U.S. patent application number 12/151243 was filed with the patent office on 2009-01-01 for micro-tube/multi-port counter flow radiator design for electronic cooling applications.
Invention is credited to James Horn, Frederic Landry, Paul Tsao, Girish Upadhya, Peng Zhou.
Application Number | 20090000771 12/151243 |
Document ID | / |
Family ID | 39943855 |
Filed Date | 2009-01-01 |
United States Patent
Application |
20090000771 |
Kind Code |
A1 |
Horn; James ; et
al. |
January 1, 2009 |
Micro-tube/multi-port counter flow radiator design for electronic
cooling applications
Abstract
A counter flow radiator includes multiple layered cooling cores
configured in series along a first direction that is the same as
the direction of airflow used to cool fluid flowing through the
counter flow radiator. Heated fluid inputs the counter flow
radiator at a first end and flows through each cooling core in a
serpentine-like path to the second end of the counter flow
radiator, effectively progressing in a direction opposite that of
the airflow.
Inventors: |
Horn; James; (Redwood City,
CA) ; Upadhya; Girish; (Austin, TX) ; Zhou;
Peng; (El Cerrito, CA) ; Tsao; Paul; (Los
Altos, CA) ; Landry; Frederic; (Montreal,
CA) |
Correspondence
Address: |
HAVERSTOCK & OWENS LLP
162 N WOLFE ROAD
SUNNYVALE
CA
94086
US
|
Family ID: |
39943855 |
Appl. No.: |
12/151243 |
Filed: |
May 2, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60927424 |
May 2, 2007 |
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Current U.S.
Class: |
165/104.19 |
Current CPC
Class: |
F28D 1/05391 20130101;
F28D 1/0435 20130101 |
Class at
Publication: |
165/104.19 |
International
Class: |
F28D 15/00 20060101
F28D015/00 |
Claims
1. A fluid-air heat exchanger comprising: a. a plurality of
fluid-air cooling cores, each cooling core includes at least one
layer of one or more thermally conductive fluid conduits and at
least one layer of thermally conductive cooling fins coupled to at
least one fluid conduit layer, wherein each fluid conduit is
configured along a first direction from a first end of the cooling
core to a second end of the cooling core, further wherein the
plurality of cooling cores are stacked side by side along a second
direction perpendicular to the first direction such that the fluid
conduits of the plurality of cooling cores are configured in
parallel; b. a first fluid header coupled to the first end of each
cooling core, wherein the first header includes an inlet port
configured to receive an input fluid; and c. a second header
coupled to the second end of each cooling core, wherein the first
header and the second header are configured to direct fluid flow in
series from a first cooling core closest to the inlet port of the
first header to each successively stacked cooling core along the
second direction, wherein a second cooling core positioned furthest
from the first cooling core within the plurality of stacked cooling
cores is configured to receive an intake airflow into the fluid-air
heat exchanger along the second direction and the first cooling
core is configured to exhaust the airflow from the fluid-air heat
exchanger.
2. The fluid-air heat exchanger of claim 1 wherein if a number of
cooling cores is even, then the first fluid header includes an
outlet port configured to output fluid received from the second
cooling core.
3. The fluid-air heat exchanger of claim 2 wherein the first header
includes at least one divider to separate the inlet port from the
outlet port.
4. The fluid-air heat exchanger of claim 1 wherein if a number of
cooling cores is odd, then the second fluid header includes an
outlet port configured to output fluid received from the second
cooling core.
5. The fluid-air heat exchanger of claim 1 wherein the first header
and the second header cumulatively include at least one fluid
divider configured to direct fluid flow from the inlet port to the
outlet port via the plurality of cooling cores.
6. The fluid-air heat exchanger of claim 5 wherein the fluid flows
between the first header, the second header, and from cooling core
to cooling core in a serpentine-like manner.
7. The fluid-air heat exchanger of claim 1 wherein a temperature of
the input fluid is greater than a temperature of the fluid output
from the outlet port.
8. The fluid-air heat exchanger of claim 7 wherein a hot-to-cold
fluid temperature gradient is formed along the second direction
from the first cooling core to the second cooling core.
9. The fluid-air heat exchanger of claim 7 wherein a temperature of
the intake airflow is colder than a temperature of the exhaust
airflow.
10. The fluid-air heat exchanger of claim 7 wherein a hot-to-cold
air temperature gradient is formed along the second direction from
the first cooling core to the second cooling core.
11. The fluid-air heat exchanger of claim 1 wherein a temperature
of the input fluid is less than a temperature of the fluid output
from the outlet port.
12. The fluid-air heat exchanger of claim 11 wherein a cold-to-hot
fluid temperature gradient is formed along the second direction
from the first cooling core to the second cooling core.
13. The fluid-air heat exchanger of claim 11 wherein a temperature
of the intake airflow is greater than a temperature of the exhaust
airflow.
14. The fluid-air heat exchanger of claim 11 wherein a cold-to-hot
air temperature gradient is formed along the second direction from
the first cooling core to the second cooling core.
15. The fluid-air heat exchanger of claim 1 wherein each cooling
core is exposed to a different temperature airflow.
16. The fluid-air heat exchanger of claim 1 wherein the inlet port
is positioned proximate a first end of the first fluid header, and
the first cooling core is positioned proximate the first end of the
first fluid header and a first end of the second fluid header.
17. The fluid-air heat exchanger of claim 16 wherein the second
cooling core is positioned proximate a second end of the first
fluid header and a second end of the second fluid header.
18. The fluid-air heat exchanger of claim 1 wherein each layer of
fluid conduits comprises a plurality of individual thermally
conductive micro-tubes, wherein each micro-tube is configured such
that fluid flow therethrough is isolated from each other
micro-tube.
19. The fluid-air heat exchanger of claim 1 wherein each layer of
fluid conduits comprises a plurality of individual thermally
conductive micro-tubes, wherein each micro-tube includes one or
more common openings with an adjacent micro-tube such that fluid
flow therethrough is intermixed between adjacent micro-tubes.
20. The fluid-air heat exchanger of claim 1 wherein each cooling
fin is configured along the second direction.
21. The fluid-air heat exchanger of claim 1 wherein each cooling
core includes a plurality of core layers, each layer including at
least one layer of cooling fins and a layer of at least one fluid
conduit, further wherein each core layer within a given cooling
core is stacked along a third direction that is perpendicular to
the first direction and perpendicular to the second direction.
22. A fluid-air heat exchanger comprising: a. a plurality of
fluid-air cooling cores, each cooling core includes at least one
layer of one or more thermally conductive fluid conduits and at
least one layer of thermally conductive cooling fins coupled to at
least one fluid conduit layer, wherein each fluid conduit is
configured along a first direction from a first end of the cooling
core to a second end of the cooling core, further wherein the
plurality of cooling cores are stacked side by side along a second
direction perpendicular to the first direction such that the fluid
conduits of the plurality of cooling cores are configured in
parallel; b. a first fluid header coupled to the first end of each
cooling core, wherein the first header includes an inlet port
configured to receive an input fluid; and c. a second header
coupled to the second end of each cooling core, wherein the first
header and the second header are configured to direct fluid flow in
series from a first cooling core closest to the inlet port of the
first header to each successively stacked cooling core along the
second direction, wherein the first cooling core is configured to
receive an intake airflow into the fluid-air heat exchanger along
the second direction, and a second cooling core positioned furthest
from the first cooling core within the plurality of stacked cooling
cores is configured to exhaust the airflow from the fluid-air heat
exchanger.
23. The fluid-air heat exchanger of claim 22 wherein if a number of
cooling cores is even, then the first fluid header includes an
outlet port configured to output fluid received from the second
cooling core.
24. The fluid-air heat exchanger of claim 23 wherein the first
header includes at least one divider to separate the inlet port
from the outlet port.
25. The fluid-air heat exchanger of claim 22 wherein if a number of
cooling cores is odd, then the second fluid header includes an
outlet port configured to output fluid received from the second
cooling core.
26. The fluid-air heat exchanger of claim 22 wherein the first
header and the second header cumulatively include at least one
fluid divider configured to direct fluid flow from the inlet port
to the outlet port via the plurality of cooling cores.
27. The fluid-air heat exchanger of claim 26 wherein the fluid
flows between the first header, the second header, and from cooling
core to cooling core in a serpentine-like manner.
28. The fluid-air heat exchanger of claim 22 wherein a temperature
of the input fluid is greater than a temperature of the fluid
output from the outlet port.
29. The fluid-air heat exchanger of claim 28 wherein a hot-to-cold
fluid temperature gradient is formed along the second direction
from the first cooling core to the second cooling core.
30. The fluid-air heat exchanger of claim 28 wherein a temperature
of the intake airflow is colder than a temperature of the exhaust
airflow.
31. The fluid-air heat exchanger of claim 28 wherein a cold-to-hot
air temperature gradient is formed along the second direction from
the first cooling core to the second cooling core.
32. The fluid-air heat exchanger of claim 22 wherein a temperature
of the input fluid is less than a temperature of the fluid output
from the outlet port.
33. The fluid-air heat exchanger of claim 32 wherein a cold-to-hot
fluid temperature gradient is formed along the second direction
from the first cooling core to the second cooling core.
34. The fluid-air beat exchanger of claim 32 wherein a temperature
of the intake airflow is greater than a temperature of the exhaust
airflow.
35. The fluid-air heat exchanger of claim 32 wherein a hot-to-cold
air temperature gradient is formed along the second direction from
the first cooling core to the second cooling core.
36. The fluid-air heat exchanger of claim 22 wherein each cooling
core is exposed to a different temperature airflow.
37. The fluid-air heat exchanger of claim 22 wherein the inlet port
is positioned proximate a first end of the first fluid header, and
the first cooling core is positioned proximate the first end of the
first fluid header and a first end of the second fluid header.
38. The fluid-air heat exchanger of claim 37 wherein the second
cooling core is positioned proximate a second end of the first
fluid header and a second end of the second fluid header.
39. The fluid-air heat exchanger of claim 22 wherein each layer of
fluid conduits comprises a plurality of individual thermally
conductive micro-tubes, wherein each micro-tube is configured such
that fluid flow therethrough is isolated from each other
micro-tube.
40. The fluid-air heat exchanger of claim 22 wherein each layer of
fluid conduits comprises a plurality of individual thermally
conductive micro-tubes, wherein each micro-tube includes one or
more common openings with an adjacent micro-tube such that fluid
flow therethrough is intermixed between adjacent micro-tubes.
41. The fluid-air heat exchanger of claim 22 wherein each cooling
fin is configured along the second direction.
42. The fluid-air heat exchanger of claim 22 wherein each cooling
core includes a plurality of core layers, each layer including at
least one layer of cooling fins and a layer of at least one fluid
conduit, further wherein each core layer within a given cooling
core is stacked along a third direction that is perpendicular to
the first direction and perpendicular to the second direction.
43. A fluid-air heat exchanger comprising: a. a plurality of
fluid-air cooling cores, each cooling core includes at least one
layer of one or more thermally conductive fluid conduits and at
least one layer of thermally conductive cooling fins coupled to the
at least one fluid conduit layer and mounted to pass air through
the fluid-air cooling core, wherein each fluid conduit is
configured along a first direction from a first end of the cooling
core to a second end of the cooling core, further wherein the
plurality of cooling cores are stacked side by side in series along
a second direction perpendicular to the first direction such that
the fluid conduits of the plurality of cooling cores are configured
in parallel; b. a first fluid header coupled to the first end of
each cooling core, wherein the first header includes an inlet port
configured to receive an input fluid; and c. a second header
coupled to the second end of each cooling core, wherein the first
header and the second header are configured to direct fluid flow in
series from a first cooling core to each successively stacked
cooling core along the second direction.
44. The fluid-air heat exchanger of claim 43 wherein if a number of
cooling cores is even, then the first fluid header includes an
outlet port configured to output fluid received from a last cooling
core in the series.
45. The fluid-air heat exchanger of claim 44 wherein the first
header includes at least one divider to separate the inlet port
from the outlet port.
46. The fluid-air heat exchanger of claim 43 wherein if a number of
cooling cores is odd, then the second fluid header includes an
outlet port configured to output fluid received from a last cooling
core in the series.
47. The fluid-air heat exchanger of claim 43 wherein the first
header and the second header cumulatively include at least one
fluid divider configured to direct fluid flow from the inlet port
to the outlet port via the plurality of cooling cores.
48. The fluid-air heat exchanger of claim 47 wherein the fluid
flows between the first header, the second header, and from cooling
core to cooling core in a serpentine-like manner.
49. The fluid-air heat exchanger of claim 43 wherein each layer of
fluid conduits comprises a plurality of individual thermally
conductive micro-tubes, wherein each micro-tube is configured such
that fluid flow therethrough is isolated from each other
micro-tube.
50. The fluid-air heat exchanger of claim 43 wherein each layer of
fluid conduits comprises a plurality of individual thermally
conductive micro-tubes, wherein each micro-tube includes one or
more common openings with an adjacent micro-tube such that fluid
flow therethrough is intermixed between adjacent micro-tubes.
51. The fluid-air heat exchanger of claim 43 wherein each cooling
fin is configured along the second direction.
52. The fluid-air heat exchanger of claim 43 wherein each cooling
core includes a plurality of core layers, each layer including at
least one layer of cooling fins and a layer of at least one fluid
conduit, further wherein each core layer within a given cooling
core is stacked along a third direction that is perpendicular to
the first direction and perpendicular to the second direction.
Description
RELATED APPLICATIONS
[0001] This Patent Application claims priority under 35 U.S.C. 119
(e) of the co-pending U.S. Provisional Patent Application Ser. No.
60/927,424, filed May 2, 2007, and entitled "MICRO-TUBE/MULTI-PORT
COUNTER FLOW RADIATOR DESIGN FOR ELECTRONIC COOLING APPLICATIONS".
The Provisional Patent Application Ser. No. 60/927,424, filed May
2, 2007, and entitled "MICRO-TUBE/MULTI-PORT COUNTER FLOW RADIATOR
DESIGN FOR ELECTRONIC COOLING APPLICATIONS" is also hereby
incorporated by reference.
FIELD OF THE INVENTION
[0002] The invention relates to an apparatus for cooling a heat
producing device in general, and specifically, to a fluid-air heat
exchanger used in fluid cooling applications.
BACKGROUND OF THE INVENTION
[0003] Cooling of high performance integrated circuits with high
heat dissipation is presenting significant challenge in the
electronics cooling arena. Conventional cooling with heat pipes and
fan mounted heat sinks are not adequate for cooling chips with ever
increasing wattage requirements.
[0004] A particular problem with cooling integrated circuits within
electronic devices is that more numerous and powerful integrated
circuits are configured within the same size or smaller chassis. As
more powerful integrated circuits are developed, each with an
increasing density of heat generating transistors, the heat
generated by each individual integrated circuit continues to
increase. Further, more and more integrated circuits, such as
graphics processing units, microprocessors, and multiple-chip sets,
are being added to electronic devices, such as electronics servers
and personal computers. Still further, the more powerful and more
plentiful integrated circuits are being added to the same, or
smaller size chassis, thereby increasing the per unit heat
generated for these devices. In such configurations, conventional
chassis' provide limited dimensions within which to provide an
adequate cooling solution. Conventionally, the integrated circuits
are cooled using a heat sink and a large fan that blows air over
the heat sink, or simply by blowing air directly over the circuit
boards containing the integrated circuits. However, considering the
limited free space within the device chassis, the amount of air
available for cooling the integrated circuits and the space
available for conventional cooling equipment, such as heat sinks
and fans, is limited.
[0005] Closed loop liquid cooling presents alternative
methodologies for conventional cooling solutions. Closed loop
liquid cooling solutions more efficiently reject heat to the
ambient than air cooling solutions. A closed loop cooling system
includes a cold plate to receive heat from a heat source, a
radiator with fan cooling for heat rejection, and a pump to drive
liquid through the closed loop. The design of each component is
often complex and requires detailed analysis and optimization for
specific applications.
[0006] FIG. 1 illustrates a first conventional radiator 2
configured with one-direction fluid flow. The radiator 2 is
configured with a fluid input header 10, a fluid output header 12,
a set of parallel fluid channels 14 through which heated fluid
flows, and a set of cooling fins 16 thermally coupled to the set of
fluid channels 14. Heated fluid enters the fluid input header 10
and flows into the fluid channels 14. The fluid channels 14 and the
cooling fins 16 are made of a thermally conductive material to
enhance heat transfer from the fluid flowing through the fluid
channels 14 to the cooling fins 16. The cooling fins 16 are exposed
to airflow for cooling. The airflow is provided in a direction that
is perpendicular to a fluid flow direction of the fluid flowing
through the fluid channels 14. In this configuration, each of the
fluid channels 14 is exposed to the same temperature airflow. As
the fluid temperature in each of the fluid channels 14 is the same,
and the air temperature intersecting each of the fluid channels 14
is the same, the temperature difference between the fluid
temperature and the air temperature is the same for each fluid
channel 14. Cooled fluid flows from the fluid channels 14 to the
fluid output header 12 and exits the radiator 2.
[0007] FIG. 2 illustrates a second conventional radiator 4
configured with two-direction fluid flow. The radiator 4 is
configured with a first fluid header 20, a second fluid header 22,
a first set of parallel fluid channels 24, a second set of parallel
fluid channels 25, and a set of cooling fins 26 thermally coupled
to the first set of fluid channels 24 and the second set of fluid
channels 25. The first set of fluid channels 24 are parallel to the
second set of fluid channels 25. Heated fluid enters the first
fluid header 20 and flows into the first set of fluid channels 24.
The first fluid header 20 includes a fluid divider 28 configured to
prevent fluid input to the first fluid header 20 from entering the
second set of fluid channels 25 via the first fluid header 20. The
fluid channels 24 and the cooling fins 26 are made of a thermally
conductive material to enhance heat transfer from the fluid flowing
through the fluid channels 24 to the cooling fins 26. The cooling
fins 26 are exposed to airflow for cooling. Cooled fluid flows from
the fluid channels 24 to the second fluid header 22 and is directed
into the fluid channels 25. The fluid channels 25 are made of a
thermally conductive material to enhance heat transfer from the
fluid flowing through the fluid channels 25 to the cooling fins 26.
Further cooled fluid flows from the fluid channels 25 to the first
fluid header 20 and exits the radiator 4. The fluid divider 28
prevents fluid exiting the fluid channels 25 from recirculating
into the fluid channels 24.
[0008] As in the first conventional radiator 2, the airflow is
provided to the second conventional radiator 4 in a direction that
is perpendicular to a fluid flow direction of the fluid flowing
through the fluid channels 24, 25. In this configuration, each of
the fluid channels 24, 25 is exposed to the same temperature
airflow. However, the fluid flowing through the second set of fluid
channels 25 is cooler relative to the fluid flowing through the
first set of fluid channels 24. Since the air temperature of the
airflow intersecting each of the fluid channels 24, 25 is the same,
there is a greater temperature difference between the airflow and
the fluid flowing through the first set of channels 24 then the
temperature difference between the airflow and the fluid flowing
through the second set of fluid channels 25. Therefore, the cooling
efficiency of the radiator 4 is non-uniform.
[0009] The performance of the radiator depends on an air flow rate
over the cooling fins, a fluid flow rate through the fluid
channels, a surface area of the cooling fins, and the difference in
temperature between the air and the fluid.
[0010] What is needed is a more efficient cooling methodology for
cooling integrated circuits within electronic devices. What is also
needed is a cooling methodology that increases cooling performance
within a given space constraint.
SUMMARY OF THE INVENTION
[0011] A counter flow radiator is air cooled and is applicable for
fluid cooling in electronic systems. Heated fluid, such as heated
liquid or two-phase fluid, enters the counter flow radiator and
travels through a fluid path including multiple micro-conduits,
such as micro-tubes, micro-channels, or micro-ports, while
rejecting the heat from the fluid into fin assemblies coupled to
the micro-conduits. Airflow is directed over the surface of the fin
assemblies to remove heat from the fin assemblies to the air. The
counter flow radiator is configured with multiple cooling cores.
Each cooling core includes at least one layer of micro-conduits and
at least one layer of cooling fin assemblies alternatively stacked
on top of each other. The cooling cores are coupled together in
series along a first direction. The airflow is also directed along
the first direction. The fins are aligned in the direction of air
flow. The heated fluid enters the counter flow radiator through one
or more inlet points in a first header. The one or more inlet
points are positioned on an air exhaust side of the counter flow
radiator. The heated fluid follows a serpentine-like path that
passes though the multiple cooling cores, crossing the air flow
path multiple times, and leaves the counter flow radiator through
one or more outlet points in a second header. The one or more
outlet points are positioned on an air intake side of the counter
flow radiator. One or both of the headers, depending on the number
of cooling cores, include a divider or dividers that selectively
separates the multiple cooling cores and facilitate the
serpentine-like fluid path. The counter flow radiator configuration
improves the thermal efficiency of the radiator by flowing fluid in
an opposite direction of airflow, thereby exposing the hottest
temperature fluid to the hottest temperature air and the coldest
temperature fluid to the coldest temperature air. In some
embodiments of the counter flow radiator, a constant temperature
differential exists in the direction of air flow, across the width
of the heat sink
[0012] In one aspect, a fluid-air heat exchanger includes a
plurality of fluid-air cooling cores, a first fluid header, and a
second fluid header. Each cooling core includes at least one layer
of one or more thermally conductive fluid conduits and at least one
layer of thermally conductive cooling fins coupled to at least one
fluid conduit layer, wherein each fluid conduit is configured along
a first direction from a first end of the cooling core to a second
end of the cooling core, further wherein the plurality of cooling
cores are stacked side by side along a second direction
perpendicular to the first direction such that the fluid conduits
of the plurality of cooling cores are configured in parallel. The
first fluid header is coupled to the first end of each cooling
core, wherein the first header includes an inlet port configured to
receive an input fluid. The second header is coupled to the second
end of each cooling core, wherein the first header and the second
header are configured to direct fluid flow in series from a first
cooling core closest to the inlet port of the first header to each
successively stacked cooling core along the second direction.
[0013] A second cooling core is positioned furthest from the first
cooling core within the plurality of stacked cooling cores. In some
embodiments, the second cooling core is configured to receive an
intake airflow into the fluid-air heat exchanger along the second
direction and the first cooling core is configured to exhaust the
airflow from the fluid-air heat exchanger. If a number of cooling
cores is even, then the first fluid header includes an outlet port
configured to output fluid received from the second cooling core.
In this configuration, the first header includes at least one
divider to separate the inlet port from the outlet port. If a
number of cooling cores is odd, then the second fluid header
includes an outlet port configured to output fluid received from
the second cooling core. In this configuration, the first header
and the second header cumulatively include at least one fluid
divider configured to direct fluid flow from the inlet port to the
outlet port via the plurality of cooling cores. The fluid flows
between the first header, the second header, and from cooling core
to cooling core in a serpentine-like manner. In some embodiments, a
temperature of the input fluid is greater than a temperature of the
fluid output from the outlet port. In this case, a hot-to-cold
fluid temperature gradient is formed along the second direction
from the first cooling core to the second cooling core. In some
embodiments, a temperature of the intake airflow is colder than a
temperature of the exhaust airflow. In this case, a hot-to-cold air
temperature gradient is formed along the second direction from the
first cooling core to the second cooling core.
[0014] In some embodiments, a temperature of the input fluid is
less than a temperature of the fluid output from the outlet port,
and a temperature of the intake airflow is greater than a
temperature of the exhaust airflow. In this case, a cold-to-hot
fluid temperature gradient is formed along the second direction
from the first cooling core to the second cooling core, and a
cold-to-hot air temperature gradient is formed along the second
direction from the first cooling core to the second cooling core.
Each cooling core is exposed to a different temperature
airflow.
[0015] In some embodiments, the inlet port is positioned proximate
a first end of the first fluid header, and the first cooling core
is positioned proximate the first end of the first fluid header and
a first end of the second fluid header. The second cooling core is
positioned proximate a second end of the first fluid header and a
second end of the second fluid header. Each layer of fluid conduits
can include a plurality of individual thermally conductive
micro-tubes, wherein each micro-tube is configured such that fluid
flow therethrough is isolated from each other micro-tube.
Alternatively, each layer of fluid conduits can include a plurality
of individual thermally conductive micro-tubes, wherein each
micro-tube includes one or more common openings with an adjacent
micro-tube such that fluid flow therethrough is intermixed between
adjacent micro-tubes. Each cooling fin is configured along the
second direction. In some embodiments, each cooling core includes a
plurality of core layers, each layer including at least one layer
of cooling fins and a layer of at least one fluid conduit, further
wherein each core layer within a given cooling core is stacked
along a third direction that is perpendicular to the first
direction and perpendicular to the second direction.
[0016] In another aspect, the fluid-air heat exchanger is included
within a fluid-based cooling system. The fluid based cooling system
includes the fluid-air heat exchanger, one or more air movers
configured to provide the intake airflow to the fluid-air heat
exchanger, and a fluid-based cooling loop coupled to the fluid-air
heat exchanger, wherein the cooling loop is configured to provide
heated fluid to inlet port of the first fluid header.
[0017] In yet another aspect, the fluid-air heat exchanger has a
concurrent flow configuration in which the fluid inlet is on the
same side of the heat exchanger as the air flow intake side.
[0018] Other features and advantages of the present invention will
become apparent after reviewing the detailed description of the
embodiments set forth below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 illustrates a first conventional radiator configured
with one-direction fluid flow.
[0020] FIG. 2 illustrates a second conventional radiator configured
with two-direction fluid flow.
[0021] FIG. 3 illustrates an exemplary block diagram of a cooling
system including a counter flow radiator coupled to a fluid-based
cooling loop.
[0022] FIG. 4 illustrates a cut-out perspective view of an
exemplary configuration of the counter flow radiator.
[0023] FIG. 5 illustrates a cut-out, top down view of the counter
flow radiator including the air and fluid flow directions.
[0024] FIG. 6 illustrates a cut-out side view of the first fluid
header including a flow divider.
[0025] FIG. 7 illustrates a cut-out side view of the second fluid
header.
[0026] FIG. 8 illustrates a cut-out, top-down view of a first
exemplary fluid conduit configured such that each micro-conduit is
isolated from each other.
[0027] FIG. 9 illustrates a cut-out, top-down view of a second
exemplary fluid conduit configured where each micro-conduit is
configured to enable fluid intermixing.
[0028] FIG. 10 illustrates the counter flow radiator of FIG. 5
reconfigured to cool an input air flow.
[0029] FIG. 11 illustrates the radiator of FIG. 5 reconfigured for
concurrent flow.
[0030] The present invention is described relative to the several
views of the drawings. Where appropriate and only where identical
elements are disclosed and shown in more than one drawing, the same
reference numeral will be used to represent such identical
elements.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0031] Embodiments of the present invention are directed to a
counter flow fluid-air heat exchanger included within a fluid-based
cooling system, where the cooling system removes heat generated by
one or more heat generating devices within an electronics device or
system. The heat generating devices include, but are not limited
to, one or more central processing units (CPU), a chipset used to
manage the input/output of one or more CPUs, one or more graphics
processing units (GPUs), and/or one or more physics processing
units (PPUs), mounted on a motherboard, a daughter card, and/or a
PC expansion card. The cooling system can also be used to cool
power electronics, such as mosfets, switches, and other high-power
electronics requiring cooling. In general, the cooling system
described herein can be applied to any electronics sub-system that
includes a heat generating device to be cooled.
[0032] In some embodiments, the counter flow fluid-air heat
exchanger is a radiator. As described herein, reference to a
radiator is used. It is understood that reference to a radiator is
representative of any type of fluid-air heat exchanging system
unless specific characteristics of the radiator are explicitly
referenced.
[0033] Heat generated from a heat generating device is received by
a heat exchanger. In some embodiments, the heat exchanger is
configured with fluid channels through which fluid in the cooling
loop passes. As the fluid passes through the heat exchanger, heat
is passed to the fluid, and heated fluid is output from the heat
exchanger and directed to the counter flow radiator. One or more
air movers, such as fans, are coupled to the counter flow radiator.
The heated fluid is input to the counter flow radiator. Airflow
provided by the air mover is directed over and through the counter
flow radiator, thereby cooling the fluid passing therethrough.
Cooled fluid is output from the counter flow radiator.
[0034] FIG. 3 illustrates an exemplary block diagram of a cooling
system 100 including a counter flow radiator coupled to a
fluid-based cooling loop. The cooling loop includes the counter
flow radiator 30, a pump 90, and a heat exchanger 92, each coupled
via fluid lines 94, 96, 98. In this configuration, the cooling loop
is coupled to a radiator inlet via fluid line 94 and to a radiator
outlet via fluid line 96. It is understood that the relative
position of each component in the cooling loop is for exemplary
purposes only. For example, the pump 90 can be positioned on the
inlet side of the counter flow radiator 30, instead of the outlet
side as shown in FIG. 3. One or more air movers (not shown), such
as fans, are coupled to the counter flow radiator 30 so as to
provide airflow to an intake side of the counter flow radiator
30.
[0035] The heat exchanger 92 is coupled to a heat generating device
102. Any conventional coupling means can be used to couple the heat
exchanger 92 to the heat generating device 102. A removable
coupling means is used to enable the heat exchanger to be removed
and reused. Alternatively, a non-removable coupling means is used.
Heat generated by the heat generating device 102 is transferred to
fluid flowing through the heat exchanger 92. The heated fluid is
output from the heat exchanger 92 and input to the counter flow
radiator 30. Although the cooling loop includes a single heat
exchanger 92, the cooling loop can include more than one heat
exchanger coupled in series or parallel to the heat exchanger 92.
In this manner, the cooling loop can be used to cool multiple heat
generating devices, where the multiple heat generating devices are
all coupled to a single circuit board or are distributed on
multiple circuit boards.
[0036] The counter flow radiator includes multiple layered cooling
cores configured in series along a first direction that is opposite
the direction of airflow used to cool fluid flowing through the
counter flow radiator. Heated fluid inputs the counter flow
radiator at a first end and flows through each cooling core in a
serpentine-like path to a second end of the counter flow radiator,
effectively progressing in a direction opposite that of the
airflow. As described herein, reference is made to a counter flow
radiator that includes two layered cooling cores, although the
counter flow radiator can include more than two layered cooling
cores.
[0037] FIG. 4 illustrates a cut-out perspective view of an
exemplary configuration of the counter flow radiator 30. The
counter flow radiator 30 includes two layered cooling cores 50, 52
coupled width-wise in series, a first fluid header 32, and a second
fluid header 34 (FIG. 5). As shown in FIG. 4, the second fluid
header 34 is removed to show a cut out side view of the cooling
cores 50, 52. Each cooling core 50, 52 includes at least one fluid
conduit 38 and at least one layer of cooling fin assemblies 36
thermally coupled to the fluid conduit 38. As shown in FIG. 4, each
cooling core 50, 52 includes three layers of fluid conduits 38 and
four layers of cooling fin assemblies 36. It is understood that
each cooling core can include more or less than the number of fluid
conduit layers and cooling fin assembly layers than those shown in
FIG. 4. The fluid conduits 38 and the cooling fin assemblies 36 are
each made of thermally conductive material such that heat is
transferred from the fluid flowing through the fluid conduits 38 to
the material of the fluid conduits 38, and the heat is further
transferred from the material of the fluid conduits 38 to the
cooling fin assemblies 36. The fluid conduits 38 can be made of the
same or different thermally conductive material(s) as the cooling
fin assemblies 36.
[0038] Each cooling core is aligned in series along a first
direction, indicated as the x-axis in FIG. 4. Each fin in the fin
assembly 36 is also aligned in the first direction. Each fin is
continuous across all of the cooling cores 50, 52. Alternatively,
each fin includes multiple segments aligned along the first
direction. Each fluid conduit 38 extends lengthwise through the
cooling core, referred to as a second direction that is indicated
as the y-axis in FIG. 4. Each fluid conduit 38 includes multiple
micro-conduits 46. Each micro-conduit 46 is made of a thermally
conductive material. A first end of each micro-conduit 46 within
the fluid conduit 38 is coupled to the first fluid header 32, and a
second end of each micro-conduit 46 is coupled to the second fluid
header 34 (FIG. 5).
[0039] The aligned cooling cores 50, 52 form an intake side 31 and
an exhaust side 33. One or more fluid inlets 40 are positioned
proximate the exhaust side 33 of the first fluid header 32. If the
counter flow radiator includes an even number of cooling cores, as
is the case of the counter flow radiator 30 in FIG. 4, then one or
more fluid outlets 42 (FIG. 5) are positioned proximate the intake
side 31 of the first fluid header 32. If the counter flow radiator
includes an odd number of cooling cores, then one or more fluid
outlets are positioned proximate the intake side 31 of the second
fluid header.
[0040] The first fluid header 32 is configured to direct fluid
entering from the fluid inlet 40 into the first end of the
micro-conduits 46 of the cooling core 50, and to direct fluid
exiting from the first end of the micro-conduits 46 of the cooling
core 52 into the fluid outlet 42 (FIG. 5). The first fluid header
32 is also configured to prevent fluid entering from the fluid
inlet 40 from bypassing the cooling core 50 and flowing directly to
the fluid outlet 42 (FIG. 5). FIG. 6 illustrates a cut-out side
view of the first fluid header 32 including a flow divider 44. The
flow divider 44 prevents fluid entering from the fluid inlet 40
from bypassing the micro-conduits 46 of the cooling core 50 and
flowing directly to the fluid outlet 42 (FIG. 5).
[0041] The second fluid header 34 (FIG. 5) is configured to direct
fluid exiting from the second ends of the micro-conduits 46 of the
cooling core 50 into the second ends of the micro-conduits 46 of
the cooling core 52, thereby forming a fluid path from the cooling
core 50 to the cooling core 52. As such, the second fluid header 34
does not include a flow divider. FIG. 7 illustrates a cut-out side
view of the second fluid header 34. As compared to the first fluid
header 32 in FIG. 6, the second fluid header 34 in FIG. 7 does not
include a flow divider, thereby providing fluidic access between
the second ends of the micro-conduits 46 in cooling core 50 and the
second ends of the micro-conduits 46 in the cooling core 52.
[0042] If additional cooling cores are added to the counter flow
radiator, a corresponding number of flow dividers are also added.
For example, if a third cooling core is coupled in series to the
cooling core 52, then a flow divider is added to the second fluid
header between the second cooling core 52 and the third cooling
core so as to prevent fluid exiting the second end of the
micro-conduits 46 in the cooling core 50 from bypassing the second
ends of the micro-conduits 46 in the cooling core 52. In this
example, another flow divider is not added to the first fluid
header. Instead, the portion of the first fluid header that
receives fluid exiting from the micro-conduits 46 in the second
cooling core 52 is extended to couple with the first ends of the
micro-conduits 46 in the third cooling core, thereby enabling fluid
to flow from the first ends of the micro-conduits 46 in the second
cooling core 52 into the first ends of the micro-conduits 46 in the
third cooling core. In this exemplary case, the first fluid header
is not configured with the fluid outlet 42. Instead, the fluid
outlet is configured on the second fluid header. Each of the fluid
headers is adapted in a similar manner for each additional cooling
core added to the counter flow radiator. In general, a flow divider
provides a means for preventing fluid flow. As such, the flow
divider can be implemented as a wall within the header, or the
header itself can be comprised of multiple separate header
components coupled together, where an interface between two
adjoining header components forms a flow divider.
[0043] FIG. 5 illustrates a cut-out, top down view of the counter
flow radiator 30 including the air and fluid flow directions.
Heated fluid is input to the counter flow radiator 30 at the fluid
inlet 40. The fluid inlet 40 is positioned proximate to the exhaust
side 33. The heated fluid flows first into the cooling core that
forms the exhaust side 33, which in this case is the cooling core
50. The fluid flows through the fluid conduits 38 in the cooling
core 50 along the second direction, which in this case is the
negative y-direction. As fluid exits the fluid conduits 38 in the
cooling core 50, the fluid is directed along the first direction,
which in this case is the positive x-direction, to the fluid
conduits 38 in the cooling core 52 via the second fluid header 34.
The fluid flows through the fluid conduits 38 in the cooling core
52 opposite the second direction, which in this case is the
positive y-direction. As fluid exits the fluid conduits 38 in the
cooling core 52, the fluid is directed out of the fluid outlet 42
via the first fluid header 32. In this manner, the fluid flows in a
serpentine-like direction, back and forth along the second
direction while progressing along the first direction. As the
heated fluid flows through the fluid conduits, heat is transferred
from the fluid to the cooling fin assemblies 36. The fluid begins
to cool as it flows through the cooling core 50, and the fluid
continues to cool as it passes through the cooling core 52 so that
the fluid flowing through the cooling core 50 is hotter than the
fluid flowing through the cooling core 52. The coldest fluid is the
fluid output from the counter flow radiator 30, and the hottest
fluid is the fluid input to the counter flow radiator.
[0044] Airflow directed at the counter flow radiator 30 is input at
the intake side 31 and output at the exhaust side 33. In this
manner, airflow is directed through the cooling cores 50, 52
opposite the first direction, that is the negative x-direction. As
the air passes over the cooling fin assemblies 36, heat is
transferred from the cooling fin assembles 36 to the air.
Therefore, the further the air passes through the counter flow
radiator 30, the hotter the air becomes. The coldest air is the air
at the intake side 31 of the counter flow radiator 30, and the
hottest air is the air output at the exhaust side 33 of the counter
flow radiator. The fluid at the intake side is exposed to cooler
air than the fluid at the exhaust side because the air at the
exhaust side has been heated from fluid it has passed while passing
from the intake side to the exhaust side.
[0045] Each fluid conduit 38 includes a plurality of micro-conduits
46. In some embodiments, each of the micro-conduits 46 are isolated
from each other and fluid flowing through each micro-conduit 46
does not intermix with fluid flowing within each of the other
micro-conduits 46.
[0046] FIG. 8 illustrates a cut-out, top-down view of a first
exemplary fluid conduit configured such that each micro-conduit 46
is isolated from each other. In this case, the fluid intermixes at
each fluid header as the fluid exits the micro-conduits 46, for
example at the fluid header 34. The micro-conduits 46 are made of
thermally conductive material that enables heat transfer with the
fluid flowing through the micro-conduits 46.
[0047] As there are fluid and air temperature gradients from the
intake side of the counter flow radiator to the exhaust side, there
are also fluid and air temperature gradients within the fluid
conduit 38 of each cooling core. Fluid flowing in the
micro-conduits located closer to the exhaust side of the counter
flow radiator interact act with hotter air than fluid flowing in
the micro-conduits closer to the intake side of the counter flow
radiator. If the fluid conduit 38 is configured with isolated
micro-conduits 46, as in the configuration shown in FIG. 8, then a
fluid temperature gradient exists between the intake side and the
exhaust side within a given fluid conduit. In some embodiments, the
fluid conduit 38 is configured as a single channel, without
micro-conduits. In this configuration, fluid is not isolated to one
position relative to the intake side and the exhaust side, and
intermixing of the fluid from the intake side to the exhaust side
occurs as the fluid flows through the fluid conduit 38. Although
sufficient intermixing may or may not occur to completely eliminate
the fluid temperature gradient between the intake side and the
exhaust side, the fluid temperature gradient in the single channel
configuration is less than the fluid temperature gradient in the
isolated micro-conduit configuration.
[0048] A disadvantage of the single channel configuration is a
reduction in the thermal transfer rate between the fluid and the
fluid conduit relative to the micro-conduit configuration. The
surface area of the micro-conduits 46 enhance the heat transfer
rate, as compared to the single channel configuration, because of
the larger heat transfer surface area of all the micro-conduits
46.
[0049] In an alternative configuration, each micro-conduit is
configured with side openings that match side openings of adjacent
micro-conduits, thereby enabling intermixing of fluid between
micro-conduits as the fluid flows through the fluid conduit. FIG. 9
illustrates a cut-out, top-down view of a second exemplary fluid
conduit configured such that each micro-conduit 46' is configured
to enable fluid intermixing. Each of the micro-conduits 46' is
configured with micro-conduit openings 48. Adjacent micro-conduits
46' are configured with matching micro-conduit openings 48 such
that fluid flowing through adjacent micro-conduits 46' intermixes
via the micro-conduit openings 48. It is understood that the
positions of the micro-conduit openings 48 shown in FIG. 9 are for
exemplary purposes only. The number and position of micro-conduit
openings can be configured into any pattern, random or non-random,
so as to achieve desired fluid intermixing effects.
[0050] The micro-conduits with openings configuration reduces the
fluid temperature gradient within the fluid conduit relative to the
isolated micro-conduit configuration. However, if the number of
micro-conduits is the same in both the isolated micro-conduit
configuration and the micro-conduits with openings configuration,
then there is a reduction in micro-conduit surface area in the
micro-conduits with openings configuration relative to the isolated
micro-conduit configuration. A reduction in surface area reduces
the thermal transfer rate between the fluid and the micro-conduits.
To increase the surface area, the fluid conduit can be configured
with a greater number of micro-conduits. A fluid conduit including
micro-conduits with openings can be configured with the same
surface area as a corresponding fluid conduit with isolated
micro-conduits be increasing the number of micro-conduits with
openings. In general, the surface area used to perform thermal
transfer can be adjusted in this manner, whether the micro-conduits
are configured as isolated micro-conduits or micro-conduits with
openings.
[0051] In general, the thermal efficiency of the counter flow
radiator is constrained by the system temperature difference
between the input fluid temperature at the exhaust side and the
input air temperature at the intake side. There are diminishing
returns for each added cooling core. As more cooling cores are
added, the cooling core temperature difference (the difference
between the fluid temperature and the air temperature input to the
cooling core) is diminished for each cooling core in the system. So
even though the overall total efficiency of the counter flow
radiator is increased (to a maximum value limited by the system
temperature difference), the efficiency of each cooling core is
diminished with each added cooling core.
[0052] The thermal efficiency of the counter flow radiator can be
adjusted by adjusting the fluid flow rate through counter flow
radiator. The slower the flow rate provides a greater fluid
temperature difference between the input fluid temperature and the
output fluid temperature because there is a longer time period for
the fluid to be exposed to the thermal transfer occurring within
the counter flow radiator. However, the fluid flow rate must also
be determined and balanced against the flow rate conditions
necessary to optimize the heat transfer occurring within the heat
exchanger, where heat is transferred to the fluid from the heat
generating device. In general, the fluid flow rate can be optimized
to achieve the desired system thermal performance and/or desired
cooling core temperature difference for each cooling core.
[0053] The counter flow radiator is described above in terms of
cooling a heated fluid. Specifically, the counter flow radiator
receives a heated fluid as input, cools the heated fluid within the
radiator, and outputs a cooled fluid. The heated fluid is cooled
using a fluid-to air cooling method in which an input air flow
passes through the radiator, and heat from the fluid flowing within
the radiator passes from the fluid, to the radiator material, and
to the air passing over the radiator material. As such, air flow
out of the radiator is hotter than the air flow input to the
radiator. In an alternative embodiment, the counter flow radiator
is configured to cool heated air. In this alternative embodiment, a
cold fluid, such as a refrigerant, is input into the counter flow
radiator and input air passes through the radiator. Heat is
transferred from the input air to the cold fluid flowing through
the radiator. As such, air flow out of the radiator is cooler than
the air flow input to the radiator. Fluid output from the radiator
is hotter than the fluid input into the radiator.
[0054] FIG. 10 illustrates the counter flow radiator of FIG. 5
reconfigured to cool an input air flow. Cold fluid is input to the
counter flow radiator at the fluid inlet 40. The cold fluid flows
through the cooling cores 50 and 52, and is output via the fluid
outlet 42 in a similar manner as that described in relation to FIG.
5. Heated air flow is directed into the counter flow radiator at
the intake side 31. As the air flow passes through the cooling
cores 52 and 50, heat is transferred from the air flow to the cold
fluid flowing through the cooling cores 52 and 50. Cooled air is
output from the counter flow radiator at the exhaust side 33.
Heated fluid is output from the counter flow radiator at the fluid
outlet 42.
[0055] The counter flow radiator is described above in terms of a
"counter flow" configuration in which the air intake side of the
radiator is opposite that of the fluid inlet. In an alternative
embodiment, the radiator is configured as concurrent flow, or
"co-flow", in which either the fluid flow direction through the
radiator is reversed or the air flow direction through the radiator
is reversed in comparison to the counter flow radiator.
Specifically, in this alternative embodiment, the fluid inlet and
the air flow intake side are on the same side of the radiator, and
the fluid outlet and the air flow exhaust side are on the same side
of the radiator.
[0056] FIG. 11 illustrates the radiator of FIG. 5 reconfigured for
concurrent flow. Heated fluid is input to the concurrent flow
radiator at the fluid inlet 40. The heated fluid flows through the
cooling cores 50 and 52, and is output via the fluid outlet 42 in a
similar manner as that described in relation to FIG. 5. Air flow is
directed into the radiator at the side 33. As the airflow passes
through the cooling cores 50 and 52, heat is transferred from the
heated fluid to the air flow passing through the cooling cores 50
and 52. Heated air is output from the radiator at the side 31.
Cooled fluid is output from the radiator at the fluid outlet
42.
[0057] Similarly to the counter flow radiator of FIG. 10, the
concurrent flow radiator of FIG. 11 can be configured to cool
heated air. In this alternative embodiment, a cold fluid is input
into the concurrent flow radiator and input heated air passes
through the radiator, where the air intake side is on the same side
of the radiator as the fluid inlet. Heat is transferred from the
heated air to the cold fluid flowing through the radiator. As such,
air flow out of the radiator is cooler than the air flow input to
the radiator. Fluid output from the radiator is hotter than the
fluid input into the radiator.
[0058] 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 modifications may be made in the embodiment chosen for
illustration without departing from the spirit and scope of the
invention.
* * * * *