SYSTEM FOR INERTING AT LEAST ONE VOLUME IN AN AIRCRAFT VIA AT LEAST ONE FUEL CELL

Abstract

A system for inerting at least one volume in an aircraft includes at least one generator of inert gas fed with compressed air originating from a passenger cabin, and means for distributing the inert gas into the volume to be rendered inert, which are connected to the generator of inert gas. According to the invention, the generator of inert gas comprises a fuel cell including an outlet of oxygen-depleted gas connected to means for drying said gas.

Claims

1. A system for inerting at least one volume in an aircraft, said system comprising at least one inert gas generator, supplied with compressed air from a passenger cabin, and means for distributing the inert gas into the volume to be rendered inert, connected to the inert gas generator, wherein the insert gas generator comprises a fuel cell including an oxygen-depleted gas outlet connected to means for drying said gas.

2. A system in accordance with claim 1, wherein the means for drying comprise a heat exchanger.

3. A system in accordance with claim 1, wherein the means for drying comprise at least one air/water separation membrane.

4. A system in accordance with claim 1, wherein the means for drying comprise at least one enthalpy wheel.

5. A system in accordance with claim 1, wherein the means for drying comprise two successive drying devices.

6. A system in accordance with claim 5, wherein the means for drying comprise at least one air/water separation membrane connected to the outlet of a heat exchanger.

7. A system in accordance with claim 5, wherein the means for drying comprise at least one enthalpy wheel connected to the outlet of a heat exchanger.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0019] Other advantages and features of the contemplated embodiments will appear more clearly from the following description, given as a non-restrictive example, with reference to the sole FIGURE appended, schematically illustrating an inerting system.

DETAILED DESCRIPTION

[0020] With reference to FIG. 1, which shows an inerting system (1) for injecting a flow of inert gas (2) into at least one volume (3), such as a fuel tank, a cargo compartment, an avionics bay, a hidden area, or sheathing for electric cables, in an aircraft or similar.

[0021] The inerting system (1) comprises a fuel cell (4) designed to be supplied with a reducing gas, such as hydrogen, and an oxidizing gas (5), such as air. In practice, the air originates from the passenger cabin of the aircraft, having been previously compressed by an electric compressor. At the outlet, the fuel cell (4) generates electricity, heat, water, and also oxygen-depleted humid air (6) destined to form the inert gas (2) to be injected into the volume (3) to be rendered inert. Depending on the aircraft, the mission profile, and the flight phase, the power of the fuel cell (4) is, for example, between 4 and 25 kW.

[0022] The fuel cell outlet is connected to means for drying (7) so that dry inert gas (2) can be injected into the volume (3) to be rendered inert, in particular a fuel tank. This is because, at the outlet of the fuel cell (4), hot, humid inert gas (6) cannot be injected in its unaltered state into a fuel tank.

[0023] The humid inert gas (6) is then channeled through a heat exchanger (8), which enables it to be cooled and hence a first drying operation to be carried out. The heat exchanger (8) can be any type, for example a condenser. As an example, and depending on the aircraft, the mission profile, and the flight phase, the condenser is sized such that it can absorb between 10 g and more than 70 g of water per kg of dry air.

[0024] According to the various embodiments, the cooled inert gas at the outlet of the heat exchanger (8) is channeled either through at least one air/water separation membrane (9) via permeation, or through at least one enthalpy wheel (10), enabling water to be absorbed to carry out a second drying step.

[0025] In practice, the air/water separation membrane (9) and the enthalpy wheel (10) are sized such that the remaining water content is between 1.90 g and 2.10 g of water per kg of dry air.

[0026] Simulations have shown that to be compatible with being injected into a fuel tank, the water content of the inert gas (2) must reach the value of 2 g of water per 1 kg of dry air, i.e. an inert gas (2) dew point of 10 C. below 1 bar absolute. Combining the heat exchanger (8) and the permeation membrane (9), or the heat exchanger (8) and the enthalpy wheel (10) enables such a water content to be achieved. The maximum value of 2 g of water per kg of dry air is set so as to ensure that the injection of dry air into the fuel tanks does not result in frosting phenomena.

[0027] The cooled inert gas (2) is dry at the outlet and can then be channeled to means for distributing (11) the inert gas (2) for injection in its unaltered state into the volume (3) to be rendered inert. The means for distribution (11) are well-known and consist of distribution pipes, various types of valves, such as check valves, etc. The injection into the volume (3) is, for example, carried out by injection nozzles. A controller (12), connected to the fuel cell (4) and to the various devices comprising means for drying (7), in particular the heat exchanger (8), the separation membrane (9) or the enthalpy wheel (10), the valves, the pressure and humidity sensors, enable the production and distribution of inerting gas (2) to be managed and controlled.

[0028] The inerting system (1) thus enables an inert gas (2) to be generated and injected into a volume (3) of an aircraft, for example a fuel tank, for safety reasons in order to reduce the risk of explosion of said volume (3). The inert gas (2) injected aims to render the volume (3) inert, i.e. it enables the oxygen content present in said tank(s) (2) to be reduced, and in particular to maintain this content below a certain threshold, for example lower than 12%.

[0029] The oxygen content present in the inert gas (2) does not depend on the aircraft engine speed and hence does not depend on the pressure profile. The pressure of the inert gas (2) at the outlet of the fuel cell (4) fluctuates far less than with an inerting system bleeding air from the engines, and has no effect on the oxygen content present in the inert gas (2). The purity of the inert gas (2) is known and remains substantially constant throughout the mission of the aircraft. It also saves on air from the aircraft engines.

[0030] The disclosed embodiments were achieved by going against certain prejudices, in particular the presence of pressurized hydrogen in an aircraft, installing new devices of yet to be proved maturity in the field of aeronautics, such as humidity sensors, air/water permeation membranes (9), managing humid air in a cold environment, and the fact of placing a fuel cell (4) into an aircraft without yet having had enough feedback on the average time between failures, and on the operating safety features.