Air purifier device

Abstract

An air-purifying device comprises a first surface made of non-insulating material, larger than approximately 1 m², configured to extend into an area to be purified, and an electric generator configured to place said first surface at a first potential between approximately 5 kV and approximately 500 kV relative to a reference surface, so as to generate an electric field between said first surface and said reference surface greater than approximately 10 kV / m. Figure 3B

Description

Title of the invention: Air purifying device Technical field of the invention

[0001] The invention relates to an air purifying device and more specifically to a device capable of destroying fine particles present in the ambient air. Such a device is intended to depollute the ambient air of an area to be depolluted, in particular an area located outdoors. State of the art

[0002] The combustion of fuels results in particular in the emission of fine and ultra-fine particles. These particles, whose low average mass keeps them suspended in the ambient air, pose a major public health problem. In particle metrology (or "PM" according to the abbreviation of the Anglo-Saxon expression "Particulate Matter"), a distinction is made, depending on the size of the particles, in particular fine particles "PM 10", "PM2.5" or "PMI", with diameters respectively less than 10 qm, 2.5 pm or 1 pm. Particles with a diameter less than 0.1 pm fall into the classification of "ultrafine particles".

[0003] Air quality monitoring uses highly sophisticated physical methods for detecting fine and ultrafine pollutant particles, involving, for example, the use of quartz microbalances, beta-ray probes, or optical counting methods using laser diffraction sensors.

[0004] For the purification of air in confined environments such as the interior of an inhabited room, certain devices, available commercially, consist of ionizing the fine particles in suspension. In this way, said ionized particles will agglomerate, and the agglomerates, of greater mass, fall to the ground, or cling to the walls of the room by electrostatic effect, where they can be stored and collected.

[0005] Today, outdoor air pollution control mainly consists of limiting the emission of particles at the source, for example by means of devices such as catalytic exhaust pipes for vehicles, filters for collective and industrial boiler rooms or waste incinerators.

[0006] To depollute the outdoor ambient air of fine and ultrafine particles, at least locally, a recent approach consists of vacuuming and filtering the fine and ultrafine particles suspended in the ambient air. The Dutch company Envinity ® has made public the design of ultra-powerful vacuum cleaners containing filters in the form of filter cartridges, generally consisting of one or more layers of porous, fibrous or granular material for filtering the air. The aces Envinity's air purifiers are said to be capable of treating 800,000 m3 of air per hour, and the company claims to filter 95% of PM and 90% of ultrafine particles from the treated air [Ref. 1]. However, this approach is energy intensive, as it involves circulating a large volume of air through a small area. In addition, changing and cleaning filters generates significant material and labor costs.

[0007] To depollute the ambient air outside, the use of photocatalysts is also known, such as titanium dioxide (TiO2). TiO2, when activated by ultraviolet rays emitted by a natural or artificial source, allows oxidation of pollutants (by photocatalysis reaction) which are then converted into oxidation products, CO2 and H2O. Photocatalysis is implemented by means of a coating comprising the photocatalyst, applied to exterior walls, for example in public places or near roads. This process makes it possible to destroy odors or clean surfaces. However, this process is limited since it only acts on particles that naturally settle on the treated surfaces.

[0008] Recently, the applicant has implemented a device for local depollution of ambient air, which uses the surface of the envelope of a captive balloon to capture and transform fine particles into CO2 and H2O [Ref. 2]. The depollution device is based on the potential difference between the envelope of the balloon and the environment, this potential difference making it possible to attract the fine particles onto the envelope where they can be degraded, for example by means of a coating comprising titanium dioxide. However, in practice, the applicant has shown that the effect of the wind on the fine particles often proves to be predominant compared to the electrical attraction, so that the fine particles tend to slide on the balloon in the presence of wind.

[0009] The present application describes an air purifying device, suitable for operating also outdoors and with low energy consumption, but with increased efficiency. Summary of the invention

[0010] In the present description, the term "comprise" means the same as "include", "contain", and is inclusive or open and does not exclude other elements not described or shown. Furthermore, in the present description, the term "approximately" or "substantially" is synonymous with (means the same as) a lower and / or upper margin of 10%, for example 5%, of the respective value.

[0011] According to a first aspect, the present description relates to an air purifying device comprising: - a first surface made of non-insulating material, with a dimension greater than approximately 1 m2, configured to extend into an area to be decontaminated; - an electrical generator configured to place said first surface at a first potential between approximately 5 kV and approximately 500 kV relative to a reference surface, so as to generate an electric field between said first surface and said reference surface greater than or equal to approximately 10 kV / m.

[0012] By non-insulating material is meant a conductive or impeding material, that is to say a material capable of totally or partially transmitting an electrical potential. In the remainder of the description, a non-insulating material will also be referred to as a material of finite electrical impedance. According to one or more exemplary embodiments, such a non-insulating material is a material whose conductivity is at least 10 4 S / cm, for example at least 1 S / cm, for example at least 10 S / cm.

[0013] The non-insulating material may comprise a single material or a combination of different materials. For example, the non-insulating material comprising the first surface may comprise an additive, e.g., aluminum, making said material conductive or of non-zero finite impedance. The first surface may also comprise a multi-layer material.

[0014] The applicant has shown that it is thus possible to trap fine particles present in the ambient air with increased efficiency compared to known devices. An intense electric field, for example of the order of 10 kV / m or higher, is generated between said first surface and the reference surface. The electrically charged particles present in the ambient air will then be subjected to the influence of the electric field. Depending on the polarity of the field and the sign of the electric charge of said particles, said particles will be attracted either by the first surface or by the reference surface, and will be deposited, respectively, on the first surface or the reference surface.

[0015] The applicant has shown that a device according to the first aspect of the present description makes it possible to purify the air without requiring filter cartridges, which presents a certain advantage. Indeed, a device according to the first aspect consumes little energy in comparison with the ultra-powerful vacuum cleaners cited in the state of the art, for example in [Ref. 1], whose energy consumption is significant in order to compensate for the air resistance inherent in the presence of the filter cartridges.

[0016] According to one or more exemplary embodiments, the electric generator is a direct or alternating current generator.

[0017] Said first potential at which the first surface is placed is between approximately 5 kV and approximately 500 kV relative to the reference surface, so as to generate an electric field between the two surfaces greater than or equal to approximately 10 kV / m. According to one or more exemplary embodiments, the first potential is between approximately 10 kV and approximately 500 kV, for example between approximately 30 kV and approximately 100 kV. According to one or more exemplary embodiments, the maximum distance separating the point(s) of said first surface closest to the reference surface is less than or equal to n / 10 meters, when the first potential = n kV. For example, when the first potential is equal to 5 kV, said maximum distance is equal to 0.5 m, so as to generate an electric field between the two surfaces greater than or equal to approximately 10 kV / m.

[0018] The area of ​​the first surface is greater than about 1 m2. According to one or more exemplary embodiments, the area of ​​the first surface is greater than about 5 m2, for example greater than about 10 m2, for example greater than about 20 m2, for example greater than about 100 m2. Such large areas can make it possible to treat a large volume of air and a large quantity of fine particles when the device is deployed to depollute an area. So that the weight of the device and the wind resistance do not become penalizing, and in view of the implementation and the cost of the device, lightweight materials may be preferred for composing the first surface, such as permeable materials, such as thin and perforated sheets, nets, canvases, and combinations thereof.According to one or more exemplary embodiments, the first surface comprises at least one flexible material, for example selected from the group comprising rubber, coated canvas, laminated canvas. According to one or more exemplary embodiments, the at least one flexible material comprises a textile weft, e.g., polyester, covered with a film, e.g., PVC or polyurethane. According to one or more exemplary embodiments, the first surface comprises at least one rigid material, for example a metal, e.g., aluminum, or a metal alloy, e.g., stainless steel. According to one or more exemplary embodiments, the at least one rigid material is in the form of rigid perforated sheets.

[0019] According to one or more exemplary embodiments, said first surface comprises a canvas and / or a net. A canvas within the meaning of the present description is a two-dimensional, meshed network of threads (i.e. arranged in substantially regular patterns), in which the average dimensions of the meshes are less than approximately 1 cm. A net within the meaning of the present description is a two-dimensional network of threads. According to one or more exemplary embodiments, the net is meshed, the average dimensions of the meshes being, for example, greater than or equal to approximately 1 cm. For example, a net may consist of an assembly of knotted ropes and / or a network of metal wires welded together.

[0020] According to one or more exemplary embodiments, the reference surface is the earth. In this way, advantageously, certain charged fine particles can be deposited on the ground and washed away by rain and / or collected.

[0021] According to one or more exemplary embodiments, said reference surface is included in the air purifying device. According to one or more exemplary embodiments, said reference surface has one or more of the aforementioned characteristics with reference to the first surface, for example in terms of composition, dimension, shape. According to one or more exemplary embodiments, the reference surface is a surface made of non-insulating material, configured to extend into said area to be depolluted. Advantageously, the reference surface may be of a dimension greater than approximately 1 m2.

[0022] According to one or more exemplary embodiments, the reference surface is electrically connected to the ground, and thus acquires the same potential as the ground. The reference surface may be electrically connected to the ground by means of an electrically conductive element. For example, when the reference surface is connected to the ground, e.g., by a mast or foot, the mast or foot may be electrically conductive or the electrically conductive element may comprise an electrical cable arranged for example along the mast or foot, on an external or internal surface of the mast or foot. Alternatively, the reference surface may be placed at a potential different from the ground potential and the first potential, so that the electric field between the two surfaces is greater than or equal to approximately 10 kV / m. According to one or more exemplary embodiments, the potentials of the first surface and the reference surface are of opposite sign.Advantageously, such a configuration of the air purifier device makes it possible to obtain a large potential difference between said first surface and said reference surface without placing the potentials of the two surfaces at excessively high values. For example, the first surface can be placed at +50 kV and the reference surface at -50 kV, so that the potential difference is 100 kV.

[0023] According to one or more exemplary embodiments, the reference surface is point-like. In the present description, the term "point-like surface" means a surface formed by one end of at least one wire, or at least one cable, or at least one tip, and combinations thereof. For example, the reference surface may consist of one end of a single wire, or a single cable, or a single tip. According to another example, the reference surface may consist of ends of a plurality of wires. Unlike a net or a canvas, the plurality of wires of such a point-like surface is not assembled, in the sense that the wires of the plurality of wires do not form a two-dimensional network.

[0024] According to one or more exemplary embodiments, said first surface is coated with a coating comprising a photocatalyst capable of transforming at least a portion of the fine particles deposited on said first surface into CO2 and H2O oxidation products. The photocatalyst is thus capable of fragmenting the fine particles deposited on the coating of said first surface, and of converting them into products oxidation of CO2 and H2O according to a mechanism described for example in [Ref. 3]. According to one or more exemplary embodiments, the coating is present on at least a portion of the first surface. According to one or more exemplary embodiments, the photocatalyst is a semiconductor having a wide band gap. According to one or more exemplary embodiments, the photocatalyst is selected from the group including photocatalysts comprising TiO2, ZnO, CeO2, ZrO2, SnO2, CdS, ZnS, and combinations thereof. According to one or more exemplary embodiments, the coating contains titanium dioxide TiO2. Among the various photocatalysts, those including or consisting of TiO2 have a strong oxidizing power, good robustness (in particular good stability over time) and a low cost.

[0025] According to one or more exemplary embodiments, said coating results from the application of a solution containing the photocatalyst to the first surface, as described for example in [Ref. 2], followed by a drying step during which the coating is formed. Such a solution, when applied to the first surface, advantageously makes it possible to stabilize the coating. The solution may contain one or more stabilizers in small quantities, which prevent the coating from crumbling once dry.

[0026] According to one or more exemplary embodiments, the reference surface is also coated with a coating comprising a photocatalyst capable of transforming at least a portion of the fine particles deposited on the reference surface into CO2 and H2O oxidation products.

[0027] According to one or more exemplary embodiments, such a coating is present on at least a portion of the reference surface. The coating of the reference surface and the photocatalyst included in the coating may be identical in every respect or have at least one common characteristic with, respectively, the coating and the photocatalyst described above with reference to the first surface.

[0028] According to one or more exemplary embodiments, said first surface has a shape configured to: - direct ambient air flows; and / or - orient yourself according to the wind; and / or - create one or more depression zones.

[0029] A depression zone within the meaning of the present description is a zone in which there is a near absence of wind or air flow. Such an absence or reduction of wind induced locally by the depression zone has the effect of maximizing the contacts between said first surface and the fine particles present in the ambient air and / or between the reference surface and the fine particles present in the ambient air. Certain shapes make it possible to generate depression zones, such as shapes having at least one central cavity or opening, such as for example torus shapes.

[0030] According to one or more exemplary embodiments, said first surface and / or the reference surface may be flat or have at least one curvature. According to one or more exemplary embodiments, said first surface comprises at least one part whose shape is selected from the group comprising toric shapes. According to one or more exemplary embodiments, said first surface comprises a toric-shaped part. This torus shape may prove very advantageous, for example, when said part of the first surface is formed by an inflatable canvas. The small radius of curvature specific to the torus will then cause even less significant forces during inflation and in terms of wind resistance.In addition, the central cavity of the torus allows the sun's rays to pass through, which can be advantageous, for example when the device is to take the form of street furniture, partially or completely, or to be included in street furniture.

[0031] Additionally, the reference surface may also have one of the aforementioned shapes with reference to the first surface. Alternatively, only the reference surface may have one of the aforementioned shapes, and not the first surface.

[0032] According to one or more exemplary embodiments, the device further comprises at least one tip arranged on said first surface or on said reference surface, such as to locally reinforce the electric field generated between the two surfaces at the end of the tip. Such reinforcement of the electric field occurs at the end of the tip, due to the “tip effect”, for example described in [Ref. 4], and this reinforcement is all the stronger locally as the tip is pointed, that is to say having a smaller radius of curvature. Tips machined for this purpose are available in the industry with radii of curvature of the order of a few micrometers. Another effect resulting directly from the tip effect, called the “corona effect”, and detailed for example in [Ref. 2] and [Ref. 5], is then likely to be produced at the end of the at least one tip.When the electric field is generated between the two surfaces, past a certain voltage threshold, at least one tip will emit ions in cascade by corona discharge and thus contribute to the ionization of the ambient air near the tip.

[0033] The ions thus produced are then likely to interact with neutral fine particles suspended in the ambient air. The neutral fine particles interacting with the ions then in turn acquire an electric charge. Depending on the polarity of the field and the sign of the electric charge of said particles, said particles will then be attracted either by the first surface or by the reference surface, and will be deposited, respectively, on the first surface or the reference surface. Thus, advantageously, the capacity of the air purifier device to trap fine particles extends to neutral fine particles.

[0034] A condition for the corona effect to be able to be observed is that the at least one tip is electrically conductive. According to one or more exemplary embodiments, the at least one tip is formed from the same non-insulating material making up part or all of the first surface. According to one or more exemplary embodiments, the at least one tip included in the reference surface is formed from the same non-insulating material making up part or all of the reference surface.

[0035] According to one or more exemplary embodiments, the device comprises a plurality of said tips, arranged on said first surface and / or said reference surface, such as to locally reinforce the electric field generated between the two surfaces at the end of the tips. According to one or more exemplary embodiments, the total number of ion-emitting tips arranged on the first surface and / or the reference surface is between 2 and 10,000, for example between 10 and 100, for example between 100 and 1000, for example between 200 and 1000. According to one or more exemplary embodiments, the tips of the plurality of tips have different lengths, in order to improve the treatment of fine particles located at different distances from said first surface or from said reference surface.

[0036] According to one or more exemplary embodiments, the device further comprises at least one ionizing device configured to ionize a portion of the fine particles present in the ambient air by corona effect. The ionizing device may be similar or identical to the ionizing device described in [Ref. 2] and comprise a clean electrical generator, e.g., in the form of a solar panel arranged on the air purifying device. Alternatively, the electrical generator configured to place the first surface at said first potential may also serve as an electrical generator for the at least one ionizing device, according to one or more exemplary embodiments.

[0037] According to one or more exemplary embodiments, the total number of ionizing devices included in the air purifier device is between 10 and 50 ionizing devices each containing between 5 and 30 ion-emitting tips. The ionizing devices may for example be distributed regularly over the first surface and / or the reference surface.

[0038] According to one or more exemplary embodiments, the device comprises at least one second surface which can have the same characteristics mentioned above with reference to the first surface, and which can be placed at a second potential by said electrical generator, said second potential being between approximately 5 kV and approximately 500 kV relative to the reference surface, so as to generate an electric field between said second surface and said reference surface greater than or equal to approximately 10 kV / m.

[0039] According to one or more exemplary embodiments, the device further comprises at at least one electrically charged water misting device. According to one or more exemplary embodiments, said at least one electrically charged water misting device comprises at least one misting nozzle emitting water droplets, at least one water supply, and means for electrically charging the water droplets emitted by the at least one misting nozzle. The electrically charged water droplets thus produced will become suspended in the ambient air, and will attract and collect fine particles. The fine particles suspended in the ambient air will then agglomerate or remain trapped inside and / or on the surface of the droplets, and will fall to the ground, where they can be washed and / or collected.According to one or more exemplary embodiments, the means for electrically charging the water droplets may comprise an electrical generator specific to the misting device, for example arranged inside or near the misting device. Alternatively, the electrical generator configured to place the first surface at said first potential may also serve as an electrical generator for the at least one misting device. According to one or more exemplary embodiments, the water included in the water droplets is charged to a potential of at least 1 kV, for example 5 kV. According to one or more exemplary embodiments, the average diameter of the water droplets emitted by the misting device is between 1 micron and 1 mm, for example between 5 and 100 microns, for example between 5 and 10 microns.According to one or more exemplary embodiments, the at least one misting device may be arranged below said first surface and / or below the reference surface, such that the electrically charged water droplets are only emitted towards the ground. When the at least one misting device is a plurality of misting devices, the misting devices may for example be distributed regularly over the first surface and / or the reference surface, so as not to generate conflict with other components of the air purifying device, such as for example the ionizing devices described above.

[0040] According to one or more exemplary embodiments, the device further comprises at least one electric field variator configured to change the polarity of the electric field generated by the electric generator between said first surface and said reference surface. It is thus possible to reverse the sign of the first potential, at which said first surface is placed, which causes an attraction of fine particles charged with the opposite sign by said first surface, said fine particles of the opposite sign then being deposited on said first surface. In the same way, according to one or more exemplary embodiments, the sign of the potential at which the reference surface is placed can also be reversed by means of the electric field variator. According to one or more exemplary embodiments, the field variator electric is configured to effect a change in polarity of the electric field at a predetermined frequency, eg, in cycles of about 0.1 seconds to about 10 seconds.

[0041] According to one or more exemplary embodiments, the device further comprises an airflow control system configured to direct ambient air towards said first surface of the device. The airflow control system may also, or alternatively, direct the ambient air towards said reference surface. According to one or more exemplary embodiments, the airflow control system comprises unrollable or foldable tarpaulins. Such tarpaulins are deployed in the periphery of the device to control ambient air flows, and for example orient the wind direction.

[0042] According to one or more exemplary embodiments, the air flow control system is configured to facilitate the passage of air flow between said first surface and said reference surface. The flow control system comprises, for example, at least one fan or aerator, which sucks and / or pushes air between the first surface and the reference surface. Said air flow control system thus makes it possible in particular to ensure a sufficient flow of air passing between said surfaces even in the event of low or no wind. Cases of zero or very low wind, e.g., less than 1 meter per second, are generally associated with the conditions in which the most severe pollution episodes occur.Said airflow control system may also make it possible to slow down said passage of airflow, for example in the event of strong wind, so that the air passing between the first surface and the reference surface has time to be sufficiently depolluted by the device.

[0043] According to one or more exemplary embodiments, the electrical generator configured to place the first surface at said first potential relative to the reference surface comprises at least one transformer for generating an output voltage from an input voltage. According to one or more exemplary embodiments, the transformer is configured to generate an output voltage of between 1 kV and 1000 kV, for example between 5 kV and 500 kV, between 5 kV and 100 kV, from an input voltage of between 12 V and 300 V, for example, 12, 24 or 230 V. According to one or more exemplary embodiments, the electrical generator configured to place the first surface at said first potential relative to the reference surface comprises an electricity production means. According to one or more exemplary embodiments, the electricity production means produces electricity autonomously.The electricity production means may for example power the air flow control system of the device and / or the at least one ionizing device and / or the at least one electrically charged water misting device. According to one or more exemplary embodiments, the electricity production means makes the device puri. self-sufficient energy air conditioner, which has the advantage of not requiring connection to the existing electricity network and of limiting operating costs. The electricity production means comprises, for example, an element selected from at least one photovoltaic panel, at least one wind turbine, and combinations thereof. The at least one solar panel may be arranged so as to limit the loss of exposure to the sun of said coating comprising a photocatalyst, when the latter coats the first surface and / or the reference surface. In addition, the at least one solar panel may be partially or substantially transparent to visible light and / or UV, for example partially or substantially transparent to blue light and / or UV.

[0044] According to a second aspect, the present description relates to a depollution method for depolluting the ambient air of an area to be depolluted by means of an air purifying device according to the first aspect, the method comprising: - the installation of said first surface below and / or above and / or around the area to be decontaminated; - the generation of an electric field greater than or equal to approximately 10 kV / m by the electric generator between said first surface and the reference surface.

[0045] According to one or more exemplary embodiments, the device is configured to be movable. Thus, all or part of the device can be stored, for example in a hangar, and deployed for decontamination missions. Alternatively, the device can be permanently deployed at a given location, for example in an area to be decontaminated.

[0046] According to a third aspect, the present description relates to an air purifier assembly comprising a plurality of devices according to the first aspect, wherein the devices are connected to each other, for example mechanically.

[0047] According to one or more exemplary embodiments, the depollution method according to the second aspect comprises the connection of a plurality of devices according to the first aspect, e.g., the mechanical connection of a plurality of said devices to each other, in the case where said devices are configured to each be mechanically connected to one or more other devices. Such a connection makes it possible to easily produce a large air purification assembly, such as an anti-pollution barrier deployed around, or along, a large area to be depolluted, such as a factory or a high-traffic area such as a motorway or ring road. For these purposes, it may be advantageous for the devices of the plurality of devices according to the first aspect to be substantially identical or all identical.

[0048] According to one or more exemplary embodiments, the device takes the form of street furniture in whole or in part, or is included in street furniture. street furniture can for example be of the shade and / or shelter type.

[0049] According to one or more exemplary embodiments, the air purifying device according to the first aspect takes the form of a shade structure with a length of between 1 and 20 m, for example between 1 and 10 m, with a width of between 1 and 10 m, for example between 1 and 5 m, and comprising a central supporting mast having a height of between 1 and 10 m.

[0050] According to one or more exemplary embodiments, the air purifying device according to the first aspect or the air purifying assembly according to the third aspect is included in street furniture of the bus shelter or bus shelter type. The bus shelter may offer one or more of the following advantages: the presence of a mechanical support, the possibility of connection to an electrical network, protection against the wind. The volume under the bus shelter is protected from the wind and can effectively benefit from the depollution provided by the device. The air purifying device may for example be installed on the roof of the bus shelter, and comprise, according to one or more exemplary embodiments, an air flow control system as described above, allowing air to be sucked in from the outside, and ventilation of purified air towards the users.

[0051] According to one or more exemplary embodiments, the air purifying device further comprising a misting device, the method further comprises misting electrically charged water droplets by the misting device. Brief description of the figures

[0052] Other advantages and characteristics of the invention will appear on reading the description, illustrated by the following figures:

[0053] [Fig.lA], a diagram illustrating a top view of an exemplary air purifying device according to the present description;

[0054] [Fig. 1B], a diagram illustrating a side view of the same exemplary device as that illustrated in [Fig. 1A], in which the misting device is activated.

[0055] [Fig.2], a diagram illustrating a cross-sectional view of the view illustrated in [Fig.lB].

[0056] [Fig.3A], a diagram illustrating a perspective view of an assembly of other examples of devices according to the present description, forming an anti-pollution barrier.

[0057] [Fig.3B], a diagram illustrating a perspective view of a device configured for be connected to one or more other devices to form the anti-pollution barrier illustrated in [Fig.3A].

[0058] [Fig.3C], a diagram illustrating a longitudinal view of the view illustrated in the [Fig.3B].

[0059] [Fig.4], a diagram illustrating a cross-sectional view of a bus shelter on the roof of which a another example of a device according to the present description is deployed. Detailed description of the invention

[0060] In the figures, the elements are not shown to scale for better visibility.

[0061] A first example of a device according to the present description is illustrated in Figures 1A, 1B and in [Fig.2].

[0062] In this particular example, the device 1 comprises a first surface 2 made of non-insulating material and of a dimension greater than 10 m2, equal to a few tens of m2. The device 1 further comprises a reference surface 4.

[0063] In this example, the first surface 2 comprises a flexible part 22 consisting of an inflatable toroidal-shaped fabric arranged above a substantially flat part 21, for example a rigid disc-shaped part and consisting of a metal net, e.g., stainless steel. The reference surface 4 comprises a metal disc, for example substantially identical to that of the first surface. The two substantially flat discs 21 and 4 are in this example arranged parallel to each other, and parallel to the ground. The two surfaces 2 and 4 are connected to the ground by a central mast or foot 5. The reference surface 4 is arranged below the disc 21 of the first surface 2, at a height of, for example, between 3 m and 5 m above the ground. The height of the disc 21 included in the first surface may be greater, so that the distance between the two discs 21 and 4 is between 1 m and 3 m.Other heights are possible, provided that the condition on the value of the electric field generated between the two surfaces 2 and 4 is respected, in other words, as long as the value of the field is greater than or equal to 10 kV / m.

[0064] In this example, an electric generator 3 - shown in [Fig.2] only - is arranged on the mast 5 between the two surfaces 2 and 4. In other embodiments, the generator can also be arranged elsewhere, such as at ground level or inside the mast 5 when the latter is hollow. The generator is configured to place the first surface 2 at a first potential of between approximately 5 kV and approximately 500 kV relative to the reference surface 4, such that the electric field generated between the first surface 2 and the reference surface 4 is at least equal to approximately 10 kV / m.

[0065] For example, the first potential is equal to approximately 10 kV. The reference surface may be placed at the same potential as the ground. Electrical cables (not shown) are used to electrically connect the disk of the reference surface 4 to the ground in order to place it at the same potential as the ground. In other examples, the mast 5 may be electrically conductive over the entire length between the ground and the reference surface 4. On the other hand, the mast 5 is advantageously insulating over at least part of the length connecting the two surfaces 2 and 4, in order to maintain the desired potential difference between the two surfaces.

[0066] In this example, the generator 3 also comprises an electrical cable connected (not shown) to the first surface 2.

[0067] As illustrated in [Fig.2], both the first surface 2 and the reference surface 4 are coated with a coating 6 comprising a photocatalyst capable of transforming at least a portion of the fine particles deposited on said surfaces into oxidation products CO2 and H2O. The coating covering the first surface is for example identical to the coating covering the reference surface in terms of composition, and covers the entirety of both surfaces. The photocatalyst comprises for example titanium dioxide or TiO2.

[0068] In this example of a device, as illustrated in the Figures, the first surface and the reference surface 4 both comprise a plurality of tips 7, such as to locally reinforce the electric field generated between the two surfaces, at the end of each tip 7. In this example, the tips 7 are distributed regularly on each of the two discs (21, 4), and face each other, i.e., for each disc, the tips 7 are arranged on the face of the disc facing the other disc. The tips 7 are for example made of the same metal as the discs (21, 4). Other devices are also conceivable according to the present description, which do not comprise tips 7. Similarly, alternative devices may further comprise one or more ionizing devices, such as those described in [Ref. 2], capable of ionizing a portion of the fine particles present in the ambient air by corona effect.

[0069] In this example, the device 1 further comprises a device for misting electrically charged water. The latter comprises a plurality of misting nozzles 8 distributed, for example, regularly at 50 cm intervals around the circumference of the disc 4, on the ground side. The nozzles 8 emit electrically charged water droplets 9. In this example, the misting device also comprises a water supply via the mast 5, and means for electrically charging the water droplets 9 emitted by the nozzles 8.

[0070] In this example, the device 1 advantageously takes the form of urban furniture of the umbrella and / or shelter type, and is not configured to be movable, but to remain permanently in an urban area in order to purify the air.

[0071] When the device is used to depollute an area and the electric field is generated by the generator 3, the electrically charged particles present in the ambient air will then be subjected to the influence of the electric field. Depending on the polarity of the field and the sign of the electric charge of said particles, said particles will be attracted either by the first surface or by the reference surface, and deposit, respectively, on the first surface 2 or the reference surface 4. Trapped in this way due to the influence of the electric field, the particles will be successively transformed by the photocatalyst present in the coating 6, into harmless oxidation products such as CO2 and H2O.

[0072] In this example, the electric field will be reinforced at the end of the tips 7, which advantageously leads to ionizing the neutral fine particles. In addition, the torus of the first surface 4 advantageously creates a depression zone which will make it possible to reduce the effect of the wind, the latter having in fact a tendency to make the fine particles slide on the fabric by preventing them from being deposited there.

[0073] Thanks to the combined arrangement of a suitable coating on the two surfaces 2 and 4 and ionizing tips 7, it is thus possible to benefit from the large surface of the device 1 to ensure effective depollution of the ambient air. An air flow control system (not shown) configured to direct the ambient air towards, for example, said first surface 2 of the device can advantageously be integrated into the device. Such a control system comprises, for example, a series of unrolled tarpaulins so as to direct the ambient air flows.

[0074] Furthermore, this model 1 has the possibility of combining the misting mode as detailed above, which may prove advantageous to use at the appropriate time, for example before recess, when the purification device is installed in a schoolyard. Alternatively, during a heatwave, the misting mode can be activated to refresh passers-by.

[0075] [Fig.3A] illustrates an air purifier assembly comprising a plurality of air purifier devices 100 according to another exemplary embodiment of the present description. The devices 100 are for example, but not necessarily, substantially identical.

[0076] In this particular example, the assembly is configured to form an anti-pollution barrier, for example of a dimension greater than approximately 40 m in length. Such a barrier is illustrated in [Fig.3A] and comprises an assembly of a plurality of devices 100 connected together mechanically. The barrier is for example deployed along a motorway axis (not shown) and thus protects the place where pedestrians circulate from pollution.

[0077] The device 100 is shown in more detail in Figures 3B and 3C.

[0078] Each air purifying device 100 comprises a first surface 102 of non-insulating material and a reference surface 104. The device 100 also comprises an electrical generator (not shown in the figure) configured to place the first surface at a potential of between approximately 5 kV and approximately 500 kV relative to the reference surface, so as to generate an electric field between the first surface and the reference surface greater than or equal to approximately 10 kV / m.

[0079] In this example, the device 100 forms a shade comprising a central supporting mast 105 with a height of, for example, between 1 and 10 m, eg, a height of approximately 2 m. Furthermore, the first surface 102 has a substantially rectangular shape whose dimensions are, for example, between 1 and 5 m in width, and 1 and 10 m in length, eg, a width of 3 meters and a length of 5 meters. Thus, an assembly of 8 devices 5 meters long makes it possible to produce an anti-pollution barrier 40 meters long. The shade is, for example, slightly flared on the side facing the motorway, that is to say that the distance separating the ends of the two surfaces in a direction parallel to the mast 105 is greater on the motorway side than on the square / pedestrian side, for example by approximately 100 cm. In this way, the shade takes the form of a converging nozzle, and the polluted air 200 coming from the highway is channeled even more towards the device.

[0080] The polluted air 200 coming from the motorway circulates between the first surface 102 and the reference surface 104 and leaves the device 100 on the square / pedestrian side as purified air 201. In this example, the device 100 comprises a system 101 for controlling the air flow passing through the device, for example a fan. The fan 101 sucks and / or pushes air between the first surface 102 and the reference surface 104. Advantageously, the fan 101 makes it possible to ensure a sufficient air flow even in the event of low or no wind. In the event of strong wind, the fan 101 also makes it possible to slow down the speed at which the air passes between said surfaces 102 and 104, so that said air has time to be sufficiently depolluted by the device.

[0081] In this example, the first surface 102 and the reference surface 104 are both substantially planar, thus providing low resistance to wind and air flowing between said surfaces of the device 100, which allows the fan 101 to consume relatively little energy.

[0082] In this example, the electrical generator configured to place the first surface 102 at said first potential relative to the reference surface 104 comprises an electricity production means, which in the example device 100 illustrated in Figures 3A to 3C produces electricity autonomously, namely photovoltaic panels 110. In this example, the photovoltaic panels 110 supply the fan 101 with electric current. The photovoltaic panels 110 thus make the device 100 self-sufficient in energy, which has the advantage of not requiring connection to the existing electrical network and of limiting the operating costs of the device.

[0083] Furthermore, in this example, the device 100 comprises a protective mesh 120 protecting the area between the first surface 102 and the reference surface 104. Advantageously, the mesh 120 makes the device less vulnerable, for example to birds or malicious people.

[0084] A third example of an air purifying device according to the present description is illustrated in [Fig. 4]. [Fig. 4] illustrates a cross-sectional view of street furniture, i.e., a bus shelter 400 comprising on its roof a device 111 according to the present description. In this example, the first surface 112 of the device 111 is positioned parallel to the reference surface 114 and the ground 300, approximately 20 cm above the reference surface 114. Furthermore, a plurality of spikes 117 are arranged on the two surfaces 112 and 114 so as to locally reinforce the electric field generated between the two surfaces 112 and 114, at the end of the spikes 117.

[0085] The bus shelter 400 offers in this example the following advantages: the presence of a mechanical support, the possibility of connection to an electrical network, and protection 401 against the wind. Furthermore, in the example illustrated in [Fig.4], the device 111 comprises an air flow control system, namely a fan 101 in this example, allowing air 200 to be sucked in from outside, and ventilation of purified air 201 towards the users.

[0086] The criteria for choosing the location of an air purifying device according to the first aspect of the present description may include, in a non-limiting manner, for example, the availability of a location with a large surface area, the proximity of the population, which makes air pollution control beneficial, or the availability of an electricity and / or water supply (when the air purifying device further comprises a misting device), for example, the availability of a connection of the device to the electricity network, the water network and the computer network of the city or municipality comprising said location.

[0087] Although described through a certain number of detailed exemplary embodiments, the device includes various variants, modifications and improvements which will be obvious to those skilled in the art, it being understood that these various variants, modifications and improvements are part of the scope of the invention, as defined by the following claims. References

[0088] Ref.l: https: / / envinitygroup.com /

[0089] Ref. 2: Patent issued FR 3075665

[0090] Ref. 3: [Chem. Rev., 2014,114 (19), pp 9919-9986, “Understanding TiO2 Photocatalysis: Mechanisms and Materials”].

[0091] Ref. 4: https: / / fr.wikipedia.org / wiki / Effet_de_pointe

[0092] Ref. 5: https: / / fr.wikipedia.org / wiki / Effet_corona

Claims

Claims

1. An air purifying device comprising: - a first surface made of non-insulating material, with a dimension greater than approximately 1 m2, configured to extend into an area to be depolluted; - an electrical generator configured to place said first surface at a first potential of between approximately 5 kV and approximately 500 kV relative to a reference surface, so as to generate an electric field between said first surface and said reference surface greater than or equal to approximately 10 kV / m; and further comprising: - an air flow control system configured to facilitate the passage of air flow between said first surface and said reference surface and comprising at least one fan which sucks and / or pushes air between said first surface and said reference surface.

2. A device according to claim 1, wherein said first surface comprises a canvas and / or a net.

3. A device according to any preceding claim, wherein the reference surface is the ground.

4. A device according to claim 1 or claim 2, wherein the device comprises said reference surface, said reference surface being a surface of non-insulating material, configured to extend into said area to be decontaminated.

5. A device according to claim 4, wherein the reference surface is a surface electrically connected to ground.

6. Device according to any one of the preceding claims, wherein said first surface and / or said reference surface is coated with a coating comprising a photocatalyst capable of transforming at least a portion of the fine particles deposited, respectively, on said first surface or said reference surface into CO2 and H2O oxidation products.

7. Device according to any one of the preceding claims, further comprising a plurality of tips arranged on said first surface and / or on said reference surface, such as to locally reinforce the electric field generated between the two surfaces, at the end of the tips.

8. A device according to any preceding claim, comprising at least one ionizing device configured to ionize a part of the fine particles present in the ambient air by the corona effect.

9. Device according to any one of the preceding claims, further comprising at least one electrically charged water misting device.

10. A device according to any preceding claim, further comprising at least one electric field variator configured to change the polarity of the electric field generated by the electric generator between said first surface and said reference surface.

11. Device according to any one of the preceding claims, in which the device takes the form, wholly or partially, of urban furniture of the shade and / or shelter type, or is included in urban furniture of the shade and / or shelter type.

12. A device according to claim 11, wherein the device takes the form of a shade structure of between 1 and 10 m in length, between 1 and 5 m in width, and comprising a central supporting mast having a height of between 1 and 10 m.

13. An air purifier assembly comprising a plurality of devices according to any preceding claim, wherein the devices are connected to each other by mechanical connection.

14. Method for depolluting the ambient air of an area to be depolluted by means of a device as defined in any one of claims 1-12, the method comprising: - placing said first surface below and / or above and / or around the area to be depolluted; - generating an electric field greater than or equal to approximately 10 kV / m by the electric generator between said first surface and said reference surface; - sucking and / or pushing an air flow between said first surface and said reference surface by means of the at least one fan.

15. The method of claim 14, further comprising: - misting electrically charged water droplets by an electrically charged water misting device.

Images