Heat exchanger with multilayer cladded tubes

Abstract

Heat exchangers, particularly brazed heat exchangers used in motor vehicle applications, are presented. The tubes of the heat exchangers are coated with a multi-layered clad of preferably at least four layers of material of metallic alloy base.

1 . A heat exchanger that will be brazed as part of its final assembly, having: 
 a first end tank;    a second end tank opposite the first end tank;    a at least one tube an internal or fluid side surface and external or airside surface in communication with the first and the second end tanks;    a braze alloy clad consisting of at least four layers, applied to the internal surface of the tube;    wherein the at least four layer clad comprises metals or metallic alloys.    
   
   
       2 . A heat exchanger according to  claim 1  wherein each of the four layers comprises a metallic alloy.  
   
   
       3 . A heat exchanger according to  claim 2  wherein the metallic alloys are selected from the group consisting of aluminum, copper, or copper-brass alloys.  
   
   
       4 . A heat exchanger according to  claim 2 , wherein at least one layer comprises Si, Fe, Cu, Mn and Zn.  
   
   
       5 . A heat exchanger according to  claim 4 , wherein the at least one layer is directly applied to the internal surface of the tube.  
   
   
       6 . A heat exchanger according to  claim 4 , wherein at least one layer comprises Si, Fe, Mn, Zn and Zr, and the at least one layer is applied directly to the layer directly applied to the internal surface of the tube.  
   
   
       7 . A heat exchanger according to  claim 4 , wherein the at least one layer is the core alloy material layer.  
   
   
       8 . A heat exchanger according to  claim 7 , wherein the Si is found in the at least one layer at about 0.6 wt % of the layer, the Cu is found in the range of about 0.05 to 0.2 wt % of the layer, the Mn is found in the range of about 1.0 to 1.5 wt % of the layer, the Fe is found at about 0.7 wt % of the layer and the Zn is found at about 0.1 wt % of the layer.  
   
   
       9 . A heat exchanger according to  claim 2 , wherein the heat exchanger is a radiator or a charge air cooler.  
   
   
       10 . A heat exchanger according to  claim 2 , wherein the heat exchanger tube has one or more beads that are in contact or close contact in the final assembly.  
   
   
       11 . A heat exchanger according to  claim 10 , wherein the beads in contact with each other create at least two flow paths, allowing a fluid circulation through the tube.  
   
   
       12 . A heat exchanger according to  claim 11 , wherein at least one of the flow paths includes dimples on the tube at the area of the path to enhance heat exchange.  
   
   
       13 . A heat exchanger according to  claim 9 , wherein none of the layers comprises aluminum alloy.  
   
   
       14 . A heat exchanger according to  claim 10 , wherein the beads are positively connected to each other via a metallurgical bond.  
   
   
       15 . A heat exchanger according to  claim 13 , wherein the heat exchanger is a radiator.  
   
   
       16 . A method for making a multiple layer cladded heat exchanger comprising the steps of: 
 a) obtaining tubes that include a metal or metallic alloy comprising four layer clad material;    b) arranging the tubes in alternating rows with secondary heat exchange fin surfaces to form a matrix;    c) compressing the matrix;    d) assembling headers to the matrix; and    e) brazing the assembled header and matrix such that metallurgical bonds form throughout the matrix.