Heat pipe with composite capillary wick structure

Abstract

A heat pipe includes a metal casing ( 100 ) and a composite capillary wick received in the casing. The metal casing has an evaporating section ( 400 ), a condensing section ( 600 ) and a central section ( 500 ) between the evaporating section and the condensing section. First type of capillary wick ( 200 ) is provided on an inner all of the metal casing at all of the condensing, central and evaporating sections, while second type of capillary wick ( 220 ) is provided on the first type of capillary wick at the central and evaporating sections only. A capillary pore size of the first type of capillary wick is larger than that of the second type of capillary wick.

1 . A heat pipe comprising:
 a metal casing containing a working fluid therein, the casing comprising an evaporating section at one end and a condensing section at an opposite end thereof, and a central section located between the evaporating section and the condensing section;   a first type of capillary wick arranged in an inner wall of the casing at the condensing, central and evaporating sections of the casing and a second type of capillary wick disposed on the first type of capillary wick at the central and evaporating sections; wherein   a capillary pore size of the first type of capillary wick is larger than that of the second type of capillary wick.   
   
   
       2 . The heat pipe of  claim 1 , wherein the first type of capillary wick is a plurality of fine grooves defined in the inner wall of the metal casing, and the second type of capillary wick is a fine mesh. 
   
   
       3 . The heat pipe of  claim 1 , wherein the first type of capillary wick is a plurality of fine grooves defined in the inner wall of the metal casing, and the second type of capillary wick comprises a fine mesh at the central section and a sintered-type wick at the evaporating section. 
   
   
       4 . The heat pipe of  claim 3 , further comprising an additional fine mesh arranged on the sintered-type wick at the evaporating section of the metal casing, the additional fine mesh connecting with the fine mesh at the central section of the metal casing. 
   
   
       5 . The heat pipe of  claim 4 , wherein the sintered-type wick is formed by one of sintered metal powders and sintered ceramic powders and the sintered-type wick fills in the fine grooves. 
   
   
       6 . The heat pipe of  claim 4 , wherein the additional fine mesh has a capillary pore size larger than that of the sintered-type wick. 
   
   
       7 . The heat pipe of  claim 5 , wherein a capillary pore size of the first type of capillary wick, the sintered-type of capillary wick and the additional fine mesh at the evaporating section is gradually increased in an inward direction from the first type of capillary wick toward the additional fine mesh. 
   
   
       8 . The heat pipe of  claim 1 , wherein the first type of capillary wick has a lower liquid flow resistance than that of the second type of capillary wick. 
   
   
       9 . A heat pipe comprising:
 a hollow metal casing containing a working fluid therein, the casing comprising an evaporating section, a condensing section and a central section between the evaporating section and the condensing section; and   first capillary wick applied to an inner wall of the metal casing at the central section and second capillary wick applied on the first capillary wick, the first capillary wick generating a smaller flow resistance for the working fluid than the second capillary wick.   
   
   
       10 . The heat pipe of  claim 9 , wherein the first capillary wick is also arranged in the inner wall of the metal casing at the evaporating and condensing sections. 
   
   
       11 . The heat pipe of  claim 10 , wherein the first capillary wick is a plurality of fine grooves, and the second capillary wick is a fine mesh. 
   
   
       12 . The heat pipe of  claim 11 , wherein an additional fine mesh is located on the first capillary wick at the evaporating of the casing and connects with the second capillary wick at the central section of the metal casing. 
   
   
       13 . The heat pipe of  claim 11 , wherein a sintered-type wick is located on the first capillary wick at the evaporating section of the metal casing. 
   
   
       14 . The heat pipe of  claim 13 , wherein an additional fine mesh is located on the sintered-type wick at the evaporating section of the casing and connects with the second capillary wick at the central section of the metal casing, a capillary pore size of the first capillary wick, the sintered-type wick and the additional fine mesh at the evaporating section of the metal casing is gradually increased in an inward direction from first capillary wick to the additional fine mesh.