Hybrid filter unit

Abstract

The present invention relates to a hybrid filter unit (2) comprising a housing (4) having an inlet (6) for the inflow of a fluid to be purified and an outlet (8) for the outflow of the purified fluid. The hybrid filter unit (2) further comprises a wall structure (16) disposed inside the housing that defines a fluid mixing chamber (18), the wall structure defining an internal cross-sectional area that decreases at least partially in the direction from the inlet (6) to the outlet (8). The hybrid filter unit (2) further comprises a nozzle (14) disposed to supply an oxidizer to the mixing chamber (18), thereby exposing the fluid to the oxidizer as it flows between the inlet and the outlet and allowing it to react with the oxidizer. The hybrid filter unit (2) further comprises a filtration structure (74) disposed between the inner wall surface of the housing and the outer wall surface of the wall structure, the filtration structure comprising volcanic pumice (78), and the wall structure (16) is at least partially adapted to the flow of fluid from the mixing chamber (18) to the filtration structure (74).

Description

Technical Field

[0001] The present invention relates to a hybrid filter unit. The term "hybrid" refers to the filter being adapted to multiple different filtration technologies. Further, this hybrid filter unit can be used for air purification. More specifically, air may contain various contaminants and pollutants, including organic and inorganic chemical substances, volatile organic compounds (VOCs), particles of various sizes, microorganisms such as various viruses and bacteria, molds and fungi, unpleasant odors, and substances that may have an adverse impact on the environment and organisms. In different applications, it is desired to remove one or more of these contaminants and pollutants to purify the air. More specifically, the hybrid filter unit can be used, for example, in the central ventilation system of an apartment building, an office building, or an industrial building, or as an independent plug-in air purifier for use in a dedicated space such as an office or a private residence (such as an apartment building or a house).

Background Art

[0002] Various types of filters are known in different filtration categories, such as physical / mechanical filtration, chemical filtration, and electrical filtration. Physical / mechanical filters include coarse filtration filters for coarse particles, fine filters for fine particles, and ultra-fine filters for ultra-fine particles. Chemical filters may be classified into ionization, oxidation, inorganic filtration, and organic filtration. Electrical filters may be based on polarization (electrostatic filtration).

Summary of the Invention

Problems to be Solved by the Invention

[0003] The first object of the present invention is to provide a hybrid filter unit adapted to purify a fluid such as air with high efficiency by at least two filtration methods, which has good spatial efficiency while simultaneously having a pressure loss lower than the total pressure loss of various filters arranged in separate units. [Means for solving the problem]

[0004] This objective is achieved by the apparatus according to claim 1. Therefore, a hybrid filter unit, - A housing comprising an inlet for the fluid to be purified and an outlet for the purified fluid, - A wall structure located inside the housing that defines a fluid mixing chamber, the wall structure defining an internal cross-sectional area that decreases at least partially in the direction from the inlet to the outlet, - A nozzle positioned to supply an oxidizing agent to a mixing chamber, thereby exposing the fluid to the oxidizing agent as it flows between the inlet and outlet, and allowing it to react with the oxidizing agent. - A filtration structure disposed between the inner wall surface of the housing and the outer wall surface of the wall structure, wherein the filtration structure contains volcanic pumice, and the wall structure is at least partially adapted for the flow of fluid from the mixing chamber to the filtration structure. This is achieved by a hybrid filter unit equipped with [specific features / features].

[0005] In one example, the housing comprises walls that define the internal space of the housing, and the wall structure providing the mixing chamber is located within the internal space. Thus, the wall structure may be formed separately from the housing. In one example, the housing walls define a substantially equal cross-sectional area along the length of the housing in the direction between the inlet and the outlet, while the wall structure defines a cross-sectional area that decreases at least partially in the direction from the inlet to the outlet.

[0006] In one example, the wall structure has an internal conical wall defining a mixing chamber, which forms a space for mixing and most chemical reactions. In another example, the tip of the internal conical wall is blocked by a transversely impermeable wall. Due to the wall structure having at least partially reduced internal cross-sectional area (being pointed), and the blocking of the tip of the internal conical wall, a specific hydraulic flow is generated, which increases the fluid pressure at the blocked tip of the wall structure, thereby compensating for at least some of the overall pressure loss of the filter by diverting the flow towards the inclined mesh wall and generating vortices that contribute to better mixing and longer reaction contact times. In other words, the tapered / conical shape of the inner wall extends the contact time between the oxidizer and the incoming air, in which case the direction of fluid flow may change and the probability of collisions between elements in the fluid flow increases.

[0007] In an application example of the hybrid filter unit, a circulating suction fan is operationally connected to the hybrid filter unit to draw fluid through the filter unit. To ensure optimal contact time, there should be a proportional relationship between the flow rate (RPM) of the circulating suction fan and the injection flow rate of the oxidizer.

[0008] In extreme cases, if the volumetric flow rate (RPM) of the suction fan is excessively high relative to the injection flow rate, the exposure time between the oxidizer and the fluid in the mixing chamber will be insufficient. In this case, the dosage of the oxidizer in the injected flow must be sufficiently high for it to be effective in the mixing chamber. The design of the hybrid filter unit increases the mixing probability and thus creates conditions that maximize the probability and yield of the reaction.

[0009] Factors influencing contact time include the dosage (concentration) of the oxidizer, the injection flow rate of the oxidizer, the fan flow rate, the concentration of contaminants, the hydraulics of the flow, the housing volume of the hybrid filter unit, the room volume (the space where the air is purified), and the permissible air circulation frequency in the room.

[0010] Furthermore, the statement that the wall structure is at least partially adapted to the flow of fluid indicates that the wall structure is permeable, where coarse particles / materials may be collected within the hybrid filter unit. This is achieved by the mesh size of at least one wall within the wall structure being smaller than the diameter of such coarse particles. In other words, the wall structure is arranged with a hole pattern through which some particles can pass. For example, the wall structure comprises walls having a uniform hole pattern throughout its entire extent.

[0011] Next, we will discuss non-electrically charged particulate matter. Most microbial oxidation reactions release CO2, H2O, and other products. Furthermore, the surrounding air contains moisture and water vapor. Dust can absorb moisture and increase in weight, causing dust particles to stick together, increasing the size of dust clumps, which can then be trapped in hybrid filter units (such as the surface of a wall structure and / or the surface of downstream porous pumice that is moist for similar reasons).

[0012] Next, we will discuss uncharged ultrafine particles. These may be filtered by a combination of oxidation processes and the filtering effect of other components, including pumice (and possibly wood fibers and coal, details of which will follow), which occur throughout the housing during operation in the presence of water vapor and moisture from the two aforementioned sources (moisture in the air and oxidation reaction products of microorganisms).

[0013] Next, we will discuss minerals (e.g., H2S), organic matter (VOCs), and microorganisms (bacteria, viruses, molds, fungi, etc.). These can be filtered through a combination of oxidation processes and filtration effects by other components, including pumice (and possibly wood fibers and coal, details of which will be discussed later), and this combination occurs throughout the housing.

[0014] Furthermore, certain chemicals such as H2S are known to cause unpleasant odors. The operation of the hybrid filter unit creates conditions for odor reduction by having an oxidizing process with an oxidizing agent that changes the chemical composition of the substance (e.g., leading to odor removal) and / or changes its physical composition (e.g., particles becoming larger because they have been oxidized and transformed into other substances). This makes the substance suitable for filtration by downstream physical filtration components.

[0015] Furthermore, hybrid filter units create conditions for minimizing pressure loss during filter operation. This can be achieved by performing multiple filtration processes within a single, potentially compact housing. In contrast, the total pressure loss when multiple filters with different filtration functions are stacked sequentially is the sum of the individual pressure losses of each filter. In other words, this characteristic creates conditions for reduced pressure loss compared to a stacked combination of units of the same operating type adapted to obtain similar filtration and / or processing results.

[0016] In one embodiment, the housing is cylindrical, with an inlet located at a first end in the axial direction of the cylindrical housing, and an outlet located at a second end opposite the first end in the axial direction of the cylindrical housing. In one embodiment, the inlet and / or outlet are positioned such that the principal axes of the inlet / outlet are parallel to the central axis of the cylindrical housing. In one further embodiment, the inlet and / or outlet are located on a transverse wall defining the end of the housing in the longitudinal direction of the housing. In one embodiment, the housing is circular cylinder.

[0017] According to one embodiment, the mixing chamber provides space for a chemical reaction between the fluid to be purified and an oxidizing agent introduced into the housing by a nozzle. The oxidizing agent used in the reaction may be generated outside the housing.

[0018] In an example of a further embodiment, the wall structure comprises a first wall and a second wall spaced apart, the inner surface of the first wall defining a mixing chamber, and the outer surface of the second wall defining the outer wall surface of the wall structure. In one example, each of the first and second walls is at least partially adapted for fluid flow. In one example, the first and second walls have similar structures with respect to material and hole pattern. Furthermore, by spacing the two walls apart, conditions are created for collecting particles in the space between the walls.

[0019] In an example of a further embodiment, at least one of the first wall and the second wall has a broad end open to the mixing chamber and a pointed end opposite the broad end, and the cross-section of the first wall and / or the second wall is at least partially reduced in the direction from the broad end to the pointed end. In one example, each of the first wall and the second wall has a broad end open to the mixing chamber and a pointed end opposite the broad end.

[0020] In an example of a further embodiment, the wider end of the first wall and the second wall faces the inlet so that the fluid can flow into the mixing chamber through the wider end. In one example, each of the wider ends of the first wall and the second wall faces the inlet.

[0021] In an example of a further embodiment, at least one of the first wall and the second wall is conical, with the base of the conical wall forming a broad end. In one example, each of the first wall and the second wall is conical.

[0022] In an example of a further embodiment, the central axis of the first conical wall and / or the central axis of the second conical wall coincide with the central axis of the housing. In one example, the first wall and the second wall are arranged such that the central axes of the first conical wall and the central axes of the second conical wall coincide with the central axis of the housing.

[0023] According to an example of a further embodiment, the wide end of at least one of the first wall and the second wall has a cross-sectional size and shape that is substantially the same as or slightly smaller than the inner cross-sectional shape and size of the housing for receiving substantially the entire flow rate of the fluid flowing between the inlet and the outlet. According to one example, the wide end of each of the first wall and the second wall has a cross-sectional size and shape that is substantially the same as or slightly smaller than the inner cross-sectional shape and size of the housing.

[0024] In other words, the first wall and the second wall are arranged such that a gap is formed between the outer surface of the first wall and the inner surface of the second wall. According to one example, the second wall defines a sharper tip than the first wall, and the gap between the walls increases in the direction from the wide end towards the pointed end. This creates an additional space for collecting substances between the walls.

[0025] According to one example, the inner conical wall defines a mixing chamber and forms a space for mixing and most chemical reactions. The first wall itself can be designed not to adsorb minerals, microorganisms, and other substances in the fluid to be treated. However, the first wall houses them and allows them to react with the oxidizing agent. Unreacted substances are captured in the housing by other filtering mechanisms.

[0026] As described above, the filtration structure includes a plurality of volcanic pumices that are at least partially rounded and have pores. This provides a significant surface area, leading to an increase in the contact area and contact time during operation, and as a result, an increase in the adsorption of substances. Furthermore, the volcanic pumice acts like a catalyst, and due to its inherent chemical properties and the mineral components contained within the pores, it promotes chemical reactions in addition to increasing the contact time and reaction surface area. Additionally, the filtration structure may include dry wood fibers and / or activated carbon, which are provided between the volcanic pumices. The pores of the pumice may retain sufficient moisture to promote the chemical reactions during operation. This moisture is supplied by the humidity of the ambient air (fluid) and / or the water of formation generated by the chemical reaction. When there is no oxidizing agent in the downstream filtration section, especially when using non-volcanic pumice, the likelihood of microbial colonies growing inside the wood fiber or activated carbon or pumice section increases. Therefore, this design takes into account the ability of the oxidizing agent to also be present in the downstream filtration medium. This prevents the growth of microorganisms and also prevents the diffusion of free radical atoms / ions into the room where the air is purified.

[0027] Minerals, microorganisms, and all other such substances that do not have sufficient contact time to react with the oxidizing agent flow through the wall structure into the pumice stones. The pumice stones provide sufficient contact time for chemical reactions due to their pores and high surface area, complete the oxidation of the residual substances, and increase the physical capture probability within the filter.

[0028] The roundness of the pumice stones minimizes the pressure loss. This enables the miniaturization of the suction fan arranged to suck the fluid passing through the pumice stones, thus creating conditions for reducing power consumption and / or improving the cost efficiency of the unit. In other words, it is cost-effective in terms of reducing the amount of energy required during operation compared to a combination of stacked units. This is one of the decisive factors when selecting the filtration technology and the type of filtration product.

[0029] Dry wood fibers and activated carbon can be adapted to adjust pressure drop. In other words, by changing the amount of dry wood fibers and activated carbon depending on the application, the pressure drop can be adjusted / adjusted according to the unit's application and the target quality of the purified air (e.g., home / hospital / cleanroom). For example, small amounts of activated carbon and wood fibers can be used between the pumice stones to fill the voids in the pumice. These are optional items for improving adsorption efficiency and adjusting pressure drop.

[0030] The effective particle size of carbon that can be used here is preferably in the range of 0.2 mm to 1.8 mm. The wood fibers are thread-like in shape of various lengths, and their cross-section is 0.1 * It has a shape that is almost rectangular with dimensions of 2 mm.

[0031] Furthermore, volcanic pumice possesses mineral properties (the presence of mineral substances such as sulfur, manganese (Mn), and magnesium (Mg), which inhibit the growth of microorganisms (e.g., algae). The main extent / diameter size of individual pumice stones is in the range of 20-50 mm, preferably about 50 mm.

[0032] Furthermore, the hybrid filter unit creates conditions for noise minimization through the arrangement of pumice and the pointed shape of the conical walls, thus changing the direction of sound waves. In addition, the filtration structure, which includes volcanic pumice (and possibly wood fibers or activated carbon), has the potential to adsorb ultrafine particles.

[0033] In an example of a further embodiment, the hybrid filter unit includes a device for attracting charged particles in a fluid flow, which is located within a housing and comprises a spaced-apart inner conductive element and an outer conductive element, which are adapted to be connectable to a power supply to be reverse-charged so as to attract charged particles in the fluid to one of the conductive elements, the power supply adapted to supply a low voltage and connected so as to positively charge the inner conductive element. Some of the particles in the fluid flow may be charged by chemical reactions occurring within the housing when the fluid is exposed to an oxidizing agent. Other particles in the fluid may already be charged when the fluid enters the housing. A low voltage means that only the cone is electrostatically charged and does not produce electrical discharge conditions such as glow discharge or corona discharge. Discharge is avoided for safety reasons and due to the presence of carbon and other flammable physical structures present in typical filters.

[0034] Therefore, during operation, the inner conductive element (adaptable to form an inner cone) is positively charged, and the outer conductive element (adaptable to form an outer cone) is negatively charged. For example, the inner conductive element is connected only to the positive terminal (+24V) of a 24-volt power supply, and the outer conductive element is connected to the negative terminal (-24V) of a 24-volt power supply.

[0035] When the space between two (conical) conductive elements becomes filled with particles / material, that space needs to be emptied. The fact that the two conductive elements are positively and negatively charged allows them to be used as sensors that can trigger an alarm when emptiness is needed. More specifically, a control circuit can be connected to the two conductive elements. When a short circuit begins to occur, the current starts to increase and, when it reaches a predetermined threshold indicating a fire risk, the control circuit discharges the positively charged cone from the anode, followed by the negatively charged cone from the cathode, at which point the voltage difference between the two cones becomes zero. An error is then notified to have a maintenance worker clean the space between the two conductive elements.

[0036] In an example of a further embodiment, the device for attracting charged particles is positioned downstream of the nozzle in the direction of fluid flow between the inlet and outlet. Thus, the hybrid filter unit creates the conditions for a sequence in which particles are first charged and then attracted as they flow through the housing. In other words, the hybrid filter unit creates the conditions for a polarization process during operation, in which particles that have become charged by reacting with the oxidizing agent in the mixing chamber are adsorbed onto conductive elements with the opposite charge. Some particles are negatively charged and are therefore attracted to positively charged conductive elements, while other positively charged particles are attracted to negatively charged conductive elements.

[0037] In an example of a further embodiment, at least one of the inner conductive element and the outer conductive element forms one of the first wall and the second wall of the wall structure defining the mixing chamber. Thus, the device attracting charged particles can be integrated into the wall structure. This creates conditions for realizing a space-saving unit. In one example, the inner conductive element forms the first wall of the wall structure defining the mixing chamber, and the outer conductive element forms the second wall.

[0038] According to an example of a further embodiment, the inner conductive element is positioned at least partially inside the outer conductive element. The inner and outer conductive elements are positioned so that particles can be collected in the space between them.

[0039] In an example of a further embodiment, the outer conductive element is positioned downstream of the inner conductive element in the fluid flow direction.

[0040] Therefore, the space between the first and second walls is empty in the initial operating state and can capture dust and some particles during operation. It should be noted that this space may capture and / or adsorb not only charged particles, but also organic matter including minerals and microorganisms, TVOCs, and products and by-products of chemical reactions between pollutants and oxidizers in the incoming fluid (liquids such as water and acid).

[0041] Therefore, charged substances are adsorbed and trapped by the polarization process of the two conical walls and cannot reach the pumice. On the other hand, particles that are not charged enough to be adsorbed by the two conical walls pass through both walls and reach the filtration structure, where they are exposed to the pumice, possibly activated carbon or wood fibers, and any present moisture.

[0042] In an example of a further embodiment, the hybrid filter unit includes an element that provides electrical insulation between an inner conductive element and an outer conductive element. In one example, the electrical insulation element is provided adjacent to the broad end of the conductive element. More specifically, the conductive element may be detachably attached to the electrical insulation element to facilitate disassembly.

[0043] In an example of a further embodiment, the housing has a first open end, and the hybrid filter unit has a first cap defining an opening, the first cap being fitted to connect to the first open end of the housing such that the cap opening forms an entrance to the housing, and at least one of the conductive elements is attached to the cap. In one example, the end cap is fitted to hold both (conical) conductive elements, where the hybrid filter unit is easily opened, the two (conical) conductive elements are separated, and the space is emptied for maintenance.

[0044] In an example of a further embodiment, at least one of the first conductive element and the second conductive element is detachably attached to the first cap, thereby allowing access to the space between the first and second conductive elements for cleaning.

[0045] According to an example of a further embodiment, the first cap forms an electrical insulating element between the first conductive element and the second conductive element.

[0046] In an example of a further embodiment, the housing comprises a second open end, and the hybrid filter unit comprises a second cap defining the opening, the second cap being adapted to connect to the second open end of the housing such that the cap opening forms an outlet of the housing. Furthermore, the second cap may be positioned downstream of the conical wall structure to contact the pumice and to fill the pumice and, optionally, other contents of the filter structure.

[0047] In an example of a further embodiment, the nozzle is positioned in the wall of the housing, so that its inner end is located inside the housing, and the nozzle body extends transversely to the central axis of the housing between the inlet and outlet. Furthermore, the inner end of the nozzle may be positioned inside a mixing chamber defined by the wall structure.

[0048] In an example of a further embodiment, the hybrid filter unit includes means for discharging by-products resulting from the reaction between a fluid and an oxidizing agent. These by-products may be other liquids such as water or carbonic acid, but depending on the pollutants in the inflow air, the liquids may also contain other chemicals that are by-products of the reaction between the oxidizing agent and the pollutants. Most possible by-products are acidic, but usually weakly acidic. Furthermore, solid by-products, such as various mineral salts, may also be present that can dissolve in the liquid by-products and be discharged.

[0049] Because the filter is cylindrical, the liquid is drawn more towards its bottom (the lowest point in the vertical direction), and therefore, to maximize discharge, the nozzle should be positioned at the bottom of the filter.

[0050] In a further aspect of the present invention, the present invention relates to a fluid purification device comprising an oxidant generator and a hybrid filter unit according to any of the prior embodiments and examples, wherein the oxidant generator is located separately from the hybrid filter unit, and the outlet of the oxidant generator is operably connected to a nozzle for supplying the oxidant to the hybrid filter unit. In one example, the oxidant generator is a Branilium® reactor.

[0051] According to one embodiment, the oxidizing agent generating apparatus is adapted to generate an oxidizing agent by exposing a further fluid to a discharge / plasma for ionization.

[0052] In an example of a further embodiment, the oxidizer generator is adapted to generate an oxidizer by exposing air to a discharge / plasma independent of the ground / earth electrode or the electrode.

[0053] In an example of a further embodiment, the fluid purification system includes an external air source located separately from the oxidizer generator, the external air source is configured to receive air from outdoors, and the external air source is operably connected to the inlet of the oxidizer generator, supplying the received outdoor air to the oxidizer generator to reduce the risks associated with the use of contaminated indoor air.

[0054] The air used for the oxidizer generator may be ambient air collected from outside the space / building containing the air to be purified. Therefore, the air used for the oxidizer generator and the air purified by the hybrid filter unit may be collected from different sources.

[0055] In a hybrid air purification system, the ionization process involves the emission (discharge) of electrons and / or positrons from electrodes under the influence of a high alternating current (AC) voltage. This high voltage application is crucial because it provides the energy necessary to overcome the ionization potential of molecules (primarily oxygen) in the surrounding air. When an AC voltage is applied, a strong electric field is generated within the chamber or around the electrodes. This electric field accelerates free electrons and provides sufficient energy to ionize oxygen and other present gases, resulting in the generation of ions and various reactive oxidizing species.

[0056] On the other hand, the hybrid filter unit can also be used by directly injecting an external oxidizing source, such as a chemical capsule containing chlorine (Cl2), titanium dioxide (TiO2), or formalin, into the chamber, without relying on ionization. These substances act as powerful oxidizing agents, chemically altering and neutralizing airborne pollutants. This method does not rely on ion generation by discharge and provides an alternative air purification mechanism that can be effective under different conditions.

[0057] The generated ions and reactive species are essential to the air purification process because they effectively neutralize pollutants, pathogens, and odors. It should be noted that the term "ionizer / anion generator" used in commercially available air purifiers is misleading. Many devices are marketed as "ionizers," implying harmless ion generation, but some generate large amounts of ozone as a byproduct. Ozone is a powerful oxidizing agent, but it is harmful to health above a certain concentration. The effectiveness and safety of these systems depend on the design and characteristics of the discharge method employed. A properly designed system will ensure that air quality is improved through ion generation without raising ozone levels to harmful levels.

[0058] It is appropriate to mention the limitations of certain air purifiers that employ direct current (DC) and low-voltage transformers. Physically, these systems typically do not provide sufficient energy for effective ionization. Ionization requires electrons to gain enough kinetic energy to detach from atoms and ionize surrounding gas molecules. DC systems and low-voltage configurations often fail to reach this energy threshold necessary to initiate and maintain the ionization process.

[0059] If the claim that simple DC low-voltage systems can sufficiently ionize air were valid, then common household appliances such as mobile chargers and electrical plugs, which also operate at low voltage (around 230V in many areas), would essentially ionize the air as well. This would mean that all indoor spaces with such devices would be automatically purified. However, such a phenomenon is not observed in real-world situations. The fact that widespread ionization does not occur in the everyday environments where these devices are present highlights the need for specific high-voltage AC systems in air purifiers designed to achieve effective ionization. These high-voltage systems create the conditions necessary for electron acceleration and subsequent air ionization, which cannot be replicated with standard DC drives or low-voltage electrical systems.

[0060] In an example of a further embodiment, the fluid purification device comprises a mounting frame, and the ionizer and hybrid filter unit are fixedly connected to the mounting frame in parallel. In one example, mounting portions at opposite ends of the ionizer and hybrid filter unit are adapted to be attached to corresponding mounting portions on opposing, spaced-out walls of the mounting frame.

[0061] The configuration in which the oxidizer generator is positioned externally to the hybrid filter unit avoids the accumulation of oil and dust within the hybrid filter unit, creating conditions that prevent oil contamination of the filter structure and oxidizer nozzle. This creates conditions that improve the efficiency (yield) of the oxidizer. Furthermore, it creates conditions in which the oxidizer is generated more efficiently and is independent of the contaminants in the fluid being purified.

[0062] For example, an oxidizing agent may include a substance containing radicals and free electrons and positrons. Such particles (electrons, positrons, and possibly quarks and / or muons) are therefore free and available. Electrons and positrons have negative and positive charges, respectively, and can attach to / induce dust and other particulate matter in the air to charge them. For example, such an oxidizing agent may be generated by an ionization process occurring elsewhere than the hybrid filter unit.

[0063] Physical particles in the air (such as wool, dust, and human or pet hair) acquire an electric charge through reaction with oxidizing agents. Some dust particles are already charged in the air (due to friction), but their charge can be amplified by mixing with oxidizing agents.

[0064] Next, we will describe the mechanism by which charged particles are attracted in a fluid flow. The opposite charges of the first and second conductive elements create the polarization conditions that are used to adsorb dust and fine particles.

[0065] In summary, the hybrid filter unit creates the conditions for the following steps during operation: 1. Some dust particles can become charged and be attracted to the surface of a charged element by an electrostatic mechanism. 2. Some other uncharged particles are adsorbed to the wall structure due to increased weight. 3. Any other particles that were not adsorbed in the first two steps above will eventually be trapped by the wall structure at some point after the indoor air has been circulated several times by the suction fan.

[0066] Further advantages and favorable features of the present invention are disclosed in the following description and dependent claims.

[0067] Refer to the attached drawings to describe in more detail the embodiments of the present invention given as examples. [Brief explanation of the drawing]

[0068] [Figure 1]This is a schematic perspective view of a hybrid filter unit according to the first embodiment. [Figure 2] Figure 1 is an exploded view of the hybrid filter unit. [Figure 3] This is a cross-sectional view of the hybrid filter unit shown in Figure 1 with additional components added. [Figure 4] Figure 1 is a schematic cross-sectional view of the hybrid filter unit, showing the flow of hydraulic fluid. [Figure 5] This is a schematic perspective view of a fluid purification device according to the first embodiment, which comprises a hybrid filter unit and an oxidizing agent generating device as shown in Figure 1. [Figure 6] Figure 5 is a partially disassembled cross-sectional perspective view of the oxidizing agent generating apparatus. [Figure 7] This is a perspective view of the mounting frame, showing the hybrid filter unit and oxidizer generator as shown in Figure 5. [Figure 8] This is a schematic perspective view of a hybrid filter unit according to the second embodiment. [Figure 9] This is a perspective view of the mounting frame, showing two hybrid filter units, each equipped with its associated oxidizer generating device, installed in the frame. [Figure 10] Figure 6 is a cross-sectional view of the ionization unit included in the oxidizing agent generating apparatus. [Figure 11] This is an alternative embodiment of the ionization unit. [Modes for carrying out the invention]

[0069] Figure 1 is a schematic perspective view of the hybrid filter unit 2 according to the first embodiment. Figure 2 is an exploded view of the hybrid filter unit 2 of Figure 1. The hybrid filter unit 2 includes a housing 4 which has an input inlet 6 for the fluid to be purified and an output outlet 8 for the purified fluid.

[0070] The housing 4 is cylindrical, with an inlet 6 located at a first end 10 in the axial direction of the cylindrical housing 4, and an outlet 8 located at a second end 12 opposite to the first end 10 in the axial direction of the cylindrical housing 4. More specifically, the housing 4 is a circular cylinder. Each of the inlet 6 and outlet 8 has an axis parallel to the axial direction of the cylindrical housing. More specifically, each of the inlet 6 and outlet 8 is located within an end wall that defines the interior of the housing 4 in the axial direction.

[0071] The hybrid filter unit 2 includes a nozzle 14 that provides an oxidizer into the internal space of the housing 4 so that the fluid is exposed to the oxidizer as it flows between the inlet 6 and outlet 8 and can react with the oxidizer. The oxidizer can be supplied from various types of sources, such as being stored in a capsule or being generated adjacent to the hybrid filter using a reactor or oxidizer generator, and in some cases simultaneously with the operation of the hybrid filter.

[0072] The hybrid filter unit 2 further includes a wall structure 16 within the housing 4 that defines a fluid mixing chamber 18. The wall structure 16 has a flow penetration area that decreases at least partially in the direction from the inlet 6 to the outlet 8. Specifically, the wall structure 16 includes a first wall 20 that defines the mixing chamber 18 in the transverse direction of the housing 4. Specifically, the first wall 20 defines the mixing chamber 18 in the radial direction of the cylindrical housing 4. More specifically, the first wall 20 has a flow penetration area that decreases in the direction from the inlet 6 to the outlet 8. Specifically, the first wall 20 is conical in shape. Such a tapered shape of the inner wall 20 has the effect of allowing the fluid flow and particles in the flow to change direction (see also Figure 4), thereby achieving uniform mixing.

[0073] The wall structure 16 further includes a second wall 22 positioned near the first wall 20 and spaced apart from the first wall 20 in the axial direction of the housing 4. This creates a gap between the first wall 20 and the second wall 22. Specifically, the second wall 22 also has a conical shape. The wider ends of the first conical wall 20 and the second conical wall 22 face the entrance 6.

[0074] Each of the first wall 20 and the second wall 22 of the wall structure 16 is at least partially adapted to fluid flow, i.e., permeable. More specifically, each of the first wall 20 and the second wall 22 of the wall structure 16 has a mesh or grid-like pattern of holes that allows fluid to pass through each wall. More specifically, each of the first wall 20 and the second wall 22 of the wall structure 16 has a pattern of holes along its entire length.

[0075] The hybrid filter unit 2 further includes a device 24 for attracting charged particles in the fluid flow. The device 24 is located within the housing 4, and the charged particle attractor comprises a first conductive element 26 and a second conductive element 28 that are spaced apart. The first conductive element 26 and the second conductive element 28 are connected to a power supply 30 (see Figure 3) and are adapted to carry opposite charges (see plus signs 40 and minus signs 42 in Figure 2). This causes charged particles in the fluid to be attracted to either the conductive element 26 or 28.

[0076] The charged particle attracting device 24 is located downstream of the nozzle 14 in the fluid flow direction between the inlet 6 and the outlet 8. More specifically, the first conductive element 26 and the second conductive element 28 each form either the first wall 20 or the second wall 22 of the wall structure 16 that defines the mixing chamber 18.

[0077] Therefore, each of the first conductive element 26 and the second conductive element 28 has a broad end 32, 34 that is open to the mixing chamber 18 and a pointed end 36, 38 opposite the broad end, and the cross-section of the conductive element decreases in the direction from the broad end 32, 34 to the pointed end 36, 38. Furthermore, the broad ends 32, 34 of each of the first conductive element 26 and the second conductive element 28 face the inlet so that the fluid can flow into the mixing chamber 18 from the broad end. In other words, each of the first conductive element 26 and the second conductive element 28 is conical in shape, and the base of the conical conductive elements 26, 28 forms the broad end.

[0078] Furthermore, the central axis 21 of the conical first conductive element 26 and the central axis 23 of the second conductive element 28 coincide with the central axis 5 of the housing 4.

[0079] Furthermore, the at least one broad end 32, 34 of the first conductive element 26 and the second conductive element 28 has a cross-sectional size and shape that is substantially the same as, or slightly smaller than, the inner cross-sectional shape and size of the housing 4 for receiving a nearly complete flow of fluid between the inlet 6 and the outlet 8.

[0080] More specifically, the first conductive element 26 is positioned at least partially inside the second conductive element 28, and the first conductive element 26 and the second conductive element 28 are positioned such that dust and / or fine particles are collected in the space between the first conductive element 26 and the second conductive element 28. More specifically, the second conductive element 28 is positioned downstream of the first conductive element 26 in the central axis direction of the housing between the inlet 6 and the outlet 8.

[0081] The hybrid filter unit 2 further includes an element 44 that provides electrical insulation between the first conductive element 26 and the second conductive element 28. This element 44 is positioned at the wider ends 32, 34 of the elements 26, 28. The electrical insulation element 44 has an annular shape and includes two radially spaced receiving portions 46, 48 for receiving the wider ends 32, 34 of the first conductive element 26 and the second conductive element 28. More specifically, each of the receiving portions 46, 48 is formed by a circular slot. The first conductive element 26 and the second conductive element 28 each have cylindrical ends 60, 62 of a certain diameter for receiving into the circular slots 46, 48.

[0082] The housing 4 has a first open end 50, and the hybrid filter unit has a first cap 52 defining an opening 54, which is fitted to connect to the first open end 50 of the housing 4 such that the cap opening 54 forms an inlet 8 of the housing. More specifically, each of the conductive elements 26, 28 is attached to the first cap 52. According to the first embodiment, the first cap 52 forms an electrical insulating element 44.

[0083] Furthermore, the first cap 52 is detachably attached to the housing 4. The first cap 52 comprises an annular wall 56 having an extension perpendicular to the central axis 5 of the housing 4, and a cylindrical portion 58 having an axis parallel to the central axis 5 of the housing 4. The annular wall 56 and the cylindrical portion 58 are formed as an integrated unit. The inner diameter of the cylindrical portion 58 is slightly larger than the outer diameter of the housing 4, ensuring a tight fit. The first conductive element 26 and the second conductive element 28 are each detachably attached to the first cap 52, allowing access to the space between the first conductive element 26 and the second conductive element 28 for cleaning.

[0084] The housing 4 further includes a second open end 64, and the hybrid filter unit 2 includes a second cap 66 defining an opening 68, the cap 66 being adapted to connect to the second open end 64 of the housing 4 such that the cap opening 68 forms an outlet 8 of the housing.

[0085] Referring to Figure 3, a cross-sectional view of the hybrid filter unit 2 is shown. The nozzle 14 is positioned in the wall 70 of the housing 4, with its inner end 72 located inside the housing 4, and the nozzle body extending laterally with respect to the central axis 5 of the housing 4. More specifically, the nozzle inner end 72 is located inside the mixing chamber 18 defined by the wall structure 16.

[0086] The hybrid filter unit 2 further comprises a filtration structure 74 positioned between the inner wall surface 80 of the housing 4 and the outer wall surface 82 of the wall structure 16. More specifically, the filtration structure 74 is positioned downstream of the device 24 that attracts charged particles in the fluid flow direction between the inlet 6 and the outlet 8. The filtration structure 74 comprises a plurality of filtration elements 78 that are at least partially rounded and have pores. More specifically, the filtration structure 74 includes volcanic pumice. More specifically, the filtration structure 74 includes dry wood fibers and / or activated carbon 76, which are positioned between the volcanic pumice.

[0087] The hybrid filter unit 2 includes a discharge means 84 for discharging by-products generated by the reaction between the fluid and the oxidizing agent. The discharge means 84 defines an opening in the wall 70 of the housing 4 at the bottom surface of the housing 4.

[0088] The arrows in Figure 3 indicate the fluid flow and oxidizer flow injected into the hybrid filter unit 2.

[0089] Figure 4 is a schematic diagram of the hybrid filter unit 2 according to Figure 1, illustrating the hydraulics of the fluid flow in more detail. Note that the inner tip 86 of the inner conical wall 20 is closed by an impermeable wall 88 extending perpendicular to the central axis 21 of the inner conical wall 20. This causes a portion of the incoming fluid flow to be folded back, promoting mixing within the mixing chamber 18. Similarly, the inner tip 90 of the outer conical wall 22 is closed by an impermeable wall 92 extending perpendicular to the central axis 23 of the outer conical wall 22. This creates conditions that further promote mixing within the mixing chamber 18. The blocking of the ends of the conical walls 20 and 22 increases the fluid pressure, thereby compensating for at least some of the pressure loss and generating vortices that contribute to better mixing and longer reaction contact times.

[0090] For example, the air to be treated may be supplied at a flow rate of approximately 1000 L / min, while the oxidizer may be supplied at a flow rate of approximately 50 L / min. Because the airflow is greater than the oxidizer flow, the airflow becomes dominant and can bend the oxidizer flow in the direction of flow toward the tips / outskirts of the conical walls 20 and 22. This interaction between the airflow and the oxidizer flow causes them to mix, and each substance reacts chemically or physically. Examples of physical reactions include charge exchange or adsorption at the surface, or charge generation due to mutual friction. An example of a chemical reaction is the oxidation reaction of the airflow substance due to the presence of the oxidizer in the oxidizer flow.

[0091] For example, if the oxidizing agent concentration is 20 mg / L (ppm), the exposure dose would be 50 × 20 = 1000 mg / min, or 1 g / min, or 60 g / hour. This may be sufficient for disinfecting office air, but for more contaminated applications, the dose needs to be adjusted via the circulation rate (by reducing the fan speed from 1000 L / min, or by increasing the oxidizing agent concentration from 20 mg / L to a higher concentration by improving the efficiency of the oxidizing agent generation process).

[0092] The ability to flexibly and spatially adjust these parameters according to various flow rates and contamination levels is advantageous when there is an independent (external) source of oxidizer. Therefore, all of the aforementioned parameters, such as injection flow rate, oxidizer concentration, and fan speed, can be adjusted as needed.

[0093] Furthermore, a suction fan (not shown) can be connected to the outlet of the housing to draw in the airflow passing through the pumice stone and wood fibers inside the housing.

[0094] Figure 5 is a schematic perspective view of a fluid purification device 102 according to the first embodiment. The fluid purification device 102 comprises a hybrid filter unit 2 as shown in Figure 1 and an oxidant generator 104. The oxidant generator 104 is adapted to ionize an additional fluid in order to obtain an output flow rate of oxidant, where the additional fluid is in the form of air. The device 104 is located separately from the hybrid filter unit 2, and the outlet 106 of the device 104 is operably connected to a nozzle 14 via a tube or hose 108 to supply the oxidant to the hybrid filter unit 2.

[0095] The fluid purification device 102 further includes an air compressor 110 operably connected to the device 104 to supply compressed air to the device 104.

[0096] The oxidizing agent generating device 104 is housed in a casing having a generally cylindrical shape. The oxidizing agent generating device 104 comprises a generally flat rectangular wall 118 and a wall 120 with a generally semicircular cross-section. Wall 120 is connected to the flat rectangular wall 118, defining an internal space between walls 118 and 120. The ionization unit 114 is housed in the internal space between walls 118 and 120.

[0097] Figure 6 is a partial cross-sectional perspective view of the ionization unit 114 of Figure 5. The ionization unit 114 is adapted to discharge compressed air to produce an output flow. The ionization unit 114 comprises an elongated container 121. The container 121 has a rounded cross-sectional shape, more specifically a circular cross-sectional shape. Furthermore, the cross-section of the container 4 is constant along most of the length of the container. Also, both ends of the container 121 in the longitudinal direction have a rounded, more specifically hemispherical shape. The walls of the container 121 define an internal chamber. The container walls are made of glass. Furthermore, an inlet 123 is provided at the first end of the container 121 in the longitudinal direction, and an outlet 125 is provided at the second end in the longitudinal direction. This transports the gas flow from the inlet 123 to the outlet 125.

[0098] Figure 10 is a cross-sectional view of the ionization unit 114 in Figure 6.

[0099] The ionization unit 114 further comprises a first pair of electrodes 122 arranged in the container, facing each other and spaced apart from one another. Each electrode of the first pair of electrodes 122 has an elongated shape with a circular cross-section and a pointed tip. The electrodes are arranged so that their tips face each other.

[0100] According to the laws of physics, when an element is charged, the charged portion accumulates at the sharp edges of that element. Therefore, the charged portion accumulates highly at the sharp edges of electrodes. In other words, the density of the charged portion is very high at the sharp edges, and the electric field becomes strong in that region. Furthermore, a highly charged electrode (positive or negative electrode) has a very high potential relative to the surrounding environment (adjacent to the electrode). The potential difference between the electrode and its adjacent environment / surroundings causes ionization of the material in the environment around each electrode, which can lead to the periodic exchange of electrons / positrons from high-potential areas to low-potential areas and vice versa, potentially generating various discharge phenomena from the electrode. This phenomenon may be similar to that of a Tesla coil.

[0101] Therefore, designing electrodes with sharp tips, particularly those with acute angles of 20 to 35 degrees (preferably 22 degrees, which results in an increase in the number of discharges and an extension of electrode life), provides favorable conditions for discharge generation from the tip surface inclined with respect to the longitudinal direction of the elongated electrode.

[0102] The ionization unit 114 further includes power supplies 124 and 128 for simultaneously charging each electrode of the first electrode pair 122 with the same charge. In this way, a potential difference can be created between each electrode and its environment such that simultaneous discharge occurs from each electrode. Furthermore, during the charging for ionization of the fluid, the fluid is transported in a gaseous state within the container, passing the first electrode pair 122 in the environment of each electrode.

[0103] More specifically, the power supplies 124, 128 comprise two transformers 124, 128 adapted to supply alternating current of a specific frequency to the electrodes. Thus, the power supplies 124, 128 are adapted to supply a voltage to the first electrode pair 122 such that both electrodes become positively charged simultaneously and therefore emit electrons. Furthermore, the container is adapted to transport a gas flowing over the first electrode pair 122, this gas flow can be considered a negatively charged region between the electrodes, which interacts with electrons emitted from the electrodes to form a first discharge structure. More specifically, multiple discharges are ejected from each electrode, ionizing the gas.

[0104] More specifically, each transformer 124, 128 has a primary winding and a secondary winding. Each transformer changes the charge (alternating current) of the electrodes to produce an input voltage of 12 to 220 volts and a frequency of 50 to 60 Hz for each pole (associated with one of the electrodes). * It converts to 7.5kV and a frequency of approximately 20kHz. Therefore, each transformer 124 and 128 is equipped with a frequency converter, and one of the functions of the grounding wire is noise reduction.

[0105] Each transformer 124, 128 is adapted to supply an output voltage of approximately 7.5kV through its respective output terminals. Furthermore, each transformer 124, 128 is adapted to supply an output voltage at a frequency of approximately 20kHz, where the polarity of the electrodes connected to the two output terminals / pole of a single transformer changes very rapidly (every 0.00005 seconds).

[0106] More specifically, each electrode is positioned in an opening in the container wall. More specifically, the container comprises a tubular portion extending transversely to the longitudinal direction of the container. More specifically, the tubular portion extends perpendicular to the longitudinal direction of the container. The tubular portion defines the opening. More specifically, the tubular portion is formed integrally with the container. More specifically, the electrodes are positioned in the tubular portion in an airtight manner to prevent leakage.

[0107] The ionization unit 114 further includes a second electrode pair 126 arranged within the container in the same manner as described above with respect to the first electrode pair 122. The second electrode pair 126 is positioned at a sufficient distance from the first electrode pair 122 in the longitudinal direction of the container. The first electrode pair 122 and the second electrode pair 126 are positioned in a portion of the container where the cross-section is constant, with a distance of approximately 30 mm between adjacent electrode pairs. Power supplies 124 and 128 are adapted to simultaneously charge each electrode of the second electrode pair 126 with the same amount of charge. In this way, a potential difference is created between each electrode and the surrounding environment, causing individual discharges from each electrode. Thus, power supplies 124 and 128 are configured to supply the same voltage to the second electrode pair 126 as well, so that both electrodes are simultaneously positively charged and emit / exchange electrons / positrons.

[0108] This configuration is adapted to synchronize the charging of the first electrode pair 122 and the second electrode pair 126, so that when the first electrode pair 122 is positively charged, the second electrode pair 126 is negatively charged, and vice versa.

[0109] The two transformers 124 and 128 are identical in that they have the same natural frequency. By placing transformers 124 and 128 relatively close to each other, they influence each other during operation according to Hertz's law and the frequency law, so that in a steady state their frequency cycles eventually synchronize. Therefore, they can operate at a permanently synchronized frequency. Thus, this synchronization occurs spontaneously as soon as the transformers are activated. Alternatively, it is possible to provide means to actively control the synchronization, such as placing unidirectional diodes (diodes that synchronize the current direction to the same direction (sine wave or cosine wave)) in the path of each output terminal.

[0110] Therefore, each transformer has two output terminals / poles connected to electrodes for charging the electrodes. When the potential reaches a sufficient amount for discharge, the aforementioned discharge phenomenon occurs. More specifically, the first electrode of the first electrode pair 122 and the first electrode of the second electrode pair 126 are connected to the opposite terminal of the first transformer 124. Furthermore, the first electrode of the first electrode pair 122 and the second electrode of the second electrode pair 126 are connected to the opposite terminal of the second transformer 128.

[0111] Figure 7 is a perspective view of the mounting frame 130, showing the hybrid filter unit 2 and oxidant generator 104 as shown in Figure 5. The oxidant generator 104 and the hybrid filter unit 2 are fixedly connected in parallel to opposing walls of the mounting frame. The mounting frame 130 is equipped with an inlet 132 for air inflow. The inlet 132 is in fluid communication with the inlet 6 of the hybrid filter unit 2. The mounting frame 130 is equipped with an outlet 134 for air outflow. The outlet 134 is in fluid communication with the outlet 8 of the hybrid filter unit 2.

[0112] Figure 8 is a schematic perspective view of the hybrid filter unit 202 according to the second embodiment. For the sake of simplicity, only the main differences from the hybrid filter unit 2 according to the first embodiment will be described. The hybrid filter unit 202 comprises a housing having a rectangular cross-section. The hybrid filter unit 202 further includes a wall structure 216 located within the housing that defines a fluid mixing chamber. The wall structure 216 has a flow penetration area that decreases at least partially in the direction from the inlet 206 to the outlet 208. More specifically, the wall structure 216 comprises a first wall 220 that defines the mixing chamber in the transverse direction of the housing. More specifically, the first wall 220 has a flow penetration area that decreases from the inlet 206 to the outlet 208. More specifically, the first wall 220 comprises two substantially flat rectangular sections, which are arranged in an inclined relationship and intersect at their tips. Furthermore, the first wall 220 comprises two spaced triangular sides connected to the periphery of the two substantially flat, inclined rectangular sections. The wall structure 216 further comprises a second wall 222 having a similar shape to the first wall 220, positioned near the first wall 220, and spaced apart from the first wall 220 in the axial direction of the housing, thereby creating a gap between the first wall 220 and the second wall 222. The wider ends of the first conical wall 220 and the second conical wall 222, respectively, face the entrance 206.

[0113] Figure 9 is a perspective view of the mounting frame, showing the two hybrid filter units 2 and 202, each associated with the oxidant generator 304, in their mounted state. The oxidant generator 304 can be operated according to a principle different from the ionization by discharge described above. For example, the oxidant generator 304 may be equipped with a light source (such as an ultraviolet light source) that irradiates the fluid with ultraviolet light. Furthermore, the oxidant can be produced from various sources, such as being stored in a capsule or being generated in-situ by a reactor or oxidant generator.

[0114] Figure 11 shows an alternative embodiment of ionization unit 204 related to ionization unit 104 shown in Figure 10. For simplicity of explanation, only the main differences from the ionization unit are described. The second electrode pair 126 in ionization unit 104 is replaced here by a light source pair 226 such as an ultraviolet lamp or UV-LED. Therefore, each light source is located in one of the tubular sections of the container.

[0115] Alternatively, ultraviolet light can be replaced by various light sources positioned at different holes, each directed towards an electrode and potentially configured with different polarity configurations to target specific ionization targets within the ionization vessel or chamber. Each electrode is capable of ionizing the surrounding fluid, emitting positrons and / or electrons through a discharge, and also operates in conjunction with the ultraviolet light. This configuration effectively eliminates the conventional heating, temperature fluctuations, and noise typically associated with corona discharge, regardless of whether the power supply is AC or DC. In this embodiment, the configuration is designed to generate a safe high voltage and efficiently target specific ionization elements.

[0116] It should be understood that the present invention is not limited to the embodiments described above and shown in the drawings. Rather, those skilled in the art will recognize that many changes and modifications are possible within the scope of the appended claims.

[0117] In another example, the inner wall structure / polarization unit can have a shape other than a cone. For example, it can be pyramidal.

[0118] Furthermore, according to the embodiment shown in Figure 10, each electrode of the first electrode pair is charged to be either negatively or positively charged simultaneously. This causes a discharge to occur from each electrode due to the potential difference between each electrode and its environment. Thus, multiple discharge structures are formed simultaneously from each electrode of the first electrode pair. Similarly, the second electrode pair is also charged to generate discharges from each electrode. According to another embodiment, the first electrode of the electrode pair is positively charged, and the second electrode of the same pair is negatively charged simultaneously, where a continuous arc structure can be realized between the electrodes of each pair.

Claims

1. Hybrid filter unit (2), - A housing (4) having an inlet (6) for the fluid to be purified to flow in and an outlet (8) for the purified fluid to flow out, - A wall structure (16) disposed inside the housing and defining the fluid mixing chamber (18), the wall structure (16) defining an internal cross-sectional area that decreases at least partially in the direction from the inlet (6) to the outlet (8), - A nozzle (14) arranged to supply an oxidizing agent to the mixing chamber (18), wherein the fluid is exposed to the oxidizing agent as it flows between the inlet and the outlet and can react with the oxidizing agent, - A filtration structure (74) disposed between the inner wall surface of the housing and the outer wall surface of the wall structure, wherein the filtration structure comprises volcanic pumice (78), and the wall structure (16) is at least partially adapted for the flow of the fluid from the mixing chamber (18) to the filtration structure (74) A hybrid filter unit (2) equipped with the following:

2. The hybrid filter unit according to claim 1, wherein the wall structure (16) comprises a first wall (20) and a second wall (22) arranged at intervals from each other, the inner surface of the first wall defines the mixing chamber (18), and the outer surface of the second wall defines the outer wall surface of the wall structure.

3. The hybrid filter unit according to claim 2, wherein at least one of the first wall (20) and the second wall (22) has a broad end (32, 34) open to the mixing chamber and a pointed end (36, 38) opposite to the broad end, and the cross-section of the first wall and / or the second wall is at least partially reduced in the direction from the broad end to the pointed end.

4. The hybrid filter unit according to claim 3, wherein at least one of the broad ends (32, 34) of the first wall (20) and the second wall (22) faces toward the inlet (6) so that the fluid can flow into the mixing chamber through the broad end.

5. The hybrid filter unit according to claim 3 or 4, wherein at least one of the first wall (20) and the second wall (22) is conical in shape, and the base of the conical wall forms the wide end.

6. The hybrid filter unit according to claim 5, wherein the central axis (21) of the first conical wall (20) and / or the central axis (23) of the second conical wall (22) coincide with the central axis (5) of the housing (4).

7. The hybrid filter unit according to any one of claims 3 to 6, wherein the broad end (32, 34) of at least one of the first wall (20) and the second wall (22) has a cross-sectional size and shape substantially the same as, or slightly smaller than, the inner cross-sectional shape and size of the housing (4) for receiving substantially the entire flow rate of the fluid flowing between the inlet (6) and the outlet (8).

8. The aforementioned hybrid filter unit The device (24) for attracting charged particles in the fluid flow is located within the housing, and the device for attracting charged particles comprises a spaced-apart inner conductive element (26) and an outer conductive element (28), the inner conductive element (26) and the outer conductive element (28) are adapted to be connected to a power supply (30) to be reverse-charged so as to attract charged particles in the fluid to one of the conductive elements, the power supply is adapted to supply a low voltage, and the power supply is connected so as to positively charge the inner conductive element. A hybrid filter unit according to any one of claims 1 to 7.

9. The hybrid filter unit according to claim 8, wherein the charged particle attracting device (24) is positioned downstream of the nozzle (14) in the direction of fluid flow between the inlet (6) and the outlet (8).

10. The hybrid filter unit according to claim 2 and any one of claim 8 or 9, wherein at least one of the inner conductive element (26) and the outer conductive element (28) forms one of the first wall (20) and the second wall (22) of the wall structure defining the mixing chamber.

11. The hybrid filter unit according to any one of claims 8 to 10, wherein the inner conductive element (26) is at least partially located inside the outer conductive element (28), and the inner conductive element and the outer conductive element are arranged to collect particles in the space between the inner conductive element and the outer conductive element.

12. The hybrid filter unit according to any one of claims 8 to 11, wherein the outer conductive element (28) is arranged downstream of the inner conductive element (26) in the fluid flow direction.

13. The hybrid filter unit according to any one of claims 8 to 12, wherein the hybrid filter unit (2) comprises an element (44) that provides electrical insulation between the inner conductive element (26) and the outer conductive element (28).

14. The hybrid filter unit according to any one of claims 1 to 13, wherein the housing (4) comprises a first open end (50), the hybrid filter unit (2) comprises a first cap (52) defining an opening, the first cap (52) is fitted to connect to the first open end of the housing such that the cap opening forms the inlet of the housing, and at least one wall of the wall structure is attached to the cap.

15. The hybrid filter unit according to claim 13 or 14, wherein at least one of the inner conductive element (26) and the outer conductive element (28) is detachably attached to the first cap (52), thereby allowing access to the space between the inner conductive element and the outer conductive element for cleaning.

16. The hybrid filter unit according to claim 14 or 15, wherein the first cap (52) forms an electrical insulating element (44) between the inner conductive element (26) and the outer conductive element (28).

17. The hybrid filter unit according to any one of claims 14 to 16, wherein the housing (4) comprises a second open end (64), and the hybrid filter unit comprises a second cap (66) defining an opening, the second cap (66) being adapted to be connected to the second open end of the housing such that the cap opening forms the outlet of the housing.

18. The hybrid filter unit according to any one of claims 1 to 17, wherein the nozzle (14) is positioned on the wall of the housing (4), so that its inner end is located inside the housing, and the nozzle body extends transversely with respect to the central axis (5) of the housing between the inlet and the outlet.

19. The hybrid filter unit according to claim 18, wherein the inner end of the nozzle is positioned inside the mixing chamber (18) defined by the wall structure (16).

20. The hybrid filter unit according to any one of claims 1 to 19, wherein the filtration structure (74) includes dry wood fibers (76) and / or activated carbon provided between volcanic pumice (78).

21. The hybrid filter unit according to any one of claims 1 to 20, wherein the hybrid filter unit (2) comprises means (84) for discharging by-products resulting from the reaction of the fluid and the oxidizing agent.

22. The hybrid filter unit according to any one of claims 1 to 21, wherein the housing (4) is cylindrical, the inlet (6) is provided at a first end of the cylindrical housing in the axial direction, and the outlet (8) is provided at a second end of the cylindrical housing opposite to the first end in the axial direction.

23. The hybrid filter unit according to any one of claims 1 to 23, wherein the housing (4) is circular and cylindrical.

24. A fluid purification device (102) comprising an oxidizing agent generating device (104, 204) and a hybrid filter unit (2) according to any one of claims 1 to 23, wherein the oxidizing agent generating device (104, 204) is arranged separately from the hybrid filter unit, and the outlet (106) of the oxidizing agent generating device is operably connected to the nozzle (14) for supplying the oxidizing agent to the mixing chamber of the hybrid filter unit.

25. The fluid purification apparatus according to claim 24, wherein the oxidizing agent generating apparatus (104, 204) is adapted to generate the oxidizing agent by exposing a further fluid to a discharge structure and ionizing it.

26. The fluid purification apparatus according to claim 25, wherein the oxidizing agent generating apparatus (104, 204) comprises a pair of electrodes (122) that face each other and are spaced apart from each other, and the oxidizing agent generating apparatus (104, 204) comprises a power supply adapted to generate a discharge that forms a discharge structure by charging the first pair of electrodes.

27. The fluid purification device according to any one of claims 24 to 26, wherein the fluid purification device (102) comprises an external air source (110) located separately from the oxidizing agent generating device (104), the external air source (110) is arranged to receive air from outdoors, the external air source (110) is operably connected to the inlets of the oxidizing agent generating devices (104, 204), and the received outdoor air is supplied to the oxidizing agent generating devices (104, 204) to reduce the risks associated with the use of contaminated indoor air.

28. The fluid purification device according to any one of claims 24 to 27, wherein the fluid purification device (102) includes a mounting frame (130), and the oxidizing agent generators (104, 204) and the hybrid filter unit (2) are fixedly connected in parallel to the mounting frame.

29. The fluid purification apparatus according to any one of claims 24 to 28, wherein the oxidizing agent generating apparatus (204) comprises at least one ultraviolet light source for generating the oxidizing agent by exposing a further fluid to ultraviolet irradiation.

30. The fluid purification apparatus according to claim 29, wherein the oxidizing agent generating apparatus (204) comprises a pair of ultraviolet light sources.

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