u200b\u200bthe room is multiplied by its height and by 2.
2. Noise level. The higher the ventilation speed, the higher the noise level. No need to purchase too "fast" systems. If the first point is calculated correctly, then you will be able not only to save your budget, but also to have a restful sleep. In this case, the installation of ventilation will be correct. Also, do not buy air ducts with low performance, as they will be difficult to install correctly, and they will not be able to withstand the load during operation. For a cottage, an acceptable average airflow velocity is from 13 to 15 m/s.
3. Another important parameter is power. The temperature of the air entering the room is regulated by the heater. According to SNiP "Heating, ventilation and air conditioning", the temperature should not exceed +16°C. Depending on the intended installation location of the device, the power of the heater is calculated. It is important that it can work even at sub-zero temperatures in winter period time. When choosing power, you should focus on the maximum plus and minus temperature indicators. If the street is maximum subzero temperature-10°C, the heater must heat the air by at least 26°C. For example, for office space up to 50 kW of power can be used, 1-5 kW is quite enough for an apartment.

scheme and installation - the main stages

Even at the design stage, it is necessary to determine the attachment points for ventilation equipment, both main and auxiliary. In this case, there are some restrictions - it is not recommended to install the equipment above heat sources (stove, fireplace, etc.). It is important that the ventilation project fully complies with the requirements that apply to regulatory and technical documentation.

Device ventilation system involves the following main steps:

1. Preparation.

• The marking of the places of the proposed installation of ventilation devices is being carried out.
• Taking into account the margin (2-3 centimeters), holes are hollowed out. The stock is required for comfortable installation of the system.
• The edges of the holes are cleaned.

• The front part of the fan is installed in the pipeline section.
• Then the design is placed in the hole.
• The space between the fan and the wall is filled with foam.

3. Electrical installation.

• Grooves are made in the wall for the cable.
• The cable to the fan is laid in the resulting holes.
• The cable is fixed with brackets.

4. Finishing work.

• A protective box is installed on the fan switch.
• All joints of the ventilation system are smeared with sealant.
• Furrows with wiring, as well as the junction of the system to the wall, are plastered and puttied.

The system is completely ready to start. This is a simple ventilation, the price of such a system will depend on the cost of the fan.

Conclusion

Heating, ventilation and air conditioning systems are an integral part modern office, house or any other property. These systems consist of the most innovative and modern units, designed depending on the design features of the building, allowing you to save a lot on heating.

It is important to remember that a well-designed and installed ventilation system is the key to creating an optimal microclimate in the room.

Ventilation is a set of devices and measures to ensure normal air exchange in the premises. Ventilation systems maintain acceptable meteorological parameters in rooms for various purposes.
Ventilation systems are divided into several types:

• by way of air circulation: natural and forced (mechanical);
• by appointment: supply and exhaust;
• by service area: general exchange and local;
• by design: channel and channelless.

natural ventilation

In natural draft air exchange systems, air movement occurs due to various factors:

• temperature difference between atmospheric and room air (aeration);
• pressure difference of the "air column" between the lower level (served premises) and the upper level - an exhaust device installed on the roof of the building;
• as a result of wind pressure.

Natural ventilation systems do not require large investments in ventilation equipment, are easy to install and do not require electricity to operate. However, their operation depends on variable factors such as air temperature or wind direction and speed. In addition, a small available pressure limits their operation.

mechanical ventilation

Mechanical ventilation systems operate on the basis of ventilation equipment and various devices that allow air to be moved over considerable distances. Their work can require very significant energy costs.

However, a significant advantage of mechanical ventilation systems is that they can supply and remove air in required quantity independently, regardless of conditions environment. If necessary, the air can be processed (cleaned, heated, cooled).

One of the attempts to combine the advantages of natural and mechanical ventilation systems has been the creation of so-called mixed systems. A typical example of such a system is Aereco ventilation.

The type of ventilation that is optimally suited to a particular room is determined at the design stage, based on sanitary and hygienic conditions, as well as on the basis of economic and technical considerations.

Supply and exhaust ventilation

Supply ventilation is used to supply fresh air to the premises instead of the remote one. In necessary cases, the supply air is subjected to pre-treatment.

Exhaust ventilation systems remove exhaust air from rooms. The composition of the hood, as a rule, includes ventilation grilles and exhaust fans, as well as air ducts that form a network of ventilation ducts through which air is removed to the outside.

In practice, supply and exhaust ventilation systems are used in pairs. At the same time, their performance should be balanced, taking into account the possibility of air entering adjacent rooms. Also, there is only a supply ventilation system in the room, or only an exhaust one. Air enters the room from the outside through special openings or mounted supply devices.

Supply and exhaust systems can be organized at the workplace ( local) and for the entire room ( general exchange).

local ventilation

At local ventilation air is supplied to certain places ( local supply system), and is removed only from the places of formation of harmful emissions ( local exhaust system).

Local ventilation is one in which air is supplied to certain places (local supply) and polluted air is removed only from places where harmful emissions are formed (local exhaust).

local forced ventilation

Local inflow systems are divided into air showers and air oases. The task of the air shower is to serve fresh air to workplaces, as well as to reduce the air temperature in the inflow zone. Air oases are areas of premises isolated by partitions, where air with a lower temperature is supplied.

Air curtains are also used as local supply ventilation, which create, as it were, air partitions or change the direction of air flows.

Local ventilation is much less expensive than general ventilation. In industrial premises, a mixed type of ventilation is often used - general exchange to eliminate harmful emissions throughout the room, and a local ventilation system to service workplaces.

Local ventilation is less expensive than general ventilation. In industrial premises, when hazards (gases, moisture, heat, etc.) are released, a mixed air exchange system is usually used - common to eliminate hazards throughout the entire volume of the premises and local (local suction and inflow) to service workplaces.

Local exhaust ventilation

Ventilation systems of this type are used to remove harmful emissions from local areas of the room, when their distribution over the entire area can be avoided. In industrial premises, local exhaust ventilation ensures the capture and removal of harmful substances(gases, dust, smoke, etc.) with the help of suctions (shelters in the form of cabinets, umbrellas, side suctions, curtains).

Local exhaust ventilation is used when the places of harmful emissions in the room are localized and it is possible to prevent their spread throughout the room.

The local exhaust system in the production premises ensures the capture and removal of harmful emissions: gases, smoke, dust and heat partially released from the equipment. To remove hazards, local suctions are used (shelters in the form of cabinets, umbrellas, side suctions, curtains, shelters in the form of casings near machine tools, etc.).

Local exhaust ventilation systems are very effective, as they allow you to remove harmful substances directly from the place of formation, preventing them from spreading throughout the room.

However, they cannot solve all problems, for example, the removal of secretions dispersed over a large area or volume. In this case, general exchange types of ventilation systems are used.

General ventilation

General ventilation is designed to provide air exchange throughout the room or in a significant part of it. General exchange exhaust systems evenly remove air from the entire room, and supply systems supply clean air, distributing it over the entire area.

General supply ventilation

The system is designed to assimilate excess heat and moisture, dilute harmful concentrations of vapors and gases that have not been removed by local or general exhaust ventilation. It also ensures compliance with the calculated sanitary and hygienic standards and free breathing in the work area.

With a lack of heat, supply ventilation of a general type is organized with mechanical stimulation and heating of the supply air. Before supply, the air is cleaned of dust.

General exhaust ventilation

The simplest type of general exhaust ventilation is a fan (usually axial) located in a window or wall opening. It removes air from the zone closest to it, carrying out general air exchange.

Sometimes the system has an exhaust duct. If the length of the exhaust duct exceeds 30-40 m and, accordingly, the pressure loss in the network is more than 30-40 kg / m2, then the axial fan is replaced by a central one.

In industrial buildings, it is rarely possible to get by with one ventilation system (local or general) due to heterogeneous harmful emissions and various conditions their entry into the premises. In such cases the best option is a device of general exchange exhaust ventilation system.

In certain cases, natural systems based on aeration may be used along with mechanical ventilation.

Channel and non-duct ventilation

Ventilation systems may have an extensive network of air ducts to move air (duct systems). Also, there may be no ventilation ducts (channelless systems) if the fan is installed in a wall (ceiling), with natural ventilation, etc.

Any ventilation system is characterized by four features: purpose, service area, method of air movement and design.

general information

The word "ventilation" comes from the Latin "ventilatio", which means ventilation. It is understood as regulated by means of technical means air exchange in order to create the most favorable and comfortable conditions for a person in residential, industrial and other premises.

Usually, in any premises, due to the leakage of windows, doors and other fences, infiltration of the outside air always occurs, that is, there is a natural air exchange, which is commonly called unorganized. Ventilation is an organized air exchange using various technical means - air handling units , fans, chiller-fan coil systems and so on.

The main characteristics of air exchange include such parameters as the volume and frequency of air exchange. Volume is the amount of air in cubic meters supplied to the premises within an hour. The minimum air exchange rate for one adult is 30 m³ / h, for a child - 20 m³ / h.

The air exchange rate is the number of times the air in an enclosed space changes in an hour. Depending on the type and purpose of the room, air exchange rates are set. So, for example, for living rooms a multiplicity of 0.5-1.0 is recommended, and in kitchens the air should change more intensively and the recommended multiplicity is 3.0. For industrial premises, this indicator can vary greatly depending on the type of production or activity carried out in these premises.

When the air exchange rate is less than 0.5 per hour, a person begins to feel uncomfortable, there is a feeling of stuffiness, a decrease in efficiency, etc.

Ventilation efficiency

It shows how quickly the exhaust air is removed from the room and is determined by the percentage of the concentration of harmful impurities in the exhaust air to the concentration of harmful impurities in the room.

Efficiency determines the quality of air exchange and shows how the ventilation system is able to provide comfortable conditions for air purity. This indicator of air exchange directly depends on the geometry of the room, the relative position of the supply and exhaust ducts, the density and distribution of sources of harmful impurities, etc.

Another parameter that determines the quality is the coefficient of air exchange.

is the percentage rate of air replacement in the room, which can be determined by the formula:

This parameter depends on the conditions of air distribution in the room, the location and geometrical parameters of diffusers, the location of heat sources, etc. Currently, there are two types of air exchange in indoors- Ventilation by mixing and displacement.

Displacement ventilation allows you to get an efficiency value of over 100%, while mixing - no more than 100%. The air exchange ratio can reach values ​​from 50 to 100% when using displacement, and does not exceed 50% when agitated.

It is the most effective method air exchange at industrial facilities. In addition to industrial facilities given type very popular in the device, the so-called comfort ventilation systems. With a properly calculated scheme, this method of air exchange allows you to achieve the highest air quality indicators.

This type air exchange works according to the following principle: air is supplied to the lower level and flows into the working area at a minimum speed. Under working area refers to the part of a room or space occupied or used by people. As a rule, the working area is considered to be a space spaced 50 cm from the walls and window openings and from 10 to 180 cm above the floor.

In addition to the working area, there is an adjacent area. Surrounding area- this is the space around the supply diffuser, where the air has its own local velocity. Comfort ventilation implies that the air velocity near the diffuser should not exceed 0.2 m/s.

For the displacement principle to work, the supply air supplied to the working area must have a slightly lower temperature than the room air. For comfort systems, the supply air temperature should be 1-3°C lower than room temperature, and for industrial buildings or special systems, 1-5°C. If the supply air temperature is too low relative to the main room air temperature, there is a risk of convection currents.

Displacement ventilation has a number of advantages and disadvantages.

Advantages:

• easy to use in industrial buildings and facilities, with significant emissions of harmful impurities and thermal energy;
• has a high efficiency and ensures high air quality.

Disadvantages:

• supply diffusers of such a ventilation system require wider areas for placement;
• supply diffusers can be accidentally cluttered and efficiency will be significantly reduced;
• the adjacent zone is expanding significantly;
• the vertical temperature gradient increases.

The vertical temperature gradient is understood as the temperature difference between the supply air and the air under the ceiling. The optimal temperature difference for residential premises should be within 2-3 ° C.

When designing ventilation according to the displacement principle, it is important to consider mutual arrangement heating devices, as well as their power. The dynamics of air flows inside the room depends on this. The supply air supplied from the diffusers to the working area from below can be mixed with extraneous air currents, and therefore there is an uneven heating of the air layers along the height and, in some cases, a displacement of warm air down. In practice, this means that displacement air exchange has changed to mixing.

When mixing, the supply air is supplied in one or more streams to the working area and entrains large volumes of air inside the room. The work zone is in the return flow zone where the air velocity is approximately 70% of the supply air velocity.

Mixing ventilation has a number of parameters that characterize it.

Jet length- this is the distance from the source-distributor to the section of the air jet where the speed of the flow core drops to 0.2 m/s.

ejection- this is the process of mixing any two media, in which one medium, being under pressure, affects the other and carries it away in the required direction. In our question, ejection is understood as the ability of diffusers to mix adjacent room air into the supply air jet.

One of the supply devices with a high degree of ejection can be attributed jet-type diffusers, where the air, passing to high speed through the nozzles, twists. Such diffusers are used for mixing devices, while displacement uses low ejection inlets.

In order to reduce the effect of drafts when the supply air temperature is lower than the room air temperature, the diffusers should have as high an ejection degree as possible.

Covering effect. If the ventilation inlet is too close to a flat surface, the supply air stream tends to deviate towards this surface and flow directly along its plane. This effect is achieved due to the rarefaction of the atmosphere between the supply jet and the bounding flat surface, and since there is no possibility of mixing air into the supply stream, it deviates towards this surface.

If air exchange requires the creation of a flooring effect, then the inlet should be located at a distance of no more than 30 cm from the bounding surface.

Air speed and temperature. One of the important factors in the feeling of comfort in the room is the absence of drafts. This effect is achieved when the air speed is less than 0.18 m/s and its temperature is within 20...22°C. At the same time, the speed of air movement in the room depends on such factors as the geometry of the room, the air temperature in the working area, the purpose of the room, the interior, etc.

Obstacles. When designing ventilation, the presence of physical obstructions must be taken into account. Physical barriers include ceiling lamps, ceilings, tiers (if the ceiling is multi-tiered), etc. The supply air jet is most likely able to go around an obstacle if it does not exceed 2% of the ceiling height.

Classroom ventilation

Auditoriums and classrooms are specific rooms - a large work zone, high ceilings, a significant number of people. Updating the air masses of such premises requires a special approach. One of the most common ways of air exchange in such premises is the organization of the supply of fresh air under the seats. This is done with the expectation that the supply air will heat up and rise up under the influence of heat. However, in practice this does not always work.

Air tends to behave like a liquid, and before rushing up, it flows down and accumulates, and only then rises up and rushes to the exhaust holes. In this regard, sometimes it is advisable to place diffusers in the front of the classrooms and classrooms. This can be illustrated as follows:

Despite theoretical calculations and computer simulation of the behavior of air flows, in practice it is quite difficult to achieve real displacement ventilation, it is necessary to take into account a number of factors such as the number and relative position of diffusers, the presence and location of heat sources, the interior of the room and other factors. In practice, this means that the replacement of air by displacement is in fact mixing.

Some experimentation with the placement and geometry of diffusers has shown that mixing ventilation can be quite satisfactory. So, for example, air mixing has shown good results when the exhaust openings are located at the rear of the room (directly above the door). However, when the exhaust openings were located in other parts of the room, it led to the formation of short-circuited flows.

If the auditorium has an entrance door at the back of the room, then the ventilation of this part is especially important. Air exchange in the back of the room does not allow the formation of a wall of warm and exhaust air.

natural ventilation

It is caused by the temperature difference between the outdoor and indoor air, as well as by the strength of the wind. It works as follows. Wind currents act on one side of the building, putting pressure on it and driving fresh air into the room. Whereas with opposite side the building creates a rarefied atmosphere and the exhaust air from the room tends to break out.
Natural ventilation largely depends on the structure of the building material of the walls of the building. Materials such as wood and concrete have good air permeability and are able to provide sufficient air exchange in the premises. Here is the concrete Oil paint, plaster significantly reduce air permeability.

In order for natural ventilation to be more efficient, they resort to the use of windows, vents, transoms, which allow outside air to freely penetrate into the room. One of the most common methods for air exchange in apartments is exhaust ventilation ducts, usually located in kitchens, bathrooms, and toilets. These channels from the rooms lead to the roof of the building, where they end with special nozzles - deflectors, which, due to the wind, enhance the effect of air mass renewal.

However, in large housing systems (for example, in high-rise buildings), ventilation of apartments using ventilation ducts is not always effective. Sometimes the so-called “draught overturning” occurs, when instead of removing the exhaust air from the room, reverse processes occur - through the channels, the outside air enters the room along with dust and odors.

In this case, it is advisable to install fans in the ventilation ducts. However, too powerful fans installed in one apartment can expel air not only to the roof, but also to neighboring apartments.

mechanical ventilation

One of the modern and most effective ways organized indoor air exchange is mechanical ventilation. It is using electric motors, fans, air heaters, filters, automation, etc. allows air to be transported over long distances.

However, unlike natural ventilation, mechanical ventilation requires electricity, sometimes quite significant. This type of system allows for high-quality air exchange in the premises, regardless of the volume of exhaust and supply air, in addition, the operation of such a system does not depend on weather conditions. Also, the positive aspects of the mechanical ventilation system include the fact that it allows for the processing of supply air - heating or cooling, air dehumidification or air humidification, filtration, etc., which is practically impossible with natural air exchange.

In practice, mixed ventilation is often used - both mechanical and natural. Each specific project determines the need in terms of sanitary and hygienic terms, technical terms and economic feasibility of which type of air exchange to give preference.

Fans

Fans are the main element of mechanical air exchange systems. By definition, fans are machines designed to transport low pressure gases through a network of ducts or simply from one room to another (or to/from the street).

By type and design features fans are divided into axial, centrifugal and tangential. Selected according to needs fan type, its performance, design and other technical characteristics.

Supply and exhaust ventilation

In general, ventilation should be both supply and exhaust. At the same time, the performance of both types should be balanced, taking into account the likelihood of air entering from adjacent rooms or its removal into them. Balanced supply and exhaust air exchange can significantly reduce the draft factor and avoid the “slamming doors” effect.

However, in practice, they often use either supply air (then air is removed from the room through openings, windows, vents, transoms), or exhaust air (when warm and polluted air is removed, and fresh air is supplied naturally).

Forced ventilation

Produced by means of supply installations. ventilation Supply unit serves to supply fresh air into the room instead of the removed one.

The supply unit in a modern design can be both monoblock and type-setting. Monoblock systems have a greater installation readiness and do not require special skills and knowledge during their installation, however, they are more expensive than stacked ventilation systems. To install a monoblock system, it is enough to fix the unit on the wall and bring the air duct network and power supply to it.

The supply unit has a heater, fans, a filtration system and electroautomatics for control and monitoring as the main components.

If there are special requirements for air quality, then the supply air can be subjected to additional processing such as heating, cooling, dehumidification , air humidification, cleaning with filters, etc. Air handling units there are both industrial purposes (used at industrial facilities) and household ones.

Exhaust ventilation

It is the exact opposite of the supply air and is designed to remove exhaust air from residential, industrial and other premises. There are general exchange (carrying out air exchange for the entire room) and local (installed directly at the workplace).

As a rule, exhaust ventilation justifies itself in industrial facilities, when it is necessary to remove excess heat and harmful impurities either from the entire volume of air in the room, or only from certain places. However, for apartments it can also use exhaust units - in kitchens, bathrooms, toilets. The operation of the exhaust unit can be based on the principle of natural air exchange, or it can be mechanically stimulated to move air, for example, using fans.

local ventilation

If the supply air is supplied to certain places in the room, or vice versa, the exhaust air is removed from such places, then the ventilation is called local. Distinguish between local supply and local exhaust.

Local supply- requires less operating costs than general exchange. It is mainly used in industrial premises where intensive air exchange (local suction and inflow) is necessary for servicing workplaces in order to reduce the concentration of excess moisture, heat, gases, harmful impurities, dust, etc. As a rule, it is used in conjunction with general exchange air.

Local exhaust- is used in cases where the sources of emission of harmful substances, heat and other emissions in the room are localized, and it is possible to prevent air pollution throughout the room. It allows you to achieve a good sanitary and hygienic effect with small volumes of air removed due to the fact that the removal of harmful substances occurs directly from the places of their formation or release and the possibility of their spread in the air is limited.

If, on the other hand, production work is carried out over the entire area of ​​\u200b\u200bthe room, and dirty air is distributed over a large area or in a significant volume, then it is inefficient, and other solutions are required to ensure necessary conditions air environment.

General ventilation

Designed for air exchange throughout the room, or in a significant part of it. General-exchange exhaust systems evenly remove air from the room, while the general-exchange supply system provides fresh air supply and its uniform distribution throughout the entire space of the room.

General exchange supply- used to dilute harmful concentrations of impurities in the indoor air that have not been removed using local ventilation systems. It also helps to maintain the free breathing rate of the person in the work area.

If the heat balance is negative, that is, the temperature in the room is lower than the temperature of the outside air, then general exchange supply ventilation is arranged with mechanical stimulation of the movement of supply air (for example, fans are used) and its heating. At the same time, the amount of air supplied by such a system must be sufficient to compensate for the removed one.

General exhaust — simplest type- these are ordinary fans, usually of an axial type, which are located in a window opening, a window or in a wall hole. Such air exchange is able to remove air only from the zone located directly next to the fan and performs only general air exchange.

Sometimes general exhaust ventilation uses air ducts to transport air masses. However, with a relatively long route of air ducts, a pressure loss occurs and the efficiency of air exchange decreases. Most simple solution in this situation, it is the installation of a more powerful axial fan or centrifugal fans are used.

Depending on the type and purpose of the room, one or another ventilation system is selected. In each specific case, it should be taken into account what pollutes the air - dust, excess heat, heavy gases, light gases, moisture, vapors, etc., as well as the nature of the distribution of pollutants in the volume of the room (concentrated distribution, dispersed, multi-level, etc.). e.) In some cases, it is rational to use exhaust ducts in the floor of the building, and sometimes vice versa - to transfer them to upper part premises.

As a rule, in a room of any purpose it is impossible to get by with one ventilation system, for example, only supply or only exhaust. The most efficient air exchange system is a general exchange supply and exhaust system with a mechanical drive.

Channel and non-duct ventilation

The ventilation system can be both channelless and ducted. Channelless does not have a network of air ducts, and air exchange occurs through any openings in the walls - windows, vents, transoms, etc. Channel also implies the presence of ventilation ducts through which air is transported and supplied (or vice versa is discharged) to certain places. At the same time, the channelless system is simpler and cheaper to install and operate, but it also has a lower efficiency compared to the channel system.

Air preparation

In some cases, simple air exchange in the room is not enough. If there are special requirements for air quality, then additional equipment comes to the rescue.

In summer, when the air is warmer and more humid, it is advisable to resort to the use of air conditioning systems, which allow, in addition to the air exchange process, to process air - filter and cool it. Such equipment includes household split air conditioning systems, chiller-fan coil systems, industrial air conditioners etc.

In winter, the air is colder and drier, and in addition to filtering, heating and humidification of the air can be used to prepare it.

If a apartment ventilation is a relatively simple matter, there are a number of specific rooms where air quality requires more attention.

Swimming pools can be distinguished as such premises. A large number of water, as a result, intense evaporation and subsequent condensation of moisture require constant dehumidification of the air in the pool room. Usually, well-designed ventilation adequately copes with this issue, but in some cases, the use of dehumidifiers is required. Beyond the pools air dryers widely used for dehumidification of the working atmosphere in water parks, laundries, warehouses and basements, pharmaceutical and food industries, for drying hygroscopic materials, etc. The main disadvantage of this type of climate equipment is the fact that dehumidifiers do not provide fresh air, but only process the air in the room.

By and large, all climatic equipment can be divided into household, semi-industrial and industrial.

As a rule, household equipment has a small and medium power, while industrial equipment has a higher one.

For handling large volumes of indoor air use industrial air conditioners, humidifiers, dehumidifiers and other climatic equipment.

Industrial air conditioners, by analogy with household ones, can have both a monoblock design and be a split system (they consist of outdoor and indoor units).

Sometimes in specific rooms additional air humidification is required. In this case, use industrial humidifiers. Examples of applications for industrial humidifiers are base and server stations (dry air is more prone to static electricity build-up and causes a risk of flashover), libraries and museums (paintings warp and paint cracks in low humidity), printers (paint does not mix well), textile industry(dry air reduces the strength of the yarn and causes it to break), wood warehouses (when dry, the wood is prone to warping and cracking), living quarters (maintaining a healthy and comfortable humidity level), etc.

Types of ventilation systems differ in the following parameters:

• by way of air movement: natural, mechanical and combined;
• by appointment: supplyandexhaust ventilation;
• by service area: localandgeneral exchange;
• by design: typesettingandmonoblock.

Natural and mechanical ventilation system

The movement of air flow in the ventilation system can be carried out due to natural forces or artificially due to mechanical energy.

• Natural ventilation works due to the pressure difference between the street and the room. The pressure difference depends on the temperature difference between the street and the room, the height difference between the air intake grille in the room and the top of the exhaust shaft, and on the wind speed. The advantages of the natural ventilation system, which determine its widespread use, are low capital and operating costs, and durability. Disadvantages - dependence on external weather conditions, as a result of which, during the warm season, natural ventilation works poorly or does not work at all.
• Mechanical (artificial) ventilation works due to the pressure created by the fan. The advantages of mechanical ventilation are stability of operation, air distribution through an extensive network of air ducts, system control, the possibility of air treatment (dust removal, heating, cooling, etc.)
• The combined ventilation system combines the advantages of natural and mechanical ventilation. The combined ventilation system works according to two schemes: natural supply / mechanical exhaust and mechanical supply / natural exhaust. A striking example of a combined ventilation system is a humidity-controlled one, in which air is supplied naturally through wall or window valves, and a mechanical fan-based exhaust ensures stable operation of the system.

Supply and exhaust ventilation system

• Supply ventilation system is designed to supply (supply) fresh air to the serviced premises. The influx (inflow) of fresh air is carried out both naturally and mechanically. The use of a fan allows for a variety of supply air treatment: dust removal, heating, cooling, humidification, etc.
• Exhaust ventilation, designed to remove polluted (exhaust) air from serviced premises. Exhaust ventilation can be either natural or mechanically driven.

Local and general ventilation system

• Local supply ventilation is mainly used in manufacturing enterprises with high levels of harmful emissions. In this case, the supply air is supplied directly to the human breathing zone.
• Local exhaust ventilation is actively used both in production and in everyday life (for example, household hoods in the kitchen). The main purpose of local exhaust ventilation is the local collection and subsequent removal of polluted air to prevent its distribution throughout the premises.
• General ventilation is used to create air exchange in a room or a group of rooms as a whole. General ventilation can be both supply and exhaust, with natural and mechanical stimulation.

Stacked and monoblock ventilation system

The mechanical ventilation system consists of a supply, exhaust or supply and exhaust ventilation unit, an air duct system and a set of air distributors. The ventilation unit can be of stacked or monoblock design.

• typesetting ventilation unit assembled directly at the facility from separate functional units - an air filter, a fan, a silencer, a heater, etc.
• In a monoblock installation, all functional units (air filter, fan, heater, etc.) are placed in a single soundproof housing at the factory assembly stage.

The functional characteristics of stacked and monoblock systems do not differ from each other. If there are problems in the operation of the ventilation system, they are more often caused by incorrect calculation of productivity, pressure, etc., and not by the use of a stacked or monoblock system.

The advantage of a stacked ventilation system is lower cost, flexibility in installation and repair, the advantage of a monoblock installation is lower noise level, ease of installation, more aesthetic appearance.