Heat Pipe with Nanostructured Wick

Abstract

A heat pipe with a nanostructured wick is disclosed, with the method of forming the nanostructured wick on a metal substrate. The wicking material is a pattern of metallic nanostructures in the form of bristles or nanowires attached to a substrate, where the bristles are substantially freestanding.

1 . A heat pipe with an interior surface enclosing a cavity comprised of at least one wicking material residing within said cavity, said wicking material comprised of a plurality nanowires. 
     
     
         2 . The heat pipe of  claim 1  where the cross sectional dimension of at least one of the plurality of nanowires are between approximately 10 nanometers and approximately 400 nanometers. 
     
     
         3 . The heat pipe of  claim 1  where the diameter of at least one of the plurality of nanowires are between approximately 50 nanometers and approximately 250 nanometers. 
     
     
         4 . The heat pipe of  claim 1  where the plurality nanowires are substantially spaced apart between approximately 20 nanometers center to center and approximately 600 nanometers center to center. 
     
     
         5 . The heat pipe of  claim 1  where the plurality nanowires are substantially spaced apart between approximately 75 nanometers center to center and approximately 500 nanometers center to center. 
     
     
         6 . The heat pipe of  claim 2  with the limitations of  claim 4 , where the diameter of the nanowire is at least equal to the center to center spacing. 
     
     
         7 . The heat pipe of  claim 3  with the limitations of  claim 5 , where the diameter of the nanowire is at least equal to the center to center spacing. 
     
     
         8 . The heat pipe of  claim 1  where the length of at least one of the nanowires is between approximately 100 nanometers and approximately 250 microns. 
     
     
         9 . The heat pipe of  claim 1  where the length of at least one of the nanowires is between approximately 50 microns and 150 microns. 
     
     
         10 . The heat pipe of  claim 1  where the length of the nanowires are between approximately 1 micron and approximately 250 microns, the spacing of the nanowires is between approximately 20 nanometers center to center and 600 nanometers center to center and the diameter of the nanowires is between approximately 10 nanometers and 400 nanometers, where the diameter of the nanowire is at least equal to the center to center spacing and the aspect ratio of the wire is no more than approximately 2500 to 1 and is at least 1 to 1. 
     
     
         11 . The heat pipe of  claim 10  where the length of the nanowires are between approximately 50 microns and approximately 150 microns. 
     
     
         12 . The heat pipe of  claim 10  where the cross section dimension of the heat pipe, measured substantially perpendicularly to the axis along which the vapor flows, is between approximately 500 microns and two millimeters. 
     
     
         13 . The heat pipe of  claims 1  and  10  where the nanowires are substantially free standing. 
     
     
         14 . A heat pipe comprised of at least one wicking material that is comprised of nanostructures, where the wicking material has a thermal resistance less than approximately 0.08° C.-cm2/W when the heat flux is between approximately 100 W/cm2 and approximately 200 W/cm2. 
     
     
         15 . A heat pipe comprised of at least one wick, where the wick is comprised of nanostructred material with anisotropic flow characteristics whereby the resistance to fluid flow along the longitudinal axis of the pipe is substantially higher than the fluid flow approximately normal to the interior surface of the heat pipe that the wick material is adjacent to, 
     
     
         16 . A heat pipe of  claim 1 ,  2 ,  3 ,  4 ,  5 ,  6 ,  7 ,  8 ,  9 ,  10 ,  11 ,  12 ,  13  or  14  where the nanowire wicking material occupies at least one selected region along the interior surface of the heat pipe, said region being an area that is less than the interior surface in area. 
     
     
         17 . The heat pipe of  claim 16  where the selected region is one of a groove, a cross pattern, a trianglular grid, a mesh. 
     
     
         18 . The heat pipe of  claim 16  where the selected regions are a substantially repeating pattern across the interior surface. 
     
     
         19 . A heat pipe of  claim 1  where the nanowire wicking material for the region that is substantially evaporating the heat transfer fluid has different nanowire dimensions than the wicking material in the region that is substantially condensing the heat transfer fluid. 
     
     
         20 . A heat pipe of  claim 19  where the wicking material in the condensing region is not a nanostructure wicking material. 
     
     
         21 . A method of forming a heat pipe body comprised of an interior surface enclosing an interior cavity, comprised of: growing nanowires on a substrate; attaching the substrate to a heat pipe body with the nanowires facing the interior cavity of the heat pipe. 
     
     
         22 . The method of  claim 21  comprising growing the nanowires through a template attached to the substrate, said template having at least one pore that substantially penetrates through the template to the surface of the substrate. 
     
     
         23 . Method of  claim 22  further comprising anodizing a metallic layer to create the template. 
     
     
         24 . The method of  claim 23  where the metallic layer is aluminum. 
     
     
         25 . The method of  claim 23  where the template is Aluminum Oxide. 
     
     
         26 . The method of  claim 23  where the anodized metallic layer is one of: Titania, Silica, Zinc Oxide, Zirconium Oxide, Lanthinum Oxide, Niobium Oxide, Tungsten Oxide, Tin Oxide, Indium Oxide, Indium Tin Oxide, Strontium Oxide, Vanadium Oxide, Molybdinum Oxide, Calcium/Titanium Oxide, blends of such materials. 
     
     
         27 . The Method of  claim 23  further comprising detecting a substantial spike in anodization current and shutting off the anodization current as a result of such detection. 
     
     
         28 . The method of  claim 27  where the shutting off occurs as a result of the anodization current spike being between approximately 2 and approximately 3 times its substantially prior steady state value. 
     
     
         29 . The method of  claim 21  further comprising characterizing the surface of the substrate where the nanowires have been grown by reflecting light energy off the surface and detecting at least one spectral characteristic of the reflected light. 
     
     
         30 . The method of  claim 29  where the spectral characteristic is detecting the amplitude of reflected light to incident light at approximately the wavelength of the two modes of plasmon resonance in the nanowires. 
     
     
         31 . The method of  claim 22  comprising growing nanowires within the at least one pore in the template by means of electroplating a metal. 
     
     
         32 . The method of  claim 31  where the electroplating current is in the range of approximately 200 milliamps to approximately 600 milliamps. 
     
     
         33 . The method of  claim 31  where the electroplating voltage is approximately 0.75 volts. 
     
     
         34 . The method of  claim 31  where the metal is copper. 
     
     
         35 . The method of  claim 31  where the metal is comprised of one of Cd, Fe, Au, Ag, Ni or Molybdinum. 
     
     
         36 . The method of  claim 31  further comprising etching the template. 
     
     
         37 . The method of  claim 36  where the etch solution is one of Phosphoric acid, NaOH, HCl, H2SO4, HF, Sodium Hydroxide. 
     
     
         38 . The method of  claim 22  where an Anodisk filter is the template. 
     
     
         39 . A heat pipe comprising at least one wicking material, where the at least one wicking material occupies a region on the surface of the interior of the cavity of the heat pipe, where the boiling surface ratio of the wicking material is between approximately 125 and approximately 3600. 
     
     
         40 . A heat pipe comprising at least one wicking material, where the at least one wicking material occupies a region on the surface of the interior of the cavity of the heat pipe, where the boiling surface ratio of the wicking material is greater than approximately 125 and less than approximately 1962. 
     
     
         41 . The heat pipe of  claim 39  where the boiling surface ratio divided by the thickness of the wicking material measured in microns is between approximately 18 and approximately 125. 
     
     
         42 . The heat pipe of  claim 39  where the boiling surface ratio divided by the thickness of the wicking material measured in microns is between approximately 1500 and 2500. 
     
     
         43 . The heat pipe of  claim 39 ,  40 ,  41  or  42  where the wicking material is nanostructured. 
     
     
         44 . The heat pipe of  claim 43  where the nanostructures are an array of nanowires. 
     
     
         45 . A method of forming a heat pipe body comprised of an interior surface enclosing an interior cavity, comprised of: growing nanowires on at least one region of the interior surface. 
     
     
         46 . The method of  claim 45  comprising growing the nanowires through a template attached to the interior surface, said template having at least one pore that substantially penetrates through the template to the surface of the interior surface. 
     
     
         47 . Method of  claim 46  further comprising anodizing a metallic layer to create the template. 
     
     
         48 . The method of  claim 47  where the metallic layer is aluminum. 
     
     
         49 . The method of  claim 47  where the template is Aluminum Oxide. 
     
     
         50 . The method of  claim 47  where the anodized metallic layer is one of: Titania, Silica, Zinc Oxide, Zirconium Oxide, Lanthinum Oxide, Niobium Oxide, Tungsten Oxide, Tin Oxide, Indium Oxide, Indium Tin Oxide, Strontium Oxide, Vanadium Oxide, Molybdinum Oxide, Calcium/Titanium Oxide, blends of such materials. 
     
     
         51 . The Method of  claim 47  further comprising detecting a substantial spike in anodization current and shutting off the anodization current as a result of such detection. 
     
     
         52 . The method of  claim 51  where the shutting off occurs as a result of the anodization current spike being between approximately 2 and approximately 3 times its substantially prior steady state value. 
     
     
         53 . The method of  claim 45  further comprising characterizing the surface of the substrate where the nanowires have been grown by reflecting light energy off the surface and detecting at least one spectral characteristic of the reflected light. 
     
     
         54 . The method of  claim 46  where the spectral characteristic is detecting the amplitude of reflected light to incident light at approximately the wavelength of the two modes of plasmon resonance in the nanowires. 
     
     
         55 . The method of  claim 46  comprising growing nanowires within the at least one pore in the template by means of electroplating a metal. 
     
     
         56 . The method of  claim 55  where the electroplating current is in the range of approximately 200 milliamps to approximately 600 milliamps. 
     
     
         57 . The method of  claim 55  where the electroplating voltage is approximately 0.75 volts. 
     
     
         58 . The method of  claim 55  where the metal is copper. 
     
     
         59 . The method of  claim 55  where the metal is one of Cd, Fe, Au, Ag, Ni, Mb. 
     
     
         60 . The method of  claim 55  further comprising etching the template. 
     
     
         61 . The method of  claim 60  where the etch solution is one of Phosphoric acid, NaOH, HCl, H 2 SO 4 , HF, Sodium Hydroxide. 
     
     
         62 . The method of  claim 55  where an Anodisk filter is the template. 
     
     
         63 . A method of making a heat pipe comprised of a body and an interior cavity, comprising:
 Cladding a substrate comprised of a first metal with a second metal;   Oxidizing the second metal by means of anodization whereby the oxide forms pores;   Electroplating a third metal within the pores to form nanowires;   Etching the oxide of the second metal, whereby the nanowires become substantially free-standing;   Attaching the substrate to the heat pipe body such that the nanowires are inside the interior cavity of the heat pipe.   
     
     
         64 . A method of making a heat pipe comprised of a metallic body comprised of a cavity with an interior surface comprising:
 Cladding a region on the interior surface with a second metal;   Oxidizing the second metal by means of anodization whereby the oxide forms pores;   Electroplating metal within the pores to form nanowires;   Etching the metallic oxide, whereby the nanowires become substantially free-standing.   
     
     
         65 . A heat pipe comprising at least one wicking material, where the at least one wicking material is nanostructured and occupies a region on the surface of the interior of the cavity of the heat pipe, where the boiling surface ratio of the wicking material is between approximately 125 and approximately 3600. 
     
     
         66 . A heat pipe comprising at least one wicking material, where the at least one wicking material is nanostructured and occupies a region on the surface of the interior of the cavity of the heat pipe, where the boiling surface ratio of the wicking material is greater than approximately 125 and less than approximately 1962. 
     
     
         67 . The heat pipe of  claim 66  where the boiling surface ratio divided by the thickness of the wicking material measured in microns is between approximately 18 and approximately 125. 
     
     
         68 . The heat pipe of  claim 65 ,  66  or  67  where the nanostructured wicking material is comprised of a plurality of nanowires, where the nanowires are between approximately 1 micron and approximately 250 microns in length. 
     
     
         69 . The heat pipe of  claim 68  where the cross section dimension of the heat pipe, measured substantially perpendicularly to the axis along which the vapor flows, is between approximately 500 microns and two millimeters. 
     
     
         70 . The heat pipe of  claim 68  where the nanowires are free standing and substantially regularly spaced. 
     
     
         71 . A method of cooling electronic devices using a nanostructured heat pipe comprised of conducting heat generated by said device into a wicking material comprised of a nanowire array substantially surrounded by a fluid and evaporating said fluid. 
     
     
         72 . The method of  claim 71  where the nanowire array is comprised of a plurality of nanowires, where the length of the nanowires are between approximately 1 micron and approximately 250 microns, the spacing of the nanowires is between approximately 20 nanometers center to center and 600 nanometers center to center and the diameter of the nanowires is between approximately 10 nanometers and 400 nanometers, where the diameter of the nanowire is at least equal to the center to center spacing and the aspect ratio of the wire is no more than approximately 2500 to 1 and greater than 1 to 1. 
     
     
         73 . The method of  claim 72  where the length of the nanowires are between approximately 50 microns and approximately 100 microns. 
     
     
         74 . The method of  claim 72  where the cross section dimension of the heat pipe, measured substantially perpendicularly to the axis along which the vapor flows, is between approximately 500 microns and two millimeters. 
     
     
         75 . The method of  claim 71  where the nanowires are substantially free standing. 
     
     
         76 . The heat pipe of any of  claims 1  through  claim 15  where the spacing of the nanowires is graded so that it is relatively sparse in the condenser region and more tightly packed in the evaporator region. 
     
     
         77 . The method of any of  claims 21  through  26  or  45  through  49  where the nanowire growth occurs on selected regions. 
     
     
         78 . The method of any of  claims 21  through  26  or  45  through  49  further comprising using microlithography techniques to change the surface profile of the metal to be anodized prior to anodization. 
     
     
         79 . The heat pipe of any of  claims 1  through  claim 15  where the nanowires are substantially regularly spaced. 
     
     
         80 . The heat pipe of any of  claims 1  through  claim 15  where the nanowires are substantially oriented substantially normal to the plane of the substrate. 
     
     
         81 . The heat pipe of  claim 44  where the nanowire array is comprised of a plurality of nanowires, where the length of the nanowires are between approximately 1 micron and approximately 250 microns, the spacing of the nanowires is between approximately 20 nanometers center to center and 600 nanometers center to center and the diameter of the nanowires is between approximately 10 nanometers and 400 nanometers, where the diameter of the nanowire is at least equal to the center to center spacing and the aspect ratio of the wire is no more than approximately 2500 to 1 and greater than 1 to 1.