Plasma filter device, electrode device, and method for operating a plasma filter device

Abstract

To provide a plasma filter device (1) having at least one electrode device (2).SOLUTION: An electrode device (2) has a first composite electrode (3) configured in a planar manner and a second composite electrode (4) configured in a planar manner. The composite electrodes (3, 4) of the electrode device (2) are arranged coplanar to one another on a main surface plane (13) of the electrode device (2) and are separated from one another by a discharge gap (9). The composite electrodes (3, 4) have electrode sheets (5, 6) respectively, and have dielectric coatings (7, 8) respectively on at least one boundary surface with the discharge gap (9) of the respective electrode sheets (5, 6). A plasma filter device (1) has a power source (22), and the power source is configured to provide an AC voltage to the electrode device (2). The AC voltage is parameterized to induce a formation of a plasma (11) through a dielectric barrier discharge in the discharge gap (9).SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a plasma filter device having at least one electrode device, an electrode device and a method for operating a plasma filter device. [Background technology]

[0002] Even before the coronavirus pandemic, preventing the transmission of pathogens through aerosols was a challenge in hospital hygiene. Until now, bacteria and particle reduction had been limited to specific rooms, such as operating rooms, examination rooms, and isolation rooms. However, due to the pandemic, the demand for pathogen-free ventilation through combined ventilation and air conditioning systems has become increasingly important. Currently, various commercially available filter solutions, combining plasma, UVC radiation, and additional filters, such as HEPA, are offered for conditioning indoor air in enclosed environments such as buildings, automobiles, aircraft, or trains.

[0003] Due to the highly specific requirements for various applications, the solutions available on the market have drawbacks in terms of the flow mechanism of the gas to be filtered or the size of the filtration device. Furthermore, existing solutions can result in high costs due to the filter units provided and due to the regular replacement and disposal of additional filter elements such as HEPA.

[0004] Therefore, effective and efficient adoption and optimization of currently used filter solutions is limited or impossible.

[0005] Known filter devices from the prior art include, for example, mechanical air filters.

[0006] In fact, mechanical filtration of indoor air is very important to keep it clean and sterile, especially in hospitals and other medical facilities. Modern building air cleaning systems use multi-stage filter devices, consisting of pre-filtration, e.g., of dust particles, and high-efficiency filtration, e.g., for microbial contamination. For surgical procedures, these are combined with mechanical devices to create a laminar (turbulence-free) air flow over the patient. Modern operating room equipment (so-called ventilation and air-conditioning systems) introduces fresh air, which must be heated to a normal room temperature (20-22°C) using a lot of energy in winter.

[0007] With a separation rate of at least 99.95%, high-efficiency HEPA filters can effectively suppress particulate contamination as well as bacteria and viruses. However, the SARS-CoV-2 virus also exists in mesoscale aerosols that can pass through these filters. These fine aerosols, in particular, have a long residence time in the air.

[0008] For buildings, the 2021 pandemic saw the proposal to improve ventilation with HEPA filters, which would have led to the expansion of large and expensive systems, which would also significantly worsen the energy balance by compensating for pressure losses and increase noise emissions through increased flow velocities.

[0009] For aircraft, central filtration systems with HEPA units are used to purify the air. The size, weight, and energy consumption of this ventilation system affect the overall performance of the aircraft. Car / bus / train vehicles consist of only central air-conditioned rooms with simple filtration technology that is not suitable to allow for air decontamination.

[0010] Not only mechanical filter devices are in use, but also filter devices that enable UVC or plasma-based methods for air decontamination.

[0011] Current ozone generators, ionizers, or plasma systems consist of a comprehensive interaction chamber. For example, to decontaminate indoor air with UV lamps, tunnel-like systems with low to moderate airflow are used. This allows high decontamination rates. Therefore, what all these filter devices have in common is that they are used as central units with an extended cubic shape or a longitudinal spatial design.

[0012] Mobile surface decontamination devices or fixed UVC lamps have been used in recent years for surface decontamination. A drawback of these commercially available solutions lies in their implementation in, for example, medical imaging equipment, subject to requirements regarding installation space, EMV or air flow conditions.

[0013] Solutions on the market are based on electromagnetic discharges and the relatively slow disinfecting effect of radicals.

[0014] Therefore, a more advanced solution is the combination of UVC-based methods with generated plasma. In UVC-based methods, the dose required for effective and efficient decontamination of air depends heavily on the wavelength of the UVC source used and the residence time of the room air in the corresponding filter unit. Experience from surface decontamination with UVC radiation has shown that long exposure times, related to distance and dose, are necessary to ensure a high degree of pathogen removal.

[0015] With regard to medical equipment, a CT device with an automatic cleaning function is known from US Pat. No. 5,629,499, which discloses a sterilization unit for a CT device based on UVC, plasma or ozone. [Prior art documents] [Patent documents]

[0016] [Patent Document 1] Chinese Utility Model Patent No. CN203524686 Summary of the Invention [Problem to be solved by the invention]

[0017] The object of the present invention is to provide a filter device which allows for more efficient decontamination of the air. [Means for solving the problem]

[0018] This problem is solved by the subject matter of the respective independent claims. Advantageous developments and preferred forms of embodiment are the subject matter of the dependent claims.

[0019] A first aspect of the present invention relates to a plasma filter device having at least one electrode device. The plasma filter device includes a filter device for filtering gas, in which plasma is generated for filtering the gas, e.g., air. The generated plasma emits UV rays, which inactivate aerosols or bacteria found in the gas, or inactivate particles.

[0020] The electrode device may include a first composite electrode formed in a plane and a second composite electrode formed in a plane. The composite electrodes may, for example, include uniform, symmetrical elements, which may be arranged within an asymmetric electromagnetic potential contour. In other words, the electrode device includes a first composite electrode and a second composite electrode. The composite electrodes of the electrode device may be configured as planar elements. The composite electrodes of the electrode device are arranged flush with one another within a main plane of the electrode device and spatially separated from one another by a discharge gap. That is, the composite electrodes of the electrode device are located within the main plane of the electrode device. A discharge gap is located between the composite electrodes of the electrode device. The discharge gap is a gap formed by the composite electrodes for the passage of the gas to be filtered. Each composite electrode may have a respective electrode sheet having a respective dielectric coating on at least one interface with the discharge gap. In other words, the electrodes may be provided as a composite, which includes a respective electrode sheet and a respective dielectric coating located on the respective electrode sheet. The dielectric coating is applied to the electrode sheet at least at the interface of each composite electrode adjacent to the discharge gap.

[0021] The plasma filter device has a voltage source configured to supply an AC voltage to the electrode device, the AC voltage being parameterized to induce plasma formation in the discharge gap by dielectric barrier discharge. In other words, the plasma filter device has a voltage source configured to supply an AC voltage to the electrode device to induce plasma formation in the discharge gap.

[0022] The plasma filter device is configured to guide the gas through the discharge gap along a main flow direction that is aligned parallel to a normal to the main plane of the electrode device, i.e., the plasma filter device has flow-guiding members, e.g., tubular members, that influence or are defined such that the main flow direction of the gas is guided through the discharge gap parallel to the normal to the main plane.

[0023] The main flow direction in this case runs parallel to the normal to the main plane of the electrode arrangement, i.e., perpendicular to the electrode arrangement. Thus, the gas flows through the discharge gap perpendicular to the electrode arrangement. Due to the plasma formed in the discharge gap by the dielectric discharge, decontamination of the gas takes place in the area of ​​the discharge gap. Decontamination can be achieved by UVC radiation emitted by the plasma and / or by ozone formed in the discharge gap when the gas is air.

[0024] The advantage of this invention is that the discharge gap provides a particle trap where particles reside longer than the gas molecules themselves. Because particles remain in the discharge gap area for a longer period of time, they are exposed to plasma effects such as radicals and UVC radiation for a longer period of time, thereby increasing the probability of particle inactivation. For example, if the UVC power is 100 W / m² and the particle residence time is only 1 second, the dose will be 100 J / m². Coronaviruses are already completely inactivated by 90% at just 37 J / m².

[0025] The present invention also has another embodiment that provides further advantages. In one embodiment of the present invention, each of the composite electrodes has a comb-shaped structure with electrode fingers. In other words, the composite electrode includes a comb-shaped structure of electrode fingers. The comb-shaped structure may be an array of electrode fingers aligned parallel to each other, spaced a predetermined distance apart and arranged adjacent to each other. The comb-shaped structures of the composite electrodes of the electrode device are arranged to engage with and separate each other by a discharge gap. That is, the comb-shaped structures of the composite electrodes of the electrode device are arranged relative to each other so that the electrode fingers of one composite electrode are located between the electrode fingers of the other composite electrode. In this case, the distance between the electrode fingers of the comb-shaped structures of each composite electrode is arranged greater than the width of the electrode fingers of the other electrode. The electrode fingers of the composite electrodes do not contact each other but are spatially separated from each other by a discharge gap. The electrode sheets of the comb-shaped structure can be made of a metallic or generally highly conductive material. Due to the mutually engaging comb-shaped structures of the composite electrodes of the electrode device, the discharge gap within the electrode device has a serpentine shape. The advantages this offers are, on the one hand, that the serpentine shape of the discharge gap is superior to other shapes in terms of particle trapping, and, on the other hand, that an optimal asymmetric electromagnetic potential contour with a completely linearly polarized electric field is created.

[0026] In one embodiment of the present invention, the electrode sheets of each composite electrode comprise aluminum and / or aluminum alloy, i.e. the material of the electrode sheets is aluminum or an aluminum alloy.

[0027] In a further embodiment of the present invention, the electrode sheet of each composite electrode comprises a non-corrosive steel, preferably a stainless steel, i.e., a material comprising a non-corrosive stainless steel, such as a chromium-containing steel.

[0028] In another embodiment of the present invention, the dielectric coating of each composite electrode comprises one or more polymers, in other words, the dielectric coating comprises one or more polymers, particularly electrically insulating polymeric materials.

[0029] In another embodiment of the present invention, the dielectric coating of each composite electrode comprises one or more fluoroplastics. In other words, the dielectric coating comprises a material that includes a fluoropolymer. The advantage of this is that the dielectric coating comprises a polymer with a relatively high insulating capacity.

[0030] In another embodiment of the present invention, the dielectric coating of each composite electrode comprises polyvinylidene fluoride (PVDF), i.e., the dielectric coating comprises a material that includes polyvinylidene fluoride (PVDF).

[0031] In another embodiment of the present invention, the dielectric coating of each composite electrode comprises polytetrafluoroethylene (PTFE). In other words, the dielectric coating comprises a material that includes polytetrafluoroethylene (PTFE). The use of polytetrafluoroethylene (PTFE) has the advantage of having relatively high corrosion resistance and temperature resistance.

[0032] In another embodiment of the present invention, the dielectric coating of each composite electrode comprises graphite fluoride, or in other words, the dielectric coating comprises a material that includes graphite fluoride.

[0033] Another embodiment of the present invention is to include one or more ceramics. In other words, the dielectric coating includes a material containing one or more ceramics. In particular, ceramics from the group of electroceramics can be included. Possible ceramics include, for example, titanates, particularly barium titanate ceramics and / or lead zirconate titanate ceramics. The use of ceramics has the advantage that they are materials with relatively high fracture strength.

[0034] In another embodiment of the present invention, the dielectric coating of each composite electrode comprises barium titanate. In other words, the dielectric coating comprises a material that includes barium titanate. The use of barium titanate has the advantage that it is a material with a relatively high dielectric constant.

[0035] In another embodiment of the present invention, the dielectric coating of each composite electrode comprises kaolinite. In other words, the dielectric coating comprises a material that includes kaolinite. The use of kaolinite has the advantage that it is a material with a relatively high dielectric constant.

[0036] In one embodiment of the present invention, the dielectric coating of each composite electrode comprises a blend containing predetermined proportions of kaolinite, aluminum oxide, titanium oxide, chromium oxide, barium titanate, and / or other ceramic powders. In other words, the dielectric coating of each composite electrode comprises a specific proportion of kaolinite, aluminum oxide, titanium oxide, chromium oxide, or barium titanate, or other ceramic powders. In other words, the dielectric coating comprises a material that includes a ceramic blend. The use of a blend has the advantage that the materials have specific, optimally matched dielectric constants. A blend may also be referred to as a mixture.

[0037] Another embodiment of the present invention is a plasma filter device having at least two electrode devices. That is, the plasma filter device has two or more electrode devices. The plasma filter device has a holder device as a housing, which is configured to arrange the at least two electrode devices in a predetermined electrode arrangement, where the at least two electrode devices in the predetermined electrode arrangement are aligned parallel to each other and arranged one behind the other along the main flow direction. Adjacent electrode devices in the predetermined electrode arrangement are arranged in pairs at a predetermined distance from each other. In other words, the plasma filter device is configured to provide an arrangement of the electrode devices in a predetermined electrode arrangement using the holder device. The electrode devices are arranged parallel to each other by the holder device. Furthermore, the electrode devices can be arranged one behind the other along the main flow direction. The electrode devices can be shifted relative to each other, for example, along the main flow direction. The holder device is configured to arrange the at least two electrode devices in an electrode arrangement where the at least two electrode devices are arranged in pairs at a predetermined distance from each other. The holder device can have, for example, a separation frame, which is arranged between two of the electrode devices and can predetermine the predetermined spacing between the electrode devices. The advantage offered by this embodiment is that the gas can be directed through multiple electrode devices arranged one behind the other along the main flow direction, thereby allowing multiple deactivation steps to be carried out during the gas flow through the filter device.

[0038] Another embodiment of the present invention is that adjacent electrode devices of at least two electrode devices are rotated by 90° relative to each other in the main flow direction. That is, the electrode devices arranged one behind the other are rotated by 90° relative to each other. For example, the electrode devices can be arranged to have the same pattern as the pattern predetermined by the discharge gap in the main plane, and this pattern can be rotated by 90° between adjacent electrode devices. This allows the pattern of the electrode devices along the main flow direction to form a cross structure. An advantage provided by this embodiment is that the residence time of aerosol, preferably suspended aerosol, can be increased at adjacent electrode devices.

[0039] In another embodiment of the present invention, the plasma filter device includes at least one dust filter. The at least one dust filter is positioned in front of the electrode device in the main flow direction. In other words, the plasma filter device is configured to guide the gas through the dust filter along the main flow direction before the gas is guided through the electrode device. The dust filter may, for example, include a mechanical dust filter having a mesh through which the gas is passed for filtering. It may also be an electrostatic dust filter. An advantage of this embodiment is that particles, dirt, or larger particles are trapped by the dust filter, which can delay or prevent clogging of the electrode device by dust or impurities.

[0040] In another embodiment of the present invention, the plasma filter device includes at least one activated carbon filter. The activated carbon filter is disposed after the electrode device in the main flow direction. In other words, the plasma filter device is configured so that the gas flows through the electrode device in the main flow direction and then passes through the activated carbon filter. This embodiment provides an advantage in that certain undesirable short-lived radicals (transient charge-carrying ions / molecules / atoms specific to plasma) that may be formed in the plasma can be catalytically removed by neutral recombination using the activated carbon filter. For example, ozone can be formed due to the formation of plasma in the discharge gap. However, in certain situations, ozone emissions are undesirable. By providing an activated carbon filter, the generated ozone can be recombined, thereby catalytically reducing the ozone content of the gas exiting the plasma filter device to a level that is acceptable for purified air.

[0041] A second subject of the invention relates to an electrode arrangement for a plasma filter device, the electrode arrangement being arranged in a plasma filter device for gas decontamination.

[0042] The electrode device includes a first composite electrode formed in a plane and a second composite electrode formed in a plane. In other words, the electrode device includes a first composite electrode and a second composite electrode. The composite electrodes of the electrode device can be configured as planar members. The composite electrodes of the electrode device are arranged coplanar with each other in a main plane of the electrode device and spatially separated from each other by a discharge gap. In other words, the composite electrodes of the electrode device are located within the main plane of the electrode device. A discharge gap is provided between the composite electrodes of the electrode device. The discharge gap is a gap formed by the composite electrodes for the flow of the gas to be filtered. Each composite electrode has a respective electrode sheet, which has a respective dielectric coating on at least one interface of the electrode sheet with the discharge gap. In other words, the electrodes are provided as a composite including a respective electrode sheet and a dielectric coating on the respective electrode sheet. A dielectric coating is applied to at least one of the composite electrodes at an interface adjacent to the discharge gap on the electrode sheet.

[0043] Yet another embodiment of the electrode device of the present invention is in accordance with the various embodiments of the plasma filter device of the present invention.

[0044] A third aspect of the present invention relates to a method of operating a plasma filter device.

[0045] The plasma filter device has at least one electrode device, which includes a first composite electrode formed in a planar shape and a second composite electrode formed in a planar shape. In other words, the electrode device includes a first composite electrode and a second composite electrode. The composite electrodes of the electrode device can be configured as planar elements. The composite electrodes of the electrode device are arranged coplanar with each other within a main plane of the electrode device and are spatially separated from each other by a discharge gap. In other words, the composite electrodes of the electrode device are located within the main plane of the electrode device. A discharge gap is provided between the composite electrodes of the electrode device. This discharge gap is a gap formed by the composite electrodes through which the gas to be filtered flows. Each composite electrode has a respective electrode sheet, which has a dielectric coating on at least one interface with the discharge gap of each electrode sheet. In other words, the electrodes are configured as a composite including a respective electrode sheet and a dielectric coating on the respective electrode sheet. The dielectric coating is applied to the electrode sheet at least on the interface of each composite electrode adjacent to the discharge gap.

[0046] In this method, the voltage source of the plasma filter device preferably provides an AC voltage in the increased AC voltage range (100-1000 Hz) or lower high-frequency range (kilohertz), and / or high and highest frequency range (1 GHz-100 GHz) to the electrode device, whereby plasma is ignited and formed in the discharge gap based on a dielectric barrier discharge. The plasma filter device guides the gas through the discharge gap along a main flow direction aligned parallel to the normal to the main plane of the electrode device. The plasma decontaminates the gas, e.g., killing bacteria.

[0047] Yet another aspect of the method embodiment of the present invention is in accordance with various embodiments of the plasma filter device and electrode device of the present invention.

[0048] Further features of the present invention are apparent from the claims, the drawings, and the description of the drawings. Features and combinations of features described herein, as well as features and combinations thereof described below in the description of the drawings, may be included in other combinations of the present invention, not just the combinations explicitly stated. Specific embodiments and combinations of features of the present invention may include those that do not have all the features of the claims originally described. Furthermore, embodiments and combinations of features of the present invention may include inventions that go beyond or deviate from the combinations of features described with reference to the claims. [Brief explanation of the drawings]

[0049] The present invention will be explained in more detail below using specific exemplary embodiments and related schematic drawings, in which identical or functionally identical components are given the same reference numerals, and the description of identical or functionally identical components is not necessarily repeated for the various figures.

[0050] [Figure 1] 1 is a schematic diagram of an electrode arrangement of a plasma filter device. [Figure 2] FIG. 1 is a schematic diagram of an electrode device. [Figure 3] FIG. 1 is a schematic diagram showing an electric electrode device. [Figure 4] FIG. 1 is a schematic diagram of a plasma filter device. [Figure 5] FIG. 1 is a schematic diagram of a plasma filter device. [Figure 6] FIG. 1 is a schematic diagram of a simulation of air flow rate through a plasma filter device. [Figure 7] FIG. 1 is a schematic diagram of aerosol transmission through an electrode device. [Figure 8] FIG. 1 is a schematic diagram of aerosol transmission through a two electrode device. [Figure 9] 1 is a schematic diagram of a possible arrangement of an electrode device. DETAILED DESCRIPTION OF THE INVENTION

[0051] FIG. 1 shows a schematic diagram of an electrode arrangement for a plasma filter device.

[0052] The electrode device 2 of the plasma filter device 1 can include a first composite electrode 3 and a second composite electrode 4. The first composite electrode 3 and the second composite electrode 4 can be planar and located within the main plane 13 of the electrode device 2. The first composite electrode 3 and the second composite electrode 4 can be arranged, for example, flush with each other. The composite electrodes 3 and 4 can be made from a single base plate, which can be separated into a first electrode sheet 5 and a second electrode sheet 6 by providing a discharge gap 9 in the base plate. In this case, the first electrode sheet 5 and the second electrode sheet 6 can be separated from each other by the discharge gap 9. The two composite electrodes 3 and 4 can include electrode sheets 5 and 6, respectively, which can be coated with respective dielectric coatings 7 and 8, thereby forming each electrode into a composite. The electrode sheets 5 and 6 of the composite electrodes 3 and 4 can be made of, for example, aluminum, an aluminum alloy, and / or stainless steel. A dielectric coating 7, 8 of each composite electrode 3, 4 may be applied to each electrode sheet 5, 6 at least on the interface between the composite electrode 3, 4 and the discharge gap 9. The role of the dielectric coating 7, 8 is to enable a dielectric discharge in the discharge gap 9 when a suitably parameterized AC voltage is applied to the electrode device 2. The dielectric coatings 7, 8 may comprise one or more polymers as their material. The polymer may be, for example, a fluoroplastic, in particular polyvinylidene difluoride and / or polytetrafluoroethylene. At least one polymer may be mixed with graphite fluoride. The dielectric coatings 7, 8 may also comprise one or more ceramics, in particular barium titanate, as their material.

[0053] Figure 2 shows a schematic diagram of the electrode apparatus.

[0054] FIG. 2 shows the comb-shaped structure of the composite electrodes 3, 4 of the electrode device 2. The first composite electrode 3 of the electrode device 2 can have a comb-shaped structure with electrode fingers that can be arranged parallel to and spaced apart from each other. Correspondingly, the second composite electrode 4 of the electrode device 2 can also have a comb-shaped structure with electrode fingers that can engage in the spaces between the composite electrodes 3, 4. The electrode fingers of each composite electrode 3, 4 can be spaced apart from each other by a discharge gap 9. The surfaces of the electrode sheets 5, 6 can have dielectric coatings 7, 8 at least in the region of the discharge gap 9. The comb-shaped structure can also have a dielectric gap 10 made of a dielectric material that can be placed on the electrode sheets 5, 6 along the centerline of each electrode finger.

[0055] FIG. 3 shows a schematic diagram of the electrical electrode device in operation.

[0056] The figure shows two electrode devices 2, which can be arranged one behind the other relative to the main flow direction 12 of the gas passing through the plasma filter device 1. The plasma filter device 1 can be configured to transport the gas to be decontaminated along the main flow direction 12 via the first and second electrode devices 2, which can be aligned parallel to the normal to the main plane 13 of the electrode devices 2. The figure shows the velocity distribution in m / s of particles present in the flowing gas. Due to the perpendicular alignment of the main flow direction 12 relative to the electrode devices 2, the gas is guided through the discharge gap 9 of the electrode devices 2. An AC voltage can be applied to the electrode devices 2 by a voltage source 22 (not shown), which can lead to the formation of plasma 11 in the discharge gap 9 by a dielectric discharge. The plasma 11 can emit ultraviolet light that inactivates aerosols in the gas. Inactivation can involve inducing specific chemical reactions in the aerosols, which can, for example, kill bacteria. The electrode devices 2 can be arranged in a predetermined electrode configuration by a holder device 20 and can be separated from each other by a distance 15. The velocity mapping shows that the velocity is lowest around the two electrode devices 2. This is because the serpentine shape of the discharge gap 9 shown in Figure 2 causes the discharge gap 9 to act as a particle trap, causing gas particles to remain in each discharge gap 9 for a long time. Since the particles remain in the discharge gap 9 for a long time, they are exposed to the plasma 11 and therefore to ultraviolet light for a long time.

[0057] FIG. 4 shows a schematic diagram of a plasma filter device.

[0058] The plasma filter device 1 may include a dust filter 16 positioned before the electrode device 2 relative to the main flow direction 12. The dust filter 16 may be provided to filter dust particles or larger aerosols from the gas passing through the plasma filter device 1 before passing through the electrode device 2 to prevent or slow down clogging and / or contamination of the electrode device 2. The first electrode device 2 may be positioned behind the dust filter 16. The electrode device 2 may have the aforementioned serpentine structure, with the electrode fingers aligned along the x direction. Another electrode device 2 may be positioned behind the first electrode device 2, spaced a predetermined distance 15 from the first electrode device 2 by a separation frame 17. The second electrode device 2 may be rotated 90° from a reference line in the z direction. In this alignment, the electrode fingers may be aligned parallel to the y direction, for example. By rotating the subsequent electrode device 2 relative to the first electrode device 2, the residence time of particles in the discharge gap 9 of the plasma filter device 1 may be increased compared to a plasma filter device 1 in which the electrode devices 2 are not rotated relative to each other. An activated carbon filter 18 through which the gas flows can be arranged after the second electrode device 2. The activated carbon filter 18 is provided to filter ozone molecules that may be formed in the plasma 11 from the gas.

[0059] FIG. 5 shows a schematic diagram of a filter device.

[0060] The plasma filter device 1 can have a holder device 20 that can be provided to hold the electrode device 2, the dust filter 16, and the activated carbon filter 18 in place. A power supply point 19 can be provided on the holder device, which can supply the electrode device 2 with an AC voltage from a voltage source 22. To achieve gas flow along the main flow direction 12, one or two tubes 21 or general guide elements can be arranged on the plasma filter device 1, which can be arranged via flanges on the holder device 20.

[0061] FIG. 6 shows a schematic diagram of a simulation of air flow rate through a plasma filter device.

[0062] Shown is a simulation of the air flow rate through this plasma filter unit in m / sec.

[0063] FIG. 7 shows a schematic diagram of aerosol transmission through an electrode device.

[0064] Figure 7 shows a schematic diagram of the transmission of a 0.3 μm aerosol through the electrode device 2 in 600 seconds. Simulations show that the 0.3 μm aerosol has a relatively long residence time in the serpentine discharge gap 9. The figure shows the aerosol velocity in m / s.

[0065] FIG. 8 shows a schematic diagram of aerosol transmission through a two electrode device.

[0066] The figure shows a schematic diagram of the penetration of a 0.3 μm aerosol through two electrode devices in 600 seconds. The velocity of the aerosol (m / s) is shown in the figure. The two electrode devices 2 are arranged one behind the other and rotated 90° relative to each other. It can be seen that the particles have a longer residence time in the plasma filter device 1 with two electrode devices 2 compared to the residence time in the plasma filter device 1 with one electrode device 2. This can be seen by comparing Figures 7 and 8.

[0067] FIG. 9 shows a schematic diagram of various possible configurations of the electrode device 2.

[0068] The electrode arrangement 2 is characterized by its preferred anisotropy direction. Figure 9 shows the possibility of aligning the electrode arrangement 2 so that any influence of the plasma 11 can be completely suppressed. The figure shows the Helmholtz coils 23 of the MRT device with the magnetic field direction B and the orientation of the electrode arrangement 2 with the plasma flow direction I.

[0069] The technical features of the present invention and the advantages it provides are due to the use of a composite electrode 3, 4 having a defined design and arrangement, which will be referred to below as plasma filter device 1.

[0070] The present invention encompasses two central concepts: the first is the generation of a plasma 11 to generate a high photon density in the UVC wavelength range, and the second is the provision of a novel electrode and filter design that enforces a longer residence time of a particular aerosol particle fraction from the laminar gas volumetric flow in the plasma filter device 1.

[0071] The following description is intended to describe in more detail the layout features of the plasma filter device 1 for decontamination of gases and to make two central ideas more precise.

[0072] The first central idea relates to the generation of plasma 11 using a certain electrode design. This central idea lies in the combination of two metal electrode sheets 5, 6, which provides the serpentine structure of the electrode device 2. The two electrode sheets 5, 6 of the electrode device 2 can be manufactured by conventional commercial and low-cost manufacturing methods, such as by punching and / or cutting a blank sheet. In this case, the blank sheet is processed to impart the serpentine shape of the discharge gap 9 to the blank sheet. This discharge gap 9 can separate the blank sheet into the two electrode sheets 5, 6 of the electrode device 2.

[0073] Dielectric coatings 7, 8 made of a dielectric having a dielectric constant ε in the range of 5 to 50 can be applied to the two electrode sheets 5, 6 of the electrode device 2, thereby forming the composite electrodes 3, 4. The two electrode sheets 5, 6 can preferably comprise aluminum, an aluminum alloy, or stainless steel.

[0074] The dielectric of the dielectric coatings 7, 8 can comprise, for example, PVDF, PTFE, and other fluoro-related polarized polymers with a very high percentage of fluorinated graphite CF, which has a bond energy of 489 kJ / mol. The dielectric of the dielectric coatings 7, 8 can also comprise, for example, ceramics such as barium titanate, which has a dielectric constant of 50.

[0075] The boundary conditions for the simulation are ceramic coatings 7, 8 with an increased dielectric constant of 12, which clearly shows the difference in properties compared to polymer-related dielectric coatings 7, 8 with an epsilon of 7. Due to the technical requirements of the injection molding process for depositing at least one polymer, the thickness of the polymer-related dielectric coatings 7, 8 is higher than that of ceramic dielectric coatings 7, 8. Experience has shown that the thickness of the polymer-related dielectric coatings 7, 8 can reach, for example, 0.5 mm. The ceramic dielectric coatings 7, 8 can have a thickness of, for example, 0.2 mm. The ceramic dielectric coatings 7, 8 can be applied, for example, by chemical vapor deposition of the dielectric onto the respective electrode sheets.

[0076] This analysis shows that, within certain regions, increasing the air gap advantageously increases the deposition power in the plasma 11 .

[0077] The plasma filter device 1 can include an electrode device 2 consisting of composite electrodes 3 and 4, as well as a planar dust filter 16 and an activated carbon filter 18, as shown in the figure, and can have a very small size compared to known plasma filter devices 1. The holder device can have a frame and an enclosure that can include a polymer material.

[0078] For gas decontamination, photons are generated in the UVC wavelength range. The plasma filter device 1 is configured to generate photons in the gap between the composite electrodes 3, 4 of the electrode device 2 by means of a plasma 11. The plasma 11 is generated in the discharge gap 9 via a dielectric barrier discharge.

[0079] The gas flowing through the plasma filter device 1 can be electrically guided onto the plasma 11 ignited in the discharge gap 9. Through this approach, high energy conversion at electron temperatures of 4-6 eV results in high photon densities>10 with wavelengths in the UVC range, as can be seen in Figure 2. 15 / s occurs.

[0080] At this UVC wavelength, a high reflectivity of up to 97% results from the dielectric and electrode structure used, which is not achievable with known assemblies from the prior art.

[0081] Unlike the use of commercially available UVC radiation sources, a 1000-10,000 times higher photon density is generated.

[0082] To carry out a comparison of the 20 W situation between UVC lamps and electrodes from the plasma filter unit in this case, six UV-C lamps of 20 cm length are required, which irradiate a cross section through a transparent ventilation tube 21 for UV-C through which the air flows, in this case also surrounded by an aluminum tube 21 with high reflectivity for UV radiation of the selected wavelength.

[0083] Aerosols contained in the air stream pass through the UVC activation region over 20 cm in approximately 0.11 seconds, with a photon density 100 to 1000 times lower than in the serpentine gap of the electrode device 2, where aerosols can remain for several minutes due to particle trapping. Therefore, the inactivation rate is a density x time product that is several orders of magnitude higher than with conventional UV-C lamps. Furthermore, the effectiveness of the plasma filter device 1 can be further increased by connecting multiple electrode devices 2 one after the other.

[0084] The aforementioned particle trapping effect for aerosol inactivation is described in more detail below. Aerosols generally consist of solid or liquid particles of different sizes. The majority are in the 100 μm range. However, it is also possible to start with particle components smaller than 5 μm or even smaller than 2.5 μm (reference: September 2019: DGUV Regulation 102-001, "Regulations for the prevention of biological agents in the classroom" (Deutschen Gesetzlichen Unfallversicherung eV, German Social Accident Insurance) DGUV "Regulations on safety during activities with biological agents in the classroom" eV DGUV). A droplet with a diameter of 100 μm takes about 6 seconds to fall from a height of 2 m to the ground, whereas a droplet with a diameter of 10 μm takes 10 minutes to cover the same distance, and a droplet with a diameter of 1 μm takes 16.6 hours (Source: Source Kappstein, Ines. Nosokomiale Infektionen: Prevention, Labordiagnostik, antimikrobielle Therapie; 122 Tabellen, Germany, Thieme 2009). Therefore, smaller particles remain in the air longer and can be distributed throughout the room via air movement, affecting the incidence of infection.

[0085] The effect of the electrode design and the arrangement of the electrode device 2 is that aerosol particles and molecules crucial for the occurrence of infection are trapped between the combined electrodes 3 and 4, where they can be effectively decontaminated. The best HEPA filters only filter out particles up to 0.3 μm in size.

[0086] As can be seen from Figures 3, 7 and 8, the majority of so-called airborne aerosol particles, classified as dangerously trapped, remain within the cylindrical serpentine structure of the electrode device 2, where a very large proportion of UV-C radiation is generated. The majority of airborne aerosol particles can be directly inactivated by the action of the UVC beam. Thus, even aerosols with particle sizes below 0.3 μm are inactivated through doses generated.

[0087] Due to the high photon density and enforced residence time of a defined particle fraction, high inactivation / decontamination rates are obtained.

[0088] A superspreader can spread up to 200,000 particles per second, or 2x10 5 Assume we generate 50 Sars-CoV-2 virus particles and a cubic meter source (reference: Michael Riediker; Dai-Hua Tsai, Estimation of Viral Aerosol Emissions from Simulated with Asymptomatic to Moderate Coronavirus Disease 2019, JAMA Network doi:10.1001 / jamanetworkopen.2020.13807). For example, 3 In a closed space, the concentration is thus 7 x 10 per cubic meter. 5 -7×10 7 virus particles accumulate from one person. Due to the high number of photons generated by the current plasma filter device 1, well over 10 photons / second, each particle receives a large number of UVC quantum hits. The extremely long particle residence time in the serpentine discharge gap 9 of the electrode device 2 allows for efficient inactivation. These results can prove the high level of effectiveness and efficiency of the plasma filter unit of the present invention.

[0089] The structure of the plasma filter device 1 has advantages compared to conventional solutions: with the plasma filter device 1 according to the invention, the laminar air flow has a very small pressure loss of about 5-6 Pa per electrode device 2, and a pressure of about 50 Pa can be achieved.

[0090] By providing application-specific filter sizes, very compact and small designs of only a few centimeters are possible, and are scalable for larger filter systems in the range of several meters, as can be seen in FIG.

[0091] The plasma filter device 1 is configured to operate in a laminar flow state at a speed of 250 to 300 m. 3It is possible to create a high flow rate of / h.

[0092] Due to the compact design and standard materials, manufacturing costs are low. The flat construction enabled by the shape of the plasma filter device 1 allows for direct integration of the plasma filter device 1 in, for example, ceiling ventilation systems. The plasma filter device 1's compact design and reduced noise emissions due to laminar airflow enable its integration into automotive and mobility applications.

[0093] The plasma filter device 1 according to the invention can replace existing filter systems in aircraft. The weight and installation space savings open up new design options for the cabin and supporting structure. The plasma filter device 1 allows for a direct replacement of complex filter cascades in buildings. This reduces the use of various variants of HEPA filter units, improves energy balance, reduces waste, and allows for the extension and / or modification of maintenance intervals. The compact design makes it possible to explicitly screen the plasma filter device 1 to ensure a high level of electromagnetic compatibility depending on the arrangement (see HF and B technology compatibility).

[0094] Due to the high electromagnetic susceptibility of electronic and imaging components, such as in magnetic resonance imaging devices, special emphasis must be placed on the electromagnetic compatibility and voltage supply technology of the plasma unit. Existing and commercially available solutions require expensive adaptations of the plasma generator and / or power electronics as well as the electrode technology used. In most cases, adaptations are not possible.

[0095] To ensure fully shielded EMC operation, the current plasma filter device 1 is recommended to be constructed with three crossed or non-crossed coated electrode devices 2, each separated by a spacer frame. This creates a Faraday cage, providing complete shielding up to a fundamental frequency of 10 kHz up to a relative electrode pin distance of 1-2 mm. The compact design of the electrode device 2 allows it to be housed, for example, together with the power electronics and / or plasma generator in a stainless steel tube 21, providing sufficient shielding.

Claims

1. A plasma filter device (1) having at least one electrode device (2), The electrode device (2) has a first composite electrode (3) formed in a plane and a second composite electrode (4) formed in a plane, the composite electrodes (3, 4) of the electrode device (2) are arranged flush with one another on a main plane (13) of the electrode device (2) and are spatially separated by a discharge gap (9); The first and second composite electrodes (3, 4) each have a comb-shaped structure with electrode fingers, and the electrode fingers engage with each other, so that the discharge gap (9) is serpentine; the composite electrodes (3, 4) each have an electrode sheet (5, 6) and a dielectric coating (7, 8) at at least one interface of the electrode sheet (5, 6) with the discharge gap (9), The first composite electrode (3) and the second composite electrode (4) are configured so that an AC voltage can be supplied between the composite electrodes (3, 4), the AC voltage is parameterized to form a plasma (11) by a dielectric barrier discharge in the discharge gap (9); the plasma filter device (1) is configured to guide the gas through the discharge gap (9) along a main flow direction (12) aligned parallel to the normal to the main plane (13) of the electrode device (2); A plasma filter device (1) characterized in that

2. the electrode sheets (5, 6) of each of the composite electrodes (3, 4) comprise aluminum and / or an aluminum alloy; 2. A plasma filter device (1) according to claim 1.

3. 2. The plasma filter device (1) according to claim 1, wherein the electrode sheets (5, 6) of each of the composite electrodes (3, 4) are stainless steel.

4. the dielectric coating (7, 8) of each of said composite electrodes (3, 4) comprises one or more polymers; 2. A plasma filter device (1) according to claim 1.

5. the dielectric coating (7, 8) of each of the composite electrodes (3, 4) comprises one or more fluoroplastics; 5. A plasma filter device (1) according to claim 4.

6. The dielectric coating (7, 8) of each of the composite electrodes (3, 4) comprises polyvinylidene fluoride. Plasma filter device (1) according to claim 5.

7. the dielectric coating (7, 8) of each of the composite electrodes (3, 4) comprises polytetrafluoroethylene; Plasma filter device (1) according to claim 5.

8. the dielectric coating (7, 8) of each of the composite electrodes (3, 4) comprises graphite fluoride; 2. A plasma filter device (1) according to claim 1.

9. the dielectric coating (7, 8) of each of the composite electrodes (3, 4) comprises one or more ceramics; 2. A plasma filter device (1) according to claim 1.

10. 10. The plasma filter device (1) according to claim 9, characterized in that the dielectric coating (7, 8) of each of the composite electrodes (3, 4) comprises barium titanate.

11. the dielectric coating (7, 8) of each of the composite electrodes (3, 4) comprises kaolinite; 10. Plasma filter device (1) according to claim 9.

12. the dielectric coating (7, 8) of each of the composite electrodes (3, 4) has a blend containing predetermined proportions of kaolinite, aluminum oxide, titanium oxide, chromium oxide, barium titanate and / or other ceramic powders; 10. Plasma filter device (1) according to claim 9.

13. The plasma filter device (1) has at least two of the electrode devices (2), The plasma filter device (1) has a holder device (20), which is configured to arrange the at least two electrode devices (2) in a predetermined electrode arrangement, the at least two electrode devices (2) being arranged parallel to each other in the predetermined electrode arrangement and spaced apart in pairs by a predetermined distance (15) along the main flow direction (12). A plasma filter device (1) according to any one of claims 1 to 12, characterized in that it

14. Adjacent electrode devices (2) of the at least two electrode devices (2) are aligned at 90° rotation relative to each other around the main flow direction (12).

14. Plasma filter device (1) according to claim 13.

15. 2. The plasma filter device (1) according to claim 1, characterized in that the plasma filter device (1) comprises at least one dust filter (16), which is arranged in front of the electrode device (2) with respect to the main flow direction (12).

16. 2. The plasma filter device (1) according to claim 1, characterized in that the plasma filter device (1) comprises at least one activated carbon filter (18) and is arranged after the electrode device (2) with respect to the main flow direction (12).

17. An electrode device (2) for a plasma filter device, comprising: The electrode device (2) has a first composite electrode (3) formed in a planar shape and a second composite electrode (4) formed in a planar shape, the composite electrodes (3, 4) of the electrode device (2) are arranged flush with one another in a main plane (13) of the electrode device (2) and are spatially separated from one another by a discharge gap (9); The first and second composite electrodes (3, 4) each have a comb-shaped structure with electrode fingers, and the electrode fingers engage with each other, so that the discharge gap (9) is serpentine; the composite electrodes (3, 4) each have an electrode sheet (5, 6) and a dielectric coating (7, 8) on at least one interface of the electrode sheets (5, 6) with the discharge gap (9), respectively; The first composite electrode (3) and the second composite electrode (4) are configured so that an AC voltage can be supplied between the composite electrodes (3, 4). An electrode device (2) characterized in that

18. A method for operating a plasma filter device (1), comprising: The plasma filter device (1) has at least one electrode device (2), and the electrode device (2) has a first composite electrode (3) formed in a plane and a second composite electrode (4) formed in a plane; the composite electrodes (3, 4) of the electrode device (2) are arranged flush with one another in a main plane (13) of the electrode device (2) and are spatially separated from one another by a discharge gap (9); The first and second composite electrodes (3, 4) each have a comb-shaped structure with electrode fingers, and the electrode fingers engage with each other, so that the discharge gap (9) is serpentine; each of the composite electrodes (3, 4) having an electrode sheet (5, 6) and a dielectric coating (7, 8) at at least one interface of each of the electrode sheets (5, 6) with the discharge gap (9); an AC voltage is applied between the first composite electrode (3) and the second composite electrode (4), whereby a plasma (11) is generated by a dielectric barrier discharge in the discharge gap (9); The plasma filter device (1) guides the gas through the discharge gap (9) along a main flow direction (12) parallel to the normal to the main plane (13) of the electrode device (2). A method of operation characterized by:

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