Fuel cell system with suction operation for an aircraft

1. A fuel cell system for an aircraft, the fuel cell system comprising:

a supply module with a fuel cell unit;

a suction module for drawing oxygen through the fuel cell unit; and

an energy management unit for controlling a suction performance of the suction module so that the suction performance is configured to be set independently of a flight altitude of the aircraft;

wherein the suction module comprises a waste water separator and is configured to draw oxygen through the fuel cell unit and to receive and separate waste water from an on-board toilet or wash basin; and

wherein the waste water separator is further configured as a pressure tank and is connected to an aircraft environment for generating a required negative pressure.

2. The fuel cell system of claim 1 ,

wherein the supply module is configured to produce fresh water and electrical energy.

3. The fuel cell system of claim 1 ,

wherein the supply module comprises a humidity/heat exchanger for pre-humidifying the oxygen drawn through the fuel cell unit.

4. The fuel cell system of claim 1 ,

wherein the waste water separator is configured in the form of a cyclone separator.

5. The fuel cell system of claim 1 , further comprising:

a storage module for collecting the waste water from the waste water separator.

6. The fuel cell system of claim 5 ,

wherein the storage module comprises a waste-water storage tank that is always subjected to cabin pressure.

7. The fuel cell system of claim 5 ,

wherein the suction module and the storage module form part of a vacuum system for an on-board toilet.

8. The fuel cell system of claim 1 , further comprising:

a fresh-water module for storing the fresh water generated by the supply module.

9. The fuel cell system of claim 8 ,

wherein the fresh-water module comprises a cold-water circuit and a hot-water circuit with a heat exchanger;

wherein the hot-water circuit is configured to be heated by a heat exchanger by waste heat arising during condensation in a condenser in the supply module or during operation of an electrical consumer; and

wherein the cold-water circuit and the hot-water circuit are configured to supply fresh water in the aircraft.

10. The fuel cell system of claim 9 ,

wherein the cold-water circuit comprises a regulating valve for feeding the hot-water circuit.

11. The fuel cell system of claim 9 ,

wherein the fresh-water module comprises an ejector pump for approximating a pressure level of an output side to a pressure level of an input side of the condenser.

12. The fuel cell system of claim 1 ,

wherein the suction module is configured to supply oxygen-depleted air from the supply module to a space in the aircraft, which space is to be inerted.

13. The fuel cell system of claim 12 , further comprising:

a pressure control device;

an outlet to an exterior air of the aircraft; and

a line for connecting the suction module to the space to be inerted;

wherein the pressure control device and the outlet are arranged in the space.

14. The fuel cell system of claim 1 , further comprising:

an oxygen sensor for measuring oxygen content in a cathode exhaust gas of the fuel cell unit.

15. A method for operating a fuel cell system for an aircraft, the method comprising:

drawing oxygen through a fuel cell unit by means of a suction module;

producing fresh water and electrical energy by means of a supply module which comprises the fuel cell unit; and

controlling a suction performance of the suction module so that the suction performance is configured to be set independently of a flight altitude of the aircraft;

wherein the suction module comprises a waste water separator and is configured to draw oxygen through the fuel cell unit and to receive and separate waste water from an on-board toilet or wash basin;

wherein the waste water separator is configured as a pressure tank and is connected to an aircraft environment for generating a required negative pressure.

16. An aircraft comprising a fuel cell system; the fuel cell system comprising:

a supply module with a fuel cell unit;

a suction module for drawing oxygen through the fuel cell unit; and

an energy management unit for controlling a suction performance of the suction module so that the suction performance is configured to be set independently of a flight altitude of the aircraft;

wherein the suction module comprises a waste water separator and is configured to draw oxygen through the fuel cell unit and to receive and separate waste water from an on-board toilet or wash basin; and

wherein the waste water separator is configured as a pressure tank and is connected to an aircraft environment for generating a required negative pressure.