U.S. patent application number 12/995220 was filed with the patent office on 2012-01-05 for cooling of an electronic device in an aircraft by case-by-case single-phase or two-phase cooling.
This patent application is currently assigned to AIRBUS OPERATIONS GMBH. Invention is credited to Wilson Willy Casas Noriega, Matthias Reiss, Sebastian Roering.
Application Number | 20120000630 12/995220 |
Document ID | / |
Family ID | 40823476 |
Filed Date | 2012-01-05 |
United States Patent
Application |
20120000630 |
Kind Code |
A1 |
Reiss; Matthias ; et
al. |
January 5, 2012 |
Cooling Of An Electronic Device In An Aircraft By Case-By-Case
Single-Phase Or Two-Phase Cooling
Abstract
Cooling of an electronic device in an aircraft by case-by-case
single-phase or two-phase cooling There is proposed a method for
cooling an electronic device in an aircraft (11), comprising the
following steps: circulating a coolant in a cooling circuit,
cooling the electronic device (2) by means of the coolant, and in
an aircraft outer-shell heat exchanger, emitting the heat taken up
by the coolant. The coolant evaporates, at least partially, during
the cooling of the electronic device (2), and condenses in the
aircraft outer-shell heat exchanger (7). The coolant circulates in
the coolant circuit by natural convection.
Inventors: |
Reiss; Matthias; (Hamburg,
DE) ; Casas Noriega; Wilson Willy; (Hamburg, DE)
; Roering; Sebastian; (Hamburg, DE) |
Assignee: |
AIRBUS OPERATIONS GMBH
Hamburg
DE
|
Family ID: |
40823476 |
Appl. No.: |
12/995220 |
Filed: |
May 13, 2009 |
PCT Filed: |
May 13, 2009 |
PCT NO: |
PCT/EP2009/003412 |
371 Date: |
May 16, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61057403 |
May 30, 2008 |
|
|
|
Current U.S.
Class: |
165/104.21 ;
165/104.11 |
Current CPC
Class: |
F28D 15/0266 20130101;
H05K 7/20354 20130101; B64D 2013/0614 20130101; B64D 13/00
20130101; B64D 2013/0674 20130101 |
Class at
Publication: |
165/104.21 ;
165/104.11 |
International
Class: |
F28D 15/02 20060101
F28D015/02; F28D 15/00 20060101 F28D015/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 30, 2008 |
DE |
10 2008 025 951.9 |
Claims
1-14. (canceled)
15. Method for cooling an electronic device in an aircraft,
comprising the following steps: circulating a coolant in a cooling
circuit, cooling the electronic device by means of the coolant,
and, in an aircraft outer-shell heat exchanger, emitting the heat
taken up by the coolant, characterized in that, during normal
operation, the coolant is permanently in a liquid phase and
circulates in the coolant circuit by forced convection and, in the
case of a malfunction and/or in the case of an increased cooling
demand, the coolant evaporates, at least partially, during the
cooling of the electronic device, condenses in the aircraft
outer-shell heat exchanger, and circulates in the coolant circuit
by natural convection.
16. Method according to claim 15, characterized in that the coolant
is bypassed past the aircraft outer-shell heat exchanger, at least
partially, if the temperature in the aircraft outer-shell heat
exchanger exceeds a first threshold value.
17. Method according to claim 15, characterized in that the coolant
is cooled case-by-case in an additional heat exchanger, which is
cooled by an additional cooling system.
18. Method according to claim 15, characterized in that the coolant
is bypassed past the aircraft outer-shell heat exchanger, at least
partially, if the temperature in the aircraft outer-shell heat
exchanger and/or the temperature of the coolant falls below a
second threshold value.
19. Aircraft cooling device, comprising a cooling heat exchanger
adapted to cool an electronic device by means of a coolant, and an
aircraft outer-shell heat exchanger adapted to cool the coolant,
wherein the cooling heat exchanger and the aircraft outer-shell
heat exchanger are arranged in a closed coolant circuit,
characterized by a pump device, which, during normal operation,
circulates coolant in the coolant circuit, wherein the aircraft
cooling device is adapted and the coolant is selected such that,
during normal operation, the liquid coolant is permanently in a
liquid phase and, because of the pump device, circulates in the
coolant circuit by forced convection and, in the case of a
malfunction and/or in the case of an increased cooling demand, the
coolant evaporates, at least partially, in the cooling heat
exchanger during the cooling of the electronic device, condenses in
the aircraft outer-shell heat exchanger, and circulates in the
coolant circuit by natural convection.
20. Aircraft cooling device according to claim 19, characterized by
at least one aircraft outer-shell heat-exchanger bypass valve,
which is adapted to bypass the coolant past the aircraft
outer-shell heat exchanger, at least partially, if the temperature
in the aircraft outer-shell heat exchanger exceeds a first
threshold value.
21. Aircraft cooling device according to claim 19, characterized by
an additional heat exchanger, which is cooled case-by-case by an
additional cooling system, wherein the additional heat exchanger is
adapted such that the coolant of the coolant circuit is cooled in
the additional heat exchanger if the additional heat exchanger is
cooled by the additional cooling system.
22. Aircraft cooling device according to claim 19, characterized in
that the at least one aircraft outer-shell heat-exchanger bypass
valve is adapted to bypass the coolant past the aircraft
outer-shell heat exchanger, at least partially, if the temperature
in the aircraft outer-shell heat exchanger and/or the temperature
of the coolant falls below a second threshold value.
23. Aircraft cooling device according to claim 19, characterized by
a pump-device bypass valve, which is adapted to bypass the coolant
past the pump device in the case of a malfunction of the pump
device.
24. Aircraft cooling device according to claim 19, characterized in
that the coolant is adapted such that, in the case of a
malfunction, it evaporates in the cooling heat exchanger at a
temperature above the dew point of the air surrounding the
electronic device.
25. Aircraft cooling device according to claim 19, characterized in
that the aircraft cooling device is adapted such that, because of
the evaporating of the coolant in the cooling heat exchanger, a
temperature below the breakdown temperature of the electronic
device prevails within the electronic device in the case of a
malfunction.
26. Redundant aircraft electronics cooling system, characterized by
a plurality of aircraft cooling devices according to claim 19,
wherein the plurality of aircraft cooling devices is adapted to
cool the same electronic device.
Description
[0001] The invention relates to the cooling of an electronic device
in an aircraft by means of a coolant that, during normal operation,
is in the single-phase, liquid phase and, in the case of a
malfunction, can have both the gaseous and the liquid phase.
[0002] In the case of an aircraft of the prior art, an electronic
device is cooled by means of air. If the aircraft is on the ground,
air is taken from the cabin for the purpose of cooling the
electronic device, and returned to the cabin. This requires fans,
which cause a considerable noise load. Further, the waste heat
drawn into the cabin results in unwanted heating of the cabin.
[0003] In the case of a cooling device of the prior art, air
circulates between the electronic device and an aircraft
outer-shell heat exchanger during the flight. Since air can take up
only relatively small quantities of heat, large quantities of air,
large heat-exchanger surfaces, and air ducts of large cross-section
are required. The weight and the space requirement of the cooling
device and electronic device are increased as a result. This
results in problems during installation in an aircraft. Both the
supplying of air to the electronic device and the removal of air
from the electronic device require a respective fan. The fans have
a comparatively high electric power consumption, this resulting in
an increased kerosene consumption on the ground and during the
flight. Further, the fans cause vibrations and noise. In the case
of a breakdown of one of the fans, the electronic device has to be
switched off, since there is a risk of malfunction in the case of
an excessively high operating temperature. Since certain functions
are no longer available when the electronic device has been
switched off, the safety of the aircraft can be impaired.
[0004] JP 2001-010595 proposes the cooling of an electronic device
through the use of three cascaded cooling circuits. In the first
cooling circuit, coolant circulates through an aircraft outer-shell
heat exchanger and a condenser of a second cooling circuit. The
second cooling circuit generates cold by compressing, condensing
and evaporating. The evaporator of the second cooling circuits
cools a heat exchanger of a third cooling circuit, which cools the
electronic device. All three cooling circuits have a forced
convection, by means of a respective pump device. In the case of a
failure of one of the three pump devices that ensure the forced
convection, the electronic device can no longer be operated, and
the safety of the aircraft is impaired.
[0005] It is an object of the invention to provide a more reliable
cooling of an electronic device in an aircraft.
[0006] In the case of a method, according to the invention, for
cooling an electronic device in an aircraft, coolant circulates in
a coolant circuit. The electronic device is cooled by means of the
coolant and, in an aircraft outer-shell heat exchanger, the heat
taken up by the coolant is emitted to the environment. The coolant
can evaporate, at least partially, during the cooling of the
electronic device and condense in the aircraft outer-shell heat
exchanger. The coolant circulates in the coolant circuit by natural
convection. The invention has the advantage that no pump device is
required to ensure forced convection. This increases the
reliability and safety of the aircraft. Further, the mass of the
aircraft is reduced, which reduces the kerosene consumption.
Further, there is no need for a refrigerating machine or
ventilators, or for air shafts of large cross-section. As a result,
the mass and the space requirement of a cooling device for the
electronic device is reduced, and the integration into an aircraft
is simplified.
[0007] During normal operation, the coolant can be permanently in a
liquid phase, and circulate in the coolant circuit by forced
convection. In the case of a malfunction, the coolant evaporates,
at least partially, during the cooling of the electronic device,
and condenses in the aircraft outer-shell heat exchanger, as
previously described. In the case of a malfunction, the coolant
circulates in the coolant circuit by natural convection. The
malfunction can be, for example, the failure of a pump device for
ensuring the forced convection.
[0008] The malfunction can also be an increased demand for cooling
capacity. In this case, a forced convection can also be provided in
addition.
[0009] This embodiment has the advantage that the cooling capacity,
and therefore the temperature of the electronic device, can be
controlled by controlling the forced convection. For example, the
forced convection can be controlled in such a way that the air
surrounding the electronic device is permanently at a temperature
above the dew point, and the temperature of the electronic device
is below a failure temperature. Even in the case of a breakdown of
the forced convection, the cooling of the electronic device can be
ensured. Consequently, in the case of a breakdown of the forced
convection, the electronic device can continue to be operated, as a
result of which the safety of the aircraft is increased.
[0010] During normal operation, the coolant is in the single-phase,
liquid phase. In the case of a malfunction, the coolant has a
two-phase behaviour. The coolant can acquire both the liquid and
the gaseous phase in the case of a malfunction.
[0011] The coolant can be bypassed past the aircraft outer-shell
heat exchanger, at least partially, if the temperature in the
aircraft outer-shell heat exchanger exceeds a first threshold
value. The coolant can be cooled case-by-case in an additional heat
exchanger, which is cooled by a further cooling system. This can be
necessary if the aircraft is on the ground and/or the external
temperature is relatively high. In this case, the aircraft
outer-shell heat exchanger is unable to cool the coolant. The
further cooling system can be a liquid cooling system, or a cooling
system that cools by compressing, condensing and evaporating. The
first threshold value can be selected in such a way that the
coolant, upon entering the electronic device, has a temperature by
which it can be ensured that the temperature of the electronic
device is safely below the breakdown temperature. The first
threshold value can also correspond to the actual temperature of
the coolant emerging from the cooling heat exchanger. If the
temperature of the aircraft outer-shell heat exchanger is lower
than the actual temperature of the coolant emerging from the
cooling heat exchanger, the coolant flows through the aircraft
outer-shell heat exchanger and is at least partially cooled. If the
temperature of the aircraft outer-shell heat exchanger is higher
than the actual temperature of the coolant emerging from the
cooling heat exchanger, the coolant does not flow through the
aircraft outer-shell heat exchanger, and therefore cannot become
heated in the aircraft outer-shell heat exchanger.
[0012] The coolant can be bypassed past the aircraft outer-shell
heat exchanger, at least partially, if the temperature in the
aircraft outer-shell heat exchanger and/or of the coolant falls
below a corresponding second threshold value in each case. If the
aircraft is at great altitude, the external temperature can acquire
very low values. Owing to the coolant being bypassed past the
aircraft outer-shell heat exchanger, at least partially, it can be
ensured that the temperature of the air surrounding the electronic
device is always above the dew point. As a result, condensation of
water in and/or on the electronic device is prevented, which
increases the reliability and service life of the electronic
device. Consequently, the second threshold value can be selected
such that the temperature of the air surrounding the electronic
device is always above the dew point.
[0013] The invention also relates to an aircraft cooling device,
comprising a cooling heat exchanger adapted to cool an electronic
device by means of a coolant, and an aircraft outer-shell heat
exchanger adapted to cool the coolant, wherein the cooling heat
exchanger and the aircraft outer-shell heat exchanger are arranged
in a closed coolant circuit. The coolant can evaporate, at least
partially, in the cooling heat exchanger during the cooling of the
electronic device and condense in the aircraft outer-shell heat
exchanger. The coolant circulates in the coolant circuit by natural
convection. The coolant Galden, for example, which is a
perfluorinated polyether distributed by Solvay Solexis, can be used
as a coolant. Further, propylene glycol solutions, also referred to
by the abbreviation PGW, can also be used as a coolant. This
cooling device operates by natural convection and consequently does
not require a pump device, so resulting in a compact and fail-safe
aircraft cooling device. To ensure the natural convection, the line
between the cooling heat exchanger and the aircraft outer-shell
heat exchanger can be dimensioned with a larger diameter. The
coolant functions as a two-phase coolant, since it can exist in
both the gaseous and the liquid state.
[0014] The aircraft cooling device can have a pump device, which,
during normal operation, circulates coolant in the coolant circuit.
The aircraft cooling device can be adapted such that, during normal
operation, the liquid coolant is permanently in a liquid phase and,
because of the pump, circulates in the coolant circuit by forced
convection. In the case of a malfunction, the coolant evaporates,
at least partially, in the cooling heat exchanger during the
cooling of the electronic device and condenses in the aircraft
outer-shell heat exchanger. In the case of a malfunction, the
coolant circulates in the coolant circuit by natural convection. As
mentioned previously, in the case of this embodiment it is
particularly easy to ensure that the temperature of the air
surrounding the electronic device is permanently above the dew
point, as a result of which the reliability and service life of the
electronic device, and thereby the safety and reliability of the
aircraft, are increased.
[0015] The aircraft cooling device can further have an aircraft
outer-shell heat-exchanger bypass valve, which is adapted to bypass
the coolant past the aircraft outer-shell heat exchanger, at least
partially, if the temperature in the aircraft outer-shell heat
exchanger exceeds a first threshold value. The aircraft cooling
device can have an additional heat exchanger, which is cooled
case-by-case by an additional cooling system, the additional heat
exchanger being adapted such that the coolant of the coolant
circuit is cooled in the additional heat exchanger if the
additional heat exchanger is cooled by the additional cooling
system. As mentioned previously, the external temperature can have
high values, for example, if the aircraft is on the ground. In this
case, the aircraft outer-shell heat exchanger might possibly no
longer cool the coolant to such an extent that the temperature of
the electronic device is always below the breakdown temperature. In
this case, the coolant is cooled partially or completely by an
additional heat exchanger, which is cooled by the additional
cooling system. The additional cooling system can be a liquid
cooling system, for example a so-called cold bus, or have a cycle
of compression, condensing and evaporation. The first threshold
value can be selected such that it is ensured that the coolant,
upon entering the cooling heat exchanger, has a temperature by
which it can be ensured that the temperature of the electronic
device is always below the breakdown temperature. The aircraft
outer-shell heat-exchanger bypass valve can also be opened if the
temperature of the aircraft outer-shell heat exchanger is higher
than the actual temperature of the coolant emerging from the
cooling heat exchanger.
[0016] The aircraft outer-shell heat-exchanger bypass valve can be
realized to bypass the coolant past the aircraft outer-shell heat
exchanger, at least partially, if the temperature in the aircraft
outer-shell heat exchanger and/or of the coolant falls below a
corresponding second threshold value in each case. It can thereby
be ensured that the temperature of the air surrounding the
electronic device is always above the dew point, so increasing the
reliability and service life of the electronic device, and thereby
the safety of the aircraft. Consequently, the second threshold
value can be selected such that the air surrounding the electronic
device has a temperature that is above the dew point. It is
understood that, instead of an aircraft outer-shell heat-exchanger
bypass valve having two threshold values, it is possible to provide
two aircraft outer-shell heat-exchanger bypass valves, each of
which responds to one threshold value.
[0017] The aircraft cooling device can have a pump-device bypass
valve, which is adapted to bypass the coolant past the pump device
in the case of a malfunction of the pump device. The pump-device
bypass valve can be connected parallel to the pump device. The
pump-device bypass valve can have a spring, which opens the valve
in the case of a preset pressure difference.
[0018] The coolant can be adapted such that, in the case of a
malfunction, it evaporates in the cooling heat exchanger at a
temperature above the dew point of the air surrounding the
electronic device. The aircraft cooling device can be adapted such
that, in the case of a malfunction, the electronic device, because
of the evaporating of the coolant in the cooling heat exchanger,
has a temperature below the breakdown temperature of the electronic
device.
[0019] The pump device can be arranged, in the direction of flow of
the coolant, after the aircraft outer-shell heat exchanger and
before the additional heat exchanger. The cooling heat exchanger is
located after the additional heat exchanger in the direction of
flow of the coolant. There can be a reservoir for equalizing a
thermal expansion of the coolant and/or for replenishing coolant in
the case of a leakage.
[0020] The invention also relates to a redundant aircraft
electronics cooling system having a plurality of the previously
described aircraft cooling devices, wherein the plurality of
aircraft cooling devices are adapted to cool the same electronic
device. As a result, a particularly fail-safe cooling of the
electronic device is achieved, such that the safety of the aircraft
is further increased.
[0021] The invention is now explained with reference to the
appended FIGURE, which is a schematic representation of an aircraft
cooling device according to the invention.
[0022] An aircraft 11 has an electronic device 2. The electronic
device 2 can be located, for example, together with a plurality of
electronic devices 2 in a switchgear cabinet (not shown). The
electronic device 2 is thermally coupled to a cooling heat
exchanger 3. This thermal coupling can be effected by means of a
gas, a liquid or a mechanical connection. The cooling heat
exchanger 3 is connected to a supply line 10, which supplies liquid
coolant to the cooling heat exchanger 3. The supplied coolant cools
the electronic device 2 as a result of the previously described
thermal coupling. During normal operation, the coolant enters the
output line 1 as a liquid coolant, and is supplied as a liquid
coolant to the aircraft outer-shell heat exchanger 7. There the
coolant undergoes cooling, in that heat is removed from it and
output to the environment of the aircraft. The coolant emerging
from the aircraft outer-shell heat exchanger 7 enters a pump device
4, which supplies the coolant back to the cooling heat exchanger 3
via an additional heat exchanger 7 and the supply line 10. The
coolant therefore passes through a closed circuit.
[0023] During normal operation, i.e. if the pump device 4 is
functional, the coolant is permanently in a closed circulation
loop. The temperature of the coolant upon entering the cooling heat
exchanger, and therefore the temperature of the electronic device,
can be set particularly easily by setting the pump power. The
temperature of the electronic device 2 is preferably to have such a
value that the temperature of the air surrounding the electronic
device 2 is always above the dew point. Further, the temperature of
the electronic device 2 must be lower than the breakdown
temperature.
[0024] As mentioned previously, there is an additional heat
exchanger 6 in the cooling circuit. If the aircraft 11 is on the
ground, the external temperature can be so high that the aircraft
outer-shell heat exchanger 7 cannot remove any heat, or cannot
remove sufficient heat, from the coolant. In this case, the coolant
is cooled partially or completely in the additional heat exchanger
6, and it cannot, at least partially, flow through the aircraft
outer-shell heat exchanger 7. The additional heat exchanger 6 can
be cooled by means of a liquid cooling system, for example a
so-called cold bus, or by means of a cooling system having a cycle
of compression, condensing and evaporation. An additional coolant
supply 12 is effected if the temperature of the external air and/or
the temperature of the coolant after emergence from the aircraft
outer-shell heat exchanger 7 is above a threshold value.
Consequently, cooling of the electronic device 2 can also be
ensured on the ground. In the case of a low external temperature,
for example during flight, the cooling of the coolant is effected
in the aircraft outer-shell heat exchanger 7. In this case, the
additional coolant supply 12 to the additional heat exchanger can
be omitted. It is also possible to provide a bypass valve (not
shown) parallel to the additional heat exchanger 6, which bypass
valve is opened if the temperature of the external air and/or the
temperature of the coolant after emergence from the aircraft
outer-shell heat exchanger 7 is below a threshold value that
ensures that the coolant circulating in the cooling circuit effects
sufficient cooling of the electronic device 2. The coolant can flow
through both the aircraft outer-shell heat exchanger 7 and the
additional heat exchanger 6 if the aircraft outer-shell heat
exchanger 7 is unable to cool the coolant to a predefined setpoint
value.
[0025] Further, the cooling circuit includes a reservoir 9 for
equalizing a change in volume of the coolant and/or for
replenishing coolant in the case of a leakage. In the embodiment
represented, the reservoir 9 is located after the aircraft
outer-shell heat exchanger 7 and before the additional heat
exchanger 6, in the direction of flow of the coolant. However, the
reservoir 9 can also be located after the aircraft outer-shell heat
exchanger 6 and before the cooling heat exchanger 3, in the
direction of flow of the coolant.
[0026] In the embodiment represented, the pump device 4 is located
between the aircraft outer-shell heat exchanger 7 and the
additional heat exchanger 6, in the direction of flow of the
coolant. The pump device can also be located between the additional
heat exchanger 6 and the cooling heat exchanger 3. At least one
aircraft outer-shell heat-exchanger bypass valve 8 is connected
parallel to the aircraft outer-shell heat exchanger 7. The aircraft
outer-shell heat-exchanger bypass valve 8 opens if the external
temperature is so high that the coolant can no longer by cooled by
the aircraft outer-shell heat exchanger 7. This prevents the
coolant from being heated by the aircraft outer-shell heat
exchanger 7. Heating of the coolant in the aircraft outer-shell
heat exchanger 7 is undesirable, because in this case the
additional heat exchanger 6 has to discharge more heat to the
additional cooling system, so increasing the kerosene
consumption.
[0027] The aircraft outer-shell heat-exchanger bypass valve 8 can
be opened if the external temperature value falls below a value
that results in the coolant being cooled to such an extent that the
air surrounding the electronic device 2 is below the dew point. In
this case, one portion of the coolant flows through the aircraft
outer-shell heat exchanger 7 and another portion flows through the
aircraft outer-shell heat-exchanger bypass valve 8. Through control
of the opening or through modulation of the aircraft outer-shell
heat-exchanger bypass valve 8, it is possible to control the
temperature of the coolant supplied to the cooling heat exchanger
3, which is thermally coupled to the electronic device 2.
[0028] In the embodiment represented, the aircraft outer-shell
heat-exchanger bypass valve 8 can open completely upon a first
threshold value being exceeded, for example if the external
temperature is too high, and open at least partially or be
modulated upon a falling below a second threshold value, for
example if the external temperature is too low. It is also
possible, however, to provide two aircraft outer-shell
heat-exchanger bypass valves, which each respond to a threshold
value. Such a design is considered as equivalent.
[0029] As mentioned previously, during normal operation, for
example if the pump device 4 is functional, the coolant is
permanently in the liquid phase. The pump device 4 operates only as
a pump for liquid coolant. The pump device 4 does not operate as a
compressor, and during normal operation, for example if the pump
device 4 is functional and there is sufficient cooling power,
condensing and evaporating does not occur.
[0030] In the case of a breakdown of the pump device 4, the
temperature of the coolant in the cooling heat exchanger 3 rises.
As a result, the coolant in the cooling heat exchanger can
evaporate. The evaporating process produces, on the one hand, a
positive pressure in the direction of the aircraft outer-shell heat
exchanger 7 and the pump device 4 and, on the other hand, a
negative pressure in the direction of the supply line 10 and the
additional heat exchanger 6. As a result, a pressure difference
emerges at the pump device 4. This pressure difference causes a
pump-device by-pass valve 5 to be opened. The pump-device bypass
valve 5 preferably has only mechanical components, so increasing
its reliability. Preferably, the release pressure of the
pump-device bypass valve can be set through a spring.
[0031] This embodiment, in the case of a functional pump device,
also enables coolant to flow through the pump-device bypass valve 8
and past the pump device 7 if coolant evaporates in the cooling
heat exchanger 3, for example because of an increased cooling load.
In this operating case, also, the at least one aircraft outer-shell
heat-exchanger bypass valve 8 can operate as described
previously.
[0032] In the case of a failed pump device 4, the coolant 3
evaporates in the cooling heat exchanger and condenses in the
aircraft outer-shell heat exchanger 7. For this purpose, it is
expedient for the output line 1 to be dimensioned with a larger
cross-section, in order that sufficient gaseous coolant can be
conveyed from the cooling heat exchanger 3 to the aircraft
outer-shell heat exchanger 7.
[0033] In the case of breakdown of the pump device 4, the coolant
circulates through the cooling circuit by natural convection. As a
result, cooling of the electronic device during flight can be
ensured, such that the latter can continue to be operated, so
increasing the reliability and safety of the aircraft.
[0034] It is possible to provide two or more aircraft cooling
devices, of substantially identical construction, which cool the
same electronic device. An additional redundancy is thereby
created, which further increases the reliability and safety of the
aircraft.
[0035] The aircraft cooling device according to the invention has
the advantage that use of a liquid coolant reduces the required
installation space. Further, there is no need for a refrigerating
machine, as in the prior art. In contrast to a cooling system
having a gaseous coolant, the aircraft cooling device according to
the invention does not require fans and air ducts of large
cross-section. Consequently, the mass of the cooling system and the
electric power consumption can be reduced, which simplifies
installation in an aircraft and reduces the kerosene requirement.
Further, the liquid coolant has the advantage that the temperature
differences in the electronic device are reduced in comparison with
a conventional gaseous coolant.
[0036] It is understood that a plurality of aircraft outer-shell
heat-exchanger bypass valves 7, which respond to the same
temperature threshold value, can be provided in order to increase
the reliability of the cooling system. It is also possible to
provide a plurality of pump-device bypass valves 5, such that the
reliability of the aircraft cooling device is increased. It is also
possible for each previously described component to be designed in
a redundant manner, e.g. through parallel connection of two
substantially identical components.
* * * * *