Abstract:
A water purification device ( 30 ) is provided for installation in an aircraft potable water system. The device ( 30 ) comprises a treatment cell ( 40 ) incorporated into the water system&#39;s plumbing and a flashlamp ( 50 ) positioned to productively transmit into the treatment chamber ( 41 ) of the cell ( 40 ). The flashlamp ( 50 ) emits short-pulse and high-intensity flashes, thereby delivering adequate UV doses (e.g., at least 40 mJ/cm 2 ) with reasonable input power (e.g., 400 watts) for an aircraft system.

Description:
RELATED APPLICATION 
       [0001]    This application claims priority under 35 USC §119(e) to U.S. Provisional Patent Application No. 61/409,457 filed on Nov. 2, 2010. The entire disclosure of this provisional patent application is hereby incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    An aircraft potable water system typically supplies water to cabin outlet facilities for selective dispensing therefrom. The dispensed liquid is used by passengers and crew for purposes calling for purified water. These uses can include, for example, washing, drinking, cooking, coffee brewing, and/or ice making. The system can integrate a UV device to ensure that the water is properly purified. According to the National Sanitation Foundation International, a minimum UV dose of 40 mJ/cm 2  is required to acceptably deactivate pathogens. 
       SUMMARY 
       [0003]    A purification device for an aircraft potable water system is provided. In this water purification device, a flashlamp emits short-pulse and high-power UV flashes to water passing through a treatment chamber. The device can be constructed compactly, lightly, and to have a useful life exceeding well beyond 1000 flights. 
     
    
     
       DRAWINGS 
         [0004]      FIG. 1  shows an aircraft with a potable water system installed thereon, the potable water system having a purification device incorporated into its plumbing. 
           [0005]      FIG. 2  shows the purification device. 
           [0006]      FIGS. 3-4  show a flashlamp and a pulse formation network of the water purification device. 
           [0007]      FIG. 5  is a graph of a short-duration and high-power pulse produced by the water purification device. 
       
    
    
     DESCRIPTION 
       [0008]    Referring now to the drawings, and initially to  FIG. 1 , an aircraft  10  with a potable water system  20  is shown. The system  20  includes plumbing  22  that supplies water to outlet facilities  24  for selective dispensing therefrom. Passengers and crew can selectively dispense potable water from the outlet facilities  24  for purposes such as showering, drinking, cooking, dish washing, coffee brewing, and/or ice making. 
         [0009]    The aircraft potable water system  20  further includes a device  30  to ensure that the water dispensed from the facilities  24  is properly purified. The location of the purification device  30  relative to the supply plumbing  22  can be selected to optimize pathogen-deactivation purposes while also being compatible with installation, inspection and maintenance. As such, various placements of the purification device  30  within the potable water system  20  are probable and presumed. 
         [0010]    Referring now to  FIG. 2 , the purification device  30  comprises a treatment cell  40  and a UV flashlamp  50 . The treatment cell  40  forms an annular chamber  41  and a hollow corridor  42  surrounded by the chamber  41 . The cell  40  can have an exterior wall  43  and end walls  44  made of a suitable UV-opaque material (e.g., stainless steel). The cell&#39;s interior wall  45  can be made of a UV-transmissive material (e.g., quartz). Water enters the chamber  41  through an inlet  46  and exits the chamber  41  through an outlet  47 . 
         [0011]    The flashlamp  50  extends through the chamber&#39;s corridor  42  whereby UV rays emitted thereby are transmitted through the cell&#39;s interior wall  45  to the water contained with the chamber  41 . As is best seen by looking additionally at  FIG. 3 , the flashlamp  50  can comprise a UV-transmissive envelope  51 , a noble gas  52  within the envelope  51 , an anode  53 , a cathode  54 , and a trigger electrode  55 . The gas  52  is selected so as to emit polychromatic UV light. Xenon is usually considered the favored gas candidate in flashlamp applications because of its relatively high conversion efficiency. That being said, neon, argon, and krypton may also be suitable contenders in certain situations. 
         [0012]    The purification device  30  further comprises a pulse formation network  60  such as is shown in  FIG. 4 . The network  60 , in its simplest form, can comprise a capacitor  61  and an inductor  62  connected in series with the flashlamp  50 . The pulse formation network  60  is architected so as to release electrical energy to the flashlamp  50  in the form of high-energy and short-duration pulses. As is graphed in  FIG. 5 , each pulse has a narrow width and extremely tall peak power. 
         [0013]    The chamber  41  can have a volume of between 1000 cm 3  and 2000 cm 3 , 1200 cm 3  and 1800 cm 3 , and/or 1400 cm 3  and 1600 cm 3 . Additionally or alternatively, the chamber  41  can be sized to provide a through pace of between 200 cm 3 /sec and 300 cm 3 /sec, between 220 cm 3 /sec and 280 cm 3 , and/or between 240 cm 3 /sec and 260 cm 3 /sec, and/or to provide a dwell time of 2 seconds to 10 seconds, 4 seconds to 8 seconds, and/or 5 seconds to 7 seconds. 
         [0014]    With the illustrated annular geometry, for example, an outer diameter of 100 mm and an inner diameter of 16 mm would result in a pace and dwell time within these ranges for a potable water system having a flow rate of approximately 4 gallons per minute or 15 liters per minute. 
         [0015]    The flashlamp  50  can have a cross voltage of between 2000 and 4000 volts, between 2500 and 3500 volts, and/or between 2800 and 3200 volts, a discharge current of between 700 and 1500 amps, between 800 and 1300 amps, and/or between 900 and 1200 amps, and/or impedance parameter of between 30 and 70 ohms 1/2 amp 1/2 , between 40 and 60 ohms 1/2 amp 1/2 , and/or between 45 and 55 ohms 1/2 amp 1/2 . These voltages, currents, and parameters can be reached with a Xenon flashlamp having 5 mm diameter, an arc length of 200 mm, a fill pressure of 450 torr, and a plasma resistivity of 0.015 ohms. 
         [0016]    With such a lamp, the water purification device  20  can be constructed compactly and/or lightly. Specifically, for example, the device  20  can occupy less than two cubic feet and/or less than one cubic meter. Additionally or alternatively, the water purification device  20  can weigh less than twenty pounds and/or less than ten kilograms. 
         [0017]    The pulse formation network  60  can be constructed to provide pulse widths of between 5 and 15 microseconds (e.g., less than 20 microseconds, less than 18 microseconds, less than 16 microseconds, less than 19 microseconds, etc.) and/or provide between 10 and 30 flashes per second (e.g., at least 5 flashes per second, at least 7 flashes per second, at least 10 flashes per second, etc.) 
         [0018]    The pulse formation network can also be constructed to provide peak power outputs between 20000 Watts and 30000 Watts (e.g., greater than 10000 Watts, greater than 20000 Watts, greater than 25000 Watts, greater than 28000 Watts, greater than 29000 Watts, etc.). Such high power outputs can correspond to extremely high peak plasma temperatures, such as over 7000° K, over 8000° K, and/or over 9000° K. This can be accomplished with an input voltage of 2950 volts, a total circuit inductance of 4.96 micro Henries, and capacitance of 4.75 microfarads. 
         [0019]    Although the aircraft  10 , the potable water system  20 , the purification device  30 , the chamber  40 , the flashlamp  50 , and/or the pulse formation network  60 , have been shown and described with respect to a certain embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings.