Carbon nanotube and graphene aerogel heat pipe wick

Abstract

In one example, a heat pipe. The heat pipe includes a sealed, hollow, thermally conductive casing. A wick is disposed on interior walls of the casing. The wick includes an aerogel of carbon nanotubes and graphene. A working fluid is disposed in a cavity defined by the casing and the wick.

What is claimed is: 
     
         1 . A heat pipe, comprising:
 a sealed hollow thermally conductive casing;   a wick disposed on interior walls of the casing, the wick comprising an aerogel of carbon nanotubes and graphene; and   a working fluid disposed in a cavity defined by the casing and the wick.   
     
     
         2 . The heat pipe of  claim 1 , wherein individual carbon nanotubes in the aerogel have a length of 1 to 3 micrometers and a widest diameter of 8 to 12 nanometers. 
     
     
         3 . The heat pipe of  claim 1 , wherein individual stacks of the graphene in the aerogel have a length and width of 0.1 to 5 micrometers, a thickness of 5 to 50 nanometers, and an aspect ratio between 100 and 4500. 
     
     
         4 . The heat pipe of  claim 1 , wherein the aerogel comprises 0.1% to 30% graphene by weight. 
     
     
         5 . The heat pipe of  claim 1 , wherein the aerogel has a density between 0.03 and 0.5 grams per cubic centimeter. 
     
     
         6 . The heat pipe of  claim 1 , wherein the aerogel has a porosity between 5% and 90%. 
     
     
         7 . The heat pipe of  claim 1 , wherein pores of the aerogel have a diameter between 3 and 50 nanometers. 
     
     
         8 . The heat pipe of  claim 1 , wherein the aerogel has a surface area between 200 and 850 square meters per gram. 
     
     
         9 . The heat pipe of  claim 1 , wherein the casing is tubular, and wherein the wick has a fluted tubular cross-sectional profile. 
     
     
         10 . A method of conducting heat with a heat pipe, comprising:
 absorbing heat from a heat source adjacent a hot end of the heat pipe;   evaporating a working fluid of the heat pipe in a first portion, adjacent the hot end, of a wick coating an interior of the heat pipe, the wick comprising an aerogel of carbon nanotubes and graphene;   condensing the evaporated working fluid in the wick at a second portion, adjacent a cold end of the heat pipe; and   migrating the condensed working fluid through the wick from the cold end to the hot end.   
     
     
         11 . The method of  claim 10 , wherein the aerogel has a thermal conductivity greater than 2,500 watts per meter degree Kelvin at room temperature. 
     
     
         12 . The method of  claim 10 , wherein the aerogel has a thermal conductivity of about 3,000 watts per meter-degree Kelvin at room temperature. 
     
     
         13 . The method of  claim 10 , wherein the percentage by weight of the graphene in the aerogel determines, at least in part, the thermal conductivity of the wick and the heat transfer performance of the heat pipe. 
     
     
         14 . A method of making a heat pipe, comprising:
 applying a carbon nanotube and graphene aerogel coating to interior walls of a hollow thermally conductive casing to define a cavity;   sintering the applied coating to solidify the carbon nanotube and graphene aerogel coating to form an absorbent wick of the heat pipe on the interior walls; and   filling the cavity of the heat pipe with a working fluid.   
     
     
         15 . The method of  claim 14 ,
 wherein the applying includes spraying the aerogel in sol-gel form into the casing through a nozzle arrangement corresponding to a cross-sectional shape of the wick,   and wherein the filling includes sealing the casing to retain the working fluid in the heat pipe.