System for inerting and method for generating an inerting gas in an aircraft, operating without collecting outside air

Abstract

An inerting system for aircraft including a gas circuit with successively at least one air inlet, a compressor and an air separation module. The air separation module includes an outlet for oxygen-enriched gas and an outlet for inerting gas. The air separation module includes gas permeation membranes resistant to a temperature greater than or equal to 100° C. and preferably 140° C., and the inerting gas outlet is connected to a turbine for releasing pressure and cooling the inerting gas.

Claims

1. An inerting system for aircraft, said system comprising a gas circuit with successively at least an air inlet, a compressor and an air separation module where the air separation module comprises an outlet for oxygen-enriched gas and an outlet for inerting gas, wherein the air separation module comprises gas permeation membranes resistant to a temperature greater than or equal to 100° C., and the inerting gas outlet is connected to a turbine for releasing pressure and cooling the inerting gas; wherein the turbine is mechanically coupled to an electric motor rotating the compressor, thus forming a turbocompressor; and wherein the air circuit comprises, at an outlet of the compressor which compresses air to the air separation module, a compressed air bypass conduit in which the electric motor is arranged, the bypass conduit comprising a portion of section sized for reducing pressure and cooling compressed air upstream from the electric motor in order to cool the electric motor.

2. The system according to claim 1, wherein the gas permeation membranes are resistant to a temperature greater than or equal to 140° C.

3. The system according to claim 1, wherein the bypass conduit opens near the oxygen-enriched gas outlet in order to be mixed therewith.

4. A method for generation of inerting gas in an aircraft implementing the inerting system according to claim 1, wherein said method comprises the steps of: Feeding the inerting system gas circuit with air; Compressing the air by means of the compressor; Circulating compressed air directly through the gas permeation membranes resistant to a temperature greater than or equal to 100° C. for depleting the air of oxygen and generating an inerting gas; and Releasing the pressure on the inerting gas by means of the turbine for generating a low temperature inerting gas.

5. The method according to claim 4, wherein the method comprises recovering energy from the turbine for rotating the compressor.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Further advantages and features will become clearer from the following description, given by way of a non-limiting example, of the inerting system and method of inerting gas generation according to the invention, with reference to the accompanying drawings, in which:

(2) FIG. 1 is a schematic representation of the inerting system according to the invention and according to a first embodiment of the means of cooling of the turbocompressor electric motor;

(3) FIG. 2 is a schematic representation similar to that from FIG. 1 showing a second embodiment of the means of cooling;

(4) FIG. 3 is a schematic representation similar to that from FIG. 1 and showing a third embodiment of the means of cooling.

DETAILED DESCRIPTION OF THE INVENTION

(5) Referring to FIGS. 1 to 3, the invention relates to an inerting system (1) for aircraft serving to make a volume inert such as a fuel tank, cargo compartment, battery storage area, or any other volume.

(6) The inerting system (1) comprises a gas circuit comprising an inlet (2) intended to be supplied with air, for example with air coming from the passenger cabin of the aircraft. The air circuit next comprises a compressor (3), rotated by an electric motor (4) for compressing the air.

(7) At the outlet of the compressor (3), the compressed air passes over an ozone converter (5) and a particle filter (6) before entering into at least one air separation module (7). Referring to FIGS. 1 to 3, the described inerting system (1) comprises two air separation modules (7). Each air separation module (7) includes gas permeation membranes inside, for example polymer membranes, resistant to high temperatures, in particular over 100° C. and preferably over 140° C. The number of air separation modules (7) depends on the desired performance of the inerting system (1). The compression rate of the compressor (3) is limited so as not to exceed the maximum allowable temperature of the membranes. For example, for a limit temperature of 130° C. for the air at the inlet of the air separation module (7), the compression rate of the compressor (3) is limited to about 2.5 if an 80% polytropic efficiency of the compressor (3) is considered.

(8) The compressed air is passed through the gas permeation membranes for generating both an oxygen-enriched gas exhausting via an outlet (8) and also an oxygen-depleted gas constituting the inerting gas exhausting by an outlet (9). The outlet (9) for inerting gas is connected to a turbine (10) used for releasing pressure and cooling the inerting gas.

(9) The turbine (10) is mechanically coupled to the electric motor (4) of the compressor (3) so as to form an electric turbocompressor assembly (3-4-10). Thus, the presence of the turbine (10) serves to recover pneumatic energy contained in the inerting gas in order to turn the compressor (3) while lowering the temperature of the inerting gas before injection into the volume to be made inert. It was observed in practice that the turbine (10) serves to recover about 20% of the pneumatic energy from the inerting gas.

(10) A flow rate regulator valve (11) is arranged on the air circuit, downstream from the turbine (10), to regulate the flow rate of inerting gas, which is then directed to a distribution system, not shown.

(11) To improve the reliability of the system and the lifetime thereof, some components require cooling, in particular the electric motor (4), an electronic control unit (12) for said motor (4), and any other electric motor component (4), such as ball bearings or air bearings, not shown.

(12) For this purpose, the system comprises cooling means which can be implemented in several ways.

(13) A first embodiment is shown in FIG. 1, in which a portion of the compressed air from the compressor (3) is collected by means of a bypass conduit (13) comprising a portion of section (14) sized for reducing the air pressure, and in which the electric motor (4) is disposed so as to be able to be cooled by the flow of air released. In fact, releasing the pressure on the air is sufficient for causing the temperature thereof to drop and thus cooling the various elements making up the electric motor (4). The bypass conduit (13) next opens near the oxygen-enriched gas outlet (8) in order to be mixed therewith, in particular in a mixer (15). The mixture thus created is routed to the outside of the airplane through a pipe.

(14) According to another mode of regulation, shown in FIG. 2, the cooling of the electric motor (4) is done by means of a bypass conduit (13) arranged upstream of the compressor (3) and in which a blower (16) is disposed for aspirating air and directing it towards the motor (4) also disposed in the bypass conduit (13) for cooling it. With the blower (16), a sufficient gas flow rate is generated for cooling the electric motor (4). In the scenario where the inerting system (1) is fed with air coming from an aircraft cabin, the blower (16) is used and running when the aircraft is on the ground, and then stopped in flight. The pressure difference between the outside of the aircraft and the passenger cabin from which the air is for example collected is sufficient to generate a flow rate for cooling the electric motor (4). The air passes through the unpowered blower (16) and the flow rate thereof is advantageously adjusted by means of a flow rate regulator valve (17) positioned in the bypass conduit (13) upstream from the oxygen-enriched gas outlet (8). In the same way as before, the bypass conduit (13) opens near the oxygen-enriched gas outlet (8) in order to be mixed therewith.

(15) A third embodiment of the cooling means is shown in FIG. 3. In this embodiment, the inerting system air circuit (1) comprises, upstream from the compressor (3), an air bypass conduit (13) intended to feed a centrifugal blower (18). The centrifugal blower (18) is mechanically connected to the first compressor (3) and has a lower compression ratio, for example 1.2, for generating a sufficient cooling air flow rate for cooling the electric motor (4) which is also disposed in the bypass conduit (13). In the same way, the bypass conduit (13) next opens near the oxygen-enriched gas outlet (8).

(16) From the preceding, the invention provides an inerting system (1) comprising an air circuit, for example fed with air collected in the passenger cabin of the aircraft. With the inerting system (1), air can be compressed by means of the compressor (3) and the compressed air can be circulated, directly at high temperature, through gas permeation membranes resistant to this high temperature, in order to deplete the air of oxygen and generate the inerting gas. In contrast to the state of the art, this inerting system (1) does not require collection of outside air for cooling the air upstream from the membranes, and at the outlet from said membranes the pressure on the inerting gas is released via a turbine (10) for generating a low-temperature inerting gas.

(17) Because of the preceding, the invention is able to eliminate the air preparation system, and in particular the outside air collection. The system therefore has a low bulk, is reliable and does not create additional drag, and therefore does not worsen aircraft fuel consumption or CO.sub.2 emissions.