Aircraft and method of operating an aircraft comprising an air separation device

Abstract

An aircraft including a combustion engine with a combustion chamber an injection device for injecting fuel in the combustion chamber and an air separation device adapted to separate air into an oxygen-enriched gas mix and an nitrogen-enriched gas mix, wherein the oxygen-enriched gas mix is injected into the combustion chamber with the fuel while the nitrogen-enriched gas mix is used to inert at least some portions of the aircraft in the environment of said combustion engine.

Claims

1. An aircraft comprising: a combustion engine including a combustion chamber, and an injection device including a fuel intake adapted to inject fuel in the combustion chamber and receive fuel through the fuel intake, an inerting circuit, and an air separation device including: an air intake adapted to intake an original gas mix comprising at least oxygen and nitrogen, an oxygen output from said air separation device is adapted to output an oxygen-enriched gas mix having an oxygen content higher than an oxygen content of the original gas mix, and a nitrogen output from which said air separation device is adapted to output a nitrogen-enriched gas mix having a nitrogen content higher than a nitrogen content of the original gas mix, wherein the nitrogen output of the air separation device is in fluid communication with the inerting circuit to provide the nitrogen-enriched gas mix to the inerting circuit, wherein the oxygen output of the air separation device is in fluid communication with the injection device to provide the oxygen-enriched gas mix to the injection device, and wherein the inerting circuit is in fluid communication with a peripheral channel around a fuel hose adapted to supply fuel to the fuel intake.

2. The aircraft according to claim 1, wherein the inerting circuit is in fluid communication with an engine compartment of the aircraft.

3. The aircraft according to claim 2, wherein the inerting circuit is in fluid communication with an upper part of the engine compartment.

4. The aircraft according to claim 1, further comprising a fuselage with a cabin adapted for passengers, and wherein the air intake of the air separation device is in fluid communication with a source of cabin air flowing to or from the cabin.

5. The aircraft according to claim 1, further comprising an engine controller configured to control at least one flow of: the original gas mix, the oxygen-enriched gas mix, the nitrogen-enriched gas mix, and the fuel.

6. The aircraft according to claim 1, further comprising a pneumatic circuit connecting the oxygen output of the air separation device and the injection device, wherein the pneumatic circuit includes a pump configured to pump the oxygen-enriched gas mix to the injection device.

7. The aircraft according to claim 1, wherein the fuel intake of the injection device is adapted to receive di-hydrogen fuel.

8. The aircraft according to claim 1, wherein the injection device is adapted to inject a mix of the oxygen-enriched gas mix and the fuel into the combustion chamber.

9. The aircraft according to claim 1, further comprising a premixer including: an oxygen intake adapted to receive the oxygen-enriched gas mix from the air separation device; a second fuel intake adapted to receive the fuel, wherein the premixer is adapted to mix the fuel and the oxygen-enriched gas mix, and an output adapted to output a mix of the fuel and the oxygen-enriched gas mix.

10. The aircraft according to claim 1, further comprising a controlled safety valve in a conduit pneumatically connecting the nitrogen output of the air separation device to the combustion chamber.

11. A method comprising producing an oxygen-enriched gas mix flow and a nitrogen-enriched gas mix from an air flow in an air separation device in an aircraft, injecting the oxygen-enriched gas mix and a fuel in a combustion chamber of a combustion engine generating power for the aircraft; and injecting the nitrogen-enriched gas mix in an inerting circuit channeling the nitrogen-enriched gas mix around a fuel pipe providing the fuel to the combustion chamber; wherein the channeling of the nitrogen-enriched gas mix includes flowing the nitrogen-enriched gas mix through a peripheral channel between a sleeve surrounding the fuel pipe and the fuel pipe.

12. The method according to claim 11, wherein the fuel is di-hydrogen.

13. The method according to claim 11, further comprising shutting off the combustion engine by injecting the nitrogen-enriched gas mix into the combustion chamber.

14. The method according to claim 13, wherein the step of shutting off the combustion engine includes injecting the nitrogen-enriched gas mix into the fuel pipe and shutting off the injection of the oxygen-enriched gas mix into the combustion chamber.

15. The method of claim 11, wherein the air flow is a flow of cabin air generated to flow into or exhausted from a passenger cabin in a fuselage of the aircraft.

16. The method of claim 11, wherein the combustion engine is an auxiliary power unit.

17. The method of claim 16, wherein the method is performed while the aircraft is in flight.

Description

SUMMARY OF DRAWINGS

(1) Some specific exemplary embodiments and aspects of the invention are described in the following description in reference to the accompanying figures.

(2) FIG. 1 is a schematic representation of an aircraft according to the invention comprising a rear fuselage section with an engine compartment hosting a combustion engine and an air separation device.

(3) FIG. 2 is a schematic representation of an engine compartment of an aircraft according to the invention.

(4) FIG. 3 is a schematic representation of systems of an aircraft according to the invention.

DETAILED DESCRIPTION

(5) FIG. 1 shows an aircraft 1 is represented. The aircraft comprises a rear fuselage section 2 in which is a combustion engine 38, such as an auxiliary power unit (APU). The auxiliary power unit and an air separation device are installed in an engine compartment in the rear fuselage section.

(6) FIG. 2 shows an engine compartment 34 in the rear fuselage section 2, shown in FIG. 1. The auxiliary power unit engine (APU) 38 is housed in this engine compartment 34. The APU includes a compressor 28 that takes in and compresses atmospheric air 37, mixes the compressed air with fuel a combustion chamber 27 which generates hot gases that drive a turbine 29 that generates the power produced by the APU. Exhaust gases 30 from the APU are discharged into the atmosphere.

(7) The engine compartment 34 houses a safety and efficiency device 11, which is or includes at least one air separation device. The safety and efficiency device 11 receives fuel via a fuel conduit 24 from a fuel source such as a fuel tank in the aircraft. The safety and efficient device also receives an original gas mix flow via a conduit 31, wherein the original gas mix flow may be cabin air 31 conditioned for a passenger cabin in the aircraft. The one or more air separation device that are or a part of the safety and efficiency device 11 separate(s) the original gas mix flow into an oxygen-enriched gas mix flow and a nitrogen-enriched gas mix flow. The safety and efficiency device 11 mixes the fuel received via that fuel conduit 24 with the oxygen-enriched gas mix to obtain a gas-fuel mixture to be supplied to an injection device 12 (FIG. 3) that injects the mixture into the combustion chamber 27 of the APU.

(8) In other embodiments of the invention, parts of the safety and efficiency device 11 may be outside of the engine compartment, as shown in FIG. 3 wherein the safety and efficiency device 11 is outside a wall 40 of the engine compartment for an APU.

(9) FIG. 3 schematically represents an example of the safety and efficiency device 11. In this embodiment, the safety and efficiency device 11 comprises an air separation device 18. The air separation device 18 receives cabin air via an intake. The cabin air is compressed by a compressor 35 that supplies compressed cabin air to the air separation device 18 at a controlled pressure.

(10) The air separation device 18 is adapted to separate the compressed cabin air flow received at its intake into an oxygen-enriched gas mix flow 26 that flows is exhausted from the air separation device via an oxygen output, and a nitrogen-enriched gas mix flow 19 that is also exhausted from the air-separation device. The air separation device 18 may for example be of the type comprising hollow fiber membranes through which flows the compressed cabin air. Oxygen in the compressed cabin air flows through porous walls of the membranes while the nitrogen cannot permeate through the walls. The porosity of the walls is selected to allow oxygen to pass but block nitrogen. The gas flow remaining within the hollow fiber membranes becomes nitrogen enriched.

(11) The oxygen-enriched gas mix flow 26 flows through pipes, e.g., conduits, and moved by a pump 36 adapted to pressurize the oxygen-enriched gas mix flow to a controlled pressure and feed the oxygen-enriched gas mix flow into a premixer 13.

(12) The premixer 13 also receives fuel from a fuel flow line 24. The premixer 13 comprises a mixing chamber adapted to mix the oxygen-enriched gas mix and the fuel. An output of the premixer 13 is connected to an input of an injection device 12, such that the fuel and oxygen-enriched gas mix may be conducted to the injection device 12. The injection device 12 is adapted and installed so as to be adapted to inject the fuel and oxygen-enriched gas mix directly into a primary zone 32 of the combustion chamber 27. The primary zone 32 of the combustion chamber is where the combustion between fuel and oxygen ignites, and this is where the highest temperatures are reached. Indeed, more air drawn from the atmosphere and compressed by the compressor 28 of the turbine engine is injected into the primary zone 32 and secondary zone 33. The combustion mix of fuel and oxygen moves towards the turbine from the primary zone to the secondary zone and out to the turbine. The temperature in the secondary zone 33 of the combustion chamber 27 is thus lower than in the primary zone 32. The injection of fuel and oxygen enriched air by the injection device 12 at the head of the primary zone provides a very pure mix with low levels of nitrogen, thereby reducing drastically the NOx byproducts during combustion.

(13) Before being brought to the premixer 13, the fuel is extracted from tanks, and is brought by fuel pipes 16 to the premixer 13. The fuel pipes 16 may comprise double-wall forming a peripheral channel 17 around the fuel pipe 16. On FIG. 3, only part of the double-walled fuel pipe 16 is represented. However, such fuel pipe may be used on any pipe section to transport fuel or a mix comprising fuel.

(14) In the embodiment presented in FIG. 3, the nitrogen-enriched gas mix flow 19 is separated into multiple nitrogen-enriched gas mix flows (illustrated by lines of dashes separated by two dots in FIG. 3). A first nitrogen-enriched gas mix flow 20 is directed towards the peripheral channel 17 around fuel pipes 16. Thereby any fuel vapor that would result from a permeation or a leak through a wall of the pipe 16 is not only vented by the nitrogen-enriched gas mix flow but also inerted by the high nitrogen content of the nitrogen-enriched gas mix. The nitrogen-enriched gas mix flow may then be vented to the atmosphere outside the aircraft through venting ports for example.

(15) A second nitrogen-enriched gas mix flow 21 is directed towards a controlled safety vale or fuel flow shut-off valve 23. This fuel flow shut-off valve 23 allows to cut a fuel flow supply from a fuel tank towards the premixer 13. Additionally, this fuel flow shut-off valve 23 allows to inject a nitrogen-enriched gas mix flow 21 into the fuel pipes 16 instead of fuel, such as a nitrogen-enriched gas mix flow flows towards the premixer 13 until the combustion chamber 27. When the nitrogen-enriched gas mix reaches the combustion chamber, the combustion is suffocated such that a safe shut down of the turbine engine is obtained.

(16) Moreover, when the engine stops by suffocation, the pipes 16 between the fuel flow shut-off valve 23 and the combustion chamber are also clean of fuel and inerted by the nitrogen-enriched gas mix flow 21.

(17) When the fuel flow shut-off valve 23 is closed to fuel and open to nitrogen-enriched gas mix, another shut-off valve 14 may close the oxygen-enriched gas mix flow to the premixer 13, such that the premixer feeds the injection system and in its turn the combustion chamber only with nitrogen-enriched gas mix.

(18) A third nitrogen-enriched gas mix flow 22 is directed to specific predetermined zones (not detailed in FIG. 3) in the engine compartment such as hot parts that require cooling in order to mitigate ignition risks, areas where leaks of fuel or other combustible product such as for example greases may happen and must be inerted. The third nitrogen-enriched gas mix flow 22 may also be directed towards an upper portion of the engine compartment in order to vent it. This is particularly beneficial in case of lighter than air fuel or combustibles such as di-hydrogen. The upper portion of the engine compartment 34 may thus be inerted and vented by a nitrogen-enriched gas mix flow 22.

(19) The aircraft example presented on FIGS. 1-3 also comprises an auxiliary power unit fuel system 15. The fuel system 15 is not detailed on FIG. 3. The auxiliary power unit fuel system 15 is designed to supply fuel to the auxiliary power unit at any ambient temperature, pressure or altitude within the operating envelope of the aircraft. The auxiliary power unit fuel system 15 comprises: a fuel flow filter, a fuel pump, a pressure regulation device, a fuel shut off valve, a fuel control unit and some sensors such as for example temperature sensor, and pressure sensor. The auxiliary power unit fuel system is adapted to operate properly with fuel containing ice at low temperatures, fuel containing additives and contaminants.

(20) FIG. 3 shows a controller 39 adapted to control a flow of oxygen-enriched gas mix 26 by controlling the oxygen-enriched gas mix pump 36. The controller 39 is also adapted to control a flow of fuel 24 for said combustion engine 38 by controlling the fuel system 15. The controller 39 may also control the premixer 13, so as to control the mix percentages between fuel and oxygen-enriched gas mix.

(21) In other embodiments of the invention, the controller 39 may also adapted to control the compressor 35 so as to control an air supply to the air separation device 18. The controller may also be adapted to control the fuel shut-off valve 23, and/or the oxygen-enriched gas mix shut-off valve 14.

(22) 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.