Heat pipe

Abstract

A heat pipe for improving heat transport performance by reducing heat resistance in an evaporating section is provided. The heat pipe comprises a groove wick extending in the longitudinal direction from the evaporating section to the condensing section through the insulated section in the container. A metal powder layer formed of metal powder adhering to the inner wall of the groove wick is arranged in the evaporating section. The metal powder layer is formed into the groove wick having a predetermined thickness.

What is claimed is: 
     
         1 . A heat pipe, comprising:
 a container sealed at both longitudinal ends;   a working fluid encapsulated in the container;   a wick that pulls the working fluid by a capillary pumping;   an evaporating section situated on one of the longitudinal ends of the container at which evaporation of the working fluid takes place; and   a condensing section situated on the other longitudinal end of the container at which condensation of the working fluid takes place;   wherein the wick includes a groove wick having a plurality of grooves extending on an inner wall of the container between the condensing section and the evaporating section via the insulated section while keeping predetermined intervals;   the heat pipe further comprising a metal powder layer formed at least on an inner wall of the groove wick and at least within the evaporating section; and   wherein a thickness of the metal powder layer falls within a predetermined range.   
     
     
         2 . The heat pipe as claimed in  claim 1 ,
 wherein the inner wall of the groove wick includes a pair of side walls and a bottom wall connecting the side walls:   wherein each groove of the groove wick is individually shaped to have a U-shaped cross-section;   wherein the metal powder layer includes a first portion formed on the side wall having a thickness less than one fifth of a width of each groove; and   wherein the metal powder layer includes a second portion formed on the bottom wall having a thickness less than one third of a depth of each groove.   
     
     
         3 . The heat pipe as claimed in  claim 2 ,
 wherein the container is made of metal;   wherein the metal powder includes copper particles whose grain size falls within a range from 1 to 5 μm, and the metal powder is sintered to the inner wall; and   wherein the thickness of the metal powder layer is restricted within a range from one to five times of grain size of the metal powder in such a manner that the thickness of the first portion is restricted to be less than one third of the width of each groove, and that the thickness of the second portion is restricted to be less than one fifth of the depth of each groove.   
     
     
         4 . The heat pipe as claimed in  claim 3 , wherein the metal powder is sprinkled sparsely on the inner wall in the evaporating section in such a manner that a surface of the inner wall is exposed partially and finely textured. 
     
     
         5 . The heat pipe as claimed in  claim 3 , wherein the metal powder layer is formed into a porous wick by sintering the deposited metal powder. 
     
     
         6 . The heat pipe as claimed in  claim 1 , wherein the metal powder layer is also formed on the inner surface of the container between the grooves. 
     
     
         7 . The heat pipe as claimed in  claim 6 , wherein a thickness of the metal powder layer formed on the inner surface of the container between the grooves is less than one fifth of a width of the each groove. 
     
     
         8 . The heat pipe as claimed in  claim 1 ,
 wherein the container includes a flat container; and   wherein the groove wick is formed entirely on the inner wall of the container.   
     
     
         9 . The heat pipe as claimed in  claim 1 , wherein the metal powder layer is formed only within the evaporating section. 
     
     
         10 . A heat pipe, comprising:
 a metal container sealed at both longitudinal ends;   a working fluid encapsulated in the container;   a wick that pulls the working fluid by a capillary pumping;   an evaporating section situated on one of the longitudinal ends of the container at which evaporation of the working fluid takes place; and   a condensing section situated on the other longitudinal end of the container at which condensation of the working fluid takes place;   wherein the wick includes a groove wick having a plurality of grooves extending on an inner wall of the container between the condensing section and the evaporating section via the insulated section while keeping predetermined intervals;   the heat pipe further comprising a metal powder layer that is formed of copper particles whose grain size fall within a range from 1 to 5 μm, and that is formed at least on an inner wall of the groove wick and at least within the evaporating section; and   wherein a thickness of the metal powder layer falls within a predetermined range;   wherein the inner wall of the groove wick includes a pair of side walls and a bottom wall connecting the side walls;   wherein each groove of the groove wick is individually shaped to have a U-shaped cross-section;   wherein the metal powder layer includes a first portion formed on the side wall having a thickness less than one fifth of a width of each groove and within a range from one to five times of grain size of the metal powder; and   wherein the metal powder layer includes a second portion formed on the bottom wall having a thickness less than one third of a depth of each groove and within a range from one to five times of grain size of the metal powder.   
     
     
         11 . The heat pipe as claimed in  claim 10 , wherein the metal powder is sprinkled sparsely on the inner wall in the evaporating section in such a manner that a surface of the inner wall is exposed partially and finely textured. 
     
     
         12 . The heat pipe as claimed in  claim 10 , wherein the metal powder layer is formed into a porous wick by sintering the deposited metal powder. 
     
     
         13 . The heat pipe as claimed in  claim 10 , wherein the metal powder layer is also formed on the inner surface of the container between the grooves. 
     
     
         14 . The heat pipe as claimed in  claim 13 , wherein a thickness of the metal powder layer formed on the inner surface of the container between the grooves is less than one fifth of a width of the each groove. 
     
     
         15 . The heat pipe as claimed in  claim 10 ,
 wherein the container includes a flat container; and   wherein the groove wick is formed entirely on the inner wall of the container.