Photocatalytic oxidation device for air treatment

Abstract

Disclosed herein is a photocatalytic oxidation device comprising a frame and a pair of opposing photocatalytic unit cells. An ultraviolet lamp is disposed within an interior chamber, and when activated, the ultraviolet lamp causes an oxidant to be produced at the unit cells. Air can pass through the holes of the unit cells and thus can move through the device. The device is structurally configured and dimensionally optimized to provide efficient photocatalytic activity without unduly restricting airflow.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 006,270, filed on April 7, 2020, and entitled “Photocatalytic Oxidation Device for Treatment of Air,” and U.S. Provisional Patent Application No. 62 / 883,410, filed on August 6, 2019, and entitled “Photocatalytic Oxidation Device for In-Line Treatment of Air,” each of which is incorporated herein by this reference in its entirety. Background Art

[0003] Conventional systems for treating ambient air and removing airborne particles include high-efficiency particulate air (HEPA) filtration systems. These systems use filters that need to meet specific HEPA requirements, such as being able to remove 99.97% of particles with a diameter greater than or equal to 0.3 μm in the air passing through the filter. Although HEPA filtration systems can be used to remove particles from the air, they are subject to all the limitations common to filtration systems, such as filters that clog over time and require constant monitoring and replacement. Filtration-based systems also cannot deactivate chemicals, remove undesirable gases, or remove smaller odor-causing molecules. In addition, while HEPA filtration systems can remove several airborne contaminants, they do not treat nearby surface contaminants.

[0004] Other systems may use activated carbon filters or electrostatic filters. While these filters can be used to enhance the ability to capture contaminants and improve filtration efficiency, they still involve the above-mentioned limitations common to filtration-based systems, such as filter replacement, degradation of filter performance over time, and inability to treat surface contaminants.

[0005] Other air purification systems, often called "ionizers," are designed to emit negative ions into the surrounding air. These ions attach to positively charged pollutants such as pollen and dust. The pollutants then become weighed down and are more likely to settle or be more easily captured in a collection plate. However, since many pollutants simply move to the floor or wall, rather than being destroyed or removed, they can reenter the air after the negative ions have dissipated or separated. If a collection plate is used, it must be cleaned or replaced regularly, as with any filtration system.

[0006] Other air purification systems are designed to use ultraviolet (UV) radiation to inactivate and / or degrade airborne pollutants. These systems may be referred to as UV germicidal irradiation or UVGI air purifiers. UV light is typically tuned to short-wave UV light (UV-C light). In operation, air is directed through the system and through one or more UV lamps, with the goal of using UV light to directly disinfect the air passing through. Although UVGI systems are able to destroy some pollutants rather than capture / filter all passing pollutants, they have limitations. For many bacteria and mold pollutants, especially spores, brief exposure to UV light is insufficient to effectively destroy pollutants. Some volatile organic compounds (VOCs) may also be resistant to UV energy, or worse, react to UV light in a way that makes them more harmful, or be exposed to nearby individuals.

[0007] Photocatalytic oxidation (PCO) air purifiers are somewhat similar to UV air purification systems in that they also use UV light. However, instead of using UV light to interact directly with passing pollutants, PCO systems direct UV light onto a catalyst material. Water molecules in the ambient air then interact with the UV light and the catalyst to produce a variety of oxidants such as hydroxyl radicals. The oxidants can then attack organic molecular pollutants and degrade them into less harmful substances.

[0008] Therefore, instead of capturing pollutants, PCO systems are able to destroy and remove pollutants from the treated environment. However, conventional PCO systems have several limitations. For example, the air passing through must be close enough to the catalyst so that the generated oxidant mixes with the air and contacts the pollutants in the air. Ideally, a portion of the generated oxidant should also continue through the catalyst and UV lamp so that the oxidant can reach nearby surfaces and also provide treatment for surface pollutants.

[0009] Therefore, several design decisions must be made with respect to the position of the catalyst material and the UV assembly relative to each other and relative to the position of the airflow path. If the contact between the air passing through and the catalyst material is insufficient, or if the irradiation of the catalyst material is insufficient, there will be a reduction in the generation of oxidant, a poor mixing of the oxidant with the air, or both, ultimately resulting in poor treatment of pollutants. On the other hand, excessive contact between the catalyst and the airflow path and / or between the UV assembly and the airflow path may unnecessarily restrict the airflow, which can increase the operating power requirements required to run the system and / or reduce the volumetric airflow through the system. Reduced airflow can hinder the treatment effect of the system, increase the time spent cleaning the target environment, and / or hinder the system's ability to discharge oxidant away from the catalyst, where it can treat surface pollutants.

[0010] Therefore, there is a continuing need for an improved PCO air purification system that is structurally configured and dimensionally optimized to provide efficient generation of oxidant and efficient mixing of oxidant with passing air while minimizing disturbance to airflow. SUMMARY OF THE INVENTION

[0012] A PCO device configured to enhance the performance of purifying ambient air is described herein. In one embodiment, the PCO device comprises a frame, a pair of cell panels disposed opposite to each other across the width of the frame, and a UV lamp disposed within an inner chamber defined by the frame and the cell panels. The cell panels comprise holes that allow air to flow into and through the inner chamber. At least the inner surface of the cell panels and the surface of the holes comprise a photocatalytic material, such as a photocatalytic coating.

[0013] The PCO device is structurally configured and dimensionally optimized to provide efficient irradiation of the photocatalyst, efficient generation of the oxidant, and efficient interaction between the gas flow and the photocatalyst without unduly restricting the gas flow path. The embodiments described herein are capable of providing efficient irradiation of the photocatalyst on a power basis (e.g., per watt used by the device), per volume basis (e.g., per cm occupied by the device), and per watt used by the device. 3 ) or both, providing more effective pollutant purification than conventional systems.

[0014] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an indicator of the scope of the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Various objects, features, characteristics and advantages of the present invention will become apparent and more readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings and the appended claims, all of which form a part of this specification. In the accompanying drawings, like reference numerals may be used to designate corresponding or similar parts in the various figures, and the various elements depicted are not necessarily drawn to scale, wherein:

[0017] Figure 1 shows an isometric view of an exemplary PCO unit;

[0018] Figure 2 shows a PCO unit in an exploded view;

[0019] Figure 3 The frame assembly of the PCO unit is shown;

[0020] Figure 4 shows a cross-sectional view of a PCO unit along a vertical plane perpendicular to the longitudinal axis;

[0021] Figure 5 shows a front view of a photocatalytic cell panel having an aperture;

[0022] Figure 6 shows a cross-sectional view of a PCO unit along a vertical plane aligned with the longitudinal axis;

[0023] Figure 7 A cross-sectional view of another embodiment of a PCO unit along a vertical plane perpendicular to the longitudinal axis is shown, wherein the PCO unit includes a reflector having an arcuate cross-sectional shape;

[0024] Fig. 8A and Figure 8B Different light reflection patterns of curved reflectors and corner reflectors are shown;

[0025] Fig. 9 and Fig.10 Alternative embodiments of reflectors having different cross-sectional shapes are shown; and

[0026] Fig.11 The different reflective characteristics of surfaces with different roughness are schematically shown. DETAILED DESCRIPTION OF THE INVENTION

[0028] Overview of Photocatalytic Oxidation Device

[0029] Figure 1 shows an isometric view of an exemplary PCO unit 100 configured for inline placement within an airflow path, and Figure 2 A PCO unit 100 is shown in an exploded view. For example, the PCO unit 100 can be placed within a duct system of a ventilation system, within a mobile air purification device, or as part of a larger air purification system with one or more additional air purification components. Sometimes, for convenience, the PCO unit 100 will be referred to as a PCO device 100 or simply as a unit 100 or device 100.

[0030] The PCO unit 100 has a length, height ("FI"), and width ("W") extending along a longitudinal axis 102. In use, the unit 100 is oriented such that the airflow path 104 is substantially perpendicular to the longitudinal axis 102, thereby allowing air to flow across the width of the device. For ease of describing the unit 100, the "vertical" axis is assumed to extend along the height of the device, while the "lateral" axis is assumed to extend along the width of the device.

[0031] The descriptors "upper," "lower," "right," "left," "front," "rear," "vertical," and "lateral" are used to facilitate describing the relative positions of the various components of the illustrated unit 100. However, it should be understood that the illustrated PCO unit 100 is not orientation-dependent, and thus in some applications, the "lower" side will not necessarily face the direction of gravity, and the longitudinal axis 102 will not necessarily be perpendicular to the ground.

[0032] The illustrated PCO unit 100 includes a frame 110. The frame 110 forms an upper side 115, a lower side 117, a left / first laterally extending side 116, and a right / second laterally extending side 118. The frame 110 is configured to hold a front cell plate 150 and preferably also a rear cell plate 151 (see, e.g., Figure 2 ). The longitudinally extending cell plates 150 and 151 extend between the laterally extending sides 116 and 118 and between the upper side 115 and the lower side 117 on opposite sides from each other. That is, one cell plate is located at the "front" of the device and one cell plate is located at the "back" of the device. In use, the cell plates 150 and 151 are intended to be oriented perpendicular to the airflow path 104. The left laterally extending side 116 can include an access hole 126 for routing wires (e.g., wires for UV lamps 124) to / from the device's internal chamber.

[0033] As shown, the frame 110 can be formed into a box shape, wherein the laterally extending edges of the upper side 115 and the lower side 117 abut the corresponding laterally extending edges of the laterally extending sides 116 and 118, and wherein the longitudinally extending edges of the upper side 115 and the lower side 117 abut the corresponding longitudinally extending edges of the cell plates 150 and 151. The frame 110 can also include one or more tabs 112 that help maintain the position of the cell plates 150 and 151. For example, one or more tabs can be connected to the longitudinally extending edge of the upper side 115 and can extend a distance toward the lower side 117, and / or one or more tabs can be connected to the longitudinally extending edge of the lower side 117 and can extend a distance toward the upper side 115.

[0034] The frame 110 may also include a reflector structure 114 (ie, a "reflective feature" or just a "reflector") extending longitudinally along a portion of the upper side 115. A similar reflector structure 113 may be included on the lower side 117 (see, e.g., Figure 2 ). The reflector structure 114 protrudes inwardly within the interior chamber of the frame 110 toward the UV lamp and serves to better direct the UV light onto the inner surfaces and holes of the unit cell panels 150 and 151.

[0035] The reflectors 113 and 114 may have a "convex" cross-sectional shape (from the perspective of the interior chamber), such as a V-shaped cross-sectional shape as shown in the illustrated embodiment. The reflectors 113 and 114 are preferably positioned so that the "peak" disposed most inwardly is aligned with and extends parallel to the UV lamps 124. The reflectors 113 and 114 are also preferably symmetrical about a vertical plane located on the longitudinal axis 102. Additional details about such a reflector structure 114 are described in U.S. Patent No. 9,867,897, which is incorporated herein by reference. Further improvements to the reflectors 113 and 114, including how they are sized and positioned relative to other components of the PCO unit 100, are described in more detail below.

[0036] refer to Figure 2 , the exploded view shows that one or more spacers, such as spacers 120 and 122, can be positioned within the interior chamber. Spacers 120 and 122 are configured to attach to UV lamp 124 and properly center the UV lamp within the interior chamber along longitudinal axis 102. As shown, when unit 100 is assembled, spacers 120 and 122 are positioned adjacent laterally extending sides 116 and 118 of frame 110, respectively.

[0037] In the illustrated embodiment, the UV lamp 124 includes a terminal coupler 125 that is configured to be inserted into the corresponding spacers 120 and 122. The terminal coupler 125 can be disposed at one or both ends of the UV lamp 124. The terminal coupler 125 includes a non-circular profile that is sized to fit into the corresponding slots in the spacers 120 and 122. The non-circular profile advantageously prevents rotation of the UV lamp 124. Wires can pass through the UV lamp 124, through the slots of the front spacer 120, and through the through-hole 126.

[0038] Although the illustrated embodiment includes a single UV lamp 124, other embodiments may include multiple UV lamps. For example, multiple lamps may be "vertically" stacked within the interior chamber, each parallel to the longitudinal axis 102, and / or may be positioned end-to-end along a direction parallel to the longitudinal axis 102.

[0039] Additional frame details

[0040] Figure 3 A portion of the frame 110 is shown with other components of the PCO unit 100 removed to better illustrate certain features of the frame 110. The frame 110 may include one or more holes 128 or other mounting features for receiving various fasteners, brackets, and / or other hardware known in the art for mounting or positioning the frame 110 in a desired location and orientation.

[0041] In the illustrated embodiment, the upper side 115, the second laterally extending side 118 and the lower side 117 of the frame 110 are connected together as a contiguous piece. The first laterally extending side 116 is formed as a separate piece that can be selectively attached to the upper side 115 and the lower side 117 relative to the second laterally extending side 118. This configuration provides several benefits for the functionality and manufacturability of the device. For example, the spacers 120 and 122 and the UV lamp 124 can be placed in their proper positions, and then the unit cell plates 150 and 151 can be easily slid into place by inserting them in the front and sliding them toward the second laterally extending side 118. Once in place, the first laterally extending side 116 can be attached to properly maintain the insertion feature and complete the complete assembly.

[0042] Reflectors 113 and 114 may also be integrally formed as part of the same continuous piece that forms upper side 115, second laterally extending side 118, and lower side 117 of frame 110. In this configuration, a single sheet of smooth stock material (e.g., aluminum, stainless steel, or other suitable metal) may be easily cut and bent / folded into a shape that forms the frame. For example, to form reflector 114, a pair of cuts 132 may be formed in upper side 115 to allow a portion of upper side 115 that forms reflector 114 to bend.

[0043] As shown, the cutouts 132 may extend from the rear edge 131 toward the front edge 130, but stop a distance before reaching the front edge 130, thereby allowing a portion of the rear edge to become a free edge 134 that can be manipulated to allow bending and forming of the reflector 114. Alternatively, the cutouts 132 may extend from the front edge 130 toward the rear edge 132. Therefore, it does not matter which side the cutouts 132 start from, as long as the free edge is formed to allow a portion of the upper side 115 disposed between the cutouts 132 to bend.

[0044] The bottom reflector 113 may be formed in the same manner as the upper reflector 114. The projection 112 may also be integrally formed with the same continuous piece of stock material used to form other components of a portion of the frame 110. Figure 3 Thus, forming the frame 110 can be easily accomplished by cutting a common raw material sheet into the appropriate size and shape and then bending it along the appropriate crease locations to form the frame 110. This can significantly reduce the number of manufacturing steps involved in forming the frame 110 while also providing a frame structure that easily lends itself to receiving and / or attaching to other components required to complete the complete assembly of the device.

[0045] Operation of the photocatalytic oxidation unit

[0046] In operation, the device is positioned according to the airflow path. The UV lamp 124 is powered and emits UV radiation toward the catalytic surfaces of the cell plates 150 and 151, thereby generating an oxidant. The oxidant then mixes with the passing air, and preferably at least some of the oxidant exits with the passing air and out of the unit 100.

[0047] Figure 41 is a cross-sectional view of the PCO unit 100 in which the section is taken along a plane perpendicular to the longitudinal axis 102 of the device. As air flows toward the device along the airflow path 104, it will first reach the front cell panel 150. After passing through the holes 152 of the front cell panel 150, the air will then enter and pass through the interior chamber 140. The air will then pass through the holes 152 of the rear cell panel 151 to move beyond the PCO unit 100 and into the target environment.

[0048] The unit cell plates 150 and 151 include a photocatalyst coating. The photocatalyst coating is disposed at least on the inner surface of the unit cell plates 150 and 151 facing the UV lamp 124. Preferably, the photocatalyst coating also extends into the hole 152 to coat the surface of the hole 152. The photocatalyst coating may include a metal oxide such as titanium oxide, and may optionally include one or more transition metals and / or transition metal alloys. Some examples of additional or alternative photocatalytic materials that can be used for the coating include graphene oxide, metal-organic frameworks (MOFs), other semiconductor materials, quantum dots, tantalite, other oxides (e.g., zinc, copper, iron, cadmium, tin, zirconium or gallium oxides), sulfides (e.g., zinc sulfide), silicon dioxide, and combinations thereof.

[0049] like Figure 4 As shown in the cross-sectional view of , reflectors 113 and 114 are positioned to reflect light toward the inner surfaces of the cell plates 150 and 151 and the aperture 152. Reflectors 113 and 114 are configured with an angle 136 that is set to optimize the amount of light reflected back toward the cell plates 150 and 151 rather than toward other portions of the interior chamber 140. Effective results have been achieved by setting angle 136 to about 30° to about 60°, or more preferably about 40° to about 50°, such as about 45°. Preferably, the opposite angles are also substantially equal, so that the reflector is symmetrical about a plane extending through the longitudinal axis.

[0050] Figure 4 The embodiment shown shows a reflector having a "V" shape in cross section. Other reflector embodiments may have other shapes, such as a semicircular shape having an arcuate cross section (e.g., Figure 7 ), the cross section is a combination or hybrid between a V and a semicircle (for example, Fig.10 ), other curved shapes (e.g., not necessarily circular in cross-section), or shapes where one portion is smooth / angled and another portion is curved (e.g., as Fig. 9 shown).

[0051] Here, the holes 152 are shown as being substantially horizontal (i.e., substantially perpendicular to the inner surface of the cell plate). In other embodiments, one or more of the holes may be angled, for example, from about 25° to about 65° to the inner surface of the cell plate. Angled holes are described in more detail in U.S. Pat. No. 9,867,897, which is incorporated herein.

[0052] Oxidants generated during operation of the device may include, for example, hydrogen peroxide, hydroxides, free oxygen molecules, superoxide ions, and ozone. Preferably, however, the PCO unit 100 is configured so that ozone generation is limited or eliminated. Although ozone is a strong oxidant, excessive amounts of ozone may cause respiratory irritation in sensitive individuals. It has been found that by customizing the PCO unit 100 to produce effective levels of oxidants while minimizing or eliminating ozone, effective purification performance is maintained without the potential harmful effects associated with excess ozone. In order to provide these performance characteristics, the UV lamp 124 preferably emits light having a wavelength of about 185nm to 254nm. The UV lamp 124 will typically be rated at about 5 to 30 watts.

[0053] Optimization of airflow and photocatalytic activity

[0054] The structural configuration of the PCO unit 100 is designed to provide efficient photocatalytic activity, efficient interaction between the gas flow and the generated oxidant, and efficient total volumetric gas flow. These functions interact with each other, and enhancing one of these functions may involve trade-offs with one or more of the other functions.

[0055] For example, photocatalytic activity can be enhanced by increasing the total surface area of ​​the UV lamps (e.g., using larger lamps) and / or by increasing the proportion of photocatalytic material within the airflow path. However, any of these changes may also increase the airflow resistance of the device, thereby reducing the volumetric airflow or requiring more power to maintain a higher pressure in the device. When the airflow through the PCO unit 100 is restricted, the air flow rate for a given room / environment is reduced, which means that it takes longer to purify the air or that more purification units are needed. Lower airflow also limits the distance that the generated oxidant can reach outside the unit 100, thereby limiting the surface that can be treated using the unit 100.

[0056] Similarly, airflow can be improved by limiting the contact between air and photocatalytic material, for example, only passing air through the photocatalyst instead of through multiple holes or increasing the size of the holes. However, this limits the interaction between air and the generated oxidant, thereby limiting the mixing and distribution of the oxidant in the air. For a given level of generated oxidant, the oxidant is therefore unlikely to contact and treat pollutants. Similarly, airflow can be improved by expanding the spacing between the UV lamp and the photocatalytic material, reducing or eliminating reflectors 113 and 114, and / or reducing the total surface area of ​​the UV lamp, but this tends to reduce the total photocatalytic generation of the oxidant.

[0057] Figure 5 A front view of the cell plate 150 is shown, showing the spacing and distribution of the holes 152. This is the surface that the airflow "sees" as it moves along the airflow path 104 and initially reaches the device 100. Therefore, smaller holes will tend to restrict the airflow to a greater extent than larger holes. However, because the coated inner surface of the holes 152 provides a significant portion of the photocatalytic activity of the device, and because smaller holes allow for a larger total area of ​​active photocatalytic surface, smaller holes tend to provide greater photocatalytic activity.

[0058] It has been found that setting the average cross-sectional area of ​​each hole 152 to be greater than about 5 mm 2 But less than about 45mm 2 Provides effective photocatalytic activity without unduly restricting airflow. The apertures 152 may more preferably be sized to have a width of about 6 mm. 2 To about 40mm 2 , or about 7mm 2 To about 30mm 2 , or about 8mm 2 To about 20mm 2 , or about 9mm 2 To about 15mm 2 A hole 152 that is too small tends to reduce the overall performance of the device by excessively restricting the airflow, while a hole 152 that is too large tends to reduce the overall performance of the device by excessively restricting the photocatalytic activity.

[0059] The number of holes 152 included in the unit cell plate 150 can vary. Preferably, the holes 152 are arranged in such a number that about 25% to about 75% of the cross-sectional area of ​​the unit cell plate 150 is composed of holes 152, or more preferably, about 35% to about 65%, or about 40% to about 60% of the cross-sectional area of ​​the unit cell plate 150 is composed of holes 152, wherein the cross section is taken along a plane arranged along the vertical axis and the longitudinal axis (for example, given Figure 5 view shown).

[0060] Thus, it has been found that the device 100 provides enhanced overall performance when the apertures are sized within the aforementioned ranges and the apertures are arranged within the aforementioned amounts. As used herein, the term "enhanced overall performance" means: an increase in overall performance on a power basis (e.g., per watt used by the device), a per volume basis (e.g., per cm occupied by the device), or a decrease in overall performance on a per volume basis (e.g., per cm occupied by the device) compared to a device that is not optimized for the same size. 3 ), or both, the ability to better remove contaminants from a given chamber / environment.

[0061] Figure 6 A front view of the PCO unit 100 is shown with the cell panels 150 and 151 removed, showing the UV lamp 124, the spacers 120 and 122, and the reflectors 113 and 114. These are the surfaces that the airflow "sees" as it moves through the front cell panel 150 and initially enters the interior chamber 140. As shown, the airflow path is blocked by these components and passes through a pair of gaps 160 and 162 disposed between the UV lamp 124 and the reflectors 113 and 114.

[0062] The size of the gaps 160 and 162 by cross-sectional area affects the volumetric airflow through the device 100 and the photocatalytic activity of the device 100. Increasing the size of the gaps 160 and 162 allows for greater airflow but tends to reduce photocatalytic activity (e.g., by moving the reflectors 113 and 114 away from the UV lamps 124). On the other hand, reducing the gaps 160 and 162 (e.g., by moving the reflectors 113 and 114 closer to the UV lamps 124) can increase photocatalytic activity but result in greater airflow restriction.

[0063] It has been found that optimizing the gap size, reflector size, and UV lamp size relative to each other can provide better overall performance of the device. "Gap fraction" is defined herein as the fraction of the cross-sectional area of ​​the device 100 that is within the gaps 160 and 162, where the cross section is taken along a plane arranged along the vertical axis and the longitudinal axis (e.g., given a Figure 6 In some embodiments, the device 100 is configured to have a gap fraction of about 0.1 to about 0.5, or more preferably, a gap fraction of about 0.125 to about 0.4, or even more preferably, a gap fraction of about 0.15 to about 0.3 or about 0.15 to about 0.2.

[0064] Reference again Figure 4 The width of the cell plates 150 and 152 may also vary. Wider cell plates provide longer pores 152 with greater total surface area, and thus provide greater photocatalytic activity, but also increase the length that air must pass through the pores, and thus increase airflow resistance.

[0065] "Cell fraction" is defined herein as the combined width of the cell plates 150 and 152 divided by the total width (from outer surface to outer surface) between the cell plates 150 and 152. The device 100 can be configured to have a cell fraction of about 0.2 to about 0.7, more preferably about 0.3 to about 0.6, and even more preferably about 0.4 to about 0.5. It has been found that setting the cell fraction within the above range provides improved overall performance of the device 100.

[0066] Still reference Figure 4 , the distance between the UV lamp 124 and the inner surface of the unit cell plates 150 and 152 can also be varied. A larger width between the UV lamp 124 and the unit cell plates 150 and 152 allows for a longer residence time for air to pass through the interior chamber 140, but also reduces the photocatalytic activity due to the increased distance between the lamp 124 and the unit cell plates 150 and 152.

[0067] "Light fraction" is defined herein as the width / diameter of UV lamp 124 divided by the total width between the inner surfaces of opposing unit cell plates 150 and 152. Device 100 can be configured to have a light fraction of about 0.45 to about 0.7 or more preferably about 0.5 to about 0.6. It has been found that configuring device 100 so that the light fraction is within the above range provides improved overall performance of device 100.

[0068] The following description provides some dimensions of an exemplary PCO unit 100 that has been found to provide effective performance in several applications, particularly in applications involving modular, mobile room cleaning units with integrated fan assemblies. However, it should be understood that the exemplary dimensions are not necessarily limiting, and other embodiments may be sized or scaled to provide specific application requirements.

[0069] In one embodiment, the device 100 can have an overall height of about 1.5 inches to 2.5 inches (about 3.8 cm to 6.4), an overall width of about 1.5 inches to 2.5 inches (about 3.8 cm to 6.4 cm), and a length of about 4 inches to 8 inches (about 10 cm to 20 cm). The unit cell plates can be sized accordingly to fit, and the unit cell plates can have a width of about 5 mm to about 30 mm, or more preferably about 10 mm to about 20 mm, or even more preferably about 10 mm to about 15 mm. The UV lamp 124 can also be sized accordingly to fit the overall dimensions of the device 100, and thus can have a length of about 3 inches to 7 inches (about 8 cm to 18 cm) and a diameter of about 0.25 inches to about 0.75 inches (about 0.6 cm to 2 cm). Reflectors 113 and 114 may be sized to extend inwardly from respective lower and upper surfaces 117 and 115 a distance of about 0.25 inches to about 0.75 inches (about 0.6 cm to 2 cm).

[0070] Other features of reflectors

[0071] The above-mentioned photocatalytic oxidation device embodiment comprises reflectors 113 and 114 having a "V"-shaped cross section (see, for example, Figure 4 ). In other embodiments, one or both of the reflectors may have different shapes. Figure 7 A cross-sectional view (taken along a plane perpendicular to the longitudinal axis) of one embodiment of a photocatalytic oxidation device 200 is shown, which includes reflectors 213 and 214 , UV lamp 224 , unit cell plates 250 and 251 , and internal chamber 240 . Figures 7 to 11 The illustrated embodiment may be configured to have features and dimensions similar to the photocatalytic oxidation device 100 described above, and thus the above description also applies to the photocatalytic oxidation device 100 including the Figures 7 to 11 Any embodiment of the described features, unless such features are specifically described as different.

[0072] As shown, the cross-section of reflectors 213 and 214 is semicircular in shape. That is, the cross-sectional shape of reflectors 213 and 214 omits any corners or edges. Reflectors 213 and 214 beneficially minimize disturbances to the passing air and thereby minimize the introduction of turbulence in the passing air. Air passing through inner chamber 240 will pass through gaps 260 and 262 that act as compression points. As air moves through gaps 260 and 262, the air velocity increases.

[0073] The curved surfaces of reflectors 213 and 214 advantageously allow smoothing of airflow through gaps 260 and 262 while minimizing the formation of jets, as compared to airflow through reflectors having angled faces, corners, and / or edges. Excessive jets may be undesirable because they disrupt the airflow and reduce the amount of air exiting the device 200, and less air exiting the device 200 means reduced delivery of the generated oxidant to the surrounding environment.

[0074] Fig. 8A A reflection pattern is shown in which a semicircular shaped reflector is used. When a light ray 254 is directed to the reflector 214, a reflected line 255 is reflected from the reflector 214 aligned with the focal point. The focal point is typically located at about half of the distance between the center of curvature and the pole of the reflector 214, which in this arrangement is typically the point of the reflector 214 closest to the UV lamp 224. As shown, most of the reflected lines 255 will be directed back inward in a direction facing the unit cell plate. This is beneficial because increasing the amount of incident light on the photocatalytic surface of the unit cell plate will increase the generation of oxidants, and therefore will increase the overall photocatalytic activity of the device.

[0075] and Fig. 8A Compared to the reflection pattern of the reflector 214 shown, Figure 8B The illustrated corner reflector 114 has a generally less desirable reflection pattern. When a light ray 154 is directed from a UV lamp 124 toward the reflector 114, a reflected ray 155 will be reflected outwardly from the surface of the reflector 114 at a reflection angle equal to the angle of incidence. This means that most of the reflected rays will be directed slightly outward rather than inwardly toward the center of the unit cell.

[0076] The reflector may have a shape other than a V-shape or a semicircle. In some embodiments, for example, the reflector may have a shape that is asymmetrical in cross-section. Fig. 9 An example of a UV lamp 324 associated with a reflector 314 that is asymmetric in cross section is shown. The reflector 314 can be shaped so that the front portion has a greater curvature than the rear portion. For example, the front portion can have a shape that generally follows a semicircular profile, while the rear portion has a flat surface similar to the rear portion of the V-shaped embodiment. Air flowing through the device in the direction indicated by arrow 304 will first contact the curved front portion of the reflector 314. Asymmetric reflectors such as the reflector 314 shown can be used in situations where it is desired to minimize jets but a flat surface reflection pattern is desired for the rear portion of the reflector 314. The curved front portion of the reflector 314 can help minimize the generation of jets, while the flat rear portion of the reflector 314 can provide a standard flat surface reflection pattern.

[0077] Fig.10Another example is shown in which the reflector 414 has a cross-sectional shape somewhere between a V-shape and a semicircle. For example, although the reflector 414 has an identifiable vertex at the point closest to the UV lamp 424, the side extending from the vertex has a slightly convex curvature, rather than the straight, flat shape in the V-shaped embodiment. A reflector such as reflector 414 can provide an intermediate effect between the V-shaped embodiment and the semicircular embodiment. For example, such an embodiment can be used for applications in which it is desired to balance the effect of a semicircle (e.g., reducing rapids) with the effect of a V-shape (e.g., providing a simpler reflection pattern).

[0078] A variety of gradients between semicircular and V-shaped can be selected based on specific application needs. For example, if a semicircular reflector has a curvature of a certain value X (the inverse of the radius), and the curvature of each of the "legs" of a similarly sized V-shaped reflector is 0, the reflector can be configured to have branches of any curvature that is a fraction of X. For example, some embodiments may include reflectors with branches that have a curvature of 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of X. Each branch may have the same or different curvature. As an example, the curvature of a semicircular reflector may be about 0.1625 inches to about 1 inch, or about 0.25 inches to 0.75 inches, or about 0.35 inches to about 0.6 inches. In other words, "X" may be equal to about 0.1625 inches to about 1 inch, or about 0.25 inches to 0.75 inches, or about 0.35 inches to about 0.6 inches.

[0079] Fig.11 Schematically illustrate the surface characteristics of the reflector, and how the difference in surface smoothness / roughness can affect the reflection pattern. As shown, when the reflector surface 150 is rough, the projected light ray 154 is reflected somewhat irregularly. In contrast, when the surface 150 is smooth, the reflected light ray 155 is more uniform and more uniformly aligned in the expected reflection direction. The smooth, highly reflective surface provides improved and more consistent light rays to the photocatalytic coating of the unit cell plate. Therefore, the reflector described herein is preferably made of polished aluminum or other highly reflective and smooth surfaces. For example, when measured at 20 degrees, 60 degrees or 85 degrees, the surface of the reflector preferably has at least about 50GU (gloss unit), or at least about 70GU, or at least about 90GU, or at least about 110GU, or at least about 130GU, or at least about 150GU of glossiness.

[0080] The reflectors described herein may additionally or alternatively include one or more films and / or coatings for enhancing reflectivity / gloss. The films and / or coatings may be formed from suitable polymeric materials. Some examples include polyester materials, such as polyethylene materials (e.g., polyethylene terephthalate (PET)). A particularly suitable example is biaxially oriented PET (BoPET), such as those sold under the trade name BoPET material for sale. The film and / or coating may be aluminized to have a shiny reflective surface.

[0081] In one example, a reflector made from standard aluminum sheet material can reflect about 93% of UV light in the range of 185nm to 254nm. Polishing the aluminum enhances the reflection to 95%. The addition of an aluminized BoPET film applied over unpolished aluminum provides about 98% reflection.

[0082] in conclusion

[0083] Although certain embodiments of the present disclosure have been described in detail with reference to specific configurations, parameters, components, elements, etc., this description is illustrative and should not be construed as limiting the scope of the invention as claimed.

[0084] Furthermore, it should be understood that for any given element of the components of the described embodiments, any possible alternatives listed for that element or component can generally be used alone or in combination with each other unless otherwise implied or explicitly stated.

[0085] In addition, unless otherwise indicated, the numbers used in the specification and claims to indicate amounts, components, distances or other measured values ​​should be understood as being optionally modified by the term "about" or its synonyms. When the terms "about", "approximately", "substantially", etc. are used in conjunction with a specified amount, value or condition, they may be considered to mean an amount, value or condition that deviates from the specified amount, value or condition by less than 20%, less than 10%, less than 5% or less than 1%. At least, without attempting to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be interpreted according to the number of reported significant figures and by applying ordinary rounding techniques.

[0086] Any headings and sub-headings used herein are for organizational purposes only and are not meant to limit the scope of the description or the claims.

[0087] It will also be noted that, as used in this specification and the appended claims, nouns without quantifiers refer to one, one or more, unless the context clearly dictates otherwise. Thus, for example, an embodiment referring to a singular referent (e.g., "a widget") may also include two or more such referents.

[0088] It should also be understood that the embodiments described herein may include characteristics, features (e.g., composition, assembly, member, element, part and / or portion) described in other embodiments described herein. Therefore, the various features of a given embodiment may be combined with other embodiments of the present disclosure and / or incorporated into other embodiments of the present disclosure. Therefore, the disclosure of certain features of a particular embodiment of the present disclosure should not be interpreted as limiting the application of the features or including to a particular embodiment. On the contrary, it should be understood that other embodiments may also include such features.

Claims

1. A photocatalytic oxidation device, comprising: a frame having a length, a width, and a height, a longitudinal axis of the frame extending through the length of the frame; a pair of cell plates disposed opposite to each other across a width of the frame, an interior portion of the frame between the cell plates defining an interior chamber, the cell plates comprising a plurality of holes to allow air to flow into and through the interior chamber, and at least an interior surface of the cell plates and a surface of the holes of the cell plates comprising a photocatalytic material; A UV lamp is disposed in the inner chamber and extends along the longitudinal axis, wherein the inner chamber comprises one or more gaps that allow air to flow from one unit cell plate to an opposite unit cell plate, and wherein a vertical cross section taken on a plane along the longitudinal axis has a cross-sectional area, and a gap fraction of the cross-sectional area is 0.1 to 0.5, wherein the gap fraction is a ratio of the cross-sectional area corresponding to the gap; and Wherein the cell fraction is equal to the combined width of the cell plates divided by the width between the outer surfaces of the cell plates, and wherein the cell fraction is between 0.2 and 0.

7. 2 . The device of claim 1 , wherein the frame further comprises one or more protrusions, each of the one or more protrusions being disposed adjacent to one of the cell plates and configured to help maintain a position of the corresponding cell plate.

3. The device of claim 1, wherein the frame further comprises one or more reflectors extending into the inner chamber toward the ultraviolet lamp.

4. The device of claim 3, wherein the one or more reflectors extend parallel to the longitudinal axis.

5. The apparatus of claim 3 or claim 4, wherein an inward-most portion of the one or more reflectors also extends parallel to the longitudinal axis and is aligned with the ultraviolet lamp.

6. The device of any one of claims 3 to 4, wherein the one or more reflectors are symmetrical about a vertical plane located on the longitudinal axis.

7. The device of any one of claims 3 to 4, wherein the one or more reflectors have a V-shaped cross section, a semicircular cross section, or a shape with a cross section between V-shaped and semicircular.

8. The device of any one of claims 1 to 4, further comprising one or more spacers configured to engage with an end of the UV lamp to help center the UV lamp within the inner chamber.

9. The device of any one of claims 1 to 4, wherein the frame comprises an upper side, a lower side, and a first laterally extending side and a second laterally extending side opposite to each other, wherein the cell plates form a front side and a rear side, wherein the upper side, the second laterally extending side, and the lower side of the frame form a single continuous material component, and wherein the first laterally extending side of the frame can be selectively attached to the single continuous material component.

10. The device of any one of claims 1 to 4, wherein the pores of the unit cell plate extend in a direction substantially perpendicular to the longitudinal axis.

11. The device of any one of claims 1 to 4, wherein the average cross-sectional area of ​​the holes is 5 mm 2 Up to 45mm 2 .

12. The device of claim 11, wherein the average cross-sectional area of ​​the holes is 6 mm 2 Up to 40mm 2 .

13. The device of claim 12, wherein the average cross-sectional area of ​​the holes is 7 mm 2 Up to 30mm 2 .

14. The device of claim 13, wherein the average cross-sectional area of ​​the holes is 8 mm 2 Up to 20mm 2 .

15. The device of claim 14, wherein the average cross-sectional area of ​​the holes is 9 mm 2 Up to 15mm 2 .

16. The device of any one of claims 1 to 4, wherein the amount of pores included is such that 25% to 75% of the cross-sectional area of ​​the unit cell plate is composed of the pores.

17. The device of claim 1, wherein the gap fraction is 0.125 to 0.

4.

18. The device of claim 1, wherein the gap fraction is 0.15 to 0.

3.

19. The device of claim 1, wherein the cell fraction is between 0.3 and 0.

6.

20. The device of claim 1, wherein the cell fraction is between 0.4 and 0.

5.

21. The device of any one of claims 1 to 4, wherein the light fraction is equal to the diameter of the ultraviolet lamp divided by the width between the inner surfaces of the unit cell plates, and wherein the light fraction is 0.45 to 0.

7.

22. The device of claim 21, wherein the light fraction is between 0.5 and 0.

6.

23. A method for purifying air, the method comprising: Providing a photocatalytic oxidation device according to any one of claims 1 to 22; activating the UV lamp to allow photocatalytic production of oxidants at the cell plate; as well as Air is moved across the width of the photocatalytic oxidation device.

24. A photocatalytic oxidation device comprising: a frame having a length, a width, and a height, a longitudinal axis of the frame extending through the length of the frame; a pair of cell plates disposed opposite to each other across a width of the frame, an interior portion of the frame between the cell plates defining an interior chamber, the cell plates comprising a plurality of holes to allow air to flow into and through the interior chamber, and at least an interior surface of the cell plates and a surface of the holes of the cell plates comprising a photocatalytic material; and A UV lamp is disposed in the inner chamber and extends along the longitudinal axis, Wherein the cell fraction is equal to the combined width of the cell plates divided by the width between the outer surfaces of the cell plates, and wherein the cell fraction is between 0.2 and 0.

7.

25. The device of claim 24, wherein the cell fraction is between 0.3 and 0.

6.

26. The device of claim 24, wherein the cell fraction is between 0.4 and 0.5.

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