FUEL CELL SYSTEM FOR AN AIRCRAFT

Abstract

In a fuel cell system intended for a pressure-independent operation, in which at least one fuel cell having an open cathode is provided, a first fluid chamber adjoins an inflow cross section and a second fluid chamber adjoins an outflow cross section. In the fluid chambers can be set an overpressure which is adapted to the operation of the at least one fuel cell.

Claims

1. A fuel cell system for an aircraft, comprising: a fuel cell unit having an anode inlet and an open cathode, which has an inflow cross section and an outflow cross section; a first fluid chamber having a first cavity, a first connecting opening and at least one first fluid port; a second fluid chamber having a second cavity, a second connecting opening and at least one second fluid port; a device coupled to the first fluid port to provide pressurized air; an air outlet coupled to the second fluid port; and a first pressure regulating device; wherein the first connecting opening is connected to the inflow cross section such that the inflow cross section is in direct connection solely with the first cavity; wherein the second connecting opening is connected to the outflow cross section such that the outflow cross section is in direct connection solely with the second cavity; wherein the first pressure regulating device is configured to, by influencing the discharge of air from the second fluid chamber, regulate an overpressure in the second cavity, so that a predetermined airflow necessary for the operation of the fuel cell unit flows from the first fluid chamber, through the open cathode of the fuel cell unit, to the second fluid chamber.

2. The fuel cell system according to claim 1, wherein the first pressure regulating device is arranged to alter the overpressure in the second cavity in dependence on an ambient pressure of the fuel cell system.

3. The fuel cell system according to claim 1, further comprising a second pressure regulating device, wherein: the anode inlet is coupled to a device for providing hydrogen; the second pressure regulating device is in operative connection with the anode inlet and the device for providing hydrogen; and the second pressure regulating device is arranged to influence a fuel pressure at the anode inlet in dependence on a pressure in the first fluid chamber.

4. The fuel cell system according to claim 1, wherein the device for providing pressurized air has a compressor coupled to the first fluid inlet.

5. The fuel cell system according to claim 1, wherein a precooler for cooling pressurized air is arranged between the device for providing pressurized air and the first fluid inlet.

6. The fuel cell system according to claim 1, wherein: the first fluid chamber has a first recirculation port; the second fluid chamber has a second recirculation port; and the first recirculation port and the second recirculation port are coupled to one another via a fan, which conveys air out of the second fluid chamber into the first fluid chamber.

7. The fuel cell system according to claim 6, further comprising a non-return valve between the fan and the first recirculation port.

8. The fuel cell system according to claim 6, further comprising a third pressure regulating device arranged to, in dependence on an ambient pressure of the fuel cell system, influence a fluid volume flow from the second fluid chamber into the first fluid chamber.

9. The fuel cell system according to claim 1, further comprising a flush valve connected to an anode outlet and arranged to selectively flush the anode of the fuel cell unit.

10. The fuel cell system according to claim 1, further comprising a fuel pressure control valve coupled to the anode inlet and arranged to influence a through-flow of fuel into the anode inlet.

11. The fuel cell system according to claim 1, wherein the device for providing pressurized air and the first pressure regulating device are arranged to set and maintain an operating differential pressure, which is predetermined for the operation of the fuel cell unit, independently of an ambient pressure of the fuel cell system.

12. An aircraft comprising: an aircraft fuselage; and at least one fuel cell system according to claim 1.

13. The aircraft according to claim 12, wherein the at least one fuel cell system is arranged in a non-pressurized region of the aircraft fuselage.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Further features, advantages and possible applications of the present disclosure emerge from the following description of the illustrative embodiments and the figures. All described and/or depicted features here form in their own right and in any chosen combination the subject of the disclosure, also independently of their composition in the individual claims or the back-references thereof. In the figures, the same reference symbols continue to stand for the same or similar objects.

[0035] FIG. 1a shows a schematic representation of the fuel cell system.

[0036] FIGS. 1b and 1c show schematic representations of the two fluid chambers in a side view.

[0037] FIG. 2 shows an aircraft in the form of a commercial airplane having a fuel cell system installed therein.

DETAILED DESCRIPTION

[0038] The following detailed description is merely illustrative in nature and is not intended to limit the embodiments of the subject matter or the application and uses of such embodiments. As used herein, the word exemplary means serving as an example, instance, or illustration. Any implementation described herein as exemplary is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.

[0039] FIG. 1a shows a schematic representation of a fuel cell system 2. This has a fuel cell unit 4, which, by way of example, possesses a plurality of single (not individually represented) fuel cells, which together form a coherent unit, for example in the form of a fuel cell stack. In order to supply consumer appliances with electric voltage, the fuel cell unit 4 is provided with electrical conductors 6, which can be connected, for instance, to an airborne supply system of an aircraft when the fuel cell system 2 is installed in one such thereof. For the supplying of the fuel cell unit 4 with fuel, for example hydrogen, an anode inlet 8 and an anode outlet 10 are provided.

[0040] The fuel cell unit 4 has, moreover, an inflow cross section 12 and an outflow cross section 14, which serve to make air flow through an open cathode 16 of the fuel cell unit 4. The inflow cross section 12 is directly adjoined by a first fluid chamber 18, which has a first connecting opening 20 that is connected solely to the inflow cross section 12. A first cavity 22 inside the first fluid chamber 18 is therefore in fluid connection solely with the inflow cross section 12.

[0041] In addition, a device 24 for providing pressurized air is provided. This is equipped with a motor 26 and a compressor 28 drivable by the motor 26 and provides pressurized air. This can be warmed by the compression and is, in this illustrative embodiment, conducted through an optional precooler 30, which is represented merely schematically. It is self-evident that the precooler 30 is arranged to cool the compressed air and to transport the heat of the compressed air, for example through a suitable medium, from the precooler 30 to a heat delivery device (not shown).

[0042] Through the introduction of the pressurized air via a first fluid port 23, in the first cavity 22 is formed an overpressure, by which air flows via the inflow cross section 12 into the cathode 16. Since the cathode 16 is constructed as an open cathode, the air flows through this and via the outflow cross section 14 into a second fluid chamber 32, i.e. into a second cavity 34 which is present there. The second fluid chamber 32 has a second connecting opening 21, which is in connection solely with the outflow cross section 14. Via a second fluid port 36, the air is delivered to the outside. As a result, the cathode 16 is supplied by the air with oxygen and further cooled.

[0043] Downstream of the second fluid port 36 is arranged a first pressure regulating device 38, which, by way of example, in dependence on an ambient pressure, influences the discharge from the second cavity 34. The pressure is thereby influenced both in the second cavity 34 and in the first cavity 22. Through targeted influencing of the discharge, a specific pressure level can be achieved in the second cavity 34 and, as a result of the fluid connection to the first cavity 22, there too.

[0044] For the pre-regulation of a fuel pressure, a fuel line 40 is equipped with a fuel pressure control valve 42, which could be constructed as a simple throttle valve. A second pressure regulating device 44 is here arranged, by way of example, downstream of the fuel pressure control valve 42 and can set a pressure of the fuel downstream of the second pressure regulating device 44 in dependence on the pressure in the first cavity 22. To this end, the second pressure regulating device is connected via a pressure port 45 to the first fluid chamber 18. As a result of the pre-regulation of the fuel pressure, the second pressure regulating device 44 has only to conduct a relatively small reduction of the fuel pressure. Further downstream follows the anode inlet 8, into which the fuel is introduced. It is preferred that the pressure of the fuel at the anode inlet 8 substantially corresponds to the pressure in the first cavity 22.

[0045] In order to flush the anode of the fuel cell unit 4 and herein, in particular, rid it of accumulated water, a flush valve 46 is present. The actuation can be realized selectively, according to need, or in an automated manner at specific time intervals.

[0046] Inter alia for the improved alignment of the pressures in the first cavity 22 and the second cavity 34, a bypass arrangement 48 can be used. This comprises, by way of example, a fan 50, a third pressure regulating device 52 and a non-return valve 54. Air can hereby be drawn from the second cavity 34 via a second recirculation port 53, which at the same time can be one of a plurality of second fluid ports. This air can be conveyed by the fan 50 to a first recirculation port 55. This can be one of a plurality of first fluid ports. Consequently, air is actively drawn by the fan 50 out of the second cavity 34 and fed to the first cavity 22. By the non-return valve 54, it is achieved that air cannot flow directly out of the first fluid chamber 18 into the second fluid chamber 32. The fan 50 shall be designed such that the hereby achievable pressure difference exceeds the drop in pressure between the first fluid chamber 18 and the second fluid chamber 32.

[0047] The third pressure regulating device 52 is arranged to, independently of an ambient pressure of the fuel cell system 2, influence a fluid volume flow from the second fluid chamber 32 into the first fluid chamber 18. In particular, the third pressure regulating device 52 opens when the ambient pressure becomes lower and closes when the ambient pressure becomes higher.

[0048] Merely by way of example, the environment with the ambient pressure and with the air contained in the environment is represented as a block, which has the reference symbol 56. Air from the environment 56 is fed to the compressor 28, the precooler 30 and the first pressure regulating device 38, and in the form of a pressure, to the third pressure regulating device 52.

[0049] FIGS. 1b and 1c additionally show schematically the two fluid chambers 18 and 32, in which respectively the connecting opening 20 or 21 is indicated. This latter is adapted to the inflow cross section 12 and outflow cross section 14 respectively. The two fluid chambers 18 and 32 are configured such that they are attachable, preferably flushly, to the fuel cell unit 4. The connecting openings 20 and 21 should here be brought into connection solely with the respective cross section 12 or 14. Transitions or separation points between the fuel cell unit 4 and outer boundaries of the fluid chambers 18 and 32 are here sealed.

[0050] FIG. 2 shows an aircraft 58, which has a fuselage 60 and a fuel cell system 2 installed therein. The fuel cell system 2 is arranged, by way of example, in a rear part of the fuselage 60 and is preferably located in a non-pressurized region.

[0051] In addition, it should be pointed out that comprising does not preclude any other elements or steps, and a or one does not preclude a plurality. It should further be pointed out that features which have been described with reference to one of the above illustrative embodiments can also be used in combination with other features of other above-described illustrative embodiments. Reference symbols in the claims should not be regarded as a restriction.

[0052] While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or embodiments described herein are not intended to limit the scope, applicability, or configuration of the claimed subject matter in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the described embodiment or embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope defined by the claims, which includes known equivalents and foreseeable equivalents at the time of filing this patent application.