Abstract:
An air-handling unit includes a primary air plenum and a primary air inlet in fluid communication with the primary air plenum. The primary air inlet is configured to provide a flow of primary air to the primary air plenum. The air-handling unit also includes a chamber in fluid communication with the primary air plenum. The chamber includes an irradiate cavity and a secondary air inlet configured to accept a flow of secondary air into the irradiate cavity, and a sterilization mechanism positioned in the irradiate cavity. The sterilization mechanism is configured to effectively treat and sterilize the secondary air.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 61/594,528, filed on Feb. 3, 2012, and U.S. Provisional Application Ser. No. 61/639,169, filed on Apr. 27, 2012, both of which are herein incorporated by reference in their entireties. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to an induction air handling unit and, more particularly, to an active chilled beam with air sterilization means. 
       BACKGROUND OF THE INVENTION 
       [0003]    Known air-conditioning systems treat predominately outside air that is mixed with a proportion of return or recirculated air from within a building. This conditioned air is then used to meet the heating or cooling load within a particular space, such as a number of rooms on a floor or an open space area on a floor of a building. 
         [0004]    A chilled beam is one such type of convection HVAC system designed to heat or cool buildings. Pipes carrying water are passed through a beam; i.e., a heat exchanger, suspended a short distance from the ceiling of a room. As the beam chills the air around it, the air becomes denser and falls to the floor. It is replaced by warmer air moving up from below, causing a constant flow of convection and cooling the room. 
         [0005]    An active chilled beam, also know as an induction diffuser, utilizes ducts to push or induce air, such as recirculated or secondary air (also known as induced air), toward the unit. Known active chilled beam systems, however, are not particularly suitable for hospitals and other environments wherein recirculated or secondary air may carry bacteria, germs, and the like. 
         [0006]    Accordingly, there is a need for an active chilled beam system that is particularly suited for use in hospital patient rooms, outpatient rooms, nurses&#39; stations, waiting areas, and in any area of a hospital that allows recirculation, among other areas where heating, cooling and/or sterilization of recirculated air is desired. 
       SUMMARY OF THE INVENTION 
       [0007]    It is an object of the present invention to provide an active chilled beam system. 
         [0008]    It is another object of the present invention to provide an active chilled beam system having sterilization means. 
         [0009]    It is another object of the present invention to provide an active chilled beam system wherein sterilization occurs within a mixing chamber/plenum. 
         [0010]    It is another object of the present invention to provide an active chilled beam that utilizes a sterilizing light to sterilize induced/recirculated air. 
         [0011]    It is yet another object of the present invention to provide an active chilled beam configured to increase the residence time of induced air within the mixing chamber/plenum. 
         [0012]    It is another object of the present invention to provide an active chilled beam that is configured to minimize leakage of sterilizing light. 
         [0013]    According to the present invention, an air-handling unit for processing an air stream therethrough is provided. The air-handling unit includes a primary air plenum and a primary air inlet in fluid communication with the primary air plenum. The primary air inlet is configured to provide a flow of primary air to the primary air plenum. The air-handling unit also includes a chamber in fluid communication with the primary air plenum. The chamber includes an irradiate cavity and a secondary air inlet configured to accept a flow of secondary air into the irradiate cavity, and a sterilization mechanism positioned in the irradiate cavity. The sterilization mechanism is configured to effectively treat and sterilize the secondary air. 
         [0014]    In an embodiment of the present invention an air handling system is provided. The air handling system includes a primary air plenum configured to receive a flow of primary air and a chamber having an irradiate cavity and an induction channel adjacent to an outer edge of said chamber. The induction channel is in fluid communication with the primary air plenum and an outlet port formed in the chamber and is configured to direct a flow of primary air from the primary air plenum to the outlet port to induce a flow of secondary air into the irradiate cavity. The system also includes a sterilization unit disposed in a lower portion of the irradiate cavity. 
         [0015]    According to the present invention, a method of processing a stream of air in an air-handling unit includes initiating a flow of primary air into the air handling unit, inducing a flow of secondary air into a cavity within the unit, and sterilizing the secondary air within the cavity. 
         [0016]    These and other objects, features, and advantages of the present invention will become apparent in light of the detailed description of the best mode embodiment thereof, as illustrated in the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure, and together with a general description of the disclosure given above, and the detailed description of the embodiments given below, serve to explain the principles of the disclosure. 
           [0018]      FIG. 1  is a perspective view of an active chilled beam in accordance with an embodiment of the present invention. 
           [0019]      FIG. 2  is a cross-sectional view of the active chilled beam of  FIG. 1 . 
           [0020]      FIG. 3  is a graph illustrating  E. Coli  survival rate as a function of exposure time under ultra violet light. 
       
    
    
       [0021]    Other features and advantages of the present disclosure will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principals of the invention. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0022]    Referring to  FIGS. 1 and 2 , an active chilled beam  110  according to an embodiment of the present invention is shown. As shown therein, the active chilled beam  110  generally takes the form of a chamber  112  having a primary air inlet  114 . The chamber  112  is generally of a sheet metal construction and is provided with flanges for mounting the chilled beam  110  to a ceiling or other support structure. Alternatively, the chamber  112  may be constructed from other materials such as sandwich-foam sheets or fiber reinforced plastics. 
         [0023]    With specific reference to  FIG. 2 , primary/ventilation air from a central air handling system (not shown for clarity) is supplied through the primary air inlet  114  to a primary air plenum  116  in the chamber  112 . The primary air within the air plenum  116  is pressurized as compared to a secondary/recirculated air from the room. As a result, the pressurized primary air from the primary air plenum  116  is directed downward through rows of induction nozzles  118  and towards the outer edges of the chamber  112 , before exiting out into the space below the unit. 
         [0024]    The flow of the primary air out of the chamber  112  induces movement of the secondary air up and into the active chilled beam  110  in the direction of arrow A. The secondary air is forced upward through an induction grill  120  before entering an induced air plenum  122  within the chamber  112 . The induced air plenum  122  is provided with a sterilization means, such as an ultra violet (UV) light bulb  124  that creates an irradiate cavity  126 , which functions to sterilize the secondary air as it passes through the irradiate cavity  126 . In an embodiment, the UV light bulb  124  is secured to the end walls of the chamber  112  by a mounting bracket  128 . In the preferred embodiment, the UV light bulb  124  is preferably a 540 μW/cm2, ¾″ in diameter UV bulb. While the preferred embodiment utilizes an ultraviolet light bulb as a sterilization means for sterilizing the secondary air within the irradiate cavity  126 , the present invention is not intended to be so limited in this regard. In particular, other sterilizing irradiate light systems/means may also be utilized within the irradiate cavity  126  to sterilize the secondary air without departing from the broader aspects of the present invention. 
         [0025]    As further shown in  FIG. 2 , a reflective mirror  130 , located beneath the UV bulb  124 , is arcuate in shape to redirect a portion of the UV light from the UV bulb  124  upwards towards the top of the irradiate cavity  126 . Importantly, the reflective mirror  130  acts to prevent direct UV light from entering the occupied area. 
         [0026]    An ultra violet (UV) light absorbing shield  132  is positioned along the top of the irradiate cavity  126 , directly above the UV light bulb  124 . The UV light absorbing shield  132  is made from or coated with UV light absorbing material to aid inhibiting the escape of UV light from the chamber  112 . As shown in  FIG. 2 , the shield  132  is preferably angled such that UV light will not be reflected directly back into the occupied space between the chilled beam  110 . In combination with the reflective mirror  130 , the absorbing shield  132  thus provides a safety feature by containing the UV light within the chilled beam  110 . 
         [0027]    In another embodiment, the internal shapes and surfaces of the air plenum  116 , and indeed the chamber  112  as a whole, may be specifically designed using ultra violet light absorbing material and/or paint so that there is substantially no direct light leakage from the chilled beam  110  into the occupied space. 
         [0028]    In operation, primary air from the central air handling system is supplied through the primary inlet  114  to the primary air plenum  116 . The primary air is then directed through the rows of induction nozzles  118  towards the outer edges of the chamber  112  to induce movement of the sterilized, secondary air down and out of chamber  112 . The movement of the sterilized, secondary air causes additional secondary air from the room to be induced to move up and into the induced air plenum  122  of the active chilled beam  110 , as illustrated by the direction of arrow A. Within the irradiate cavity  126 , the secondary air is sterilized and disinfected by the UV light emitted from the UV bulb  124 . 
         [0029]    The sterilized, secondary air then passes through a coil heat exchanger  134  and mixes with the primary air from the induction nozzles  118  and is forced to exit the chilled beam  110  down through discharge air slots  136  and outward away from the induction grill  120 . 
         [0030]    The design of the chilled beam  110  increases the residence time of the secondary air within the irradiate cavity  126 . Thus, increasing the time the particles (germs, bacteria, etc.) of the secondary air will be exposed to direct or indirect UV light emitted from the UV bulb  124 . Through testing, it has been demonstrated that the induced air exposure time of the chilled beam  110  is approximately 0.64 seconds per pass, an exposure time of 3.84 seconds/hour, yielding an airborne  E. Coli  survival rate of 0.0014%. With reference to  FIG. 3 ,  E. Coli  survival rate as a function of exposure time under UV light is shown. 
         [0031]    As discussed above, the chilled beam  10 ,  110  of the present invention is an HVAC terminal device located within an occupied space and which operates on the basis of inducting room air, with or without a coil heat exchanger, to sterilize and/or disinfect the induced room air by means of a UV light bulb. As further discussed above, the reflective mirror  30 ,  130  and angled plate  32 /UV light absorbing shield  132  within the induced air plenum  18 ,  118  minimizes “leakage” of the UV light from the chilled beam  10 ,  110  into the occupied space. 
         [0032]    Although this invention has been shown and described with respect to the detailed embodiments thereof, it will be understood by those of skill in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed in the above detailed description, but that the invention will include all embodiments falling within the scope of this disclosure.