HYDROGEN TANK ASSEMBLY FOR A VEHICLE, SUCH AS AN AIRCRAFT

Abstract

A hydrogen tank assembly is provided for use in vehicles, such as aircraft. The hydrogen tank assembly has an inner tank wall, an outer tank wall, and an inert gas source. The inner tank wall defines a hydrogen tank volume that is surrounded by a shroud volume which is defined by the outer tank wall. The hydrogen tank volume is filled with cryogenic hydrogen and has a higher pressure than the shroud volume that is filled with an inert gas, such as helium. The counter-pressure of the inert gas prevents micro-cracks in the inner tank wall and increases the in-service life.

Claims

1. A hydrogen tank assembly for a vehicle, the hydrogen tank assembly comprising: an inner tank wall that defines a hydrogen tank volume configured to store cryogenic hydrogen at a predetermined hydrogen pressure; an outer tank wall that defines a shroud volume which surrounds the inner tank wall; and an inert gas source that is fluidly connected to the shroud volume and configured to pressurize the shroud volume with an inert gas to an inert gas pressure that is smaller than the hydrogen pressure.

2. The hydrogen tank assembly according to claim 1, further comprising an inner tank wall cover that is at least one of configured to allow the inert gas to pass towards the inner tank wall for flushing hydrogen or configured as a thermal insulation.

3. The hydrogen tank assembly according to claim 2, wherein the inner tank wall cover is made of a material chosen from a group of materials consisting of open porous foam material, perforated honeycomb material, dry fiber layer material, thermal insulation material having channels.

4. The hydrogen tank assembly according to claim 1, wherein the inert gas source is fluidly connected by an inert gas supply line, the inert gas supply line having an end portion for discharging the inert gas, and the end portion is arranged at least one of adjacent to the inner tank wall or within the tank wall cover.

5. The hydrogen tank assembly according to claim 1, wherein the inner tank wall is configured as a liner.

6. The hydrogen tank assembly according to claim 1, wherein the inner tank wall is made of at least one of a mono-resin material or of a fiber composite material.

7. The hydrogen tank assembly according to claim 1, wherein the inner tank wall comprises at least one compensation member configured to reduce or prevent thermal shrinkage of at least one of the inner tank wall or an inner tank wall cover.

8. The hydrogen tank assembly according to claim 7, wherein the compensation member is configured to reduce or prevent relative shrinkage between the inner tank wall and the inner tank wall cover.

9. The hydrogen tank assembly according to claim 1, further comprising a main hydrogen line that is configured to allow a main hydrogen consumer to be supplied with hydrogen from the hydrogen tank volume.

10. The hydrogen tank assembly according to claim 1, further comprising at least one leakage line that is arranged to collect hydrogen that has leaked from the hydrogen tank volume into the shroud volume.

11. The hydrogen tank assembly according to claim 10, wherein the leakage line comprises a leakage sensor configured to determine a leak rate of the hydrogen.

12. The hydrogen tank assembly according to claim 10, wherein the leakage line comprises a check valve.

13. The hydrogen tank assembly according to claim 1, further comprising at least one auxiliary hydrogen line that is arranged for allowing an auxiliary hydrogen consumer to be supplied with hydrogen from the hydrogen tank volume.

14. The hydrogen tank assembly according claim 13, wherein the auxiliary hydrogen line is fluidly connected to the at least one leakage line.

15. An aircraft comprising at least one engine and a hydrogen tank assembly according to claim 1, wherein the engine is supplied with hydrogen from the hydrogen tank volume.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The FIGURE schematically shows an embodiment of a hydrogen tank assembly in an aircraft.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] Embodiments of the invention are described in more detail with reference to the accompanying schematic drawings. Therein, the only FIGURE depicts an embodiment of a hydrogen tank assembly 10 for a vehicle 100, such as an aircraft, according to the invention.

[0036] The hydrogen tank assembly 10 comprises a hydrogen tank volume 12 for cryogenic hydrogen. The hydrogen can be stored therein at cryogenic temperatures and with a hydrogen pressure of preferably 3 bar or slightly above. Under these conditions the hydrogen is generally a liquid that boils of hydrogen gas.

[0037] The hydrogen tank assembly 10 includes an inner tank wall 14 that defines the hydrogen tank volume 12. The inner tank wall 14 is made of a thin thermoplastic resin layer. The inner tank wall 14 includes a plurality of compensation members 16. The compensation members 16 may be disposed on the outer circumferential surface of the inner tank wall 14 and extend in an axial direction of the inner tank wall 14. The compensation members 16 are preferably configured to prevent thermal shrinkage of the inner tank wall 14. The compensation members 16 may be made of an elastic meta-material, which are known per se.

[0038] The hydrogen tank assembly 10 has an inner tank wall cover 18. The inner tank wall cover 18 may be configured as a thermal insulation 20. The inner tank wall cover 18 is configured to allow an inert gas, such as helium, to pass through the inner tank wall cover 18 and flush hydrogen that leaked out of the hydrogen tank volume 12 away from the inner tank wall 14. The inner tank wall cover 18 can be made of open porous foam, perforated material, or dry fiber material.

[0039] The thermal insulation 20 may also include a glass sphere material that is known in the field of cryogenics. The glass sphere material is usually a bulk material comprising a plurality of microscopic glass spheres. The glass spheres enclose a vacuum. The glass sphere material may be arranged within preformed chambers, such as those of a honeycomb structure or the like. The vacuum in the glass spheres provides excellent thermal insulation while the “porosity” of the glass sphere material allows sufficient gas movement.

[0040] It is also possible that the tank wall cover 18 and/or the thermal insulation 20 has a plurality of channels. The channels are preferably configured in plane of the respective tank wall cover 18 or thermal insulation 20 such that the tank wall cover 18 and/or the thermal insulation 20 are divided into a plurality of sections. The extent of the sections along parallel to the inner tank wall 14 is determined by the pressure differential between the inner tank volume 12 and the shroud volume 24 (see below) such that the pressure drop of hydrogen passing through the tank wall cover 18 or thermal insulation 20 does not exceed the pressure differential.

[0041] The hydrogen tank assembly 10 comprises an outer tank wall 22 (also called outer tank skin). The outer tank wall 22 surrounds the inner tank wall 14 and defines a shroud volume 24. The shroud volume 24 can be pressurized with an inert gas, such as helium, having a predetermined inert gas pressure. The inert gas pressure is chosen to be slightly smaller than the hydrogen pressure, e.g., 10 mbar less than the hydrogen pressure.

[0042] The hydrogen tank assembly 10 includes an inert gas source 26 that stores and pressurizes the inert gas. The inert gas source 26 is fluidly connected to the shroud volume 24 via an inert gas supply line 28. The inert gas supply line 28 has an end portion 30 for discharging the inert gas. The end portion 30 is arranged in the vicinity of the inner tank wall 14 or within the inner tank wall cover 18.

[0043] The hydrogen tank assembly 10 includes a main hydrogen line 32 that fluidly connects to a main hydrogen consumer 34, such as an aircraft engine 102. The main hydrogen line 32 is configured for supplying the main hydrogen consumer 34 with hydrogen.

[0044] The hydrogen tank assembly 10 includes an auxiliary hydrogen line 36. The auxiliary hydrogen line 36 includes a selector valve 38. The selector valve 38 allows the auxiliary hydrogen line 36 to fluidly connect to multiple outputs. The auxiliary hydrogen line 36 can fluidly connect to the environment for discharging excess hydrogen, to the main hydrogen line 32 or to a fuel cell 40. A check valve may be installed where needed, in order to avoid back flow.

[0045] The hydrogen tank assembly 10 has a leakage line 42. The leakage line 42 fluidly connects the shroud volume 24 to the auxiliary hydrogen line 36 via a check valve 44. The leakage line 42 collects hydrogen that has leaked through the inner tank wall 14. The leakage line 42 has an end portion 46 that is arranged in the vicinity of the inner tank wall 14 or within the inner tank wall cover 18. The leakage line 42 may include a leakage sensor 48 that is arranged downstream from the end portion 46, preferably adjacent to the check valve 44.

[0046] The fuel cell 40 may be supplied with a mixture of hydrogen and helium via the auxiliary hydrogen line 36. The fuel cell 40 transforms hydrogen and oxygen in a manner known into electrical energy and water. The inert gas does not react. The fuel cell 40, therefore, also acts as an inert gas separator 50 that is configured for separating the inert gas from the hydrogen. The fuel cell 40 is also capable of generating a pressure that causes hydrogen or a mixture of hydrogen and the inert gas to flow from the tank volume 12 or shroud volume 24, respectively, toward the fuel cell 40. The fuel cell 40 may thus act as a pump without moving parts.

[0047] The hydrogen tank assembly 10 includes a recirculation line 52 that fluidly connects the inert gas separator 50 with the inert gas source 26, so as to recirculate the inert gas back into the system.

[0048] In order to improve hydrogen tanks for use in vehicles, such as aircraft, the invention proposes a hydrogen tank assembly 10. The hydrogen tank assembly 10 has an inner tank wall 14, an outer tank wall 22, and an inert gas source 26. The inner tank wall 14 defines a hydrogen tank volume 12 that is surrounded by a shroud volume 24 which is defined by the outer tank wall 22. The hydrogen tank volume 12 is filled with cryogenic hydrogen and has a higher pressure than the shroud volume 24 that is filled with an inert gas, such as helium. The counter-pressure of the inert gas prevents micro-cracks in the inner tank wall 14 and increases the in-service life.

[0049] 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.

LIST OF REFERENCE SIGNS

[0050] hydrogen tank assembly [0051] hydrogen tank volume [0052] inner tank wall [0053] compensation member [0054] inner tank wall cover [0055] thermal insulation [0056] outer tank wall [0057] shroud volume [0058] inert gas source [0059] inert gas supply line [0060] end portion [0061] main hydrogen line [0062] main hydrogen consumer [0063] auxiliary hydrogen line [0064] selector valve [0065] fuel cell [0066] leakage line [0067] check valve [0068] end portion [0069] leakage sensor [0070] inert gas separator [0071] recirculation line