Fuel cell system for aviation vehicle

Abstract

A propulsion system for an aircraft includes a fan section having a fan; a turbine including a compressor section, a combustion section, and a turbine section arranged in a serial flow order; at least one motor; a fuel cell assembly configured to supply power to the motor; and a controller including a memory and one or more processors. One or both of the turbine and the at least one electric machine are configured to drive rotation of a fan of the fan section. A fuel cell assembly includes at least one fuel cell, a first fluid inlet for receiving a flow of pressurized air, and a second fluid inlet for receiving a flow of fuel.

Description

Fuel cell systems for aircraft Technical Field

[0001] This disclosure relates to fuel cell systems for aircraft and methods of operating such fuel cell systems. Background Technology

[0002] Aircraft launch vehicles use various power sources to drive one or more propellers that can generate thrust for the launch vehicle. Many launch vehicles use gas turbine engines with turbine and rotor assemblies. For example, a turbine includes a compressor section, a combustion section, and a turbine section in a sequential flow order, and the rotor assembly is configured as a fan assembly.

[0003] A fuel cell can be used as a power source for one or more propulsion systems. A compressor can be used to supply air to the fuel cell. However, the operation of the compressor may be limited by the altitude of the aircraft. Therefore, it is desirable to design an improved fuel cell system for operation within a certain altitude range. Attached Figure Description

[0004] The complete and feasible disclosure of this disclosure, including its best mode, is set forth in the specification with reference to the accompanying drawings, for those skilled in the art, wherein:

[0005] Figure 1 is a schematic diagram of an air carrier according to aspects of this disclosure.

[0006] Figure 2 is a schematic diagram of a thruster according to an aspect of this disclosure.

[0007] Figure 3 is a schematic diagram of a propulsion system including a fuel cell assembly according to aspects of this disclosure.

[0008] Figure 4 is a perspective view of the fuel cell of the fuel cell assembly of Figure 3 according to an exemplary aspect of the present disclosure.

[0009] Figure 5 is a schematic diagram of a propulsion system including a fuel cell assembly according to aspects of this disclosure.

[0010] Figure 6 is a schematic diagram of a propulsion system according to an aspect of this disclosure.

[0011] Figure 7 is a schematic diagram of a propulsion system according to an aspect of this disclosure.

[0012] Figure 8 is a schematic diagram of a propulsion system according to an aspect of this disclosure.

[0013] Figure 9 is a flowchart of a method for operating a system according to aspects of this disclosure.

[0014] Figure 10 is a flowchart of a method for operating a propulsion system according to aspects of this disclosure. Detailed Implementation

[0015] Reference will now be made in detail to the present embodiments of this disclosure, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerals and letter reference numerals to denote features in the drawings. Similar or analogous reference numerals in the drawings and description have been used to denote similar or analogous portions of this disclosure.

[0016] The term "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as superior or better than other implementations. Furthermore, unless explicitly stated otherwise, all embodiments described herein should be considered exemplary.

[0017] Unless the context clearly indicates otherwise, the singular forms “a,” “a,” and “the” include plural references.

[0018] In a context such as “at least one of A, B and C”, the term “at least one” means only A, only B, only C, or any combination of A, B and C.

[0019] The term "turbine" refers to a machine that includes one or more compressors, a heating section (e.g., a combustion section), and one or more turbines that together generate torque output.

[0020] The term "gas turbine engine" refers to an engine that has a turbine as its power source, in whole or in part. Examples of gas turbine engines include turbofan engines, turboprop engines, turbojet engines, turboshaft engines, and hybrid electric versions of one or more of these engines.

[0021] The term "combustion section" refers to any heat addition system used in a turbine. For example, the term combustion section can refer to a section including one or more of a knock combustion assembly, a rotating detonation combustion assembly, a pulse detonation combustion assembly, or other suitable heat addition assembly. In some example embodiments, the combustion section may include an annular burner, a can burner, a tubular burner, a vortex burner (TVC), or other suitable combustion systems, or combinations thereof.

[0022] 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.

[0023] Unless otherwise stated herein, the terms “connection,” “fixed,” “attached to,” etc., refer to both direct connection, fixation, or attachment, and indirect connection, fixation, or attachment via one or more intermediate components or features.

[0024] 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.

[0025] The term "electric motor" can generally refer to a machine having a stator and a rotor, with the rotor rotating relative to the stator. Additionally, an electric motor can be constructed in any suitable manner for converting mechanical power, such as from a turbine (e.g., a gas turbine engine), into electrical power, or vice versa. For example, an electric motor can be constructed as a synchronous reluctance motor; a permanent magnet motor, such as an internal permanent magnet motor and / or a spoked permanent magnet motor; or a closed-rotor slot induction motor. In this way, the motor can be operated to generate or utilize alternating current (AC) or direct current (DC) electricity. It will also be understood that the stator, rotor, or both can generally comprise one or more of the following: multiple coils or windings arranged in any suitable number of phases, one or more permanent magnets, one or more electromagnets, etc.

[0026] As will be discussed in more detail below, a fuel cell is an electrochemical device that converts the chemical energy from a fuel (such as hydrogen) into electrical energy through an electrochemical reaction between the fuel and an oxidant (such as oxygen contained in the atmosphere). Fuel cell systems can be advantageously used as energy supply systems because they can be considered environmentally superior and highly efficient compared to at least some existing systems. To improve system efficiency and fuel utilization and reduce external water consumption, fuel cell systems may include an anode recirculation loop. Since a single fuel cell can only generate about 1V of voltage, multiple fuel cells can be stacked together (which may be called a fuel cell stack) to generate the desired voltage. Fuel cells can include solid oxide fuel cells (SOFC), molten carbonate fuel cells (MCFC), phosphoric acid fuel cells (PAFC), and proton exchange membrane fuel cells (PEMFC), all of which are generally named after their respective electrolytes. Each of these fuel cells can offer specific benefits in the form of a preferred operating temperature range, power generation capacity, efficiency, etc.

[0027] This disclosure generally relates to fuel cell systems for aircraft. Fuel (e.g., hydrogen) and air (e.g., oxygen) are supplied to a fuel cell unit in the fuel cell system, and the fuel cell unit generates electrical energy through an electrochemical reaction between the fuel and air. The performance of the fuel cell unit may be affected by the altitude of the aircraft. For example, at lower altitudes, the fuel cell unit may require an increased supply of pressurized air compared to higher altitudes. Pressurized air can be supplied to the fuel cell unit via a compressor. However, typical compressors operate at limited pressure ratios and cannot operate above certain altitudes. Therefore, this disclosure provides fuel cell systems and methods for supplying air to the fuel cell unit at increased altitudes.

[0028] Referring now to the accompanying drawings, FIG1 is a schematic diagram of an air carrier 100 according to aspects of the present disclosure. The exemplary air carrier 100 of FIG1 is configured as an aircraft. The aircraft generally includes a fuselage 102 forming the main body of the carrier 100, a first wing 104 extending from the port side of the aircraft, and a second wing 106 extending from the starboard side of the aircraft. The first and second wings 104, 106 each extend laterally from the fuselage 102. The aircraft also includes a tail 108.

[0029] Additionally, the launch vehicle 100 includes a propulsion system 112, which includes one or more thrusters 114 and one or more power sources 116. The propulsion system 112 also includes a power distribution bus 118 that electrically connects the various components of the propulsion system 112.

[0030] Figure 2 is a schematic diagram of a thruster according to aspects of this disclosure. More specifically, the thruster of Figure 2 is configured as a gas turbine engine 120 that can be incorporated into an exemplary propulsion system 112 (such as one or more thrusters 114) of the carrier 100 of Figure 1. The gas turbine engine 120 includes a fan section 122 and a turbine 124 drivenly coupled to the fan section 122. The turbine 124 generally includes a compressor section 128, a combustion section 130, and a turbine section 132 arranged in a serial flow sequence, and one or more shafts 134 connecting one or more compressors of the compressor section 128 and one or more turbines of the turbine section 132. Furthermore, the fan section 122 is coupled to the turbine 124 via one or more shafts 134 through a gearbox 140. The gearbox 140 includes a plurality of gears for adjusting the rotational speed of the fan section 122 relative to the rotational speeds of one or more compressors of the compressor section 128 and one or more turbines of the turbine section 132.

[0031] In at least one example embodiment, the gas turbine engine 120 may be configured as a turbofan engine and includes an outer nacelle 126 that at least partially surrounds the fan section 122 and the turbine 124, as shown in FIG2. In other example embodiments, the gas turbine engine may be configured as a turboprop engine. For example, in such an embodiment, the fan section 122 may not be surrounded by the outer nacelle 126.

[0032] Furthermore, as shown in Figure 2, the gas turbine engine 120 also includes an electric motor 136 that can rotate together with one or more shafts 134 of the fan section 122. The electric motor 136 can be coupled to the fan section 122 in parallel with the turbine 124. Additionally, the electric motor 136 can be configured to receive power from the power distribution bus 118 to, for example, drive the fan of the fan section 122, as will be discussed in more detail below. Therefore, one or both of the turbine 124 and the electric motor 136 can drive the rotation of the fan section 122.

[0033] Figure 3 is a schematic diagram of a propulsion system 112 including a fuel cell assembly 300 according to aspects of the present disclosure. An exemplary fuel cell assembly 300 may be integrated into a vehicle 100 and used in conjunction with one or more thrusters, such as thruster 114. More specifically, the fuel cell assembly 300 may be incorporated into the propulsion system 112 of the vehicle 100 as one or more power sources 116. Thus, in some example embodiments, the vehicle 100 may include a plurality of fuel cell assemblies 300.

[0034] The fuel cell assembly 300 includes at least one fuel cell 305, at least one compressor 310, and at least one bypass valve 315 for controlling the flow of pressurized air 320 from the at least one compressor 310 to the at least one fuel cell 305. In at least one example embodiment, the bypass valve 315 may be a three-way valve in fluid communication with the at least one fuel cell 305, the at least one compressor 310, and the surrounding environment. The bypass valve 315 enables the compressor 310 to operate at a higher compressor ratio. For example, the compressor 310 may operate at a pressure ratio greater than or equal to 5.4. The at least one compressor 310 may be a centrifugal compressor. Such a centrifugal compressor can provide high power density, isentropic efficiency, and low noise. Furthermore, the at least one compressor 310 may be configured to operate at an altitude of at least 25,000 feet. For example, the altitude of the vehicle 100 including the fuel cell assembly 300 may be greater than or equal to 0 feet and less than or equal to 25,000 feet. More specifically, the at least one compressor 310 may be configured to operate at an altitude greater than or equal to 7,000 feet.

[0035] At least one fuel cell 305 includes a first fluid inlet 325 for receiving a stream of pressurized air 320 from at least one compressor 310. At least one fuel cell 305 also includes a second fluid inlet 330 configured to receive a stream of fuel 335 from a fuel source (not shown). For example, in some exemplary embodiments, the stream of fuel 335 may be a stream of hydrogen fuel.

[0036] In at least one example embodiment, at least one fuel cell 305 comprises multiple fuel cells stacked together and defining a fuel cell stack, as will be discussed with respect to Figure 4. Furthermore, at least one fuel cell 305 may have any suitable chemical composition. For example, at least one fuel cell 305 may include solid oxide fuel cells (SOFC), molten carbonate fuel cells (MCFC), phosphoric acid fuel cells (PAFC), and proton exchange membrane fuel cells (PEMFC), all of which are generally named after their respective electrolyte layers. Each of these fuel cells may offer specific benefits in the form of a preferred operating temperature range, power generation capacity, efficiency, etc.

[0037] As shown in Figure 3, the controller 340 can be operatively coupled to the fuel cell assembly 300. For example, the controller 340 can be operatively coupled to a bypass valve 315 for controlling the operation of the bypass valve 315. In at least one example embodiment, as shown in Figure 3, the controller 340 can be wirelessly connected to the bypass valve 315. In other example embodiments, the controller 340 can be operatively connected to the bypass valve 315 via one or more wired electrical connections.

[0038] The controller 340 may include one or more computing devices 342. The one or more computing devices 342 may include one or more processors 344 and one or more memory devices 346. The one or more processors 344 may include any suitable processing device, such as a microprocessor, microcontroller, integrated circuit, logic device, and / or other suitable processing device. The one or more memory devices 346 may include one or more computer-readable media, including but not limited to non-transitory computer-readable media, RAM, ROM, hard disk drives, flash drives, and / or other memory devices. The one or more memory devices 346 may store information accessible by the one or more processors 344, including computer-readable instructions 350 executable by the one or more processors 344 (e.g., method 900 described below with respect to FIG. 9). The memory devices 346 may also store data 348 accessible by the processors 344. Furthermore, the one or more computing devices 342 include a network interface 352 configured to communicate, for example, with a bypass valve 315 and other components of the gas turbine engine 120 (FIG. 2) and the carrier 100 (FIG. 1).

[0039] As described above, the bypass valve 315 is configured to control the flow of pressurized air 320 from at least one compressor 310 to at least one fuel cell 305. More specifically, the controller 340 may control the flow of pressurized air 320 to at least one fuel cell 305 via the bypass valve 315 based on the height of the vehicle 100. Therefore, the vehicle 100 may include a height sensor communicatively coupled to the controller 340 to determine the height of the vehicle 100.

[0040] In at least one example embodiment, at least one fuel cell 305 can receive an increased supply of pressurized air 320 from at least one compressor 310 at a lower altitude. Therefore, controller 340 can at least partially open bypass valve 315 based on the height of carrier 100 being less than or equal to a height threshold to increase the supply of pressurized air 320 from at least one compressor 310 to at least one fuel cell 305. Furthermore, the supply of pressurized air 320 to at least one fuel cell 305 can be reduced based on the height of carrier 100 exceeding a height threshold. For example, controller 340 can at least partially close bypass valve 315 based on the height of carrier 100 being greater than a height threshold to reduce the supply of pressurized air 320 from at least one compressor 310 to at least one fuel cell 305. The height threshold can be based on the type and capacity of at least one compressor 310 and at least one fuel cell 305.

[0041] Any portion of the pressurized air 320 not utilized by at least one fuel cell 305 (such as excess air 355) can be discharged from the fuel cell assembly 300. For example, as discussed above, at least one fuel cell 305 can receive a reduced amount of pressurized air 320 at altitudes exceeding a height threshold. Therefore, the controller 340 can operate the bypass valve 315 such that at least one fuel cell 305 is at least partially bypassed, and the excess air 355 can be discharged into the surrounding environment.

[0042] Additionally or alternatively, excess air 355 can be recirculated for use by at least one compressor 310. For example, the fuel cell assembly 300 may include a recirculation valve 360. The recirculation valve 360 ​​may be a three-way valve in fluid communication with a bypass valve 315, at least one compressor 310, and the ambient environment. As shown in FIG3, the recirculation valve 360 ​​may be downstream of the bypass valve 315 and upstream of at least one compressor 310. The recirculation valve 360 ​​may be configured to receive excess air 355 from the bypass valve 315 and supply the excess air 355 to at least one compressor 310 to generate pressurized air 320. Furthermore, the recirculation valve 360 ​​may receive ambient air 365 from the surrounding environment and supply the ambient air 365 to at least one compressor 310 to generate pressurized air 320. In other example embodiments, the recirculation valve 360 ​​may discharge at least a portion of the excess air 355 to the ambient environment.

[0043] In at least one example embodiment, the fuel cell assembly 300 is configured to supply power to a load 370. For example, an electrochemical reaction between a fuel 335 stream and a pressurized air 320 stream occurs within at least one fuel cell 305, providing an electrical power output. Therefore, the electrical power output from at least one fuel cell 305 can be supplied to the load 370. The load 370 may include a motor 136 as described with respect to FIG. 2. For example, the electrical power output from at least one fuel cell 305 can be provided to the motor 136 to drive the rotation of a fan section 122. Thus, as shown in FIG. 2, one or both of the motor 136 (supplying electrical power from the fuel cell assembly 300) and the turbine 124 can drive the rotation of the fan section 122.

[0044] Furthermore, a DC / DC converter 375 can be operatively connected between at least one fuel cell 305 of the fuel cell assembly 300 and a load 370. The fuel cell assembly 300 can use the DC / DC converter 375 to manage the electrical power output from at least one fuel cell 305 to provide a specified power output to the load 370.

[0045] In an additional example embodiment, at least a portion of the electrical power output from at least one fuel cell 305 may be supplied to at least one compressor 310. For example, a motor 380 may be operatively coupled to at least one compressor 310. The motor 380 may be configured to receive the electrical power output from at least one fuel cell 305 and convert the electrical power into mechanical rotational force to drive at least one compressor 310.

[0046] Figure 4 is a perspective view of at least one fuel cell 305 of the fuel cell assembly 300 of Figure 3 according to an exemplary aspect of the present disclosure. As discussed above with respect to Figure 3, at least one fuel cell 305 may include a fuel cell stack 400. For the depicted embodiment, the fuel cell stack 400 is configured as a PEM fuel cell stack having a plurality of proton exchange membrane (“PEM”) fuel cells.

[0047] The fuel cell stack 400 shown in Figure 4 includes a housing 405, which has a combustion outlet side 410 and a side 415 opposite to the combustion outlet side 410, a fuel and air inlet side 420 and a side 425 opposite to the fuel and air inlet side 420, and sides 430 and 435. Sides 430, 425 and 415 are not visible in the perspective view of Figure 4.

[0048] As described above, the fuel cell stack 400 includes, for example, a plurality of fuel cells “stacked” side-by-side from one end of the fuel cell stack 400 (e.g., fuel and air inlet side 420) to the other end of the fuel cell stack 400 (e.g., side 425). The combustion outlet side 410 includes a plurality of combustion outlets 440 defined by each fuel cell in the fuel cell stack 400. During operation, combustion gases 455 are directed from the combustion outlets 440 and exit the housing 405. The combustion gases 455 are generated using air and fuel not consumed by the fuel cells within the housing 405 of the fuel cell stack 400.

[0049] The fuel and air inlet side 420 includes one or more fuel inlets and one or more air inlets, such as a first fluid inlet 325 and a second fluid inlet 330. Optionally, the one or more fuel inlets and one or more air inlets may be on the other side of the housing 405. Each of the one or more fuel inlets (such as the second fluid inlet 330) is fluidly connected to a fuel source (such as one or more pressurized containers containing hydrogen gas) for the fuel cell stack 400. Each of the one or more air inlets (such as the first fluid inlet 325) is fluidly connected to an air source (such as at least one compressor 310 (FIG. 3)) for the fuel cell. The first fluid inlet 325 and the second fluid inlet separately receive air and fuel from external air and fuel sources, and separately direct the air and fuel into the fuel cell.

[0050] Figure 5 is a schematic diagram of a propulsion system 112 including a fuel cell assembly 500 according to aspects of the present disclosure. The fuel cell assembly 500 may be similar to or analogous to the exemplary fuel cell assembly 300 discussed above with respect to Figure 3. For example, the fuel cell assembly 500 includes at least one fuel cell 305, at least one compressor 310, at least one bypass valve 315 for controlling the flow of pressurized air 320 from at least one compressor 310 to at least one fuel cell 305, and a controller 340. The fuel cell assembly 500 is also configured to supply power to a load 370. Furthermore, the fuel cell assembly 500 may be incorporated as one or more power sources 116 into the propulsion system 112 of the vehicle 100. Thus, in some example embodiments, the vehicle 100 may include multiple fuel cell assemblies 500.

[0051] As discussed above with respect to Figure 3, bypass valve 315 is configured to control the flow of pressurized air 320 from at least one compressor 310 to at least one fuel cell 305. More specifically, controller 340 may control the flow of pressurized air 320 to at least one fuel cell 305 via bypass valve 315 based on the altitude of vehicle 100. In at least one example embodiment, as shown in Figure 5, bypass valve 315 may be configured to direct at least a portion of excess air 355 not utilized by at least one fuel cell 305 to vehicle 100 for aircraft utilities. Aircraft utilities may include low-pressure loads.

[0052] As shown in Figure 5, at least one compressor 310 can receive incoming air (such as ambient air 365) from the surrounding environment to generate pressurized air 320. In some example embodiments, a turbocharger 503, a supercharger 505, or both turbocharger 503 and supercharger 505 may be fluidly connected between the turbine 124 and at least one compressor 310, as indicated by arrows 504 and 508. The turbocharger 503 and supercharger 505 are configured to increase the incoming air from the turbine 124 to at least one compressor 310 to generate a pressurized air 320 flow. Therefore, the turbocharger 503 and supercharger 505 can recover hot air from the turbine 124 and use the energy from this hot air to increase the pressurized air 320 flow to at least one fuel cell 305 of the fuel cell system 500. Furthermore, turbocharger 503 and supercharger 505 can recover hot air to support the operation of at least one compressor 310 and reduce the amount of electrical power required for motor 380 to drive at least one compressor 310. Additionally or alternatively, turbocharger 503 and supercharger 505 can support the operation of at least one compressor 310, thereby eliminating the need for motor 380 in some example embodiments. For example, enthalpy can be obtained from turbine 124, exhaust gas from at least one fuel cell, or both, to support the operation of at least one compressor 310, making the at least one compressor 310 require almost no electrical power from motor 380.

[0053] In at least one example embodiment, as shown in FIG5, the motor 380 may be drivably coupled to the turbine 124. In such an embodiment, the motor 380 may be configured to convert mechanical power from the turbine 124 (such as from one or more shafts 134 (FIG. 2)) into electrical power that can be utilized by at least one compressor 310.

[0054] Figure 6 is a schematic diagram of a propulsion system 612 according to aspects of this disclosure. The exemplary propulsion system 612 can be integrated into vehicle 100 and used with one or more thrusters, such as thruster 114. More specifically, propulsion system 612 can be incorporated into vehicle 100 as propulsion system 112.

[0055] The propulsion system 612 includes a fuel cell assembly 600 and an air management system 610 in fluid communication with the fuel cell assembly 600. The fuel cell assembly 600 includes a plurality of fuel cells 605. The plurality of fuel cells 605 of the fuel cell assembly 600 can have any suitable chemical composition. For example, the plurality of fuel cells can include solid oxide fuel cells (SOFC), molten carbonate fuel cells (MCFC), phosphoric acid fuel cells (PAFC), and proton exchange membrane fuel cells (PEMFC), all of which are generally named after their respective electrolyte layers. Each of these fuel cells can have specific benefits in the form of a preferred operating temperature range, power generation capacity, efficiency, etc. Furthermore, the plurality of fuel cells 605 can include the plurality of fuel cell stacks 400 discussed above with respect to Figure 4.

[0056] Each of the plurality of fuel cells 605, or fuel cell stack, includes a first fluid inlet 625 for receiving a stream of pressurized air 620 from an air management system 610 and a second fluid inlet 630 for receiving a stream of fuel 635 from a fuel source (not shown). In at least one example embodiment, the fuel 635 stream may be a hydrogen fuel stream.

[0057] As shown in Figure 6, the air management system 610 may be in fluid communication with the turbine 124. More specifically, the air management system 610 may be in fluid communication with the compressor section 128 of the turbine 124. The air management system 610 includes a control valve 615 and a distribution manifold 623. The control valve 615 is configured to control the flow of pressurized air 620 from the compressor section 128 to the distribution manifold 623. The distribution manifold 623 is configured to distribute the flow of pressurized air 620 to a plurality of fuel cells 605. For example, the distribution manifold 623 may be configured to distribute the flow of pressurized air 620 to each of the plurality of fuel cells 605, or to a fuel cell stack.

[0058] In other example embodiments, control valve 615 may directly control the flow of pressurized air 620 from compressor section 128, without including distribution manifold 623. In such example embodiments, one or more of control valves 615 may be in direct fluid communication with each of the plurality of fuel cells 605 or fuel cell stacks and compressor section 128.

[0059] Controller 640 can be operatively coupled to control valve 615 for controlling the operation of control valve 615. In at least one example embodiment, as shown in FIG6, controller 640 can be wirelessly connected to control valve 615. In other example embodiments, controller 640 can be operatively connected to control valve 615 via one or more wired electrical connections. Furthermore, controller 640 can be similar to or analogous to the exemplary controller 340 discussed above with respect to FIGS. 3 and 5.

[0060] As described above, control valve 615 is configured to control the flow of pressurized air 620 to the plurality of fuel cells 605 via distribution manifold 623. More specifically, controller 640 may control the flow of pressurized air 620 to distribution manifold 623 and the plurality of fuel cells 605 via control valve 615 based on the height of vehicle 100. Vehicle 100 may include a height sensor communicatively coupled to controller 640 to determine the height of vehicle 100 and communicate the determined height to controller 640. In at least one example embodiment, the height of vehicle 100 may be greater than or equal to 0 feet and less than or equal to 25,000 feet.

[0061] In some example embodiments, the fuel cell assembly 600 may require an increased supply of pressurized air 620 from the compressor section 128 at lower altitudes, such as below 25,000 feet. Therefore, the controller 640 may at least partially open the control valve 615 to increase the supply of pressurized air 620 to the distribution manifold 623 for distribution to the multiple fuel cells 605 based on the carrier 100's altitude being less than or equal to an altitude threshold (such as less than or equal to 25,000 feet). Furthermore, the supply of pressurized air 620 to the fuel cell assembly 600 may be reduced based on the carrier's altitude exceeding an altitude threshold. For example, the controller 640 may at least partially close the control valve 615 to reduce the flow of pressurized air 620 from the compressor section 128 to the distribution manifold 623 for distribution to the multiple fuel cells 605 based on the carrier 100's altitude exceeding an altitude threshold. The altitude threshold may be based on the type and capacity of the compressor section 128 and the multiple fuel cells 605.

[0062] Referring again to Figure 6, the fuel cell assembly 600 is configured to supply power to a load 670. For example, an electrochemical reaction occurs between a fuel stream 635 and a pressurized air stream 620 within a plurality of fuel cells 605, providing an electrical power output. The electrical power output from the plurality of fuel cells 605 can be supplied to the load 670. The load 670 may include a motor 136 as described with respect to Figure 2. For example, the electrical power output from the fuel cell assembly 600 can be provided to the motor 136 to drive the rotation of the fan section 122. Thus, as shown in Figure 2, one or both of the motor 136 (supplying electrical power from the fuel cell assembly 600) and the turbine 124 can drive the rotation of the fan section 122.

[0063] Furthermore, the DC / DC converter 675 can be operatively connected between multiple fuel cells 605 and a load 670. The DC / DC converter 675 can be configured to provide a specified power output from the multiple fuel cells 605 to the load 670.

[0064] Figure 7 is a schematic diagram of a propulsion system 712 including a fuel cell assembly 700 according to aspects of the present disclosure. An exemplary propulsion system 712 can be incorporated as a propulsion system 112 into the vehicle 100 of Figure 1. Furthermore, the fuel cell assembly 700 can be incorporated as one or more power sources 116 into the propulsion system 112 of the vehicle 100.

[0065] The fuel cell assembly 700 includes at least one fuel cell 705, an air management system 723, and an airflow supply unit 702. The airflow supply unit 702 includes a fuel cell compressor 710 in fluid communication with the air management system 723 and a fuel cell turbine 755 drivenly coupled to the fuel cell compressor 710. The fuel cell compressor 710 can be a centrifugal compressor. Such a centrifugal compressor can provide high power density, isentropic efficiency, and low noise. Furthermore, the fuel cell compressor 710 can be configured to operate at an altitude of less than or equal to 25,000 feet. For example, the altitude of the vehicle 100 including the fuel cell assembly 700 can be greater than or equal to 0 feet and less than or equal to 25,000 feet.

[0066] A fuel cell turbine 755 may be drivably coupled to a fuel cell compressor 710 via one or more shafts 760. In at least one example embodiment, the fuel cell turbine 755 is configured to receive exhaust gas 765 from at least one fuel cell 705 to drive the rotation of the fuel cell turbine 755. Additionally or alternatively, the fuel cell turbine 755 may receive exhaust gas from a propulsion unit 114 (such as a gas turbine engine 120) to drive the rotation of the fuel cell turbine 755. In an additional example embodiment, the fuel cell compressor 710 may be drivably coupled to a turbine section 132 of a turbine 124 (FIG. 2) to drive the rotation of the fuel cell compressor 710. The rotation of the fuel cell turbine 755 drives the rotation of the fuel cell compressor 710 via one or more shafts 760 to generate a stream of pressurized air 720.

[0067] At least one fuel cell 705 may include multiple fuel cells. The multiple fuel cells in at least one fuel cell 705 may have any suitable chemical composition. For example, the multiple fuel cells may include solid oxide fuel cells (SOFC), molten carbonate fuel cells (MCFC), phosphoric acid fuel cells (PAFC), and proton exchange membrane fuel cells (PEMFC), all of which are generally named after their respective electrolyte layers. Each of these fuel cells may have specific benefits in the form of a preferred operating temperature range, power generation capacity, efficiency, etc. Furthermore, at least one fuel cell 705 may include the multiple fuel cell stacks 400 discussed above with respect to Figure 4.

[0068] As shown in Figure 7, each fuel cell or fuel cell stack in at least one fuel cell 705 includes a first fluid inlet 725 for receiving a stream of pressurized air 720 from an air management system 723 and a second fluid inlet 730 for receiving a stream of fuel 735 from a fuel source (not shown). In at least one example embodiment, the fuel 735 stream may be a hydrogen fuel stream.

[0069] As shown in Figure 7, the air management system 723 may be in fluid communication with the air supply unit 702. More specifically, the air management system 723 may be in fluid communication with the fuel cell compressor 710 and is configured to receive a pressurized air 720 flow from the fuel cell compressor 710. A guide vane assembly 715 may be disposed upstream of the fuel cell compressor 710 and includes a plurality of inlet guide vanes. The guide vane assembly 715 may include an actuator 745 configured to change the pitch angle of each of the plurality of inlet guide vanes. Modifying the pitch angle of the plurality of inlet guide vanes controls the amount of air 718 supplied to the fuel cell compressor 710 to generate the pressurized air 720 flow. For example, the fuel cell compressor 710 may require an increased supply of air 718 at lower altitudes and a reduced supply of air 718 at higher altitudes. More specifically, the supply of air 718 to the fuel cell compressor 710 can be controlled by adjusting the pitch angle of the plurality of inlet guide vanes of the guide vane assembly 715 based on the height of the carrier 100 relative to an altitude threshold. For example, the airflow 718 to the fuel cell compressor 710 can be reduced based on the height of the carrier 100 being greater than a height threshold, and the airflow 718 to the fuel cell compressor 710 can be increased based on the height of the carrier 100 being less than or equal to a height threshold. The height threshold can be based on the type and capacity of the fuel cell compressor 710 and at least one fuel cell 705.

[0070] Furthermore, the controller 740 can be operatively coupled to the actuator 745 of the guide vane assembly 715. For example, the controller 740 can drive the operation of the actuator 745 such that the actuator 745 adjusts the pitch angle of a plurality of inlet guide vanes of the guide vane assembly 715 based on the height of the carrier 100. In at least one example embodiment, the controller 740 is configured to rotate the plurality of inlet guide vanes to a first position based on a height less than or equal to a height threshold, and the controller 740 is configured to rotate the plurality of inlet guide vanes to a second position based on a height exceeding the height threshold.

[0071] Additionally, the carrier 100 may include a height sensor communicatively coupled to the controller 740 for communicating the height of the carrier 100 to the controller 740. In at least one example embodiment, as shown in FIG7, the controller 740 may be wirelessly connected to the actuator 745 of the guide vane assembly 715. In other example embodiments, the controller 740 may be operatively connected to the actuator 745 of the guide vane assembly 715 via one or more wired electrical connections. Furthermore, the controller 740 may be similar to or analogous to the exemplary controllers 340, 640 discussed above with respect to FIGS. 3, 5, and 6.

[0072] As shown in Figure 7, the air management system 723 may be in fluid communication with the fuel cell compressor 710. More specifically, the air management system 723 is downstream of the fuel cell compressor 710 and upstream of at least one fuel cell 705. The air management system 723 may include a distribution manifold configured to distribute a stream of pressurized air 720 to at least one fuel cell 705. For example, the distribution manifold may be configured to distribute a stream of pressurized air 720 to each fuel cell or fuel cell stack in at least one fuel cell 705.

[0073] Referring again to Figure 7, the fuel cell assembly 600 is configured to supply power to a load 770. For example, an electrochemical reaction between a fuel stream 735 and a pressurized air stream 720 occurs within at least one fuel cell 705, providing an electrical power output. The electrical power output from at least one fuel cell 705 can be supplied to the load 770. The load 770 may include a motor 136 as described with respect to Figure 2. For example, the electrical power output from at least one fuel cell 705 can be provided to the motor 136 to drive the rotation of the fan section 122. Thus, as shown in Figure 2, one or both of the motor 136 (supplying electrical power from the fuel cell assembly 700) and the turbine 124 can drive the rotation of the fan section 122.

[0074] Furthermore, a DC / DC converter 775 can be operatively connected between the fuel cell assembly 600 and the load 770. The DC / DC converter 775 can be configured to provide a specified power output from at least one fuel cell 705 to the load 770.

[0075] Figure 8 is a schematic diagram of a propulsion system 812 including a fuel cell assembly 800 according to aspects of the present disclosure. An exemplary propulsion system 812 can be incorporated as a propulsion system 112 into the vehicle 100 of Figure 1. Alternatively, the fuel cell assembly 800 can be incorporated as one or more power sources 116 into the propulsion system 112 of the vehicle 100. Furthermore, the propulsion system 812 and the fuel cell assembly 800 can be similar to or analogous to the propulsion system 712 and fuel cell assembly 700 discussed with respect to Figure 7.

[0076] For example, fuel cell assembly 800 includes at least one fuel cell 805, an air management system 838, and an airflow supply unit 802. The airflow supply unit 802 includes a fuel cell compressor 810 in fluid communication with the air management system 838 and a fuel cell turbine 855 drivenly coupled to the fuel cell compressor 810. The fuel cell compressor 810 may be a centrifugal compressor. Such a centrifugal compressor can provide high power density, isentropic efficiency, and low noise. Furthermore, the fuel cell compressor 810 may be configured to operate at an altitude of at least 25,000 feet. For example, the altitude of the vehicle 100 including the fuel cell assembly 800 may be greater than or equal to 0 feet and less than or equal to 25,000 feet.

[0077] A fuel cell turbine 855 may be drivably coupled to a fuel cell compressor 810 via one or more shafts 860. In at least one example embodiment, the fuel cell turbine 855 is configured to receive exhaust gas 865 from at least one fuel cell 805 to drive the rotation of the fuel cell turbine 855. Additionally or alternatively, the fuel cell turbine 855 may receive exhaust gas from a propulsion unit 114 (such as a gas turbine engine 120) to drive the rotation of the fuel cell turbine 855. In an additional example embodiment, the fuel cell compressor 810 may be drivably coupled to a turbine section 132 of a turbine 124 (FIG. 2) to drive the rotation of the fuel cell compressor 810. The rotation of the fuel cell turbine 855 drives the rotation of the fuel cell compressor 810 via one or more shafts 860 to generate a stream of pressurized air 820.

[0078] At least one fuel cell 805 may include multiple fuel cells. The multiple fuel cells in at least one fuel cell 805 may have any suitable chemical composition. For example, the multiple fuel cells may include solid oxide fuel cells (SOFC), molten carbonate fuel cells (MCFC), phosphoric acid fuel cells (PAFC), and proton exchange membrane fuel cells (PEMFC), all of which are generally named after their respective electrolyte layers. Each of these fuel cells may have specific benefits in the form of a preferred operating temperature range, power generation capacity, efficiency, etc. Furthermore, at least one fuel cell 805 may include the multiple fuel cell stacks 400 discussed above with respect to Figure 4.

[0079] As shown in Figure 8, each fuel cell or fuel cell stack in at least one fuel cell 805 includes a first fluid inlet 825 for receiving a stream of pressurized air 820 from an air management system 838 and a second fluid inlet 830 for receiving a stream of fuel 835 from a fuel source (not shown). In at least one example embodiment, the fuel 835 stream may be a hydrogen fuel stream.

[0080] As shown in Figure 8, the air management system 838 includes a distribution manifold 823 in fluid communication with at least one fuel cell 805 and an air supply unit 843. In at least one example embodiment, the air supply unit 843 may be removable and replaceable within the vehicle 100. In some example embodiments, the air supply unit 843 may be refillable.

[0081] In at least one example embodiment, the air supply unit 843 is an air tank for storing at least a portion of the pressurized air 820. The air supply unit 843 can allow for a reduction in the size of the fuel cell compressor 810 used to supply a stream of pressurized air 820 to at least one fuel cell 805. For example, the size of the fuel cell compressor 810 can be reduced because the air supply unit 843 provides an additional source of pressurized air 820, allowing the fuel cell compressor 810 to supply less pressurized air 820 required by at least one fuel cell 805.

[0082] Additionally or alternatively, the air supply unit 843 includes an oxygen tank for storing oxygen. Adding oxygen to the pressurized air stream 820 can improve the operation of at least one fuel cell 805. For example, increasing the oxygen content of the pressurized air stream 820 reduces nitrogen buildup in at least one fuel cell 805. This reduction in nitrogen can improve the durability of at least one fuel cell 805.

[0083] An air management system 838 is configured to supply pressurized air 820, oxygen, or both from an air supply unit 843 to a distribution manifold 823. For example, the air supply unit 843 may supply pressurized air 820, oxygen, or both during operation of the vehicle 100. Therefore, the air supply unit 843 can accommodate fluctuations in the pressurized air 820 flow from at least one fuel cell 805, such as fluctuations in the pressurized air 820 flow from the fuel cell compressor 810. The distribution manifold 823 is configured to distribute the pressurized air 820 flow, oxygen, or both to each cell or fuel cell stack in at least one fuel cell 805.

[0084] Additionally or alternatively, the air management system 838 is configured to receive a stream of pressurized air 820 from the fuel cell compressor 810 of the air flow supply unit 802. The fuel cell compressor 810 may be similar to or analogous to the fuel cell compressor 710 discussed above with respect to FIG. 7. For example, a guide vane assembly 815 may be disposed upstream of the fuel cell compressor 810 and include a plurality of inlet guide vanes. The guide vane assembly 815 may also include an actuator 845 configured to change the pitch angle of each of the plurality of inlet guide vanes, thereby controlling the amount of air 718 supplied to the fuel cell compressor 810 to generate the stream of pressurized air 820, as discussed above with respect to FIG. 7. Furthermore, in some example embodiments, the stream of pressurized air 820 from the fuel cell compressor 810 may be used to refill the air supply unit 843.

[0085] Referring again to Figure 8, controller 840 may be operatively coupled to air supply unit 843 for controlling the flow of pressurized air 820, oxygen, or both to distribution manifold 823 and at least one fuel cell 805. Furthermore, controller 840 may be operatively coupled to actuator 845 of guide vane assembly 815. For example, controller 840 may drive actuator 845 such that actuator 845 adjusts the pitch angle of multiple inlet guide vanes of guide vane assembly 815 based on the height of carrier 100. Carrier 100 may include a height sensor communicatively coupled to controller 840 for communicating the height of carrier 100 to controller 840.

[0086] In at least one example embodiment, as shown in FIG8, the controller 840 may be wirelessly connected to the air supply unit 843, the actuator 845 of the guide vane assembly 815, or both. In other example embodiments, the controller 840 may be operatively connected to the air supply unit 843, the actuator 845 of the guide vane assembly 815, or both via one or more wired electrical connections. Furthermore, the controller 840 may be similar to or analogous to the exemplary controllers 340, 640, 740 discussed above with respect to FIG3 and FIG5-7.

[0087] Referring again to Figure 8, the fuel cell assembly 800 is configured to supply power to a load 870. For example, an electrochemical reaction between a fuel stream 835 and a pressurized air stream 820 occurs within at least one fuel cell 805, providing an electrical power output. The electrical power output from at least one fuel cell 805 can be supplied to the load 870. The load 870 may include a motor 136 as described with respect to Figure 2. For example, the electrical power output from at least one fuel cell 805 can be provided to the motor 136 to drive the rotation of the fan section 122. Thus, as shown in Figure 2, one or both of the motor 136 (supplying electrical power from the fuel cell assembly 800) and the turbine 124 can drive the rotation of the fan section 122.

[0088] Furthermore, a DC / DC converter 875 can be operatively connected between at least one fuel cell 805 and a load 870. The DC / DC converter 875 can be configured to provide a specified power output from at least one fuel cell 805 of the fuel cell assembly 800 to the load 870.

[0089] Figure 9 is a flowchart of a method 900 for an operation advancement system according to aspects of this disclosure. Method 900 is shown as a collection of boxes in a logic flowchart, representing operations that can be implemented in hardware, software, or a combination thereof. For example, method 900 can be implemented by the exemplary controllers 340, 640, 740, and 840 discussed above with respect to Figures 3 and 5-8. The order of the described method 900 is not intended to be construed as limiting, and any number of the described boxes can be combined in any order to implement the exemplary methods disclosed herein or equivalent alternative methods. Furthermore, without departing from the spirit and scope of the subject matter described herein, certain boxes can be removed from the exemplary methods, or certain boxes can be enhanced by additional boxes having additional functionality.

[0090] In at least one example embodiment, method 900 includes determining the altitude of the aircraft at 905. For example, the altitude of carrier 100 (FIG. 1) may be determined at 905. In at least one example embodiment, carrier 100 includes an altitude sensor for detecting the altitude of carrier 100 and communicating the detected altitude to one or more of exemplary controllers 340, 640, 740, 840.

[0091] Method 900 proceeds to compare the height determined at 905 at 910 with a height threshold. If, at 910, the determined height is less than or equal to the height threshold, then method 900 proceeds to increase the pressurized airflow at 915. Increasing the pressurized airflow at 915 may include increasing the pressurized airflow 320, 620, 720, 720 to the exemplary fuel cell assembly 300, 500, 600, 700, 800, as discussed above with respect to Figures 3 and 5-8. If, at 910, the determined height is less than or equal to the height threshold, then method 900 proceeds to decrease or maintain the pressurized airflow at 920. For example, the pressurized airflow 320, 620, 720, 720, 720 to the exemplary fuel cell assembly 300, 500, 600, 700, 800 may be decreased or maintained, as discussed above with respect to Figures 3 and 5-8.

[0092] After increasing the pressurized airflow at 915 or decreasing or maintaining the pressurized airflow at 920, method 900 returns to determining the altitude of the aircraft at 905. Therefore, according to method 900, pressurized airflows 320, 620, 720, 720, 720 to exemplary fuel cell assemblies 300, 500, 600, 700, 800 can be continuously managed, such as via exemplary controllers 340, 640, 740, 840.

[0093] Therefore, this disclosure provides various systems and methods for supplying pressurized air to fuel cell systems in aircraft carriers to operate at increased altitudes. For example, the fuel cell systems described herein can operate at altitudes up to at least 25,000 feet.

[0094] Figure 10 is a flowchart of a method 1000 for operating a propulsion system according to aspects of this disclosure. For example, method 1000 may be implemented by exemplary controllers 340, 640, 740, 840 discussed above with respect to Figures 3 and 5-8.

[0095] In at least one example embodiment, method 1000 includes receiving data indicating the altitude of an aircraft at 1005, comparing the data indicating the altitude of the aircraft with an altitude threshold at 1010, and managing pressurized airflow to a fuel cell assembly at 1015 based on the received data indicating the altitude of the aircraft and the altitude threshold.

[0096] Receiving altitude data for the indicated aircraft at 1005 may include receiving altitude data for the carrier 100. For example, receiving altitude data for the indicated aircraft at 1005 may include determining the altitude of the carrier 100. In at least one example embodiment, the carrier 100 includes an altitude sensor to determine the altitude of the carrier 100. Furthermore, comparing the altitude data for the indicated aircraft at 1010 includes comparing the determined altitude of the carrier 100 with an altitude threshold.

[0097] At point 1015, the pressurized airflow to the fuel cell assembly is managed based on the received data indicating the aircraft's altitude and an altitude threshold. This includes managing the pressurized airflow 320, 620, 720, 720, 720, 720 to the exemplary fuel cell assemblies 300, 500, 600, 700, and 800, respectively, as discussed above with reference to Figures 3 and 5-8. For example, the pressurized airflow 320, 620, 720, 720, 720 to the exemplary fuel cell assemblies 300, 500, 600, 700, and 800 can be increased based on an altitude less than or equal to an altitude threshold. Conversely, the pressurized airflow 320, 620, 720, 720, 720 to the exemplary fuel cell assemblies 300, 500, 600, 700, and 800 can be decreased or maintained based on an altitude greater than an altitude threshold. Furthermore, as discussed with respect to Figures 3 and 5-8, managing the pressurized airflow to the fuel cell assembly at 1015 based on the received data indicating the altitude of the aircraft and an altitude threshold may include controlling a bypass valve 315 with controller 340, controlling a control valve 615 with controller 640, controlling an actuator 745 and multiple inlet guide vanes of the guide vane assembly 715 with controller 740, and controlling an actuator 845 and multiple inlet guide vanes of the guide vane assembly 815 with controller 740.

[0098] Therefore, this disclosure provides a fuel cell system for operating an aircraft at increased altitudes (such as greater than or equal to 0 feet and less than or equal to 25,000 feet). For example, the fuel cell system may include a bypass valve that enables the compressor of the fuel cell system to operate at a higher compressor ratio. Additionally or alternatively, the fuel cell system may include a turbocharger and / or a supercharger to support the operation of the compressor. In some example embodiments, the fuel cell system may also receive a pressurized airflow from the aircraft's turbine to support the operation of the fuel cell system. Furthermore, the fuel cell system may include a fuel cell turbine and a fuel cell compressor for supplying pressurized air to the fuel cell. In such example embodiments, a guide vane assembly may control the air supply to the fuel cell compressor. In further example embodiments, the fuel cell system may include an air supply unit for supplying at least a portion of the pressurized air or oxygen to the fuel cell of the fuel cell system.

[0099] Further details are provided by the following topics:

[0100] A propulsion system for an aircraft includes: a fan section including a fan; a turbine including a compressor section, a combustion section, and a turbine section arranged in a serial flow sequence; at least one motor, wherein one or both of the turbine and the at least one motor are configured to drive rotation of the fan of the fan section; a fuel cell assembly configured to power the motor, the fuel cell assembly including at least one fuel cell, a first fluid inlet for receiving a pressurized airflow, and a second fluid inlet for receiving a fuel flow; and a controller including a memory and one or more processors, the memory storing instructions that, when executed by the one or more processors, cause the propulsion system to perform a plurality of operations, the plurality of operations including: receiving data indicating the altitude of the aircraft; and managing the pressurized airflow to the fuel cell assembly in response to the received data indicating the altitude of the aircraft.

[0101] According to any of the preceding clauses, the propulsion system wherein receiving data indicating the altitude of the aircraft includes determining the altitude of the aircraft and comparing the determined altitude with an altitude threshold.

[0102] According to any of the preceding clauses, the propulsion system wherein receiving data indicating the altitude of the aircraft includes receiving data indicating that the altitude is less than or equal to an altitude threshold, and wherein managing the pressurized airflow to the fuel cell assembly includes increasing the pressurized airflow to the fuel cell assembly based on the altitude being less than or equal to the altitude threshold.

[0103] According to any of the preceding clauses, the propulsion system wherein receiving data indicating the altitude of the aircraft includes receiving data indicating that the altitude is greater than an altitude threshold, and wherein managing the pressurized airflow to the fuel cell assembly includes reducing the pressurized airflow to the fuel cell assembly based on the altitude being greater than the altitude threshold.

[0104] The propulsion system according to any of the foregoing clauses, wherein the fuel cell assembly includes at least one compressor and at least one bypass valve, the at least one bypass valve being in fluid communication with the compressor and the first fluid inlet.

[0105] According to any of the preceding clauses, the altitude of the aircraft is greater than or equal to 0 feet and less than or equal to 25,000 feet.

[0106] According to any of the preceding clauses, the propulsion system wherein the controller is operatively coupled to the at least one bypass valve and configured to activate the at least one bypass valve based on the height being less than or equal to a height threshold, and to deactivate the at least one bypass valve based on the height exceeding the height threshold.

[0107] The propulsion system according to any of the foregoing clauses further includes a recirculation valve downstream of the at least one bypass valve and upstream of the at least one compressor.

[0108] According to any of the preceding clauses, the propulsion system wherein the fuel cell assembly includes a supercharger or a turbocharger, the supercharger or the turbocharger being in fluid communication with the at least one compressor and being upstream of the at least one compressor.

[0109] According to any of the preceding clauses, the propulsion system includes a first motor, and the fuel cell assembly includes a second motor mechanically coupled to the at least one compressor to drive the rotation of the at least one compressor.

[0110] According to any of the preceding clauses, the propulsion system wherein the turbine section is in fluid communication with and downstream of the fluid outlet of the fuel cell.

[0111] According to any of the preceding clauses, the propulsion system wherein the turbine section is configured to receive at least a portion of the exhaust gas discharged from the turbine section.

[0112] According to any of the preceding clauses, the propulsion system wherein the fuel cell assembly includes: an air management system in fluid communication with the at least one fuel cell and the compressor section, the air management system being downstream of the compressor section and upstream of the at least one fuel cell; and a control valve in fluid communication with the air management system and the compressor section, the control valve being downstream of the compressor section and upstream of the at least one fuel cell.

[0113] According to any of the preceding clauses, the propulsion system further includes a distribution manifold in fluid communication with the control valve and the at least one fuel cell, the distribution manifold being configured to distribute the pressurized airflow to the at least one fuel cell; and the controller is operatively coupled to the control valve and configured to activate the control valve based on the height being less than or equal to a height threshold, and to deactivate the control valve based on the height exceeding the height threshold.

[0114] According to any of the preceding clauses, the propulsion system further includes: an air management system in fluid communication with the at least one fuel cell; and an airflow supply unit in fluid communication with the air management system, the airflow supply unit including: a fuel cell compressor in fluid communication with the air management system; a fuel cell turbine drivenly coupled to the fuel cell compressor; a guide vane assembly having a plurality of inlet guide vanes and disposed upstream of the fuel cell compressor; and an actuator operable to change the pitch angle of each of the plurality of inlet guide vanes; wherein the controller is operably coupled to the actuator; and wherein the pressurized airflow managed to the fuel cell assembly includes rotating one or more of the plurality of inlet guide vanes via the actuator.

[0115] According to any of the preceding clauses, the propulsion system wherein: the controller is configured to rotate the plurality of inlet guide vanes to a first position based on the height being less than or equal to a height threshold; and the controller is configured to rotate the plurality of inlet guide vanes to a second position based on the height exceeding the height threshold.

[0116] The propulsion system according to any of the foregoing clauses, wherein the fuel cell assembly includes: an air management system in fluid communication with the at least one fuel cell; and an air flow supply unit configured to supply the pressurized air flow to the fuel cell assembly.

[0117] The propulsion system according to any of the foregoing clauses, wherein the air supply unit includes one or both of an air tank and an oxygen tank for storing the pressurized air.

[0118] According to any of the preceding clauses, the propulsion system comprises a plurality of fuel cells stacked together to form a fuel cell stack.

[0119] The propulsion system according to any of the foregoing clauses, wherein the plurality of fuel cells include proton exchange membrane fuel cells (PEMFC).

[0120] A propulsion system for an aircraft includes: a fan section including a fan; a turbine including a compressor section, a combustion section, and a turbine section arranged in a serial flow sequence; at least one motor, wherein one or both of the turbine and the at least one motor are configured to drive rotation of the fan in the fan section; a fuel cell assembly configured to power the motor, the fuel cell assembly including a plurality of fuel cells; and an air management system in fluid communication with the plurality of fuel cells and the compressor section, the air management system including a control valve operable to distribute airflow from the compressor section through the air management system and to the plurality of fuel cells.

[0121] According to any of the preceding clauses, the propulsion system wherein the air management system further includes a distribution manifold in fluid communication with the control valve and the plurality of fuel cells, the distribution manifold being configured to distribute the airflow to the plurality of fuel cells.

[0122] The propulsion system according to any of the foregoing clauses further includes a controller, the controller including a memory and one or more processors, the memory storing instructions that, when executed by the one or more processors, cause the propulsion system to perform a plurality of operations, the plurality of operations including: receiving data indicating the altitude of the aircraft, and managing pressurized airflow to the fuel cell assembly in response to the received data indicating the altitude of the aircraft.

[0123] According to any of the preceding clauses, the propulsion system wherein receiving data indicating the altitude of the aircraft includes determining the altitude of the aircraft and comparing the determined altitude with an altitude threshold.

[0124] According to any of the preceding clauses, the propulsion system wherein the pressurized airflow managed to the fuel cell assembly includes increasing the pressurized airflow from the air management system to the fuel cell assembly based on the height being less than or equal to the height threshold.

[0125] According to any of the preceding clauses, the propulsion system wherein managing the pressurized airflow to the fuel cell assembly includes reducing the pressurized airflow from the air management system to the fuel cell assembly based on the altitude being greater than the altitude threshold.

[0126] According to any of the preceding clauses, the propulsion system wherein the controller is operatively coupled to the control valve and configured to activate the control valve based on the height being less than or equal to the height threshold, and to deactivate the control valve based on the height exceeding the height threshold.

[0127] According to any of the preceding clauses, the propulsion system wherein the altitude of the aircraft is greater than or equal to 0 feet and less than or equal to 25,000 feet.

[0128] The propulsion system according to any of the foregoing clauses, wherein the plurality of fuel cells comprises a plurality of fuel cell stacks.

[0129] The propulsion system according to any of the foregoing clauses, wherein the fuel cell assembly comprises a plurality of fuel cell assemblies.

[0130] The propulsion system according to any of the foregoing clauses, wherein the plurality of fuel cells includes a first fluid inlet for receiving a pressurized air flow and a second fluid inlet for receiving a fuel flow.

[0131] The propulsion system according to any of the foregoing clauses, wherein the fuel stream comprises a hydrogen fuel stream.

[0132] The propulsion system according to any of the foregoing clauses further includes a converter configured to provide a specified power output from the plurality of fuel cells to the at least one motor.

[0133] According to any of the preceding clauses, the propulsion system wherein the turbine section is in fluid communication with and downstream of the fluid outlet of the fuel cell assembly.

[0134] The propulsion system according to any of the foregoing clauses, wherein the plurality of fuel cells include proton exchange membrane fuel cells (PEMFC).

[0135] A propulsion system for an aircraft includes: a fan section including a fan; a turbine including a compressor section, a combustion section, and a turbine section arranged in a serial flow sequence; at least one motor, wherein one or both of the turbine and the at least one motor are configured to drive rotation of the fan in the fan section; a fuel cell assembly configured to power the motor, the fuel cell assembly including: at least one fuel cell, an air management system, and an airflow supply unit, the at least one fuel cell including a first fluid inlet for receiving an airflow, a second fluid inlet for receiving a fuelflow, and a fluid outlet, the air management system being in fluid communication with the at least one fuel cell, the airflow supply unit being in fluid communication with the air management system, the airflow supply unit including a guide vane assembly and an actuator, the guide vane assembly having a plurality of inlet guide vanes, the actuator being operable to change the pitch angle of each of the plurality of inlet guide vanes; and a controller operatively coupled to the actuator and configured to control the airflow rate supplied from the airflow supply unit to the air management system based on data indicating the altitude of the aircraft.

[0136] The propulsion system according to any of the foregoing clauses, wherein the airflow supply unit includes: a fuel cell compressor in fluid communication with the air management system; and a fuel cell turbine drivenly coupled to the fuel cell compressor.

[0137] According to any of the preceding clauses, the propulsion system wherein the fuel cell turbine is driven to the fuel cell compressor via one or more rotatable shafts.

[0138] According to any of the preceding clauses, the propulsion system wherein the fuel cell turbine is in fluid communication with and located downstream of the fluid outlet of the at least one fuel cell.

[0139] According to any of the preceding clauses, the propulsion system wherein the fuel cell turbine is configured to receive at least a portion of the exhaust gas discharged from at least one fuel cell.

[0140] The propulsion system according to any of the foregoing clauses, wherein the controller includes a memory and one or more processors, the memory storing instructions that, when executed by the one or more processors, cause the propulsion system to operate, the operation including: receiving data indicating the altitude of the aircraft; and driving the actuator in response to the received data to control the airflow rate supplied from the airflow supply unit to the air management system.

[0141] According to any of the preceding clauses, the propulsion system wherein: the controller is configured to rotate the plurality of inlet guide vanes to a first position based on the height being less than or equal to a height threshold; and the controller is configured to rotate the plurality of inlet guide vanes to a second position based on the height exceeding the height threshold.

[0142] According to any of the preceding clauses, the propulsion system wherein rotating the plurality of inlet guide vanes to the first position includes increasing the pressurized airflow to the fuel cell assembly.

[0143] According to any of the preceding clauses, the propulsion system wherein rotating the plurality of inlet guide vanes to the second position includes reducing the pressurized airflow to the fuel cell assembly.

[0144] The propulsion system according to any of the foregoing clauses, wherein the air management system includes a distribution manifold configured to distribute the pressurized airflow to the at least one fuel cell.

[0145] According to any of the preceding clauses, the propulsion system wherein the altitude of the aircraft is greater than or equal to 0 feet and less than or equal to 25,000 feet.

[0146] The propulsion system according to any of the foregoing clauses, wherein the at least one fuel cell comprises a plurality of fuel cell stacks.

[0147] The propulsion system according to any of the foregoing clauses, wherein the fuel cell assembly comprises a plurality of fuel cell assemblies.

[0148] The propulsion system according to any of the foregoing clauses, wherein the fuel stream comprises a hydrogen fuel stream.

[0149] The propulsion system according to any of the foregoing clauses further includes a converter configured to provide a specified power output from the at least one fuel cell to the motor.

[0150] The propulsion system according to any of the foregoing clauses, wherein the plurality of fuel cells include proton exchange membrane fuel cells (PEMFC).

[0151] A propulsion system for an aircraft includes: a fan section including a fan; a turbine including a compressor section, a combustion section, and a turbine section arranged in a serial flow sequence; at least one motor, wherein one or both of the turbine and the at least one motor are configured to drive rotation of the fan in the fan section; and a fuel cell assembly configured to power the motor, the fuel cell assembly including: at least one fuel cell, an air management system, and an airflow supply unit, the at least one fuel cell including a first fluid inlet for receiving a pressurized airflow, a second fluid inlet for receiving a fuel flow, and a fluid outlet, the air management system being in fluid communication with the at least one fuel cell, and the airflow supply unit being configured to supply pressurized airflow to the air management system, the at least one fuel cell, or both the air management system and the at least one fuel cell.

[0152] The propulsion system according to any of the foregoing clauses, wherein the air management system comprises: a distribution manifold in fluid communication with the at least one fuel cell; and an air supply unit in fluid communication with the distribution manifold and the air flow supply section.

[0153] In any of the preceding clauses, the propulsion system wherein the air supply unit is removable and replaceable.

[0154] The propulsion system according to any of the foregoing clauses, wherein the air supply unit is refillable.

[0155] The propulsion system according to any of the foregoing clauses, wherein the air supply unit includes an air tank for storing the pressurized air.

[0156] The propulsion system according to any of the foregoing clauses, wherein the air supply unit includes an oxygen tank.

[0157] According to any of the preceding clauses, the propulsion system wherein the airflow supply unit comprises: a fuel cell compressor in fluid communication with the air management system; a fuel cell turbine drivenly coupled to the fuel cell compressor; a guide vane assembly having a plurality of inlet guide vanes and disposed upstream of the fuel cell compressor; and an actuator operable to change the pitch angle of each of the plurality of inlet guide vanes.

[0158] The propulsion system according to any of the foregoing clauses further includes a controller operatively coupled to the actuator, and includes a memory and one or more processors, the memory storing instructions that, when executed by the one or more processors, cause the propulsion system to operate, the operation including: receiving data indicating the altitude of the aircraft; and driving the actuator in response to the received data to control the airflow rate supplied from the airflow supply unit to the air management system.

[0159] According to any of the preceding clauses, the propulsion system wherein: the controller is configured to rotate the plurality of inlet guide vanes to a first position based on the height being less than or equal to a height threshold; and the controller is configured to rotate the plurality of inlet guide vanes to a second position based on the height exceeding the height threshold.

[0160] According to any of the preceding clauses, the propulsion system wherein rotating the plurality of inlet guide vanes to the first position includes increasing the pressurized airflow to the fuel cell assembly.

[0161] According to any of the preceding clauses, the propulsion system wherein rotating the plurality of inlet guide vanes to the second position includes reducing the pressurized airflow to the fuel cell assembly.

[0162] According to any of the preceding clauses, the propulsion system wherein the altitude of the aircraft is greater than or equal to 0 feet and less than or equal to 25,000 feet.

[0163] According to any of the preceding clauses, the propulsion system comprises a plurality of fuel cells stacked together to form a fuel cell stack.

[0164] The propulsion system according to any of the foregoing clauses, wherein the fuel cell assembly comprises a plurality of fuel cell assemblies.

[0165] The propulsion system according to any of the foregoing clauses, wherein the fuel stream comprises a hydrogen fuel stream.

[0166] The propulsion system according to any of the foregoing clauses, wherein the plurality of fuel cells include proton exchange membrane fuel cells (PEMFC).

[0167] This written description uses examples to disclose this disclosure, including best practices, and also enables any person skilled in the art to practice this disclosure, including making and using any device or system and methods of making any combination. The patentable scope of this disclosure is defined by the claims, but may include other examples that would occur to a person skilled in the art. Such other examples are intended to fall within the scope of the claims if they include structural elements that are not indistinguishable from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims.

Claims

1. A propulsion system (112) for an aircraft (100), characterized in that, include: A fan section (122), the fan section (122) including a fan; a turbine (124), the turbine (124) including a compressor section (128), a combustion section (130) and a turbine section (132) arranged in a serial flow sequence; at least one motor (136), wherein one or both of the turbine (124) and the at least one motor (136) are configured to drive the rotation of the fan of the fan section (122); a fuel cell assembly (600), the fuel cell assembly (600) being configured to The motor (136) is powered, the fuel cell assembly (600) includes a plurality of fuel cells (605); and an air management system (610) is in fluid communication with the plurality of fuel cells (605) and the compressor section (128), the air management system (610) including a control valve (615) operable to distribute airflow from the compressor section (128) through the air management system (610) and to the plurality of fuel cells (605).

2. The propulsion system (112) according to claim 1, characterized in that, in, The air management system (610) further includes a distribution manifold (623) in fluid communication with the control valve (615) and the plurality of fuel cells (605), the distribution manifold (623) being configured to distribute the airflow to the plurality of fuel cells (605).

3. The propulsion system (112) according to claim 1, characterized in that, The system further includes a controller (640) comprising a memory (346) and one or more processors (344), the memory (346) storing instructions (350) which, when executed by the one or more processors (344), cause the propulsion system (112) to perform a plurality of operations, including: receiving data indicating the altitude of the aircraft (100), and managing the airflow of pressurized air (620) to the fuel cell assembly (600) in response to the received data indicating the altitude of the aircraft (100).

4. The propulsion system (112) according to claim 3, characterized in that, in, Receiving data indicating the altitude of the aircraft (100) includes determining the altitude of the aircraft (100) and comparing the determined altitude with an altitude threshold.

5. The propulsion system (112) according to claim 4, characterized in that, in, The airflow of the pressurized air (620) managed to the fuel cell assembly (600) includes increasing the airflow of the pressurized air (620) from the air management system (610) to the fuel cell assembly (600) based on the height being less than or equal to the height threshold.

6. The propulsion system (112) according to claim 4, characterized in that, in, Managing the airflow of the pressurized air (620) to the fuel cell assembly (600) includes reducing the airflow of the pressurized air (620) from the air management system (610) to the fuel cell assembly (600) based on the height being greater than the height threshold.

7. The propulsion system (112) according to claim 4, characterized in that, in, The controller (640) is operatively coupled to the control valve (615) and configured to activate the control valve (615) based on the height being less than or equal to the height threshold, and to deactivate the control valve (615) based on the height exceeding the height threshold.

8. The propulsion system (112) according to claim 3, characterized in that, in, The altitude of the aircraft (100) is greater than or equal to 0 feet and less than or equal to 25,000 feet.

9. The propulsion system (112) according to claim 1, characterized in that, in, The plurality of fuel cells (605) includes a plurality of fuel cell stacks.

10. The propulsion system (112) according to claim 1, characterized in that, in, The fuel cell assembly (600) includes multiple fuel cell assemblies.

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