Purge system for hydrogen fuel system

Abstract

A hydrogen fuel system includes a fuel delivery assembly, a purge gas source, and a vent. The fuel delivery assembly is configured to receive hydrogen fuel from a hydrogen fuel source and provide the hydrogen fuel from the hydrogen fuel source to a power generator. The purge gas source is fluidly coupled to the fuel delivery assembly and configured to provide a purge gas to the fuel delivery assembly. The vent is fluidly coupled to the fuel delivery assembly and configured to vent the hydrogen fuel from the fuel delivery assembly when the purge gas is provided to the fuel delivery assembly.

Description

Technical Field

[0001] This disclosure relates to fuel systems, and more particularly to fuel systems for aircraft, wherein the fuel system is a hydrogen fuel system. Background Technology

[0002] Propulsion systems for commercial aircraft typically include one or more aircraft engines, such as turbofan jet engines. These engines can be powered by aviation turbine fuel, which is typically a combustible hydrocarbon liquid fuel with a desired carbon number and hydrocarbon ratio, such as kerosene-based fuel. This fuel produces carbon dioxide when burned, and improvements are needed to reduce or eliminate this carbon dioxide emission in commercial aircraft. Attached Figure Description

[0003] The features and advantages of this disclosure will become apparent from the following description of various exemplary embodiments, as illustrated in the accompanying drawings, wherein the same reference numerals generally denote the same, functionally similar and / or structurally similar elements.

[0004] Figure 1 This is a schematic perspective view of an aircraft with a hydrogen fuel system according to an embodiment of the present disclosure.

[0005] Figure 2 yes Figure 1 The gas turbine engine of the aircraft shown in the figure Figure 1 A schematic cross-sectional view taken along the centerline 2-2.

[0006] Figure 3 This is a schematic diagram of a fuel system including a hydrogen fuel purging system according to an embodiment of the present disclosure.

[0007] Figure 4 This is a schematic diagram of a fuel system with a carburetor replacement arrangement.

[0008] Figure 5A , 5B Figures 5C and 5C are schematic diagrams of fuel systems, each with a further carburetor arrangement.

[0009] Figure 6 This is a schematic diagram of a fuel system with multiple emission connections and purging sources.

[0010] Figure 7 This is a schematic cross-sectional view of a double-walled tube that can be used as part of a fuel system.

[0011] Figure 8 This is a schematic cross-sectional view of a three-walled tube that can be used as part of a fuel system. Detailed Implementation

[0012] The features, advantages, and embodiments of this disclosure will be set forth or apparent from consideration of the following detailed description, accompanying drawings, and claims. Furthermore, it should be understood that the following detailed description is exemplary and intended to provide further explanation without limiting the scope of the claimed disclosure.

[0013] Various embodiments are discussed in detail below. Although specific embodiments are discussed, they are for illustrative purposes only. Those skilled in the art will recognize that other components and configurations can be used without departing from the spirit and scope of this disclosure.

[0014] As used herein, the terms “first,” “second,” and “third” are used interchangeably to distinguish one component from another and are not intended to indicate the location or importance of the individual components.

[0015] The terms "front" and "rear" refer to relative positions within a gas turbine engine or vehicle, and specifically to the normal operating posture of the gas turbine engine or vehicle. For example, in the case of a gas turbine engine, "front" refers to the position closer to the engine inlet, while "rear" refers to the position closer to the engine nozzle or exhaust port.

[0016] The terms "upstream" and "downstream" refer to the relative directions of fluid flow within a fluid path. For example, "upstream" refers to the direction from which the fluid flows, and "downstream" refers to the direction from which the fluid flows.

[0017] The terms "direct upstream" or "direct downstream" when used to describe the relative positions of components in a fluid path refer to components placed adjacent to each other in the fluid path without any intermediate components between them, except for appropriate fluid connections, such as pipes, tubes, valves, etc., to fluidly connect the components. These components may be spaced apart from each other by intermediate components that are not in the fluid path.

[0018] The terms “connection,” “fixation,” “attachment,” “linkage,” etc., refer to direct connection, fixation, attachment, or linking, as well as indirect connection, fixation, attachment, or linking through one or more intermediate parts or features, unless otherwise stated herein.

[0019] The singular forms “one,” “a,” and “the” include plural references unless the context clearly indicates otherwise.

[0020] As used throughout this specification and claims, approximate language is applied to modify any quantitative expression that allows for variation without altering its underlying function. Therefore, values ​​modified by one or more terms such as “approximately,” “about,” and “substantially” are not limited to specified exact values. In at least some cases, approximate language may correspond to the precision of the instrument used to measure the value, or the precision of the method or machine used to construct or manufacture the component and / or system. For example, approximate language may refer to a margin of one percent, two percent, four percent, ten percent, fifteen percent, or twenty percent at the endpoints of a single value, a range of values, and / or a defined range of values.

[0021] Scope limitations are combined and interchanged herein and throughout the specification and claims. Unless the context or language otherwise indicates, such scopes are identified and include all subscopes contained herein. For example, all scopes disclosed herein include endpoints, and endpoints may be combined independently of each other.

[0022] Hydrogen fuel can be used to reduce carbon dioxide emissions from commercial aircraft. However, hydrogen fuel presents several challenges compared to flammable liquid hydrocarbon fuels. For example, hydrogen fuel has a relatively low boiling point, and its power density is much lower in its gaseous form. Hydrogen fuel, when in gaseous form, also tends to permeate through materials and joints between components without leaving residue. Hydrogen fuel is colorless and odorless. It also exhibits high reactivity (relative to other fuels, such as Jet-A fuel) and a wide range of flammability limits.

[0023] This disclosure discusses methods for improving the use of hydrogen fuel systems, particularly those used in aircraft. Various embodiments described herein and illustrated in the figures depict a hydrogen fuel purging system that can be used to actively purge fuel lines, fittings, valves, sensors, and hydrogen-receiving components in the event of a leak. The purging can be immediately removed and discharged from the outside.

[0024] The hydrogen fuel systems discussed in this article include hydrogen fuel purging systems that are particularly suitable for use on aircraft. Figure 1 This is a perspective view of an aircraft 10 that can be implemented in various preferred embodiments. The aircraft 10 includes a fuselage 12, a pair of wings 14 attached to the fuselage 12, and a tail 16. The aircraft 10 also includes a propulsion system that generates the thrust required to propel the aircraft 10 during flight, taxiing operations, etc. Figure 1 The propulsion system of the aircraft 10 shown includes a pair of engines 100. In this embodiment, each engine 100 is attached to one of the wings 14 in an underwing configuration via a pylon 18. Although the engines 100 are... Figure 1The engine 100 is shown attached to the wing 14 in an underwing configuration, but in other embodiments, the engine 100 may have an alternative configuration and be coupled to other parts of the aircraft 10. For example, the engine 100 may additionally or alternatively include one or more aspects coupled to other parts of the aircraft 10, such as, for example, the tail 16 and the fuselage 12.

[0025] The following will be a reference Figure 2 To be further described, Figure 1 The engine 100 shown is a gas turbine engine, which is capable of selectively generating propulsive thrust for the aircraft 10. The amount of propulsive thrust can be at least partially based on the thrust generated via fuel system 200 (see fuel system 200). Figure 3 The volume of fuel supplied to the gas turbine engine 100 is controlled. In the embodiment discussed herein, the fuel is hydrogen fuel stored in the fuel tank 210 of the fuel system 200. Figure 1 As shown, at least a portion of the fuel tank 210 is located within the fuselage 12, and in this embodiment, it is entirely located within the fuselage 12. However, the fuel tank 210 may be located in other suitable locations within the fuselage 12 or the wing 14, for example, a portion of the fuel tank 210 may be located within the fuselage 12 and a portion of the fuel tank 210 may be located within the wing 14. Alternatively, the fuel tank 210 may also be entirely located within the wing 14. Figure 1 In the illustrated embodiment, a single fuel tank 210 is used, and the fuel tank 210 is located within the fuselage such that it is positioned relative to the wing's center of lift in both forward and rearward directions. However, any suitable number of fuel tanks 210 can be used, including multiple fuel tanks 210. Multiple fuel tanks 210 may include, for example, a forward fuel tank and a rear fuel tank. The forward and rear fuel tanks can be located within the fuselage 12 and balanced about the wing's center of lift to promote the stability of the aircraft 10 during flight. In another example, multiple fuel tanks 210 may include two separate tanks, each located within a corresponding wing 14.

[0026] although Figure 1The aircraft 10 shown is an airplane, but the embodiments described herein are also applicable to other aircraft 10, including, for example, helicopters and unmanned aerial vehicles (UAVs). The aircraft discussed herein are fixed-wing or rotary-wing aircraft that generate lift through aerodynamic forces acting on, for example, a fixed wing (e.g., wing 14) or a rotating wing (e.g., the rotor of a helicopter), and are heavier than air, rather than lighter than air (e.g., airships). Furthermore, the embodiments described herein are also applicable to other applications using hydrogen as fuel. The engine described herein is a gas turbine engine, but the embodiments described herein are also applicable to other engines. Moreover, the engine, specifically the gas turbine engine, is an example of a generator using hydrogen as fuel, but hydrogen can be used as fuel for other generators (including, for example, fuel cells (hydrogen fuel cells)). Such generators can be used in a variety of applications, including stationary power generation systems (including gas turbines and hydrogen fuel cells) and other vehicles besides the aircraft 10 explicitly described herein, such as small boats, large ships, cars, trucks, etc.

[0027] Figure 2 yes Figure 1 A schematic cross-sectional view of one of the engines 100 used in the propulsion system of the aircraft 10 shown. Figure 2 The engine 100 shown is a high-bypass turbofan engine. Engine 100 may also be referred to herein as turbofan engine 100. Turbofan engine 100 has an axial direction A (extending parallel to the longitudinal centerline 101, in...) Figure 2 (Shown for reference), radial direction R and circumferential direction. Circumferential direction ( Figure 2 (Not shown in the figure) Extends in the direction of rotation about the axial direction A. The turbofan engine 100 includes a fan section 102 and a turbine 104 disposed downstream of the fan section 102.

[0028] Figure 2The turbine 104 depicted includes a tubular housing 106 (casing or nacelle) defining an annular inlet 108. The housing 106 surrounds a compressor section in series flow relationship, which includes a turbocharger or low-pressure (LP) compressor 110 and a high-pressure (HP) compressor 112; a combustion section 114; a turbine section including a high-pressure (HP) turbine 116 and a low-pressure (LP) turbine 118; and an exhaust nozzle section 120. The compressor section, combustion section 114, and turbine section together at least partially define a core airflow path 121 extending from the annular inlet 108 to the exhaust nozzle section 120. The turbofan engine also includes one or more drive shafts. More specifically, the turbofan engine includes a high-pressure (HP) shaft or spool 122 drivingly connecting the HP turbine 116 to the HP compressor 112, and a low-pressure (LP) shaft or spool 124 drivingly connecting the LP turbine 118 to the LP compressor 110.

[0029] Figure 2 The fan section 102 described herein includes a fan 126 having a plurality of fan blades 128 coupled to a disk 130 and spaced circumferentially around the disk 130. The fan blades 128 and the disk 130 are rotatable together about a longitudinal centerline (axis) 101 via an LP shaft 124. The disk 130 is covered by a rotatable front hub 132 having an aerodynamic profile to facilitate airflow through the plurality of fan blades 128. Furthermore, an annular fan housing or outer nacelle 134 circumferentially surrounds at least a portion of the fan 126 and / or the turbine 104. The nacelle 134 is supported relative to the turbine 104 by a plurality of circumferentially spaced outlet guide vanes 136. A downstream section 138 of the nacelle 134 extends above the outer portion of the turbine 104 to define a bypass airflow passage 140 therebetween.

[0030] The turbofan engine 100 is capable of operating in conjunction with and receiving a fuel flow from the fuel system 200. As will be further described below, the fuel system 200 includes a fuel delivery assembly 202 that supplies a fuel flow from the fuel tank 210 to the engine 100, and more specifically, to the fuel manifold 172 of the combustion section 114 of the turbine 104 of the turbofan engine 100. Figure 2 Unmarked, see Figure 3 ).

[0031] The turbofan engine 100 also includes various auxiliary systems to assist in the operation of the turbofan engine 100 and / or the aircraft including the turbofan engine 100. For example, the turbofan engine 100 may include a main lubrication system 152, a compressor cooling air (CCA) system 154, an active thermal gap control (ATCC) system 156, and a generator lubrication system 158, each in... Figure 2 The diagram is schematically depicted. The main lubrication system 152 is configured to provide lubricant to various bearings and gear meshing in, for example, the compressor section, turbine section, HP shaft 122, and LP shaft 124. The lubricant provided by the main lubrication system 152 can increase the service life of these components and remove a certain amount of heat from them. The compressor cooling air (CCA) system 154 supplies air from one or both of the HP compressor 112 or LP compressor 110 to one or both of the HP turbine 116 or LP turbine 118. The active thermal gap control (ATCC) system 156 cools the turbine section housing to maintain the clearance between the various turbine rotor blades and the turbine housing within desired ranges under various engine operating conditions. The generator lubrication system 158 provides lubrication for an electric generator (not shown) and provides cooling / heat removal for the electric generator. The electric generator can provide power to, for example, the starter motor of the turbofan engine 100 and / or various other electronic components of the turbofan engine 100 and / or the aircraft including the turbofan engine 100.

[0032] The heat from these accessory systems 152, 154, 156, 158 and other accessory systems can be supplied as waste heat from the turbofan engine 100 to various radiators, such as various carburetors 221, 223, as follows: Figure 3 As discussed above. Furthermore, the turbofan engine 100 may include one or more heat exchangers 162, for example, within the core airflow path 121 (such as the turbine section or the exhaust nozzle section 120). Such heat exchangers 162 can be used to extract waste heat from the airflow passing through them, and also to provide heat to various radiators (such as carburetors 221, 223 discussed below).

[0033] The turbofan engine 100 discussed herein is provided by way of example only. In other embodiments, any other suitable engine may be used in conjunction with aspects of this disclosure. For example, in other embodiments, the engine may be any other suitable gas turbine engine, such as a turboshaft engine, a turboprop engine, a turbojet engine, etc. Furthermore, in other embodiments, the gas turbine engine may have other suitable configurations, such as other suitable numbers or arrangements of shafts, compressors, turbines, fans, etc. In addition, although the turbofan engine 100 is shown as a direct-drive, fixed-pitch turbofan engine 100, in other embodiments, the gas turbine engine may be a geared gas turbine engine (i.e., including a gearbox between a fan 126 and a shaft (e.g., LP shaft 124) driving the fan), or a variable-pitch gas turbine engine (i.e., including a fan 126 having a plurality of fan blades 128 rotatable about their respective pitch axes), etc. Furthermore, still in alternative embodiments, various aspects of this disclosure may be incorporated into or otherwise used with any other type of engine (e.g., a reciprocating engine), as described above. Additionally, in other exemplary embodiments, the exemplary turbofan engine 100 may include or be operatively connected to any other suitable accessory system. Additionally, or alternatively, the exemplary turbofan engine 100 may not include or be operatively connected to one or more of the accessory systems 152, 154, 156, 158, and 162 discussed above.

[0034] Engine 100 may also include engine controller 180. Engine controller 180 is configured to operate various aspects of engine 100 and fuel system 200, including, for example, opening and closing valves (e.g., shut-off valve 204 or flow divider valves 312, 326), operating metering valve 240, operating carburetors 221, 223, and operating pumps 230, 314. Figure 3 In this embodiment, the engine controller 180 is a computing device having one or more processors 182 and one or more memories 184. The processor 182 can be any suitable processing device, including but not limited to a microprocessor, microcontroller, integrated circuit, logic device, programmable logic controller (PLC), application-specific integrated circuit (ASIC), and / or field-programmable gate array (FPGA). The memory 184 can include one or more computer-readable media, including but not limited to non-transitory computer-readable media, computer-readable non-volatile media (e.g., flash memory), RAM, ROM, hard disk drive, flash drive, and / or other memory devices.

[0035] Memory 184 may store information accessible by processor 182, including computer-readable instructions executable by processor 182. Instructions may be any set or sequence of instructions that, when executed by processor 182, cause processor 182 and engine controller 180 to perform operations. In some embodiments, instructions may be executed by processor 182 to cause processor 182 to perform any operations and functions configured for engine controller 180, as will be further described below. Instructions may be software written in any suitable programming language or may be implemented in hardware. Additionally and / or alternatively, instructions may be executed on processor 182 in logically and / or virtually separate threads. Memory 184 may further store data accessible by processor 182.

[0036] The techniques discussed herein refer to computer-based systems and the actions taken by and from computer-based systems, as well as the information sent to and from computer-based systems. Those skilled in the art will recognize that the inherent flexibility of computer-based systems allows for a wide variety of possible configurations, combinations, and divisions of tasks and functions between and within components. For example, the processes discussed herein can be implemented using a single computing device or multiple computing devices working in combination. Databases, memories, instructions, and applications can be implemented on a single system or distributed across multiple systems. Distributed components can operate sequentially or in parallel.

[0037] Figure 3 This is a schematic diagram of a fuel system 200 according to an embodiment of the present disclosure. The fuel system 200 is configured to store hydrogen fuel for engine 100 in a fuel tank 210 and deliver the hydrogen fuel to engine 100 via a fuel delivery assembly 202. The fuel delivery assembly 202 includes pipes, tubes, etc., to fluidly connect various components of the fuel system 200 to engine 100. The fuel tank 210 may be configured to at least partially hold the hydrogen fuel in a liquid phase and may be configured to supply the hydrogen fuel to the fuel delivery assembly 202 substantially entirely in a liquid phase (e.g., entirely in a liquid phase). For example, the fuel tank 210 may have a fixed volume and contain a certain volume of hydrogen fuel in a liquid phase (liquid hydrogen fuel). Because the fuel tank 210 supplies the hydrogen fuel to the fuel delivery assembly 202 substantially entirely in a liquid phase, the volume of liquid hydrogen fuel in the fuel tank 210 is reduced and the remaining volume in the fuel tank 210 is replenished by, for example, hydrogen in a gaseous phase (gaseous hydrogen). As used herein, the term “substantially complete” to describe a hydrogen fuel phase means that at least 99% of the mass of the portion of hydrogen fuel is in the phase, for example, at least 97.5%, at least 95%, at least 92.5%, at least 90%, at least 85%, or at least 75% of the mass of the portion of hydrogen fuel is in the phase.

[0038] To ensure that hydrogen fuel is stored essentially entirely in the liquid phase, it is stored in fuel tank 210 at very low (cryogenic) temperatures. For example, hydrogen fuel can be stored in fuel tank 210 at atmospheric pressure at approximately -253 degrees Celsius or lower, or at other temperatures and pressures, to maintain its essentially liquid state. Fuel tank 210 can be made of materials such as titanium, A double-walled cryogenic storage tank made of known materials such as aluminum or composite materials. The fuel tank 210 and fuel system 200 may include various support structures and components to facilitate the storage of hydrogen fuel in this manner.

[0039] Liquid hydrogen fuel is supplied from fuel tank 210 to fuel delivery assembly 202. Fuel delivery assembly 202 may include one or more lines, conduits, pipes, etc., configured to transport hydrogen fuel between fuel tank 210 and engine 100. Fuel delivery assembly 202 provides a flow path for hydrogen fuel from fuel tank 210 downstream to engine 100. Here, the terms "downstream" and "upstream" are used to describe the position of components relative to the flow direction of hydrogen fuel in the flow path of fuel delivery assembly 202. Fuel delivery assembly 202 may also include various valves (e.g., shut-off valve 204) and other components for delivering hydrogen fuel to engine 100, these components not in... Figure 3 As shown in the figure. The fluid pipelines discussed in this article, especially those transporting liquid hydrogen, can be vacuum-jacketed pipelines.

[0040] In this embodiment, the fuel tank 210 is a hydrogen fuel source. The fuel delivery assembly 202 is configured to receive hydrogen fuel from the fuel tank 210 (hydrogen fuel source) and supply hydrogen fuel from the hydrogen fuel source to the engine 100 (generator), and more specifically, to the fuel input array of the engine 100 (e.g., fuel manifold 172 and fuel nozzle 174, which will be discussed further below). The fuel system 200 may include, for example, a shut-off valve 204 located in the mounting bracket 18 or at another location between the fuel tank 210 and the engine 100, which can be used to isolate and disconnect the fuel tank 210 from components of the fuel delivery assembly 202 downstream of the shut-off valve 204. Thus, the shut-off valve 204 may be positioned to isolate components of the fuel system 200 located in the engine from components of the fuel system 200 located in the rest of the aircraft 10.

[0041] Hydrogen fuel is delivered to engine 100 via fuel delivery assembly 202 in the liquid phase, gas phase, supercritical phase, or both gas and supercritical phase. Therefore, fuel system 200 includes at least one carburetor 221, 223 in fluid communication with fuel delivery assembly 202 to heat the liquid hydrogen fuel flowing through fuel delivery assembly 202. Figure 3In the illustrated embodiment, the fuel system 200 includes two vaporizers, a primary vaporizer 221 and a secondary vaporizer 223. Each vaporizer 221, 223 is positioned in the hydrogen fuel flow path between the fuel tank 210 and the engine 100. Figure 3 In the illustrated embodiment, each carburetor 221, 223 is at least partially located within the engine 100. For example, when located within the engine 100, the carburetor 221, 223 may be located in the nacelle 134. However, the carburetor 221, 223 may be located at other suitable locations in the hydrogen flow path between the fuel tank 210 and the engine 100. For example, the carburetor 221, 223 may be located outside the engine 100 and within the fuselage 12, wing 14, or pylon 18.

[0042] Each carburetor 221, 223 is thermally connected to at least one heat source, such as a primary heat source 225, a secondary heat source 227, or both. In this embodiment, the primary carburetor 221 is configured to operate once the engine 100 is in a thermally stable state, and the primary heat source 225 is waste heat from the engine 100. Therefore, the primary carburetor 221 is thermally connected to at least one of the primary lubrication system 152, the compressor cooling air system 154, the active thermal gap control system 156, the generator lubrication system 158, and the heat exchanger 162 to extract waste heat from the engine 100 to heat the hydrogen fuel. In this way, it should be understood that the carburetor 221 is configured to operate by extracting heat from the primary heat source 225 once the engine 100 can provide sufficient heat to the carburetor 221 via the primary heat source 225 to facilitate the operation of the carburetor 221.

[0043] In this embodiment, the secondary vaporizer 223 is a combination of a starter and a fine-tuning vaporizer, used to heat the liquid hydrogen fuel flowing through the fuel delivery assembly 202 when the main vaporizer 221 is insufficient to heat the hydrogen fuel. For example, during engine 100 startup, the engine 100 may not be in a thermally stable state, and the secondary vaporizer 223 is used instead of the main vaporizer 221 to heat the hydrogen fuel during (or before) startup. In this example, the secondary vaporizer 223 operates as a starter vaporizer. In another example, the main vaporizer 221 may not heat the hydrogen fuel to the required temperature; therefore, the secondary vaporizer 223 operates as a fine-tuning vaporizer to add supplemental heat to the hydrogen fuel and heat it to the required temperature. This may occur when, for example, the heat supplied to the main vaporizer 221 by the main heat source 225 is insufficient to heat the hydrogen fuel to the required temperature.

[0044] The secondary carburetor 223 is thermally connected to the secondary heat source 227. When the secondary carburetor 223 operates as a combined start-up and fine-tuning carburetor, the secondary heat source 227 is preferably a heat source external to the engine 100, which can provide heat to the secondary carburetor 223 regardless of whether the engine 100 is running, and can be used, for example, during (or before) starting the engine 100. The secondary heat source 227 may include, for example, a power source, a catalytic heater or burner, and / or bleed airflow from an auxiliary power unit. For example, when the secondary carburetor 223 includes one or more resistance heaters powered by a power source, the secondary heat source 227 may be integrated into the secondary carburetor 223.

[0045] As described above, carburetors 221 and 223 can be thermally coupled to any suitable heat source. For example, the main carburetor 221 and / or the secondary carburetor 223 can be thermally coupled to both waste heat from the engine 100 and a heat source outside the engine 100. Figure 3 In the illustrated embodiment, the primary vaporizer 221 and the secondary vaporizer 223 are positioned in series relative to the flow of hydrogen in the fuel delivery assembly 202, with the secondary vaporizer 223 located downstream of the primary vaporizer 221. However, other arrangements of the vaporizers 221 and 223 can be used, such as arranging the primary vaporizer 221 and the secondary vaporizer 223 in parallel with each other, as shown below. Figure 4 As shown. Figure 4 This is a schematic diagram of a fuel system 200a with a main vaporizer 221 and a secondary vaporizer 223 arranged in parallel. Although the vaporizers 221 and 223 are arranged in... Figure 3 and Figure 4 The differences are between them, but the remaining components of the fuel system 200a are the same as those of the others. Figure 3 The components shown are the same or similar.

[0046] Figure 5A , 5B Figures 5C and 5C show additional arrangements of the carburetor in fuel systems 200b, 200c, and 200d. Figure 5A , 5B Figures 5C and 5C are schematic diagrams of fuel systems 200b, 200c, and 200d. In Figure 5A and 5B In the arrangement shown, multiple secondary vaporizers 223 are used, one of which is a starting vaporizer 223a, and another is a fine-tuning vaporizer 223b. Figure 3 and 4In the illustrated embodiment, the secondary vaporizer 223 is positioned to receive hydrogen fuel from the same hydrogen source as the primary vaporizer 221 (e.g., fuel tank 210). However, the starter vaporizer 223a can be positioned to receive hydrogen fuel from a secondary hydrogen fuel source 212, different from the primary vaporizer 221. The secondary hydrogen fuel source 212 can be attached to the primary fuel tank (fuel tank 210) or a separate tank. Using the secondary hydrogen fuel source 212 allows the hydrogen fuel delivery system to be designed to handle only a limited fuel flow (e.g., up to idle). Using the secondary hydrogen fuel source 212 helps determine the dimensions of the heat source 227 and the starter vaporizer 223a, and optimizes the heat source 227 and the starter vaporizer 223a to better meet start-up requirements.

[0047] The fine-tuning carburetor 223b can be positioned in series with the main carburetor 221, such as... Figure 5A As shown, or connected in parallel with the main vaporizer 221, such as Figure 5B As shown. In another alternative arrangement, the fine-tuning carburetor 223b can be omitted, as... Figure 5C As shown. Although carburetors 221 and 223 are in Figures 5A to 5C The layout in is different from that in Figure 3 The arrangement shown, but Figure 3 The same or similar components of the fuel system 200 shown can be used Figures 5A to 5C The arrangement of fuel systems 200b, 200c, and 200d is shown. The following discussion will focus on... Figure 3 It applies to, but it also applies to. Figures 4 to 5C The arrangement shown.

[0048] like Figure 3 As shown, the fuel delivery assembly 202 also includes a pump 230 to direct a flow of hydrogen fuel through the fuel delivery assembly 202 to the engine 100. The pump 230 is typically a primary source of pressure increase in the fuel delivery assembly 202 between the fuel tank 210 and the engine 100. The pump 230 can be configured to increase the pressure in the fuel delivery assembly 202 to a level greater than that in the combustion chamber of the combustion section 114 of the engine 100. Figure 2The pressure within the fuel delivery assembly 202. In this embodiment, pump 230 is positioned upstream of the main vaporizer 221 in the hydrogen fuel stream. In this embodiment, pump 230 is positioned outside the fuselage 12 and wing 14, and at least partially within the pylon 18, or at least partially within the engine 100. More specifically, pump 230 is positioned within the engine 100. With pump 230 in such a position, pump 230 can be any suitable pump configured to receive a hydrogen fuel stream that is substantially entirely in the liquid phase. However, in other embodiments, pump 230 can be positioned at any other suitable location, including other locations within the hydrogen fuel flow path. For example, pump 230 can be located downstream of the main vaporizer 221 and can be configured to receive a hydrogen fuel stream that is substantially entirely in the gaseous or supercritical phase through the fuel delivery assembly 202.

[0049] The fuel system 200 also includes a fuel metering unit in fluid communication with the fuel delivery assembly 202. In this embodiment, the fuel metering unit is a metering valve 240 located downstream of the carburetors 221, 223 and the pump 230. The metering valve 240 is configured to receive hydrogen fuel that is substantially entirely in the gas phase or substantially entirely in the supercritical phase. The metering valve 240 is further configured to supply a fuel flow to the engine 100 in a desired manner. More specifically, as Figure 3 Schematably depicted, metering valve 240 is configured to supply a desired volume of hydrogen fuel to fuel manifold 172 of engine 100 at, for example, a desired flow rate. Fuel manifold 172 then distributes (supplyes) the received hydrogen fuel to multiple fuel nozzles 174 within combustion section 114 of engine 100, where the hydrogen fuel is mixed with compressed air and the mixture of hydrogen fuel and compressed air is combusted to produce combustion gases that drive engine 100. Adjusting metering valve 240 changes the volume of fuel supplied to combustion section 114 of engine 100, thus changing the amount of propulsive thrust produced by engine 100 in propulsion vehicle 10.

[0050] The hydrogen fuel used in engine 100 and fuel system 200 can be substantially pure hydrogen molecules (diatomic hydrogen). Because diatomic hydrogen is the smallest known molecule, it is difficult to contain, especially in its gaseous form. When in its gaseous form, hydrogen also tends to permeate through materials and joints between components without leaving residue. Hydrogen can easily leak through conventional seals and other small openings (e.g., cracks that may form in fuel system 200 over time). When hydrogen fuel is not supplied to engine 100 for combustion, hydrogen is purged from fuel system 200. This embodiment of fuel system 200 includes a hydrogen fuel purging system 300 for purging hydrogen fuel from at least a portion of fuel system 200. For example, a commercial aircraft 10 may land and, after parking at the gate, be temporarily shut down for a period of time or longer, such as overnight, before boarding another flight. Hydrogen fuel purging system 300 can be used to purge a portion of fuel system 200 after shutdown.

[0051] The hydrogen fuel purging system 300 uses a purging fluid to remove hydrogen fuel from at least a portion of the fuel system 200. Any suitable purging fluid can be used; however, in the embodiments discussed herein, the purging fluid is a gas and will be referred to as the purging gas. The purging gas is preferably a substantially inert gas and does not react with hydrogen, or reacts with minimal reaction with hydrogen. The inert gas can be a substantially thermally inert gas that does not promote ignition or act as an oxidizer to produce combustion, flame, spark, or exothermic energy release in any type of reaction with hydrogen as a fuel source. In some embodiments, the purging gas has a very low freezing point, suitable for purging low-temperature (cryogenic) systems of the fuel system 200. Examples of suitable purging gases include rare gases such as helium, neon, argon, krypton, xenon, and radon. Examples of thermally inert gases that can be used as purging gases include carbon dioxide, carbon monoxide, etc. Well-known fire extinguishing agents can also be used as purging gases. These fire extinguishing agents include, but are not limited to, halon, FS 227, NAF S 125, and NAF S 227. Another suitable purging gas includes nitrogen, such as diatomic nitrogen.

[0052] Purge gas is supplied to the hydrogen fuel purging system 300 by purge gas source 310. In some embodiments, purge gas source 310 may be a tank for storing purge gas. In other embodiments where the purge gas is nitrogen, purge gas source 310 may be a nitrogen separator configured to extract (strip) nitrogen from the atmosphere or another nitrogen generation system. Suitable nitrogen generation systems include, for example, those used as part of existing fuel tank inerting systems or onboard inert gas generation systems (OBIGGS). Purge gas source 310 in Figure 3The purge gas source 310 is shown as being located within engine 100, but it may be located at other suitable locations outside engine 100. For example, purge gas source 310 may be located at other locations within aircraft 10, including, for example, in fuselage 12, wing 14, or pylon 18.

[0053] Purge gas flows from purge gas source 310 into purge gas delivery assembly 302. Purge gas delivery assembly 302 includes pipes, tubes, etc., to fluidly connect various components of the hydrogen fuel purging system 300 to the fuel system 200. In the embodiments discussed herein, purge gas delivery assembly 302 fluidly connects purge gas source 310 to at least one location in the fuel system 200, and more specifically, to fuel delivery assembly 202. More specifically, in Figure 3 In the illustrated embodiment, the purge gas delivery assembly 302 is fluidly coupled to the fuel delivery assembly 202 using a diverter valve 312. The diverter valve 312 can be used to selectively connect the purge gas delivery assembly 302 to the fuel delivery assembly 202. In a first position, the diverter valve 312 allows hydrogen fuel to flow through the fuel delivery assembly 202, but in a second position, the diverter valve 312 shuts off a portion of the fuel system 200 and fluidly connects the purge gas source 310 to the fuel delivery assembly 202.

[0054] Figure 3 The embodiments illustrate multiple diversion valves 312. These diversion valves 312 are shown to illustrate various locations where purge gas can be introduced into the fuel system 200, but some of these diversion valves 312 may be omitted. The diversion valves 312 are located upstream of the metering valve 240, the secondary vaporizer 223, the main vaporizer 221, and the pump 230, respectively. As shown, the diversion valves 312 may be located directly upstream of each of these components. The diversion valves 312 may be located in a second position to isolate the components upstream of the diversion valve 312, allowing purge gas to be introduced at the diversion valve 312 and directed to the components downstream of the diversion valve 312. Thus, purge gas may be introduced upstream of the metering valve 240, the secondary vaporizer 223, the main vaporizer 221, and / or the pump 230, and in some embodiments, directly upstream of each of these components.

[0055] Although purge gas can be used to propel hydrogen fuel through fuel system 200 and out of fuel nozzle 174 for emission, the hydrogen and purge gas are preferably vented outside the aircraft. The hydrogen fuel purging system 300 includes an exhaust line 322 for venting hydrogen fuel and purging gas to the exterior of engine 100. In this embodiment, exhaust line 322 is fluidly connected to an exhaust port 324, which has an exhaust opening on the exterior of engine 100 (e.g., outer casing 106 or outer nacelle 134). The exhaust port 324 may be located in other locations on aircraft 10, including, for example, on wing 14 or fuselage 12, such as on tail 16. Figure 1 As shown. A diversion valve 326 is used to fluidly connect the fuel delivery assembly 202 to the discharge line 322 and the discharge port 324. The diversion valve 326 can be used to selectively connect the fuel delivery assembly 202 to the discharge line 322 and the discharge port 324. In a first position, the diversion valve 326 allows hydrogen fuel to flow through the fuel delivery assembly 202, but in a second position, the diversion valve 326 closes off a portion of the fuel system 200 and fluidly connects the fuel delivery assembly 202 to the discharge line 322 and the discharge port 324. Figure 3 In the illustrated embodiment, the diversion valve 326 is positioned upstream of the fuel manifold 172 and downstream of the metering valve 240. In this way, components upstream of the fuel input array, in this embodiment the fuel manifold 172 and the fuel nozzle 174, can be purged with hydrogen fuel. Although only one exhaust port 324 is shown, multiple exhaust ports 324 can be used. In this configuration, multiple exhaust ports 324 can be connected to a single exhaust line 322, but in other embodiments, each exhaust port 324 can be fluidly connected to a corresponding exhaust line 322 and diversion valve 326 at multiple locations within the fuel delivery assembly 202.

[0056] The hydrogen fuel purging system 300 also includes a pump 314 configured to increase the pressure of the purging gas to a level sufficient to propel hydrogen fuel through the fuel delivery assembly 202, the discharge line 322, and out of the discharge port 324. One of the diverter valves 312 connected to the purging gas delivery assembly 302 is positioned in a second position, and a diverter valve 326 connected to the discharge line 322 is also positioned in a second position. The pump 314 can then be operated to propel the purging gas and hydrogen through the fuel delivery assembly 202 and out of the discharge port 324. In this configuration, the discharge port 324 is fluidly coupled to the fuel delivery assembly 202 and configured to discharge hydrogen fuel from the fuel delivery assembly 202 when purging gas is supplied from the purging gas source 310 to the fuel delivery assembly 202.

[0057] As mentioned above, hydrogen is highly reactive and has a wide flammability limit. Even when exposed to small amounts of oxygen, the ignition energy requirement for hydrogen is very low, even as low as that of an electrostatic spark. Therefore, an anti-ignition system can be used to prevent the ignition of emitted hydrogen and hydrogen upstream of the exhaust port 324, included within the fuel delivery assembly 202. The anti-ignition system may include a spark prevention system, such as a grounding system. Figure 3 In the illustrated embodiment, the anti-ignition system includes a flame arrester 328. The flame arrester 328 is positioned in the discharge line 322, near the discharge port 324. Any suitable flame arrester 328 can be used. The flame arrester 328 can be, for example, a serpentine channel formed in the discharge line 322, such as a P-trap, which prevents a continuous, uninterrupted gas path to the fuel delivery assembly 202. Other suitable flame arresters 328 may include a wire mesh or a diffusion system in which the emitted gas is foamed by a liquid (e.g., water) before reaching the discharge port 324.

[0058] exist Figure 3 In the illustrated embodiment, the purge gas delivery assembly 302 is also fluidly connected to the fuel delivery assembly 202 at a location between the diverter valve 326 and the fuel nozzle 174, which are connected to the discharge line 322. A check valve 316 is positioned in this line of the purge gas delivery assembly 302 to allow purge gas to flow into the fuel delivery assembly 202, but prevents any backflow from the fuel delivery assembly 202 to the purge gas delivery assembly 302. Introducing purge gas at this point allows the fuel array (e.g., fuel manifold 172 and fuel nozzle 174) to remain charged with purge gas forward from the diverter valve 312 and check valve 316 after closure. With the diverter valve 326 connected to the discharge line 322 in the first position, the discharge line 322 and the discharge port 324 are closed, and the upstream component of the fuel delivery assembly 202 contacts the fuel check valve 176. Figure 3 (Only one is shown in the diagram) traps purge gas between the ambient air and the system as a buffer. For example, a sensor (e.g., a pressure sensor) can be used to monitor this trapped purge gas, which is communicatively coupled to a controller (e.g., engine controller 180) to monitor system integrity. Thus, engine controller 180 can sense pressure loss, which may indicate a leak in fuel delivery assembly 202.

[0059] Figure 6 This is a schematic diagram of fuel system 200e, which has multiple discharge connections to fuel delivery assembly 202. Apart from the differences mentioned below, the remaining components and arrangement of fuel system 200e are similar to... Figure 3 The components of the fuel system 200e shown are the same or similar. Figure 3In the illustrated embodiment, a diversion valve 326 is shown to fluidly connect the fuel delivery assembly 202 to an exhaust port 324 on the exterior of the aircraft 10. In some embodiments, the fuel delivery assembly 202 may be fluidly connected to the exhaust port 324 at multiple locations. Figure 6 As shown, for example, a connection to the discharge port 324 is as described above regarding... Figure 3 It is positioned as described above, and is connected to another outlet 324 downstream of pump 230 and upstream of vaporizers 221 and 223.

[0060] In this configuration, different sections of the fuel delivery assembly 202 can be purged at different times or using different purge gases. Two different purge gases are used here. When the hydrogen fuel is in the gaseous or supercritical phase, one purge gas, such as nitrogen, is used for sections operating at higher temperatures. When the hydrogen fuel is in the liquid phase, another purge gas, such as helium, is used for sections operating at lower temperatures. The fuel delivery assembly 202 is fluidly coupled to a second purge gas source 310a containing the second purge gas (e.g., helium). If nitrogen is used as the purge gas for the section of the fuel system 200e that delivers hydrogen fuel in the liquid phase, there is a risk that some nitrogen purge gas may condense in these sections, forming, for example, nitrogen crystals in the fuel system 200e. Conversely, when the hydrogen fuel is liquid, helium can remain suspended in the hydrogen fuel; therefore, helium may be preferred for the section of the fuel delivery assembly 202 that delivers hydrogen fuel in the liquid phase. Due to the cost of helium, minimizing its use is likely preferred; therefore, another purging gas, such as nitrogen, is used for other parts of the fuel system 200.

[0061] Figure 7This is a schematic cross-sectional view of a double-walled tube 400 that can be used as part of a fuel delivery assembly 202 to deliver hydrogen fuel. In the embodiment discussed above, purge gas can flow through the same channel of the fuel delivery assembly 202 as the hydrogen fuel; however, in addition (or alternatively), purge gas can flow through a separate channel such that the purge gas can act as a buffer between the hydrogen fuel and the surrounding environment. In this way, the purge gas can be used to remove hydrogen leaking from the hydrogen flow path through the discharge port 324. The double-walled tube 400 includes an inner wall 412 and an outer wall 414. In this embodiment, the inner wall 412 is annular and defines a hydrogen fuel flow path 422. The hydrogen fuel flows through the hydrogen fuel flow path 422 as it is delivered from the fuel tank 210 to the fuel nozzle 174 in the fuel delivery assembly 202. The outer wall 414 surrounds the inner wall 412 and defines an annular outer flow path 424 (or cavity) between the inner wall 412 and the outer wall 414. In some embodiments, the external flow path 424 may be subjected to a vacuum to help maintain the temperature of the hydrogen fuel in the hydrogen fuel flow path 422. In this embodiment, the hydrogen fuel flow path 422 is fluidly connected to the purge gas source 310, the discharge line 322, and the discharge port 324. This fluid connection can be made in a manner similar to that discussed above; however, in some embodiments, the diverter valves 312, 326 may be omitted. The purge gas can then flow through the external flow path 424 to remove any hydrogen in the event of a leak. Therefore, the external flow path 424 is fluidly connected to the purge gas source 310 to receive the purge gas and is configured to guide the purge gas flow through it. The external flow path 424 may also be fluidly connected to the discharge port 324 to discharge the purge gas flowing through the external flow path 424.

[0062] Figure 8 This is a schematic cross-sectional view of a three-walled tube 402 that can be used as part of a fuel delivery assembly 202 to deliver hydrogen fuel. In some embodiments, the three-walled tube 402 can be in a manner similar to... Figure 7 The double-walled tube 400 shown is used in part of the fuel delivery assembly 202. Figure 8 The three-walled tube 402 shown also includes an intermediate wall 416. The intermediate wall 416 surrounds the inner wall 412 and defines an annular intermediate flow path 426 (or cavity) between the inner wall 412 and the intermediate wall 416. An outer wall 414 surrounds both the intermediate wall 416 and the inner wall 412, and an outer flow path 424 is formed between the intermediate wall 416 and the outer wall 414. The intermediate flow path 426 can withstand a vacuum to help maintain the temperature of the hydrogen fuel in the hydrogen fuel flow path 422.

[0063] Further aspects of this disclosure are provided by the subject matter of the following clauses.

[0064] A hydrogen fuel system for supplying hydrogen to a generator includes a fuel delivery assembly, a purge gas source, and an exhaust port. The fuel delivery assembly is configured to receive hydrogen fuel from the hydrogen fuel source and supply the hydrogen fuel from the hydrogen fuel source to the generator. The purge gas source is fluidly coupled to the fuel delivery assembly and configured to supply purge gas to the fuel delivery assembly. The exhaust port is fluidly coupled to the fuel delivery assembly and configured to discharge hydrogen fuel from the fuel delivery assembly when the purge gas is supplied to the fuel delivery assembly.

[0065] According to the hydrogen fuel system described in the foregoing clause, the purging gas is one of an inert gas, nitrogen, carbon dioxide, carbon monoxide, or a fire extinguishing agent.

[0066] The hydrogen fuel system according to any one of the preceding claims, wherein the fuel delivery assembly comprises a double-walled tube having an inner wall and an outer wall. The inner wall defines a hydrogen fuel flow path. The outer wall surrounds the inner wall and defines an external flow path between the inner wall and the outer wall. The external flow path is fluidly coupled to the purge gas source to receive the purge gas and is configured to guide the purge gas through it.

[0067] In a hydrogen fuel system according to any one of the preceding clauses, the external flow path is fluidly connected to the exhaust port to discharge the purge gas flowing through the external flow path.

[0068] The hydrogen fuel system according to any one of the preceding claims, wherein the fuel delivery assembly comprises a three-walled tube having an inner wall, an outer wall, and an intermediate wall. The inner wall defines a hydrogen fuel flow path. The intermediate wall surrounds the inner wall and defines a cavity between the inner wall and the intermediate wall. The outer wall surrounds the intermediate wall and the inner wall and defines an external flow path between the inner wall and the outer wall. The external flow path is fluidly coupled to the purge gas source to receive the purge gas and is configured to guide the purge gas flow therethrough.

[0069] In a hydrogen fuel system according to any one of the preceding clauses, the external flow path is fluidly connected to the exhaust port to discharge the purge gas flowing through the external flow path.

[0070] The hydrogen fuel system according to any one of the preceding claims further includes a purge gas delivery assembly and a diversion valve. The purge gas delivery assembly fluidly connects the purge gas source to at least one location in the fuel delivery assembly. The diversion valve fluidly connects the purge gas delivery assembly to the fuel delivery assembly.

[0071] According to any one of the preceding clauses, in the hydrogen fuel system, the diversion valve includes a first position and a second position. In the first position, the diversion valve allows hydrogen fuel to flow through the fuel delivery assembly. In the second position, the diversion valve shuts off a portion of the hydrogen fuel system and fluidly connects the purge gas source to the fuel delivery assembly.

[0072] The hydrogen fuel system according to any one of the preceding clauses further includes an exhaust line that fluidly connects the fuel delivery assembly to the exhaust port.

[0073] The hydrogen fuel system according to any one of the preceding clauses further includes a flame arrester positioned in the discharge line near the discharge port.

[0074] The hydrogen fuel system according to any one of the preceding clauses further includes a diversion valve fluidly connecting the fuel delivery assembly to the emission line, the diversion valve having a first position and a second position. In the first position, the diversion valve allows hydrogen fuel to flow through the fuel delivery assembly. In the second position, the diversion valve closes off a portion of the hydrogen fuel system and fluidly connects the fuel delivery assembly to the emission line.

[0075] The hydrogen fuel system according to any one of the preceding clauses further includes a fuel input array. The fuel delivery assembly is selectively fluidly coupled to the exhaust port at a location upstream of the fuel input array.

[0076] The hydrogen fuel system according to any one of the preceding clauses further includes a fuel metering unit. The fuel delivery assembly is selectively fluidly coupled to the exhaust port at a location downstream of the fuel metering unit.

[0077] In the hydrogen fuel system according to any one of the preceding clauses, the purge gas source is selectively fluidly coupled to the fuel delivery assembly at a location upstream of the fuel metering unit.

[0078] In the hydrogen fuel system according to any one of the preceding clauses, the purge gas source is fluidly connected to the fuel delivery assembly at a location downstream of the fuel metering unit and upstream of the fuel input array.

[0079] The hydrogen fuel system according to any one of the preceding clauses further includes a check valve located in the purge gas source between the purge gas source and the fuel delivery assembly. The check valve is configured to allow the purge gas to flow into the fuel delivery assembly and to prevent backflow from the fuel delivery assembly into the purge gas source.

[0080] The hydrogen fuel system according to any one of the preceding clauses further includes at least one vaporizer in communication with the fuel delivery assembly. The fuel delivery assembly receives the hydrogen fuel in a liquid phase, and the at least one vaporizer is configured to heat the hydrogen fuel in the liquid phase to at least one of a gas phase and a supercritical phase.

[0081] The hydrogen fuel system according to any one of the preceding clauses further includes a fuel tank configured to maintain the hydrogen fuel in a liquid phase. The fuel tank is the source of the hydrogen fuel, and the vaporizer is located between the fuel tank and the generator.

[0082] An aircraft comprising: a hydrogen fuel system according to any one of the preceding clauses, wherein the generator is a gas turbine engine.

[0083] The aircraft according to any one of the foregoing clauses further includes a fuselage. The fuel tank is at least partially located within the fuselage.

[0084] While the foregoing description is directed to preferred embodiments, it should be noted that other variations and modifications will be apparent to those skilled in the art and can be made without departing from the spirit or scope of this disclosure. Furthermore, features described in connection with one embodiment may be used in conjunction with other embodiments, even if not explicitly stated above.

Claims

1. A hydrogen fuel system for supplying hydrogen to a generator, characterized in that, The hydrogen fuel system includes: Fuel input array; A fuel delivery assembly configured to receive hydrogen fuel in the liquid phase from a hydrogen fuel source and to supply the hydrogen fuel from the hydrogen fuel source to the fuel input array; At least one vaporizer, the at least one vaporizer being in communication with the fuel delivery assembly, the at least one vaporizer being configured to heat the hydrogen fuel in the liquid phase to at least one of the gas phase or supercritical phase; A fuel metering unit, located upstream of the fuel input array, is adjustable to change the volume of fuel supplied to the fuel input array. Purge gas source; A purge gas delivery assembly fluidly connects the purge gas source to the fuel delivery assembly at multiple locations, including a first location and a second location, the first location being upstream of the at least one vaporizer; A purge gas pump, located in the purge gas delivery assembly and configured to supply purge gas from the purge gas source to the fuel delivery assembly at the plurality of locations; An exhaust port, fluidly connected to the fuel delivery assembly and configured to discharge hydrogen fuel from the fuel delivery assembly when the purge gas is supplied to the fuel delivery assembly, the exhaust port being fluidly connected to the fuel delivery assembly at a connection location upstream of the fuel input array and downstream of the fuel metering unit; An exhaust valve, which can be positioned to fluidly connect the exhaust port to the fuel delivery assembly and shut off a portion of the hydrogen fuel system downstream of the connection location; An ambient air valve is located between the fuel input array and the ambient air downstream of the fuel input array, and is configured to prevent the ambient air from flowing into the fuel delivery assembly; A purge gas recirculation valve, wherein the purge gas source is fluidly coupled to the fuel delivery assembly at a second position, the second position being downstream of the exhaust valve and upstream of the fuel input array, and configured to supply the purge gas to the fuel delivery assembly between the fuel input array and the exhaust valve, the purge gas recirculation valve being located in the fuel delivery assembly to prevent backflow from the fuel delivery assembly to the purge gas delivery assembly; and A controller operably connected to the purge gas pump and one or more valves, the one or more valves including one or more of the exhaust valve, the ambient air valve, or the purge gas return valve, the controller being configured to operate the purge gas pump and adjust the one or more valves to retain purge gas as a buffer between the connection location and the fuel input array.

2. The hydrogen fuel system according to claim 1, characterized in that, The purging gas is one of the following: an inert gas, nitrogen, carbon dioxide, carbon monoxide, or a fire extinguishing agent.

3. The hydrogen fuel system according to claim 1, characterized in that, The fuel delivery assembly includes a double-walled tube having an inner wall and an outer wall, the inner wall defining a hydrogen fuel flow path, the outer wall surrounding the inner wall and defining an external flow path between the inner wall and the outer wall, the external flow path being fluidly coupled to the purge gas source to receive the purge gas and configured to guide the purge gas through it.

4. The hydrogen fuel system according to claim 3, characterized in that, The external flow path is fluidly connected to the outlet to discharge the purge gas flowing through the external flow path.

5. The hydrogen fuel system according to claim 1, characterized in that, The fuel delivery assembly includes a three-walled tube having an inner wall, an outer wall, and a middle wall. The inner wall defines a hydrogen fuel flow path. The middle wall surrounds the inner wall and defines a cavity between the inner wall and the middle wall. The outer wall surrounds the middle wall and the inner wall and defines an external flow path between the inner wall and the outer wall. The external flow path is fluidly coupled to the purge gas source to receive the purge gas and is configured to guide the purge gas through it.

6. The hydrogen fuel system according to claim 5, characterized in that, The external flow path is fluidly connected to the outlet to discharge the purge gas flowing out of the external flow path.

7. The hydrogen fuel system according to claim 1, characterized in that, Further includes: One or more diversion valves fluidly connect the purge gas delivery assembly to the fuel delivery assembly.

8. The hydrogen fuel system according to claim 7, characterized in that, Each of the one or more flow divider valves includes a first position and a second position. In the first position, the diversion valve allows hydrogen fuel to flow through the fuel delivery assembly, and In the second position, the diversion valve shuts off a portion of the hydrogen fuel system and fluidly connects the purge gas source to the fuel delivery assembly.

9. The hydrogen fuel system according to claim 1, characterized in that, It further includes a discharge line that fluidly connects the fuel delivery assembly to the discharge port.

10. The hydrogen fuel system according to claim 9, characterized in that, It further includes a flame arrester positioned in the discharge line near the discharge port.

11. The hydrogen fuel system according to claim 9, characterized in that, in, The discharge valve is a diversion valve that fluidly connects the fuel delivery assembly to the discharge line, and the diversion valve includes a first position and a second position. In the first position, the diversion valve allows hydrogen fuel to flow through the fuel delivery assembly, and In the second position, the diversion valve closes the portion of the hydrogen fuel system downstream of the connection position and fluidly connects the fuel delivery assembly to the discharge line.

12. The hydrogen fuel system according to claim 1, characterized in that, The purge gas delivery assembly is selectively fluidly coupled to the fuel delivery assembly at multiple locations upstream of the discharge valve.

13. The hydrogen fuel system according to claim 12, characterized in that, in, The purge gas delivery assembly is fluidly connected to the fuel delivery assembly at a third location, which is downstream of the at least one vaporizer.

14. The hydrogen fuel system according to claim 1, characterized in that, in, The purge gas backflow valve is a check valve located between the purge gas source and the fuel delivery assembly. The check valve is configured to allow the purge gas to flow into the fuel delivery assembly and to prevent backflow from the fuel delivery assembly into the purge gas source.

15. The hydrogen fuel system according to claim 1, characterized in that, The device further includes a fuel tank configured to maintain the hydrogen fuel in a liquid phase, the fuel tank being the source of the hydrogen fuel, and the at least one vaporizer located between the fuel tank and the fuel input array.

16. An aircraft, characterized in that, include: According to claim 15, the hydrogen fuel system The generator mentioned therein is a gas turbine engine.

17. An aircraft, characterized in that, The aircraft includes a fuselage and a hydrogen fuel system according to claim 1, wherein the exhaust port includes an exhaust opening and the exhaust opening is located on the fuselage.

18. An aircraft, characterized in that, The aircraft includes: According to claim 1, the hydrogen fuel system, The generator is a gas turbine engine, and The exhaust port includes an exhaust opening located on the exterior of the gas turbine engine.

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