Heat recovery in ventilation systems: operating principle and options. Supply and exhaust ventilation with heat recovery Wall-mounted supply and exhaust unit with heat recovery

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

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

It is to maintain these four parameters that recuperative ventilation units are used. This is especially true for modern business centers, where the natural flow of fresh air is completely absent. Industrial, administrative, retail, residential, and other premises cannot do without modern ventilation equipment. With today's air pollution, the issue of installing ventilation units with recuperation is most relevant.

It is possible to install additional filters and other devices in ventilation with recuperation, which make it possible to even better purify and process the air to the specified parameters.

All this can be done with Dantex ventilation units.

The principle of operation of the supply and exhaust ventilation system with heat recovery

Thanks to the supply and exhaust ventilation system, clean air is blown into the room, and the heated exhaust air is discharged outside. Passing through the heat exchanger, the heated air leaves some of the heat to the walls of the structure, as a result of which the cold air coming from the street heats up from the heat exchanger, without spending additional energy for heating. This system is more efficient and less energy consuming than a ventilation system without heat recovery.

The efficiency of the recuperator varies with the outside temperature and can be calculated using the general formula:

S = (T1 - T2): (T3 - T2)
where:

S- efficiency of recuperation;
T1- the temperature of the air entering the room;
T2- outside air temperature;
T3- air temperature in the room.

Types of recuperators

Plate recuperators

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

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

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

Rotary recuperators

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

No ice forms on rotary recuperators, but they are more difficult to maintain, in contrast to plate recuperators.

With intermediate heating agent

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

Chamber recuperators

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

Heat pipes

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

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

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

It should be noted that TURKOV enthalpy recuperators are the only ones manufactured in the Russian Federation.

Enthalpy recuperator 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 extract air, thereby increasing efficiency recuperator.

Recuperator moisture capacity depends on the outside temperature. The working area made of a polymer membrane passes water vapor molecules from the humidified extract air and transfers it to the dry supply air.

No mixing takes place in the recuperator supply and exhaust streams 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 size of which is 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 plate of the recuperator allows it to absorb moisture without condensation on the surface of the plates.

The casing of the supply and exhaust ventilation equipment manufactured by the company is constantly being improved, improving the properties of thermal insulation and noise absorption.
Thanks to the use of polypropylene, it was possible to achieve a dramatic reduction in the level of low-frequency noise.

Our company offers the widest range of ventilation equipment with recuperation, capable of meeting the needs of premises of various purposes and sizes.

The main differences between the supply and exhaust ventilation systems TURKOV

In addition to enthalpy recuperators, the supply and exhaust ventilation can be equipped with other types of recuperative devices, with a brief overview of which we invite you to familiarize yourself with:

About recuperation in the supply and exhaust ventilation system

This process determines the return of a certain amount of heat to reheat the air entering the room. The return is carried out through the heat exchanger of the recuperator, when part of the heat is transferred from the removed air to the incoming fresh stream. And in the hot period of summer, the heat exchanger reduces the penetration of high ambient temperatures into the room together with the supply air.

In heat exchangers extract and supply air proceeds separately, having different temperatures. Cold air in contact with the warm surface of the wall heats up. An air stream with an increased temperature, in contact with a cold surface, cools.

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 the available capacity.
• by the design of the coolant.
• existing types can be tubular, plate 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 installation site at the facility. If the recuperator serves the premises of the entire building, it is called central. Decentralized devices include those that are mounted to serve individual rooms or offices.

The main components of the recuperator design are as follows:

• a case for fixing the component parts of the unit, ensuring their safety and operability.
• a heat exchanger that exchanges heat between different energy carriers.
• fan block - for moving air flows along the exhaust and inflow.
• heating elements that maintain the required temperature.
• multistage filters with varying degrees of air purification, retaining pollution, impurities, odors.
• automation unit with programmable control elements for recuperation processes.
• controller with a panel displaying the real mode of operation by timer with the function of diagnostics of nodes, sensors.
• air dampers of various shapes with manual or electric drive, regulating the throughput of the air duct.
• valves with rubber seals, having the same function as air dampers.
• mufflers to absorb outgoing sound from a working device.

The main types of recuperators

Rotary type characteristics.

They cover a wide range of industrial and municipal applications. Having a large surface of the heat exchanger, devices of this type are quite effective. The ability to regulate the speed of the rotor, allows you to select the required optimal mode. Its efficiency is less than that of a plate recuperator. This is explained by the increased power consumption for its optimal operation. The disadvantages include the large size of the recuperator, control over the rotating rotor and partial ingress of air from the exhaust jet into the incoming air supply. For this reason, the use of rotary heat exchangers in humid and toxic environments is limited.

Rotary recuperator design and operation.

The main unit is a set of heat exchange discs with blades forming a cylindrical rotor. Rotating, it pushes air currents. And at the same time as the heat exchanger heats it up or cools it down. 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 drives alternately the heated air, then draws in the supply air, transferring part of the heat to it. The structure of the device is technically complex, which increases its cost. Its installation requires qualified installation and skillful maintenance.

Characteristics of the plate recuperative device.

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

The device is in high demand from customers. The disadvantage is the appearance of traces of freezing on the plates from the exit side. This is due to the fact that the heat exchanger plate has different temperatures with the removed air. 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. Operation resumes after defrosting the plates. The degree of freezing is regulated by a special valve. When a layer of ice forms, the valve opens and the incoming air flows for some time without heating. The warm exhaust air is directed to defrost the ice layer, and the resulting wet streams are discharged into a drainage tank and into the sewer. In this mode, the energy consumption for the operation of the recuperator is reduced to a minimum.
About the design of the recuperator and its operation. It consists of a body made of aluminum, galvanized sheet with anti-corrosion coating. The walls inside the body are covered with a layer of insulating material. Supply and extract air pass through built-in filters.

Comparing with a rotary device - the air flows in the plate recuperator are clearly delineated. The exhaust and supply channels are separated by plates. The aerodynamic characteristics and efficiency are influenced by the selected distance between the heat exchanger plates.

Heat exchange units are made of copper, aluminum or sheet steel. The aluminum heat exchanger features increased heat transfer and corrosion resistance. For manufacturing, plastic or very rarely cellulosic materials are also used. Plastic heat exchangers are lightweight, have low productivity and are used for domestic conditions. Paper heat exchangers are rarely used, but they are good at converting moisture and heat. The moisture is not removed to the atmosphere, but enters the room along with the incoming air. The number of the set of plates separating the flows can be different. The optimum distance is maintained from 5 to 9 mm. By adjusting the selection of the number of cassettes, the appearance of condensation is reduced. The thermal element of defrosting reduces the efficiency, taking away part of the electricity for its operation. The structure is easy to install, reliable in operation and low cost.

Rooftop recuperators

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

Characteristic.

Establish such supply and exhaust ventilation systems on the roofs of buildings through the holes made in them. The recuperators extract the used air collected from the ceiling and release it into the atmosphere, and its heat is transferred to the powerful incoming jet. The air supply is directed directly to the ceiling or directed to the working area. The recuperator can be an integral unit in the overall ventilation scheme of the entire facility. The device is easy to operate.

Design.

Models of units are made of different power, which is measured by the volume of passing air in cubic meters per hour. The base of the device is a frame-panel construction made of aluminum profiles. The optimum thickness of the heat exchanger sheets is about 0.2 mm. For sound and thermal insulation, the walls of the case are laid with mineral wool. Recuperators are equipped with electric, water and gas sections for heating. 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 - "glass" for the correct distribution of the load. Installing the recuperator on the roof does not take up the useful volume of the building.

Recuperator with water circulation

Characteristic.

The thermal energy carrier is water or antifreeze supplied to the supply unit from a separately located exhaust heat exchanger. The operation of a water circulation recuperator is similar to that of a water heating. The efficiency of the action of the 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 great distance supply and exhaust heat exchangers use this option is impractical. The recuperator performs only the function of heat exchange without moisture transformation.

Design.

The main nodes supply and exhaust ventilation system with heat recovery are two heat exchangers. They are installed separately in the supply and extract air ducts. Connect them with an insulated flexible pipe. It allows for an easier choice of the location of the nodes and the installation of the system. The recuperator with water circulation is equipped with a pump, expansion tank, controller, pressure indicator. Temperature sensors. Air, safety and control valves. When installing a single recuperation system, it is possible to connect several heat carriers. Different air exhaust and air flow paths ensure that the recuperator operates without the formation of traces of icing. The transfer of contaminants by the outgoing air to the inlet stream is excluded.

Selection of the air handling unit

There are special air handling unit selection programs... Using a computer, and in accordance with the requirements, the equipment is selected taking into account performance, air consumption, and suitable configuration. The program will simulate the installation with the required dimensions and characteristics. In reality, you can analyze the optimal connection of nodes and constituent elements. The program does not require special training. The selection of the air handling 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 selection is carried out automatically, according to the data entered by the customer. Further, as in a game constructor, the required nodes are removed or supplemented. For example, add a section of water heating, specifying its parameters. Or include other adjustment elements and automation kits.

Briefly about recuperator installation

Prior to the installation of the supply and exhaust ventilation system, an initial installation project is carried out. Roughly estimate the scope of the cost of 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 a detailed project is drawn up with an agreed final price.

Recuperators are mounted on walls, ceilings, roofs on the floor. They are placed 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 positioned at an inclination of about 3 degrees to the foundation of the building. The outer pipe must extend beyond the wall surface at least 5 cm.

Installation of the roof recuperator is carried out according to a special project on the load-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 a building. Its size is 700-1450 mm in diameter. Before installing the recuperator, a casing is preliminarily fixed to prevent foreign objects from entering the channels.

To move air, two air ducts are laid. The first is the main supply. It is larger in diameter. Serves for the intake and separation of air flows to each consumer. The second is of a smaller diameter for the removal of the used atmosphere. For quiet operation and to prevent condensation, the pipelines are completely insulated. By strengthening the pipes behind the suspended ceiling, they “eat up” the size of the room in height by 20 cm. The long length of the air ducts creates an increased resistance to air flow. In this case, the device is equipped with additional fans that maintain the required pressure.

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

The customer needs it.

1. Get information about the equipment manufacturer from the manager or the seller. The duration of the existence of the company, its position in the sales market and customer reviews.
2. Refine the performance of the recuperator 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 flows after installation of the unit, taking into account the dimensions and bends of the air duct. The calculation is carried out by the designer.
4. Selection of the type and power of the recuperator, taking into account the air flow rate and the resistance of the pipelines. Carried out by the designer.
5. Determination of the class (energy consumption) of the recuperator. The customer receives an answer to the questions: the costs of operating the system, the amount of energy saved, the calculation of costs for the heating season.
6. Check for certificate availability and warranty period. It is issued for the component parts of the recuperator and the entire supply and exhaust ventilation system... The better the quality of the components, the more expensive the device will be.
7. Compare the passport efficiency with the real coefficient. It depends on:
   - the difference between the air temperature in the room and the outside environment;
   - type of heat exchanger cassette;
   - air humidity;
   - correct layout of the system and its placement at the facility.

Efficiency for different types of recuperators.

• For a paper plate heat exchanger, it will be 60-70%. When the installation freezes, it is defrosting by the system itself, thereby reducing performance. The highest value is reached in the absence of defrosting function and additional heating of the incoming air.
• For an aluminum plate heat exchanger, the efficiency will be up to 63%. Sometimes productivity drops to 45%. This is due to the frequent defrosting of the heat exchanger. Ice formation on the surface is eliminated by increasing energy consumption.
• In a rotary recuperator, the efficiency is regulated by "automatic equipment". It reacts to the readings of temperature sensors located outside and in the room. However, when ice build-up appears, the efficiency decreases.

Approximate characteristics of some household recuperators.

Main factors	Quantity	unit of measurement	Note
Inflow (inflow)	115-135	cubic meters in hour	Simultaneous implementation of exhaust and inflow. Air exchange regulation is carried out within the limits of 13-160 cubic meters within one hour.
Pulling	105-125	cubic meters in hour
Recuperator dimensions
Cylindrical diameter up to	200	mm.
Body length	535	mm.
Installation hole up to	250	mm.
Power consumption is lower	32	Tue / hour
Efficiency no more	83	%
Regulation			External remote control, rheostat
Service area	60	m2
Heat exchanger			Copper. Saves up to 70% heat.
Frame			Insulated housing with anti-noise insulation
Place of application			Apartment, office, building

From all of the above, we can confidently say:

It's obvious that supply and exhaust ventilation with the recuperation company from TURKOV is at the cutting edge of modern engineering technologies.

Let us remind once again the main distinctive features of the TURKOV air handling units and invite them to our catalog to get acquainted with the detailed descriptions of the equipment:

Possibilities	Zenit	Zenit HECO	CrioVent
Stable operation of the recuperator	up to -25 ° С	up to -35 ° С	up to -45 ° С
Heat recovery (recovery efficiency)	71%

Price: 25 500 RUB

Units with recuperation and plate heat exchanger, Mitsubishi LOSSNEY are designed for air exchange and maintaining relative humidity in small rooms for various purposes. Made in japan.

Air consumption - from 55 to 100 m3 / h.

Price: 62 600 RUB

A series of air handling units with heat recovery, Daikin ( VAM-150F, VAM-250F, VAM-350FB, VAM-500FB, VAM-650FB, VAM-800FB, VAM-1000FB, VAM-1500FB, VAM-2000FB), is designed for air exchange, energy saving and maintaining relative humidity in rooms for various purposes. They are suitable for country houses, cottages, apartments and commercial premises. The main distinguishing feature of DAIKIN units is high efficiency and low power consumption. These ventilation units can operate both independently and as part of VRV air conditioning systems, as well as in conjunction with air humidifiers.

Air consumption - from 150 to 2000 m3 / h.

Price: 51 500 RUB

A series of air handling units with plate recuperator, Mitsubishi LOSSNEY ( LGH-15RX5ELGH-5E, LGH-25RX5ELGH-5E, LGH-35RX5ELGH-5E, LGH-50RX5ELGH-5E, LGH-65RX5ELGH-5E, LGH-80RX5ELGH-5E, LGH-100RX5ELGH-5E), is designed for air exchange, energy saving and maintaining relative humidity in rooms for various purposes. They are great for country houses, cottages, apartments and commercial premises. The main distinguishing feature of LOSSNEY units is their high efficiency and low power consumption. Made in japan.

Air consumption - from 100 to 1000 m3 / h.

Price: 29 500 RUB

Plant series inflow recuperative ventilation, Electrolux ( EPVS-200, EPVS-300, EPVS-450, EPVS-650, EPVS-1100, EPVS-1300), is designed for air exchange, energy saving and maintaining relative humidity in rooms for various purposes. They are great for country houses, cottages, apartments and commercial premises. The main distinguishing feature of Electrolux STAR units is high efficiency up to 90% and low power consumption.

Air consumption - from 200 to 1300 m3 / h.

Price: 131 000 RUB

A series of supply and exhaust ventilation units with plate recuperator, TURKOV ZENIT ( 200 heco, 350 heco, 450 heco, 550 heco), is designed for ventilation, energy saving and maintaining relative humidity in rooms for various purposes. They are great for country houses, cottages, apartments and commercial premises. Air handling units with heat recovery TURKOV have the ability to connect an electric heater of 1.5 kW, which makes it possible to regulate the temperature of the incoming air into the room.
Office of WI-FI and MODBAS with a smart home system.

Air consumption - from 200 to 550 m 3 / hour.

Price: 29 400 RUB

Supply and exhaust ventilation series with plate recuperator, Dantex DV ( DV-200HRE, DV-250HRE, DV-350HRE, DV-400HRE, DV-500E, DV-600HRE, DV-800HRE, DV-1000HRE, DV-1200HRE), designed for ventilation, energy saving and maintaining relative humidity in rooms for various purposes. They are great for country houses, cottages, apartments and commercial premises. Dantex heat recovery air handling units have a low power consumption that allows you to regulate the temperature of the incoming air into the room.

Air consumption - from 150 to 1200 m3 / h.

Price: 36 500 RUB

A series of air handling units with heat recovery, Royal Clima ( RCS 350, RCS 500, RCS 650, RCS 950, RCS 1350, RCS 1500), is designed for air exchange, energy saving and maintaining relative humidity in rooms for various purposes. High efficiency and low power consumption.

Air consumption - from 330 to 1500 m3 / h.

Price: 87 900 RUB

Rotary heat exchanger, UNI ( Norway) are intended for ventilation and energy saving in the premises of country houses, cottages, apartments. The main distinguishing feature of the installations is built-in electric air heater allowing to regulate the temperature of the air leaving the room, low power consumption and a wide range of operating temperatures. Supply and exhaust UNI units can be connected to the "Smart Home" system via the MODBUS protocol.

Air consumption - up to 720 m3 / h.

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

Supply and exhaust ventilation with heat recovery and recirculation,
where L is the air flow rate, T is the temperature.

Heat recovery in ventilation is a method of transferring heat energy from the exhaust air stream to the supply air stream. Heat recovery is used when there is a temperature difference between the extract air and the supply air, in order to increase the fresh air temperature. This process does not imply mixing of air streams; the process of heat transfer takes place through any material.

Temperature and air movement in the recuperator

Devices that recuperate heat are called heat recuperators. They are of two types:

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

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

Heat recovery ventilation is the most common way to use heat recovery. The main element of this system is the air handling unit, which includes a recuperator. The device of the air supply unit with a recuperator allows to transfer to the heated air up to 80-90% of the heat, which significantly reduces the power of the air heater, in which the supply air is heated, in the event of a lack of heat flow from the recuperator.

Features of the use of recirculation and recuperation

The main difference between recuperation and recirculation is the absence of mixing air from the room to the outside. Heat recovery is applicable in most cases, while recirculation has a number of limitations, which are specified in the regulations.

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

• In rooms, the air consumption in which is determined from the calculation of the emitted harmful substances;
• In rooms in which there are pathogenic bacteria and fungi in high concentrations;
• Indoors, with the presence of harmful substances, sublimated upon contact with heated surfaces;
• In rooms of category B and A;
• In rooms in which work is carried out with harmful or flammable gases, vapors;
• In rooms of category B1-B2, in which flammable dust and aerosols can be emitted;
• From systems with local suction of harmful substances and explosive mixtures with air;
• From the lobbies-sluices.

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

Recirculation ventilation allows you to increase energy efficiency, to solve the problem of energy saving in the case when 70-80% of the exhaust air enters the ventilation system again.

Recovery:
Air handling units with recuperation can be installed at almost any air flow rate (from 200 m 3 / h to several thousand m 3 / h), both small and large. Recuperation also allows the transfer of heat from the extract air to the supply air, thereby reducing the energy requirement for the heating element.

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

The air handling unit with recuperation requires maintenance, which requires a hatch in the ceiling for servicing the recuperator, filters, blowers (fans).

Main elements of air handling units

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

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

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

	Supply air temperature sensor		Heat exchanger
	Extract air temperature sensor		Motorized air valve
	Outside temperature sensor		Bypass
	Exhaust air temperature sensor		Bypass valve
	Air heater		Inlet filter
	Overheat protection thermostat		Exhaust filter
	Emergency thermostat		Supply air filter sensor
	Supply fan flow sensor		Extract air filter sensor
	Frost protection thermostat		Exhaust air damper
	Water valve actuator		Supply air damper
	Water valve		Supply fan
	Exhaust fan

Control scheme

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

Ventilation control panel

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

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

Consider a ventilation system with a flow rate of 500 m 3 / h. The calculations will be carried out for the heating season in Moscow. From SNiP 23-01-99 "Construction climatologists and geophysics" it is known that the duration of the period with an average daily air temperature below + 8 ° С is 214 days, the average temperature of the period with an average daily temperature below + 8 ° С is -3.1 ° С ...

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

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

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

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

Calculation 1: Heat is transferred to the supply air by means of an electric heater. The cost of electricity in Moscow S = 5.2 rubles / (kW * h). Ventilation works around the clock, for 214 days of the heating period, the amount of money, in this case, will be equal to:
C 1 = S * 24 * N * n = 5.2 * 24 * 4.021 * 214 = 107 389.6 rubles / (heating period)

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

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

Calculation 3: A water heater is used to heat the outside air. Estimated cost of heat from technical hot water per 1 Gcal in the city of Moscow:
S m. = RUB 1500 / Gcal Kcal = 4.184 kJ

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

In the operation of ventilation and heat exchanger throughout the cold period of the year, the amount of money for the heat of industrial water:
C 3 = S (year on.) * Q (on. On.) = 1500 * 17.75 = 26 625 rubles / (heating period)

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

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

In conclusion, I would like to note that the use of units with recuperation or recirculation in ventilation systems allows the use of the energy of the exhaust air, which makes it possible to reduce energy costs for heating the supply air, therefore, the monetary costs of operating the ventilation system are reduced. The use of the heat of the exhaust air is a modern energy-saving technology and allows you to approach the “smart home” model, in which any available form of energy is used to the fullest and most efficiently.

Many believe that an air recuperator for an apartment is an optional item that you can do without. How can supply and exhaust ventilation reduce heating costs when the whole house is connected to a central network? In fact, it will not be possible to reduce costs, but it will be possible to retain heat. In addition, the recuperator performs a number of other equally important tasks. Which ones - read our article.

Prana 150

Russian-made apartment ventilator with a capacity of 32 W / h and a maximum efficiency of 91%. Air exchange rates are 115 cubic meters / h for supply air, 105 cubic meters / h for exhaust air, 25 cubic meters / h for night mode. Users complain that the recuperation is ineffective, the air does not even have time to warm up to room temperature, but as for ventilation, everyone here puts the maximum marks.

Electrolux EPVS-200

Air handling unit with plate heat exchangers, distilling more than 200 cubic meters of air per hour. Designed for residential buildings, offices, small industrial premises. Effectively cleans the air from dust and all impurities, dries it and ionizes it.

Power 70 W. F5 (EU5) class fine filters are installed on the inlet and outlet. Self-diagnosis system.

VIDEO: The easiest and cheapest way to ventilate rooms with closed windows