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 casing has an evaporating section ( 400 ), a condensing section ( 600 ) and a central section ( 500 ) between the evaporating section and the condensing section. A first type of capillary wick ( 250 ) is provided in the central section of casing and a second type of capillary wick ( 240 ) is disposed at the evaporating section of the casing. The capillary pore size of the first type of capillary wick is larger than that of the second type of capillary wick and the first type of capillary wick is made by stacked metal sheets.

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 central section, the first type of capillary wick being formed by metal sheets; and   a second type of capillary wick disposed on the inner wall of the casing at the evaporating section; wherein   a capillary pore size of the first type of capillary wick is larger than that of the second type of capillary wick and a vapor passage is enclosed by the first and second types of the capillary wick.   
   
   
       2 . The heat pipe of  claim 1 , wherein the metal sheets are tightly stacked together along a radial direction of the casing with an outer metal sheet being attached to the inner wall of the casing. 
   
   
       3 . The heat pipe of  claim 2 , wherein each metal sheet is folded and the first type of capillary wick has a beehive-shaped structure in the radial direction of the casing. 
   
   
       4 . The heat pipe of  claim 3 , wherein the first type of capillary wick is also arranged in the condensing section of the casing. 
   
   
       5 . The heat pipe of  claim 4 , wherein thicknesses of the first and second types of capillary wick from the condensing section to the evaporating section via the central section are gradually increased and the vapor passage has a gradually decreasing radial cross-sectional area along a longitudinal direction of the casing from the condensing section toward the evaporating section. 
   
   
       6 . The heat pipe of  claim 4 , wherein the second type of capillary wick is one of sintered-type wick and mesh-type wick. 
   
   
       7 . The heat pipe of  claim 3 , wherein a sintered-type wick is disposed in the condensing section of the casing and has a capillary pore size larger than that of the second type of capillary wick at the evaporating section of the casing. 
   
   
       8 . The heat pipe of  claim 7 , wherein thicknesses of the capillary wicks from the condensing section to the evaporating section via the central section are gradually increased and the vapor passage has a gradually decreasing radial cross-sectional area along a longitudinal direction of the casing from the condensing section toward the evaporating section. 
   
   
       9 . The heat pipe of  claim 8 , wherein the second type of capillary wick has a thickest point at the evaporating section of the casing in a radial direction of the casing. 
   
   
       10 . The heat pipe of  claim 3 , wherein each metal sheet has a cross-sectional configuration with a plurality of serrations disposed along a circle.