Patent Publication Number: US-2007107597-A1

Title: Air Purifying Device

Description:
FIELD OF THE PRESENT INVENTION  
      This invention relates to an air purifying device, particularly such a device within fins or plates coated with titanium dioxide (TiO 2 ). The invention further relates to an air purifying apparatus including such an air purifying device.  
     BACKGROUND OF THE PRESENT INVENTION  
      Air purifiers working on photo-catalytic oxidation (PCO) mechanism are known. It is known that when TiO2 is exposed to ultraviolet (UV) radiation, electron hole pairs are created. The resulting free radicals, e.g. hydroxyl radicals (.OH) and superoxide ions (O 2   − ), are very efficient oxidizers of organic matter, and are thus capable of decomposing various organic compounds. In particular, such free radicals are found to be able to kill a number of fungi, mold, bacteria and viruses, deodorize, and decompose such volatile organic compounds (VOCs) as benzene and formaldehyde.  
      Representative constructions of conventional air purifiers are shown in FIGS.  1  to  3  hereof. All of these constructions have a UV light source and a number of structures coated with titanium dioxide. As shown in FIGS.  1  to  3 , these constructions differ from each other mainly in the relative positioning of the titanium dioxide coated structures and the UV light source.  
      In the construction shown in  FIG. 1 , air flow passes through a mesh  10  coated with TiO 2 , which is also illuminated by a UV light source  12 . The shortcomings of such an arrangement include: 
          short contact time between the air flow (and thus the harmful substances carried by the air) and the TiO 2  coating;     such a purifier is generally rather thick;     there is a high air resistance or, in other words, a greater pressure drop; and     some portions of the mesh  10  are not exposed to UV radiation, such that the coating of TiO 2  on such portions is wasted.        

      As to the construction shown in  FIG. 2 , a TiO 2  coated honeycomb structure  16  is illuminated by a UV light source  18 . Such an arrangement suffers from the following disadvantages: 
          leakage of UV radiation;     such a purifier is generally rather thick; and     some portions of the honeycomb structure  16  are not exposed to UV radiation, such that the coating of TiO 2  on such portions is wasted.        

      Turning to the construction shown in  FIG. 3 , a number of parallel TiO 2  coated fins  20  are illuminated by a UV light source  22 . The shortcomings of this prior art arrangement are similar to those of the construction shown in  FIG. 2 .  
      It is thus an object of the present invention to provide an air purifying device, and an air purifying apparatus including such an air purifying device, in which the aforesaid shortcomings are mitigated, or at least to provide a useful alternative to the trade and public.  
     SUMMARY OF THE PRESENT INVENTION  
      According to a first aspect of the present invention, there is provided an air purifying device including a plurality of fins coated with titanium dioxide (TiO 2 ) and positioned substantially parallel to one another to define at least one passageway allowing air to pass through; and a source of ultraviolet (UV) light; wherein each of said fins has a hole and two ends; wherein at least part of said UV light source is received within a channel defined by said holes of said fins; and wherein each of said two ends of each said fin has two bent portions.  
      According to a second aspect of the present invention, there is provided an air purifying apparatus including at least an air purifying device, at least an air inlet, and at least an air outlet, wherein said air inlet and said air outlet are in a gas communicable relationship with said at least one passageway of said device, wherein said air purifying device includes a plurality of fins coated with titanium dioxide (TiO 2 ) and positioned substantially parallel to one another to define at least one passageway allowing air to pass through; and a source of ultraviolet (UV) light; wherein each of said fins has a hole and two ends; wherein at least part of said UV light source is received within a channel defined by said holes of said fins; and, wherein each of said two ends of each said fin has two bent portions. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Preferred embodiments of the present invention will now be described, by way of examples only, with reference to the accompanying drawings, in which:  
       FIG. 1  is a schematic diagram of a first conventional air purifying device;  
       FIG. 2  is a schematic diagram of a second conventional air purifying device;  FIG. 3  is a schematic diagram of a third conventional air purifying device;  
       FIG. 4  is a schematic diagram of an air purifying device according to the present invention;  
       FIG. 5A  is a front view of the air purifying device shown in  FIG. 4 ;  
       FIG. 5B  is a side view of the air purifying device shown in  FIG. 4 ;  
       FIG. 6  is a sectional view taken along the line A-A in  FIG. 5A ;  
       FIG. 7  is a front view of a fin of the air purifying device shown in  FIG. 4 ;  
       FIG. 8  is an enlarged side view of part of the edge of the fin shown in  FIG. 7 ;  
       FIG. 9A  is an enlarged top view of a first kind of protuberance on the fin shown in  FIG. 7 .  
       FIG. 9B  is an enlarged top view of a second kind of protuberance on the fin shown in  FIG. 7 ;  
       FIG. 10A  is a sectional view taken along the line B-B of  FIG. 9A , and that taken along the line D-D of  FIG. 9B ;  
       FIG. 10B  is a sectional view taken along the line C-C of  FIG. 9A , and that taken along the line E-E of  FIG. 9B ;  
       FIG. 11  shows the positioning of a number of fins in the air purifying device of  FIG. 4 ;  
       FIG. 12  shows the movement of air through the passageways between the fins shown in  FIG. 11 ;  
       FIG. 13  shows an enlarged view of a UV blocking structure along one side of the fins shown in  FIG. 11 ;  
       FIG. 14A  shows a first arrangement of the fins in an air purifying device according to the present invention;  
       FIG. 14B  shows a second arrangement of the fins in an air purifying device according to the present invention;  
       FIG. 14C  shows a third arrangement of the fins in an air purifying device according to the present invention;  
       FIG. 15  shows a schematic diagram of a first air purifying apparatus according to the present invention including the air purifying device of  FIG. 4 ;  
       FIG. 16  shows a schematic diagram of a second air purifying apparatus according to the present invention including the air purifying device of  FIG. 4 ;  FIG. 17  shows a schematic diagram of a third air purifying apparatus according to the present invention including the air purifying device of  FIG. 4 ; and  FIG. 18  shows a schematic diagram of a fourth air purifying apparatus according to the present invention including the air purifying device of  FIG. 4 . 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION  
      An air purifying device according to the present invention is shown in  FIGS. 4, 5A  and  58 , and generally designated as  100 . The device  100  includes a number of plates or fins  102  coated with titanium dioxide (TiO 2 ). The fins  102  are arranged within the device  100  parallel to one another. An ultraviolet (UV) light source  104  is positioned through the TiO2 coated fins  102 , emitting UV radiation of a wavelength of 360 nm to 380 nm. Each of the fins  102  is provided with a hole (not seen in  FIGS. 4, 5A  or  58 ) such that when the fins  102  are assembled as shown in  FIGS. 4 and 58 , the holes collectively define a channel through which the UV light source  104  is received.  
      It can be seen that when the fins  102  are assembled as shown in  FIGS. 4 and 58 , a number of passageways are defined among the fins  102  allowing air to pass through, as shown in  FIG. 4 . Generally speaking, the air leaving the passageways among the fins  102  forming part of the air purifying device  100  is cleaner than that entering the passageways among the fins  102 .  
      As shown in  FIG. 6 , the device  100  has a front cover  106 , a rear cover  108  and two side covers  11   b  inter-engaged with one another and with the fins  102  by screws  112 , for enclosing the fins  102 , such that only two sides of the fins  102  are exposed outside the device  100 . In such an arrangement, a first of the two exposed sides of the fins  102  serves as an inlet of air into the passageways among the fins  102 , and a second of the two exposed sides of the fins  102  serves as an outlet of air from the passageways among the fins  102 .  
      As shown in  FIG. 7 , a fin  102  of the air purifying device  100  is generally rectangular in shape and has a central through hole  114  for receiving the UV light source  104 . Air flows across the surface  115  of the fin  102  from a first side  116  to a second side  118 . On the surface of the fin  102  are a number of protuberances  120 ,  122 , to be further discussed below. The edge  116   a  of the side  116  and the edge  118   a  of the side  118  are waved, as shown in  FIG. 8 . Such an arrangement increases the contact surface area between the air and the fins  102 , enhances the generation of air turbulence in the passageway  124  between the fins  102  (thus promoting contact of the air with the fins  102 ), and increases the physical strength of the fins  102 , as it can minimize deflection of the fins  102  by the air pressure of the incoming air.  
      As discussed above, a number of protuberances  120 ,  122  are provided on the surface of the fin  102 .  FIG. 9A  shows an enlarged top view of the protuberance  120 , and  FIG. 9B  shows an enlarged top view of the protuberance  122 . It can be seen in  FIGS. 9A  to  10 B that the existence of these protuberances  120 ,  122  causes the air passing by to generate turbulence, thus increasing the time of contact between the air and the TiO2 coated fins  102 . Similar effect can be achieved by providing troughs or recesses on the surface  115  of the fins  102 . It is also envisaged that the surface  115  of the fins  102  may be provided with both protuberances  120 ,  122  and recesses.  
      As discussed above, two sides of the fins  102  are exposed outside the air purifying device  100 . In order to prevent leakage of UV radiation to the outside, along each such side of each fin  102  is formed a UV radiation blocking structure. As shown in  FIG. 11 , each of the fin  102  is in a wing-like shape, with two raised outer strips  130  joined with a lower central major surface  132  each via a slanted strip  134 .  
      It can be seen in  FIG. 11  that the longitudinal axis of the UV light source  104  coincides with the central longitudinal axis L-L of the fins  102 .  
      Thus, it can be seen that each exposed side of the fins  102  has a portion which is bent twice, namely the inclined strip  134  which is bent relative to the central surface  132  towards the axis L-L, and the raised strip  130  which is bent relative to the inclined strip  134  away from the axis L-L. The raised strips  130  and the central surface  132  are parallel with each other but not co-planar.  
      By way of such an arrangement, a bent passageway  124  is formed between each pair of adjacent fins  102 , which further enhances the formation of turbulence in the air passing therethrough, as shown in  FIG. 12 .  
      In addition, the bent portions at the two exposed sides of the fins  102  serve the additional purpose of preventing leakage of UV radiation away from the fins  102 . All or at least most of the UV radiation from the UV light source  104  will be reflected by the fins  102 , in particular by the inclined strips  134 , back towards the UV light source  104 , and thus be kept within the passageways  124  formed among the fins  102 . To achieve such an effect, it is found that the central surface  132   a  of a fin  102   a  must be below the level of the raised strip  130   b  of an adjacent fin  102   b , as shown in  FIG. 13 .  
      Several exemplary fin arrangements and dimensions are shown in  FIGS. 14A  to  20   14 C. In  FIG. 14A , an 8-fin-per-inch arrangement is shown, in which adjacent fins are separated by a distance of 3.29 mm so that there are eight fins for each 25.4 mm. The inclined strips are inclined relative to the central major surface at an angle of 145°. In  FIG. 14B , a 6-fin-per-inch arrangement is shown, in which adjacent fins are separated by a distance of 4.72 mm so that there are six fins for each 25.4 mm.  
      The inclined strips are inclined relative to the central major surface at an angle of 138.5°. In  FIG. 14C , a 4-fin-per-inch arrangement is shown, in which adjacent fins are separated by a distance of 8.07 mm so that there are four fins for each 25.4 mm. The inclined strips are inclined relative to the central major surface at an angle of 124.5°.  
      The air purifying device  100  may be used in a number of air purifying apparatus. As a general arrangement, and as shown in  FIG. 15 , the air purifying device  100  may be positioned downstream of a pre-filter  202  for filtering out dust, and a secondary filter  204  for filtering out finer dust, pollen, molds, dust mile and the like. The device  100  may then decompose the remaining bacteria, viruses, VOCs and odors.  
      The air purifying device  100  may form part of an air handling unit (AHU)  210 , as shown in  FIG. 16 . Air entering the AHU  210  first passes through an auto-cleaning high efficiency air filtration system with control  212 , then through one of a number of air purifying devices  100 . The filtered and cleaned air then passes through a coil section  214 , to be supplied to the outside environment through an air delivering section  216 .  
      As an alternative, the air purifying device  100  may form part of a fan coil unit (FCU) system, generally designated as  220  in  FIG. 17 . In such an arrangement, a number of devices  100  are fitted into the housing of the FCU side by side with the flange of the FCU at one end and the return plenum at another end. Return air is first treated by the devices  100  contained within a housing  222 , and then exits the system  220  through a fan coil unit  224  as supply air.  
      The air purifying device  100  may also be formed as a standalone machine, e.g. for domestic, commercial or industrial use, as shown in  FIG. 18 , and generally designated as  230 . Return air is drawn into the interior of the machine  230  by a blower  232 . Such air is pre-treated by a pre-filter  234  and a secondary filter  236  (e.g. as shown in  FIG. 15  and discussed above). Such pre-treated and filtered air is then passed to one or a number of air purifying devices  100 , downstream of the pre-filter  234  and secondary filter  236 , for further sterilization. The machine  230  further includes a number of wheels  238  for allowing movement of the machine  230  and a positive-temperature coefficient (PTC) heater  240 . Air so treated then exits the machine  230  to the outside environment via a diffuser  242 . The operation of the machine  230  may be controlled by operating a light-touch control panel  244 .  
      It should be understood that the above only illustrates examples whereby the present invention may be carried out, and that various modifications and/or alterations may be made thereto without departing from the spirit of the invention.  
      It should also be understood that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any appropriate sub-combinations.