Abstract:
A vehicle air purification system has a photocatalyst activated by photons emitted via an ultraviolet light emitting diode (UV-LED). The photocatalyst on a supporting structure is positioned to contact airflow passing through or over the photocatalyst. Chemical contaminants and microorganisms are eliminated from the airflow that makes contact with the photocatalyst structure.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/872742, filed Sep. 1, 2013, the disclosure of which is incorporated herein by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not Applicable 
       REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISK APPENDIX 
       [0003]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0004]    The present invention relates to air purification systems, and more particularly, to an air purification system for transportation vehicles using ultraviolet (UV) activated photocatalyst for the degradation of chemical pollutants and elimination of microorganisms. 
         [0005]    Advanced air purification systems can be applied to a wide range of purposes, from homes and offices to high-specification environments such as hospitals, laboratories, and industrial facilities. Ultraviolet (UV) photolysis and photocatalysis have been proved to be very effective for the elimination of many toxic airborne contaminants; and as a result have been incorporated in some high-end air purification systems. UV photocatalysis is being referred to as oxidation and reduction reactions on photocatalyst surfaces, which are generated by UV radiation. A photocatalyst is a substance that generates catalyst activity using radiation energy. A fundamental barrier to UV photocatalysis widespread deployment and application is the source for the UV radiation. The radiation source is UV lamps, which are relatively bulky, require high power, and have health and environmental issues due to the mercury contained in them. Furthermore, the UV lamps are typically needed replacing on a regular basis, leading to high maintenance costs. Such size, power, and cost considerations have excluded UV photocatalysis systems from a number of potential applications, which require a compact and low-power solution, for example in vehicle air purification systems. 
         [0006]    Light emitting diodes (LEDs) emit radiation of a single wavelength. With recent advancements in LED technology, LEDs now can be designed to generate UV radiation. The UV-LEDs compact and robust design makes them an attractive alternative for replacing UV lamps in UV reactor systems. 
         [0007]    There are harmful airborne contaminants and toxic organic chemicals within vehicles. A compact, low-power vehicular air purification system to eliminate chemical contaminants is desirable to vehicle users and manufacturers. 
       SUMMARY OF THE INVENTION 
       [0008]    In one aspect, the present invention is a vehicle air purifying system operating with one or more ultraviolet light emitting diodes (UV-LEDs) that activates one or more photocatalyst structures, in order to kill microorganisms (e.g. bacteria and viruses) and to degrade chemical contaminants (e.g. toxic organic compounds). The UV-LED is arranged to emit ultraviolet (UV) radiation onto the photocatalyst structure. The photocatalyst structure is positioned to contact airflow passing through or over the photocatalyst structure. As used throughout this specification, the term “photocatalyst structure” is intended to mean a photocatalyst, a photocatalyst composition, or a photocatalyst supported on a substrate. 
         [0009]    In another aspect, the present invention is a method of purifying airflow in transportation vehicles, comprising passing the airflow through a reactor including one or more photocatalyst structures; emitting ultraviolet radiation from one or more ultraviolet light emitting diodes (UV-LEDs) onto the photocatalyst structure; and eliminating chemical contaminants and microorganisms from the airflow that makes contact with the UV-activated photocatalyst structure while the photocatalyst is activated by the ultraviolet radiation emitted from the UV-LED. 
         [0010]    These and other features, aspects, and advantages of the present invention will become better understood with reference to the following drawings, description, and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a partially-diagrammatic perspective view of a UV-LED air purification system of the present invention; 
           [0012]      FIG. 2  is a partially-diagrammatic side view of a UV-LED air purification system shown in  FIG. 1 ; 
           [0013]      FIG. 3  is a partially-diagrammatic top view of a UV-LED air purification system shown in  FIG. 1 ; 
           [0014]      FIG. 4  is a partially-diagrammatic perspective view of a UV-LED air purification system of the present invention; 
           [0015]      FIG. 5  is a partially-diagrammatic perspective view of a UV-LED air purification system of the present invention; 
           [0016]      FIG. 6  is a partially-diagrammatic perspective view of a UV-LED air purification system of the present invention; 
           [0017]      FIG. 7  is a partially-diagrammatic perspective view of a UV-LED air purification system of the present invention; 
           [0018]      FIG. 8  is a partially-diagrammatic perspective view of a UV-LED air purification system of the present invention; 
           [0019]      FIG. 9  is a partially-diagrammatic perspective view of a UV-LED air purification system of the present invention; 
           [0020]      FIG. 10  is a partially-diagrammatic perspective view of a UV-LED air purification system of the present invention; 
           [0021]      FIG. 11  is a partially-diagrammatic perspective view of a UV-LED air purification system of the present invention; 
           [0022]      FIG. 12A-12C  is a partially-diagrammatic perspective view ( 12 A), top view ( 12 B), and side view ( 12 C) of a UV-LED air purification system of the present invention; 
           [0023]      FIG. 13  is a partially-diagrammatic perspective view of a conceptual design of a UV-LED air purification system of the present invention; and 
           [0024]      FIG. 14  is a partially-diagrammatic perspective view of a conceptual design of a UV-LED air purification system of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    The following detailed description is of the best currently contemplated modes of carrying out 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. 
         [0026]    In general, the present invention provides an air purifying system that eliminates chemical contaminants from airflow using a photocatalyst activated by UV radiation from a UV-LED. The airflow moves through the system by forced-convection preferably using an air-moving device such as an electrical fan. The photocatalyst is preferably supported on a porous substrate, where air passes through; or the photocatalyst is immobilized on a solid substrate, where air passes over. The photocatalyst may be titanium dioxide TiO 2 , or other photocatalysts. It may also be any combination of photocatalysts and catalyst supports, and co-catalysts (such as metals and metal oxides). 
         [0027]    The air purifying system may contain baffles or static mixers to alter the hydrodynamics of the airflow. This may be applied to provide a better distribution of the air through or over the photocatalyst and to enhance mass transfer of chemical contaminants to and from the photocatalyst surface. This may also be applied to provide a better thermal management of the system by transferring heat from the UV-LED and other parts of the air purifying system. Other material such as a heat sink or thermal conductive plates may also be applied to better transfer heat from the system. The air purifying system may also contain an air quality sensor to monitor and potentially indicate the air quality. A signal from the sensor may be used to turn the air purifying system on and off automatically. 
         [0028]    The air purifying system may have the shape of a cylinder and the like that can be placed in a vehicle cup holder. It may also have the shape of a coffee tumbler, cup, or other typical drinking containers. The air purifying system may be powered by a vehicle electrical circuit, by a vehicle cabin power-outlet, or by a battery. 
         [0029]    The air purifying system may be a mobile stand-alone reactor to be placed inside a transportation vehicle passenger cabin. Alternatively, the air purifying system may be integrated into the air circulation or filtration system of automobiles or other vehicles. In that case, the UV-LED air purification system may be implemented as part of the air circulation or filtration at the time of manufacturing of the car air filtration system or may be added later into the car air filtration system. 
         [0030]    Referring now to  FIG. 1  to  FIG. 3 , an air purification system  201  is shown according to an exemplary embodiment of the present invention.  FIG. 1  to  FIG. 3  shows a partially-diagrammatic perspective view of air cleaning system  201  having a rigid housing  10 , an inlet  11  for airflow to enter and an outlet  12  for airflow to exit, an UV-LED  13  with heat sink  14  to remove the heat generated by the UV-LED, a photocatalyst structure  15 , an electrical fan  16 , an internal cylinder  81 , electrical circuits  17  such as electrical drive circuits for UV-LED and other electronic components operation and microcontrollers for controlling the operation and automation, a power port  18 , and an on/off key  19 . The internal cylinder  81  is concentrically disposed in the housing  10 . The components of the air purification system may be held in their places or may be connected to one another by different means. For example, the LED  13 , the photocatalyst structure  15 , the electrical fan  16 , and the electrical circuits  17  may be held in their places by connecting to the internal cylinder  81 . The internal cylinder  81  has openings  82  to allow air to flow through. A perforated cap  83  is used on the inlet and outlet. This is to allow for the airflow movement in and out of the air purifying system, while covering inlet and outlet large openings. A cap  84  is used as the bottom of the system. For a better illustration, the perforated cap  83  is shown as an expanded view (with a distance from the inlet and outlet) in  FIG. 1  and  FIG. 2 . The arrows in  FIG. 1  show the overall direction of the airflow moving through the air cleaning system. 
         [0031]    Still referring to the air purifying system in  FIG. 1  to  FIG. 3 , the internal cylinder makes possible for the airflow to both enter and exit from the same end (top end, in  FIG. 1  to  FIG. 3 ) of the system, allowing the other end (bottom end, in  FIG. 1  to  FIG. 3 ) to be placed inside of a holder. Airflow enters the air cleaning system from the inlet  11  and after flowing downward in the annulus between the housing  10  and the internal cylinder  81 , it flows upward in the internal cylinder  81  and passes through the pores of a photocatalyst structure  15 . The photocatalyst structure may be a photocatalyst immobilized on a porous substrate (such as metal foam) or a perforated substrate (such as mesh). The UV-LED irradiates the photocatalyst; the photocatalyst is activated and initiate the desired reactions for microorganism inactivation and for chemical pollutant degradation in the airflow. 
         [0032]    Referring now to  FIG. 4  there is shown a partially-diagrammatic perspective view of an air purification system  202  having a rigid housing  20 , an inlet  21  for airflow to enter and an outlet  22  for airflow to exit, an UV-LED  23  with heat sink  24 , a photocatalyst structure  25 , an electrical fan  26 , electrical circuits  27 , a power port  28 , and an on/off key  29 . The air purification system is powered by electricity through a cable  91  with a connector  92  and a plug  93 . The plug  93  may be a USB or other plugs, to be connected to a power outlet in an automobile and other vehicles. Still referring to  FIG. 4 , there are wires and/or other eclectically conductive material  94  in the air purifying system to electrically connect the components. The power port  28 , the on/off key  29 , the LED  23 , and the fan  26  may be connected to drive circuits  27  by wires  94  to control and power the fan and UV LED. The LED, fan, and on/off key may have their separate circuit boards. 
         [0033]    Referring now to  FIG. 5  there is shown a partially-diagrammatic perspective view of an air purification system  203  having a rigid housing  30 , an inlet  31  for airflow to enter and an outlet  32  for airflow to exit, a LED  33  with heat sink  34 , a photocatalyst structure  35 , a fan  36 , electrical circuits  37 , a power port  38 , and an on/off key  39 . The air purification system further includes a baffle  95  to better distribute the airflow that flows through the photocatalyst structure, resulting in higher efficiency of the system. 
         [0034]    Referring now to  FIG. 6  there is shown a partially-diagrammatic perspective view of an air purification system  204  having a rigid housing  40 , an inlet  41  for airflow to enter and an outlet  42  for airflow to exit, a LED  43  with heat sink  44 , a photocatalyst structure  45 , a fan  46 , electrical circuits  47 , a power port  48 , an on/off key  49 , and a baffle  96 . The UV-LED board or its heat sink is connected by heat conductive plates  98  to the internal cylinder for better heat transfer and thermal management of the UV-LED. 
         [0035]    Referring now to  FIG. 7  there is shown a partially-diagrammatic perspective view of an air purification system  205  having a rigid housing  50 , an inlet  51  for airflow to enter and an outlet  52  for airflow to exit, a LED  53  with heat sink  54 , a photocatalyst structure  55 , a fan  56 , electrical circuits  57 , a power port  58 , and an on/off key  59 . The air purification system further includes a filter  99  that may be made of carbon or other material or may contain carbon or other material. One or more filters are used to absorb undesirable airborne materials, such as particulate, chemical, and microbial contaminants from the airflow. 
         [0036]    Referring now to  FIG. 8  there is shown a partially-diagrammatic perspective view of an air purification system  206  having a rigid housing  60 , an inlet  61  for airflow to enter and an outlet  62  for airflow to exit, a LED  63  with heat sink  64 , a photocatalyst structure  65 , a fan  66 , electrical circuits  67 , a power port  68 , and an on/off key  69 . The inlet  61  is on the side, while the outlet is on the top of the air purification system. The advantage of this configuration is that there is minimal mixing between the untreated airflow entering the inlet and the treated airflow exiting the outlet. 
         [0037]    Referring now to  FIG. 9  there is shown a partially-diagrammatic perspective view of an air purification system  207  having a rigid housing  70 , an inlet  71  for airflow to enter and an outlet  72  for airflow to exit, a LED  73  with heat sink  74 , a photocatalyst structure  75 , a fan  76 , electrical circuits  77 , a power port  78 , and an on/off key  79 . The UV-LED air purification system has the shape of a conical frustum (as shown in  FIG. 9 ). It may also have the shape of a popular beverage container such as a coffee tumbler, a coffee mug, a coffee cup, a beverage can, and the like. These shapes make it easy for the air purifying system to be placed inside of an automobile cup holder or other holders, and give the system a more familiar look. 
         [0038]    In further detail, referring to the invention of  FIG. 1  to  FIG. 9 , the airflow moving in the system removes the heat generated by the LED and other components. When the airflow moves inside the annulus—the space between the system housing and the internal cylinder—, it helps keeping the temperature of the air purifying system&#39;s housing low and simultaneously removes the heat generated by the LED in the internal cylinder. 
         [0039]    Referring now to invention shown in  FIG. 10 , there is shown an air purification system  208  having a rigid housing  110 , an inlet  111  for airflow to enter and an outlet  112  for airflow to exit, a LED  113  with heat sink  114 , a photocatalyst structure  115 , a fan  116 , electrical circuits  117 , a power port  118 , and an on/off key  119 . The airflow enters the air purifying system from one end and exit the system from the other end. The arrows show the overall direction of the airflow moving through the system. The air purifying system configuration shown in  FIG. 10  may be integrated into the air circulation or air ventilation pipe (preferably the main pipe) of a vehicle cabin, for cleaning the air entering to the cabin. 
         [0040]    Referring now to the invention shown in  FIG. 11 , there is shown an air purification system  209  having a rigid housing  120 , an inlet  121  for airflow to enter and an outlet  122  for airflow to exit, a LED  123  with heat sink  124 , a photocatalyst structure  125 , a fan  126 , electrical circuits  127 , and an on/off key  129 . The air purification system, which is sufficiently small, has a rigid power connector or plug  128  attached to its housing that may be directly connected to a power outlet in an automobile and other vehicles. The arrows show the overall direction of the airflow moving through the air purifying system. 
         [0041]    Referring to the air purification system of  FIG. 1  to  FIG. 11 , the shape of the air purification system housing (e.g.  10 , in  FIG. 1 ) may be different. The shape, position, orientation, order, and dimensions of LED, photocatalyst, fan, and other internal and external components may be different. The shape, position, and location of inlet (e.g.  11 , in  FIG. 1 ) and outlet (e.g.  12 , in  FIG. 1 ) may vary. Still referring to the air purification system of  FIG. 1  to  FIG. 11 , more than one LED and photocatalyst structure may be inside the air purification system. More than one set of LED and photocatalyst may be stacked in the air purification system. Also, the photocatalyst may be irradiated from one side or both sides by LEDs. The LED (e.g.,  13 ,  FIG. 1 ) may have a range of power outputs and wavelengths suitable for photocatalyst activation. The wavelength peak of the LED may be in UV radiation range, including wavelength from 250 nm to 385 nm. Still referring to the air purification system of  FIG. 1  to  FIG. 11 , the photocatalyst may be unsupported structure or be supported on a substrate structure. The photocatalyst structure may be a perforated, porous, solid or other material; its shape may be flat, dome, and the like, where airflow flows through and/or over the photocatalyst structure. Still referring to the air purification system of  FIG. 1  to  FIG. 11 , the drive (e.g.  17  in  FIG. 1 ) may be designed such that the air purifying system and LED is powered with different power sources including a battery and/or electrical plug and/or solar cell, and/or other power sources. Also, the air purification system may have its power source integrated in the system, such as a replaceable battery, a rechargeable battery and the like. 
         [0042]    The construction details of the invention as shown in  FIG. 1  to  FIG. 11 , are that the system housing may be made of aluminum, stainless steel, or of any other sufficiently rigid and strong material such as metal, alloy, high-strength plastic, and the like. The inlet and outlet caps may be made of any perforated material, mesh, and the like. Further, the various components of the air purification system may be made of different materials. For example, the conductive plates (e.g.,  98 ,  FIG. 6 ) may be made of copper, aluminum, or other heat conductive material. The photocatalyst support substrate may be a porous material such as a mesh or foam made of metal or metal composite or metal alloy, or other material. The housing may be made of material double layer with vacuum insulation (between the layers). 
         [0043]    The parts of the invention as shown in  FIG. 1  to  FIG. 11  may be put together in several ways. For example, the main components, including the LED and photocatalyst may be connected on a frame that fits inside the air purification system housing. The housing mat be closed on one side (top or bottom) or both sides (top and bottom) by a cap. The cap, if used as inlet and outlet cover, may have several openings to allow airflow to flow through the air purifying system; it may also be made of perforated material or mesh structure to allow the flowing of the airflow in and out of the system. The air purifying system may be easily opened and closed, for example by removing, unlocking, or unscrewing the cap on one or both sides (top and bottom). The air purifying system components, including the UV-LED and photocatalyst structure, may be easily replaceable. For example, the photocatalyst structure may slide in and out from an opening (e.g. slot) on the side of the internal cylinder. 
         [0044]    Referring now to the invention shown in more detail in  FIGS. 12A-12C , there is shown partially-diagrammatic perspective view ( FIG. 12A ), top view ( FIG. 12B ), and side view ( FIG. 12C ) of an air purification system  210 . In  FIGS. 12A-12C  the invisible parts are mainly shown by broken lines. In  FIGS. 12A-12C , there is shown an air purification system  210 , having a rigid housing  150 , an inlet  151  for airflow to enter, an outlet  152  covered by a perforated cap for airflow to exit, a bottom  154 , an internal cylinder  161  with openings  162  for airflow to go through, an UV-LED  153 , a photocatalyst structure  155 , an electrical fan  156 , prolongs  157  to connect the fan to the internal cylinder  161 , an on/off key  159 , a baffle  163  having the shape of a “hyperboloid of one sheet”, thermal conductive plates  164 , and a frame  165  for connecting the LED, the baffle, and the photocatalyst. The drive circuits (not shown) for operating the UV-LED and other electrical components may be placed in the space between the fan  156  and on/off key  159 , preferably in the central space, not to block the airflow. The UV-LED drive circuit (not shown) may alternatively be placed under the UV-LED  153 . The UV-LED may be connected to a heat sink (not shown) for its thermal management. 
         [0045]    Still referring to the invention shown in  FIG. 12A-12C , the internal cylinder  161  makes possible for the airflow to both enter and exit from the same end (top) of the system. Further, the internal cylinder  161  provides a housing for holding some of the air purifying system components including the photocatalyst structure  155 , UV-LED  159 , fan  156 , and baffle  163 . The inlet  151  is consisting of several opening slots on the side of the air purification housing at the top-end, and the outlet  152  is on the top of the air purification system. This configuration minimizes mixing between the untreated airflow entering the inlet  151  (mainly horizontally from the top side area) and the treated or purified airflow exiting the outlet  152  (mainly vertically from the top central area), as shown in  FIG. 12C  by the arrows. Still referring to  FIG. 12A-12C , the air purification system  150  has the shape of a coffee tumbler to be easily placed inside of an automobile cup holder and to have a familiar look. The arrows in  FIG. 12C  show the overall direction of the airflow moving through the air purifying system. 
         [0046]    Referring now to  FIG. 13  and  FIG. 14 , there are shown two potential configurations for UV-LEDs and photocatalyst structure arrangements in an air purification system with multi UV-LEDs and multi photocatalyst structures and a filter. Only the UV-LEDs, photocatalysts, and filter parts of the air purifying system are shown in these figures (for simplicity and for a better illustration of the concepts). 
         [0047]    Referring now to  FIG. 13 , there is shown a partially-diagrammatic perspective view of a configuration for UV-LEDs and photocatalyst structure arrangements in an air purification system  211 , having a series of UV-LEDs  171  mounted on perforated boards  172 , and a series of photocatalyst structures  173 , and a filter  174 , wherein the photocatalyst structures and the filter are irradiated by the UV-LEDs. Airflow passes through the LED perforated boards, photocatalyst structures, and the filter. The filter is irradiated by UV radiation from UV-LED to inactivate microbial contaminates and to degrade organic pollutants absorbed on the filter that may be eliminated by direct photolysis, without the need for photocatalytic reactions. The arrows show the overall direction of the airflow flowing through the UV-LEDs and photocatalyst structures. 
         [0048]    Referring now to  FIG. 14 , there is shown another partially-diagrammatic perspective view of a configuration for UV-LEDs and photocatalyst structure arrangements in an air purification system  212 , having a series of UV-LEDs  175  mounted on solid boards  176 , and a series of photocatalyst structures  177 , and a filter  178 , wherein the photocatalyst structures and the filter are irradiated by the UV-LEDs. Airflow (shown by the arrows) passes through the open-side of the LED boards  179  and through the photocatalyst structures and the filter. This design may enhance the flow mixing through the air purifying system. The arrows show the overall direction of the airflow flowing through the UV-LEDs and photocatalyst structures. 
         [0049]    In both air purification system configurations presented in  FIG. 13  and  FIG. 14 , the photocatalyst structures may be irradiated by UV-LEDs from one side or both sides. Further, in both configurations presented in  FIG. 13  and  FIG. 14 , static mixers (not shown) or baffles (not shown) may be used to enhance the airflow hydrodynamics and to enhance mass transfer of chemical contaminants to and from the photocatalyst surface. 
         [0050]    The advantages of the present invention include, without limitation, that it is a portable, compact air purifying system that can be easily placed inside vehicles. Further, the system purifies airflow by both inactivation of microorganisms and degradation of many chemical pollutants. Further, the system can be operated at low voltage and low power, unlike many other electronic air purification systems. Further, the system can be easily operated by several power sources, including a vehicle battery. Further, the system can be a stand-alone device or be integrated into a vehicle air circulation system. Further, if the system is a stand-alone device, it can be easily placed in a typical cup holder, which is commonly found in many vehicles, such as automobiles. 
         [0051]    In broad embodiment, the present invention is a compact air purifying system operating with photocatalyst activated by UV-LED applicable to air treatment in vehicles. 
         [0052]    While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention as claimed.