U.S. patent application number 10/400190 was filed with the patent office on 2003-10-16 for heat transport device.
This patent application is currently assigned to Mitsubishi Denki Kabushiki Kaisha. Invention is credited to Ippoushi, Shigetoshi, Ishikawa, Hiroaki, Nakao, Kazushige, Ogushi, Tetsuro, Umemoto, Toshiyuki.
Application Number | 20030192674 10/400190 |
Document ID | / |
Family ID | 28786225 |
Filed Date | 2003-10-16 |
United States Patent
Application |
20030192674 |
Kind Code |
A1 |
Ippoushi, Shigetoshi ; et
al. |
October 16, 2003 |
Heat transport device
Abstract
A heat transport device includes a container having a hollow
structure in which a fluid channel is formed, at least one each
thermal-receiver-type heat exchanger and thermal-radiator-type heat
exchanger arranged side by side on an outer wall of the container
along the fluid channel, and driving heat exchangers provided at
both terminal portions of the container. In this heat transport
device, both ends of the fluid channel are closed to prevent
intrusion of external air, and a liquid and gas are sealed in the
fluid channel. The driving heat exchangers cause the liquid to
oscillate in the container along its fluid channel. The heat
transport device provides low acoustic noise performance and
improved temperature controllability, high heat transportation and
heat radiating capacities, as well as improved heat transfer and
fluid flow characteristics.
Inventors: |
Ippoushi, Shigetoshi;
(Tokyo, JP) ; Ogushi, Tetsuro; (Tokyo, JP)
; Nakao, Kazushige; (Tokyo, JP) ; Ishikawa,
Hiroaki; (Tokyo, JP) ; Umemoto, Toshiyuki;
(Tokyo, JP) |
Correspondence
Address: |
LEYDIG VOIT & MAYER, LTD
700 THIRTEENTH ST. NW
SUITE 300
WASHINGTON
DC
20005-3960
US
|
Assignee: |
Mitsubishi Denki Kabushiki
Kaisha
Tokyo
JP
|
Family ID: |
28786225 |
Appl. No.: |
10/400190 |
Filed: |
March 27, 2003 |
Current U.S.
Class: |
165/104.21 ;
257/E23.088 |
Current CPC
Class: |
F28D 15/0266 20130101;
H01L 2924/0002 20130101; H01L 2924/0002 20130101; F28D 15/0233
20130101; H01L 2924/00 20130101; F28D 15/06 20130101; H01L 23/427
20130101 |
Class at
Publication: |
165/104.21 |
International
Class: |
F28D 015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 2, 2002 |
JP |
JP2002-099461 |
Claims
What is claimed is:
1. A heat transport device comprising: a container having a hollow
structure in which a fluid channel is formed, both ends of the
fluid channel being closed to prevent intrusion of external air,
and a liquid and gas being sealed in the fluid channel; at least
one each thermal-receiver-type heat exchanger and
thermal-radiator-type heat exchanger arranged on an outer wall of
the container along the fluid channel; and driving heat exchangers
provided at both terminal portions of the container for causing
said liquid to oscillate along the fluid channel.
2. The heat transport device according to claim 1, wherein the
internal volume of each terminal portion of the container where the
driving heat exchanger is provided is equal to or larger than the
internal volume of that portion of the container which is bounded
by the center of the thermal-receiver-type heat exchanger and the
center of the thermal-radiator-type heat exchanger.
3. The heat transport device according to claim 1, wherein said
liquid is a combination of two types of liquids having different
boiling points.
4. The heat transport device according to claim 1, wherein each
terminal portion of the container where the driving heat exchanger
is provided is formed into a double pipe structure.
5. The heat transport device according to claim 1, wherein a porous
element which produces capillary action is fitted inside at least
one of the terminal portions of the container where the driving
heat exchangers are provided.
6. The heat transport device according to claim 1, wherein means
serving as a nucleus for bubble formation is provided in at least
one of the terminal portions of the container where the driving
heat exchangers are provided.
7. The heat transport device according to claim 1, wherein said
fluid channel in which the liquid flows is a meandering fluid
channel.
8. The heat transport device according to claim 7, wherein adjacent
portions of the wall of the meandering fluid channel are united,
together forming a single structure.
9. The heat transport device according to claim 7, wherein the
driving heat exchangers are formed of a Peltier element, and
wherein the terminal portions of the container are joined to each
other via the Peltier element.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a heat transport device
used for cooling electronics equipment, for example.
[0003] 2. Description of the Background Art
[0004] To meet the requirements for reliability, lightweight design
and low acoustic noise performance, a heat pipe having no moving
parts unlike pumps has conventionally been used as a heat transport
device for cooling electronics equipment, for example. It has
however become difficult in recent years to cool electronic and
other types of equipment by using heat pipes as a-result of a rapid
increase in the amount of heat radiated from the equipment.
[0005] In addition, as it is fairly difficult to control the
temperature with a heat pipe, there has been a pending need for a
heat transport device which allows easy temperature control.
[0006] Under these circumstances, a new heat transport device was
developed taking into consideration low acoustic noise performance
and good temperature controllability. FIG. 22 is a cross-sectional
view of this kind of heat transport device disclosed in Japanese
Laid-open Patent Publication No. H7-286788.
[0007] In the heat transport device shown in FIG. 22, a pair of
flat headers 100 are interconnected by small-diameter tubes 30 and
a liquid is sealed inside the heat transport device, leaving a gas
phase portion 101 at one end of a fluid channel 52. The fluid
channel 52 is formed of fins 50, 51 provided inside the headers
100, and a capillary tube 70 equipped with a heating unit 80, such
as an electric heater, is connected to a particular part of one
header 100. In this heat transport device, a power source 90
supplies a voltage of a pulse-shaped waveform to the heating unit
80 to heat the liquid inside the capillary tube 70 in a steplike
fashion, eventually causing the liquid to bump. This produces the
effect of a so-called bubble lift pump, in which the liquid is
driven by a rapid pressure increase as a result of evaporation at
one end of the fluid channel 52, while volumetric changes are
absorbed by the gas phase portion 101 at the other end of the fluid
channel 52.
[0008] The aforementioned conventional heat transport device has a
problem that its heat transportation and heat radiating capacities
are low. This is because the conventional heat transport device is
of a type which dissipates heat by driving the liquid as a result
of a small-scale oscillation of the liquid within the capillary
tube 70 by means of a bubble lift pump.
[0009] Although the liquid used as a working fluid should
preferably have properties suited to a bubble lift pump as well as
good heat transfer and flow characteristics, it has so far been
extremely difficult to satisfy all these requirements. In other
words, there has been a problem that it is difficult to increase
the amplitude of oscillation and reduce the period of oscillation
of the working fluid for improving the performance of the bubble
lift pump and to improve the heat transfer and flow characteristics
of the working fluid.
SUMMARY OF THE INVENTION
[0010] The present invention is intended to overcome the
aforementioned problems of the prior art. Accordingly, it is an
object of the invention to provide a heat transport device
featuring low acoustic noise performance and improved temperature
controllability as well as high heat transportation and heat
radiating capacities. It is another object of the invention to
provide a heat transport device capable of offering improved
performance as a bubble lift pump. It is a further object of the
invention to provide a heat transport device using a working fluid
having improved heat transfer and flow characteristics.
[0011] According to the invention, a heat transport device includes
a container having a hollow structure in which a fluid channel is
formed, at least one each thermal-receiver-type heat exchanger and
thermal-radiator-type heat exchanger arranged side by side on an
outer wall of the container along the fluid channel, and driving
heat exchangers provided at both terminal portions of the
container. In this heat transport device, both ends of the fluid
channel are closed to prevent intrusion of external air, and a
liquid and gas are sealed in the fluid channel. The driving heat
exchangers,cause the liquid to oscillate in the container along its
fluid channel.
[0012] Since the driving heat exchangers provided at both terminal
portions of the container cause the liquid to oscillate along the
fluid channel, the heat transport device offers low acoustic noise
performance and improved temperature controllability as well as an
enhanced heat transport efficiency.
[0013] These and other objects, features and advantages of the
invention will become more apparent upon reading the following
detailed description along with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIGS. 1A-1B are sectional diagrams showing the construction
of a heat transport device according to a first embodiment of the
invention;
[0015] FIG. 2 is a sectional diagram showing the construction of a
heat transport device according to a third embodiment of the
invention;
[0016] FIG. 3 is a sectional diagram showing the construction of a
heat transport device according to a fourth embodiment of the
invention;
[0017] FIG. 4 is a sectional diagram showing the construction of a
heat transport device according to a variation of the fourth
embodiment of the invention;
[0018] FIG. 5 is a sectional diagram showing the construction of a
heat transport device according to another variation of the fourth
embodiment of the invention;
[0019] FIG. 6 is a sectional diagram showing the construction of a
heat transport device according to a fifth embodiment of the
invention;
[0020] FIG. 7 is a sectional diagram showing the construction of a
heat transport device according to a sixth embodiment of the
invention;
[0021] FIGS. 8A-8B are sectional diagrams showing the construction
of a heat transport device according to a variation of the sixth
embodiment of the invention;
[0022] FIGS. 9A-9D are fragmentary sectional diagrams showing the
construction of a heat transport device according to a seventh
embodiment of the invention;
[0023] FIGS. 10A-10B are fragmentary sectional diagrams showing the
construction of a heat transport device according to an eighth
embodiment of the invention;
[0024] FIGS. 11A-11B are fragmentary sectional diagrams showing the
construction of a heat transport device according to a ninth
embodiment of the invention;
[0025] FIG. 12 is a sectional diagram showing the construction of a
heat transport device according to a tenth embodiment of the
invention;
[0026] FIG. 13 is a sectional diagram showing the construction of a
heat transport device according to a variation of the tenth
embodiment of the invention;
[0027] FIG. 14 is a sectional diagram showing the construction of a
heat transport device according to an eleventh embodiment of the
invention;
[0028] FIG. 15 is a sectional diagram showing the construction of a
heat transport device according to a twelfth embodiment of the
invention;
[0029] FIG. 16 is a sectional diagram showing the construction of a
heat transport device according to a variation of the twelfth
embodiment of the invention;
[0030] FIGS. 17A-17B are sectional diagrams showing the
construction of a heat transport device according to another
variation of the twelfth embodiment of the invention;
[0031] FIG. 18 is a sectional diagram showing the construction of a
heat transport device according to still another variation of the
twelfth embodiment of the invention;
[0032] FIGS. 19A-19B are sectional diagrams showing the
construction of a heat transport device according to a thirteenth
embodiment of the invention;
[0033] FIGS. 20A-20B are sectional diagrams showing the
construction of a heat transport device according to a variation of
the thirteenth embodiment of the invention;
[0034] FIGS. 21A-21B are sectional diagrams showing the
construction of a heat transport device according to a fourteenth
embodiment of the invention; and
[0035] FIG. 22 is a sectional diagram showing the construction of a
conventional heat transport device.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] Specific embodiments of the invention are now described with
reference to the appended drawings.
First Embodiment
[0037] FIGS. 1A-1B are sectional diagrams showing the construction
of a heat transport device according to a first embodiment of the
invention, in which the numeral 1 designates a container, the
numeral 2 designates thermal-receiver-type heat exchangers, the
numeral 3 designates thermal-radiator-type heat exchangers, the
numeral 4 designates driving heat exchangers, the numeral 5
designates a liquid, and the numeral 6 designates gas.
[0038] As shown in FIGS. 1A-1B, appropriate quantities of the
liquid 5 and the gas 6 are sealed in the container 1 and one each
or more thermal-receiver-type heat exchangers 2 and
thermal-radiator-type heat exchangers 3 are alternately arranged
side by side on an outer wall of the container 1 along its length,
with the driving heat exchangers 4 provided at both terminal
portions of the container 1.
[0039] The interior of the container 1 serves as a fluid channel in
which the liquid 5 and the gas 6 can move. The
thermal-receiver-type heat exchangers 2 are heat generating
portions of an electronic apparatus or its heat radiating portions
for releasing heat of the heat generating portions, for example.
The thermal-radiator-type heat exchangers 3 are heat receiving
portions of external heat transport means or its heat radiating
walls which release heat by natural or forced convection, heat
conduction or radiation. The thermal-radiator-type heat exchangers
3 may be formed of portions of the container 1 exposed directly to
the exterior (e.g., surrounding atmosphere, water or outer space)
such that heat is directly dissipated by natural or forced
convection or radiation. In this case, fins or the like may be
fitted to the exposed portions of the surface of the container
1.
[0040] The driving heat exchangers 4 may be heat exchangers like
electric heaters which are provided at both terminal portions of
the container 1 and can be heated periodically or such a heat
source as sunlight of which amount of input heat varies with time.
In a case where the heat transport device is installed on an
apparatus like an artificial satellite orbiting the earth, for
example, the heat transport device is cyclically heated and cooled
at particular intervals. More specifically, a surface of the heat
transport device upon which sunlight is incident is heated, while
the opposite surface is cooled. This regularly recurring heating
and cooling cycle may be used to constitute the driving heat
exchangers 4.
[0041] The liquid 5 may be a liquid of a single substance, such as
distilled water or ethyl alcohol, a mixture of two or more
single-substance liquids. In either case, the liquid 5 is a liquid
which can undergo phase changes. The gas 6 is a vapor of the liquid
5, although the gas 6 may contain a small amount of gas other than
the vapor of the liquid 5.
[0042] In the heat transport device constructed as shown in FIGS.
1A-1B, the liquid 5 in the container 1 close to the
thermal-receiver-type heat exchangers 2 receives heat and becomes
warmer, producing high-temperature liquid masses, whereas the
liquid 5 in the container 1 close to the thermal-radiator-type heat
exchangers 3 releases heat and becomes cooler, producing
low-temperature liquid masses. Let us assume that the left-hand
driving heat exchanger 4 is once heated and cooled as shown in FIG.
1A, and after a specific period of time has passed, the right-hand
driving heat exchanger 4 is heated and cooled as shown in FIG. 1B,
where the duration to complete this sequence is referred to as one
cycle or period. If the two terminal portions of the container 1
are alternately heated by the respective driving heat exchangers 4
in this fashion, vapor develops due to boiling, builds up due to
continued boiling or evaporation, and shrinks due to condensation
at the left and right ends of the interior of the container 1 with
a time delay equal to a half-cycle duration, causing the
high-temperature and low-temperature liquid masses formed in a
middle part of the container 1 to move left and right as if in
oscillating motion. As a result of this oscillating motion, the
high-temperature liquid masses move to the locations of the
individual thermal-radiator-type heat exchangers 3, where heat of
the high-temperature liquid masses is released, producing
low-temperature liquid masses. On the other hand, the
low-temperature liquid masses move to the locations of the
individual thermal-receiver-type heat exchangers 2, where the
liquid masses receive heat and turn into high-temperature liquid
masses.
[0043] As discussed above, the heat transport device of the present
embodiment is constructed in such a manner that the left and right
ends of the container 1 are alternately heated at regular intervals
by the driving heat exchangers 4 provided at both terminal portions
of the container 1. As a result, the liquid 5 is caused to
periodically oscillate left and right to and from the locations of
the thermal-receiver-type heat exchangers 2 and the
thermal-radiator-type heat exchangers 3, so that heat is
transported from the thermal-receiver-type heat exchangers 2 to the
thermal-radiator-type heat exchangers 3. According to this
construction, it is possible to easily increase the amplitude of
oscillation and reduce the period of oscillation of the liquid 5 by
varying the amount of heat input and the interval of heating
cycles. This makes it possible to improve heat transport efficiency
and control the temperature of the liquid 5 at the locations of the
individual thermal-receiver-type heat exchangers 2.
[0044] Since the heat transport device of the embodiment has no
moving parts unlike a pump, it provides enhanced durability and
reliability and can be made compact and lightweight.
[0045] Furthermore, unlike a heat pipe which utilizes gravity, the
heat transport device does not use gravity and is not easily
affected by the effect of gravity due to its construction.
Therefore, the heat transport device can be used in the
microgravity or zero-gravity environment of space as well as under
high-gravity conditions.
Second Embodiment
[0046] In the heat transport device of FIGS. 1A-1B, it is
preferable that the internal volume V1 of a portion of the
container 1 where each driving heat exchanger 4 is provided be
equal to or larger than the internal volume V2 of that portion of
the container 1 which is bounded by the center of each
thermal-receiver-type heat exchanger 2 and the center of its
adjacent thermal-radiator-type heat exchanger 3. It is also
preferable that the total volume V3 of the liquid 5 be
approximately equal to a value obtained by subtracting the volume
V1 from the total internal volume V of the container 1.
[0047] If the heat transport device is designed such that the
internal volumes V1, V2 and the volume V3 satisfy the relationships
V1.gtoreq.V2 and V3.apprxeq.V.about.V1, the liquid 5 can be caused
to oscillate with a large amplitude. When a larger oscillation of
the liquid 5 is produced in this fashion, masses of the liquid 5
move between multiple pairs of the thermal-receiver-type heat
exchangers 2 and the thermal-radiator-type heat exchangers 3, so
that heat is transported from the thermal-receiver-type heat
exchangers 2 to the thermal-radiator-type heat exchangers 3 with a
higher efficiency.
Third Embodiment
[0048] FIG. 2 is a sectional diagram showing the construction of a
heat transport device according to a third embodiment of the
invention, in which elements identical or similar to those depicted
in FIGS. 1A-1B are designated by the same reference numerals. What
is characteristic of the third embodiment is that it employs a
combination of a low-boiling liquid 7 and a high-boiling liquid 8
separated from each other.
[0049] The low-boiling liquid 7 should be a liquid which shows a
large volumetric change with a small amount of heat input. For
example, it should be a liquid having a large amount of latent heat
and a large difference in density between the liquid and vapor
phases. On the other hand, the high-boiling liquid 8 should be a
liquid which has a higher boiling point than the low-boiling liquid
7, high fluidity and good heat transportation performance. For
example, it should be a liquid having a small viscosity
coefficient, a large heat capacity and a high thermal conductivity.
Specifically, Fluorinert (which is a trademark of a product of
Sumitomo 3M Ltd. expressed by the chemical formula C.sub.6F.sub.14)
or Freon HFC134a may be used as the low-boiling liquid 7 while
water may be used as the high-boiling liquid 8, for example.
[0050] By using the combination of the low-boiling liquid 7 and the
high-boiling liquid 8 separated from each other, it is possible to
cause a large oscillation of the high-boiling liquid 8 with a small
amount of energy consumption by the driving heat exchangers 4
(resulting in a high coefficient of performance) and reduce the
period of oscillation.
[0051] Even if the amount of heat input through the
thermal-receiver-type heat exchangers 2 is large and the
temperature of liquid masses close to the thermal-receiver-type
heat exchangers 2 increases, vapor develops, builds up and
condenses in a stable manner at the locations of the driving heat
exchangers 4, because the low-boiling liquid 7 is present at both
terminal portions of the container 1. Consequently, it is possible
to cause the high-boiling liquid 8 to oscillate and transport heat
in a stable manner. Accordingly, the present embodiment helps
increase the amount of maximum transportable heat.
Fourth Embodiment
[0052] FIGS. 3-5 are sectional diagrams showing the construction of
a heat transport device according to a fourth embodiment of the
invention and variations thereof, in which elements identical or
similar to those depicted in FIGS. 1A-1B are designated by the same
reference numerals. The fourth embodiment employs a double pipe
structure having outer pipes connected to the container 1 as shown
in FIG. 3, a double pipe structure in which both terminal portions
of the container 1 are folded back as shown in FIG. 4, or a double
pipe structure in which both terminal portions of the container 1
are connected to separate vessels as shown in FIG. 5.
[0053] According to the fourth embodiment, heat is exchanged
between the liquid 5 and the gas 6 through an outer wall of the
container 1 when the liquid 5 has returned to either of the
terminal portions of the container 1 where the driving heat
exchangers 4 are provided. The gas 6 is cooled and condensed,
causing a drop in internal pressure and producing a great liquid
driving pressure. With the double pipe structures of FIGS. 3-5, it
is possible to cause the liquid 5 to oscillate at shorter recurring
cycles and transport heat from the thermal-receiver-type heat
exchangers 2 to the thermal-radiator-type heat exchangers 3 with a
higher efficiency.
Fifth Embodiment
[0054] FIG. 6 is a sectional diagram showing the construction of a
heat transport device according to a fifth embodiment of the
invention, in which elements identical or similar to those depicted
in FIGS. 1A-1B are designated by the same reference numerals. The
construction of this embodiment is characterized in that porous
elements 9 formed of a porous material or having grooves which
produce capillary action are fitted inside the terminal portions of
the container 1 where the driving heat exchangers 4 are
provided.
[0055] With the provision of the porous elements 9 at the terminal
portions of the container 1 where the driving heat exchangers 4 are
provided, it is possible to supplement the amount of the liquid 5
consumed by evaporation or boiling with the aid of the capillary
action. Furthermore, since inside wall surfaces of the container 1
at its terminal portions can easily retain the liquid 5, they
become less likely to dry out. It is therefore possible to use high
heat flux heat exchangers as the driving heat exchangers 4.
[0056] Furthermore, the porous elements 9 serve to release the gas
6 by evaporating the liquid 5 and thereby maintain a driving force
for moving the liquid 5 for an extended period of time, making it
possible to increase the distance of oscillation-assisted movement
of the liquid 5.
[0057] In addition, pores (or grooves) in the porous elements 9 act
just like nuclei for producing the gas (vapor bubbles) 6, so that
the gas 6 can easily develop and, as a consequence, it becomes
possible to reduce the period of oscillation of the liquid 5.
Sixth Embodiment
[0058] FIG. 7 is a sectional diagram showing the construction of a
heat transport device according to a sixth embodiment of the
invention, in which elements identical or similar to those depicted
in FIGS. 1A-1B are designated by the same reference numerals. The
construction of this embodiment is characterized in that there are
provided turbulence accelerators 10 in the container 1 at its
portions where the thermal-receiver-type heat exchangers 2 and the
thermal-radiator-type heat exchangers 3 are provided.
[0059] Located at the portions of the container 1 where the
thermal-receiver-type heat exchangers 2 and the
thermal-radiator-type heat exchangers 3 are provided, the
turbulence accelerators 10 produce turbulences in the liquid 5 as
it oscillates left and right. This construction makes it possible
to considerably enhance the heat transfer performance of the heat
transport device without causing a substantial increase in pressure
loss within a fluid channel in the whole container 1.
[0060] The construction of the heat transport device of FIG. 7 may
be modified by replacing the turbulence accelerators 10 with
microchannel chips 11 as shown in FIGS. 8A-8B, of which FIG. 8B is
a sectional view of the microchannel chip 11 taken along lines A-A
of FIG. 8A. The microchannel chip 11 is formed of multiple straight
fins, pin fins, a porous material or foam metal, and has a number
of narrow flow paths. This variation of the embodiment offers the
same advantageous effect as the construction of FIG. 7.
Seventh Embodiment
[0061] FIGS. 9A-9D are fragmentary sectional diagrams showing the
construction of a heat transport device according to a seventh
embodiment of the invention, in which elements identical or similar
to those depicted in FIGS. 1A-1B are designated by the same
reference numerals. In this embodiment, a hole 13 is formed in an
inside wall surface 12 of the container 1 and a plug-like insert 14
is fitted in the hole 13 in such a fashion that a hollow space is
formed at the bottom of the hole 13 as shown in FIG. 9A.
[0062] According to the construction of this embodiment, the gas 6
is formed at the bottom of the hole 13 in a stable fashion, so that
a vapor bubble 15 easily develops from between the inside wall
surface 12 and the insert 14. Since the space between the insert 14
and the bottom of the hole 13 serves as a nucleus for bubble
formation and the vapor bubble 15 produced therefrom stirs up the
liquid 5 adjacent to the inside wall surface 12, heat transfer
efficiency is increased close to the inside wall surface 12. In
addition, it is possible to controllably select the position where
the vapor bubble 15 is produced by providing the hole 13 and the
insert 14 at a desired location.
[0063] Preferably, one or more grooves should be formed along a
side surface of the insert 14 to connect the hollow space at the
bottom of the hole 13 to the liquid 5 lying in contact with the
inside wall surface 12 as illustrated in FIGS. 9B-9D.
[0064] The heat transfer efficiency can be further improved by
forming more than one such hole 13 fitted with the insert 14 in the
inside wall surface 12.
Eighth Embodiment
[0065] FIGS. 10A-10B are fragmentary sectional diagrams showing the
construction of a heat transport device according to an eighth
embodiment of the invention, FIG. 10B being an enlarged view of a
portion A shown in FIG. 10A. In these Figures, elements identical
or similar to those depicted in FIGS. 1A-1B are designated by the
same reference numerals. The construction of this embodiment is
characterized in that there is formed a cavity 16 in a bottom
surface of the insert 14 itself as shown in FIG. 10A.
[0066] As depicted in FIG. 10B, angle .theta. formed by surfaces of
the hole 13 and the insert 14 increases when the cavity 16 is
formed in the bottom surface of the insert 14. An advantage of this
structure is that the gas 6 can stay in the hollow space bounded by
the bottom of the hole 13 and the cavity 16 in a more stable
fashion and the vapor bubble 15 can develop more easily.
Ninth Embodiment
[0067] FIGS. 11A-11B are sectional diagrams showing the
construction of a heat transport device according to a ninth
embodiment of the invention, FIG. 11B being an enlarged view of a
portion A shown in FIG. 11A. In these Figures, elements identical
or similar to those depicted in FIGS. 1A-1B are designated by the
same reference numerals. In this embodiment, a hole 13 fitted with
an insert 14 having the same structure as that of the seventh or
eighth embodiment is provided at least at one terminal portion of
the inside wall surface 12 of the container 1 where the driving
heat exchanger 4 is provided.
[0068] In this embodiment, a vapor bubble 15 develops more easily
from the inside wall surface 12 of the container 1 at its terminal
portion where the driving heat exchanger 4 is provided, making it
possible to reduce the period of oscillation of the liquid 5.
[0069] Since the hole 13 fitted with the insert 14 is provided at
the terminal portion of the container 1, the vapor bubble 15
develops from that portion of the container 1. This makes it
possible to increase the distance of movement of the liquid 5 and
further enhance the heat transfer performance of the heat transport
device.
[0070] If a cavity 16 is formed in a bottom surface of the insert
14, the gas 6 can stay at the bottom of the hole 13 in a more
stable fashion and the vapor bubble 15 can develop more easily.
Tenth Embodiment
[0071] FIGS. 12-13 are sectional diagrams showing the construction
of a heat transport device according to a tenth embodiment of the
invention and a variation thereof, in which elements identical or
similar to those depicted in FIGS. 1A-1B are designated by the same
reference numerals. The tenth embodiment is characterized in that
it employs a meandering pipe 17 instead of the container 1 of the
foregoing embodiments.
[0072] By using the meandering pipe 17 in any of the foregoing
embodiments, heat can be easily carried away from randomly located
heat sources.
[0073] If a thermal-receiver-type heat exchanger 2 and a
thermal-radiator-type heat exchanger 3 are flat-shaped as shown in
FIG. 13, the overall surface area of heat exchange increases,
offering a higher efficiency of heat exchange.
Eleventh Embodiment
[0074] FIG. 14 is a sectional diagram showing the construction of a
heat transport device according to an eleventh embodiment of the
invention, in which elements identical or similar to those depicted
in FIGS. 1A-1B are designated by the same reference numerals. The
construction of this embodiment is characterized in that both
terminal portions of a meandering pipe 17 are joined to each other
with a Peltier element 18 placed in between, the Peltier element 18
serving as a driving heat exchanger.
[0075] In this embodiment, the direction of an electric current
flowing through the Peltier element 18 is periodically reversed so
that one end of the meandering pipe 17 is heated while the other
end of the meandering pipe 17 is cooled, and vice versa, causing
the liquid 5 in the meandering pipe 17 to oscillate.
[0076] Since the gas 6 produced by the heating condenses when
cooled as a result of the reversing of the electric current, a
large pressure difference is produced between both terminal
portions of the meandering pipe 17. This makes it possible to
reduce the period of oscillation of the liquid 5, enabling more
efficient heat transfer operation.
[0077] Furthermore, since the pressure difference between both
terminal portions of the meandering pipe 17 can be increased as
stated above, a resultant driving force permits satisfactory heat
transfer operation even when the length of the meandering pipe 17
is increased or the liquid 5 has a large flow resistance.
Twelfth Embodiment
[0078] FIG. 15 is a sectional diagram showing the construction of a
heat transport device according to a twelfth embodiment of the
invention, in which elements identical or similar to those depicted
in FIGS. 1A-1B are designated by the same reference numerals. The
construction of this embodiment is characterized in that a
meandering pipe 17 is structured such that heat is properly
transferred between adjacent portions of the wall of the meandering
pipe 17. In the construction shown in FIG. 15, the adjacent
portions of the wall of the meandering pipe 17 are in mutual
contact and joined together by welding, brazing or adhesive
bonding.
[0079] In one variation of the embodiment shown in FIG. 16, a
meandering groove is formed in a flat plate and a meandering fluid
channel 19 is fitted in the meandering groove, forming a single
structure with the flat plate. Since adjacent portions of the wall
of the meandering fluid channel 19 are joined to each other by the
flat plate, heat is properly transferred between them.
[0080] Alternatively, a meandering pipe 17 may be molded by a
material having a high thermal conductivity such that adjacent
portions of the wall of the meandering pipe 17 are united into a
single structure and heat is properly transferred between those
portions.
[0081] In another variation of the embodiment shown in FIGS.
17A-17B, a meandering fluid channel 19 is formed by making
contiguous inner walls in a container. Since adjacent portions of
the meandering fluid channel 19 are separated by the contiguous
inner walls but formed in a single structure, heat is properly
transferred between those portions.
[0082] The aforementioned constructions of this embodiment provide
an improved efficiency of heat exchange between a
thermal-receiver-type heat exchanger 2 and a thermal-radiator-type
heat exchanger 3 as heat is not only transported by oscillation of
the liquid 5 but dissipated between the adjacent portions of the
meandering pipe 17 or of the meandering fluid channel 19.
[0083] The variations of the embodiment shown in FIGS. 16 and
17A-17B provide flat-shaped heat transport devices which can be
easily bent or otherwise deformed. If there is an obstacle in a
heat radiating area where the thermal-radiator-type heat exchanger
3 should be situated, the heat transport device may be formed in an
odd shape as illustrated in FIG. 18. In this variation of the
embodiment, the thermal-radiator-type heat exchanger 3 is formed of
multiple fins 20 attached to radiating portions of a meandering
fluid channel 19 to effectively use their two opposite
surfaces.
Thirteenth Embodiment
[0084] FIGS. 19A-19B, 20A-20B are sectional diagrams showing the
construction of a heat transport device according to a thirteenth
embodiment of the invention and a variation thereof, in which
elements identical or similar to those depicted in FIGS. 1A-1B are
designated by the same reference numerals. The heat transport
device of this embodiment has a meandering fluid channel 19 similar
to that of the twelfth embodiment, but there are formed bypass
holes 21 in inner walls separating adjacent portions of the
meandering fluid channel 19.
[0085] Since the liquid 5 is allowed to pass from one side of the
inner wall to the other through the bypass holes 21 in this
construction, the embodiment makes it possible to dissipate heat
more positively.
Fourteenth Embodiment
[0086] FIG. 21A is a sectional plan view showing the construction
of a heat transport device according to a fourteenth embodiment of
the invention and FIG. 21B is a horizontal sectional view taken
along lines C-C of FIG. 21A. In these Figures, elements identical
or similar to those depicted in FIGS. 1A-1B are designated by the
same reference numerals. The construction of this embodiment is
characterized in that multiple layers of meandering fluid channels
19 are stacked one on top of another in a manner that the flow
direction of the liquid 5, in one layer is the same as, opposite
to, or perpendicular to the flow direction of the liquid 5 in
another layer.
[0087] This embodiment helps achieve a higher heat transfer
efficiency as heat is dissipated in two- or three-dimensional
form.
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