Abstract:
A filtration system includes a frame directing a fluid flow through the filtration system. An ionization array is located in the frame and has an ionizer current flowing therethrough. The system further includes a media filter having a plurality of media fibers arranged to capture particles flowing therethrough and a conductive surface located at the media filter and having a filter current flowing therethrough. A comparator is utilized to determine a difference between the ionizer current and the filter current, and compare that difference to a predetermined range.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to air filtration systems. More specifically, electrostatic filters for air filtration systems and installation thereof 
         [0002]    In air filtration systems, for example, electrically enhanced air filtration systems, electrostatic filters installed in the systems collect impurities in an airflow through the system before the airflow is circulated through a space such as a home or other building. The air filtrations utilize high voltage and ions to enhance the particle collection efficiency of the electrostatic filters. Such filters incorporate a conductive electrode into the filter at a downstream side of the filter. In some instances a filtration system may wet, become contaminated with electrically conductive dusts or other particles, or suffer a component failure which results in the high voltage not only producing ions in the system, but resulting in a leakage of charge to other portions of the purification system. Such charge leakage results in a filter performance reduction and often presents a safety hazard. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0003]    According to one aspect of the invention, a filtration system includes a frame directing a fluid flow through the filtration system. An ionization array is located in the frame and has an ionizer current flowing therethrough. The system further includes a media filter having a plurality of media fibers arranged to capture particles flowing therethrough and a conductive surface located at the media filter and having a filter current flowing therethrough. A comparator is utilized to determine a difference between the ionizer current and the filter current, and compare that difference to a predetermined range. 
         [0004]    According to another aspect of the invention, a method of operating an filtration system includes directing a fluid flow through the filtration system and ionizing the fluid flow via an ionizer current flowing through an ionization array. Particles in the fluid flow are collected at a media filter, the media filter having a conductive surface with a filter current flowing therethrough. A difference between the ionizer current to the filter current is determined and the difference between the ionizer current and the filter current is compared to a predetermined range. 
         [0005]    These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0007]      FIG. 1  schematically illustrates an embodiment of an air filtration system; 
           [0008]      FIG. 2  is a schematic cross-sectional view of an embodiment of an air filtration system; 
           [0009]      FIG. 3  is a schematic view of an embodiment of a media filter and detection circuit for an air filtration system; and 
           [0010]      FIG. 4  illustrates another embodiment of an air filtration system. 
       
    
    
       [0011]    The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0012]    Shown in  FIG. 1  is a view of an embodiment of an air filtration system  10 . The air filtration system  10  of  FIG. 1  is an electrically enhanced air filtration system  10  having a replaceable filter. It is to be appreciated, however, that electrically enhanced air filtration systems  10  having, for example, cleanable filter elements, are within the scope of the present disclosure. 
         [0013]    The air filtration system  10  includes a field enhancement module (FEM)  12 , shown exploded in  FIG. 1 . The FEM  12  includes a frame  14 . The frame  14  is configured to arrange the components of the FEM  12  which are secured therein. At an upstream end  16  of the FEM  12 , relative to an airflow direction  18  of air through the filtration system  10 , is an ionization array  22  with, in some embodiments, a safety screen  20  located upstream of the ionization array  22 , which also acts as an upstream ground for the FEM  12 . The ionization array  22  is an array of points sufficiently sharp such as to produce corona discharge when a pre-determined voltage is applied. For example, the ionization array may comprise a plurality of thin wires, barbed wires, or any structure capable of producing the corona needed to yield ions. A field-generating array  24  is located downstream of the ionization array  22 . It is to be appreciated that, in some embodiments, the field generating array  24  may be omitted from the system  10 . The field-generating array  24  and the ionization array  22  are both connected to and powered by a high voltage power supply  26 . A media filter  28  is disposed in the frame  14  downstream of the field-generating array  24 . 
         [0014]    Referring now to  FIG. 2 , when the power supply  26  (shown in  FIG. 1 ) is activated, an ionizer current  40  passes through the ionization array  22  to ionize gas (air) molecules via a corona discharge at the array points. The ionized gas molecules charge particles  30  in an airstream  32  passing through the FEM  12 . The voltage between the field-generating array  24  and the downstream filter ground polarizes a plurality of media fibers  34  of the media filter  28 , which causes the ionized particles  30  to be attracted to and captured by the media fibers  34 . Additionally, charge from the ionization array  22  passing into the media filter  28  may charge the fibers to enhance particle  30  capture effectiveness. 
         [0015]    To enhance performance of the media filter  28  and polarize the media fibers  34 , the media filter  28  includes a conductive surface  36  at, in some embodiments, a downstream side  38  of the media filter  28 . The conductive surface  36  may be, for example, a layer of carbon paint applied to the media filter  28 , or a screen affixed to the media filter. The ionizer current  40  passing through the ionization array  22  results in a filter current  42  ( FIG. 3 ) in the conductive surface  36  of the media filter  28 , differing by a predetermined amount from the ionizer current  40  during normal operation of the air filtration system  10 . Referring to  FIG. 3 , the air filtration system  10  includes a comparator  44  electrically connected to the ionization array  22  and the media filter  28 . The comparator  44  continuously monitors the current difference between the ionizer current  40  and the filter current  42 . A current difference outside of a predetermined range indicates a current leakage into the FEM  12 , for example, into the frame  14 . Current leakage is indicative of poor filtration system  10  health and results in reduced performance of the media filter  28  and, if the current leakage is great enough, could result in a safety hazard, for example, fire or electrical shock. 
         [0016]    In some embodiments, once a current difference outside of the predetermined range is measured by the comparator  44 , the control system of FEM  12  communicates this information via for example, a warning light or lights, or LED or LCD message at a display  46 , shown in  FIG. 4 , on the air filtration system  10 . Further, the information may be communicated to another device, for example, a thermostat  48  or an internet-based location which displays the status of the FEM  12 . 
         [0017]    In some embodiments, when the current difference is outside of the predetermined range, the air filtration system  10  automatically shuts down in response to the indication of current leakage. In these embodiments, once shut down, the air filtration system  10  may wait for a short period of time, then attempt to restart. If the current leakage is no longer indicated, the air filtration system  10  will continue to operate. If, on the other hand, current leakage is still indicated, the air filtration system  10  will shut down again. As long as current leakage is detected, the shut down and restart process will continue for a predetermined number of times, for example, 5 cycles of shut down and restart, before the air filtration system  10  finally shuts down into a mode requiring user intervention to restart. 
         [0018]    While the media filter  28  illustrated is substantially planar, it is to be appreciated that the media filter  28  may be, for example, cylindrical or portions thereof, conical or portions thereof, or partially spherical, or other suitable shape. Further, the flow through the system  10  need not be air, but may be another gaseous and/or liquid flow. 
         [0019]    While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claim.