Abstract:
A fill sheet arrangement in a direct heat exchange section of a cooling tower is provided. Each fill sheet includes ridges, grooves, separators, and an air inlet louver zone itself having ridges, grooves and separators, that improve the performance of the fill sheet arrangement when installed as a direct heat exchange section of a cooling tower. The air inlet louver zone improves the air flow capabilities and performance of the direct heat exchange section by limiting the evaporative liquid from leaving the fill sheet.

Description:
[0001]    This application is a continuation-in-part of U.S. application Ser. No. 14/529,941, filed Oct. 31, 2014. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to air inlet louver zone of heat and mass transfer media, or fill sheet arrangement within the direct heat exchange portion of a cooling tower. More particularly, the present invention relates to inlet louver zone attached to a fill sheet that is used in a direct heat exchange unit, which could be a cooling tower. 
         [0003]    The heat and mass transfer media, or fill sheet arrangement, is generally vertically oriented with an evaporative liquid, usually water, coursing over the material, usually flowing downwardly, with an air stream directed usually transversely but potentially concurrent or cross current through the spaced fill sheet direct cooling section. The air interacts with the evaporative liquid for heat and mass transfer. 
         [0004]    The integrated air inlet louver zone, hereafter called louver zone, is attached to an edge of fill sheet, is a part of fill sheet, directs airstream to fill sheet, and limits evaporative fluid from leaving the fill sheet beyond the fill sheet edge. 
         [0005]    When a pair of fill sheets are stacked a gap forms between two fill sheets&#39; evaporative areas but a plurality of air tunnels forms between two fill sheets&#39; louver zones. These air tunnels, which are generally hexagonal in shape, form a straight pattern that matches well to the gap contour between the pair of fill sheets. Multiple repeats of the pair of fill sheets form a fill pack, and multiple repeats of a pair of louver zones form a louver pack within a fill pack. 
         [0006]    The louver pack prevents evaporative liquid from splashing out of the fill pack. The louver zone&#39;s plurality of ridges and grooves are sloped downward toward the evaporative area so that the evaporative liquid that is splashed on to the louver zone is flowed back toward the evaporative area of the fill pack. 
         [0007]    To prevent evaporative liquid from falling between two adjacent louver zones, one louver zone&#39;s plurality of ridges must align and touch adjacent louver zone&#39;s plurality of grooves so that there is no gap between the plurality of ridges and the plurality of grooves. Otherwise, two adjacent louver zones can nest and a large gap between louver zones can form within the louver pack. In this invention, during stacking, two adjacent inlet louvers are guided into an aligned location by the male indexer of the first louver zone riding on one of the guide walls of the second louver zone so that a plurality of fill sheet spacers located in the evaporative area can easily lock in the fill sheets in place with respect to each other. 
         [0008]    For best thermal performance of a cooling tower, it is critical that the evaporative areas of the fill pack receive well distributed air streams from their louver pack. In this invention, a plurality of male indexers within the louver pack is designed so the male indexers can be positioned inside the plurality of air tunnels while preserving both the hexagonal shape and the straight pattern of a plurality of air tunnels that match so well to the gap opening shape of the evaporative areas. 
         [0009]    For best thermal performance of a cooling tower, it is also critical that louver pack&#39;s plurality of indexing features does not incur significant air pressure drop by blocking the cooling air that travels toward the evaporative areas of the fill pack. Air pressure drop is caused by traveling air blocked by an object with a cross sectional area. A larger cross sectional area blocks more air and causes higher pressure drop. This invention uses a plurality of recessed ridges in the louver pack to decrease the size of overall cross sectional area of plurality of indexing features. A recessed ridge is located inside one of plurality of air tunnels that also houses one of plurality of male indexers. The recessed ridge lowers a small portion of the ridge of the air tunnel so that the male indexer inside the air tunnel does not have to be so tall to reach the ridge of the air tunnel. A shorter male indexer has a smaller cross sectional area, when viewed from the air tunnel opening, than a taller male indexer, and the smaller cross sectional area allows larger air passageways on both sides of shorter male indexer. A small increase in the air blockage by adding of the recessed ridge in the air tunnel is more than offset by the large increase in the air passageways. Because fill sheets, which include louver zones and a plurality of male indexers, are made from thermal forming of thin sheets of plastic, all of the fill sheet features require a draft angle of a minimum of 15°˜17°. By using the recessed ridge, the cross sectional area of the male indexers can be decreased while maintaining the minimum draft angle. 
         [0010]    In order to further reduce the pressure drop within the air tunnel, this invention also uses curved ridge cutouts and air bypasses. In one of plurality of air tunnels that houses a male indexer, a pair of curved ridge cutouts is made to two opposing tunnel walls near the base of the male indexer. These curved ridge cutouts in the air tunnel increase the size of air passageways and allow air to go around the male indexer freely and with only a minimum air pressure drop. These curved ridge cutouts start near the base of a male indexer and opens up toward the plane of a plurality of ridges at an angle that ranges from 30° to 60° such that a portion of the two ridges at the top of the curved ridge cutouts are lowered slightly and two bypass openings are formed between the male indexer tunnel and its two adjacent tunnels. These two bypass openings allow air to travel through from two adjacent tunnels to the male indexer tunnel so that the air distribution going into the fill pack is better maintained than the design without the bypass openings. 
       SUMMARY OF THE INVENTION 
       [0011]    The invention made improvements to the air inlet louver zone included in the fill sheet near the first side edge of the fill sheet arrangement. Each fill sheet includes an air inlet louver zone comprised of a plurality of gradually raised surfaces that lead to form a plurality of raised ridges of each fill sheet. A pair of air inlet louver zones stacked together forms a plurality of air tunnels between two air inlet louver zones. 
         [0012]    The invention made improvements, more specifically, to the indexing feature inside one of plurality of air tunnels. The invention&#39; indexing feature comprises a male indexer that aids alignment of louver zones during stacking, a pair of curved ridge cutouts made to the air tunnel walls in order to both minimize the air pressure drop and create bypass openings to adjacent tunnels, a recessed ridge to minimize the cross sectional area of the male indexer in order to minimize the air tunnel blockage thereby increasing the size of air passageways, and two guide walls that are attached to the recessed ridge to guide the male indexer toward the recessed ridge. These components working together improve the stacking of the fill sheets while maintaining the nice distribution of air streams going into the fill pack&#39;s evaporative area. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    In the drawings, 
           [0014]      FIG. 1  is a side view of a first fill sheet in accordance with an embodiment of the present invention; 
           [0015]      FIG. 2  is a partial view of a first inlet louver zone showing a male indexer and adjacent raised surfaces in accordance with an embodiment of the present invention; 
           [0016]      FIG. 2 a    is a partial view of a first inlet louver zone showing an enlarged plan view of a male indexer and adjacent raised surfaces in accordance with an embodiment of the present invention; 
           [0017]      FIG. 2 b    is a partial view of a first inlet louver zone showing an enlarged isometric view of a male indexer and adjacent raised surfaces in accordance with an embodiment of the present invention; 
           [0018]      FIG. 3  is a partial view of a first inlet louver zone showing a male indexer and curved ridge cutouts in adjacent raised surfaces in accordance with an embodiment of the present invention; 
           [0019]      FIG. 4  is a perspective side view of a second fill sheet in accordance with an embodiment of the present invention; 
           [0020]      FIG. 5  is a partial view of a second fill sheet showing second inlet louver zone in accordance with an embodiment of the present invention; 
           [0021]      FIG. 6A  is a schematic view of a portion of a first and second inlet louver zone showing a male indexer in accordance with an embodiment of the present invention; 
           [0022]      FIG. 6B  is a view of a portion of a first and second inlet louver zone showing a male indexer in accordance with an embodiment of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0023]    Referring now to  FIG. 1  of the drawings, a first fill sheet is shown at  10  and a first inlet louver zone is shown at  15 . First fill sheet  10  is shown to be of a generally rectangular and generally planar structure; however, it should be understood that based on design of installation needs first fill sheet  10  may be of a square or trapezoidal structure as well. First fill sheet  10  is seen to comprise a top edge  11 , bottom edge  12 , first side edge  18 , and second side edge  14 . Cooling air typically enters from the direction of first side edge  18  and travels and exits towards the general direction of second side edge  14 . Included in first fill sheet  10  is first inlet louver zone  15  extending from first inlet edge  18  to first transition edge  13 . It is noted that first transition edge  13  may be straight or curved. First inlet louver zone  15  is shown to be of a generally rectangular and generally planar structure; however, it should be understood that based on the design of installation needs first inlet louver zone  15  may be of a square or trapezoidal structure as well. First inlet louver zone  15  extends from first side edge  18  to first transition edge  13  and from top edge  11  to bottom edge  12 . Generally, when installed in a direct heat exchange unit, possibly as a component of a cooling tower, evaporative liquid, usually water, flows downwardly onto top edge  11  and across first fill sheet  10 , and exits bottom edge  12 . First side edge  18  is typically an air inlet edge wherein air is forced or drawn cross-current to the evaporative liquid downward flow to exit from second side edge  14 . Such combination of evaporative liquid generally flowing down and cross-current air flow acts to remove heat from the evaporative liquid by both a heat and mass transfer operation. It should be understood that air flow may be somewhat counter current or con-concurrent with the evaporative liquid downward flow, depending on the design of the direct heat exchange unit. 
         [0024]    Each first fill sheet  10  including first inlet louver zone  15  is usually comprised of polyvinyl chloride, polypropylene, or any other plastic sheet formed in a press, vacuum forming, or molding operation. 
         [0025]    First fill sheet  10  is seen to comprise of a plurality of first fill sheet ridge  34  on the rear surface of first fill sheet  10  extending from first transition edge  13  to second side edge  14 . Alternating with first fill sheet ridges  34  are first fill sheet grooves  35 . 
         [0026]    First inlet louver zone  15  is also seen to comprise of a plurality of first ridges  20  extending length wise from first side edge  18  to first transition edge  13  matching the shapes of a plurality of first fill sheet ridge  34 . Alternating with first ridge  20  are first grooves  21 , which also extend lengthwise across first inlet louver zone  15  from first side edge  18  to first transition edge  13  at an inclined angle. 
         [0027]    Referring now to  FIG. 2 ,  FIG. 2 a   , and  FIG. 2 b   , first fill sheet  10  is shown and first louver zone  15  is also seen to comprise a first male indexer  30 , first male separators  31 , and first recessed ridges  32 .  FIG. 2 a    is an enlarged figure of an area near first male indexer  30 , and  FIG. 2 b    is an isometric view of an enlarged figure of an area near first male indexer  30 . 
         [0028]    A plurality of alternating first groove  21  and first ridge  20  cover most of first louver  15 . Connecting a plurality of first ridge  20  to a plurality of first groove  21  are a plurality of air tunnel walls  38 . 
         [0029]    First male indexer  30  extends upwardly from one of a plurality of first groove  21  past the plane of a plurality of first ridge  20 . The height of first male indexer  30  is discussed more in  FIG. 6A  description section. 
         [0030]    First male separator  31  extends upwardly from the plane of a plurality of first groove  21  until the top flat surface of first male separator is flushed with first ridge  20 . Each first male separator  31  is located generally in the middle of one of plurality of first ridge  20 . First male separator  31  are generally spaced from 3 to 6 inches apart. 
         [0031]    First recessed ridges  32  extends upwardly from the plane of a plurality of first groove  21  to slightly lower than a plurality of first ridge  20 . There are two first guide walls  33  per each first recessed ridge  32 . More about first guide wall  33  is discussed in  FIG. 6A  description section. 
         [0032]    There are two first curved ridge cutouts  36  on each side of first male indexer  30 , and first curved ridge cutouts  36  are made by gauging out air tunnel walls  38  adjacent first male indexer  30  until a portion of first ridge  20  is lowered to form locally lowered ridge  37 . First recessed ridge  32  and its two accompanying first guide walls  33  are shown clearly. The angle between first guide wall  33  and the plane of the plurality of first groove  21  is between 30° and 60°. 
         [0033]    Referring now to  FIG. 3 , first fill sheet  10  is shown with a plurality of first ridge  20  and first curved ridge cutout  36  on two adjacent first ridges  20  of first male indexer  30 . 
         [0034]    Referring now to  FIG. 4 , second fill sheet  40  is shown. 
         [0035]    First fill sheet  10  and second fill sheet  40  could be identical. Therefore, details shown in  FIG. 2 a    and  FIG. 2 b    could also be applied to second fill sheet  40 . By making these sheets identical and by stacking them in the same orientation except one sheet slightly shifted from another so that an air gap could be formed between sheets as shown in US 2015/0034277, the manufacturing cost could be reduced. 
         [0036]    Similar to first fill sheet  10 , second fill sheet  40  is a generally rectangular, generally planar structure, having top edge  41 , bottom edge  42 , first side edge  43 , and second side edge  44 . 
         [0037]    Included in second fill sheet  40  is second inlet louver zone  50  extending from first inlet edge  43  to transition edge  51  and from top edge  41  to bottom edge  42 . It is noted that transition edge  51  may be straight or curved. Second inlet louver zone  50  is seen to be quite similar to first inlet louver zone  15  in that second inlet louver zone is shown to be of a generally rectangular and generally planar structure; however, it should be understood that based on design of installation needs second inlet louver zone  50  may be of a square or trapezoidal structure as well. 
         [0038]    Second fill sheet  40  including second inlet louver zone  50  is again quite similar or identical to first fill sheet  10  there to in being comprised of polyvinyl chloride, polypropylene, or any other plastic sheet made in a pressing, vacuum forming, or molding operation. 
         [0039]    Further, second fill sheet  40  is seen to comprise a series of second fill sheet ridges  45  on the front surface of second fill sheet  40  and alternating series of second fill sheet grooves  46  on the front surface of second fill sheet  40 . Second fill sheet ridges  45  extend lengthwise from transition edge  51  to second side edge  44  and second fill sheet grooves  46  extend lengthwise from transition edge  51  to second side edge  44 . 
         [0040]    Second inlet zone  50  is seen to comprise a series of second ridges  52  extending from first edge  43  to transition edge  51 . Similarly, second inlet zone  50  is seen to comprise a series of second groove  53  extending from first edge  43  to transition edge  51 . Second ridge  52  aligns with second fill sheet ridge  45  and second groove  53  aligns with second fill sheet groove  46 . 
         [0041]    Referring now to  FIG. 5 , second fill sheet  40  has second inlet louver zone  50 , which is also seen to comprise a second male indexer  55 , second male separators  56 , and second recessed ridges  57 . 
         [0042]    Second male indexer  55  extends upwardly from the surface of second inlet louver zone  50 . As to be further explained, second male indexer  55  is typically located on one of plurality of second grooves  53  on the front surface of second inlet louver zone  50 . 
         [0043]    Second male separator  56  extends upwardly from the surface of second inlet louver zone  50 . As to be further explained, the extended surface of second male separator  56  is typically flushed with the plane of a plurality of second ridge  52 , and the center of second male separator  56  is typically located on second ridge  52  on the front surface of second inlet louver zone  50 . 
         [0044]    Second recessed ridge  57  extends upwardly from the surface of second inlet louver zone  50  to slightly lower than second ridge  52 . Second guide wall  58  connects second groove  53  to second recessed ridge  57 . 
         [0045]    In practice, a fill arrangement in a direct heat exchange unit would be comprised of two fill sheets, first fill sheet  10  and second fill sheet  40 , located adjacent each other and repeated multiple times as needed to form a fill pack, which is a direct heat exchanger. Subsequently, two inlet louver zones included in the two fill sheets would also be located adjacent each other and repeated multiple times as needed. 
         [0046]    In many cases first fill sheet  10  and second fill sheet  40  could be identical. By making these two fill sheets identical, one thermal forming mold could be used to produce both first fill sheet  10  and second fill sheet  40 , and the manufacturing cost could be reduced. 
         [0047]    Referring now to  FIG. 6 a   , schematics are shown wherein a portion of first inlet louver zone  15  is seen to be adjacent a portion of second inlet louver zone  50 . First inlet louver zone  15  has a plurality of first ridges  20  and a plurality of first grooves  21 . Second inlet louver zone  50  has a plurality of second ridges  52  and a plurality of second grooves  53 . 
         [0048]    First male indexer  30  is seen to extend from one of plurality of first groove  21  of first inlet louver zone  15  toward one of second recessed ridges  57  of second inlet louver zone  50 . During the assembly process of stacking first inlet louver zone  15  and second inlet louver zone  50 , as first male indexer  30  travels toward second inlet louver zone  50 , second guide wall  58  guides first male indexer  30  toward second recessed ridge  57  thereby shifting aligning first inlet louver zone  15  to second inlet louver zone  50 . 
         [0049]      FIG. 6 b    shows the desired location of first inlet louver zone  15  with respect to second inlet louver zone  50  where first male indexer  30  contacting second recessed ridge  57 . Air travels through a plurality of air tunnels  60  created by adjacent first inlet louver zone  15  and second inlet louver zone  50 , but for air tunnel  62  that is partially blocked by first male indexer  30  a pair of first curved ridge cutouts  36  allows air to go around first male indexer  30  through enlarged air passageway  63  without significant air pressure drop. Each of first curved ridge cutouts  36  also creates an air bypass opening  61  between one of locally lowered ridges  37  and one of plurality of second groove  53  on either side of male indexer  30  so that air traveling inside two adjacent air tunnels  60  can enter air tunnel  62  and equalize the air pressure difference among three air tunnels.