U.S. patent application number 13/477080 was filed with the patent office on 2012-11-29 for method and apparatus for radiative heat transfer augmentation for aviation electronic equipments cooled by convection.
Invention is credited to Shreesh Mishra, Punit Tiwari.
Application Number | 20120298337 13/477080 |
Document ID | / |
Family ID | 47218440 |
Filed Date | 2012-11-29 |
United States Patent
Application |
20120298337 |
Kind Code |
A1 |
Tiwari; Punit ; et
al. |
November 29, 2012 |
METHOD AND APPARATUS FOR RADIATIVE HEAT TRANSFER AUGMENTATION FOR
AVIATION ELECTRONIC EQUIPMENTS COOLED BY CONVECTION
Abstract
A method and apparatus for radiative heat transfer augmentation
for aviation electronic equipments cooled by forced and/or natural
convection are disclosed. In one embodiment, the apparatus includes
a first heat dissipation device to dissipate heat from the aviation
electronic equipments housed in an aviation electronic equipment
rack using forced convection. Further, the apparatus includes a
second heat dissipation device to enhance heat dissipation from the
aviation electronic equipments by radiation and natural convection.
Furthermore, the second heat dissipation device is strategically
disposed with respect to aircraft skin and configured to maximize
radiative view factor.
Inventors: |
Tiwari; Punit; (Bangalore,
IN) ; Mishra; Shreesh; (Bangalore, IN) |
Family ID: |
47218440 |
Appl. No.: |
13/477080 |
Filed: |
May 22, 2012 |
Current U.S.
Class: |
165/104.26 ;
165/104.34; 165/185 |
Current CPC
Class: |
H05K 7/20681 20130101;
H05K 7/2059 20130101; B64D 2013/0614 20130101; F28D 2021/0021
20130101; F28D 15/0266 20130101 |
Class at
Publication: |
165/104.26 ;
165/104.34; 165/185 |
International
Class: |
F28D 15/04 20060101
F28D015/04; F28F 7/00 20060101 F28F007/00; F28D 15/00 20060101
F28D015/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 24, 2011 |
IN |
1757/CHE/2011 |
Claims
1. An apparatus for radiative heat transfer augmentation for
aviation electronic equipments cooled by convection, comprising: a
first heat dissipation device to dissipate heat from the aviation
electronic equipments housed in an aviation electronic equipment
rack using forced convection; and a second heat dissipation device
strategically disposed with respect to aircraft skin and configured
to maximize radiative view factor to enhance heat dissipation from
the aviation electronic equipments by radiation and natural
convection.
2. The apparatus of claim 1, wherein the first heat dissipation
device dissipates heat from the aviation electronic equipments
using air stream capable of causing forced ventilation.
3. The apparatus of claim 1, wherein the first heat dissipation
device cools the aviation electronic equipments by natural and
forced convection in thermal contact with one or more hot spots of
the aviation electronic equipments.
4. The apparatus of claim 1, wherein the second heat dissipation
device is an external thermal radiator.
5. The apparatus of claim 4, wherein the external thermal radiator
comprises a heat collector that is coupled to the one or more heat
spots of the aviation electronic equipments using thermal
conductors.
6. The apparatus of claim 5, wherein the thermal conductors are
heat pipes.
7. The apparatus of claim 5, wherein the heat pipes have high
thermal conductivity in the longitudinal direction.
8. The apparatus of claim 1, wherein the second heat dissipation
device is sized to complement the cooling provided by the first
heat dissipation device should the forced convection be lost and
wherein the second heat dissipation device is disposed with respect
to the aircraft skin to maximize heat dissipation by radiation.
9. A method of radiative heat transfer augmentation for aviation
electronic equipments cooled by forced and/or natural convection,
comprising: dissipating heat from the aviation electronic
equipments housed in an aviation electronic equipment rack by
forced convection using a first heat dissipation device; and
enhancing heat dissipation from the aviation electronic equipments
by radiation and natural convection using a second heat dissipation
device, wherein the second heat dissipation device is strategically
disposed with respect to aircraft skin and configured to maximize
radiative view factor.
10. The method of claim 9, wherein, in dissipating heat from the
aviation electronic equipments, the first heat dissipation device
dissipates heat from the aviation electronic equipments using air
stream capable of causing forced ventilation.
11. The method of claim 9, wherein, in dissipating heat from the
aviation electronic equipments, the first heat dissipation device
cools the aviation electronic equipments by natural and forced
convection in thermal contact with one or more hot spots of the
aviation electronic equipments.
12. The method of claim 9, wherein the second heat dissipation
device is an external thermal radiator.
13. The method of claim 12, wherein the external thermal radiator
comprises a heat collector that is coupled to the one or more hot
spots of the aviation electronic equipments using thermal
conductors.
14. The method of claim 13, wherein the thermal conductors are heat
pipes.
15. The method of claim 13, wherein the heat pipes have high
thermal conductivity in the longitudinal direction.
16. The method of claim 9, wherein the second heat dissipation
device is sized to complement the cooling provided by the first
heat dissipation device should the forced convection be lost and
wherein the second heat dissipation device is disposed with respect
to the aircraft skin to maximize heat dissipation by radiation.
Description
RELATED APPLICATIONS
[0001] Benefit is claimed under 35 U.S.C. 119(a)-(d) to Indian
Provisional Application Serial No. 1757/CHE/2011 entitled "METHOD
AND APPARATUS FOR RADIATIVE HEAT TRANSFER AUGMENTATION FOR AVIATION
ELECTRONIC EQUIPMENTS COOLED BY CONVECTION" filed on May 24, 2011
by Airbus Engineering Centre India.
FIELD OF TECHNOLOGY
[0002] Embodiments of the present subject matter relate to
dissipating heat from electronic equipments. More particularly,
embodiments of the present subject matter relate to dissipating
heat by radiation augmentation for electronic equipments on board
aircraft cooled by forced and/or natural convection.
BACKGROUND
[0003] Electronic equipments installed inside aircraft, often
contain many heat generating components that are housed in racks.
Existing techniques for cooling such electronic equipments
primarily depend on ventilation systems based on forced and/or
natural convection. Typically, ventilation of such electronic
equipments is based on forced airflow from the bottom of the racks,
which then passes through the electronic equipments. The heated air
coming from the electronic equipments is then collected and
exhausted from the aircraft. Such method of heat extraction is
generally referred to as "forced ventilation". Further, the
ventilation of such electronic equipments is also based on natural
convection. Generally, natural convection does not occur due to
fluid motion generated by an external source (e.g., a pump, a fan,
a suction device and the like), but occurs due to density
difference in the fluid occurring as a result of temperature
gradients.
[0004] However, a failure in the forced ventilation system can lead
to complete dependence of cooling of the electronic equipments by
natural convection and this may not be sufficient and can lead to
failure of the electronic equipments.
SUMMARY
[0005] A method and apparatus for radiative heat transfer
augmentation for aviation electronic equipments cooled by
convection are disclosed. According to one aspect of the present
subject matter, heat from the aviation electronic equipments housed
in an aviation electronic equipment rack is dissipated by forced
convection using a first heat dissipation device. Further, heat
dissipation from the aviation electronic equipments by radiation
and natural convection is enhanced using a second heat dissipation
device. In one embodiment, the second heat dissipation device is
strategically disposed with respect to aircraft skin and configured
to maximize radiative view factor.
[0006] According to another aspect of the present subject matter,
the apparatus for radiative heat transfer augmentation for the
aviation electronic equipments cooled by forced and/or natural
convection includes the first heat dissipation device to dissipate
heat from the aviation electronic equipments housed in the aviation
electronic equipment rack using forced convection. Further, the
apparatus includes the second heat dissipation device to enhance
heat dissipation from the aviation electronic equipments by natural
convection. Furthermore, the second heat dissipation device is
strategically disposed with respect to the aircraft skin and
configured to maximize radiative view factor.
[0007] The methods and apparatuses disclosed herein may be
implemented in any means for achieving various aspects. Other
features will be apparent from the accompanying drawings and from
the detailed description that follow.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Various embodiments are described herein with reference to
the drawings, wherein:
[0009] FIG. 1 is a side elevation view of an aircraft showing
location of avionics bay, in the context of the invention;
[0010] FIG. 2 is an isometric view of the avionics bay in the
aircraft, such as those shown in FIG. 1, in the context of the
invention;
[0011] FIG. 3 is a schematic showing a radiative heat transfer
augmentation technique deployed in the aircraft for aviation
electronic equipments cooled by forced and/or natural convection,
according to one embodiment; and
[0012] FIG. 4 illustrates a flow diagram of an exemplary method for
radiative heat transfer augmentation for the aviation electronic
equipments cooled by forced and/or natural convection, such as
those shown in FIG. 3, according to one embodiment.
[0013] The drawings described herein are for illustration purposes
only and are not intended to limit the scope of the present
disclosure in any way.
DETAILED DESCRIPTION
[0014] A method and apparatus for radiative heat transfer
augmentation for aviation electronic equipments cooled by
convection are disclosed. In the following detailed description of
the embodiments of the present subject matter, reference is made to
the accompanying drawings that form a part hereof, and in which are
shown by way of illustration specific embodiments in which the
present subject matter may be practiced. These embodiments are
described in sufficient detail to enable those skilled in the art
to practice the present subject matter, and it is to be understood
that other embodiments may be utilized and that changes may be made
without departing from the scope of the present subject matter. The
following detailed description is, therefore, not to be taken in a
limiting sense, and the scope of the present subject matter is
defined by the appended claims.
[0015] FIG. 1 is a side elevation view of an aircraft 100 showing
location of avionics bay 102, in the context of the invention.
Particularly, FIG. 1 illustrates a portion of the aircraft 100
including the avionics bay 102, a cockpit 104, a cabin 106 and a
cargo bay 108. As shown in FIG. 1, the avionics bay 102 is,
typically, located below the cockpit 104. However, one can
envision, the avionics bay 102 being located anywhere else in the
aircraft based on the design and configuration of an aircraft.
Further as shown in FIG. 1, the avionics bay 102 includes aviation
electronic equipments housed in racks 110. For example, the
aviation electronic equipments housed in racks 110 can include one
or more aviation electronic equipment racks 110A-N.
[0016] Referring now to FIG. 2, an isometric view of the avionics
bay 102 in the aircraft 100, such as those shown in FIG. 1, is
illustrated, in the context of the invention. Particularly, FIG. 2
illustrates the aviation electronic equipments housed in racks 110,
in the avionics bay 102, including one or more aviation electronic
equipment racks 110A-N. As shown in FIG. 2, each of the aviation
electronic equipment racks 110A-N includes one or more heat
generating aviation electronic equipments. Exemplary aviation
electronic equipments include equipments used for navigation of the
aircraft 100, control of other equipments in the aircraft 100 and
the like. For example, the aviation electronic equipments can also
be arranged in the form of stacks or the aviation electronic
equipments can be placed independently. Further, the aviation
electronic equipments in the aviation electronic equipment racks
110A-N are cooled by forced and/or natural convection.
[0017] In operation, the aviation electronic equipment racks 110A-N
are cooled using sources of cold air 202A-N in each of the aviation
electronic equipment racks 110A-N, respectively, as shown in FIG.
2. Further, the cold air is passed through the aviation electronic
equipments in the aviation electronic equipment racks 110A-N to
extract the heat from the aviation electronic equipments and is
output as hot air. Furthermore as shown in FIG. 2, the hot air is
collected, from the aviation electronic equipment racks 110A-N, in
collectors for disposing hot air 204A-N in each of the aviation
electronic equipment racks 110A-N, respectively. This is explained
in more detail with reference to FIG. 3.
[0018] Referring now to FIG. 3, a schematic 300 shows a radiative
heat transfer augmentation technique deployed in the aircraft 100
for an aviation electronic equipment rack 322 cooled by forced
and/or natural convection, according to one embodiment.
Particularly, FIG. 3 illustrates a first heat dissipation device
320 and a second heat dissipation device for cooling the aviation
electronic equipment rack 322. In one embodiment, the second heat
dissipation device includes an external thermal radiator 308 and
one or more heat pipes 310A-C.
[0019] As shown in FIG. 3, the first heat dissipation device 320
includes the aviation electronic equipment rack 322, a collector
for disposing hot air 304 and a source of cold air 306. For
example, the aviation electronic equipment rack 322 can include any
one of the aviation electronic equipment racks 110A-N, shown in
FIG. 2. Further, the collector for disposing hot air 304 and the
source of cold air 306 can include any of the corresponding sources
of cold air 202A-N and the collectors for disposing hot air 204A-N
associated with the aviation electronic equipment racks 110A-N, as
shown in FIG. 2.
[0020] Further as shown in FIG. 3, the aviation electronic
equipment rack 322 includes a plurality of hot units 312A-F.
Exemplary hot units 312A-F include the heat generating aviation
electronic equipments, as shown in the aviation electronic
equipment racks 110A-N in FIG. 2. However, one can envision a hot
unit in aviation electronic equipments arranged in the form of
stacks or an aviation electronic equipment placed independently.
Furthermore as shown in FIG. 3, each of the hot units 312A-F
include one or more hot spots H314A1-AN, H314B1-BN, H314C1-CN,
H314D1-DN, H314E1-EN and H314F1-FN, respectively. The hot spots in
the hot units 312A-F are heat generating areas in the hot units
312A-F.
[0021] In operation, the first heat dissipation device 320
dissipates heat from the hot units 312A-F housed in the aviation
electronic equipment rack 322 using forced convection. In
dissipating heat from the hot units 312A-F, the first heat
dissipation device 320 uses cold air streams 316 capable of causing
forced ventilation. As shown in FIG. 3, the source of cold air 306
injects cold air streams 316 into the hot units 312A-F. Further as
shown in FIG. 3, the arrows coming from the source of cold air 306
and into the hot units 312A-F indicate the direction of the cold
air streams 316.
[0022] Further in operation, the cold air streams 316 pass through
the hot spots in the hot units 312A-F and is output as hot air
streams 318. As shown in FIG. 3, the dotted line arrows coming from
the hot units 312A-F indicate the direction of the hot air streams
318. Furthermore in operation, the hot air streams 318 are
collected by the collector for disposing hot air 304. Moreover, the
collector for disposing hot air 304 is connected to ventilation
ducts for extracting the hot air streams 318 from the avionics bay
102, shown in FIG. 2, and disposing the hot air streams 318 outside
the aircraft 100. In addition to heat dissipation by forced
convection, the first heat dissipation device 320 also dissipates
heat from the aviation electronic equipment rack 322 by natural
convection, in thermal contact with the hot spots in the hot units
312A-F, shown in FIG. 3.
[0023] In one embodiment, the second heat dissipation device, which
includes the external thermal radiator 308 and the heat pipes
310A-C, enhances heat dissipation from the hot units 312A-F by
natural convection and radiation. In this embodiment, the external
thermal radiator 308 is strategically disposed with respect to
aircraft skin 302 to maximize radiative heat dissipation from the
hot units 312A-F. As shown in FIG. 3, the external thermal radiator
308 includes heat collectors that are coupled to the hot spots in
the hot units 312A-F using thermal conductors. In this embodiment,
the thermal conductors are the heat pipes 310A-C, shown in FIG. 3.
The heat pipes 310A-C have high thermal conductivity in the
longitudinal direction. Further in this embodiment, the heat pipes
310A-C are connected to the hot spots of the hot units 312A-F to
facilitate the heat transfer from the hot units 312A-F to the
external thermal radiator 308.
[0024] Furthermore in this embodiment, the external thermal
radiator 308 is sized to complement the cooling provided by the
first heat dissipation device 320 when the ventilation provided by
the forced convection is lost. Also, the external thermal radiator
308 is configured to maximize heat dissipation by radiation and to
obtain high radiative view factor. The radiative view factor is the
fraction of radiation heat leaving the external thermal radiator
308 which is incident on the aircraft skin 302. In this embodiment,
the external thermal radiator 308 is located and oriented in such a
way that the radiative view factor is maximized. Also in this
embodiment, the hot units 312A-F are strategically disposed in the
avionics bay 102 to maximize the radiative view factor with the
aircraft skin 302.
[0025] Generally, when the aircraft 100 is cruising, the aircraft
skin 302 is at a very low temperature. Therefore, the temperature
difference between the aircraft skin 302 and the surface of the
external thermal radiator 308 is very high. As a result, the heat
dissipated by radiation from the external thermal radiator 308 to
the aircraft skin 302 is maximized. Further, the heat is
transferred from the external thermal radiator 308 in two modes,
which include radiation and convection. The heat transferred from
the external thermal radiator 308 by radiation is transferred to
the aircraft skin 302 and the heat transferred from the external
thermal radiator 308 by convection is transferred to the
surrounding air. Further, the heat transferred from the external
thermal radiator 308 by radiation can be computed using
equation:
q.sub.radiation=.epsilon.A.sigma.F(T.sup.4.sub.surface-T.sup.4.sub.skin)
(1)
wherein,
[0026] q.sub.radiation is radiative heat transfer rate;
[0027] .epsilon. is an emissivity of the surface;
[0028] A is area of emitting surface;
[0029] .sigma. is the Stefan-Boltzmann Constant;
[0030] T.sub.surface is an absolute temperature of emitting surface
of the external thermal radiator 308 (K);
[0031] T.sub.skin is an absolute temperature of the aircraft skin
302 (K); and
[0032] F is a radiative view factor from the surface of the
external thermal radiator 308 to the aircraft skin 302.
[0033] Furthermore, the heat transferred from the external thermal
radiator 308 by convection can be computed using equation:
q.sub.convection=hA(T.sub.surface-T.sub.reference) (2)
wherein,
[0034] q.sub.convection is convective heat transfer rate;
[0035] h is the heat transfer coefficient; and
[0036] T.sub.reference is an absolute temperature of surrounding
air (K).
[0037] It can be seen from the equation (2) that convective heat
transfer is proportional to the difference between the temperature
of the emitting surface of the external thermal radiator 308 and
the surrounding air. Further, it can be seen from the equation (1)
that radiative heat transfer is proportional to difference in
fourth power of temperature values of the aircraft skin 302 and the
external thermal radiator 308. Therefore, it can be seen that,
higher the difference in temperature between the aircraft skin 302
and the external thermal radiator 308, the higher is the radiative
heat flux. The large temperature difference between the aircraft
skin 302 and the external thermal radiator 308 while the aircraft
100 is cruising results in the radiative heat transfer dominating
the convective heat transfer. Since the heat transferred from the
external thermal radiator 308 by radiation is transferred to the
aircraft skin 302, the temperature of the surrounding air is not
increased. This effectively increases the temperature difference
between the emitting surface of the external thermal radiator 308
and the surrounding air resulting in higher convective heat
transfer rates.
[0038] Typically, radiative heat transfer increases the temperature
of the surrounding air when the surrounding air has high humidity
content. However, in this embodiment, the participation of humidity
in the radiative heat transfer is negligible as humidity level in
the avionics bay 102, shown in FIG. 2, while the aircraft is
cruising, is typically very low. Hence, the heat transfer between
the external thermal radiator 308 and the aircraft skin 302 does
not result in an increase in the surrounding air temperature in the
avionics bay 102, shown in FIG. 1.
[0039] Referring now to FIG. 4, which illustrates a flow diagram
400 of an exemplary method for radiative heat transfer augmentation
for the aviation electronic equipment rack 322 cooled by forced
and/or natural convection, such as those shown in FIG. 3, according
to an embodiment. At block 402, heat is dissipated from the
aviation electronic equipments housed in the aviation electronic
equipment rack by forced convection using a first heat dissipation
device. In dissipating heat from the aviation electronic
equipments, the first heat dissipation device uses air stream
capable of causing forced ventilation. Further in dissipating heat
from the aviation electronic equipments, the first heat dissipation
device cools the aviation electronic equipments by natural and
forced convection in thermal contact with one or more hot spots of
the aviation electronic equipments. This is explained in more
detail with reference to FIG. 3.
[0040] At block 404, heat dissipation from the aviation electronic
equipments by radiation and natural convection is enhanced using a
second heat dissipation device. In this embodiment, the second heat
dissipation device is strategically disposed with respect to the
aircraft skin and configured to maximize radiative view factor.
Further in this embodiment, the second heat dissipation device is
an external thermal radiator. Furthermore, the external thermal
radiator includes a heat collector that is coupled to the one or
more heat spots of the aviation electronic equipments using thermal
conductors. The thermal conductors are heat pipes having high
thermal conductivity in the longitudinal direction. This is
explained in more detail with reference to FIG. 3.
[0041] In addition in this embodiment, the second heat dissipation
device is sized to complement the cooling provided by the first
heat dissipation device should the forced convection be lost. Also
in this embodiment, the second heat dissipation device is disposed
with respect to the aircraft skin to maximize heat dissipation by
radiation.
[0042] In various embodiments, the methods and systems described in
FIGS. 1 through 4 enable extracting heat from the aviation
electronic equipment racks in the avionics bay using the external
thermal radiator which increases the radiation heat transfer to the
aircraft skin. Further, the method described in FIGS. 1 through 4
enable substantially eliminating heat transferred to the
surrounding air in the avionics bay.
[0043] Although the present embodiments have been described with
reference to specific example embodiments, it will be evident that
various modifications and changes may be made to these embodiments
without departing from the broader spirit and scope of the various
embodiments. Furthermore, the various devices, modules, analyzers,
generators, and the like described herein may be enabled and
operated using hardware circuitry, for example, complementary metal
oxide semiconductor based logic circuitry, firmware, software
and/or any combination of hardware, firmware, and/or software
embodied in a machine readable medium. For example, the various
electrical structure and methods may be embodied using transistors,
logic gates, and electrical circuits, such as application specific
integrated circuit.
* * * * *