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

What it is?

When using supply and exhaust ventilation in the autumn-winter period, the question of preserving 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 the flow of cold street air before supplying it to the room. However, this method is quite energy-consuming and does not prevent heat loss in the room.

The best option The solution to the problem is to equip the ventilation system with a recuperator. The recuperator is a device in which the air outflow and supply channels are located in close proximity to each other. The recuperation unit allows partial transfer of 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 sound insulating materials and is made of sheet steel. The device body is quite durable and can withstand weight and vibration loads. The housing has inflow and outflow openings, and air movement through the device is ensured by two fans, usually of an axial or centrifugal type. The need to install them is due to a significant slowdown natural circulation air, which is caused by the high aerodynamic resistance of the recuperator. 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 opening, but on the room side, is also equipped with a grille or diffuser that evenly distributes air flows. When installing branched systems, air ducts are mounted to the openings.

In addition, the inlets of both flows are equipped with fine filters that protect the system from dust and grease droplets. This protects the heat exchanger channels from clogging and significantly extends the service life of the equipment. However, the installation of filters is complicated by the need to constantly monitor their condition, clean them, and, if necessary, replace them. Otherwise, a clogged filter will act as a natural barrier to air flow, causing resistance to increase and the fan to break.

According to the type of design, recuperator filters can be dry, wet or electrostatic. The choice of the desired model depends on the power of the device, physical properties And chemical composition exhaust air, as well as 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 relay and is capable of automatically turning on if the heat leaving the house cannot cope with heating 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, 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 explained by the fact that the coolant that moves along the copper coil enters it from the heating system of the house. The coil heats the plates, which, in turn, give off heat to the air flow. The water heater regulation system is presented three-way valve, opening and closing 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 an air duct system with a rectangular or square cross-section.

Electric heaters are often installed on air ducts with round, and their heating element is a spiral. For correct and efficient operation of the spiral heater, the air flow speed 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 if it overheats.

In addition to the standard set of elements, at the request of the consumer, air ionizers and humidifiers are installed in recuperators, and the most modern models are equipped with an electronic control unit and a function for programming the operating mode, depending on external and internal conditions. The instrument panels have an aesthetic appearance, allowing the heat exchangers to fit seamlessly 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, you should refer to the translation of the word “recuperator”. Literally it means “return of used”, in this context – heat exchange. In ventilation systems, the recuperator takes heat from the air leaving the room and transfers it to incoming air flows. The temperature difference between multidirectional air jets can reach 50 degrees. IN summer time 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 rational use of energy resources and significant savings on electricity.

In practice, heat exchange in a recuperator looks like this: Forced ventilation drives an excess volume of air into the room, as a result of which contaminated masses are forced to leave the room through the exhaust duct. The escaping warm air passes through the heat exchanger, heating the walls of the structure. At the same time, a flow of cold air moves towards it, which takes away the heat received by the heat exchanger without mixing with the exhaust flows.

However, cooling the air leaving the room leads to the formation of condensation. If the fans work well, imparting high speed to the air masses, the condensate does not have time to fall onto the walls of the device and goes out into the street 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, the design of the recuperator includes a tray, which is located at a slight inclination towards the drain hole.

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

However, if ice still forms from condensation, it is recommended to install additional equipment– bypass. This device is made in the form of a bypass channel through which 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 the ice. The incoming air, in turn, is heated by a heater, which turns on synchronously with the bypass. After all the ice has been melted and the water has been drained into storage tank, the bypass is turned off and the recuperator begins to operate normally.

In addition to installing a bypass, hygroscopic cellulose is used to combat icing. The material is located in special cassettes and absorbs moisture before it has time to fall into condensation. 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 storage tank. In addition, the operating efficiency of cellulose recuperator cassettes does not depend on external conditions, and the efficiency is more than 80%. The disadvantages include the inability to use in rooms with excess humidity and the high cost of some models.

Types of recuperators

Modern market ventilation equipment is wide choose recuperators 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 recuperator, 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 the 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 was made possible by bending the edges on the plates and sealing the joints using polyester resins. In addition to aluminum, alloys of copper and brass, as well as polymer hydrophobic plastics, are used to produce plates. However, in addition to advantages, plate recuperators also have their own weak sides. The downside of the models is the 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 rotor consisting of profiled plates rotates. During rotation of the rotor, heat is transferred from the outgoing flows to the incoming ones, as a result of which a slight mixing of the masses is observed. And although the mixing rate 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 recovery depends entirely on the rotor rotation speed, which is set manually. 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 and then evaporates. The disadvantages include difficulty in maintenance, high noise load, which is due to the presence of moving mechanisms, as well as the size of the device, the impossibility of installing on a 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 let cold air into warm chamber. Then the heated air goes into the room, the damper closes and the process repeats again. However, the chamber recuperator has not gained wide popularity. This is due to the fact that the damper is not able to ensure complete sealing of the chambers, so the air flows are mixed.

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

• Models with intermediate coolant consist of two separate air ducts passing through a heat exchanger filled with a water-glycol solution. As a result of passing through the heating unit, the exhaust air transfers heat to the coolant, which, in turn, heats the incoming flow. The advantages of the model include its wear resistance, due to the absence of moving parts, and among the disadvantages are low efficiency, reaching only 60%, and a predisposition to condensation formation.

How to choose?

Thanks to the wide variety of recuperators presented to consumers, choose the desired model won't be difficult. Moreover, each type of device has its own narrow specialization and recommended installation location. So, when purchasing a device for an apartment or 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 have 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 dimensions. 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 is slightly higher than 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, non-food warehouse or underground parking lot, you should choose rotary devices. Such devices have great power and high performance, which is one of the main criteria for working over large areas. Recuperators with intermediate coolant have also proven themselves well, but due to their low efficiency they are not as in demand as drum units.

An important factor when choosing a device is its price. Yes, the most budget options 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 when choosing a recuperator, you should calculate the efficiency and operating efficiency of the device. To calculate the efficiency, use the following formula: K = (Tp – Tn) / (Tv – Tn), where Tp denotes the temperature of the incoming flow, Tn – outside temperature, and TV – room temperature. Next, you need to compare your value with the maximum possible efficiency indicator of the purchased device. Typically this value is specified in technical passport model or other accompanying documentation. However, when comparing the desired efficiency and that indicated in the passport, you should remember that in fact this coefficient will be slightly lower than stated in the document.

Knowing the efficiency of a particular model, you can calculate its effectiveness. This can be done by the following formula: E (W) = 0.36xPxKx (Tv - Tn), where P will denote air flow and measured in m3/h. After all the calculations have been made, you should compare the costs of purchasing a recuperator with its efficiency, converted into monetary equivalent. If the purchase justifies itself, you can safely purchase the device. Otherwise, you should think about alternative methods heating the incoming air or installing a number of simpler devices.

At independent design When using the device, it should be taken into account that counterflow devices have the maximum efficiency of heat exchange. They are followed by cross-flow ducts, and in last place are unidirectional ducts. In addition, how intense the heat exchange will be directly depends on the quality of the material, the thickness of the dividing partitions, and also on how long the air masses will remain inside the device.

Installation details

Assembly and installation of the recovery unit can be carried out independently. The most simple view homemade device is a coaxial recuperator. To make it, take a two-meter plastic pipe for a sewer with a cross-section of 16 cm and an aluminum air corrugation 4 m long, the diameter of which should be 100 mm. At the ends big pipes put on adapter-splitters, with the help of which the device will be connected to the air duct, and put the corrugation inside, twisting it in a spiral. The recuperator 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, mixing of flows does not occur, and the street air has time to warm up while moving inside the pipe. To improve the performance of the device, you can combine it with a ground heat exchanger. During testing, such a recuperator gives good results. Yes, when outside temperature at -7 degrees and internal at 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. average cost homemade model– 5 thousand rubles.

At self-production When installing a recuperator, it should be remembered that the longer the heat exchanger is, the higher the efficiency of the installation. Therefore, experienced craftsmen recommend assembling a recuperator from four sections of 2 m each, having carried out preliminary thermal insulation of all pipes. The problem of condensate drainage can be solved by installing a fitting for draining water, and placing the device itself at a slightly inclined angle.

Issues discussed in the material:

• What is heat recovery ventilation?
• Ventilation scheme with recovery
• What are the advantages of a ventilation system with recovery?
• Types of recuperators for ventilation
• How to choose air handling units with heat recovery
• Tips on how to install supply and exhaust ventilation with recovery

Each person, of course, has his own idea of ​​how comfortable housing should be arranged. For one, the appearance and interior of the premises will be of paramount importance, while the other will consider the various amenities most important. But no matter what we give preference, in any case, the majority will agree that in order for housing to be called comfortable, it is necessary that it has optimal temperature- warm in the cold season, and cool in hot weather.

Of course, no matter how we create such conditions, they are always associated with certain costs. We can use devices like air conditioners, fans, heaters. Someone will prefer to carry out repairs in such a way as to make the premises airtight. And such a move will really help preserve the internal temperature. But we must not forget that in such cases one serious trouble cannot be avoided - the housing will stop being ventilated, so there will be no talk of any comfort. The only solution is to ventilate to ensure air movement. Some may be concerned about whether this will result in additional energy costs. But they will even decrease if your choice is ventilation with heat recovery for a private house, apartment or industrial facility. What is it, how does it work? This article will tell you about this and much more.

What is heat recovery ventilation?

Home ventilation with heat recovery is one of the systems forced ventilation. It usually provides for air heating. This function is partially performed by a recuperator - a device designed to heat air, although the main heating is not provided by it, but by the air heater.

Of course, you may have never heard of supply or exhaust ventilation with heat recovery, but this does not mean that it is a new invention. Most likely, you are misled by the Latin word “recuperation,” which can be translated into Russian as “return of what was spent.” This reveals the whole point: a recuperator is a special heat exchanger, that is, a device that is quite common in ventilation systems, although in Russia it is not used as often as abroad. How does the ventilation of a private house or apartment recover? Let's take a closer look at it.

Heat recovery - This is the return of heat leaving the room. The point is that there is incoming and outgoing air flow. At the same time, the air that leaves the room heats the counter air due to heat exchange. This happens in the cold season, and on hot days, for example in summer, the outgoing air, on the contrary, cools the incoming air. But in such situations it is more correct to talk about cold recovery.

Obviously, such a procedure is necessary for the user to save available funds, because when the ventilation is not equipped with recovery, a lot of heat goes outside instead of being reused indoors. Accordingly, heating bills increase, since, in fact, we heat the street, spending an exorbitant amount of heat for nothing. It is precisely in order to avoid such waste and colossal bills that it is worth thinking about installing ventilation with heat recovery. After all, this way you return the air that you heated, do not allow the heat to leave the room, and save money.

It is not surprising that ventilation with recovery is becoming more and more popular and classic options ventilation systems have nothing to oppose such a design. This is logical, because forced ventilation with recovery is not much more expensive than conventional ventilation, and its maintenance is completely elementary. In this regard, many prefer to forget about climate control equipment, which was once positioned as the most effective in combination with ventilation systems. Recuperation is much more profitable in terms of rational use electricity, and in terms of saving heating costs. Its cheapness is compared with the cost of lighting with energy-saving light bulbs.

What else attracts consumers to a supply and exhaust ventilation system with air recovery?

Firstly, such devices have small dimensions.

Secondly, they do not spoil the interior.

Third, they have low level noise.

Fourth, with a minimum of costs we get maximum operating efficiency.

They are also in demand in public institutions, among which the following can be listed:

• Cinemas and theaters.
• Canteens, cafes, snack bars.
• Libraries.
• Hotels and inns.
• Stations.
• Offices and retail premises.

It is possible to design a ventilation system with recovery for a private house, multi-storey building, etc. The variety of such devices allows you to choose them for any occasion. The different capacities of such structures make it possible to find an option even for buildings that have a residential basement floor.

It is important to understand that supply ventilation with heat recovery for an apartment or house is coercive system. It is distinguished from natural by the presence of fans, which ensure the movement of air flows at any convenient time and do not depend on external factors, such as draft that appears due to differences in temperatures.

Ventilation scheme with recovery

What are the advantages of a ventilation system with recovery?

As we have noted more than once, the main advantage of such a system is the ability to control the interaction of air inflow and outlet. Due to this, we significantly reduce ventilation heat loss, although we continue to saturate the room with fresh air.

Now let's talk in more detail about each of the advantages of ventilation systems with recovery.

Efficiency. Natural air removal is not always the case convenient solution, because we become dependent on circumstances, environmental conditions, temperature differences. In this regard, it is much easier to use a ventilation system with recovery, which can force air. A simple example of forced ventilation is kitchen hood. More complex devices are capable, among other things, of getting rid of excess moisture. But this is simple exhaust equipment. In our case, we are talking about supply and exhaust systems that are capable of organizing the movement of air flows in both directions at once, mixing them and forming required temperatures for a comfortable stay of a person in the room, that is, to recuperate air.

Profitability. It should be noted that recuperation systems can recoup their cost through savings on heating and electricity. Costs are significantly reduced, sometimes by 5 times, that is, you are already paying 80% less than usual. Ask your friends how much heating costs them country house, if you don't have one. The numbers will be impressive. Imagine how much money recovery ventilation can save. If inexpensive elements wear out, they can be replaced without negative consequences. During the warm season, you can save on climate control equipment, while simultaneously reducing emissions into the atmosphere harmful substances. Yes, even from an environmental point of view, you are causing significantly less damage to the environment, because, among other things, you are reducing the load on the network. And don’t let it seem to you that one person is too little. Firstly, these are quite serious amounts of energy. Secondly, more and more people are switching to ventilation with recovery over the years.

Practicality. Ventilation systems with recovery are usually small in size, which means they are easy to install. Such equipment can be located in the bathroom, in the closet, and built into the ceiling. Today there are a huge variety of models to suit all tastes. So you don't have to worry about the interior.

Types of recuperators for ventilation

Recuperator - This is a heat exchanger, albeit a special one. It is connected to ventilation channels that produce air exhaust and supply. Dirty air from the room gives off heat to incoming flows, that is, a recovery procedure is performed.

Plate recuperators differ from the usual ones in that they prevent air mixing. In them, recovery is performed somewhat differently. A number of plates are located close to each other, due to which the air can transfer heat without touching. The material in such ventilation systems is usually aluminum foil, known for its thermal conductivity. There are products made of plastic. They are more expensive, but more effective.

Ventilation with recovery, performed using plate heat exchangers, often suffers from ice. The fact is that the surfaces of the recuperator are covered with ice due to condensation. This does not have the most favorable effect on the quality of the device. And then the owner of ventilation with recovery has to work hard to make the ice melt. Accordingly, time, effort, and electricity are wasted.

However, some developers have foreseen how to protect ventilation with recovery from ice. For this purpose, a technology has been invented that heats the incoming air flow to the temperature at which the condensate simply cannot freeze.

By the way, this is not the only way out. Other developers have proposed equipping ventilation systems with recuperation with cassettes made of hygroscopic cellulose. We save on heating the air, since such cellulose itself absorbs moisture and then returns it at the outlet. But they can only be used in cases where there is no over-humidification of the air.

Rotary recuperators. In recovery ventilation systems using these devices, the air is mixed. The operating principle is as follows: a metal rotor rotates, allowing air to move outward and inward. The rotation speed is usually adjustable.

As is clear, recovery in this case has a number of disadvantages, for example, it is much more expensive due to the presence of elements that fail over time. But high efficiency rates, reaching 90%, contribute to the popularity of such products.

In essence, the feasibility of purchasing such a device largely depends on the efficiency of organizing air recovery. A quality product can usually pay for itself.

Recuperators with intermediate coolant. This device has two compartments separated by a container of liquid capable of transferring heat from the outgoing to the incoming air.

Of course, recovery in this case is very safe, because contaminants are not transferred between streams. Speed ​​adjustment is provided. Wear is unlikely. But the disadvantage is the low efficiency, ranging from 45 to 60%.

Chamber recuperators. The flap divides the compartment into two halves. Rotating, it changes places of air flows. The temperature change occurs from the chamber walls.

Although air recovery in this case has a high efficiency rate of 70 to 80%, and wear is unlikely, there is a tendency for the transmission of dirt and unpleasant odors.

Heat pipes. This recovery device is made of hermetically connected tubes. They contain a substance that contributes to changes in air temperature. Most often it is some kind of freon.

Closedness avoids leakage of substances. It just flows into different sides tubes. The efficiency of such equipment is in the region of 50 – 70%.

How to choose air handling units with heat recovery

What should you remember when choosing ventilation with recovery? You need to buy such equipment so as not to regret it, so ask the seller about the following nuances:

First of all, ask the seller the following questions:

1. Who is the manufacturer of this air recovery ventilation? How long has this company been in business, what reputation does it have, what else does it produce?
2. How productive is this ventilation with air recovery?

Here you will need a specialist who can produce detailed calculation, based on the characteristics of your premises. It is clear that buying supply and exhaust ventilation with heat recovery for an apartment and a three-story house is not the same thing.

3. What will be the resistance of the system to air flows after installing this equipment?

Here again you will need specialist advice. It is important not to just limit yourself to some general characteristics indicated in the table from the Internet, but to make a detailed calculation, for example, taking into account the number of bends in the air duct and many other nuances. The ratio of air flow and system resistance is one of the most important selection factors.

4. How expensive will it be to maintain ventilation with this recuperator? What is its energy class? What are the savings when using this device?
5. What are the Efficiency Coefficients of this recuperator for ventilation?

Note that we say “coefficients” and not “coefficient”. Why? Is he really not alone? Not really. There is a declared one - this is some average value. And there is real efficiency, which is an objective indicator. What does it depend on? There are many factors. Here is the humidity and air, and how the system is organized, and the temperatures inside and outside.

• If there is a paper heat exchanger, the efficiency will be from 60 to 70 percent. What does this mean for us? Is it good or bad? This means that ventilation with air recovery is resistant to freezing, although not one hundred percent.
• If there is an aluminum heat exchanger, the efficiency will be no more than 63%, while the efficiency of the air recuperator will be from 42 to 45% percent. Thus, you will have to use a significant amount of electricity to get rid of the frost.
• A rotary air recuperator has excellent efficiency indicators, but provided that it is controlled automatically, based on the readings of special sensors. However, these recuperators can freeze in the same way as aluminum ones, which reduces efficiency.

What else should you consider when choosing a recuperator for ventilation?

Tips on how to install supply and exhaust ventilation with recovery

Now let's talk about how to install supply and exhaust ventilation with recovery. Let's start with how to choose the most suitable installation location.

• If you have a private house, then it is best to choose for installation non-residential premises. This is the basement, attic, utility room. And the boiler room is generally the most perfect option for supply and exhaust ventilation.
• Please ensure that the installation of ventilation with recovery does not contradict the requirements specified in the technical documentation.
• It is best that the distribution of the ventilation system with air recovery be in rooms where there is heating.
• Ventilation with air recovery will most likely take place in those rooms where there is no heating. These sections must be thoroughly insulated.
• It is necessary to insulate outdoor ventilation ducts with air recovery, as well as those located in external walls.
• It is advisable to locate ventilation equipment with air recovery in such a way that it is as far away from living spaces as possible, so that operating noise, which is never excluded, does not interfere.

Actually, these tips for installing ventilation with air recovery cannot be applied in all cases without exception. It is quite possible that you have other conditions and places where you can equip a similar system. Much depends on the layout of the building and the dimensions of the equipment.

Air intake For ventilation with recovery, it is better to install it on the side where the wind is less frequent. This will avoid dust and debris, or at least reduce their amount. It is important to make sure that there are no chimneys, pipes or any other places nearby where unwanted air may escape.

Installation. It is highly not recommended to install ventilation with air recovery yourself. This is a risky venture that can lead to unpleasant consequences. If you are reading this article, then you are unlikely to be an expert in the field of installing ventilation with recovery, so we recommend seeking help from professionals.

That's all. We hope that the material was useful to you!

P.S. You can always call the company " Climate Formula", and our specialists will advise you on all your questions.

Due to the increase in tariffs for primary energy resources, recovery has become more relevant than ever. In air handling units with recovery, the following types of recuperators are usually used:

• plate or cross-flow recuperator;
• rotary recuperator;
• recuperators with intermediate coolant;
• Heat pump;
• chamber type recuperator;
• recuperator with heat pipes.

Principle of operation

The operating principle of any recuperator in air handling units is as follows. It provides heat exchange (in some models - both cold exchange and moisture exchange) between the supply and exhaust air. The heat exchange process can occur continuously - through the walls of the heat exchanger, using freon or an intermediate coolant. Heat exchange can also be periodic, as in a rotary and chamber recuperator. As a result, the exhaust air is cooled, thereby heating the fresh supply air. The cold exchange process in certain models of recuperators takes place during the warm season and makes it possible to reduce energy costs for air conditioning systems due to some cooling of the supply air supplied to the room. Moisture exchange occurs between the exhaust and supply air flows, allowing you to maintain comfortable humidity in the room all year round, without the use of any additional devices - humidifiers and others.

Plate or cross-flow recuperator.

The heat-conducting plates of the recuperative surface are made of thin metal (material - aluminum, copper, stainless steel) foil or ultra-thin cardboard, plastic, hygroscopic cellulose. The supply and exhaust air flows move through many small channels formed by these heat-conducting plates in a counterflow pattern. Contact and mixing of flows and their contamination are practically excluded. There are no moving parts in the recuperator design. Efficiency rate 50-80%. In a metal foil recuperator, due to the difference in air flow temperatures, moisture may condense on the surface of the plates. In the warm season, it must be drained into the building's sewerage system through a specially equipped drainage pipeline. In cold weather, there is a danger of this moisture freezing in the recuperator and causing mechanical damage (defrosting). In addition, the formed ice greatly reduces the efficiency of the recuperator. Therefore, when operating in the cold season, heat exchangers with metal heat-conducting plates require periodic defrosting with a flow of warm exhaust air or the use of an additional water or electric air heater. In this case, supply air is either not supplied at all, or is supplied to the room bypassing the recuperator through an additional valve (bypass). Defrost time averages from 5 to 25 minutes. A heat exchanger with heat-conducting plates made of ultra-thin cardboard and plastic is not subject to freezing, since moisture exchange occurs through these materials, but it has another drawback - it cannot be used for ventilation of rooms with high humidity in order to dry them. The plate heat exchanger can be installed in the supply and exhaust system in both vertical and horizontal positions, depending on the requirements for the size of the ventilation chamber. Plate recuperators are the most common due to their relative simplicity of design and low cost.

Rotary recuperator.

This type is the second most widespread after the lamellar type. Heat from one air flow to another is transferred through a cylindrical hollow drum, called a rotor, rotating between the exhaust and supply sections. The internal volume of the rotor is filled with tightly packed metal foil or wire, which plays the role of a rotating heat transfer surface. The material of the foil or wire is the same as that of the plate recuperator - copper, aluminum or stainless steel. The rotor has a horizontal axis of rotation drive shaft, rotated by an electric motor with stepper or inverter control. The engine can be used to control the recovery process. Efficiency rate 75-90%. The efficiency of the recuperator depends on the flow temperatures, their speed and rotor speed. By changing the rotor speed, you can change the operating efficiency. Freezing of moisture in the rotor is excluded, but mixing of flows, their mutual contamination and transfer of odors cannot be completely excluded, since the flows are in direct contact with each other. Mixing up to 3% is possible. Rotary heat exchangers do not require large amounts of electricity and allow you to dry air in rooms with high humidity. The design of rotary recuperators is more complex than plate recuperators, and their cost and operating costs are higher. However, air handling units with rotary recuperators are very popular due to their high efficiency.

Recuperators with intermediate coolant.

The coolant is most often water or aqueous solutions glycols Such a recuperator consists of two heat exchangers connected by pipelines with a circulation pump and fittings. One of the heat exchangers is placed in a channel with the exhaust air flow and receives heat from it. The heat is transferred through the coolant using a pump and pipes to another heat exchanger located in the supply air channel. The supply air receives this heat and heats up. Mixing of flows in this case is completely excluded, but due to the presence of an intermediate coolant, the efficiency coefficient of this type of recuperator is relatively low and amounts to 45-55%. Efficiency can be influenced using a pump by influencing the speed of coolant movement. The main advantage and difference between a recuperator with an intermediate coolant and a recuperator with a heat pipe is that the heat exchangers in the exhaust and supply units can be located at a distance from each other. The installation position for heat exchangers, pumps and pipelines can be either vertical or horizontal.

Heat pump.

Relatively recently, an interesting type of recuperator with an intermediate coolant has appeared - the so-called. thermodynamic recuperator, in which the role of liquid heat exchangers, pipes and pump is played by refrigeration machine operating in heat pump mode. This is a kind of combination of a recuperator and a heat pump. It consists of two refrigerant heat exchangers - an evaporator-air cooler and a condenser, pipelines, a thermostatic valve, a compressor and a 4-way valve. Heat exchangers are located in the supply and exhaust air ducts, a compressor is necessary to ensure circulation of the refrigerant, and the valve switches the refrigerant flows depending on the season and allows heat to be transferred from the exhaust air to the supply air and vice versa. In this case, the supply and exhaust system can consist of several supply and one exhaust unit higher productivity, united by one refrigeration circuit. At the same time, the capabilities of the system allow several air handling units to operate in different modes (heating/cooling) simultaneously. The conversion coefficient of the COP heat pump can reach values ​​of 4.5-6.5.

Recuperator with heat pipes.

According to the principle of operation, a recuperator with heat pipes is similar to a recuperator with an intermediate coolant. The only difference is that not heat exchangers are placed in the air flows, but so-called heat pipes or, more precisely, thermosiphons. Structurally, these are hermetically sealed sections of copper finned pipe, filled inside with a specially selected low-boiling freon. One end of the pipe in the exhaust flow heats up, the freon boils in this place and transfers the heat received from the air to the other end of the pipe, blown by the flow of supply air. Here the freon inside the pipe condenses and transfers heat to the air, which heats up. Mutual mixing of flows, their pollution and transfer of odors are completely excluded. There are no moving elements; pipes are placed in flows only vertically or at a slight slope so that the freon moves inside the pipes from the cold end to the hot end due to gravity. Efficiency rate 50-70%. An important condition for ensuring its operation: the air ducts in which the thermosiphons are installed must be located vertically one above the other.

Chamber type recuperator.

The internal volume (chamber) of such a recuperator is divided into two halves by a damper. The damper moves from time to time, thereby changing the direction of movement of the exhaust and supply air flows. The exhaust air heats one half of the chamber, then the damper directs the flow of supply air here and it is heated by the heated walls of the chamber. This process is repeated periodically. The efficiency ratio reaches 70-80%. But the design has moving parts, and therefore there is a high probability of mutual mixing, contamination of flows and transfer of odors.

Calculation of recuperator efficiency.

In the technical characteristics of recuperative ventilation units of many manufacturing companies, as a rule, two values ​​of the recovery coefficient are given - by air temperature and its enthalpy. The efficiency of a recuperator can be calculated based on temperature or air enthalpy. Calculation by temperature takes into account the sensible heat content of the air, and by enthalpy, the moisture content of the air (its relative humidity) is also taken into account. Calculation based on enthalpy is considered more accurate. For the calculation, initial data is required. They are obtained by measuring the temperature and humidity of the air in three places: indoors (where the ventilation unit provides air exchange), outdoors, and in the cross section of the supply air distribution grille (from where treated outdoor air enters the room). The formula for calculating the recovery efficiency by temperature is as follows:

Kt = (T4 – T1) / (T2 – T1), Where

• Kt– recuperator efficiency coefficient by temperature;
• T1– outside air temperature, oC;
• T2– temperature of the exhaust air (i.e. indoor air), °C;
• T4– supply air temperature, oC.

Enthalpy of air is the heat content of air, i.e. the amount of heat contained in it per 1 kg of dry air. Enthalpy is determined with using i-d diagram of the state of humid air, plotting on it the points corresponding to the measured temperature and humidity in the room, outside and supply air. The formula for calculating the recovery efficiency based on enthalpy is as follows:

Kh = (H4 – H1) / (H2 – H1), Where

• Kh– recuperator efficiency coefficient in terms of enthalpy;
• H1– enthalpy of outside air, kJ/kg;
• H2– enthalpy of exhaust air (i.e. indoor air), kJ/kg;
• H4– enthalpy of supply air, kJ/kg.

Economic feasibility of using air handling units with recovery.

As an example, let’s take a feasibility study for the use of ventilation units with recovery in the supply and exhaust ventilation systems of a car dealership.

Initial data:

• object – car showroom with a total area of ​​2000 m2;
• the average height of the premises is 3-6 m, consists of two exhibition halls, an office area and a technical service station (STS);
• For supply and exhaust ventilation of these premises, duct-type ventilation units were selected: 1 unit with an air flow rate of 650 m3/hour and a power consumption of 0.4 kW and 5 units with an air flow rate of 1500 m3/hour and a power consumption of 0.83 kW.
• The guaranteed range of external air temperatures for ducted installations is (-15…+40) оС.

To compare energy consumption, we will calculate the power of a duct electric air heater, which is necessary to heat the outside air in the cold season in a traditional type air-handling unit (consisting of a check valve, a duct filter, a fan and an electric air heater) with an air flow rate of 650 and 1500 m3/hour, respectively. At the same time, the cost of electricity is 5 rubles per 1 kW*hour.

The outside air must be heated from -15 to +20°C.

The power of the electric air heater was calculated using the heat balance equation:

Qн = G*Cp*T, W, Where:

• Qn– air heater power, W;
• G- mass air flow through the air heater, kg/sec;
• Wed– specific isobaric heat capacity of air. Ср = 1000kJ/kg*K;
• T– difference in air temperature at the outlet of the air heater and the inlet.

T = 20 – (-15) = 35 oC.

1. 650 / 3600 = 0.181 m3/sec

p = 1.2 kg/m3 – air density.

G = 0.181*1.2 = 0.217 kg/sec

Qn = 0.217*1000*35 = 7600 W.

2. 1500 / 3600 = 0.417 m3/sec

G = 0.417*1.2 = 0.5 kg/sec

Qn = 0.5*1000*35 = 17500 W.

Thus, the use of ducted units with heat recovery in the cold season instead of traditional ones using electric air heaters makes it possible to reduce energy costs with the same amount of supplied air by more than 20 times and thereby reduce costs and accordingly increase the profit of a car dealership. In addition, the use of recovery units makes it possible to reduce the consumer's financial costs for energy resources for heating premises in the cold season and for air conditioning in the warm season by approximately 50%.

For greater clarity, we will carry out a comparative financial analysis of the energy consumption of supply and exhaust ventilation systems for car dealership premises, equipped with duct-type heat recovery units and traditional units with electric air heaters.

Initial data:

System 1.

Installations with heat recovery with a flow rate of 650 m3/hour – 1 unit. and 1500 m3/hour – 5 units.

The total electrical power consumption will be: 0.4 + 5*0.83 = 4.55 kW*hour.

System 2.

Traditional ducted supply and exhaust ventilation units - 1 unit. with a flow rate of 650m3/hour and 5 units. with a flow rate of 1500m3/hour.

Total electric power installation at 650 m3/hour will be:

• fans – 2*0.155 = 0.31 kW*hour;
• automation and valve drives – 0.1 kW*hour;
• electric air heater – 7.6 kW*hour;

Total: 8.01 kW*hour.

The total electrical power of the installation at 1500 m3/hour will be:

• fans – 2*0.32 = 0.64 kW*hour;
• automation and valve drives – 0.1 kW*hour;
• electric air heater – 17.5 kW*hour.

Total: (18.24 kW*hour)*5 = 91.2 kW*hour.

Total: 91.2 + 8.01 = 99.21 kW*hour.

We assume the period of use of heating in ventilation systems is 150 working days per year for 9 hours. We get 150*9 =1350 hours.

Energy consumption of installations with recovery will be: 4.55 * 1350 = 6142.5 kW

Operating costs will be: 5 rubles * 6142.5 kW = 30712.5 rubles. or in relative terms (to the total area of ​​the car dealership of 2000 m2) 30172.5 / 2000 = 15.1 rub./m2.

Energy consumption traditional systems will be: 99.21 * 1350 = 133933.5 kW Operating costs will be: 5 rubles * 133933.5 kW = 669667.5 rubles. or in relative terms (to the total area of ​​the car dealership of 2000 m2) 669667.5 / 2000 = 334.8 rubles/m2.

Recuperators

Supply- exhaust ventilation - This A complex approach to the problem of ventilation.

Supply and exhaust units provide an active flow of fresh air into the room and removal of exhaust air masses from the room. Recuperators are becoming increasingly popular, the advantage of which is the supply of fresh air heated to room temperature, with minimal annual energy consumption.

Recuperators return up to 95% of the heat back to the room, creating virtually no additional energy costs. Thus, recuperators are the most economical view ventilation unit supplying warm air to the room. This is achieved by retaining heat from waste room air on heat exchangers.

The latest models of recuperators combine the functions of supply and exhaust ventilation and fine air purification from allergens, are equipped with carbon dioxide sensors, specially designed heat exchangers to maintain optimal humidity conditions, and the ability to control from a smartphone.

Installing a recuperator effectively helps to cope with stuffiness, control room humidity, mold and dampness in the house, and condensation on plastic windows.

We are official dealer leading manufacturers, and we can provide a guarantee best price. From us you can choose and buy any model of recuperator with delivery throughout Moscow and Russia.

It is impossible to imagine comfortable suburban housing without a good ventilation system, since it is this that is the key to a healthy microclimate. However, many are cautious and even wary about implementing such an installation, fearing huge electricity bills. If certain doubts have settled in your head, we recommend taking a look at a recuperator for a private home.

We are talking about a small unit, combined with supply and exhaust ventilation and eliminating the excessive consumption of electrical energy in winter, when the air requires additional heating. There are several ways to reduce unwanted expenses. The most effective and affordable way is to make an air recuperator yourself.

What kind of device is this and how does it work? This is what we will discuss in today’s article.

Features and principle of operation

So what is heat recovery? – Recuperation is a heat exchange process in which cold air from the street is heated by the exhaust flow from the apartment. Thanks to this organizational scheme, a heat recovery installation saves heat in the house. In an apartment in a short period of time and with minimal costs electricity creates a comfortable microclimate.

The video below shows the air recovery system.

What is a recuperator? A general concept for the average person.

Economic expediency recuperative heat exchanger depends on other factors:

• energy prices;
• unit installation cost;
• costs associated with servicing the device;
• the duration of operation of such a system.

note! An air recuperator for an apartment is an important, but not the only element necessary for effective ventilation in the living space. Ventilation with heat recovery is a complex system that functions exclusively under the condition of a professional “bundle”.

Recuperator for home

As the ambient temperature decreases, the efficiency of the unit decreases. Be that as it may, a recuperator for a home is vital during this period, since a significant temperature difference “loads” the heating system. If it is 0°C outside the window, then the living space is supplied air flow, heated to +16°C. Household recuperator for an apartment it copes with this task without any problems.

Formula for calculating efficiency

Modern air recuperators differ not only in efficiency, nuances of use, but also in design. Let's look at the most popular solutions and their features.

Main types of structures

Experts emphasize that there are several types of heat:

• lamellar;
• with separate coolants;
• rotary;
• tubular.

Lamellar type – includes a structure based on aluminum sheets. This recuperator installation is considered the most balanced in terms of the cost of materials and thermal conductivity (efficiency varies from 40 to 70%). The unit is distinguished by its simplicity of execution, affordability, and the absence of moving elements. No specialized training is required for installation. Installation can be done at home, with your own hands, without any difficulties.

Plate type

Rotary– solutions that are quite popular among consumers. Their design includes a rotation shaft, powered from the mains, as well as 2 channels for air exchange with countercurrents. How does this mechanism work? – One of the sections of the rotor is heated by air, after which it turns and the heat is redirected to the cold masses concentrated in the adjacent channel.

Rotary type

Despite the high efficiency, the installations also have a number of significant disadvantages:

• impressive weight and size indicators;
• requirement for regular maintenance, repair;
• it is problematic to reproduce the recuperator with your own hands and restore its functionality;
• mixing of air masses;
• dependence on electrical energy.

You can watch the video below about the types of recuperators (starting from 8-30 minutes)

Recuperator: why is it needed, their types and my choice

note! A ventilation installation with tubular devices, as well as separate coolants, is practically impossible to reproduce at home, even if you have all the necessary drawings and diagrams at hand.

DIY air exchange device

The simplest from the point of view of implementation and subsequent equipment is considered to be a plate-type heat recovery system. This model boasts both obvious “pros” and annoying “cons”. If we talk about the advantages of the solution, then even a homemade air recuperator for the home can provide:

• decent efficiency;
• lack of “connection” to the power grid;
• structural reliability and simplicity;
• availability of functional elements and materials;
• duration of operation.

But before you start creating a recuperator with your own hands, you should clarify the disadvantages of this model. The main disadvantage is the formation of glaciations during severe frosts. Outside, the moisture level is lower than in the air in the room. If you do not act on it in any way, it turns into condensate. During frosts high level Humidity promotes the formation of ice.

The photo shows how air exchange occurs

There are several ways to protect the recuperator device from freezing. These are small solutions that differ in efficiency and implementation method:

• thermal effect on the structure due to which ice does not linger inside the system (efficiency drops by an average of 20%);
• mechanical removal of air masses from the plates, due to which forced heating of the ice is carried out;
• addition of a ventilation system with a recuperator with cellulose cassettes absorbing excess moisture. They are redirected to the home, not only eliminating condensation, but also achieving a humidifier effect.

We invite you to watch the video - Do-it-yourself air recuperator for the home.

Recuperator - do it yourself

Recuperator - do it yourself 2

Experts agree that cellulose cassettes are the optimal solution today. They operate regardless of the weather outside, and the installations do not consume electricity and do not require sewer outlet, collector for condensate.

Materials and components

What solutions and products should be prepared if it is necessary to assemble a plate-type home unit? Experts strongly recommend paying primary attention to the following materials:

1. 1. Aluminum sheets (textolite and cellular polycarbonate). Please note that the thinner this material is, the more efficient the heat transfer will be. Forced ventilation in this case it works better.
2. 2. Wooden slats (about 10 mm wide and up to 2 mm thick). Placed between adjacent plates.
3. 3. Mineral wool (up to 40 mm thick).
4. 4. Metal or plywood for preparing the body of the device.
5. 5. Glue.
6. 6. Sealant.
7. 7. Hardware.
8. 8. Corner.
9. 9. 4 flanges (according to the pipe cross-section).
10. 10. Fan.

note! The diagonal of the recuperative heat exchanger housing corresponds to its width. As for the height, it is adjusted to the number of plates and their thickness in conjunction with the slats.

Device drawings

Metal sheets are used to cut squares, the dimensions of each side can vary from 200 to 300 mm. In this case, it is necessary to select the optimal value, taking into account what kind of ventilation system is installed in your home. There should be at least 70 sheets. To make them smoother, we recommend working with 2-3 pieces at a time.

Scheme of a plastic device

In order for energy recovery in the system to be fully carried out, it is necessary to prepare wooden slats in accordance with the selected square side dimensions (from 200 to 300 mm). Then they must be carefully treated with drying oil. Each wooden element is glued to 2 sides of a metal square. One of the squares must be left unpasted.

In order for recovery, and with it air ventilation, to be more efficient, each upper edge of the slats is carefully coated adhesive composition. The individual elements are assembled into a square “sandwich”. Very important! The 2nd, 3rd and all subsequent square products should be rotated 90° relative to the previous one. This method implements alternation of channels, their perpendicular position.

The upper square, on which there are no slats, is fixed with glue. Using the corners, the structure is carefully pulled together and secured. To ensure heat recovery in ventilation systems without air loss, the cracks are filled with sealant. Flange mounts are formed.

Ventilation solutions (manufactured unit) are placed in the housing. It is first necessary to prepare several corner guides on the walls of the device. The heat exchanger is positioned so that its corners rest against the side walls, while the entire structure visually resembles a rhombus.

On the picture homemade version devices

Residual products in the form of condensate remain in its lower part. the main task consists in obtaining 2 exhaust channels, isolated from each other. Inside the structure made of plate elements, air masses are mixed, and only there. A small hole is made at the bottom to drain condensate through a hose. 4 holes are made in the design for flanges.

Formula for calculating power

Example! To heat the air in the room up to 21°C, which requires60 m3 airat one o'clock:Q = 0.335x60x21 = 422 W.

To determine the efficiency of a unit, it is enough to determine the temperatures at 3 key points of its entry into the system:

Calculation of recuperator payback

Now you know , what is a recuperator and how necessary is it for modern ventilation systems. These devices are increasingly being installed in country cottages, social infrastructure facilities. Recuperators for a private home are quite a popular product nowadays. At a certain level of desire, you can assemble a recuperator with your own hands from available materials, as mentioned above in our article.