U.S. patent application number 10/881980 was filed with the patent office on 2005-09-29 for interwoven manifolds for pressure drop reduction in microchannel heat exchangers.
This patent application is currently assigned to Cooligy,Inc.. Invention is credited to Corbin, David, Goodson, Kenneth, Kenny, Thomas W., Munch, Mark, Shook, James Gill, Upadhya, Girish, Zhou, Peng.
Application Number | 20050211417 10/881980 |
Document ID | / |
Family ID | 36001745 |
Filed Date | 2005-09-29 |
United States Patent
Application |
20050211417 |
Kind Code |
A1 |
Upadhya, Girish ; et
al. |
September 29, 2005 |
Interwoven manifolds for pressure drop reduction in microchannel
heat exchangers
Abstract
A microchannel heat exchanger coupled to a heat source and
configured for cooling the heat source comprising a first set of
fingers for providing fluid at a first temperature to a heat
exchange region, wherein fluid in the heat exchange region flows
toward a second set of fingers and exits the heat exchanger at a
second temperature, wherein each finger is spaced apart from an
adjacent finger by an appropriate dimension to minimize pressure
drop in the heat exchanger and arranged in parallel. The
microchannel heat exchanger includes an interface layer having the
heat exchange region. Preferably, a manifold layer includes the
first set of fingers and the second set of fingers configured
within to cool hot spots in the heat source. Alternatively, the
interface layer includes the first set and second set of fingers
configured along the heat exchange region.
Inventors: |
Upadhya, Girish; (Mountain
View, CA) ; Kenny, Thomas W.; (San Carlos, CA)
; Zhou, Peng; (Albany, CA) ; Munch, Mark;
(Los Altos, CA) ; Shook, James Gill; (San Jose,
CA) ; Goodson, Kenneth; (Belmont, CA) ;
Corbin, David; (Los Altos, CA) |
Correspondence
Address: |
HAVERSTOCK & OWENS LLP
162 NORTH WOLFE ROAD
SUNNYVALE
CA
94086
US
|
Assignee: |
Cooligy,Inc.
|
Family ID: |
36001745 |
Appl. No.: |
10/881980 |
Filed: |
June 29, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10881980 |
Jun 29, 2004 |
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10439912 |
May 16, 2003 |
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60423009 |
Nov 1, 2002 |
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60442383 |
Jan 24, 2003 |
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60455729 |
Mar 17, 2003 |
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Current U.S.
Class: |
165/80.4 ;
257/E23.098 |
Current CPC
Class: |
F28D 15/0266 20130101;
F04B 19/006 20130101; F28F 3/12 20130101; F28F 13/185 20130101;
H01L 2924/00 20130101; H01L 2924/0002 20130101; F28F 2260/02
20130101; H01L 2924/0002 20130101; H01L 23/473 20130101 |
Class at
Publication: |
165/080.4 |
International
Class: |
F28F 007/00 |
Claims
What is claimed is:
1. A heat exchanger comprising: a. an interface layer for cooling a
heat source, wherein the interface layer is configured to pass
fluid therethrough and the interface layer includes a thickness
within a range of about 0.3 millimeters to about 1.0 millimeters;
and b. a manifold layer for circulating fluid to and from the
interface layer, the manifold layer having a first set fingers and
a second set of fingers, wherein the first set of fingers are
disposed in parallel with the second set of fingers and arranged to
reduce pressure drop within the heat exchanger.
2. The heat exchanger according to claim 1 wherein the fluid is in
single phase flow condition.
3. The heat exchanger according to claim 1 wherein the fluid is in
two phase flow fluid conditions.
4. The heat exchanger according to claim 1 wherein at least a
portion of the fluid undergoes a transition between single and two
phase flow conditions in the interface layer.
5. The heat exchanger according to claim 1 wherein a particular
finger in the first set is spaced apart by an appropriate dimension
from a particular finger in the second set to minimize the pressure
drop in the heat exchanger.
6. The heat exchanger according to claim 1 wherein each of the
fingers have the same length and width dimensions.
7. The heat exchanger according to claim 1 wherein at least one of
the fingers has a different dimension than the remaining
fingers.
8. The heat exchanger according to claim 1 wherein the fingers are
arranged non-periodically in at least one dimension in the manifold
layer.
9. The heat exchanger according to claim 1 wherein at least one of
the fingers has at least one varying dimension along a length of
the manifold layer.
10. The heat exchanger according to claim 1 wherein the manifold
layer includes more than three and less than 10 parallel
fingers.
11. The heat exchanger according to claim 1 wherein the fingers in
the first set and second set are alternately disposed along a
dimension of the manifold layer.
12. The heat exchanger according to claim 1 wherein the manifold
layer is configured to cool at least one interface hot spot
region.
13. The heat exchanger according to claim 1 further comprising at
least one first port in communication with the first set of
fingers, wherein fluid enters the heat exchanger through the at
least one first port.
14. The heat exchanger according to claim 13 further comprising at
least one second port in communication with the second set of
fingers, wherein fluid exits the heat exchanger through the at
least one second port.
15. The heat exchanger according to claim 1 wherein the manifold
layer is positioned above the interface layer, wherein fluid flows
downward through the first set of fingers and upward though the
second set of fingers.
16. The heat exchanger according to claim 13 further comprising a
first port passage in communication with the first port and the
first set of fingers, the first port passage configured to channel
fluid from the first port to the first set of fingers.
17. The heat exchanger according to claim 16 further comprising a
second port passage in communication with the second port and the
second set of fingers, the second port passage configured to
channel fluid from the second set of fingers to the second
port.
18. The heat exchanger according to claim 1 wherein the interface
layer is integrally formed with the heat source.
19. The heat exchanger according to claim 1 wherein the interface
layer is coupled to the heat source.
20. The heat exchanger according to claim 1 further comprising an
intermediate layer for channeling fluid to and from one or more
predetermined positions in the interface layer via at least one
conduit, the intermediate layer positioned between the interface
layer and the manifold layer.
21. The heat exchanger according to claim 20 wherein the
intermediate layer is coupled to the interface layer and the
manifold layer.
22. The heat exchanger according to claim 20 wherein the
intermediate layer is integrally formed with the interface layer
and the manifold layer.
23. The heat exchanger according to claim 20 wherein the at least
one conduit has at least one varying dimension along the
intermediate layer.
24. The heat exchanger according to claim 1 wherein the interface
layer includes a coating thereupon, wherein the coating provides an
appropriate thermal conductivity of at least 10 W/m-K.
25. The heat exchanger according to claim 1 wherein the interface
layer has a thermal conductivity of at least 100 W/m-K.
26. The heat exchanger according to claim 1 further comprising a
plurality of pillars configured in a predetermined pattern along
the interface layer.
27. The heat exchanger according to claim 26 wherein at least one
of the plurality of pillars has an area dimension within the range
of and including (10 micron).sup.2 and (100 micron).sup.2.
28. The heat exchanger according to claim 26 wherein at least one
of the plurality of pillars has a height dimension within the range
of and including 50 microns and 2 millimeters.
29. The heat exchanger according to claim 26 wherein at least two
of the plurality of pillars are separate from each other by a
spacing dimension within the range of and including 10 to 150
microns.
30. The heat exchanger according to claim 26 wherein the plurality
of pillars include a coating thereupon, wherein the coating has an
appropriate thermal conductivity of at least 10 W/m-K.
31. The heat exchanger according to claim 1 wherein the interface
layer has a roughened surface.
32. The heat exchanger according to claim 1 wherein the interface
layer includes a micro-porous structure disposed thereon.
33. The heat exchanger according to claim 32 wherein the porous
microstructure has a porosity within the range of and including 50
to 80 percent.
34. The heat exchanger according to claim 32 wherein the porous
microstructure has an average pore size within the range of and
including 10 to 200 microns.
35. The heat exchanger according to claim 32 wherein the porous
microstructure has a height dimension within the range of and
including 0.25 to 2.00 millimeters.
36. The heat exchanger according to claim 1 further comprises a
plurality of microchannels configured in a predetermined pattern
along the interface layer.
37. The heat exchanger according to claim 36 wherein at least one
of the plurality of microchannels has an area dimension within the
range of and including (10 micron).sup.2 and (100
micron).sup.2.
38. The heat exchanger according to claim 36 wherein at least one
of the plurality of microchannels has a height dimension within the
range of and including 50 microns and 2 millimeters.
39. The heat exchanger according to claim 36 wherein at least two
of the plurality of microchannels are separate from each other by a
spacing dimension within the range of and including 10 to 150
microns.
40. The heat exchanger according to claim 36 wherein at least one
of the plurality of microchannels has a width dimension within the
range of and including 10 to 100 microns.
41. The heat exchanger according to claim 36 wherein the plurality
of microchannels are coupled to the interface layer.
42. The heat exchanger according to claim 36 wherein the plurality
of microchannels are integrally formed with the interface
layer.
43. The heat exchanger according to claim 36 wherein the plurality
of microchannels are divided into segmented arrays with at least
one groove disposed therebetween, wherein the at least one groove
is aligned with a corresponding finger.
44. The heat exchanger according to claim 36 wherein the plurality
of microchannels include a coating thereupon, wherein the coating
has an appropriate thermal conductivity of at least 10 W/m-K.
45. The heat exchanger according to claim 1 wherein an overhang
dimension is within the range of and including 0 to 15
millimeters.
46. A heat exchanger for cooling a heat source comprising: a. a
manifold layer including a first set of fingers in a first
configuration, wherein each finger in the first set channels fluid
at a first temperature, the manifold layer further including a
second set of fingers in a second configuration, wherein each
finger in the second set channels fluid at a second temperature,
the first set and second set of fingers arranged parallel to each
other; and b. an interface layer including a thickness within a
range of about 0.3 to 1.0 millimeters, and configured to receive
fluid at the first temperature at a plurality of first locations,
wherein each first location is associated with a corresponding
finger in the first set, the interface layer passing fluid along a
plurality of predetermined paths to a plurality of second
locations, wherein each second location is associated with a
corresponding finger in the second set.
47. The heat exchanger according to claim 46 wherein the fluid is
in single phase flow conditions.
48. The heat exchanger according to claim 46 wherein the fluid is
in two phase flow conditions.
49. The heat exchanger according to claim 46 wherein at least a
portion of the fluid undergoes a transition between single and two
phase flow conditions in the interface layer.
50. The heat exchanger according to claim 46 wherein a particular
finger in the first set is spaced apart by an appropriate dimension
from a particular finger in the second set, wherein the appropriate
dimension reduces the pressure drop in the heat exchanger.
51. The heat exchanger according to claim 46 further comprising at
least one first port in communication with the first set of
fingers, wherein fluid enters the heat exchanger through the at
least one first port.
52. The heat exchanger according to claim 51 further comprising at
least one second port in communication with the second set of
fingers, wherein fluid exits the heat exchanger through the at
least one second port.
53. The heat exchanger according to claim 46 wherein the manifold
layer is positioned above the interface layer, wherein fluid flows
downward through the first set of fingers and upward through the
second set of fingers.
54. The heat exchanger according to claim 46 wherein the interface
layer is integrally formed with the heat source.
55. The heat exchanger according to claim 46 wherein the interface
layer is coupled to the heat source.
56. The heat exchanger according to claim 46 wherein the fingers in
the first set are positioned in an alternating configuration with
the fingers in the second set.
57. The heat exchanger according to claim 46 wherein each of the
fingers have the same length and width dimensions.
58. The heat exchanger according to claim 46 wherein at least one
of the fingers has a different dimension than the remaining
fingers.
59. The heat exchanger according to claim 46 wherein the fingers
are arranged non-periodically in at least one dimension in the
manifold layer.
60. The heat exchanger according to claim 46 wherein at least one
of the fingers has at least one varying dimension along a length of
the manifold layer.
61. The heat exchanger according to claim 46 wherein the manifold
layer includes more than three and less than 10 parallel
fingers.
62. The heat exchanger according to claim 52 further comprising a
first port passage in communication with the first port and the
first set of fingers, the first port passage configured to channel
fluid from the first port to the first set of fingers.
63. The heat exchanger according to claim 62 further comprising a
second port passage in communication with the second port and the
second set of fingers, the second port passage configured to
channel fluid from the second set of fingers to the second
port.
64. The heat exchanger according to claim 46 further comprising an
intermediate layer for channeling fluid to and from one or more
predetermined positions in the interface layer via at least one
conduit, the intermediate layer positioned between the interface
layer and the manifold layer.
65. The heat exchanger according to claim 64 wherein the conduit is
arranged in a predetermined configuration to channel fluid to one
or more interface hot spot regions in the interface layer.
66. The heat exchanger according to claim 64 wherein the conduit is
arranged in a predetermined configuration to channel fluid from one
or more interface hot spot regions in the interface layer.
67. The heat exchanger according to claim 64 wherein the
intermediate layer is coupled to the interface layer and the
manifold layer.
68. The heat exchanger according to claim 64 wherein the
intermediate layer is integrally formed with the interface layer
and the manifold layer.
69. The heat exchanger according to claim 64 wherein the conduit
has at least one varying dimension in the intermediate layer.
70. The heat exchanger according to claim 46 wherein the interface
layer includes a coating thereupon, wherein the coating provides an
appropriate thermal conductivity of at least 10 W/m-K.
71. The heat exchanger according to claim 46 wherein the interface
layer has a thermal conductivity is at least 100 W/m-K.
72. The heat exchanger according to claim 46 further comprising a
plurality of pillars configured in a predetermined pattern along
the interface layer.
73. The heat exchanger according to claim 72 wherein at least one
of the plurality of pillars has an area dimension within the range
of and including (10 micron).sup.2 and (100 micron).sup.2.
74. The heat exchanger according to claim 72 wherein at least one
of the plurality of pillars has a height dimension within the range
of and including 50 microns and 2 millimeters.
75. The heat exchanger according to claim 72 wherein at least two
of the plurality of pillars are separate from each other by a
spacing dimension within the range of and including 10 to 150
microns.
76. The heat exchanger according to claim 72 wherein the plurality
of pillars include a coating thereupon, wherein the coating has an
appropriate thermal conductivity of at least 10 W/m-K.
77. The heat exchanger according to claim 46 wherein the interface
layer has a roughened surface.
78. The heat exchanger according to claim 46 wherein the interface
layer includes a microporous structure disposed thereon.
79. The heat exchanger according to claim 78 wherein the porous
microstructure has a porosity within the range of and including 50
to 80 percent.
80. The heat exchanger according to claim 78 wherein the porous
microstructure has an average pore size within the range of and
including 10 to 200 microns.
81. The heat exchanger according to claim 78 wherein the porous
microstructure has a height dimension within the range of and
including 0.25 to 2.00 millimeters.
82. The heat exchanger according to claim 46 further comprises a
plurality of microchannels configured in a predetermined pattern
along the interface layer.
83. The heat exchanger according to claim 82 wherein at least one
of the plurality of microchannels has an area dimension within the
range of and including (10 micron).sup.2 and (100
micron).sup.2.
84. The heat exchanger according to claim 82 wherein at least one
of the plurality of microchannels has a height dimension within the
range of and including 50 microns and 2 millimeters.
85. The heat exchanger according to claim 82 wherein at least two
of the plurality of microchannels are separate from each other by a
spacing dimension within the range of and including 10 to 150
microns.
86. The heat exchanger according to claim 82 wherein at least one
of the plurality of microchannels has a width dimension within the
range of and including 10 to 100 microns.
87. The heat exchanger according to claim 82 wherein the
microchannels are coupled to the interface layer.
88. The heat exchanger according to claim 82 wherein the
microchannels are integrally formed with the interface layer.
89. The heat exchanger according to claim 82 wherein the
microchannels are divided into segments along a dimension of the
interface layer, at least one groove disposed in between the
divided microchannel segments.
90. The heat exchanger according to claim 82 wherein the
microchannels are continuous along a dimension of the interface
layer.
91. The heat exchanger according to claim 89 wherein the at least
one groove is aligned with a corresponding finger.
92. The heat exchanger according to claim 82 wherein the plurality
of microchannels include a coating thereupon, wherein the coating
has an appropriate thermal conductivity of at least 10 W/m-K.
93. The heat exchanger according to claim 46 wherein an overhang
dimension is within the range of and including 0 to 15 millimeters.
Description
RELATED APPLICATIONS
[0001] This Patent application is a continuation in part of U.S.
patent application Ser. No. 10/439,912, filed May 16, 2003, and
entitled "INTERWOVEN MANIFOLDS FOR PRESSURE DROP REDUCTION IN
MICROCHANNEL HEAT EXCHANGERS", hereby incorporated by reference,
which claims priority under 35 U.S.C. 119 (e) of the co-pending
U.S. Provisional Patent Application Ser. No. 60/423,009, filed Nov.
1, 2002 and entitled "METHODS FOR FLEXIBLE FLUID DELIVERY AND
HOTSPOT COOLING BY MICROCHANNEL HEAT SINKS" which is hereby
incorporated by reference, as well as co-pending U.S. Provisional
Patent Application Ser. No. 60/442,383, filed Jan. 24, 2003 and
entitled "OPTIMIZED PLATE FIN HEAT EXCHANGER FOR CPU COOLING" which
is also hereby incorporated by reference, and co-pending U.S.
Provisional Patent Application Ser. No. 60/455,729, filed Mar. 17,
2003 and entitled "MICROCHANNEL HEAT EXCHANGER APPARATUS WITH
POROUS CONFIGURATION AND METHOD OF MANUFACTURING THEREOF", which is
hereby incorporated by reference.
FIELD OF THE INVENTION
[0002] The invention relates to a method and apparatus for cooling
a heat producing device in general, and specifically, to an
interwoven manifold for pressure drop reduction in a microchannel
heat exchanger.
BACKGROUND OF THE INVENTION
[0003] Since their introduction in the early 1980s, microchannel
heat sinks have shown much potential for high heat-flux cooling
applications and have been used in the industry. However, existing
microchannels include conventional parallel channel arrangements
which are used are not well suited for cooling heat producing
devices which have spatially-varying heat loads. Such heat
producing devices have areas which produce more heat than others.
These hotter areas are hereby designated as "hot spots" whereas the
areas of the heat source which do not produce as much heat are
hereby termed, "warm spots".
[0004] FIG. 1A illustrates a prior art heat exchanger 10 which is
coupled to an electronic device 99, such as a microprocessor via a
thermal interface material 98. As shown in FIG. 1A, fluid generally
flows from a single inlet port 12 and flows along the bottom
surface 11 in between the parallel microchannels 14, as shown by
the arrows, and exits through the outlet port 16. Although the heat
exchanger 10 cools the electronic device 99, the fluid flows from
the inlet port 12 to the outlet port 16 in a uniform manner. In
other words, the fluid flows substantially uniformly along the
entire bottom surface 11 of the heat exchanger 10 and does not
supply more fluid to areas in the bottom surface 11 which
correspond with hot spots in the device 99. In addition, the
temperature of liquid flowing from the inlet generally increases as
it flows along the bottom surface 11 of the heat exchanger.
Therefore, regions of the heat source 99 which are downstream or
near the outlet port 16 are not supplied with cool fluid, but
actually fluid which has already been heated upstream. In effect,
the heated fluid actually propagates the heat across the entire
bottom surface 11 of the heat exchanger and region of the heat
source 99, whereby fluid near the outlet port 16 is so hot that it
becomes ineffective in cooling heat source. In addition, the heat
exchanger 10 having only one inlet 12 and one outlet 16 forces
fluid to travel along the long parallel microchannels 14 in the
bottom surface 11 for the entire length of the heat exchanger 10,
thereby creating a large pressure drop.
[0005] FIG. 1B illustrates a side view diagram of a prior art
multi-level heat exchanger 20. Fluid enters the multi-level heat
exchanger 20 through the port 22 and travels downward through
multiple jets 28 in the middle layer 26 to the bottom surface 27
and out port 24. In addition, the fluid traveling along the jets 28
may or may not uniformly flow down to the bottom surface 27.
Nonetheless, although the fluid entering the heat exchanger 20 is
spread over the length of the heat exchanger 20, the design does
not provide more fluid to the hotter areas of the heat exchanger 20
and heat source that are in need of more fluid flow
circulation.
[0006] In addition, conventional heat exchangers are made of
materials which have high thermal resistance in the bottom surface,
such that the heat exchanger has a coefficient of thermal expansion
which matches that of the heat source 99. The high thermal
resistance of the heat exchanger thereby does not allow sufficient
heat exchange with the heat source 99. To account for the high
thermal resistance, larger channel cross-sectional areas are chosen
such that more thermal exchange occurs between the heat exchanger
10 and the heat source 99. In addition, the dimensions of the
channels in the heat exchanger are scaled down and the distance
between the channel walls and the hydraulic diameter is made
smaller, the thermal resistance of the heat exchanger is reduced.
However, a problem with using narrow microchannels is the increase
in pressure drop along the channels. The increase in pressure drop
places extreme demands on a pump driving the fluid through the heat
exchanger. In addition, larger microchannel dimensions also cause a
larger pressure drop between the inlet and outlet ports, due to the
long distance that one or two phase fluid must travel. Further,
boiling of the fluid in a microchannel heat exchanger causes a
larger pressure drop for a given flowrate due to the mixing of
fluid and vapor as well as the acceleration of the fluid into the
vapor phase. Both of these factors increase the pressure drop per
unit length. The large pressure drop created within the current
microchannel heat exchangers require larger pumps which can handle
higher pressures and thereby are not feasible in a microchannel
setting.
[0007] What is needed is a microchannel heat exchanger which is
configured to achieve proper temperature uniformity in the heat
source. What is also needed is a heat exchanger which is configured
to achieve proper uniformity in light of hot spots in the heat
source. What is also needed is a heat exchanger having a relatively
high thermal conductivity to adequately perform thermal exchange
with the heat source. What is further needed is a heat exchanger
which is configured to achieve a small pressure drop between the
inlet and outlet fluid ports.
SUMMARY OF THE INVENTION
[0008] In one aspect of the invention, a heat exchanger comprises
an interface layer for cooling a heat source, wherein the interface
layer is configured to pass fluid therethrough and the interface
layer includes a thickness within a range of about 0.3 millimeters
to about 1.0 millimeters, and a manifold layer for circulating
fluid to and from the interface layer, the manifold layer having a
first set fingers and a second set of fingers, wherein the first
set of fingers are disposed in parallel with the second set of
fingers and arranged to reduce pressure drop within the heat
exchanger. The fluid can be in single phase flow condition. The
fluid can be in two phase flow fluid conditions. At least a portion
of the fluid can undergo a transition between single and two phase
flow conditions in the interface layer. A particular finger in the
first set can be spaced apart by an appropriate dimension from a
particular finger in the second set to minimize the pressure drop
in the heat exchanger. Each of the fingers can have the same length
and width dimensions. At least one of the fingers can have a
different dimension than the remaining fingers. The fingers can be
arranged non-periodically in at least one dimension in the manifold
layer. At least one of the fingers can have at least one varying
dimension along a length of the manifold layer. The manifold layer
can include more than three and less than 10 parallel fingers. The
fingers in the first set and second set can be alternately disposed
along a dimension of the manifold layer. The manifold layer can be
configured to cool at least one interface hot spot region. The heat
exchanger can also include at least one first port in communication
with the first set of fingers, wherein fluid enters the heat
exchanger through the at least one first port. The heat exchanger
can also include at least one second port in communication with the
second set of fingers, wherein fluid exits the heat exchanger
through the at least one second port. The manifold layer can be
positioned above the interface layer, wherein fluid flows downward
through the first set of fingers and upward though the second set
of fingers. The heat exchanger can also include a first port
passage in communication with the first port and the first set of
fingers, the first port passage configured to channel fluid from
the first port to the first set of fingers. The heat exchanger can
also include a second port passage in communication with the second
port and the second set of fingers, the second port passage
configured to channel fluid from the second set of fingers to the
second port. The interface layer can be integrally formed with the
heat source. The interface layer can be coupled to the heat source.
The heat exchanger can also include an intermediate layer for
channeling fluid to and from one or more predetermined positions in
the interface layer via at least one conduit, the intermediate
layer positioned between the interface layer and the manifold
layer. The intermediate layer can be coupled to the interface layer
and the manifold layer. The intermediate layer can be integrally
formed with the interface layer and the manifold layer. The at
least one conduit can have at least one varying dimension along the
intermediate layer. The interface layer can include a coating
thereupon, wherein the coating provides an appropriate thermal
conductivity of at least 10 W/m-K. The interface layer can have a
thermal conductivity of at least 100 W/m-K. The heat exchanger can
also include a plurality of pillars configured in a predetermined
pattern along the interface layer. At least one of the plurality of
pillars can have an area dimension within the range of and
including (10 micron).sup.2 and (100 micron).sup.2. At least one of
the plurality of pillars can have a height dimension within the
range of and including 50 microns and 2 millimeters. At least two
of the plurality of pillars can be separate from each other by a
spacing dimension within the range of and including 10 to 150
microns. The plurality of pillars can include a coating thereupon,
wherein the coating has an appropriate thermal conductivity of at
least 10 W/m-K. The interface layer can have a roughened surface.
The interface layer can include a micro-porous structure disposed
thereon. The porous microstructure can have a porosity within the
range of and including 50 to 80 percent. The porous microstructure
can have an average pore size within the range of and including 10
to 200 microns. The porous microstructure can have a height
dimension within the range of and including 0.25 to 2.00
millimeters. The heat exchanger can also include a plurality of
microchannels configured in a predetermined pattern along the
interface layer. At least one of the plurality of microchannels can
have an area dimension within the range of and including (10
micron).sup.2 and (100 micron).sup.2. At least one of the plurality
of microchannels can have a height dimension within the range of
and including 50 microns and 2 millimeters. At least two of the
plurality of microchannels can be separate from each other by a
spacing dimension within the range of and including 10 to 150
microns. At least one of the plurality of microchannels can have a
width dimension within the range of and including 10 to 100
microns. The plurality of microchannels can be coupled to the
interface layer. The plurality of microchannels can be integrally
formed with the interface layer. The plurality of microchannels can
be divided into segmented arrays with at least one groove disposed
therebetween, wherein the at least one groove is aligned with a
corresponding finger. The plurality of microchannels can include a
coating thereupon, wherein the coating has an appropriate thermal
conductivity of at least 10 W/m-K. An overhang dimension can be
within the range of and including 0 to 15 millimeters.
[0009] In another aspect of the present invention, a heat exchanger
for cooling a heat source comprises a manifold layer including a
first set of fingers in a first configuration, wherein each finger
in the first set channels fluid at a first temperature, the
manifold layer further including a second set of fingers in a
second configuration, wherein each finger in the second set
channels fluid at a second temperature, the first set and second
set of fingers arranged parallel to each other, and an interface
layer including a thickness within a range of about 0.3 to 1.0
millimeters, and configured to receive fluid at the first
temperature at a plurality of first locations, wherein each first
location is associated with a corresponding finger in the first
set, the interface layer passing fluid along a plurality of
predetermined paths to a plurality of second locations, wherein
each second location is associated with a corresponding finger in
the second set. The fluid can be in single phase flow conditions.
The fluid can be in two phase flow conditions. At least a portion
of the fluid can undergo a transition between single and two phase
flow conditions in the interface layer. A particular finger in the
first set can be spaced apart by an appropriate dimension from a
particular finger in the second set, wherein the appropriate
dimension reduces the pressure drop in the heat exchanger. The heat
exchanger can also include at least one first port in communication
with the first set of fingers, wherein fluid enters the heat
exchanger through the at least one first port. The heat exchanger
can also include at least one second port in communication with the
second set of fingers, wherein fluid exits the heat exchanger
through the at least one second port. The manifold layer can be
positioned above the interface layer, wherein fluid flows downward
through the first set of fingers and upward through the second set
of fingers. The interface layer can be integrally formed with the
heat source. The interface layer can be coupled to the heat source.
The fingers in the first set can be positioned in an alternating
configuration with the fingers in the second set. Each of the
fingers can have the same length and width dimensions. At least one
of the fingers can have a different dimension than the remaining
fingers. The fingers can be arranged non-periodically in at least
one dimension in the manifold layer. At least one of the fingers
can have at least one varying dimension along a length of the
manifold layer. The manifold layer can include more than three and
less than 10 parallel fingers. The heat exchanger can also include
a first port passage in communication with the first port and the
first set of fingers, the first port passage configured to channel
fluid from the first port to the first set of fingers. The heat
exchanger can also include a second port passage in communication
with the second port and the second set of fingers, the second port
passage configured to channel fluid from the second set of fingers
to the second port. The heat exchanger can also include an
intermediate layer for channeling fluid to and from one or more
predetermined positions in the interface layer via at least one
conduit, the intermediate layer positioned between the interface
layer and the manifold layer. The conduit can be arranged in a
predetermined configuration to channel fluid to one or more
interface hot spot regions in the interface layer. The conduit can
be arranged in a predetermined configuration to channel fluid from
one or more interface hot spot regions in the interface layer. The
intermediate layer can be coupled to the interface layer and the
manifold layer. The intermediate layer can be integrally formed
with the interface layer and the manifold layer. The conduit can
have at least one varying dimension in the intermediate layer. The
interface layer can include a coating thereupon, wherein the
coating provides an appropriate thermal conductivity of at least 10
W/m-K. The interface layer can have a thermal conductivity is at
least 10 W/m-K. The heat exchanger can also include a plurality of
pillars configured in a predetermined pattern along the interface
layer. At least one of the plurality of pillars can have an area
dimension within the range of and including (10 micron).sup.2 and
(100 micron).sup.2. At least one of the plurality of pillars can
have a height dimension within the range of and including 50
microns and 2 millimeters. At least two of the plurality of pillars
can be separate from each other by a spacing dimension within the
range of and including 10 to 150 microns. The plurality of pillars
can include a coating thereupon, wherein the coating has an
appropriate thermal conductivity of at least 10 W/m-K. The
interface layer can have a roughened surface. The interface layer
can include a micro-porous structure disposed thereon. The porous
microstructure can have a porosity within the range of and
including 50 to 80 percent. The porous microstructure can have an
average pore size within the range of and including 10 to 200
microns. The porous microstructure can have a height dimension
within the range of and including 0.25 to 2.00 millimeters. The
heat exchanger can also include a plurality of microchannels
configured in a predetermined pattern along the interface layer. At
least one of the plurality of microchannels can have an area
dimension within the range of and including (10 micron).sup.2 and
(100 micron).sup.2. At least one of the plurality of microchannels
can have a height dimension within the range of and including 50
microns and 2 millimeters. At least two of the plurality of
microchannels can be separate from each other by a spacing
dimension within the range of and including 10 to 150 microns. At
least one of the plurality of microchannels can have a width
dimension within the range of and including 10 to 100 microns. The
microchannels can be coupled to the interface layer. The
microchannels can be integrally formed with the interface layer.
The microchannels can be divided into segments along a dimension of
the interface layer, at least one groove disposed in between the
divided microchannel segments. The microchannels can be continuous
along a dimension of the interface layer. The at least one groove
can be aligned with a corresponding finger. The plurality of
microchannels can include a coating thereupon, wherein the coating
has an appropriate thermal conductivity of at least 20 W/m-K. An
overhang dimension can be within the range of and including 0 to 15
millimeters.
[0010] Other features and advantages of the present invention will
become apparent after reviewing the detailed description of the
preferred embodiments set forth below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1A illustrates a side view of a conventional heat
exchanger.
[0012] FIG. 1B illustrates a top view of the conventional heat
exchanger.
[0013] FIG. 1C illustrates a side view diagram of a prior art
multi-level heat exchanger.
[0014] FIG. 2A illustrates a schematic diagram of a closed loop
cooling system incorporating a preferred embodiment of the flexible
fluid delivery microchannel heat exchanger of the present
invention.
[0015] FIG. 2B illustrates a schematic diagram of a closed loop
cooling system incorporating an alternative embodiment of the
flexible fluid delivery microchannel heat exchanger of the present
invention.
[0016] FIG. 3A illustrates a top view of an alternative manifold
layer of the heat exchanger in accordance with the present
invention.
[0017] FIG. 3B illustrates an exploded view of an alternative heat
exchanger with the alternative manifold layer in accordance with
the present invention.
[0018] FIG. 4 illustrates a perspective view of the preferred
interwoven manifold layer in accordance with the present
invention.
[0019] FIG. 5 illustrates a top view of the preferred interwoven
manifold layer with interface layer in accordance with the present
invention.
[0020] FIG. 6A illustrates a cross-sectional view of the preferred
interwoven manifold layer with interface layer of the present
invention along lines A-A.
[0021] FIG. 6B illustrates a cross-sectional view of the preferred
interwoven manifold layer with interface layer of the present
invention along lines B-B.
[0022] FIG. 6C illustrates a cross-sectional view of the preferred
interwoven manifold layer with interface layer of the present
invention along lines C-C.
[0023] FIG. 7A illustrates an exploded view of the preferred
interwoven manifold layer with interface layer of the present
invention.
[0024] FIG. 7B illustrates a perspective view of an alternative
embodiment of the interface layer of the present invention.
[0025] FIG. 8A illustrates a top view diagram of an alternate
manifold layer in accordance with the present invention.
[0026] FIG. 8B illustrates a top view diagram of the interface
layer in accordance with the present invention.
[0027] FIG. 8C illustrates a top view diagram of the interface
layer in accordance with the present invention.
[0028] FIG. 9A illustrates a side view diagram of the alternative
embodiment of the three tier heat exchanger in accordance with the
present invention.
[0029] FIG. 9B illustrates a side view diagram of the alternative
embodiment of the two tier heat exchanger in accordance with the
present invention.
[0030] FIG. 10 illustrates a perspective view of the interface
layer having a micro-pin array in accordance with the present
invention.
[0031] FIG. 11 illustrates a cut-away perspective view diagram of
the alternate heat exchanger in accordance with the present
invention.
[0032] FIG. 12 illustrates a side view diagram of the interface
layer of the heat exchanger having a coating material applied
thereon in accordance with the present invention.
[0033] FIG. 13 illustrates a flow chart of an alternative method of
manufacturing the heat exchanger in accordance with the present
invention.
[0034] FIG. 14 illustrates a schematic of an alternate embodiment
of the present invention having two heat exchangers coupled to a
heat source.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0035] Generally, the heat exchanger captures thermal energy
generated from a heat source by passing fluid through selective
areas of the interface layer which is preferably coupled to the
heat source. In particular, the fluid is directed to specific areas
in the interface layer to cool the hot spots and areas around the
hot spots to generally create temperature uniformity across the
heat source while maintaining a small pressure drop within the heat
exchanger. As discussed in the different embodiments below, the
heat exchanger utilizes a plurality of apertures, channels and/or
fingers in the manifold layer as well as conduits in the
intermediate layer to direct and circulate fluid to and from
selected hot spot areas in the interface layer. Alternatively, the
heat exchanger includes several ports which are specifically
disposed in predetermined locations to directly deliver fluid to
and remove fluid from the hot spots to effectively cool the heat
source.
[0036] It is apparent to one skilled in the art that although the
microchannel heat exchanger of the present invention is described
and discussed in relation to flexible fluid delivery for cooling
hot spot locations in a device, the heat exchanger is alternatively
used for flexible fluid delivery for heating a cold spot location
in a device. It should also be noted that although the present
invention is preferably described as a microchannel heat exchanger,
the present invention can be used in other applications and is not
limited to the discussion herein.
[0037] FIG. 2A illustrates a schematic diagram of a closed loop
cooling system 30 which includes a preferred flexible fluid
delivery microchannel heat exchanger 400 in accordance with the
present invention. In addition, FIG. 2B illustrates a schematic
diagram of a closed loop cooling system 30 which includes an
alternative flexible fluid delivery microchannel heat exchanger 200
with multiple ports 108, 109 in accordance with the present
invention.
[0038] As shown in FIG. 2A, the fluid ports 108, 109 are coupled to
fluid lines 38 which are coupled to a pump 32 and heat condensor
30. The pump 32 pumps and circulates fluid within the closed loop
30. It is preferred that one fluid port 108 is used to supply fluid
to the heat exchanger 100. In addition, it is preferred that one
fluid port 109 is used to remove fluid from the heat exchanger 100.
Preferably a uniform, constant amount of fluid flow enters and
exits the heat exchanger 100 via the respective fluid ports 108,
109. Alternatively, different amounts of fluid flow enter and exit
through the inlet and outlet port(s) 108, 109 at a given time.
Alternatively, as shown in FIG. 2B, one pump provides fluid to
several designated inlet ports 108. Alternatively, multiple pumps
(not shown), provide fluid to their respective inlet and outlet
ports 108, 109. In addition, the dynamic sensing and control module
34 is alternatively employed in the system to variate and
dynamically control the amount and flow rate of fluid entering and
exiting the preferred or alternative heat exchanger in response to
varying hot spots or changes in the amount of heat in a hot spot
location as well as the locations of the hot spots.
[0039] The preferred embodiment is a three level heat exchanger 400
which includes an interface layer 402, at least one intermediate
layer 404 and at least one manifold layer 406. The preferred
manifold layer 402 and the preferred interface layer 402 are shown
in FIG. 7 and the intermediate layer 104 is shown in FIG. 3B.
Alternatively, as discussed below, the heat exchanger 400 is a two
level apparatus which includes the interface layer 402 and the
manifold layer 406, as shown in FIG. 7. As shown in FIGS. 2A and
2B, the heat exchanger 400 is coupled to a heat source 99, such as
an electronic device, including, but not limited to a microchip and
integrated circuit, whereby a thermal interface material 98 is
preferably disposed between the heat source 99 and the heat
exchanger 100. Alternatively, the heat exchanger 400 is directly
coupled to the surface of the heat source 99. It is also apparent
to one skilled in the art that the heat exchanger 400 is
alternatively integrally formed into the heat source 99, whereby
the heat exchanger 400 and the heat source 99 are formed as one
piece. Thus, the interface layer 102 is integrally disposed with
the heat source 99 and is formed as one piece with the heat
source.
[0040] It is preferred that the heat exchanger 400 of the present
invention is configured to be directly or indirectly in contact
with the heat source 99 which is rectangular in shape, as shown in
the figures. However, it is apparent to one skilled in the art that
the heat exchanger 400 can have any other shape conforming with the
shape of the heat source 99. For example, the heat exchanger of the
present invention can be configured to have an outer semicircular
shape which allows the heat exchanger (not shown) to be in direct
or indirect contact with a corresponding semicircular shaped heat
source (not shown). In addition, it is preferred that the heat
exchanger 400 is slightly larger in dimension than the heat source
within the range of and including 0.5-5.0 millimeters.
[0041] FIG. 3A illustrates a top view of the alternate manifold
layer 106 of the present invention. In particular, as shown in FIG.
3B, the manifold layer 106 includes four sides as well as a top
surface 130 and a bottom surface 132. However, the top surface 130
is removed in FIG. 3A to adequately illustrate and describe the
workings of the manifold layer 106. As shown in FIG. 3A, the
manifold layer 106 has a series of channels or passages 1116, 118,
120, 122 as well as ports 108, 109 formed therein. The fingers
1118, 120 extend completely through the body of the manifold layer
106 in the Z-direction as shown in FIG. 3B. Alternatively, the
fingers 118 and 120 extend partially through the manifold layer 106
in the Z-direction and have apertures as shown in FIG. 3A. In
addition, passages 116 and 122 extend partially through the
manifold layer 106. The remaining areas between the inlet and
outlet passages 116, 120, designated as 107, extend from the top
surface 130 to the bottom surface 132 and form the body of the
manifold layer 106.
[0042] As shown in FIG. 3A, the fluid enters manifold layer 106 via
the inlet port 108 and flows along the inlet channel 116 to several
fingers 118 which branch out from the channel 116 in several
directions in the X and/or Y directions to apply fluid to selected
regions in the interface layer 102. The fingers 118 are arranged in
different predetermined directions to deliver fluid to the
locations in the interface layer 102 corresponding to the areas at
or near the hot spots in the heat source. These locations in the
interface layer 102 are hereinafter referred to as interface hot
spot regions. The fingers are configured to cool stationary as well
as temporally varying interface hot spot regions. As shown in FIG.
3A, the channels 116, 122 and fingers 118, 120 are disposed in the
X and/or Y directions in the manifold layer 106. Thus, the various
directions of the channels 116, 122 and fingers 1118, 120 allow
delivery of fluid to cool hot spots in the heat source 99 and/or
minimize pressure drop within the heat exchanger 100.
Alternatively, channels 116, 122 and fingers 1118, 120 are
periodically disposed in the manifold layer 106 and exhibit a
pattern, as in the preferred embodiment.
[0043] The arrangement as well as the dimensions of the fingers
118, 120 are determined in light of the hot spots in the heat
source 99 that are desired to be cooled. The locations of the hot
spots as well as the amount of heat produced near or at each hot
spot are used to configure the manifold layer 106 such that the
fingers 118, 120 are placed above or proximal to the interface hot
spot regions in the interface layer 102. The manifold layer 106
preferably allows one phase and/or two-phase fluid to circulate to
the interface layer 102 without allowing a substantial pressure
drop from occurring within the heat exchanger 100 and the system 30
(FIG. 2A). The fluid delivery to the interface hot spot regions
creates a uniform temperature at the interface hot spot region as
well as areas in the heat source adjacent to the interface hot spot
regions.
[0044] The dimensions as well as the number of channels 116 and
fingers 118 depend on a number of factors. In one embodiment, the
inlet and outlet fingers 118, 120 have the same width dimensions.
Alternatively, the inlet and outlet fingers 118, 120 have different
width dimensions. The width dimensions of the fingers 118, 120 are
preferably within the range of and including 0.25-0.50 millimeters.
In one embodiment, the inlet and outlet fingers 118, 120 have the
same length and depth dimensions. Alternatively, the inlet and
outlet fingers 118, 120 have different length and depth dimensions.
In another embodiment, the inlet and outlet fingers 118, 120 have
varying width dimensions along the length of the fingers. The
length dimensions of the inlet and outlet fingers 118, 120 are
within the range of and including 0.5 millimeters to three times
the size of the heat source length. In addition, the fingers 118,
120 have a height or depth dimension within the range and including
0.25-0.50 millimeters. In addition, less than 10 or more than 30
fingers per centimeter are disposed in the manifold layer 106.
However, it is apparent to one skilled in the art that between 10
and 30 fingers per centimeter in the manifold layer is
alternatively contemplated.
[0045] It is contemplated within the present invention to tailor
the geometries of the fingers 118, 120 and channels 116, 122 to be
in non-periodic arrangement to aid in optimizing hot spot cooling
of the heat source. In order to achieve a uniform temperature
across the heat source 99, the spatial distribution of the heat
transfer to the fluid is matched with the spatial distribution of
the heat generation. As the fluid flows along the interface layer
through the microchannels 110, its temperature increases and as it
begins to transform to vapor under two-phase conditions. Thus, the
fluid undergoes a significant expansion which results in a large
increase in velocity. Generally, the efficiency of the heat
transfer from the interface layer to the fluid is improved for high
velocity flow. Therefore, it is possible to tailor the efficiency
of the heat transfer to the fluid by adjusting the cross-sectional
dimensions of the fluid delivery and removal fingers 118, 120 and
channels 116, 122 in the heat exchanger 100.
[0046] For example, a particular finger can be designed for a heat
source where there is higher heat generation near the inlet. In
addition, it may be advantageous to design a larger cross section
for the regions of the fingers 118, 120 and channels 116, 122 where
a mixture of fluid and vapor is expected. Although not shown, a
finger can be designed to start out with a small cross sectional
area at the inlet to cause high velocity flow of fluid. The
particular finger or channel can also be configured to expand to a
larger cross-section at a downstream outlet to cause a lower
velocity flow. This design of the finger or channel allows the heat
exchanger to minimize pressure drop and optimize hot spot cooling
in areas where the fluid increases in volume, acceleration and
velocity due to transformation from liquid to vapor in two-phase
flow.
[0047] In addition, the fingers 118, 120 and channels 116, 122 can
be designed to widen and then narrow again along their length to
increase the velocity of the fluid at different places in the
microchannel heat exchanger 100. Alternatively, it may be
appropriate to vary the finger and channel dimensions from large to
small and back again many times over in order to tailor the heat
transfer efficiency to the expected heat dissipation distribution
across the heat source 99. It should be noted that the above
discussion of the varying dimensions of the fingers and channels
also apply to the other embodiments discussed and is not limited to
this embodiment.
[0048] Alternatively, as shown in FIG. 3A, the manifold layer 106
includes one or more apertures 119 in the inlet fingers 118. In the
three tier heat exchanger 100, the fluid flowing along the fingers
118 flows down the apertures 119 to the intermediate layer 104.
Alternatively, in the two-tier heat exchanger 100, the fluid
flowing along the fingers 118 flows down the apertures 119 directly
to the interface layer 102. In addition, as shown in FIG. 3A. the
manifold layer 106 includes apertures 121 in the outlet fingers
120. In the three tier heat exchanger 100, the fluid flowing from
the intermediate layer 104 flows up the apertures 121 into the
outlet fingers 120. Alternatively, in the two-tier heat exchanger
100, the fluid flowing from the interface layer 102 flows directly
up the apertures 121 into the outlet fingers 120.
[0049] In the embodiment shown in FIG. 3A, the inlet and outlet
fingers 1118, 120 are open channels which do not have apertures.
The bottom surface 103 of the manifold layer 106 abuts against the
top surface of the intermediate layer 104 in the three tier
exchanger 100 or abuts against the interface layer 102 in the two
tier exchanger. Thus, in the three-tier heat exchanger 100, fluid
flows freely to and from the intermediate layer 104 and the
manifold layer 106. The fluid is directed to and from the
appropriate interface hot spot region by conduits 105 the
intermediate layer 104. It is apparent to one skilled in the art
that the conduits 105 are directly aligned with the fingers, as
described below or positioned elsewhere in the three tier
system.
[0050] FIG. 3B illustrates an exploded view of the three tier heat
exchanger 100 with the alternate manifold layer in accordance with
the present invention. Alternatively, the heat exchanger 100 is a
two layer structure which includes the manifold layer 106 and the
interface layer 102, whereby fluid passes directly between the
manifold layer 106 and interface layer 102 without passing through
the intermediate layer 104. It is apparent to one skilled in the
art that the configuration of the manifold, intermediate and
interface layers are shown for exemplary purposes and is thereby
not limited to the configuration shown.
[0051] As shown in FIG. 3B, the intermediate layer 104 includes a
plurality of conduits 105 which extend therethrough. The inflow
conduits 105 direct fluid entering from the manifold layer 106 to
the designated interface hot spot regions in the interface layer
102. Similarly, the apertures 105 also channel fluid flow from the
interface layer 102 to the exit fluid port(s) 109. Thus, the
intermediate layer 104 also provides fluid delivery from the
interface layer 102 to the exit fluid port 109 where the exit fluid
port 108 is in communication with the manifold layer 106.
[0052] The conduits 105 are positioned in the interface layer 104
in a predetermined pattern based on a number of factors including,
but not limited to, the locations of the interface hot spot
regions, the amount of fluid flow needed in the interface hot spot
region to adequately cool the heat source 99 and the temperature of
the fluid. The conduits have a width dimension of 100 microns,
although other width dimensions are contemplated up to several
millimeters. In addition, the conduits 105 have other dimensions
dependent on at least the above mentioned factors. It is apparent
to one skilled in the art that each conduit 105 in the intermediate
layer 104 has a same shape and/or dimension, although it is not
necessary. For instance, like the fingers described above, the
conduits alternatively have a varying length and/or width
dimension. Additionally, the conduits 105 may have a constant depth
or height dimension through the intermediate layer 104.
Alternatively, the conduits 105 have a varying depth dimension,
such as a trapezoidal or a nozzle-shape, through the intermediate
layer 104. Although the horizontal shape of the conduits 105 are
shown to be rectangular in FIG. 2C, the conduits 105 alternatively
have any other shape including, but not limited to, circular (FIG.
3A), curved and elliptical. Alternatively, one or more of the
conduits 105 are shaped and contour with a portion of or all of the
finger or fingers above.
[0053] The intermediate layer 104 is horizontally positioned within
the heat exchanger 100 with the conduits 105 positioned vertically.
Alternatively, the intermediate layer 104 is positioned in any
other direction within the heat exchanger 100 including, but not
limited to, diagonal and curved forms. Alternatively, the conduits
105 are positioned within the intermediate layer 104 in a
horizontally, diagonally, curved or any other direction. In
addition, the intermediate layer 104 extends horizontally along the
entire length of the heat exchanger 100, whereby the intermediate
layer 104 completely separates the interface layer 102 from the
manifold layer 106 to force the fluid to be channeled through the
conduits 105. Alternatively, a portion of the heat exchanger 100
does not include the intermediate layer 104 between the manifold
layer 106 and the interface layer 102, whereby fluid is free to
flow therebetween. Further, the intermediate layer 104
alternatively extends vertically between the manifold layer 106 and
the interface layer 102 to form separate, distinct intermediate
layer regions. Alternatively, the intermediate layer 104 does not
fully extend from the manifold layer 106 to interface layer
102.
[0054] It is preferred that the heat exchanger 100 of the present
invention is larger in width than the heat source 99. In the case
where the heat exchanger 100 is larger than the heat source 99, an
overhang dimension exists. The overhang dimension is the farthest
distance between one outer wall of the heat source 99 and the
interior fluid channel wall of the heat exchanger 100, such as the
inner wall of the inlet port 408 (FIG. 4). In the preferred
embodiment, the overhang dimension is within the range of and
including 0 to 5 millimeters for single phase and 0 to 15
millimeters for two phase fluid.
[0055] FIG. 10 illustrates a perspective view of one embodiment of
an interface layer 202' in accordance with the present invention.
As shown in FIG. 10, the interface layer 202' includes a series of
pillars 203 which extend upwards from a top surface of the
interface layer 202'. In addition, FIG. 10 illustrates a
microporous structure 213 disposed on the top surface of the
interface layer 202'. It is apparent that the interface layer 202'
can include only the microporous structure 213 as well as a
combination of the microporous structure with any other interface
layer feature (e.g. microchannels, pillars, etc.). In addition, the
interface layer 202' of the present invention preferably has a
thickness dimension within the range of and including 0.3 to 0.7
millimeters for single phase fluid and 0.3 to 1.0 millimeters for
two phase fluid.
[0056] In the embodiment of the heat exchanger which utilizes a
microporous structure 213 disposed upon the interface layer 202',
the microporous structure 213 has an average pore size within the
range of and including 10 to 200 microns for single phase as well
as two phase fluid. In addition, the microporous structure 213 has
a porosity within the range and including 50 to 80 percent for
single phase as well as two phase fluid. The height of the
microporous structure 213 is within the range of and including 0.25
to 2.00 millimeters for single phase as well as two phase
fluid.
[0057] In the embodiment which utilizes pillars and/or
microchannels along the interface layer 202', the interface layer
202' of the present invention has a thickness dimension in the
range of and including 0.3 to 0.7 millimeters for single phase
fluid and 0.3 to 1.0 millimeters for two phase fluid. In addition,
the area of at least one pillar, or microchannel, is in the range
of and including (10 micron).sup.2 and (100 micron).sup.2 for
single phase as well as two phase fluid. In addition, the area of
the separation distance between at least two of the pillars and/or
microchannels is in the range of and including 10 microns to 150
microns for single phase as well as two phase fluid. The width
dimension of the microchannels are in the range of and including 10
to 100 microns for single phase as well as two phase fluid. The
height dimension of the microchannels and/or pillars is within the
range of and including 50 to 800 microns for single phase fluid and
50 microns to 2 millimeters for two phase fluid. It is contemplated
by one skilled in the art that other dimension are alternatively
contemplated.
[0058] FIG. 3B illustrates a perspective view of the interface
layer 102 in accordance with the present invention. As shown in
FIG. 3B, the interface layer 102 includes a bottom surface 103 and
a plurality of microchannel walls 110, whereby the area in between
the microchannel walls 110 channels or directs fluid along a fluid
flow path. The bottom surface 103 is flat and has a high thermal
conductivity to allow sufficient heat transfer from the heat source
99. Alternatively, the bottom surface 103 includes troughs and/or
crests designed to collect or repel fluid from a particular
location. The microchannel walls 110 are configured in a parallel
configuration, as shown in FIG. 3B, whereby fluid preferably flows
between the microchannel walls 110 along a fluid path.
Alternatively, the microchannel walls 110 have non-parallel
configurations.
[0059] It is apparent to one skilled in the art that the
microchannel walls 110 are alternatively configured in any other
appropriate configuration depending on the factors discussed above.
For instance, the interface layer 102 alternatively has grooves in
between sections of microchannel walls 110, as shown in FIG. 8C. In
addition, the microchannel walls 110 have dimensions which minimize
the pressure drop or differential within the interface layer 102.
It is also apparent that any other features, besides microchannel
walls 110 are also contemplated, including, but not limited to,
pillars (FIG. 10), roughed surfaces, and a micro-porous structure,
such as sintered metal and silicon foam (FIG. 10). However, for
exemplary purposes, the parallel microchannel walls 110 shown in
FIG. 3B is used to describe the interface layer 102 in the present
invention.
[0060] The microchannel walls 110 allow the fluid to undergo
thermal exchange along the selected hot spot locations of the
interface hot spot region to cool the heat source 99 in that
location. The microchannel walls 110 have a width dimension within
the range of 10-100 microns and a height dimension within the range
of 50 microns to two millimeters, depending on the power of the
heat source 99. The microchannel walls 110 have a length dimension
which ranges between 100 microns and several centimeters, depending
on the dimensions of the heat source, as well as the size of the
hot spots and the heat flux density from the heat source.
Alternatively, any other microchannel wall dimensions are
contemplated. The microchannel walls 110 are spaced apart by a
separation dimension range of 50-500 microns, depending on the
power of the heat source 99, although any other separation
dimension range is contemplated.
[0061] Referring back to the assembly in FIG. 3B, the top surface
of the manifold layer 106 is cut away to illustrate the channels
116, 122 and fingers 118, 120 within the body of the manifold layer
106. The locations in the heat source 99 that produce more heat are
hereby designated as hot spots, whereby the locations in the heat
source 99 which produce less heat are hereby designated as warm
spots. As shown in FIG. 3B, the heat source 99 is shown to have a
hot spot region, namely at location A, and a warm spot region,
namely at location B. The areas of the interface layer 102 which
abut the hot and warm spots are accordingly designated interface
hot spot regions. As shown in FIG. 3B, the interface layer 102
includes interface hot spot region A, which is positioned above
location A and interface hot spot region B, which is positioned
above location B.
[0062] As shown in FIGS. 3A and 3B, fluid initially enters the heat
exchanger 100 through one inlet port 108. The fluid then preferably
flows to one inlet channel 116. Alternatively, the heat exchanger
100 includes more than one inlet channel 116. As shown in FIGS. 3A
and 3B, fluid flowing along the inlet channel 116 from the inlet
port 108 initially branches out to finger 118D. In addition, the
fluid which continues along the rest of the inlet channel 116 flows
to individual fingers 1181B and 118C and so on.
[0063] In FIG. 3B, fluid is supplied to interface hot spot region A
by flowing to the finger 118A, whereby fluid flows down through
finger 118A to the intermediate layer 104. The fluid then flows
through the inlet conduit 105A positioned below the finger 118A to
the interface layer 102, whereby the fluid undergoes thermal
exchange with the heat source 99. The fluid travels along the
microchannels 110 as shown in FIG. 3B, although the fluid may
travel in any other direction along the interface layer 102. The
heated liquid then travels upward through the conduit 105B to the
outlet finger 120A. Similarly, fluid flows down in the Z-direction
through fingers 118E and 118F to the intermediate layer 104. The
fluid then flows through the inlet conduit 105C down in the
Z-direction to the interface layer 102. The heated fluid then
travels upward in the Z-direction from the interface layer 102
through the outlet conduit 105D to the outlet fingers 120E and
120F. The heat exchanger 100 removes the heated fluid in the
manifold layer 106 via the outlet fingers 120, whereby the outlet
fingers 120 are in communication with the outlet channel 122. The
outlet channel 122 allows fluid to flow out of the heat exchanger
through one outlet port 109.
[0064] In one embodiment, the inflow and outflow conduits 105 are
positioned directly or nearly directly above the appropriate
interface hot spot regions to directly apply fluid to hot spots in
the heat source 99. In addition, each outlet finger 120 is
configured to be positioned closest to a respective inlet finger
119 for a particular interface hot spot region to minimize pressure
drop therebetween. Thus, fluid enters the interface layer 102 via
the inlet finger 118A and travels the least amount of distance
along the bottom surface 103 of the interface layer 102 before it
exits the interface layer 102 to the outlet finger 120A. It is
apparent that the amount of distance which the fluid travels along
the bottom surface 103 adequately removes heat generated from the
heat source 99 without generating an unnecessary amount of pressure
drop. In addition, as shown in FIGS. 3A and 3B, the corners in the
fingers 118, 120 are curved to reduce pressure drop of the fluid
flowing along the fingers 118.
[0065] It is apparent to one skilled in the art that the
configuration of the manifold layer 106 shown in FIGS. 3A and 3B is
only for exemplary purposes. The configuration of the channels 116
and fingers 118 in the manifold layer 106 depend on a number of
factors, including but not limited to, the locations of the
interface hot spot regions, amount of flow to and from the
interface hot spot regions as well as the amount of heat produced
by the heat source in the interface hot spot regions. For instance,
the preferred configuration of the manifold layer 106 includes an
interdigitated pattern of parallel inlet and outlet fingers that
are arranged along the width of the manifold layer, as shown in
FIGS. 4-7A and discussed below. Nonetheless, any other
configuration of channels 116 and fingers 118 is contemplated.
[0066] FIG. 4 illustrates a perspective view of the preferred
manifold layer 406 in accordance with the heat exchanger of the
present invention. The manifold layer 406 in FIG. 4 preferably
includes a plurality of interwoven or inter-digitated parallel
fluid fingers 411, 412 which allow one phase and/or two-phase fluid
to circulate to the interface layer 402 without allowing a
substantial pressure drop from occurring within the heat exchanger
400 and the system 30 (FIG. 2A). As shown in FIG. 8, the inlet
fingers 411 are arranged alternately with the outlet fingers 412.
However, it is contemplated by one skilled in the art that a
certain number of inlet or outlet fingers can be arranged adjacent
to one another and is thereby not limited to the alternating
configuration shown in FIG. 4. In addition, the fingers are
alternatively designed such that a parallel finger branches off
from or is linked to another parallel finger. Thus, it is possible
to have many more inlet fingers than outlet fingers and vice
versa.
[0067] The inlet fingers or passages 411 supply the fluid entering
the heat exchanger to the interface layer 402, and the outlet
fingers or passages 412 remove the fluid from the interface layer
402 which then exits the heat exchanger 400. The preferred
configuration of the manifold layer 406 allows the fluid to enter
the interface layer 402 and travel a very short distance in the
interface layer 402 before it enters the outlet passage 412. The
substantial decrease in the length that the fluid travels along the
interface layer 402 substantially decreases the pressure drop in
the heat exchanger 400 and the system 30 (FIG. 2A).
[0068] As shown in FIGS. 4-5, the preferred manifold layer 406
includes a passage 414 which is in communication with two inlet
passages 411 and provides fluid thereto. As shown in FIGS. 8-9 the
manifold layer 406 includes three outlet passages 412 which are in
communication with passage 418. Preferably the passages 414 in the
manifold layer 406 have a flat bottom surface which channels the
fluid to the fingers 411, 412. Alternatively, the passage 414 has a
slight slope which aids in channeling the fluid to selected fluid
passages 411. Alternatively, the inlet passage 414 includes one or
more apertures in its bottom surface which allows a portion of the
fluid to flow down to the interface layer 402. Similarly, the
passage 418 in the manifold layer has a flat bottom surface which
contains the fluid and channels the fluid to the port 408.
Alternatively, the passage 418 has a slight slope which aids in
channeling the fluid to selected outlet ports 408. In addition, the
passages 414, 418 have a dimension width of approximately 2
millimeters, although any other width dimensions are alternatively
contemplated.
[0069] The passages 414, 418 are in communication with ports 408,
409 whereby the ports are coupled to the fluid lines 38 in the
system 30 (FIG. 2A). The manifold layer 406 preferably includes
horizontally configured fluid ports 408, 409. Alternatively, the
manifold layer 406 includes vertically and/or diagonally configured
fluid ports 408, 409, as discussed below, although not shown in
FIG. 4-7. Alternatively, the manifold layer 406 does not include
passage 414. Thus, fluid is directly supplied to the fingers 411
from the ports 408. Again, the manifold layer 411 alternatively
does not include passage 418, whereby fluid in the fingers 412
directly flows out of the heat exchanger 400 through ports 408. It
is apparent that although two ports 408 are shown in communication
with the passages 414, 418, any other number of ports are
alternatively utilized.
[0070] The inlet passages 411 preferably have dimensions which
allow fluid to travel to the interface layer without generating a
large pressure drop along the passages 411 and the system 30 (FIG.
2A). The inlet passages 411 preferably have a width dimension in
the range of and including 0.25-5.00 millimeters, although any
other width dimensions are alternatively contemplated. In addition,
the inlet passages 411 preferably have a length dimension in the
range of and including 0.5 millimeters to three times the length of
the heat source. Alternatively, other length dimensions are
contemplated. In addition, as stated above, the inlet passages 411
extend down to or slightly above the height of the microchannels
410 such that the fluid is channeled directly to the microchannels
410. The inlet passages 411 preferably have a height dimension in
the range of and including 0.25-5.00 millimeters. It is apparent to
one skilled in the art that the passages 411 do not extend down to
the microchannels 410 and that any other height dimensions are
alternatively contemplated. It is apparent to one skilled in the
art that although the inlet passages 411 have the same dimensions,
it is contemplated that the inlet passages 411 alternatively have
different dimensions. In addition, the inlet passages 411
alternatively have varying widths, cross sectional dimensions
and/or distances between adjacent fingers. varying dimensions. In
particular, the passage 411 has areas with a larger width or depths
as well as areas with narrower widths and depths along its length.
The varied dimensions allow more fluid to be delivered to
predetermined interface hot spot regions in the interface layer 402
through wider portions while restricting flow to warm spot
interface hot spot regions through the narrow portions.
[0071] In addition, the outlet passages 412 preferably have
dimensions which allow fluid to travel to the interface layer
without generating a large pressure drop along the passages 412 as
well as the system 30 (FIG. 2A). The outlet passages 412 preferably
have a width dimension in the range of and including 0.25-5.00
millimeters, although any other width dimensions are alternatively
contemplated. In addition, the outlet passages 412 preferably have
a length dimension in the range of and including 0.5 millimeters to
three times the length of the heat source. In addition, the outlet
passages 412 extend down to the height of the microchannels 410
such that the fluid easily flows upward in the outlet passages 412
after horizontally flowing along the microchannels 410. The inlet
passages 411 preferably have a height dimension in the range of and
including 0.25-5.00 millimeters, although any other height
dimensions are alternatively contemplated. It is apparent to one
skilled in the art that although outlet passages 412 have the same
dimensions, it is contemplated that the outlet passages 412
alternatively have different dimensions. Again, the inlet passage
412 alternatively have varying widths, cross sectional dimensions
and/or distances between adjacent fingers.
[0072] The inlet and outlet passages 411, 412 are preferably
segmented and distinct from one another, as shown in FIGS. 4 and 5,
whereby fluid among the passages do not mix together. In
particular, as shown in FIG. 8, two outlet passages are located
along the outside edges of the manifold layer 406, and one outlet
passage 412 is located in the middle of the manifold layer 406. In
addition, two inlet passages 411 are configured on adjacent sides
of the middle outlet passage 412. This particular configuration
causes fluid entering the interface layer 402 to travel the a short
distance in the interface layer 402 before it flows out of the
interface layer 402 through the outlet passage 412. However, it is
apparent to one skilled in the art that the inlet passages and
outlet passages may be positioned in any other appropriate
configuration and is thereby not limited to the configuration shown
and described in the present disclosure. The number of inlet and
outlet fingers 411, 412 are more than three within the manifold
layer 406 but less than 10 per centimeter across the manifold layer
406. It is also apparent to one skilled in the art that any other
number of inlet passages and outlet passages may be used and
thereby is not limited to the number shown and described in the
present disclosure.
[0073] Preferably, the manifold layer 406 is coupled to the
intermediate layer (not shown), whereby the intermediate layer (not
shown) is coupled to the interface layer 402 to form a three-tier
heat exchanger 400. The intermediate layer discussed herein is
referred to above in the embodiment shown in FIG. 3B. The manifold
layer 406 is alternatively coupled to the interface layer 402 and
positioned above the interface layer 402 to form a two-tier heat
exchanger 400, as shown in FIG. 7A. FIGS. 6A-6C illustrate
cross-sectional schematics of the preferred manifold layer 406
coupled to the interface layer 402 in the two tier heat exchanger.
Specifically, FIG. 6A illustrates the cross section of the heat
exchanger 400 along line A-A in FIG. 5. In addition, FIG. 6B
illustrates the cross section of the heat exchanger 400 along line
B-B and FIG. 6C illustrates the cross section of the heat exchanger
400 along line C-C in FIG. 5. As stated above, the inlet and outlet
passages 411, 412 extend from the top surface to the bottom surface
of the manifold layer 406. When the manifold layer 406 and the
interface layer 402 are coupled to one another, the inlet and
outlet passages 411, 412 are at or slightly above the height of the
microchannels 410 in the interface layer 402. This configuration
causes the fluid from the inlet passages 411 to easily flow from
the passages 411 through the microchannels 410. In addition, this
configuration causes fluid flowing through the microchannels to
easily flow upward through the outlet passages 412 after flowing
through the microchannels 410.
[0074] In the preferred embodiment, the intermediate layer 104
(FIG. 3B) is positioned between the manifold layer 406 and the
interface layer 402, although not shown in the figures. The
intermediate layer 104 (FIG. 3B) channels fluid flow to designated
interface hot spot regions in the interface layer 402. In addition,
the intermediate layer 104 (FIG. 3B) is preferably utilized to
provide a uniform flow of fluid entering the interface layer 402.
Also, the intermediate layer 104 is preferably utilized to provide
fluid to interface hot spot regions in the interface layer 402 to
adequately cool hot spots and create temperature uniformity in the
heat source 99. Although, the inlet and outlet passages 411, 412
are preferably positioned near or above hot spots in the heat
source 99 to adequately cool the hot spots, although it is not
necessary.
[0075] FIG. 7A illustrates an exploded view of the alternate
manifold layer 406 with the an alternative interface layer 102 of
the present invention. Preferably, the interface layer 102 includes
continuous arrangements of microchannel walls 110, as shown in FIG.
3B. In general operation, similar to the preferred manifold layer
106 shown in FIG. 3B, fluid enters the manifold layer 406 at fluid
port 408 and travels through the passage 414 and towards the fluid
fingers or passages 411. The fluid enters the opening of the inlet
fingers 411 and preferably flows the length of the fingers 411 in
the X-direction, as shown by the arrows. In addition, the fluid
flows downward in the Z-direction to the interface layer 402 which
is positioned below to the manifold layer 406. As shown in FIG. 7A,
the fluid in the interface layer 402 traverses along the bottom
surface in the X and Y directions of the interface layer 402 and
performs thermal exchange with the heat source 99. The heated fluid
exits the interface layer 402 by preferably flowing upward in the
Z-direction via the outlet fingers 412, whereby the outlet fingers
412 channel the heated fluid to the passage 418 in the manifold
layer 406 in the X-direction. The fluid then flows along the
passage 418 and exits the heat exchanger by flowing out through the
port 409.
[0076] The interface layer, as shown in FIG. 7A, includes a series
of grooves 416 disposed in between sets of microchannels 410 which
aid in channeling fluid to and from the passages 411, 412. In
particular, the grooves 416A are located directly beneath the inlet
passages 411 of the alternate manifold layer 406, whereby fluid
entering the interface layer 402 via the inlet passages 411 is
directly channeled to the microchannels adjacent to the groove
416A. Thus, the grooves 416A allow fluid to be directly channeled
into specific designated flow paths from the inlet passages 411, as
shown in FIG. 5. Similarly, the interface layer 402 includes
grooves 416B which are located directly beneath the outlet passages
412 in the Z-direction. Thus, fluid flowing horizontally along the
microchannels 410 toward the outlet passages are channeled
horizontally to the grooves 416B and vertically to the outlet
passage 412 above the grooves 416B.
[0077] FIG. 6A illustrates the cross section of the heat exchanger
400 with manifold layer 406 and interface layer 402. In particular,
FIG. 6A shows the inlet passages 411 interwoven with the outlet
passages 412, whereby fluid flows down the inlet passages 411 and
up the outlet passages 412. In addition, as shown in FIG. 6A, the
fluid flows horizontally through the microchannel walls 410 which
are disposed between the inlet passages and outlet passages and
separated by the microchannels 410. Alternatively, the microchannel
walls are continuous (FIG. 3B) and are not separated by the
grooves. As shown in FIG. 6A, either or both of the inlet and
outlet passages 411, 412 preferably have a curved surface 420 at
their ends at the location near the grooves 416. The curved surface
420 directs fluid flowing down the passage 411 towards the
microchannels 410 which are located adjacent to the passage 411.
Thus, fluid entering the interface layer 102 is more easily
directed toward the microchannels 410 instead of flowing directly
to the groove 416A. Similarly, the curved surface 420 in the outlet
passages 412 assists in directing fluid from the microchannels 410
to the outer passage 412.
[0078] In an alternative embodiment, as shown in FIG. 7B, the
interface layer 402' includes the inlet passages 411' and outlet
passages 412' discussed above with respect to the manifold layer
406 (FIGS. 8-9). In the alternative embodiment, the fluid is
supplied directly to the interface layer 402' from the port 408'.
The fluid flows along the passage 414' towards the inlet passages
411'. The fluid then traverses laterally along the sets of
microchannels 410' and undergoes heat exchange with the heat source
(not shown) and flows to the outlet passages 412'. The fluid then
flows along the outlet passages 412' to passage 418', whereby the
fluid exits the interface layer 402' by via the port 409'. The
ports 408', 409' are configured in the interface layer 402' and are
alternatively configured in the manifold layer 406 (FIG. 7A).
[0079] It is apparent to one skilled in the art that although all
of the heat exchangers in the present application are shown to
operate horizontally, the heat exchanger alternatively operates in
a vertical position. While operating in the vertical position, the
heat exchangers are alternatively configured such that each inlet
passage is located above an adjacent outlet passage. Therefore,
fluid enters the interface layer through the inlet passages and is
naturally channeled to an outlet passage. It is also apparent that
any other configuration of the manifold layer and interface layer
is alternatively used to allow the heat exchanger to operate in a
vertical position.
[0080] FIGS. 8A-8C illustrate top view diagrams of another
alternate embodiment of the heat exchanger in accordance with the
present invention. In particular, FIG. 8A illustrates a top view
diagram of an alternate manifold layer 206 in accordance with the
present invention. FIGS. 8B and 8C illustrate a top view of an
intermediate layer 204 and interface layer 202. In addition, FIG.
9A illustrates a three tier heat exchanger utilizing the alternate
manifold layer 206, whereas FIG. 9B illustrates a two-tier heat
exchanger utilizing the alternate manifold layer 206.
[0081] As shown in FIGS. 8A and 9A, the manifold layer 206 includes
a plurality of fluid ports 208 configured horizontally and
vertically. Alternatively, the fluid ports 208 are positioned
diagonally or in any other direction with respect to the manifold
layer 206. The fluid ports 208 are placed in selected locations in
the manifold layer 206 to effectively deliver fluid to the
predetermined interface hot spot regions in the heat exchanger 200.
The multiple fluid ports 208 provide a significant advantage,
because fluid can be directly delivered from a fluid port to a
particular interface hot spot region without significantly adding
to the pressure drop to the heat exchanger 200. In addition, the
fluid ports 208 are also positioned in the manifold layer 206 to
allow fluid in the interface hot spot regions to travel the least
amount of distance to the exit port 208 such that the fluid
achieves temperature uniformity while maintaining a minimal
pressure drop between the inlet and outlet ports 208. Additionally,
the use of the manifold layer 206 aids in stabilizing two phase
flow within the heat exchanger 200 while evenly distributing
uniform flow across the interface layer 202. It should be noted
that more than one manifold layer 206 is alternatively included in
the heat exchanger 200, whereby one manifold layer 206 routes the
fluid into and out-of the heat exchanger 200 and another manifold
layer (not shown) controls the rate of fluid circulation to the
heat exchanger 200. Alternatively, all of the plurality of manifold
layers 206 circulate fluid to selected corresponding interface hot
spot regions in the interface layer 202.
[0082] The alternate manifold layer 206 has lateral dimensions
which closely match the dimensions of the interface layer 202. In
addition, the manifold layer 206 has the same dimensions of the
heat source 99. Alternatively, the manifold layer 206 is larger
than the heat source 99. The vertical dimensions of the manifold
layer 206 are within the range of 0.1 and 10 millimeters. In
addition, the apertures in the manifold layer 206 which receive the
fluid ports 208 are within the range between 1 millimeter and the
entire width or length of the heat source 99.
[0083] FIG. 11 illustrates a broken-perspective view of a three
tier heat exchanger 200 having the alternate manifold layer 200 in
accordance with the present invention. As shown in FIG. 11, the
heat exchanger 200 is divided into separate regions dependent on
the amount of heat produced along the body of the heat source 99.
The divided regions are separated by the vertical intermediate
layer 204 and/or microchannel wall features 210 in the interface
layer 202. However, it is apparent to one skilled in the art that
the assembly shown in FIG. 11 is not limited to the configuration
shown and is for exemplary purposes.
[0084] As shown in FIG. 3, the heat source 99 has a hot spot in
location A and a warm spot, location B, whereby the hot spot in
location A produces more heat than the warm spot in location B. It
is apparent that the heat source 99 may have more than one hot spot
and warm spot at any location at any given time. In the example,
since location A is a hot spot and more heat in location A
transfers to the interface layer 202 above location A (designated
in FIG. 11 as interface hot spot region A), more fluid and/or a
higher rate of liquid flow is provided to interface hot spot region
A in the heat exchanger 200 to adequately cool location A. It is
apparent that although interface hot spot region B is shown to be
larger than interface hot spot region A, interface hot spot regions
A and B, as well as any other interface hot spot regions in the
heat exchanger 200, can be any size and/or configuration with
respect to one another.
[0085] Alternatively, as shown in FIG. 11, the fluid enters the
heat exchanger via fluid ports 208A is directed to interface hot
spot region A by flowing along the intermediate layer 204 to the
inflow conduits 205A. The fluid then flows down the inflow conduits
205A in the Z-direction into interface hot spot region A of the
interface layer 202. The fluid flows in between the microchannels
210A whereby heat from location A transfers to the fluid by
conduction through the interface layer 202. The heated fluid flows
along the interface layer 202 in interface hot spot region A toward
exit port 209A where the fluid exits the heat exchanger 200. It is
apparent to one skilled in the art that any number of inlet ports
208 and exit ports 209 are utilized for a particular interface hot
spot region or a set of interface hot spot regions. In addition,
although the exit port 209A is shown near the interface layer 202A,
the exit port 209A is alternatively positioned in any other
location vertically, including but not limited to the manifold
layer 209B.
[0086] Similarly, in the example shown in FIG. 11, the heat source
99 has a warm spot in location B which produces less heat than
location A of the heat source 99. Fluid entering through the port
208B is directed to interface hot spot region B by flowing along
the intermediate layer 204B to the inflow conduits 205B. The fluid
then flows down the inflow conduits 205B in the Z-direction into
interface hot spot region B of the interface layer 202. The fluid
flows in between the microchannels 210 in the X and Y directions,
whereby heat generated by the heat source in location B is
transferred into the fluid. The heated fluid flows along the entire
interface layer 202B in interface hot spot region B upward to exit
ports 209B in the Z-direction via the outflow conduits 205B in the
intermediate layer 204 whereby the fluid exits the heat exchanger
200.
[0087] Alternatively, as shown in FIG. 9A, the heat exchanger 200
alternatively includes a vapor permeable membrane 214 positioned
above the interface layer 202. The vapor permeable membrane 214 is
in sealable contact with the inner side walls of the heat exchanger
200. The membrane is configured to have several small apertures
which allow vapor produced along the interface layer 202 to pass
therethrough to the outlet port 209. The membrane 214 is also
configured to be hydrophobic to prevent liquid fluid flowing along
the interface layer 202 from passing through the apertures of the
membrane 214. More details of the vapor permeable membrane 114 is
discussed in co-pending U.S. application Ser. No. 10/366,128, filed
Feb. 12, 2003 and entitled, "VAPOR ESCAPE MICROCHANNEL HEAT
EXCHANGER" which is hereby incorporated by reference.
[0088] The microchannel heat exchanger of the present invention
alternatively has other configurations not described above. For
instance, the heat exchanger alternatively includes a manifold
layer which minimizes the pressure drop within the heat exchanger
in having separately sealed inlet and outlet apertures which lead
to the interface layer. Thus, fluid flows directly to the interface
layer through inlet apertures and undergoes thermal exchange in the
interface layer. The fluid then exits the interface layer by
flowing directly through outlet apertures arranged adjacent to the
inlet apertures. This porous configuration of the manifold layer
minimizes the amount of distance that the fluid must flow between
the inlet and outlet ports as well as maximizes the division of
fluid flow among the several apertures leading to the interface
layer.
[0089] The details of how the heat exchanger 100 as well as the
individual layers in the heat exchanger 100 are fabricated and
manufactured are discussed below. The following discussion applies
to the preferred and alternative heat exchangers of the present
invention, although the heat exchanger 100 in FIG. 3B and
individual layers therein are expressly referred to for simplicity.
It is also apparent to one skilled in the art that although the
fabrication/manufacturing details are described in relation to the
present invention, the fabrication and manufacturing details also
alternatively apply to conventional heat exchangers as well as two
and three-tier heat exchangers utilizing one fluid inlet port and
one fluid outlet port as shown in FIGS. 1A-1C.
[0090] Preferably, the interface layer 102 has a coefficient of
thermal expansion (CTE) which is approximate or equal to that of
the heat source 99. Thus, the interface layer 102 preferably
expands and contracts accordingly with the heat source 99.
Alternatively, the material of the interface layer 102 has a CTE
which is different than the CTE of the heat source material. An
interface layer 102 made from a material such as Silicon has a CTE
that matches that of the heat source 99 and has sufficient thermal
conductivity to adequately transfer heat from the heat source 99 to
the fluid. However, other materials are alternatively used in the
interface layer 102 which have CTEs that match the heat source
99.
[0091] The interface layer 102 in the heat exchanger 100 preferably
has a high thermal conductivity for allowing sufficient conduction
to pass between the heat source 99 and fluid flowing along the
interface layer 102 such that the heat source 99 does not overheat.
The interface layer 102 is preferably made from a material having a
high thermal conductivity of 100 W/m-K. However, it is apparent to
one skilled in the art that the interface layer 102 has a thermal
conductivity of more or less than 100 W/m-K and is not limited
thereto.
[0092] To achieve the preferred high thermal conductivity, the
interface layer is preferably made from a semiconductor substrate,
such as Silicon. Alternatively, the interface layer is made from
any other material including, but not limited to single-crystalline
dielectric materials, metals, aluminum, nickel and copper, Kovar,
graphite, diamond, composites and any appropriate alloys. An
alternative material of the interface layer 102 is a patterned or
molded organic mesh.
[0093] As shown in FIG. 12, it is preferred that the interface
layer 102 is coated with a coating layer 112 to protect the
material of the interface layer 102 as well as enhance the thermal
exchange properties of the interface layer 102. In particular, the
coating 112 provides chemical protection that eliminates certain
chemical interactions between the fluid and the interface layer
102. For example, an interface layer 102 made from aluminum may be
etched by the fluid coming into contact with it, whereby the
interface layer 102 would deteriorate over time. The coating 112 of
a thin layer of Nickel, approximately 25 microns, is thus
preferably electroplated over the surface of the interface layer
102 to chemically pacify any potential reactions without
significantly altering the thermal properties of the interface
layer 102. It is apparent that any other coating material with
appropriate layer thickness is contemplated depending on the
material(s) in the interface layer 102.
[0094] In addition, the coating material 112 is applied to the
interface layer 102 to enhance the thermal conductivity of the
interface layer 102 to perform sufficient heat exchange with the
heat source 99, as shown in FIG. 12. For example, an interface
layer 102 having a metallic base covered with plastic can be
thermally enhanced with a layer of Nickel coating material 112 on
top of the plastic. The layer of Nickel has a thickness of at least
25 microns, depending on the dimensions of the interface layer 102
and the heat source 99. It is apparent that any other coating
material with appropriate layer thickness is contemplated depending
on the material(s) in the interface layer 102. The coating material
112 is alternatively used on material already having high thermal
conductivity characteristics, such that the coating material
enhances the thermal conductivity of the material. The coating
material 112 is preferably applied to the bottom surface 103 as
well as the microchannel walls 110 of the interface layer 102, as
shown in FIG. 12. Alternatively, the coating material 112 is
applied to either of the bottom surface 103 or microchannel walls
110. The coating material 112 is preferably made from a metal
including, but not limited to, Nickel and Aluminum. However, the
coating material 112 is alternatively made of any other thermally
conductive material.
[0095] The interface layer 102 is preferably formed by an etching
process using a Copper material coated with a thin layer of Nickel
to protect the interface layer 102. Alternatively, the interface
layer 102 is made from Aluminum, Silicon substrate, plastic or any
other appropriate material. The interface layer 102 being made of
materials having poor thermal conductivity are also coated with the
appropriate coating material to enhance the thermal conductivity of
the interface layer 102. One method of electroforming the interface
layer is by applying a seed layer of chromium or other appropriate
material along the bottom surface 103 of the interface layer 102
and applying electrical connection of appropriate voltage to the
seed layer. The electrical connection thereby forms a layer of the
thermally conductive coating material 112 on top of the interface
layer 102. The electroforming process also forms feature dimensions
in a range of 10-100 microns. The interface layer 102 is formed by
an electroforming process, such as patterned electroplating. In
addition, the interface layer is alternatively processed by
photochemical etching or chemical milling, alone or in combination,
with the electroforming process. Standard lithography sets for
chemical milling are used to process features in the interface
layer 102. Additionally, the aspect ratios and tolerances are
enhanceable using laser assisted chemical milling processes.
[0096] The microchannel walls 110 are preferably made of Silicon.
The microchannel walls 110 are alternatively made of any other
materials including, but not limited to, patterned glass, polymer,
and a molded polymer mesh. Although it is preferred that the
microchannel walls 110 are made from the same material as that of
the bottom surface 103 of the interface layer 102, the microchannel
walls 110 are alternatively made from a different material than
that of the rest of the interface layer 102.
[0097] It is preferred that the microchannel walls 110 have thermal
conductivity characteristics of at least 10 W/m-K. Alternatively,
the microchannel walls 110 have thermal conductivity
characteristics of more than 10 W/m-K. It is apparent to one
skilled in the art that the microchannel walls 110 alternatively
have thermal conductivity characteristics of less than 10 W/m-K,
whereby coating material 112 is applied to the microchannel walls
110, as shown in FIG. 12, to increase the thermal conductivity of
the wall features 110. For microchannel walls 110 made from
materials already having a good thermal conductivity, the coating
112 applied has a thickness of at least 25 microns which also
protects the surface of the microchannel walls 110. For
microchannel walls 110 made from material having poor thermal
conductivity characteristics, the coating 112 has a thermal
conductivity of at least 50 W/m-K and is more than 25 microns
thick. It is apparent to one skilled in the art that other types of
coating materials as well as thickness dimensions are
contemplated.
[0098] To configure the microchannel walls 110 to have an adequate
thermal-conductivity of at least 10 W/m-K, the walls 110 are
electroformed with the coating material 112 (FIG. 12), such as
Nickel or other metal, as discussed above. To configure the
microchannel walls 110 to have an adequate thermal conductivity of
at least 50 W/m-K, the walls 110 are electroplated with Copper on a
thin metal film seed layer. Alternatively, the microchannel walls
110 are not coated with the coating material. It is understood that
the thermal conductivity characteristics of the microchannel walls
110 and the coating 112, when appropriate, also apply to the
pillars 203 (FIG. 10) and any appropriate coating applied
thereon.
[0099] The microchannel walls 110 are preferably formed by a hot
embossing technique to achieve a high aspect ratio of channel walls
110 along the bottom surface 103 of the interface layer 102. The
microchannel wall features 110 are alternatively fabricated as
Silicon structures deposited on a glass surface, whereby the
features are etched on the glass in the desired configuration. The
microchannel walls 110 are alternatively formed by a standard
lithography techniques, stamping or forging processes, or any other
appropriate method. The microchannel walls 110 are alternatively
made separately from the interface layer 102 and coupled to the
interface layer 102 by anodic or epoxy bonding. Alternatively, the
microchannel features 110 are coupled to the interface layer 102 by
conventional electroforming techniques, such as electroplating.
[0100] There are a variety of methods that can be used to fabricate
the intermediate layer 104. The intermediate layer is preferably
made from Silicon. It is apparent to one skilled in the art that
any other appropriate material is contemplated including, but not
limited to glass, laser-patterned glass, polymers, metals, glass,
plastic, molded organic material or any composites thereof.
Preferably, the intermediate layer 104 is formed using plasma
etching techniques. Alternatively, the intermediate layer 104 is
formed using a chemical etching technique. Other alternative
methods include machining, etching, extruding and/or forging a
metal into the desired configuration. The intermediate layer 104 is
alternatively formed by injection molding of a plastic mesh into
the desired configuration. Alternatively, the intermediate layer
104 is formed by laser-drilling a glass plate into the desired
configuration.
[0101] The manifold layer 106 is manufactured by a variety of
methods. It is preferred that the manifold layer 106 is fabricated
by an injection molding process utilizing plastic, metal, polymer
composite or any other appropriate material, whereby each layer is
made from the same material. Alternatively, as discussed above,
each layer is made from a different material. The manifold layer
106 is alternatively generated using a machined or etched metal
technique. It is apparent to one skilled in the art that the
manifold layer 106 is manufactured utilizing any other appropriate
method.
[0102] The intermediate layer 104 is coupled to the interface layer
102 and manifold layer 106 to form the heat exchanger 100 using a
variety of methods. The interface layer 102, intermediate layer 104
and manifold layer 106 are preferably coupled to one another by an
anodic, adhesive or eutectic bonding process. The intermediate
layer 104 is alternatively integrated within features of the
manifold layer 106 and interface layer 102. The intermediate layer
104 is coupled to the interface layer 102 by a chemical bonding
process. The intermediate layer 104 is alternatively manufactured
by a hot embossing or soft lithography technique, whereby a wire
EDM or Silicon master is utilized to stamp the intermediate layer
104. The intermediate layer 104 is then alternatively electroplated
with metal or another appropriate material to enhance the thermal
conductivity of the intermediate layer 104, if needed.
[0103] Alternatively, the intermediate layer 104 is formed along
with the fabrication of the microchannel walls 110 in the interface
layer 102 by an injection molding process. Alternatively, the
intermediate layer 104 is formed with the fabrication of the
microchannel walls 110 by any other appropriate method. Other
methods of forming the heat exchanger include, but are not limited
to soldering, fusion bonding, eutectic Bonding, intermetallic
bonding, and any other appropriate technique, depending on the
types of materials used in each layer.
[0104] Another alternative method of manufacturing the heat
exchanger of the present invention is described in FIG. 13. As
discussed in relation to FIG. 13, an alternative method of
manufacturing the heat exchanger includes building a hard mask
formed from a silicon substrate as the interface layer (step 500).
The hard mask is made from silicon dioxide or alternatively
spin-on-glass. Once the hard mask is formed, a plurality of
under-channels are formed in the hard mask, wherein the
under-channels form the fluid paths between the microchannel walls
110 (step 502). The under-channels are formed by any appropriate
method, including but not limited to HF etching techniques,
chemical milling, soft lithography and xenon difluoride etch. In
addition, enough space between each under-channel must be ensured
such that under-channels next to one another do not bridge
together. Thereafter, spin-on-glass is then applied by any
conventional method over the top surface of the hard mask to form
the intermediate and manifold layers (step 504). Following, the
intermediate and manifold layers are hardened by a curing method
(step 506). Once the intermediate and manifold layers are fully
formed and hardened, one or more fluid ports are formed into the
hardened layer (step 508). The fluid ports are etched or
alternatively drilled into the manifold layer. Although specific
methods of fabricating the interface layer 102, the intermediate
layer 104 and manifold layer 106 are discussed herein, other known
methods known in art to manufacture the heat exchanger 100 are
alternatively contemplated.
[0105] FIG. 14 illustrates an alternative embodiment of the heat
exchanger of the present invention. As shown in FIG. 6, two heat
exchangers 200, 200' are coupled to one heat source 99. In
particular, the heat source 99, such as an electronic device, is
coupled to a circuit board 96 and is positioned upright, whereby
each side of the heat source 99 is potentially exposed. A heat
exchanger of the present invention is coupled to one exposed side
of the heat source 99, whereby both heat exchangers 200, 200'
provide maximum cooling of the heat source 99. Alternatively, the
heat source is coupled to the circuit board horizontally, whereby
more than one heat exchanger is stacked on top of the heat source
99 (not shown), whereby each heat exchanger is electrically coupled
to the heat source 99; More details regarding this embodiment are
shown and described in co-pending U.S. patent application Ser. No.
10/072,137, filed Feb. 7, 2002, entitled "POWER CONDITIONING
MODULE" which is hereby incorporated by reference.
[0106] As shown in FIG. 14, the heat exchanger 200 having two
layers is coupled to the left side of the heat source 99 and the
heat exchanger 200' having three layers is coupled to the right
side of the heat source 99. It is apparent to one skilled in the
art that the preferred or alternative heat exchangers are coupled
to the sides of the heat source 99. It is also apparent to one
skilled in the art that the alternative embodiments of the heat
exchanger 200' are alternatively coupled to the sides of the heat
source 99. The alternative embodiment shown in FIG. 14 allows more
precise hot spot cooling of the heat source 99 by applying fluid to
cool hot spots which exist along the thickness of the heat source
99. Thus, the embodiment in FIG. 14 applies adequate cooling to hot
spots in the center of the heat source 99 by exchanging heat from
both sides of the heat source 99. It is apparent to one skilled in
the art that the embodiment shown in FIG. 14 is used with the
cooling system 30 in FIGS. 2A-2B, although other closed loop
systems are contemplated.
[0107] As stated above, the heat source 99 may have characteristics
in which the locations of one or more of the hot spots change due
to different tasks required to be performed by the heat source 99.
To adequately cool the heat source 99, the system 30 alternatively
includes a sensing and control module 34 (FIGS. 2A-2B) which
dynamically changes the amount of flow and/or flow rate of fluid
entering the heat exchanger 100 in response to a change in location
of the hot spots.
[0108] In particular, as shown in FIG. 14, one or more sensors 124
are placed in each interface hot spot region in the heat exchanger
200 and/or alternatively the heat source 99 at each potential hot
spot location. Alternatively, a plurality of heat sources are
uniformly placed in between the heat source and heat exchanger
and/or in the heat exchanger itself. The control module 38 (FIG.
2A-2B) is also coupled to one or more valves in the loop 30 which
control the flow of fluid to the heat exchanger 100. The one or
more valves are positioned within the fluid lines, but are
alternatively positioned elsewhere. The plurality of sensors 124
are coupled to the control module 34, whereby the control module 34
is preferably placed upstream from heat exchanger 100, as shown in
FIG. 2. Alternatively, the control module 34 is placed at any other
location in the closed loop system 30.
[0109] The sensors 124 provide information to the control module 34
including, but not limited to, the flow rate of fluid flowing in
the interface hot spot region, temperature of the interface layer
102 in the interface hot spot region and/or heat source 99 and
temperature of the fluid. For example, referring to the schematic
in FIG. 14, sensors positioned on the interface 124 provide
information to the control module 34 that the temperature in a
particular interface hot spot region in heat exchanger 200 is
increasing whereas the temperature in a particular interface hot
spot region in heat exchanger 200' is decreasing. In response, the
control module 34 increases the amount of flow to heat exchanger
200 and decreases the amount of flow provided to heat exchanger
200'. Alternatively, the control module 34 alternatively changes
the amount of flow to one or more interface hot spot regions in one
or more heat exchangers in response to the information received
from the sensors 118. Although the sensors 118 are shown with the
two heat exchangers 200, 200' in FIG. 14, it is apparent that the
sensors 118 are alternatively coupled with only one heat
exchanger.
[0110] The present invention has been described in terms of
specific embodiments incorporating details to facilitate the
understanding of the principles of construction and operation of
the invention. Such reference herein to specific embodiments and
details thereof is not intended to limit the scope of the claims
appended hereto. It will be apparent to those skilled in the art
that modification s may be made in the embodiment chosen for
illustration without departing from the spirit and scope of the
invention.
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