Aircraft comprising a hydrogen supply device incorporating a hydrogen heating system positioned in the fuselage of the aircraft

An aircraft including a fuselage, a wing structure, at least one turbomachine running on hydrogen and generating thrust at a propulsion unit distant from the fuselage, at least one fuel tank positioned in the fuselage and configured to store hydrogen in the cryogenic state, at least one hydrogen supply device connecting the fuel tank and the turbomachine and including at least one pump positioned in the fuselage in the vicinity of the fuel tank, at least one hydrogen heating system positioned in the fuselage in the vicinity of the pump. This solution makes it possible to reduce a length of the complex double-walled pipes configured for carrying the hydrogen in the cryogenic state between the fuel tank and the hydrogen heating system.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of the French patent application No. 2108416 filed on Aug. 3, 2021, the entire disclosures of which are incorporated herein by way of reference.

FIELD OF THE INVENTION

The present application relates to an aircraft comprising a hydrogen supply device incorporating a hydrogen heating system positioned in the fuselage of the aircraft.

According to one embodiment visible inFIG.1, an aircraft10comprises a fuselage12, a wing structure14and several propulsion units16positioned on each side of the fuselage, connected to the wing structure14and each comprising a turbomachine18.

In the case of an aircraft running on a hydrocarbon-based fuel, the aircraft10comprises fuel tanks20incorporated into the wing structure14and a fuel supply device22connecting each turbomachine18to a fuel tank20. In one configuration, the fuel supply device comprises at least a pump24and at least a heat exchanger26for preheating the fuel. This heat exchanger26, which uses at least a source of heat from the turbomachine18, is positioned at the propulsion unit16.

In the case of an aircraft running on hydrogen, the latter comprises at least one fuel tank positioned in the fuselage and configured to store the hydrogen in the liquid and cryogenic state. The aircraft also comprises a hydrogen supply device connecting each turbomachine to a fuel tank and comprising a high-pressure pump and a heat exchanger. In so far as the energy required to compress the hydrogen is lower when the hydrogen is in the liquid state, the high-pressure pump is positioned at the outlet of the fuel tank. As the sources of heat are essentially produced by the turbomachines, the heat exchangers are positioned in the vicinity of the turbomachines in the propulsion units. To complement this, the hydrogen supply device comprises pipes to carry the hydrogen at high pressure, in the liquid and cryogenic state, from the high-pressure pump positioned in the fuselage as far as the heat exchanger positioned in one of the propulsion units. Given the liquid and cryogenic state, the pipes are complex double-walled thermally insulated pipes, the space between the two walls being inerted or evacuated.

The use of complex double-walled pipes, combined with the significant distance separating the high-pressure pump and the heat exchanger leads to high costs and significantly increases the on-board mass. Because such double-walled pipes are short, it is necessary to provide numerous couplings which even further increase the costs and the on-board mass.

Document US2008/006743 discloses an aircraft with a high-flying altitude and long endurance, powered by hydrogen and comprising a tank of cryogenic fluid positioned in the fuselage of the aircraft, the aircraft propulsion system being arranged on the fuselage or on the wing of the aircraft.

SUMMARY OF THE INVENTION

The present invention seeks to overcome all or some of the disadvantages of the prior art. To this end, the subject matter of the invention is an aircraft comprising a fuselage, a wing structure, at least one propulsion unit connected to the wing structure and distant from the fuselage, at least one turbomachine running on hydrogen and generating thrust at the propulsion unit, at least one fuel tank positioned in the fuselage, and configured to store hydrogen in the liquid and cryogenic state, and at least one hydrogen supply device connecting the turbomachine and the fuel tank, this hydrogen supply device comprising at least one pump connected to the fuel tank and positioned in the fuselage in the vicinity of the fuel tank as well as at least one hydrogen heating system positioned upstream of the turbomachine.

According to the invention, the hydrogen heating system is positioned in the fuselage in the vicinity of the pump or in the region of a junction connecting the fuselage and the wing structure.

This solution makes it possible to reduce the length of the complex double-walled pipes configured to carry the hydrogen in the cryogenic state between the fuel tank, the pump and the hydrogen heating system.

According to another feature, the hydrogen heating system is separated from the fuel tank by a distance less than 5 m.

According to another feature, the hydrogen heating system comprises at least a heat exchanger, at least an electrical heating system and/or at least a catalysis-heating system.

According to another feature, the hydrogen heating system comprises at least a heat exchanger through which a stream of air bled from outside the aircraft passes.

According to another feature, the hydrogen heating system comprises at least a heat exchanger configured to exchange heat energy between the hydrogen and a heat-transfer fluid coming from at least a source present in the aircraft.

According to another feature, the hydrogen heating system comprises at least a main heat exchanger configured to exchange heat energy between the hydrogen and an intermediate heat-transfer fluid passing through at least a secondary heat exchanger.

According to another feature, the hydrogen heating system comprises at least two main heat exchangers arranged in series and configured to exchange heat energy between the hydrogen and the one same intermediate heat-transfer fluid passing through at least one secondary heat exchanger.

According to another feature, the hydrogen heating system comprises a return circuit configured to tap off some of the heated hydrogen leaving the hydrogen heating system and reintroduce it into the inlet of the hydrogen heating system.

According to another feature, the propulsion unit comprises a multiblade propeller, and the turbomachine is positioned in the region of a junction connecting the fuselage and the wing structure, the aircraft comprising a mechanical drivetrain connecting the turbomachine and the multiblade propeller.

According to another feature, the turbomachine comprises a rotor which has an axis of rotation and it is positioned in such a way that this axis of rotation is parallel to a longitudinal axis of the fuselage.

According to another feature, the hydrogen supply device comprises a first double-walled pipe connecting the fuel tank and the pump and a second double-walled pipe connecting the pump and the hydrogen heating system.

According to another feature, the hydrogen supply device comprises a third double-walled pipe connecting the hydrogen heating system and the turbomachine.

According to another feature, the aircraft comprises propulsion units positioned on each side of the fuselage and connected to the wing structure, each propulsion unit being distant from the fuselage and comprising a turbomachine, said aircraft comprising a fuel tank common to said turbomachines and a hydrogen supply device for each turbomachine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to one embodiment visible inFIGS.2,9and10, an aircraft30comprises a fuselage32, a wing structure34and propulsion units36positioned on each side of the fuselage32and connected to the wing structure34. In the vicinity of the wing structure34, the fuselage32is approximately cylindrical and has a longitudinal axis A32parallel to the exterior wall of the fuselage32.

According to one configuration, the propulsion units36are positioned beneath the wing structure34. They are distant from the fuselage32. In other words, the propulsion units36are positioned some distance from the fuselage32, which is to say, there is a space between each propulsion unit36and the fuselage32.

According to an embodiment visible inFIG.2, each propulsion unit36comprises a nacelle38, a turbomachine40positioned in the nacelle38and having an output shaft A40, a multiblade propeller42positioned on the outside of the nacelle38and having a rotation shaft A42coupled to the output shaft A40of the turbomachine40. According to one configuration, the propulsion unit36comprises reduction gear44positioned inside the nacelle38and connecting the rotation shaft A42of the multiblade propeller42and the output shaft A40of the turbomachine40.

Since the turbomachine40runs on hydrogen, the aircraft30comprises at least one fuel tank46, positioned in the fuselage32and configured to store hydrogen in the liquid and cryogenic state, and a hydrogen supply device connecting the turbomachine40and the fuel tank46.

The fuel tank46has at least one outlet48. As an idea of scale, the hydrogen is at a pressure of the order of 3 bar and a temperature of the order of −243° C. at the outlet48of the fuel tank46.

In one configuration, the aircraft30comprises one fuel tank common to a plurality of turbomachines40and one hydrogen supply device for each turbomachine40. Of course, the invention is not limited to that configuration.

The hydrogen supply device comprises at least a pump50connected to the outlet48of the fuel tank46and at least one hydrogen heating system52upstream of the turbomachine40.

According to one embodiment, the pump50is a high pressure pump. In one arrangement, the pump50is positioned in the fuselage32in the vicinity of the outlet48of the fuel tank46. The pump50is positioned a short distance away from the outlet48of the fuel tank46, for example at a distance of 5 m or less. Because the hydrogen is in the liquid state when it is compressed, this arrangement makes it possible to reduce the energy needed for compressing the hydrogen. As an idea of scale, the hydrogen in the liquid and the cryogenic state is at a pressure of the order of 50 bar at the outlet of the pump50.

According to one particular feature of the invention, the hydrogen heating system52is positioned in the fuselage32in the vicinity of the pump50a short distance from the fuel tank46. What is meant by a short distance is that the hydrogen heating system52is separated from the fuel tank46by a distance of less than 5 m. The hydrogen heating system52is preferably separated from the fuel tank46by a distance of less than 5 m, but could of course be separated from the fuel tank46by a distance greater than 5 m.

According to another particular feature of the invention, the hydrogen heating system52is positioned in the region of a junction72connecting the fuselage32and the wing structure34, which is to say, at an interface between the fuselage32and the wing structure34(wing box) in the vicinity of the pump50, a short distance from the fuel tank46.

The hydrogen heating system52is configured so that the temperature of the hydrogen leaving it is an optimal temperature for the turbomachine40. Thus, on leaving the hydrogen heating system52, the hydrogen is in the gaseous state and no longer in the cryogenic state. As an idea of scale, the hydrogen is at a temperature of the order of 27° C. on leaving the hydrogen heating system52.

The hydrogen supply device comprises a first double-walled pipe54.1connecting the fuel tank46and the pump50, and a second double-walled pipe54.2connecting the pump50and the hydrogen heating system52. These first and second double-walled pipes54.1,54.2are configured to carry hydrogen in the liquid and cryogenic state. The cumulative length of the first and second double-walled pipes54.1,54.2is reduced and markedly shorter by comparison with the length of such walls of the prior art, thus limiting the increase in on-board mass.

The hydrogen supply device comprises a third pipe56connecting the hydrogen heating system52and the turbomachine40and configured to carry hydrogen in the gaseous state. The third pipe56is a double-walled pipe, different than the first and second double-walled pipes54.1,54.2, and simpler, having a mass per unit length that is markedly lower than that of the first and second double-walled pipes54.1,54.2. In addition, because this third pipe56does not carry a fluid in the cryogenic state, the risks of icing of the aircraft structures that support it are low.

The hydrogen supply device may comprise a combination of various hydrogen heating systems52.

According to another embodiment, the hydrogen heating system52comprises at least one heat exchanger58.

According to an embodiment visible inFIG.2, the hydrogen heating system comprises at least one heat exchanger58through which there passes a stream of air bled from outside the aircraft. The air stream is carried along a duct60connecting an air inlet62.1configured to bleed the air from outside the fuselage32and an air outlet62.2configured to eject the air to outside the fuselage32.

According to another embodiment, the hydrogen heating system52comprises at least one heat exchanger58configured to exchange heat energy between the hydrogen and a heat-transfer gas coming from at least a source present in the aircraft, such as hot air from a turbomachine40or from an auxiliary power unit (APU) and used, amongst other things, for air conditioning the cabin of the aircraft.

According to another embodiment, the hydrogen heating system52comprises at least one heat exchanger58configured to exchange heat energy between the hydrogen and a heat-transfer liquid coming from at least one source present in the aircraft, such as the oil from a turbomachine40or from an auxiliary power unit.

According to another embodiment, the hydrogen heating system52comprises at least one heat exchanger58configured to exchange heat energy between the hydrogen and an intermediate heat-transfer fluid coming from at least one other heat exchanger configured to exchange heat energy between the intermediate heat-transfer fluid and a heat-transfer fluid coming from at least one source present in the aircraft, such as hot air or oil coming from a turbomachine40or from an auxiliary power unit.

As illustrated inFIGS.3to8, the hydrogen heating system52comprises a combination of several heat exchangers.

According to one embodiment visible inFIG.3, the hydrogen heating system52comprises first and second heat exchangers58,58′ in series, the first heat exchanger58being configured to exchange heat energy between the hydrogen and a heat-transfer fluid, such as oil for example, coming from a turbomachine40or from an auxiliary power unit, the second heat exchanger58′ being configured to exchange heat energy between the hydrogen and a heat-transfer fluid, such as hot air for example, coming from a turbomachine40or from an auxiliary power unit. According to this embodiment, the hydrogen heating system52may comprise a return circuit configured to tap off some of the heated hydrogen at the outlet of the hydrogen heating system52and reintroduce the heated hydrogen to the inlet thereof.

According to a second embodiment visible inFIG.4, the hydrogen heating system52comprises three heat exchangers58,58′,58″ in series, a first heat exchanger58configured to exchange heat energy between the hydrogen and a heat-transfer fluid, such as oil for example, coming from a turbomachine40or from an auxiliary power unit, a second heat exchanger58′ configured to exchange heat energy between the hydrogen and a heat-transfer fluid, such as hot air for example, coming from a turbomachine40or from an auxiliary power unit, a third heat exchanger58″ configured to exchange heat energy between the hydrogen and a heat-transfer fluid coming from another heat source64of the aircraft. According to this embodiment, the hydrogen heating system52comprises a return circuit66configured to tap off some of the heated hydrogen leaving the hydrogen heating system52and reintroduce the heated hydrogen to the inlet thereof.

Of course, the invention is not restricted to three heat exchangers in series.

According to an embodiment visible inFIG.5, the hydrogen heating system52comprises first and second main heat exchangers58,58′ in series and first and second secondary heat exchangers68,68′. The first main heat exchanger58is configured to exchange heat energy between the hydrogen and a first intermediate heat-transfer fluid70coming from the first secondary heat exchanger68configured to exchange heat energy between the first intermediate heat-transfer fluid70and a heat-transfer fluid, such as oil for example, coming from a turbomachine40or from an auxiliary power unit. The second main heat exchanger58′ being configured to exchange heat energy between the hydrogen and a second intermediate heat-transfer fluid70′ coming from the second secondary heat exchanger68′ configured to exchange heat energy between the second intermediate heat-transfer fluid70′ and a heat-transfer fluid, such as hot air, coming from a turbomachine40or from an auxiliary power unit. According to one configuration, the hydrogen heating system comprises a return circuit66configured to tap off some of the heated hydrogen leaving the hydrogen heating system52and reintroduce it to the inlet thereof. In a variant, the hydrogen heating system52may comprise three or more main heat exchangers in series each coupled with a secondary heat exchanger. In this variant, a third main heat exchanger is configured to exchange heat energy between the hydrogen and a third intermediate heat-transfer fluid coming from a third secondary heat exchanger configured to exchange heat energy between the third intermediate heat-transfer fluid and a heat-transfer fluid coming from another heat source of the aircraft.

According to one embodiment visible inFIG.6, the hydrogen heating system52comprises a main heat exchanger58and first and second secondary heat exchangers68,68′ in series. The main heat exchanger58is configured to exchange heat energy between the hydrogen and an intermediate heat-transfer fluid70passing through the first and second secondary heat exchangers68,68′. The first secondary heat exchanger68is configured to exchange heat energy between the intermediate heat-transfer fluid70and a heat-transfer fluid, such as oil for example, coming from a turbomachine40or from an auxiliary power unit. The second secondary heat exchanger68′ is configured to exchange heat energy between the intermediate heat-transfer fluid70and a heat-transfer fluid, such as hot air for example, coming from a turbomachine40or from an auxiliary power unit. In one configuration, the hydrogen heating system52comprises a return circuit66configured to tap off some of the heated hydrogen leaving the main heat exchanger58and reintroduce it upstream of the latter.

In a variant, the hydrogen heating system52may comprise three secondary heat exchangers in series through which there passes an intermediate heat-transfer fluid70that passes through the main heat exchanger58. In this variant, a third secondary heat exchanger68is configured to exchange heat energy between the intermediate heat-transfer fluid and a heat-transfer fluid coming from another heat source of the aircraft.

According to an embodiment visible inFIG.7, the hydrogen heating system52comprises a first heat exchanger58configured to exchange heat energy between the hydrogen and an intermediate heat-transfer fluid70coming from a secondary heat exchanger68and a second heat exchanger58′ configured to exchange heat energy between the hydrogen and a heat-transfer fluid, such as hot air for example, coming from a turbomachine40or from an auxiliary power unit, the first and second heat exchangers58,58′ being arranged in series. The secondary heat exchanger68is configured to exchange heat energy between the intermediate heat-transfer fluid70and a heat-transfer fluid, such as oil for example, coming from a turbomachine40or from an auxiliary power unit. In one configuration, the hydrogen heating system52comprises a return circuit66configured to tap off some of the heated hydrogen leaving the hydrogen heating system52and reintroduce it to the inlet of the latter.

According to an embodiment visible inFIG.8, the hydrogen heating system52comprises at least two main heat exchangers58,58′ arranged in series and configured to exchange heat energy between the hydrogen and the one same intermediate heat-transfer fluid70passing through at least a secondary heat exchanger68. In one configuration, the hydrogen heating system52comprises first, second and third secondary heat exchangers68,68′,68″ arranged in series and through which there passes the intermediate heat-transfer fluid70which passes through the first and second main heat exchangers58,58′ in parallel. The first secondary heat exchanger68is configured to exchange heat energy between the intermediate heat-transfer fluid70and a heat-transfer fluid, such as oil for example, coming from a turbomachine40or from an auxiliary power unit. The second secondary heat exchanger68′ is configured to exchange heat energy between the intermediate heat-transfer fluid70and a heat-transfer fluid, such as hot air for example, coming from a turbomachine40or from an auxiliary power unit. The third secondary heat exchanger68″ is configured to exchange heat energy between the intermediate heat-transfer fluid70and a heat-transfer fluid coming from another heat source64of the aircraft.

The secondary heat exchanger or exchangers may be arranged in the nacelle38.

Of course, the invention is not restricted to these combinations of heat exchangers.

According to another embodiment, the hydrogen heating system52is an electrical heating system comprising at least one resistive electrical element powered by an electrical source, for example an electric battery or any other electrical source of the aircraft.

According to another embodiment, the hydrogen heating system52is a heating system employing catalysis, for example consuming hydrogen in order to produce heat.

Of course, the invention is not restricted to these embodiments of the hydrogen heating system52. Thus, the hydrogen heating system52comprises at least one heat exchanger, at least one electrical heating system and/or at least one catalysis heating system.

According to an embodiment illustrated inFIGS.9and10, the turbomachine40is not positioned in the nacelle38. The turbomachine40is positioned as close as possible to the fuselage32in the region of a junction72connecting the fuselage32and the wing structure34. The turbomachine40may, as the case may be, be positioned under, in or on the wing structure34.

According to one configuration, all the turbomachines40coupled to a multiblade propeller42are positioned on each side of the fuselage32in the junction regions72connecting the fuselage32and the wing structure34.

For each turbomachine40positioned in the junction region72connecting the fuselage32and the wing structure34and which is coupled to a multiblade propeller42, the aircraft comprises a mechanical driveline74connecting the turbomachine40and the multiblade propeller42and more particularly the reduction gearbox44coupled to the multiblade propeller42.

In one configuration, each mechanical driveline74comprises at least a transmission shaft74.1and a coupling mechanism74.2provided at each end of each transmission shaft74.1.

The act of positioning the turbomachine40or at least one turbomachine40in the junction region72connecting the fuselage32and the wing structure34means that the dimensions of the nacelle38and, more particularly, the cross section thereof (perpendicular to the rotation shaft A42of the multiblade propeller42) can be reduced, thereby contributing to improving the aerodynamic performance of the aircraft.

According to another advantage, that makes it possible to reduce the length of the double-walled pipes to the strict minimum, thereby contributing to reducing the risks of hydrogen leaks and to not increasing the on-board mass excessively.

According to one configuration, the turbomachine40or at least one turbomachine40comprises a rotor which has an axis of rotation76and it is positioned in such a way that this axis of rotation76is parallel to the longitudinal axis A32of the fuselage32. This configuration makes it possible to broaden the scope of options regarding the positioning of the fuel tanks46. However, the invention is not restricted to this configuration, it being possible for the turbomachine40to be positioned in such a way that the axis of rotation76of the rotor thereof is perpendicular to or inclined with respect to the longitudinal axis A32of the fuselage32.

The invention is not restricted to the embodiments described hereinabove. Whatever the embodiment, the aircraft comprises at least one turbomachine40generating thrust at a propulsion unit. In certain embodiments, the turbomachine40generates the thrust directly and is positioned in the propulsion unit. In other embodiments, the turbomachine40is coupled to a multiblade propeller incorporated into the propulsion unit and the turbomachine is positioned in the propulsion unit or spaced away therefrom.