Hydrogen storage system and aircraft comprising a hydrogen storage system

Abstract

The present disclosure relates to a hydrogen storage system and to an aircraft comprising a hydrogen storage system. The hydrogen storage system (10) comprises a hydrogen tank (12) and a system for controlling the evaporation of hydrogen within said tank. The control system comprises a hydrogen discharge pipe (18) connected on one hand to the hydrogen tank and on the other hand to a controllable valve (22), and a processing unit (16) configured to control the valve as a function of the pressure in the tank. The hydrogen storage system (10) further comprises a fuel cell (14) permanently connected to the hydrogen tank, and the processing unit is powered by the fuel cell.

Description

Technical Field

[0001] This invention relates to the field of hydrogen storage, and more specifically to its application in aircraft using electric propulsion systems powered by hydrogen. Background Technology

[0002] This system requires a liquid hydrogen tank to be installed on the aircraft to allow hydrogen to be supplied to fuel cells or hydrogen-powered propulsion engines. To maintain the liquid state in the tank, the hydrogen must be kept at a very low temperature of approximately -253°C. For this purpose, the hydrogen tank is equipped with very effective insulation. However, despite this insulation, some hydrogen will still evaporate from the tank. When the hydrogen from the tank is used to ensure the operation of the aircraft, especially its propulsion, this evaporation is not a problem because the evaporated hydrogen is used by the aircraft, for example, to power the fuel cells or hydrogen-powered engines. However, when the aircraft is parked on the ground, the fuel cells or hydrogen-powered engines are no longer used to operate the aircraft and therefore no longer consume hydrogen. As a result, the pressure in the tank increases due to the aforementioned hydrogen evaporation. However, to ensure the integrity of the tank and prevent it from exploding, the pressure inside the tank needs to be limited to a value lower than the maximum pressure, for example, approximately 850 bar.

[0003] One solution envisioned by the inventors to this problem involves installing a pressure monitoring system inside the tank. This system would control the opening of a valve when the pressure inside the tank becomes too high, releasing some of the hydrogen contained within the tank into the atmosphere, thereby allowing the pressure inside the tank to decrease. However, for operation, this monitoring system must be powered, for example, by an electric power source. The aircraft may no longer be powered by the fuel cells used to propel it, as these fuel cells are shut down when the aircraft is parked on the ground. A first solution might involve powering this monitoring system via batteries. However, this solution is difficult to implement safely because it requires ensuring that the battery capacity allows for powering the monitoring system as long as the hydrogen tank is not empty. A second solution might involve powering the monitoring system via a ground-based power source, such as a "ground power unit" located at the airport where the aircraft is docked. However, this solution makes the aircraft dependent on available ground-based equipment, which could lead to management difficulties when the airport lacks suitable power. Summary of the Invention

[0004] The specific objective of this invention is to provide a solution to this problem. This invention relates to a hydrogen storage system, comprising a hydrogen tank and a system for controlling hydrogen evaporation within the hydrogen tank, the control system comprising:

[0005] - A hydrogen emission pipe, which is connected on one side to the hydrogen tank and on the other side to a controllable valve; and

[0006] - A processing unit configured to control the valve based on the pressure in the tank to ensure that the pressure value in the hydrogen tank does not exceed a first predetermined pressure threshold.

[0007] It is worth noting that the hydrogen storage system further includes a fuel cell permanently connected to the hydrogen tank so as to generate electricity permanently as long as there is hydrogen in the tank, and the processing unit is powered by the fuel cell.

[0008] Therefore, since the fuel cell is permanently connected to the hydrogen tank, hydrogen is supplied to the fuel cell indefinitely as long as there is hydrogen in the tank. Thus, as long as there is hydrogen in the tank, the fuel cell generates electricity to power the processing unit. This allows for automatic power supply to the hydrogen evaporation control system, and thus ensures that the hydrogen evaporation control system operates as long as there is hydrogen in the tank. Furthermore, consuming hydrogen from the tank to power the fuel cell increases the time before the hydrogen tank needs to be depressurized via a control valve.

[0009] In one embodiment, the hydrogen emission pipe differs at least slightly from the pipe connecting the fuel cell to the hydrogen tank. Specifically, the controllable valve does not form part of the hydrogen supply loop for the fuel cell. Advantageously, a first end of the emission pipe is connected to the hydrogen tank, while a second end of the emission pipe is configured to release hydrogen from the hydrogen tank into the environment when the controllable valve is open, the controllable valve being mounted in series on the emission pipe between the first and second ends. The invention also relates to aircraft comprising the hydrogen storage system described above.

[0010] According to various embodiments that can be considered individually or in combination:

[0011] - The aircraft includes a propulsion system powered by hydrogen from the hydrogen storage system;

[0012] - The propulsion system includes an engine that operates by burning hydrogen from the hydrogen storage system;

[0013] - The propulsion system includes an electric motor powered by a fuel cell assembly that supplies hydrogen via a hydrogen storage system;

[0014] - The fuel cell of the hydrogen storage system forms part of the fuel cell assembly that powers the electric motor;

[0015] - The fuel cell of the hydrogen storage system is independent of the fuel cell assembly that powers the electric motor;

[0016] - The aircraft includes circuitry configured to power the electric motor via the fuel cell of the hydrogen storage system, and also to supply power to the electric motor via the fuel cell assembly;

[0017] -The aircraft further includes: a non-propulsion system, which is normally powered by the aircraft's onboard power source, referred to as the main power source; the fuel cell and the fuel cell assembly, which are independent of the hydrogen storage system; and circuitry configured to supply power to the non-propulsion system via the fuel cell of the hydrogen storage system, particularly when the main power source fails during flight.

[0018] - The aircraft includes an electrical system and circuitry separate from the processing unit, the circuitry being configured to supply power to the electrical system via the fuel cell of the hydrogen storage system when the aircraft is stationary on the ground;

[0019] - The electrical system corresponds to a system for heating at least one of the fuel cells in the fuel cell assembly;

[0020] The aircraft includes circuitry configured to allow external electrical systems to be connected to the aircraft when it is parked on the ground, and to power the electrical systems via the fuel cell of the hydrogen storage system.

[0021] The present invention also relates to an assembly comprising an aircraft and a hydrogen storage system as described above, wherein the hydrogen tank is mounted on the aircraft and the fuel cell of the hydrogen storage system is mounted in a unit located outside the aircraft, the unit being intended to be connected to the aircraft via a detachable hydrogen pipe and detachable electrical connections. Attached Figure Description

[0022] The invention will be better understood by reading the following description and referring to the accompanying drawings.

[0023] Figure 1 A hydrogen storage system according to an embodiment of the present invention is illustrated schematically.

[0024] Figure 2 An aircraft equipped with a hydrogen storage system was showcased.

[0025] Figure 3 A hydrogen storage system according to an embodiment of the present invention is schematically shown, which is connected to an aircraft propulsion system.

[0026] Figure 4 An alternative embodiment of a hydrogen storage system connected to an aircraft propulsion system is demonstrated.

[0027] Figure 5 A specific embodiment of a hydrogen storage system connected to an aircraft propulsion system is illustrated schematically.

[0028] Figure 6This schematically illustrates another specific embodiment of a hydrogen storage system connected to an aircraft propulsion system.

[0029] Figure 7 This schematically illustrates another specific embodiment of a hydrogen storage system connected to an aircraft propulsion system.

[0030] Figure 8 The illustration schematically demonstrates a specific mode of integrating the hydrogen storage system according to the invention with an aircraft. Detailed Implementation

[0031] exist Figure 1 The hydrogen storage system 10 shown includes a hydrogen tank 12 (labeled "H2" in the figure), a fuel cell 14 (labeled "FC" in the figure), a processing unit 16 (labeled "Proc" in the figure), and a pipe 18 to which a controllable valve 22 is mounted in series. A first end of the pipe 18 is connected to the hydrogen tank 12. A second end of the pipe 18 is configured to release hydrogen from the hydrogen tank 12 into the atmosphere when the controllable valve 22 is opened. The fuel cell 14 is permanently connected to the hydrogen tank 12 via a pipe 21, such that the fuel cell 14 can generate electricity as long as the tank 12 contains hydrogen. The processing unit 16 is connected to the fuel cell 14 via a circuit 24 configured to allow the processing unit 16 to be powered by the fuel cell 14. The output of the processing unit 16 is also connected via a link 26 to the control input of the valve 22, allowing the processing unit 16 to control the opening or closing of the valve 22. Advantageously, the input of the processing unit 16 is also connected via a link 23 to a pressure sensor 25. Pressure sensor 25 is mounted to allow measurement of the pressure of hydrogen in hydrogen tank 12. According to a first alternative embodiment, pressure sensor 25 is mounted in hydrogen tank 12. According to another alternative embodiment, pressure sensor 25 is mounted in a hydrogen pipe connected to the hydrogen tank. For example, processing unit 16 includes a microprocessor or microcontroller.

[0032] In a specific embodiment, the hydrogen tank 12 is mounted on an aircraft, such as... Figure 2 The aircraft 1 is shown. Then, the hydrogen tank 12 is connected to the aircraft propulsion system 3, for example, through a pipe 20, in such a way that the propulsion system 3 is powered by hydrogen from the hydrogen tank 12.

[0033] The hydrogen storage system operates as follows. As long as hydrogen tank 12 contains hydrogen, fuel cell 14 receives hydrogen from the tank via pipe 21 in a manner that enables the fuel cell to permanently generate electricity. Therefore, as long as hydrogen tank 12 contains hydrogen, processing unit 16, electrically connected to fuel cell 14 via circuit 24, is permanently powered. This ensures that processing unit 16 operates as long as hydrogen tank 12 contains hydrogen. Processing unit 16 controls the opening or closing of valve 22 based on the pressure within hydrogen tank 12. In one embodiment, when the pressure is greater than or equal to a first predetermined pressure threshold, processing unit controls valve 22 to open, and when the pressure is less than or equal to a second predetermined pressure threshold, which is lower than the first pressure threshold, processing unit controls valve 22 to close. Therefore, when the pressure inside the tank reaches the first predetermined pressure threshold due to hydrogen evaporation, valve 22 is opened to allow a portion of the hydrogen contained in the tank to be released as gas through pipe 18. This portion of hydrogen is thus released into the atmosphere, causing the pressure inside the hydrogen tank to decrease. The pressure inside the tank thus decreases until it reaches the second predetermined pressure threshold. Then, the processing unit 16 controls valve 22 to close, stopping the release of hydrogen into the atmosphere. This operation ensures that the pressure inside the hydrogen tank does not exceed a first predetermined pressure threshold. For this purpose, the processing unit uses, for example, a pressure value obtained from pressure sensor 25 as this pressure value. Preferably, the processing unit repeatedly monitors this pressure, for example, at a cycle of approximately 1 second. The value of the first pressure threshold is selected, for example, in the range of [5 bar; 25 bar], such as 10 bar, while the value of the second predetermined pressure threshold is selected, for example, in the range of [5 bar; 10 bar], such as 5 bar.

[0034] In one embodiment, when the hydrogen storage system 10 is connected to the propulsion system 3, the propulsion system 3 includes an engine that operates by burning hydrogen from the hydrogen storage system 10 via a pipe 20.

[0035] exist Figure 3 In another embodiment shown, the propulsion system 3 includes a fuel cell assembly 34 electrically connected to at least one electric motor 32 via a set of electrical links 33. A propulsion propeller 30 is mechanically coupled to the electric motor 32. The input end of the fuel cell of the fuel cell assembly 34 is connected to a hydrogen storage system 10 via a pipe 20. The propulsion system 3 further includes a controller, which is not... Figure 3 As shown in the diagram. To enable the propulsion system 3 to operate, the controller controls the supply of hydrogen to the fuel cell assembly 34, for example, by controlling the opening of a valve mounted in series on the pipe 20. The fuel cell then generates electricity, thereby allowing the motor 32 to be powered, which in turn rotates the propulsion propeller 30.

[0036] exist Figure 4In the alternative embodiment shown, the fuel cell 14 of the hydrogen storage system forms part of the fuel cell assembly 34 that powers the electric motor 32. As in Figure 3 In the illustrated embodiment, fuel cell 14 is permanently connected to a hydrogen tank via pipe 21. Other fuel cells in fuel cell assembly 34 are supplied with hydrogen via pipe 20. As previously indicated, this hydrogen supply is controlled by the controller of propulsion system 3. The electrical output of fuel cell 14 supplies power to processing unit 16 via electrical link 24.

[0037] Specifically, the aircraft includes circuitry configured to power an electric motor 32 via a fuel cell 14 of a hydrogen storage system 10, and also via a fuel cell assembly 34. Figure 5 In the example shown, the circuit includes an electrical connector 24a and a contactor 28a mounted in series on the connector. A first end of the connector 24a is connected to the electrical output of the fuel cell 14, and a second end is connected to the electric motor 32 or to a controller of the motor. The contactor 28a is controlled by a controller of the propulsion system 3. For example, during high-power operation phases of the propulsion system 3, particularly during aircraft takeoff, the controller closes the contactor 28a. This avoids making the fuel cell assembly 34 too large to allow for a single supply of maximum power during takeoff.

[0038] In another specific way, such as Figure 6 As shown, the aircraft further includes a non-propulsion system 29b (labeled "S" in the figure), which is normally powered by an onboard power source (not shown), referred to as the main power source, independent of the fuel cell 14 and fuel cell assembly 34 of the hydrogen storage system. The aircraft also includes circuitry configured to supply power to the non-propulsion system 29b via the fuel cell 14 of the hydrogen storage system 10, particularly in the event of a main power failure during flight. This circuitry includes an electrical link 24b located between the electrical output of the fuel cell 14 and the non-propulsion system 29b, and a contactor 28b mounted in series on this electrical link. The contactor 28b is controlled, for example, by the aircraft's electrical core (not shown) to close in the event of a main power failure.

[0039] In another specific way, such as Figure 7As shown, the aircraft further includes an electrical system 29c (labeled "R" in the figure), separate from the processing unit 16, and circuitry configured to power the electrical system via the fuel cell of the hydrogen storage system when the aircraft is stationary on the ground. This circuitry includes an electrical link 24c located between the electrical output of the fuel cell 14 and the electrical system 29c, and a contactor 28c mounted in series on the electrical link. The electrical system 29c is, for example, a heating system for the fuel cell assembly 34 of the propulsion system 3, as indicated by arrow "F" in the figure. The contactor 28c is controlled by the processing unit 16, for example, via link 25c, to close when the fuel cell of the fuel cell assembly 34 must be heated while the aircraft is stationary on the ground.

[0040] In an alternative embodiment, electrical system 29c is an external electrical system of the aircraft. In this case, electrical connector 28c includes an electrical socket mounted on the aircraft (e.g., attached to a wall of the aircraft fuselage 2) and a detachable cable that connects the electrical socket to electrical system 29c when the aircraft is parked on the ground.

[0041] exist Figure 8 In the specific embodiment shown, the hydrogen storage system 10 is partially mounted on the aircraft 1. In fact, the fuel cell 14 is external to the aircraft, for example, mounted on a service vehicle at the airport where the aircraft is docked. An electrical socket Pe and a hydrogen pipe connector Ph are mounted on the aircraft, for example, attached to the aircraft fuselage 2. A wire 24 extends between the electrical socket Pe and the processing unit 16. A hydrogen pipe 21 extends between the hydrogen tank 12 and the hydrogen pipe connector Ph. When the aircraft is parked on the ground, a detachable hydrogen pipe 21a connected to the fuel cell 14 is connected to the hydrogen pipe connector Ph, while a detachable cable 24e connected to the electrical output of the fuel cell 14 is connected to the electrical socket Pe. This specific embodiment has the advantage that the fuel cell 14 does not need to be transported during the flight phase of the aircraft, which allows for a reduction in aircraft weight and thus a reduction in the energy consumption required to propel the aircraft.

Claims

1. An aircraft comprising a hydrogen storage system (10) or said hydrogen storage system (10) partially mounted on the aircraft, said hydrogen storage system (10) comprising a hydrogen tank (12) and a system for controlling hydrogen evaporation within said hydrogen tank, said system for controlling hydrogen evaporation within said hydrogen tank comprising: - Hydrogen emission pipe (18), which is connected to the hydrogen tank on one side and to the controllable valve (22) on the other side; as well as - Processing unit (16), the processing unit being configured to control the valve based on the pressure in the hydrogen tank to ensure that the pressure value in the hydrogen tank does not exceed a first predetermined pressure threshold. The hydrogen storage system is characterized in that it further includes a fuel cell (14) permanently connected to the hydrogen tank so as to permanently generate electricity as long as hydrogen remains in the tank, even when the aircraft is stationary on the ground, and the processing unit is powered by the fuel cell. The aircraft includes a propulsion system (3) powered by hydrogen from the hydrogen storage system (10). The propulsion system includes an engine or electric motor (32), the engine being operated by combustion of hydrogen from the hydrogen storage system, and the electric motor being powered by a fuel cell assembly (34) supplied with hydrogen through the hydrogen storage system (10). The fuel cell (14) of the hydrogen storage system (10) is independent of the fuel cell assembly (34) that powers the electric motor.

2. The aircraft according to claim 1, characterized in that, The aircraft includes circuits (24a, 28a) configured to power the electric motor (32) via the fuel cell (14) of the hydrogen storage system (10), and also to supply power to the electric motor via the fuel cell assembly (34).

3. The aircraft according to claim 1, characterized in that, The aircraft further includes: a non-propulsion system (29b) which is normally powered by the aircraft's onboard power source, referred to as the main power source; the fuel cell (14) and the fuel cell assembly (34) which are independent of the hydrogen storage system (10); and circuits (24b, 28b) configured to supply power to the non-propulsion system (29b) via the fuel cell (14) of the hydrogen storage system in the event of a failure of the main power source while the aircraft is in flight.

4. The aircraft according to any one of claims 1 to 3, characterized in that, The aircraft includes an electrical system (29c) and circuits (24c, 28c) separate from the processing unit (16), the circuits being configured to supply power to the electrical system via the fuel cell (14) of the hydrogen storage system (10) when the aircraft is stationary on the ground.

5. The aircraft according to claim 4, characterized in that, The electrical system (29c) corresponds to a system for heating at least one of the fuel cells in the fuel cell assembly (34).

6. The aircraft according to any one of claims 1 to 3, characterized in that, The aircraft includes circuitry configured to allow external electrical systems to be connected to the aircraft when it is parked on the ground, and to power the electrical systems via the fuel cell (14) of the hydrogen storage system (10).

7. A component comprising the aircraft (1) according to claim 1, characterized in that, The hydrogen tank (12) is installed on the aircraft and the fuel cell (14) of the hydrogen storage system is installed in a unit located outside the aircraft, the unit being designed to be connected to the aircraft via a detachable hydrogen pipe (21a) and a detachable electrical connector (24e).

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