Heat pipe with composite wick structure

Abstract

A heat pipe ( 10 ) includes a metal casing ( 12 ) having an evaporator section ( 121 ) and a condenser section ( 122 ). A major wick structure ( 14 ) is disposed on an inner wall of the casing. At least one assistant wick structure ( 16 ) is disposed in and contacts with the major wick structure, and working medium fills in the casing and saturates the major wick structure and the at least one assistant wick structure. An average pore size of the major wick structure corresponding to the evaporator section is smaller than that of the major wick structure corresponding to the condenser section. A diameter of a cross section of the at least one assistant wick structure is smaller than a diameter of a cross section of the major wick structure, and thus the at least one assistant wick structure has a linear contact with the major wick structure.

1 . A heat pipe comprising:
 an elongated casing having an evaporator section and a condenser section;   a major wick structure disposed on an inner wall of the casing, an average pore size of the major wick structure corresponding to the evaporator section being smaller than that of the major wick structure corresponding to the condenser section;   at least one assistant wick structure disposed in and contacting with an inner wall of the major wick structure and extending from the evaporator section to the condenser section, a diameter of a cross section of the at least one assistant wick structure being smaller than a diameter of a cross section of the major wick structure, the at least one assistant wick structure having a linear contact with the inner wall of the major wick structure; and   working medium filling in the casing and saturating the major wick structure and the at least one assistant wick structure.   
   
   
       2 . The heat pipe of  claim 1 , wherein the at least one assistant wick structure is a hollow tube made of sintered powder. 
   
   
       3 . The heat pipe of  claim 1 , wherein the at least one assistant wick structure is a hollow tube made of a plurality of woven metal wires, and the metal wires are selected from a group consisting of copper wires and stainless steel wires. 
   
   
       4 . The heat pipe of  claim 1 , wherein the at least one assistant wick structure comprises a plurality of assistant wick structures spacing a distance from each other. 
   
   
       5 . The heat pipe of  claim 1 , wherein the at least one assistant wick structure comprises a plurality of assistant structures contacting with each other. 
   
   
       6 . The heat pipe of  claim 1 , wherein the at least one assistant wick structure is a hollow tube with an inner diameter ranging from 0.5 mm to 2 mm. 
   
   
       7 . The heat pipe of  claim 1 , wherein the major wick structure is selected from the group of grooves, sintered powder, fiber and screen mesh. 
   
   
       8 . The heat pipe of  claim 7 , wherein the major wick structure corresponding to the evaporator section of the heat pipe is one of sintered powder and screen mesh, and the major wick structure corresponding to the condenser section of the heat pipe is grooves. 
   
   
       9 . The heat pipe of  claim 7 , wherein the major wick structure corresponding to the evaporator section of the heat pipe has two layers stacked along a radial direction of the heat pipe, one layer being grooves and the other layer being one of sintered powder and screen mesh. 
   
   
       10 . A heat pipe comprising:
 a metal casing having an evaporator section and a condenser section;   a porous major wick structure disposed on an inner wall of the casing, an average pore size of the major wick structure corresponding to the evaporator section being smaller than that of the wick structure corresponding to the condenser section;   at least one assistant wick structure disposed in an inner wall of the major wick structure, the at least one assistant wick structure defining a plurality of pores communicating an inside of the at least one assistant wick structure with an inside of the major wick structure and a channel in an inner space thereof; and   working medium filling in the casing and saturating the major wick structure and the at least one assistant wick structure;   wherein vapor in the metal casing flows from the evaporator section to the condenser section via a space between the major wick structure and the at least one assistant wick structure, and condensate in the metal casing flows from the condenser section to the evaporator section via the pores of the major and the assistant wick structures and the channel of the assistant wick structure.   
   
   
       11 . The heat pipe of  claim 10 , wherein a diameter of the at least one assistant wick structure ranges from 0.5 mm to 2 mm. 
   
   
       12 . The heat pipe of  claim 10 , wherein the at least one assistant wick structure is made of a plurality of woven metal wires selected from a group consisting of copper and stainless steel wires. 
   
   
       13 . The heat pipe of  claim 10 , wherein the at least one assistant wick structure comprises a plurality of assistant wick structures spaced from each other. 
   
   
       14 . The heat pipe of  claim 13 , wherein the plurality of assistant wick structures are evenly spaced from each other. 
   
   
       15 . The heat pipe of  claim 10 , wherein the at least one assistant wick structure comprises a plurality of assistant wick structures contacting with each other. 
   
   
       16 . The heat pipe of  claim 10 , wherein the major wick structure is selected from the group of grooves, sintered powder, fiber and screen mesh. 
   
   
       17 . The heat pipe of  claim 16 , wherein the major wick structure corresponding to the evaporator section of the heat pipe is one of sintered powder and screen mesh, and the major wick structure corresponding to the condenser section of the heat pipe is grooves. 
   
   
       18 . The heat pipe of  claim 16 , wherein the major wick structure corresponding to the evaporator section of the heat pipe has two layers stacked along a radial direction of the heat pipe, one layer being grooves and the other layer being one of sintered powder and screen mesh.