U.S. patent application number 11/641585 was filed with the patent office on 2007-08-30 for multi-chamber spray cooling system.
This patent application is currently assigned to Isothermal Systems Research, Inc.. Invention is credited to Paul A. Knight, Charles L. Tilton.
Application Number | 20070199340 11/641585 |
Document ID | / |
Family ID | 46326864 |
Filed Date | 2007-08-30 |
United States Patent
Application |
20070199340 |
Kind Code |
A1 |
Knight; Paul A. ; et
al. |
August 30, 2007 |
Multi-chamber spray cooling system
Abstract
The present invention uses multiple global cooling chambers for
providing liquid cooling to a plurality of electronic components.
The global cooling chambers utilize a non-electrically conductive
fluid which is in direct contact with the components to be cooled.
The system provides very effective heat transfer rates,
environmental isolation of the electronics components and can be
deployed in a wide range of applications. Multiple global cooling
chambers allows for the hot swapping of cards during operation of
the system.
Inventors: |
Knight; Paul A.; (Spokance,
WA) ; Tilton; Charles L.; (Colton, WA) |
Correspondence
Address: |
Isothermal Systems Research, Inc.
2218 North Molter Road
Liberty Lake
WA
99019
US
|
Assignee: |
Isothermal Systems Research,
Inc.
Liberty Lake
WA
|
Family ID: |
46326864 |
Appl. No.: |
11/641585 |
Filed: |
December 18, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10648774 |
Aug 25, 2003 |
7150109 |
|
|
11641585 |
Dec 18, 2006 |
|
|
|
Current U.S.
Class: |
62/259.2 ;
62/310 |
Current CPC
Class: |
F28D 15/0266 20130101;
H05K 7/20345 20130101; H05K 7/1425 20130101; F28D 5/00
20130101 |
Class at
Publication: |
062/259.2 ;
062/310 |
International
Class: |
F25D 23/12 20060101
F25D023/12; F28D 5/00 20060101 F28D005/00 |
Claims
1. A closed loop liquid cooling system comprising: a chassis having
a plurality of sealed cooling chambers for housing one or more
electronic cards; a plurality of spray modules located within said
plurality of cooling chambers for receiving a supply of dielectric
liquid coolant and providing two-phase cooling to said one or more
electronic cards; a backplane electrically connecting said one or
more electronic cards; and, a plurality of removable faceplates
attached to said chassis, for sealing said electronic cards within
said plurality of cooling chambers.
2. The closed loop liquid cooling system of claim 1, wherein said
plurality of removable faceplates are made from a clear
material.
3. The closed loop liquid cooling system of claim 1, wherein said
one or more electronic cards include a blade server.
4. The closed loop liquid cooling system of claim 1, wherein said
dielectric fluid is a perfluorocarbon.
5. A closed loop liquid cooling system comprising: a chassis having
a plurality of sealed cooling chambers for housing one or more
electronic cards; a plurality of spray modules located within said
plurality of cooling chambers for receiving a supply of dielectric
liquid coolant and providing two-phase cooling to said one or more
electronic cards; a plurality of sealing connectors attached to
said plurality of cooling chambers and electrically connected to
said one or more electronic cards, a backplane electrically
connecting said plurality of sealing connectors; and, a plurality
of removable faceplates attached to said chassis, for sealing said
electronic cards within said plurality of cooling chambers.
6. The closed loop liquid cooling system of claim 5, wherein said
plurality of removable faceplates are made from a clear
material.
7. The closed loop liquid cooling system of claim 5, wherein said
one or more electronic cards include a blade server.
8. The closed loop liquid cooling system of claim 5, wherein said
dielectric fluid is a perfluorocarbon.
9. A liquid cooling chassis for providing global cooling to a
plurality of electronic cards, said chassis comprising: a plurality
of cooling chambers having a generally cubic structure, said
plurality of cooling chambers having a plurality of access openings
in the front of said chambers and a plurality of electrical
connectors sealed to the back of said chambers; a plurality of
electrical cards connected to said plurality of electrical
connectors of said chassis; a plurality of covers removably
sealable to said plurality of access openings; a plurality of
cooling modules adjacent to said plurality of electronic cards;
and, wherein a liquid cooling system is fluidly connected to said
cooling modules for providing two-phase dielectric cooling to said
plurality of electronic cards.
10. The closed loop liquid cooling system of claim 9, wherein said
plurality of removable faceplates are made from a clear
material.
11. The closed loop liquid cooling system of claim 9, wherein said
one or more electronic cards include a blade server.
12. The closed loop liquid cooling system of claim 9, wherein said
dielectric fluid is a perfluorocarbon.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present invention is a continuation-in-part of U.S.
patent application Ser. No. 10/648,774 filed Aug. 18, 2003 entitled
"Wet-Dry Thermal Management System". The Ser. No. 10/648,744 patent
application is incorporated herein by this reference.
STATEMENT REGARDING FEDERALLY SPONSORED R&D
[0002] Not applicable to this application.
TECHNICAL FIELD
[0003] This invention relates to a liquid cooling system, and more
particularly to a direct liquid cooling system that utilizes a
chassis that contains a plurality of individually sealed
chambers.
BACKGROUND OF THE INVENTION
[0004] Liquid cooling is becoming widely understood in the field of
electronics cooling. Rather than use air to cool heat producing
components, liquid is used to absorb and transport the heat.
Liquids are typically much more efficient than air as a heat
transfer fluid since they have considerably higher thermal
conductivities, specific heat capacities and provide the
opportunity for phase change processes.
[0005] Liquid cooling systems used to cool commercial type
electronics generally utilize a closed loop process. Although some
liquid cooling systems, such as heat pipes, are passive, active
systems provide system flexibility needed for most cooling
applications. With active systems, the fluid is pressurized via one
or more pumps. The pressurized fluid is delivered to the cooling
module wherein the fluid absorbs heat from an electronic component.
The fluid leaving the cooling module is transported to a heat
exchanger wherein the heat is removed from the fluid. Many other
components, such as filters, may be placed into the closed loop
system for additional system functionality.
[0006] There are many ways for the liquid of a cooling system to
absorb heat from the heat producing device. Forced convection is
often used by cold plates. Cold plates replace heat sinks and keep
the fluid separate from the electronics to be cooled. Inside the
cold plate can be features such as micro-channels and
mini-channels, which increase the surface area and overall heat
transfer. Cold plates are required for use with conductive liquid
cooling fluids, such as water. Water must be kept separate from the
electronics since it would obviously short out the circuits and
cause irreparable harm to the electronic systems and
components.
[0007] Dielectric fluids are electrically inert to electronic
components. Depending upon the exact type of fluid, dielectric
fluids typically have breakdown voltages in excess of air.
Fluorinert (a trademark of 3M) is a commercially available
dielectric fluid that has been used in liquid cooling systems for
several decades. Most electronic components can be placed directly
in contact with dielectric fluids, such as Fluorinert. By placing
the fluid in direct contact with components to be cooled, heat
transfer rates can be much greater than typical cold plate systems.
In addition, entire boards having many electronic components of
varying height and shapes can be cooled by a single liquid cooling
system. In addition to Fluorinert, other dielectric fluids are
available such as commonly used refrigerants.
[0008] A significant challenge in using dielectric fluids within
closed loop cooling systems is that they typically have poor heat
transfer properties. Fluorinert, for example, has a thermal
conductivity value in the range of air. Water has a thermal
conductivity several orders of magnitude greater. The result is
that it can be difficult to get heat into dielectric fluids. To
make dielectric fluids effective, two-phase cooling can be
employed. Rather than use single phase heat transfer wherein a
fluid is heated up by sensible heat gains, two-phase cooling takes
advantage of changing liquid into vapor. Liquid absorbs heat and
transforms into vapor which requires substantial amounts of energy.
The vapor is condensed by a heat exchanger back to liquid form. The
result is a highly efficient system. Preferably, thin-film
evaporative cooling is used to maximize heat transfer
coefficients.
[0009] Spray cooling is an ideal thin-film cooling method for
producing effective and efficient dielectric liquid cooling
systems. Fluid is pumped via a pump and delivered to a spray
module. Nozzles, preferably atomizers, break up the liquid into
small drops that travel to the cooling surface with significant
momentum. The drops create a very thin coolant film which readily
changes phase to a vapor state. The drops also entrain vapor within
the module. Entrained vapor can be used to further reduce the
thickness of the cooling film and reduce localized pressures, both
results increase heat transfer coefficients. Spray cooling can be
used within cold plates for systems that have localized heat
sources, and can also be used within global type systems that spray
the fluid directly on entire electronic systems. A coldplate spray
cooling system is described by U.S. Pat. No. 7,104,078 and U.S.
Pat. No. 5,220,804; and a global spray cooling system is described
by U.S. Pat. No. 5,880,931 and U.S. Pat. No. 6,976,528.
[0010] Global spray cooling allows electronics to be used in
revolutionary ways. By creating a completely sealed chamber for the
electronics, the systems can be used in environments that may be
nearly void of air, under water, and in extreme hot and cold.
Global cooling is also ideal for benign environments, such as data
centers. Global cooling can be used for blade servers which
provides the ability to create very power dense systems and
racks.
[0011] One problem with prior art global cooling systems is that
because the electronics reside within a single chamber, the entire
computing system must be shut down in order to provide service and
maintenance of a single board within. Although the maintenance and
service requirements may be perfectly acceptable for global cooling
systems used in airplanes and standalone systems, the requirements
are not optimal for use with systems that must be used in
7.times.24 applications. Computers used in data centers for
example, are expected to be plug and play.
[0012] One method of creating hot-swappable electronics within a
global cooling system is the "clamshell" method, such as described
by U.S. Pat. No. 6,955,062. Cards are completely enclosed by a
chamber. Each chamber has an inlet and an outlet comprised of quick
disconnect couplings or blind mate connectors. The quick disconnect
couplings are part of an electrical backplane. Each chamber can be
removed from the backplane assembly individually. A weakness in the
clamshell design is that the backplane assembly is not
environmentally isolated. The result is that the system can not be
placed in very harsh working environments. In addition, the cards
typically have to be custom designed in order to interface with the
clamshell housing.
[0013] Another problem with prior art global cooling systems that
utilize single and large chambers for cooling, is that a
significant amount of the fluid within is open to the environment
during service and maintenance. Perfluorocarbon type fluids are
very stable molecules, and hence, there is very little risk in the
fluid breaking down. Perfluorocarbon type fluids do have the
ability to absorb significant amounts of air. During maintenance
cycles, it is disadvantageous to have the cooling fluid absorb air,
or non-condensable gases, as during operation the non-condensable
gases cause increased system pressures, saturation temperatures and
temperatures of electronics. Other fluids, such as the Novec family
(a trademark of 3M), may break down into other substances with the
introduction of water, or water vapor. Prior art single chamber
global cooling systems do provide the means to reduce the exposure
of the fluid within the system to fluid and gases as part of the
environment.
[0014] In these respects, the multi-chamber cooling system
according to the present invention substantially departs from
conventional concepts of the prior art, and in doing so provides an
apparatus primarily designed to provide global cooling to
electronics while allowing cards to be hot-swapped.
SUMMARY OF THE INVENTION
[0015] The present invention uses multiple global cooling chambers
for providing liquid cooling to a plurality of electronic
components. The global cooling chambers utilize a non-electrically
conductive fluid which is in direct contact with the components to
be cooled. The system provides very effective heat transfer rates,
environmental isolation of the electronics components and can be
deployed in a wide range of applications. Multiple global cooling
chambers allows for the hot swapping of cards during operation of
the system. Multiple global cooling chambers reduce the amount of
interaction between the cooling fluid and the outside environment
during service and maintenance. Another object of the present
invention is to allow standard air cooled cards to be cooled within
a global cooling system. Yet another object of the present
invention is to allow fluid within individual chambers to drain
back to the reservoir when not in use, or prior to opening the
chamber for service or maintenance.
[0016] These and other features, aspects, and advantages of the
present invention will become better understood with regard to the
following description, appended claims, and accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Preferred embodiments of the invention are described below
with the reference to the following accompanying drawings:
[0018] FIG. 1 is a perspective view of a multi-chamber global
cooling system according to the present invention;
[0019] FIG. 2 is a perspective view of a typical heat producing
electronic card that would be cooled by the multi-chamber global
cooling system of FIG. 1;
[0020] FIG. 3 is a side view of the multi-chamber global cooling
system of FIG. 1, with the end panel of the chamber removed, making
visible a cooling chamber;
[0021] FIG. 4 is a front perspective view of a fluid control
valve;
[0022] FIG. 5 is a rear perspective view of the fluid control valve
of FIG. 4;
[0023] FIG. 6 is a perspective view of a spray module for
dispensing cooling fluid onto the electronic card of FIG. 2;
[0024] FIG. 7 is a front perspective view of a backplane sealing
connector assembly;
[0025] FIG. 8 is a perspective view of the front of an electrical
backplane;
[0026] FIG. 9 is a perspective view of the multi-chamber global
cooling system of FIG. 1 with the side of the chassis removed, the
back and side wall of the chassis are shown to be transparent so
that the backplane chamber of the system is sealed from the outside
environment;
[0027] FIG. 10 is a perspective view of the multi-chamber global
cooling system of FIG. 1, with the side of the chassis removed and
a chamber cover in the open position;
[0028] FIG. 11 is an alternative embodiment of the present
invention, showing a chassis having cooling chambers that can
support wide cards, or multiple cards within a single chamber;
[0029] FIG. 12 is a side view of an alternative embodiment cooling
chamber having two angled bottom surfaces;
[0030] FIG. 13 is a side view of an alternative embodiment cooling
chamber having two curved bottom surfaces; and,
[0031] FIG. 11 is a flow chart showing the connections between some
of the elements of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0032] Many of the fastening and fluid components utilized and
described in this invention are widely known and used in the field
of the invention, and their exact nature or type is not necessary
for a person of ordinary skill in the art or science to understand
the invention; therefore they will not be discussed in detail.
[0033] As used herein, the term "card" generally refers to an
electronic system that may produce heat. A card may include a blade
server, a networking device, or any type of computer sub-system. In
addition, the card may be a power device, such as a power supply,
or a conversion device such as used for converting alternating
current to direct current, or vice-versa. The present invention
should not be construed to be limited to any one type of card
system.
[0034] As part of the description of the preferred embodiment, the
present invention is described for use with the dielectric fluid
Fluorinert (a trademark of 3M). Fluorinert is brand that represents
a family of perfluorocarbon fluids. Each perfluorocarbon fluid has
unique phase change properties. Fluorinert 5060 is ideal for many
cooling applications as it changes phase from a liquid to a vapor
in the range of 50 degrees Celsius at standard pressures. Other
grades may suit a particular application better than others.
Although the preferred embodiment of the present invention is
described for use with Fluorinert, the present invention should not
be construed to be limited to any particular grade of
Fluorinert.
[0035] In addition, the present invention should not be construed
to be limited to the family of perfluorocarbon fluids. Novec (a
trademark of 3M) is another trade name for a family of dielectric
fluids which can be used within the present invention. HFE7100 (a
trademark of 3M), also known as methoxy-nonafluorobutane, has been
successfully used within global cooling systems. Depending upon the
type of dielectric fluid chosen for use within the present
invention, it is likely to be compatible with different materials,
such as o-rings, adhesives, and electrical connectors. The
preferred embodiment described herein is consistently described for
use with perfluorocarbon fluids. The present invention should not
be construed to be limited to perfluorocarbon fluids however, as
many other dielectric fluids can be used within the scope and
spirit of the invention.
[0036] Although it is preferred to use dielectric fluids within the
present invention, the present invention should not be construed to
be limited to only dielectric fluids. Through the use of coatings
and sealants, non-dielectric fluids can be applied to cards without
causing shorting of the electronic components. Although an object
of the present invention is to allow standard air cooled cards to
be used within global cooling chambers without the need for
secondary processes, the present invention should not be construed
to be limited to dielectric fluids.
[0037] Now referring to FIG. 1, a multi-chamber global cooling
system 20 is shown. Generally, cooling system 20 may provide
two-phase liquid cooling to a heat producing card assembly 60. One
or more of card assembly 60 may reside within a sealed cooling
chamber 33 of a chassis 30. A cover 40 provides access to cooling
chamber 33 so each card can be accessed individually. A valve 50
controls the flow of cooling fluid to and from chamber 33 so
excessive loss of fluid does not occur when each card 60 is
accessed.
[0038] FIG. 14 shows the flow between some of the elements of the
present invention and how they fit into an overall closed loop
cooling system. A reservoir 44 is used for retaining a supply of
liquid coolant. A pump 45 is fluidly connected to reservoir 44 and
is used for converting the lower pressure coolant in reservoir 44
to a supply of higher pressure fluid. Depending upon the
application of the closed loop cooling system, the reduced size of
direct current motors can provide space advantages in comparison to
alternating current pumps. Depending upon applications of the
cooling system, U.S. Pat. No. 6,447,270 and U.S. Pat. No. 7,009,842
both provide advantageous pump configurations. Pump 45 supplies
fluid to a supply fluid connector 57 located on the back of chassis
30. Supply fluid connector 57 is preferably a self sealing type
that minimizes pressure losses of the fluid, as well as minimizes
fluid loss when disconnected and connected. Acceptable fluid
connectors are made available by the Colder Products Company and
Faster Inc.
[0039] Optionally located between pump 45 and supply fluid
connector 57 can be a fluid manifold system. An exemplary manifold
system is described by U.S. Pat. No. 6,958,911 for a "Low Momentum
Loss Fluid Manifold System" which is herein incorporated by
reference in its entirety. A manifold system allows for multiples
of cooling system 20 to be placed into a single application, such
as a network rack used in a data center. Each system 20 can be
removed and placed into the overall cooling system without
disrupting the uptime of the others. In addition, fluid pressure
drops are minimized.
[0040] Supply fluid connector 57 delivers the higher pressure
supply fluid to a supply chamber 32 located within chassis 30.
Supply chamber 32 allows for equalization of pressures and flow to
a valve system 50. Valve system 50 provides the ability to stop and
start the flow of supply fluid to a spray module 80 located in each
of cooling chamber 33. Spray module 80 is used to provide improved
fluid conditions to create two-phase liquid cooling of card 60. The
two-phase liquid cooling process transforms the supply liquid
coolant into a lower pressure return fluid having both vapor and
liquid. This return fluid is transported again, through valve
system 50 so cooling chamber 33 can be completely isolated from the
rest of the cooling system. Return fluid from valve system 50
travels through a return chamber 33 to a return fluid connector 58.
Return fluid connector 58 can be similar to supply fluid connector
57, although due to system impacts it is preferable to make return
fluid connector 58 as large as possible. Pressure drops on the
return side of the fluid system cause increased pressures within
cooling chamber 33, resulting in increased boiling temperatures of
the cooling fluid. Increased boiling temperatures of the fluid
cause a corresponding increase in component temperatures of card
60.
[0041] Return fluid leaving return fluid connector 58 is delivered
to a heat exchanger 43, and can also utilize a low momentum loss
fluid manifold system between. Heat exchanger 43 condenses the
vapor back to a liquid state and can provide sub-cooling of the
liquid. Condensed liquid is returned to reservoir 44 to be
re-pumped by pump 45. Acceptable heat exchanger technologies
include fin and tube as well as bar and plate.
[0042] More detailed, FIGS. 2 through 13 distinctly show the
interconnections of the elements of the present invention. Chassis
30 is shown with typical dimensions to support an array of blade
servers. Card assembly 60 is shown in FIG. 2 as a typical blade
server. Card substrate 62 is shown with dimensions roughly 10
inches tall and 17 inches long. Exact dimensions vary between type
of blade server and manufacturer and hence the present invention
can be optimized for any particular card but is not limited to any
single version. On the back edge of card substrate 62 is an
electrical connector 61 which provides electrical connectivity to
card assembly 60. Typically, a blade server will have at least one
CPU 63. CPU 63 can produce substantial amounts of heat over a
limited surface area. With air cooling, the CPUs typically have
heat sinks.
[0043] Card assembly 60 is surrounded and sealed by cooling chamber
33. Chassis 30 has multiples of cooling chamber 33 which each can
house one or more card assembly 60. Shown in FIG. 7, a sealing
connector assembly 24 has a sealing plate 26 and provides support
to a sealing connector 25. Although sealing plate 26 can be glued
to chassis 30 by means of an adhesive, preferably plate 26 is
removably sealed to chassis 30 by means of an o-ring and pressure
created by screws (not shown) through a sealing plate fastener hole
27 located at the top and bottom of plate 26. Although the exact
dimension and pressures depends upon the size of chamber 33 and
connector plate 26, it is preferable to use an o-ring with 10% to
20% compression when used in a radial seal scenario, and a 20% to
30% compression in a face seal scenario. It is also preferable to
use Viton as the o-ring material as it is chemically compatible
with Fluorinert. Sealing connector 25 may be comprised of one or
more individual connectors as is commonly done in card type
computer systems. Connector 25 may be a commercial type connector,
or a specialized hermetic connector, but in either case it must
provide a seal to the fluid type used. The purpose of sealing
connector assembly 24 is to both provide electrical connection
between card assembly 60 and a backplane assembly 70 and to provide
a seal to cooling chamber 33. As shown, connector assembly 24
allows card assembly 60 to be removed from operation without
disrupting the service of other cards. In the event that a failure
were to occur with connector assembly 24, it can be individually
replaced by removing any fasteners and disconnecting it from
backplane assembly 70.
[0044] Backplane assembly 70 would be typical of computer systems
used today. A backplane substrate 72 holds an array of backplane
connector 71. Backplane 72 may have active components and power
conversion devices and provide input and output of power and
signals via ports (not shown). For instance, a network connection
can be made to the backplane and individual network connections can
be distributed to each card 60 of multi-chamber global cooling
system 20. Card 60 sealed within cooling chamber 33 may directly
communicate with another card located in chassis 30. Backplane
assembly 70 can be fastened to chassis 30 by means of commonly used
standoffs and fasteners (not shown). As shown in FIG. 9 wherein the
back and side walls of chassis 30 are shown transparent, chassis 30
can provide a completely sealed chamber for backplane assembly 70.
The result is preferably an overall system, including backplane
assembly 70, that can be completely sealed from the outside
environment.
[0045] Card 60 is completely sealed within cooling chamber 33 by
means of sealing connector assembly 24, the walls of chassis 30,
cover 40 and valve 50. Cover 40 is preferably rotatably connected
to chassis 30 through the use of a hinge joint. Cover 40 has a
cover mounting groove 47 which engages with a chassis hinge pin 37.
Cover 40 can rotate and be sealed to chassis 30 by means of an
o-ring (not shown) which is compressed by a common fastener (not
shown) though a cover fastener hole 46. The dimensions and
compression forces for cover 40 should be similar to that of
sealing connector assembly 24, already described herein. Cover 40
is preferably made from a clear plastic that is chemically
compatible with the cooling fluid. Polycarbonate is suitable for
use with perfluorocarbon fluids. The clear material makes it
possible for the user to see the spray within cooling chamber 33
and any indicator lights on card assembly 60. In addition, and for
use with fluids that may have negative effects when exposed to
ultraviolet light, cover 40 may be made from a material that does
not allow for the transmission of ultraviolet light to the cooling
fluid. This may be accomplished by the base material of cover 40,
or a film, or coating, may be applied to nearly any base material.
Such a ultraviolet reflecting or absorbing cover may be
advantageous when fluids from the Novec family (a trademark of 3M)
are used.
[0046] Mounted within cooling chamber 33 is spray module 80. Spray
module 80 receives supply fluid from a supply port 36 which is on
the output side of a supply passage of valve 50. An o-ring (not
shown) seals spray module 80 to supply port 36 and a common
fastener (not shown) through module fastener hole 82 secures spray
module 80 in place. Fluid travels between the two thin plates of
spray module 80 wherein a nozzle 83 dispenses the fluid onto card
assembly 60. Nozzle 83 may be a simple orifice creating a jet of
fluid, or preferably a pressure swirl atomizer. Typical atomizer
orifice sizes are six-thousandths to twelve-thousandths of an inch
in diameter. At fifteen pounds per square inch of supply pressure,
a flow rate of twenty milliliters per minute provides acceptable
heat transfer rates. Too much flow causes incomplete vaporization
of supply fluid and too little causes dry out and component
failures.
[0047] For most applications more than one nozzle 83 is needed for
complete cooling coverage of card assembly 60. Multiples of nozzle
83 may be placed in a rectangular array, or can be optimized by
having a more dense population over higher heat producing
components, such as CPU 63, and less dense populations over lower
heat flux zones. It is also possible to have a fewer number of
nozzles with wider spray angles over lower heat flux areas.
[0048] In addition to size and flow of individual nozzles, it is
also possible to optimize the cooling mode within each cooling
chamber 33. U.S. Pat. No. 7,009,842 for a "Three Dimensional
Packaging and Cooling of Mixed Signal Mixed Power Density
Electronic Modules" is incorporated in its entirety by this
reference. U.S. Pat. No. 7,009,842 teaches optimizing cooling
modes, such as but not limited to direct impingement, narrow gap or
transverse spray, and vapor entrainment, depending upon the
geometry and cooling characteristics of the card system being
cooled. Each card may be shipped by its manufacturer with its own
unique version of spray module 80. For added structural support,
spray module 80 may be secured to card 60 by means of standoffs and
common fasteners (not shown).
[0049] Fluid is delivered to spray module 80 by means of a chassis
valve chamber 38 which houses valve assembly 50. Vapor and leftover
liquid coming from card 60 within cooling chamber 33 enters chassis
valve chamber 38 via return port 35. The bottom surface of cooling
chamber 33 can be flat, but preferably it has an angled chassis
bottom 34 which provides the means to allow gravity to assist the
fluid momentum of the system in getting excess liquid within
chamber 33 to return port 35. If fluid within chamber 33 builds up
excessively it can deplete reservoir 44, increase the quantity of
fluid within system 20, and potentially flood card 60. Components
immersed in a pool of dielectric fluid can be susceptible to
overheating as single phase cooling results. Chassis bottom 34
provides the means to minimize the amount of cooling fluid within
cooling chamber 33.
[0050] Valve assembly 50 is axially constrained by chassis valve
chamber 38, but allowed to rotate. An access groove 51 on the front
end of valve 50 allows valve 50 to rotate through the use of a
Phillips style screwdriver. Grooves 51 can be made for use with a
custom tool as well. Valve 50 has a plurality of an o-ring channel
52 which provides seating and retention of an o-ring (not shown).
The plurality of o-ring 52 isolates the supply fluid from the
return fluid, and keeps both from leaking from chassis 30. With the
position of valve 50 in the open position with respect to chassis
valve chamber 38, fluid from supply chamber 32 flows through valve
supply passage 53, through supply port 36 of chassis 30 and into
spray module 80. By rotating valve 50 to the supply closed
position, supply passage 53 is not aligned to supply port 36 and
not open to supply chamber 32, hence no supply fluid flows to spray
module 80.
[0051] Similarly, valve 50 has a return passage 54 that when supply
passage is in the open position also allows for fluid to flow from
cooling chamber 33 through return port 35, into return passage 54,
out a return opening 55 into return chamber 31. The open position
of valve 50 allows fluid to cool card 60 and for the return fluid
to make it to heat exchanger 43. Conversely, when valve 50 is
orientated in the closed position, supply fluid does not make it to
cool card 60 and return fluid within cooling chamber 33 is isolated
within.
[0052] A third position of valve 50 is the drain position. Valve 50
has a single supply passage 53 but two of return passage 54. The
drain position has return passage 54 in line with return port 35,
allowing return fluid to drain from cooling chamber 33 into return
chamber 31, but does not provide for fluid to flow from supply
chamber 32 to supply passage 53. The result is that cooling is not
provided to card 60 and any excess fluid within cooling chamber 33
can flow under the effects of gravity to heat exchanger 43, or
preferably to reservoir 44. The drain position is used when card 60
is off and does not require cooling. Such a time may be appropriate
just prior to card 60 being accessed for maintenance or service.
After valve 50 being in the drain orientation for some time,
primarily vapor may be left inside of cooling chamber 33, reducing
the amount of fluid that may be displaced while servicing any
particular card. After some delay, valve 50 may be rotated from the
drain position to the closed position so card 60 may be accessed
without fluid flow. Valve 50 may be accessed through a cover
opening 41, which allows it to be turned with cover 40 in the
closed and sealed position.
[0053] To install card 60 into cooling system 20, cooling chamber
33 is accessed by means of opening cover 40. Valve 50 should be in
the closed position so that no fluid can flow into or out of
cooling chamber 33. Card 60 is placed inside of cooling chamber 33
with rear connector 61 of card 60 inserted into backplane connector
71. Spray module 80 is placed adjacent to card 60 with supply
connection 81 in direct contact with supply port 36. Cover 40 is
rotated to its upright position so it seals cooling chamber 33.
Valve 50 should be turned to the open position prior to starting up
card 60.
[0054] To remove or access card 60, valve 50 is preferably turned
to the drain position so that no fluid flows out of spray module
80. A brief amount of time should pass before turning valve 50 to
the closed position. This time allows for any excess fluid to flow
from cooling chamber 33 and into return chamber 31. Any fasteners
in cover 40 should be removed prior to rotating it downward and
into the open position. Card 60 can then be removed from chamber
33.
[0055] Other embodiments of the present invention are possible. One
such embodiment is shown in FIG. 11. A multi-card cooling system 90
is shown having a plurality of multi-card chamber 91. Fundamentally
multi-card cooling system is the same as cooling system 20 of the
preferred embodiment with the exception that the size of multi-card
chamber 91 allows for multiple cards to be placed inside of a
single cooling chamber. If two or more cards must be in operation
together, than it may be advantageous to access both cards at the
same time. The chassis may be less expensive to produce, cards may
be swapped quicker, and there is less seal surface requirements,
than the preferred embodiment. According to the present invention,
any number of cooling chambers greater than two may be employed,
and in any combination of single or multiple chambers in a single
chassis.
[0056] Another embodiment of the present invention may utilize two
separate valves rather than a single valve 50. Instead of valve 50
which is capable of shutting on and off both the supply and return
fluids, having two separate valves allows control of each
independently. Low cost plungers can provide the same net function
as valve 50. Two separate valves may be advantageous for
applications that space is not limited.
[0057] Another embodiment of the present invention is shown in FIG.
14. An electronic control system 21 can open and close electronic
valves that control flow of fluid through chassis valve chamber 38.
Electronic solenoid valves can be used instead of valve 50 which
requires manual operation. Electronic control system 21 can be
remotely operated via a software system. Acceptable commercially
available solenoid valves can be obtained from Clippard Inc.
[0058] Yet another embodiment is shown in FIG. 12. The walls of a
cooling chamber are shown. Rather than having a single sloped
bottom chamber surface such as described by the preferred
embodiment, FIG. 12 shows an angled bottom 94. Both sides of an
angled bottom return opening 95 flow towards it. This embodiment
may be preferred for applications wherein system 20 may be placed
in a mobile environment such as on a ship. Fluid would not easily
collect inside cooling chamber 33 regardless of the direction
system 20 is tilted. Another version of an alternative bottom
surface is shown in FIG. 13. A curved bottom 96 causes fluid to
flow to a curved bottom return opening 97. Curved bottom 96 need
not be two dimensional as shown, but rather can have a three
dimensional type curve. It may also have fluid channels protruding
which could help guide fluid to curved bottom return opening
97.
[0059] In yet another embodiment, chassis 30 may be enclosed within
a secondary enclosure. The secondary enclosure would have a
secondary door for access to chassis 30 and the individual
faceplates covers of the cooling system. The result may be a
further sealed cooling system and a system that allows for fluid
reclaim in the event a seal to an individual cooling chamber became
compromised during operation.
[0060] While the multi-chamber global cooling system herein
described constitute preferred embodiments of the invention, it is
to be understood that the invention is not limited to these precise
form of assemblies, and that changes may be made therein without
departing from the scope and sprit of the invention as defined in
the appended claims.
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