Wall ventilation with heat recovery. Supply and exhaust ventilation with heat recovery

The intake of fresh air during the cold period of time leads to the need to heat it to ensure the correct microclimate of the premises. To minimize the cost of electricity can be used supply and exhaust ventilation with heat recovery.

Understanding the principles of its operation will allow you to reduce heat losses as efficiently as possible while maintaining a sufficient volume of replaced air. Let's try to understand this issue.

In the autumn-spring period, when ventilating rooms, a serious problem is the large temperature difference between the incoming and inside air. The cold stream rushes down and creates an unfavorable microclimate in residential buildings, offices and production or an unacceptable vertical temperature gradient in the warehouse.

A common solution to the problem is integration into the supply ventilation, with the help of which the flow is heated. Such a system requires electricity, while a significant amount of warm air coming out leads to significant heat losses.

The exit of air to the outside with intense steam serves as an indicator of significant heat loss, which can be used to heat the incoming flow

If the air inlet and outlet channels are located nearby, then it is possible to partially transfer the heat of the outgoing stream to the incoming one. This will reduce the consumption of electricity by the heater or completely abandon it. A device for ensuring heat exchange between different-temperature gas flows is called a recuperator.

In the warm season, when the outdoor air temperature is much higher than the room temperature, a heat exchanger can be used to cool the incoming flow.

Block device with recuperator

The internal structure of supply and exhaust ventilation systems is quite simple, so their independent element-by-element purchase and installation is possible. In the event that assembly or self-assembly is difficult, you can purchase turnkey solutions in the form of standard monoblock or individual prefabricated structures on order.

An elementary device for collecting and draining condensate is a tray located under the heat exchanger with a slope towards the drain hole

The output of moisture is carried out in a closed container. It is placed only indoors in order to avoid freezing of the outflow channels during sub-zero temperatures. There is no algorithm for reliable calculation of the volume of water received when using systems with a recuperator, so it is determined experimentally.

The reuse of condensate for air humidification is undesirable, since the water absorbs many pollutants such as human sweat, odors, etc.

Significantly reduce the amount of condensate and avoid the problems associated with its appearance by organizing a separate exhaust system from the bathroom and kitchen. It is in these rooms that the air has the highest humidity. If there are several exhaust systems air exchange between the technical and residential area must be limited by installing non-return valves.

In the case of cooling of the outgoing air flow to negative temperatures inside the heat exchanger, the condensate passes into frost, which causes a reduction in the effective cross section of the flow and, as a result, a decrease in the volume or a complete cessation of ventilation.

For periodic or one-time defrosting of the heat exchanger, a bypass is installed - a bypass channel for the movement of supply air. When the flow bypasses the device, the heat transfer stops, the heat exchanger heats up and the ice passes into a liquid state. Water flows into the condensate collection tank or it evaporates to the outside.

The principle of the bypass device is simple, therefore, if there is a risk of ice formation, it is advisable to provide such a solution, since heating the heat exchanger in other ways is complicated and time-consuming

When the flow passes through the bypass, there is no heating of the supply air through the heat exchanger. Therefore, when this mode is activated, it is necessary to automatically turn on the heater.

Features of various types of recuperators

There are several structurally different options for implementing heat transfer between cold and heated air flows. Each of them has its own distinctive features, which determine the main purpose for each type of recuperator.

The design of a plate heat exchanger is based on thin-walled panels connected in turn in such a way as to alternate the passage of different-temperature flows between them at an angle of 90 degrees. One of the modifications of this model is a device with finned channels for air passage. It has a higher heat transfer coefficient.

The alternating passage of warm and cold air flow through the plates is realized by bending the edges of the plates and sealing the joints with polyester resin

Heat exchange panels can be made of various materials:

• copper, brass and aluminum-based alloys have good thermal conductivity and are not susceptible to rust;
• plastics made of polymeric hydrophobic material with a high coefficient of thermal conductivity are lightweight;
• hygroscopic cellulose allows condensate to penetrate through the plate and back into the room.

The disadvantage is the possibility of condensation during low temperatures. Due to the small distance between the plates, moisture or frost significantly increases the aerodynamic drag. In case of freezing, it is necessary to shut off the incoming air flow to warm up the plates.

The advantages of plate heat exchangers are as follows:

• low cost;
• long service life;
• long period between preventive maintenance and ease of its implementation;
• small dimensions and weight.

This type of heat exchanger is most common for residential and office premises. It is also used in some technological processes, for example, to optimize fuel combustion during the operation of furnaces.

Drum or rotary type

The principle of operation of a rotary heat exchanger is based on the rotation of the heat exchanger, inside which there are layers of corrugated metal with a high heat capacity. As a result of interaction with the outgoing flow, the drum sector is heated, which subsequently gives off heat to the incoming air.

The fine-mesh heat exchanger of a rotary heat exchanger is prone to clogging, so you need to pay special attention to the quality work of fine filters

The advantages of rotary recuperators are as follows:

• sufficiently high efficiency compared to competing types;
• return a large number moisture that remains in the form of condensate on the drum and evaporates on contact with the incoming dry air.

This type of heat exchanger is less commonly used for residential buildings with apartment or cottage ventilation. It is often used in large boiler houses to return heat to furnaces or for large industrial or commercial and entertainment premises.

However, this type of device has significant disadvantages:

• a relatively complex design with moving parts, including an electric motor, a drum and a belt drive, which requires constant maintenance;
• increased noise level.

Sometimes for devices of this type you can find the term "regenerative heat exchanger", which is more correct than "recuperator". The fact is that a small part of the outgoing air gets back due to the loose fit of the drum to the body of the structure.

This imposes additional restrictions on the possibility of using devices of this type. For example, polluted air from heating furnaces cannot be used as a heat carrier.

Tube and shell system

The tubular type heat exchanger consists of a system of thin-walled tubes of small diameter located in an insulated casing, through which outside air is supplied. A warm air mass is removed from the room through the casing, which heats the incoming flow.

Warm air must be exhausted through the casing, and not through the pipe system, since it is impossible to remove condensate from them

The main advantages of tubular heat exchangers are as follows:

• high efficiency, due to the countercurrent principle of movement of the coolant and incoming air;
• simplicity of design and the absence of moving parts ensures low noise levels and a rarely occurring need for maintenance;
• long service life;
• the smallest section among all types of recuperation devices.

Tubes for this type of device use either light-alloy metal or, less commonly, polymer. These materials are not hygroscopic, therefore, with a significant difference in flow temperatures, intense condensate may form in the casing, which requires constructive solution on its removal. Another disadvantage is that the metal filling has a significant weight, despite the small dimensions.

The simplicity of the design of the tubular heat exchanger makes this type of device popular for self-manufacturing. As an external casing, plastic pipes for air ducts, insulated with polyurethane foam shells, are usually used.

Device with intermediate heat carrier

Sometimes the supply and exhaust air ducts are located at some distance from each other. This situation may arise due to technological features building or sanitary requirements for reliable separation of air flows.

In this case, an intermediate heat carrier is used, which circulates between the air ducts through an insulated pipeline. As a medium for the transfer of thermal energy, water or a water-glycol solution is used, the circulation of which is provided by work.

The recuperator with an intermediate heat carrier is a bulky and expensive device, the use of which is economically justified for rooms with large areas

In the event that it is possible to use another type of heat exchanger, it is better not to use a system with an intermediate heat carrier, since it has the following significant disadvantages:

• low efficiency compared to other types of devices, therefore, such devices are not used for small rooms with low air flow;
• significant volume and weight of the entire system;
• the need for additional electric pump for fluid circulation;
• increased noise from the pump.

There is a modification of this system, when instead of forced circulation of the heat exchange fluid, a medium with a low boiling point, such as freon, is used. In this case, movement along the contour is possible in a natural way, but only if the supply air duct is located above the exhaust duct.

Such a system does not require additional energy costs, but works for heating only with a significant temperature difference. In addition, it is necessary to fine-tune the point of change in the state of aggregation of the heat exchange fluid, which can be implemented by creating the desired pressure or a certain chemical composition.

Main technical parameters

Knowing the required performance of the ventilation system and the heat exchange efficiency of the heat exchanger, it is easy to calculate the savings on air heating for the room at specific climatic conditions. By comparing the potential benefits with the costs of purchasing and maintaining the system, you can reasonably make a choice in favor of a heat exchanger or a standard heater.

Often, equipment manufacturers offer a model line in which ventilation units with similar functionality differ in air exchange volume. For residential premises, this parameter must be calculated according to Table 9.1. SP 54.13330.2016

Efficiency

The efficiency of a heat exchanger is understood as the efficiency of heat transfer, which is calculated using the following formula:

K \u003d (T p - T n) / (T in - T n)

Wherein:

• T p - the temperature of the incoming air inside the room;
• T n - outdoor air temperature;
• T in - the air temperature in the room.

The maximum efficiency value at standard and certain temperature conditions is indicated in technical documentation devices. His real figure will be slightly less.

In the case of self-manufacturing of a plate or tubular heat exchanger, in order to achieve maximum heat transfer efficiency, it is necessary to adhere to the following rules:

• The best heat transfer is provided by countercurrent devices, then by cross-flow devices, and the smallest - with unidirectional movement of both flows.
• The intensity of heat transfer depends on the material and thickness of the walls separating the flows, as well as on the duration of the presence of air inside the device.

E (W) \u003d 0.36 x P x K x (T in - T n)

where P (m 3 / hour) - air consumption.

Calculation of the efficiency of the heat exchanger in monetary terms and comparison with the cost of its purchase and installation for a two-story cottage with total area 270 m2 shows the feasibility of installing such a system

The cost of recuperators with high efficiency is quite high, they have complex structure and significant size. Sometimes you can get around these problems by installing a few more simple devices so that the incoming air passes through them in sequence.

Ventilation system performance

The volume of air passed through is determined by the static pressure, which depends on the power of the fan and the main components that create aerodynamic resistance. As a rule, its exact calculation is impossible due to the complexity of the mathematical model, therefore, experimental studies are carried out for typical monoblock structures, and components are selected for individual devices.

The fan power must be selected taking into account the throughput of any type of heat exchangers installed, which is indicated in the technical documentation as the recommended flow rate or the volume of air passed by the device per unit of time. As a rule, the permissible air velocity inside the device does not exceed 2 m/s.

Otherwise, at high speeds, a sharp increase in aerodynamic resistance occurs in the narrow elements of the recuperator. It leads to extra costs electricity, inefficient heating of the outdoor air and shortening the life of the fans.

The graph of dependence of pressure loss on air flow rate for several models of high-performance heat exchangers shows a non-linear increase in resistance, therefore, it is necessary to adhere to the requirements for the recommended air exchange volume indicated in the technical documentation of the device

Changing the direction of the air flow creates additional aerodynamic drag. Therefore, when modeling the geometry of an indoor duct, it is desirable to minimize the number of pipe turns by 90 degrees. Diffusers to disperse air also increase resistance, so it is advisable not to use elements with a complex pattern.

Dirty filters and gratings create significant flow problems and must be cleaned or replaced periodically. One of effective ways clogging assessment is the installation of sensors that monitor the pressure drop in the areas before and after the filter.

Conclusions and useful video on the topic

The principle of operation of a rotary and plate heat exchanger:

Measurement of the efficiency of a plate-type heat exchanger:

Domestic and industrial ventilation systems with an integrated heat exchanger have proven their worth. energy efficiency for maintaining heat indoors. Now there are many offers for the sale and installation of such devices, both in the form of ready-made and tested models, and on an individual order. You can calculate the necessary parameters and perform the installation yourself.

If you have questions or find inaccuracies in our material while reading the information, please leave your comments in the block below.

Air handling units with heat recovery- ventilation equipment designed to supply fresh air from the street into the premises and at the same time remove old, exhaust air from low content oxygen. Supply air is blown into the outer chamber by means of a fan, and then distributed throughout the rooms through diffusers. The exhaust fan removes the exhaust air through special valves.

The main problem of intensive air exchange with the help of supply and exhaust ventilation is high heat loss. To minimize them, supply and exhaust units with heat recovery were developed, which made it possible to reduce heat losses by several times and reduce the cost of space heating by 70-80%. The principle of operation of such installations is to utilize the heat of the outgoing air flow by transferring it to the supply air.

When equipping an object air handling unit with recuperation of heat, warm exhaust air is taken through air intakes located in the most humid and polluted rooms (kitchens, bathrooms, sanitary facilities, utility rooms, etc.). Before leaving the building, the air passes through the heat exchanger heat exchanger, transferring heat to the incoming (supply) air. Heated and purified supply air enters the premises through air ducts through bedrooms, living rooms, offices, etc. This ensures constant air circulation, while the incoming air is heated by the heat given off by the exhaust air.

Types of recuperators

Air handling units can be equipped with several types of recuperators:

• plate heat exchangers are one of the most common designs of heat exchangers. Heat exchange is carried out by passing supply and exhaust air through a series of plates. Condensation may form in the heat exchanger during operation, therefore plate heat exchangers are additionally equipped with a condensate drain. Heat exchange efficiency reaches 50-75%;
• rotary recuperators - heat exchange is carried out by means of a rotating rotor, and its intensity is regulated by the speed of rotation of the rotor. The rotary heat exchanger has a high heat exchange efficiency - from 75 to 85%;
• less common types are recuperators with an intermediate heat carrier (water or a water-glycol solution acts as its role) with an efficiency of up to 40-60%, chamber recuperators divided into two parts by a damper (efficiency up to 90%) and heat pipes filled with freon (efficiency 50-70%).

Order air handling units with recuperation heat in the MirCli online store on a turnkey basis - with delivery and professional installation.

Supply and exhaust ventilation units with heat recovery appeared relatively recently, but quickly gained popularity and became a fairly popular system. The devices are able to fully ventilate the room during the cold period, while maintaining the optimal temperature regime of the incoming air.

What it is?

When using supply and exhaust ventilation in the autumn-winter period, the question of maintaining heat in the room often arises. The flow of cold air coming from the ventilation rushes to the floor and contributes to the creation of an unfavorable microclimate. The most common way to solve this problem is to install a heater that heats cold outdoor air flows before supplying them to the room. However, this method is quite energy-intensive and does not prevent heat losses in the room.

The best option The solution to the problem is to equip the ventilation system with a heat exchanger. The heat exchanger is a device in which the outflow and air supply channels are located in close proximity to each other. The heat recovery unit allows you to partially transfer heat from the air leaving the room to the incoming air. Thanks to the technology of heat exchange between multidirectional air flows, it is possible to save up to 90% of electricity, in addition, in the summer, the device can be used to cool incoming air masses.

Specifications

The heat recuperator consists of a housing, which is covered with heat and noise insulating materials and is made of sheet steel. The case of the device is strong enough and able to withstand weight and vibration loads. There are inflow and outflow openings on the case, and air movement through the device is provided by two fans, usually of axial or centrifugal type. The need for their installation is due to a significant slowdown in the natural circulation of air, which is caused by the high aerodynamic resistance of the heat exchanger. In order to prevent the suction of fallen leaves, small birds or mechanical debris, an air intake grille is installed on the inlet located on the street side. The same hole, but from the side of the room, is also equipped with a grill or diffuser that evenly distributes air flows. When installing branched systems, air ducts are mounted to the holes.

In addition, the inlets of both streams are equipped with fine filters that protect the system from dust and grease drops. This prevents the heat exchanger channels from clogging and significantly extends the life of the equipment. However, the installation of filters is complicated by the need for constant monitoring of their condition, cleaning, and, if necessary, replacing them. Otherwise, the clogged filter will act as a natural barrier to air flow, as a result of which the resistance to it will increase and the fan will break.

According to the type of construction, heat exchanger filters can be dry, wet and electrostatic. The choice of the right model depends on the power of the device, the physical properties and chemical composition of the exhaust air, as well as on the personal preferences of the buyer.

In addition to fans and filters, recuperators include heating elements which can be water and electric. Each heater is equipped with a temperature switch and is able to automatically turn on if the heat leaving the house cannot cope with the heating of the incoming air. The power of the heaters is selected in strict accordance with the volume of the room and the operating performance of the ventilation system. However, in some devices, the heating elements only protect the heat exchanger from freezing and do not affect the temperature of the incoming air.

Water heater elements are more economical. This is due to the fact that the coolant, which moves along the copper coil, enters it from the heating system of the house. From the coil, the plates are heated, which, in turn, give off heat to the air flow. The water heater control system is represented by a three-way valve that opens and closes the water supply, a throttle valve that reduces or increases its speed, and a mixing unit that regulates the temperature. Water heaters are installed in a system of air ducts with a rectangular or square section.

Electric heaters are often installed on air ducts with a circular cross section, and a spiral acts as a heating element. For the correct and efficient operation of the spiral heater, the air flow velocity must be greater than or equal to 2 m/s, the air temperature must be 0-30 degrees, and the humidity of the passing masses must not exceed 80%. All electric heaters are equipped with an operation timer and a thermal relay that turns off the device in case of overheating.

In addition to the standard set of elements, at the request of the consumer, air ionizers and humidifiers are installed in the recuperators, and the most modern samples are equipped with an electronic control unit and a function for programming the operating mode, depending on external and internal conditions. Dashboards have an aesthetic appearance, allowing the heat exchangers to organically fit into the ventilation system and not disturb the harmony of the room.

Principle of operation

In order to better understand how the recuperative system works, one should refer to the translation of the word “recuperator”. Literally, it means "return of used", in this context - heat exchange. In ventilation systems, the heat exchanger takes heat from the air leaving the room and gives it to the incoming flows. The temperature difference of multidirectional air jets can reach 50 degrees. In the summer, the device works in reverse and cools the air coming from the street to the temperature of the outlet. On average, the efficiency of devices is 65%, which allows for the rational use of energy resources and significant savings on electricity.

In practice, the heat exchange in the heat exchanger is as follows: forced ventilation drives an excess volume of air into the room, as a result of which the polluted masses are forced to leave the room through the exhaust duct. outgoing warm air passes through the heat exchanger, while heating the walls of the structure. At the same time, a stream of cold air moves towards it, which takes the heat received by the heat exchanger without mixing with the exhaust streams.

However, cooling the exhaust air from the room causes condensation to form. With the good operation of the fans, which give the air masses a high speed, the condensate does not have time to fall on the walls of the device and goes outside along with the air stream. But if the air speed was not high enough, then water begins to accumulate inside the device. For these purposes, a tray is included in the design of the heat exchanger, which is located at a slight inclination towards the drain hole.

Through the drain hole, water enters a closed tank, which is installed from the side of the room. This is dictated by the fact that the accumulated water can freeze the outflow channels and the condensate will have nowhere to drain. The use of collected water for humidifiers is not recommended: the liquid may contain a large number of pathogenic microorganisms, and therefore must be poured into the sewer system.

However, if frost from condensation still forms, it is recommended to install additional equipment– bypass. This device is made in the form of a bypass channel through which the supply air will enter the room. As a result, the heat exchanger does not heat the incoming flows, but spends its heat exclusively on melting ice. The incoming air, in turn, is heated by a heater, which is switched on synchronously with the bypass. After all the ice is melted and water is discharged into the storage tank, the bypass is turned off and the heat exchanger starts to operate normally.

In addition to installing a bypass, hygroscopic cellulose is used to combat icing. The material is in special cassettes and absorbs moisture before it has time to condensate. Moisture vapor passes through the cellulose layer and returns to the room with the incoming flow. The advantages of such devices are simple installation, the optional installation of a condensate collector and a storage tank. In addition, the efficiency of the cassettes of cellulose recuperators does not depend on external conditions, and the efficiency is more than 80%. The disadvantages include the inability to use in rooms with excessive humidity and the high cost of some models.

Types of recuperators

The modern market of ventilation equipment represents a wide range of recuperators of different types, differing from each other both in design and in the method of heat exchange between flows.

• Plate Models are the simplest and most common type of recuperators, they are characterized by low cost and long service life. The heat exchanger of the models consists of thin aluminum plates, which have high thermal conductivity and significantly increase the efficiency of devices, which in plate models can reach 90%. High efficiency indicators are due to the peculiarity of the structure of the heat exchanger, the plates in which are located in such a way that both flows, alternating, pass between them at an angle of 90 degrees to each other. The sequence of passing warm and cold jets became possible due to the bending of the edges on the plates and the sealing of the joints with polyester resins. In addition to aluminum, alloys of copper and brass, as well as polymeric hydrophobic plastics, are used for the production of plates. However, in addition to advantages, plate heat exchangers also have their weaknesses. The downside of the models is considered to be a high risk of condensation and ice formation, which is due to the plates being too close to each other.

• Rotary models consist of a housing inside which a cylindrical type rotor, consisting of profiled plates, rotates. During the rotation of the rotor, heat is transferred from the outgoing flows to the incoming ones, as a result of which there is a slight mixing of the masses. And although the mixing ratio is not critical and usually does not exceed 7%, such models are not used in children's and medical institutions. The level of air mass recuperation entirely depends on the rotor speed, which is set in manual mode. The efficiency of rotary models is 75-90%, the risk of ice formation is minimal. The latter is due to the fact that most of the moisture is retained in the drum, after which it evaporates. The disadvantages include difficulty in maintenance, high noise load, which is due to the presence of moving mechanisms, as well as the overall dimensions of the device, the inability to install on the wall and the likelihood of the spread of odors and dust during operation.

• chamber models consist of two chambers, between which there is a common damper. After warming up, it begins to turn and run cold air into the warm chamber. Then the heated air goes into the room, the damper closes and the process repeats again. However chamber heat exchanger did not gain wide popularity. This is due to the fact that the damper is not able to ensure complete tightness of the chambers, so the air flows are mixed.

• Tubular models consist of a large number of tubes that contain freon. In the process of heating from the outgoing flows, the gas rises to the upper sections of the tubes and heats the incoming flows. After heat is released, freon takes on a liquid form and flows into the lower sections of the tubes. The advantages of tubular recuperators include a fairly high efficiency, reaching 70%, the absence of moving elements, the absence of hum during operation, small size and long service life. The disadvantages are the large weight of the models, which is due to the presence of metal pipes in the design.

• Models with intermediate heat carrier consist of two separate air ducts passing through a heat exchanger filled with a water-glycol solution. As a result of passing through the thermal unit, the exhaust air gives off heat to the coolant, which, in turn, heats the incoming flow. The pluses of the model include its wear resistance, due to the absence of moving parts, and among the minuses they note a low efficiency, reaching only 60%, and a predisposition to the formation of condensate.

How to choose?

Due to the wide variety of recuperators presented to consumers, it will not be difficult to choose the right model. Moreover, each type of device has its own narrow specialization and recommended installation location. So, when buying a device for an apartment or a private house, it is better to choose a classic plate model with aluminum plates. Such devices do not require maintenance, do not require regular maintenance and are distinguished by a long service life.

This model is perfect for use in an apartment building. This is due to the low noise level during its operation and compact size. Tubular standard models have also proven themselves well for private use: they are small in size and do not buzz. However, the cost of such recuperators somewhat exceeds the cost of plate products, so the choice of device depends on the financial capabilities and personal preferences of the owners.

When choosing a model for a production workshop, a non-food warehouse or an underground car park, you should choose rotary devices. Such devices have high power and high performance, which is one of the main criteria for working on large areas. Recuperators with an intermediate coolant have also proven themselves well, however, due to their low efficiency, they are not as in demand as drum units.

An important factor when choosing a device is its price. So, the most budget options for plate heat exchangers can be purchased for 27,000 rubles, while a powerful rotary heat recovery unit with additional fans and a built-in filtration system will cost about 250,000 rubles.

Design and Calculation Examples

In order not to make a mistake with the choice of a heat exchanger, it is necessary to calculate the efficiency and efficiency of the device. To calculate the efficiency, the following formula is used: K = (Tp - Tn) / (Tv - Tn), where Tp denotes the temperature of the incoming flow, Tn is the street temperature, and Tv is the temperature in the room. Next, you need to compare your value with the maximum possible efficiency indicator of the purchased device. This value is usually specified in technical passport model or other accompanying documentation. However, when comparing the desired efficiency and that indicated in the passport, it should be remembered that in fact this coefficient will be slightly lower than prescribed in the document.

Knowing the efficiency of a particular model, you can calculate its effectiveness. This can be done using the following formula: E (W) \u003d 0.36xRxKx (Tv - Tn), where P will denote the air flow and is measured in m3 / h. After carrying out all the calculations, it is necessary to compare the costs of purchasing a heat exchanger with its efficiency converted into a monetary equivalent. If the purchase justifies itself, the device can be safely purchased. Otherwise, it is worth considering alternative methods for heating the incoming air or installing a number of simpler devices.

When designing the device yourself, it should be borne in mind that countercurrent devices have the maximum heat transfer efficiency. They are followed by cross-flow ducts, and in the last place are unidirectional ducts. In addition, how intense the heat transfer will be depends directly on the quality of the material, the thickness of the dividing partitions, and also on how long the air masses will be inside the device.

Installation subtleties

Assembly and installation of the recovery unit can be carried out independently. The simplest type of homemade device is a coaxial heat exchanger. For its manufacture take a two-meter plastic pipe for sewerage with a cross section of 16 cm and an air corrugation made of aluminum 4 m long, the diameter of which should be 100 mm. Adapters-splitters are put on the ends of a large pipe, with the help of which the device will be connected to the air duct, and a corrugation is inserted inside, twisting it in a spiral. The heat exchanger is connected to the ventilation system in such a way that warm air is driven through the corrugation, and cold air goes through a plastic pipe.

As a result of this design, there is no mixing of flows, and the outside air has time to warm up, moving inside the pipe. To improve the performance of the device, you can combine it with a ground heat exchanger. In the process of testing, such a heat exchanger gives good results. So, at an outside temperature of -7 degrees and an internal temperature of 24 degrees, the productivity of the device was about 270 cubic meters per hour, and the temperature of the incoming air corresponded to 19 degrees. The average cost of a homemade model is 5 thousand rubles.

At self-manufacturing and the installation of the heat exchanger, it should be remembered that the longer the heat exchanger is, the higher the efficiency of the installation will be. Therefore, experienced craftsmen recommend assembling a heat exchanger from four sections of 2 m each, after preliminary thermal insulation of all pipes. The problem of condensate drainage can be solved by installing a water drain fitting, and the device itself can be placed slightly at an angle.

Ventilation in rooms can be natural, the principle of operation of which is based on natural phenomena (spontaneous type) or on air exchange provided by specially made holes in a buiding (organized ventilation).However, in this case, despite the minimum material costs, the dependence on the season, climate, and the lack of the ability to purify the air do not fully meet the needs of people.

Supply and exhaust ventilation, air exchange

Artificial ventilation makes it possible to provide those in the premises with more comfortable conditions, but its device requires certain X financial investments. She is also quite energy-consuming . To compensate for the pros and cons of both types of ventilation systems, their combination is most often used.

Any is Artificial ventilation system according to its purpose is divided into supply or exhaust. In the first case, the equipment must provide forcedair supply to the room. At the same time, the exhaust air masses are brought out in a natural way.

Video - Supply and exhaust ventilation with recuperation in the apartment

Our company manufactures supply and exhaust ventilation systems using highly efficient enthalpy heat exchangers, thanks to which it was possible to achieve stable heat recovery with high efficiency in difficult climatic conditions.

It should be noted that TURKOV enthalpy heat exchangers are the only ones produced in the Russian Federation.

Enthalpy heat exchanger It is designed to transfer heat and moisture from the exhaust air to the supply air. In addition to moisture, part of the heat is transferred from the exhaust air, thereby increasing efficiency recuperator.

Moisture capacity of the heat exchanger depends on the outside temperature. The working area made of a polymer membrane allows water vapor molecules to pass from the humidified exhaust air and transfer it to the dry supply air.

There is no mixing in the recuperator supply and exhaust flows air.
Water molecules pass through the membrane due to diffusion due to the difference in the concentration of water vapor on both sides of the membrane, the cell sizes of which are so small that only water vapor can pass through it - for other substances that pollute the air flow, the membrane turns out to be a reliable barrier.

Possessing the property of a sponge, the heat exchanger plate allows it to absorb moisture without condensate falling on the surface of the plates.

Cases of supply and exhaust ventilation equipment produced by the company are constantly being improved, improving the properties of thermal insulation and noise absorption.
Thanks to the use of polypropylene, it was possible to achieve a radical reduction in the level of low-frequency noise.

Our company offers the widest range of ventilation equipment with heat recovery that can meet the needs of premises of various purposes and sizes.

The main differences between TURKOV supply and exhaust ventilation systems

In addition to enthalpy heat exchangers, supply and exhaust ventilation can be equipped with other types of heat recovery devices, with overview which we invite you to read:

About recovery in the supply and exhaust ventilation system

This process determines the return of some heat to reheat the air entering the room. The return is carried out through the heat exchanger of the heat exchanger, when part of the heat is transferred from the exhaust air to the incoming fresh flow. And during the hot summer period, the heat exchanger reduces the penetration into the room along with the supply air high temperature environment.

In heat exchangers extract and supply air flowing at different temperatures. Cold air in contact with the warm surface of the wall is heated. The air stream with an increased temperature, in contact with a cold surface, is cooled.

Main characteristics of recuperators

Supply and exhaust ventilation with recuperation is used in industrial and public facilities, as well as in residential buildings. The indicators by which ventilation units with recuperation are distinguished are as follows:

• according to available power.
• according to the design of the coolant.
• existing types can be tubular, lamellar and ribbed.
• according to the material used for heat transfer. This function is performed by air or liquid.
• in the direction of movement of the energy carrier, the direction of which can be direct, transverse or countercurrent.
• from the place of installation on the object. If the heat exchanger serves the premises of the entire building, it is called central. Decentralized devices are those that are installed for maintenance private rooms or offices.

The main components of the design of the recuperator are as follows:

• housing for fixing the component parts of the unit, ensuring their safety and performance.
• a heat exchanger that exchanges heat between various energy carriers.
• fan unit - to move the flow of air masses through the exhaust and inflow.
• heating elements that maintain the required temperature.
• multi-stage filters with different degrees of air purification, retaining pollution, impurities, odors.
• automation unit with programmable controls for recuperation processes.
• controller with a panel for displaying the real mode of operation by timer with the function of diagnosing nodes, sensors.
• air dampers of various shapes with a manual or electric drive, regulating the throughput of the air duct.
• valves with rubber seals, having the same function as air dampers.
• silencers to absorb outgoing sound from the operating device.

The main types of recuperators

Characteristics of the rotary type.

They occupy a wide range of applications in industry and in public utilities. Having a large surface of the heat exchanger, devices of this type are quite effective. Possibility of regulation of speed of turns of a rotor, allows to choose the required optimum mode. Its efficiency is less than that of a plate heat exchanger. This is explained by the increased consumption of electricity for its optimal operation. The disadvantages include: a large size of the heat exchanger, control over the rotating rotor and partial ingress of air from the exhaust jet into the incoming inflow. For this reason, the use of rotary heat exchangers in humid and toxic environments is limited.

The design of the rotary heat exchanger and its operation.

The main unit is a set of heat exchange discs with blades forming a cylindrical rotor. Rotating, it pushes air flows. And at the same time as the heat exchanger heats it or cools it. The discs, the number of which can vary, consist of cells made of corrugated sheet material. During installation, the drum shaft is oriented horizontally, maintaining parallelism to the direction of air flow. Rotating, it alternately drives out the first heated air, then draws in the supply air, transferring part of the heat to it. The structure of the device is technically complex, increasing its cost. Its installation requires qualified installation and skillful maintenance.

Characteristics of the plate recuperative device.

Working on a supply and exhaust system, it is designed for ventilation and saving thermal energy. The main characteristic is its efficiency (COP). The thermal coefficient is calculated according to this formula. The temperature difference in the room after the inflow and outside air is divided by the temperature difference between the removed and outside air.

The device is in high demand by customers. The disadvantage is the appearance of frost marks on the plates on the exit side. This is due to the fact that the heat exchanger plate has a different temperature with the air being removed. Therefore, condensation forms. Lowering the outside temperature accelerates the build-up of icing layers. Frozen plates create resistance to the passing air stream. Because of this, the ventilation performance decreases, the recovery slows down until the device stops completely. Work resumes after thawing of the plates. The degree of freezing is regulated by a special valve. When an ice layer occurs, the valve opens and the incoming air enters for some time without heating. The exhaust warm air is directed to defrosting the ice layer, and the resulting wet streaks merge into drainage tank and into the sewer. In this mode, the energy consumption for the operation of the heat exchanger is reduced to a minimum.
About the device of the recuperator and its operation. It consists of a housing made of aluminum, galvanized sheet with anti-corrosion coating. The walls inside the case are covered with a layer of insulating material. Supply and exhaust air pass through built-in filters.

Compared with a rotary device, the air flows in a plate heat exchanger are clearly demarcated. The exhaust and supply channels are separated by plates. Aerodynamic characteristics and efficiency are affected by the chosen distance between the heat exchanger plates.

Heat exchange units are made of copper, aluminum or steel sheets. The aluminum heat exchanger is characterized by increased heat transfer and corrosion resistance. For the manufacture of plastic or very rarely cellulose materials are also used. Plastic heat exchangers are light in weight, low in performance and are used for living conditions. Paper heat exchangers are rarely used, but they transform moisture and heat well. Moisture is not removed into the atmosphere, but enters the room along with the incoming air. The number of a set of plates separating the flows can be different. The optimal distance is maintained from 5 to 9 mm. By adjusting the selection of the number of cassettes, the appearance of condensate is reduced. The thermal defrost element reduces efficiency by taking part of the electricity for its operation. The design is easy to mount, reliable in operation and low cost.

Roof mounted heat exchangers

These ventilation units are used in facilities with a large working space. They filter, heat and supply air to the building. The air temperature is controlled by a duct heater or cooler. Its inflow is carried out partially or in full through the lamellar structure of the heat exchanger.

Characteristic.

Install such supply and exhaust ventilation systems on the roofs of buildings through holes made in them. Recuperators extract the used air collected under the ceiling and release it into the atmosphere, and its heat is transferred to a powerful incoming jet. The air supply is directed directly to the ceiling or directed to working area. The recuperator can be a component in general scheme ventilation of the entire facility. The device is easy to operate.

Design.

Unit models are made different power, which is measured by the volume of passing air in cubic meters per hour. The basis of the device is a frame-panel structure made of aluminum profiles. Optimal Thickness heat exchanger sheets about 0.2 mm. For sound and thermal insulation, the walls of the case are laid mineral wool. Recuperators are completed for heating with electric, water and gas sections. The achieved efficiency is about 65%. Installation of supply and exhaust ventilation does not cause any difficulties. To do this, it is necessary to make a window in the roof and strengthen the structure - the “glass” for proper load distribution. Installing a heat exchanger on the roof does not occupy the usable volume of the building.

Heat exchanger with water circulation

Characteristic.

The thermal energy carrier is water or antifreeze entering the supply unit from a separately placed exhaust heat exchanger. The operation of a heat exchanger with water circulation is similar to that of water heating. Usefulness of an action plate heat exchanger with water circulation reaches 50-65%.
Supply and exhaust ventilation with recuperators of this type is rarely used when it is possible to assemble a heat exchange line. The operation of this system requires frequent monitoring. The weak point is the presence of a pump that circulates the heat exchanger. As well as additional nodes that regulate the operation of the system. They increase energy consumption. At a large distance supply and exhaust heat exchangers, it is not advisable to use this option. The heat exchanger performs only the function of heat exchange without moisture transformation.

Design.

Main nodes supply and exhaust ventilation system with heat recovery are two heat exchangers. They are installed separately in the supply and exhaust ducts. Connect them with an insulated flexible pipeline. It allows an easier choice of the location of nodes and installation of the system. The heat exchanger with water circulation is equipped with a pump, expansion tank, controller, pressure indicator. temperature sensors. Air, safety and control valves. When installing a single recovery system, several heat carriers can be connected. Different ways of exhaust and air supply ensure the operation of the heat exchanger without the formation of traces of icing. The transfer of contaminants from the outgoing air to the inlet stream is excluded.

Selection of supply and exhaust ventilation unit

There are special ventilation unit selection programs. Using a computer, and in accordance with the requirements, they select equipment taking into account performance, air consumption, and a suitable configuration. The program will simulate the installation with the required dimensions and characteristics. In reality, it is possible to analyze the optimal connection of nodes and constituent elements. The program does not require special training. The selection of the supply and exhaust ventilation unit is facilitated by the demonstration of the selection result on the monitor. Indicate only its composition, laying the necessary information from the proposed options. The choice is made automatically, according to the data entered by the customer. Further, as in the game constructor, the required nodes are removed or supplemented. For example, add a water heating section, specifying its parameters. Or include other adjustment elements and automation kits.

Briefly about the installation of the heat exchanger

Before installing the supply and exhaust ventilation system, a primary installation project is carried out. Roughly estimate the scope of the cost future work. Having studied all the features of the object, the conditions of the customer and the capabilities of the contractor, they set the exact price. Then they draw up a detailed project with an agreed final price.

Mount recuperators on walls, ceilings, roofs on the floor. They are located in any position and on the outside of the building. The mounting opening in the wall is made with a diameter of up to 250 mm with a diamond tool. The working module of the device is located in the wall. Ventilation grilles are placed at the end. The hole in the wall is placed at an inclination of about 3 degrees to the foundation of the building. The outer pipe must protrude at least 5 cm beyond the wall surface.

Installation of the roof heat exchanger is carried out according to a special project on the bearing part of the ceiling. It is installed in a round or square structure made of galvanized steel. Or in a reinforced concrete glass, laid during the construction of the building. Its size in diameter is 700-1450 mm. Before installing the heat exchanger, a casing is preliminarily fixed to protect against foreign objects entering the channels.

Two air ducts are laid to move air. The first one is the main one. It is larger in diameter. Serves for the intake and separation of air flows to each consumer. The second one is of smaller diameter to remove the used atmosphere. The piping is fully insulated for quiet operation and to prevent condensation. By reinforcing the pipes behind the suspended ceiling, they “eat up” the size of the room in height by 20 cm. The large length of the air ducts creates increased resistance to air flow. In this case, the device is equipped with additional fans that support the required pressure.

List of questions on the choice of supply and exhaust ventilation with recuperation

The customer needs.

1. Get information about the equipment manufacturer from the manager or seller. The duration of the existence of the company, its position in the market and customer reviews.
2. Specify the performance of the heat exchanger at the place of its installation. In accordance with the size, layout of the room or house. Information can be obtained from the company's specialists.
3. Determine the resistance to air flow after installation of the unit, taking into account the dimensions and bends of the duct. The calculation is carried out by the designer.
4. The choice of the type and power of the heat exchanger, taking into account the air flow and the resistance of pipelines. Performed by the designer.
5. Determination of the class (energy consumption) of the heat exchanger. The customer receives an answer to the questions: the cost of operating the system, the amount of energy saved, the calculation of the cost of the heating season.
6. Check the availability of the certificate and the validity of the warranty. It is issued for the components of the heat exchanger and the entire supply and exhaust ventilation system. How best quality component parts - the more expensive the device will cost.
7. Compare the passport efficiency with the real coefficient. It depends on:
   - the difference between the temperature of the air in the room and the external environment;
   - type of heat exchanger cassette;
   - air humidity;
   - the correct layout of the system and its placement on the site.

Efficiency for different types of recuperators.

• For a paper plate heat exchanger, it will be 60-70%. When the installation freezes, it is defrosted by the system itself, while reducing productivity. The highest rate is achieved in the absence of the defrosting function and additional heating of the incoming air.
• For an aluminum plate heat exchanger, the efficiency will be up to 63%. Sometimes productivity decreases up to 45%. This is due to the frequent defrosting process of the heat exchanger. The formation of ice on the surface is eliminated by increasing the consumption of electricity.
• In a rotary heat exchanger, the efficiency is regulated by “automatic”. It responds to the readings of temperature sensors placed outside and in the room. However, with the appearance of ice layering, the efficiency decreases.

Approximate characteristics of some household recuperators.

From all of the above, we can confidently say:

It's obvious that supply and exhaust ventilation with a recovery company from TURKOV is at the forefront of modern engineering technologies.

Once again, we recall the main distinguishing features of the TURKOV air handling units and invite you to our catalog to get acquainted with detailed descriptions equipment: