ENHANCED PHOTO-CATALYTIC CELLS

Abstract

A photo-catalytic cell may produce bactericidal molecules in air by passing air across catalyst coated targets. Ultraviolet (UV) energy may be emitted from a source. A first portion of the UV energy from the source may be applied directly onto the targets. A second portion of the UV energy from the source may be reflected onto the targets.

Claims

1. An apparatus for ionizing air, the apparatus comprising: a first target including: an inner side arranged to receive ultra-violet (UV) energy from a UV emitter, an outer side that abuts a region where an airflow is unobstructed, a plurality of passages extending continuously between the inner side and the outer side, and a photo-catalytic coating on the plurality of passages, wherein the photo-catalytic coating comprises titanium dioxide; a first reflector configured to reflect UV energy from the UV emitter towards the photo-catalytic coating of the first target, wherein the first reflector is a specular UV reflector; and wherein the first target is arranged to: receive, through the inner side and at the photo-catalytic coating, UV energy from the UV emitter and UV energy from the first reflector, wherein incident angles of specularly reflected UV ray paths received from the first reflector are greater than incident angles of UV ray paths received directly from the UV emitter, ionize air in response to the received UV energy, and pass the airflow from the inner side and through the plurality of passages to carry the ionized air away from the outer side.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 is a perspective view of a typical photo-catalytic cell in accordance with an embodiment of the invention in which a typical honeycomb matrix is shown as the target;

[0011] FIG. 2 is a side elevation view of the photo-catalytic cell of FIG. 1;

[0012] FIG. 3 is a cross sectional view of the photo-catalytic cell of FIG. 2 taken along the line 3-3; and

[0013] FIG. 4 is a comparison graph showing a difference in performance of the photo-catalytic cell of FIG. 1 with and without use of UV reflectors in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0014] The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.

[0015] Various inventive features are described below that can each be used independently of one another or in combination with other features.

[0016] Broadly, embodiments of the present invention generally provide photo-catalytic cells in which reflectors may be positioned to reflect UV energy and increase a proportion of emitted UV energy that strikes titanium dioxide in the cell at high incident angles.

[0017] Referring now to the Figures, it may be seen that an exemplary embodiment of a photo-catalytic cell 10 may comprise an electronics box 12; a light pipe indicator 14; a power cord 16; a chamber 18; honeycomb targets 20; UV reflectors 22-1, 22-2 and 22-3; and a UV emitter or lamp 24. The honeycomb targets 20 may be coated with titanium dioxide.

[0018] In operation, air may pass across the honeycomb targets 20 while UV energy may be applied to the target 20 by the lamp 24. A photo-catalytic reaction may take place in the presence of the UV energy. The reaction may produce bactericidal molecules in the air.

[0019] Referring now particularly to FIG. 3, the efficacy of the UV reflectors 22-1 may be illustrated. If the reflector 22-1 were not present, an emitted ray 26 might pass through the honeycomb target 20 without impinging on the titanium dioxide. However, when one of the reflectors 22-1 is present, an illustrative emitted ray 28-1 of UV energy may impinge on the UV reflectors 22-1. The ray 28-1 may be reflected to become a reflected ray 28-2. It may be seen that the reflected ray 28-2 may impinge on a surface of the honeycomb target 20. It may be seen that a hypothetical unreflected ray 26, which might follow a path parallel to that of the ray 28-1, might pass through the honeycomb target 20 without impinging on the target 20. Thus, presence of the reflector 22-1 in the path of the ray 28-1 may result in avoidance of loss of the UV energy from the ray 28-1. The reflectors 22-1 may be relatively small as compared to the size of the honeycomb target 20. The small size (about 10% of the size of the target 20) may allow for minimal air flow obstruction. In spite of their relatively small size, the reflectors 22-1 may be effective because they may reflect virtually all of the (normally lost) UV energy that is emitted in a direction that is almost orthogonal (i.e., within 5 of orthogonality) to the outer vertical plane of the honeycomb target 20. Hence, UV energy would pass thru the honeycomb target without touching the TiO2 surface. But by reflecting the UV rays onto the opposite side target matrixthat energy could be captured and utilized so as to add to the total ion count within the desired cloud of ionized molecules. In other words, the number of ions created by any incoming UV ray is proportional to the sine of the incident angle (Theta) between the UV ray path and the TiO2 surface that a given ray is impacting.

[0020] At theta=90 deg Sine (90)=1 Maximum energy gathered

[0021] At theta=0 deg Sine (0)=0 Minimum energy gathered

[0022] Reflectors 22-3 may be interposed between the lamp 24 and walls of the chamber 18. UV energy striking the reflectors 22-3 may be reflected onto the honeycomb target 20. Thus presence of the reflectors 22-3 may result in avoidance of loss of UV energy that might otherwise be absorbed or diffused by walls of the chamber 18. Similarly, reflectors 22-2 may be placed in corners of the chamber 18 to reflect UV energy onto the honeycomb target 20.

[0023] The reflectors 22-1, 22-2 and/or 22-3 may be constructed from material that is effective for reflection of energy with a wavelength in the UV range (i.e., about 184 nanometers [nm] to about 255 nm). While soft metals such as gold and silver surfaces may be effective reflectors for visible light, their large grain size may make them less suitable than metallic surfaces with a small grain size (i.e., hard metals). Thus, hard metals such as chromium and stainless steel and other metals that do not readily oxidize may be effective UV reflectors and may be particularly effective for use as UV reflectors in the photo-catalytic cell 10. Material with a UV reflectivity of about 90% or higher may be suitable for use in the reflectors 22-1, 22-1 and 22-3. Lower reflectively produces lower effectiveness. To achieve the level of reflection required, it may be necessary to micro-polish or buff a selected materials reflective surface to achieve the specifications defined in para 22]-24] below.

[0024] Advantageously, reflecting surfaces of the reflectors 22 should be electrically conductive. Specifically, outer surface coatings (added for oxidation protection) like glass, clear plastics, clear anodization (i.e. non-conductive) may diminish (considerably) any performance enhancement of the photo-catalytic cell 10.

[0025] Also it is important that reflecting surfaces of the UV reflector 22 produce surface specular reflection. (Specular reflection being a mirror-like reflection of lightin which a single incoming light ray is reflected into a single outgoing direction) Specular reflection is distinct from diffuse reflection where an incoming light ray is reflected into a broad range of directions. Diffuse reflection may diminish performance enhancement of the photo-catalytic cell 10.

[0026] In an exemplary embodiment of the photo-catalytic cell 10, the reflectors 22-1, 22-2 and 22-3 may be chromium-plated plastic. Chromium-plated plastic may be a desirably low cost material with a desirably high degree of reflectivity for UV energy. So called soft chrome such as the plating used to produce a mirror-like finish that is seen on automobile chromed surfaces may be advantageously employed.

[0027] It may be noted that there may be other cell shape designs which are not rectangular. For example, the cell 10 may be circular, tubular, or may have an otherwise complex shape. For these non-rectangular shaped cells, an optimum reflector design may be curved or otherwise non-flat in shape.

[0028] It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.