Types of ventilation systems: a comparative review of options for organizing ventilation systems. Types of ventilation and its classification

Local supply systems ventilation supply fresh air directly to workplace or to a place of rest. In the coverage area of the system, conditions are created that differ from the conditions in the entire room and satisfy the set requirements. Local supply ventilation includes air showers and oases. An air shower is a local air flow aimed at a person. In the zone of action of the air shower, conditions are created that are different from the conditions in the entire volume of the room. With the help of an air shower, parameters such as: human mobility can be changed; temperature; humidity; concentration of a particular hazard. Most often, an air shower is used in hot shops, in workplaces exposed to thermal radiation.

Local supply ventilation also includes air oases - areas of premises fenced off from the rest of the premises by movable partitions 2.0 - 2.5 meters high, into which air with a lower temperature is injected.

Local ventilation is less expensive than general ventilation.

General exhaust ventilation

Exhaust ventilation is used to remove polluted or heated exhaust air from a production or living space (workshop, building). In the case of equipping the premises with only an exhaust ventilation system, air is removed from the premises in an organized manner. The inflow is carried out unorganized or through leaks in building structures, or through holes specially provided for this purpose.

Exhaust ventilation (Fig. 2) consists of a cleaning device 1, a fan 2, a central 3 and suction ducts 4.

Unlike supply ventilation systems, in rooms with only exhaust systems, the pressure is set below atmospheric pressure or lower than in neighboring rooms.

If there is only an exhaust ventilation system in the room, as well as in the case of forced ventilation, air flows from the zone of high pressure to the zone of low pressure. Thus, the movement of air in the opposite direction is excluded or hindered. The most “dirty” rooms are equipped with exhaust ventilation systems when it is necessary to prevent or reduce the spread of air from them to neighboring rooms.

Rice. 2. Scheme of the exhaust ventilation system

Local exhaust ventilation

Local exhaust ventilation is used in a situation where the places of emission of harmful substances in the room are localized and it is possible to prevent their spread throughout the room. Local exhaust ventilation in industrial premises provides capture and removal harmful secretions: gases, smoke, dust, mists and partly heat released from the equipment. To remove hazards, local suctions are used (shelters in the form of cabinets, umbrellas, side suctions, shelters in the form of casings near machine tools, etc.).

The main requirements they must meet are:

the place of formation of harmful emissions, if possible, should be completely covered;

the design of the local suction must be such that the suction does not interfere with normal operation and does not reduce labor productivity;

harmful emissions must be removed from the place of their formation in the direction of their natural movement (hot gases and vapors must be removed upwards, cold heavy gases and dust - downwards).

The air removed from the room during local exhaust ventilation must be cleaned of dust before being released into the atmosphere. The most complex exhaust systems are those that provide for a very high degree of air purification from dust with the installation of two or even three dust collectors (filters) in series.

Local exhaust systems are usually very effective, as they allow you to remove harmful substances directly from the place of their formation or release, preventing them from spreading indoors. Due to the significant concentration of harmful substances (vapours, gases, dust), it is usually possible to achieve a good sanitary and hygienic effect with a small amount of air removed.

local ventilation- this is an air exchange system in a limited part of space, the microclimate of which differs from its general atmosphere. That is, in fact, this type of ventilation is intended for installation at a separately considered workplace.

If the ventilation tasks that the room and its purpose sets for the specialists of VeerVent LLC can be solved by the method of general and local ventilation, the latter option is always chosen, since it not only has high efficiency, but compared to the general exchange analogue, it is much more economical in terms of electricity consumption. But in terms of performance, a separate local ventilation system, without a general exchange supply and exhaust system, is not very effective. HVAC designers estimate such efficiency from 40% to 70%, from the required 95-100%, since the health of personnel depends on the local exhaust system.

In rooms with a local emission of harmful substances, the use of local ventilation can reduce the amount of supplied and exhausted air by several times!

Types of local ventilation

To create a ventilation system at the workplace, one of two types is formed - exhaust or supply local ventilation.

Exhaust local ventilation is used for localized foci of harmful substances, when it is possible to prevent their spread throughout the production area. It consists in capturing and removing harmful emissions emitted into the air of the room. With its help, the emission of dust, smoke, gases is organized.

Supply local ventilation is designed for intensive supply of fresh air directly to the workplace, its cooling if necessary, as well as blowing with cooled air flows if there is significant thermal radiation.

But you should not consider local ventilation a panacea for all types of buildings. When evaluating the premises, identifying the tasks that are set for ventilation, when implementing the project of industrial ventilation systems, our specialists are primarily guided by the expected efficiency, economy and expediency of using one or another method. So, local ventilation is not always able to properly remove from the premises and eliminate the emitted hazards; in this case the best option there will be a combination of elements of general and local ventilation.

Ways to create local ventilation

To remove harmful emissions from localized areas of the premises (exhaust local ventilation), shelter cabinets, curtains, side suctions, covers near machines, umbrellas, etc. are formed.

To create supply local ventilation, air oases are organized, air curtains. Air oases are mobile partitions having a sufficiently large height (up to 2.5 m), into which cooled air is injected. Air curtains are fan heaters installed near furnaces, work windows, gates, etc.

Application of local ventilation

Local ventilation is in many cases justified, and often simply objectively necessary. It is used in almost all industrial sectors, including in mines, chemical, metallurgical industries.

Depending on the type of source of harmfulness (machine, bath, etc.), various local suctions, exhaust hoods, exhaust panels, etc. are used. Onboard suctions, for example, are conveniently located around the perimeter of the baths.

Benefits of Local Ventilation

These include, first of all, the environmental need associated with the maximum effective protection worker health harmful production. With its help, they prevent the occurrence and development of pulmonary and cancerous diseases, allergies, irritation of the mucous membrane of the eyes, and headaches.

The second significant advantage is economic efficiency its application. It consists in saving energy costs (up to 60%), as well as in increasing the productivity of working personnel (according to statistics - up to 20%). In addition, local ventilation contributes to additional heating of the air in the production room, which creates another savings item.

We recommend that you solve problems with exhaust air emissions, starting with the design of ventilation systems. Systems with several local suctions and umbrellas require accurate calculation, which will allow the cost-effective implementation of the project, and starting from the project engineering systems there is a strategic opportunity to plan the construction or reconstruction of systems.

Ventilation is one of the main engineering systems of 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 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 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 of application natural ventilation- cheapness. 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.

With all the variety of ventilation systems, due to the different purpose of the premises, the different nature technological processes, types of harmful emissions and other factors, they can be classified according to the following criteria:

Depending on which method of creating pressure for ventilation processes is used. They can be natural or mechanical.
Depending on the purpose, the system can be supply, exhaust or supply and exhaust.
Depending on the zone served by the system - local and general exchange.
Depending on the design ventilation can be ducted or non-ducted.

Given these varieties, various combinations of ventilation systems are possible. For example, a general exchange duct system with supply and exhaust ventilation and mechanical stimulation (this is a standard ventilation used for large climate systems) or a ductless local exhaust ventilation system with natural stimulation (this is air exhaust without using a fan, operating naturally air convection).

natural ventilation

This type of ventilation works thanks to:

temperature difference between atmospheric air and indoor air (aeration);
air column pressure difference between the served room and the exhaust device;
the effect of wind pressure.

Aeration finds application in workshops with high heat releases when not exceeding allowable concentration harmful gases and dust in the supply air in the working area.

Aeration is not applied if, according to the conditions of the workshop technology, it is necessary to pre-treat the supply air or if, due to the inflow atmospheric air condensation or mist will form.

In ventilation systems in which air moves due to the pressure difference of the air column, the height difference (minimum) between the level of intake of internal air and its outlet through the exhaust device must be at least 3 m.

The recommended horizontal length of the air duct sections should not exceed 3 m, and the air velocity in the air duct should not exceed 1 m/s. If these requirements are not met, ventilation will simply work inefficiently.

The effect of wind pressure is expressed in the fact that on the windward sides of the building (facing the wind) high blood pressure and, conversely, on the leeward sides - reduced (air rarefaction).

If there are openings in the fences of the building, then outside air enters the room from the windward side, and leaves it from the windward side, while the speed of its movement in the openings depends on the speed of the wind blowing the building and, accordingly, on the difference in pressures that arise.

The natural ventilation system is simple, does not require electricity and expensive equipment. But since the efficiency of the use of this system depends on external variables (temperature of atmospheric air, wind direction and speed), more complex functions in the field of ventilation cannot be solved with their help.

mechanical ventilation

These ventilation systems use equipment and devices (electric motors, dust collectors, air heaters, automation, etc.) that allow you to move air masses over long distances.

Expenses electrical energy for the operation of this equipment are usually quite high.

Thanks to mechanical ventilation, air can be supplied and taken into the right amount from local areas of the room, regardless of changing atmospheric conditions outside the building. If necessary, the air can be exposed different ways processing (cleaning, moisturizing, heating, and others), which is impossible in a system with natural motivation.

It should be noted that very often in practice the so-called combined ventilation is provided - this is the simultaneous use of natural and mechanical systems. This can significantly improve ventilation efficiency and reduce resource costs.

Forced ventilation

Supply ventilation serves exclusively to supply air masses to a ventilated room. In necessary cases, the air is subjected to special treatment before it is supplied to the room - humidification, purification, heating, cooling, etc. Its removal occurs due to the occurrence overpressure in which excess air is forced out and replaced with fresh air. Air leaves the room through opening doors and leaks in the building envelope.

Exhaust ventilation

The task of exhaust systems is to remove contaminated or heated treated air from a room (production, workshop, building) to create a vacuum in it. Due to rarefaction, outside air enters through the doors and leaks in the fences.

Supply and exhaust ventilation

Depending on the desired effect, only the supply system or only the exhaust system can be used. But in most cases, both systems are provided at once in the premises.

With the help of supply and exhaust equipment, ventilation of premises has the following advantages:

there is no residual pressure in the ventilated room;
also there are no drafts.

On the one hand, this type of ventilation is quite powerful and is able to provide the necessary air exchange. On the other hand, air handling units are not very expensive in terms of electrical energy consumption and operating costs.

General and local ventilation

Purpose of general ventilation- ensuring air exchange throughout the room. With such a system, all the necessary parameters of air masses are maintained throughout the entire volume of the room. In addition, its tasks include the removal of pollutants, excess heat and humidity that have not been eliminated by local ventilation to the permitted level.

The local ventilation system is as follows: fresh air is supplied to specific places (this is supply ventilation), and polluted is removed only from places where unacceptable harmful emissions are formed (this is exhaust ventilation). Such a system can approach a large room with a small number of people in it, in which case air exchange is carried out only in the places where working people are located.

Ducted and non-ducted ventilation systems

Ventilation systems can have a large network of channels (air ducts) that are designed to move air. Such a system is called a channel system. Also, these channels may be absent, then the ventilation is called channelless.

Installation of a system with a channel network is used mainly in rooms that are large in volume. As for channelless, it is used when installing small-sized systems, for example, a home fan.

The choice of the ventilation system should be carried out at the design stage of the building (structure). And this, of course, should be done by professionals.

Introduction

Ventilation is the main element in creating a favorable climate, designed to supply fresh air from the street and remove polluted air from the premises.

Indoor air is an important factor affecting the health and, as a result, the ability to work of people in these rooms.

Ventilation is one of critical systems ensuring normal conditions of human life. If it works in conjunction with other climate systems, then a comfortable microclimate is maintained in the premises. Ventilation is a set of measures and devices used in the organization of air exchange to ensure a given state of the air in the room and at workplaces in accordance with building codes. It's about about the fresh air that must enter the room. It is for this purpose that ventilation systems are installed in the premises.

All buildings are provided with central ventilation risers, a branch on each floor through which natural exhausts from the kitchen and bathrooms are organized, and due to which the simplest natural air exchange in the room is organized: air leaves through the ventilation grilles, and from the street gradually enters through windows, doors, various leaky joints, etc.

To solve the problems of ventilation of premises for various purposes from apartments to industrial premises, there is a large number of ventilation systems, where the required volume of air circulation is provided by fans of various capacities, in addition, such systems usually have additional air processing sections: heating, filtration, humidification, cooling, etc. can be added. of necessity.

Ventilation is characterized by the volume and frequency of air exchange. The volume of ventilation is the amount of air that enters the room during the hour.

Classification of ventilation systems

The four main ways in which ventilation systems are classified are:

By the method of creating pressure to move air:

o with natural

o with artificial drive

By appointment:

o supply

o exhaust

By service area:

o local

o general exchange

By design:

o channel

o channelless

Types of ventilation

Natural ventilation

Mechanical ventilation

· Forced ventilation

· Exhaust ventilation

· Supply and exhaust ventilation

General and local ventilation

natural ventilation

Natural ventilation is created, as you might guess in a natural way, without the use of ventilation equipment, but only due to natural air exchange, the difference in temperature between indoors and outdoors and wind flows. Due to changes in atmospheric pressure depending on the floor on which the room is located. Natural ventilation systems are easy to install and relatively inexpensive. But such ventilation systems are closely dependent on climatic conditions, as a result of which they are not able to solve the entire volume assigned to the ventilation of the room.

Figure 1. Scheme of natural ventilation of a dwelling.

mechanical ventilation

Forced replacement of exhaust air in a room with fresh air is called mechanical ventilation. In this case, special equipment is used that allows air to be supplied and removed from the premises in the required amount, regardless of changing ambient air conditions.

If necessary, ventilation systems, the air is subjected to various types of treatment (heating, purification, dehumidification, cooling, humidification, etc.), which is practically impossible to implement in systems with natural ventilation.

In practice, so-called mixed ventilation is often provided, which combines both natural and mechanical ventilation. Each specific project determines which type of ventilation is the best in sanitary and hygienic terms, as well as economically and technically more rational. Mechanical ventilation can be arranged both at the local workplace (local) and for the entire room as a whole (general exchange).

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

Forced ventilation

The supply ventilation system is used to supply clean air to ventilated premises in exchange for remote polluted air. The supply air, if necessary, is subjected to special treatment (cleaning, heating, humidification, etc.).

Exhaust ventilation

Exhaust ventilation removes polluted air from the room.

In the general case, both supply and exhaust systems are provided in the room. Their performance must be balanced with regard to the possibility of air entering adjacent rooms or from adjacent rooms. In the premises, only an exhaust or only a supply system can also be provided. In this case, the air enters the room from the outside or from adjacent rooms through special openings, or is removed from the room to the outside, or flows into adjacent rooms.

local ventilation

Local supply ventilation

Local supply ventilation includes air showers (concentrated air flow at an increased speed). Their task is to supply clean air to permanent workplaces, reduce the ambient air temperature in their area and blow on workers exposed to intense thermal radiation.

local supply ventilation They are also used in the form of air curtains (at gates, stoves, etc.), which create, as it were, air partitions or change the direction of air flows. Local ventilation is less expensive than general ventilation. In industrial premises, when hazards (gases, moisture, heat, etc.) are released, a mixed ventilation 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

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

Figure 2.

Local exhaust ventilation is used when hazardous smoke, gases, dust, and partially heat are localized, for example, from a machine in production or from a stove in the kitchen. Such ventilation captures and removes harmful substances, preventing their spread throughout the room; local exhaust ventilation includes local exhausts - shelters in the form of cabinets or casings near machines, exhaust hoods, side exhausts, etc. Local ventilation also includes air curtains - air shields that do not allow air to penetrate from one room to another, or from the street to the room.

The main requirements that local exhaust ventilation must meet:

The place of formation of harmful emissions should, if possible, be completely covered.

The design of the local suction must be such that the suction does not interfere with normal operation and does not reduce labor productivity.

Harmful emissions must be removed from the place of their formation in the direction of their natural movement (hot gases and vapors must be removed upwards, cold heavy gases and dust - downwards).

The designs of local suctions are conditionally divided into three groups:

half open blowjobs ( fume hoods, umbrellas). Air volumes are determined by calculation.

Open type (onboard suction). Removal of harmful emissions is achieved only with large volumes of sucked air.

BENEFITS: Local exhaust systems are generally very efficient as they allow the removal of harmful substances directly from the place of their formation or excretion, preventing them from spreading indoors. Due to the significant concentration of harmful substances (vapours, gases, dust), it is usually possible to achieve a good sanitary and hygienic effect with a small amount of air removed.

LIMITATIONS: local systems ventilation cannot solve all the problems facing ventilation. Not all harmful secretions can be localized by these systems. For example, when harmful emissions are dispersed over a large area or volume; air supply to separate zones premises cannot provide the necessary conditions air environment. The same thing happens if the work is done on the entire area of the premises or its nature is associated with movement, etc.

General ventilation

General exchange ventilation systems - both supply and exhaust, are designed for ventilation in the room as a whole or in a significant part of it.

General exchange exhaust systems relatively evenly remove air from the entire serviced premises, and general exchange supply systems supply air and distribute it throughout the volume of the ventilated premises.

General supply ventilation

General exchange supply ventilation is arranged to assimilate excess heat and moisture, dilute harmful concentrations of vapors and gases that are not removed by local and general exchange exhaust ventilation, as well as to ensure the calculated sanitary and hygienic standards and free breathing of a person in the working area.

With negative thermal balance, i.e. with a lack of heat, general exchange supply ventilation is arranged with mechanical stimulation and with heating of the entire volume of supply air. As a rule, before supplying the air is cleaned of dust.

When harmful emissions enter the air of the workshop, the amount of supply air must fully compensate for general and local exhaust ventilation.

General exhaust ventilation

The simplest type of general exhaust ventilation is a separate fan (usually of an axial type) with an electric motor on one axis, located in a window or wall opening. Such an installation removes air from the room zone closest to the fan, performing only general air exchange.

AT industrial buildings where there are heterogeneous harmful emissions (heat, moisture, gases, vapors, dust, etc.) and their entry into the room occurs in various conditions(concentrated, dispersed, on various levels etc.), it is often impossible to get by with any one system, for example, local or general exchange.

In such rooms, to remove harmful emissions that cannot be localized and enter the air of the room, general exchange exhaust systems are used.

In certain cases, in industrial premises, along with mechanical ventilation systems, systems with natural motivation are used, for example, aeration systems.

The need for good ventilation in the room.

Clean air is one of essential conditions the existence of life itself. However, the air always contains impurities, the amount of which depends on many reasons. Various measures are taken to reduce outdoor air pollution.

At the same time, very little is being done to improve indoor air quality. And this despite the fact that in all parts of the world people spend most of their time indoors. For example, residents Northern Europe spend up to 90% of the time indoors.

Indoor air is initially polluted with impurities contained in outdoor air. Therefore, the gas we inhale is a mixture of outside air and impurities emitted building materials, machines, people, animals and other sources of pollution in the room. modern houses are usually densely insulated, so pollutants quickly accumulate inside buildings unless special systems are used to remove them.

Wherever people are - at work, at school or at home, when inhaling purified air, their well-being and performance improve. Research shows that as office ventilation improves, sickness (and therefore sick leave) among staff decreases. This highlights the need to improve air quality.

The quality of the air environment is inextricably linked with ventilation. A decrease in the amount of oxygen and an increase in the amount of carbon dioxide cause a state of closeness in the premises. An increased concentration of carbon dioxide leads to oxygen starvation of the brain, heart failure, and suffocation. Increased concentration of dust in the air tobacco smoke and other pollutants poison the human body. Unpleasant odors create discomfort or annoy our nervous system, reduce the ability to work. High air speed causes a feeling of draft, and low air speed leads to stagnation of air in various parts rooms, which causes accelerated reproduction of bacteria and mold. When we are indoors, we feel the impact of any of these factors. It is as a result of the lack of air circulation, poor ventilation and insufficient fresh air in the house that conditions are created under which harmful substances can act on a person, posing a direct threat to his health.

The number of people suffering from various types allergies. Even science is not able to explain the reason for such widespread this disease. Highly an important factor is the internal environment of the room - it is recognized by all. Thus, a decrease in the incidence of allergies is directly related to an improvement in the quality of the ventilation system.

Today, there are virtually no barriers to improving indoor air quality. In this area, modern requirements have been developed, which must be strictly observed. There is hardly a person who would deny the importance of research on the impact of air quality on our health and well-being. In a government health report and environment(No. SOU 1996: 124) formulated the main task of the state commission for the study of this issue: "The possibility of illness or deterioration of health due to the poor quality of the internal environment of the room must be excluded."