Heat pipe having a wick with a hybrid profile

Abstract

A heat pipe system for conducting thermal energy. The heat pipe system includes a sealed tube having along its length a reservoir region, an evaporator region, and a condenser region, the tube having a first end and a second end and an inside wall. The system also includes a wick disposed adjacent the inside wall of the tube, the wick including a first portion at the first end of the tube and a second portion adjacent the first portion, wherein the first portion of the wick is thicker than the second portion of the wick, and wherein the second portion of the wick does not extend to the second end of the tube. The system also includes a working fluid contained within the tube.

What is claimed is: 
     
         1 . A heat pipe system for conducting thermal energy from a heat source, the heat pipe system comprising:
 a heat pipe having an interior volume;   a wick region disposed in the interior volume and a condenser region in fluid communication with the wick region;   a first wick portion disposed in the wick region and a second wick portion disposed in the wick region adjacent the first wick portion, the first wick portion having a first thickness and the second wick portion having a second thickness that is greater than the first thickness, wherein the condenser region is free from a wick; and   a working fluid,   wherein the first wick portion and the second wick portion are configured such that (i) when heat is generated by the heat source, working fluid is drawn from the second wick portion to the first wick portion, and vapor formed from evaporation of the working fluid flows to the condenser region through a space formed at least in part by the first wick portion, and (ii) when no heat is applied to the first wick portion, the working fluid is absorbed by at least one of the first wick portion and the second wick portion.   
     
     
         2 . The heat pipe system of  claim 1 , wherein the second wick portion is disposed adjacent an interior surface of the heat pipe. 
     
     
         3 . The heat pipe system of  claim 1 , wherein the first wick portion is disposed adjacent an interior surface of the heat pipe. 
     
     
         4 . The heat pipe system of  claim 1 , wherein the second wick portion is annular. 
     
     
         5 . The heat pipe system of  claim 1 , wherein the first wick portion is annular. 
     
     
         6 . The heat pipe of  claim 1 , wherein the first wick portion and the second wick portion are each disposed adjacent an interior surface of the heat pipe. 
     
     
         7 . The heat pipe system of  claim 1 , wherein the first wick portion and the second wick portion together comprise a single, one-piece wick. 
     
     
         8 . The heat pipe system of  claim 1 , wherein the first wick portion is disposed between the condenser region and the second wick portion. 
     
     
         9 . The heat pipe of  claim 1 , wherein the first and second wick portions form an interior space through which the vapor flows to the condenser region. 
     
     
         10 . The heat pipe system of  claim 1 , wherein the first wick portion and the second wick portion are each annular. 
     
     
         11 . A heat pipe system for conducting thermal energy from a heat source, the heat pipe system comprising:
 a wick disposed within a heat pipe, the wick including a first wick portion and a second wick portion, wherein the first wick portion has a first thickness and the second wick portion has a second thickness that is greater than the first thickness;   a condenser in fluid communication with the wick, wherein the condenser does not include the wick at any point along the condenser region; and   a working fluid,   wherein the first wick portion is positioned to receive heat from the heat source and the second wick portion is configured as a reservoir to hold the working fluid for the first wick portion, and   wherein the wick is configured such that (i) when heat is generated by the heat source, working fluid is drawn from the second wick portion to the first wick portion, and vapor formed from evaporation of the working fluid flows past the first wick portion to the condenser such that the vapor condenses and returns back to the wick, and (ii) when no heat is applied to the wick, all of the working fluid is absorbed by at least one of the first wick portion and the second wick portion.   
     
     
         12 . The heat pipe system of  claim 11 , wherein the first wick portion is disposed adjacent an interior surface of the heat pipe. 
     
     
         13 . The heat pipe system of  claim 11 , wherein the second wick portion is disposed adjacent an interior surface of the heat pipe. 
     
     
         14 . The heat pipe system of  claim 11 , wherein the first wick portion is annular. 
     
     
         15 . The heat pipe system of  claim 11 , wherein the second wick portion is annular. 
     
     
         16 . The heat pipe of  claim 1 , wherein the heat pipe defines a sealed chamber, and the first wick portion and the second wick portion are each disposed adjacent an interior surface of the sealed chamber. 
     
     
         17 . The heat pipe system of  claim 11 , wherein the first wick portion and the second wick portion together comprise a single, one-piece wick. 
     
     
         18 . The heat pipe system of  claim 11 , wherein the first wick portion is disposed between the condenser and the second wick portion. 
     
     
         19 . The heat pipe of  claim 11 , wherein the wick forms at least in part an interior space through which the vapor flows to the condenser. 
     
     
         20 . The heat pipe system of  claim 11 , wherein the first wick portion and the second wick portion are each annular. 
     
     
         21 . A method of cooling using a heat pipe, the method comprising:
 providing a wick structure of different thicknesses in an interior of the heat pipe, wherein a condenser region of the heat pipe does not include any portion of the wick structure;   applying heat to the heat pipe at an evaporator region of the heat pipe located adjacent a reservoir region of the heat pipe;   drawing working fluid to a first portion of the wick structure in the evaporator region from an adjacent and thicker second portion of the wick structure in the reservoir region;   evaporating the working fluid in the first portion of the wick structure, so that the vapor flows away from the wick structure;   condensing the working fluid in the condenser region of the heat pipe;   forming a film of condensed working fluid along an inside wall of the heat pipe at the condenser region;   spreading the film along the inside wall of the heat pipe to come into contact with the first portion of the wick structure;   drawing the film of working fluid back into the first portion of the wick structure;   repeating the applying, evaporating, condensing, forming, spreading and drawing steps.   
     
     
         22 . The method of  claim 21 , wherein each of the steps are carried out in a low gravity environment. 
     
     
         23 . The method of  claim 22 , wherein at least a portion of the heat pipe is annular in cross-section.