Method for making brazed heat exchanger and apparatus

Abstract

A heat exchanger has a boiling passage and a cooling passage defined by opposite sides of metal walls. Layers of brazing material between the metal walls and a spacer member bond components of the heat exchanger together. An enhanced boiling layer (EBL) having metal particles bonded to each other and to a boiling side of the metal wall provides nucleate boiling pores to improve heat transfer. The EBL has a melting temperature that is higher than the melting temperature of the brazing material.

1 : A heat exchanger comprising: 
 a plurality of metal walls, each metal wall comprising two sides, a boiling side with an enhanced boiling layer comprising thermally conductive particles integrally bonded together and metallurgically bonded to the boiling side and a cooling side, said boiling side of said plurality of metal walls defining a boiling passage and said cooling side of said plurality of metal walls defining a cooling passage and each of said plurality of metal walls further including a bonding surface;    a spacer member for spacing metal walls from each other;    a layer of metal between said bonding surfaces of said metal walls and said spacer member in said heat exchanger, said layer of metal having a melting temperature that is less than a melting temperature of said enhanced boiling layer;    a boiling inlet for delivering liquid to said boiling passage;    a cooling inlet for delivering fluid to said cooling passage;    a boiling outlet for recovering vapor from said boiling passage; and    a cooling outlet for recovering fluid from said cooling passage.    
     
     
         2 : The heat exchanger of  claim 1  wherein the metal walls predominantly comprise aluminum.  
     
     
         3 : The heat exchanger of  claim 1  wherein the thermally conductive particles predominantly comprise aluminum.  
     
     
         4 : The heat exchanger of  claim 3  wherein said enhanced boiling layer includes between about 0.5 and about 1.5 wt-% silicon.  
     
     
         5 : The heat exchanger of  claim 3  wherein said thermally conductive particles of said enhanced boiling layer comprises a highly proportioned aluminum alloy powder mixed with a eutectic alloy of aluminum and silicon.  
     
     
         6 : The heat exchanger of  claim 5  wherein the highly proportioned aluminum alloy comprises 92 wt-% of the enhanced boiling layer and the eutectic alloy comprises 8 wt-% of the enhanced boiling layer.  
     
     
         7 : The heat exchanger of  claim 5  wherein said layer of metal comprises said eutectic alloy.  
     
     
         8 : The heat exchanger of  claim 5  wherein the eutectic alloy is 12 wt-% silicon and 88 wt-% aluminum.  
     
     
         9 : A heat exchanger comprising: 
 a plurality of metal walls, each metal wall comprising two sides, a boiling side with an enhanced boiling layer comprising thermally conductive particles integrally bonded together and a cooling side, said thermally conductive particles comprising an alloy of a first metal and a second metal, said second metal alloying with said first metal to provide an alloy with a melting temperature that is lower than the melting temperature of said first metal, said boiling sides of said plurality of metal walls defining boiling passages and said cooling sides of said plurality of metal walls defining cooling passages and each of said plurality of metal walls further including a bonding surface;    a plurality of spacer bars each between pairs of said metal walls, each of said spacer bars having a bonding surface;    a layer of metal between each of said bonding surfaces of said metal walls and a bonding surface of an adjacent one of said plurality of spacer bars, said layer of metal comprising an alloy including said first metal and a melting temperature of said layer of metal is less than a melting temperature of said enhanced boiling layer;    a boiling inlet for delivering liquid to said boiling passage;    a cooling inlet for delivering fluid to said cooling passages;    a boiling outlet for recovering vapor from said boiling passages; and    a cooling outlet for recovering fluid from said cooling passages.    
     
     
         10 : The heat exchanger of  claim 9  wherein said layer of metal comprises an additional metal with a greater concentration of said additional metal than a concentration of said second metal in said enhanced boiling layer.  
     
     
         11 : The heat exchanger of  claim 9  wherein the metal walls and the first metal predominantly comprise aluminum.  
     
     
         12 : The heat exchanger of  claim 9  wherein the second metal and the additional metal are silicon.  
     
     
         13 : The heat exchanger of  claim 9  wherein the enhanced boiling layer includes between 0.5 and 1.5 wt-% silicon.  
     
     
         14 : The heat exchanger of  claim 9  wherein the thermally conductive particles of said enhanced boiling layer comprises a highly proportioned aluminum alloy powder mixed with a eutectic alloy of aluminum and silicon  
     
     
         15 : The heat exchanger of  claim 14  wherein the highly proportioned aluminum alloy comprises 92 wt-% of the enhanced boiling layer and the eutectic alloy comprises 8 wt-% of the enhanced boiling layer.  
     
     
         16 : The heat exchanger of  claim 15  wherein said eutectic alloy is 12 wt-% silicon and 88 wt-% aluminum.  
     
     
         17 - 18  (canceled)  
     
     
         19 : A method of constructing a heat exchanger comprising: 
 providing a plurality of metal walls having a boiling side, a cooling side and at least one bonding surface;    applying thermally conductive particles to a boiling side of a plurality of metal components;    heating said metal walls with applied thermally conductive particles to a first temperature to integrally bond said thermally conductive particles together and to metallurgically bond thermally conductive particles to said boiling side to form an enhanced boiling surface,    assembling said plurality of metal walls with a spacing member so that said boiling sides of said plurality of metal walls define a boiling passage and said cooling sides of said plurality of metal walls define a cooling passage and providing layers of metal between said bonding surfaces of said metal walls and adjacent surfaces of the spacing member; and    heating the assembly to a second temperature that is less than said first temperature to bond the layers of metal to at least one of the adjacent surfaces of the spacing member and the bonding surfaces of the metal walls.    
     
     
         20 : The method of  claim 19  further comprising: 
 affixing a boiling header to the heat exchanger to be in fluid communication with an inlet to said boiling passages;  
 affixing a cooling header to said heat exchanger to be in fluid communication with an inlet to said cooling passages;  
 affixing a boiling manifold to said heat exchanger to be in fluid communication with an outlet of said boiling passages; and  
 affixing a cooling manifold to said heat exchanger to be in fluid communication with an outlet of said cooling passages.  
 
     
     
         21 : A heat exchanger comprising: 
 a plurality of metal walls, each metal wall comprising two sides, a cooling side and a boiling side with an enhanced boiling layer comprising thermally conductive particles, said thermally conductive particles including a highly proportioned aluminum alloy powder mixed with a eutectic alloy of aluminum and silicon, said thermally conductive particles being integrally bonded together and metallurgically bonded to the boiling side, said boiling side of said plurality of metal walls defining a boiling passage and said cooling side of said plurality of metal walls defining a cooling passage and each of said plurality of metal walls further including a bonding surface;    a spacer member for spacing metal walls from each other;    a layer of metal between said bonding surfaces of said metal walls and said spacer member in said heat exchanger, said layer of metal having a melting temperature that is less than a melting temperature of said enhanced boiling layer;    a boiling inlet for delivering liquid to said boiling passage;    a cooling inlet for delivering fluid to said cooling passage;    a boiling outlet for recovering vapor from said boiling passage; and    a cooling outlet for recovering fluid from said cooling passage.