Abstract:
A heat exchanger has heat exchange elements and an inlet header and an outlet header that fluidly communicate with the heat exchange elements. The inlet header has a fluid inlet. The heat exchange elements are connected to the inlet header along a length of the inlet header and are various distances from the fluid inlet. A distributor is located inside the inlet header, which distributor forms a perforated wall between the fluid inlet and the heat exchange elements. The distributor provides back pressure to incoming fluid into the inlet header, wherein the fluid is evenly distributed between the heat exchange elements.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to heat exchangers and more particularly to evaporative condensers and coolers. 
       BACKGROUND OF THE INVENTION 
       [0002]    Evaporative condensers are condensers where water is sprayed onto a heat exchanger to condense a gas into a liquid. For example, in a refrigeration system, a compressor compresses a heat exchange fluid, such as ammonia. The output of the compressor is hot, high pressure ammonia gas. The gas is provided to a condenser, where it condenses into a liquid. The liquid ammonia then passes through an expansion valve, where it drops in pressure and decreases in temperature to provide refrigeration. 
         [0003]    In a conventional evaporative condenser, the heat exchanger for the fluid is a set of coils or tubes. The ammonia gas flows into a header and then into the coils. Condensed or liquid ammonia flows out of the coils to an outlet header. 
         [0004]    In a cooler, the liquid disposes heat to the spraying water on the outside of the coils. The cooler uses an input header for the liquid. 
         [0005]    It is desirable to make improvements over conventional condensers. It is also desirable to make improvements to conventional coolers. 
       SUMMARY OF THE INVENTION 
       [0006]    A heat exchanger comprises inlet headers. The inlet header has a fluid inlet and an interior cavity. The outlet header has a fluid outlet. Heat exchange elements are coupled to and in fluid communication with the inlet and outlet headers. The heat exchange elements comprise first and second heat exchange elements. The first heat exchange element is coupled to the inlet header at a first location. The second heat exchange element is coupled to the inlet header at a second location. The first location is closer to the fluid inlet than is the second location. A distributor is located in the interior cavity of the inlet header between the fluid inlet and the heat exchange elements and extends between the first and second locations and the fluid inlet. The distributor causes back pressure for fluid entering the inlet header from the fluid inlet. 
         [0007]    In accordance with one aspect, the distributor comprises a perforated wall. 
         [0008]    In accordance with another aspect, the heat exchange elements comprise coils. 
         [0009]    In accordance with another aspect, the inlet header comprises a pipe and the distributor comprises a perforated plate located in the pipe. 
         [0010]    In accordance with another aspect, an evaporative condenser comprises a condenser unit. A water sprayer is located above the condenser unit. A fill section is located below the condenser unit. A basin located below the fill section. At least one fan for flowing air through the condenser unit and the fill section is provided. The condenser unit comprises an inlet header and an outlet header. The inlet header has a fluid inlet at a first location. The inlet header has heat exchange elements at locations other than the first location. A distributor is in the inlet header between the first and other locations. The distributor applies back pressure to incoming fluid in the inlet header. 
         [0011]    In accordance with still another aspect, the distributor further comprises a perforated wall. 
         [0012]    In accordance with still another aspect, the heat exchange elements comprise coils. 
         [0013]    In accordance with another aspect, the inlet header comprises a pipe and the distributor comprises a perforated plate located in the pipe. 
         [0014]    In accordance with still another aspect, the perforated plate is flat. In accordance with still another aspect, the perforated plate is curved. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a schematic view of an evaporative condenser. 
           [0016]      FIG. 2  is a top plan view of a portion of the heat exchanger condenser and inlet header. 
           [0017]      FIG. 3  is a cross-sectional view of the header of  FIG. 2 , taken along lines III-III. 
           [0018]      FIGS. 3A  and  FIG. 3B  are cross-sectional views of the header, similar to  FIG. 3 , but of other embodiments. 
           [0019]      FIG. 4  is a view of a distributor.  FIG. 5  shows the distributor in accordance with another embodiment. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0020]    The efficiency of any heat exchanger depends upon whether the incoming fluid is distributed evenly over all portions of the heat exchanger. For example, if the heat exchanger has coils arranged side by side, if the center coils receive more fluid than the other coils, then efficiency declines. 
         [0021]    The heat exchanger described herein evenly distributes the incoming fluid throughout all portions thereof, thereby increasing efficiency. Although the heat exchanger can be a cooler, the particular application shown is in an evaporative cooler. 
         [0022]      FIG. 1  shows an evaporative condenser  11 . Sprayers  61  spray water onto a heat exchanger  13 . A fan  15  draws air  17  through the wetted heat exchanger  13  to provide evaporative cooling and condensing of a fluid (typically from a gas into a liquid). 
         [0023]    The evaporative condenser  11  has a housing  19 . The heat exchanger  13  is located in the housing. Below the heat exchanger is a fill or stuffing section  21 . The fill section  21  has layers that expose descending water to air flow. The layers can be made of plastic, etc. Below the fill section  21  is a basin  23  to catch the water. The housing also has a plenum  25  that communicates with the heat exchanger and the fill section. The fan  15  draws air through the heat exchanger  13 , in through the fill section  21 , through demisters  27  or dehydrators, into the plenum  25  and out of the housing. 
         [0024]    The heat exchanger  13  has heat exchange elements  31  that extend from an inlet header  33  to an outlet header  35 . In the preferred embodiment, the heat exchanger elements  31  are coils, however the heat exchange elements could be plates. Thus, there is a first set of coils  31 A (see  FIG. 2 ), a second set of coils  31 B, a third set of coils  31 C and so on. Gas enters the inlet header  33  and then the coils  31 . Once in the coils, the gas condenses to a liquid. The liquid exits the coils  31  into the outlet header  35 . 
         [0025]    The inlet header  33  has an inlet pipe  37  (see  FIG. 1 ) which delivers the gas to the inlet header  33 . Likewise, the outlet header  35  has an outlet pipe  39 , which removes the liquid from the outlet header. Referring to  FIGS. 2 and 3 , the heat exchanger and inlet header are shown. In the preferred embodiment, the inlet header  33  is a pipe with an interior cavity  41  that extends between two ends  43 . The header can be circular in transverse cross-section, rectangular, etc. The inlet pipe  37  and the heat exchange elements  31  all communicate with the interior cavity  41 . The heat exchange elements are connected with the inlet header by way of feed pipe stubs  38 . The ends  43  of the header are closed such as with caps. 
         [0026]    The inlet pipe  37  is typically located in the center between the ends  43 . The coils  31  are spaced out along the length of the header from one end to the other end  43 . Consequently, some coils are located closer to the inlet pipe  37  than other coils. For example, centrally located coils  31 A- 31 D are closer to the inlet pipe than are end coils  31 E,  31 F,  31 G,  31 H. 
         [0027]    In order to evenly distribute the end feed fluid to all of the heat exchange coils, a distributor  51  is provided in the interior cavity  41  of the inlet header  33 . As shown in  FIGS. 3 and 4 , the distributor  51  is a plate with perforations  53 . In the preferred embodiment, the perforations are circular holes; however the perforations could be any shape such as slots, etc. The number and size of the perforations is determined relative to the flow of the incoming gas. The distributor  51  applies a back pressure to the gas in the inlet header  33 . This back pressure causes the gas to move from the central location of the inlet header out along the length of the inlet header toward the ends  43 . This in turn promotes even distribution of the gas to the coils  31 . 
         [0028]    To assemble the inlet header  33 , the inlet pipe  37  and feed pipes  38  are connected to the header. With the interior cavity  41  of the header exposed by way of an open end  43 , the distributor plate  51  is inserted into the header interior cavity. The length of the distributor plate is slightly less than the length of the header. The distributor plate is positioned (vertically as shown in the orientation of  FIG. 3 ) and then tacked or welded in place. The tacked points need only be at the ends and serve to immobilize the distributor inside the header. Then the end caps can be put onto the header. 
         [0029]    Because the plate is porous, there can be gaps between the plate and the header.  FIG. 5  shows another embodiment of the distributor  51 A, having openings  53 A in the sites adjacent to the header  33 . 
         [0030]    The distributor plate  51  is located between the inlet pipe  37  and the coils  31  so that gas flowing into the header passes through the distributor plate to flow into the coils. The distributor plate  51  can be positioned along a vertical chord, as shown by solid lines in  FIG. 3 . The plate is positioned closer to the feed pipes than to the inlet pipe  37 . The plate  51  could be positioned closer to the inlet pipe  37 , as shown by dashed lines in  FIG. 3 . The plate could also be positioned through the center of the header instead of along a chord. 
         [0031]      FIG. 3  shows the distributor plate  51  as flat. The distributor plate  51  need not be flat but can be curved.  FIG. 3A  shows the distributor plate as concave relative to the inlet pipe  37  and can be closer to the inlet pipe (as shown by dashed lines) or closer to the feed pipes  38  (as shown in dashed lines).  FIG. 3B  shows the distributor plate as convex relative to the inlet pipe  37  and can be closer to the feed pipes  38  (as shown in solid lines) or to the inlet pipe  37  (as shown in dashed lines). 
         [0032]    The outlet header is not provided with a distributor. 
         [0033]    In operation, gas enters the header. While some gas enters the coil or coils  31 A- 31 D adjacent to the inlet pipe  37 , much of the gas flows toward the ends of the header and into the associated coils (for example  31 E- 31 H). The coils, which are all the same size, all receive equal amounts of the gas. Thus, the heat exchanger operates more efficiently. 
         [0034]    Although the distributor has been described in conjunction with an evaporative condenser as the preferred embodiment, it can also be used with other heat exchangers, such as coolers. The heat exchanger described above can be used as a cooler. When used as a cooler, the distributor is in the inlet header (which is now  35 ). Liquid enters the header and encounters back pressure due to the distributor  51 . The liquid thus extends along the length of the header and enters the coils  31  as spaced along the length of the header. 
         [0035]    The foregoing disclosure and showings made in the drawings are merely illustrative of the principles of this invention and are not to be interpreted in a limiting sense.