Hybrid turbofan engine and solid oxide fuel cell propulsion system and related methods

Abstract

The name of the invention is hybrid turbofan engine and solid oxide fuel cell propulsion system and related methods. A hybrid propulsion system utilizes a liquid natural gas solid oxide fuel cell in a practical manner suitable for an aircraft that avoids the use of heavy batteries, provides transient response times suitable for use in an aircraft, and / or simplifies a reactant pre-processing system using a compressor and turbine operably coupled to the solid oxide fuel cell. Such a hybrid propulsion system for an aircraft can include a liquid natural gas solid oxide fuel cell, an electric motor driven by electrical power from the solid oxide fuel cell, a gearbox operably coupled to the electric motor, and a turbofan engine configured to produce thrust for the aircraft. The turbofan engine can be configured to provide electrical power and shaft power, and can include a ducted fan operably coupled to the electric motor by the gearbox, the ducted fan driven by mechanical power from the gearbox and the electric motor.

Description

Technical Field

[0001] This disclosure relates to propulsion systems, and more specifically to solid oxide fuel cell propulsion systems using liquefied natural gas. Background Technology

[0002] A turbofan engine is a type of jet engine that has long been used in propulsion systems for aircraft and other vehicles or machinery. Attempts have been made to design turboshaft engines that reduce or eliminate CO2 emissions and other greenhouse gases. One such solution is electric propulsion, but the weight loss is too great to be feasible in the aviation industry. Attempts have also been made to incorporate fuel cells into such propulsion systems, although conventional fuel cell systems suffer from slow transient response times unsuitable for aviation and may adversely require complex systems for pre-processing (heating and pressurizing) fuel cell reactants. Summary of the Invention

[0003] The hybrid propulsion system disclosed herein can be configured to use alternative energy sources and configurations not considered in the prior art to reduce emissions and improve the efficiency of the overall aircraft propulsion system, while avoiding the drawbacks of prior art systems, such as the excessive weight and slow transient response time of electric propulsion. By addressing these shortcomings of prior art systems, the hybrid propulsion system of this disclosure can utilize liquefied natural gas solid oxide fuel cells in an aircraft-appropriate manner. The hybrid propulsion system of this disclosure can also be configured to simplify the reactant pretreatment system.

[0004] In one example, a hybrid propulsion system for an aircraft may include a liquefied natural gas turbofan engine, a liquefied natural gas solid oxide fuel cell, an electric motor driven by electricity from the solid oxide fuel cell, a gearbox operatively coupled to the electric motor, and a turbofan engine configured to generate thrust for the aircraft, wherein the turbofan engine is configured to provide both electrical and shaft power. The turbofan engine may include a ducted fan operatively coupled to the electric motor via the gearbox, and the ducted fan may be driven by mechanical power from the gearbox and the electric motor. Liquefied natural gas may be used as fuel for both the turbofan engine and the solid oxide fuel cell, which may be operatively coupled together to reduce the transient response time of the turbofan engine. Aircraft including a fuselage, fuselage-supported wings, a turbofan engine, and the hybrid propulsion system of this disclosure are also within the scope of this disclosure.

[0005] In some instances, a hybrid propulsion system for an aircraft may include a liquefied natural gas solid oxide fuel cell, an electric motor driven by electricity from the solid oxide fuel cell, a gearbox operatively coupled to the electric motor, a turbofan engine configured to generate thrust for the aircraft, and a turbine generator operatively coupled to a duct fan and a turbine downstream of the turbofan engine, the turbine generator being connected in parallel with the solid oxide fuel cell. The turbofan engine may include a duct fan operatively coupled to the electric motor via the gearbox, and the duct fan of the turbofan engine may be driven by mechanical power from the gearbox and the electric motor.

[0006] A method for providing thrust to an aircraft via a hybrid propulsion system is also disclosed. This method may include generating a first amount of electricity through a liquefied natural gas solid oxide fuel cell and using it to drive an electric motor, which in turn drives a ducted fan of a turbofan engine via mechanical power from a gearbox, thereby providing thrust to the aircraft. Bleed air from the ducted fan of the turbofan engine is extracted and used as source air for the solid oxide fuel cell. In this method, the electric motor can be operatively coupled to the ducted fan of the aircraft's turbofan engine via a gearbox. Attached Figure Description

[0007] Figure 1 The illustration is based on the example aircraft of this disclosure.

[0008] Figure 2 This is a schematic diagram illustrating a non-exclusive example of a hybrid propulsion system according to the present disclosure.

[0009] Figure 3 This is a schematic diagram illustrating a non-exclusive example of a hybrid propulsion system according to the present disclosure.

[0010] Figure 4 This is a flowchart schematically illustrating the method according to this disclosure. Detailed Implementation

[0011] Figure 1 A non-exclusive example of an aircraft 12 according to this disclosure is shown, which may include one or more hybrid propulsion systems 10 and / or 11. Although shown as a fixed-wing passenger aircraft including a fuselage 60 with a cabin 18, two wings 62 supported by the fuselage 60, a tail 14, and a jet engine 16 supported by each wing 62, other configurations of the aircraft 12 are also within the scope of this disclosure, including, for example, gyroplanes, military aircraft, autonomous aircraft, etc. Figure 1One or more components of the hybrid propulsion system 10 and / or 11, as well as all optional components, are schematically shown, which may be supported and / or housed therein by one or more of the fuselage 60 and / or wings 62 of the aircraft 12.

[0012] Figure 2-3 Non-exclusive examples of hybrid propulsion systems 10 and 11 according to this disclosure are schematically illustrated. Typically, in Figure 2-3 In this disclosure, elements that may be included in a given instance are indicated by solid lines, while elements that are optional in a given instance or correspond to a particular instance are indicated by dashed lines. However, elements indicated by solid lines are not necessary for all instances of this disclosure, and elements shown by solid lines may be omitted from a particular instance without departing from the scope of this disclosure.

[0013] Figure 2 An example of a hybrid propulsion system 10 for an aircraft (e.g., aircraft 12) is shown, which combines a geared turbofan engine 44 and a liquefied natural gas solid oxide fuel cell 24. The disclosed hybrid propulsion system 10 includes an electric motor 26 (hereinafter simply referred to as motor 26) driven by electricity 108 from the solid oxide fuel cell 24, a gearbox 20 operatively coupled to the electric motor 26, and a turbofan engine 44 configured to generate thrust for the aircraft. The turbofan engine 44 includes a ducted fan 46 operatively coupled to the electric motor 26 via the gearbox 20, the ducted fan 46 being mechanically driven by the gearbox 20. The gearbox 20 is driven by the mechanical shaft power of the turbofan engine 44 and the electric motor 26. In some examples, the turbofan engine 44 is configured to provide electricity (used for power generation via engine exhaust 74 through the solid oxide fuel cell 24) and / or shaft power. The hybrid propulsion system 10 may include a fuel system 72 configured to supply liquefied natural gas (LNG) to both the turbofan engine 44 and the solid oxide fuel cell 24 (e.g., LNG is used as fuel or reactant for both the turbofan engine 44 and the solid oxide fuel cell 24). The use of LNG in the disclosed hybrid propulsion system 10, combined with the arrangement of the solid oxide fuel cell 24 and the turbofan engine 44, creates a humid environment for the operation of the solid oxide fuel cell 24 by preheating the LNG using engine exhaust 74 and fuel cell exhaust 64 to evaporate it, and by condensing water from the engine exhaust 74 using the cold properties of the LNG, resulting in synergistic efficiencies not considered in the prior art.

[0014] A turbofan engine 44 typically includes a low-pressure compressor 28, a high-pressure compressor 30, a high-pressure turbine 32, and a low-pressure turbine 34. A combustor 40 (e.g., a combustion chamber or burner) is housed within the turbofan engine 44, typically located between the high-pressure compressor 30 and the high-pressure turbine 32. A first shaft 36 may be coupled to the high-pressure compressor 30 and the high-pressure turbine 32, such that the high-pressure compressor 30 can be driven by the high-pressure turbine 32. A second shaft 38 may be coupled to the low-pressure turbine 34 and the low-pressure compressor 28 within the turbofan engine 44, such that the low-pressure compressor 28 can be driven by the low-pressure turbine 34. In some instances, the second shaft 38 is also coupled to a gearbox 20, allowing power to be extracted from the low-pressure turbine 34 to operate the gearbox 20.

[0015] The main inlet 42 receives ambient air or air from the environment and regulates the ambient air for downstream components of the hybrid propulsion system 10, for example, by reducing the Mach number of the ambient air. The air is then delivered via a duct fan 46 to a low-pressure compressor 28 (i.e., the low-pressure compressor 28 receives air from both the main inlet 42 and the duct fan 46), which pressurizes (compresses) the air from the main inlet 42. Downstream of the duct fan 46, a turbofan splitter 118 delivers a first portion 110 of the air from the duct fan 46 to the low-pressure compressor 28 and a second portion 112 of the air from the duct fan 46 to a secondary nozzle 114. The low-pressure compressor 28 delivers the air 110 it receives from the turbofan splitter 118 to a high-pressure compressor 30 for further pressurization (and then to a combustor 40 for combustion). The turbofan splitter 118 also diverts fan bleed air 120 (also referred to herein as bleed air 120) along a bleed airflow path 48 to the compressor 50 of the compressor and turbine pair 54. Compressor 50, located downstream of turbofan splitter 118 along bleed airflow path 48, is configured to pretreat bleed air 120 for solid oxide fuel cell 24 by pressurizing and increasing the temperature of bleed air 120 due to compression. In some instances, compressor 50 is configured to primarily compress and / or pressurize bleed air 120 from duct fan 46 for solid oxide fuel cell 24. Once compressed by compressor 50, bleed air 120 continues to flow along bleed airflow path 48 and is delivered to cathode 52 of solid oxide fuel cell 24 for use as reactant or source air for solid oxide fuel cell 24. In other words, bleed air 120 can be extracted from turbofan engine 44 via turbofan splitter 118 to provide pretreated source air to solid oxide fuel cell 24. While main nozzle 94 can provide the primary outlet point for engine exhaust 74 to generate primary thrust for the aircraft, secondary nozzle 114 can provide an outlet point for a second portion 112 of air from duct fan 46 to generate secondary thrust for the aircraft.

[0016] Compressor 50 is part of a compressor and turbine pair 54, which also includes a turbine 56 and a shaft 58 operatively connecting the compressor and turbine such that compressor 50 is driven by power from turbine 56. Compressor 50 is located upstream of cathode 52 of solid oxide fuel cell 24 to deliver bleed air 120 to cathode 52, and turbine 56 is located downstream of cathode 52 to receive fuel cell exhaust 64 from solid oxide fuel cell 24. Compressor and turbine pair 54 can be used to extract power from fuel cell exhaust 64 leaving solid oxide fuel cell 24 to improve the efficiency of hybrid propulsion system 10, rather than wasting the heat of fuel cell exhaust 64. For example, compressor and turbine pair 54 can be configured to use the energy extracted from fuel cell exhaust 64 to regulate or control one or more conditions of fuel cell reactants (e.g., bleed air 120) of solid oxide fuel cell 24. In some instances, turbine 56 is configured to limit power extraction from fuel cell exhaust 64 to maintain the pressure of fuel cell exhaust 64 above a desired threshold pressure. Alternatively, the compressor and turbine pair 54 can be configured to fine-tune reactant conditions rather than primarily pressurizing the reactants, thus serving as a simplified means of pre-treating the bleed air 120 of the solid oxide fuel cell 24 compared to conventional fuel cell systems that require complex processing systems.

[0017] In some instances, the hybrid propulsion system 10 includes a splitter 66 upstream of a turbine 56 and downstream of the cathode 52 of a solid oxide fuel cell 24, and / or a mixer 68 downstream of the turbine 56 (and also downstream of the cathode 52). In these instances, the mixer 68 receives turbine exhaust 70 from the turbine 56 and fuel cell exhaust 64 from the solid oxide fuel cell 24 (e.g., via the splitter 66) and mixes the turbine exhaust 70 with the fuel cell exhaust 64. The splitter 66 and the mixer 68 may be configured to control the outlet pressure of the turbine exhaust 70 exiting the turbine 56 and / or may be configured to control the pretreatment operating conditions of the bleed air 120 of the solid oxide fuel cell 24. The splitter 66 and the mixer 68 may be mounted around a turbine 56 operatively coupled to the solid oxide fuel cell 24, such as... Figure 2 An example of the hybrid propulsion system 10 is shown.

[0018] As described above, liquefied natural gas from fuel system 72 is used as fuel / reactant for both turbofan engine 44 and solid oxide fuel cell 24. The liquefied natural gas from fuel system 72 can also be used in the steam generation process within hybrid propulsion system 10. In some instances, the liquefied natural gas from fuel system 72 is used as a coolant to cool engine exhaust 74 from turbofan engine 44 and condense water from engine exhaust 74. Alternatively or additionally, the liquefied natural gas from fuel system 72 can be preheated using engine exhaust 74 for use in solid oxide fuel cell 24. For this purpose, hybrid propulsion system 10 may include a condenser 76, a heat exchanger 78, and / or a water extractor 80. Condenser 76 may receive liquefied natural gas 122 from fuel system 72 and evaporate (e.g., vaporize) the liquefied natural gas to form gaseous natural gas 82 (i.e., condenser 76 may be configured to convert liquefied natural gas 122 into gaseous natural gas 82). The condenser 76 can also condense liquid water (e.g., water vapor) from the engine exhaust 74 exiting the turbofan engine 44 and cool the engine exhaust 74. In other words, the liquid natural gas 122 from the fuel system 72 can be preheated by the engine exhaust 74 in the condenser 76 before being supplied to the anode 90 of the solid oxide fuel cell 24.

[0019] A heat exchanger 78 may be located downstream of a condenser 76 and may receive fuel cell exhaust 64 from a solid oxide fuel cell 24 (which may pass through a turbine 56 and a mixer 68). The heat exchanger 78 may be configured to receive gaseous natural gas 82 from the condenser 76 and supply gaseous natural gas 82 to a turbofan engine 44 (e.g., a combustor 40). In some instances, the heat exchanger 78 uses heat from the fuel cell exhaust 64 to further heat the gaseous natural gas 82 from the condenser 76. In some instances, the hybrid propulsion system 10 includes a turbofan mixer 92 located downstream of the heat exchanger 78 and a low-pressure turbine 34. In these instances, the turbofan mixer 92 is configured to mix the high-pressure fuel cell exhaust 64 into the outlet flow (e.g., engine exhaust 74) of the low-pressure turbine 34 exiting the turbofan engine 44 after the fuel cell exhaust 64 has passed through the heat exchanger 78, which can generate more power (e.g., greater thrust through the air exiting the main nozzle 94).

[0020] Water extractor 80 can be configured to receive air 84 and liquid water in the air from condenser 76, as well as gaseous natural gas 82. For example, a splitter 86 downstream of heat exchanger 78 can divert the gaseous natural gas 82 leaving the heat exchanger, such that some gaseous natural gas 82' is directed to turbofan engine 44, while some gaseous natural gas 82'' is directed to water extractor 80. Water extractor 80 can be configured to generate water vapor (i.e., steam) by extracting liquid water condensed from engine exhaust 74 by condenser 76, and is configured to add (e.g., mix) the water vapor to the gaseous natural gas 82'' received by water extractor 80 to provide humidified natural gas 88 to the anode 90 of solid oxide fuel cell 24. In some instances, anode 90 has an internal reformer to convert natural gas into hydrogen-rich gas, while in other instances, an external reformer 128 is provided upstream of anode 90 to convert natural gas into hydrogen-rich gas.

[0021] The electricity 108 output from the solid oxide fuel cell 24 can be transmitted via an inverter 104 before reaching the electric motor 26, which is operatively coupled to the gearbox 20 via a gearbox shaft 126. In this way, the electricity 108 from the solid oxide fuel cell 24 can cause the operation of the electric motor 26, which powers the gearbox 20, thereby driving the duct fan 46 of the turbofan engine 44. Similarly, power to drive the gearbox 20 can also be provided by coupling the gearbox 20 to the shaft 38 of the low-pressure turbine 34.

[0022] Figure 3 An example of a hybrid propulsion system 11 is shown, which is a modification of the hybrid propulsion system 10 and may include any of the features of the hybrid propulsion system 10 described above. Similar to the hybrid propulsion system 10, the hybrid propulsion system 11 includes a liquefied natural gas solid oxide fuel cell 24, an electric motor 26 driven by electricity 108 from the solid oxide fuel cell 24, a gearbox 20 operatively coupled to the electric motor 26, and a turbofan engine 44 configured to generate thrust for the aircraft. The turbofan engine 44 includes a duct fan 46 operatively coupled to the electric motor 26 via the gearbox 20, such that the duct fan 46 of the turbofan engine 44 can be driven by mechanical power from the gearbox 20 and the electric motor 26. The hybrid propulsion system 11 also includes a turbine generator 22 operatively coupled to the duct fan 46, and a turbine 100 downstream of the turbofan engine 44, connected in parallel with the solid oxide fuel cell 24. In this example, the electric motor 26 can be driven simultaneously by power 108 from the solid oxide fuel cell 24 and power 96 from the turbine generator 22, which can provide greater flexibility in managing power usage.

[0023] Similar to the hybrid propulsion system 10, in the hybrid propulsion system 11, downstream of the duct fan 46, a turbofan splitter 118 delivers a first portion 110 of air from the duct fan 46 to the low-pressure compressor 28 and a second portion 112 of air from the duct fan 46 to the secondary nozzle 114. Instead of transferring bleed air 120 from the turbofan splitter 118 to the compressor 50, the hybrid propulsion system 11 transfers bleed air 120 from the low-pressure compressor 28 along the bleed air flow path 48 to the compressor 50. The low-pressure compressor 28, together with the compressor 50 downstream of it along the bleed air flow path 48, pre-treats the bleed air 120 of the solid oxide fuel cell 24 by pressurizing and raising the temperature of the bleed air 120 due to compression. Once the bleed air 120 has been compressed in both the low-pressure compressor 28 and the compressor 50, it continues to flow along the bleed air flow path 48 and is delivered to the cathode 52 of the solid oxide fuel cell 24, whereby it is used as reactant or source air for the solid oxide fuel cell 24. In other words, bleed air 120 is extracted from turbofan engine 44 after being compressed by low-pressure compressor 28 to provide pretreated air to solid oxide fuel cell 24. Low-pressure compressor 28 also delivers a portion of the air it receives from turbofan splitter 118 to high-pressure compressor 30 for further pressurization, and then delivers it to combustor 40.

[0024] In some instances, the hybrid propulsion system 11 includes a turbofan mixer 92 located downstream of the heat exchanger 78 and the low-pressure turbine 34. In these instances, the turbofan mixer 92 is configured to mix the high-pressure fuel cell exhaust 64 into the outlet flow (e.g., engine exhaust 74) of the low-pressure turbine 34 exiting the turbofan engine 44 after the fuel cell exhaust 64 has passed through the heat exchanger 78, which can generate more electricity. This can be achieved because the fuel cell exhaust 64 has a similar pressure to the engine exhaust 74 exiting the low-pressure turbine 34. The high pressure of the fuel cell exhaust 64 can be achieved by the disclosed hybrid propulsion system 11 because less power is extracted through the turbine 56 compared to a conventional hybrid gas turbine fuel cell. Mixing the fuel cell exhaust 64 back into the turbofan engine 44 (e.g., mixing the fuel cell exhaust 64 and the engine exhaust 74) can increase the power generated by the turbine 100, which receives the engine exhaust 74 from the turbofan engine 44. Furthermore, the turbine 100 extracts power from the engine exhaust 74 to generate electricity 96 to power the electric motor 26, for example by connecting the turbine 100 to the shaft 98 of the turbine generator 22.

[0025] The power 108 output from the solid oxide fuel cell 24, after being converted from direct current (DC) to alternating current (AC) by a DC transformer 116, can be combined via bus 102 with power 96 from the turbine generator 22 to produce combined power, as shown in 124. The combined power 124 can be transmitted via inverter 104 before reaching the electric motor 26, which is operatively coupled to the gearbox 20 via gearbox shaft 126. In this way, the combined power 124 from the turbine generator 22 and the solid oxide fuel cell 24 can cause the operation of the electric motor 26, which powers the gearbox 20, thereby driving the duct fan 46 of the turbofan engine 44. Similarly, the power to drive the gearbox 20 can also be provided via shaft 38, which couples the gearbox 20 to the low-pressure turbine 34.

[0026] The power for the electric motor 26 can be provided solely by the solid oxide fuel cell 24, solely by the turbine generator 22, and / or by both the solid oxide fuel cell 24 and the turbine generator 22. In some instances, the power for the electric motor 26 is supplied simultaneously from both the solid oxide fuel cell 24 and the turbine generator 22. The hybrid propulsion system 11 may include an electric motor controller configured to control the source and relative amount of power supplied to the electric motor 26. For example, the electric motor controller may be configured to allocate a certain ratio of electrical load to the solid oxide fuel cell 24 and the turbine generator 22, thereby determining the fuel consumption ratio of the solid oxide fuel cell 24 to the turbine generator 22. The fuel consumption ratio can further determine the fuel ratio of the amount of fuel allocated by the fuel system 72 to each of the turbofan engine 44 and the solid oxide fuel cell 24. The disclosed hybrid propulsion system 11 may be configured such that the transient response time of the electric motor 26 is fast enough to be suitable for use in an aircraft. For example, compared to conventional systems using only fuel cells, the operative coupling of the solid oxide fuel cell 24 and the turbofan engine 44 in the hybrid propulsion system 11 of this disclosure can have the technical effect of reducing (e.g., accelerating) the transient response time of the electric motor 26 and / or the duct fan 46 (or the entire turbofan engine 44). The faster transient response in the disclosed hybrid propulsion systems 10 and / or 11 can be handled by the gas turbine side (e.g., the turbofan engine 44), and then, after the operation of the hybrid propulsion systems 10, 11 approaches steady state, power splitting can be transferred from the gas turbine side to the fuel cell side (e.g., the solid oxide fuel cell 24). In this way, the disclosed hybrid propulsion systems 10, 11 can be configured to utilize the faster transient response time of the turbofan engine 44 while also obtaining fuel efficiency benefits from the solid oxide fuel cell 24.

[0027] The controller, such as the described electronic engine controller, can be any suitable one or more devices configured to perform the functions of the electronic engine controller discussed herein. For example, the controller may include one or more of an electronic controller, a dedicated controller, a special-purpose controller, a personal computer, a special-purpose computer, a display device, a logic device, a memory device, and / or a memory device having a computer-readable medium adapted to store computer-executable instructions for implementing aspects of the system and / or method according to the present disclosure.

[0028] The scope of this disclosure also includes aircraft comprising the disclosed hybrid propulsion systems 10 and / or 11, such as Figure 1 The aircraft 12 is schematically represented herein. Such an aircraft 12 may include a fuselage 60, wings 62 supported by the fuselage 60, one or more jet engines 16 (which may be the turbofan engine 44 described herein), and a hybrid propulsion system 10 and / or 11. In some instances, at least a portion of the hybrid propulsion system 10 and / or 11 is supported by and / or housed within the wings 62. For example, the solid oxide fuel cell 24, compressor, and turbine pair 54 and / or heat exchanger 78 of the hybrid propulsion system 10 and / or 11 may be housed within the wings 62. In some instances, the turbofan engine 44 is supported by the tail section 14 of the fuselage 60 and / or the wings 62. In some instances, a turbine generator 22, a condenser 76, an electric motor 26, and / or a turbofan splitter 118 are housed within the turbofan engine 44. Embodiments of the aircraft 12 may include, but are not limited to, a single-channel turbo-electric aircraft.

[0029] Compared to existing propulsion systems, the benefits of the disclosed hybrid propulsion systems 10 and / or 11 may include reduced emissions and / or increased efficiency of the overall aircraft propulsion system. The disclosed hybrid propulsion systems 10 and / or 11 utilize alternative energy sources and configurations not considered in the prior art and are configured to avoid the heavy-duty batteries required by existing electric systems. Furthermore, since the disclosed hybrid propulsion systems 10 and / or 11 utilize bleed air 120 as pressurized air reactant for the solid oxide fuel cell 24, complex pretreatment systems can also be avoided, which is another advantage over the prior art. Additionally or alternatively, the hybrid propulsion systems 10 or 11 according to this disclosure can provide improved transient response time by coordinating the operation of the solid oxide fuel cell 24 and the turbofan engine 44.

[0030] Figure 4A flowchart illustrating a non-exclusive example of method 200 according to this disclosure is provided schematically. Figure 4 In the dashed boxes, some steps are shown, indicating that these steps may be optional or may correspond to optional forms of method 200 according to this disclosure. That is, not all methods 200 according to this disclosure need to include the steps shown in the solid boxes. Figure 4 The method 200 and steps shown are not limiting, and other methods and steps are also within the scope of this disclosure, including methods having a greater or less number of steps than shown, as understood in the discussion herein.

[0031] Method 200 for providing thrust to an aircraft (e.g., aircraft 12) via a hybrid propulsion system (e.g., hybrid propulsion systems 10 and / or 11) typically includes generating a first amount of electricity at 204 via a liquefied natural gas solid oxide fuel cell (e.g., solid oxide fuel cell 24) and driving an electric motor (e.g., electric motor 26) at 206 with the electricity from the solid oxide fuel cell, wherein the electric motor is operatively coupled via a gearbox (e.g., gearbox 20) to a ducted fan (e.g., ducted fan 46) of a turbofan engine (e.g., turbofan engine 44) of the aircraft. The gearbox may be driven at 238 by power from the electric motor and by mechanical shaft power provided at 236 (e.g., shaft 38 driven by the low-pressure turbine 34 of turbofan engine 44). Method 200 also includes driving the ducted fan at 240 via mechanical power from the gearbox and the electric motor, thereby providing thrust to the aircraft. In some instances, method 200 also includes generating electricity at 202 via a turbine generator, while simultaneously driving the electric motor via the turbine generator (e.g., turbine generator 22). Therefore, the drive motor at 206 can be implemented using a first amount of electricity generated at 204 from the solid oxide fuel cell and / or electricity generated at 202 by the turbine generator. In other words, powering the motor at 206 can include generating and supplying a first amount of electricity at 204 and / or generating and supplying a second amount of electricity at 202 to the motor at 206, optionally simultaneously. For operating the solid oxide fuel cell and the turbofan engine, at 242, liquefied natural gas can be supplied to the condenser and preheated, for example, from the fuel system (e.g., fuel system 72).

[0032] Method 200 may include cooling engine exhaust (e.g., engine exhaust 74) from a turbofan engine at 208 using liquefied natural gas as a coolant. Alternatively or additionally, liquefied natural gas from a fuel system (e.g., fuel system 72) may be preheated at 210 by engine exhaust (e.g., the outlet flow of low-pressure turbine 34). Some methods 200 include condensing liquefied natural gas from the fuel system of a hybrid propulsion system and engine exhaust from the turbofan engine at 212 (e.g., via condenser 76), and then recuperating the gaseous natural gas from the solid oxide fuel cell using fuel cell exhaust from the solid oxide fuel cell at 214 (e.g., via heat exchanger 78). Condensation at 212 may also include condensing liquid water in the engine exhaust from the turbofan engine. In some instances, heat recuperation at 214 includes preheating the gaseous natural gas using fuel cell exhaust from the solid oxide fuel cell. Alternatively or alternatively, some methods 200 include extracting water from engine exhaust downstream of the turbofan engine at 216 and generating water vapor (e.g., steam) (e.g., via water extractor 80), and adding the water vapor to natural gas from the fuel system at 218 to provide humidified natural gas to the anode (e.g., anode 90) of the solid oxide fuel cell.

[0033] Method 200 may include extracting bleed air from a duct fan of a turbofan engine at 220. In some instances, such as associated with the disclosed hybrid propulsion system 11, the extraction of bleed air is performed at 220 via a low-pressure compressor (e.g., low-pressure compressor 28) of the turbofan engine. In some instances, such as associated with the disclosed hybrid propulsion system 10, the extraction of bleed air is performed at 220 via a turbofan splitter (e.g., turbofan splitter 118) downstream of the duct fan. The bleed air may be supplied at 222 to the cathode (e.g., cathode 52) of a solid oxide fuel cell, such that the fan bleed air is used as source air for the solid oxide fuel cell. Prior to being supplied at 222, the bleed air (e.g., reactants) for the solid oxide fuel cell may be pretreated at 224 by compressing and / or pressurizing the bleed air via a compressor and turbine pair (e.g., compressor and turbine pair 54) of the turbofan engine and exhaust gas from the solid oxide fuel cell (e.g., fuel cell exhaust gas 64). Some methods 200 include controlling one or more conditions of the fuel reactants (e.g., bleed air) of a solid oxide fuel cell at 226 via a compressor and turbine pair, wherein the compressor of the compressor and turbine pair receives bleed air from a low-pressure compressor of a turbofan engine or from a turbofan splitter.

[0034] At 228, energy can be extracted from the fuel cell exhaust to process and / or fine-tune the bleed gas at the cathode of the solid oxide fuel cell via a compressor and turbine pair. In some instances, the power extracted from the fuel cell exhaust is limited or controlled at 230, maintaining the pressure of the fuel cell exhaust via a compressor and turbine pair, wherein the turbines of the compressor and turbine pair receive the fuel cell exhaust from the cathode of the solid oxide fuel cell. Alternatively or optionally, at 230, the pressure of turbine exhaust (e.g., turbine exhaust 70 from turbine 56) from the turbines in the compressor and turbine pair can be controlled or limited via a splitter upstream of the turbine and a mixer downstream of the turbine (e.g., splitter 66 and mixer 68). In some methods 200, the fuel cell exhaust can be mixed at 232 via a turbofan mixer (e.g., turbofan mixer 92) downstream of a heat exchanger into the outlet flow leaving the low-pressure turbine of the turbofan engine, thereby increasing the power generated by the downstream turbine operatively coupled to a turbine generator (e.g., turbine 100). In some instances, the ratio of power generated by a solid oxide fuel cell to power generated by a turbine generator is controlled at point 234, for example, through the electric motor control system of a hybrid propulsion system.

[0035] The following paragraphs describe illustrative, non-exclusive examples of the inventive subject matter according to this disclosure: A1. A hybrid propulsion system (10, 11) for an aircraft (12), said hybrid propulsion system (10, 11) comprising: Liquid natural gas solid oxide fuel cell (24); An electric motor (26) is driven by electricity (108) from the solid oxide fuel cell (24); A gearbox (20) operably coupled to the electric motor (26); and A turbofan engine (44) configured to generate thrust for the aircraft (12), wherein the turbofan engine (44) includes a duct fan (46) operably coupled to the electric motor (26) via the gearbox (20), and wherein the duct fan of the turbofan engine (44) is driven by mechanical power from the gearbox (20) and the electric motor (26).

[0036] A2. The hybrid propulsion system (10, 11) according to paragraph A1 further includes a turbine generator (22) operatively connected to the duct fan (46) and a turbine downstream of the turbine fan engine (44), in parallel with the solid oxide fuel cell (24).

[0037] A3. The hybrid propulsion system (10, 11) according to paragraph A2, wherein the electric motor (26) is simultaneously driven by electricity (108) from the solid oxide fuel cell (24) and the turbine generator (22).

[0038] A4. The hybrid propulsion system (10, 11) described in any of paragraphs A1-A3, wherein the turbofan engine (44) is configured to provide electric and / or shaft power.

[0039] A5. The hybrid propulsion system (10, 11) described in any of paragraphs A1-A4, wherein the hybrid propulsion system (10, 11) includes an electric motor controller configured to distribute a certain ratio of electrical load to the solid oxide fuel cell (24), the electric motor (26), and / or the turbine generator (22), thereby determining the fuel consumption ratio of the solid oxide fuel cell (24), the electric motor (26), and the turbine generator (22).

[0040] A5.1. The hybrid propulsion system (10, 11) according to paragraph A5, wherein the fuel consumption ratio determines the fuel ratio of the amount of fuel allocated by the fuel system (72) to each of the turbofan engine (44) and the solid oxide fuel cell (24).

[0041] A6. The hybrid propulsion system (10, 11) according to any of paragraphs A1-A5.1, wherein fan bleed air (120) extracted from the duct fan (46) of the turbofan engine (44) is used as the source air for the solid oxide fuel cell (24).

[0042] A7. The hybrid propulsion system (10, 11) according to any of paragraphs A1-A6 further includes a compressor and a turbine pair (54) configured to primarily compress and / or pressurize fan bleed air (120) from the duct fan (46) of the turbofan engine (44) to pretreat the fan bleed air (120) for use in the solid oxide fuel cell (24).

[0043] A7.1. The hybrid propulsion system (10, 11) according to paragraph A7, wherein the compressor and turbine pair (54) are configured to extract power from the fuel cell exhaust (64) of the solid oxide fuel cell (24).

[0044] A8. The hybrid propulsion system (10, 11) according to any one of paragraphs A1-A7 includes a compressor and a turbine pair (54), wherein the compressor and turbine pair (54) are configured to fine-tune one or more reactants for the solid oxide fuel cell (24).

[0045] A9. The hybrid propulsion system (10, 11) according to any of paragraphs A1-A8 further includes a splitter (66) and a mixer (68) configured to control the pretreatment operating conditions of the fan bleed air (120) of the solid oxide fuel cell (24).

[0046] A10. The hybrid propulsion system (10, 11) according to paragraph A9, wherein the splitter (66) and the mixer (68) are located downstream of the cathode (52) of the solid oxide fuel cell (24).

[0047] A11. The hybrid propulsion system (10, 11) according to any of paragraphs A9-A10, wherein the splitter (66) and the mixer (68) are mounted around the turbine (56) operatively coupled to the solid oxide fuel cell (24).

[0048] A12. The hybrid propulsion system (10, 11) according to any one of paragraphs A1-A11, wherein liquefied natural gas (122) is used as fuel or reactant for the turbofan engine (44) and the solid oxide fuel cell (24).

[0049] A13. The hybrid propulsion system (10, 11) according to any one of paragraphs A1-A12, wherein liquefied natural gas (122) is used to cool engine exhaust (74) from the turbofan engine (44).

[0050] A14. The hybrid propulsion system (10, 11) according to any one of paragraphs A1-A13, wherein the high-pressure fuel cell exhaust (64) from the solid oxide fuel cell (24) is mixed back into the engine exhaust (74) of the turbofan engine (44) via a turbofan mixer (92).

[0051] A15. The hybrid propulsion system (10, 11) according to any of paragraphs A1-A14, wherein liquefied natural gas (122) is used as a coolant for steam generation downstream of the turbofan engine (44).

[0052] A16. The hybrid propulsion system (10, 11) according to any one of paragraphs A1-A15, wherein steam is generated by extracting water condensed from the engine exhaust (74) of the turbofan engine (44).

[0053] A17. The hybrid propulsion system (10, 11) according to paragraph A16 further includes a condenser (76) configured to cool engine exhaust (74) from the turbofan engine (44) and condense liquid water from the engine exhaust (75).

[0054] A18. The hybrid propulsion system (10, 11) according to paragraph A17 further includes a water extractor (80) configured to extract liquid water from liquid water condensed from the engine exhaust (74) by the condenser (76).

[0055] A19. According to any of paragraphs A1-A18, the hybrid propulsion system (10, 11) wherein, before supplying the liquefied natural gas (122) to the anode (90) of the solid oxide fuel cell (24), the liquefied natural gas from the fuel system (72) of the hybrid propulsion system (10, 11) is preheated in a condenser (76) by engine exhaust (74).

[0056] A19.1. The hybrid propulsion system (10, 11) according to paragraph A19, wherein the condenser (76) is configured to convert the liquefied natural gas (122) into gaseous natural gas (82).

[0057] A19.2. The hybrid propulsion system (10, 11) according to paragraph A19.1, wherein the gaseous natural gas (82) is heated in a heat exchanger (78) by fuel cell exhaust (64).

[0058] A19.3. The hybrid propulsion system (10, 11) according to paragraph A19.2, wherein a portion of the gaseous natural gas (82) is received by a water extractor (80) and mixed with liquid water condensed from the engine exhaust (74) to obtain humidified natural gas (88).

[0059] A19.4. The hybrid propulsion system (10, 11) according to paragraph A19.3, wherein the humidified natural gas (88) is received by the anode (90) of the fuel cell.

[0060] A19.5. A hybrid propulsion system (10, 11) according to any of paragraphs A1-A19.4, wherein the anode (90) of the solid oxide fuel cell (24) includes an internal reformer configured to convert natural gas into hydrogen-rich gas.

[0061] A19.6. The hybrid propulsion system (10, 11) according to any of paragraphs A1-A19.4 further includes an external reformer (128) located upstream of the anode (90) of the solid oxide fuel cell (24), wherein the external reformer (128) is configured to convert natural gas into hydrogen-rich gas.

[0062] A20. The hybrid propulsion system (10, 11) according to any of paragraphs A1-A19.6 further includes a fuel system (72) configured to supply liquefied natural gas (122) to the turbofan engine (44) and the solid oxide fuel cell (24).

[0063] A21. The hybrid propulsion system (10, 11) according to any of paragraphs A1-A20 further includes a condenser (76) that receives the liquefied natural gas (122) from the fuel system (72), condenses engine exhaust (74) from the turbofan engine (44), and mixes the gaseous natural gas (82) with the condensed liquid water.

[0064] A21.1. A hybrid propulsion system (10, 11) according to any of paragraphs A1-A21, wherein a condenser (76) vaporizes the liquid natural gas (122) to form gaseous natural gas (82), and wherein the condenser (76) condenses liquid water from the engine exhaust (74) exiting the turbofan engine (44).

[0065] A22. The hybrid propulsion system (10, 11) according to any of paragraphs A1-A21.1 further includes a heat exchanger (78) located downstream of the condenser (76), wherein the heat exchanger (78) receives fuel cell exhaust (64) from the solid oxide fuel cell (24).

[0066] A23. The hybrid propulsion system (10, 11) according to paragraph A22, wherein the heat exchanger (78) supplies gaseous natural gas (82) to the turbofan engine (44).

[0067] A24. The hybrid propulsion system (10, 11) according to any of paragraphs A1-A23 further includes a water extractor (80) configured to receive air from a condenser (76), wherein the water extractor (80) extracts liquid water from engine exhaust (74) and adds the liquid water to liquid natural gas (122) to provide humidified natural gas (88) to the anode (90) of the solid oxide fuel cell (24).

[0068] A25. The hybrid propulsion system (10, 11) described in any of paragraphs A1-A24, wherein the hybrid propulsion system (10, 11) is configured such that the transient response time of the duct fan (46) of the turbofan engine (44) is fast enough to be suitable for the propulsion of the aircraft (12).

[0069] A26. A hybrid propulsion system (10, 11) according to any of paragraphs A1-A25, wherein the solid oxide fuel cell (24) and the turbofan engine (44) are operatively coupled together such that the transient response time of the turbofan engine (44) is reduced (accelerated) compared to a conventional system using only a fuel cell.

[0070] B1. An aircraft (12) comprising: Fuselage (60); Wings (62) supported by the fuselage (60); Turbofan engine (44); and The hybrid propulsion system (10, 11) described in any of paragraphs A1-A26.

[0071] B2. The aircraft (12) according to paragraph B1, wherein at least a portion of the hybrid propulsion system (10, 11) is supported by the wing (62).

[0072] B3. The aircraft (12) described in any of paragraphs B1-B2, wherein at least a portion of the hybrid propulsion system (10, 11) is housed within the wing (62).

[0073] B3.1. According to paragraph B3, the solid oxide fuel cell (24), compressor and turbine pair (54) and / or heat exchanger (78) of the hybrid propulsion system (10, 11) are housed within the wing (62).

[0074] B4. The aircraft (12) according to paragraph B3 or B3.1, wherein the turbogenerator (22), condenser (76), turbofan splitter (118) and / or electric motor (26) are housed within the turbofan engine (44).

[0075] B5. The aircraft (12) described in any of paragraphs B1-B4, wherein the turbofan engine (44) is supported by the wing (62).

[0076] B6. The aircraft (12) described in any of paragraphs B1-B5, wherein the turbofan engine (44) is supported by the tail (14) of the fuselage (60).

[0077] C1. A method (200) for providing thrust to an aircraft (12) via a hybrid propulsion system (10, 11), the method (200) comprising: A first amount of electricity (108) is generated (204) by a liquid natural gas solid oxide fuel cell (24) and used to drive (206) an electric motor (26), wherein the electric motor (26) is operatively coupled (20) to a duct fan (46) of a turbofan engine (44) of the aircraft (12) via a gearbox (20); and The thrust is provided to the aircraft (12) by mechanical power from the gearbox (20) and by driving the duct fan (46) of the turbine fan engine (44) via the electric motor (26) (240).

[0078] C2. The method (200) according to paragraph C1 further includes driving (206) the electric motor (26) via a turbine generator (22), while driving the electric motor with a first amount of electricity (108) from the solid oxide fuel cell (24).

[0079] C3. The method (200) according to any one of paragraphs C1-C2 further includes extracting (220) fan bleed air (120) from the duct fan (46) of the turbofan engine (44) via a turbofan splitter (118) downstream of the duct fan (46).

[0080] C3.1. The method (200) according to any one of paragraphs C1-C3 further includes extracting (220) fan bleed air (120) from the duct fan (46) of the turbofan engine (44) via the low-pressure compressor (28) of the turbofan engine (44).

[0081] C3.2. The method (200) according to paragraph C3 or C3.1 further includes using the fan bleed air (120) as the source air for the solid oxide fuel cell (24).

[0082] C4. The method (200) according to any one of paragraphs C1-C3.2 further includes compressing and / or pressurizing (224) the fan bleed air (120) from the duct fan (46) of the turbofan engine (44) to pretreat one or more reactants for the solid oxide fuel cell (24), wherein the compression and / or pressurization (224) is performed by the compressor and turbine pair (54) of the hybrid propulsion system (10, 11).

[0083] C5. The method (200) according to any one of paragraphs C1-C4 further includes extracting (228) power from the fuel cell exhaust (64) of the solid oxide fuel cell (24) via the compressor and turbine pair (54) of the hybrid propulsion system (10, 11).

[0084] C6. The method (200) according to any one of paragraphs C1-C5 further includes fine-tuning one or more reactants for the solid oxide fuel cell (24) via the compressor and turbine pair (54) of the hybrid propulsion system (10, 11).

[0085] C7. The method (200) according to any one of paragraphs C1-C6 further includes controlling (226) the pretreatment operating conditions for one or more reactants of the solid oxide fuel cell (24) via a splitter (66) and a mixer (68) of the hybrid propulsion system (10, 11).

[0086] C8. The method (200) according to any one of paragraphs C1-C7 further includes providing (242) liquefied natural gas (122) as fuel or reactant for the turbofan engine (44) and the solid oxide fuel cell (24).

[0087] C9. The method (200) according to any one of paragraphs C1-C8 further includes using liquefied natural gas (122) to cool (208) engine exhaust (74) from the turbofan engine (44).

[0088] C10. The method (200) according to any one of paragraphs C1-C9 further includes mixing (232) the high-pressure fuel cell exhaust (64) from the solid oxide fuel cell (24) back into the turbofan engine (44) via a turbofan mixer (118).

[0089] C11. The method (200) according to any one of paragraphs C1-C10 further includes using liquefied natural gas (122) as a coolant to generate (216) steam downstream of the turbofan engine (44).

[0090] C12. The method (200) according to any one of paragraphs C1-C11 further includes extracting (216) water condensed from the engine exhaust (74) of the turbofan engine (44) to generate steam.

[0091] C13. The method (200) according to any one of paragraphs C1-C12 further includes condensing (216) liquid water from engine exhaust (74) from the turbofan engine (44).

[0092] C14. The method described in paragraph C13 (200) further includes: Liquid natural gas (122) from the fuel system (72) of the hybrid propulsion system (10, 11) is preheated (210) in a condenser (76) via engine exhaust (74) from the turbofan engine (44), thereby producing gaseous natural gas (82); and The gaseous natural gas (82) is heated (210) in a heat exchanger (78) using fuel cell exhaust (64) from the solid oxide fuel cell (24).

[0093] C15. The method (200) described in paragraph C14 includes: The first portion of the gaseous natural gas (82) is supplied to the water extractor (80); The first portion of the gaseous natural gas (82) is mixed with the condensed liquid water to humidify the gaseous natural gas (82); After the mixing and humidification, the gaseous natural gas (82) is supplied to the anode (90) of the solid oxide fuel cell (24).

[0094] C16. The method (200) according to any one of paragraphs C1 to C15, wherein the method (200) is performed using the hybrid propulsion system (10, 11) described in any one of paragraphs A1 to A26.

[0095] D1. The hybrid propulsion system (10, 11) described in any of paragraphs A1-A26 serves to provide thrust to the aircraft (12).

[0096] Specifically, this application includes the following provisions.

[0097] Clause 1. A hybrid propulsion system (10, 11) for an aircraft (12), said hybrid propulsion system (10, 11) comprising: Liquid natural gas solid oxide fuel cell (24); An electric motor (26) is powered by electricity from the solid oxide fuel cell (24); A gearbox (20) operably coupled to the electric motor (26); and A turbofan engine (44) configured to generate thrust for the aircraft (12), wherein the turbofan engine (44) is configured to provide electric and shaft power, wherein the turbofan engine (44) includes a duct fan (46) operably coupled to the electric motor (26) via the gearbox (20), wherein the duct fan (46) of the turbofan engine (44) is driven by mechanical power from the gearbox (20) and the electric motor (26), wherein liquefied natural gas (122) is used as fuel for the turbofan engine (44) and the solid oxide fuel cell (24), and wherein the solid oxide fuel cell (24) and the turbofan engine (44) are operably coupled together to reduce the transient response time of the turbofan engine (44).

[0098] Clause 2. The hybrid propulsion system (10, 11) according to Clause 1, wherein fan bleed air (120) extracted from the duct fan (46) of the turbofan engine (44) is used as source air for the solid oxide fuel cell (24).

[0099] Clause 3. The hybrid propulsion system (10, 11) according to Clause 1 further includes a compressor and turbine pair (54) configured to primarily compress and pressurize fan bleed air (120) from the duct fan (46) of the turbofan engine (44) to pretreat the fan bleed air (120) for use in the solid oxide fuel cell (24).

[0100] Clause 4. The hybrid propulsion system (10, 11) according to Clause 3, wherein the compressor and turbine pair (54) is configured to extract power from the fuel cell exhaust (64) of the solid oxide fuel cell (24).

[0101] Clause 5. The hybrid propulsion system (10, 11) according to Clause 3 further includes a splitter (86) and a mixer (68) configured to control pretreatment operating conditions for fan bleed air (120) for the solid oxide fuel cell (24), wherein the splitter (86) and the mixer (68) are located downstream of the cathode (52) of the solid oxide fuel cell (24), and wherein the splitter (86) and the mixer (68) are mounted around the turbine (56) of the compressor and turbine pair (54), the turbine (56) being operatively coupled to the solid oxide fuel cell (24).

[0102] Clause 6. The hybrid propulsion system (10, 11) according to Clause 1, wherein steam is generated by extracting water condensed from the engine exhaust (74) of the turbofan engine (44).

[0103] Clause 7. A hybrid propulsion system (10, 11) for an aircraft (12), said hybrid propulsion system (10, 11) comprising: Liquid natural gas solid oxide fuel cell (24); An electric motor (26) is powered by electricity from the solid oxide fuel cell (24); A gearbox (20) operatively connected to the electric motor (26); A turbofan engine (44) configured to generate thrust for the aircraft (12), wherein the turbofan engine (44) includes a ducted fan (46) operably coupled to the electric motor (26) via the gearbox (20), and wherein the ducted fan (46) of the turbofan engine (44) is driven by mechanical power from the gearbox (20) and the electric motor (26); and A turbine generator (22) is operatively connected to the duct fan (46) and the turbine (56) downstream of the turbine fan engine (44), the turbine generator (22) being connected in parallel with the solid oxide fuel cell (24).

[0104] Clause 8. The hybrid propulsion system (10, 11) according to Clause 7, wherein the electric motor (26) is simultaneously driven by electricity from the solid oxide fuel cell (24) and from the turbine generator (22).

[0105] Clause 9. The hybrid propulsion system (10, 11) according to Clause 8, wherein the hybrid propulsion system (10, 11) includes an electric motor controller configured to distribute a certain ratio of electrical load to the solid oxide fuel cell (24), the electric motor (26) and the turbine generator (22), thereby determining the fuel consumption ratio of the solid oxide fuel cell (24), the electric motor (26) and the turbine generator (22).

[0106] Clause 10. The hybrid propulsion system (10, 11) according to Clause 7, wherein fan bleed air (120) extracted from the duct fan (46) of the turbofan engine (44) is used as source air for the solid oxide fuel cell (24).

[0107] Clause 11. The hybrid propulsion system (10, 11) according to Clause 7, wherein high-pressure fuel cell exhaust (64) from the solid oxide fuel cell (24) is mixed back into the turbofan engine (44) via a turbofan mixer (92) to increase power generation.

[0108] Clause 12. The hybrid propulsion system (10, 11) pursuant to Clause 7 further includes: A condenser (76) configured to cool engine exhaust (74) from the turbofan engine (44) and condense liquid water from the engine exhaust (74); and A water extractor (80) is configured to extract liquid water from the liquid water condensed from the engine exhaust (74) by the condenser (76).

[0109] Clause 13. The hybrid propulsion system (10, 11) according to Clause 12, wherein before the liquefied natural gas (122) from the fuel system (72) of the hybrid propulsion system (10, 11) is supplied to the anode (90) of the solid oxide fuel cell (24), the liquefied natural gas (122) is preheated by engine exhaust (74) in the condenser (76), wherein the condenser (76) is configured to convert the liquefied natural gas (122) into gaseous natural gas (82), wherein the gaseous natural gas (82) is heated in a regenerator (78) by fuel cell exhaust (64), wherein a portion of the gaseous natural gas (82) is received by the water extractor (80) and mixed with liquid water condensed from the engine exhaust (74) to form humidified natural gas, and wherein the humidified natural gas is received by the anode (90) of the solid oxide fuel cell (24).

[0110] Clause 14. The hybrid propulsion system (10, 11) according to Clause 7, wherein the hybrid propulsion system (10, 11) is configured such that the transient response time of the duct fan (46) of the turbofan engine (44) is fast enough to be suitable for the propulsion of the aircraft (12).

[0111] Clause 15. An aircraft (12) comprising: Fuselage (60); Wings supported by the fuselage (60); Turbofan engine (44); and Hybrid propulsion system (10, 11) as described in Clause 1.

[0112] Clause 16. An aircraft (12) comprising: Fuselage (60); Wings (62) supported by the fuselage (60); Turbofan engine (44); and Hybrid propulsion system (10, 11) as described in Clause 7.

[0113] Clause 17. A method (200) for providing thrust to an aircraft (12) via a hybrid propulsion system (10, 11), said method (200) comprising: A first amount of electricity (108) is generated (204) by a liquid natural gas solid oxide fuel cell (24) and used to drive an electric motor (26) (206), wherein the electric motor (26) is operatively coupled to the duct fan (46) of the turbofan engine (44) of the aircraft (12) via a gearbox (20); The aircraft (12) is provided with thrust by the mechanical power from the gearbox (20) and the electric motor (26) driving the duct fan (46) of the turbofan engine (44); Extract (220) fan bleed air (120) from the duct fan (46) of the turbofan engine (44); and The fan bleed air (120) is used as the source air for the solid oxide fuel cell (24).

[0114] Clause 18. The method (200) according to Clause 17 further includes driving (206) the electric motor (26) via a turbine generator (22), while driving (206) the electric motor (26) with a first amount of electricity from the solid oxide fuel cell (24).

[0115] Clause 19. The method (200) described pursuant to Clause 17 further includes: Compression (224) is applied to the bleed air (120) from the duct fan (46) of the turbofan engine (44) to pretreat one or more reactants of the solid oxide fuel cell (24), wherein the compression (224) is performed by the compressor and turbine pair (54) of the hybrid propulsion system (10, 11); and Power is extracted (228) from the fuel cell exhaust (64) of the solid oxide fuel cell (24) by the compressor and turbine pair (54) of the hybrid propulsion system (10, 11).

[0116] Clause 20. The method (200) according to Clause 17 further includes mixing (232) the high-pressure fuel cell exhaust (64) from the solid oxide fuel cell (24) back into the turbofan engine (44) via a turbofan mixer (92).

[0117] As used herein, the terms “suitable” and “configured” mean that an element, component, or other subject matter is designed and / or intended to perform a given function. Therefore, the use of the terms “suitable” and “configured” should not be construed as meaning that a given element, component, or other subject matter is merely “capable” of performing a given function, but rather that the element, component, and / or other subject matter is specifically selected, created, implemented, used, programmed, and / or designed to perform that function. Also within the scope of this disclosure, elements, components, and / or other subjects referred to as suitable for performing a particular function may additionally or optionally be described as being configured to perform that function, and vice versa. Similarly, subjects stated as being configured to perform a particular function may additionally or optionally be described as being operable to perform that function.

[0118] As used herein, the term “and / or” placed between the first entity and the second entity means (1) the first entity, (2) the second entity, and (3) one of the first and second entities. Multiple entries listed with “and / or” should be interpreted in the same way as “one or more” entities so combined. In addition to the entities expressly identified by the “and / or” clause, other entities may optionally exist, whether related to or unrelated to those expressly identified entities. Thus, as a non-restrictive example, when used in conjunction with open-ended language such as “includes”, a reference to “A and / or B” may in one instance refer only to A (optionally including entities other than B); in another instance refer only to B (optionally including entities other than A); and in yet another instance include both A and B (optionally including other entities). These entities may refer to elements, actions, structures, steps, operations, values, etc.

[0119] The various disclosed elements and steps of the devices and methods disclosed herein are not essential to all devices and methods according to this disclosure, which includes all novel and non-obvious combinations and sub-combinations of the various elements and steps disclosed herein. Furthermore, one or more of the various elements and steps disclosed herein may define an independent inventive subject matter separate from the overall disclosed device or method. Therefore, such inventive subject matter does not need to be associated with the specific device and method explicitly disclosed herein, and such inventive subject matter may find utility in devices and / or methods not explicitly disclosed herein.

Claims

1. A hybrid propulsion system (10, 11) for an aircraft (12), said hybrid propulsion system (10, 11) comprising: Liquid natural gas solid oxide fuel cell (24); An electric motor (26) is powered by electricity from the solid oxide fuel cell (24); A gearbox (20) operably coupled to the electric motor (26); and A turbofan engine (44) configured to generate thrust for the aircraft (12), wherein the turbofan engine (44) is configured to provide electric and shaft power, wherein the turbofan engine (44) includes a duct fan (46) operably coupled to the electric motor (26) via the gearbox (20), wherein the duct fan (46) of the turbofan engine (44) is driven by mechanical power from the gearbox (20) and the electric motor (26), wherein liquefied natural gas (122) is used as fuel for the turbofan engine (44) and the solid oxide fuel cell (24), and wherein the solid oxide fuel cell (24) and the turbofan engine (44) are operably coupled together to reduce the transient response time of the turbofan engine (44).

2. The hybrid propulsion system (10, 11) according to claim 1, wherein fan bleed air (120) extracted from the duct fan (46) of the turbofan engine (44) is used as source air for the solid oxide fuel cell (24).

3. The hybrid propulsion system (10, 11) according to claim 1 further includes a compressor and turbine pair (54) configured to primarily compress and pressurize fan bleed air (120) from the duct fan (46) of the turbofan engine (44) to pretreat the fan bleed air (120) for use in the solid oxide fuel cell (24).

4. The hybrid propulsion system (10, 11) according to claim 3, wherein the compressor and turbine pair (54) are configured to extract power from the fuel cell exhaust (64) of the solid oxide fuel cell (24).

5. The hybrid propulsion system (10, 11) according to claim 3 further includes a splitter (86) and a mixer (68) configured to control pretreatment operating conditions for fan bleed air (120) for the solid oxide fuel cell (24), wherein the splitter (86) and the mixer (68) are located downstream of the cathode (52) of the solid oxide fuel cell (24), and wherein the splitter (86) and the mixer (68) are mounted around the turbine (56) of the compressor and turbine pair (54), the turbine (56) being operatively coupled to the solid oxide fuel cell (24).

6. The hybrid propulsion system (10, 11) according to claim 1, wherein steam is generated by extracting water condensed from the engine exhaust (74) of the turbofan engine (44).

7. A hybrid propulsion system (10, 11) for an aircraft (12), said hybrid propulsion system (10, 11) comprising: Liquid natural gas solid oxide fuel cell (24); An electric motor (26) is powered by electricity from the solid oxide fuel cell (24); A gearbox (20) operatively connected to the electric motor (26); A turbofan engine (44) configured to generate thrust for the aircraft (12), wherein the turbofan engine (44) includes a ducted fan (46) operably coupled to the electric motor (26) via the gearbox (20), and wherein the ducted fan (46) of the turbofan engine (44) is driven by mechanical power from the gearbox (20) and the electric motor (26); and A turbine generator (22) is operatively connected to the duct fan (46) and the turbine (56) downstream of the turbine fan engine (44), the turbine generator (22) being connected in parallel with the solid oxide fuel cell (24).

8. The hybrid propulsion system (10, 11) according to claim 7, wherein the electric motor (26) is simultaneously driven by electricity from the solid oxide fuel cell (24) and the turbine generator (22).

9. The hybrid propulsion system (10, 11) according to claim 8, wherein the hybrid propulsion system (10, 11) includes an electronic engine controller configured to distribute a certain ratio of electrical load to the solid oxide fuel cell (24), the electric motor (26) and the turbine generator (22), thereby determining the fuel consumption ratio of the solid oxide fuel cell (24), the electric motor (26) and the turbine generator (22).

10. The hybrid propulsion system (10, 11) according to claim 7, wherein fan bleed air (120) extracted from the duct fan (46) of the turbofan engine (44) is used as source air for the solid oxide fuel cell (24).

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