US20080078530A1

Movatterモバイル変換

Info

Publication number: US20080078530A1
Application number: US11/309,808
Authority: US
Inventors: Chang-Shen Chang; Juei-Khai Liu; Chao-Hao Wang; Hsien-Sheng Pei
Original assignee: Foxconn Technology Co Ltd
Current assignee: Foxconn Technology Co Ltd
Priority date: 2006-10-02
Filing date: 2006-10-02
Publication date: 2008-04-03

Abstract

A loop heat pipe (10) includes an evaporator (11) thermally connected with a heat generating electronic component and including a wick structure (112) disposed therein, a condenser (12) thermally connected with a heat dissipating component, a vapor line (13) and a liquid line (14) connecting the evaporator with the condenser to form a closed loop, a predetermined quantity of bi-phase working medium contained in the closed loop, and an artery mesh (15) located within the liquid line.

Description

1. FIELD OF THE INVENTION

The present invention relates generally to a loop heat pipe for transfer or dissipation of heat from heat-generating components, and more particularly to a loop heat pipe with flexible artery mesh disposed therein for improving heat dissipation for the heat-generating components.

2. DESCRIPTION OF RELATED ART

Loop heat pipes have excellent heat transfer performance due to their low thermal resistance, and are therefore an effective means for transfer or dissipation of heat from heat-generating components such as central processing units (CPUs) of computers.

A conventionally loop heat pipe includes an evaporator thermally connected with a CPU and disposing a wick structure therein, a condenser thermally connected with a heat sink, a vapor line and a liquid line disposed between and connecting the evaporator with the condenser, a compensation disposed between the wick structure and the liquid line, and a predetermined quantity of bi-phase working medium contained in the evaporator and the liquid line.

During operation of the loop heat pipe, the working medium in the evaporator absorbs heat from the CPU and vaporizes, thus generating a vapor pressure which propels vaporized working medium towards the condenser via the vapor line. The vaporized working medium dissipates the heat to the heat sink at the condenser and condenses to liquid thereat. The condensed working medium is then propelled through the liquid line, the compensation and the evaporator in that order by the vapor pressure and by capillary action generated by the wick structure. The condensed working medium at the evaporator then evaporates and is condensed to liquid thus perpetuating the cycle.

In the operation of the loop heat pipe, the working medium at the evaporator needs to be heated to vaporize and generate enough vapor pressure to conquer gravitational force acting on the working medium in the liquid line so as to power the circulation of the working fluid. Therefore, a start up temperature must first be achieved before the heat pipe can operate, which troubles the loop heat pipe to be operated in a lower temperature.

Therefore, it is desirable to provide a loop heat pipe which has better gravity conquest capability and easily to be operated under lower temperature.

SUMMARY OF THE INVENTION

The present invention relates to a loop heat pipe for removing heat from heat-generating components. The loop heat pipe includes an evaporator with a wick structure disposed therein and thermally connected with a heat generating electronic component, a condenser thermally connected with a heat dissipating component, a vapor line and a liquid line connecting the evaporator with the condenser to form a closed loop, with a predetermined quantity of bi-phase working medium contained in the closed loop, and an artery mesh disposed within the liquid line.

Other advantages and novel features of the present invention will become more apparent from the following detailed description of preferred embodiment when taken in conjunction with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views:

FIG. 1 is a loop heat pipe in accordance with a preferred embodiment of the present invention;

FIG. 2 is an enlarged transverse cross-sectional view of the loop heat pipe ofFIG. 1, taken along line II-II;

FIG. 3 is an enlarged transverse cross-sectional view of the loop heat pipe ofFIG. 1, taken along line III-III;

FIG. 4 is an enlarged view of a circled portion IV of the loop heat pipe ofFIG. 1;

FIG. 5 is an enlarged transverse cross-sectional view of the loop heat pipe ofFIG. 1, taken along line V-V;

FIG. 6 is a front view of an artery mesh of the loop heat pipe ofFIG. 1; and

FIG. 7 a transverse cross-sectional view of the artery mesh of theFIG. 6, taken along line VII-VII.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates aloop heat pipe10 in accordance with a first embodiment of the present invention. Theloop heat pipe10 includes anevaporator11 thermally connected with a heat generating electronic component such as a CPU (not shown), acondenser12 thermally connected with a heat dissipating component such as a heat sink (not shown), vapor and

liquid lines

13,14 connecting theevaporator11 with thecondenser12 to form a closed loop, a predetermined quantity of bi-phase working medium (not labeled) contained in the closed loop, and a flexibleinterwoven artery mesh15 disposed within theliquid line14.

Referring particularly toFIGS. 2 and 3, theevaporator11 is a hollow tube which contains awick structure112 coextensive with a central longitudinal axis of theevaporator11. Thewick structure112 is tubular shaped in profile and has a column shapedouter wall113 contacting with an inner wall of theevaporator11. Thewick structure112 has a closedend114 abutting against theliquid line14 and anopen end115 abutting against thevapor line13. A column-shaped vapor channel116 communicating with an inner space of thevapor line13 is defined in a middle portion along a central longitudinal axis of thewick structure112. A diameter of thevapor channel116 is larger than a diameter of an inner wall of thevapor line13, thus increasing the flow rate of vaporized working medium entering into the inner space of thevapor line13. Thewick structure112 in theevaporator11 of theloop heat pipe10 can, for example, consist of porous structures, such as fine grooves integrally formed at the inner wall of theevaporator11, screen mesh or fiber inserted into theevaporator11 and held against the inner wall thereof, or sintered powders combined to the inner wall of theevaporator11 using a sintering process.

Thecondenser12 is disposed distant from theevaporator11 and has a lower temperature than that of theevaporator11, thus causing the vaporized working medium to be condensed. Thecondenser12 is a heat sink including a plurality of fins (not shown) for increasing heat dissipation area thereof so as to benefit the condensation of the vaporized working medium. An end of theliquid line14 extends into thecondenser12 and connects with thevapor line13 so that the vaporized working medium is condensed at thecondenser12 and is directly propelled towards theevaporator11. Alternatively, thecondenser12 may be a cooling chamber, with theliquid line14 and thevapor line13 separating from each other and respectively connecting with two ends of the chamber. Under this status, the vaporized working medium enters into thecondenser12 and is condensed thereat. The condenser working medium in thecondenser12 enters into theliquid line14 and is propelled towards theevaporator11.

The vapor and the

liquid lines

13,14 are made of deformable materials compatible with the working medium, such as aluminum, stainless steel, or plastics. Each of the vapor and

liquid lines

13,14 includes two

parallel sections

13aand13b/14aand14bwith two corresponding ends thereof connecting with the respective ends of theevaporator11 and thecondenser12, and aperpendicular section13c/14cwith two ends thereof connecting with the other two ends of the

parallel sections

13aand13b/14aand14b.

The working medium is usually selected from a liquid which has a low boiling point such as water, methanol, or alcohol. Thus, the working medium can easily evaporate to vapor when it receives heat in theevaporator11 and condense to liquid when it dissipates heat in thecondenser12.

Referring toFIGS. 4 to 7, theartery mesh15 is an elongated hollow tube, which is attached to and extends along an inner wall of theliquid line14. Theartery mesh15 is woven from a plurality of metal wires151 (FIG. 6), such as copper, or stainless steel wires. Alternatively, theartery mesh15 can be formed by weaving a plurality of non-metal threads such as fiber together. Afirst channel152 is defined in an inner space of theartery mesh15, whilst asecond channel153 is defined between an outer wall of theartery mesh15 and the inner wall of theliquid line14 for passage of the condensed working medium. A plurality of pores (not shown) are formed in a peripheral wall of theartery mesh15, which provide capillary action to the working medium and communicate thefirst channel152 with thesecond channel153. Theartery mesh15 has a ring-like transverse cross section, a diameter of which is smaller than a diameter of theliquid line14. Theartery mesh15 has a linear contact with the inner wall of theliquid line14 thereby defining anadjacent portion154 contacting with the inner wall of theliquid line14 and adistal portion155 spaced a distance from the inner wall of theliquid line14 along a radial direction of theloop heat pipe10. In the presentloop heat pipe10, theartery mesh15 may be loosely inserted into theliquid line14 with some portions thereof isolated from the inner walls thereof.

In operation of theloop heat pipe10, the working medium in theevaporator11 absorbs heat from the heat generating electronic component and evaporates. A vapor pressure is generated due to the vaporization of the working medium and propels the vaporized working medium into thevapor line13 and towards thecondenser12. The vaporized working medium looses its heat to the heat dissipating component at thecondenser12 and condenses to liquid to accumulate in thecondenser12 and theartery mesh15 thereat. The condensed working medium in thecondenser12 is propelled towards theliquid line14 and into theevaporator11 via the vapor pressure and the capillary force generated by theartery mesh15 and thewick structure112. The condensed working medium then evaporates to vapor thus perpetuating a cycle in the loop heat pipe and continuously absorbing heat from the heat generating electronic component and dissipate the heat to the heat dissipating component.

In the presentloop heat pipe10, the capillary force generated by theartery mesh15 conquers the gravity action of the condensed working medium and helps to propel the condensed working medium to enter into theevaporator11 via theliquid line14. Therefore, the vapor pressure exerted on the condensed working medium is decreased, and the start up temperature needed to generate the vapor pressure is accordingly decreased. This results in the dependence of the start up temperature of theloop heat pipe10 not being limited by the gravity action of the condensed working medium. Thus, theloop heat pipe10 is easy to be operated under a lower temperature and is preferably used for dissipating heat generated by heat sensitive electronic components.

As compared to a conventional loop heat pipe with a plurality of vapor channels defined between an inner wall of the evaporator and an outer wall of the wick structure, thewick structure112 of the presentloop heat pipe10 has a larger contacting area for the inner wall of theevaporator11. The larger contacting area of the inner wall of the evaporator enables the heat generating electronic component to transfer more heat to the working medium in theevaporator11 and therefore increases the heat dissipation efficiency of the presentloop heat pipe10. Moreover, thewick structure112 has a simpler structure than the conventional loop heat pipe, which simplifies the manufacture thereof. Furthermore, a part of the condensed working medium is accommodated in the artery mesh of the presentloop heat pipe10, which compensates for the working medium in theevaporator11 which evaporates to vapor, thus preventing the drying out of the evaporator. Thus, there is no need to for additional compensation in theevaporator11 thus preventing the working medium therein from drying out, which reduces the volume of theevaporator11 of the presentloop heat pipe10.

It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Claims

1. A loop heat pipe comprising:

an evaporator configured for thermally connecting with a heat generating electronic component and comprising a wick structure disposed therein;

a condenser configured for thermally connecting with a heat dissipating component;

a vapor line and a liquid line connecting the evaporator with the condenser to form a closed loop;

a predetermined quantity of bi-phase working medium filled in the closed loop; and

an artery mesh positioned within the liquid line.

2. The loop heat pipe ofclaim 1, wherein the artery mesh has a linear contact with an inner wall of the liquid line.

3. The loop heat pipe ofclaim 1, wherein a diameter of a cross section of the artery mesh is smaller than that of the liquid line.

4. The loop heat pipe ofclaim 1, wherein the artery mesh is a flexible hollow tube woven from a plurality of metal wires.

5. The loop heat pipe ofclaim 4, wherein the material of the metal wires is selected from a group consisting of copper wires and stainless steel wires.

6. The loop heat pipe ofclaim 1, wherein the artery mesh is formed by weaving a plurality of fiber together.

7. The loop heat pipe ofclaim 1, wherein the wick structure is selected from the group consisting of grooves, sintered powder, fiber and screen mesh.

8. The loop heat pipe ofclaim 1, wherein the wick structure is tubular shaped in profile and disposed in an inner wall of the evaporator.

9. The loop heat pipe ofclaim 1, wherein the wick structure has a closed end contacting with the liquid line and an open end communicating with the vapor line, a vapor channel being defined in a middle portion of the open end.

10. A loop heat pipe comprising:

a vapor line connecting an open end of the wick structure with the condenser;

a liquid line connecting a closed end of the wick structure with the condenser;

a vapor channel defined in a middle portion of the open end of the wick structure and communicating with the vapor line;

an artery mesh positioned within the liquid line; and

a predetermined quantity of bi-phase working medium contained in the loop heat pipe.

11. The loop heat pipe ofclaim 10, wherein the artery mesh is a hollow tube in contact with an inner wall of the liquid line.

12. The loop heat pipe ofclaim 10, wherein a diameter of a cross section of the artery mesh is smaller than that of the liquid line.

13. The loop heat pipe ofclaim 10, wherein the artery mesh is woven from a plurality of metal wires selected from a group consisting of copper and stainless steel wires.

14. The loop heat pipe ofclaim 10, wherein the artery mesh is tightly attached to inner walls of the liquid line.

15. The loop heat pipe ofclaim 10, wherein the wick structure has a column shaped outer wall contacting with an inner wall of the evaporator.

16. The loop heat pipe ofclaim 10, wherein a diameter of the vapor channel is larger than a diameter of an inner wall of the vapor line.