U.S. patent application number 13/058316 was filed with the patent office on 2011-06-09 for equipment cooling.
This patent application is currently assigned to BAE SYSTEMS plc. Invention is credited to Nicholas Chandler, David Eatly, Murray James Todd.
Application Number | 20110132016 13/058316 |
Document ID | / |
Family ID | 41569052 |
Filed Date | 2011-06-09 |
United States Patent
Application |
20110132016 |
Kind Code |
A1 |
Chandler; Nicholas ; et
al. |
June 9, 2011 |
EQUIPMENT COOLING
Abstract
Convection cooling channels are provided by means of an at least
partially enclosed open cell metal foam structure for removing heat
from equipment. In particular, an electronic equipment box is
provided having walls comprising sections of open cell aluminium
foam, clad with aluminium, through which air or other types of
coolant may pass to remove heat from heat-generating components
mounted thereon. Other types of equipment, such as electric motors,
may be surrounded by customised sections of open cell metal foam,
appropriately clad, through which a coolant may be channeled. The
foam cell size may be adjusted according to desired coolant flow
rate and weight considerations. Convection cooling structures may
be combined with latent heat storage bodies comprising similar open
cell metal foam structures containing wax, operating in tandem with
the present convection cooling structures in a heat management
solution.
Inventors: |
Chandler; Nicholas; (Essex,
GB) ; Todd; Murray James; (Essex, GB) ; Eatly;
David; (Essex, GB) |
Assignee: |
BAE SYSTEMS plc
|
Family ID: |
41569052 |
Appl. No.: |
13/058316 |
Filed: |
August 10, 2009 |
PCT Filed: |
August 10, 2009 |
PCT NO: |
PCT/GB09/50996 |
371 Date: |
February 9, 2011 |
Current U.S.
Class: |
62/259.1 |
Current CPC
Class: |
Y02E 60/145 20130101;
F28D 20/023 20130101; Y02E 60/14 20130101; F28F 13/003 20130101;
F28F 2270/00 20130101; H05K 7/20127 20130101; H05K 7/20245
20130101; F28F 3/12 20130101 |
Class at
Publication: |
62/259.1 |
International
Class: |
F25D 31/00 20060101
F25D031/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 13, 2008 |
EP |
08275044.9 |
Aug 13, 2008 |
GB |
0814776.1 |
Claims
1. An equipment cooling apparatus, comprising a structure formed at
least in part by an open cell foam made using a thermally
conducting material, wherein said structure is arranged to enable a
coolant to pass through the foam for removing heat conducted into
the foam from equipment to be cooled.
2. The equipment cooling apparatus according to claim 1, wherein
said structure comprises a panel of said open cell foam arranged to
provide a duct for the passage of said coolant.
3. The equipment cooling apparatus according to claim 1, wherein
said structure comprises a panel of said open cell foam arranged to
provide a duct for the passage of said coolant, and wherein said
apparatus is a cooled equipment box and said panel is a structural
component of the box.
4. The equipment cooling apparatus according to claim 3, wherein
said panel forms at least a part of a wall of the box.
5. The equipment cooling apparatus according to claim 3, wherein
said box further comprises a panel of said open cell foam that is
detached from the walls of the box and provides equipment cooling
within the box.
6. The equipment cooling apparatus according to claim 3, wherein
the equipment box further comprises a chimney, detached from the
walls of the box, formed using said open cell foam to provide a
supplementary passage for said coolant and for removing heat from
equipment thermally linked thereto.
7. The equipment cooling apparatus according to claim 2, wherein
said panel is provided with propelling means for propelling said
coolant through the panel.
8. The equipment cooling apparatus according to claim 1, wherein
said structure is shaped to correspond with the shape of a piece of
equipment to be cooled.
9. The equipment cooling apparatus according to claim 1, wherein
said structure is shaped to correspond with the shape of a piece of
equipment to be cooled, and wherein said structure is shaped to at
least partially enclose the piece of equipment to be cooled.
10. The equipment cooling apparatus according to claim 1, wherein
said structure further comprises an enclosed section formed using
said open cell foam and containing a latent heat thermal storage
material to provide a heat storage body, thermally linked to that
portion of the structure arranged to pass said coolant.
11. The equipment cooling apparatus according to claim 1, wherein
said coolant comprises a gas or a mixture of gases.
12. The equipment cooling apparatus according to claim 1, wherein
said coolant comprises a liquid.
13-17. (canceled)
18. An equipment cooling apparatus, comprising a structure formed
at least in part by an open cell foam made using a thermally
conducting material, wherein said structure is arranged to enable a
coolant to pass through the foam for removing heat conducted into
the foam from equipment to be cooled, wherein said structure
further comprises an enclosed section formed using said open cell
foam and containing a latent heat thermal storage material to
provide a heat storage body, thermally linked to that portion of
the structure arranged to pass said coolant.
19. The equipment cooling apparatus according to claim 18, wherein
said structure comprises a panel of said open cell foam arranged to
provide a duct for the passage of said coolant, and wherein said
apparatus is a cooled equipment box and said panel is a structural
component of the box.
20. The equipment cooling apparatus according to claim 19, wherein
the equipment box further comprises a chimney, detached from the
walls of the box, formed using said open cell foam to provide a
supplementary passage for said coolant and for removing heat from
equipment thermally linked thereto.
Description
[0001] This invention relates to cooling for equipment, in
particular but not exclusively to the use of an open cell
foam-filled ducting for convection cooling of electronic and other
heat-generating equipment.
[0002] From a first aspect the present invention resides in an
equipment cooling apparatus, comprising a structure formed at least
in part by an open cell foam of a thermally conducting material,
wherein the structure is arranged to enable a coolant to pass
through the foam for removing heat conducted into the foam from
equipment to be cooled.
[0003] The use of an open cell foam in such a cooled structure has
been found to be particularly advantageous in that it provides a
large surface area in contact with the coolant and the open cell
nature of the material enables coolant to flow relatively easily
through the structure.
[0004] An open cell foam structure may be formed or cut to any
desired shape due to the structurally homogeneous nature of the
open cell foam. For example the structure may be shaped to at least
partially enclose or to fit closely to the surface of a piece of
equipment to be cooled.
[0005] In one convenient implementation, the structure comprises a
panel of the open cell foam arranged to provide a duct for the
passage of the coolant. In a preferred embodiment, one or more such
panels may be used to form walls or parts of a wall of a cooled
equipment box, or they may be detached from the walls of the box to
provide supplemental equipment cooling within the box.
Alternatively, or in addition, the equipment box may further
comprise a chimney, detached from the walls of the box, formed
using the open cell foam to provide a supplementary passage for the
coolant and for removing heat from equipment thermally linked to
it.
[0006] In a further preferred embodiment, a panel of the open cell
foam may be provided with one or more fans for propelling air
through the panel, so forming a self-contained cooled panel for
equipment thermally linked to it.
[0007] In designing a heat management solution, there are
situations where cooling provided by structures according to this
first aspect of the present invention may be insufficient, at least
for short periods of time. Preferably, therefore, in the cooling
apparatus according to this first aspect of the present invention,
the structure further comprises an enclosed section formed using
the open cell foam and containing a latent heat thermal storage
material to provide a heat storage body, thermally linked to that
portion of the structure arranged to pass the coolant. In this way,
short term demands for higher levels of heat removal may be
accommodated with help from the heat storage body while, during
times of cooler operation, the cooled portion of the structure may
be used to remove heat from the heat storage body. The heat storage
body may contain a phase change material such as wax in which the
wax would be allowed to set during a cooling phase. However, other
types of latent heat thermal storage material may be used in the
heat storage body, including solids such as metal hydrides, for
example.
[0008] The open cell foam may be made using metals, such as
aluminium or copper, or other materials with good thermal
conductivity. The choice of material may depend upon weight
considerations, required levels of thermal conductivity, expansion
properties and mechanical robustness, to name but a few
considerations. Furthermore, the size of the cells in the foam may
be adjusted on the same or similar bases, taking account also of
the nature of the coolant and the required rate of flow of the
coolant through the open cell foam.
[0009] The coolant itself may take a number of different forms.
Typically, air may be pumped or allowed to flow freely through the
structure. However, other types of gas and various types of liquid
may be used as coolants according to the particular cooling
application.
[0010] Preferred embodiments of the present invention will now be
described in more detail and with reference to the accompanying
drawings, of which:
[0011] FIG. 1 is a perspective view of a portion of a cooled
electronics equipment box according to a first preferred embodiment
of the present invention;
[0012] FIG. 2 provides two sectional views through a cooled
electronics equipment box according to a second preferred
embodiment of the present invention;
[0013] FIG. 3 provides a perspective view of a self-contained
cooling panel according to a third preferred embodiment of the
present invention;
[0014] FIG. 4 provides a perspective view and a cross-sectional
view of a cooling structure for at least partially enclosing a heat
source such as an electric motor, according to a fourth preferred
embodiment of the present invention; and
[0015] FIG. 5 provides a plan view of an equipment box combining
cooled panels with heat storage panels according to a fifth
preferred embodiment of the present invention.
[0016] Preferred features according to a first embodiment of the
present invention will now be described, with reference to FIG. 1,
in the context of a cooled electronic equipment box.
[0017] Referring to FIG. 1, a perspective view is provided of a
portion of a cooled electronics equipment box 100 comprising a
hollow base plenum chamber 105 having a coolant inlet 110 and a
coolant outlet 115, and four walls 120, 125, 130 and 135 fixed to a
mounting surface of the plenum chamber 105. Each of the walls
120-135 comprises one or more panels of an open cell aluminium
foam, clad in aluminium on those faces forming the inner and outer
faces of the box 100. The open-cell nature of the aluminium foam
panels allows for the flow of air, or other types of coolant such
as water, through selected sections of the walls 120-135. Coolant
is able to flow from the plenum chamber 105 into selected panels
through holes or slots (not shown in FIG. 1) formed in the mounting
surface of the plenum chamber 105 and, after flowing through the
selected panels, may emerge into a lid (not shown in FIG. 1)
comprising a similar plenum chamber into which the coolant may flow
through corresponding holes or slots. The cladding on the faces of
each panel ensures that the panels act as foam-filled ducts through
which the coolant may flow without entering the box 100 itself.
[0018] Cladding or other types of divider may be provided between
panels within or between walls 120-135 of the box 100 to direct or
to increase the flow rate of coolant to selected panels, in
particular to those having heat-producing components mounted
thereon or otherwise thermally linked thereto. The relative
positioning of holes or slots in the mounting surface of the base
105 and of dividers between panels may be arranged to provide for
any desired route through the panels for coolant to flow. Coolant
may for example enter one panel from the plenum chamber 105 and
flow through that and an adjacent panel before emerging from the
adjacent panel into a lid.
[0019] Sources of heat in an electronic circuit, e.g. power
transistors 140, are shown in FIG. 1 fixed directly to the inner
walls of panels 145 and 150 of the box 100. Those panels 145, 150
in particular have been arranged to receive a flow of coolant from
the plenum chamber 105. In an alternative arrangement, a heat
source may be attached to a heat path of high thermal conductivity,
made using metal encapsulated anisotropic graphite or another
high-conductivity material, arranged to conduct heat to the inner
wall of such a panel 145, 150 for removal.
[0020] Omitted from the view provided in FIG. 1 is a plenum chamber
lid arranged to receive and remove coolant emerging from selected
ones of the wall panels 120-135. In the box 100 shown in FIG. 1,
the open cell structure of one panel in each of the walls 130 and
135 has been exposed (155) to allow coolant to emerge from those
panels and to flow into the plenum chamber lid when mounted on the
box 100.
[0021] In the particular example of a box 100 in FIG. 1, each of
the walls 120-135 is constructed from aluminium foam panels of
substantially the same thickness and hence of volume. However,
according to the heat management requirements for the electronics
intended for mounting in the box 100, one or more of the panels may
be of greater thickness than the others, or some of the panels may
comprise only aluminium sheeting of appropriate thickness with no
convection cooling duct provided. An example of this is shown in
sectional views through an alternative electronic equipment box in
FIG. 2 according to a second preferred embodiment of the present
invention.
[0022] Referring to FIG. 2a and to FIG. 2b, a plan view and a
cross-sectional view, respectively, are provided through an
electronic equipment box 200. FIG. 2a shows the box 200 in section
through a plane parallel to a plenum chamber base 260 of the box
200. FIG. 2b provides a cross-sectional view through the same box
in a plane indicated by A-A in FIG. 2a, perpendicular to the plenum
chamber base 260 of the box 200.
[0023] The box 200 is provided with one wall 205 comprising two
open cell aluminium foam panels 210, 215 of differing thicknesses;
the panel 215 having a greater thickness and hence of volume of
open cell aluminium foam than the panel 210. A wall 220 of the box
200 is also provided with an open cell aluminium foam panel 225
similar in thickness to the panel 210, but the remainder of the
wall 220 comprises a section 230 of aluminium sheeting, as do the
other two walls 235 and 240 of the box 200. Four power transistors
245 are shown mounted on the inner wall of the panel 215 and three
circuit boards 250 are shown in position within the box 200 with
their mounting edges in thermal contact with the panels 210 and
225.
[0024] Whereas open cell aluminium foam panels have been shown to
provide both walls and coolant channels in an electronic equipment
box 200, further cooling may be provided by inserting an
appropriately clad, open cell aluminium foam chimney 275 through
the equipment box 200, as shown in section in FIGS. 2a and 2b. As
with the panels 210, 215, 225, coolant may flow through the open
cell foam of the chimney 275. The profile of the chimney 275 may be
tapered, as in a conventional chimney, to improve the ducting of
coolant through the chimney. Heat sources 280 may be mounted or
otherwise thermally linked to the chimney 275 in the same way as
for a wall panel 210, 215, 225.
[0025] Referring in particular to FIG. 2b, the sectional view A-A
though the box 200 shows the plenum chamber base 260 and lid 265 in
place on the box 200 with the panel 215 and the aluminium wall
section 230 shown in position mounted between them. Holes or slots
270 are provided in the mounting surfaces of the base 260 and the
lid 265 to enable coolant to flow between the base 260 and the lid
265 through the open cell aluminium foam of the panel 215 and the
chimney 275, in either direction, to remove heat from the power
transistors 245 and heat sources 280 respectively.
[0026] The increased surface area of open cell thermally conducting
foams in comparison with alternative heat transfer features such as
fins or pins placed in the path of a flowing coolant, makes for a
more effective heat transfer device while providing high structural
rigidity in a lightweight electronics equipment box. The open cell
foam is suitable for use with air coolants or with liquid coolants
such as water, although increased attention to the effective
sealing of joints is required if liquid coolants are to be used, as
would be apparent to a person of ordinary skill in the relevant
art.
[0027] In situations where an equipment box is not required, but a
more self-contained cooling arrangement is required, for example in
the form of panel, a arrangement according to a third embodiment of
the present invention may be used. This arrangement will now be
described with reference to FIG. 3.
[0028] Referring to FIG. 3, a perspective view is provided of a
self-contained cooled panel 300 having heat-producing components
305 mounted thereon. The panel 300 comprises an open cell aluminium
foam panel clad on both main faces and on two of the four edges,
leaving one edge 310 open to the atmosphere and the opposite edge
open for the mounting of three low voltage motorised fans 315 to
blow air through the panel and out of the exposed edge 310, so
carrying heat away from the mounted components 305. The panel 300
may be changed in size and shape, in all three dimensions, and the
number and type of fans may be changed to suit different
applications as required, without departing from the scope of the
present invention as regards this third preferred embodiment.
Furthermore, if a liquid coolant is used, the fans are replaced by
one or more pumps.
[0029] A further application of open cell thermally conducting foam
to the removal of heat from equipment will now be described with
reference to FIG. 4 according to a fourth preferred embodiment of
the present invention.
[0030] Referring to FIG. 4a and to FIG. 4b, a perspective and a
cross-sectional view are provided, respectively, of an enclosing
structure comprising a body 400 of open cell aluminium foam through
which a hole has been formed to accommodate an electric motor 405.
The foam has been clad in aluminium on all the exposed surfaces. A
coolant inlet 410 and a coolant outlet 415 are provided such that
coolant may flow through the enclosing open cell foam structure to
remove heat from the electric motor 405. The volume of the
enclosing structure may be adjusted, for example according to the
amount of heat likely to be generated by the electric motor, the
flow rate of the coolant through the structure and the available
space. The external shape of the enclosing foam structure 400 does
not need to correspond to that of the equipment being enclosed and
cooled.
[0031] Of course, any shape of enclosure may be provided to
completely or partially surround a source of heat with a structure
functionally equivalent to that shown in FIG. 4, clad as required
to contain the coolant as it flows through the open cell foam
enclosure from one or more inlets to one or more outlets. The body
400 may be changed in size and shape, to suit the object to be
cooled. In the case of the coolant being air, the foam may be
unclad in suitable locations, so that the air can enter and exit
the foam without needing to fabricate the inlet 410 and outlet 415
as physical entities.
[0032] Whereas preferred embodiments of the present invention have
been described as using open cell aluminium foam in particular,
other metals and other materials, having good thermal conductivity,
may be used for the foam and the cladding. For all embodiments, the
choice of material (foam or cladding) may be varied to achieve
different mechanical or thermo-mechanical properties such as
strength, stiffness, coefficient of thermal expansion, etc.
according to particular requirements of the application. For
example, copper may be used where weight is not as critical.
Furthermore, the cell structure may be altered to provide larger or
smaller cell sizes according to the available surface area required
for the transfer of heat to the coolant, the type and the required
flow rate of coolant through the open cell structure and the
resultant weight of the structure.
[0033] In providing a heat management solution, besides providing
enhanced convention cooling by the techniques described above, it
may be advantageous to incorporate one or more heat storage bodies
into a cooling arrangement. A heat storage body, based for example
upon a phase change material such as wax, may be used to
accommodate short term higher levels of heat which may be beyond
the capability of the convection cooling structure to handle
without an undesirable increase in temperature of the cooled
equipment.
[0034] Improved heat storage bodies have been developed by the
present Applicant, making use of an open cell foam structure
similar to that used in preferred embodiments of the present
invention to spread heat more effectively through the phase change
material. Such improved heat storage bodies are described in a
co-pending patent application by the present Applicant.
[0035] Conveniently, a structure comprising thermally linked
sections of open cell foam may be made initially without needing to
decide which portions will carry a coolant for convection cooling
and which portions will be filled with wax for heat storage. Having
established the position of heat sources to be cooled, a
corresponding arrangement of convection cooling and heat storage
portions of the cooling structure may be designed and easily
implemented. For example, an equipment box with walls made from
isolated panels of open cell aluminium foam may be easily adapted
to a particular application by using one or more panels as heat
storage bodies and others as convection cooling ducts. One
particular example of such an equipment box will now be described
with reference to FIG. 5, according to a fifth preferred embodiment
of the present invention.
[0036] Referring to FIG. 5, a plan view is provided showing a
cross-section through an equipment box 500 similar in configuration
to that shown in FIG. 1 in that the walls of the box 500 comprise
eight discrete panels 505-540, each formed using an open cell
aluminium foam clad in aluminium on its largest faces and on the
upstanding internal and external edges. Any of the panels 505-540
may be linked to a plenum chamber in a base and a lid or the box
500 (not shown in FIG. 5) for the passage of a coolant by means of
holes of slots as required. Similarly, any of the panels may
contain a phase change material such as wax and be used as a heat
storage body. In the particular example shown in FIG. 5, two of the
panels 510 and 530 contain wax and the remaining panels 505, 515,
520, 525, 535 and 540 remain open and available for the passage of
a coolant. Each of the wax-filled panels 510, 530 abuts and is
preferably thermally bonded to two panels 505, 515, 525, 535
carrying coolant so that, during a cooling phase, heat from the
wax-filled panels 510, 530 may be transferred to and carried away
by the coolant.
[0037] In addition to the walls of the box 500, further structures
are provided within the box 500 to supplement the cooling provided
by the walls 505-540. In particular, an additional panel 545 has
been provided for the passage of coolant and a square-sectioned
heat storage body 550 has been provided comprising an enclosure
containing two portions 555 of open cell aluminium foam containing
wax. The heat storage body 550 has been thermally bonded to the
internal face of the panel 540 so that during a cooling phase of
the heat storage body 550, heat may be conducted away by the cooled
panel 540.
[0038] In principle, and as would be apparent to a person of
ordinary skill in the relevant art, a cooled equipment box may
comprise any desired combination of heat storage panels and coolant
panels, with different panels having different sizes if required.
Any combination of additional coolant carrying structures and heat
storage bodies may be provided within the box, such as those (545,
550) shown in FIG. 5. Such structures are not limited to panel-like
structures and may be shaped according to available space or to the
shape of the equipment to be cooled.
[0039] While the use of cooled structures in combination with heat
storage bodies, both formed using open cell foams of thermally
conducting material, has been described in the context of an
equipment box in this preferred embodiment of the present
invention, any other type or shape of structure may be formed using
such foam materials, appropriately enclosed, according to the
physical requirements of the equipment to be cooled and overall
heat management requirements. Structures such as that described
above with reference to FIG. 4 may comprise one or more partitioned
but thermally linked sections to be made into heat storage
portions, containing a suitable latent heat thermal storage
material. Conveniently, the heat storage portions of such a
structure may closely resemble the coolant conducting portions as
regards their physical structure, so simplifying the manufacture of
such structures. Preferably, a structure may be provided in which
the choice of coolant carrying and heat storage portions need not
be made at the time of manufacture. The structure may be adapted to
suit a particular application by filling selected portions with a
phase change material such as wax. The porous nature of the
structure enables this to be achieved easily at any time prior to
use.
* * * * *