Patent Publication Number: US-2017356696-A1

Title: Complex pin fin heat exchanger

Description:
BACKGROUND OF THE INVENTION 
     This application relates to a heat exchanger having complex shaped pins. 
     Heat exchangers are known and utilized in any number of applications. One type of heat exchanger is a pin fin heat exchanger. In such a heat exchanger, a first fluid flows through a first chamber and a second fluid flows through a second chamber. A plate separates the two chambers and the fluids exchange heat through the plate. 
     To increase the heat transfer efficiency, it is known to have pins extending between adjacent plates. Historically, the plates and fins have had a constant cross-sectional thickness. 
     Additive manufacturing techniques have been developed. In an additive manufacturing system, a tool lays down material in layers and forms components. While it has been proposed to form heat exchangers from additive manufacturing techniques, a pin fin heat exchanger has not been formed by additive manufacturing techniques. 
     SUMMARY OF THE INVENTION 
     A heat exchanger has a plurality of outer walls and at least one inner wall. A first fluid port communicates a first fluid into a chamber on one side of the at least one inner wall and a second port communicates a second fluid into a second chamber on an opposed side of the at least one inner wall. A plurality of pins extends from the inner wall in at least one of the chambers. The plurality of pins has a generally frusto-conical outer surface. 
     A method is also disclosed and claimed. 
     These and other features may be best understood from the following drawings and specification. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically shows a heat exchanger. 
         FIG. 2  is a cross-sectional view through the  FIG. 1  heat exchanger. 
         FIG. 3A  shows a first pin embodiment. 
         FIG. 3B  shows an alternative embodiment. 
         FIG. 3C  shows an alternative embodiment. 
         FIG. 3D  shows an alternative embodiment. 
         FIG. 3E  shows an alternative embodiment. 
         FIG. 3F  shows yet another alternative embodiment. 
         FIG. 4  shows a manufacturing technique. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a heat exchanger  20  having a first port  22 , which may be an inlet port, and communicating fluid to an outlet port  24 . A second fluid enters through an inlet port  26  and exits through an outlet port  28 . 
     While a particular arrangement is disclosed, the parallel flow of the two fluids as illustrated can be replaced with a cross-flow application. In such an application, the port  28  could be an inlet and port  26  an outlet. For that matter, a number of other inlet/outlet port arrangements and configurations could be utilized. 
       FIG. 2  is a cross-sectional view through the heat exchanger  20 . As can be seen, the port  22  provides fluid to chambers  23  and the second port  28  provides fluid to chambers  29 . Outer walls  30  are formed along with intermediate or inner walls  32 . As can be appreciated, the inner walls  32  separate chambers  23  and  29 . As known, heat is exchanged between the fluids in the chambers through the walls  32 . 
     As shown in this figure, ports  34  communicate from the port  22  into the chambers  23 . Similarly, ports  36  communicate with chambers  29  to the ports  28 . 
     Pins  42  extend between the walls  30  and  32 . Pins also extend between walls  32 . 
     As can be appreciated in this figure, the pins  42  have enlarged surfaces adjacent the walls  30  and  32  and a thinner portion in the center. 
       FIG. 3A  shows the pin embodiment  42 . The outer portions  44 , which are actually in contact with the walls  30  and  32 , are larger and extend in a frusto-conical direction to a smaller central portion  46 . The outer surfaces  48  in this embodiment are straight, or along a constant angle. Thus, the shape is actually frusto-conical. 
       FIG. 3B  shows a generally frusto-conical pin embodiment  50 . Here again, the outer portions  52  are larger than the central portion  56 . However, the term “generally conical” can be seen to be a concave curving surface  56 . 
       FIG. 3C  shows another pin embodiment  60  having outer portions  62  and a thinner central portion  64 . The generally frusto-conical section  68  is a convex curve. 
       FIG. 3D  shows an embodiment  70  wherein the outer portions  74  are smaller than the central portion  72 . Here again, the outer surface  76  is generally frusto-conical on both sides of the portion  72 . 
     For purposes of this application, the term “generally frusto-conical” means that the size either increases or decreases from one end toward the center and then moves back to either a larger or smaller size as shown across these embodiments. 
       FIG. 3E  shows yet another embodiment  80  wherein the frusto-conical surface  81  is provided with a plurality of spikes  82 . 
       FIG. 3F  shows an embodiment  90  where the generally frusto-conical surface  92  is formed with a spiral rib  94 . The discrete surfaces are spikes. 
     It should be appreciated that any number of other shapes may be provided on the outer surface of the pins. Stated generally, there are discrete surfaces extending outwardly of the generally frusto-conical shapes to increase the heat transfer effect. 
     The pin embodiments, as disclosed above, would be difficult to manufacture using standard manufacturing techniques.  FIG. 4  shows a manufacturing technique for forming the heat exchanger, as disclosed. Here, an intermediate heat exchanger  96  is being formed. There are plates  97  and pins  98 . An additive manufacturing tool  99  is shown laying down material  100 . As known, material is deposited in layers and very complex shapes can be achieved. 
     Any number of additive manufacturing techniques can be utilized to form a heat exchanger as disclosed. In one embodiment, direct metal selective laser melting may be used. 
     This disclosure could be summarized as a heat exchanger  20  has a plurality of outer walls and at least one inner wall (walls  30  and  32 ), a first fluid port communicating a first fluid into a chamber  23  on one side of at least one inner wall and a second port communicating a second fluid into a second chamber  29  on an opposed side of the at least one inner wall. A plurality of pins extend from the at least one inner wall in at least one of chambers  23 / 29 , the plurality of pins have a generally frusto-conical shape. 
     A method of forming a heat exchanger  20  includes laying down layers of material  100  with an additive manufacturing process and forming a plurality of outer walls and at least one inner wall. The method also includes forming a first fluid port for communicating a first fluid into a chamber formed on one side of at least one inner wall and forming a second port communicating a second fluid into a second chamber formed on an opposed side of the at least one inner wall. The method further includes the step of forming a plurality of pins extending from at least one inner wall in at least one of the chambers, the plurality of pins are formed to have a generally frusto-conical shape. 
     Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.