Patent Application
20120175080
The technical field relates to a system for cooling at least one heat producing device in an aircraft and to a method for cooling at least one heat producing device. The technical field also relates to the use of a system for cooling at least one heat producing device in an aircraft and to an aircraft comprising at least one heat producing device and at least one system for cooling the heat producing device.
In larger aircraft of a modern design, increasingly a multitude of devices are integrated which during normal operation of the aircraft produce a considerable amount of heat which must safely and reliably be removed from the aircraft and dissipated, for example to the environment. For example, modern commercial aircraft comprise a multitude of different arithmetic units or other (power) electronics units, which are generally referred to as “avionics” and which are accommodated in an avionics compartment. In the state of the art, avionics compartments in aircraft are cooled by means of various systems. Systems are known in which a coolant by way of a coolant circuit absorbs heat from the avionics compartment and dissipates said heat to the environment by means of a skin-section heat exchanger. However, in this arrangement, the situation when the aircraft is located on the ground on hot days is important, because the temperature difference between the skin-section heat exchanger and the environment may be insufficient to carry out adequate heat dissipation.
Furthermore, it is known, at least in flight, to cool components in the avionics compartment by blowing in air from the aircraft cabin. Air from the so-called “triangular region” underneath the cabin floor and near the fuselage wall may be removed and, after absorbing heat from the avionics devices, leaves the avionics compartment in a heated state. However, this requires that the air conditioning system of the aircraft is already operative and, in particular, during stops on the ground on hot days, the cabin has been cooled down to a predetermined temperature level. Accordingly, it may be required, during operation of an aircraft on a hot day, to operate the air conditioning system before the avionics devices can be switched on.
Furthermore, it is known for outside air to be used in order to dissipate heat from the interior of an aircraft to its environment. To this effect, by way of a so-called ram air duct, air that flows past the aircraft in flight is guided into the interior of the aircraft, is fed by way of a heat exchanger that thermally communicates with the coolant to be cooled, and is discharged to the aircraft environment by way of an outlet opening. In this process, the air flowing through the ram air duct absorbs heat to be dissipated. This principle is, for example, already used in aircraft air conditioning systems in order to cool hot compressed air that is later to flow into the aircraft cabin. Furthermore, this principle is used in cooling systems, as described for example in DE 4340317. The air flowing through the ram air duct may, however, noticeably increase the aerodynamic resistance of the aircraft in flight. On the ground, the ram air can be conveyed through the ram air duct by means of a fan.
It may thus be considered at least one object to propose a cooling system for cooling heat producing devices in an aircraft, which cooling system independently of an ambient temperature and independently of an air conditioning system makes possible reliable cooling of the heat producing devices. Likewise, it may be considered at least one object to propose such a cooling system that is associated with as little complexity as possible, with the lowest possible energy requirement, the lightest possible weight, which cooling system in particular does not generate any additional aerodynamic resistance. In addition, other objects, desirable features, and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.
A system is provided for cooling at least one heat producing device in an aircraft, comprising at least one coolant circuit through which coolant flows in order to absorb heat from the heat producing device. The coolant circuit comprises a feed line arranged upstream of the heat producing device, and a return line arranged downstream of the heat producing device. The system is a heat dissipation device that thermally communicates with the return line of the coolant circuit provided for dissipating heat from the coolant circuit, in that a temperature spreading device reduces the temperature of the coolant in the feed line of the coolant circuit and increases a heat dissipation temperature of the heat dissipation device relative to the temperature of the coolant in the return line of the coolant circuit.
The type of heat dissipation device does not limit the invention. Instead, numerous types of heat dissipation devices are to be considered as being suitable, by means of which heat can be dissipated to an environment. The use of heat transfer devices suggests itself, which heat transfer devices implement direct, indirect (recuperative), and/or semi-direct heat transfer. The coolant can be of a liquid or gaseous nature. Any type of commonly used coolant or special coolant can be used. The invention is not limited to the type of coolant.
Thus by means of the temperature spreading device the coolant is cooled down to a suitable temperature so that a distinct and adequate temperature difference to corresponding heat transfer means (cooling elements, heat exchangers and the like) on the heat producing devices is produced in order to in an efficient manner absorb heat from the heat producing devices. At the same time, by means of the temperature spreading device, the heat dissipation temperature of a heat dissipation device is significantly increased relative to the temperature of the coolant in the return line. This means that even when the aircraft is situated on the ground on hot days in the sun an adequate temperature difference between the heat dissipation device and the environment of the aircraft can be ensured.
This provides a further technical effect in that it is not necessary to have already started up an air conditioning system of the aircraft in order to be able to provide adequately cool air for cooling the heat producing devices. Instead, it is imaginable to start up the temperature spreading device already shortly before starting up the heat producing devices so that in a relatively timely manner adequate cooling of the heat producing devices can be ensured even in the case of extreme temperatures within the aircraft. By means of the significant increase in temperature relative to the temperature of the coolant in the return line of the coolant circuit any type of heat dissipation device, for example a heat exchanger or the like, can dissipate the heat absorbed by the coolant to the environment even in the case of extreme ambient temperatures.
The embodiments are not limited to the use of a single design of a temperature spreading device; instead, any equipment, devices, and systems can be used that are able to spread a temperature level between two coolant lines. Accordingly, compression cooling machines, absorption cooling machines, diffusion absorption cooling machines, adsorption cooling machines, cooling machines based on the Joule-Thomson effect, thermo-electrical cooling generators (Peltier elements) and the like are imaginable. In addition, heat sinks or heat sources are imaginable in order to increase or decrease the temperature in a coolant line.
The design of the system is not complex, involves low-cost technically mature components, and operable without active blowing of cooling air or the like from the aircraft to the outside.
According to another embodiment of the system, the heat dissipation device is designed as a skin-section heat exchanger. The skin-section heat exchanger can in particular in flight ensure adequate heat transport to the environment. In order to improve the cooling performance with the aircraft situated on the ground, the skin-section heat exchanger can extend into an air duct pointing towards the aircraft interior, which air duct comprises at least one conveying device for conveying air from the environment or for conveying ram air. The extension of the skin-section heat exchanger into the air duct means that the skin-section heat exchanger can not only dissipate heat on the outside of the aircraft, but also comprises lamellae, ribs or other air-permeable structures towards the interior of the aircraft, which structures make it possible to dissipate heat to the ambient air. With the aircraft stationary on the ground, an air flow through the air duct can be enforced by operating the conveying device.
In another embodiment of the system, on openings that are directed towards the surroundings the air duct comprises closing elements, which during adequate flight speed of the aircraft can be closed in order to eliminate the additional aerodynamic resistance. The closing elements may, for example, be designed in the form of flaps or rotary-closure screens. The drive is to be implemented by electric, pneumatic, or hydraulic actuators that are customary in this special field.
In another embodiment of the system, the coolant circuit is an open circulation system. This provides an advantage in that air can be used as a coolant. Since a certain air volume flow needs to be removed anyway from the cabin of the aircraft to the environment, at least part of this can be used as coolant for the system.
Furthermore, in another embodiment, the temperature spreading device comprises a first coolant medium circuit with a condenser and an evaporator. In this way, by means of mature technology, in a mechanically simple manner and economical manner adequate temperature spreading and consequently particularly efficient cooling can be achieved by means of the system according to the invention.
According to another embodiment of the system, the condenser can be cooled with air from an additional air source. The air source is situated in the interior of the aircraft and/or is implemented with the use of ambient air and/or bleed air. In this manner, still further improved temperature spreading is achieved. This suggests itself in those cases where air is used as a coolant, and in particular, where the coolant circuit is open.
In another embodiment, the condenser is arranged at the return line of the coolant circuit. In this manner, at the same time, the temperature reduction that can be achieved by the evaporator is improved and consequently the overall efficiency of the system is improved.
At the same time, the evaporator too can be arranged at the return line of the coolant circuit. In this case, however, the condenser is not to be arranged at the feed line of the coolant circuit, but instead may, for example, be directly connected to the heat dissipation device or to some other heat dissipating element.
According to another embodiment of the system according, the condenser can be connected to a heat exchanger that is subjected to air from an air source. The air source is located in the interior of the aircraft, and/or is implemented by ambient air. Consequently, in this embodiment, too, the heat of the condenser can be dissipated by means of the heat exchanger to the through-flowing air from the air source.
Furthermore, in another embodiment of the system according, the temperature spreading device may comprise a first heat exchanger for cooling coolant from the return line of the coolant circuit with air from an air source. The air source is situated in the interior of the aircraft, and/or is implemented by ambient air. In this manner, at least in the case where the air conditioning system of the aircraft is already in operation, or in the case of adequately low ambient temperatures, reliable operation of the system can be achieved. The temperature spreading device should then in addition comprise further measures at least for cooling the coolant in the feed line.
A method is provided for cooling at least one heat producing device, by the use of a system for cooling at least one heat producing device in an aircraft, and by an aircraft comprising at least one heat producing device and at least one system for cooling a heat producing device in an aircraft.
Further characteristics, advantages, and application options of the present invention are disclosed in the following description of the exemplary embodiments and of the Figs. All the described and/or illustrated characteristics per se and in any combination form the subject of the embodiments, even irrespective of their composition in the individual claims or their interrelationships. Furthermore, identical or similar components in the Figs have the same reference characters.
In
The system 2 further comprises a heat dissipation device 8, which with a feed line 10 and a return line 12 of the space 6 or the heat producing device 4 forms a closed circulation system. In this circulation system, a coolant circulates that flows from the feed line 10 to the heat producing devices 4 where it absorbs heat. The coolant subsequently flows into the return line 12 to the heat dissipation device 8 where it dissipates heat to the environment of the aircraft, and subsequently again flows to the feed line 10 where it is again available for heat absorption.
Efficient heat dissipation by the heat dissipation device 8 to the environment, and particularly efficient heat absorption from a heat producing device 4 by the coolant from the feed line 10 can be achieved only in those cases where there is a corresponding temperature gradient to the environment or to the coolant. In particular, at high temperatures it can be difficult or entirely impossible to achieve a correspondingly high heat dissipation temperature in the heat dissipation device 8, which makes possible a heat flow to the environment in the first place. Likewise without further equipment the temperature of the coolant in the feed line 10 would be so high that there is no adequate temperature difference for cooling the heat producing devices 4, and in turn as a result of this a very high volume flow of the coolant becomes necessary. If the temperature of the environment is too high, even the highest coolant flow may not be sufficient to dissipate the heat.
For this reason, the system 2 comprises a temperature spreading device 14, which as an example is designed as a cooling medium circuit with a condenser 16, a flow control valve 18, an evaporator 20, and a compressor 22. This cooling medium circuit, which is also referred to as a cold-vapor cooling machine, is able to increase the temperature of the coolant from the return line 12 by means of the condenser 16, and to lower said temperature by means of the evaporator 20. This means that the coolant from the return line 12, which has already absorbed heat, is heated still further so that the heat dissipation temperature in the heat dissipation device 8 is clearly increased. This has the effect that the temperature gradient to the environment is adequate even on hot days, thus allowing efficient dissipation of heat. Likewise, the coolant flowing to the feed line 10 is cooled to a significantly lower temperature by the evaporator 20 so that, as a result, efficient absorption of heat from the heat producing device 4 can take place. If it were to become necessary, for example, due to a low ambient temperature, to increase to a lesser extent the temperature of the coolant flowing into the return line 12, in order to reduce heating of the coolant, a bypass 24 can be arranged on the condenser 16 so that at least part of the coolant flowing into the return line 12 can flow directly to the heat dissipation device 8.
In addition, the system 26 comprises an optional further air source 28, which introduces air into the return line 12 of the coolant circuit. As a result, the temperature of the coolant from the return line 12 is reduced before said coolant reaches the condenser 16. An optional bypass 24, shown in a dashed line in the illustration, serves to maintain the volume flow balance, and possibly for the exclusive use of air from the air source 28 for cooling the condenser 16, should this air be cooler than the temperature in the return line 12 of the coolant circuit.
If the aircraft is stationed on the ground on a hot day, it is not expected that ambient air automatically enters the aircraft in order to be used in the system 26. The system 26 thus comprises, for example, two conveying devices 30 and 32 by means of which fresh air from the surroundings of the aircraft is channeled to the evaporator 20 in the direction of the feed line 10 and is then conveyed from the aircraft to the outside. In this arrangement, the conveying devices 30 and 32 are located on suitable air openings 34 and 36, which, for example, in flight can be closed by means of closing elements 38 and 40, and on the ground, can be opened again.
In order to achieve an efficient spread of the temperature level between the heat dissipation device 44 and the feed line 10 a temperature spreading device 52 in the form of a cooling medium circuit is used, with the latter comprising an evaporator 54, a compressor 56, a condenser 58, and a flow control valve 60. However, in the figure, as an example the evaporator 54 is arranged between the feed line 10 and the return line 12 so that consequently the temperature of the coolant flowing from the return line 12 to the feed line 10 is reduced. Since already upstream of the evaporator 54 a heat dissipation device 44 can dissipate heat from the return line 12, with the use of the cooling medium circuit 52, the temperature in the feed line 10 can be further reduced to a significant extent.
Furthermore, the condenser 58 is cooled in a ram air duct or from an additional air source 28, for example, with the use of extraction air that also, for example, originates from the avionics compartment, from the cockpit, or from the cabin. As an alternative, the alternative air source 28 can be implemented by means of an inlet valve for ambient air on the aircraft fuselage, or by means of bleed air from one or several engines 130.
Such an arrangement is associated with a particular advantage in that the temperature spreading device 70 can be accommodated and operated in a pressurized region of the aircraft fuselage. In theory, a temperature spreading device, for example the temperature spreading device 52 of
If the system 64 is operated as an open circuit, then the two conveying devices 30 and 32 shown in
It is of course possible to use not only one single system 2, 26, 42 or 64 in an aircraft; for reasons associated with redundancy, multiplication is also imaginable. For this reason,
If, for example, one of the two temperature spreading devices 90 were to fail, the return lines 12 of the two coolant circuits may be pneumatically interconnected by means of the valve 92, and the feed lines 10 of the two coolant circuits may be pneumatically interconnected by means of a valve 94. As an alternative or in addition to this, it is also possible for heat to be transferred by way of the heat exchanger 96 from one coolant circuit to the other coolant circuit. This ensures that, for example, two spaces 6 with several heat producing devices 4 in an aircraft, which spaces are positioned at locations that are situated apart from each other, can be cooled adequately, also on the ground, also if one of the temperature spreading devices 90 were to fail.
To achieve an adequate airflow for absorbing the heat of the skin-section heat exchanger 102 when the aircraft is situated on the ground, in addition a fan 116 is arranged in the ram air duct 108. Accordingly, the skin-section heat exchanger 102 is not limited to heat transfer by convection on the outer skin 104. In order to reduce the aerodynamic resistance during flight phases with adequately high flight speed and adequately good heat transfer through the outer skin 104, the openings 110 and 112 can be closed by mechanically driven closing elements 118.
In a method as shown in
Finally,
It should be pointed out that “comprising” does not exclude other elements or steps, and “a” or “one” does not exclude a plural number. Furthermore, it should be pointed out that characteristics or steps, which have been described with reference to one of the above exemplary embodiments, can also be used in combination with other characteristics or steps of other exemplary embodiments described above. In addition, while at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment. It should be understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2009 039 814.7 | Sep 2009 | DE | national |
This application is a continuation of International Application No. PCT/EP2010/062734, filed Aug. 31, 2010, which was published under PCT Article 21(2) and claims priority to U.S. Provisional Patent Application No. 61/239,244, filed Sep. 2, 2009 and also claims priority to German Patent Application No. 10 2009 039 814.7, filed Sep. 2, 2009, the contents of which applications are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61239244 | Sep 2009 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2010/062734 | Aug 2010 | US |
| Child | 13409955 | US |
