Fuel handling system for hybrid electric propulsion using hydrocarbon fuel

Abstract

A fuel treatment system for a hybrid gas-electric propulsion system using hydrocarbon fuel includes a fuel pretreatment unit; comprising a first fuel passage and a second fuel passage, wherein the first fuel passage is in fluid communication with the fuel outlet of the fuel pretreatment unit. The partial oxidation reformer includes a heated fuel inlet and a reformed fuel outlet. The heated fuel inlet is in fluid communication with the fuel pretreatment unit via a first fuel passage. The solid oxide fuel cell includes an anode inlet and an anode outlet. The anode inlet is in fluid communication with the reformed fuel outlet of the partial oxidation reformer, and the anode outlet is in fluid communication with the second fuel passage of the regenerator. The combustor is in fluid communication with the anode outlet via a second fuel passage.

Description

Technical Field

[0001] The present disclosure relates to a hybrid gas-electric propulsion system, and more particularly to a fuel processing system for a hybrid gas-electric propulsion system using hydrocarbon fuel. Background Art

[0002] Hybrid electric propulsion systems rely on electricity generated by processing hydrogen fuel during operation to power the fan section or other components of the propulsion system. Carrying hydrogen fuel on board an aircraft requires bulky fuel tanks and cooling systems, which increases the weight of the hybrid electric propulsion system. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] A full and enabling disclosure of the present disclosure, including the best mode thereof, to one of ordinary skill in the art is set forth in the specification with reference to the accompanying drawings, in which:

[0004] Figure 1 is a perspective view of an exemplary aircraft that may incorporate at least one exemplary embodiment of the present disclosure.

[0005] Figure 2 is an exemplary embodiment according to the present disclosure that may be incorporated into Figure 1 A schematic cross-sectional view of an exemplary turbofan engine in a propulsion system is shown.

[0006] Figure 3 is a method for implementing an exemplary embodiment of the present disclosure. Figure 1 A schematic diagram of a hybrid electric propulsion system for an aircraft or other vehicle is shown.

[0007] Figure 4 According to an exemplary embodiment of the present disclosure Figure 3 Schematic diagram of the fuel processing system of the hybrid electric propulsion system shown.

[0008] Figure 5 is a method for implementing an exemplary embodiment of the present disclosure. Figure 4 A schematic diagram of a portion of the fuel handling system of a hybrid electric propulsion system is shown with an afterheat heat exchanger added. DETAILED DESCRIPTION

[0009] Reference will now be made in detail to the present embodiments of the present disclosure, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and the description have been used to refer to like or similar parts of the present disclosure.

[0010] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Furthermore, all embodiments described herein should be considered exemplary unless specifically stated otherwise.

[0011] The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. The term "at least one" in a context such as "at least one of A, B, or C" means only A, only B, only C, or any combination of A, B, and C.

[0012] 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 each component. Furthermore, the terms "upstream" and "downstream" refer to relative directions relative to the flow of a fluid in a fluid path. For example, "upstream" refers to the direction from which the fluid is flowing, and "downstream" refers to the direction toward which the fluid is flowing.

[0013] The term "turbomachine" refers to a machine that includes one or more compressors, a heat-generating section (e.g., a combustion section), and one or more turbines that together produce a torque output. The term "gas turbine engine" refers to an engine that has a turbine as all or part of its power source. Example gas turbine engines include turbofan engines, turboprop engines, turbojet engines, turboshaft engines, etc., as well as hybrid-electric versions of one or more of these engines.

[0014] Unless otherwise specified herein, the terms "coupled," "fixed," "attached," and the like refer to both direct coupling, fixing, or attachment as well as indirect coupling, fixing, or attachment through one or more intermediate components or features.

[0015] The phrases "from X to Y" and "between X and Y" each refer to a numerical range including the endpoints (ie, to a numerical range that includes X and Y).

[0016] The terms "fluid connection" and "fluid coupling" refer to a fluid connection established between two or more components or systems via a pipe, fluid coupling, conduit, valve, etc., so that a fluid (liquid or gas) can flow therebetween. The term "fluid communication" means that a fluid (liquid or gas) flows between two or more components or systems. The term "thermal communication" means that two components, systems, or features are formed, positioned, or configured to transfer thermal energy or heat therebetween.

[0017] The present disclosure generally relates to hybrid electric propulsion systems using hydrocarbon fuels. The system disclosed herein provides a near-term solution to achieving the goal of zero-emission or near-zero-emission aviation through electrification using smaller fuel tanks than systems based on liquid hydrogen (LH2) fuel.

[0018] In hybrid electric engines, generating large amounts of electricity using hydrocarbon fuels is a challenge because coke forms in the fuel at the high operating temperatures required for efficient power generation systems. The present disclosure introduces a fuel processing system for processing hydrocarbon fuels in hybrid electric aircraft by combining a solid oxide fuel cell with a partial oxidation reformer. Solid oxide fuel cells (SOFCs) can generate large amounts of power (~100 MW) due to their high operating temperature (~800°C) and high efficiency, making them suitable for hybrid electric aircraft engines. In addition, SOFCs are not susceptible to carbon monoxide (CO) poisoning and do not require expensive catalysts due to their high operating temperature - making them low-cost. The partial oxidation reformer is used to convert hydrocarbon fuels into the hydrogen fuel H2 required by the SOFC. Because the reactions in both units are exothermic, the combined system can be self-sustaining after a cold start. The high fuel inlet temperature required by the SOFC (~800°C) is provided by the partial oxidation reformer, while the SOFC also acts as a water-gas shift reactor, using water produced in the SOFC to convert the CO produced by the reformer into CO2, which is then processed to increase the power generated.

[0019] This disclosure describes a fuel processing system for hybrid electric propulsion using hydrocarbon fuels. The system includes a fuel preconditioning unit, a recovery heat exchanger, a partial oxidation reformer, a solid oxide fuel cell, and a combustion chamber that enables combustion of the hydrocarbon fuel and hydrogen. In an exemplary configuration, the fuel preconditioning unit deoxygenates and preheats the hydrocarbon fuel. The fuel preconditioning unit may include a fuel-to-air heat exchanger, a fuel deoxygenator or "deoxygenation unit," and may also include a fuel-to-oil heat exchanger.

[0020] Referring now to the accompanying drawings, Figure 1 is a perspective view of an exemplary aircraft 10 that may incorporate at least one exemplary embodiment of the present disclosure. Figure 1As shown, aircraft 10 has a fuselage 12, wings 14 attached to fuselage 12, and an empennage 16. Aircraft 10 further includes a propulsion system 18 that generates propulsive thrust to propel aircraft 10 during flight, taxiing operations, and the like. Although propulsion system 18 is shown attached to wings 14, in other embodiments, it may additionally or alternatively include one or more aspects coupled to other portions of aircraft 10, such as empennage 16, fuselage 12, or both. Propulsion system 18 includes at least one gas turbine engine 20 (two gas turbine engines are shown). Each gas turbine engine 20 is mounted to aircraft 10 in an underwing configuration. Each gas turbine engine 20 is capable of selectively generating propulsive thrust for aircraft 10. Each gas turbine engine 20 can be configured to burn various forms of fuel, including, but not limited to, jet fuel / aviation turbine fuel and hydrogen fuel, unless otherwise specified. Additionally or alternatively, each gas turbine engine 20 can be operated at least in part using onboard generated electricity.

[0021] like Figure 1 As further shown by hidden lines, the aircraft 10 may include a cabin 22 for carrying passengers or cargo, an environmental control system 24 for supplying air and for controlling the temperature on the aircraft 10, and may include an oxygen storage tank 26 for use with the environmental control system or for other purposes on the aircraft 10. In certain embodiments, the aircraft 10 may include a vent 28 for discharging air or exhaust gas to the atmosphere.

[0022] Figure 2 is an exemplary embodiment of the present disclosure that may be incorporated into Figure 1 A schematic cross-sectional view of a turbofan engine 120 in the propulsion system 18 is shown. More specifically, Figure 2 In an embodiment, the turbofan engine 120 is a high-bypass gas-electric (hybrid) turbofan jet engine. Figure 2 As shown, the turbofan engine 120 defines an axial direction A (extending parallel to a longitudinal centerline 122 for reference) and a radial direction R. Generally speaking, the turbofan engine 120 includes a fan section 124 and a core turbine engine 126 disposed downstream of the fan section 124 .

[0023] The illustrated core turbine engine 126 generally includes an outer casing 128 that is substantially tubular and defines an annular inlet 130. Outer casing 128 encloses, in series flow relationship, a compressor section including a supercharger or low-pressure (LP) compressor or "LP compressor 132" and a high-pressure (HP) compressor or "HP compressor 134"; a combustion section 136; a turbine section including a high-pressure (HP) turbine or "HP turbine 138" and a low-pressure (LP) turbine or "LP turbine 140"; and an exhaust nozzle section 142. A high-pressure (HP) shaft or spool or "HP shaft or spool 144" drivingly connects the HP turbine 138 to the HP compressor 134. A low-pressure (LP) shaft or spool or "LP shaft or spool 146" drivingly connects the LP turbine 140 to the LP compressor 132. Together, the LP compressor 132 , the HP compressor 134 , the combustion section 136 , the HP turbine 138 , the LP turbine 140 , and the exhaust jet nozzle section 142 define a core air flow path through the turbofan engine 120 in a series flow sequence.

[0024] For the illustrated embodiment, fan section 124 includes a fan 148 having a plurality of fan blades 150 coupled to a disk 152 in a circumferentially spaced apart manner. As shown, fan blades 150 extend outwardly from disk 152 generally in a radial direction R. Each fan blade 150 is rotatable relative to disk 152 about a pitch axis P by virtue of fan blades 150 being operably coupled to a pitch change mechanism 154 that is configured to collectively change the pitch of fan blades 150 in unison. Fan blades 150, disk 152, and pitch change mechanism 154 are rotatable together about longitudinal centerline 122 via an LP shaft or spool 146 across a power gearbox 156. Power gearbox 156 includes a plurality of gears for adjusting the rotational speed of fan 148 relative to LP shaft or spool 146 to a more efficient fan rotational speed.

[0025] Still refer to Figure 2 In an exemplary embodiment, disk 152 is covered by a forward hub 158 that is rotatable and aerodynamically contoured to facilitate airflow across and through the plurality of fan blades 150. Additionally, fan section 124 includes an annular fan casing or nacelle 160 that circumferentially surrounds fan 148 and / or at least a portion of core turbine engine 126. Nacelle 160 is supported relative to core turbine engine 126 by a plurality of circumferentially spaced outlet guide vanes 162. Furthermore, a downstream section 164 of nacelle 160 extends over an outer portion of core turbine engine 126 to define a bypass airflow passage 166 therebetween.

[0026] During operation of turbofan engine 120, air 168 enters turbofan engine 120 through nacelle 160 and / or associated inlet 170 of fan section 124. As air 168 passes through fan blades 150, a first portion 172 of air 168 is directed or channeled into bypass airflow passage 166, while a second portion 174 of air 168 is directed or channeled into core air flow path 147, or more specifically, into LP compressor 132. The ratio between first portion 172 of air 168 and second portion 174 of air 168 is generally referred to as the bypass ratio. For the exemplary embodiment shown, the bypass ratio may be at least approximately 8:1. Consequently, turbofan engine 120 may be referred to as an ultra-high bypass turbofan engine. Second portion 174 of air 168 then increases in pressure as it is directed through HP compressor 134 and into combustion section 136, where it mixes with fuel and combusts to provide combustion gases 176.

[0027] Combustion gases 176 are channeled through HP turbine 138, wherein a portion of thermal and / or kinetic energy from combustion gases 176 is extracted via successive stages of HP turbine stator blades 178 coupled to outer casing 128 and HP turbine rotor blades 180 coupled to HP shaft or spool 144, thereby causing HP shaft or spool 144 to rotate, which supports operation of HP compressor 134. Combustion gases 176 are then channeled through LP turbine 140, wherein a second portion of thermal and kinetic energy is extracted from combustion gases 176 via successive stages of LP turbine stator blades 182 coupled to outer casing 128 and LP turbine rotor blades 184 coupled to LP shaft or spool 146, which causes LP shaft or spool 146 to rotate, which supports operation of LP compressor 132 and / or rotation of fan 148.

[0028] The combustion gases 176 are then directed through the exhaust nozzle section 142 of the core turbine engine 126 to provide propulsive thrust. Simultaneously, the pressure of the first portion 172 of the air 168 is significantly increased as it is directed through the bypass airflow passage 166 before being discharged from the fan nozzle exhaust section 186 of the turbofan engine 120, also providing propulsive thrust. The HP turbine 138, the LP turbine 140, and the exhaust nozzle section 142 at least partially define a hot gas path 188 for directing the combustion gases 176 through the core turbine engine 126.

[0029] Figure 2The turbofan engine 120 shown in FIG is configured as an aviation gas turbine engine. Compared to land-based gas turbine engines, aviation gas turbine engines are designed to maximize power output and efficiency while minimizing the total weight of the gas turbine engine itself and any required accessory systems. However, it should be understood that Figure 2 The turbofan engine 120 shown in FIG. 1 is provided by way of example only, and in other exemplary embodiments, the turbofan engine 120 may have any other suitable configuration. It should also be understood that in other exemplary embodiments, aspects of the present disclosure may be incorporated into any other suitable gas turbine engine. For example, in other exemplary embodiments, aspects of the present disclosure may be incorporated into, for example, a turboprop engine, a turboshaft engine, or a turbojet engine.

[0030] Now refer to Figure 3 , which is used according to an exemplary embodiment of the present disclosure Figure 1 , a schematic diagram of a hybrid electric propulsion system 200 for an aircraft 10 or other vehicle is shown in FIG. For the illustrated embodiment, the hybrid electric propulsion system 200 includes a fuel tank 202 fluidly coupled to a fuel processing system 300 for processing hydrocarbon fuel (500) in the hybrid electric propulsion system 200. The fuel tank 202 is configured to hold the hydrocarbon fuel 500 and provide the fuel to the fuel processing system 300. In certain embodiments, a fuel pump 204 provides power for moving the hydrocarbon fuel 500 from the fuel tank 202 to the fuel processing system 300 and at least partially through the fuel processing system 300.

[0031] In the exemplary embodiment, fuel processing system 300 is fluidly coupled to Figure 2 The combustion section 136 of the turbofan engine 120 is shown schematically in FIG. Figure 3 As shown, the fuel processing system 300 may be electrically connected to the electric machine 206, such as, but not limited to, an electric motor. Additionally, or alternatively, the fuel processing system 300 may be electrically connected to the aircraft 10 ( Figure 1 ) of auxiliary electrical systems 208, such as but not limited to the environmental control system 24 ( Figure 1 ) or flight control system (not shown).

[0032] In an exemplary embodiment, as Figure 3As shown, the electric motor 206 is mechanically coupled to a fan gearbox 212 via a shaft 210. The fan gearbox 212 may be coupled to the fan section 124 of the turbofan engine 120 via a fan shaft 214. In certain configurations, the fan gearbox 212 may be mechanically coupled to the power gearbox 156. In operation, the electric motor 206 receives electrical power 216 from the fuel processing system 300, converts the electrical power 216 into rotational or mechanical power to rotate the shaft 210 and drive the fan gearbox 212, thereby driving the fan blades 150 of the fan section 124. Additionally, or alternatively, at least a portion of the electrical power 216 may be sent to the auxiliary electrical system 208 to support the aircraft 10 ( Figure 1 )'s various power needs.

[0033] As previously described herein, the fuel processing system 300 for the hybrid electric propulsion system 200 generally includes a fuel pre-processing unit fluidly coupled to the fuel tank 202, a purge gas generator, a multi-port valve, a regenerator, a partial oxidation reformer, a solid oxide fuel cell, and a combustor, generally arranged as shown and described herein. Figure 4 According to an exemplary embodiment of the present disclosure Figure 3 A schematic diagram of the fuel processing system 300 of the hybrid electric propulsion system 200 is shown.

[0034] like Figure 4 As shown, fuel processing system 300 includes a fuel pre-processing unit 302. Fuel pre-processing unit 302 includes a fuel inlet 304 and a fuel outlet 306 in fluid communication with fuel tank 202. A fuel flow passage 308 (shown in phantom) is fluidly coupled to fuel inlet 304 and fuel outlet 306 and provides a fluid flow path through fuel pre-processing unit 302. Fuel flow passage 308 may be at least partially defined by various pipes, valves, fluid couplings, etc. (not shown). As previously described, fuel pre-processing unit 302 is configured to receive hydrocarbon fuel 500 from fuel tank 202 via fuel pump 204. Fuel pump 204 provides power to move hydrocarbon fuel 500 from fuel tank 202 through fuel processing system 300 via various pipes, valves, fluid couplings, etc. (not shown). In an exemplary embodiment, fuel filter 218 may be positioned downstream of fuel pump 204 and upstream of fuel inlet 304 of fuel pre-processing unit 302 to remove particulates from hydrocarbon fuel 500.

[0035] In the exemplary embodiment, fuel pre-processing unit 302 includes at least one heat exchanger for heating hydrocarbon fuel 500. In the exemplary embodiment, fuel pre-processing unit 302 includes a pre-heating heat exchanger 310 in thermal communication with hydrocarbon fuel 500 via fuel inlet 304, and a fuel deoxygenation unit 312 in fluid and chemical communication with hydrocarbon fuel 500 via fuel flow passage 308. Pre-heating heat exchanger 310 and fuel deoxygenation unit 312 may be formed as a single device or body, or may be formed from two separate bodies.

[0036] In an exemplary embodiment, the preheat heat exchanger 310 is in thermal communication with the bleed air system 220. The bleed air system 220 may include a hot side fluid source 222. The hot side fluid source 222 may include either or both of the LP compressor 132 and the HP compressor 134, which provide a hot side fluid (HSF), such as compressor bleed air, to the preheat heat exchanger 310 via various conduits, valves, fluid couplings, etc. (not shown) extending through the preheat heat exchanger 310. A flow valve 224 may be disposed downstream of the hot side fluid source 222 and upstream of the preheat heat exchanger 310. The flow valve 224 may be configured and adjusted to control the flow rate of the hot side fluid HSF provided to the preheat heat exchanger 310, thereby controlling the amount of heat transfer between the hot side fluid HSF and the hydrocarbon fuel 500. The downstream end of the bleed air system 220 may be fluidly connected to the HP turbine 138, the HP compressor 134, the HP turbine 138 for the aircraft 10 ( Figure 1 ) of the environmental control system 24 and the aircraft 10 ( Figure 1 ) in one or more of the compartments 22.

[0037] In an exemplary embodiment, as Figure 3 As shown, the fuel processing system 300 includes a purge gas generator 314 for providing a purge gas (SG), such as nitrogen (N2) or other gas suitable for absorbing or purging oxygen from the hydrocarbon fuel 500. The purge gas generator 314 is fluidly coupled to a purge gas circuit 316, which is at least partially formed by various pipes, valves, fluid connectors, etc. (not shown). The purge gas circuit 316 is fluidly coupled to the fuel deoxygenation unit 312 and is in fluid and chemical communication therewith, and is fluidly coupled to the partial oxidation reformer 318 and is in fluid communication therewith. The partial oxidation reformer 318 includes a heated fuel inlet 320, a reformed fuel outlet 322, and an oxygen inlet 324. In the exemplary embodiment, the partial oxidation reformer 318 can be a catalytic partial oxidation reformer (preferred due to its lower operating temperature of -800°C) or a thermal partial oxidation reformer (operating at a temperature of ~1200°C).

[0038] In the exemplary embodiment, purge gas generator 314 includes a purge gas and oxygen separation membrane, referred to herein as "SG-O2 separation membrane 326." Purge gas generator 314 further includes an exhaust oxygen outlet 328 that is fluidly coupled to and in fluid communication with oxygen inlet 324 of partial oxidation reformer 318. Exhaust oxygen outlet 328 is in fluid communication with SG-O2 separation membrane 326. Purge gas circuit 316 may include a pump 330 that is fluidly coupled to and in fluid communication with purge gas generator 314 via a purge gas outlet 332 of purge gas generator 314 and via a purge gas inlet 334 of purge gas generator 314.

[0039] The purge gas circuit 316 may include a flame arrester 336 disposed downstream of the fuel deoxygenation unit 312 and upstream of the purge gas inlet 334. The purge gas generator 314 may be fluidly coupled to and in fluid communication with an ambient air source 338, such as, but not limited to, the nacelle 160 or the LP compressor 132. A valve 340 may be fluidly coupled to and in fluid communication with the exhaust oxygen outlet 328 and the oxygen inlet 324 of the partial oxidation reformer 318. In an exemplary embodiment, the exhaust oxygen outlet 328 of the purge gas generator 314 is fluidly coupled to the aircraft 10 upstream of the valve 340. Figure 1 )'s environmental control system 24, oxygen storage tank 26, and one or more of the vents 28 and in fluid communication therewith.

[0040] like Figure 4 As shown, multi-way valve 342 includes an inlet 344 that is fluidly coupled to fuel tank 202 and fuel flow passage 308 via fuel outlet 306 of fuel pre-processing unit 302 and is in fluid communication therewith. Actuation or manipulation of oxygen flow or fuel flow through either or both of valve 340 and multi-way valve 342, respectively, can be controlled by controller 346. In at least some exemplary embodiments, controller 346 can be a full authority digital engine control ("FADEC") controller. However, in other embodiments, other suitable controllers can be provided. For example, in other embodiments, controller 346 can include a health monitoring unit and other electronic systems.

[0041] The multi-way valve 342 includes at least a first outlet 348 and a second outlet 350. The second outlet 350 can be fluidly coupled to and in fluid communication with a burner 352 to enable direct fuel combustion during cold start of the engine. The burner 352 can be connected to a Figure 3 The combustion section 136 of the turbofan engine 120 is shown integrated or may be separate from the combustion section 136 of the turbofan engine 120. Figure 3 Combustion section 136 of turbofan engine 120 is shown. For example, combustor 352 may be part of a combustion system for an auxiliary power unit (not shown).

[0042] In the exemplary embodiment, a heat exchanger or "regenerator 354," including a first fuel passage 356 and a second fuel passage 358, is disposed downstream of the first outlet 348 of the multi-way valve 342. More specifically, the first fuel passage 356 is fluidly coupled to and in fluid communication with the fuel pre-processing unit 302 via the fuel outlet 306 and the first outlet 348 of the multi-way valve 342. In operation, the first fuel passage 356 and the second fuel passage 358 are in thermal communication within the regenerator 354. In the exemplary embodiment, the regenerator 354 can be a liquid fuel-to-gas heat exchanger, for example. For example, the first fuel passage 356 can be configured to receive a liquid fuel (such as hydrocarbon fuel 500), while the second fuel passage can be configured to receive a gaseous fuel (such as hydrogen-rich fuel).

[0043] In the exemplary embodiment, fuel processing system 300 includes a cold-start heat exchanger 360. Cold-start heat exchanger 360 can be configured as a fuel-gas heat exchanger or an electric heater heat exchanger. Cold-start heat exchanger 360 includes a fuel preheating passage 362 disposed upstream of first fuel passage 356 of regenerator 354 and in fluid communication with fuel outlet 306 of fuel preprocessing unit 302 and with heated fuel inlet 320 of partial oxidation reformer 318. In certain embodiments, fuel preheating passage 362 can be in fluid communication with fuel outlet 306 of fuel preprocessing unit 302 via first outlet 348 of multi-way valve 342.

[0044] The cold-start heat exchanger 360 may include an exhaust passage 364. In operation, the fuel preheat passage 362 is in thermal communication with the exhaust passage 364. The exhaust passage 364 may be fluidly coupled to the turbofan engine 120 ( Figure 3 ) and is in fluid communication therewith. For example, exhaust passage 364 may be in fluid communication with LP compressor 132, HP compressor 134, combustion section 136, HP turbine 138, LP turbine, or exhaust nozzle section 142 of turbofan engine 120. When cold-start heat exchanger 360 is configured as an electric heater, it may include an electrical resistor or other suitable electrically powered heater in thermal communication with fuel preheat passage 362.

[0045] In an exemplary embodiment, controller 346 is electronically connected to cold-start heat exchanger 360 and is configured to control or allow fuel to flow through a fuel preheat path 362 of cold-start heat exchanger 360 to bypass or at least partially bypass first fuel path 356 of regenerator 354 during certain operating modes (such as during a cold start of turbofan engine 120).

[0046] Temperature sensor 366 can be electronically coupled to controller 346 and configured to measure and transmit an electronic signal indicative of the fuel temperature, as measured upstream of heated fuel inlet 320 of partial oxidation reformer 318. Controller 346 can be configured to adjust or manipulate one or both of valve 340 and multi-way valve 342 from a fully closed or zero flow position to a fully open or full flow position, or to any open position defined therebetween, to meter or control the volume of flow through valve 340 or multi-way valve 342, respectively. Thus, controller 346 can be configured to regulate the amount of fuel used to generate electricity versus the amount of fuel that is directly combusted. Additionally, or alternatively, controller 346 can be configured to control the flow through exhaust passage 364 or the power provided to the electric heater of cold-start heat exchanger 360.

[0047] like Figure 4 As shown, a solid oxide fuel cell 368 or "SOFC" is disposed downstream of the reformed fuel outlet 322 of the partial oxidation reformer 318. The solid oxide fuel cell 368 includes an anode inlet 370, an anode outlet 372, a cathode inlet 374, and a cathode outlet 376. An anode flow channel 378 passes through the solid oxide fuel cell 368 and is fluidly coupled to and in fluid communication with the anode inlet 370 and the anode outlet 372. A cathode flow channel 380 passes through the solid oxide fuel cell 368 and is fluidly coupled to and in fluid communication with the cathode inlet 374 and the cathode outlet 376.

[0048] The anode inlet 370 is fluidly coupled to and in fluid communication with the reformed fuel outlet 322 of the partial oxidation reformer 318. In an exemplary embodiment, the anode outlet 372 can be in fluid communication with the second fuel channel 358 of the regenerator 354. Additionally or alternatively, the anode outlet 372 can be in fluid communication with the second fuel channel 358 of the regenerator 354. In certain embodiments, the solid oxide fuel cell 368 is configured as a water-gas shift reactor to convert CO to CO2 and to produce additional H2 fuel using the water produced by the solid oxide fuel cell 368.

[0049] In certain embodiments, a fuel and water separation unit 382 is disposed between the solid oxide fuel cell 368 and the regenerator 354 and is in fluid communication with the anode outlet 372. The fuel and water separation unit 382 includes a hydrogen fuel outlet 384 and an anode water outlet 386. The hydrogen fuel outlet 384 is fluidly coupled to the second fuel passage 358 of the regenerator 354 and the combustor 352. In certain embodiments, the anode water outlet 386 may be fluidly coupled to and in fluid communication with one or more of the partial oxidation reformer 318, the HP turbine 138, and the combustor 352.

[0050] In certain embodiments, the solid oxide fuel cell 368 may be in thermal communication with a cathode air heating system 388, which includes a cathode air source 390 and an air-to-air heat exchanger 392 that may be configured as a regenerator. The cathode inlet 374 and the cathode outlet 376 are fluidly coupled to the cathode air heating system 388. The cathode air source 390 may include an LP compressor 132 or an HP compressor 134. The air-to-air heat exchanger 392 includes a cathode air passage 394 that is fluidly coupled to and in fluid communication with the cathode air source 390 and the cathode inlet 374, and a cathode air exhaust passage 396 that is fluidly coupled to and in fluid communication with the cathode outlet 376. In operation, the cathode air passage 394 is in thermal communication with the cathode air exhaust passage 396. In an exemplary embodiment, the cathode air exhaust passage 396 may be fluidly coupled to the turbofan engine 120 ( Figure 3 ) (including but not limited to HP compressor 134 and combustor 352) and is in fluid communication therewith.

[0051] In an exemplary embodiment, the cathode air heating system 388 may further include an auxiliary heater 398, such as an air-to-exhaust heat exchanger or an electric heater. The auxiliary heater 398 is fluidly connected to and in fluid communication with the cathode air source 390 and the cathode inlet 374. The auxiliary heater 398 may be fluidly connected and configured within the cathode air heating system 388 to provide a suitable temperature for the cathode air source 390 to be heated during operation of the turbofan engine 120 ( Figure 2 ) during certain operating modes (such as during the turbofan engine 120 ( Figure 2 ) during a cold-start of the auxiliary heater 398, the air-to-air heat exchanger 392 is bypassed. The auxiliary heater 398 includes a bypass air passage 400 in fluid communication with the cathode air source 390 and the cathode inlet 374. In an embodiment where the auxiliary heater 398 is configured as an air-to-exhaust heat exchanger, the auxiliary heater 398 includes an exhaust hot air passage 402 in fluid communication with an exhaust air source 404. The exhaust air source 404 may include a turbofan engine 120 ( Figure 1 ), such as but not limited to the jet exhaust nozzle section 142 ( Figure 3 In embodiments where the auxiliary heater 398 is configured as an electric heater, the auxiliary heater 398 may include a resistor or other suitable electric heater in thermal communication with the bypass air passage 400 .

[0052] Figure 5 is a method for implementing an exemplary embodiment of the present disclosure. Figure 4 Schematic diagram of a portion of the fuel processing system 300 of the hybrid electric propulsion system 200 is shown, wherein an afterheat heat exchanger 406 is added to the fuel pre-processing unit 302. It should be understood that Figure 4 and Figure 5The fuel processing system 300 has similar components, and the same reference numbers are used for common components. Figure 5 In the exemplary embodiment shown, fuel pre-processing unit 302 is in fluid communication with fuel tank 202 and is configured to receive hydrocarbon fuel 500 therefrom. Preheat heat exchanger 310 is in thermal communication with hydrocarbon fuel 500 via fuel flow path 308. Fuel deoxygenation unit 312 is in fluid and chemical communication with hydrocarbon fuel 500 downstream of preheat heat exchanger 310.

[0053] The post-heat heat exchanger 406 is disposed downstream of the fuel deoxygenation unit 312 and is in thermal communication with the hydrocarbon fuel 500 after it passes through the fuel deoxygenation unit 312. The post-heat heat exchanger 406 is also fluidly connected to the inlet 344 of the multi-way valve 342 via the fuel outlet 306 of the fuel pre-processing unit 302 and is in fluid communication therewith. The pre-heat heat exchanger 310, the fuel deoxygenation unit 312, and the post-heat heat exchanger 406 can be formed or packaged as a single device or body. Alternatively, the pre-heat heat exchanger 310, the fuel deoxygenation unit 312, and the post-heat heat exchanger 406 can be formed from two or more separate devices.

[0054] Afterheat heat exchanger 406 is also in thermal communication with hot-side fluid system 408. Hot-side fluid system 408 may include an oil reservoir 410, a pump 412, and a heat source 414, such as a gearbox or bearing compartment. In operation, oil 416 is pumped from oil reservoir 410 by pump 412 and passed through heat source 414 to absorb heat. The now heated oil 418 is directed through afterheat heat exchanger 406, where at least a portion of the heat absorbed by oil 418 from heat source 414 is transferred to the flow of hydrocarbon fuel 500 flowing from fuel deoxygenation unit 312, thereby cooling heated oil 418 upstream of oil reservoir 410.

[0055] As arranged and described herein and as Figure 4 and Figure 5 The fuel processing system 300 shown together provides a system for processing hydrocarbon fuel 500 and converting it into hydrogen H2 fuel for hybrid electric aircraft by combining a solid oxide fuel cell with a partial oxidation reformer, while addressing or preventing potential coke formation in the hydrocarbon fuel 500 at the high operating temperatures required for the efficient power generation system of the hybrid electric aircraft.

[0056] First reference Figure 4In operation, hydrocarbon fuel 500 is drawn from fuel tank 202, passes through fuel filter 218 (if present) to remove particulates typically present in hydrocarbon fuel 500, and is then transferred to preheat heat exchanger 310 of fuel pretreatment unit 302. Heat is transferred from the hot-side fluid (HSF) of bleed air system 220 to hydrocarbon fuel 500. The hot-side fluid (HSF) is cooled, thereby producing cooled hot-side fluid (CHSF), which can be directed to one or more of the supply compartment 22, the environmental control system 24 directly to the compartment 22, the HP turbine 138, and the HP compressor 134. When the CHSF is directed to the environmental control system (ECS) 24, the preheat heat exchanger 310 acts as an ECS precooler, eliminating the need for a separate ECS precooler heat exchanger and reducing engine weight. When the CHSF is directed to the HP turbine 138 and / or HP compressor 134, it serves as cooling air, enabling the engine to operate at higher temperatures, thereby improving fuel efficiency. The flow valve 224 (when present) can be adjusted to control the flow rate of the hot side fluid HSF through the preheat heat exchanger 310 , thereby controlling the temperature of the hydrocarbon fuel 500 as it passes through the preheat heat exchanger 310 and enters the fuel deoxygenation unit 312 .

[0057] As the now heated hydrocarbon fuel 502 passes through the fuel deoxygenation unit 312, purge gas SG from the purge gas generator 314 flows through the purge gas circuit 316 and enters the fuel deoxygenation unit 312, where it reacts with the heated hydrocarbon fuel 502 to purge or absorb oxygen from the heated hydrocarbon fuel 502, thereby producing oxygen-containing purge gas (OSG) and heated deoxygenated hydrocarbon fuel 504. The oxygen-containing purge gas OSG is directed back to the purge gas generator 314, where the SG-O2 separation membrane 326 separates the absorbed oxygen from the purge gas SG. The purge gas SG is allowed to flow back through the purge gas circuit 316 to continue operation. In the exemplary embodiment, the purge gas is nitrogen (N2).

[0058] In certain embodiments, the SG-O2 separation membrane 326 can separate nitrogen (N2) from oxygen (O2) and other gases from the ambient air (A) drawn into the purge gas generator 314 from the ambient air source 338. Nitrogen can be used as the purge gas SG. This configuration allows the generation of purge gas SG during operation of the aircraft 10 without requiring a purge gas storage system to be carried on board the aircraft 10 or the turbofan engine 120, thereby saving weight and additional system components.

[0059] Oxygen (O 2 ) separated from the oxygen-containing purge gas OSG or excess oxygen from ambient air A may be directed from an exhaust oxygen outlet 328 to the partial oxidation reformer 318. Additionally, or alternatively, the oxygen O 2 may be directed to one or more of an environmental control system 24, an oxygen storage tank 26, and a vent 28 for discharging the oxygen O 2 to the atmosphere.

[0060] Brief Reference Figure 5 In the exemplary embodiment where an afterheat heat exchanger 406 is present in the fuel pre-processing unit 302 , the now heated deoxygenated hydrocarbon fuel 504 may be directed through the afterheat heat exchanger 406 , wherein additional heat is transferred from the heated oil 418 of the hot side fluid system 408 to the heated deoxygenated hydrocarbon fuel 504 , thereby further increasing the operating temperature of the deoxygenated hydrocarbon fuel 500 upstream of the multi-way valve 342 .

[0061] Reference back Figure 4 , the controller 346 may send an electronic signal to the multi-way valve 342 to manipulate the multi-way valve 342 to control the flow rate of the heated deoxygenated hydrocarbon fuel 504 to one or more of the burner 352 for combustion, the regenerator 354 for further processing, and the cold-start heat exchanger 360 (when the turbofan engine 120 is in a cold-start condition). The temperature sensor 366 may send a signal back to the controller 346 indicating the temperature of the heated deoxygenated hydrocarbon fuel 504 just upstream of the heated fuel inlet 320 of the partial oxidation reformer 318.

[0062] In an exemplary embodiment, if the temperature of the heated deoxygenated hydrocarbon fuel 504 is less than 80° C. when the partial oxidation reformer 318 is a catalytic partial oxidation reformer, or less than 120° C. when the partial oxidation reformer 318 is a thermal partial oxidation reformer, the controller 346 may send an electronic signal to the cold-start heat exchanger 360 instructing it to open the first outlet 348 of the multi-way valve 342 or otherwise receive at least a portion or all of the heated deoxygenated hydrocarbon fuel 504 from the first outlet 348 of the multi-way valve 342 for additional heating to a suitable operating temperature for the partial oxidation reformer 318. Under non-cold-start conditions, the heated deoxygenated hydrocarbon fuel 504 is directed through the first fuel passage 356 of the regenerator 354 to provide the heated deoxygenated hydrocarbon fuel 504 to the partial oxidation reformer 318 at a suitable operating temperature.

[0063] As the heated deoxygenated hydrocarbon fuel 504 flows through the partial oxidation reformer 318, it reacts with oxygen O2 from the exhaust oxygen outlet 328 of the purge gas generator 314. The exothermic reaction produces a hydrogen-rich carbon monoxide fuel mixture, or "H2+CO fuel mixture 506." The hot H2+CO fuel mixture 506 is then directed to the anode inlet 370 of the solid oxide fuel cell 368. Within the solid oxide fuel cell, the H2+CO fuel mixture 506 acts as an anode and reacts with cathode air (CA) provided by the cathode air source 390 of the cathode air heating system 388. The cathode air CA reacts within the solid oxide fuel cell 368 as a cathode. Excess air (EA) generated by the exothermic reaction within the solid oxide fuel cell 368 can flow from the cathode outlet 376, through the air-to-air heat exchanger 392, and to one or more other components or systems of the turbofan engine 120 or the aircraft 10, such as, but not limited to, the HP compressor 134 or the combustor.

[0064] In an exemplary embodiment, the solid oxide fuel cell 368 acts as a water-gas shift reactor for the reaction between the H2+CO fuel mixture 506 in the solid oxide fuel cell 368 and the cathode air CA, thereby converting CO into CO2 and generating more hydrogen fuel using the water produced by the solid oxide fuel cell 368. This produces a hydrogen + carbon dioxide and water fuel mixture, or "H2+CO2+H2O fuel mixture 508." In an exemplary embodiment, the fuel and water separator 382 can separate the H2+CO2 from the H2O, thereby producing a hydrogen and carbon dioxide fuel mixture, or "hot H2+CO2 fuel mixture 510," and anode water 512.

[0065] Since the reactions in the partial oxidation reformer 318 and the solid oxide fuel cell 368 are both exothermic, the hot H2+CO2 fuel mixture 510 can be directed to the recuperator 354 to preheat the heated deoxygenated hydrocarbon fuel 504 before the hot H2+CO2 fuel mixture 510 is directed to the combustor 352 for combustion. The hot H2+CO2 fuel mixture 510 can be directed to the recuperator 354 for additional heating upstream of the combustor 352 before being directed to the combustor 352 for combustion. Anode water 512 can be directed from the fuel and water separation unit 382 to one or more of the HP turbine 138 for cooling, the combustor for NOx reduction, and the partial oxidation reformer 318 to reduce soot formation therein, thereby increasing the life expectancy of the catalyst of the partial oxidation reformer 318.

[0066] This written description uses examples to disclose the disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

[0067] Further aspects are provided by the subject matter of the following clauses:

[0068] A fuel processing system for a hybrid electric propulsion system using hydrocarbon fuel, the fuel processing system comprising: a fuel preprocessing unit, the fuel preprocessing unit comprising a fuel inlet, a fuel outlet, and a fuel flow channel defined between the fuel inlet and the fuel outlet; a regenerator, the regenerator comprising a first fuel channel and a second fuel channel, wherein the first fuel channel is fluidically connected to the fuel outlet of the fuel preprocessing unit; a partial oxidation reformer, the partial oxidation reformer comprising a heating fuel inlet and a reforming fuel outlet, wherein the heating fuel inlet is fluidically connected to the fuel preprocessing unit via the first fuel channel; a solid oxide fuel cell, the solid oxide fuel cell comprising an anode inlet and an anode outlet, wherein the anode inlet is fluidically connected to the reforming fuel outlet of the partial oxidation reformer, and wherein the anode outlet is fluidically connected to the second fuel channel of the regenerator; and a burner, the burner is fluidically connected to the anode outlet via the second fuel channel.

[0069] The fuel processing system of any preceding or following clause, wherein the fuel pre-processing unit comprises a pre-heat heat exchanger and a fuel deoxygenation unit, wherein the fuel flow path passes through the pre-heat heat exchanger and the fuel deoxygenation unit.

[0070] The fuel processing system of any preceding or following clause, wherein the fuel pre-processing unit includes an afterheat heat exchanger disposed downstream of the fuel deoxygenation unit and in fluid communication with the fuel deoxygenation unit via the fuel flow channel.

[0071] The fuel processing system of any preceding or following clause, further comprising a purge gas generator comprising a purge gas circuit, wherein the fuel pre-processing unit comprises a fuel deoxygenation unit, wherein the purge gas circuit is in fluid communication with the fuel deoxygenation unit.

[0072] The fuel processing system of any preceding or following clause, wherein the purge gas generator comprises a purge gas and an oxygen separation membrane.

[0073] The fuel processing system of any preceding or following clause, wherein the partial oxidation reformer includes an oxygen inlet, wherein the purge gas generator includes an exhaust oxygen outlet in fluid communication with the purge gas and an oxygen separation membrane, wherein the exhaust oxygen outlet is in fluid communication with the oxygen inlet of the partial oxidation reformer.

[0074] The fuel processing system of any preceding or following clause, wherein the solid oxide fuel cell is configured as a water gas shift reactor.

[0075] The fuel processing system of any preceding or following clause, further comprising a cold-start heat exchanger comprising a fuel preheat passage, wherein the fuel preheat passage is in fluid communication with the fuel outlet of the fuel preprocessing unit and the heated fuel inlet of the partial oxidation reformer.

[0076] The fuel processing system of any preceding or following clause, wherein the fuel preheat passage is in fluid communication with the fuel outlet of the fuel preprocessing unit upstream of the first fuel passage of the regenerator.

[0077] The fuel processing system of any preceding or following clause, wherein the cold-start heat exchanger includes an exhaust passage in fluid communication with a turbofan engine, wherein the fuel preheat passage is in thermal communication with the exhaust passage.

[0078] The fuel processing system of any preceding or following clause, wherein the cold-start heat exchanger comprises an electric heater, wherein the fuel preheat passage is in thermal communication with the electric heater.

[0079] The fuel processing system of any preceding or following clause, further comprising a fuel and water separation unit in fluid communication with the anode outlet, wherein the fuel and water separation unit comprises a hydrogen fuel outlet in fluid communication with the burner via the second fuel passage of the regenerator.

[0080] The fuel processing system of any preceding or following clause, wherein the fuel and water separation unit comprises an anode water outlet, wherein the anode water outlet is in fluid communication with the partial oxidation reformer.

[0081] The fuel processing system of any preceding or following clause, wherein the fuel and water separation unit comprises an anode water outlet, wherein the anode water outlet is in fluid communication with the burner.

[0082] The fuel processing system of any preceding or following clause, wherein the fuel and water separation unit comprises an anode water outlet, wherein the anode water outlet is in fluid communication with a high pressure turbine of a turbofan engine.

[0083] The fuel processing system of any preceding or following clause, further comprising a controller, wherein the controller is configured to regulate one or more of an oxygen flow rate, a fuel flow rate, and a fuel temperature supplied to the partial oxidation reformer.

[0084] The fuel processing system of any preceding or following clause, further comprising a cathode air heating system, wherein the solid oxide fuel cell comprises a cathode inlet and a cathode outlet, wherein the cathode inlet and the cathode outlet are fluidly coupled to the cathode air heating system.

[0085] The fuel processing system of any preceding or following clause, wherein the cathode air heating system comprises a cathode air source and an air-to-air heat exchanger, wherein the air-to-air heat exchanger comprises a cathode air channel in fluid communication with the cathode inlet and a cathode air exhaust channel in fluid communication with the cathode outlet.

[0086] A fuel processing system according to any preceding or following clause, wherein the cathode air heating system includes a cathode air source and an auxiliary heater, wherein the auxiliary heater includes a bypass air channel in fluid communication with the cathode air source and the cathode inlet, and an exhaust hot air channel in fluid communication with the exhaust air source.

[0087] The fuel processing system of any preceding or following clause, wherein the cathode air heating system comprises a cathode air source and an auxiliary heater, wherein the auxiliary heater comprises a bypass air channel in fluid communication with the cathode air source and the cathode inlet, and an electric heater in thermal communication with the bypass air channel.

Claims

1. A fuel processing system for a hybrid electric propulsion system using hydrocarbon fuel, characterized in that: The fuel processing system comprises: a fuel pre-processing unit comprising a fuel inlet, a fuel outlet, and a fuel flow passage defined between the fuel inlet and the fuel outlet; a regenerator, the regenerator comprising a first fuel channel and a second fuel channel, wherein the first fuel channel is in fluid communication with the fuel outlet of the fuel pre-processing unit; a partial oxidation reformer comprising a heated fuel inlet and a reformed fuel outlet, wherein the heated fuel inlet is in fluid communication with the fuel pre-processing unit via the first fuel passage; a solid oxide fuel cell comprising an anode inlet and an anode outlet, wherein the anode inlet is in fluid communication with the reformed fuel outlet of the partial oxidation reformer, and wherein the anode outlet is in fluid communication with the second fuel channel of the regenerator; and A burner is in fluid communication with the anode outlet via the second fuel passage.

2. The fuel processing system according to claim 1, wherein: The fuel pre-processing unit includes a preheating heat exchanger and a fuel deoxidation unit, wherein the fuel flow channel passes through the preheating heat exchanger and the fuel deoxidation unit.

3. The fuel processing system according to claim 2, characterized in that The fuel pretreatment unit includes a post-heat heat exchanger, which is disposed downstream of the fuel deoxygenation unit and is in fluid communication with the fuel deoxygenation unit via the fuel flow channel.

4. The fuel processing system according to claim 1, wherein: Further comprising a purge gas generator comprising a purge gas loop, wherein the fuel pre-processing unit comprises a fuel deoxygenation unit, wherein the purge gas loop is in fluid communication with the fuel deoxygenation unit.

5. The fuel processing system according to claim 4, characterized in that The purge gas generator includes a purge gas and an oxygen separation membrane.

6. The fuel processing system according to claim 5, characterized in that wherein the partial oxidation reformer comprises an oxygen inlet, wherein the purge gas generator comprises an exhaust oxygen outlet in fluid communication with the purge gas and an oxygen separation membrane, wherein the exhaust oxygen outlet is in fluid communication with the oxygen inlet of the partial oxidation reformer.

7. The fuel processing system according to claim 1, wherein: The solid oxide fuel cell is configured as a water-gas shift reactor.

8. The fuel processing system according to claim 1, wherein: Further included is a cold-start heat exchanger comprising a fuel preheating channel, wherein the fuel preheating channel is in fluid communication with the fuel outlet of the fuel preprocessing unit and the heated fuel inlet of the partial oxidation reformer.

9. The fuel processing system according to claim 8, characterized in that The fuel preheating channel is in fluid communication with the fuel outlet of the fuel preprocessing unit upstream of the first fuel channel of the regenerator.

10. The fuel processing system according to claim 8, wherein: The cold-start heat exchanger includes an exhaust passage in fluid communication with a turbofan engine, wherein the fuel preheating passage is in thermal communication with the exhaust passage.

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