Air purification

Abstract

Use of charging air contaminants by a plasma generated in ambient air by a plasma generating unit (1100, 2100, 3100, 4100, 8100, 9100) in order to provide charged air contaminants for subsequent collection in a collection unit (1100, 2100, 3100, 4100, 8100, 9100). A method of treating ambient air using the air purification system (10, 800) to reduce the concentration of air contaminants therein, an air purification system (10, 800) and an air purification apparatus (900) for use in the method are also described.

Description

Background Technology

[0001] Air pollution is becoming an increasingly serious problem, and many air pollutants are known or suspected to be harmful to human health. The potential negative effects of air pollutants depend on the type and concentration of the pollutants, as well as the length of time exposed to polluted air. For example, high levels of air pollution can lead to immediate health problems, such as the worsening of cardiovascular and respiratory diseases, while long-term exposure to polluted air can have permanent health effects, such as lung volume loss and reduced lung function, and the development of diseases such as asthma, bronchitis, emphysema, and possible cancer.

[0002] Many people have recognized the benefits of minimizing their exposure to these pollutants and have used air purification systems. These systems are used for air treatment, removing airborne particles, including pollutants, from the air. Known examples of air purifiers use particulate filters that physically capture airborne particles through size-based barrier structures, where high-efficiency particulate air (HEPA) filters remove at least 99.97% of particles with a size of 0.3 micrometers. Other known examples of air purifiers ionize the air and generate negatively charged airborne particles, thereby allowing for improved filtration of particles in the air through electrostatic attraction.

[0003] The negative impacts of gaseous pollutants (such as VOCs) on human health in indoor environments are also known. Many indoor pollutants found in residential environments are organic chemicals and span a wide range of functional groups, sizes, and potential chemical properties. These can be classified as volatile organic compounds (VOCs) and volatile inorganic compounds (VICs). VOCs that humans are typically exposed to in indoor environments include alcohols, aldehydes, aromatic compounds, ketones, alkanes, and alkenes.

[0004] Various technologies for removing VOCs from the air have been studied, such as adsorption, catalytic thermal oxidation, cold plasma, and photocatalysis.

[0005] Ultimately, the goal is to improve the performance of air purifiers and ensure the rapid and effective removal of solid, liquid, and gaseous air pollutants from the air. Summary of the Invention

[0006] The drawback of known air purification systems that use mechanical filter media to remove solid and liquid air pollutants from ambient air is that the higher the efficiency of air pollutant removal, the greater the pressure drop of the entire system, which makes the system more energy-intensive and expensive for a given ambient air treatment rate.

[0007] Therefore, in a first aspect, an air purification system for purifying ambient air is provided, the air purification system comprising:

[0008] A plasma generation unit is configured to generate plasma in ambient air to charge air pollutants therein, thereby providing charged air pollutants; and

[0009] A collection unit is configured to collect charged air pollutants by electrostatic attraction between at least a portion of the collection unit and charged air pollutants.

[0010] By providing an air purification system in which a collection unit is configured to collect air pollutants by electrostatic attraction between at least a portion of the collection unit and the air pollutants, the pressure drop of the entire collection unit can be reduced to that achievable with the same filtration efficiency by a purely mechanical filtration system. From an alternative perspective, the filtration efficiency is improved for a given pressure drop compared to a purely mechanical filtration system. By utilizing a plasma generation unit to generate charged air pollutants for collection by the collection unit, an ion generator can be omitted from the air purification system, thus reducing the number of ozone molecules generated by the air purification system compared to using an ion generator. Therefore, the likelihood of the ozone concentration in the ambient air treated by the system exceeding the WHO ozone guideline values ​​is reduced. The WHO ozone guideline values ​​are a maximum daily value of 100 μg / m³ (51 ppb) over 8 hours and an average of 60 μg / m³ (31 ppb) as the time-weighted average of the maximum daily values ​​over 8 hours over six months during the peak season for O3 concentration (World Health Organization (2021). WHO Global Air Quality Guidelines: Particulate Matter (PM2.5 and PM10), Ozone, Nitrogen Dioxide, Sulfur Dioxide and Carbon Monoxide: Executive Summary). In addition, VOCs contained in ambient air can be decomposed by reactive substances in the plasma generated by the plasma generation unit, thereby reducing the concentration of VOCs in ambient air and enhancing the removal of solid and / or liquid phase air pollutants.

[0011] Electrostatic attraction can include ion-dipole forces or ion-ion forces. This does not mean that electrostatic attraction includes ion-induced dipole forces.

[0012] Charged air pollutants generated by the plasma generation unit and collected by the collection unit may include solid and / or liquid air pollutants. Particulate air pollutants present in the ambient air within the plasma generation unit to be charged may include solid and / or liquid particles having an aerodynamic diameter of at least 0.1 micrometers.

[0013] Particulate air pollutants present in the ambient air of the plasma generation unit to be charged may include solid and / or liquid particles having an aerodynamic diameter of at least 0.2 micrometers, at least 0.3 micrometers, at least 0.4 micrometers, or at least 0.5 micrometers.

[0014] Ambient air may contain one or more VOCs. The plasma generation unit can be configured to decompose one or more VOCs contained in the ambient air, thereby forming VOC decomposition products and plasma byproducts (e.g., O3 and / or NO). X ).

[0015] The system and / or collection unit may not include a HEPA filter. By using a plasma generation unit to generate charged air pollutants and using a collection unit configured to collect the charged air pollutants by electrostatic attraction, solid and liquid air pollutants in the ambient air flowing through the system can be adequately removed without the use of a HEPA filter, thereby reducing the pressure drop across the system and / or collection unit compared to the presence of a HEPA filter in the system and / or collection unit.

[0016] The plasma generation unit can be configured not to generate ozone. This can help reduce the system's users' exposure to ozone, which is harmful to humans at high concentrations (see the WHO exposure guidelines above).

[0017] This plasma generation unit can be configured to generate micro-plasma. As a result of the lower voltage (typically about 1 kV) and smaller discharge gap (typically <1 mm) used to generate micro-plasma compared to larger plasma generation units, NO is formed through the plasma generation unit less frequently than with plasma generation units that generate larger plasma. X The rate of O3 decreases.

[0018] A microplasma can be defined as a plasma having a discharge gap of less than or equal to (about) 1 mm and / or a plasma voltage of about 1 kV (i.e., the voltage required to generate plasma). Optionally, the discharge gap of the microplasma can be greater than or equal to 0.01 mm. Optionally, the discharge gap of the microplasma can be less than or equal to 0.5 mm, less than or equal to 0.25 mm, or less than or equal to 0.15 mm. Optionally, the discharge gap of the microplasma can be greater than or equal to 0.05 mm, greater than or equal to 0.09 mm, greater than or equal to 0.11 mm, greater than or equal to 0.20 mm, or greater than or equal to 0.4 mm. Optionally, a microplasma can be defined as a plasma having a plasma voltage greater than or equal to 0.3 kV. The plasma voltage can be less than or equal to 1.9 kV. The plasma voltage can be greater than or equal to 0.8 kV. The plasma voltage can be less than or equal to 1.0 kV. The plasma voltage can be greater than or equal to 0.88 kV. The plasma voltage can be less than or equal to 0.92 kV.

[0019] The plasma generation unit may include multiple electrode components. The discharge gap can be measured between the opposing and adjacent surfaces of two adjacent electrode components. The plasma voltage can be the potential difference between two adjacent electrode components.

[0020] The plasma generation unit can be a dielectric barrier discharge (DBD) plasma generation unit. This facilitates the generation of plasma at voltages lower than typical (approximately 1 kV) and within small discharge gaps (<1 mm) with low free electron energies. The generation of high-energy free electrons increases the likelihood of producing various reactive substances within the plasma generation unit, which in turn leads to NO. X And the formation of O3. Therefore, compared to the case where the plasma generation unit is not a micro-plasma DBD unit, when using plasma to treat ambient air, the micro-plasma DBD plasma generation unit has the advantage of reducing NO. X The potential for forming with O3.

[0021] When the plasma generation unit is a DBD plasma generation unit, the DBD plasma generation unit may include: a first electrode member comprising a conductive core and a dielectric coating; and a second electrode member disposed relative to the first electrode member so as to generate plasma between the first and second electrode members when a plasma generation voltage is applied between the first and second electrode members. In this way, during use, VOCs in the ambient air within the plasma generation unit can be decomposed to form VOC decomposition products, and plasma byproducts can also be formed. Compared to conventional plasma generation units, this micro-plasma generation unit can effectively decompose VOCs in the ambient air while limiting the amount of plasma byproducts and partially oxidized VOCs released by the plasma generation unit.

[0022] The dielectric coating may include a catalyst that catalyzes the decomposition of one or more of the following: VOCs; VOC decomposition products; and plasma byproducts. This allows for the removal of air pollutants from the airflow passing through the system via plasma decomposition, catalytic decomposition, and electrostatic filtration, thereby improving the efficiency of the air purification system compared to systems relying solely on one of these mechanisms. Furthermore, compared to conventional plasma generation units, this plasma generation unit is capable of effectively decomposing VOCs in ambient air while limiting the amount of plasma byproducts and partially oxidized VOCs released by the plasma generation unit. The dielectric coating may include a dielectric material that is itself a catalyst (e.g., MnO2, Al2O3, CeO2, SiO2, and TiO2), and / or a catalyst (e.g., a noble metal) may be disposed (e.g., impregnated) on the dielectric material of the dielectric coating.

[0023] The catalyst contained within the dielectric coating may include one or more of the following: metal oxides, mixed metal oxides, noble metals, noble metal-metal oxide composites, and noble metal-mixed metal oxide composites. This allows the composition of the catalyst within the dielectric coating to be suited to the quantity and / or type of VOCs to be decomposed contained in ambient air and / or the quantity and / or type of plasma byproducts generated within the plasma generation unit.

[0024] The catalyst may contain one or more of the following: Ag, Pt, Pd, Rh, Ni, Cu, Mo, Co, Mg, and Ti. Catalysts containing one or more of the above elements can effectively catalyze the decomposition of one or more of VOCs, VOC decomposition products, and plasma byproducts.

[0025] The dielectric coating may include one or more metal oxides, optionally including one or more of MnO2, Al2O3, CeO2, SiO2, and TiO2. Alternatively, the dielectric coating of the electrode component may include activated carbon or zeolite. This material has a high surface area and can also act as a catalyst in the presence of plasma. Noble metal catalysts, such as one or more of Au, Ag, Tu, Rh, Pd, and Pt, may be impregnated in the dielectric layer (e.g., a metal oxide coating).

[0026] The first and second electrodes can be arranged upstream and downstream of each other relative to the gas flow path through the plasma generation unit. A plasma generation unit with this geometry is capable of generating plasma within the unit for a specified residence time, and thus catalyzing a range of compounds within the plasma.

[0027] The second electrode component of the first aspect may include a conductive core and a dielectric coating. Both electrodes having a conductive core and a dielectric coating structure reduce the likelihood of arcing between the electrode components, thus reducing the likelihood of forming a large number of plasma arc byproducts compared to the second electrode component not having a dielectric coating.

[0028] The dielectric coating of the second electrode component may also include a catalyst that catalyzes the decomposition of one or more of the following: VOCs; VOC decomposition products; and plasma byproducts. This provides a larger catalyst surface area for catalyzing the decomposition of these compounds compared to the second electrode component having no catalyst provided on the dielectric coating. The dielectric coating may include a dielectric material that is itself a catalyst (e.g., MnO2, Al2O3, CeO2, SiO2, and TiO2), and / or a catalyst (e.g., a noble metal) may be disposed on (e.g., impregnated) the dielectric material of the dielectric coating.

[0029] The dielectric coating of the first electrode component and / or the dielectric coating of the second electrode component may include a first catalyst and a second catalyst. The presence of two catalysts on the electrode components allows each catalyst to more specifically catalyze the decomposition of a certain compound without unduly impairing the catalytic activity of other compounds within the plasma generation unit.

[0030] Alternatively, when both the first and second electrode components include a dielectric coating containing a catalyst, the dielectric coating of the first electrode component may include a first catalyst, and the dielectric coating of the second electrode may include a second catalyst. The first catalyst may be different from the second catalyst. This can improve the catalytic efficiency of the plasma generation unit by adjusting the catalyst on a given electrode to a compound near that electrode during operation of the plasma generation unit.

[0031] With the first and second electrode components arranged upstream and downstream of each other relative to the gas flow path through the plasma generating unit, the first catalyst can be applied only to the downstream electrode. This configuration allows for the efficient use of the first catalyst because, relative to the midpoint between the two electrode components, the catalyst is positioned in the direction in which the active material generated in the plasma will travel through the plasma generating unit.

[0032] The conductive core of each electrode component may include one or more of stainless steel, aluminum, brass, iron, or copper. The composition of the conductive core can be customized based on the desired conductivity, cost, weight, and ductility of the conductive core.

[0033] The dielectric coating of the electrode components can be porous or non-porous. For porous coatings, any catalysts included in the dielectric coating (e.g., additional catalysts where the dielectric material itself is a catalyst) can be disposed at least partially on the inner surface of the pores of the dielectric coating. Compared to non-porous dielectric coatings, this structure can provide an increased surface area for catalysis of decomposition reactions occurring within the plasma generation unit.

[0034] When the dielectric coating of the electrode component is porous and the catalyst is at least partially disposed on the inner surface of the pores in the dielectric coating, an impregnation technique (e.g., incipient wetness impregnation technique) can be used to deposit the catalyst on the inner surface of the pores. The incipient wetness impregnation technique is technically simple, low-cost, and generates a limited amount of waste, while also ensuring that the catalyst is located within the pores of the substrate. This means that the overall thickness and uniformity of the coating are not affected by catalyst deposition.

[0035] Porous dielectric coatings can exhibit inhomogeneity in terms of a wide range of cracks and pores within the film, potentially extending downwards to the metal electrode, which can alter discharge characteristics and breakdown mechanisms. Impregnating dielectric films with catalysts can provide the additional benefit of pore / crack sealing, allowing the porosity of the coated film to be controlled from relatively porous to non-porous, which helps maintain desired electrical, mechanical, and chemical properties.

[0036] The plasma generation unit may include multiple first electrode components and multiple second electrode components, wherein each pair of adjacent first electrode components is intervened by a second electrode component, and each pair of adjacent second electrode components is intervened by a first electrode component. Compared to a plasma generation unit with only a single first electrode component and a single second electrode component, this plasma generation unit can handle a larger volume of air, and compared to a plasma generation unit including only a pair of first electrode components and a second electrode component, it maintains the conversion of the plasma generation unit by increasing the residence time of air within the plasma generation unit.

[0037] The plasma generation unit may also include a power source connected to each first electrode member and / or each second electrode member. The power source, thus connected, can be configured to deliver pulsed DC to each electrode member to which it is connected, so as to generate plasma between the first electrode member and the second electrode member adjacent to the first electrode. By providing pulsed DC to the electrode members connected to the power source, the energy consumption of the plasma generation unit can be reduced compared to using non-pulsed DC, and additional control variables can be provided for controlling the plasma discharge within the plasma generation unit.

[0038] The plasma generation unit may further include a third electrode component, which is positioned between the first and second electrode components. The third electrode component may incorporate one or more optional features of the first and / or second electrode components described above.

[0039] The power supply can be configured such that the parameters for supplying pulsed DC current to each electrode component to which the power supply is connected can be adjusted independently of other electrode components to which the power supply is connected. This allows the plasma discharge between a pair of adjacent electrode components to be controlled independently of the plasma discharge between other pairs of adjacent electrode components.

[0040] When the power supply is configured to deliver pulsed DC to each electrode component connected to the power supply, the pulsed DC received by each electrode component can: generate an electric field strength with an applied voltage greater than or equal to 0.3 kV and less than or equal to 1.9 kV between that electrode component and adjacent electrode components; have a pulse frequency greater than or equal to 0.5 kHz and less than or equal to 100 kHz; and have a pulse width of more than 0.05 μs and less than 50 μs. The plasma generation unit is configured to provide such pulsed DC to each electrode component connected to the power supply to promote the effective decomposition of VOCs in ambient air, while limiting the amount of plasma byproducts and partially oxidized VOCs released by the plasma generation unit compared to the case where the power supply does not provide such pulsed DC to the electrode components connected to the power supply.

[0041] In a plasma generation unit including a power source, the power source is configured to deliver pulsed DC to each electrode component to which it is connected. The pulsed DC received by each electrode component can have a voltage greater than or equal to 0.3 kV. The pulsed DC received by each electrode component can have a voltage less than or equal to 1.9 kV. The pulsed DC received by each electrode component can have a voltage greater than or equal to 0.8 kV. The pulsed DC received by each electrode component can have a voltage less than or equal to 1.0 kV. The pulsed DC received by each electrode component can have a voltage greater than or equal to 0.88 kV. The pulsed DC received by each electrode component can have a voltage less than or equal to 0.92 kV. Compared to a case where the power source does not provide such pulsed DC to the electrode components to which it is connected, providing each electrode component with pulsed DC of this voltage is beneficial for generating plasma to catalyze the decomposition of VOCs, while limiting the presence of plasma byproducts in the air leaving the plasma generation unit.

[0042] In a plasma generation unit including a power source, the power source is configured to deliver pulsed DC current to each electrode component connected to the power source. The pulsed DC current received by each electrode component can have a current amplitude greater than or equal to 0.01 A. Alternatively, the pulsed DC current received by each electrode component can have a current amplitude less than or equal to 8 A. Other options include: 0.2 A, 0.3 A, 0.4 A, and 0.5 A. Providing such pulsed DC current to each electrode component is beneficial for generating plasma to catalyze the decomposition of VOCs, compared to a situation where the power source does not provide this pulsed DC current to the electrode components connected to the power source.

[0043] In a plasma generation unit including a power source, the power source is configured to deliver pulsed DC to each electrode component to which it is connected. The pulsed DC received by each electrode component can have a pulse width greater than or equal to 0.05 μs. Alternatively, the pulsed DC received by each electrode component can have a pulse width greater than or equal to 3 μs. Or, the pulsed DC received by each electrode component can have a pulse width less than or equal to 10 μs. Or, the pulsed DC received by each electrode component can have a pulse width less than or equal to 50 μs. Or, the pulsed DC received by each electrode component can have a pulse width less than or equal to 15 μs. Or, the pulsed DC received by each electrode component can have a pulse width less than or equal to 5 μs. Providing pulsed DC with this pulse width to each electrode component is beneficial for generating plasma to catalyze the decomposition of VOCs, while limiting the presence of plasma byproducts in the air leaving the plasma generation unit.

[0044] In a plasma generation unit, each electrode component can be a perforated plate. Setting the electrode components as perforated plates promotes greater contact between the ambient air and the electrode components, thereby increasing the conversion efficiency of the plasma generation unit. Furthermore, the perforated plate structure is easy to manufacture and provides electrode components with a high surface area to volume ratio, thus reducing excess material within the electrode components. Perforated plates can include a regular array of perforations or an irregular arrangement of perforations. Perforated plates can have an opening area percentage greater than or equal to 10%. Perforated plates can have an opening area percentage less than or equal to 35%. Perforated plates can have an opening area percentage greater than or equal to 22%. Perforated plates can have an opening area percentage less than or equal to 90%. Perforated plates can have an opening area percentage greater than or equal to 24.5%. Perforated plates can have an opening area percentage less than or equal to 25.5%. The opening area percentage can be set to balance the pressure drop across the plasma generation unit with the surface area of ​​the electrode components that can be used for catalysis and plasma generation.

[0045] When the electrode components are plate-shaped and offset from each other axially, the first catalyst can be applied only to the surface of the electrode component adjacent to another electrode component within the electrode group. This positioning of the catalyst effectively utilizes the catalyst by positioning it near the center of the discharge region in the plasma generation unit where plasma is generated.

[0046] When the electrode components are perforated plates, those perforated plates can be curved and / or bent. Perforated plates with curves and / or bends can facilitate different plasma generation unit geometries.

[0047] The plasma generation unit may also include non-conductive spacers located between adjacent electrode members. The non-conductive spacers may extend around at least a portion of the periphery of the electrode members. Such non-conductive spacers electrically isolate the electrode members from each other and from the remainder of the plasma generation unit. The non-conductive spacers may comprise PTFE or another electrically insulating polymer, such as other polymers having approximately the same hardness and / or resistance as PTFE.

[0048] In a plasma generation unit where each electrode component is a perforated plate, adjacent plate electrode components can be substantially parallel to each other and offset from each other such that the distance between adjacent surfaces of adjacent electrode components is 1 mm or less. The offset distance between adjacent electrode components can be greater than or equal to 0.01 mm. The offset distance between adjacent electrode components can be less than or equal to 1 mm. The offset distance between adjacent electrode components can be less than or equal to 0.5 mm. The offset distance between adjacent electrode components can be less than or equal to 0.25 mm. The offset distance between adjacent electrode components can be less than or equal to 0.15 mm. The offset distance between adjacent electrode components can be greater than or equal to 0.05 mm. The offset distance between adjacent electrode components can be greater than or equal to 0.09 mm. The offset distance between adjacent electrode components can be less than or equal to 0.11 mm. The offset distance between adjacent electrode components can be greater than or equal to 0.20 mm. The offset distance between adjacent electrode components can be greater than or equal to 0.4 mm. Providing such an offset distance between adjacent plate electrode components helps generate plasmas with voltages ranging from approximately 0.3 to 1.9 kV and lower electron energies, resulting in fewer plasma byproducts than at higher voltages and electron energies.

[0049] The system may also include an adsorption unit connected to the plasma generation unit. The adsorption unit can be connected to the plasma generation unit such that it is located directly downstream of the plasma generation unit, so that air leaving the plasma generation unit flows directly into the adsorption unit (i.e., does not enter the ambient air). The adsorption unit can be configured to adsorb one or more of VOCs, VOC decomposition products, and plasma byproducts contained in the airflow leaving the plasma generation unit during use of the plasma generation unit. Advantageously, including the adsorption unit downstream of the plasma generation unit can reduce the concentration of VOCs, VOC decomposition products, and / or plasma byproducts contained in the airflow that has already been released into the ambient air by the plasma generation unit. Furthermore, long-lived plasma material arriving at the adsorption unit from plasma generation can decompose the VOCs and VOC decomposition products adsorbed onto the adsorbent within the adsorption unit, thereby increasing the adsorbent's lifetime.

[0050] The system may also include a catalytic unit connected to the plasma generation unit. The catalytic unit can be connected to the plasma generation unit such that it is located directly downstream of the plasma generation unit, so that air leaving the plasma generation unit flows directly into the adsorption unit (i.e., without entering ambient air). The catalytic unit can be configured to catalyze the decomposition of one or more of VOCs, VOC decomposition products, and plasma byproducts contained in the airflow leaving the plasma generation unit during the use of the plasma generation unit. Advantageously, including the catalytic unit downstream of the plasma generation unit allows for a further increase in VOC conversion achieved by the air purification device beyond that achieved in the plasma generation unit. Furthermore, the long-lived plasma material reaching the catalytic unit from the plasma generation unit can enhance the decomposition of VOCs and VOC decomposition products on the catalyst surface in the catalytic unit, thereby further reducing the concentration of VOCs and VOC decomposition products contained in the airflow already released into the ambient air by the plasma generation unit. The catalytic unit can operate at room temperature or higher, depending on the required energy consumption and the balance of conversion.

[0051] The system may include both an adsorption unit and a catalytic unit in combination with a plasma generation unit. When both adsorption and catalytic units are present, the catalytic unit may be located directly downstream of the plasma generation unit and directly upstream of the adsorption unit, such that air leaving the plasma generation unit flows directly into the catalytic unit (i.e., without entering ambient air), and air leaving the catalytic unit flows directly into the adsorption unit (i.e., without entering ambient air). Alternatively, when both adsorption and catalytic units are present, the adsorption unit may be directly downstream of the plasma generation unit and upstream of the catalytic unit, such that air leaving the plasma generation unit flows directly into the adsorption unit (i.e., without entering ambient air), and air leaving the adsorption unit flows directly into the catalytic unit (i.e., without entering ambient air).

[0052] The adsorption unit and the catalytic unit can be combined into a single unit by doping a catalyst onto the adsorbent contained within the adsorption unit. In this way, the oxidation of adsorbed compounds (including VOCs, VOC decomposition products, and plasma byproducts) can be accelerated compared to the adsorbent without catalyst doping.

[0053] Multiple adsorption and / or catalyst units may be configured not to remove charged air pollutants generated by the plasma generation unit from the airflow passing through them, for example, by means of the adsorption and / or catalyst units being charge-neutral and non-electrostatic.

[0054] When the system includes an adsorption unit and / or a catalytic unit, the system can be configured to operate under continuous storage-discharge operation, wherein air flows through the plasma generation unit and the adsorption unit and / or catalytic unit once before leaving for ambient air. Advantageously, this can increase the flow rate of ambient air that can be introduced into the plasma.

[0055] Alternatively, when the system includes an adsorption unit and / or a catalytic unit, the air purification device can be configured to operate under a cyclic storage-discharge operation, wherein a portion of the air leaving the adsorption unit and / or catalytic unit is recirculated back into the plasma generation unit before leaving the ambient air. Advantageously, this can increase the total VOC conversion achieved by the system.

[0056] Within an air purification system, the collection unit may include an electrostatic precipitator. Therefore, charged air pollutant particles generated by the plasma generation unit can be collected by the collection unit and removed from the ambient air, and this collection unit provides a lower pressure drop for the corresponding collection efficiency compared to purely mechanical filter media.

[0057] When the collection unit of an air purification system includes an electrostatic precipitator, the electrostatic precipitator may include: one or more main collection elements; and a main voltage source configured to supply a positive DC voltage to the one or more collection elements. In this way, during use, negatively charged air pollutants can be electrostatically attracted to the main collection elements. Since a plasma generation unit will preferentially generate negatively charged air pollutants, it may be advantageous for the electrostatic precipitator to include a positively charged main collection element.

[0058] An electrostatic precipitator may include one or more secondary collecting elements and a secondary voltage source configured to supply a negative DC voltage to the collecting elements. In this way, during use, positively charged airborne contaminants can be electrostatically attracted to the secondary collecting elements. This allows the electrostatic precipitator to collect both negatively and positively charged airborne contaminants. Alternatively, the electrostatic precipitator may not include one or more secondary elements and a secondary voltage source. Omitting the secondary elements and voltage source helps to make the electrostatic precipitator more compact compared to the case where they are present.

[0059] Electrostatic precipitators may not include a charging section (e.g., an air ionizer). This helps to make the electrostatic precipitator more compact. Typically, a charging section / air ionizer is not required in the system according to the first aspect because charged air pollutant particles are already generated by the plasma generation unit.

[0060] The primary collecting element may include multiple substantially parallel plates, and the electrostatic precipitator may be configured such that airflow through the collecting unit is in a direction substantially parallel to the plates. When present, the secondary collecting element may include multiple substantially parallel plates, and the electrostatic precipitator may be configured such that airflow through the collecting unit is in a direction substantially parallel to the plates. The secondary collecting element may be spaced apart from the primary collecting element (e.g., a secondary collecting element may be inserted between each pair of primary collecting elements). In the case where the electrostatic precipitator includes a single primary collecting element and a single secondary collecting element, the primary and secondary collecting elements may be substantially parallel plates, and the electrostatic precipitator may be configured such that airflow through the collecting unit is in a direction substantially parallel to the plates.

[0061] According to the first aspect, the collection unit of the air purification system may include an electrostatic filter medium. The electrostatic filter medium may be an electret filter medium, such as a space charge electret or a dipole electret. The electret filter medium may be an electrostatically charged synthetic nonwoven material. The electret filter medium can be produced using thermal charging, corona effect, or triboelectric effect. By utilizing the electrostatic filter medium within the collection unit, a device is provided for collecting charged air pollutants by electrostatic attraction without consuming power.

[0062] Electrostatic filter media may include one or more positively charged regions separated from one or more negatively charged regions. Therefore, electrostatic filter media can effectively collect both positively and negatively charged air pollutants through electrostatic attraction between at least a portion of the collection unit and charged air pollutants.

[0063] In the air purification system according to the first aspect, a plasma generating unit may be included in a plasma generating device; a collection unit may be included in a collection device; and the plasma generating device may be separate from the collection device, allowing the devices to be positioned independently of each other. That is, the system may include the two devices to be independently positioned within the volume of ambient air (e.g., a room) to be purified by the system. By placing the plasma generating unit and the collection unit in separate devices, charged air pollutants from the plasma generating unit enter the surrounding environment before passing through the collection unit. This provides the possibility for the removal of charged air pollutants from the ambient air in the surrounding environment by agglomeration and settling or attraction to surfaces in the surrounding environment rather than entering the collection unit. Therefore, the required capacity of the collection unit is reduced compared to the direct flow of airflow from the plasma generating unit into the collection unit, because the amount of charged air pollutants from the plasma generating unit subsequently entering the collection unit is reduced, thus making the collection unit more compact.

[0064] In a second aspect, an air purification device is provided, comprising: an air inlet; an air outlet; and an air purification system according to the first aspect; wherein, in use, ambient air flows along an air path that enters the device via the air inlet, passes through the air purification system, and exits the device via the air outlet.

[0065] By providing an air purification device in which a collection unit is configured to collect air pollutants through electrostatic attraction between at least a portion of the collection unit and the air pollutants, the pressure drop of the collection unit can be reduced compared to that achievable with a purely mechanical filtration system for the same filtration efficiency. From an alternative perspective, the filtration efficiency is improved for a given pressure drop compared to a purely mechanical filtration system. By utilizing a plasma generation unit to generate charged air pollutants for collection by the collection unit, an ion generator can be omitted from the air purification system, thereby reducing the amount of ozone molecules generated by the air purification system. Furthermore, VOCs contained in the ambient air can be decomposed by reactive substances within the plasma generated by the plasma generation unit, thereby also reducing the concentration of VOCs in the ambient air while enhancing the removal of solid and / or liquid phase air pollutants.

[0066] Any one or more optional features described in the first aspect may be incorporated into the second aspect, unless such combination of optional features is clearly not permitted or explicitly avoided.

[0067] An air purification device may include a housing that contains an air purification system according to the first aspect and defines an air inlet and an air outlet.

[0068] Air purification devices may also include airflow generating units (e.g., fan assemblies or compressors, such as motor-driven impellers) configured to drive airflow along an air path. Therefore, this device can handle much higher airflow velocities compared to situations where airflow along an air path is driven by natural convection, diffusion, etc.

[0069] The plasma generating unit can be positioned upstream of the collecting unit along the air path through the device. This arrangement causes charged air pollutants from the plasma generating unit to enter the collecting unit before they reach the air outlet. Therefore, compared to an arrangement where the plasma generating unit is downstream of the collecting unit along the air path through the device, the likelihood of the charged air pollutants generated by the plasma generating unit being collected by the collecting unit is increased.

[0070] Alternatively, the plasma generation unit can be positioned downstream of the collection unit along the air path through the device. This arrangement results in charged air pollutants from the plasma generation unit exiting the device via an air outlet into the surrounding environment, while charged air pollutants entering the collection unit are drawn from the surrounding environment into the device via an air inlet. This arrangement allows charged air pollutants to be removed from the ambient air by agglomeration and settling and / or attraction to surfaces of the surrounding environment, rather than being drawn into the collection unit. Therefore, compared to a configuration where the plasma generation unit is located directly upstream of the collection unit along the air path, the required capacity of the collection unit is reduced because the amount of charged air pollutants from the plasma generation unit subsequently entering the collection unit is reduced, allowing for a more compact collection unit.

[0071] The device may also include a particulate filter (e.g., a non-electrostatic particulate filter) positioned upstream of the plasma generation unit and / or collection unit along the air path through the device. This can reduce the amount of large (e.g., aerodynamic diameter > 5 μm) solid and / or liquid particles entering these units. When the collection unit is upstream of the plasma generation unit along the air path and the collection unit includes an electrostatic filter medium, the particulate filter can be omitted from the device without substantially increasing the amount of large solid and / or liquid particles entering the plasma generation unit. However, including a particulate filter (e.g., a coarse pre-screen filter or mesh grid, but typically not a HEPA filter (e.g., a filter with a lower filtration efficiency than a HEPA filter) can significantly reduce the amount of large solid and / or liquid particles entering the plasma generation unit, where the plasma generation unit is positioned upstream of the collection unit along the air path, or the collection unit includes an electrostatic precipitator instead of an electrostatic filter medium.

[0072] Air purification devices can be fan components, such as indoor fans, like table fans or floor fans.

[0073] In a third aspect, a method is provided for treating ambient air using an air purification system to reduce the concentration of air pollutants, the system comprising:

[0074] Plasma generation unit; and

[0075] Collection unit;

[0076] The method includes the following steps:

[0077] The airflow containing air pollutants is passed through the plasma generation unit;

[0078] A plasma generation unit is used to generate plasma in ambient air to charge air pollutants, thereby providing charged air pollutants; and

[0079] An airflow containing charged air pollutants is passed through a collection unit to collect the charged air pollutants by electrostatic attraction between at least a portion of the collection unit and the charged air pollutants.

[0080] The method described in the third aspect can provide higher solid and / or liquid phase air pollutant removal efficiency than purely mechanical filtration at a given pressure drop by utilizing electrostatic attraction, while avoiding the use of ion generators to produce charged air pollutants, thereby reducing the amount of ozone molecules generated during the implementation of this method. Furthermore, VOCs contained in ambient air can be decomposed by reactive substances within the plasma generated by the plasma generation unit, thereby reducing the concentration of VOCs in ambient air and enhancing the removal of solid and / or liquid phase air pollutants.

[0081] Any one or more optional features set forth in the first and / or second aspects may be incorporated into the third aspect, unless such combination of optional features is clearly not permitted or explicitly avoided.

[0082] Air pollutants contained in the airflow passing through the plasma generation unit may include solid and / or liquid air pollutants.

[0083] Charged air pollutants generated by the plasma generation unit and collected by the collection unit may include solid and / or liquid air pollutants.

[0084] Air pollutants contained in the airflow passing through the plasma generation unit may include one or more VOCs.

[0085] In a fourth aspect, a method is provided for treating ambient air using an air purification system to reduce the concentration of air pollutants, the system including a plasma generation unit, the method comprising the following steps:

[0086] An airflow containing particulate air pollutants is passed through a plasma generation unit;

[0087] Plasma is generated in ambient air using a plasma generation unit to charge particulate air pollutants, thereby providing charged air pollutants.

[0088] Among them, particulate air pollutants present in the airflow include solid and / or liquid particles with an aerodynamic diameter of at least 0.1 micrometers.

[0089] According to the fourth aspect of the method, plasma can be used to generate charged solid and / or liquid air pollutants, which can then be removed from the airflow by electrostatic attraction. Alternatively, plasma can be used to promote the decomposition of VOCs in the airflow by reacting with active substances present in the plasma, thereby reducing the concentration of VOCs in the airflow.

[0090] The median mass aerodynamic diameter of solid and / or liquid particles present in the airflow can be at least 0.1 micrometers.

[0091] The gas stream containing particulate air pollutants delivered to the plasma generation unit can have a concentration of 12 μg / m³. 3 Or larger, 21 μg / m 3 Or larger, 29 μg / m 3 Or larger, 36 μg / m 3 Or larger, 43 μg / m 3 Or larger, 49 μg / m 3 Or larger, 54 μg / m 3 Or larger, 63 μg / m 3 Or larger, 71 μg / m 3 Or larger, 111 μg / m 3 Or larger, 151 μg / m 3 Or larger, 201 μg / m 3 Or larger, 251 μg / m 3 Or larger, or 376 μg / m 3 Or the concentration of particulate air pollutants (PM2.5) with a diameter of 2.5 micrometers or smaller.

[0092] The airflow containing particulate pollutants delivered to the plasma generation unit can have a concentration of 500 μg / m³. 3 or smaller, 375 μg / m 3 or smaller, 250 μg / m 3 or smaller, 200 μg / m 3 or smaller, 150 μg / m 3 or smaller, 110 μg / m 3 or smaller, 70 μg / m 3 or smaller, 62 μg / m 3 or smaller, 53 μg / m 3 or smaller, 48 μg / m 3 or smaller, 42 μg / m 3 or smaller, 35 μg / m 3 or smaller, 28 μg / m 3 or smaller or 20 μg / m 3 Concentration of particulate air pollutants with a diameter of 2.5 micrometers or smaller (PM2.5).

[0093] The airflow containing particulate air pollutants delivered to the plasma generation unit can have a concentration of 17 μg / m³. 3 Or larger, 29 μg / m 3 Or larger, 40 μg / m3 Or larger, 51 μg / m 3 Or larger, 60 μg / m 3 Or larger, 68 μg / m 3 Or larger, 76 μg / m 3 Or larger, 89 μg / m 3 or greater, 101 g / m3 or greater, 226 μg / m 3 Or larger, 351 μg / m 3 Or larger, 368 μg / m 3 Or larger, 421 μg / m 3 Or larger, or 511 μg / m 3 Or the concentration of particulate air pollutants (PM10) with a diameter of 10 micrometers or smaller.

[0094] The airflow containing particulate pollutants delivered to the plasma generation unit can have a concentration of 600 μg / m³. 3 or smaller, 510 μg / m 3 or smaller, 420 μg / m 3 or smaller, 385 μg / m 3 or smaller, 350 μg / m 3 or smaller, 225 μg / m 3 or smaller, 100 μg / m 3 or smaller, 88 μg / m 3 or smaller, 75 μg / m 3 or smaller, 67 μg / m 3 or smaller, 59 μg / m 3 or smaller, 50 μg / m 3 or smaller, 39 μg / m 3 Or smaller, or 28 μg / m 3 Or the concentration of particulate air pollutants (PM10) with a diameter of 10 micrometers or smaller.

[0095] The diameter of particulate air pollutants can be defined as the aerodynamic diameter of the air pollutant.

[0096] Any one or more of the optional features described in the first, second and / or third aspects may be combined into the fourth aspect, unless such combination of optional features is obviously not permitted or explicitly avoided.

[0097] In a fifth aspect, a plasma generation unit is provided for charging air pollutants with plasma generated in ambient air to provide charged air pollutants for subsequent collection in a collection unit, wherein the air pollutants are entrained in an ambient air stream incident on the plasma generation unit and the charged air pollutants are conveyed to the collection unit by the stream.

[0098] According to the method of the fifth aspect, plasma can be used to generate charged solid and / or liquid air pollutants so that these pollutants can be removed from the airflow by electrostatic attraction, or to promote the decomposition of VOCs in the airflow by reacting with active substances present in the plasma, thereby reducing the concentration of VOCs in the airflow.

[0099] Any one or more of the optional features described in the first, second, third and / or fourth aspects may be combined into the fifth aspect, unless such combination of optional features is obviously not permitted or explicitly avoided.

[0100] The anhydrous gaseous room-temperature composition of the ambient airflow containing air pollutants entering the plasma generation unit may be: 21% by mass of O2 and 78% by mass of N2, with the balance including VOCs, Ar, CO2, and trace elements and molecules. Ambient air (e.g., having a temperature greater than or equal to 0°C and less than or equal to 40°C, more typically greater than or equal to 15°C and less than or equal to 25°C, and an absolute pressure greater than or equal to 80 kPa and less than or equal to 120 kPa, typically about 100 kPa) may alternatively be referred to as atmospheric air and distinguished by its composition from, for example, exhaust gas from a vehicle. The system and / or any air purification equipment forming part of it are preferably not configured for vehicle architecture (e.g., not configured to treat exhaust gases from a vehicle engine). For example, in an air purification device forming part of the system, the airflow generator may be positioned downstream of the system (i.e., in a configuration opposite to the vehicle's exhaust gas treatment system). Additionally or alternatively, the catalyst module and / or adsorbent module may be configured to catalyze and adsorb VOCs respectively at low temperatures (e.g., less than or equal to 40°C). This system and / or air purification device may be configured for use in building environments, such as inside a building. As an example, this system and / or air purification device may be used in a fan (e.g., a table fan or floor fan) or incorporated into a fan.

[0101] This disclosure includes combinations of the described aspects and preferred features, unless such combinations are obviously not permitted or explicitly avoided. Attached Figure Description

[0102] Figure 1 A first air purification system including a plasma generation unit and a collection unit is shown;

[0103] Figure 2 It shows that it can be combined with Figure 1 The first plasma generation unit in the system;

[0104] Figure 3 It shows that it can be combined with Figure 1 The second plasma generation unit in the system;

[0105] Figure 4 It shows that it can be combined with Figure 1 The third plasma generation unit in the system;

[0106] Figure 5 Different controllable parameters of the pulsed DC supplied to the plasma generation unit by the power source are shown on the voltage-time curve.

[0107] Figure 6 It shows that it can be combined with Figure 1 The first electrostatic precipitator within the collection unit of the system;

[0108] Figure 7 It shows that it can be combined with Figure 1 The second electrostatic precipitator within the collection unit of the system;

[0109] Figures 8A to 8C They respectively show the combinations Figure 1 The air purification system and the first and second air purification devices that can be alternatively configured to the air purification system.

[0110] Figure 9 This is a schematic diagram of an air purification device;

[0111] Figure 10 A flowchart is provided for a method of treating ambient air to reduce the concentration of air pollutants therein;

[0112] Figure 11A This is a process flow diagram of the plasma generation unit combined with the adsorption unit;

[0113] Figure 11B This is a process flow diagram of the plasma generation unit combined with the catalytic unit;

[0114] Figure 11C This is a process flow diagram of the plasma generation unit combined with the catalytic unit and the adsorption unit.

[0115] Figure 12 Includes chromatograms of the feed and effluent streams of the plasma generation unit corresponding to Comparative Reference Example 1 in Table 3; and

[0116] Figure 13The chromatograms include those of the feed and effluent streams of the plasma generation unit corresponding to Reference Example 2 in Table 3. Detailed Implementation

[0117] Aspects, embodiments, and experiments relating to this disclosure will now be discussed with reference to the accompanying drawings. Other aspects and embodiments will be apparent to those skilled in the art. All references herein are incorporated by way of citation.

[0118] Figure 1 This is a schematic diagram of the first air purification system 10. The air purification system includes a plasma generation unit 1100 and a collection unit 1200. Figure 1 Arrow 1 illustrates the airflow of ambient air through each of the units, introducing and exiting each unit. Typically, the airflow through each unit is provided by an airflow generating unit (e.g., a fan assembly) that drives the airflow through that unit. Regarding... Figure 8B The use of airflow generation units within the system is further discussed. However, it is also envisioned that airflow could be driven by natural convection, diffusion, etc., rather than by airflow generation units.

[0119] The ambient air flowing into each unit typically includes a combination of solid and / or liquid air pollutants (such as dust, aerosols, etc.) and gaseous air pollutants (such as VOCs).

[0120] The plasma generation unit 1100 is configured to generate plasma in the ambient air flowing through it. Generating plasma in the ambient air has two effects on air pollutants contained in the ambient air.

[0121] First, the plasma contains several highly reactive substances that effectively react with and decompose VOCs contained in the ambient air within the plasma generation unit 1100. Therefore, the plasma generation unit 1100 reduces the concentration of VOCs in the ambient air flowing through it.

[0122] Secondly, the plasma contains several different charged substances (e.g., free electrons, hydroxyl ions, etc.) that can interact with solid and / or liquid air pollutants in the ambient air to form charged solid and / or liquid air pollutants with a sufficiently long lifetime to leave the plasma generation unit. Therefore, the plasma generation unit 1100 emits an airflow containing a variety of charged air pollutants. Typically, the charged air pollutants generated by the plasma generation unit 1100 are primarily negatively charged due to the high mobility of free electrons compared to larger charged substances such as helium nuclei (which are positively charged). Regarding... Figures 2 to 5 The plasma generation unit 1100 will be discussed in more detail.

[0123] Collection unit 1200 is configured to collect charged air pollutants generated by plasma generation unit 1100. Collection unit 1200 achieves this by an airflow containing charged air pollutants entering collection unit 1200, and collection unit 1200 is configured to generate electrostatic attraction between at least a portion of collection unit 1200 and those charged air pollutants. For example, this electrostatic attraction can be generated by a collection unit including an electrostatic precipitator or an electrostatic filter medium, both of which will be combined. Figure 6 and Figure 7 Further discussion. By using electrostatic attraction, the collection unit 1200 separates charged air pollutants from the airflow passing through it, thereby reducing the concentration of solid and / or liquid air pollutants in the ambient air flowing through it. By utilizing electrostatic attraction, the collection unit 1200 can provide the same reduction in air pollutant concentration as a purely mechanical filter medium, thus reducing the pressure drop across it. When the airflow through the collection unit 1200 is driven by a powered airflow generation unit, this reduction in pressure drop lowers the power consumption of the airflow generation unit for a given airflow velocity.

[0124] The system 10 can be configured such that the plasma generation unit 1100 and the collection unit 1200 are located within the overall air purification device / apparatus. However, the plasma generation unit 1100 and the collection unit 1200 can alternatively be located in separate devices, such as in a plasma generation device and a collection device, respectively. This will be relevant to... Figures 8A-8C Further discussion.

[0125] Figure 2 A schematic diagram of a cross-section of the first plasma generation unit 2100 is provided, which is substantially parallel to the air path passing through the unit 2100 (by...). Figure 2 (As indicated by the thick arrow 1 in the image). The first plasma generation unit 2100 can be incorporated into... Figure 1 In system 10, the plasma generation unit 2100 has a first electrode component 2110 and a second electrode component 2120, separated by a discharge gap 2140 between their adjacent surfaces. The first electrode component 2110 includes a conductive core 2111 and a dielectric coating 2112. Figure 2In the plasma generation unit 2100, the second electrode member 2120 also includes a corresponding conductive core 2121 and dielectric coating 2122. Therefore, the plasma generation unit 2100 is a dielectric barrier discharge (DBD) unit. For the two electrode members 2110 and 2120, the dielectric coatings 2112 and 2122 of the electrode members 2110 and 2120 completely coat the conductive cores 2111 and 2112 of the electrode members 2110 and 2120, such that no part of the cores 2111 and 2112 is exposed on the outer surface of the electrode members 2110 and 2120. As described in more detail below, the dielectric coatings of the first electrode member 2110 and the second electrode member 2120 may optionally include one or more catalysts.

[0126] A power supply 2150 is connected to the conductive core 2111 of the first electrode member 2110, and the conductive core 2121 of the second electrode member 2120 is connected to ground 2155. Current is supplied from the power supply 2150 to the first electrode member, thereby creating a potential difference between the electrode members 2110 and 2120 and generating an electric field across the discharge gap 2140. (Regarding...) Figure 5 The power supply 2150 and the current supplied to the electrode components 2110 and 2120 are further discussed. The potential difference applied between the electrode components 2110 and 2120 and the strength of the electric field generated in the discharge gap 2140 are sufficiently large to generate plasma in the discharge gap 2140 and near the electrode components 2110 and 2120 (i.e., the surfaces adjacent to the electrode components 2110 and 2120 but not adjacent to the discharge gap 2140), which together form the plasma discharge region of the plasma generation unit 2100. The highly reactive substances generated within the plasma can effectively decompose VOCs contained in the ambient air in the plasma generation unit, and the charged substances generated within the plasma can interact with solid and / or liquid air pollutants flowing through the plasma discharge region, thereby generating charged air pollutants.

[0127] although Figure 2 The core 2121 of the second electrode component 2120 is connected to ground 2155, but other structures are also possible, as long as a potential difference can be generated between the first electrode component 2110 and the second electrode component 2120 to generate plasma. For example, the cores 2111 and 2121 of the first electrode component 2110 and the second electrode component 2120 can also be connected to opposite terminals of the power supply 2150, or the core 2111 of the first electrode component 2110 is connected to ground 2155 and the core 2121 of the second electrode component 2120 is connected to the power supply 2150.

[0128] exist Figure 2In this design, both the first electrode component 2110 and the second electrode component 2120 are perforated plates. The first electrode component 2110 has a plurality of perforations 2113 arranged in a regular array on its planar surface, and the second electrode component 2120 also has a plurality of perforations 2123 arranged in a regular array on its planar surface. Figure 2 In the case where the perforation 2113 in the first electrode member 2110 and the perforation 2123 in the second electrode member 2120 are aligned across the discharge gap 2140 separating the electrode members 2110 and 2120. In the case where there is airflow through the electrode members 2110 and 2120 in the direction in which the perforations 2113 and 2123 extend through the electrode members 2110 and 2120 (e.g.) Figure 2 (As shown by the thick arrow 1 in the diagram), aligning the perforations 2113 and 2123 of adjacent electrode components 2110 and 2120 can reduce the pressure drop across unit 2100. However, by misaligning the perforations 2113 and 2123 of adjacent electrode components 2110 and 2120, the flow through unit 2100 can be made more turbulent, and the residence time and mixing of air in the discharge gap 2140 can be increased. When plasma is generated in unit 2100 near electrode components 2110 and 2120, increasing the residence time and mixing of air in the discharge gap 2140 can increase the VOC conversion achieved by plasma generation unit 2100, and can increase the proportion of charged solid and / or liquid phase air pollutants. For similar reasons, it is desirable to control the supply airflow into the plasma generation unit 2100 such that the air velocity through the perforations 2113, 2123 is uniform over the regions of the electrode members 2110, 2120, rather than the air velocity through the perforations 2113, 2123 closer to the center of the electrode members 2110, 2120 being substantially greater than the air velocity through the perforations 2113, 2123 closer to the edges of the electrode members 2110, 2120.

[0129] In such Figure 2In the plasma generation unit 2100 shown, the cores 2111 and 2121 of the plate electrode members 2110 and 2120 can have a thickness of about 1 mm, and the spacing between the holes can be about 5 mm, wherein the hole diameter is 3 mm, thereby providing about 32.7% of the opening area for the cores 2111 and 2112. Dielectric coatings 2112 and 2122 are then uniformly applied to the cores 2111 and 2121, and can have a thickness of about 200 μm, thereby reducing the opening area of ​​the resulting electrode members 2110 and 2120 to about 24.6%. The width of the discharge gap 2140 (i.e., the distance between adjacent surfaces of adjacent electrode members) is typically less than 1 mm, and preferably about 0.1 mm, to allow plasma to be formed at low voltage and low electron energy, thereby limiting the formation of plasma byproducts (discussed below with respect to the tests and examples in Tables 1-3).

[0130] The cores 2111 and 2121 of the electrode components 2110 and 2120 can be formed of any conductive material; however, it is preferred that the cores 2111 and 2121 comprise one or more of stainless steel, aluminum, brass, iron, or copper. These metals and metal alloys have high conductivity and are readily available. Compared to stainless steel and iron, aluminum, copper, and brass may be particularly advantageous in terms of light weight and high ductility. Another factor in selecting the material of the cores 2111 and 2121 is the portion of the power supplied to the electrode components that is lost as heat. Among the materials listed above, stainless steel offers the highest process efficiency in terms of heat loss, while the efficiency of aluminum, brass, iron, and copper decreases progressively. The outer surfaces of the cores 2111 and 2121 are ground (i.e., subjected to a grinding process, for example, to flatten them) prior to coating to increase surface uniformity and reduce plasma concentration areas and / or arc formation within the plasma generation unit 2100.

[0131] Depending on the operation of the plasma generation unit 2100, VOC decomposition within the plasma can lead to the formation of partially oxidized VOCs (VOC decomposition products) and long-lived plasma byproducts such as O3 and NO. X By providing a catalyst on the dielectric coating 2112, 2122 of one or both of the electrode components 2110, 2120, the decomposition of one or more of VOCs, VOC decomposition products and plasma byproducts can be catalyzed near the plasma in order to reduce the concentration of these substances in the gas stream leaving the plasma generation unit 2100.

[0132] The dielectric coatings 2112 and 2122 applied to the cores 2111 and 2121 of the electrode components 2110 and 2120 can have a substrate formed of metal oxides such as MnO2, Al2O3, CeO2, SiO2, and TiO2. Alternatives to the metal oxides include activated carbon and zeolite. Advantageously, these metal oxide materials and alternatives can be provided as substrates with high surface areas on which catalytic materials are disposed, and they themselves can also act as catalysts in the presence of plasma. When the dielectric coatings 2112 and 2122 are porous, the catalyst can be disposed on the substrate, at least partially disposed on the inner surface of the pores of the dielectric coating. Thus, by filling the pores or cracks with the catalyst, the porosity of the coating film can be controlled from relatively porous to non-porous.

[0133] In this plasma generation unit 2100, at least the first electrode member 2110 has a dielectric coating 2112, which includes a catalyst for the decomposition of one or more of the following: VOCs, VOC decomposition products; and plasma byproducts contained in the ambient air flowing through the unit 2100. Figure 2 In the plasma generation unit 2100 shown, if only the first electrode member 2110 includes a catalyst, it is preferable that the first electrode member 2110 is located downstream of the second electrode member 2120, such as... Figure 2 In this case, because the catalyst is located downstream of the discharge gap 2140, the plasma generated by unit 2100 is concentrated in the discharge gap 2140. This means that VOCs and plasma matter are more likely to interact on the surface where the catalyst is present, because this is the direction in which VOCs and plasma matter will travel through plasma generation unit 2100 after generation.

[0134] The catalyst may comprise one or more of the following: metal oxides, mixed metal oxides, noble metals, noble metal-metal oxide complexes, and noble metal-mixed metal oxide complexes. This catalyst may comprise one or more of Ag, Pt, Pd, Rh, Ni, Cu, Mo, Co, Mg, and Ti. The selected catalyst can be deposited on the surface of the material forming the remainder of the dielectric coatings 2112 and 2122 using an in-situ wet impregnation (IWI) technique. The use of IWI means that the macroscopic thickness and uniformity of the dielectric coatings 2112 and 2122 are unaffected by catalyst deposition.

[0135] While the plasma generation unit 2100 may include only a single electrode member 2110 having a dielectric coating 2112 including a catalyst, typically several or all of the electrode members 2110, 2120 within the unit 2100 have dielectric coatings 2112, 2122, and each dielectric coating 2112, 2122 includes a catalyst. However, the catalysts included in the dielectric coatings 2112, 2122 of each electrode member 2110, 2120 may differ between the electrode members 2110, 2120, such that different catalysts can be provided at different residence times within the plasma generation unit 2100; that is, the selection of the catalyst for each electrode member 2110, 2120 may be tailored to the substances present in the plasma at the location of that electrode member 2110, 2120 within the plasma generation unit 2100.

[0136] exist Figure 2 In the first electrode component 2110 and the second electrode component 2120, both include dielectric coatings 2112 and 2122, because this can help reduce the possibility of arc discharge between the electrodes and the formation of a large number of plasma byproducts and damage to the coating caused by arc formation.

[0137] Furthermore, the addition of a catalyst on the substrate of dielectric coatings 2112 and 2122 increases the capacitance of electrode components 2110 and 2120, enabling plasma generation unit 2100 to operate at a lower current level while still generating plasma, thereby reducing the energy consumption of plasma generation unit 2100.

[0138] Figure 3 A schematic diagram of a cross-section of the second plasma generation unit 3100 is provided, which is substantially parallel to the air path passing through the unit (by...). Figure 3 (Indicated by the thick arrow 1 in the image). The second plasma generation unit 3100 can be combined with... Figure 1 In System 10. Figure 3 The plasma generation unit 3100 in the middle can be considered as Figure 2 A variation of the first plasma generation unit 2100 shown, and Figure 2 Most of the foregoing descriptions can be applied with necessary modifications to the details. Figure 3 .

[0139] However, Figure 3 The second plasma generation unit 3100 in the middle and Figure 2The difference between the first plasma generation unit 2100 and the second plasma generation unit 3100 shown is that the second plasma generation unit 3100 further includes a third electrode member 3130 located between the first electrode member 3110 and the second electrode member 3120. The electrode members 3110, 3120, and 3130 are spaced apart from each other, such that a discharge gap 3140 is disposed between adjacent electrode members 3110, 3120, and 3130, as per [reference to...]. Figure 1 The subject of discussion (i.e., Figure 3 The distance between the first electrode member 3110 and the second electrode member 3120 in the plasma generation unit 3100 is made larger to accommodate the third electrode member 3130 between them, wherein the discharge gaps 3140a and 3140b disposed between adjacent electrode members 3110, 3120 and 3130 are within the same size range as discussed with respect to the discharge gap 2140 of the first plasma generation unit 2100. Figure 3 The electrode components 3110, 3120, and 3130 of the second plasma generation unit 3100 have a structure substantially the same as that described above with respect to the first electrode component 2110 and / or the second electrode component 2120 of the first plasma generation unit 2100. However, the dielectric coatings 3112, 3122, and 3132 of each electrode component 3110, 3120, and 3130 may include (multiple) catalysts that can differ between the electrode components 3110, 3120, and 3130, allowing different catalysts to be provided within the plasma generation unit 3100 at different residence times. This allows the selection of catalysts for each electrode component 3110, 3120, and 3130 to be tailored to the substances present in the plasma at the location of the electrode component 3110, 3120, and 3130 in the unit 3100.

[0140] Another difference between the second plasma generation unit 3100 and the first plasma generation unit 2100 is the connection between the power supply 3150 and the electrode components 3110, 3120, and 3130. In the first plasma generation unit 2100, the power supply 2150 is only connected to the core 2111 of the first electrode component 2110, and the core 2121 of the second electrode component 2120 is connected to ground 2155. However, for the second plasma generation unit 3100, the cores 3111 and 3121 of the first electrode component 3110 and the second electrode component 3120 are both connected to the power supply 3150, and the core 3131 of the third electrode component 3130 is connected to ground 3155. The connections of the power supplies 2150 and 3150 are... Figure 2 and Figure 3The difference is that the electrode components 3110, 3120, and 3130 of the second plasma generation unit 3100 need to be supplied with current in such a way that a potential difference is generated between a given electrode component and the (multiple) electrode components adjacent to the given electrode component, so that plasma is subsequently generated through the generated electric field.

[0141] Understandable, such as Figure 3 As shown, by intervening the third electrode component 3130 between the first electrode component and the second electrode components 3110 and 3120, the distance in the air path direction for generating plasma within the plasma generation unit 3100 is increased. This increases the residence time of air within the unit 3100 for a given airflow velocity entering the unit 3100, while maintaining the potential difference between the discharge gap and adjacent electrode components 3110, 3120, and 3130. This contributes to the generation of plasma with minimal plasma byproducts. Therefore, the conversion of VOCs and VOC decomposition products within the plasma generation unit 3100 increases because VOCs and VOC decomposition products reside in the plasma for a longer time and are closer to the catalyst used in the reaction to decompose these compounds. Furthermore, the proportion of charged solid and / or liquid air pollutants in the airflow increases.

[0142] An additional feature of the second plasma generation unit 3100 is the presence of a non-conductive spacer 3160 located between the electrode members 3110, 3120, and 3130. The non-conductive spacer extends circumferentially around the electrode members 3110, 3120, and 3130 to isolate adjacent electrode members 3110, 3120, and 3130 from each other and from any other conductive structures within the plasma generation unit 3100 (e.g., the housing of the plasma generation unit 3100). Typically, the spacer 3160 comprises a rigid insulating plastic (e.g., PTFE or other polymers having approximately the same hardness and / or resistance as PTFE). To provide adequate insulation, the spacer 3160 has a thickness greater than or equal to 25 μm. Typically, the diaphragm thickness is less than or equal to 1000 μm.

[0143] Figure 4 With the air path substantially parallel to that passing through the unit (by Figure 4 The cross-section shown by the thick arrow 1 in the diagram provides a schematic diagram of the third plasma generation unit 4100. The second plasma generation unit 4100 can be combined with... Figure 1 In System 10. Figure 4 The plasma generation unit 4100 in the middle can be considered as Figure 2 A variation of the first plasma generation unit 2100 shown, and Figure 2 Most of the foregoing descriptions can be applied with necessary modifications to the details. Figure 4 .

[0144] However, Figure 4 The third plasma generation unit 4100 in Figure 2 The difference shown is that the third plasma generation unit 4100 includes a plurality of first electrode members 4110 and a plurality of second electrode members 4120. Specifically, the third plasma generation unit 4100 includes two first electrode members 4110a and 4110b and two second electrode members 4120a and 4120b. A pair of adjacent first electrode members 4110a-b are intervened by the second electrode members 4120, and a pair of adjacent second electrode members 4120a-b are intervened by the first electrode members 4110a. The electrode members 4110 and 4120 are spaced apart from each other such that a discharge gap 4140 is disposed between adjacent electrode members, as shown in the figure. Figure 2 The discharge gaps 4140a, 4140b, and 4140c discussed (i.e., the gaps 4140a, 4140b, and 4140c disposed between adjacent electrode components) are related to... Figure 2 (Within the same size range discussed for the discharge gap 140 of the first plasma generation unit 2100). The core 4121 of the two second electrode members 4120a, 4120b is connected to the power supply 4150, while the core 4111 of the two first electrode members 4110a, 4110b is connected to ground 4155. It can be understood that by adding, as Figure 4 The increased number of first and second electrode components 4110 and 4120 within the plasma generation unit 4100, along with the increased distance between them in the direction of the air path for plasma generation within the unit 4100, results in a longer residence time of air within the plasma generation unit 4100 for a given airflow velocity, while maintaining the discharge gap and potential difference between adjacent electrode components 4110 and 4120. This contributes to the generation of plasma with minimal plasma byproducts. Consequently, the conversion of VOCs and VOC decomposition products within the plasma generation unit 4100 increases due to their longer residence time in the plasma and their proximity to the catalyst used in the reaction to decompose these compounds. Furthermore, the proportion of charged solid and / or liquid air pollutants in the airflow increases.

[0145] exist Figure 4In the third plasma generation unit 4100, the dielectric coatings 4112 and 4122 of each electrode component 4110a-b and 4120a-b may include (multiple) catalysts that may differ between the electrode components, so that different catalysts can be provided within the unit 4100 at different residence times. That is, the selection of catalysts for each electrode component 4110a-b and 4120a-b can be customized according to the substances present in the plasma at the location of the electrode component 4110a-b and 4120a-b in the plasma generation unit 4100.

[0146] Understandable. Figure 3 and Figure 4 The arrangement of plasma generation units 3100 and 4100 shown can be extended in a similar manner to further increase the residence time of plasma generation units 3100 and 4100. For example, Figure 4 The plasma generation unit 4100 shown can be scaled up to have three, four or five first electrode components 4110 and second electrode components 4120, respectively, wherein each pair of adjacent first electrode components 4110 is intervened by the second electrode component 4120, and each pair of adjacent second electrode components 4120 is intervened by the first electrode component 4110.

[0147] Such as about Figure 2 and Figure 3 The power supplies 2150, 3150, and 4150 discussed are connected to... Figure 2 and Figure 3One or more electrode components in plasma generation units 2100, 3100, and 4100 are used to supply current to the electrode components connected to a power source. This current generates a potential difference between adjacent electrode components, which in turn generates an electric field across a discharge gap between the adjacent electrode components. The potential difference applied between the electrode components and the intensity of the electric field generated in the discharge gap can be sufficiently large to generate plasma in the discharge gap and in the vicinity of the electrode components (i.e., the surfaces of adjacent electrode components that are not adjacent to the discharge gap), which together form the plasma discharge region of the plasma generation unit. The energy of the free electrons within the plasma generated in units 2100, 3100, and 4100 affects the likelihood of plasma byproduct formation and also influences the conversion of VOCs contained within the plasma and the generation of solid and / or liquid-phase charged air pollutants. Generally, the higher the energy of the free electrons, the more plasma byproducts are formed, the higher the VOC conversion within the plasma generation units 2100, 3100, and 4100, and the greater the amount of solid and / or liquid-phase charged air pollutants generated. Therefore, a balance must be struck between these factors. The energy of free electrons within the plasma strongly depends on the electric field strength between adjacent electrode components, and therefore on the potential difference between them. Power supplies 2150, 3150, and 4150 are configured to provide pulsed DC to the electrode components to which they are connected; by providing pulsed DC to the electrode components connected to the power supply, the energy consumption of plasma generation units 2100, 3100, and 4100 can be reduced compared to using non-pulsed DC, and additional control variables for the electric field strength between adjacent electrode components are also provided.

[0148] Figure 5 An illustrative voltage-time graph is provided, which includes the waveform of pulsed DC supplied by a power source to the electrode components of the plasma generation unit of this disclosure. The pulsed DC waveform includes a pulse-on phase when the voltage of the power source is non-zero and a pulse-off phase when the voltage of the power source is approximately zero. Figure 5 The pulsed DC waveform shown has three controllable parameters to adjust the potential difference between adjacent electrode components in the plasma generation unit. First, the voltage amplitude 4 of the pulsed DC is adjustable; voltage amplitude 4 is the amplitude of the waveform during the pulse on-phase. Second, the pulse width 2 is adjustable; pulse width 2 is the duration of the pulse on-phase. Third, the waveform period 3 is adjustable; period 3 is the duration for completing a full pulse-on-pulse-off cycle. Period 3 is the reciprocal of the frequency of the pulsed DC.

[0149] The data in Tables 1-3 for the examples further illustrate the impact of these pulsed DC parameters on the performance of the plasma generation unit.

[0150] Figure 6 Provided Figure 1 The collection unit 1200 of system 10 may include a schematic diagram of a first electrostatic precipitator. (See also: Regarding...) Figure 1 The collection unit 6200 discussed typically includes an electrostatic precipitator and / or an electrostatic filter medium.

[0151] An electrostatic precipitator is a filterless device that can be used within the system of the first aspect of this disclosure for removing charged airborne contaminants from the airflow passing through collection unit 6200. It is understood that... Figure 6 A specific electrostatic precipitator is shown, but other configurations of electrostatic precipitators can be used within the system of the first aspect of this disclosure.

[0152] Figure 6 The first electrostatic precipitator includes three main collecting elements 6210a-c and a main voltage source 6250, which is configured to provide a positive DC voltage to all three main collecting elements 6210a-c to generate an electric field around each main collecting element 6210a-c. Therefore, when an airflow is supplied through a collecting unit 6200 containing negatively charged air pollutants generated by the system's plasma generation unit, these air pollutants will be electrostatically attracted to the main collecting elements 6210a-c and will move to contact the collecting elements 6210a-c and be held adhered to them by electrostatic attraction. (See also: ...) Figure 1 The charged air pollutants discussed are generally mainly negatively charged by the plasma generating unit 1100. Therefore, the electrostatic precipitator can omit the negatively charged collection element without significantly affecting the collection efficiency of the electrostatic precipitator, thus allowing the electrostatic precipitator to be more compact (because there is no need to provide space for the negatively charged collection element inside the electrostatic precipitator).

[0153] In the first electrostatic precipitator, the main collecting elements 6210a-c are in the form of plate-like elements, each plate-like element having two main surfaces (i.e., the largest flat surface of each collecting element), at least one of which faces the adjacent main collecting element 6210a-c. The main collecting elements 6210a-c are arranged to be substantially parallel to each other. They generally overlap each other, but are spaced apart from each other in a direction perpendicular to their main surfaces, such that airflow channels defined on both sides by the main collecting elements 6210a-c are provided between adjacent main collecting elements 6210a-c.

[0154] The main collecting elements 6210a-c are relative to the airflow passing through the collecting unit 6200 (by... Figure 6(Indicated by the thick arrow 1) The airflow is oriented such that it is substantially parallel to the main surface of the main collection elements 6210a-c. This orientation provides the advantage that, compared to, for example, if the airflow were perpendicular to the main surface of the main collection elements 6210a-c, it increases the time the airflow spends near the surface of the main collection elements 6210a-c and thus exposed to the electric field of the main collection elements 6210a-c. Therefore, this arrangement increases the likelihood that charged air pollutants in the airflow are attracted to the main collection elements 6210a-c and thus removed from the airflow.

[0155] After air pollutants accumulate on the main collection elements 6210a-c, a regeneration cycle can be performed to remove the accumulation of air pollutants on the collection elements 6210a-c. This regeneration cycle typically involves stopping the airflow through the electrostatic precipitator, followed by temporarily disconnecting the main voltage source 6250 from the main collection elements 6210a-c to discharge the collection elements and allow the air pollutants to fall off the collection elements under gravity for removal.

[0156] Figure 7 Provided Figure 1 The system 10's collection unit 1200 may include a schematic diagram of a second electrostatic precipitator. The second electrostatic precipitator can be considered a modification of the first electrostatic precipitator, and... Figure 6 Most of the foregoing descriptions can be adapted to the following purposes with the necessary modifications: Figure 7 .

[0157] However, the second electrostatic precipitator differs from the first in that it includes both negatively charged and positively charged collecting elements. Specifically, in Figure 7 In the electrostatic precipitator, there are two main collecting elements 7210a-b positively charged by a main voltage source 7250 and a single secondary collecting element 7220 negatively charged by a secondary voltage source 7260. The main voltage source 7250 and the secondary voltage source 7260 are respectively... Figure 7 The positive and negative terminals of the battery.

[0158] and Figure 6 The first electrostatic precipitator has the same main collecting element as the second electrostatic precipitator. The main collecting element and the secondary collecting elements 7210a-b and 7220 are plate-shaped elements, and the secondary collecting element 7220 is located between the two main collecting elements.

[0159] By including both positively charged main collecting elements 7210a-b and negatively charged collecting elements 7220, the second electrostatic precipitator is able to collect both negatively charged and positively charged air pollutants from the airflow passing through the collecting unit 7200.

[0160] Additionally, or usually alternatively, for example regarding Figure 6 and Figure 7 The discussion includes the collection unit of an electrostatic precipitator, which may include an electrostatic filter medium. The electrostatic filter medium generates an electric field through uncompensated space charge or aligned dipoles present within the medium, and these electric fields allow the medium to electrostatically interact with air pollutants, particularly charged air pollutants. A range of techniques for forming electrostatic filter media can be used, including thermal charging, corona effect, or triboelectric effect. Typically, the electrostatic filter medium is an electrostatically charged synthetic nonwoven material.

[0161] In a second aspect of this disclosure, the aforementioned air purification system is integrated into an air purification device. This air purification device includes an air inlet and an air outlet. Ambient air can be supplied to the system through the air inlet, and the air processed by the system can exit the air purification device through the air outlet. In other words, the air inlet, air purification system, and air outlet are all arranged along the air path through which the ambient air can flow.

[0162] Figure 8A and 8B This is a schematic diagram of a first air purification device and a second air purification device that can be combined with the aforementioned air purification system. In both the first and second air purification devices, a plasma generation unit 8100 and a collection unit 8200 are disposed within an integrated air purification device 800. This device has an air inlet 810 and an air outlet 820, through which ambient air can flow into and out of the device 800, thus providing an air path that passes through the device via the air inlet 810, through the air purification system, and out of the device via the air outlet 820. Figure 8A and 8B In the air purification device, the plasma generation unit 8100 and the collection unit 8200 are contained within the housing 830 of the device 810. The housing 830 may define an air inlet 810 and / or an air outlet 820, and may further define the air path through the device.

[0163] Figure 8A and Figure 8B The first and second air purification devices differ from each other in the order in which the plasma generation unit 8100 and the collection unit 8200 are positioned along the air path. In the first air purification device, the plasma generation unit 8100 is located upstream of the collection unit 8200, while in the second air purification device, the plasma generation unit 8100 is located downstream of the collection unit 8200.

[0164] In the first air purification device, by positioning the plasma generation unit 8100 upstream of the collection unit 8200 within the device 800, charged air pollutants generated in the plasma generation unit 8100 flow into the collection unit 8200 without passing through the air outlet 820 of the device, and therefore do not enter the ambient air surrounding the device 800 (e.g., the ambient air contained in the room where the device 800 may be located). In other words, without any other units intervening between the plasma generation unit 8100 and the collection unit 8200 within the first device, charged air pollutants flow directly from the plasma generation unit 8100 into the collection unit 8200.

[0165] Conversely, in the second air purification device, by positioning the plasma generation unit 8100 downstream of the collection unit 8200 within the device 800, the charged air pollutants generated in the plasma generation unit 8100 flow out of the device 800 via the air outlet 820 and into the ambient air surrounding the device 800, instead of flowing directly into the collection unit 8200. Therefore, for the second air purification device to allow the charged air pollutants generated by the plasma generation unit 8100 to reach the collection unit 8200, the charged air pollutants must first leave the device 800 via the air outlet 820 and enter the ambient air surrounding the device 800, and then subsequently re-enter the device via the air inlet 810 to flow into the collection unit 8200 along the air path.

[0166] Compared to the arrangement of units in the second air purification device, the arrangement of units in the first air purification device provides a higher probability that charged air pollutants generated by the plasma generation unit 8100 will be collected by the collection unit 8200. This is because the residence time of charged air pollutants passing between the plasma generation unit 8100 and the collection unit 8200 in the first device is much shorter than the equivalent residence time in the second device (due to the dilution of charged air pollutants that occurs when they are emitted into the surrounding environment using the second device). Therefore, with the second device, charged air pollutants are more likely to be neutralized or removed from the ambient air (e.g., by settling on a surface) before reaching the collection unit 8200. Thus, relative to the amount of charged air pollutants generated, the first device can provide a higher solid and / or liquid phase air pollutant removal efficiency through the collection unit 8200.

[0167] However, although the efficiency of the second device may be lower, there are also advantages associated with it. By emitting charged air pollutants from the plasma generation unit 8100 into the surrounding environment of the device 800 before they reach the collection unit 8200, charged air pollutants can be removed from the ambient air of the surrounding environment by aggregation and settling and / or attraction to the surfaces of the surrounding environment.

[0168] Aggregation and settling involve charged air pollutants being attracted to other air pollutants in the ambient air (which may be oppositely charged or neutral, but capable of electrical interaction with charged air pollutants via van der Waals forces) and forming a sufficiently large collective mass, which then settles out of the air under the influence of gravity.

[0169] Alternatively, charged air pollutants can be attracted to surfaces in the surrounding environment (e.g., walls, ceilings, floors, and other surfaces in a room where device 800 may be located) by van der Waals forces between the charged air pollutants and the atoms or molecules of the surface, causing the charged air pollutants to adhere to these surfaces and thus be removed from the ambient air.

[0170] The accumulation, sedimentation, and / or adhesion of charged air pollutants on the surface around the device 800 reduces the amount of charged air pollutants in the ambient air that need to be collected by the collection unit 8200 for removal from the ambient air. Therefore, the required capacity of the collection unit 8200 is reduced because less charged air pollutants from the plasma generation unit 8100 subsequently enter the collection unit 8200, allowing for a more compact collection unit and / or a longer service life. For example, when the collection unit 8200 includes an electrostatic filter medium, a smaller amount of this medium can be included in the device 800 and / or the medium requires less frequent replacement or regeneration.

[0171] Figure 8C yes Figure 8A and 8B air purification system Figure 1 A schematic diagram of an alternative configuration for an air purification system. It does not provide the plasma generation unit 8100 and collection unit 8200 in an integrated device (such as...). Figure 8A and 8B (as in the middle), but in Figure 8C In this system, the plasma generation unit 8100 is included in the plasma generation device 800a and the collection unit 8200 is included in the collection device 800b, with the plasma generation device 800a and the collection device 800b being separate from each other.

[0172] The plasma generating device 800a and the collecting device 800b each include their own air inlets 810a and 810b, air outlets 820a and 820b, and housings 830a and 830b.

[0173] By arranging the plasma generation unit 8100 and the collection unit 8200 in their own separate devices 800a, 800b, the air purification system is integrated with... Figure 8BThe second air purification device 800 operates in a substantially similar manner, as charged air pollutants generated by the plasma generation unit 8100 enter the ambient air surrounding the devices 800a and 800b before reaching the collection unit 8200. This provides the possibility of aggregation and settling and / or adhesion to surfaces containing charged air pollutants.

[0174] However, Figure 8C Another benefit of the system configuration is that the plasma generating device 800a can be positioned independently of the collecting device 800b, for example, in different locations within a room containing ambient air to be purified. Furthermore, because... Figure 8C Each of the plasma generating device 800a and the collecting device 800b can be made smaller than the overall device 800 incorporated into the plasma generating unit 8100 and the collecting unit 8200, for example... Figure 8A and 8B Those in the above, so when using the system in locations where space is unavailable or limited for a single larger device 800, Figure 8C The system configuration in the middle may be advantageous.

[0175] Figure 9 An embodiment of an air purification device in the form of an integrated unit 900 is shown. An air inlet 910 is located at the base of the air purification device 900, and an air outlet 920 is located at the top of the device 900. A plasma generation unit 9100 and a collection unit 9200 of the air purification system are located along an air path between the air inlet 910 and the air outlet 920 and are contained within a housing 930 of the device 900. The plasma generation unit 9100 and the collection unit 9200 are arranged in series along the air path, such that air passing through the air inlet 910 (e.g., plasma from the air inlet 910) is... Figure 9 (As shown by the thick arrow 1 in the image) It first flows through the plasma generation unit 9100, and then through the collection unit 9200.

[0176] Despite Figure 9 In the device 900, the plasma generation unit 9100 is located upstream of the collection unit 9200; however, it is understood that the order of these units along the air path can be reversed, as per [reference to...]. Figure 8A and 8B The subject of discussion.

[0177] Figure 9 The air purification device 900 also includes an air propulsion unit 9300 (e.g., a compressor, fan, or blower) to drive airflow along an air path through the device 900. Figure 9In this configuration, the air propulsion unit 9300 is located downstream of the collection unit 9200 along the air path, causing air to be drawn by the air propulsion unit 9300 through the plasma generation unit 9100 and the collection unit 9200. However, the air propulsion unit 9300 can also be provided upstream of the plasma generation unit 9100 and the collection unit 9200 along the air path. The position of the air propulsion unit 9300 relative to the plasma generation unit 9100 and the collection unit 9200 affects the characteristics of the airflow through these units: positioning the air propulsion unit 9300 upstream of the plasma generation unit 9100 and the collection unit 9200 results in a more turbulent and higher pressure airflow through these units, while positioning the air propulsion unit 9300 downstream of the plasma generation unit 9100 and the collection unit 9200 provides a more laminar and lower pressure airflow through these units. While the air propulsion unit 9300 may be advantageous in driving airflow through the air purification device 900, the device 900 can also operate without the air propulsion unit 13, for example, if the device 900 is configured and / or positioned such that airflow convects naturally through the device 900, and / or if the airflow convects due to a temperature gradient caused by heat generated by the plates and / or power electronics of the plasma generation unit, and / or if the airflow convects due to an ion wind caused by the electrostatic forces acting on the particles within the plasma. Although in Figures 8A-8C Not shown in the image, but related to Figure 9 The air propulsion units (or multiple air propulsion units) shown therein can be included in the devices 800, 800a, 800c.

[0178] Despite Figures 8A-8C Not shown in Figures 8100 and 9100, but these air purification devices / appliances may also include particulate filters positioned upstream of plasma generation units 8100, 9100 and / or collection units 8200, 9200 along the air path through the device to reduce the amount of large (e.g., aerodynamic diameter > 5 μm) solid and / or liquid particles entering these units. In particular, it is desirable to reduce the amount of these large particles entering plasma generation units 8100, 9100, where they may, for example, clog the electrode components used to generate plasma and interfere with plasma generation. Various types of particulate filters may be used, including coarse pre-screen filters or mesh grilles, but are generally not HEPA filters.

[0179] Figure 10 A flowchart is provided for a method of using an air purification system to treat ambient air in order to reduce the concentration of air pollutants therein. Figure 10 The method utilizes an air purification system, which includes at least a plasma generation unit and an optional collection unit.

[0180] In step S100, an ambient airflow containing air pollutants is passed through the plasma generation unit. Typically, the air pollutants contained in the ambient air include solid and / or liquid particles with an aerodynamic diameter of at least 0.5 micrometers.

[0181] In step S200, the plasma generation unit is used to generate plasma in the ambient air passing through the plasma generation unit in step S100. Generating plasma in the ambient air first generates highly reactive substances (e.g., H, O, ·NO, ·OH, ·NO2, ONOO-, ·O2-, OOH), which effectively react with and decompose the VOCs contained in the ambient air within the plasma generation unit. Therefore, generating plasma in the ambient air reduces the concentration of VOCs in the air passing through the plasma generation unit.

[0182] Additionally, plasma is generated in ambient air to produce several different charged substances (e.g., free electrons, hydroxyl ions, O2, etc.). These charged substances can interact with solid and / or liquid air pollutants in the ambient air to form charged solid and / or liquid air pollutants with a sufficiently long lifetime to leave the plasma generation unit.

[0183] Therefore, the plasma generation unit discharges an airflow containing various charged air pollutants. Typically, the charged air pollutants generated by the plasma generation unit are primarily negatively charged due to the high mobility of free electrons compared to larger charged matter such as helium nuclei (which are positively charged).

[0184] In the event that these charged air pollutants are emitted from the plasma generation unit into the surrounding environment, they can be removed from the ambient air through aggregation and sedimentation and / or attraction to surfaces in the surrounding environment, as mentioned above. Figure 8B The second air purification device discussed here reduces the concentration of air pollutants in the ambient air.

[0185] However, if the air purification system also includes a collection unit, step S300 may optionally be included in the method. In step S300, ambient air containing charged air pollutants enters the collection unit, which is configured to generate an electrostatic attraction between at least a portion of the collection unit and the charged air pollutants. For example, this electrostatic attraction may be generated by the collection unit including an electrostatic precipitator or an electrostatic filter medium, as per [reference to...]. Figure 6 and Figure 7 As discussed, charged air pollutants are electrostatically attracted to the collection unit upon entering it. They are separated from the airflow and retained in the collection unit, thereby reducing the concentration of solid and / or liquid air pollutants in the ambient air exiting the collection unit.

[0186] Figure 11A-11C Process flow diagrams are provided for several different configurations of the plasma generation unit and adsorption and / or catalyst units that can be connected to the plasma generation unit. Figure 11A-11C In the flowchart, the plasma generation unit is equipped with a humid test gas flow containing VOCs, and an environmental gas flow containing O2, N2, H2O, toluene, solid and / or liquid air pollutants, as well as other trace elements and molecules. Figure 11A-11C The anhydrous gaseous, room-temperature composition of the VOC-containing ambient airflow in the plasma generation unit is: 21% by mass O2, 78% by mass N2, and 1 ppm toluene, with the balance including Ar, CO2, and other trace elements and molecules. Connecting the adsorption unit and / or catalytic unit to the plasma generation unit, such that the adsorption unit and / or catalytic unit are directly downstream of the plasma generation unit, and thus the air leaving the plasma generation unit flows directly into the adsorption unit (i.e., does not enter the ambient air), may be useful when the VOC concentration and / or plasma byproduct concentration in the air leaving the plasma generation unit remains high. For example, the number of electrode components within the plasma generation unit may be limited due to factors such as the pressure drop across the plasma generation unit and the space available for the plasma generation unit and / or additional electrode components.

[0187] exist Figure 11A In addition, the system also includes an adsorption unit directly connected downstream of the plasma generation unit, with the airflow path being... Figure 11A The thick arrow 1 in the diagram indicates this. Therefore, the air leaving the plasma generation unit flows directly into the adsorption unit (i.e., it does not enter the ambient air). (See above reference.) Figure 1-4 The plasma generation unit is used to decompose toluene molecules contained in the supply gas stream, wherein the effluent gas stream from the plasma generation unit includes toluene that has not been decomposed by the plasma generation unit, partially oxidized VOCs generated from the decomposition of toluene, and long-lived plasma substances (e.g., O, O2 (Al)). ), OH, HO2) and plasma byproducts (e.g. O3, NO) X The plasma generation unit is also used to charge the solid and / or liquid air pollutants in the supply gas stream through the interaction between solid and / or liquid air pollutants and charged substances (e.g., free electrons, hydroxyl ions, oxygen radicals, etc.) formed by the plasma generation unit. In the effluent gas stream of the plasma generation unit, the concentration and characteristics of toluene, VOC decomposition products, and plasma byproducts are functions of the operating conditions of the plasma generation unit (as mentioned above). Figure 5 And the following text about Tables 1-3 and Figure 12 and 13 (As discussed).

[0188] Then, Figure 11A The outflow gas from the plasma generation unit is conveyed to the adsorption unit. The adsorption unit is provided to adsorb toluene, toluene decomposition products, and plasma byproducts from the air treated by the plasma generation unit before the air leaves the ambient air. The adsorbent in the adsorption unit, located downstream of the plasma generation unit, is able to (at least partially) pass through long-lived plasma materials (e.g., O, O2 (Al2O3)). The plasma is regenerated in situ (e.g., OH, HO2), and the plasma material remains outside the plasma discharge zone of the plasma generation unit and reacts with toluene, toluene decomposition products, and plasma byproducts adsorbed onto the adsorbent in the adsorption unit. Therefore, the plasma generation unit and the adsorption unit work synergistically to provide an airflow with reduced VOC concentrations that conforms to WHO guidelines on ozone and nitrogen oxides. This airflow still contains charged liquid and / or solid air pollutants to be collected by the collection unit, but these can now be released into the ambient air.

[0189] exist Figure 11B The system also includes a catalytic unit, which is directly connected to the plasma generation unit downstream of the plasma generation unit, with the gas flow path being... Figure 11B The thick arrow 1 in the diagram indicates this. Therefore, the air leaving the plasma generation unit flows directly into the catalytic unit (i.e., it does not enter the ambient air). (See above reference.) Figure 1-4 The plasma generation unit is used to decompose toluene molecules contained in the supply gas stream, wherein the effluent gas stream from the plasma generation unit includes toluene that has not been decomposed by the plasma generation unit, partially oxidized VOCs generated from the decomposition of toluene, and long-lived plasma substances (e.g., O, O2 (Al)). ), OH, HO2) and plasma byproducts (e.g. O3, NO) X The plasma generation unit is also used to charge the solid and / or liquid air pollutants in the supply gas stream through the interaction between solid and / or liquid air pollutants and charged substances (e.g., free electrons, hydroxyl ions, oxygen radicals, etc.) formed by the plasma generation unit. In the effluent gas stream of the plasma generation unit, the concentration and characteristics of toluene, VOC decomposition products, and plasma byproducts are functions of the operating conditions of the plasma generation unit (as mentioned above). Figure 5 And the following text about Tables 1-3 and Figure 12 and 13 (As discussed).

[0190] Then, Figure 11BThe outflow gas from the plasma generation unit is conveyed to the catalytic unit. The catalytic unit is provided to catalyze the decomposition of one or more of toluene, toluene decomposition products, and plasma byproducts contained in the outflow gas from the plasma generation unit before the air is discharged into the ambient air. Similar to... Figure 11A The arrangement, by positioning the catalytic unit downstream of the plasma generation unit, maintains a long-lived plasma material (e.g., O, O2 (Al)) outside the plasma discharge region of the plasma generation unit. Plasma (e.g., OH, HO2) can reach the catalytic unit. In the presence of a catalyst in the catalytic unit, these long-lived plasma materials can increase the conversion of toluene and other partially oxidized VOCs on the catalyst surface and decompose plasma byproducts on the catalyst surface. The catalytic unit can operate at room temperature or higher, depending on the required energy consumption and the balance of conversion. Therefore, the plasma generation unit and the catalytic unit work together to provide an airflow with reduced VOC concentrations and in compliance with WHO guidelines on ozone and nitrogen oxides. This airflow still contains charged liquid and / or solid air pollutants to be collected by the collection unit, but these may now be released into the ambient air.

[0191] exist Figure 11C The system also includes a catalytic unit connected to the plasma generation unit and an adsorption unit connected to the plasma generation unit. The catalytic unit is located directly downstream of the plasma generation unit, and the adsorption unit is located downstream of the catalytic unit. The gas flow path is... Figure 11C The thick arrow 1 in the image indicates this. It is understandable that... Figure 11C The order of the catalytic and adsorption units can be switched, allowing the adsorption unit to be positioned between the plasma generation unit and the catalytic unit. (See above reference.) Figure 1-4 The plasma generation unit is used to decompose toluene molecules contained in the supply gas stream, wherein the effluent gas stream from the plasma generation unit includes toluene that has not been decomposed by the plasma generation unit, partially oxidized VOCs generated from the decomposition of toluene, and long-lived plasma substances (e.g., O, O2 (Al)). ), OH, HO2) and plasma byproducts (e.g. O3, NO) X The plasma generation unit is also used to charge the solid and / or liquid air pollutants in the supply gas stream through the interaction between solid and / or liquid air pollutants and charged substances (e.g., free electrons, hydroxyl ions, oxygen radicals, etc.) formed by the plasma generation unit. In the effluent gas stream of the plasma generation unit, the concentration and characteristics of toluene, VOC decomposition products, and plasma byproducts are functions of the operating conditions of the plasma generation unit (as mentioned above). Figure 5 And the following text about Tables 1-3 and Figure 12 and13 (As discussed).

[0192] Figure 11C The functions of the catalytic and adsorption units are as described above. Figure 11A and 11B Advantageously, any toluene not decomposed by the plasma generation unit, partially oxidized VOCs generated from toluene decomposition, and long-lived plasma substances (e.g., O, O2 (Al)) flow into the adsorption unit via the outflow gas from the catalytic unit. ), OH, HO2) and plasma byproducts remaining in the gas flow (e.g. O3, NO) X The airflow can be adsorbed onto the adsorbent within the adsorption unit before it is released into the ambient air. When the airflow is released into the ambient air, it still contains charged liquid and / or solid air pollutants collected by the collection unit.

[0193] Despite Figure 11C The adsorption and catalytic units are shown as separate units, but the adsorption and catalytic units can be combined into a single unit by doping a catalyst onto the adsorbent contained within the adsorption unit. In this way, the oxidation of adsorbed compounds, including VOCs, VOC decomposition products, and plasma byproducts, can be accelerated compared to an adsorbent without catalyst doping.

[0194] When the system includes an adsorption unit and / or a catalytic unit, the system can be configured to operate under continuous storage-discharge operation, wherein air flows through the plasma generation unit and the adsorption unit and / or catalytic unit once before leaving for ambient air. Advantageously, this can increase the flow rate of ambient air that can be introduced into the plasma.

[0195] Alternatively, when the system includes an adsorption unit and / or a catalytic unit, the air purification device can be configured to operate under a cyclic storage-discharge operation, wherein a portion of the air leaving the adsorption unit and / or catalytic unit is recirculated back into the plasma generation unit before leaving the ambient air. Advantageously, this can increase the total VOC conversion achieved by the system.

[0196] Reference Example

[0197] Table 1 contains data from experiments investigating the formation of plasma byproducts in a microplasma generator using a pulsed DC-supplied microplasma generator. The plasma generator comprised two perforated plate electrode components with a 200 μm thick alumina dielectric coating separated by a 100 μm discharge gap; no catalyst was present within the dielectric coating. The electrode components had a diameter of 58.4 mm and a thickness of 1.4 mm. The perforations, with a diameter of 2.6 mm, were arranged in a regular hexagonal array at 5 mm intervals, providing an opening area of ​​24.6%. Dry, VOC-free ambient air (relative humidity <1%) was supplied to the plasma generator at a flow rate of 5 L / min.

[0198] Tests 1-15 in Table 1 correspond to different pulse DC parameters with varying voltage, frequency, and pulse width. The concentrations of ozone (O3), nitric oxide (NO), and nitrogen dioxide (NO2) (plasma byproducts) in the effluent gas stream of the plasma generator were measured, along with the current amplitude and power consumption of the plasma generator. This was achieved using the following relationship... The power consumption is calculated by integrating the product of voltage and current pulses over time within one cycle, where T is the cycle time, and V(t) and I(t) are the applied voltage and current, respectively.

[0199] The tests in Table 1 can be roughly divided into three operating regions. The first region covers tests 1-9, where the DC power supply voltage is in the range of 0.9-1.1 kV, and plasma is generated without plasma byproducts (i.e., no O3, NO, or NO2 is formed within the plasma generation unit). The second region covers tests 10 and 12, where pulsed DC power supplies at 1.2 kV with frequencies of 1 kHz and 50 kHz, respectively, generate plasma, where O3 is formed but NO is not. X The third region covers tests 11 and 13-15, and due to the high free electron energy generated by the pulsed DC parameters of tests 11 and 13-15, O3 and NO are formed within the plasma. X This makes it easier for nitrogen to dissociate and lead to NO. X The existence of the second region indicates that O radicals can be selectively formed within the plasma generation unit, while suppressing the formation of N radicals.

[0200] Table 2 contains experimental data for micro-plasma generation units using pulsed DC power and catalytic micro-plasma generation units using pulsed DC power to investigate the formation of plasma byproducts in the plasma generation units. VOC-free, humid ambient air (approximately 50% relative humidity) was supplied to the plasma generation units at a flow rate of 5 L / min. The micro-plasma generation units used in tests 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, and 44 were the same as those used in tests 1-15 of Table 1. The catalytic micro-plasma generation units (used in tests 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, and 43) were the same as those used in tests 1-15 of Table 1, but the dielectric coating also included a MnO2 catalyst. The manganese dioxide catalyst was incorporated into the alumina-coated electrode of the catalytic micro-plasma generation unit using a wet impregnation technique. The catalyst precursor, manganese(II) nitrate tetrahydrate, was dissolved in water with a volume equal to the pore volume of the alumina coating. The amount of precursor in the solution was based on the mass of the desired metal element (10 wt% Mn) per mass of Al₂O₃. Capillary action drew the precursor solution into the pores. The impregnated electrode was dried in an oven at 110°C for 30 minutes to remove water, and then calcined at 450°C for 2 hours with a heating and cooling rate of 2°C / min. This calcination process converted the manganese nitrate precursor into manganese dioxide.

[0201] Plasma discharge in humid ambient air exhibits a strong tendency towards instability, thus byproduct formation is more likely to occur in humid air than in dry air under the same pulsed DC parameters. Considering the micro-plasma generation unit test results, it is evident that, under the same pulsed DC parameters, the humid air test resulted in significantly higher concentrations of O3, NO, and NO2 compared to the dry air test in Table 1. Furthermore, for humid air, the first and second regions in Table 1 no longer exist within the voltage range studied in the tests in Table 2: O3 and NO... X It forms at voltages as low as 0.7 kV. In contrast, in the case of dry air, the plasma generation unit only generates O3 and NO at voltages greater than or equal to 1.2 kV. X The explanation for the behavior observed in humid air is that the presence of water in the discharge gap alters the formation of O3 and NO within the plasma. X The reaction mechanism and reaction rate. In particular, the formation of free radicals O and OH within the plasma (which can act as O3 and NO) X (The precursor) is expected to contribute to the release of O3 and NO in the air leaving the plasma generation unit. XHigher concentrations were observed. Many tests using the catalytic microplasma generator unit (Table 2) resulted in O3 concentrations in the plasma generator unit effluent exceeding the WHO guidelines for O3 exposure levels, namely an 8-hour daily maximum of 100 μg / m³. 3 (51 ppb) and the average of the daily maximum time-weighted average of O3 concentrations over 8 hours during the 6-month peak season was 60 μg / m³. 3 (31 ppb) (World Health Organization. (2021). WHO Global Air Quality Guidelines: Particulate Matter (PM2.5 and PM10), Ozone, Nitrogen Dioxide, Sulfur Dioxide and Carbon Monoxide: Executive Summary. World Health Organization).

[0202] However, under the same or similar conditions, the tests in Table 2 using the catalytic microplasma generator resulted in significantly lower plasma byproduct concentrations than those using the microplasma generator. In tests 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, and 43, no O3 was detected in the plasma generator effluent stream, even at voltages as high as 1 kV. Although NO and NO2 were detected in the plasma generator effluent stream, their concentrations were consistently lower than those observed with the microplasma generator operating under the same or similar conditions, typically by an order of magnitude or more. The conclusion of the comparison of tests using the microplasma generator and the catalytic microplasma generator in Table 2 is that when humid air is supplied to the catalytic microplasma generator, the MnO2 catalyst within the dielectric layer catalyzes the decomposition of O3, NO, and NO2 formed within the plasma.

[0203] Table 3 contains data for Reference Examples 1-5 on the decomposition of toluene contained in the feed gas stream of the plasma generation unit using a catalytic microplasma generation unit, and for Reference Examples 6-9 on the decomposition of toluene contained in the feed gas stream of the plasma generation unit using a microplasma generation unit. The catalytic microplasma generation unit and the microplasma generation unit used in the reference examples are the same as those described above with respect to Tables 1 and 2. Moist ambient air (approximately 50% relative humidity) containing 1 ppm toluene is supplied to the plasma generation unit at a flow rate of 5 L / min. The electrode components are supplied with pulsed DC from a power source, wherein the reference examples in Table 3 cover a range of pulsed DC parameters (voltage, frequency, pulse width).

[0204] In low-energy plasma discharges, such as those generated in micro-plasma generation units, toluene is oxidized to CO2 and water through a series of reactions with electrons and active free radicals (O, H, OH) and N2. However, alternative reaction mechanisms for toluene oxidation are provided by supplying a catalyst within the plasma discharge.

[0205] Reference Examples 6-9 in Table 3 show that, when operating under ambient conditions, the micro-plasma generation unit can achieve over 70% toluene decomposition and minimize (<1 ppb) the formation of O3, NO, and NO2. However, Figure 12 Chromatograms of the feed and effluent streams from the plasma generation unit of Reference Example 6 (0.9 kV, 25 kHz, 1 μs, 97.9% toluene conversion) are provided, and these chromatograms illustrate the presence of a range of partially oxidized VOC compounds in the effluent stream. The partially oxidized VOCs present include benzene, phenol, and o-xylene, with toxicities substantially similar to toluene contained in the plasma generation unit feed, as well as less toxic acetone and ethanol. The formation of these partially oxidized VOCs at concentrations up to 0.1 ppm indicates that if the catalyst is not incorporated into the dielectric layer of the micro-plasma generation unit, an adsorption bed needs to be integrated into the air purification device downstream of the micro-plasma generation unit.

[0206] Considering Reference Examples 1-5 in Table 3, which relate to the catalytic microplasma generation unit according to this disclosure, it can be seen that improved toluene conversion and reduced plasma byproduct formation are achieved. Since the plasma method is non-selective, the presence of a catalyst can improve reaction selectivity by favoring certain reaction pathways. For example, considering the formation of O3 within the plasma, O3 does not react directly with toluene but readily decomposes in the presence of a MnO2 catalyst, generating oxygen free radicals with high oxidizing activity that will react with toluene.

[0207] Furthermore, the energy consumption of the catalytic microplasma generation unit is approximately an order of magnitude lower than that of the microplasma generation unit. This power reduction can be attributed to the increased capacitance of the electrode components when the dielectric-coated alumina substrate is impregnated with the catalyst (the capacitance of the electrode components increases to 100 pF, compared to 20 pF for the electrode components of the microplasma generation unit) and the lower activation energy of the reaction mechanism that occurs in the presence of the catalyst. The reference examples in Table 3 show a wide operating window with pulse widths ranging from 0.6 to 30 μs at 0.9 kV and 25 kHz pulsed DC.

[0208] also, Figure 13 Chromatograms of the feed and effluent gas streams from the plasma generation unit of Reference Example 1 (0.9 kV, 25 kHz, 1 μs, 99.8% toluene conversion) are provided, showing much lower concentrations (indicated by peak size) and ranges of partially oxidized VOCs present in the effluent gas stream of the catalytic microplasma generation unit. Only benzene, ethanol, acetone, and phthalic anhydride were identified, all at very low concentrations (<0.01 ppm).

[0209] Comparing Reference Examples 1-5 and Reference Examples 6-9 in Table 3, it is clear that the catalytic microplasma generation unit can provide higher conversion, lower by-product formation (plasma by-products and partially oxidized VOCs) and lower power consumption than microplasma generation units operating under the same conditions.

[0210] Suitable implementations employ, for example, a catalytic plasma generating unit according to one of Reference Examples 1-5 or a plasma generating unit according to one of Reference Examples 6-9, and combine such a (catalytic) plasma generating unit with a collection unit, such as an electrostatic precipitator or an electrostatic filter medium, which is located downstream of the (catalytic) plasma generating unit along the airflow path.

[0211] Table 1

[0212]

[0213] Table 2

[0214]

[0215] Table 3

[0216]

[0217] The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, are expressed in their particular form or according to means for performing the disclosed functions, or methods or processes for obtaining the disclosed results, and may, where appropriate, be used alone or in any combination of these features to implement the invention in its various forms.

[0218] While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art upon presentation of this disclosure. Therefore, the exemplary embodiments set forth above are to be considered illustrative rather than restrictive. Various changes may be made to the described embodiments without departing from the spirit and scope of the invention.

[0219] To avoid any doubt, any theoretical explanations provided herein are intended to enhance the reader's understanding. The inventor does not wish to be bound by any of these theoretical explanations.

[0220] Any chapter headings used in this article are for organizational purposes only and should not be construed as limiting the subject matter described.

[0221] Throughout this specification, including the following claims, unless the context otherwise requires, the words “comprising” and “including”, as well as variations such as “comprising,” “including,” and “including,” shall be understood to imply inclusion of the said integer or step or group of steps, but not to exclude any other integer or step or group of steps.

[0222] It should be noted that, as used in the specification and appended claims, the singular forms “a,” “an,” and “the” include plural indicators unless the context clearly specifies otherwise. A range may be expressed herein as from “about” a particular value and / or to “about” another particular value. When expressing such a range, another embodiment includes from one particular value and / or to another particular value. Similarly, when a value is expressed as an approximation using the antecedent “about,” it should be understood that the particular value forms another implementation. The numerical term “about” is optional and means, for example, + / - 10%.

Claims

1. An air purification system for purifying ambient air, the air purification system comprising: The plasma generation unit is configured to generate plasma in ambient air to charge air pollutants therein, thereby providing charged air pollutants. and A collection unit is configured to collect the charged air pollutants by electrostatic attraction between at least a portion of the collection unit and the charged air pollutants.

2. The air purification system according to claim 1, wherein, The plasma generation unit is configured not to generate ozone.

3. The air purification system according to any one of the preceding claims, wherein, The plasma generation unit is configured to generate microplasma.

4. The air purification system according to any one of the preceding claims, wherein, The plasma generation unit is a dielectric barrier discharge plasma generation unit.

5. The air purification system according to claim 4, wherein, The dielectric barrier discharge plasma generation unit includes: A first electrode component, the first electrode component comprising a conductive core and a dielectric coating; and A second electrode component is disposed relative to the first electrode component so as to generate plasma between the first electrode component and the second electrode component when a plasma generation voltage is applied between the first electrode component and the second electrode component, such that, in use, VOCs in ambient air are decomposed in the plasma generation unit to form VOC decomposition products and plasma byproducts.

6. The air purification system according to claim 5, wherein, The dielectric coating includes a catalyst that catalyzes the decomposition of one or more of the following: The VOC; The VOC decomposition products; and The plasma byproducts.

7. The air purification system according to claim 6, wherein, The dielectric coating comprises a metal oxide, optionally one or more of MnO2, Al2O3, CeO2, SiO2, and TiO2.

8. The air purification system according to any one of claims 5 to 7, wherein: The plasma generation unit further includes a power supply connected to the first electrode component or the second electrode component; and The power source is configured to deliver pulsed DC to the electrode components to which the power source is connected, so as to generate plasma between the first electrode component and the second electrode component.

9. The air purification system according to claim 8, wherein, The power supply is configured to deliver pulsed DC to each electrode component to which the power supply is connected, wherein the pulsed DC received by each electrode component is: An electric field strength with an applied voltage greater than or equal to 0.3 kV and less than or equal to 1.9 kV is generated between the electrode component and the adjacent electrode component; It has a pulse frequency greater than or equal to 0.5 kHz and less than or equal to 100 kHz; and It has a pulse width greater than or equal to 0.05 μs and less than or equal to 50 μs.

10. The air purification system according to any one of the preceding claims, wherein, The collection unit includes an electrostatic precipitator.

11. The air purification system according to claim 10, wherein, The electrostatic precipitator includes: One or more main collection elements; and A main voltage source, configured to supply a positive DC voltage to the one or more main collector elements; This allows negatively charged air pollutants to be electrostatically attracted to the main collection element during use.

12. The air purification system according to any one of claims 1 to 9, wherein, The collection unit includes an electrostatic filter medium.

13. The air purification system according to claim 12, wherein, The electrostatic filter medium includes one or more regions with positive static charge, separated from one or more regions with negative static charge.

14. The air purification system according to any one of the preceding claims, wherein: The plasma generation unit is included in the plasma generation device; The collection unit is included in the collection device; and The plasma generating device is separate from the collecting device, allowing the devices to be positioned independently of each other.

15. An air purification device, comprising: Air inlet; Air outlet; and The air purification system according to any one of claims 1 to 13; In use, ambient air flows along an air path that enters the device through the air inlet, passes through the air purification system, and exits the device through the air outlet.

16. The air purification device according to claim 15, wherein, The plasma generation unit is positioned upstream of the collection unit along the air path through the device.

17. The air purification device according to claim 16, wherein, The device also includes a particulate filter positioned upstream of the plasma generation unit along the air path through the device.

18. The air purification device according to claim 15, wherein, The plasma generation unit is positioned downstream of the collection unit along the air path through the device.

19. A method for treating ambient air using an air purification system to reduce the concentration of air pollutants therein, the system comprising: Plasma generation unit; and Collection unit; The method includes the following steps: An airflow containing air pollutants is passed through the plasma generation unit; The plasma generation unit is used to generate plasma in ambient air to charge air pollutants, thereby providing charged air pollutants; and An airflow containing the charged air pollutants is passed through the collection unit to collect the charged air pollutants by electrostatic attraction between at least a portion of the collection unit and the charged air pollutants.

20. A method for treating ambient air using an air purification system to reduce the concentration of air pollutants therein, the system comprising a plasma generating unit, the method comprising the following steps: An airflow containing particulate air pollutants is passed through the plasma generation unit; as well as The plasma generation unit is used to generate plasma in the ambient air to charge the particulate air pollutants, thereby providing charged air pollutants. The particulate air pollutants present in the airflow include solid and / or liquid particles having an aerodynamic diameter of at least 0.1 micrometers.

21. Use of a plasma generated in ambient air by a plasma generation unit to charge air pollutants in order to provide charged air pollutants for subsequent collection in a collection unit, the air pollutants being entrained in an ambient air stream incident on the plasma generation unit, and the charged air pollutants being conveyed to the collection unit by the stream.

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