Recuperation ventilation system. Air handling units with heat recovery. Types of recuperative units

Air recirculation in ventilation systems is the mixing of a certain amount of exhaust (exhaust) air into the supply air flow. Thanks to this, a reduction in energy costs for heating fresh air is achieved. winter period of the year.

Scheme of supply and exhaust ventilation with recovery and recirculation,
where L is air flow, T is temperature.

Heat recovery in ventilation- this is a method of transferring thermal energy from the exhaust air flow to the supply air flow. Recuperation is used when there is a temperature difference between the exhaust and supply air to increase the temperature of the fresh air. This process does not imply mixing of air flows; the process of heat transfer occurs through any material.

Temperature and air movement in the recuperator

Devices that perform heat recovery are called heat recuperators. They come in two types:

Heat exchangers-recuperators- they transmit heat flow through the wall. They are most often found in installations of supply and exhaust ventilation systems.

In the first cycle, which are heated by the exhaust air, in the second they are cooled, giving off heat to the supply air.

A supply and exhaust ventilation system with recovery is the most common way to use heat recovery. The main element of this system is the supply and exhaust unit, which includes a recuperator. The device of the air supply unit with a recuperator allows up to 80-90% of the heat to be transferred to the heated air, which significantly reduces the power of the heater in which the supply air is heated in case of shortage heat flow from the recuperator.

Features of the use of recirculation and recovery

The main difference between recovery and recirculation is the absence of mixing air from indoors to outdoors. Heat recovery is applicable in most cases, while recirculation has a number of limitations that are specified in regulatory documents.

SNiP 41-01-2003 does not allow re-supply of air (recirculation) in the following situations:

• In rooms where the air flow is determined based on the emitted harmful substances;
• In rooms where there are pathogenic bacteria and fungi in high concentrations;
• In rooms with the presence of harmful substances that sublimate upon contact with heated surfaces;
• In premises of categories B and A;
• In premises where work is carried out with harmful or flammable gases and vapors;
• In premises of category B1-B2, in which flammable dust and aerosols may be released;
• From systems with local suction of harmful substances and explosive mixtures with air;
• From airlock vestibules.

Recirculation:
Recirculation in air handling units is actively used more often when great productivity systems when air exchange can be from 1000-1500 m 3 / h to 10000-15000 m 3 / h. The removed air carries large stock thermal energy, mixing it into the external flow, allows you to increase the temperature of the supply air, thereby reducing the required power of the heating element. But in such cases, before being re-entered into the room, the air must pass through a filtration system.

Ventilation with recirculation allows you to increase energy efficiency and solve the problem of energy saving in the case when 70-80% of the removed air is re-entered into the ventilation system.

Recovery:
Air handling units with recovery it is possible to install at almost any air flow rate (from 200 m 3 / h to several thousand m 3 / h), both small and large. Recuperation also allows heat to be transferred from the exhaust air to the supply air, thereby reducing the energy demand on the heating element.

Relatively small installations used in ventilation systems of apartments and cottages. In practice, air handling units are mounted under the ceiling (for example, between the ceiling and suspended ceiling). This decision requires some specific installation requirements, namely: small overall dimensions, low noise level, simple maintenance.

A supply and exhaust unit with recovery requires maintenance, which requires making a hatch in the ceiling for servicing the recuperator, filters, and blowers (fans).

Main elements of air handling units

A supply and exhaust unit with recovery or recirculation, which has both the first and second processes in its arsenal, is always a complex organism that requires highly organized management. The air handling unit hides behind its protective box such main components as:

• Two fans various types, which determine the productivity of the installation in terms of flow rate.
• Heat exchanger recuperator- heats supply air by transferring heat from the exhaust air.
• Electric heater- heats the supply air to the required parameters in case of insufficient heat flow from the exhaust air.
• Air filter- thanks to it, the outside air is monitored and cleaned, as well as the exhaust air processed in front of the recuperator to protect the heat exchanger.
• Air valves with electric drives - can be installed in front of the outlet air ducts for additional regulation of the air flow and blocking the channel when the equipment is turned off.
• Bypass- thanks to which the air flow can be directed past the recuperator in the warm season, thereby not heating the supply air, but supplying it directly to the room.
• Recirculation chamber- ensuring the admixture of exhaust air into the supply air, thereby ensuring recirculation of the air flow.
  
  

In addition to the main components of the air handling unit, it also includes a large number of small components such as sensors, automation systems for control and protection, etc.

Control circuit

All components of the air handling unit must be correctly integrated into the system of operation of the unit and perform their functions to the proper extent. The task of controlling the operation of all components is solved by automated system process control. The installation kit includes sensors, analyzing their data, the control system corrects the operation necessary elements. The control system allows you to smoothly and competently fulfill the goals and objectives of the air handling unit, solving complex problems interaction of all installation elements with each other.

Ventilation control panel

Despite the complexity of the process control system, technological developments make it possible to provide to an ordinary person control panel for the installation in such a way that from the first touch it is clear and pleasant to use the installation throughout its service life.

Example. Heat recovery efficiency calculation:
Calculation of the efficiency of using a recuperative heat exchanger in comparison with using only an electric or only a water heater.

Let's consider a ventilation system with a flow rate of 500 m 3 /h. Calculations will be carried out for the heating season in Moscow. From SNiP 23-01-99 “Construction climatology and geophysics” it is known that the duration of the period with an average daily air temperature below +8°C is 214 days, average temperature period from average daily temperature below +8°C is -3.1°C.

Let's calculate the required average thermal power:
In order to heat the air from the street to a comfortable temperature of 20°C, you will need:

N = G * C p * ρ ( in-ha) * (t in -t av) = 500/3600 * 1.005 * 1.247 * = 4.021 kW

This amount of heat per unit time can be transferred to the supply air in several ways:

1. Heating of supply air with an electric heater;
2. Heating of the supply coolant removed through the recuperator, with additional heating by an electric heater;
3. Heating of outdoor air in a water heat exchanger, etc.

Calculation 1: We transfer heat to the supply air using an electric heater. The cost of electricity in Moscow is S=5.2 rubles/(kWh). Ventilation operates around the clock, during 214 days of the heating period, the amount of funds in this case will be equal to:
C 1 =S * 24 * N * n = 5.2 * 24 * 4.021 * 214 =107,389.6 rub/(heating period)

Calculation 2: Modern recuperators transfer heat with high efficiency. Let the recuperator heat the air by 60% of the required heat per unit time. Then electric heater The following amount of power must be expended:
N (electric load) = Q - Q rec = 4.021 - 0.6 * 4.021 = 1.61 kW

Provided that the ventilation will work throughout the entire heating period, we get the amount for electricity:
C 2 = S * 24 * N (electric heat) * n = 5.2 * 24 * 1.61 * 214 = 42,998.6 rub/(heating period)

Calculation 3: A water heater is used to heat the outdoor air. Estimated cost heat from industrial hot water per 1 Gcal in Moscow:
S g.v. = 1500 rub./gcal. Kcal=4.184 kJ

To heat up we need the following amount of heat:
Q (g.v.) = N * 214 * 24 * 3600 / (4.184 * 106) = 4.021 * 214 * 24 * 3600 / (4.184 * 106) = 17.75 Gcal

During the operation of ventilation and heat exchange apparatus throughout the cold period of the year, the amount of money for the heat of process water is:
C 3 = S (g.w.) * Q (g.w.) = 1500 * 17.75 = 26,625 rubles/(heating period)

The results of calculating the costs of heating the supply air during the heating period
period of year:

From the above calculations it is clear that the most economical option This is the use of a hot service water circuit. In addition, the amount of money required to heat the supply air is significantly reduced when using a recuperative heat exchanger in the supply and exhaust ventilation system compared to using an electric heater.

In conclusion, I would like to note that the use of recovery or recirculation units in ventilation systems makes it possible to use the energy of the exhaust air, which reduces energy costs for heating the supply air, therefore reducing the cash costs of operating the ventilation system. The use of heat from exhaust air is modern energy saving technology and allows you to get closer to the model " smart home", in which any available type of energy is used as fully and usefully as possible.

Creating a comfortable microclimate in the premises of the house is possible only with appropriate ventilation. Stagnant air can cause mold to appear on the walls, as well as physical illness. An open vent or window cannot always qualitatively renew the air in the premises of a private home. To do this effectively, you need to install a supply and exhaust ventilation system.

The principle of operation and the need for supply and exhaust ventilation in a private house

This type of ventilation is also called “forced”. Unlike the option with natural circulation, it is equipped with electrical devices that pump and promote air flows.

Designs with a forced air exchange system are equipped with fans of various powers, electronics, noise suppressors and heating elements. All these devices are designed to supply housing with environmentally friendly oxygen, creating internal comfort and a feeling of freshness.

The presence of the specified elements will create effective ventilation in the house

Unlike natural ventilation, the supply and exhaust type of air exchange is effective under the following conditions:

1. The minimum temperature difference between indoors and outdoors, when warm air rises, cannot create draft.
2. When there is a difference in air pressure between the upper and lower levels of the building.

This type of ventilation should be used for residential premises or buildings with several rooms located at different levels, as well as in areas with a polluted atmosphere. The supply and exhaust ventilation method will not only change the air in the room, but also make it clean, thanks to the special filters provided in the system.

The design can carry out not only conventional filtration through a foam layer, but also carry out this process using a lamp with ultraviolet light.

Efficient forced ventilation system

An important role in the supply and exhaust system is played by:

• engine and fan power;
• filter material class;
• heating element size;
• quality of material and type of air ducts.

Fans

Forced movement of air masses is provided by fans. Simple models are equipped with three levels of blade speed:

• normal;
• low (used for “quiet” operation at night or during the absence of owners);
• high (used to create powerful air currents).

Modern fan models are made with big amount speeds that satisfy the needs of any owner. Fans are upgraded with automatic and electronic controllers. This makes it possible to program the device by setting blade rotation speed modes. Electrical equipment allows you to synchronize ventilation with the smart home system.

When choosing, preference should be given to trusted manufacturers

Since the operation of the ventilation system is designed for continuous long term, the quality of the fans must be at the highest level.

Filters

Supply air masses must be cleaned using filters. Recuperators are equipped with filter layers that are capable of trapping particles less than 0.5 microns. This parameter corresponds to the European standard. A filter with this throughput does not allow fungal spores, plant pollen, dry soot and dust to enter the room.

The presence of this device is especially important for owners suffering from allergic diseases.

The design of ventilation ducts can be equipped with several filter barriers, installing them in front of heat exchange devices. However, such filters are designed to protect them from carrier dirt from exhaust flows.

Manufactured with multiple layers

Recuperation systems are equipped with electronic sensors, which, having detected the maximum degree of filter contamination, are signaled by a sound or light indicator.

Heating elements

A supply and exhaust ventilation system requires the installation of heating elements, since heat exchangers lose their efficiency if the external air temperature is below -10°C. To do this, it is mounted on the supply channel electrical system heating the incoming air.

Modern heating elements are programmed for a specific operating mode. This makes it possible to control the temperature without outside intervention. Typically, computerized heating elements are installed and synchronized with the smart home system.

The size, power, shape and design of the heating elements are selected in compliance with the parameters of the entire ventilation system and the desire of the owner.

Makes the temperature comfortable

When choosing the power of the heater, you should take into account its operation at low external temperatures and high humidity. Such conditions will contribute to the fact that condensation may appear on the heat exchanger parts, which subsequently turns into ice.

1. This problem can be solved in two ways:
2. Change the operation order of the supply fan. It must be turned on every 20–30 minutes for 5–10 minutes. The heated air flow passing through the heat exchanger eliminates icing.

Change the direction of cold air flow. To do this, the supply air masses are separated, directing their flows past the heat exchanger.

Air ducts

It is most convenient to install ventilation in a building under construction - in basements, attics or behind suspended panels. It should be noted that the installation of this system must be carried out in a dry and insulated room with a positive temperature. The most convenient and popular air ducts are flexible options made of aluminum or plastic. Pipes are made with round, square or rectangular cross-section

. This material has a reinforcing frame made of steel wire, and can also be covered with a thermal insulation layer based on mineral fibers, for example, mineral wool.

Supply and exhaust ventilation with heat recovery

Humid air concentrated in the kitchen, bathroom or utility room is directed outside using air intakes. Before leaving the air duct channels, it is retained in the heat exchanger, which takes away part of the heat, giving it to the opposite (supply movement of air masses).

A good recovery option with partial moisture return is implemented in Naveka units, Node5 series: https://progress-nw.ru/shop?part=UstanovkiventilyatsionnyieNode5.

Operating principle of the device

Systems equipped with recuperators have gained great popularity in Western European countries. Thanks to this equipment, buildings built in these regions lose 5–10 times less heat than those built without these systems. Recycling heated exhaust streams reduced heat generation costs by 65–68%. This made it possible to pay for such a system over a period of 4–5 years. The energy efficiency of houses equipped with this system has made it possible to reduce the heating period.

The dimensions and power of supply and exhaust systems equipped with a recuperator depend on the area and location of the ventilated premises.

Enterprising homeowners install natural and forced (with heat recovery) in their homes. This is necessary in case of malfunction or repair of mechanical air exchange. Natural ventilation is convenient to use during unheated periods.

When using two ventilation systems in your home, you should adhere to the rule - the natural ventilation ducts must be tightly closed during forced air exchange.

If this is neglected, then the quality of air renewal with the help supply and exhaust system, will decrease significantly.

Most often used in ventilation systems the following types recuperators:

• lamellar;
• rotary;
• with intermediate coolant;
• chamber;
• in the form of heat pipes.

Plate recuperators

In this device, warm and cold air flows pass from both sides of the plates. This promotes the formation of condensation on them. In this regard, special outlets for accumulated water are installed on such structures. Chambers for collecting moisture must be equipped with valves that prevent liquid from entering the channel. If water drops enter the system, ice may form. Therefore for normal operation device, a defrosting system is required.

The appearance of ice can be avoided by controlling the operation of the bypass valve, which regulates the amount of air flow passing through the device.

The design feature increases its efficiency

Rotary

Heat exchange in this device occurs through the removed and supply channels as a result of the rotation of the rotor disks. The elements of this system are not protected from dirt and odors, so their particles can move from one air stream to another.

The recovery of warm air flows can be controlled by changing the rotation speed of the rotor disks.

This device, unlike the previous one, is less susceptible to freezing, since the working elements are dynamically movable. Coefficient useful action of these devices reaches 75–85%.

Equipped with movable elements

Recuperators with intermediate coolant

The coolant in this recuperator design is water or a water-glycol solution. The peculiarity of this type is that the heat exchangers are in different channels - one in the exhaust channel, the other in the supply channel. The water moves through the tubes between two heat exchangers. The design has a closed system. This prevents contaminants from the exhaust air from entering the supply air.

Heat exchange is regulated by changing the speed of movement of coolant moisture.

Such devices do not have moving elements, so their efficiency is lower, amounting to 45–60%.

Has no moving elements

Chamber

Heat exchange in such a design occurs as a result of changing the direction of air flow. Chamber recuperators are devices, usually in the form rectangular parallelepiped, with a camera that is divided into two parts by a shutter. During operation, it changes the direction of the air masses so that the temperature of the supply flow increases from the heated chamber body. The disadvantage of this recuperator is that dirty particles and odors can mix with the exhaust and supply air.

Flows inside the chamber can mix

Heat pipes

Recuperators of this type have a sealed housing, inside of which there is a system of tubes filled with freon. Under the influence of high temperature (during the removal of air), the substance turns into steam. As the influent masses pass along the tubes, the steam collects in drops, forming a liquid. The design of such recuperators eliminates the transfer of odors and dirt. Since the body of this device does not have moving elements, it has low efficiency (45–65%).

The work is based on temperature changes in freon

Due to their high efficiency, rotor and plate types have become most popular. Recuperator designs can be modernized, for example, by installing two plate-type heat exchangers in series. The efficiency of such ventilation increases.

PES design

When designing a ventilation system, it is necessary to determine the type of this device, since its power and the amount of electricity consumed may not be suitable for every owner. In this regard, if there is no need for forced ventilation, then it is better to install natural ventilation.

Each ventilation system has its own standard parameters for the volume of air passed in 1 hour:

• For natural option this norm is 1m³/h;
• for forced - in the range from 3 to 5 m³/h.

When designing a ventilation system for large rooms, it is advisable to install forced ventilation.

Design and installation of ventilation systems is a technically complex process that includes several stages:

1. The first stage consists of drawing up drawings and collecting data on the layout of the premises. Based on the established information, the type of ventilation system is selected and the power of the equipment is determined.
2. At the second stage, necessary calculations in terms of air exchange volumes for each room in the house. This is a crucial design moment, since incorrect calculations will subsequently cause stagnant air, the appearance of mold and mildew, and a feeling of stuffiness.
3. The third stage consists of calculating sections for air ducts. This is also an important point, since incorrect calculations will cause low efficiency of the entire system, despite expensive equipment.

• Therefore, it is better to entrust the calculations to specialists than to do it yourself. To correctly calculate the size of air ducts, follow the basic rules:
• in natural exhaust air flow speed should correspond to 1 m/s; V air channels
• equipped with fans, this parameter is 5 m/s;

1. in air duct branches the speed of air masses is 3 m/s.
2. At the fourth stage, a diagram of the ventilation system is drawn up indicating the separation valves. The purpose of this stage is to correctly distribute barriers to prevent the spread of smoke and fire during a fire. The fifth stage is to coordinate the selected system with the existing ones regulatory documents and installation and placement rules. ventilation system must be approved by fire, sanitary and hygienic and architectural organization. Obtaining permissions from all these services and government agencies gives the right to installation.

Pay attention to the material on the design and installation of ventilation in the cellar of a private house:.

Calculations

When carrying out calculations of supply and exhaust ventilation systems, it is necessary to take into account the amount of replaced air in the room per certain time. The unit of measurement is cubic meter per hour (m³/h).

To apply this indicator to calculations, you need to calculate the passage of air flows and add 20% (resistance of filter layers and grids).

Air volume calculation

As an example, the air volume was calculated for a private house with a ceiling height of 2.5 m. The system will also serve 3 bedrooms (11 m² each), a hallway (15 m²), a toilet (7 m²) and a kitchen (9 m²). Let's substitute the values ​​(3∙11+15+7+9) ∙2.5=160 m³.

When making calculations, it is necessary to round the obtained data upward.

The installed heat exchanger must match the power of all fans in the supply and exhaust system. To do this, it is necessary to subtract 25% from the sum of the fan performance (resistance to air flow in the system). The inlet and outlet of the recuperator must be equipped with fans.

It should be noted that in each room of the house where the system is located, 1 supply air supply and 1 exhaust fan. The required performance of each of them is calculated as follows:

1. Bedroom: 11∙2.5=27.5+20%=33 m³/h. Since the house has three bedrooms with the same area, it is necessary to multiply this value by three: 33∙3=99 m³/h.
2. Hallway: 15∙2.5=37.5+20%=45 m³/h.
3. Toilet: 7∙2.5=17.5+20%=21 m³/h.
4. Kitchen: 9∙2.5=22.5+20%=27 m³/h.

Now you need to add these values ​​to get the total fan performance: 99+45+21+27=192 m³/h.

The load on the recuperator will be: 192–25%=144 m³/h.

Calculation of the diameter of the ventilation duct

To calculate the diameter of the ventilation duct, it is necessary to use the formula for calculating the cross-sectional area, which is as follows: F=L/(S∙3600), where L is the total number of air masses passing in one hour, S is the average air speed equal to 1 m/s. Let's substitute the values: 192/(1 m/s∙3600)=0.0533 m².

To calculate the pipe radius with round you need to use the following formula: R=√(F:π), where R is the radius round pipe; F - air duct section; π – mathematical quantity, equal to 3.14. In an example, it looks like this: √(0.0533∙3.14)=0.167 m².

Electricity calculation

Correctly calculated energy consumption will allow rational use of the ventilation system. This is especially important if the duct structure is equipped with heating elements.

To calculate the amount of energy consumed, you should use the formula: M=(T1∙L∙C∙D∙16+T2∙L∙C∙N∙8)∙AD:1000, where M is the total price for the electricity used; T1 and T2 - temperature difference between day and night (the values ​​differ depending on the month of the year); D, N - the cost of electricity in accordance with the time of day; A, D- total number calendar days in a month.

Air temperature readings are easy to find out from local weather forecasts, so there is no need to purchase any reference books. Tariff sizes are determined according to the region of residence. Using these sources, you can obtain accurate readings on energy consumption when the ventilation system is operating.

Equipment installation procedure

Installation of equipment elements for the supply and exhaust ventilation system is carried out after finishing the walls, before installation hanging panels ceiling. The ventilation system equipment is installed in a certain order:

1. The intake valve is installed first.
2. After it there is a filter for cleaning the incoming air.
3. Then an electric heater.
4. The heat exchange device is a recuperator.
5. Air duct cooling system.
6. If necessary, the system is equipped with a humidifier and a fan in the supply duct.
7. If the power is high, then a noise isolating device is installed.

Do-it-yourself supply and exhaust ventilation system installation

Installation of a ventilation system consists of several construction stages:

1. Using the previously obtained values, make a calculation optimal parameters for holes in the wall.
2. Make markings to place the supply channel. To drill a hole in a concrete wall, you must use a rig with a construction drill bit to concrete surfaces. This device is fixed to the wall, thanks to which the hole is smooth, in a precisely marked place. The contact point between the core drill and concrete wall it is insulated with a special cap, to which tubes are connected to supply a stream of water and a powerful vacuum cleaner.

   

   Provides forced movement of air masses

Air duct installation

Installation of air ducts should be preceded by drawing up diagrams and drawings. You should also make sure that you have additional fasteners and clamps. Installation of air ducts is carried out in the following order:

How to operate and maintain the PES

The high-quality operation of the supply and exhaust ventilation system depends not only on professional installation, but also on competent maintenance. Elements of the supply and exhaust device require:

• periodic cleaning of filters;
• their renewal in case of contamination or expiration of service life;
• replacing the lubricant of moving parts and fan parts;
• If the system is equipped with heating elements, ionizers and noise insulators, regular checks of their serviceability are necessary.

Typically, all necessary actions for caring for this system are described in the operating rules and instructions.

Video: apartment ventilation on 2 levels with heat recovery

Having familiarized yourself with all the nuances of installing and equipping a ventilation system, you can create a healthy and comfortable atmosphere in your home, providing yourself and your loved ones with fresh air.

Ventilation with recovery is equipment designed to process air to such parameters that a person could feel comfortable and safe. Such parameters are regulated by standards and lie within the following limits: temperature 23÷26 C, humidity 30÷60%, air speed 0.1÷0.15 m/s.

There is another indicator that is directly related to the safety of a person in enclosed spaces - the presence of oxygen, or more precisely, the percentage of carbon dioxide in the air. Carbon dioxide displaces oxygen and, at levels of 2 to 3% carbon dioxide in the air, can cause loss of consciousness or death.

It is to maintain these four parameters that ventilation units with recovery are used. This is especially true for modern business centers where there is no natural flow of fresh air. Industrial, administrative, commercial, residential, and other premises cannot do without modern ventilation equipment. With today's air pollution, the issue of installing ventilation units with recovery is most relevant.

It is possible to install additional filters and other devices in ventilation with recovery that allow you to even better clean and process the air to the specified parameters.

All this can be done using Dantex ventilation units.

Operating principle of a supply and exhaust ventilation system with heat recovery

Thanks to the supply and exhaust ventilation system, the room is pumped fresh air, and the heated exhaust air is discharged outside. Passing through the heat exchanger, the heated air leaves part of the heat to the walls of the structure, as a result of which the cold air coming from the street is warmed up by the heat exchanger without spending additional energy on heating. This system is more efficient and less energy-consuming than a ventilation system without heat recovery.

The efficiency of the recuperator varies depending on the outside air temperature; it can be calculated using the general formula:

S = (T1 – T2) : (T3 – T2)
Where:

S– recovery efficiency;
T1– temperature of the air entering the room;
T2– air temperature outside;
T3– room air temperature.

Types of recuperators

Plate recuperators

This type of heat exchanger consists of a set of thin plates made of aluminum or any other material, preferably with good heat transfer characteristics). This is the cheapest and most popular type of device (recuperator). The efficiency of a plate recuperator can range from 50% to 90%, and the service life, due to the absence of moving parts, is very long.

The main disadvantage of such recuperators is the formation of ice due to temperature differences. There are three options for solving this problem:

• Do not use recovery at extremely low temperatures
• Use models with an automated recovery process. IN in this case cold air bypasses the plates, and warm air warms the ice. But it is worth considering that the efficiency of such models in cold weather will decrease by 20%.

Rotary recuperators

The heat exchanger has a moving part - a cylindrical rotor (recuperator), which consists of profiled plates. Heat transfer occurs when the rotor rotates. Efficiency ranges from 75 to 90%. In this case, the rotation speed affects the level of recuperation. The speed can be adjusted independently.

Ice does not form on rotary heat exchangers, but they are more difficult to maintain, unlike plate heat exchangers.

With intermediate coolant

In the case of an intermediate coolant, as in plate recuperators, two channels are provided for clean and exhaust air, but heat exchange occurs through a water-glycol solution or water. The efficiency of such a device is below 50%.

Chamber recuperators

In this form, the air passes through a special chamber (recuperator), which contains a movable damper. It is the damper that has the ability to redirect the flow of cold and hot air. Due to such periodic switching of air flows, recuperation occurs. However, in such a system there is a partial mixing of outgoing and incoming air flows, which leads to the entry of foreign odors back into the room, but, in turn, this design has a high efficiency of 80%.

Heat pipes

This mechanism has many tubes, which are assembled into a single sealed block, and inside the tubes are filled with a special easily condensing and evaporating substance, most often freon. Warm air, passing through a certain part of the tubes, heats and evaporates it. It moves into the area of ​​the tubes through which cold air passes and heats it with its heat, while the freon cools and this can lead to the formation of condensation. The advantage of this design is that polluted air does not enter the room. Optimal use of heat pipes is possible in small spaces V climatic zones with a small difference between internal and external temperatures.

Sometimes recovery is not enough to heat the room at low outside temperatures, so electric or water heaters are often used in addition to recovery. In some models, heaters perform the function of protecting the heat exchanger from icing.

Recovery in ventilation plays an important role, as it allows you to increase the efficiency of the system due to design features. There are different designs of recovery units, each of which has its own pros and cons. The choice of supply and exhaust ventilation system depends on what problems are being solved, as well as on climatic conditions terrain.

Design features, purpose

Recovery in ventilation is quite new technology. Its action is based on the ability to use the removed heat to heat the room. This happens thanks to separate channels, so the air flows do not mix with each other. The design of recuperative units can be different; some types avoid the formation of condensation during the heat transfer process. The performance level of the system as a whole also depends on this.

Ventilation with heat recovery can produce high efficiency during operation, which depends on the type of heat recovery unit, the speed of air flow through the heat exchanger and how large the difference between the temperature outside and inside the room is. The efficiency value in some cases, when the ventilation system is designed taking into account all factors and has high performance, can reach 96%. But even taking into account the presence of errors in the operation of the system, the minimum efficiency limit is 30%.

The goal of the regenerative unit is to maximize efficient use ventilation resources to further ensure sufficient air exchange in the room, as well as energy savings. Taking into account the fact that supply and exhaust ventilation with recovery operates most of the day, and also, taking into account that ensuring a sufficient frequency of air exchange requires considerable equipment power, the use of a ventilation system with a built-in recovery unit will help save up to 30% of electricity.

The disadvantage of this technique is its rather low efficiency when installed on large areas. In this case, the electricity consumption will be high, and the system performance aimed at heat exchange between air currents, may be noticeably lower than the expected limit. This is explained by the fact that air exchange occurs much faster in small areas than in large objects.

Types of recuperative units

There are several varieties used in ventilation system equipment. Each of the options has advantages and disadvantages, which must be taken into account even when forced ventilation with recovery is being designed. There are:

1. Recuperator plate mechanism. It can be made on the basis of metal or plastic plates. Along with fairly high performance (efficiency is 75%), such a device is susceptible to icing due to the formation of condensation. The advantage is the absence of moving structural elements, which increases the service life of the device. There is also a plate type of recuperative unit with moisture-permeable elements, which eliminates the possibility of condensation. A feature of the plate design is that there is no possibility of mixing two air flows.

1. Ventilation systems with heat recovery can operate based on rotor mechanism. In this case, heat exchange between air flows occurs due to the operation of the rotor. The productivity of this design increases to 85%, but there is a possibility of air mixing, which can bring odors back into the room that are removed outside the room. The advantages include the ability to additionally dry air environment, which makes it possible to use equipment of this type in special-purpose premises with an increased level of importance, for example, in swimming pools.
2. The chamber mechanism of the recuperator is a chamber that is equipped with a movable damper, which allows odors and contaminants to penetrate back into the room. However, this type of design is very productive (efficiency reaches 80%).
3. Recuperative unit with intermediate coolant. In this case, heat exchange occurs not directly between two air flows, but through a special liquid (water-glycol solution) or plain water. However, a system based on such a node has low performance (efficiency below 50%). A recuperator with an intermediate coolant is almost always used to organize ventilation in production.
4. Regenerative unit based on heat pipes. This mechanism works using freon, which tends to cool, which leads to the formation of condensation. The performance of such a system is at an average level, but the advantage is that there is no possibility of odors and contaminants penetrating back into the room. Ventilation in an apartment with recuperation will be very effective due to the fact that it is necessary to maintain relatively small area. To be able to operate such equipment without negative consequences for it, it is necessary to select a model based on a recuperative unit that eliminates the possibility of condensation. In places with a fairly mild climate, where the air temperature outside does not reach critical levels, the use of almost any type of recuperator is allowed.