Patent Publication Number: US-2023151983-A1

Title: Air purifier and air purifying method

Description:
This application claims priority to Korean Patent Application No. 10-2021-0157101, filed on Nov. 15, 2021, and all the benefits accruing therefrom under 35 U.S.C. § 119, the content of which in its entirety is herein incorporated by reference. 
     BACKGROUND 
     1. Field 
     Embodiments of the invention relate to air purifiers and air purifying methods for purifying air including fine dust and pollutants. 
     2. Description of the Related Art 
     An air purifier purifies air by capturing or decomposing a gas, for example, fine dust or pollutants in the air. An air purifier may be included in industrial dust capturing equipment, air conditioning/ventilation systems in buildings, etc. 
     Representative methods of removing fine dust and pollutants in the art include a filter method and an adsorption method. In the filter method, fine dust and pollutants from the air are captured by a filter. In the adsorption method, fine dust and pollutants from the air are captured by an activated carbon-based adsorbent having a large predetermined surface area. The filter method and the adsorption method have excellent fine dust and pollutant removal efficiency, and may filter out various types of fine dust and pollutants from the air. 
     SUMMARY 
     An increase in the amount of fine dust captured in a filter or an adsorbent may degrade the performance of the filter and the adsorbent and increase the pressure drop in the filter. Thus, there is a difficulty in terms of periodically managing or replacing the filter and the adsorbent. 
     Provided are air purifiers and air purifying methods, which remove fine dust and pollutants may be removed by a gas-liquid mixture and a gas-liquid contact. 
     Provided are air purifiers and air purifying methods, which do not desire to periodically replace or maintain a pollutant removing unit. 
     Provided are air purifiers and air purifying methods, which have improved pollutant removal performance. 
     Additional features will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments of the invention. 
     According to an embodiment of the invention, an air purifier includes an air inlet portion through which polluted air flows in, a plasma reaction portion connected to and in fluid communication with the air inlet portion and including a discharge region generating discharge plasma, a gas-liquid mixing portion connected to and in fluid communication with the plasma reaction portion, and including a gas-liquid mixing portion housing, a droplet spraying device arranged in the gas-liquid mixing portion housing and including at least one spray nozzle spraying fine droplets, and a fluid mixing device which mixes the fine droplets with first purified air transferred from the plasma reaction portion, and a gas-liquid contact portion connected to and in fluid communication with the gas-liquid mixing portion, defining micro-channels through which a gas-liquid mixture fluid transferred from the gas-liquid mixing portion passes, and including an impactor which captures droplets from the gas-liquid mixture fluid. 
     In an embodiment, the gas-liquid mixing portion and the gas-liquid contact portion may be sequentially arranged in an opposite direction to a gravity direction, and the air purifier may further include a fluid communication portion extending in the gravity direction and arranged between the gas-liquid mixing portion and the gas-liquid contact portion. 
     In an embodiment, the fluid communication portion may include a vortex finder. 
     In an embodiment, the at least one spray nozzle may be provided in plural, and a plurality of spray nozzles may be arranged apart from each other at predetermined distances in an upper portion of the gas-liquid mixing portion housing. 
     In an embodiment, the at least one spray nozzle may be provided in plural, and a plurality of spray nozzles may be arranged apart from each other at predetermined distances in a lower portion of the gas-liquid mixing portion housing. 
     In an embodiment, the at least one spray nozzle may be provided in plural, and a plurality of spray nozzles may be arranged apart from each other at predetermined distances on a side portion of the gas-liquid mixing portion housing. 
     In an embodiment, the impactor may include a porous member for capturing the droplets from the gas-liquid mixture fluid. 
     In an embodiment, the impactor may include a mesh screen arranged on a side surface of the housing and supporting the plurality of fillers. 
     In an embodiment, a porosity of the porous member may be about 0.5 or more. 
     In an embodiment, the gas-liquid contact portion may include a gas discharge portion through which an uncaptured gas from among the gas-liquid mixture fluid is discharged, wherein the gas discharge portion may be disposed along a direction different from a gravitational direction. 
     In an embodiment, the impactor may have one of a polyprism shape or a cylindrical shape. 
     In an embodiment, the impactor may have one of a square pillar shape or a cylindrical shape. 
     In an embodiment, a voltage of about 2 kilovolts (kV) to about 500 (kV) may be applied to the discharge region. 
     In an embodiment, the plasma reaction portion may include a plurality of dielectric particles arranged in the discharge region. 
     In an embodiment, the air purifier may further include a liquid collecting portion which collects a liquid discharged from the gas-liquid contact portion. 
     According to an embodiment of the invention, an air purifying method includes allowing polluted air to flow into a plasma reaction portion connected to be in fluid communication with an air inlet portion through which polluted air flows in and comprising a discharge region generating discharge plasma, purifying the polluted air into first purified air by the discharge plasma, generating a gas-liquid mixture fluid by mixing the first purified air with the fine droplets, capturing droplets from a gas-liquid mixture fluid transferred from a gas-liquid mixing portion connected to be in fluid communication with the plasma reaction portion, and discharging the captured liquid in a gravity direction and discharging a purified gas in a direction different from the gravity direction. 
     In an embodiment, the gas-liquid mixing portion and the gas-liquid contact portion may be sequentially arranged in an opposite direction to the gravity direction, wherein the air purifier further includes a fluid communication portion extending in the gravity direction and arranged between the gas-liquid mixing portion and the gas-liquid contact portion. 
     In an embodiment, the fluid communication portion may include a vortex finder. 
     In an embodiment, the air purifying method may further include collecting and purifying a liquid discharged from the gas-liquid contact portion and re-supplying the purified air to the droplet spraying device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features and advantages of predetermined embodiments of the invention will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
         FIG.  1    is a block diagram of an embodiment of an air purifier; 
         FIG.  2    is a schematic structural diagram of an embodiment of an air purifier; 
         FIG.  3    is an enlarged cross-sectional view of an embodiment of a portion of plasma reaction portion illustrated in  FIG.  2   ; 
         FIG.  4 A  is a perspective view of an embodiment of a gas-liquid mixing portion and a gas-liquid contact portion; 
         FIG.  4 B  is a schematic diagram of an embodiment of a gas-liquid mixing portion; 
         FIG.  4 C  is a schematic diagram of another embodiment of a gas-liquid mixing portion; 
         FIG.  4 D  is a schematic diagram of another embodiment of a gas-liquid mixing portion; 
         FIG.  5    is a perspective view of an embodiment of an impactor; 
         FIG.  6    is a schematic view illustrating an embodiment of a relationship between a liquid and a gas in an impactor; 
         FIG.  7 A  is a perspective view of an embodiment of an impactor; 
         FIG.  7 B  is a perspective view of an embodiment of an impactor; 
         FIG.  7 C  is a perspective view of an embodiment of an impactor; and 
         FIG.  8    is a perspective view of an embodiment of a gas-liquid mixing portion and a gas-liquid contact portion. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, in which like reference numerals refer to like elements throughout. In this regard, the embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the drawing figures, to explain features. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. 
     Hereinafter, embodiments of the disclosure are described in detail with reference to the accompanying drawings. In the drawings, like reference numerals in the drawings denote like elements, and the sizes of elements in the drawings may be exaggerated for clarity and convenience of description. 
     It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may be therebetween. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present. 
     It will be understood that, although the terms “first,” “second,” “third” etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, “a first element,” “component,” “region,” “layer” or “section” discussed below could be termed a second element, component, region, layer or section without departing from the teachings herein. 
     Furthermore, relative terms, such as “lower” or “bottom” and “upper” or “top,” may be used herein to describe one element&#39;s relationship to another element as illustrated in the Figures. It will be understood that relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. In an embodiment, when the device in one of the figures is turned over, elements described as being on the “lower” side of other elements would then be oriented on “upper” sides of the other elements. The exemplary term “lower,” can therefore, encompasses both an orientation of “lower” and “upper,” depending on the particular orientation of the figure. Similarly, when the device in one of the figures is turned over, elements described as “below” or “beneath” other elements would then be oriented “above” the other elements. The exemplary terms “below” or “beneath” can, therefore, encompass both an orientation of above and below. 
     “About” or “approximately” as used herein is inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (i.e., the limitations of the measurement system). The term “about” can mean within one or more standard deviations, or within ±30%, 20%, 10%, 5% of the stated value, for example. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the invention, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
       FIG.  1    is a block diagram of an embodiment of an air purifier.  FIG.  2    is a schematic structural diagram of an embodiment of an air purifier. 
     Referring to  FIGS.  1  and  2   , an air purifier  1  according to an example may include an air inlet (also referred to as an air inlet portion)  10  through which polluted air Air 1  flows in, a plasma reaction portion  20  connected to be in fluid communication with the air inlet  10  and purifying polluted air by discharge plasma, a gas-liquid mixing portion  30  connected to be in fluid communication with the plasma reaction portion  20  and mixing first purified air Air 2  with droplets by spraying the droplets, a fluid communication portion  40  arranged between the gas-liquid mixing portion  30  and the gas-liquid contact portion  50 , which is described below, and the gas-liquid contact portion  50  capturing droplets included in a gas-liquid mixture fluid Air 3  and separating purified gas Air 4  and liquid L 2  from each other. 
     In the illustrated embodiment, the plasma reaction portion  20 , the gas-liquid mixing portion  30 , and the gas-liquid contact portion  50  are sequentially arranged, but the invention is not limited thereto. In the air purifier  1  according to another example, the gas-liquid mixing portion  30 , the gas-liquid contact portion  50 , and the plasma reaction portion  20  may be sequentially arranged. 
     According to an example, the gas-liquid mixing portion  30  and the gas-liquid contact portion  50  may be sequentially arranged in a direction opposite to a gravitational direction (also referred to as a gravity direction) G. Here, the fluid communication portion  40  may extend in the gravitational direction G, and may be arranged between the gas-liquid mixing portion  30  and the gas-liquid contact portion  50 . The fluid communication portion  40  according to an example may be used as a movement path through which a mixture fluid moves from the gas-liquid mixing portion  30  to the gas-liquid contact portion  50 . 
     In the specification, the polluted air Ain refers to a mixture gas including the air and one or more of fine dust (also referred to as a particulate matter), a water-soluble volatile organic compound (“VOC”), and a water-insoluble VOC. In an embodiment, the fine dust may include small fine dust of about 10 micrometers (μm) or less and ultrafine dust of about 2.5 μm or less. In addition, the water-soluble VOC may include a volatile organic compound, and may include gaseous substances that may be captured in water or aqueous solution to be removed, for example, ammonia (NH 3 ), acetaldehyde (CH 3 CHO), acetic acid (CH 3 COOH). In addition, the water-insoluble VOC may include a volatile organic compound that is not captured in water or an aqueous solution, and may include, for example, benzene (C 6 H 6 ), formaldehyde (CH 2 O), toluene (C 6 H 5 CH 3 ), or the like. However, the invention is not limited thereto, and any gas other than the fine dust, the water-soluble VOC, and the water-insoluble VOC may be included in polluted air Air 1 . Hereinafter, each of the plasma reaction portion  20 , the gas-liquid mixing portion  30 , and the gas-liquid contact portion  50 , through which the polluted air Air 1  passes, will be described in detail. 
       FIG.  3    is an enlarged cross-sectional view of a portion of the plasma reaction portion  20  illustrated in  FIG.  2   . 
     Referring to  FIGS.  2  and  3   , the plasma reaction portion  20  according to an example may include a reactor  210  that is hollow and extends in one direction, a discharge plasma generator  220  generating a discharge plasma inside the reactor  210 , and a plurality of dielectric particles  230  arranged in a packed bed of the reactor  210 . 
     The reactor  210  defines a flow path of the polluted air Air 1 . In addition, a packed bed  211  in which the plurality of dielectric particles  230  is arranged is provided inside the reactor  210 . In an embodiment, the packed bed  211  may be a discharge region in which a discharge plasma is generated using the plasma reaction portion  20 . However, the invention is not limited thereto, and another region including the packed bed  211  may be a discharging region. 
     The reactor  210  according to an example extends in one direction and may have a hollow shape through which the polluted air Air 1  and a liquid may flow. In an embodiment, the reactor  210  may be provided as a glass conduit or an aluminum conduit extending in one direction. However, the invention is not limited thereto, and any hollow conduit capable of generating a discharge plasma may be used as the reactor  210 . 
     The discharge plasma generator  220  may include a first electrode  221  arranged on an outer wall of the reactor  210 , a second electrode  222  arranged inside the reactor  210 , and a high voltage generator  223 . The first electrode  221  according to an example may include a ground electrode, and the discharge region in which a discharge plasma may be generated may be surrounded by the first electrode  221 . In an embodiment, when the reactor  210  includes a conductor, the first electrode  221  may be integrated with the reactor  210 , and when the reactor  210  includes a non-conductor, the first electrode  221  may include a silver paste film and arranged to surround the outer wall of the reactor  210 , for example. 
     In addition, the second electrode  222  may include a power electrode, and may be arranged to be apart from the first electrode  221  with a predetermined interval therebetween in the discharge region where a discharge plasma may be generated. In an embodiment, the second electrode  222  may be provided as a steel wire extending in one direction and arranged inside the reactor  210 , for example. 
     Also, the high voltage generator  223  may apply a high voltage to the discharge region in which a discharge plasma may be generated. The high voltage generator  223  according to an example may include alternating current (“AC”) power supply of a sinusoidal waveform and a transformer. The high voltage generator  223  may continuously apply, through the above-described electric system, a high voltage into the reactor  210 , for example, to the discharge region in which a discharge plasma may be generated. In an embodiment, a voltage applied to the discharge region may be about 2 kilovolts (kV) or more and about 500 kV or less, and a frequency thereof may be about 10 hertz (Hz) or more and about 1000 Hz or less, but the invention is not limited thereto. In addition, a distance between the first electrode  221  and the second electrode  222  in the discharge region may be about 10 millimeters (mm) or more and about 100 mm or less, and accordingly, an electric field of about 2 kilovolts per centimeter (kV/cm) or more and about 5 kV/cm or less may be applied to the discharge region. 
     The plurality of dielectric particles  230  may be arranged in the packed bed  211  inside the reactor  210 . The plurality of dielectric particles  230  according to an example may be polarized to attract ionized pollutants. In an embodiment, the plurality of dielectric particles  230  may include a dielectric material that may be polarized in the discharge region generated by the discharge plasma generator  220 , for example. In an embodiment, the plurality of dielectric particles  230  may include a metal oxide or a metal nitride, for example, at least one of silicon oxide, boron oxide, aluminum oxide, manganese oxide, titanium oxide, barium oxide, copper oxide, magnesium oxide, zinc oxide, zirconium oxide, yttrium oxide, calcium oxide, nickel oxide, iron oxide, or at least one of combinations thereof. 
     In addition, In an embodiment, the plurality of dielectric particles  230  may form predetermined pores to adjust a period of time that the polluted air Ain remains in the reactor  210 . In an embodiment, the plurality of dielectric particles  230  may have a bead shape having a predetermined particle diameter, for example, an average diameter of about 1 mm or more and about 20 mm or less, for example. However, the invention is not limited thereto, and the plurality of dielectric particles  230  may also have other three-dimensional (“3D”) shapes such as an arbitrary cuboid. 
     In an embodiment, the water-soluble VOC may be directly decomposed using the discharge plasma generator  220 . In an embodiment, when a high voltage is applied to the packed bed  211  by the discharge plasma generator  220 , the water-soluble VOC may be decomposed using OH radicals (OH.). In an embodiment, when a high voltage is applied to the packed bed  211  by the discharge plasma generator  220 , oxygen (O 2 ) and water molecules (H 2 O) in the air around the second electrode  222  arranged inside the reactor  210  may be broken into a neutral ionized gas state (plasma state), and OH radicals (OH.) may be generated from among these ions. In an embodiment, acetic acid (CH 3 COOH), acetaldehyde (CH 3 CHO), and methane (CH 4 ) among the water-soluble VOCs may be decomposed into carbon dioxide (CO 2 ) and water (H 2 O) as shown in Reaction Formulae 1 to 3 below. Here, carbon dioxide (CO 2 ) and water (H 2 O), which are products of decomposition, may be discharged out of the reactor  210 . 
       CH 3 COOH+4OH+O 2 →2CO 2 +4H 2 O  [Reaction Formula 1]
 
       CH 3 CHO+6OH+O 2 →2CO 2 +5H 2 O  [Reaction Formula 2]
 
       CH 4 +4OH+O 2 →CO 2 +4H 2 O  [Reaction Formula 3]
 
     Also, In an embodiment, the water-insoluble VOC may be directly decomposed using the discharge plasma generator  220 . In an embodiment, when a high voltage is applied to the packed bed  211  by the discharge plasma generator  220 , the water-insoluble VOC may be decomposed using OH radicals (OH.). In an embodiment, when a high voltage is applied to the packed bed  211  by the discharge plasma generator  220 , oxygen (O 2 ) and water molecules (H 2 O) in the air surrounding the second electrode  222  arranged inside the reactor  210  may be broken into a neutral ionized gas state (plasma state), and OH radicals (OH.) may be generated from among these ions. In an embodiment, water-soluble organic toluene (C 6 H 5 CH 3 ) may be decomposed into carbon dioxide (CO 2 ) and water (H 2 O) by OH radicals (OH.). Here, carbon dioxide (CO 2 ) and water (H 2 O), which are products of decomposition, may be discharged out of the reactor  210 . 
     Also, in an embodiment, ozone (O 3 ) may be generated from oxygen (O 2 ) in the air by the discharge plasma generator  220 . When ozone (O 3 ) is generated inside the reactor  210 , the ozone (O 3 ) may be combined with fine droplets to be described later and used as ozone water. However, when a concentration of ozone (O 3 ) generated by the discharge plasma generator  220  exceeds a range that may be used as ozone water, an ozone decomposition catalyst filter (not shown) may be arranged at a rear end of the discharge plasma generator  220  to remove ozone (O 3 ). 
     As described above, by a decomposition method using the discharge plasma generator  220 , the polluted air Air 1  that has passed through the reactor  210  may be discharged as the first purified air Air 2 , from which some pollutants are removed. Here, the first purified air Air 2  may include ozone (O 3 ) of a predetermined concentration. 
       FIG.  4 A  is a perspective view of a gas-liquid mixing portion and a gas-liquid contact portion, according to an example.  FIG.  4 B  is a schematic diagram of a gas-liquid mixing portion according to an example.  FIG.  4 C  is a schematic diagram of a gas-liquid mixing portion according to another example.  FIG.  4 D  is a schematic diagram of a gas-liquid mixing portion according to another example. 
     Referring to  FIGS.  2  and  4 A , the gas-liquid mixing portion  30  according to an example may be connected to be in fluid communication with the plasma reaction portion  20 . Accordingly, the first purified air Air 2  passing through the plasma reaction portion  20  may be introduced into the gas-liquid mixing portion  30  to be mixed with fine droplets. In an embodiment, the gas-liquid mixing portion  30  may include a droplet spraying device  31  spraying fine droplets, a fluid mixing device  32  mixing fine droplets with the first purified air Air 2 , and a gas-liquid mixing portion housing  33 . 
     The droplet spraying device  31  may spray droplets, for example, water, into the gas-liquid mixing portion housing  33 . The droplet spraying device  31  may include at least one spray nozzle  310 . In an embodiment, water stored in a liquid collecting portion  80  is pressurized by a pump (not shown) and sprayed into the gas-liquid mixing portion housing  33  in the form of fine droplets, through the spray nozzle  310 , for example. In this process, some of fine dust contained in the first purified air Air 2  are captured in the droplets. Accordingly, a gas-liquid mixture fluid in which air and droplets are mixed may be formed or provided in the gas-liquid mixing portion housing  33 . 
     The plurality of spray nozzles  310  included in the droplet spraying device  31  according to an example may be arranged, as illustrated in  FIG.  4 B , in an upper portion of the gas-liquid mixing portion  30 , for example, in an upper portion of the gas-liquid mixing portion housing  33 , apart from each other with a predetermined interval therebetween. The plurality of spray nozzles  310  included in the droplet spraying device  31  according to an example may be arranged, as illustrated in  FIG.  4 C , in a lower portion of the gas-liquid mixing portion  30 , for example, in a lower portion of the gas-liquid mixing portion housing  33 , apart from each other with a predetermined interval therebetween. The plurality of spray nozzles  310  included in the droplet spraying device  31  according to an example may be arranged, as illustrated in  FIG.  4 D , on a side portion of the gas-liquid mixing portion  30 , for example, on a side portion of the gas-liquid mixing portion housing  33 , apart from each other with a predetermined interval therebetween. 
     As described above, the one or more spray nozzles  310  may be arranged in an arbitrary region of the gas-liquid mixing portion housing  33 . Accordingly, the fine droplets passing through the one or more spray nozzles  310  may be sprayed onto the arbitrary region of the gas-liquid mixing portion housing  33 . According to an example, the first purified air Air 2  that has passed through the plasma reaction portion  20  may be mixed with the fine droplets sprayed to the arbitrary region, to generate the gas-liquid mixture fluid Air 3 . 
     In the specification, the gas-liquid mixture fluid Air 3  is a fluid in which fine droplets and the first purified air Air 2 , which has passed through the plasma reaction portion  20 , are mixed. In addition, according to an example, when ozone (O 3 ) is included in the first purified air Air 2 , the gas-liquid mixture fluid Air 3  may include ozone (O 3 ) and fine droplets, for example, ozone water in which water droplets are combined. When ozone water is included in the gas-liquid mixture fluid Air 3 , by the oxidizing power of the ozone water, water pollutants included in the gas-liquid mixture fluid Air 3  may be removed and bacteria may be inactivated. 
     The fluid mixing device  32  may generate a fluid flow for mixing the first purified air Air 2  that has passed through the plasma reaction portion  20  and the fine droplets sprayed from the one or more spray nozzles  310 . In an embodiment, the fluid mixing device  32  may be a fluid pressurizing device that forms a vortex in the gas-liquid mixing portion housing  33 , for example. However, the invention is not limited thereto. In an embodiment, as illustrated in  FIG.  2   , when the plasma reaction portion  20 , the gas-liquid mixing portion  30 , and the gas-liquid contact portion  50  are sequentially arranged and movement paths of fluids are connected to each other, a pressure applying portion with respect to each of the plasma reaction portion  20 , the gas-liquid mixing portion  30  and the gas-liquid contact portion  50  may be integrated into one. In an embodiment, a pressure member  90  arranged in a discharge path of purified air, for example, a blower, may replace pressure applying portions with respect to the plasma reaction portion  20 , the gas-liquid mixing portion  30 , and the gas-liquid contact portion  50 , for example. The fluid mixing device  32  may not be arranged in the gas-liquid mixing portion  30 . 
     In an embodiment, the first purified air Air 2  flowing into the gas-liquid mixing portion housing  33  may form a vortex. In an embodiment, when a pressure is applied to move the first purified air Air 2  in a tangential direction of an inlet portion  330  provided in the gas-liquid mixing portion housing  33  as illustrated in  FIG.  4 A , the first purified air Air 2  may rotate at a very high speed along a sidewall of the gas-liquid mixing portion housing  33 , for example. Here, fine droplets sprayed from the one or more spray nozzles  310  may also rotate at a very high speed along the sidewall of the gas-liquid mixing portion housing  33 , together with the first purified air Air 2 . In an embodiment, the gas-liquid mixing portion housing  33  may be provided in a cylindrical shape. 
     According to an example, as the first purified air Air 2  and the fine droplets rotate at a very high speed along the side wall of the gas-liquid mixing portion housing  33  by a centrifugal force, a mixing rate of the first purified air Air 2  and the fine droplets may be increased. In an embodiment, the first purified air Air 2  and the fine droplets sprayed from the one or more spray nozzles  310  may rotate at a very high speed along the sidewall of the gas-liquid mixing portion housing  33 , for example. Here, a centrifugal force acts on the first purified air Air 2  and the fine droplets, and accordingly, the number of times of contact between the first purified air Air 2  and the fine droplets on the side wall of the liquid mixing portion housing  33  may be increased. Accordingly, the gas-liquid mixture gas-fluid Air 3  in which the fine droplets and the first purified air Air 2  are mixed may be generated easily. 
     A portion of the gas-liquid mixture fluid Air 3  may be combined with another gas-liquid mixture fluid Air 3  in a process of downward rotating along the sidewall of the gas-liquid mixing portion housing  33 . The gas-liquid mixture fluid Air 3  combined with other gas-liquid mixture fluids Air 3  and converted to a state of liquid L 1  having a predetermined mass or more may be moved to the liquid collecting portion  80 . 
     According to an example, the liquid L 1 captured in the liquid collecting portion  80  may include pollutants. In this case, an arbitrary purifier capable of purifying the pollutants captured in the liquid L 1 may be arranged in the liquid collecting portion  80 . The liquid L 1 , from which pollutants have been removed by the purifier arranged in the liquid collecting portion  80 , may be supplied to the droplet spraying device  31  by a pressure unit such as a pump (not shown) and reused. The gas-liquid mixture fluid Air 3  reaching the bottom of the gas-liquid mixing portion housing  33  without being combined with other gas-liquid mixture fluids Air 3  may be moved to the gas-liquid contact portion  50  through the fluid communication portion  40 . 
     The fluid communication portion (also referred to as fluid communication unit)  40  may be arranged between the gas-liquid mixing portion  30  and the gas-liquid contact portion  50  to transfer the gas-liquid mixture fluid Air 3  generated in the gas-liquid mixing portion  30 , to the gas-liquid contact portion  50 . In an embodiment, the fluid communication portion  40  may be provided as a hollow conduit extending in the gravitational direction. In an embodiment, when a vortex is formed or provided in the gas-liquid mixing portion housing  33  by the fluid mixing device  32  as described above, the fluid communication portion  40  may be a vortex finder, for example. In an embodiment, when the fluid communication portion  40  is provided as a vortex finder, a pressure drop may occur in an inner region of the bottom of the gas-liquid mixing portion housing  33 . Accordingly, the gas-liquid mixture fluid Air 3  may rise in a direction opposite to the gravitational direction and be transferred to the gas-liquid contact portion  50 . 
       FIG.  5    is a perspective view of an embodiment of an impactor.  FIG.  6    is a schematic view illustrating an embodiment of a relationship between a liquid and a gas in an impactor.  FIG.  7 A  is a perspective view of an embodiment of an impactor.  FIG.  7 B  is a perspective view of an embodiment of an impactor.  FIG.  7 C  is a perspective view of an embodiment of an impactor.  FIG.  8    is a perspective view of an embodiment of a gas-liquid mixing portion and a gas-liquid contact portion. 
     Referring to  FIGS.  2 ,  5  and  6   , the gas-liquid contact portion  50  according to an example may be connected to be in fluid communication with the gas-liquid mixing portion  30 , and may include an impactor  51  which captures droplets included in the gas-liquid mixture fluid Air 3  and a gas-liquid contact portion case  52 . In an embodiment, a plurality of micro-channels  510  may be defined in the impactor  51 . The gas-liquid mixture fluid Air 3  transferred from the gas-liquid mixing portion  30  may pass through the plurality of micro-channels  510 . In an embodiment, the gas-liquid contact portion case  52  may include an accommodation member for accommodating the impactor  51 . The gas-liquid contact portion case  52  according to an example may be provided in a cube shape as illustrated in  FIG.  4 A  or a cylindrical shape as illustrated in  FIG.  8   . In the gas-liquid contact portion case  52 , a discharge path  520  through which a gas is discharged to the outside, which will be described later, may be arranged. 
     The impactor  51  according to an example may include a porous member for capturing fine droplets included in the gas-liquid mixture fluid Air 3 . In an embodiment, the porous member filled in the impactor  51  may be a filling member in which a predetermined void is defined. In an embodiment, the porous member may include one or more of a porous foam block, a fine filler, or a porous mesh screen. In this case, the porosity of the porous member may be about 0.5 or more, for example. The plurality of micro-channels  510  defined in the impactor  51  may be defined by a spacing between porous members. Hereinafter, as a porous member provided in the impactor  51 , a fine filler and a porous mesh screen supporting the fine filler are described in an embodiment, but the invention is not limited thereto. 
     In an embodiment, the impactor  51  may include a housing  530 , a plurality of fillers  550  filled in the housing  530 , and a mesh screen  570  supporting the plurality of fillers  550 . The housing  530  according to an example may be provided in a cuboid frame structure. The plurality of fillers  550  may include, for example, beads. The beads may include, for example, glass, metal, or the like. The diameters of the plurality of beads may be uniform or non-uniform. The plurality of beads may be regularly or irregularly packed inside the housing  530 . The plurality of beads may be stacked in one or more layers along a flow direction of the gas-liquid mixture fluid Air 3 , for example, the gravitational direction G. The micro-channels  510  may be defined by voids between the plurality of beads. A bead according to an example may be a spherical bead as illustrated in  FIG.  6   . The plurality of beads may have the same diameter. The plurality of beads may be packed in various forms inside the housing  530 . The packing form of the plurality of beads may be various as, for example, a cubic structure such as a primitive centered cubic (“PCC”) structure, a face centered cubic (“FCC”) structure, a body centered cubic (“BCC”) structure, and a hexagonal structure such as a hexagonal closed-packed (“HCP”) structure, or the like. 
     According to an example, a surface of the fillers  550  may be treated to have non-affinity with respect to the droplet such droplets may be easily separated from the surface of the fillers  550 . In an embodiment, the surface of the fillers  550  may be hydrophobic-treated, for example. To expand a hydrophobic-treated surface area, the surface of the fillers  550  may have a concave-convex shape before hydrophobic treatment. 
     The housing  530  according to an example may include a fluid inlet portion  531  through which the gas-liquid mixture fluid Air 3  is introduced and a liquid L 2  is discharged according to the gravitational direction G and a gas discharge portion  532  through which the gas Air 4  not captured by the porous member from among the gas-liquid mixture fluid Air 3  is discharged. In an embodiment, the fluid inlet portion  531  may be arranged in the gravitational direction G, for example, in a lower surface portion of the housing  530 , such that the gas-liquid mixture fluid Air 3  is introduced therein and the liquid L 2  is discharged therethrough. Here, the gas discharge portion  532  may be arranged in a direction different from the gravitational direction G, for example, in a side surface portion of the housing  530 , such that the gas Air 4  may be discharged therethrough. An upper surface portion of the housing  530  may be provided as a sealed plate  580  so that the gas-liquid mixture fluid Air 3  does not leave the impactor  51 . However, the invention is not limited thereto, and the gas discharge portion  532  may also be arranged on the upper surface portion of the housing  530  so that the gas Air 4  may be discharged therethrough. 
     In an embodiment, the impactor  51  may have one of a polyprism shape or a cylindrical shape. In an embodiment, when the impactor  51  has a pentagonal prism shape as illustrated in  FIG.  7 A , the housing  530  may also have a pentagonal prism shape, for example. Here, the fluid inlet portion  531  may be arranged on the lower surface portion of the housing  530 . Also, the gas discharge portion  532  may be arranged on five side surface portions of the housing  530 . In addition, when the impactor  51  has a hexagonal prism shape as illustrated in  FIG.  7 B , the housing  530  may also be provided in a hexagonal prism shape. The fluid inlet portion  531  then may be arranged on the lower surface portion of the housing  530 . Also, the gas discharge portion  532  may be arranged on six side surface portions of the housing  530 . When the impactor  51  has a pentagonal prism shape as illustrated in  FIG.  7 C , the housing  530  may also have a cylindrical shape. Here, the fluid inlet portion  531  may be arranged on the lower surface portion of the housing  530 . Also, the gas discharge portion  532  may be arranged the side surface portion of the housing  530 . 
     In an embodiment, the mesh screen  570  may be arranged on the gas discharge portion  532 . According to an example, the mesh screen  570  may be processed to have non-affinity with respect to the liquid L 2 . Accordingly, clogging of the pores of the mesh screen  570  due to a liquid may be prevented. 
     As described above, according to an example, the gas-liquid mixture fluid Air 3  transferred from the gas-liquid mixing portion  30  passes through the micro-channels  510  defined by the plurality of fillers  550 . In this process, droplets are captured on the surface of the micro-channels  510 , that is, on the surface of the fillers  550 . The droplets fall in the gravitational direction G. The liquid L 2  that has fallen in the gravitational direction G may pass through the mesh screen  570  to be collected in the liquid collecting portion  80 . Here, the gas Air 4  that is not captured by the porous member among the gas-liquid mixture fluid Air 3  may be discharged through the gas discharge portion (also referred to as a gas discharge unit)  532 . Here, the gas Air 4  passing through the gas discharge unit  532  may be final purified air that has undergone all purification processes. The purified gas Air 4  discharged through the gas discharge portion  532  may be discharged to the outside through the discharge path  520  provided in the gas-liquid contact portion case  52 . Here, the pressure member  90 , for example, a blower, may apply pressure to the gas Air 4  so that the gas Air 4  is discharged in a direction opposite to the gravitational direction G. 
     According to an example, the liquid L 2  captured by the liquid collecting portion  80  may include pollutants. Here, an arbitrary purifier capable of purifying the pollutants captured in the liquid L 2  may be arranged in the liquid collecting portion  80 . The liquid L 2 , from which pollutants have been removed by the purifier arranged in the liquid collecting portion  80 , may be supplied to the droplet spraying device  31  by a pressure unit such as a pump (not shown) and reused. 
     According to the above-described embodiments of the air purifier and the air purifying method, fine dust and pollutants may be ionized or decomposed by discharge plasma, and captured in a liquid that passes through the gas-liquid mixing portion and the gas-liquid contact portion and then easily discharged from the air purifier. Accordingly, as fine dust and pollutants in the air are easily captured in a liquid and discharged to the outside, excellent pollutant removal performance may be realized. 
     In addition, the liquid in which fine dust and pollutants are captured is easily discharged from the air purifier, and thus, the burden regarding periodic maintenance or replacement of a pollutant purifying unit such as filters and absorbents may be reduced. 
     It should be understood that embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or advantages within each embodiment should typically be considered as available for other similar features or advantages in other embodiments. While embodiments have been described with reference to the drawing figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope as defined by the following claims.