U.S. patent application number 11/291041 was filed with the patent office on 2007-05-31 for system and method for electronic chassis and rack mounted electronics with an integrated subambient cooling system.
This patent application is currently assigned to Raytheon Company. Invention is credited to Albert P. Payton, Kerrin A. Rummel, Richard M. Weber, William G. Wyatt.
Application Number | 20070119199 11/291041 |
Document ID | / |
Family ID | 37950623 |
Filed Date | 2007-05-31 |
United States Patent
Application |
20070119199 |
Kind Code |
A1 |
Weber; Richard M. ; et
al. |
May 31, 2007 |
System and method for electronic chassis and rack mounted
electronics with an integrated subambient cooling system
Abstract
According to one embodiment of the invention, a cooling system
for a heat-generating structure that is disposed in an environment
having an ambient pressure comprises a fluid coolant and three
structures. The first structure allows the heat generating
structure to removably couple to the cooling system. The second
structure reduces a pressure of the fluid coolant to a subambient
pressure at which the fluid coolant has a boiling temperature less
than a temperature of the heat-generating structure. The third
structure directs a flow of the fluid coolant in the form of a
liquid at the subambient pressure in a manner causing the fluid
coolant to be brought into thermal communication with the
heat-generating structure where heat from the heat-generating
structure causes the fluid coolant in the form of the liquid to
boil and vaporize so that the fluid coolant absorbs heat from the
heat-generating structure as the fluid coolant changes state.
Inventors: |
Weber; Richard M.; (Prosper,
TX) ; Rummel; Kerrin A.; (Richardson, TX) ;
Payton; Albert P.; (Sachse, TX) ; Wyatt; William
G.; (Plano, TX) |
Correspondence
Address: |
BAKER BOTTS LLP
2001 ROSS AVENUE
6TH FLOOR
DALLAS
TX
75201
US
|
Assignee: |
Raytheon Company
|
Family ID: |
37950623 |
Appl. No.: |
11/291041 |
Filed: |
November 30, 2005 |
Current U.S.
Class: |
62/259.2 ;
257/E23.088 |
Current CPC
Class: |
H01L 2924/0002 20130101;
F28D 15/0266 20130101; H05K 7/20681 20130101; H01L 23/427 20130101;
H05K 7/207 20130101; H01L 2924/0002 20130101; H01L 2924/00
20130101 |
Class at
Publication: |
062/259.2 |
International
Class: |
F25D 23/12 20060101
F25D023/12 |
Claims
1. A cooling system for a heat-generating structure disposed in an
environment having an ambient pressure, the cooling system
comprising: a fluid coolant; a structure which reduces a pressure
of the fluid coolant to a subambient pressure at which the fluid
coolant has a boiling temperature less than a temperature of the
heat-generating structure. a channel in thermal communication with
the heat generating structure, the channel comprising a plurality
of passages, the channel having an inlet port and an exit port, the
inlet port operable to receive fluid coolant into the channel
substantially in the form of a liquid, and the exit port operable
to dispense of fluid coolant out of the channel substantially in
the form of a vapor; a structure which directs a flow of the fluid
coolant in the form of a liquid into the channel through the inlet
port, heat from the heat-generating structure causing the fluid
coolant in the form of a liquid to boil and vaporize in the channel
so that the fluid coolant absorbs heat from the heat-generating
structure as the fluid coolant changes state; and a vapor passage
in fluid communication with the exit port, each of the plurality of
passages in fluid communication with the vapor passage, the fluid
communication between the plurality of passages and the vapor
passage inhibiting blockage of the exit port when the channel is
subjected to adverse orientations.
2. A cooling system for a heat-generating structure disposed in an
environment having an ambient pressure, the cooling system
comprising: a fluid coolant; a structure which allows the heat
generating structure to removably couple to the cooling system; a
structure which reduces a pressure of the fluid coolant to a
subambient pressure at which the fluid coolant has a boiling
temperature less than a temperature of the heat-generating
structure; and a structure which directs a flow of the fluid
coolant in the form of a liquid at the subambient pressure in a
manner causing the fluid coolant to be brought into thermal
communication with the heat-generating structure, the heat from the
heat-generating structure causing the fluid coolant in the form of
the liquid to boil and vaporize so that the fluid coolant absorbs
heat from the heat-generating structure as the fluid coolant
changes state.
3. The cooling system of claim 2, wherein the heat generating
structure is disposed within a chassis, and the chassis is operable
to removably couple to the cooling system.
4. The cooling system of claim 3, wherein at least one fluid
channel is disposed within the chassis, and the at least one fluid
channel is a portion of the structure which directs the flow of the
fluid coolant to bring the fluid coolant into thermal communication
with the heat generating structure.
5. The cooling system of claim 3, wherein the structure which
directs a flow of the fluid coolant includes a fluid manifold
operable to direct the fluid coolant to a plurality of chassis,
each of the plurality of chassis contains a heat generating
structure, and each of the plurality of chassis is operable to
removably couple to the cooling system.
6. The cooling system of claim 5, wherein the cooling system is
integrated into a rack operable to hold the plurality of chassis,
and the cooling system is a closed system.
7. The cooling system of claim 5, wherein at least one fluid
channel is disposed within at least some of plurality of chassis,
and the at least one fluid channel of the at least some of the
plurality of chassis being a portion of the structure which directs
the flow of the fluid coolant to bring the fluid coolant into
thermal communication with the heat generating structure.
8. The cooling system of claim 7, wherein; the at least one fluid
channel of the at least some of the plurality of channels include
an inlet port and an exit port, the inlet port and the exit port
operable to fluidly couple to the fluid manifold.
9. The cooling system of claim 8, wherein; the cooling system
includes an air removal system operable to remove air that leaks
into the cooling system.
10. A cooling system for a heat-generating structure, the cooling
system comprising: a fluid coolant; a channel in thermal
communication with the heat generating structure, the channel
having an inlet port and an exit port, the inlet port operable to
receive fluid coolant into the channel substantially in the form of
a liquid, and the exit port operable to dispense of fluid coolant
out of the channel substantially in the form of a vapor; a
structure which directs a flow of the fluid coolant in the form of
a liquid into the channel through the inlet port, heat from the
heat-generating structure causing the fluid coolant in the form of
a liquid to boil and vaporize in the channel so that the fluid
coolant absorbs heat from the heat-generating structure as the
fluid coolant changes state; and a structure within the channel
which inhibits blockage of the exit port when the channel is
subjected to adverse orientations.
11. The cooling system of claim 10, wherein the structure which
inhibits blockage of the exit port includes: a vapor passage in
fluid communication with the exit port, the vapor passage including
at least two fluid, one of the fluid passageway in selective fluid
communication with the channel; and a device operable to
selectively close the one of the fluid passageways when the channel
is subjected to adverse orientations.
12. The cooling system of claim 11, wherein the device operable to
selectively close the one of the fluid passageways is a check ball,
which rolls on to a balls seat to selectively close the one of the
fluid passageways.
13. The cooling system of claim 11, wherein the heat-generating
structure is disposed in an environment having an ambient pressure,
the cooling system further comprising: a structure which reduces a
pressure of the fluid coolant to a subambient pressure at which the
fluid coolant has a boiling temperature less than a temperature of
the heat-generating structure.
14. The cooling system of claim 10, wherein the channel comprises a
plurality of passages and the structure which inhibits blockage of
the exit port includes: a vapor passage in fluid communication with
the exit port, each of the plurality of passages in fluid
communication with the vapor passage.
15. A method for cooling a heat-generating structure disposed in an
environment having an ambient pressure, the method comprising:
providing a fluid coolant; removably coupling the heat-generating
structure to at least a portion of the cooling system; reducing a
pressure of the fluid coolant to a subambient pressure at which the
fluid coolant has a boiling temperature less than a temperature of
the heat-generating structure; and bringing the fluid coolant into
thermal communication with the heat-generating structure, so that
the fluid coolant absorbs heat from the heat-generating
structure.
16. The method of claim 15, wherein the heat generating structure
is disposed within a chassis, and removably coupling the
heat-generating structure to at least a portion of the cooling
system includes removably coupling the chassis to the cooling
system.
17. The method of claim 16, wherein at least one fluid channel is
disposed within the chassis, the method further comprising:
transporting the fluid coolant fluid to the at least one fluid
channel to bring the fluid coolant into thermal communication with
the heat-generating structure.
18. The method of claim 16, further comprising: transporting,
through a fluid manifold, the fluid coolant to a plurality of
chassis, each of the plurality of chassis containing a heat
generating structure, and each of the plurality of chassis operable
to removably couple to the cooling system.
19. The method of claim 18, wherein at least one fluid channel is
disposed within at least some of the plurality of chassis, further
comprising: transporting the fluid coolant fluid to the at least
one fluid channel of the at least some of plurality of chassis to
bring the fluid coolant into thermal communication with the
heat-generating structure.
20. The method of claim 19, wherein the at least one fluid channel
of the at least some of the plurality of channels include an inlet
port and an exit port, further comprising: fluidly coupling the
inlet port and the exit port of at least one of the fluid channels
of the at least some of the plurality of chassis to the fluid
manifold.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] This invention relates generally to the field of cooling
systems and, more particularly, to a system and method for
electronic chassis and rack mounted electronics with an integrated
subambient cooling system.
BACKGROUND OF THE INVENTION
[0002] Chassis mounted electronics continue to generate higher and
higher levels of heat or thermal energy. With the generation of
such thermal energy, such chassis mounted electronics need to be
cooled to prevent overheating. However, conventional cooling
systems do not always meet the current or future needs for such
chassis based systems.
SUMMARY OF THE INVENTION
[0003] According to one embodiment of the invention, a cooling
system for a heat-generating structure that is disposed in an
environment having an ambient pressure comprises a fluid coolant
and three structures. The first structure allows the heat
generating structure to removably couple to the cooling system. The
second structure reduces a pressure of the fluid coolant to a
subambient pressure at which the fluid coolant has a boiling
temperature less than a temperature of the heat-generating
structure. The third structure directs a flow of the fluid coolant
in the form of a liquid at the subambient pressure in a manner
causing the fluid coolant to be brought into thermal communication
with the heat-generating structure where heat from the
heat-generating structure causes the fluid coolant in the form of
the liquid to boil and vaporize so that the fluid coolant absorbs
heat from the heat-generating structure as the fluid coolant
changes state.
[0004] Certain embodiments of the invention may provide numerous
technical advantages. For example, a technical advantage of one
embodiment may include the capability to enhance cooling capability
for chassis based systems. Other technical advantages of other
embodiments may include the capability to enable flexibility in the
integration of a cooling system with a heat generating structure or
the capability to compensate for adverse orientations, including
tilting, that may be experienced by a cooling system.
[0005] Although specific advantages have been enumerated above,
various embodiments may include all, some, or none of the
enumerated advantages. Additionally, other technical advantages may
become readily apparent to one of ordinary skill in the art after
review of the following figures and description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] For a more complete understanding of example embodiments of
the present invention and its advantages, reference is now made to
the following description, taken in conjunction with the
accompanying drawings, in which:
[0007] FIG. 1 is a block diagram of a cooling system, according to
an embodiment of the invention; and
[0008] FIG. 2 show an integration of a cooling system with a
chassis of a circuit card assembly, according to another embodiment
of the invention;
[0009] FIG. 3 show an integration of a cooling system with a
chassis of a circuit card assembly, according to another embodiment
of the invention;
[0010] FIGS. 4A and 4B show an integration of a cooling system with
a rack, according to another embodiment of the invention;
[0011] FIG. 5 is a block diagram of a cooling system, according to
another embodiment of the invention;
[0012] FIGS. 6A and 6B illustrate a problem that can develop in a
channel;
[0013] FIGS. 7A, 7B, and 7C illustrate a channel, according to an
embodiment of the invention;
[0014] FIG. 8 is an illustration of an interior wall of cut-away
channel, according to another embodiment of the invention; and
[0015] FIG. 9 illustrates a channel, according to another
embodiment of the invention.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION
[0016] It should be understood at the outset that although example
embodiments of the present invention are illustrated below, the
present invention may be implemented using any number of
techniques, whether currently known or in existence. The present
invention should in no way be limited to the example embodiments,
drawings, and techniques illustrated below, including the
embodiments and implementation illustrated and described herein.
Additionally, the drawings are not necessarily drawn to scale.
[0017] As briefly referenced in the Background, current cooling
systems do not always meet the current or future needs for chassis
based systems. The teachings of certain embodiments of the
invention recognize that systems that rely purely on convection or
conduction cooling provide limited heat removal capability. Some
air flow systems require 4.degree. C. inlet air to maintain the
component temperatures limits, thereby causing undesirably large
temperature gradients. Other air flow systems operating at higher
temperatures (e.g., 49.degree. C.) require undesirably high air
mass flow rates. Additionally, with conventional systems, there is
little, if any, flexibility in the integration of the cooling
system with the structure in which they are cooling. Accordingly,
teachings of some embodiments of the invention recognize a cooling
system that enhances cooling capability for chassis based systems.
Additionally, teachings of some embodiments of the invention
recognize a cooling system that enables flexibility in the
integration of the cooling system with a heat generating
structure.
[0018] Cooling systems may additionally be subjected to adverse
orientations in adverse environments that tilt and rock the cooling
systems. Accordingly, teachings of some embodiments of the
invention recognize components that may be utilized in a cooling
system to compensate for such adverse orientations.
[0019] FIG. 1 is a block diagram of a cooling system 10, according
to an embodiment of the invention. In this embodiment, the cooling
system 10 is shown cooling a circuit card assembly 12. Electronic
or circuit components within the circuit card assembly 12 may take
on a variety of configurations. Accordingly, the details of the
circuit card assembly are not illustrated and described. The
cooling system 10 of FIG. 1 includes channels 23 and 24, pump 46,
inlet orifices 47 and 48, a condenser heat exchanger 41, an
expansion reservoir 42, and a pressure controller 51.
[0020] The circuit card assembly 12 may be arranged and designed to
conduct heat or thermal energy from the electronic or circuit
components on the circuit card assembly 12 to the channels 23, 24.
To receive this thermal energy or heat, the channels 23, 24 may be
disposed on an edge of the circuit card assembly or may extend
through portions of the circuit card assembly 12, for example,
through a thermal plane of circuit card assembly 12. In particular
embodiments, the channels 23, 24 may extend up to the circuit
components, directly receiving thermal energy from the circuit
components. Although two channels 23, 24 are shown in the
embodiment of FIG. 1, one channel or more than two channels may be
used to cool a circuit card assembly 12, according to other
embodiments of the invention.
[0021] In operation, a fluid coolant flows through each of the
channels 23, 24. As discussed later, this fluid coolant may be a
two-phase fluid coolant, which enters inlet conduits 25 of channels
23, 24 in liquid form. Absorption of heat from the circuit card
assembly 12 causes part or all of the liquid coolant to boil and
vaporize such that some or all of the fluid coolant leaves the exit
conduits 27 of channels 23, 24 in a vapor phase. To facilitate such
absorption or transfer of thermal energy, the channels 23, 24 may
be lined with pin fins or other similar devices which increase
surface contact between the fluid coolant and walls of the channels
23, 24. Additionally, in particular embodiments, the fluid coolant
may be forced or sprayed into the channels 23, 24 to ensure fluid
contact between the fluid coolant and the walls of the channels 23,
24.
[0022] The fluid coolant departs the exit conduits 27 and flows
through the condenser heat exchanger 41, the expansion reservoir
42, a pump 46, and a respective one of two orifices 47 and 48, in
order to again to reach the inlet conduits 25 of the channels 23,
24. The pump 46 may cause the fluid coolant to circulate around the
loop shown in FIG. 1. In particular embodiments, the pump 46 may
use magnetic drives so there are no shaft seals that can wear or
leak with time
[0023] The orifices 47 and 48 in particular embodiments may
facilitate proper partitioning of the fluid coolant among the
respective channels 23, 24 , and may also help to create a large
pressure drop between the output of the pump 46 and the channels
23, 24 in which the fluid coolant vaporizes. The orifices 47 and 48
may have the same size, or may have different sizes in order to
partition the coolant in a proportional manner which facilitates a
desired cooling profile.
[0024] A flow 56 of fluid (either gas or liquid) may be forced to
flow through the condenser heat exchanger 41, for example by a fan
(not shown) or other suitable device. In particular embodiments,
the flow 56 of fluid may be ambient fluid. The condenser heat
exchanger 41 transfers heat from the fluid coolant to the flow 56
of ambient fluid, thereby causing any portion of the fluid coolant
which is in the vapor phase to condense back into a liquid phase.
In particular embodiments, a liquid bypass 49 may be provided for
liquid fluid coolant that either may have exited the channels 23,
24 or that may have condensed from vapor fluid coolant during
travel to the condenser heat exchanger 41.
[0025] The liquid fluid coolant exiting the condenser heat
exchanger 41 may be supplied to the expansion reservoir 42. Since
fluids typically take up more volume in their vapor phase than in
their liquid phase, the expansion reservoir 42 may be provided in
order to take up the volume of liquid fluid coolant that is
displaced when some or all of the coolant in the system changes
from its liquid phase to its vapor phase. The amount of the fluid
coolant which is in its vapor phase can vary over time, due in part
to the fact that the amount of heat or thermal energy being
produced by the circuit card assembly 12 will vary over time, as
the circuit card assembly 12 system operates in various operational
modes.
[0026] Turning now in more detail to the fluid coolant, one highly
efficient technique for removing heat from a surface is to boil and
vaporize a liquid which is in contact with a surface. As the liquid
vaporizes in this process, it inherently absorbs heat to effectuate
such vaporization. The amount of heat that can be absorbed per unit
volume of a liquid is commonly known as the latent heat of
vaporization of the liquid. The higher the latent heat of
vaporization, the larger the amount of heat that can be absorbed
per unit volume of liquid being vaporized.
[0027] The fluid coolant used in the embodiment of FIG. 1 may
include, but is not limited to mixtures of antifreeze and water. In
particular embodiments, the antifreeze may be ethylene glycol,
propylene glycol, methanol, or other suitable antifreeze. In other
embodiments, the mixture may also include fluoroinert. In
particular embodiments, the fluid coolant may absorb a substantial
amount of heat as it vaporizes, and thus may have a very high
latent heat of vaporization.
[0028] Water boils at a temperature of approximately 100.degree. C.
at an atmospheric pressure of 14.7 pounds per square inch absolute
(psia). In particular embodiments, the fluid coolant's boiling
temperature may be reduced to between 55-65.degree. C. by
subjecting the fluid coolant to a subambient pressure of about 2-3
psia. Thus, in the embodiment of FIG. 1, the orifices 47 and 48 may
permit the pressure of the fluid coolant downstream from them to be
substantially less than the fluid coolant pressure between the pump
46 and the orifices 47 and 48, which in this embodiment is shown as
approximately 12 psia. The pressure controller 51 maintains the
coolant at a pressure of approximately 2-3 psia along the portion
of the loop which extends from the orifices 47 and 48 to the pump
46, in particular through the channels 23 and 24, the condenser
heat exchanger 41, and the expansion reservoir 42. In particular
embodiments, a metal bellows may be used in the expansion reservoir
42, connected to the loop using brazed joints. In particular
embodiments, the pressure controller 51 may control loop pressure
by using a motor driven linear actuator that is part of the metal
bellows of the expansion reservoir 42 or by using small gear pump
to evacuate the loop to the desired pressure level. The fluid
coolant removed may be stored in the metal bellows whose fluid
connects are brazed. In other embodiments, the pressure controller
51 may utilize other suitable devices capable of controlling
pressure.
[0029] In particular embodiments, the fluid coolant flowing from
the pump 46 to the orifices 47 and 48 may have a temperature of
approximately 55.degree. C. to 65.degree. C. and a pressure of
approximately 12 psia as referenced above. After passing through
the orifices 47 and 48, the fluid coolant may still have a
temperature of approximately 55.degree. C. to 65.degree. C., but
may also have a lower pressure in the range about 2 psia to 3 psia.
Due to this reduced pressure, some or all of the fluid coolant will
boil or vaporize as it passes through and absorbs heat from the
channels 23 and 24.
[0030] After exiting the exits ports 27 of the channels 23, 24, the
subambient coolant vapor travels to the condenser heat exchanger 41
where heat or thermal energy can be transferred from the subambient
fluid coolant to the flow 56 of fluid. The flow 56 of fluid in
particular embodiments may have a temperature of less than
50.degree. C. In other embodiments, the flow 56 may have a
temperature of less than 40.degree. C. As heat is removed from the
fluid coolant, any portion of the fluid which is in its vapor phase
will condense such that substantially all of the fluid coolant will
be in liquid form when it exits the condenser heat exchanger 41. At
this point, the fluid coolant may have a temperature of
approximately 55.degree. C. to 65.degree. C. and a subambient
pressure of approximately 2 psia to The fluid coolant may then flow
to pump 46, which in particular embodiments 46 may increase the
pressure of the fluid coolant to a value in the range of
approximately 12 psia, as mentioned earlier. Prior to the pump 46,
there may be a fluid connection to an expansion reservoir 42 which,
when used in conjunction with the pressure controller 51, can
control the pressure within the cooling loop. 3 psia.
[0031] It will be noted that the embodiment of FIG. 1 may operate
without a refrigeration system. In the context of electronic
circuitry, such as may be utilized in the circuit card assembly 12,
the absence of a refrigeration system can result in a significant
reduction in the size, weight, and power consumption of the
structure provided to cool the circuit components of the circuit
card assembly 12.
[0032] Although components of one embodiment of a cooling system 10
have been shown in FIG. 1, it should be understood that other
embodiments of the cooling system 10 can include more, less, or
different component parts. For example, although specific
temperatures and pressures have been described for one embodiment
of the cooling system, other embodiments of the cooling system 10
may operate at different pressures and temperatures. Additionally,
in some embodiments a coolant fill port and/or a coolant bleed port
may be utilized with metal-to-metal caps to seal them. Further, in
some embodiments, all or a portion of the joints between various
components may be brazed, soldered or welded using metal-to-metal
seal caps.
[0033] FIG. 2 show an integration of a cooling system 100 with a
chassis 162 of a circuit card assembly 112, according to another
embodiment of the invention. The cooling system 100 of FIG. 2 may
utilize similar or different component parts than those outlined in
the block diagram of the cooling system 10 of FIG. 1. In this
integration, components of the cooling system 100 such as, but not
limited to, the condenser heat exchanger, the pump, the pressure
controller, and the expansion reservoir may be disposed in an end
piece 160 on one end of the chassis 162. In a manner similar to
that described above with reference to FIG. 1, the components of
the end piece 160 may circulate fluid coolant through channels 123,
124 that are disposed in coldwalls 163 of the chassis 162. For
example, subambient pressurized fluid coolant may enter the
channels 123, 124 disposed within the coldwalls 163 in a
substantially liquid state.
[0034] Thermal energy from the circuit card assembly 112 boils or
vaporizes at least a portion of the subambient fluid coolant,
allowing in particular embodiments a high heat flux or high heat
load. The fluid coolant exits the channels 124 disposed in the
coldwalls 163 in a substantially vapor state. The heat inherent
within the vapor fluid coolant is then removed as the vapor fluid
coolant travels through the condensing heat exchanger in the end
piece 160. To facilitate this removal, the end piece 160 may
include vents 157 (only one shown in FIG. 2) for the heat exchanger
(not explicitly shown. The vents 157 are operable to interact with
a flow of ambient fluid for transfer of thermal energy. Upon
condensing, the fluid coolant may be circulated back to the
channels 123, 124.
[0035] FIG. 3 show an integration of a cooling system 200 with a
chassis 262 of a circuit card assembly 212, according to another
embodiment of the invention. The integration of the cooling system
200 with the chassis 262 may be similar to that described above
with reference to the embodiment of FIG. 2, except that the chassis
262 of FIG. 3 is removable from the cooling system 200. In this
embodiment, the cooling system 200 may have similar or different
features than the cooling system 100 of FIG. 2 and the cooling
system 10 of FIG. 1. For example, the cooling system 200 of FIG. 3
may includes channels 223, 224 and an end piece 260 with vents 257.
The end piece 260, similar to end piece 160 of FIG. 2 may include,
but is not limited to, a heat exchanger, a pump, a pressure
controller, and an expansion reservoir. The inlet conduit 225 and
exit conduit 227 for the cooling system 200 can also be seen.
[0036] The chassis 262 includes an inner chassis wall 265, which
can be coupled to the channels 223, 224 in a variety of manners,
including, but not limited to, bolting, clamping, or use of a
variety of actuating devices. Thermal energy or heat may be
conducted from components of the circuit card assembly 212 to the
inner chassis wall 265 to the channels 223, 224. From the channels
223, 224, the thermal energy or heat may be transferred through the
remaining portion of the cooling system 200 in a similar manner to
that described above with reference to FIG. 2, namely through
vaporization in the channels 223, 224 and then offloading to a flow
of ambient fluid in the condensing heat exchanger in the end piece
260, for example, through use of the vent 257.
[0037] With the embodiment of FIG. 3, the circuit card assembly 212
and chassis 262 can be can be removed and replaced without
disrupting or disassembling the sealed cooling system 200. Although
the channels 223, 224 have been described as coupling to an inner
chassis wall 265 in this embodiment, in other embodiments the
cooling system may be used to circulate flow directly to the
circuit card assembly 212. In such an embodiment, components of the
circuit card assembly 212 may be attached to a hollow thermal
plane, which may include any of a variety of features to direct
flow or improve heat transfer. In this embodiment, the fluid
coolant may enter the hollow thermal plane in a liquid state and
vaporize within the thermal plane. Such an embodiment may provide
high heat transfer at substantially low fluid flow rates.
[0038] FIGS. 4A and 4B show an integration of a cooling system 300
with a rack 380, according to another embodiment of the invention.
The rack 380 may be designed to hold a plurality of circuit card
assemblies 312 and their associated chassis using shelves 382 or
other suitable components.
[0039] Similar to the embodiments of FIGS. 2 and 3, portions of the
cooling system 300 may be may be disposed in an end piece 360 on an
end of the rack 380. The end piece 360 may include, but is not
limited to, a heat exchanger, a pump, a pressure controller, and a
expansion reservoir. Further details of other components that may
be used with a cooling system 300 are described below in FIG. 5
with reference to another cooling system 400.
[0040] The cooling system 300 of FIGS. 4A and 4B includes a coolant
manifold 308, which may deliver liquid coolant (e.g., received from
the end piece 360) and receive vapor coolant (e.g, for delivery to
the end piece 360). To deliver such liquid coolant and receive
vapor coolant, the coolant manifold 308 may be arranged in a
variety of configurations. In particular embodiments, the coolant
manifold 308 may be vertically disposed in a rear portion of the
rack 380.
[0041] One or more electronic chassis 362 may respectively be
plugged into the manifold 308 to obtain cooling functionality. The
chassis 362 may have a fluid channel 324 in its wall, which contain
an inlet port 325 (e.g., for substantial liquid fluid coolant) and
an exit port 327 (e.g., for substantially vapor fluid coolant). The
inlet port 325 and the exit port 327 of the electronic chassis 362
may respectively be fluidly coupled to the manifold 308 using a
variety of fluid coupling techniques, including but not limited to
techniques which utilize seals, O-rings, and other devices. In this
embodiment, each chassis 362 may utilize the centralized cooling
system 300 without having its own separate cooling system.
[0042] Although the chassis 362 has been described as fluidly
coupling to a coolant manifold 308 in the rack 380 in this
embodiment, in other embodiments, the rack 380 may provide a series
of coolant channels plumbed into the walls of the rack 380.
Accordingly, each chassis 362 would simply slide into its allocated
slot where it may be coupled or clamped to the coolant channels in
a manner similar to that described above with reference to FIG. 3.
An advantage of such an embodiment is that the cooling system may
be sealed. Accordingly, minimized perturbances to such a sealed
system would occur during insertion or removal of a chassis
362.
[0043] FIG. 5 is a block diagram of a cooling system 400, according
to another embodiment of the invention. The cooling system 400 of
FIG. 5 may operate in a similar to the cooling system 10 of FIG. 1;
however, the cooling system 400 of FIG. 5 also incorporates an air
removal system 490. For a variety of reasons, unintended air or
other fluids may be introduced into the cooling system 400. For
example, with reference to FIG. 4, the insertion of the inlet port
325 and the exit port 327 into the coolant manifold 308 may
undesirably insert air or air may undesirably leak into the system,
for example, through O-ring connections used in a fluid coupling
between the inlet port 325 and the manifold 380 or the exit port
327. Accordingly the cooling system 400 utilize the air removal
system 490 to remove air from the cooling system 400. The air
removal system 490 in the embodiment of FIG. 5 includes an air pump
492, a reclamation heat exchanger 494, an air trap 496, and a
reclamation fill valve 498.
[0044] With reference to FIG. 5, the cooling loop for the cooling
system 400 is similar to cooling loop for the cooling system 10 of
FIG. 1 for example, including a pump 460, an expansion reservoir
442, a pressure controller 451, and a condenser heat exchanger 441.
However, air leaks 402 may enter the system at a rack 480 and
travel to the condenser heat exchanger 441. At the condenser heat
exchanger 441, condensed coolant liquid may pass though while air
(and any associated coolant vapor that may be present therein) may
be pumped using air pump 492 to a reclamation heat exchanger 494.
The reclamation heat exchanger 494 may cool the air/coolant vapor
combination, which condenses the vapor from the air stream being
removed from the bottom of the condenser heat exchanger 441.
Coolant separates from the air in a trap 496 while the air exits
through a vent 495. A level switch 497 may be in communication with
a reclamation fill valve 498 to allow the reclamation fill valve
498 to open when recovered coolant is present. The recovered
coolant may be reintroduced to the loop through the reclamation
fill valve 498 and a conduit in communication with the pump 446.
Although one example of an air removal system 490 has been shown
with reference to FIG. 5, other air removal systems may be used in
other embodiments of the invention with more, less, or alternative
component parts.
[0045] FIGS. 6A and 6B illustrate a problem that can develop in a
channel 524. In particular embodiments, the channel 524 may be
positioned adjacent a chassis that is subjected to movement. For
example, the chassis and channel 524 may be subjected to as much as
plus or minus 60.degree. rolling and pitching in a combat vehicle.
In particular embodiments, it is desirable for the interior of the
wall of the channel 524 to be wet, for example, to ensure
appropriate heat transfer. Accordingly, a chamber 502 of the
channel 524 may be substantially filled with liquid fluid coolant.
Vapor that develops during boiling heat transfer needs to be
allowed to exit the channel 524, for example, through a an exit
port 527. However, during such rolling and pitching, an undesirable
vapor pocket 590 can arise as shown in FIG. 6B. When such a vapor
pocket 590 develops, vapor does not exit through the exit port
527.
[0046] FIGS. 7A, 7B, and 7C illustrate a channel 724, according to
an embodiment of the invention. Given the problem with the
development of vapor pockets, the configuration of the channel 724
of FIGS. 7A, 7B, and 7C minimizes development of vapor pockets. The
channel 724 includes a coolant chamber 702, a vapor passage 704, a
rib 706, a check ball 708, a ball stop 710, a ball seat 712, an
inlet port 725, and an exit port 727.
[0047] When the channel 724 is level as shown in FIG. 7A, vapor can
exit from either of the passageways 713, 714 in the upper corners
of the chamber 702. When the channel 724 is tilted with the exit
port 727 upward, the check ball 708 rests on the ball stop 710 as
shown in FIG. 7B. In FIG. 7B, the vapor will exit from the
passageway 713 adjacent the ball seat 712 as the check ball 708
does not block passageway 713. When the channel 724 is tilted with
the exit port 727 downward, the check ball 708 rests on the ball
seat 712 as shown in FIG. 7C. In this case, the check ball 708
closes the passageway 713, which forces the vapor to exit through
passageway 714.
[0048] In the embodiment of FIGS. 7A, 7B, and 7C, the fluid coolant
remains in contact with the wall of the chamber 702 which, for
example, may be lined with pin fins. Accordingly, proper heat
transfer may occur while still allowing vapor to exit the exit port
727.
[0049] FIG. 8 is an illustration of an interior wall 894 of
cut-away channel 824, according to another embodiment of the
invention. The embodiment of FIG. 8 minimizes development of vapor
pockets by using internal jet impingement. The interior wall 894 of
the channel 824 includes a plurality of pin fins 896 extending
therefrom. With internal jet impingement, coolant jets with small
nozzles (not expressly shown) direct coolant on to the plurality of
pin fins 896. The liquid fluid vaporizes upon contact with the pins
fins 896. Accordingly, liquid fluid coolant is not free standing
and vapor pockets do not develop. In operation, the plurality of
pin fins 896 may linearly be aligned in clusters or strips that
coincide with a location where heat transfer is expected to occur,
for example, an edge of the circuit card assembly.
[0050] FIG. 9 illustrates a channel 924, according to another
embodiment of the invention. For purposes of illustration, portions
of the channel 924 are shown in a cut-way view. The channel 924 of
FIG. 9 includes a plurality of walled areas or passages 902
connected by a common vapor passage 904. Each of the passages 902
may be fed liquid coolant through a coolant feed hole 905. In
particular embodiments, each of the passages 902 may be lined with
pin fins 906. The pin fins 906 may couple to a plane of thermal
transfer and extend outwards across each passage 902 to increase
surface area in the thermal transfer. Each of the coolant feed
holes 905 may be connected through a common feed passage 906, which
receives the liquid coolant from an inlet conduit 925.
[0051] In particular embodiments, the feed passage 906 may be
disposed in a separate sheet of material within the channel 924.
For example, the passages 902 may be directly adjacent the plane of
thermal transfer while the feed passage 906 is at least one layer
removed from the plane of thermal transfer. Controlled liquid
coolant may be forced into the bottom of each respective feed hole
905 up through passages 902 transversing the plurality of pin fins
906. As the liquid fluid coolant boils to a vapor state, the vapor
in each passage 902 will move up to the common vapor passage 904.
If the channel 924 is tilted, liquid coolant may run out of one of
the passages 902, cascading over another passage 902. However,
vapor may still escape to the common vapor passage 904 and out an
exit port 927. Each one of the passages 902 may correspond to a
board for a circuit card assembly or another location where heat
may be expected.
[0052] Although the present invention has been described with
several embodiments, a myriad of changes, variations, alterations,
transformations, and modifications may be suggested to one skilled
in the art, and it is intended that the present invention encompass
such changes, variations, alterations, transformation, and
modifications as they fall within the scope of the appended
claims.
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