Active field polarized media air purification device

Abstract

A gas purification device (1) comprising a first electrode (31) and a second electrode (32), a first filter medium (20) having a first side (21) and a second side (22), wherein the first side (21) faces the first electrode (31) and the second side (22) faces the second electrode (32), if a corona discharge electrode (30) is located at a distance from the first electrode (21), wherein the first electrode (21) is located between the corona discharge electrode (30) and the first filter medium (20), then active field polarized medium air purification is allowed to be combined with corona discharge air purification.

Description

Technical Field

[0001] This invention relates to a cabin air filtration system, or more generally, to an active field polarized medium gas purification device comprising a dielectric filter medium located between a first electrode and a second electrode. Background Technology

[0002] The cabin air filtration system removes pollutants from the ambient air and delivers purified air to the interior of the vehicle's passenger cabin. Essentially the same technology can be used in other areas, such as building ventilation.

[0003] Generally, "filtration" refers to the removal of particulate matter from an airflow by using a filter medium—a sieve—to sieve the airflow. Purifying air solely based on sieving requires maintaining a balance between the size of the smallest particle trapped in the sieve and the pressure drop across the sieving element—the filter medium. Removing particulate matter from an airflow through filtration appears to be the result of many processes, including interception, diffusion, and inertial impaction. It has been proposed to improve particle removal from the airflow using electrostatic forces with electret filters. However, the particle removal of these electret filters seems to decrease with increasing particle deposition on the fibers. To address this drawback, it has been proposed to apply an external electric field to the filter medium by positioning it as a dielectric between two air-permeable electrodes. (See, for example, Frank Jordan, ...) Untersuchungen zum Partikelabscheideverhalten submikroner Partikel in Faserfiltern im elektrischen Feld (Doctoral dissertation, University of Duisburg, Germany, 2001) Using this technology, even uncharged submicron particles can be effectively removed from the airflow. This technology is called Active Field Polarized Medium (AFPM) gas purification, which differs from electrostatic precipitation filters and passive electrostatic filters (electret filters).

[0004] These active field-polarized medium gas purifiers typically have a gas filter housing and a high-voltage (HV) power supply. The gas filter housing has a receiving section for the gas filter, and the HV power supply is connected to the electrodes of the gas filter. Once the gas filter reaches the end of its service life, it is removed from the housing and replaced with another gas filter. Therefore, the housing has at least two electrical contacts for removable contact with corresponding electrical contacts of the gas filter, thereby enabling electrical connection between the gas filter and the HV power supply.

[0005] US5,474,599A, EP3488933A1, EP2774628A1, and US2008 / 0190772A each disclose an air purifier having an upstream air ionizer having a set of discharge electrodes and a set of ground electrodes located between the discharge electrodes. Downstream of the air ionizer is a filter medium located between two other electrodes.

[0006] US5,549,735 discloses an active field-polarized medium gas purifier having two equally charged electrodes located upstream of a filter medium and another electrode located downstream of the filter medium.

[0007] US2007 / 0199450A1 discloses an air filter having two air-permeable ground electrodes and an air-permeable HV electrode located between the two ground electrodes. A dielectric filter medium exists between each ground electrode and the HV electrode. The HV field between the electrodes can polarize both the particles and the fibers of the dielectric.

[0008] While these active field-polarized dielectric air purifiers allow for the effective removal of even submicron-sized particles, air ionization can sterilize the air and remove odors at the molecular scale. Air ionization requires approximately 5 kV—depending on the electrode distance—and typically 10 μA to 10 mA of current—depending on the size of the air ionizer. Corona discharge gas purifiers are examples of air ionizers. Industrial-scale gas ionizers may have correspondingly larger currents.

[0009] WO2020 / 263171A1 proposes using the conductive filter medium of a filter element as the electrode of a gas ionizer. Multiple insulating supports for the emitting electrode are attached to the upstream side of the filter element, the emitting electrode having a tip pointing upstream. Approximately 7kV to 10kV is supplied to the emitting electrode while the filter medium is grounded. The voltage between the filter medium and the emitting electrode causes corona discharge, which facilitates the removal of particles from the gas flow through the filter element. The power supply is directly attached to the filter element and removed with it when the filter element is replaced. The power supply can then be removed from the used filter element and mechanically attached to the support structure of a new filter element. Furthermore, the output terminal of the power supply is connected to the emitting electrode of the gas ionizer via a cable. The ground electrode is embedded in the center of the filter medium and can be, for example, an activated carbon layer or a carbon fiber layer of the filter medium. This ground electrode layer is contacted by passing a needle through the stacked filter medium. The needle is connected to the grounding connector of the power supply via a wire.

[0010] US2003 / 0005824A1 relates to dust collectors and proposes an alternative to dust removal via corona discharge: According to US2003 / 0005824A1, the dust collector has… Ion release device for releasing ions without causing corona discharge. "Set" And a dust collection zone, located downstream of the gas flow through the dust collector. By ionizing air molecules without corona discharge, both the power consumption of the dust collector and ozone generation are reduced. Summary of the Invention

[0011] The problem to be solved by the present invention is to provide a gas purification device that effectively combines gas purification due to corona discharge and active field polarization medium gas purification.

[0012] The solution to this problem is described below. Further improvements to the invention are also discussed below.

[0013] A preferred example of a gas purification device includes at least a first filter medium. Preferably, the first filter medium is dielectric and / or non-conductive. The first filter medium may comprise at least one layer of laminated filter paper or any other filter medium, or be composed of at least one layer of laminated filter paper or any other filter medium. For example, the first filter medium may comprise at least one fibrous filter medium and / or a porous filter medium, or be composed of at least one fibrous filter medium and / or a porous filter medium. The first filter medium has a first side and a second side.

[0014] For simplicity, we assume that during operation, the gas flow enters the filter medium at a first side, flows through the first filter medium, and exits the filter medium at a second side. In practice, the first and second sides of the first filter medium are usually, but not necessarily, oriented in opposite directions. In many examples, the first filter medium forms a filter element or is a component of a filter element.

[0015] The gas purification device may further include a first electrode and a second electrode. A first filter medium may be located on a first side, and a second filter medium may be located on a second side. Therefore, the first side faces the first electrode, and the second side faces the second electrode. In other words, the first filter medium is located between the first electrode and the second electrode. Referring to a preferred flow direction, the first electrode is located upstream of the first filter medium, and the first filter medium is located upstream of the second electrode.

[0016] The corona discharge electrode (also referred to as the corona electrode) can be located at a distance from the first electrode, which is situated between the corona discharge electrode and the first filter medium. This means that the corona discharge electrode can be located upstream of the first electrode. In other words, at least one corona discharge electrode can be located on the first side of the filter medium, spaced apart from it, with the first electrode positioned between the first filter medium and the corona discharge electrode, thereby allowing a corona discharge current between the corona discharge electrode and the first electrode. Assuming the gas flow direction described above through the gas filtration device, the corona discharge electrode can therefore be considered to be located upstream of the first filter medium. This location is not mandatory but is preferred because it allows ozone generated by the corona discharge process to be removed through the filter medium.

[0017] A corona discharge electrode may include or consist of at least one emitter electrode. In practice, multiple emitter electrodes are typically used, but for smaller filters, a single emitter electrode may be sufficient. Typically, a corona discharge electrode has one or more tips. Examples of corona discharge electrodes are already known from other published subjects, such as WO2020 / 263171A which has been cited, or PCT application PCT / EP2022 / 071714 which is not previously published, both of which are incorporated herein by reference as fully set forth herein, or are at least strongly recommended to the reader.

[0018] In summary, three electrodes are sufficient: a corona discharge electrode, a first electrode, and a second electrode. Therefore, in a preferred embodiment, the gas purification device has only these three electrodes to achieve the two purposes of establishing a corona discharge current and creating an electric field on the filter medium; that is, there is no fourth electrode, at least not in this context. Thus, the gas purification device allows the first electrode to be electrically connected to a first output port of a power supply, wherein the first output port of the power supply provides a first potential. U 1. The corona discharge electrode is electrically connected to the second output port of the power supply, wherein the second output port of the power supply provides the corona potential. U c The corresponding potential difference U c -U 1 is referred to in this article as Corona voltage Furthermore, to obtain active field-polarized medium air purification as needed, the first electrode can also be connected to the first output port of the voltage source, and the second electrode can be electrically connected to the second output terminal of the voltage source, which provides a second potential. U 2. Therefore, the potential difference U 1- U2 can be referred to as the AFPM voltage. By applying the AFPM voltage between the first and second electrodes, an external electric field is applied to the filter medium, which also helps to purify the gas flowing through the filter element; this is called Active Field Polarized Medium Gas Purification (AFPMGC, see above). Therefore, in operation, a corona discharge current can be established between the corona discharge electrode and the first electrode, and an AFPM voltage can be applied between the first and second electrodes to provide an electric field for AFPM. Thus, the gas flow through the gas purification device can be purified by corona discharge and by AFPM, requiring only three electrodes. According to the prior art, the fourth electrode can be omitted.

[0019] the term power supply and voltage source The device was chosen solely to distinguish between the two different voltage supply devices, taking into account the following: due to corona discharge, current flows between the corona discharge electrode and the first electrode, and therefore the power source must indeed supply power. Ideally, once the capacitor formed by the first electrode, the first filter element, and the second electrode is charged, the voltage source can be disconnected and therefore does not supply power. However, in the real world, the voltage source compensates for (unintended) voltage loss and therefore essentially does not supply power.

[0020] The gas purification device described above thus allows the first electrode to be used for two purposes (simultaneously), namely, as an electrode in a corona discharge circuit and as an electrode in an actively field-polarized filter medium. This dual use of the first electrode offers numerous advantages. For example, it allows for a very compact gas purification device, freeing up space to add the device to the passenger compartment without increasing the vehicle's volume. In many cases, vehicles with passenger compartments have cabin air purification devices under their hoods. The size of the cabin air purification device imposes constraints on the vehicle's aerodynamics. Due to the size reduction provided by the present invention, these constraints are eliminated, and an aerodynamically improved hood design can be achieved. Therefore, the present invention helps reduce vehicle energy consumption. Alternatively, depending on the circumstances, the size can remain unchanged but the surface area of ​​the filter medium can be increased, which allows for an increase in the lifespan of the filter medium or filter material.

[0021] For example, the first output terminal of the power supply and the first output terminal of the voltage source can be electrically connected to the first electrode. The corresponding voltage level of the first electrode ( U 1) Can be considered as the geopotential (this geopotential can, but is not required, be the same as the geopotential defined by an uncharged electrode). The potential of the corona discharge electrode (measured in volts). U c The potential of the second electrode U 2 can both be higher than the first potential. U1 or both are below the first potential U 1, or the second potential U 2 can be higher than the ground potential, while the potential of the corona discharge electrode is higher. U c Below U 1. In another example, the second potential U 2 can be lower than the first potential U 1. The potential of the corona discharge electrode U c Higher than the first potential U 1. Preferably, the potential of the second electrode U 2. Potential of the corona discharge electrode U c Potential relative to the first electrode U 1. At potentials of opposite polarity. In a preferred example, the corona discharge electrode is grounded ( U c =0). In this case, there is no high voltage at the inlet of the gas purification device that could harm people or cause other problems. In another example, the first electrode can be grounded. In practice, this means that the first voltage source and the second voltage source share a common ground terminal, making the design of the power supply and voltage source particularly simple.

[0022] The corona discharge current implies the existence of a gap or void between the corona discharge electrode and the first electrode. During operation, the gap is filled with the gas to be purified. For the sake of linguistic distinction from other gaps, we refer to the gap between the corona discharge electrode and the first electrode as the "corona gap." Isolating spacers or other types of support structures may be present, mechanically supporting the corona discharge electrode and the first electrode relative to each other, thus defining the corona gap. However, a gas flow path typically exists between the corona discharge electrode and the first electrode, and from the first electrode through the first filter medium.

[0023] Another gap (referred to as the first gap) may exist between the first electrode and the first filter element, but this is not necessary. The first electrode may also be directly attached to the first side of the first filter medium and / or penetrate into the first filter medium.

[0024] The first electrode may be gas-permeable to allow gas to flow through the first electrode, through a selectable first gap, and into the first filter medium through a first side of the first filter medium.

[0025] In a preferred embodiment, the first electrode and / or the second electrode are each a conductive sheet or conductive layer that covers a first side and / or a second side of the first filter medium, respectively. As is apparent, in this case, the layer and / or sheet should correspondingly be breathable (or cover only a portion of the respective side of the first filter medium). Preferably, at least one of the first electrode and the second electrode comprises or includes a carbon filter layer.

[0026] Particularly preferably, the second electrode comprises or is composed of a carbon filter layer, while the first electrode is made of a material having a lower resistivity than carbon. In any case, the carbon filter layer preferably comprises or includes activated carbon. This is because the carbon layer is conductive (and therefore can be used as an electrode), and simultaneously contains volatile organic compounds or mercury (Hg) and ozone (…). O 3) The carbon layer is a highly efficient adsorbent, thus also helping to reduce costs. Ozone is generated by corona air purification and must be removed from the airflow before releasing purified air to avoid human or animal exposure to increased ozone levels. Using a carbon layer as the first and / or second electrode thus avoids the use of metal electrodes, which would make the disposal of gas filtration devices more expensive because the metal needs to be recycled. Metal-free filter cartridges with a first filter medium and at least one carbon layer can be disposed of with conventional municipal waste, primarily through incineration or landfill.

[0027] As already explained, at least one of the first electrode and / or the second electrode may be attached to the first filter medium and itself serve as a filter layer, such as the carbon layer already discussed.

[0028] For example, the first electrode and / or the second electrode may be a filter layer laminated to the first filter medium. Therefore, while reducing the volume and weight of the gas purification device, filtration characteristics can be enhanced, allowing for vehicle optimization as described above, and also reducing manufacturing costs. As is apparent, the first and second electrodes are preferably at least substantially parallel to each other and / or have at least a substantially constant distance between them (e.g., constant within at least ±15%, ±10%, ±5%, ±2.5%, ±1% of the average distance). The second filter element may be located downstream of the first filter layer, between the second electrode and the second electrode on the second side of the first filter element. In an example, the filter medium may be a pleated filter medium. In a preferred example, at least one of the first and second electrodes is first applied to an unpleated filter medium, and subsequently, the filter medium having at least one of the first and second electrodes is pleated. Preferably, both electrodes are applied to the filter medium prior to the pleating step.

[0029] Alternatively or additionally, the second or third filter element may be located downstream of the second electrode, where "downstream" means on the side of the second electrode opposite to the first filter element (assuming the filter elements are arranged in series in a straight gas channel).

[0030] Alternatively or additionally, the second, third, or fourth filter element may be located upstream of the corona discharge electrode, wherein "upstream" means on the side of the corona discharge electrode opposite to the first electrode.

[0031] Note that the filter media may, but is not required to, include a single layer of a single filter material. The filter media may also be, or include, multiple layers of the same or different filter materials. Attached Figure Description

[0032] In the following description, the invention will be illustrated by way of example with reference to the accompanying drawings, without limiting the overall inventive concept.

[0033] Figure 1 A simplified cross-sectional view of a gas filtration device is shown. Detailed Implementation

[0034] The gas filtration device 1 includes a first filter medium 20. The first filter medium 20 can be housed in a filter housing 10. The first filter medium 20 has a first side 21 and a second side 22, and the first filter medium 20 is at least substantially non-conductive. In a preferred embodiment, the first filter medium is a dielectric.

[0035] During operation of the gas filtration device 1, the preferred gas flow direction is indicated by arrow 2. Therefore, the first side 21 can be considered the upstream side, and the second side 22 can be considered the downstream side of the filter element. In the depicted example, the filter element 20 has a box-like shape, but in a preferred example, the filter element is or includes a pleated filter medium, such as some fabric filter or paper filter.

[0036] A first electrode 31 may be located at or on a first side 21 of the first filter medium 20. A second electrode 32 may be located at or on a second side 22 of the first filter medium 20. As in the illustrated example, the first filter medium 20 may be sandwiched between the first electrode 31 and the second electrode 32. Furthermore, the first electrode 31 and the second electrode 32 may respectively span or cover at least substantially the entire first side 21 or the entire second side 22. At least substantially the entire first side 21 or the second side 22 should be understood to span or cover at least one of 85%, 90%, 95%, 97.5%, 99%, or 100% of the respective surface. The first electrode 31 and the second electrode 32 are preferably made of a breathable material and have through holes that allow the illustrated gas flow 2 to pass through.

[0037] As illustrated in the example, the second electrode 32 may include an activated carbon layer.

[0038] The first electrode is upstream of the corona discharge electrode 30. During operation, a corona discharge occurs in the gas flow indicated by arrow 2, and a corona discharge current flows between the corona discharge electrode 30 and the first electrode 31 (indicated by the dashed curve extending from the corona discharge electrode 30 to the first electrode 31).

[0039] It should be noted that other filter media and shapes can also be used. Here we chose a box shape simply to facilitate visualization of the general relative positions of the first electrode 31 and the second electrode 32 with respect to the first filter element 20 and with respect to the corona discharge electrode 30.

[0040] like Figure 1 As shown, the first electrode 31 can be electrically connected to the first output port 41 of the power supply 40 and the first output 51 of the voltage source 50. The corona discharge electrode 30 can be electrically connected to the second output port 42 of the power supply 40, and the second electrode 32 can be electrically connected to the second output port 52 of the voltage source 50.

[0041] There are two preferred operating modes: In the first operating mode, the corona discharge electrode 30 is grounded (indicated by the dashed line). In the second operating mode, the first electrode 31 is grounded. However, the ground potential can also be the potential of the second electrode or any other potential. The power supply 40 and voltage source 50 are depicted as separate devices. Of course, they can be integrated into a single device.

[0042] In a preferred embodiment, the first electrode 31 is positively charged relative to the corona discharge electrode 30. U c < U 1). Furthermore, preferably, the second potential U 2, that is, the potential of the second electrode 22 U 2. Preferably, the potential is lower than the first potential. U 1. In other words, preferably, U c <U 1 and / or U 2 <U 1.

[0043] List of reference numerals

[0044] 1. Gas purification device

[0045] 2. Preferred / hypothetical flow direction

[0046] 10 Housing / Channel

[0047] 20 First filter media

[0048] 21 The first side of the first filter medium

[0049] 22 The second side of the first filter medium

[0050] 30 Corona discharge electrode

[0051] 31 First Electrode

[0052] 32 Second electrode

[0053] 40 power supply

[0054] 41. First output port of the power supply

[0055] 42 Corona discharge port / First output port of the power supply

[0056] 50Voltage Source

[0057] 51 Voltage source first output port

[0058] 52. First output port of the voltage source

[0059] U 1. First potential (potential at the first electrode)

[0060] U 2. Second potential (potential at the second electrode)

[0061] U c Corona potential (potential at the corona discharge electrode)

[0062] U c -U 1. Corona voltage (potential difference between the first electrode and the corona discharge electrode)

[0063] U 2 -U 1. Active polarization dielectric voltage (potential difference between the first and second electrodes)

Claims

1. An active field-polarized medium gas purification device (1), comprising at least: - First electrode (31) and second electrode (32). - Filter medium (20) having a first side (21) and a second side (22), wherein the first side (21) faces the first electrode (31) and the second side (22) faces the second electrode (32). - A corona discharge electrode (30) is located at a distance from the first electrode (31), wherein the first electrode (31) is located between the corona discharge electrode (30) and the filter medium (20). - Power supply (40) The active field polarization medium gas purification device (1) is configured to be electrically connected: - The first electrode (31) is connected to the first output port (41) of the power supply (40), wherein the first output port (41) of the power supply provides a first potential U1, and - The corona discharge electrode (30) is connected to the second output port (42) of the power supply (40), wherein the second output port of the power supply provides a corona potential U. c The corresponding potential difference U c -U1 is called the corona voltage, and a potential difference U1-U2 is applied between the first electrode (31) and the second electrode (32) to obtain active field polarization medium air purification, where U2 is the potential of the second electrode (32). Its features are, - The active field polarized medium gas purification device has no more than three electrodes (30, 31, 32), and the active field polarized medium gas purification device is configured to use the first electrode (31) as both an electrode in the corona discharge circuit and an electrode in the active field polarized filter medium.

2. The active field polarization medium gas purification device (1) according to claim 1. Its features are, The first electrode (31) is electrically connected to the first output port (41) of the power supply (40) and the first output port (51) of the voltage source (50), and / or The second electrode (32) is connected to the second output port (52) of the voltage source (50), and / or The corona discharge electrode (30) is electrically connected to the second output port (42) of the power supply (40).

3. The active field polarization medium gas purification device (1) according to claim 1 or 2. Its features are, The second electrode (32) and the corona discharge electrode (30) are at potentials opposite in sign to those of the first electrode (31).

4. The active field polarization medium gas purification device (1) according to claim 1 or 2. Its features are, The first electrode (31) and / or the second electrode (32) are attached to the filter medium (20).

5. The active field polarization medium gas purification device (1) according to claim 1 or 2. Its features are, The first electrode (31) and / or the second electrode (32) are filter layers laminated onto the filter medium (20).

6. The active field polarization medium gas purification device (1) according to claim 1 or 2. Its features are, The corona discharge electrode (30) or the second electrode (32) is grounded.

7. The active field polarization medium gas purification device (1) according to claim 1 or 2. Its features are, The corona discharge electrode (30) and the second electrode (32) are at different potentials.

8. A method of using an active field polarized medium gas purification device, wherein the active field polarized medium gas purification device includes a filter medium (20) and only three electrodes, namely a first electrode (31), a second electrode (32), and a corona discharge electrode (30), wherein the filter medium (20) has a first side (21) and a second side (22), wherein the first side (21) faces the first electrode (31), and the second side (22) faces the second electrode (32), and the corona discharge electrode (30) is located at a distance from the first electrode (31), wherein the first electrode (31) is located between the corona discharge electrode (30) and the filter medium (20). The method of use includes: pass - Connect the first electrode (31) electrically to the first output port (41) of the power supply (40), and connect the corona discharge electrode (30) electrically to the second output port (42) of the power supply (40), wherein the first output port (41) of the power supply (40) provides a first potential U1, and the second output port (42) of the power supply (40) provides a corona potential U. c And the potential difference U c -U1 is the corona voltage, and through - Connect the first electrode (31) electrically to the first output port (51) of the voltage source (50), and connect the second electrode (32) electrically to the second output port (52) of the voltage source (50) to provide a second potential U2 as needed, so as to obtain active field polarization medium air purification by the external electric field generated on the filter medium. The first electrode (31) is used for two purposes simultaneously: as an electrode in a corona discharge circuit and as an electrode in an active field polarization filter medium.

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