U.S. patent application number 14/349034 was filed with the patent office on 2015-02-05 for flat plate cooling device and method for using the same.
This patent application is currently assigned to NEC CORPORATION. The applicant listed for this patent is Masaki Chiba, Kenichi Inaba, Arihiro Matsunaga, Hitoshi Sakamoto, Minoru Yoshikawa. Invention is credited to Masaki Chiba, Kenichi Inaba, Arihiro Matsunaga, Hitoshi Sakamoto, Minoru Yoshikawa.
Application Number | 20150034288 14/349034 |
Document ID | / |
Family ID | 48043743 |
Filed Date | 2015-02-05 |
United States Patent
Application |
20150034288 |
Kind Code |
A1 |
Matsunaga; Arihiro ; et
al. |
February 5, 2015 |
Flat Plate Cooling Device and Method for Using the Same
Abstract
In a cooling device using an ebullient cooling system, a cooling
device becomes larger when a degree of freedom of the arrangement
in installing it in electronic equipment is increased, and that it
is impossible to obtain a sufficient degree of freedom of the
arrangement, therefore, a flat plate cooling device according to an
exemplary aspect of the invention includes a plate-like container
including a first flat plate and a second flat plate opposite to
the first flat plate; a refrigerant enclosed in the plate-like
container; and a guiding wall unit connecting the first flat plate
to the second flat plate and controlling a flow of the refrigerant
in the plate-like container; wherein the plate-like container
includes a heat receiving area which is thermally connected to a
heating element disposed on at least one of the first flat plate
and the second flat plate; and the guiding wall unit includes a
pair of guiding walls, and the guiding walls are disposed on
opposite sides of the heat receiving area.
Inventors: |
Matsunaga; Arihiro; (Tokyo,
JP) ; Sakamoto; Hitoshi; (Tokyo, JP) ;
Yoshikawa; Minoru; (Tokyo, JP) ; Chiba; Masaki;
(Tokyo, JP) ; Inaba; Kenichi; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Matsunaga; Arihiro
Sakamoto; Hitoshi
Yoshikawa; Minoru
Chiba; Masaki
Inaba; Kenichi |
Tokyo
Tokyo
Tokyo
Tokyo
Tokyo |
|
JP
JP
JP
JP
JP |
|
|
Assignee: |
NEC CORPORATION
Tokyo
JP
|
Family ID: |
48043743 |
Appl. No.: |
14/349034 |
Filed: |
September 26, 2012 |
PCT Filed: |
September 26, 2012 |
PCT NO: |
PCT/JP2012/075575 |
371 Date: |
April 1, 2014 |
Current U.S.
Class: |
165/170 |
Current CPC
Class: |
F28F 3/12 20130101; H01L
2924/0002 20130101; H01L 23/427 20130101; H01L 2924/00 20130101;
F28D 2015/0216 20130101; H01L 2924/0002 20130101; F28D 15/0233
20130101 |
Class at
Publication: |
165/170 |
International
Class: |
F28F 3/12 20060101
F28F003/12 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 4, 2011 |
JP |
2011-219887 |
Claims
1. A flat plate cooling device, comprising: a plate-like container
comprising a first flat plate and a second flat plate opposite to
the first flat plate; a refrigerant enclosed in the plate-like
container; and a guiding wall unit connecting the first flat plate
to the second flat plate and controlling a flow of the refrigerant
in the plate-like container; wherein the plate-like container
comprises a heat receiving area which is thermally connected to a
heating element disposed on at least one of the first flat plate
and the second flat plate; and the guiding wall unit comprises a
pair of guiding walls, and the guiding walls are disposed on
opposite sides of the heat receiving area.
2. The flat plate cooling device according to claim 1, wherein an
interval between the pair of guiding walls is equal to or larger
than the width of the heat receiving area and not larger than the
outer perimeter of the heat receiving area.
3. The flat plate cooling device according to claim 1, wherein the
guiding walls are disposed extending parallel to one side in a
longitudinal direction of the plate-like container.
4. The flat plate cooling device according to claim 1, wherein the
guiding walls are disposed inclined with respect to a straight line
parallel to one side in a longitudinal direction of the plate-like
container.
5. The flat plate cooling device according to claim 4, wherein the
pair of guiding walls is disposed symmetrically with respect to the
straight line parallel to one side in a longitudinal direction of
the plate-like container.
6. The flat plate cooling device according to claim 1, wherein a
vapor-liquid interface of the refrigerant is located higher than
the lower limit of the heat receiving area in the vertical
direction.
7. The flat plate cooling device according to claim 1, wherein the
heat receiving area is disposed near the center of one side in a
longitudinal direction of the plate-like container.
8. The flat plate cooling device according to claim 1, wherein the
plate-like container comprises a heat radiation area which is
thermally connected to a heat radiating unit disposed on at least
one of the first flat plate and the second flat plate; and the heat
radiation area is disposed uniformly in the plate-like
container.
9. A method for using a flat plate cooling device, comprising the
steps of: using the flat plate cooling device according to claim 1
switching between a first arrangement state where a straight line
parallel to one side in a longitudinal direction of the plate-like
container is parallel to the vertical direction and a second
arrangement state where to be disposed upside down in the vertical
direction inversely with the first arrangement state.
10. A method for using a flat plate cooling device, comprising the
steps of: using the flat plate cooling device according to claim 4
switching between a first arrangement state where a straight line
parallel to one side in a longitudinal direction of the plate-like
container is parallel to the vertical direction and a third
arrangement state where a straight line parallel to one side in a
longitudinal direction of the plate-like container is perpendicular
to the vertical direction.
11. The flat plate cooling device according to claim 3, wherein a
vapor-liquid interface of the refrigerant is located higher than
the lower limit of the heat receiving area in the vertical
direction.
12. The flat plate cooling device according to claim 3, wherein the
heat receiving area is disposed near the center of one side in a
longitudinal direction of the plate-like container.
13. The flat plate cooling device according to claim 3, wherein the
plate-like container comprises a heat radiation area which is
thermally connected to a heat radiating unit disposed on at least
one of the first flat plate and the second flat plate; and the heat
radiation area is disposed uniformly in the plate-like
container.
14. A method for using a flat plate cooling device, comprising the
steps of: using the flat plate cooling device according to claim 3
switching between a first arrangement state where a straight line
parallel to one side in a longitudinal direction of the plate-like
container is parallel to the vertical direction and a second
arrangement state where to be disposed upside down in the vertical
direction inversely with the first arrangement state.
15. The flat plate cooling device according to claim 4, wherein a
vapor-liquid interface of the refrigerant is located higher than
the lower limit of the heat receiving area in the vertical
direction.
16. The flat plate cooling device according to claim 4, wherein the
heat receiving area is disposed near the center of one side in a
longitudinal direction of the plate-like container.
17. The flat plate cooling device according to claim 4, wherein the
plate-like container comprises a heat radiation area which is
thermally connected to a heat radiating unit disposed on at least
one of the first flat plate and the second flat plate; and the heat
radiation area is disposed uniformly in the plate-like
container.
18. A method for using a flat plate cooling device, comprising the
steps of: using the flat plate cooling device according to claim 4
switching between a first arrangement state where a straight line
parallel to one side in a longitudinal direction of the plate-like
container is parallel to the vertical direction and a second
arrangement state where to be disposed upside down in the vertical
direction inversely with the first arrangement state.
19. A method for using a flat plate cooling device, comprising the
steps of: using the flat plate cooling device according to claim 5
switching between a first arrangement state where a straight line
parallel to one side in a longitudinal direction of the plate-like
container is parallel to the vertical direction and a third
arrangement state where a straight line parallel to one side in a
longitudinal direction of the plate-like container is perpendicular
to the vertical direction.
Description
TECHNICAL FIELD
[0001] The present invention relates to cooling devices for
semiconductor devices and electronic equipment and, in particular,
to a flat plate cooling device and a method for using the same
employing an ebullient cooling system in which heat transport and
heat radiation are performed by a cycle of vaporization and
condensation of a refrigerant.
BACKGROUND ART
[0002] In recent years, with the progress of high performance and
high functionality in semiconductor devices, electronic equipment
and the like, the amount of heat generation from them has also been
increasing. On the other hand, the miniaturization of semiconductor
devices and electronic equipment has been advancing due to the
popularization of portable devices. Because of such background, a
cooling device with high efficiency and a small size has been
required. The cooling device using an ebullient cooling system in
which heat transport and heat radiation are performed by a cycle of
vaporization and condensation of a refrigerant does not require any
driving unit such as a pump. It is therefore suitable for
miniaturization, and accordingly it has been expected as a cooling
device for semiconductor devices, electronic equipment and the
like.
[0003] An example of the cooling device using the ebullient cooling
system (hereinafter, also denoted as an ebullient cooling device)
is described in patent literature 1. FIG. 9A and FIG. 9B are
cross-sectional views showing the configuration of a related
ebullient cooling device 500 described in patent literature 1. The
related ebullient cooling device 500 is composed of a coolant tub
510 and a heat dissipation unit 520 and cools heating elements 530
and 531 such as semiconductor devices. The coolant tub 510 is a
refrigerant container with a flattened box shape, in which a heat
receiving surface 511 and a heat radiation surface 512 as external
surfaces are formed facing each other. The heating elements 530 and
531 are respectively fixed nearly in the center of the heat
receiving surface 511 and the heat radiation surface 512.
[0004] The heat dissipation unit 520 is composed of a plurality of
heat radiation tubes connecting two headers and heat radiation fins
interposed between respective heat radiation tubes. The two headers
are respectively attached to one side of the coolant tub 510 almost
perpendicularly to the heat radiation surface 512, and are formed
connected to the internal space of the coolant tub 510.
[0005] The coolant tub 510 is provided with a tank 513 as a water
level regulation unit. The tank 513 is disposed at the other side
of the coolant tub 510 protruding to the same side as the heat
dissipation unit 520. A given amount of refrigerant is enclosed in
the internal space of the coolant tub 510. Here, as shown in FIG.
9A, the water level of the refrigerant is set so as to keep a level
between the heating elements 530 and 531 and the heat dissipation
unit 520 in the case where the heat receiving surface 511 and the
heat radiation surface 512 are turned in a vertical direction with
the heat dissipation unit 520 up (a vertical direction attitude).
And, as shown in FIG. 9B, it is set so that the inside of the
coolant tub 510 except for the tank 513 may be filled with the
refrigerant in the case where the heat receiving surface 511 and
the heat radiation surface 512 are turned in a horizontal direction
with the heat dissipation unit 520 up (a horizontal direction
attitude). That is to say, a configuration is given where the
refrigerant does not flow into heat dissipation unit 520 by means
of the tank 513 contacting with the inner wall of the coolant tub
510 adjacent to an area where the heating elements 530 and 531 are
to be attached, even if the arrangement attitude of the coolant tub
510 is changed.
[0006] It is said that employing the above-described configuration
in the related ebullient cooling device 500 enables the heat of the
heating elements 530 and 531 surely to be transferred to the
refrigerant and to be cooled, even if the arrangement attitude (the
vertical direction attitude or the horizontal direction attitude)
of the coolant tub 510 is changed. Patent Literature 1: Japanese
Patent Application Laid-Open Publication No. 2004-349652
(paragraphs [0017] to [0027])
DISCLOSURE OF INVENTION
Problem to be Solved by the Invention
[0007] As described above, the related ebullient cooling device 500
is configured to dispose the tank 513 as the water level regulation
unit for the coolant tub 510 with it protruding in order to
increase a degree of freedom of the arrangement in installing it in
electronic equipment. Accordingly, there has been a problem that
the cooling device becomes larger. When the related ebullient
cooling device 500 is disposed turning it upside down in the
vertical direction attitude, the heat dissipation unit 520 becomes
located below the ebullient cooling device 500 in the vertical.
Since the reflux of the refrigerant is not accelerated in that
case, the cooling performance is remarkably degraded. Therefore,
there has been a problem that it is impossible to use the ebullient
cooling device 500 as a cooling device in the arrangement.
[0008] Thus, the related ebullient cooling device has a problem
that the cooling device becomes larger when a degree of freedom of
the arrangement in installing it in electronic equipment is
increased, and that it is impossible to obtain a sufficient degree
of freedom of the arrangement.
[0009] The object of the present invention is to provide a flat
plate cooling device and a method for using the same which solve
the problem mentioned above that in a cooling device using an
ebullient cooling system, a cooling device becomes larger when a
degree of freedom of the arrangement in installing it in electronic
equipment is increased, and that it is impossible to obtain a
sufficient degree of freedom of the arrangement.
Means for Solving a Problem
[0010] A flat plate cooling device according to an exemplary aspect
of the invention includes a plate-like container including a first
flat plate and a second flat plate opposite to the first flat
plate; a refrigerant enclosed in the plate-like container; and a
guiding wall unit connecting the first flat plate to the second
flat plate and controlling a flow of the refrigerant in the
plate-like container; wherein the plate-like container includes a
heat receiving area which is thermally connected to a heating
element disposed on at least one of the first flat plate and the
second flat plate; and the guiding wall unit includes a pair of
guiding walls, and the guiding walls are disposed on opposite sides
of the heat receiving area.
[0011] A method for using a flat plate cooling device according to
an exemplary aspect of the invention includes the steps of: using a
flat plate cooling device according to an exemplary aspect of the
invention switching between a first arrangement state where a
straight line parallel to one side in a longitudinal direction of
the plate-like container is parallel to the vertical direction and
a second arrangement state where to be disposed upside down in the
vertical direction inversely with the first arrangement state.
Effect of the Invention
[0012] According to the flat plate cooling device of the present
invention, it is possible to obtain a small flat plate cooling
device employing an ebullient cooling system with an improved
degree of freedom of the arrangement in installing it in electronic
equipment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a perspective view schematically illustrating a
usage state of a flat plate cooling device in accordance with the
first exemplary embodiment of the present invention.
[0014] FIG. 2 is an exploded perspective view illustrating a
configuration of a flat plate cooling device in accordance with the
first exemplary embodiment of the present invention.
[0015] FIG. 3 is a cross-sectional plan view illustrating a
configuration of a flat plate cooling device in accordance with the
first exemplary embodiment of the present invention.
[0016] FIG. 4 is a cross-sectional plan view to explain the
operation of a flat plate cooling device in accordance with the
first exemplary embodiment of the present invention. FIG. 5 is a
perspective view schematically illustrating another usage state of
a flat plate cooling device in accordance with the first exemplary
embodiment of the present invention.
[0017] FIG. 6 is a cross-sectional plan view illustrating a
configuration of a flat plate cooling device in accordance with the
second exemplary embodiment of the present invention.
[0018] FIG. 7 is a cross-sectional plan view to explain the
operation of a flat plate cooling device in accordance with the
second exemplary embodiment of the present invention.
[0019] FIG. 8A is a cross-sectional plan view to explain an
arrangement state of a flat plate cooling device in accordance with
the second exemplary embodiment of the present invention.
[0020] FIG. 8B is a cross-sectional plan view to explain an
arrangement state of a flat plate cooling device in accordance with
the second exemplary embodiment of the present invention.
[0021] FIG. 8C is a cross-sectional plan view to explain an
arrangement state of a flat plate cooling device in accordance with
the second exemplary embodiment of the present invention.
[0022] FIG. 8D is a cross-sectional plan view to explain an
arrangement state of a flat plate cooling device in accordance with
the second exemplary embodiment of the present invention.
[0023] FIG. 9A is a cross-sectional view illustrating a
configuration of a related ebullient cooling device.
[0024] FIG. 9B is a cross-sectional view illustrating a
configuration of a related ebullient cooling device.
DESCRIPTION OF EMBODIMENTS
[0025] The exemplary embodiments of the present invention will be
described with reference to drawings below.
The First Exemplary Embodiment
[0026] FIG. 1 is a perspective view schematically illustrating a
usage state of a flat plate cooling device 100 in accordance with
the first exemplary embodiment of the present invention. The flat
plate cooling device 100 includes a plate-like container enclosing
a refrigerant. By using materials having a low boiling point as the
refrigerant and evacuating the plate-like container after injecting
the refrigerant into it, it is possible to keep the internal
pressure in the plate-like container at the saturated vapor
pressure of the refrigerant constantly.
[0027] The flat plate cooling device 100 is used with a heating
element 300 such as a semiconductor device thermally connected to
the outer surface of the plate-like container composing the flat
plate cooling device 100. The heat from the heating element 300 is
transmitted to the refrigerant through the plate-like container,
and the refrigerant vaporizes. Since the refrigerant draws heat as
vaporization heat from the heating element 300 at that time, the
increase in temperature of the heating element 300 is suppressed.
The vaporized refrigerant radiates heat in the plate-like container
and condenses and liquefies. Thus, the flat plate cooling device
100 is configured employing an ebullient cooling system in which
heat transport and heat radiation are performed by a cycle of
vaporization and condensation of a refrigerant.
[0028] The configuration of the flat plate cooling device 100 will
be described in more detail using FIGS. 2 and 3. FIG. 2 is an
exploded perspective view of the flat plate cooling device 100, and
FIG. 3 is a cross-sectional plan view of it. The flat plate cooling
device 100 includes a plate-like container 110 including a first
flat plate 111 and a second flat plate 112 opposite to the first
flat plate 111, and a refrigerant 120 enclosed in the plate-like
container 110. It further includes a guiding wall unit 130
connecting the first flat plate 111 to the second flat plate 112
and controlling a flow of the refrigerant 120 in the plate-like
container 110.
[0029] The plate-like container 110 includes a heat receiving area
140 which is thermally connected to a heating element 300 disposed
on at least one of the first flat plate and the second flat plate.
The guiding wall unit 130 is composed of a pair of guiding walls
131 and 132, and the guiding walls 131 and 132 are disposed on
opposite sides of the heat receiving area 140.
[0030] In FIG. 3, the hatched area within the plate-like container
110 represents the refrigerant in liquid state, and the dotted line
in the hatched area represents an interface between the refrigerant
in liquid state (liquid-phase refrigerant) and the refrigerant in
vapor state (vapor-phase refrigerant), which will be hereafter
referred to as "a vapor-liquid interface of refrigerant". It is
possible to use as the refrigerant, for example, hydrofluorocarbon,
hydrofluoroether and the like, which are insulating and inactive
materials.
[0031] Since a flow path of the refrigerant is restricted by the
guiding wall unit 130 regardless of the arrangement state, it is
possible to obtain a small flat plate cooling device employing an
ebullient cooling system with an improved degree of freedom of the
arrangement in installing it in electronic equipment according to
the flat plate cooling device 100 of the present exemplary
embodiment.
[0032] Next, a description will be given of a method for making the
flat plate cooling device 100 in accordance with the present
exemplary embodiment. As shown in FIG. 2, the plate-like container
110 has a configuration where the first flat plate 111 and the
second flat plate 112 are disposed on opposite sides of a side
frame unit 113, for example. The guiding wall unit 130 is disposed
within the plate-like container 110 so as to connect the first flat
plate 111 to the second flat plate 112. As the materials composing
above components, it is possible to use the metal having an
excellent thermal conductive property such as aluminum and copper.
The plate-like container 110 and the guiding wall unit 130 are
produced by joining each other using a brazing material such as
silver alloy. At that time, it is possible to use a clad material
in which a brazing material is bonded to a metal composing the
guiding wall unit 130 and the plate-like container 110. In that
case, it is possible to reduce production costs because the joining
processes can be performed at the same time by a single heating
process.
[0033] The joining process is not limited to the above-described
process, but it is also accepted that the side frame unit 113 is
fixed to the first flat plate 111 and the second flat plate 112 by
screws and the like using a sealing member such as an O-ring. It is
also possible to produce a part of the first flat plate 111 or the
second flat plate 112 and the side frame unit 113 as a unit by
means of a cutting process, a press process and the like.
[0034] After producing the plate-like container 110 and the guiding
wall unit 130, the refrigerant 120 is injected into the plate-like
container 110.
[0035] At that time, for example, by forming an inlet in the side
frame unit 113, injecting the refrigerant 120, and sealing the
inlet after evacuating the plate-like container through the inlet,
it is possible to keep the internal pressure in the plate-like
container 110 at the saturated vapor pressure of the
refrigerant.
[0036] Next, the operation of the flat plate cooling device 100 in
accordance with the present exemplary embodiment will be described.
Arrowed lines in FIG. 4 represent the flow paths of the refrigerant
120 in the flat plate cooling device 100. The refrigerant in liquid
state lying in the heat receiving area 140 draws heat from the
heating element 300 and vaporizes, turning to a bubble refrigerant
121, and then rises by buoyancy toward the vapor-liquid interface
of refrigerant. The refrigerant turned to the vapor state diffuses
within the plate-like container 110 due to the difference in
pressure, radiates heat, and condenses and liquefies. The
refrigerant turned to the liquid state flows back downward in the
vertical direction due to gravity, and then is utilized again for
the heat transport of the heating element 300.
[0037] According to the flat plate cooling device 100 of the
present exemplary embodiment, a pair of guiding walls 131 and 132
composing the guiding wall unit 130 is disposed on opposite sides
of the heat receiving area 140. In the present exemplary
embodiment, as shown in FIG. 4, the guiding walls 131 and 132 are
configured to be disposed extending parallel to one side in a
longitudinal direction of the plate-like container 110. In that
case, the interval between a pair of guiding walls 131 and 132 can
be set equal to or larger than the width of the heat receiving area
140 and not larger than the outer perimeter of the heat receiving
area 140. By employing such a configuration, it becomes possible to
efficiently generate a vapor-liquid two-phase flow of the
refrigerant and to accelerate circulation of the refrigerant. Here,
the vapor-liquid two-phase flow is defined as flowing with two
phases of a vapor phase and a liquid phase being mixed.
[0038] That is to say, if the interval between a pair of guiding
walls 131 and 132 is narrower or less than the width of the heat
receiving area 140, the bubble refrigerant 121 also arises on the
outside of the guiding walls 131 and 132, which does not contribute
to generating the vapor-liquid two-phase flow because such a bubble
refrigerant diffuses within the refrigerant in liquid state. In
contrast, if the interval between a pair of guiding walls 131 and
132 is wider than the width of the heat receiving area 140, the
generation of the vapor-liquid two-phase flow is suppressed because
the vapor-phase refrigerant flows out through all boundaries of the
outer perimeter of the heat receiving area 140 and the liquid-phase
refrigerant flows into there. It is desirable, therefore, that the
interval between the guiding walls 131 and 132 should be set equal
to or smaller than the outer perimeter of the heat receiving area
140.
[0039] Thus, the flat plate cooling device 100 of the present
exemplary embodiment is configured to transport and diffuse heat by
changing the liquid refrigerant into the vapor-phase refrigerant
through the phase transition. In that case, the larger the space
occupied by the vapor refrigerant in the plate-like container 110
is, the more widely heat diffuses, and accordingly, it is possible
to improve the cooling performance. On the other hand, it is
necessary for the liquid refrigerant to be thermally in contact
with the heat receiving area 140 in order to receive heat from the
heating element 300. It is considered, therefore, to increase the
amount of the liquid refrigerant, which causes the volume occupied
by the vapor refrigerant within the plate-like container 110 to
decrease. In that case, it becomes difficult to improve the cooling
performance because the vapor refrigerant is capable of
transporting large amounts of heat.
[0040] It is possible, however, to prevent the problem because the
flat plate cooling device 100 of the present exemplary embodiment
is configured to dispose a pair of guiding walls 131 and 132
composing the guiding wall unit 130 on opposite sides of the heat
receiving area 140. The reason is as follows. The bubble
refrigerant 121 arisen from the phase transition caused by
receiving heat of the heating element 300 is prevented from
diffusing by the guiding walls 131 and 132, and moves in clusters
upward in the vertical direction in the guiding wall unit 130 by
buoyancy. At that time, the refrigerant becomes a vapor-liquid
two-phase flow and rises with the vapor refrigerant taking in the
liquid refrigerant. It becomes possible, therefore, for the liquid
refrigerant to reach the heat receiving area 140 located above the
vapor-liquid interface of the refrigerant in the vertical
direction. Accordingly, it is only necessary for the vapor-liquid
interface of the refrigerant to be located higher than the lower
limit of the heat receiving area 140 in the vertical direction. As
a result, it becomes possible to reduce the amount of the liquid
refrigerant and to increase the volume of a space occupied by the
vapor refrigerant. Which enhances the diffusion and the heat
radiation of the vapor refrigerant, and so it is possible to
improve the cooling performance of the flat plate cooling device
100.
[0041] When the bubble refrigerant 121 escapes from the heat
receiving area 140, liquid refrigerant flows into the heat
receiving area 140. At that time, the liquid refrigerant flows
round the outside of the guiding wall unit 130 into the heat
receiving area 140. That is to say the flow path of the liquid
refrigerant increases in length due to the guiding wall unit 130.
By which the heat radiation of the liquid refrigerant is also
enhanced, and so it becomes possible to further improve the cooling
performance of the flat plate cooling device 100.
[0042] As described above, according to the flat plate cooling
device 100 of the present exemplary embodiment, since the flow path
of the refrigerant is restricted by the guiding wall unit 130, it
is possible to use the flat plate cooling device 100 even in the
arrangement state where it is disposed upside down in the vertical
direction. That is to say, it becomes possible to use the flat
plate cooling device 100 switching between a first arrangement
state where the straight line parallel to one side in a
longitudinal direction of the plate-like container 110 is parallel
to the vertical direction and a second arrangement state where the
flat plate cooling device 100 is disposed upside down in the
vertical direction inversely with the first arrangement state.
Here, by adopting the configuration where the heat receiving area
140 is disposed near the center of one side in a longitudinal
direction of the plate-like container 110, it is possible to
minimize the amount of liquid refrigerant in a case where the flat
plate cooling device 100 is used in two upside-down arrangement
states.
[0043] It is also accepted that a roughened surface area is formed
on the inner surface of the plate-like container 110. The roughened
surface area has a concavo-convex structure, which functions as a
generating nucleus of a bubble refrigerant in the heat receiving
area 140 and functions as a condensing nucleus of the vapor-phase
refrigerant in the area where the vapor-phase refrigerant lies. As
a result, it is possible to activate the phase transition of the
refrigerant and to further increase the cooling performance.
[0044] The optimum value of the size of the concavo-convex
structure is determined by considering physical properties such as
surface tension of the refrigerant and the amount of heat
generation of the heating element. For example, if
hydrofluorocarbon, hydrofluoroether, and the like, which are
insulating and inactive materials, are used as the refrigerant, the
optimum size of the bubble nucleus is in the range of sub-micron to
about a hundred micrometers in center line average roughness. It is
possible, therefore, to form the concavo-convex structure
comparable in size to it by a mechanical processing using abrasive
grains, a sandblast, and the like, or by a chemical processing such
as a plating.
[0045] It is also accepted to use the flat plate cooling device 100
thermally connecting a heat radiating unit 400 composed of heat
radiation fins and the like to the outer surface of the plate-like
container 110 composing the flat plate cooling device 100, as shown
in FIG. 5. Here, the plate-like container 110 can be configured to
include a heat radiation area which is thermally connected to the
heat radiating unit 400 disposed on at least one of the first flat
plate 111 and the second flat plate 112, with the heat radiation
area disposed uniformly in the plate-like container 110. In that
case, since the vaporization and condensation of the vapor-phase
refrigerant in the plate-like container 110 is enhanced by means of
the heat radiation area, it is possible to further improve the
cooling performance of the flat plate cooling device 100. In
addition, since the heat radiation area is disposed uniformly
within the plate-like container 110, the above-mentioned effect is
obtained regardless of the arrangement state of the flat plate
cooling device 100.
The second Exemplary Embodiment
[0046] Next, the second exemplary embodiment of the present
invention will be described. FIG. 6 is a cross-sectional plan view
illustrating a configuration of a flat plate cooling device 200 in
accordance with the second exemplary embodiment of the present
invention. The flat plate cooling device 200 includes the
plate-like container 110 including the first flat plate 111 and the
second flat plate 112 opposite to the first flat plate 111, and the
refrigerant 120 enclosed in the plate-like container 110. It
further includes a guiding wall unit 230 connecting the first flat
plate 111 to the second flat plate 112 and controlling a flow of
the refrigerant 120 in the plate-like container 110. The plate-like
container 110 includes the heat receiving area 140 which is
thermally connected to the heating element 300 disposed on at least
one of the first flat plate and the second flat plate. The guiding
wall unit 230 is composed of a pair of guiding walls 231 and 232,
which are disposed on opposite sides of the heat receiving area
140.
[0047] The flat plate cooling device 200 in accordance with the
present exemplary embodiment differs from the flat plate cooling
device 100 of the first exemplary embodiment in the configuration
of the guiding wall unit 230. That is to say, as shown in FIG. 6,
the guiding walls 231 and 232 composing the guiding wall unit 230
are disposed inclined with respect to the straight line parallel to
one side in a longitudinal direction of the plate-like container
110. Here, it is also accepted a pair of guiding walls 231 and 232
is configured to be disposed symmetrically with respect to the
straight line parallel to one side in a longitudinal direction of
the plate-like container 110.
[0048] According to the flat plate cooling device 200 of the
present exemplary embodiment, since a flow path of the refrigerant
is restricted by the guiding wall unit 230 regardless of the
arrangement state, it is possible to obtain a small flat plate
cooling device employing an ebullient cooling system with an
improved degree of freedom of the arrangement in installing it in
electronic equipment. That is to say, as shown in FIG. 7, it
becomes possible to use the flat plate cooling device 200 even in
the arrangement state where the straight line parallel to one side
in a longitudinal direction of the plate-like container 110 is
perpendicular to the vertical direction. The reason is that a flow
path of the refrigerant is also formed in such case because a
bubble refrigerant 221 generated in the heat receiving area 140
flows along the guiding wall 231. According to the present
exemplary embodiment, therefore, it is possible to use the flat
plate cooling device 200 switching between a first arrangement
state where the straight line parallel to one side in a
longitudinal direction of the plate-like container 110 is parallel
to the vertical direction and a third arrangement state where
perpendicular to the vertical direction.
[0049] In addition, as is the case with the first exemplary
embodiment, it is possible to use the flat plate cooling device 200
even in the arrangement state where it is disposed upside down in
the vertical direction. That is to say, as shown in FIGS. 8A to 8D,
according to the flat plate cooling device 200 of the present
exemplary embodiment, it is possible to use it in a first
arrangement state (FIG. 8A) and also in a second arrangement state
(FIG. 8B) where the first arrangement state is turned upside down.
As described above referring to FIG. 7, it is possible to use it
also in a third arrangement state (FIG. 8C) where the first
arrangement state is turned 90 degrees, and similarly, it is
possible to use it also in a fourth arrangement state (FIG. 8D)
where the third arrangement state is turned upside down. As a
result, according to the present exemplary embodiment, it is
possible to obtain a small flat plate cooling device employing an
ebullient cooling system with a further improved degree of freedom
of the arrangement in installing it in electronic equipment.
[0050] The present invention is not limited to the above-mentioned
exemplary embodiments and can be variously modified within the
scope of the invention described in the claims. It goes without
saying that these modifications are also included in the scope of
the present invention.
[0051] This application is based upon and claims the benefit of
priority from Japanese Patent Application No. 2011-219887, filed on
Oct. 4, 2011, the disclosure of which is incorporated herein in its
entirety by reference.
DESCRIPTION OF THE CODES
[0052] 100, 200 flat plate cooling device
[0053] 110 plate-like container
[0054] 111 first flat plate
[0055] 112 second flat plate
[0056] 113 side frame unit
[0057] 120 refrigerant
[0058] 121, 221 bubble refrigerant
[0059] 130, 230 guiding wall unit
[0060] 131, 132, 231, 232 guiding wall
[0061] 140 heat receiving area
[0062] 300 heating element
[0063] 400 heat radiating unit
[0064] 500 related ebullient cooling device
[0065] 510 coolant tub
[0066] 511 heat receiving surface
[0067] 512 heat radiation surface
[0068] 513 tank
[0069] 520 heat dissipation unit
[0070] 530, 531 heating element
* * * * *