Brazed wick for a heat transfer device and method of making same

Abstract

A capillary structure for a heat transfer device, such as a heat pipe is provided having a plurality of particles joined together by a brazing compound such that fillets of the brazing compound are formed between adjacent ones of the plurality of particles. In this way, a network of capillary passageways are formed between the particles to aid in the transfer of working fluid by capillary action, while the plurality of fillets provide enhanced thermal transfer properties between the plurality of particles so as to greatly improve over all heat transfer efficiency of the device. A method of making the capillary structure according to the invention is also presented.

1 . A capillary structure for a heat transfer device comprising: 
 a plurality of particles joined together by a brazing compound such that fillets of said brazing compound are formed between adjacent ones of said plurality of particles so as to form a network of capillary passageways between said particles.    
     
     
         2 . A capillary structure according to  claim 1  wherein said plurality of particles comprise a first melting temperature and said brazing compound comprises a second melting temperature that is lower than said first melting temperature.  
     
     
         3 . (canceled)  
     
     
         4 . A capillary structure according to  claim 1  wherein said fillets are formed by capillary action of said braze compound when in a molten state.  
     
     
         5 . A capillary structure according to  claim 1  wherein said particles are selected from the group consisting of carbon, tungsten, copper, aluminum, magnesium, nickel, gold, silver, aluminum oxide, and beryllium oxide.  
     
     
         6 . A capillary structure according to  claim 1  wherein said particles comprise a shape selected from the group consisting of spherical, oblate spheroid, prolate spheroid, ellipsoid, polygonal, and filament.  
     
     
         7 . A capillary structure according to  claim 1  wherein said particles comprise at least one of copper spheres and oblate copper spheroids having a melting point of about one thousand eighty-three ° C.  
     
     
         8 - 11 . (canceled)  
     
     
         12 . A capillary structure according to  claim 2  wherein metal particles are a constituent portion of said braze compound prior to reaching said second melting temperature and comprise a smaller size than said plurality of particles.  
     
     
         13 . A capillary structure according to  claim 1  wherein said braze compound is selected from the group consisting of nickel-based Nicrobrazes, silver/copper brazes, tin/silver, lead/tin, and polymers.  
     
     
         14 . A capillary structure according to  claim 1  wherein said plurality of particles comprise aluminum and magnesium and said brazing compound comprises an aluminum/magnesium intermetallic alloy.  
     
     
         15 . A heat pipe comprising: 
 a hermetically sealed and partially evacuated enclosure, said enclosure comprising internal surfaces;    a wick disposed on at least one of said internal surfaces and comprising a plurality of particles joined together by a brazing compound such that fillets of said brazing compound are formed between adjacent ones of said plurality of particles so as to form a network of capillary passageways between said particles; and    a two-phase fluid at least partially disposed within a portion of said wick.    
     
     
         16 . A heat pipe according to  claim 15  wherein said plurality of particles comprise a first melting temperature and said brazing compound comprises a second melting temperature that is lower than said first melting temperature.  
     
     
         17 . (canceled)  
     
     
         18 . A heat pipe according to  claim 15  wherein said fillets are formed by capillary action of said braze compound when in a molten state.  
     
     
         19 . A heat pipe according to  claim 15  wherein said particles are selected from the group consisting of carbon, tungsten, copper, aluminum, magnesium, nickel, gold, silver, aluminum oxide, and beryllium oxide.  
     
     
         20 . A heat pipe according to  claim 15  wherein said particles comprise a shape selected from the group consisting of spherical, oblate spheroid, prolate spheroid, polygonal, and filament.  
     
     
         21 . A heat pipe according to  claim 14  wherein said particles comprise at least one of copper spheres and oblate copper spheroids having a melting point of about 1083° C.  
     
     
         22 . (canceled)  
     
     
         23 . A heat pipe according to  claim 16  wherein said brazing compound is present in the range from about two percent to about ten percent.  
     
     
         24 . A heat pipe according to  claim 16  wherein said particles comprise copper powder comprising particles size in a range from about twenty mesh to about two-hundred mesh.  
     
     
         25 . A heat pipe according to  claim 16  wherein said braze compound comprises particles that comprise about minus three hundred and twenty-five mesh prior to melting.  
     
     
         26 . A heat pipe according to  claim 16  wherein particles are a constituent portion of said braze compound prior to reaching said second melting temperature and comprise a smaller size than said plurality of particles.  
     
     
         27 . A heat pipe according to  claim 16  wherein said braze compound is selected from the group consisting of nickel-based Nicrobrazes, silver/copper brazes, tin/silver, lead/tin, and polymers.  
     
     
         28 . A heat pipe according to  claim 16  wherein said plurality of particles comprise aluminum and magnesium and said brazing compound comprises an aluminum/magnesium intermetallic alloy.  
     
     
         29 - 43 . (canceled)  
     
     
         44 . A heat pipe comprising: 
 a sealed and partially evacuated enclosure having an internal surface;    a grooved brazed wick disposed upon said internal surface comprising a plurality of individual particles and a brazing compound such that fillets of said brazing compound are formed between adjacent ones of said plurality of particles, and further including at least two lands that are in fluid communication with one another wherein said particles are thermally engaged with one another by a plurality of said fillets; and    a working fluid disposed within said enclosure.    
     
     
         45 - 58 . (canceled)