Abstract:
A system for providing cooled compressed air free of entrained moisture. A housing surrounds a heat exchanger and has an inlet for passage of hot compressed air into an input plenum of the housing and an outlet plenum having an outlet for the cooled and dried compressed air. The bottom of the output plenum extends below the bottom of the heat exchanger to form a trough which collects condensate that collects on the plates of the heat exchanger, flows to the bottom of the heat exchanger, and is pushed by the flow of the compressed air to the output plenum. A shield is placed between the outlet and the heat exchanger to prevent condensate spewed from the plates of the heat exchanger from passing directly across the outlet opening or directly into the outlet opening.

Description:
RELATED APPLICATIONS  
       [0001]     The present application is a continuation-in-part of U.S. patent application Ser. No. 11/722,042, filed Jun. 18, 2007 which claims priority to International Application PCT/US2005/045366 filed Dec. 15, 2005 which in turn claims priority to U.S. Provisional Application Ser. No. 60/637,055 filed Dec. 17, 2004. 
     
    
     TECHNICAL FIELD  
       [0002]     The present invention relates to the art of heat transfer; more particularly, to heat exchangers for cooling adiabatically compressed air before delivery for use; and most particularly to a compressed air aftercooler including integral passive moisture separation means for removing entrained water from cooled compressed air before delivery for use.  
       BACKGROUND OF THE INVENTION  
       [0003]     Compressed air is widely used in many industrial processes. Typically, air at ambient temperature, pressure, and dew point is adiabatically compressed by known means, such as a motor- or engine-driven piston compressor, to many times atmospheric pressure. In accordance with Boyle&#39;s Law, PV=nRT, during adiabatic compression the absolute temperature in a compressed air tank of constant volume increases in direct proportion to the increase in absolute pressure.  
         [0004]     In many applications, it is desirable to cool the compressed air before it is delivered to a header for use. In the prior art, such cooling is typically accomplished by passing the compressed air through one side of a conventional heat exchanger while passing air at ambient pressure and temperature through the other side. A known problem in the art is that such cooling of compressed air immediately produces condensation of water in the heat exchanger. It is generally undesirable that the condensate be delivered for use with the cooled compressed air; thus in the prior art sumps or active demoisturizing means may be provided for collecting and removing condensate.  
         [0005]     What is needed in the art is an improved moisture separation system, preferably passive and preferably formed integrally with an air compression aftercooler.  
         [0006]     It is a primary object of the invention to provide cooled compressed air for use substantially free of entrained moisture.  
       SUMMARY OF THE INVENTION  
       [0007]     Briefly described, a system for providing cooled compressed air free of entrained moisture comprises a housing having an inlet for receiving hot compressed air, a heat exchanger, an outlet plenum and an outlet for passing cooled and dried compressed air. At least a portion of a bottom of the output plenum may be recessed and may be lined with a moisture separating material, and a drain for passing condensate formed in the heat exchanger. In a preferred embodiment, a shield is placed between the outlet and the heat exchanger to prevent condensate spewed from the plates of the heat exchanger from passing directly across the outlet opening or directly into the outlet opening. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:  
         [0009]      FIG. 1  is a semi-schematic drawing showing a top layout of a compressed air aftercooler and passive moisture-removal improvement in accordance with the invention;  
         [0010]      FIG. 2  is a semi-schematic drawing showing a side layout of the compressed air aftercooler of  FIG. 1 ;  
         [0011]      FIG. 3  is a semi-schematic drawing showing a side layout of the compressed air aftercooler of  FIG. 1  that has been modified;  
         [0012]      FIG. 4  is a semi-schematic drawing showing a side layout of the compressed air aftercooler of  FIG. 1  with a different modification than shown in  FIG. 3 ;  
         [0013]      FIG. 5  is a semi-schematic drawing of an alternate embodiment of the lower portion of  FIG. 2 ;  
         [0014]      FIG. 6  is a semi-schematic drawing showing the top layout of  FIG. 1  with a modified condensate shield;  
         [0015]      FIG. 7  is a semi-schematic drawing showing a side layout of the compressed air aftercooler of  FIG. 6 ;  
         [0016]      FIG. 8  is a semi-schematic drawing showing a top layout of an alternative embodiment of a compressed air aftercooler and passive moisture-removal improvement in accordance with the invention;  
         [0017]      FIG. 9  is a semi-schematic drawing showing a side layout of the compressed air aftercooler of  FIG. 8 ;  
         [0018]      FIG. 10  is a perspective view of an alternate embodiment of the invention;  
         [0019]      FIG. 11  is the view of  FIG. 10  with the moisture separator shown in section;  
         [0020]      FIG. 12  is a perspective view thereof opposite to the view seen in  FIG. 10 ;  
         [0021]      FIG. 13  is a side elevational view of the sectioned moisture removal part seen in  FIG. 11 ; and  
         [0022]      FIG. 14  is a bottom plan view thereof. 
     
    
       [0023]     It will be appreciated that for purposes of clarity and where deemed appropriate, reference numerals have often been repeated in the figures to indicate corresponding features, and that the various elements in the drawings have not necessarily been drawn to scale in order to better show the features of the invention.  
       DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]     Referring to  FIGS. 1 and 2 , an improved compressed air aftercooler system  10  for aftercooling and demoisturizing compressed air is shown. By “aftercooling” is meant the removal of the adiabatic heat of compression from compressed air. A housing  12  has an inlet  14  for admitting hot compressed air  15  and an outlet  16  located in the top of the housing  12  for exhausting cooled and demoisturized air  17 . Within housing  12  is a heat exchanger  18  known in the art, for example, a conventional bar-and-plate heat exchanger having a plurality of plates  20  for separating a first flow side from a second flow side and for conducting heat therebetween. An intake plenum  22  distributes hot air  15  for flow through the first flow side of heat exchanger  18 , and an exhaust plenum  24  collects moisture-laden cooled air  26 . Coolant, for example, air at ambient temperature, is passed through the second side of heat exchanger  18  consisting of the vertical channels  19  by conventional pressurizing means (not shown).  
         [0025]     The exhaust plenum  24  has a bottom  30  which is lower than the bottom  32  of heat exchanger  18  to form a trough  34 . Placed within this trough  34  is moisture separating material  36  preferably made of a high porosity material such as preferably a metallic or plastic mesh. At the bottom of the trough  34  is a water drain  38  for passing the water collected from the hot compressed air  15 .  
         [0026]     The exhaust plenum  24  also has an arcuate shield  40  positioned between the compressed air entrance  42  of the outlet  16  and the compressed air flowing parallel with the plates  20  which would flow substantially directly across the outlet entrance  42  without the shield  40 . The shield  40  extends from the top plate  44  down to approximately the middle of the heat exchanger  18   
         [0027]     In operation of system  10 , hot moist air  15  as from a compressor enters housing  12  via inlet  14  and is distributed by intake plenum  22  into a first side of heat exchanger  18 . The coolant is passed through the channels  19  of heat exchanger  18 . Air  15  emerges from heat exchanger  18  as cooled air  26  which is collected in exhaust plenum  24  and exits the aftercooler system  10  through outlet  16 . The majority of the moisture which condenses from the compressed air during the cooling process collects on the walls of the plates  20  and flows to the floor  32  of the heat exchanger  18 . This condensate as water is pushed by the flow of the compressed air towards and into the exhaust plenum  24  where it flows into the trough  34  and down the drain  38 .  
         [0028]     While most of the condensate flows to the floor  32  of the heat exchanger  18 , some of the condensate remains on the plates  20  and is spewed out from the plates  20  into the exhaust plenum  24 . The shield  40  keeps the spewed condensate from directly entering the outlet  16 . The spewed condensate hitting the shield  40  either drops directly to the bottom of the trough  30  or is deflected to the inside back wall  46  of the housing  12  where it then drains into the trough  30 . The moisture separator  11  essentially prevents the water in the bottom of the trough from being carried by the compressed air through the outlet  16 .  
         [0029]      FIG. 3  is an alternate embodiment of the invention in which the outlet  16  is located in the bottom of the housing  12 .  
         [0030]      FIG. 4  is another embodiment of the invention in which the outlet  16  is located in the back wall  46  of the housing  12 .  
         [0031]      FIG. 5  is a semi-schematic drawing of an alternate embodiment of the lower portion of  FIG. 2  in which a slopped bottom  48  has been formed in the trough  30  to better drain the water in the trough  30  into the drain  38 .  
         [0032]      FIG. 6  is a semi-schematic drawing showing the top layout of  FIG. 1  with a modified condensate shield  50  which is curved in the middle and has straight plates attached to the ends of the curve. It will be appreciated that other configurations of the condensate shield can be used such as, for example, a V-shaped shield and a non circular shield.  
         [0033]      FIG. 7  is a semi-schematic drawing showing a side layout of the compressed air aftercooler of  FIG. 6  in which the shield  50  extends down to close to the top of the mesh  36 . The shield  40  of  FIGS. 1-5  could, in the same manner, extend down to the top of the mesh  36  in other embodiments.  
         [0034]      FIG. 8  is a semi-schematic drawing showing a top layout of an alternative embodiment of a compressed air aftercooler and passive moisture-removal improvement in accordance with the invention. In  FIG. 8  the output  16  is on the narrow side  60  of the exhaust plenum  24 . A rectangular shield  62  has one long edge located at the junction of the side  60  and the cooled air outlet end of the heat exchanger  18 . The shield  62  is at an angle  64  with respect to the end of the cooled air outlet of the heat exchanger  18 . In the preferred configuration of this alternative embodiment the angle  64  is 15°.  
         [0035]      FIG. 9  is a semi-schematic drawing showing a side layout of the compressed air aftercooler of  FIG. 8 . As shown in  FIG. 9  the shield  60  extends from close to the top of the mesh  36  to near the top plate  44 .  
         [0036]     Referring now to the  FIGS. 10-14 , there is shown yet another possible embodiment of the present invention comprising an aftercooler body  110 . Aftercooler  110  generally includes a vertically-oriented core heat exchanger  112 , manifolds  14   a,b  and  16   a  located on opposite sides of core  112 , and a moisture removal plenum  118 . In one possible embodiment, plate  117  bisects core  112 , dividing core  112  and manifolds  114   a,b  and  116   a  into two separate circuits for the cooling of different substances. For example, a first fluid circuit is defined which may be used for cooling oil which has been heated in the air compressor (not shown) which delivers heated, compressed air to the air cooler. The heated oil would then enter manifold  114   a  at inlet  120  and pass through this first circuit of the heat exchanger  112 , exiting manifold  114   a  at outlet  122  and redirected to the air compressor. An oil drain  124  may also be included in this fluid circuit.  
         [0037]     The second fluid circuit (or only fluid circuit depending on the chosen embodiment) is defined with hot, compressed, moisture-laden air entering manifold  14   b  at air inlet  126  whereupon it is directed through heat exchanger  112 , exiting at the series of exchanger air outlets  144  and finally exiting cooler  110  through air outlet  130  located on moisture removal plenum  118 . As moisture is removed from hot air within plenum  118 , it falls to the plenum bottom  142  and exits through condensate drain  128 .  
         [0038]     More particularly, plenum  118  comprises an enclosure defined by a front wall  132 , a rear wall  134 , side walls  136  and  138 , a top wall  140 , and a bottom wall  142  although it is understood that other plenum configurations are of course possible. Plenum  118  is of a size so as to completely surround cooled air outlets  144 . As best illustrated by  FIG. 13 , cooler  110  is of a configuration intended to be oriented and installed in a vertical manner with respect to a floor. As such, the series of cooled air outlets  144  of the heat exchanger  112 , as defined by the stacked plates and fins of the core, may be considered to linearly extend along a vertical axis A-A, substantially perpendicular to a floor  111 .  
         [0039]     A dry air outlet tube  148  having an inlet  148   a  and an outlet  148   b  connected to plenum outlet  130  extends along an axis B-B which is substantially parallel to and laterally offset from axis A-A along which the air outlets  144  of exchanger core  112  extend. It will be appreciated that this embodiment of the invention provides a vertically oriented heat exchanger with integral moisture separator that takes up very little horizontal space.  
         [0040]     A shield  146  may be positioned in plenum  118  to extend downwardly between air outlets  144  and the upper segment of air outlet tube  148 . Shield  146  is of a length which is suited to block the air from flowing out of core  112  directly into outlet tube  148 . As such, the air must travel beneath the bottom edge  146   a  of shield  146  to reach tube inlet end  148   a  (see  FIG. 13 ). Shield  146  further assists in removing moisture from the air by slowing down the velocity of the air as it travels to the outlet tube inlet end  148   a . This assists in causing the condensate to fall while at the same time not re-entraining condensate that has already been released and accumulated at the plenum bottom  142 .  
         [0041]     In operation, hot, compressed air enters the aftercooler  110  via inlet  126  where it travels through manifold  114   b  and is distributed through the core  112  for cooling. The cooled, moisture-laden air exits air outlets  144  into plenum  118 . As the cooled air enters plenum  118 , it releases moisture in the form of condensate which falls due to gravity to plenum bottom  142 . The plenum bottom  142  may be recessed with respect to exchanger core  112  to provide a sump for the collection of condensate should the drain be closed for any reason. Should condensate collect on plenum bottom  142 , the condensate will be spaced from the lower-most air outlets  144  which helps discourage condensate from becoming re-entrained into the plenum air flow.  
         [0042]     Thus, the cooled, compressed air is directed under shield  146  to reach air outlet tube  148 , releasing moisture in the form of condensate as it reaches tube  148 . Beveling inlet edge  150  functions to increase the air flow area of the air inlet which further assists in reducing the velocity of the air traveling from the core air outlets  144  to the air outlet tube  148 . It is furthermore preferred that the bevel faces away from the shield  146  to provide yet another angle about which the air must travel to reach the inlet since the more angles (i.e. walls) the air must flow around, the more opportunity there is for the condensate to fall from the air flow. Thus, cooled, condensed air exits the system through outlet  130 , while condensate which was removed from the air exits the system through condensate outlet  128 .  
         [0043]     While the invention has been described by reference to various specific embodiments, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiments, but will have full scope defined by the language of the following claims.