Heat pipe with a secondary wick for supplying subcooled liquid to high heat flux areas

Abstract

A heat pipe has a sealed envelope. A primary wick extends along an inside surface of the envelope. A working fluid is contained within the envelope. The fluid is capable of undergoing a liquid/vapor phase change. An evaporator section is defined within the envelope for vaporizing the fluid. The evaporator section has at least one high heat flux area that is capable of being thermally coupled to an external heat source to be cooled by the heat pipe. A secondary wick is formed of mesh screens or sintered metal powders. The secondary wick is connected to the primary wick in the high heat flux area and connected to the primary wick at a location approximately opposite the high heat flux area, for transporting subcooled liquid to the high heat flux area. A condenser section is defined within the envelope for condensing the vaporized fluid.

What is claimed is:  
     
         1 . A heat pipe, comprising: 
 a sealed envelope;    a primary wick extending along an inside surface of the envelope    a working fluid contained within the envelope; the fluid being capable of undergoing a liquid/vapor phase change;    an evaporator section defined within the envelope for vaporizing the fluid, the evaporator section having at least one high heat flux area that is capable of being thermally coupled to an external heat source to be cooled by the heat pipe;    a secondary wick formed of mesh screens or sintered metal or non-metal particles, the secondary wick being connected to the primary wick in the high heat flux area and also connected to the primary wick at a location approximately opposite to the high heat flux area, for transporting subcooled liquid to the high heat flux area; and    a condenser section defined within the envelope for condensing the vaporized fluid, whereby a liquid is formed.    
     
     
         2 . The heat pipe of  claim 1 , wherein the secondary wick has a cylindrical core and at least two radial web portions connecting the core to the primary wick, and the primary wick is attached to the inner surface of the envelope.  
     
     
         3 . The heat pipe of  claim 2 , wherein the secondary wick extends longitudinally from the evaporator section to the condenser section.  
     
     
         4 . The heat pipe of  claim 2 , wherein the cylindrical core is porous.  
     
     
         5 . The heat pipe of  claim 1 , wherein the secondary wick is located substantially at a center of the high heat flux area.  
     
     
         6 . The heat pipe of  claim 5 , wherein the secondary wick has a cylindrical shape.  
     
     
         7 . The heat pipe of  claim 5 , wherein the secondary wick has a flat web shape.  
     
     
         8 . The heat pipe of  claim 1 , wherein the primary wick is sufficiently thin to promote heat transfer in the high heat flux area.  
     
     
         9 . The heat pipe of  claim 1 , wherein the secondary wick is formed of one of the group consisting of powders of copper, aluminum, steel nickel, silicon, silicon carbide and silicon nitride.  
     
     
         10 . A heat pipe, comprising: 
 a sealed envelope;    a primary wick extending along an inside surface of the envelope    a working fluid contained within the envelope; the fluid being capable of undergoing a liquid/vapor phase change;    an evaporator section defined within the envelope for vaporizing the fluid, the evaporator section having at least one high heat flux area that is capable of being thermally coupled to an external heat source to be cooled by the heat pipe;    a secondary wick formed of mesh screens or sintered metal or non-metal particles, the secondary wick having a cylindrical core and at least two radial web portions connecting the core to the primary wick, the secondary wick being connected to the primary wick in the high heat flux area, for transporting subcooled liquid to the high heat flux area; and    a condenser section defined within the envelope for condensing the vaporized fluid, whereby a liquid is formed.    
     
     
         11 . The heat pipe of  claim 10 , wherein the secondary wick extends longitudinally from the evaporator section to the condenser section.  
     
     
         12 . The heat pipe of  claim 10 , wherein the cylindrical core is porous.  
     
     
         13 . The heat pipe of  claim 10 , wherein the primary wick is sufficiently thin to promote heat transfer in the high heat flux area.  
     
     
         14 . The heat pipe of  claim 10 , wherein the secondary wick is formed of one of the group consisting of powders of copper, aluminum, steel nickel, silicon, silicon carbide and silicone nitride.  
     
     
         15 . In a heat pipe having a sealed envelope, a primary wick extending along an inside surface of the envelope, a working fluid contained within the envelope, the fluid being capable of undergoing a liquid/vapor phase change, an evaporator section defined within the envelope for vaporizing the fluid, and a condenser section defined within the envelope for condensing the vaporized fluid, a method for transferring heat, comprising the steps of: 
 (a) thermally coupling an external heat source to a high heat flux area of a portion of the heat pipe containing the evaporator section; and    (b) transporting subcooled liquid to the high heat flux area via a secondary wick formed of mesh screens or sintered metal, the secondary wick being connected to the primary wick in the high heat flux area and also connected to the primary wick at a location approximately opposite to the high heat flux area.    
     
     
         16 . The method of  claim 15 , wherein step (b) includes transporting subcooled liquid in a direction perpendicular to a longitudinal axis of the heat pipe, to the high heat flux area.  
     
     
         17 . The method of  claim 15 , wherein step (b) includes conducting subcooled liquid to the high heat flux area from a porpous central cylindrical core portion of the secondary wick extending from the condenser section to the evaporator section, via a web portion of the secondary wick connecting the core to primary wick.  
     
     
         18 . The method of  claim 15 , further comprising boiling liquid inside the primary wick within the high heat flux area.