U.S. patent application number 11/164094 was filed with the patent office on 2006-08-03 for heat pipe with wick structure of screen mesh.
Invention is credited to Ching-Tai Cheng, Chu-Wan Hong, Chang-Ting Lo, Jung-Yuan Wu.
Application Number | 20060169439 11/164094 |
Document ID | / |
Family ID | 36755271 |
Filed Date | 2006-08-03 |
United States Patent
Application |
20060169439 |
Kind Code |
A1 |
Hong; Chu-Wan ; et
al. |
August 3, 2006 |
HEAT PIPE WITH WICK STRUCTURE OF SCREEN MESH
Abstract
A heat pipe (10) includes a hollow pipe body (20) for receiving
a working fluid therein and a screen mesh (30) disposed in the pipe
body. The screen mesh includes at least two layers. One of the two
layers is in the form of a planar layer (50) and the other is in
the form of a wave layer (40). A plurality of flowing channels (48)
is formed by the wave layer. The channels formed by the wave layer
of the screen mesh are capable of reducing the flow resistance for
the condensed fluid to flow back while pores in the screen mesh
provide a relatively large capillary pressure for drawing the
condensed fluid to flow back.
Inventors: |
Hong; Chu-Wan; (Shenzhen,
CN) ; Cheng; Ching-Tai; (Shenzhen, CN) ; Lo;
Chang-Ting; (Shenzhen, CN) ; Wu; Jung-Yuan;
(Shenzhen, CN) |
Correspondence
Address: |
NORTH AMERICA INTELLECTUAL PROPERTY CORPORATION
P.O. BOX 506
MERRIFIELD
VA
22116
US
|
Family ID: |
36755271 |
Appl. No.: |
11/164094 |
Filed: |
November 10, 2005 |
Current U.S.
Class: |
165/104.26 |
Current CPC
Class: |
F28D 15/046
20130101 |
Class at
Publication: |
165/104.26 |
International
Class: |
F28D 15/02 20060101
F28D015/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 28, 2005 |
TW |
094102615 |
Claims
1. A heat pipe comprising: a hollow pipe body for receiving a
working fluid therein; a screen mesh furled and disposed in the
pipe body, the screen mesh comprising at least two layers, one of
the at least two layers is in the form of a planar layer and
another of the at least two layers in the form of a wave layer; and
a plurality of flowing channels being formed by the wave layer for
the working fluid received in the heat pipe to flow.
2. The heat pipe as claimed in claim 1, wherein the wave layer
comprises a horizontal section and a vertical section alternately
arranged along a circumferential direction of pipe body, and each
flowing channel has a trapezoid-shaped cross section.
3. The heat pipe as claimed in claim 1, wherein the wave layer
comprises a plurality of continuous serrations, and each flowing
channel has a triangle-shaped cross section.
4. The heat pipe as claimed in claim 1, wherein the wave layer
comprises a plurality of horizontal sections and a plurality of
serrations each interconnecting two horizontal sections, and the
flowing channels comprises a triangle-shaped first flow channel and
a trapezoid-shaped second flow channel alternately arranged along a
circumferential direction of pipe body.
5. The heat pipe as claimed in claim 1, wherein the wave layer of
the at least two layers is directly attached to the pipe body.
6. The heat pipe as claimed in claim 1, wherein the screen mesh
comprises three layers stacked on each other along a radial
direction of the pipe body.
7. The heat pipe as claimed in claim 6, wherein the three layers
comprise two planar layers and a wave layer sandwiched between the
two planar layers.
8. The heat pipe as claimed in claim 6, wherein the three layers
comprise two wave layers and a planar layer sandwiched between the
two wave layers.
9. The heat pipe as claimed in claim 8, wherein the wave layers
have a pore size different from that of the planar layer.
10. The heat pipe as claimed in claim 8, wherein each layer of the
screen mesh has a pore size different from that of the other
layers.
11. A heat pipe comprising: a pipe body having an inner wall;
working fluid received in the pipe body; a screen mesh rolled and
installed in the pipe body and abutting against the inner wall
thereof, the screen mesh having a plurality of pores therein for
drawing the working fluid from a first section to a second section
the pipe body, the screen mesh forming circumferentially
distributed flowing channels in pipe body, the flowing channels
being larger than the pores in the screen mesh, the flowing
channels extending along a longitudinal direction of the pipe
body.
12. The heat pipe of claim 11, wherein the screen mesh comprises a
wave layer and a planar layer, the wave layer abutting against the
inner wall of the pipe body.
13. The heat pipe of claim 12, wherein the wave layer is
square-wave shaped, and comprises alternate upper and lower
horizontal sections and vertical sections between the horizontal
sections, the upper horizontal sections abutting against the inner
wall of the pipe body, and the vertical sections together with the
inner wall forming the channels.
14. The heat pipe of claim 12, where the wave layer comprises of a
plurality of continuous serrations.
15. The heat pipe of claim 12, wherein the wave layer includes a
plurality of horizontal sections and a plurality of serrations each
interconnecting two horizontal sections, the serrations being
equally spaced from each other and tips thereof abutting the inner
wall of the pipe body, the wave layer forming a plurality of
trapezoid-shaped flowing channels with the inner wall of the pipe
body, and a plurality of triangle-shaped flowing channels with the
planar layer.
16. The heat pipe of claim 11, wherein the screen mesh comprises
two planar layers and a wave layers sandwiched between the two
planar layers, one of the two planar layers abutting against the
inner wall of the pipe body.
17. The heat pipe of claim 11, wherein the screen mesh comprises
two wave layers and a planar layer sandwiched between the two wave
layers, one of the two wave layers abutting against the inner wall
of the pipe body.
18. The heat pipe of claim 17, wherein the two wave layers have a
pore size which is different from that of the planar layer.
19. The heat pipe of claim 17, wherein the two wave layers have
different pore sizes which are different from that of the planar
layer.
20. A heat pipe comprising: a pipe body having an inner wall; a
screen mesh disposed in the pipe body and abutting against the
inner wall of the pipe body, the screen mesh comprising a plurality
of layers stacked on each other along a radial direction of the
pipe body, wherein two neighboring layers have different
configurations with one of which having a wave-like configuration.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to heat pipes, and
more particularly to a heat pipe with a wick structure of screen
mesh.
Description of Related Art
[0002] As electronic industry continues to advance, electronic
components such as central processing units (CPUs), are made to
provide faster operational speeds and greater functional
capabilities. When a CPU operates at a high speed, its temperature
frequently increases greatly. It is desirable to dissipate the heat
generated by the CPU quickly.
[0003] To solve this problem of heat generated by the CPU, a
cooling device is often used to be mounted on top of the CPU to
dissipate heat generated thereby. It is well known that heat
absorbed by fluid having a phase change is ten times more than that
the fluid does not have a phase change; thus, the heat transfer
efficiency by phase change of fluid is better than other
mechanisms, such as heat conduction or heat convection.
Accordingly, a heat pipe has been developed.
[0004] The heat pipe has a hollow pipe body receiving a working
fluid therein and a wick structure disposed on an inner wall of the
pipe body. Generally the heat pipe is divided into an evaporating
section, an adiabatic section and a condensing section along a
longitudinal direction thereof. During operation of the heat pipe,
the working fluid absorbs the heat generated by the CPU or other
electronic device and evaporates into vapor. The vapor moves from
the evaporating section to the condensing section to dissipate the
heat, whereby the vapor cools and condenses at the condensing
section. The condensed working fluid returns to the evaporating
section via a capillary force generated by the wick structure. From
the evaporating section, the fluid is evaporated again to thereby
repeat the heat transfer from the evaporating section to the
condensing section.
[0005] In general, movement of the working fluid depends on the
capillary pressure (force) of the wick structure. Usually the wick
structure has following four configurations: sintered powders,
grooves, fiber and screen mesh. Since the thickness and pore size
of the screen mesh can be easily changed, the screen mesh is widely
used in the heat pipe.
[0006] It is well recognized that the capillary pressure of a
screen mesh increases due to a decrease in the pore size of the
screen mesh. In order to obtain a relatively large capillary
pressure, a mesh screen having a small-sized pore is usually
adopted. However, it is not always the best way to choose a screen
mesh having small-sized pores, because the flow resistance to the
condensed working fluid also increases due to a decrease in the
pore size of the screen mesh. The increased flow resistance reduces
the speed of the condensed working fluid in returning back to the
evaporating section and therefore limits the heat transfer
performance of the heat pipe. As a result, a heat pipe with a
screen mesh that has too large or too small a pore size often
suffers dry-out problem at the evaporating section as the condensed
working fluid cannot be timely sent back to the evaporating section
of the heat pipe.
[0007] Therefore, there is a need for a heat pipe with a screen
mesh which can provide simultaneously a relatively large capillary
pressure and a relatively low flow resistance so as to effectively
and timely bring the condensed working fluid back from the
condensing section to the evaporating section of the heat pipe and
thereby to avoid the undesirable dry-out problem at the evaporating
section.
SUMMARY OF THE INVENTION
[0008] According to a preferred embodiment of the present
invention, a heat pipe comprises a hollow pipe body for receiving a
working fluid therein and a screen mesh disposed in the pipe body.
The screen mesh comprises at least two layers. One of the two
layers is in the form of a planar layer and the other of the two
layers is in the form of a wave layer. The wave layer forms a
plurality of flowing channels for the working fluid to flow from a
condensing section to an evaporating section of the heat pipe. The
channels formed by the wave layer of the screen mesh is capable of
reducing the flow resistance to the condensed fluid to flow back
while pores in the screen mesh are capable of providing a
relatively large capillary pressure for drawing the condensed fluid
to flow back.
[0009] Other advantages and novel features of the present invention
will be drawn from the following detailed description of a
preferred embodiment of the present invention with attached
drawings, in which:
BRIEF DESCRIPTION OF DRAWINGS
[0010] FIG. 1 is a transverse cross-section view of a heat pipe in
accordance with a preferred embodiment of the present
invention;
[0011] FIG. 2 is an isometric, unfurled view of a planar layer of a
mesh screen of the heat pipe of FIG. 1;
[0012] FIG. 3 is an isometric, unfurled view of a wave layer of the
mesh screen of the heat pipe of FIG. 1;
[0013] FIG. 4 is a transverse cross-section view of the heat pipe
in accordance with a second embodiment of the present
invention;
[0014] FIG. 5 is an isometric, unfurled view of the wave layer of
the mesh screen of the heat pipe of FIG. 4;
[0015] FIG. 6 is a transverse cross-section view of the heat pipe
in accordance with a third embodiment of the present invention;
[0016] FIG. 7 is an isometric, unfurled view of the wave layer of
the mesh screen of the heat pipe of FIG. 6;
[0017] FIG. 8 is a transverse cross-section view of the heat pipe
in accordance with a fourth embodiment of the present
invention;
[0018] FIG. 9 is a transverse cross-section view of the heat pipe
in accordance with a fifth embodiment of the present invention,
and
[0019] FIG. 10 is a transverse cross-section view of the heat pipe
in accordance with a sixth embodiment of the present invention.
DETAILED DESCRIPTION
[0020] Referring to FIG. 1, a heat pipe 10 according to a preferred
embodiment of the present invention comprises a hollow pipe body 20
and a screen mesh 30 disposed on an inner wall 22 of the pipe body
20. The heat pipe 10 comprises an evaporating section and a
condensing section at respective opposite ends thereof, and an
adiabatic section located between the evaporating section and the
condensing section. The heat pipe 10 is vacuumed and two ends of
the heat pipe 10 are sealed.
[0021] The pipe body 20 is made of high heat conductivity material
such as copper or copper alloys. The screen mesh 30 has a plurality
of pores and is saturated with a working fluid (not shown). The
working fluid may be water, alcohol or other material having a low
boiling point; thus, the working fluid can easily evaporate to
vapor during operation when the evaporating section receives heat
from a heat-generating electronic device, such as a CPU.
[0022] The screen mesh 30 comprises a wave layer 40 and a planar
layer 50 arranged along circumferential and axial directions of the
pipe body 20. The wave layer 40 is staked on the inner wall 22 of
the pipe body 20 while the planar layer 50 is stacked on the wave
layer 40 along a radial direction of the heat pipe 10 from a center
to a periphery thereof. The wave layer 40 is directly attached to
the inner wall 22 of the pipe body 20. The planar layer 50 is
disposed on an inner side of the wave layer 40.
[0023] As best seen in FIG. 2, which shows the planar layer 50 in
an unfurled state, outer surfaces of the planar layer 50 are
flat.
[0024] FIG. 3 shows the wave layer 40 in an unfurled state. The
wave layer 40 is square-wave shaped and comprises alternate upper
and lower horizontal sections 42 and vertical sections 46 between
the horizontal sections 42. When the wave layer 40 is rolled and
inserted into the pipe body 20, the upper horizontal sections 42
abut against the inner wall 22 of the pipe body 20. Thus, a flow
channel 48 is formed between two adjacent vertical sections 46 of
the wave layer 40 of the screen mesh 30 and the inner wall 22. Each
flow channel 48 extends along the longitudinal direction and entire
length of the pipe body 20, and has a trapezoid-shaped cross
section (as shown in FIG. 1).
[0025] During operation of the heat pipe 10, when the working fluid
saturated in the screen mesh 30 at the evaporating section of the
heat pipe 10 evaporates to vapor due to heat absorbed from the CPU,
the vapor moves toward the condensing section of the heat pipe 10
due to the difference of vapor pressure to perform heat transport.
The vapor then cools and condenses at the condensing section to
perform heat dissipation. In this case, the condensed working fluid
is absorbed into the screen mesh 30 at the condensing section, and
then returns to the evaporating section through the screen mesh 30.
The pores of the screen mesh 30 can provide a relatively large
capillary pressure to the working fluid while the flow channels 48
can provide a relatively small flow resistance to the working
fluid. The screen mesh 30 accordingly can increase the speed of the
condensed working fluid in returning back to the evaporating
section and therefore promotes the heat transfer performance of the
heat pipe 10. As a result, a dry-out problem of the heat pipe 10
can be avoided.
[0026] Referring to FIGS. 4-5, they illustrate the heat pipe 410 in
accordance with a second embodiment of the present invention.
Similar to the first embodiment, the heat pipe 410 also comprises a
pipe body 20 and a screen mesh 430 arranged in the pipe body 20.
The screen mesh 430 comprises a wave layer 440 directly attached to
the pipe body 20 and a planar layer 50 disposed on an inside of the
wave layer 440. Flow channels 448 are formed by the wave layer 440
between it and the pipe body 20 and between it and the planar layer
50. The difference of the second embodiment over the first
embodiment is that the wave layer 440 is consisted of a plurality
of continuous serrations as viewed from the transverse
cross-sectional view of the heat pipe 410. Thus, each flow channel
448 has a triangle-shaped cross section. Upper tips of the
serrations of the wave layer 440 abut against the inner wall of the
pipe body 20, while lower tips thereof abut against the planar
layer 50.
[0027] FIGS. 6-7 illustrate the heat pipe 610 in accordance with a
third embodiment of the present invention. Except for the screen
mesh 630 and flow channels 648, 648', other parts of the heat pipe
610 in accordance with the third embodiment are substantially the
same as the heat pipe 410 of the previous embodiment. The screen
mesh 630 also comprises a wave layer 640. The wave layer 640
comprises a plurality of horizontal sections 642 and a plurality of
serrate sections 646 each interconnecting two neighboring
horizontal sections 642. The serrate sections 646 are equally
spaced from each other. When the screen mesh 630 is rolled and
installed in the pipe body 20, the wave layer 640 defines
triangle-shaped first flow channels 648 and trapezoid-shaped second
flow channels 648' alternately arranged along the circumferential
direction of pipe body 20. Tips of the serrate sections 646 abut
against the inner wall of the pipe body 20, and the horizontal
sections 642 abut against planar layer 50.
[0028] It is to be understood that the screen mesh 30, 430, 630 is
used to provide capillary pressure to force the working fluid
returning back to the evaporating section. The screen mesh 30, 430,
630 may be in the form of a multi-layer structure more than two
layers. Referring to FIG. 8, the screen mesh 830 has three layers
stacked on each other along the radial direction of the pipe body
20. The three layers comprise a wave layer 40 and two planar layers
50 sandwiching the wave layer 40 therebetween. FIG. 9 shows a
screen mesh 930 also having three layers stacked on each other
along the radial direction of the pipe body 20. These three layers
comprise a planar layer 50 and two wave layers 40 sandwiching the
planar layer 50 therebetween.
[0029] FIG. 10 also illustrates the heat pipe having a screen mesh
130 comprising three layers. The three layers comprise a planar
layer 150 and two wave layers 140, 140' sandwiching the planar
layer 150 therebetween. The difference of this embodiment over that
of FIG. 9 is that the planar layer 150 has a pore size different
from that of the wave layers 140, 140'. In this embodiment, the
wave layers 140, 140' have the same pore size. Although it is not
shown in the drawings, it is apparent to those skilled in the art
that the embodiment of FIG. 10 can be further modified that the two
wave layers 140, 140' have different pore sizes, whereby the heat
pipe can be used in an environment with a broader range of
parameters regarding heat-dissipation requirement.
[0030] It is understood that the invention may be embodied in other
forms without departing from the spirit thereof. Thus, the present
example and embodiment is to be considered in all respects as
illustrative and not restrictive, and the invention is not to be
limited to the details given herein.
* * * * *