WO2020178646A1

WO2020178646A1 - Filtration device

Info

Publication number: WO2020178646A1
Application number: PCT/IB2020/051057
Authority: WO
Inventors: Marek Prymon
Original assignee: Thessla Green Sp. Z O.O.
Priority date: 2019-03-04
Filing date: 2020-02-11
Publication date: 2020-09-10
Also published as: WO2020178646A8; PL429143A1

Abstract

The subject of invention is a filtration device to be installed in ventilation or air conditioning systems consisting of a housing equipped with connection ports, a filtration unit equipped with a controlled fan and at least one sensor for measuring the concentration of air pollutants connected to the microcontroller controlling the fan, characterized in that in the space of the filtration chamber (2), formed by the housing of the filtration device (3), a filtration unit (4) composed of at least a pre-filter (5) and a HERA fine filter (6) and a fan (8) with adjustable capacity, placed in a common structure (9), whereby the fan (8) is mounted tightly with its suction side to the outlet baffle of this structure, preferably enabling two-sided replacement of the filters and permanently connected to the housing of the filtration device (3), with dimensions and location in the filtration chamber (2), dividing the space in the filtration chamber (2) into an air inlet section (10), an air outlet section (11) and a bypass duct (12), so that the space from the inlet air port side (13) between the wall of the filtration device housing (3) and the surface defined by the frontal surface of the air inflow to the filtration unit (4) forms the air inlet section (10) and the space from the outlet air port side (14) between the wall of the filtration device housing (3) and the area defined by the outlet structural surface of the filtration unit (9) forms the air outlet section (11) with the cross-sectional area of the filtration unit (4) in the plane perpendicular to the direction of air flow through the filtration device (4) and passing through the centre of the structure (9) of the filtration unit (4) being 40% - 90% of the cross-sectional area of the filtration chamber (2) while the remaining space of the filtration chamber is the bypass duct (12), whereas the fan (8) of the filtration unit (4) is controlled by a microcontroller (15), to which a sensor for outlet air pollution concentration (18) is connected, mounted downstream of the outlet port (14) or by the user, using the control panel (16).

Description

Filtration device

The subject of the invention is a filtration device designed to filter the air supplied to rooms through a mechanical ventilation system and through an air conditioning system. The filtration device is designed to be installed in the main supply duct of a mechanical ventilation system. The purpose of the filtration device is to thoroughly purify the air supplied to the ventilated rooms.

In order to ensure adequate air purity in the rooms of buildings, especially in large agglomerations or industrialised areas, mechanical ventilation and air conditioning systems use air filtration. In this process, the purification of fresh ventilation air supplied from the outside is of particular importance, as it is a major source of indoor air pollution, particularly harmful to human health with dust particles of less than 1 micrometer. These are pollutants in the form of particulate matter (atmospheric aerosols - PM - particulate matter) with particles smaller than 1 , 2.5, 4, 10 micrometers respectively and designated as PM1 , PM2.5, PM4, PM10.

Air filtration is carried out by means of a single filter or an air filter system with a specific filtration performance, installed in ventilation ducts or in an air handling unit/air conditioning unit. Effective filtration by lowering the concentration of pollutants in the air flowing into the rooms, improves the health and well-being of room users, protects the equipment in the air handling unit/air conditioning unit and in the duct network (especially in heat exchangers) and the ventilation ducts themselves against dust contamination, extending their operating time and improving their effectiveness.

Air filters used to ensure adequate purity of the air supplied to rooms by means of mechanical ventilation and air conditioning systems should have the highest possible pollutant retention efficiency and the lowest possible air flow resistance.

In addition to pre-filters, high efficiency particulate air filters (HEPA) filters, are used in mechanical ventilation and air conditioning systems to achieve high supply air quality in the 1 pm to 10 pm particle size range. Such filters are used e.g. for air disinfection, as well as for ventilation or air conditioning of rooms where a sterile environment is required.

HEPA filter filtration material is made of randomly arranged glass fibres with diameters from 0.5 pm to 2 pm. The structure of the material ensures air flow through pores of about 0.3 pm. HEPA filters retain more than 99.97% of mechanical impurities, larger than 0.3 pm, as well as: fungal cells, protozoa and bacteria and most viruses. HEPA filters, as a rule, are not an integral part of the air conditioning or ventilation equipment used in residential buildings because of the large and highly fluctuating air flow resistance. These resistances vary from 100 to 150 Pa for a new, uncontaminated filter to 600 Pa for a dirty filter. Such high airflow resistance values make it impossible to use these filters in typical compact air handling units connected to residential buildings, whose available pressure does not exceed 200 Pa at the nominal air flow rate.

The use of HEPA filters in central supply air filtration systems would enable the practical elimination of the influence of smog on air quality in buildings. The problem, however, is the high resistance of the fine filter forcing the use of a much larger fan in the air handling unit than would be necessary in the case of installation without a fine filter, which in practice means the use of unreasonably larger air handling units. In addition, in a classic system, where the HEPA filter is installed as a duct filter, the fan must overcome the resistance of the filter at all times, regardless of whether filtration is needed or not (because for example the value of the pollutant concentration in the air pumped through the system is lower than the setpoint (required) by the user). Another disadvantage of the classic solution of a filtration system, i.e. the use of a fine filter installed in a duct, is its significant impact on air flow. The airflow resistance of a HEPA filter varies between 450 Pa and 500 Pa depending on whether it is new or worn out. In order to maintain a constant flow of air, in addition to a properly oversized fan, a flow control system is required. Otherwise, increasing resistance of the filter along with its contamination will reduce the air flow in the system by several dozen percent (depending on the characteristics of the fan used). Installation of a fine air filter in a ventilation duct, in small ventilation systems present in residential buildings, where the total system resistance does not exceed 150 - 200 Pa, requires the use of more than twice the size of an air handling unit. For this reason, in practice, solutions in the form of a fine air filter in a ventilation duct are not used, and the fine air purification in residential rooms is usually carried out with portable air purifiers.

There are known solutions in which the fine filter is equipped with a fan ensuring that its resistance is overcome, regardless of the air handling unit fan operation. A fine filter with a fan is a unit that is mounted in the main duct. With proper selection of fan characteristics, such a unit overcomes the fine filter resistance regardless of the resistance of the whole system, thanks to which the value and variability of fine filter resistance does not force oversizing of the air handling unit. Fine filter and fan units designed to overcome its resistance are also used at the air inlet to the ventilation system or downstream of the air handling unit in the form of a parallel bypass equipped with a damper or a damper assembly. If the bypass damper is closed, the air is directed to a duct with a fine filter and the fan to overcome its resistance and after filtering the air is introduced into the main ventilation duct downstream of the closed damper.

The description of a Chinese utility model number CN206683200(U) reveals a solution representing a fine filter unit to be installed as part of a ventilation system. The unit is placed in a chamber which has an inlet and outlet matching the dimension of the ventilation system in which it is to be installed. The unit chamber is divided into two separate parts; the inlet chamber and the outlet chamber. The outlet chamber covers only part of the unit chamber and has two walls perpendicular to the chamber axis and parallel to the axis. In the wall perpendicular to the axis of the unit's chamber there is a section of the ventilation duct with a damper inside which can be closed. In the wall parallel to the axis of the unit chamber there is a fine filter integrated with the fan. When the damper in the vertical wall is open, air flows between the inlet and outlet and is not filtered. After closing the damper and switching on the fan, the air from the inlet chamber passes to the outlet chamber through the fine filter and is directed to the outlet of the filtration unit chamber.

The description of the Chinese utility model number CN205783364U reveals a solution of an air purification device in the ventilation system.

The purification device is mounted on the air inlet to the ventilation system. It consists of two fans at the inlet and outlet of the unit and the space between them in which a filtration unit consisting of two HEPA filters, an active carbon filter and catalytic filters is located. In order to overcome the resistance of the filtration unit, two fans are used, the first one pumping air into the filters and the second one extracting purified air and pumping it into the ventilation system, whose air handling unit distributes purified air streams only.

Known state-of-the-art solutions for equipping typical new and existing ventilation systems with fine filter units, without the need to use fans with powers exceeding those of such ventilation systems, are complex, complicated and thus expensive structures or are uneconomic or do not provide sufficiently effective air filtration in ventilation systems.

The aim of the invention is the design of a new type of filtration device intended for the fine filtration of air supplied to rooms through a mechanical ventilation or air conditioning system, whose impact on the air flow resistance in the ventilation or air conditioning system in which the filtering device, according to the invention, is installed, is negligible and independent of the degree of wear of the filters used in it - including the fine filter.

The essence of the filtration device, according to the invention, is a design that allows fine filtration of the air pumped in the ventilation system, without the need to install air handling units of higher power. The filtration device to be installed in ventilation or air conditioning systems consists of a housing equipped with connection ports, a filtration unit equipped with a controlled fan and at least one sensor for measuring the concentration of air pollutants combined with a microcontroller controlling the capacity of the fan, and is characterised by the fact that in the space of the filtration chamber formed by the housing of the filtration device, a filtration unit consisting of at least a pre-filter and a HEPA fine filter and a fan with adjustable capacity is installed. The parts of the filtration unit are placed in a common structure allowing the filters to be replaced on both sides and permanently connected to the housing of the filtration device and the fan is tightly fixed with its suction side to the outlet baffle of this structure, covering the outlet side of the filtration unit and having a suitable opening for fan installation. The dimensions of the filtration unit and its location in the filtration chamber divides the space of the filtration chamber into the air inlet section, the air outlet section and the bypass duct. The space from the inlet air port side between the wall of the filtration device housing and the surface determined by the front surface of the filtration unit, onto which the air forced through by the fan flows, forms the air inlet section. The space from the outlet air port between the wall of the filtration device housing and the surface defined by the outlet surface of the filtration unit forms the air outlet section. The cross-sectional area of the filtration unit constitutes 40% - 90% of the cross-sectional area of the filtration chamber, perpendicular to the direction of air flow through the filtration unit passing through the centre of the structure of the filtration unit, while the remaining space of the filtration chamber constitutes a bypass duct. The fan of the filtration unit is controlled by the microcontroller on the basis of a comparison of the setpoint value of the concentration of pollutants in the air downstream of the filtration device set by the user from the control panel with the value read from the sensor mounted downstream of the outlet port and connected to the microcontroller, or by the user using the control panel.

The filtration unit consists of filters which are placed in order from the fan side: the HEPA fine filter, the carbon filter and the pre-filter. The filtration unit is located in the filtration chamber transversely to the direction of air flow in the ventilation system, in the section where the filtration device is installed.

The size of the filtration unit measured in the direction parallel to the air flow in the system is 30% - 80% of the filtration chamber size.

The fan of the filtration unit has a nominal capacity of at least 20% more than that of the system in which the filtration device is installed.

The fan of the filtration unit forces the recirculation air flow in the bypass duct, the direction being opposite to that of the air flowing through the filtration unit.

Each filter comprising the filtration unit is installed separately in the filtration unit design, which makes it possible to replace filters easily on both sides. The length of the rails for the installation of the filters is adjusted to the size of the filtration unit and is equal to the width of the structure.

Preferably, the width of the filtration unit structure is the width of the filtration chamber.

In the design version of the filtration device, the width of the filters included in the filtration unit and the structure fixing the filtration unit is smaller than the width of the filtration chamber, and the filtration unit is located at one of the walls of the filtration chamber or centrally.

The chamber in which the ports are placed on opposite walls is a pass-through chamber, where streams of incoming and outgoing air have the same sense and direction. A chamber in which the ports are placed on one wall is a bypass chamber, where streams of incoming and outgoing air have the same direction but the opposite sense.

The filtration unit, in the pass-through type filtration chamber, is located centrally at any height, preferably not on the axis of the air inlet and outlet port. The space on the inlet air port side between the wall of the filtration device housing and the surface of the filtration unit is the air inlet section. The space on the outlet air port side, between the wall of the filtration device housing and the outlet surface of the filtration unit, is the air outlet section. The width of the air inlet section is 10% - 40% of the filtration chamber dimension, measured in the direction parallel to the air flow in the system and the width of the air outlet section is 10% - 50% of this dimension.

The filtration unit, in the bypass type filtration chamber, is centrally located at any height, in the space between inlet and outlet ports, preferably not in the immediate vicinity of air inlet and outlet. The air inflow section constitutes 10% - 40% of the filtration chamber dimensions, measured perpendicularly to the air flow in the system, in the section where the filtration device is installed and the width of the air outflow section constitutes 10% - 50% of this dimension.

A different embodiment of the filtration device is a device with a pass-through cylinder type filtration chamber. The filtration chamber is cylindrical in shape, with one base having the air inlet port to the filtration chamber and the other base having the air outlet port from the filtration chamber. The filtration unit is a hollow cylindrical shape closed on the side of the incoming air and with the fan of the filtration unit installed on the side of the outlet air port. The side surface of the cylinder constituting the filtration unit is made of layers of filtration material. The pre-filter filtration material is the outer layer and the fine filter material the inner layer of the filtration unit. The set of filters is the layered side surface of the cylinder and the outlet side of the filtration unit is the inner surface of the hollow cylinder. The outer surface of the filtration cylinder is the front side of the air intake of the filtration unit. The space between the front of the filtration unit and the housing of the filtration device is the air inlet section and the space between the filter cylinder and the outlet port is the air outlet section.

The filtration unit has adjustable capacity. The adjustment is effected by changing the fan speed. The fan capacity is controlled smoothly, as a function of pollutant concentration in the air flowing out of the filtration chamber, by a microcontroller connected to a sensor of pollution concentration in the outgoing air, mounted in the outlet air duct of the filtration chamber. The setpoint value of pollutant concentration in the outgoing air is determined by the control panel.

An alternative to automatic control is manual control by setting the fan capacity of the filtration unit by the user via the control panel, by inputting the required fan operation settings.

The filtration device according to the invention also works properly without an air quality sensor. In this case, the rotational speed of the fan rotor of the filtration unit is set by the user and remains constant until the next setting is made by the user, and the level of pollutant concentration at the outlet of the device is the result of the setting and depends on the set rotational speed of the fan rotor, the air quality at the particular moment and the air flow stream in the system. This option is less economical than the option with a sensor placed downstream of the outlet, which enables smooth control of the fan speed and thus controls the momentary intensity of filtration. If a filtration device is equipped with sensors both upstream of the inlet to the filtration chamber and downstream of the outlet from the filtration chamber, the momentary value of filtration efficiency is monitored.

The advantage of the filtration device according to the invention is the possibility to adjust the filtration intensity to the current needs by smoothly controlling the fan capacity of the filtration unit. The filtration device will use exactly as much energy as is necessary to purify the air to the required condition. The design of the filtration device according to the invention allows significant savings resulting from reduced power consumption in comparison to a filter permanently installed in a duct. Moreover, in the case of a filtration device according to the invention, the air flows through the filtration unit only when necessary and only with the intensity required to achieve the required air quality at the outlet of the filtration chamber, so that the filter is used up more slowly, which reduces the cost of replacing it compared to a classical duct filter.

The filtration device according to the invention is not equipped with any airflow cut-off device. The bypass duct of the filtration chamber remains open regardless of whether the fan of the filtration unit is running or not.

The device has a simple design, easy to install and maintain. The filtration unit, according to the invention, can be installed in new and existing ventilation and air conditioning systems that do not have fine anti-smog filters in the system.

The filtration device according to the invention has a number of additional advantages;

> The effect of the filtration device installed in the ventilation duct on the increase of air flow resistance in the system is negligible and independent of the degree of filter wear at a particular time. This allows the device to be used in any existing system regardless of its extent, size or capacity.

> The filtration device can be installed without any technical problems on virtually any type of ventilation or air conditioning system.

> With a recirculation air stream ratio of 1.2 to 2.5 to the nominal ventilation air stream, the filtration unit purifies the air with accuracy not inferior to typical fine duct filters.

> The filtration device operates in passive or active mode, i.e. it operates only when air purification is required and consumes only as much energy as is needed to bring the air to the condition required by the user. > The filtration device operates in automatic mode keeping the concentration of pollutants in the air supplied to the building (or room) at a preset level. In this mode, the fan capacity (and thus energy consumption) is variable, as it depends on the momentary need - the controller keeps the pollutant concentration at the outlet of the filtration device constant, at a preset level.

> The filtration device also operates in manual mode at a constant filtration intensity set by the user for a particular time. In this mode, the value of pollutant concentration at the outlet of the filtration device is the result of - and depends on the condition of the air at a particular, the set intensity of the device's operation and the stream of air flowing in the system in which the filtration device is installed.

> The filtration device is installed in the main supply air duct of a mechanical ventilation system supplying air to rooms downstream of the air handling unit or on any section of the ventilation system branch supplying air to the zone where it is intended to improve air quality.

The filtration device according to the invention is shown in the drawing, in an example of embodiment, presented in a schematic view, Fig. 1 shows a rectangular cross- section of the filtration device, Fig. 2 shows a diagram of the connection of the filtration device according to the invention to the ventilation system and Fig. 3 shows a diagram showing the efficiency of air purification by the filtration device connected to the ventilation system, based on measurements carried out under actual conditions.

The filtration device consists of a filtration chamber (2) inside which there is a filtration unit (4), the fan of the filtration unit (8), and through the appropriate location of the filtration unit (4) in the filtration chamber (2) a bypass duct (12), an air inlet section (10) and an air outlet section (1 1 ) are designated. The filtration device is equipped with an outlet air pollution concentration sensor (18) and an inlet air pollution concentration sensor (17) as well as a microcontroller (15) controlling the fan capacity (8) of the filtration unit (4) and a control panel (16) for manual setting of the fan capacity (8) of the filtration unit and for setting the expected value of pollution concentration at the outlet of the device.

The device is equipped with two sensors that measure the concentration of pollutants. Sensor (17) measures the concentration of pollutants in the air entering the chamber and sensor (18) measures the concentration of pollutants in the air leaving the filtration chamber (2). The capacity of the fan (8) of the filtration unit (4) is dependent on the concentration of pollutants in the air flowing out of the filtration chamber (2). The rotation of the fan (8) is adjusted by a microcontroller (15) which keeps the concentration of pollutants in the air flowing out of the filtration chamber (2) at a preset level. In the case of an increase in the concentration of pollutants in the air flowing into the filtration chamber (2), the controller increases the speed of the fan (8), thus increasing the air flow through the filtration unit (4). Decreasing the concentration of pollutants causes a reduction in the fan speed (8) and thus a decrease in the air flow through the filtration unit (4).

In the filtration chamber (2), formed by the housing (3) of the filtration device (1 ), a filtration unit (4) consisting of a pre-filter (5), a carbon filter (7) and a HEPA fine filter (6) is installed and tightly connected to the structure of the filtration chamber, with the suction side of the fan (8) with adjustable capacity. The elements of the filtration unit (4) are placed in a common structure (9) enabling filter replacement and permanently connected to the housing of the filtration device. Each filter in the filtration unit is installed separately in an assembly consisting of an upper and a lower rail, which are fixed permanently to the structure of the filtration unit (9). The length of the rails for mounting the filters and the length of the filtration unit (4) is equal to the width of the filtration chamber (2). The filtration unit (4) is located in the filtration chamber (2) and the structure of the filtration unit (9) is permanently attached to the housing (3) of the filtration device (1 ). The space on the side of the inlet port (13) to the filtration chamber (2) between the wall of the filtration device housing (1 ) and the surface defined by the frontal area of the air inlet to the filtration device (4) forms the air inlet section (10). The space on the outlet port side (14) of the filtration chamber (2) between the housing wall of the filtration device (1 ) and the surface defined by the structural surface on which the fan (8) is fixed forms the air outlet section (1 1 ). The cross-sectional area, perpendicular to the direction of air flow through the filtration unit (4) of this unit represents 40% - 90% of the cross-sectional area of the filtration chamber. The filtration unit is placed in the filtration chamber transversely to the direction of ventilation air flow in the system in the section where the filtration device is installed. The fan of the filtration unit is controlled by a microcontroller (15), to which a sensor for outlet air pollution concentration (18) is connected, mounted downstream of the outlet port (14).

The fan of the filtration unit (8) has a nominal capacity of at least 20% more than that of the system (19) in which the filtration unit is installed according to the invention.

The filtration device according to the invention works as follows: When the value of pollutant concentration measured in the air supplied by the ventilation system to the building or an area of the building is lower than the required value, the filtration device enters passive mode, in which the fan (8) of the filtration unit (4) is switched off and the air stream flowing through the ventilation system (19) flows freely through the bypass duct (12) of the filtration chamber (2) bypassing the filtration unit (4) due to significantly higher flow resistance of the filtration unit (4) compared to the bypass duct (12). In the passive mode, the energy consumption results only from the operation of the control system (15), which consumes a few [W] The processor of the microcontroller (15) decides about the transition to the passive mode on the basis of instantaneous readings of the pollutant concentration values from the pollutant concentration sensor (18) located downstream of the air outlet of the filtration chamber (2). When the value of the concentration of pollutants measured in the air supplied by the ventilation system (19) to the building or an area of the building is higher than the required value, the filtration device, according to the invention, switches to the active mode, in which the fan (8) that forces the air through the filtration unit (4) is started. If the differences between the pollutant concentration values in the air entering through the inlet (13) to the filtration chamber (2) and the set (required) pollutant concentration at the outlet (14) from the filtration chamber (2) are small, only part of the air flows through the filtration unit (4) and the remaining part flows through the bypass duct (12). In this case, the concentration of pollutants in the air leaving the filtration chamber (2) is the result of mixing the air stream that flows through the filtration unit (4) and the air stream that flows through the bypass duct (12).

The filtration device according to the invention was implemented, in the form of a working prototype, installed in a mechanical ventilation system and tested.

The housing of the filtration device is rectangular in shape with dimensions 623 x 617 x 310 mm and is closed with two panels with dimensions of 623 x 617 x 30 mm. The housing and closing panels are made of 0.8 mm thick steel sheet. The housing is fitted with a 30 mm thick XPE foam insulation, which provides thermal and acoustic insulation. The closing panels are connected to the housing by means of hinges and closed by means of buckle locks. The panels allow two-sided access to all parts installed in the housing and thus enable easy filter replacement. The housing is equipped with inlet and outlet ports, placed coaxially on opposite side walls of the device at a distance of 165 mm from the top surface of the device. Ports with a diameter of 199 mm were used to enable the installation of a filtration device in a system with a diameter of 200 mm, by pushing the ducts of the system onto the inlet and outlet ports of the filtration device. The structure of the filtration unit is made of 0.8 mm thick steel sheet. It consists of an element with the shape of an inward-lipped C section with dimensions of 310 x 247 x 25 mm and a length of 316 mm with the ridge facing the lower side of the device and of the outlet baffle part to which the fan is attached. The construction height of the filtration unit is equal to the internal height of the filtration device (557 mm). The structure of the filtration unit is permanently connected to the filtration device housing by riveting to the housing parts. The outlet baffle of the filtration unit structure has a 175 x 175 mm hole adapted to the installation of the fan. The filters are installed parallel to the outlet baffle in mounting guides formed by a set of angles and C-sections riveted to the filtration unit structure in the direction parallel to the outlet baffle.

A class F7 pre-filter of 305 x 305 x 50 mm and a HEPA13 filter of 305 x 305 x 150 mm, placed in independent guides 30 mm apart, were used in the filtration device. The filters are sealed with a polyurethane gasket glued to the perimeter of each filter frame. The centrifugal fan with a rotor diameter of 190 mm, with a DC EC motor, is tightly mounted using four M5 screws, with the suction side on the outlet baffle on the outlet port side. Dimensions of the filtration unit: dimension along the port axis including the fan is 423 mm, dimension along the filter guides is 310 mm, height of the filtration unit is 310 mm. The distance of the filtration unit (calculated from the front surface of the filtration unit, i.e. the surface of the air inflow to the pre-filter) from the side of the device with the inlet port is 98.5 mm, the distance of the filtration unit (calculated from the surface of the fan motor) from the side with the outlet port is 40.5 mm. The height of the bypass duct above the filtration device = 245 mm and its width is 308.5 mm.

The device's inlet and outlet port is equipped with pollution concentration sensors, based on HPMA1 1550 particle sensors and electronic systems enabling the transfer of the measurement results to the controller.

The controller with a PIC24F microcontroller is placed on the external wall of the side of the filtration device under the inlet port. The controller is connected to the communication cables of sensors measuring the particulate concentration at the inlet and outlet of the unit, the power supply and control cables of the fan and the communication cables of the control panels, including the AirS panel for setting the constant fan speed (allows the unit to operate only in manual mode, where the fan speed controller is not activated as a function of the particulate concentration value at the outlet of the unit, and the concentration of pollutants at the outlet is a result depending on the momentary condition of the air, the set speed of the fan and the air flow in the ventilation system), and the advanced Air++ panel, which allows the device to operate in automatic mode by assigning the expected value of particulate concentration at the outlet of the unit.

The filtration device, according to the invention, solved the biggest problem of HEPA fine filters, namely high resistance of air flow through these filters, which radically changed the operating conditions of air handling units and air conditioning units.

Thanks to the use of a filtration device according to the invention, the fine air filtration has become possible in any mechanical ventilation system, also in those that have not been designed for fine purification and are currently in operation. The use of the filtration device according to the invention will definitely improve the conditions for fighting smog in all buildings and rooms with ventilation or air conditioning systems.

List of designations:

1. Filtration device

2. Filter chamber

3. Filtration device housing

4. Filtration unit

5. Pre-filter

6. HEPA fine filter Patent claims:

Filtration device to be installed in ventilation or air conditioning systems consisting of a housing equipped with connection ports, a filtration unit equipped with a controlled fan and at least one sensor for measuring the concentration of air pollutants connected to the microcontroller controlling the fan, characterized in that in the space of the filtration chamber (2), formed by the housing of the filtration device (3), a filtration unit (4) composed of at least a pre-filter (5) and a HE PA fine filter (6) and a fan (8) with adjustable capacity, placed in a common structure (9), whereby the fan (8) is mounted tightly with its suction side to the outlet baffle of this structure, preferably enabling two- sided replacement of the filters and permanently connected to the housing of the filtration device (3), with dimensions and location in the filtration chamber (2), dividing the space in the filtration chamber (2) into an air inlet section (10), an air outlet section (1 1 ) and a bypass duct (12), so that the space from the inlet air port side (13) between the wall of the filtration device housing (3) and the surface defined by the frontal surface of the air inflow to the filtration unit (4) forms the air inlet section (10) and the space from the outlet air port side (14) between the wall of the filtration device housing (3) and the area defined by the outlet structural surface of the filtration unit (9) forms the air outlet section (1 1 ) with the cross-sectional area of the filtration unit (4) in the plane perpendicular to the direction of air flow through the filtration device (4) and passing through the centre of the structure (9) of the filtration unit (4) being 40% - 90% of the cross-sectional area of the filtration chamber (2) while the remaining space of the filtration chamber is the bypass duct (12), whereas the fan (8) of the filtration unit (4) is controlled by a microcontroller (15), to which a sensor for outlet air pollution concentration (18) is connected, mounted downstream of the outlet port (14) or by the user, using the control panel (16). Filtration device according to claim 1 , characterized in that the filtration unit (4), consists of filters placed in order from the fan side (8); the HEPA fine filter (6), the carbon filter (7) and the pre-filter (5), the filtration device (4) being located in a filtration chamber (2) of the pass-through type, transverse to the direction of air flow in the ventilation system, in the section where the filtration device (1 ) is installed, and in a filtration chamber (2) of the by-pass type, the filtration unit (4) being located parallel to the direction of air flow in the ventilation system, in the section where the filtration device (1 ) is installed. Filtration device according to claim 1 characterized in that the dimension of the filtration unit (4) measured in the direction parallel to the air flow in the ventilation system, in the section where the filtration device (1 ) is installed, is 30% - 80% of the dimension of the filtration chamber (2).

Claims

4. Filtration device according to claim 1 characterized in that the fan (8) of the filtration unit (4) has a nominal capacity of at least 20% more than the capacity of the system in which the filtration device is installed (1 )

5. The filtration device according to claim 1 characterized in that the fan (8) of the filtration unit (4) forces the recirculation air flow in the bypass duct (12) with the opposite sense to that of the air flowing through the filtration unit (4).

6. Filtration device according to claim 1 characterized in that the width of the filters being part the filtration unit (4) and the structure (9) that fixes the filtration device is smaller than the width of the filtration chamber (2), and the filtration unit (4) is located at one of the walls of the filtration chamber (2) or centrally.

7. The filtration device according to claim 1 characterized in that the filtration unit (4), in the filtration chamber (2) of the pass-through type, is placed at any height, preferably not at the axis of the air inlet port (13) and the air outlet (14) port, and the space on the side of the air inlet port (13) between the housing wall (3) of the filtration device (1 ) and the front surface of the filtration unit (4) is the air inlet section (10) while the on the side of the outlet air port (14) between the housing wall (3) of the filtration device (1 ), and the outlet surface of the filtration unit (4) is the air outlet section (1 1 ), while the width of the air inlet section (10) is 10% - 40% of the dimension of the filtration chamber dimension (2), measured in the direction parallel to the air flow in the system, on the section where the filtration device is installed (1 ) and the width of the air outlet section (1 1 ) is 10% - 50% of this dimension.

8. The filtration device according to claim 1 characterized in that the filtration unit (5), in the filtration chamber (1 ) of bypass type, is placed at any height, in the space between the axes of inlet (3) and outlet (4) port, preferably not in the immediate vicinity of air inlet and outlet, whereas the air inlet section (16) represents 15% - 30% of the filtration chamber dimension (2), measured perpendicularly to the air flow in the system on the section where the filtration device is installed (1 ) and the width of the air outlet section (17) represents 5% - 15% of this dimension.

9. Filtration device according to claim 1 is characterized in that the filtration chamber (2) has the shape of a cylinder, in which one base is fitted with an air inlet port to the filtration chamber (13) and the other base with an air outlet port from the filtration chamber (14) while the filtration unit (4) has the shape of a hollow cylinder closed from the side of the air incoming from the system and with the fan (8) of the filtration unit (4) installed on the side of the outlet air port (14), while the side surface of the cylinder constituting the filtration unit (4) is made of layers of filtration material, with the pre-filter material (5) being the outer layer and the fine filter material (6) the inner layer of the filtration unit (4) being the layered side of the cylinder, while the outlet side of the filtration unit (4) is the inner surface of the hollow cylinder while the outer surface of the filtration cylinder is the frontal side of the air inlet of the filtration unit (4) and the space between the front side of the filtration unit (4) and the housing of the filtration device is the air inlet section (10) and the space between the filter cylinder and the outlet port (14) is the air outlet section (11 ).