U.S. patent application number 11/306455 was filed with the patent office on 2007-01-11 for loop-type heat exchange device.
Invention is credited to Chih-Feng Fan, Chuen-Shu Hou, Tay-Jian Liu, Chao-Nien Tung, Chih-Hao Yang.
Application Number | 20070006994 11/306455 |
Document ID | / |
Family ID | 37597716 |
Filed Date | 2007-01-11 |
United States Patent
Application |
20070006994 |
Kind Code |
A1 |
Liu; Tay-Jian ; et
al. |
January 11, 2007 |
LOOP-TYPE HEAT EXCHANGE DEVICE
Abstract
A loop-type heat exchange device (10) is disclosed, which
includes an evaporator (20), a condenser (40), a vapor conduit (30)
and a liquid conduit (50). The evaporator defines therein a chamber
for containing a working fluid. The chamber is divided into an
evaporating region and a micro-channel region. The working fluid in
the evaporator evaporates into vapor after absorbing heat at the
evaporating region, and the generated vapor flows, via the vapor
conduit, to the condenser where the vapor releases its latent heat
of evaporation and is condensed into condensate. The condensate
then returns back, via the liquid conduit, to the evaporator to
thereby form a heat transfer loop. The evaporator is configured in
such a manner that an amount of vapor to be formed and accumulated
in the micro-channel region can be minimized.
Inventors: |
Liu; Tay-Jian; (Shenzhen,
CN) ; Tung; Chao-Nien; (Shenzhen, CN) ; Hou;
Chuen-Shu; (Shenzhen, CN) ; Fan; Chih-Feng;
(Shenzhen, CN) ; Yang; Chih-Hao; (Shenzhen,
CN) |
Correspondence
Address: |
NORTH AMERICA INTELLECTUAL PROPERTY CORPORATION
P.O. BOX 506
MERRIFIELD
VA
22116
US
|
Family ID: |
37597716 |
Appl. No.: |
11/306455 |
Filed: |
December 29, 2005 |
Current U.S.
Class: |
165/104.26 ;
165/104.33 |
Current CPC
Class: |
H01L 2924/00 20130101;
H01L 2924/0002 20130101; F28D 15/0266 20130101; H01L 2924/0002
20130101; F28D 15/043 20130101 |
Class at
Publication: |
165/104.26 ;
165/104.33 |
International
Class: |
F28D 15/04 20060101
F28D015/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 8, 2005 |
CN |
200510035934.X |
Claims
1. A heat exchange device comprising: an evaporator defining
therein a chamber for containing a working fluid, the chamber being
divided into two regions, the working fluid being capable of
turning into vapor in the evaporator upon receiving heat at one
region of said chamber; a condenser; a vapor conduit and a liquid
conduit each being connected between the evaporator and the
condenser, wherein the vapor generated in the evaporator is capable
of being transferred via the vapor conduit to the condenser and
turning into condensate in the condenser upon releasing the heat,
and the condensate is capable of being transferred via the liquid
conduit to the evaporator; and means formed on the evaporator for
reducing an amount of vapor being accumulated in the other region
of said chamber.
2. The heat exchange device of claim 1, wherein said means is a
cooling device thermally connected to the evaporator at a location
corresponding to the other region of said chamber.
3. The heat exchange device of claim 2, wherein the cooling device
includes a plurality of cooling fins connected to an outer surface
of the evaporator.
4. The heat exchange device of claim 1, wherein the evaporator
includes a top cover and a bottom cover cooperating with each other
to define said chamber, and said means is a protrusion section
projecting downwardly from the bottom cover corresponding to the
one region of said chamber.
5. The heat exchange device of claim 1, wherein a wick structure is
arranged inside the liquid conduit.
6. The heat exchange device of claim 1, wherein a wick structure is
arranged inside the evaporator spanning across the two regions of
said chamber.
7. The heat exchange device of claim 6, wherein the one region of
said chamber is partially filled with the first wick structure and
the other region of said chamber is fully filled with the wick
structure.
8. The heat exchange device of claim 7, wherein a portion of the
wick structure extends from the other region of said chamber into a
middle part of the one region of said chamber.
9. The heat exchange device of claim 1, wherein the vapor conduit
and the liquid conduit are flexible.
10. The heat exchange device of claim 1, further comprising another
vapor conduit connected between the evaporator and the
condenser.
11. The heat exchange device of claim 1, further comprising another
condenser, another vapor conduit and another liquid conduit, the
another vapor conduit and the another liquid conduit each being
connected between the another condenser and said evaporator.
12. A heat exchange device comprising: an evaporator defining
therein a chamber for containing a first wick structure and a
working fluid saturated in the first wick structure, the chamber
being divided into two regions, the first wick structure spanning
across both the two regions of the chamber, the working fluid being
capable of turning into vapor in the evaporator upon receiving heat
at one region of said chamber; a condenser; and a vapor conduit and
a liquid conduit each being connected between the evaporator and
the condenser, the liquid conduit having a second wick structure
arranged therein, wherein the vapor generated in the evaporator is
capable of being transferred via the vapor conduit to the condenser
and turning into condensate in the condenser upon releasing the
heat, and the condensate is capable of being transferred via the
liquid conduit to the other region of said chamber of said
evaporator under a capillary force developed by the second wick
structure.
13. The heat exchange device of claim 12, wherein a plurality of
cooling fins is thermally connected to an outer surface of the
evaporator corresponding to the other region of said chamber.
14. The heat exchange device of claim 12, wherein the evaporator
includes a top cover and a bottom cover cooperating with each other
to define said chamber, and the bottom cover has a section being
thicker than the remaining part of the bottom cover, the section
corresponding to the one region of said chamber.
15. A loop heat exchanging device having working fluid therein
comprising: an evaporator having a first region accommodating
therein a first wick structure and a second region having a part
adapted for receiving heat from a heat generating component for
heating the working fluid into vapor; a vapor conduit having a
first end communicating with the second region of the evaporator so
that the vapor can enter the vapor conduit and a second end; a
condenser communicating with the second end of the vapor conduit,
in the condenser the vapor being condensed to condensate; and a
condensate conduit having a first end communicating with the
condenser so that the condensate can enter the condensate conduit
and a second end communicating with the first region of the
evaporator so that the condensate in the condensate conduit can
enter the first region of the evaporator to saturate the first wick
structure.
16. The loop heat exchanging device of claim 15, wherein the
condensate conduit accommodates a second wick structure
therein.
17. The loop heat exchanging device of claim 16, wherein the first
wick structure extends to the part of the second region of the
evaporator for receiving heat from the heat generating
component.
18. The loop heat exchanging device of claim 17, wherein the part
of the second region of the evaporator is located at a middle of
the second region and the first wick structure extends further to
two sides of the second region.
19. The loop heat exchanging device of claim 17, wherein the
evaporator has outwardly extending fins at the first region.
20. The loop heat exchanging device of claim 19, wherein the
evaporator has an outer wall, the outer wall having first portion
and second portion corresponding to the first and second regions,
respectively, the second portion being thicker than the first
portion.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to an apparatus for
transfer or dissipation of heat from heat-generating components,
and more particularly to a loop-type heat exchange device suitable
for removing heat from electronic components.
DESCRIPTION OF RELATED ART
[0002] As progress continues to be made in electronic industries,
electronic components such as integrated circuit chips are produced
to have more powerful functions while maintaining a unchanged size
or even a smaller size. As a result, the amount of heat generated
by these electronic components during their normal operations is
commensurately increased, which in turn will adversely affect their
workability and stability. It is well known that cooling devices
are commonly used to remove heat from heat-generating components.
However, currently well-known cooling devices such as heat sink
plus cooling fan are no longer qualified or desirable for removing
the heat from these electronic components due to their low heat
removal capacity. Conventionally, increasing the rotation speed of
the cooling fan and increasing the size of the heat sink are two
approaches commonly used to improve the heat dissipating
performance of the cooling device involved. However, if the
rotation speed of the cooling fan is increased, problems such as
large noise will inevitably be raised. On the other hand, by
increasing the size of the heat sink, it will make the cooling
device bulky, which contravenes the current trend towards
miniaturization.
[0003] Currently, an advantageous mechanism for more effectively
removing the heat from these electronic components and overcoming
the aforementioned disadvantages is adopted, which is related to
use of heat pipe technology. Heat pipes are an effective heat
transfer means due to their low thermal resistance. A heat pipe is
usually a vacuum casing containing therein a working fluid.
Preferably, a wick structure is provided inside the heat pipe,
lining an inner wall of the casing. The heat pipe has an
evaporating section for receiving heat from a heat-generating
component and a condensing section for releasing the heat absorbed
by the evaporating section. When the heat is inputted into the heat
pipe via its evaporating section, the working fluid contained
therein absorbs the heat and turns into vapor. Due to the
difference of vapor pressure between the two sections of the heat
pipe, the generated vapor moves, with the heat being carried,
towards the condensing section where the vapor is condensed into
condensate after releasing the heat into ambient environment by,
for example, fins thermally contacting the condensing section. Due
to the difference of capillary pressure developed by the wick
structure between the two sections, the condensate is then drawn
back by the wick structure to the evaporating section where it is
again available for evaporation.
[0004] In the heat pipe, however, there still exists a fatal
drawback awaited to be overcome. The movement of the vapor is
countercurrent to that of the condensate within the casing of the
heat pipe. The movement of the vapor will, to a certain extent,
produce a resistance to the flow of the condensate due to an
interaction between the vapor and the condensate. This negative
effect will lower down the speed of the condensate in supplying to
the evaporating section of the heat pipe. If the condensate is not
timely sent back to the evaporating section, the heat pipe will
suffer a dry-out problem at that section.
[0005] In order to overcome the drawback of the conventional heat
pipe, a loop-type heat exchange device has been proposed. The
loop-type heat exchange device includes an evaporator, a condenser,
a vapor conduit and a liquid conduit. The evaporator defines
therein a chamber for containing a working fluid. The vapor and
liquid conduits each are connected between the evaporator and the
condenser by two individual pipes. Specifically, the working fluid
in the evaporator evaporates into vapor after absorbing the heat
from the heat-generating component, and the generated vapor then
flows, via the vapor conduit, to the condenser where the vapor is
condensed into condensate after releasing its latent heat of
evaporation. The condensate then returns back to the evaporator via
the liquid conduit to thereby be available again for evaporation,
thus forming a heat transfer loop. One of the advantages of the
loop-type heat exchange device in relation to the conventional heat
pipe is that the vapor and the condensate move separately and do
not interfere with each other.
[0006] In practice, however, many improvements still can be made on
the design of the loop-type heat exchange device in order to
exhibit its full advantages. For example, since both the vapor
conduit and the liquid conduit are connected to the evaporator, if
no effective mechanism is provided to prevent the vapor generated
in the evaporator from moving backwards towards and entering into
the liquid conduit, a situation that the vapor flows in the liquid
conduit along a direction countercurrent to that of the condensate
will happen. In this situation, the loop-type heat exchange device
cannot have an optimal heat dissipation performance. Furthermore,
the irregular movement of the vapor into the liquid conduit also
produces significant resistance to the condensate to enter the
evaporator, which will prevent the condensate from being supplied
to the place where the evaporation of the working fluid is
effectuated. If the condensate is not brought back to that place
timely due to the influence of the vapor, a dry-out problem will
accordingly be raised in the evaporator.
[0007] Therefore, it is desirable to provide a loop-type heat
exchange device which overcomes the foregoing disadvantages.
SUMMARY OF INVENTION
[0008] The present invention relates to a loop-type heat exchange
device for removing heat from a heat-generating component. The heat
exchange device includes an evaporator, a condenser, a vapor
conduit and a liquid conduit. The evaporator defines therein a
chamber for containing a working fluid. The chamber is divided into
two regions. The working fluid is capable of turning into vapor in
the evaporator upon receiving the heat at one region of said
chamber from the heat-generating component. Each of the vapor and
liquid conduits is connected between the evaporator and the
condenser. The vapor generated in the evaporator is capable of
being transferred via the vapor conduit to the condenser and
turning into condensate in the condenser upon releasing the heat
carried by the vapor. The condensate is capable of being
transferred via the liquid conduit to the evaporator. The heat
exchange device further includes means formed on the evaporator for
reducing an amount of vapor being accumulated in the other region
of the chamber of the evaporator.
[0009] In one embodiment of the present heat exchange device, said
means for reducing the amount of vapor being accumulated in the
other region of the chamber of the evaporator is a cooling device
thermally connected to the evaporator corresponding to that region.
The cooling device may be a plurality of cooling fins connected to
an outer surface of the evaporator. In an alternative embodiment,
the evaporator includes a top cover and a bottom cover cooperating
with each other to define the chamber of the evaporator and said
means is a projected section from the bottom cover corresponding to
the one region of the chamber of the evaporator. The cooling device
is capable of condensing that portion of vapor having entered into
the other region of the chamber and meanwhile maintaining a low
temperature for that region. The projected section of the bottom
cover is used to receive the heat from the heat-generating
component and functions for reducing an amount of the heat to be
conducted from the projected section to the remaining part of the
bottom cover and finally to the other region of the chamber. On
this basis, the vapor formed and accumulated in the other region of
the chamber is reduced to a minimum amount and the unidirectional
working fluid movement mechanism along the heat transfer loop
established by the present heat exchange device is well followed,
thus effectively taking the heat away from the heat-generating
component.
[0010] Other advantages and novel features of the present invention
will become more apparent from the following detailed description
of preferred embodiment when taken in conjunction with the
accompanying drawings, in which:
BRIEF DESCRIPTION OF DRAWINGS
[0011] FIG. 1 is an isometric view of a loop-type heat exchange
device in accordance with a first embodiment of the present
invention;
[0012] FIG. 2 is a cross-sectional view of an evaporator of the
loop-type heat exchange device of FIG. 1, taken along line II-II
thereof;
[0013] FIG. 3 is an isometric view of the evaporator of the
loop-type heat exchange device of FIG. 1, with a top cover thereof
being removed;
[0014] FIG. 4 is a bottom plan view of the evaporator of the
loop-type heat exchange device of FIG. 1;
[0015] FIG. 5 is an isometric view of a loop-type heat exchange
device in accordance with a second embodiment of the present
invention; and
[0016] FIG. 6 is an isometric view of a loop-type heat exchange
device in accordance with a third embodiment of the present
invention.
DETAILED DESCRIPTION
[0017] FIG. 1 illustrates a loop-type heat exchange device 10 in
accordance with a first embodiment of the present invention. The
heat exchange device 10 includes an evaporator 20, a vapor conduit
30, a condenser 40 (shown in broken lines) and a liquid conduit 50.
The evaporator 20 preferably is made of two separable portions
connected together, as will be discussed in more detail later. The
vapor and liquid conduits 30, 50 lie in parallel to each other,
although they are not limited to this relationship. Two ends of
each of the vapor and liquid conduits 30, 50 are respectively
connected to the evaporator 20 and the condenser 40. The vapor and
liquid conduits 30, 50 preferably are made of flexible metal or
non-metal materials so that they could be bent or flattened easily
in order to cause the heat exchange device 10 to be applicable in
electronic products having a limited mounting space such as
notebook computers.
[0018] The evaporator 20 contains therein a working fluid (not
shown). As heat from a heat source (not shown) is applied to the
evaporator 20, the working fluid contained in the evaporator 20
evaporates into vapor after absorbing the heat. Then, the generated
vapor flows, via the vapor conduit 30, to the condenser 40 where
the vapor releases its latent heat of evaporation and is thus
condensed into condensate. The condensate then returns back from
the condenser 40, via the liquid conduit 50, to the evaporator 20
where it is again available for evaporation, thus forming a heat
transfer loop. In the present heat transfer device 10, the
movements of the vapor and the condensate are carried out
respectively and separately in the vapor conduit 30 and the liquid
conduit 50.
[0019] In the present heat exchange device 10, the condenser 40 is
used to dissipate the heat carried by the vapor. Although the
condenser 40 located between the vapor conduit 30 and the liquid
conduit 50 is schematically shown in broken lines, it is well known
by those skilled in the art that the condenser 40 may take various
forms, including metal fins, cooling devices (typically including
heat sinks and cooling fans), or liquid cooling systems. For
example, if the vapor conduit 30 and the liquid conduit 50 are an
integral pipe, as shown in FIG. 1, the condenser 40 may be a
plurality of fins stacked on the pipe between the vapor and liquid
conduits 30, 50. However, the condenser 40 may also be designed to
include a hollow casing defined therein a chamber, and a plurality
of fins attached to an outer surface of the casing. In this
situation, the vapor conduit 30 and the liquid conduit 50 are
preferably discrete members, each with a distal end portion being
inserted into the chamber of the casing. Thus, the generated vapor
in the evaporator 20 is firstly guided to the chamber of the
casing, and then the heat carried in the vapor is conducted to the
fins outside the chamber of the casing for further dissipation.
[0020] With reference to FIGS. 2-4, the evaporator 20 of the
present heat exchange device 10 has a plate-type configuration,
which includes a top cover 210 and a bottom cover 220. The top and
bottom covers 210, 220 cooperate with each other to define a
chamber (not labeled) inside the evaporator 20. The bottom cover
220 includes a first, thinner section 221 and a second, thicker
section 223 extending from the first section 221. The second
section 223 projects downwardly to an extent below the first
section 221 with a step (not labeled) formed between the first and
second sections 221, 223. As shown in FIGS. 2 and 4, a protrusion
225 is formed by extending further downwardly from a central
portion of the second section 223 of the bottom cover 220. A first
wick structure 230 is arranged inside the evaporator 20. The first
wick structure 230 defines therein a plurality of micro-channels
(not labeled) for storage of and providing passageways for the
working fluid contained in the evaporator 20. The first wick
structure 230 is preferably in the form of sintered powder or a
screen mesh made of metal wires or organic fibers woven together.
The working fluid contained in the evaporator 20 is saturated in
the first wick structure 230. The working fluid is injected into
the evaporator 20 via a small tube 203 inserted into the evaporator
20, as shown in FIG. 3. The working fluid is usually selected from
liquids such as water or alcohol. Then, the evaporator 20 is
vacuumed and the tube 203 is sealed.
[0021] Corresponding to the first and second sections 221, 223 of
the bottom cover 220 of the evaporator 20, an interior of the
chamber of the evaporator 20 is divided into two major regions,
i.e., a liquid micro-channel region 231 and an adjacent evaporating
region 232. The micro-channel region 231 is fully filled with the
first wick structure 230. A portion of the first wick structure 230
extends from the micro-channel region 231 into a middle part of the
evaporating region 232 between opposite front and rear sides of the
evaporator 20 as viewed from FIG. 3. This portion of the first wick
structure 230 has a size substantially equal to that of the
protrusion 225 of the bottom cover 220, and is fittingly located
above that protrusion 225. Additionally, another portion of the
first wick structure 230 also extends from the micro-channel region
231 into opposite front and rear sides of the evaporating region
232. As a result, the first wick structure 230 spans across both
the micro-channel region 231 and the evaporating region 232 of the
chamber of the evaporator 20. The vapor and liquid conduits 30, 50
are connected to the evaporating region 232 and the micro-channel
region 231, respectively. The remaining part of the evaporating
region 232 not filled with the first wick structure 230 functions
as a vapor-gathering section 233 for accommodating the generated
vapor. This vapor-gathering section 233 is communicated with the
vapor conduit 30 so as to enable the generated vapor to leave the
evaporator 20 and go into the vapor conduit 30. Additionally,
corresponding to the micro-channel region 231, each of the top and
bottom covers 210, 220 of the evaporator 20 has a plurality of
metal fins 250 extending from an outer surface thereof, as shown in
FIG. 2.
[0022] Preferably, a second wick structure 501 is arranged against
an inner surface of the liquid conduit 50 in order to bring the
condensate resulting from the vapor back from the condenser 40 to
the evaporator 20 timely, as shown in FIG. 3. The second wick
structure 501 may be fine grooves integrally formed at the inner
surface of the liquid conduit 50, screen mesh or bundles of fiber
inserted into the liquid conduit 50, or sintered powder combined to
the inner surface of the liquid conduit 50 by a sintering process.
Thus, the condensate in the condenser 40 is capable of being timely
sent back to the evaporator 20 under a capillary force developed by
the second wick structure 501, thereby avoiding the potential
dry-out problem occurring at the evaporator 20.
[0023] In operation, the protrusion 225 of the evaporator 20 is
maintained into thermal contact with the heat source. Preferably, a
layer of thermal interface material is applied over their
contacting surfaces in order to reduce thermal resistance. The heat
generated by the heat source is firstly transferred to the
projected second section 223 of the bottom cover 220 and then to
the evaporating region 232 of the chamber of the evaporator 20 to
cause the working fluid contained in that region to evaporate into
the vapor after absorbing the heat from the heat source. Since the
micro-channel region 231 is filled with the first wick structure
230, the generated vapor then enters into the vapor-gathering
section 233 for temporary storage. Thereafter, due to the
difference of vapor pressure between the evaporator 20 and the
condenser 40, the vapor accordingly goes into the vapor conduit 30
and moves towards the condenser 40. After the vapor releases its
latent heat in the condenser 40 and turns into the condensate, the
condensate is then rapidly drawn back to the micro-channel region
231 of the chamber of the evaporator 20 via the liquid conduit 50
due to the capillary force of the second wick structure 501. Since
an inventory of working fluid in the evaporating region 232 is
reduced due to the evaporation in that region, the condensate
returned to the micro-channel region 231 is subsequently drawn to
the evaporating region 232 for being available again for
evaporation as a result of the capillary force developed by the
first wick structure 230, thus forming the heat transfer loop for
continuously and effectively removing the heat generated by the
heat source. In the present heat exchange device 10, the working
fluid takes the heat away from the heat source specially in the
unidirectional, circular manner along the heat transfer loop, when
the working fluid continuously undergoes phase transitions from
liquid to vapor and then from vapor to liquid (condensate). Due to
the presence of the first wick structure 230 in the micro-channel
region 231, which is saturated by the condensate, the vapor
generated in the evaporating region 232 is prevented from moving
towards the micro-channel region 231 and proceeding therefrom to
the liquid conduit 50.
[0024] In order to reduce an amount of vapor to be formed and
accumulated in the micro-channel region 231, it is preferred to
prevent the condensate returned to and stored in that region from
being directly heated and evaporated into vapor, since the thus
generated vapor will accumulate in that region and accordingly
produce a large resistance to the flow of the condensate towards
the evaporating region 232. If the condensate is not timely sent to
the evaporating region 232 due to the resistance of the vapor
accumulated in the micro-channel region 231, a dry-out problem will
be raised in the evaporating region 232. On the other hand, the
vapor accumulated in the micro-channel region 231 will also has the
chance to enter into and march along the liquid conduit 50, which
will disorder the heat transfer mechanism along the heat transfer
loop established by the present heat exchange device 10. In the
present heat exchange device 10, the heat coming from the heat
source is directly transferred to the second, thicker section 223
of the bottom cover 220. The two-section design of the bottom cover
220 is aimed to reduce an amount of the heat from the heat source
to be conducted from the second, thicker section 223 to the thinner
first section 221 and finally to the micro-channel region 231 of
the evaporator 20. Since the second, thicker section 223 has a
larger thickness than the first section 221, the heat conducted
laterally from the second, thicker section 223 towards the first
section 221 is thus capable of being effectively reduced. As a
result, the heat transferred from the first section 221 of the
bottom cover 220 to the micro-channel region 231 of the evaporator
20 is also effectively reduced, and thus excessive vapor is
prevented from being formed and accumulated in that region. The
condensate temporarily stored in the micro-channel region 231 is
accordingly capable of being timely supplied to the evaporating
region 232.
[0025] Since the micro-channel region 231 is connected with the
adjacent evaporating region 232, a portion of the vapor generated
in the evaporating region 232 will "creep" from the evaporating
region 232 into the micro-channel region 231 due to a large vapor
pressure in the vapor-gathering section 233. That is, a specific
amount of the vapor generated in the evaporating region 232 will
gradually move towards and enter into the micro-channel region 231
due to the large vapor pressure. In addition, the temperature in
the micro-channel region 231 will also gradually increase, subject
to a relatively high temperature and a flow of the vapor in the
evaporating region 232. Thus, in order to reduce the vapor to be
brought into and accumulated in the micro-channel region 231 to a
minimum amount, it is also preferred to lower the temperature in
the micro-channel region 231. In the present heat exchange device
10, the metal fins 250 formed on the top and bottom covers 210, 220
of the evaporator 20 corresponding to the micro-channel region 231
are applied to directly condense that portion of vapor having crept
into the micro-channel region 231 into condensate at that region
and on the other hand to maintain a relatively low temperature for
the micro-channel region 231. In practice, the metal fins 250 may
be substituted with other cooling devices such as cooling fans or
thermoelectric cooling devices. The metal fins 250 preferably have
a low height and are integrally formed with the top and bottom
covers 210, 220 so as to minimize the size of the evaporator
20.
[0026] In the present heat exchange device 10, the condensate
resulting from the vapor after releasing its latent heat in the
condenser 40 is sent back to the evaporator 20 for being available
again for evaporation under the capillary force developed by the
second wick structure 501 arranged in the liquid conduit 50. With
respect to the evaporator 20, the two-section design of the bottom
cover 220 and the presence of the metal fins 250 on both the top
and bottom covers 210, 220 cooperatively maintain a low temperature
for the micro-channel region 231 of the evaporator 20 and
effectively reduce the amount of vapor to be formed and accumulated
in that region, thus enabling the condensate returned to the
evaporator 20 to be supplied from the micro-channel region 231 to
the evaporating region 232 of the evaporator 20 timely and
eliminating the potential dry-out problem occurring at the
evaporating region 232. As a result, the unidirectional working
liquid movement mechanism along the heat transfer loop established
by the present heat exchange device 10 is well followed and the
heat generated by the heat source is taken away effectively.
[0027] FIG. 5 shows a loop-type heat exchange device (not labeled)
in accordance with a second embodiment of the present invention. In
this embodiment, the heat exchange device is provided with two heat
transfer loops in order to increase its heat removal capacity, thus
making it applicable for removing heat from heat-generating
components with a high cooling requirement.
[0028] FIG. 6 shows a loop-type heat exchange device (not labeled)
in accordance with a third embodiment of the present invention. In
this embodiment, the heat exchange device includes two heat
transfer loops and in each heat transfer loop two vapor conduits 30
are provided so as to reduce a resistance to the vapor generated in
the evaporator 20 as it flows towards the condenser 40. To attain
this purpose (i.e., reducing resistance to the vapor), the vapor
conduit 30 may also be made to have a larger diameter than the
liquid conduit 50 so as to enable the generated vapor to move
towards the condenser 40 effectively and smoothly.
[0029] It is to be understood, however, that even though numerous
characteristics and advantages of the present invention have been
set forth in the foregoing description, together with details of
the structure and function of the invention, the disclosure is
illustrative only, and changes may be made in detail, especially in
matters of shape, size, and arrangement of parts within the
principles of the invention to the full extent indicated by the
broad general meaning of the terms in which the appended claims are
expressed.
* * * * *