U.S. patent application number 16/439085 was filed with the patent office on 2019-12-19 for cooling system with two heat exchangers and vehicle with a cooling system.
The applicant listed for this patent is Airbus Defence and Space GmbH. Invention is credited to Robert SCHOELL.
Application Number | 20190383568 16/439085 |
Document ID | / |
Family ID | 66776100 |
Filed Date | 2019-12-19 |
United States Patent
Application |
20190383568 |
Kind Code |
A1 |
SCHOELL; Robert |
December 19, 2019 |
COOLING SYSTEM WITH TWO HEAT EXCHANGERS AND VEHICLE WITH A COOLING
SYSTEM
Abstract
A cooling system with icing protection for a coolant flowing
therein comprises a first heat exchanger to withdraw coolant
thermal energy. The first heat exchanger uses a first fluid flow as
a heat sink. A second heat exchanger withdraws thermal energy from
the coolant using a second fluid flow, differing from the first
fluid flow, as a heat sink. A conveyor device supplies the coolant
to the first and second heat exchangers. The cooling system
comprises a valve to regulate a volumetric flow of the coolant
supplied to the second heat exchanger, a temperature sensor
configured to measure a temperature of the coolant downstream of
the first and/or second heat exchanger, and a control unit to
control a delivery rate of the conveyor device and/or the
volumetric flow such that the temperature measured by the
temperature sensor does not fall below a predetermined coolant
viscosity.
Inventors: |
SCHOELL; Robert; (Hamburg,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Airbus Defence and Space GmbH |
Taufkirchen |
|
DE |
|
|
Family ID: |
66776100 |
Appl. No.: |
16/439085 |
Filed: |
June 12, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
Y02T 50/50 20130101;
F28F 27/00 20130101; F28F 19/006 20130101; B64D 2013/0674 20130101;
B64D 13/06 20130101 |
International
Class: |
F28F 19/00 20060101
F28F019/00; F28F 27/00 20060101 F28F027/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 15, 2018 |
DE |
10 2018 114 353.2 |
Claims
1. A cooling system with icing protection for a coolant flowing in
the cooling system, comprising: a first heat exchanger configured
to withdraw thermal energy from the coolant, wherein the first heat
exchanger uses a first fluid flow as a heat sink; a second heat
exchanger configured to withdraw thermal energy from the coolant,
wherein the second heat exchanger uses a second fluid flow, which
differs from the first fluid flow, as a heat sink; a conveyor
device, configured to supply the coolant to the first heat
exchanger and to the second heat exchanger, a valve configured to
regulate a volumetric flow of the coolant supplied to the second
heat exchanger; at least one temperature sensor configured to
measure a temperature of the coolant downstream of at least one of
the first heat exchanger or of the second heat exchanger; and a
controller configured to control at least one of a delivery rate of
the conveyor device or the volumetric flow regulated by the valve
in such a manner that the temperature measured by the temperature
sensor does not fall below a threshold value which corresponds to a
predetermined viscosity of the coolant.
2. The cooling system according to claim 1, furthermore comprising:
a first coolant line configured to conduct coolant heated by a heat
source to the first heat exchanger; and a second coolant line which
branches off from the first coolant line and is configured to at
least partially conduct the coolant heated by the heat source to
the second heat exchanger, wherein the valve is arranged in the
second coolant line and is configured to regulate the volumetric
flow of the coolant flowing through the second coolant line.
3. The cooling system according to claim 1, furthermore comprising:
a first coolant line configured to conduct coolant heated by a heat
source to the first heat exchanger; a third coolant line configured
to conduct coolant cooled by the first heat exchanger to the second
heat exchanger; and a fourth coolant line, which branches off from
the third coolant line and is configured to guide coolant past the
second heat exchanger, wherein the valve is arranged in the fourth
coolant line and is configured to regulate the volumetric flow of
the coolant flowing through the fourth coolant line such that the
volumetric flow of the coolant supplied to the second heat
exchanger is regulated.
4. The cooling system according to claim 2, wherein the at least
one temperature sensor comprises: a temperature sensor configured
to measure a temperature of the coolant directly upstream of the
conveyor device; a temperature sensor configured to measure a
temperature of the coolant directly downstream of the first heat
exchanger; a temperature sensor configured to measure a temperature
of the coolant directly downstream of the second heat exchanger; a
temperature sensor configured to measure a temperature of the
coolant directly upstream of the heat source; a temperature sensor
configured to measure a temperature of the coolant directly
downstream of the heat source; a temperature sensor configured to
measure a temperature of the first fluid flow directly upstream of
the first heat exchanger; and a temperature sensor configured to
measure a temperature of the second fluid flow directly upstream of
the second heat exchanger, wherein the controller is configured to
receive corresponding signals from each of the temperature sensors,
said signals representing the temperature measured by the
respective temperature sensor.
5. The cooling system according to claim 1, furthermore comprising:
a fluid line configured to branch off at least part of the first
fluid flow downstream of the first heat exchanger and to supply
same to the second fluid flow upstream of the second heat
exchanger; and a control apparatus configured to regulate a
volumetric flow of the first fluid flow branched off through the
fluid line.
6. A cooling system according to claim 1, wherein at least one of
the first heat exchanger or the second heat exchanger is a matrix
heat exchanger.
7. A cooling system according to claim 1, wherein at least one of
the first heat exchanger or the second heat exchanger is a skin
heat exchanger.
8. A cooling system according to claim 1, wherein at least one of
the first heat exchanger or the second heat exchanger is a
combination of a matrix heat exchanger and a skin heat
exchanger.
9. A vehicle with a cooling system according to claim 1.
10. The vehicle according to claim 9, wherein a heat source cooled
by the cooling system is a passenger cabin.
11. The vehicle according to claim 9, wherein a heat source cooled
by the cooling system is a cargo hold.
12. The vehicle according to claim 9, wherein a heat source cooled
by the cooling system is a cockpit.
13. The vehicle according to claim 9, wherein a heat source cooled
by the cooling system is an avionics component.
14. The vehicle according to claim 9, wherein a heat source cooled
by the cooling system is a hydraulic component.
15. The vehicle according to claim 9, wherein a heat source cooled
by the cooling system is an electronic component.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims the benefit of the German patent
application No. 10 2018 114 353.2 filed on Jun. 15, 2018, the
entire disclosures of which are incorporated herein by way of
reference.
FIELD OF THE INVENTION
[0002] The invention relates to a cooling system with two heat
exchangers and to a vehicle with such a cooling system. In
particular, the invention relates to a cooling system with a
control device which makes it possible to supply a volumetric flow
of a coolant in the cooling system to the second heat exchanger in
such a manner that the coolant downstream of the first and/or
second heat exchanger does not fall below a temperature which
corresponds to a predetermined viscosity of the coolant.
BACKGROUND OF THE INVENTION
[0003] In vehicles, such as, for example, aircraft, buses, trains,
ships, etc., many heat sources are installed, with passengers or
freight also being able to generate and/or output heat. For the
cooling of the heat sources, use is generally made of a cooling
system which comprises a coolant which absorbs heat from the heat
sources and outputs same to a heat sink. Ambient air which is
thermally coupled to the coolant by means of heat exchangers is
generally used as the heat sink.
[0004] The cooling system firstly has to be configured to be able
to output the maximum waste heat from the heat source(s) to the
heat sink depending on the temperature of the ambient air and waste
heat generated by the heat source(s), and secondly has to be
configured to prevent the coolant from being too severely cooled.
For example, with little waste heat and/or at very low temperatures
of ambient air, the viscosity of the coolant may greatly increase
after cooling in the heat exchanger. However, this impairs the
possibility of conveying the coolant by means of a conveyor device
or may even damage the conveyor device.
[0005] Conventional cooling systems, therefore, provide a bypass
line through which heated coolant can be conducted past the heat
exchanger and can be mixed there with the cooled coolant. As a
result, the viscosity of the coolant upstream of the conveyor
device can be improved. Alternatively, a shut-off apparatus, for
example a flap, can also be provided which limits an air flow of
the ambient air to the heat exchanger such that the cooling power
of the heat exchanger is reduced.
SUMMARY OF THE INVENTION
[0006] The invention is based on an object of providing an improved
cooling system which is capable of using simple means to avoid
overcooling of the coolant. Furthermore, the invention is based on
an object of providing a vehicle with such a cooling system.
[0007] According to a first aspect, a cooling system with icing
protection for a coolant flowing in the cooling system comprises a
first heat exchanger which is configured to withdraw thermal energy
from the coolant, wherein the first heat exchanger uses a first
fluid flow as a heat sink, and a second heat exchanger which is
configured to withdraw thermal energy from the coolant, wherein the
second heat exchanger uses a second fluid flow, which differs from
the first fluid flow, as a heat sink. The first and second fluid
flow can involve the same fluid or a different fluid. For example,
both the first heat exchanger and the second heat exchanger can use
air as a heat sink, wherein the air flows flow parallel to one
another. In other words, the first and second heat exchangers are
arranged parallel to each other with regard to the fluid flow/flows
used as a heat sink.
[0008] In another configuration, one of the two fluid flows can be
an air flow while the other is formed from water or from another
liquid, or the two fluid flows comprises a liquid.
[0009] The cooling system can furthermore comprise a conveyor
device, which is configured to supply the coolant to the first heat
exchanger and to the second heat exchanger. For example, the
conveyor device can be provided in the form of a pump for conveying
a liquid or gaseous coolant. Of course, the conveyor device can
also be provided in the form of a compressor which supplies gaseous
coolant to the first and second heat exchangers.
[0010] Furthermore, the cooling system comprises a valve which is
configured to regulate a volumetric flow of the coolant which is
supplied to the second heat exchanger. For example, the valve can
(infinitely variably) change a cross section of a valve portion,
through which the coolant flows, in such a manner that the valve
completely closes or completely opens the cross section or, in an
intermediate position, leaves part of the cross section open for
the throughflow with coolant.
[0011] The cooling system furthermore contains at least one
temperature sensor which is configured to measure a temperature of
the coolant downstream of the first heat exchanger and/or of the
second heat exchanger, and a control unit which is configured to
control a delivery rate of the conveyor device and/or the
volumetric flow regulated by the valve in such a manner that the
temperature measured by the temperature sensor does not fall below
a threshold value which corresponds to a predetermined viscosity of
the coolant. In other words, the conveyor device and the valve are
regulated by the control unit in such a manner that the coolant
downstream of the two heat exchangers always has a certain
temperature, and therefore the viscosity of the coolant has an
upwards limit. As the temperature rises, the viscosity of the
coolant decreases, and therefore the coolant downstream of the two
heat exchangers and therefore upstream of the conveyor device is
likewise present with the viscosity having an upwards limit.
[0012] Use can be made, for example, of a water-based coolant. This
includes ethylene glycol water (EGW) in a mixture ratio of, for
example, 50/50, or propylene glycol water (PGW) in a mixture ratio
of 60/40. These coolants are distinguished by good heat transport
capacity with a conveying capability at low temperatures, and also
by high burst protection, i.e., the coolant does not expand further
even at lower temperatures and with possible freezing, and
therefore the coolant-containing devices are not damaged. The
temperature level at which the mixtures may lose their normal fluid
property and, in particular, can no longer be expediently conveyed
by centrifugal pumps is at approx. -32.degree. C. to -34.degree. C.
for EGW and approx. -43.degree. C. to -45.degree. C. for PGW, at
the mixture ratios specified.
[0013] Other heat carriers, such as silicone oils or certain
fluorinated hydrocarbons (tradenames Novec, Galden) are generally
capable of being conveyed even at lower temperatures although the
viscosity also greatly increases there. However, these are
significantly inferior in specific heat transport capability to the
water-based heat carriers and are also more expensive.
[0014] In conventional cooling systems, the arrangement of a bypass
line conducting the coolant past the generally single heat
exchanger can lead to the coolant being virtually completely guided
through the bypass line when little cooling is required and/or at
very low temperatures of the heat sink. Coolant remaining in the
heat exchanger, however, may be overcooled here, i.e., the coolant
is cooled to such an extent that the viscosity of the coolant
increases such that the coolant can no longer be conveyed in the
cooling system, or leads to such high pressure losses in the heat
exchanger that the flow rate is greatly impaired. For example, the
coolant can freeze in the heat exchanger or can crystalize or
freeze on the walls of the coolant-guiding lines in the heat
exchanger such that the cross section of the heat exchanger is
greatly restricted or is entirely closed. In this case (and, in
particular, at very low temperatures of the fluid forming the heat
sink), the cooling system can fail since no more cooling at all
takes place when a certain viscosity value is exceeded and when
icing occurs. As a consequence, the heat source will overheat.
De-icing (thawing) of the heat exchanger can be impossible because
of the bypass line since, although closing of the bypass line
increases the pressure of the coolant in the inlet region of the
heat exchanger, the latter is not necessarily de-iced if no
throughflow of coolant is possible.
[0015] In conventional cooling systems with a shut-off apparatus
(for example a flap) for the fluid which is supplied to the heat
exchanger and forms a heat sink, thawing of the heat exchanger when
icing of the heat exchanger has occurred is likewise not easily
possible. Even if the shut-off apparatus entirely stops the fluid
flow, the cross section which is already closed within the heat
exchanger for the coolant can be thawed (opened) only slowly. In
this time, the conveyor device of the cooling system can incur
damage and/or the cooling power provided for the heat source is
insufficient. In addition, the shut-off apparatus constitutes a
resistance in the fluid flow serving as a heat sink, the resistance
leading to a reduction in the energy efficiency of the overall
system (for example of a vehicle). If the fluid flow is generated,
for example, by the movement of the vehicle, for example ambient
air which is guided through a ram air duct, when the shut-off
apparatus is closed the flow at the input of the ram air duct
changes, as a result of which unfavorable flows may arise and
therefore the aerodynamics of the vehicle may be impaired.
[0016] By contrast, the cooling system described here affords the
advantage that the control unit prevents overcooling of the
coolant. Overcooling is understood here as meaning the exceeding of
a threshold value of the viscosity of the coolant, and also
freezing or crystallizing of at least part of the coolant within or
downstream of the heat exchanger. By controlling the delivery rate
of the conveyor device and/or of the volumetric flow of the coolant
being supplied to the second heat exchanger through the valve, a
predetermined quantity of coolant can always be guided through the
first heat exchanger while, when a higher cooling power is
required, coolant can also be guided through the second heat
exchanger and cooled. The first heat exchanger can therefore be
dimensioned in such a manner that overcooling of the coolant only
by the first heat exchanger is not possible. For example, the first
heat exchanger can be of smaller dimensions than in conventional
cooling systems, and therefore, when the fluid serving as a heat
sink is at customary temperatures which can be anticipated and in
the event of customary cooling powers which can be anticipated, the
heat exchanger cannot cool the coolant in such a manner that the
viscosity exceeds the threshold value. An increased cooling power
of the cooling system is made possible by opening the valve and/or
increasing the delivery rate through the conveyor device.
[0017] In a variant configuration, the cooling system can
furthermore comprise a first coolant line which is configured to
conduct coolant heated by a heat source to the first heat
exchanger, and a second coolant line which branches off from the
first coolant line and is configured to at least partially conduct
the coolant heated by the heat source to the second heat exchanger.
The valve is arranged in the second coolant line, in this case, and
is configured to regulate the volumetric flow of the coolant
flowing through the second coolant line. This arrangement permits
the use of a single valve (a valve with only an input and an
output) which is arranged within the second coolant line and
regulates the flow through the second coolant line.
[0018] Conventional cooling systems with a bypass line generally
have a three-way valve which regulates the respective volumetric
flow into the bypass line and to the heat exchanger. However, these
three-way valves are more expensive, more maintenance-intensive and
heavier. By contrast, in the cooling system described here, the
volumetric flow to the second heat exchanger is prevented by
closing the single valve in the second coolant line, and therefore
all of the coolant moved by the conveyor device is supplied to the
first heat exchanger.
[0019] In another variant configuration, the cooling system can
furthermore comprise a first coolant line which is configured to
conduct coolant heated by a heat source to the first heat
exchanger, a third coolant line which is configured to conduct
coolant cooled by the first heat exchanger to the second heat
exchanger, and a fourth coolant line, which branches off from the
third coolant line and is configured to guide coolant past the
second heat exchanger. Here, the valve is arranged in the fourth
coolant line and is configured to regulate the volumetric flow of
the coolant flowing through the fourth coolant line such that the
volumetric flow of the coolant supplied to the second heat
exchanger is regulated. Also here, a simple and cost-effective
valve which merely regulates the flow through the fourth coolant
line can be used. By closing of the valve, the flow through the
fourth coolant line is stopped, and therefore the coolant leaving
the first heat exchanger flows completely into the second heat
exchanger. By (partial) opening of the valve, at least some of the
coolant leaving the first heat exchanger is guided past the second
heat exchanger through the fourth coolant line. Since the second
heat exchanger provides a higher flow resistance for the coolant
than the fourth coolant line with the valve, when the valve is open
the coolant will predominantly (if not completely) flow through the
fourth coolant line.
[0020] In a further variant configuration, the at least one
temperature sensor can comprise at least one of the following
sensors: [0021] a (first) temperature sensor which is configured to
measure a temperature of the coolant directly upstream of the
conveyor device; [0022] a (second) temperature sensor which is
configured to measure a temperature of the coolant directly
downstream of the first heat exchanger; [0023] a (third)
temperature sensor which is configured to measure a temperature of
the coolant directly downstream of the second heat exchanger;
[0024] a (fourth) temperature sensor, which is configured to
measure a temperature of the coolant directly upstream of the heat
source; [0025] a (fifth) temperature sensor which is configured to
measure a temperature of the coolant directly downstream of the
heat source; [0026] a (sixth) temperature sensor which is
configured to measure a temperature of the first fluid flow
directly upstream of the first heat exchanger; and [0027] a
(seventh) temperature sensor which is configured to measure a
temperature of the second fluid flow directly upstream of the
second heat exchanger.
[0028] "Directly upstream" or "directly downstream" here means an
arrangement of the sensor in the direct vicinity of the respective
cooling system component. That is to say, a short section of a
coolant line or fluid line can be located between sensor and
component, or the sensor is arranged in the region of a connection
of the coolant line or fluid line to the component. The purpose of
this arrangement is to measure the temperature of the coolant or
fluid at the point where a significant temperature change no longer
takes place because of a further conduction by line as far as the
component.
[0029] Alternatively or additionally, each sensor can be replaced
or supplemented by a pressure sensor.
[0030] The control unit here can be configured to receive
corresponding signals from each of the temperature and/or pressure
sensors, the signals representing the temperature/pressure of the
coolant prevailing at the respective temperature and/or pressure
sensor. For example, the control unit can receive analogue and/or
digital signals from at least one of the sensors in order to
determine the temperature/pressure of the coolant and/or fluid
flow. Furthermore, from the signals of the sixth and seventh
temperature sensor measuring the temperature of a fluid flow, the
control unit can draw at least conclusions regarding a possible
temperature of the coolant after the latter has passed through the
associated heat exchanger. For example, from the customarily known
power parameters of the associated heat exchanger and the received
sensor signal, the control unit can determine the lowest possible
temperature of the coolant after the latter has passed through the
associated heat exchanger.
[0031] In a further variant configuration, the cooling system can
furthermore comprise a fluid flow line which is configured to
branch off at least part of the first fluid flow downstream of the
first heat exchanger and to supply same to the second fluid flow
upstream of the second heat exchanger. Alternatively or
additionally, the cooling system can also comprise a fluid flow
line which is configured to branch off at least some of the second
fluid flow downstream of the second heat exchanger and to supply
same to the first fluid flow upstream of the first heat exchanger.
The cooling system can optionally also comprise at least one
control apparatus which is configured to regulate a volumetric flow
of the fluid flow branched off, or of the two fluid flows branched
off, through the respective fluid flow line. In this variant
configuration, it is possible to provide a fluid flow having an
increased temperature to one of the two heat exchangers. For
example, a heat exchanger which is still frozen can thereby thaw
because of the heated fluid flow after the latter has passed
through the other heat exchanger. The control device can be
configured to regulate the control apparatus for controlling the
volumetric flow of the branched-off fluid flow in order to heat the
other fluid flow.
[0032] In a further refinement, the first and/or second heat
exchanger is designed in such a manner that the coolant enters on a
side of the respective heat exchanger on which the fluid flow
exits, and exits on a side of the respective heat exchanger on
which the fluid flow enters. The opposed passage by the coolant
flow and the fluid flow through the heat exchanger increases the
efficiency of the cooling system. The required fluid flow can
thereby be reduced, which also permits a reduction in the necessary
cross section for the fluid flow and the associated reduction in
vortexes on a skin of the vehicle.
[0033] In yet another refinement, the first heat exchanger and/or
the second heat exchanger can be a matrix heat exchanger, a skin
heat exchanger or a combination of a matrix heat exchanger and a
skin heat exchanger. A matrix heat exchanger permits a more compact
design since a larger surface between coolant flow and fluid flow
is made possible. By contrast, the skin heat exchanger does not
require any fluid inlet and fluid outlet in a skin of the vehicle,
as a result of which vortexes are reduced in comparison to a matrix
heat exchanger.
[0034] According to a further aspect, a vehicle comprises a cooling
system according to the first aspect or one of the associated
variant refinements.
[0035] Furthermore, the vehicle can comprise a heat source which is
cooled by the cooling system. The heat source can be, for example,
a passenger cabin, a freight hold, a cockpit, an avionics
component, a hydraulic component and/or an electronic
component.
[0036] The refinements, variants and aspects described here can
furthermore be combined as desired, and therefore further variant
refinements which are not explicitly described are included in the
present disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] Exemplary embodiments of the invention will be described in
more detail below with reference to the drawings.
[0038] FIG. 1 schematically shows a conventional cooling system
with a bypass line,
[0039] FIG. 2 schematically shows a conventional cooling system
with a shut-off apparatus in a cooling air line,
[0040] FIG. 3 schematically shows a cooling system according to the
present disclosure,
[0041] FIG. 4 schematically shows a variant of the cooling system
according to the present disclosure,
[0042] FIG. 5 schematically shows a fluid flow control for a
cooling system, and
[0043] FIG. 6 schematically shows a vehicle with a cooling
system.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0044] The present invention describes a cooling system with a
control device which makes it possible to supply a volumetric flow
of a coolant in the cooling system to a second heat exchanger in
such a manner that the coolant downstream of a first and/or the
second heat exchanger does not exceed a predetermined viscosity,
and also a vehicle with such a cooling system.
[0045] FIG. 1 schematically shows a conventional cooling system 300
with a heat exchanger 301 and a heat source 302. The heat exchanger
301 is thermally coupled to a heat sink, for example an air flow
303, in order to output thermal energy generated by the heat source
302. In the cooling system 300, coolant is moved in the flow
direction, illustrated by an arrow, by a conveyor device 304, and
therefore the coolant after absorbing thermal energy from the heat
source 302 is supplied by a coolant line 305 to the heat exchanger
301. In the event that the air flow 303 too greatly cools the
coolant in the heat exchanger 301, a bypass line 306 is provided
which conducts the coolant past the heat exchanger 301 and,
upstream of the conveyor device 304, brings the coolant together
with the cooled coolant from the heat exchanger 301. As a result,
the coolant flowing to the conveyor device 304 has a higher
temperature, and therefore, for example, a viscosity of the coolant
can be limited. The rate of the coolant flowing through the bypass
line 306 is controlled by a three-way valve 307. The valve 307
permits complete or partial deflection of the coolant from the line
305 into the bypass line 306 and/or the heat exchanger 301.
[0046] FIG. 2 schematically shows another conventional cooling
system 310 that generally corresponds to the cooling system 300
from FIG. 1. Instead of a bypass line 306 and associated three-way
valve 307 (FIG. 1), the coolant line 305 leads directly into the
heat exchanger 301. In order to prevent the coolant which leaves
the heat exchanger 301 from being too greatly cooled and therefore
having too high a viscosity, a cooling air line 311 through which
the air flow 303 flows and is supplied to the heat exchanger 301
can be equipped with a shut-off apparatus 312. The shut-off
apparatus 312, for example a flap, can limit the air flow 303 or
even stop same entirely, i.e., can completely close the cooling air
line 311. As a result, the amount of heat which can be absorbed by
the air flow 303 acting as a heat sink is limited, and therefore
the coolant after leaving the heat exchanger 301 does not fall
below a desired temperature.
[0047] FIG. 3 schematically shows an improved cooling system 10
which can transport away waste heat generated by a heat source 20.
For this purpose, the cooling system 10 has a first heat exchanger
101. The latter can withdraw thermal energy from a coolant flowing
through the cooling system, wherein the heat exchanger 101 uses a
first fluid flow 201 as a heat sink. The fluid flow 201 can be an
air flow or else a liquid which is capable of absorbing thermal
energy and optionally of transporting same away. The fluid flow 201
can thus be an air flow into a ram air duct, the air flow being
guided past or through the heat exchanger 101 by means of the
movement of a vehicle, or stationary air in a region of the vehicle
that outputs heat to the environment via the skin of the vehicle,
such as, for example, a stowage space. The liquid used can be a
coolant from a different cooling circuit or a stationary fluid,
such as, for example, a fresh water tank or a fuel tank.
[0048] A conveyor device 105 drives the coolant such that the
latter can continuously absorb thermal energy from the heat source
20 and can continuously output thermal energy to the fluid flow
201. The lines necessary for this purpose are illustrated in FIG.
3, but are not all explained in detail since they are conventional
coolant lines of a cooling system. The coolant lines form a
circuit, as is shown in FIG. 3.
[0049] In order to prevent overcooling of the coolant in the heat
exchanger 101, i.e., in order to prevent the cooling of the coolant
below a temperature in which the coolant has too high a viscosity,
a second heat exchanger 102 is provided in the cooling system 10.
The second heat exchanger 102 is configured to withdraw thermal
energy from the coolant and, for this purpose, uses a second fluid
flow 202 as a heat sink. The second fluid flow 202 differs from the
first fluid flow 201. The first heat exchanger 101 can therefore be
of smaller dimensions than in conventional systems since the second
heat exchanger 102 can be "switched to" if a greater cooling power
is required. It can thereby be ensured that coolant leaving the
first and second heat exchanger 102 is not overcooled. For example,
the first fluid flow 201 can be an air flow (for example in a ram
air duct) while the second fluid flow 202 is a liquid which acts as
a heat sink. The liquid here does not have to form any moving fluid
flow as such, but rather can be a liquid reservoir, such as, for
example, a fresh water tank.
[0050] Of course, the first and second fluid flow 201, 202 can also
have the same origin. For example, the first and second fluid flow
201, 202 can each be part of an air flow in a ram air duct, wherein
the ram air duct has only one inlet and one outlet.
[0051] In each case, the two heat exchangers 101, 102 are arranged
parallel to each other with respect to the fluid flows 201, 202 in
the cooling system 10 illustrated in FIG. 3.
[0052] In addition, the cooling system 10 illustrated in FIG. 3
also has a parallel arrangement of the heat exchangers 101, 102
with respect to the coolant flow. In other words, the conveyor
device 105 supplies the coolant both to the first heat exchanger
101 and to the second heat exchanger 102, wherein a valve 111 can
regulate a volumetric flow of the coolant which is supplied to the
second heat exchanger 102. In other words, the valve 111 regulates
the volumetric flow of the coolant which is cooled by the second
heat exchanger 102.
[0053] The valve 111 could indeed be designed as a three-way valve,
and therefore the valve 111 conducts a coolant flowing through a
coolant line 141 coming from the heat source 20 either to the first
heat exchanger 101 or to the second heat exchanger 102 or to the
two heat exchangers 101, 102. However, in the variant illustrated
in FIG. 3, a more cost-effective "normal" valve is arranged in a
coolant line 142 which branches off from the coolant line 141
coming from the heat source 20 and leads to the second heat
exchanger 102. By closing of the valve 111, the coolant is guided
exclusively through the first heat exchanger 101 and the second
heat exchanger 102 is "disconnected."
[0054] A control unit 130 is provided in the cooling system 10 in
order to control the conveyor device 105 and/or the valve 111. The
control unit 130 can thus send a signal to the conveyor device 105
in order to determine a delivery rate of the conveyor device 105,
i.e. a volumetric flow of the coolant moved by the conveyor device
105 in the cooling system 10. The valve 111 can be regulated by the
control unit 130 to the effect that a throughflow cross section of
the valve 111 is set, after which a volumetric flow of the coolant
through the second heat exchanger 102 is regulated. The control
unit 130 is configured to control the delivery rate of the conveyor
device 105 and/or the volumetric flow regulated by the valve 111 in
such a manner that a temperature of the coolant does not fall below
a threshold value which corresponds to a predetermined viscosity of
the coolant. It is thereby prevented that the coolant can be moved
only very poorly, if at all, by the conveyor device 105, and
therefore the conveyor device 105 is saved from damage.
[0055] The control unit 130 here can be configured in such a manner
that the coolant temperature downstream of the first heat exchanger
101 and/or of the second heat exchanger 102 or (directly) upstream
of the conveyor device 105 does not fall below the threshold value.
For this purpose, at least one temperature sensor 121 can be
arranged in the cooling system 10 and measures a temperature of the
coolant.
[0056] Alternatively or additionally, the control unit 130 can be
configured in such a manner that a coolant pressure downstream of
the first heat exchanger 101 and/or of the second heat exchanger
102 or (directly) upstream of the conveyor device 105 does not fall
below a threshold value. For this purpose, at least one pressure
sensor (not illustrated separately) can be arranged in the cooling
system 10 and measures a pressure of the coolant. The system
properties described below for temperature sensors apply equally to
pressure sensors.
[0057] The temperature sensor 121 can be arranged upstream of the
conveyor device 105. Of course, the one temperature sensor or an
additional temperature sensor 122 can be arranged (shortly or
directly) downstream of the first heat exchanger 101 and/or a
temperature sensor 123 can be arranged (shortly or directly)
downstream of the second heat exchanger 102 in the cooling system
10. Further temperature sensors 124 and 125 can be arranged
(shortly or directly) upstream of the heat source 20 and/or
(shortly or directly) downstream of the heat source 20 in the
cooling system 10.
[0058] Of course, the temperature of at least one of the fluid
flows 201, 202 can also be measured. For this purpose, temperature
sensors 126 and 127 can be provided in the cooling system 10, the
temperature sensors respectively measuring a temperature of the
first fluid flow 201 (shortly or directly) upstream of the first
heat exchanger 101 and a temperature of the second fluid flow 202
(shortly or directly) upstream of the second heat exchanger
102.
[0059] The control unit 130 can be connected to each of the sensors
in order to draw conclusions regarding the viscosity of the coolant
on the basis of the temperature and/or the pressure. On the basis
of the determined temperature and/or pressure, the control unit 130
can determine and regulate the delivery rate of the conveyor device
105 and/or the volumetric flow of the coolant which flows from the
valve 111 to the second heat exchanger 102. The control unit 130
can thereby prevent the viscosity of the coolant from exceeding a
critical value in which the cooling system no longer functions
correctly.
[0060] FIG. 4 schematically shows a variant of the cooling system
10 according to the present disclosure, wherein the coolant line
142 does not branch off from the coolant line 141. On the contrary,
the cooling system 10 comprises a third coolant line 143 in order
to conduct coolant cooled by the first heat exchanger 101 to the
second heat exchanger 102. The first and second heat exchanger 101,
102 are accordingly connected in series with respect to the coolant
flow. In order to control the coolant flow into the second heat
exchanger, a fourth coolant line 144 is provided in the cooling
system 10, the coolant line branching off from the third coolant
line 143 and guiding coolant past the second heat exchanger 102. In
this refinement, the valve 111 is arranged in the fourth coolant
line 144 in order to regulate the volumetric flow of the coolant
flowing through the fourth coolant line 144. This likewise permits
regulation of the volumetric flow of the coolant through the second
heat exchanger 102 by means of the control unit 130.
[0061] FIG. 5 schematically shows a fluid flow control system for a
cooling system 10, wherein only the first and second heat exchanger
101, 102 of the cooling system 10 are illustrated. The other
elements of the cooling system 10 can correspond to those of the
variants illustrated in FIGS. 3 and 4.
[0062] The fluid flow control system can provide a fluid line 203
through which at least some of the first fluid flow 201 is branched
off downstream of the first heat exchanger 101 and is supplied to
the second fluid flow 202 upstream of the second heat exchanger
102. For example, a fluid duct 204, in which the first heat
exchanger 101 is arranged and the first fluid flow 201 flows, can
have a branch downstream (with respect to the fluid flow 201) from
which the fluid line 203 extends. Similarly, a fluid duct 205 in
which the second heat exchanger 102 is arranged and the second
fluid flow 202 flows can have a branch or opening to which the
fluid line 203 extends. In other words, the fluid line 203 forms a
connection of the fluid ducts 204 and 205, wherein portions of the
fluid ducts 204 and 205 are connected to each other downstream or
upstream of the respective heat exchanger 101, 102.
[0063] Of course, the fluid line 203 can also be provided in the
reverse direction (not illustrated). In this case, a portion of the
fluid duct 205 of the second fluid flow 202 would be connected
downstream of the second heat exchanger 102 to a portion of the
fluid duct 204 of the first fluid flow 201 upstream of the first
heat exchanger 101 by the fluid line 203.
[0064] In both cases, the fluid line 203 can comprise a control
apparatus 210 which regulates a volumetric flow of the fluid flow
branched off through the fluid line 203. The control apparatus 210
can be a valve, a flap or another shut-off member which is capable
of closing or opening a cross section of the fluid flow line
203.
[0065] By means of the branched-off fluid flow, heated fluid can be
supplied to the heat exchanger 101, 102 connected downstream in
each case. This makes it possible to avoid overcooling of the
coolant in the cooling system 10 if the two fluid flows 201, 202
have too low a temperature, and therefore the viscosity of the
coolant cannot be kept under the desired critical value. It is also
possible to deice one of the heat exchangers 101, 102, for example
if the second heat exchanger 102 has not been used for a prolonged
period in the cooling system 10 and the coolant located in the heat
exchanger 102 has reached a very high viscosity or has frozen.
[0066] The control apparatus 210 can furthermore comprise a
conveyor device (not illustrated separately) in order to move the
fluid heated by a heat exchanger 101, 102 through the fluid flow
line 203 to the other heat exchanger 101, 102 upstream in the
direction of the respective fluid flow 201, 202.
[0067] FIG. 6 schematically shows a vehicle 11 with a cooling
system 10. Although the vehicle 11 is illustrated as an aircraft,
it can also be a bus, a train, a ship or another vehicle. A heat
source 20 which is cooled by the cooling system 10 is arranged in
the vehicle 11. The heat source 20 can be a passenger cabin, a
cargo hold, a cockpit, an avionics component, a hydraulic component
and/or an electronic component.
[0068] The first and/or second heat exchanger 101, 102 of the
cooling system 10 can be implemented as a matrix heat exchanger or
as a skin heat exchanger or in the form of a combination of a
matrix heat exchanger with a skin heat exchanger. The first and/or
second heat exchanger 101, 102 can thus form a skin heat exchanger
on a skin of the vehicle 11, as is illustrated in FIG. 6. Of
course, the first and/or second heat exchanger 101, 102 can also be
arranged in the interior of the vehicle 11 and can be implemented
in the form of a matrix heat exchanger. In both variants, the
coolant of the cooling system 10 is thermally coupled to a fluid
flow 201, 202 or to a static fluid. The fluid flows 201, 202 can be
ambient air which flows along a skin of the vehicle 11 and/or flows
through an inlet into a fluid duct 204, 205 into the interior of
the vehicle 11.
[0069] The variants, refinements and exemplary embodiments
discussed above serve merely for describing the claimed teaching,
but do not restrict the latter to the variants, refinements and
exemplary embodiments.
[0070] While at least one exemplary embodiment of the present
invention(s) is disclosed herein, it should be understood that
modifications, substitutions and alternatives may be apparent to
one of ordinary skill in the art and can be made without departing
from the scope of this disclosure. This disclosure is intended to
cover any adaptations or variations of the exemplary embodiment(s).
In addition, in this disclosure, the terms "comprise" or
"comprising" do not exclude other elements or steps, the terms "a"
or "one" do not exclude a plural number, and the term "or" means
either or both. Furthermore, characteristics or steps which have
been described may also be used in combination with other
characteristics or steps and in any order unless the disclosure or
context suggests otherwise. This disclosure hereby incorporates by
reference the complete disclosure of any patent or application from
which it claims benefit or priority.
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