US20190316848A1

US20190316848A1 - Loop heat pipe with fluid slug pipe

Info

Publication number: US20190316848A1
Application number: US16/015,849
Authority: US
Inventors: Chuan-Chi TSENG; Yueh-Lung Chuang; Xiao-Long Wu
Original assignee: Tai Sol Electronics Co Ltd
Current assignee: Tai Sol Electronics Co Ltd
Priority date: 2018-04-16
Filing date: 2018-06-22
Publication date: 2019-10-17
Also published as: TW201944019A; JP2019184219A; TWI660149B

Abstract

A loop heat pipe with fluid slug pipes includes: an evaporation chamber having a casing and a wick disposed therein; a return line having two ends connected to the casing; and a working fluid filling the evaporation chamber. A condensation segment is defined as a predetermined length of a body of the return line. A vapor segment is defined as a portion of the return line, extending from the condensation segment to the vapor end. A liquid segment is defined as another portion of the return line, extending from the condensation segment to the liquid end. At least one partition element is disposed inside the liquid segment to thereby divide the liquid segment into at least two fluid slug pipes not in communication with each other but in communication with the condensation segment and the casing. The fluid slug pipes each have a smaller diameter than the return line.

Description

BACKGROUND OF THE INVENTION

1. Technical Field

The present disclosure relates to loop heat pipes and, more particularly, to a loop heat pipe with fluid slug pipes.

2. Description of Related Art

Taiwan patent 1604173 discloses a loop heat pipe which has a casing and an external circulation line. The casing comprises an outer case and an inner case. The outer case has a higher coefficient of thermal conductivity than the inner case. A conductive opening of the inner case has a wick component. However, a liquid line of the loop heat pipe is not specially designed to facilitate ease of flow of liquid; as a result, the return of the liquid passing the liquid line into the casing is unlikely to be smooth.
Taiwan patent 1304467 discloses another loop heat pipe which consists of a liquid line with flexible braided vasa therein so that return of liquid is smooth. However, the loop heat pipe requires the flexible braided vasa to be coupled to the liquid line and a condensation portion; but the aforesaid structure not only overburdens the assembly procedure during the manufacturing process, but also necessitates sintering it. As a result, the loop heat pipe not only adds to manufacturing costs, but also reduces yield because of poor assembly or sintering.

BRIEF SUMMARY OF THE INVENTION

It is an objective of the present disclosure to provide a loop heat pipe with fluid slug pipes, characterized in that a liquid segment of a return line is divided into pipes of a smaller diameter so as for a liquid working fluid to produce fluid slugs, and in consequence the liquid working fluid can still move and return to an evaporator smoothly under a pressure difference in the return line even in the absence of a capillary force.
Another objective of the present disclosure is to provide a loop heat pipe with fluid slug pipes, characterized in that a liquid segment of a return line is not confronted with problems related to assembly of braided vasa or any other wick, thereby reducing manufacturing costs but enhancing yield.
In order to achieve the above and other objectives, the present disclosure provides a loop heat pipe with fluid slug pipes, comprising: an evaporation chamber having a casing and a wick disposed in the casing, the wick not occupying the casing fully so as for a vapor space to be formed between the wick and the casing; a return line having two ends defined as a vapor end and a liquid end, respectively, the vapor end connecting to the casing and thereby being in communication with the space, and the liquid end connecting to the casing and thereby being in communication with an inside of the casing; and a working fluid filling the evaporation chamber; wherein a condensation segment is defined as a predetermined length of a body of the return line, allowing a heat-dissipating unit to be disposed on a surface of the condensation segment, a vapor segment is defined as a portion of the return line, the portion extending from the condensation segment to the vapor end, and a liquid segment is defined as another portion of the return line, the another portion extending from the condensation segment to the liquid end, with at least one partition element disposed in an inside of the liquid segment of the return line to thereby divide the liquid segment of the return line into at least two fluid slug pipes not in communication with each other but in communication with the condensation segment and the casing, wherein the at least two fluid slug pipes each have a smaller diameter than the return line.
Therefore, the present disclosure has advantages as follows: the liquid segment of the return line is divided into pipes of a smaller diameter so as for a liquid working fluid to produce fluid slugs, and in consequence the liquid working fluid can still move and return to an evaporator smoothly under a pressure difference in the return line even in the absence of a capillary force. Furthermore, according to the present disclosure, the liquid segment of the return line is not confronted with problems related to assembly of braided vasa or any other wick, thereby reducing manufacturing costs but enhancing yield.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view of a loop heat pipe with fluid slug pipes according to the first preferred embodiment of the present disclosure;

FIG. 2 is a horizontal cross-sectional view of the loop heat pipe with fluid slug pipes according to the first preferred embodiment of the present disclosure;

FIG. 3 is a cross-sectional view of a return line and a partition element according to the first preferred embodiment of the present disclosure;

FIG. 4 is another cross-sectional view of the partition element according to the first preferred embodiment of the present disclosure;

FIG. 5 is yet another cross-sectional view of the partition element according to the first preferred embodiment of the present disclosure;

FIG. 6 is still yet another cross-sectional view of the partition element according to the first preferred embodiment of the present disclosure;

FIG. 7 is a horizontal cross-sectional view of the loop heat pipe with fluid slug pipes according to the second preferred embodiment of the present disclosure;

FIG. 8 is a horizontal cross-sectional view of the loop heat pipe with fluid slug pipes according to the third preferred embodiment of the present disclosure;

FIG. 9 is a horizontal cross-sectional view of the loop heat pipe with fluid slug pipes according to the fourth preferred embodiment of the present disclosure; and

FIG. 10 is a horizontal cross-sectional view of the loop heat pipe with fluid slug pipes according to the fifth preferred embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Technical features of the present disclosure are illustrated by preferred embodiments, depicted by drawings, and described below.
Referring to FIG. 1 through FIG. 6, a loop heat pipe 10 with fluid slug pipes according to the first preferred embodiment of the present disclosure essentially comprises an evaporation chamber 11, a return line 21 and a working fluid 31.
The evaporation chamber 11 has a casing 12 and a wick 14 disposed in the casing 12. The wick 14 does not occupy the inside of the casing 12 fully and thereby a vapor space 16 is formed between the wick 14 and the casing 12. The vapor space 16 has a common room 161 and a plurality of branch rooms 162. The plurality of branch rooms 162 are separated by a predetermined distance because of the wick 14. The plurality of branch rooms 162 are each in communication with the common room 161; except for the aforesaid communication, the plurality of branch rooms 162 are not in communication with each other in any other portion. The wick 14 in this embodiment is made of sintered copper powder.
The return line 21 has two ends which are defined as a vapor end 214 and a liquid end 216, respectively. The vapor end 214 of the return line 21 is connected to the casing 12 and thereby is in communication with the space. The liquid end 216 of the return line 21 is connected to the casing 12 and thereby is in communication with the inside of the casing 12.
The working fluid 31 in this embodiment is exemplified by pure water that fills the evaporation chamber 11, is adsorbed to the wick 14, and exists at a portion of the return line 21.
A condensation segment 22 is defined as a predetermined length of a body of the return line 21. A heat-dissipating unit 100 is disposed on the surface of the condensation segment 22. In practice, the heat-dissipating unit 100 comprises a plurality of fins. Furthermore, a vapor segment 24 is defined as a portion of the return line 21, and the portion extends from the condensation segment 22 to the vapor end 214. A liquid segment 26 is defined as another portion of the return line 21, and the another portion extends from the condensation segment 22 to the liquid end 216. A partition element 28 is disposed in the inside of the liquid segment 26 of the return line 21 to thereby divide the liquid segment 26 of the return line 21 into two sub-pipes defined as fluid slug pipes 29, respectively. The two fluid slug pipes 29 are not in communication with each other in the liquid segment 26 of the return line 21. The two fluid slug pipes 29 each have a smaller diameter than the return line 21. The two fluid slug pipes 29 are each in communication with the condensation segment 22 and the casing 12. In practice, the partition element 28 is a plate and thus is integrally formed with the return line 21. The working fluid 31 is disposed in the liquid segment 26 of the return line 21.
In this embodiment, the partition element 28 is disposed at the liquid segment 26 and extended to the condensation segment 22 as well as the full length of the condensation segment 22, but not to the vapor segment 24. With the condensation segment 22 being a place where a gaseous working fluid condenses into a liquid working fluid, the fact that the partition element 28 is extended to the full length of the condensation segment 22 ensures that the fluid slug pipes 29 are formed at the condensation segment 22 in its entirety. The fluid slug pipes 29 each have a smaller diameter than the return line 21; hence, a liquid working fluid can form fluid slugs such that the liquid working fluid can still move and return to the evaporation chamber 11 smoothly under a pressure difference in the return line 21 even in the absence of a capillary force, so as to be adsorbed by the wick 14.
In this embodiment, the vapor segment 24 has the same diameter as the liquid segment 26. Furthermore, the fluid slug pipes 29 each have a smaller diameter than the vapor segment 24 of the return line 21. Therefore, not only is it definitely defined as to how great the diameter of the fluid slug pipes 29 is relative to the return line 21, but it is also understandable why the fluid slug pipes 29 have a smaller diameter and thus can form the fluid slugs easily.
Referring to FIG. 4, when the partition element 28′ is a plate, the outline of its cross section is not necessarily linear, but may be curved. Referring to FIG. 5, the partition element 28″ is not necessarily in the number of one, but may be three, and thus the three partition elements 28″ divide the return line 21″ into three fluid slug pipes 29″. Referring to FIG. 6, the partition element 28′″ is not necessarily plate-shaped, but may be a pipe wall left behind after a solid post shown in FIG. 6 has been hollowed out to form a tube.
Structural features of the first preferred embodiment are described above. Operation-related features of the first preferred embodiment are described below.
Referring to FIG. 1 and FIG. 2, before using the loop heat pipe 10, a user attaches the evaporation chamber 11 to an object to-cool (such as a central processing unit, CPU, not shown) and mounts a heat-dissipating unit 100 on the condensation segment 22 of the return line 21. The heat-dissipating unit 100 in this embodiment comprises a plurality of fins.
During the operation of the loop heat pipe 10, heat is transferred from the object to-cool to the evaporation chamber 11, and thus the working fluid adsorbed to the wick 14 in the evaporation chamber 11 evaporates into a gaseous working fluid which then spreads and fills the vapor space 16. The plurality of branch rooms 162 are conducive to provision of sufficient space whereby the gaseous working fluid spreads to the common room 161, enters the vapor segment 24 of the return line 21, and finally reaches the condensation segment 22. Owing to the heat-dissipating unit 100 mounted on the condensation segment 22, the heat is carried away by air such that temperature inside the condensation segment 22 is lower than that inside the evaporation chamber 11; hence, upon its arrival at the condensation segment 22, the gaseous working fluid cools down and condenses into the liquid working fluid in droplets which are then adsorbed to the walls of the fluid slug pipes 29 in the condensation segment 22. As time passed, the resultant liquid working fluid in droplets becomes massive enough to fill fluid slugs 311 defined by the cross sections of the fluid slug pipes 29, respectively. Since the fluid slug pipes 29 each have a smaller diameter than the return line 21, the liquid working fluid can form the fluid slugs. In addition, the continuous flow of the gaseous working fluid from the vapor segment 24 into the condensation segment 22 spontaneously generates a pressure difference under which the fluid slugs 311 move from the condensation segment 22 to the liquid line, enter the evaporation chamber 11, and are finally adsorbed to the wick 14 again. The aforesaid process recurs and thus guides heat out of the object to-cool continuously, thereby performing heat dissipation well.
Therefore, according to the present disclosure, the liquid segment 26 of the return line 21 is divided into the fluid slug pipes 29 with smaller diameters so that the liquid working fluid can form the fluid slugs such that the liquid working fluid can still move and return to the evaporation chamber 11 smoothly under a pressure difference in the return line 21 even in the absence of a capillary force. Furthermore, unlike the prior art, the present disclosure is advantageous in that the liquid segment 26 of the return line 21 is not confronted with problems related to assembly of braided vasa or any other wick, thereby reducing manufacturing costs but enhancing yield.
Referring to FIG. 7, a loop heat pipe 40 with fluid slug pipes in the second preferred embodiment of the present disclosure is substantially identical to its counterpart in the first preferred embodiment of the present disclosure except for its distinguishing technical features described below.
A water storage space 47 is formed between the wick 44 and the casing 42. The water storage space 47 is in communication with the liquid end of the return line. The water storage space 47 is not in communication with the vapor space 46. The purpose of the water storage space 47 is to regulate the amount of the working fluid, for a reason described below. A conventional loop heat pipe requires a liquid segment requires for the return of the liquid working fluid. If most of the working fluid in the evaporation chamber is present in the vapor segment, the condensation segment and the liquid segment of the return line and thus has not yet returned, the working fluid in the evaporation chamber will be too little to work, thereby leading to a state of dry heating. By contrast, the water storage space 47 regulates the amount of the working fluid and thus ensures a constant amount of a working fluid 49 in an evaporation chamber 41, so as to prevent dry heating.
In the second preferred embodiment, a partition element 58 is not extended to a condensation segment 52. Although the liquid working fluid is unable to go from the condensation segment 52 to fluid slug pipes 59 at a liquid segment 56 directly, the liquid working fluid can, when accumulated sufficiently, enter the liquid line and thus reach the fluid slug pipes 59. Understandably, the second preferred embodiment is outperformed slightly by the first preferred embodiment in the formation of the fluid slugs. However, owing to the fluid slug pipes 59, it is still feasible for the liquid working fluid to form the fluid slugs, rendering it easier for the liquid working fluid to return to the evaporation chamber 41.
As inferable from the second preferred embodiment, if in a variant embodiment the partition element 58 is only extended to a half of the length from the liquid segment 56 to the condensation segment 52, the resultant fluid slug pipes 59 will be extended to a half of the length of the condensation segment 52 for certain. Hence, the variant embodiment outperforms the second preferred embodiment but is outperformed by the first preferred embodiment in the formation of the fluid slugs.
The other structures and achievable advantages in the second preferred embodiment are substantially identical to their counterparts in the first preferred embodiment and thus are not described again.
Referring to FIG. 8, a loop heat pipe 60 with fluid slug pipes in the third preferred embodiment of the present disclosure is substantially identical to its counterpart in the first preferred embodiment of the present disclosure except for its distinguishing technical features described below.
A partition element 68 is extended not only to a condensation segment 62 but also to a vapor end 614 of a vapor segment 64.
Therefore, the gaseous working fluid passes the vapor segment 64 and thus directly enters fluid slug pipes 69 of small diameters. At this point in time, the gaseous working fluid has not yet reached the condensation segment 62, and thus the liquid working fluid in the form of droplets produced as a result of condensation of the gaseous working fluid is too little to turn into fluid slugs. Therefore, working efficiency in the third preferred embodiment remains unaffected. However, since a return line 61 in the third preferred embodiment consists of fluid slug pipes, it can be provided in a one-piece manner and thus dispenses with any portion which lacks a partition element. Furthermore, unlike the first preferred embodiment, the third preferred embodiment does not require confirming whether the partition element 68 is extended to a precise point of the condensation segment 62; hence, the third preferred embodiment outperforms the first preferred embodiment in manufacturing cost saving.
The other structures and achievable advantages in the third preferred embodiment are substantially identical to their counterparts in the first preferred embodiment and thus are not described again.
Referring to FIG. 9, a loop heat pipe 70 with fluid slug pipes in the fourth preferred embodiment of the present disclosure is substantially identical to its counterpart in the first preferred embodiment of the present disclosure except for its distinguishing technical features described below.
A return line 71 comprises two tubes 71 a, 71 b. The tube 71 b functions as a liquid segment 76 and a condensation segment 72. The tube 71 a functions as a vapor segment 74. The vapor segment 74 has a smaller diameter than the liquid segment 76 and the condensation segment 72. The tube 71 b functioning as the liquid segment 76 and the condensation segment 72 fits partially around and thus connects to the tube 71 a functioning as the vapor segment 74, thereby achieving internal spatial communication. Therefore, the two tubes 71 a, 71 b are connected to thereby form the return line 71. A partition element is disposed inside the tube 71 b functioning as the liquid segment 76 and the condensation segment 72. No partition element is disposed inside the tube 71 a functioning as the vapor segment 74.
The fourth preferred embodiment of the present disclosure is advantageous in that two different tubes are connected to thereby form the return line 71.
The other structures and achievable advantages in the fourth preferred embodiment are substantially identical to their counterparts in the first preferred embodiment and thus are not described again.
Referring to FIG. 10, a loop heat pipe 80 with fluid slug pipes in the fifth preferred embodiment of the present disclosure is substantially identical to its counterpart in the fourth preferred embodiment of the present disclosure except for its distinguishing technical features described below.
A return line 81 has two tubes 81 a, 81 b. The tube 81 b functions as a liquid segment 86 and a condensation segment 82. The tube 81 a functions as a vapor segment 84. The tube 81 a fits partially around and thus connects to the tube 81 b, so as to achieve internal spatial communication. Since the tube 81 a has a smaller diameter than the tube 81 b, it is necessary to enlarge the terminal segment of the tube 81 a in order for the tube 81 a to fit around and thus connect to the tube 81 b.
The fifth preferred embodiment of the present disclosure is advantageous in that the tube 81 a has a smaller diameter than the tube 81 b but still manages to fit around and connect to the tube 81 b.
The other structures and achievable advantages in the fifth preferred embodiment are substantially identical to their counterparts in the fourth preferred embodiment and thus are not described again.

Claims

What is claimed is:

1. A loop heat pipe with fluid slug pipes, comprising:

an evaporation chamber having a casing and a wick disposed in the casing, the wick not occupying the casing fully so as for a vapor space to be formed between the wick and the casing;

a return line having two ends defined as a vapor end and a liquid end, respectively, the vapor end connecting to the casing and thereby being in communication with the space, and the liquid end connecting to the casing and thereby being in communication with an inside of the casing; and

a working fluid filling the evaporation chamber;

wherein a condensation segment is defined as a predetermined length of a body of the return line, allowing a heat-dissipating unit to be disposed on a surface of the condensation segment, a vapor segment is defined as a portion of the return line, the portion extending from the condensation segment to the vapor end, and a liquid segment is defined as another portion of the return line, the another portion extending from the condensation segment to the liquid end, with at least one partition element disposed in an inside of the liquid segment of the return line to thereby divide the liquid segment of the return line into at least two fluid slug pipes not in communication with each other but in communication with the condensation segment and the casing, wherein the at least two fluid slug pipes each have a smaller diameter than the return line.

2. The loop heat pipe with fluid slug pipes according to claim 1, wherein the at least one partition element extends from the liquid segment to the condensation segment.

3. The loop heat pipe with fluid slug pipes according to claim 2, wherein the at least one partition element extends to the condensation segment lengthwise fully.

4. The loop heat pipe with fluid slug pipes according to claim 1, wherein the at least one partition element extends from the liquid segment to the condensation segment and then to the vapor end of the vapor segment.

5. The loop heat pipe with fluid slug pipes according to claim 1, wherein the return line has two tubes, one of the tubes functions as the liquid segment and the condensation segment, another tube functions as the vapor segment, the vapor segment having a smaller diameter than the liquid segment and the condensation segment, the liquid segment and the condensation segment fit partially around the vapor segment and thereby connect to the vapor segment, thereby achieving internal spatial communication.

6. The loop heat pipe with fluid slug pipes according to claim 1, wherein the return line has two tubes, one of the tubes functions as the liquid segment and the condensation segment, another tube functions as the vapor segment, the vapor segment fitting partially around the liquid segment and the condensation segment, thereby achieving internal spatial communication.

7. The loop heat pipe with fluid slug pipes according to claim 1, wherein the at least one partition element is in a plural number to thereby divide the liquid segment of the return line into a plurality of said fluid slug pipes.

8. The loop heat pipe with fluid slug pipes according to claim 1, wherein a water storage space is formed between the wick and the casing, adapted to be in communication with the liquid end of the return line, and adapted to be not in communication with the vapor space.

9. The loop heat pipe with fluid slug pipes according to claim 1, wherein the vapor space has a common room and a plurality of branch rooms separated by a predetermined distance and each adapted to be in communication with the common room.

10. The loop heat pipe with fluid slug pipes according to claim 1, wherein the wick is made of sintered copper powder.

11. The loop heat pipe with fluid slug pipes according to claim 1, wherein the fluid slug pipes each have a smaller diameter than the vapor segment of the return line.

12. The loop heat pipe with fluid slug pipes according to claim 1, wherein the at least one partition element and the return line are integrally formed.