Patent Application
20240384883
Conventional systems for treating ambient air and removing airborne particles include high-efficiency particulate air (HEPA) filtration systems. These systems utilize filters that are required to meet certain HEPA requirements, such as the ability to remove 99.97% of particles with diameter greater than or equal to 0.3 μm in air passing through the filter(s). While HEPA filtration systems may be useful for removing particles from the air, they suffer from all the limitations common to filtration systems, such as filters that clog over time and require continual monitoring and replacement. Filtration-based systems are also incapable of deactivating chemicals, removing unwanted gases, or removing smaller odor-causing molecules. Moreover, while a HEPA filtration system can remove several airborne contaminants, it will not treat nearby surface contaminants.
Other systems may utilize activated carbon filters or electrostatic filters. While these may be utilized to enhance the ability to trap contaminants and improve the effectiveness of filtration, they still involve the above-mentioned limitations common to filtration-based systems such as filter replacement, degrading filter performance over time, and the inability to treat surface contaminants.
Other air purification systems, commonly referred to as “ionizers,” are designed to emit negative ions into the surrounding air. These ions attach to positively charged contaminants such as pollen and dust. The contaminants then become weighed down and are more likely to settle or are easier to trap in a collection plate. However, because many of the contaminants are simply moved to the floor or walls rather than destroyed or removed, they can reenter the air after the negative ions dissipate or disassociate. If a collection plate is used, it must be regularly cleaned or replaced as with any filtration system.
Other air purification systems are designed to use ultraviolet (UV) radiation to inactivate and/or degrade airborne contaminants. These systems may be referred to as UV germicidal irradiation or UVGI air purifiers. The UV light is typically tuned to short-wave UV light (UV-C light). In operation, air is directed through the system and past one or more UV lamps, with the intent of using the UV light to directly disinfect the passing air. Although UVGI systems are capable of destroying some contaminants rather than trapping/filtering all passing contaminants, they have limitations. For many bacteria and mold contaminants, especially spores, the brief exposure to UV light is not enough to effectively destroy the contaminant. Some volatile organic compounds (VOCs) may also be resistant to UV energy, or worse, be reactive with UV light in a way that makes them more harmful or exposed to nearby individuals.
Photocatalytic oxidation (PCO) air purifiers are somewhat similar to UV air purification systems in that they also utilize UV light. However, rather than using the UV light to directly interact with passing contaminants, 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 generate a variety of oxidizers such as hydroxyl radicals. The oxidizers can then attack organic molecule contaminants and degrade them into less harmful substances.
Thus, rather than trapping contaminants, PCO systems are capable of destroying and removing contaminants from the treated environment. However, conventional PCO systems have several limitations. For example, the passing air must be brought into sufficient proximity with the catalyst for the generated oxidizers to mix with the air and contact contaminants in the air. Ideally, a portion of the generated oxidizers should also continue to pass beyond the catalyst and UV lamp so that oxidizers can reach nearby surfaces and provide treatment of surface contaminants as well.
Several design decisions must therefore be made as to where to position the catalyst material and the UV assembly relative to each other and relative to the airflow path. If there is insufficient contact between passing air and the catalyst material, or if there is insufficient irradiation of the catalyst material, there will be reduced generation of oxidizers, poor mixing of the oxidizers with the air, or both, ultimately leading to suboptimal treatment of the contaminants. 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 airflow, which can increase the operational power demand needed to run the system and/or reduce the volumetric airflow through the system. Reduced airflow can hamper the treatment effectiveness of the system, increase the time it takes to clean the targeted environment, and/or hinder the ability of the system to emit oxidizers very far beyond the catalyst where they can treat surface contaminants.
Accordingly, there is an ongoing need for improved PCO air purification systems. An improved PCO air purification system would be structurally configured and dimensionally optimized to provide effective generation of oxidizers and effective mixing of the oxidizers with passing air while minimizing disruption to airflow.
Described herein are air sanitation units configured for increased rates of airflow and greater concentration of generated oxidizer in the airflow. The air sanitation unit comprises a duct for directing airflow through the unit and one or more photocatalytic oxidation (PCO) devices disposed within the duct. Each of PCO devices may include a frame having a length, width, and height, with a longitudinal axis extending through the length of the frame and a pair of cell panels disposed opposite one another across the width of the frame, an interior portion of the frame between the cell panels defining an interior chamber. The cell panels may include a plurality of apertures to allow air to flow into and through the interior chamber, with at least the interior surfaces of the cell panels and aperture surfaces of the cell panels including a photocatalytic material. The PCO devices may also include an ultraviolet (UV) lamp disposed within the interior chamber and extending along the longitudinal axis. The air sanitation unit may also comprise a fan configured to move surrounding air into the inlet, through the one or more PCO devices, and through the outlet.
The air sanitation unit may comprise an inverted funnel at the inlet of the duct to direct substantially all the airflow through the one or more PCO devices. The unit may also comprise additional cell panels to further limit the escape of UV light from the duct. The air sanitation unit may be installed in a mass transit system or in the air ducts of a ventilation system. The air sanitation unit may rely on ventilation devices connected to the ventilation system to induce an airflow through the air sanitation unit. The air sanitation unit may additionally be configured to activate a fan when a minimum rate of airflow is not exceeded (e.g., by connecting the unit to an airflow sensor) or to activate when all other ventilation devices fail to push air through the ventilation system.
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 indication of the scope of the claimed subject matter.
Various objects, features, characteristics, and advantages of the invention will become apparent and more readily appreciated 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 Drawings, like reference numerals may be utilized to designate corresponding or similar parts in the various Figures, and the various elements depicted are not necessarily drawn to scale, wherein:
Each PCO device 108 includes a UV lamp 110 and cell panels 112, 114 disposed to either side of the UV lamp and which may be secured by a frame 116. The cell panels 112, 114 include a plurality of apertures that allow the airflow 117 to pass therethrough. Typically, cell panels 112, 114 will be oriented such that cell panel 112 is positioned upstream of the UV lamp 110 while cell panel 114 is positioned downstream of the UV lamp 110. The major plane 118 of cell panel 112 and the major plane 120 of cell panel 114 may be oriented to be substantially perpendicular to the airflow 117 moving through the unit 100 so as to allow the airflow 117 to move through the PCO device 108.
The cell panels 112, 114 include a photocatalyst coating. The photocatalyst coating is placed at least on the inside surfaces of the cell panels 112, 114 facing the UV lamp 110. Preferably, the photocatalyst coating also extends into the apertures to coat the surfaces of the apertures. The photocatalyst coating may comprise a metal oxide such as titanium oxide and may optionally include one or more transition metals and/or alloys of transition metals. Examples of additional or alternative photocatalytic materials that may be utilized in 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 oxide), sulfides (e.g., zinc sulfide), silica, and combinations thereof.
Oxidizers generated during operation of the PCO devices 108 may include, for example, hydrogen peroxides, hydroxides, free oxygen molecules, super oxide ions, and ozone. Preferably, however, the PCO devices 108 are configured so that ozone generation is limited or eliminated. While ozone is a powerful oxidizing agent, excess ozone may cause respiratory irritation in sensitive individuals. It has been found that by tailoring the PCO devices 108 to generate effective levels of oxidizers while minimizing or eliminating ozone, effective purification performance is maintained without the potential detrimental effects related to excess ozone. In order to provide these performance characteristics, the UV lamp 110 preferably emits light with a wavelength of about 185 nm to about 254 nm. The UV lamp 110 will typically be rated at about 5 to 30 watts. The PCO device 108 is further described in U.S. Patent Application No. 63/006,270, which is incorporated herein by this reference.
One or more PCO devices 108 may be included within the duct 106 of the air sanitation unit 100. The one or more PCO devices 108 preferably extend to the edges of the cross-section of the duct 106 so that substantially all of the airflow 117 is directed though the PCO devices 108.
The fan 104 induces an airflow flowing through the duct 106 and across the one or more PCO devices 108. The fan 104 may be selected from a variety of fan types, including axial fans, centrifugal fans, blowers, or, as shown, a cross flow fan. A cross flow fan is preferably used because it has a high air flow rate, and specifically a higher flow rate compared to axial fans, while being small enough to maintain the compact size of the unit 100.
The fan 104 may be positioned upstream of the one or more PCO devices 108, such as immediately upstream of the duct inlet 122 as shown, or may be positioned further downstream of the one or more PCO devices 108, such as immediately upstream of the outlet 102. Preferably, the fan 104 is positioned upstream of the one or more PCO devices 108 such that air is pushed rather than pulled through the one or more PCO devices 108. Through testing, it has been found that airflow 117 pushed through the one or more PCO devices 108 has a four to five times as great a concentration of generated oxidizers as airflow that is pulled through the unit 100.
The duct 106 of the air sanitation unit 100 may include an inverted funnel 124 located at the duct inlet 122, such that the airflow 117 is directed immediately from a narrow opening near the fan 104 to an expanded area having limits at the edges of the one or more PCO devices 108. The inverted funnel 124 beneficially directs substantially all of the airflow 117 through the one or more PCO devices 108 and increases the concentration of generated oxidizers in the airflow 117 of the unit 100. This is an improvement on other photocatalytic devices wherein the UV lamp and catalytic material form only a small portion of the cross-sectional area of the ductwork, compared to other devices wherein only approximately 30% of the airflow passes across or makes contact with the photocatalytic material and UV lamp.
The air sanitation unit 100 may also include one or more additional cell panels disposed within the duct 106 to facilitate absorption of any UV light that escapes cell panels 112, 114 and frame 116 of the one or more PCO devices 108. The additional cell panels are similar in shape and material as the cell panels 112, 114 of the one or more PCO devices 108, having a plurality of apertures to allow the airflow 117 to pass along the duct 106 and including a photocatalytic coating on at least the surface closest to the PCO devices 108. The additional cell panels preferably have at least a sufficient width and height to extend to the edges of the duct 106.
The additional cell panels may be positioned upstream and/or downstream of the one or more PCO devices 108, although the additional cell panels are preferably positioned both upstream and downstream of the PCO devices 108. The additional cell panels may, like cell panels 112, 114 of the PCO devices 108, be oriented such that the major plane 132 of the additional cell panels is substantially perpendicular to the airflow 117 of the unit 100. For example, the major plane 126 of downstream cell panel 128 shown in
Although the air sanitation unit 200 may include fans 204, the air sanitation unit 200 may rely on one or more ventilation devices connected to the ventilation system to push air through the unit 200 (e.g., air conditioning system, furnace, etc.). This aids in reducing operation costs of the air sanitation unit 200 and helps to ensure that sanitizing air is continuously provided to the interior of the building. However, typical ventilation devices connected to the ventilation system may not induce an airflow through the system approximately 50% to 60% of the time during operation.
The fans 204 of the air sanitation unit 200 may be configured to activate when the ventilation devices are not pushing air through the ventilation system or when no airflow is detected in the system. For example, the air sanitation unit 200 may be connected to an airflow sensor that activates the fans 204 when no airflow is detected above a particular minimum flow rate at the unit 200. Alternatively, the air sanitation unit 200 and the one or more ventilation devices may be connected via a circuit, or other system, such that the fans 204 of the air sanitation unit 200 are activated when the one or more ventilation devices are not pushing air through the ventilation system. This ensures that sanitizing air is continuously provided to the interiors of the building.
The air sanitation unit 200 may comprise one or more PCO devices 208, such as one PCO device 208, two PCO devices 208, three PCO devices 208, or more than three PCO devices 208, through which the airflow is directed. The airflow may be directed from the fans 204 through the one or more PCO devices 208 by a duct 206 positioned between the one or more PCO devices 208 and the fans 204. The air sanitation unit 200 may comprise cell panels, such as an upstream cell panel and a downstream cell panel 214, as well as additional cell panels, having the same or similar characteristics as those described in relation to air sanitation unit 100 above, including apertures (not shown) through which the airflow may pass.
The one or more PCO devices 208 of air sanitation unit 200 may be oriented parallel to the airflow moving through the fans 204. In other embodiments, the one or more PCO devices 208 may be oriented at an oblique angle relative to the airflow moving through the fans 204. In instances wherein the air sanitation unit 200 comprises two or more PCO devices 208, the two or more PCO devices may be oriented relative to the airflow moving through the fans 204 at different angles. In this manner, the one or more PCO devices 208 can redirect and increase the turbulence of the airflow to mix the oxidizers throughout the air.
While certain embodiments of the present disclosure have been described in detail, with reference to specific configurations, parameters, components, elements, etcetera, the descriptions are illustrative and are not to be construed as limiting the scope of the claimed invention.
Furthermore, it should be understood that for any given element of component of a described embodiment, any of the possible alternatives listed for that element or component may generally be used individually or in combination with one another, unless implicitly or explicitly stated otherwise.
In addition, unless otherwise indicated, numbers expressing quantities, constituents, distances, or other measurements used in the specification and claims are to be understood as optionally being modified by the term “about” or its synonyms. When the terms “about,” “approximately,” “substantially,” or the like are used in conjunction with a stated amount, value, or condition, it may be taken to mean an amount, value or condition that deviates by less than 20%, less than 10%, less than 5%, less than 1%, less than 0.1%, or less than 0.01% of the stated amount, value, or condition. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
Any headings and subheadings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims.
It will also be noted that, as used in this specification and the appended claims, the singular forms “a,” “an” and “the” do not exclude plural referents unless the context clearly dictates otherwise. Thus, for example, an embodiment referencing a singular referent (e.g., “widget”) may also include two or more such referents.
It will also be appreciated that embodiments described herein may also include properties and/or features (e.g., ingredients, components, members, elements, parts, and/or portions) described in one or more separate embodiments and are not necessarily limited strictly to the features expressly described for that particular embodiment. Accordingly, the various features of a given embodiment can be combined with and/or incorporated into other embodiments of the present disclosure. Thus, disclosure of certain features relative to a specific embodiment of the present disclosure should not be construed as limiting application or inclusion of said features to the specific embodiment. Rather, it will be appreciated that other embodiments can also include such features.
This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63/467,536, filed on May 18, 2023 and titled “Modular Air Sanitation Unit,” the entirety of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63467536 | May 2023 | US |
