U.S. patent application number 12/904277 was filed with the patent office on 2012-03-15 for method for manufacturing two-phase flow heat sink.
This patent application is currently assigned to NATIONAL YUNLIN UNIVERSITY OF SCIENCE & TECHNOLOGY. Invention is credited to SHIH-YING CHANG, WEI-SHEN CHEN, JI-RONG FU, YEN-HUAN LEI.
Application Number | 20120060371 12/904277 |
Document ID | / |
Family ID | 45805272 |
Filed Date | 2012-03-15 |
United States Patent
Application |
20120060371 |
Kind Code |
A1 |
CHANG; SHIH-YING ; et
al. |
March 15, 2012 |
METHOD FOR MANUFACTURING TWO-PHASE FLOW HEAT SINK
Abstract
The present invention relates to a method for manufacturing a
two-phase flow heat sink. The two-phase flow heat sink comprises an
evaporation chamber and a capillary layer. The material of the
capillary layer, which has at least a porous structure, is cooled
and disposed on the inner side of the evaporation chamber from a
melted state. The method first sprays the thermally melted material
of the capillary layer on the substrate of the evaporation chamber
for forming the capillary layer on the substrate. Because the
capillary layer is sprayed on the substrate of the evaporation
chamber, the capillary layer is distributed irregularly on the
substrate and forming irregularly distributed holes. Thereby, the
flowing space for fluids in the evaporation chamber is increased,
and hence enhancing the heat transfer efficiency of the heat
sink.
Inventors: |
CHANG; SHIH-YING; (YUNLIN,
TW) ; LEI; YEN-HUAN; (YUNLIN, TW) ; CHEN;
WEI-SHEN; (YUNLIN, TW) ; FU; JI-RONG; (YUNLIN,
TW) |
Assignee: |
NATIONAL YUNLIN UNIVERSITY OF
SCIENCE & TECHNOLOGY
YUNLIN
TW
|
Family ID: |
45805272 |
Appl. No.: |
12/904277 |
Filed: |
October 14, 2010 |
Current U.S.
Class: |
29/890.032 |
Current CPC
Class: |
F28D 15/046 20130101;
F28D 15/0283 20130101; Y10T 29/49353 20150115; F28D 15/0233
20130101 |
Class at
Publication: |
29/890.032 |
International
Class: |
B21D 53/02 20060101
B21D053/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 14, 2010 |
TW |
099131029 |
Claims
1. A method for manufacturing a two-phase flow heat sink,
comprising steps of: providing a substrate; spraying a capillary
layer on a surface of said substrate using a melting injection
process, and said capillary layer having at least a porous
structure; and forming a two-phase flow heat sink according to said
substrate and said capillary layer.
2. The method for manufacturing a two-phase flow heat sink of claim
1, and further comprising steps of: vacuuming said two-phase flow
heat sink; filling a working fluid to said two-phase flow heat
sink; and sealing said two-phase flow heat sink.
3. The method for manufacturing a two-phase flow heat sink of claim
2, and further comprising a step of bonding said capillary layer
and said substrate after said step of spraying said capillary layer
on said surface of said substrate using said melting injection
process.
4. The method for manufacturing a two-phase flow heat sink of claim
1, wherein said melting injection process includes plasma melting
injection, arc melting injection, fire melting injection, and
high-speed fire melting injection.
5. The method for manufacturing a two-phase flow heat sink of claim
1, wherein said porous structure is a net structure.
6. The method for manufacturing a two-phase flow heat sink of claim
1, wherein said porous structure is a fiber-bundle structure.
7. The method for manufacturing a two-phase flow heat sink of claim
1, wherein said porous structure includes a plurality of
trenches.
8. The method for manufacturing a two-phase flow heat sink of claim
1, wherein said porous structure includes a plurality of
powders.
9. The method for manufacturing a two-phase flow heat sink of claim
1, wherein said capillary layer is a trench-shaped, needle-shaped,
or grid-shaped structure.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to a method for
manufacturing a heat transfer apparatus, and particularly to a
method for manufacturing a two-phase flow heat sink.
BACKGROUND OF THE INVENTION
[0002] With the development of electronic industry, the operating
speed and overall performance of electronic devices increase
continuously. However, as the performance of electronic devices
enhances, power consumption increases accordingly, which brings
about heat dissipation problems. Heat pipes, such as fins with heat
pipes and heat-sinking module, are extensively applied to heat
sinking of electronic devices owing to their small size, capability
of transferring a substantial amount of heat using latent heat,
uniform temperature distribution, simple structure, light weight,
nature of requiring no external force, long lifetime, low thermal
resistivity, and capability of long-range heat transfer. The
working principle of heat pipes is to use phase changes between gas
and liquid phases while the fluids filled in the heat pipes absorb
and release heat for transferring heat. In general, heat pipes can
be classified as trench type, sintering type, fiber type, and net
type. The capillary structure in a trench-type heat pipe is
composed by a plurality of trenches. The capillary structure of a
sintering-type heat pipe is formed by sintering metal powders. The
capillary structure of a fiber-type heat pipe is texturized by
fiber bundles. The capillary structure of a net-type heat pipe is
formed by weaving a plurality of metal threads.
[0003] The advantages of heat pipes include simple structure and
operations. Besides, they need no external force to do work on the
working fluids in heat pipes for achieving heat transfer and
circulation. They use latent heat in the working fluids to produce
phase changes and hence transferring heat. Because the temperature
difference is smaller when the working fluids absorb latent heat
and evaporate into the gas phase and when they release latent heat
and condense, heat pipes can have a large thermal conductivity in
the operating condition of a smaller temperature difference, which
means they can substantially conduct the heat produced by
electronic devices. When the temperature difference is within the
operating range, the thermal conducting capability of heat pipes
can exceed tens of times of the thermal conducting capability of
high thermal conducting materials such as copper. The gas-phase
working fluids release vaporization latent heat while condensing at
the cooling end of heat pipes. The vaporization latent heat passes
through the capillary structure and pipe walls in heat pipes to
radiators external to heat pipes. The reason why the working fluids
evaporate to gas phase when heated is that the working fluids at
the heating end form various radiuses of curvature in the capillary
structure and thus making the capillary structure produce
capillarity, which draws condensed liquids from the cooling end
back to the heating end and hence completing a working cycle.
Thereby, when the capillarity produced in the capillary structure
is greater than the total pressure in the heat pipes, the heat
pipes can work normally.
[0004] In addition, the thermal conducting efficiency of heat pipes
is based on coordination between the capillary structure and
working fluids. In particular, the capillary structure provides
capillarity for liquid-phase working fluids, which can thereby flow
to the cooling end of heat pipes. Then the gas-phase working fluids
can release the latent heat of evaporation and condense to liquid
phase. The liquid-phase working fluids are recycled to the heating
end via capillarity to absorb the latent heat of evaporation
conducted from the external of heat pipes to the internal. By this
way, the liquid-phase working fluids are changed to gas-phase
working fluids, which flow to the cooling end and condense to
liquid phase again. Accordingly, the strength of capillarity
determines the flow rate of liquid-phase working fluids, and hence
further influences the heat-conducting efficiency, namely,
heat-sinking efficiency, of heat pipes. This is what manufacturers
of the field stress and propose to improve for the hope of
enhancing capillarity of the capillary structure and thus
increasing the flow rate of liquid-phase working fluids.
[0005] Most prior art adopts sintering metal powders on the inner
sidewall of heat pipes to form porous capillary structures. The
capillary structures formed by metal powders can provide better
capillarity for liquid-phase working fluids by means of smaller
holes and hence speeding up the flow rate of liquid-phase working
fluids flowing back to the cooling end. Nonetheless, bubbles in the
capillary structures formed by this way are uneasy to exhaust,
which brings flow resistance to gas- and liquid-phase working
fluids and hence reducing the flow rate of the working fluids
cycling in heat pipes. As a result, the heat-conducting efficiency
of heat pipes is reduced. The capillary structure of a trench-type
heat pipe is formed by etching or machining pipe parts attached to
the inner sidewall, and thereby having better heat-conducting
efficiency. However, the holes in the capillary structures of
trench-type heat pipes are greater than those in net-type or
sintering-type heat pipes. In addition, the amount of the holes in
the capillary structures of trench-type heat pipes is fewer than
that in net-type or sintering-type heat pipes. Therefore, the
capillarity of trench-type heat pipes is inferior to net- and
sintering-type heat pipes.
[0006] Moreover, the capillary structures of net-type heat pipes
have superior permeability, providing better capillarity and hence
providing a faster flow rate for liquid-phase working fluids.
However, the contact areas between the capillary structures and the
inner sidewall of net-type heat pipes are smaller than those of
sintering-type heat pipes. Therefore, the heat-conducting
efficiency of the inner sidewall of the capillary structures of
net-type heat pipes is inferior to that of sintering- and
trench-type heat pipes. Thereby, although the heat pipe apparatuses
according to the prior art solve the problem of heat conduction,
they don't provide solid technique, such as enhancing the flow rate
and convection of liquid-phase working fluids, for enhancing
heat-conducting efficiency.
[0007] Accordingly, the present invention provides a method for
manufacturing a two-phase flow heat sink, which uses a porous
capillary structure for enhancing the conversion efficiency of
working fluids from the liquid phase to the gas phase. In addition,
the capillary structure according to the present invention has a
greater moistened area, which facilitates producing convection when
working fluids are changing from the liquid phase to the gas phase.
Thereby, gas-phase working fluids and liquid-phase working fluids
can convect in an evaporation chamber with ease.
SUMMARY
[0008] An objective of the present invention is to provide a method
for manufacturing a two-phase flow heat sink, which sprays a
capillary layer on a substrate of an evaporation chamber. The
capillary layer is thermally bonded to the substrate of the
evaporation chamber and hence increasing flow channels in the
evaporation chamber.
[0009] Another objective of the present invention is to provide a
method for manufacturing a two-phase flow heat sink, which sprays
the capillary layer using a melting injection process for forming a
porous structure rapidly.
[0010] The present invention provides a method for manufacturing a
two-phase flow heat sink, which sprays a capillary layer on a
substrate of an evaporation chamber using the melting injection
process, and condensing a porous structure during the cooling
process of the capillary layer. Then the two-phase flow heat sink
is formed according to the substrate of the evaporation chamber and
the capillary layer. Thereby, the two-phase flow heat sink
according to the present invention comprises the evaporation
chamber and the capillary layer. The capillary layer is disposed at
the inner side of the evaporation chamber and has at least a porous
structure. The two-phase flow heat sink according to the present
invention adopts the melting injection process for increasing flow
channels of fluids inside the two-phase flow heat sink.
Consequently, the flow rate of the fluids is increased, and hence
enhancing the heat transfer efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1A shows a cross-sectional view of a two-phase flow
heat sink according to a preferred embodiment of the present
invention;
[0012] FIG. 1B shows a cross-sectional view of a two-phase flow
heat sink according to another preferred embodiment of the present
invention;
[0013] FIG. 1C shows a cross-sectional view of a two-phase flow
heat sink according to another preferred embodiment of the present
invention;
[0014] FIG. 1D shows a cross-sectional view of a two-phase flow
heat sink according to another preferred embodiment of the present
invention;
[0015] FIG. 1E shows a cross-sectional view of a two-phase flow
heat sink according to another preferred embodiment of the present
invention;
[0016] FIG. 2 shows a flowchart according to a preferred embodiment
of the present invention;
[0017] FIG. 3A shows a structural schematic diagram of a two-phase
flow heat sink according to another preferred embodiment of the
present invention;
[0018] FIG. 3B shows a partial enlarged view of FIG. 3A;
[0019] FIG. 4A shows a structural schematic diagram of a two-phase
flow heat sink according to another preferred embodiment of the
present invention;
[0020] FIG. 4B shows a partial enlarged view of FIG. 4A;
[0021] FIG. 5A shows a structural schematic diagram of a two-phase
flow heat sink according to another preferred embodiment of the
present invention; and
[0022] FIG. 5B shows a partial enlarged view of FIG. 5A.
DETAILED DESCRIPTION
[0023] In order to make the structure and characteristics as well
as the effectiveness of the present invention to be further
understood and recognized, the detailed description of the present
invention is provided as follows along with embodiments and
accompanying figures.
[0024] FIG. 1A shows a cross-sectional view of a two-phase flow
heat sink according to a preferred embodiment of the present
invention. As shown in the figure, the two-phase flow heat sink 10
according to the present invention comprises an evaporation chamber
12 and a first capillary layer 16. The first capillary layer 16 is
disposed on the inner side of the evaporation chamber 12, and has
at least a porous stricture (not shown in the figure). The material
of the evaporation chamber 12 is a metal material, such as copper
(Cu) or aluminum (Al), or a nonmetal material, such as silicon
oxide or polymers, with superior heat conductivity. Besides, the
two-phase flow heat sink 10 according to the present invention
further comprises a working fluid 18 sealed in the evaporation
chamber 12. According to the present embodiment, the working fluid
18 is in the gas phase. Because the working fluid 18 is changed
from the liquid phase (not shown in the figure) to the gas-phase
working fluid 18 by absorbing the latent heat of evaporation. and
the working fluid 18 flows on an inner surface of the first
capillary layer 16 and flows in the first capillary layer 16 after
changing to the liquid phase by releasing heat, the liquid-phase
working fluid filled in the evaporation chamber 12 is generally a
liquid substance, such as water, ethanol, and acetone, with high
heat of evaporation, good fluidity, and low boiling point.
[0025] As shown in FIG. 1B, the porous structure 164 according to
the present invention is net structured. As shown in FIG. 1C, the
porous structure 166 according to the present invention is fiber
bundles. As shown in FIG. 1D, the porous structure 168 according to
the present invention is trenches. As shown in FIG. 1E, the porous
structure 170 according to the present invention is powders.
Thereby, the porous structure according to the present invention
can be nets, fiber bundles, trenches, or powders. The porous
structure 164 is formed by weaving a plurality of thin threads. The
material of the plurality of thin threads includes copper (Cu),
aluminum (Al), or stainless steel. The porous structure 166 can be
a structure formed by fiber bundles chosen of the group consisting
of metal fiber bundles, carbon fiber bundles, glass fiber bundles,
and ceramic fiber bundles. The porous structure 168 is formed by
cutting or etching. The material of the porous structure 170 is
chosen from the group consisting of copper (Cu), aluminum (Al),
zinc (Zn), tin (Sn), nickel (Ni), gold (Au), silver (Ag), silicon
oxide, and aluminum oxide. In addition to round tube, the shape of
the two-phase flow heat sink 10 according to the present invention
can be a plate for attaching to electronic devices, such as
flat-panel displays, various processors, and circuit boards, with a
flat appearance.
[0026] FIG. 2 shows a flowchart according to a preferred embodiment
of the present invention. As shown in the figure, the method for
manufacturing a two-phase flow heat sink 10 according to the
present invention comprises steps of: [0027] Step S10: Providing a
substrate; [0028] Step S20: Spraying a capillary layer on a surface
of the substrate; [0029] Step S30: Thermally bonding the capillary
layer and the substrate; [0030] Step S40: Forming a two-phase flow
heat sink according to the substrate and the capillary layer;
[0031] Step S50: Vacuuming the two-phase flow heat sink; [0032]
Step S60: Filling a working fluid to the two-phase flow heat sink;
and [0033] Step S70: Sealing the two-phase flow heat sink.
[0034] In the step S10, the substrate is provided for the
evaporation chamber 12. Because the evaporation chamber 12 of the
two-phase flow heat sink 10 needs sufficient thermal conductivity
and low thermal resistance, a preferred choice of the substrate is
oxygen-free copper. In the step S20, the melting injection process
is used for spraying the material of the first capillary layer 16
onto the substrate of the evaporation chamber 12. Because the
melting injection process adopts electricity or thermal power to
melt the material of the first capillary layer 16 and injects the
melted material to the processing surface, the melted material of
the first capillary layer 16 will be distributed irregularly on the
surface of the substrate. Next, in the step S30, cooled by external
air, the material of the first capillary layer 16 condenses on the
surface of the substrate. The melting injection process adopts
techniques including plasma melting injection, arc melting
injection, fire melting injection, and high-speed fire melting
injection. In the step S40, The substrate of the evaporation
chamber 12 is rolled to form the evaporation chamber 12, and
thereby the evaporation chamber 12 and the first capillary layer 16
form the two-phase flow heat sink. The evaporation chamber 12 is
located at the outer most side, while the capillary layer 16 is in
the inner most. In the step S50, the two-phase flow heat sink 10 is
vacuumed. In other words, the evaporation chamber 12 is in the
vacuum condition. In the step S60, guide the working fluid of the
two-phase heat sink into the evaporation chamber 12. Finally, in
the step S70, seal the evaporation chamber 12.
[0035] The present invention adopts the melting injection process
to form the capillary layer on the substrate of the evaporation
chamber 12. Thereby, the number of flow channels of the
liquid-phase working fluid in the evaporation chamber 12 is
increased, and hence increasing capillarity as well as the flow
rate of the liquid-phase working fluid in the evaporation chamber
12. Consequently, the speed of the liquid-phase working fluid
changing to the gas-phase working fluid 18 by absorbing the latent
heat of evaporation is increased, speeding up the flow rate of the
gas-phase working fluid 18. Accordingly, the heat transfer
efficiency of the two-phase flow heat sink 10 is enhanced as a
result of faster cycles of phase changes between gas and liquid
phases therein. In addition. the capillary layer 16 formed by the
melting injection process has a greater moistened area,
facilitating convection of the liquid- and gas-phase working fluids
in the two-phase flow heat sink 10.
[0036] Moreover, the structure of the substrate of the evaporation
chamber 12 according to the present invention can be a
trench-shaped, needle-shaped, or grid-shaped structure, as shown in
FIGS. 3A, 4A, and 5A. Because the capillary layer is disposed
according to the shape of the substrate of the evaporation chamber
12, the capillary layer will be a trench-shaped, needle-shaped, or
grid-shaped structure. As shown in FIG. 3A, a second capillary
layer 20 is disposed on a trench-shaped substrate 124. In FIG. 3B,
the second capillary layer 20 forms a trench-shaped structure
following the shape of the trench-shaped substrate 124. Thereby,
the two-phase flow heat sink 10 can use the trench-shaped structure
to enhance the speed of changing the gas-phase working fluid 18 to
the liquid phase. The difference between FIG. 3A and FIG. 4A is
that the second capillary layer 20 according to FIG. 3A is disposed
on the trench-shaped substrate 124 and a third capillary layer 22
according to FIG. 4A is disposed on a needle-shaped substrate 126.
Besides, as shown in FIG. 4B, the third capillary structure 22
forms a needle-shape structure following to the shape of the
needle-shaped substrate 126. Thereby, the present invention can use
the third capillary layer 22 of the needle-shaped structure to
increase the contact areas of the gas-phase working fluid 18. The
difference between FIG. 4A and FIG. 5A is that the third capillary
layer 22 according to FIG. 4A is disposed in the needle-shaped
substrate 126, and a fourth capillary layer 24 according to FIG. 5A
is disposed on a grid-shaped substrate 128 and thus forming a
grid-shaped structure following the grid-shaped substrate 128.
Thereby, the contact areas of the gas-phase working fluid 18 are
increased, and hence increasing the conversion efficiency of the
gas-phase working fluid 18 to the liquid phase. Furthermore, the
capillary layers described above. including the first, second,
third, and fourth capillary layers 16, 20, 22, 24, can have
multiple holes for enhancing circulation of two-phase flow, which
means increasing the conversion efficiency of the liquid-phase
working fluid to the gas-phase working fluid 18.
[0037] To sum up, the present invention provides a method for
manufacturing a two-phase flow heat sink, which uses the melting
injection process to spray the material of capillary layer to the
substrate of the evaporation chamber. The capillary layer is
arranged irregularly on the substrate of the evaporation chamber
owing to the influence of spraying and thus increasing multiple
holes therein as the flow channels of the liquid-phase working
fluid. Thereby, the flow rate the liquid-phase working fluid is
increased. The present invention can increase the number of
multiple holes in the heat sink, and hence enhancing the
circulation effect of two-phase flow.
[0038] Accordingly, the present invention conforms to the legal
requirements owing to its novelty, nonobviousness, and utility.
However, the foregoing description is only embodiments of the
present invention, not used to limit the scope and range of the
present invention. Those equivalent changes or modifications made
according to the shape, structure, feature, or spirit described in
the claims of the present invention are included in the appended
claims of the present invention.
* * * * *