Systems and methods of operating a fuel cell assembly, a gas turbine engine, or both

Abstract

A method for operating a propulsion system having a gas turbine engine and a fuel cell assembly is provided. The fuel cell assembly includes a fuel cell. The method includes receiving gas composition data from an output product of the fuel cell and controlling operation of the fuel cell assembly, the gas turbine engine, or both in response to the received gas composition data from the output product of the fuel cell.

Description

Technical Field

[0001] This disclosure relates to systems and methods for operating fuel cell components, gas turbine engines, or both. Background Technology

[0002] A gas turbine engine generally consists of a turbine and a rotor assembly. Gas turbine engines (such as turbofan engines) can be used for aircraft propulsion. In the case of a turbofan engine, the turbine includes a compressor section, a combustion section, and a turbine section in a sequential flow sequence, and the rotor assembly is configured as a fan assembly.

[0003] During operation, air is compressed in the compressor and mixed with fuel in the combustion section and ignited to generate combustion gases, which flow downwards through the turbine section. The turbine section extracts energy from the combustion gases to rotate the compressor section and fan assembly, thereby powering the gas turbine engine and propelling the aircraft containing this gas turbine engine during flight.

[0004] At least some gas turbine engines include fuel cell components that can operate in conjunction with them. Attached Figure Description

[0005] The complete and feasible disclosure of this disclosure, including its best mode, is set forth in the specification with reference to the accompanying drawings, for those skilled in the art, wherein:

[0006] Figure 1 This is a cross-sectional view of a gas turbine engine according to an exemplary aspect of this disclosure.

[0007] Figure 2 This is a perspective view of the integrated fuel cell and burner assembly according to this disclosure.

[0008] Figure 3 yes Figure 2 A schematic axial view of an exemplary integrated fuel cell and burner assembly.

[0009] Figure 4 This is a schematic diagram of a fuel cell assembly according to an exemplary aspect of the present disclosure, the fuel cell being incorporated into... Figure 2 An exemplary integrated fuel cell and burner assembly.

[0010] Figure 5 This is a schematic diagram of a gas turbine engine including an integrated fuel cell and burner assembly, according to an exemplary aspect of this disclosure.

[0011] Figure 6 This is a schematic diagram of a propulsion system according to another exemplary embodiment of the present disclosure.

[0012] Figure 7 This is a schematic diagram of a fuel cell assembly according to an exemplary embodiment of the present disclosure.

[0013] Figure 8 This is a schematic diagram of a fuel cell assembly according to another exemplary embodiment of the present disclosure.

[0014] Figure 9 It is a flowchart that graphically depicts the interrelationships of various aspects of the fuel cell assembly integrated into a gas turbine engine.

[0015] Figure 10 This is a flowchart of a method for operating a propulsion system according to an exemplary aspect of this disclosure.

[0016] Figure 11 This is a flowchart of a method for determining diagnostic information about a fuel cell leak, based on an exemplary aspect of this disclosure.

[0017] Figure 12 It is used to determine fuel cell leak diagnostic information related to external leaks. Figure 11 A flowchart of an exemplary aspect of the method.

[0018] Figure 13 It is used to determine fuel cell leak diagnostic information related to cross-leakage. Figure 11 A flowchart of an exemplary aspect of the method.

[0019] Figure 14 This is a flowchart of a method for determining carbon deposition diagnostic information according to an exemplary aspect of this disclosure.

[0020] Figure 15A This is a reporting module based on an exemplary aspect of this disclosure.

[0021] Figure 15B This is an inventory and maintenance table based on an exemplary aspect of this disclosure.

[0022] Figure 16 This is a flowchart of a method for operating a propulsion system according to another exemplary aspect of this disclosure.

[0023] Figure 17 This is a flowchart of a model-based control method according to an exemplary aspect of this disclosure.

[0024] Figure 18 This is a flowchart of a fuel cell model modified according to exemplary aspects of this disclosure.

[0025] Figure 19 This is a perspective view of the integrated fuel cell and burner assembly according to this disclosure.

[0026] Figure 20This is a schematic diagram of a propulsion system according to another exemplary embodiment of the present disclosure.

[0027] Figure 21 This is a schematic diagram of a propulsion system according to yet another exemplary embodiment of the present disclosure.

[0028] Figure 22 It is a method for operating a propulsion system that includes modular fuel cell components.

[0029] Figure 23 An embodiment of a multi-gas sensing system according to one embodiment is shown.

[0030] Figure 24 It shows Figure 23 The sensing circuit of the multi-gas sensing system is shown.

[0031] Figure 25 The system layout of a multi-gas sensing system according to one embodiment is shown.

[0032] Figure 26 A flowchart is shown as an embodiment of a method for sensing multiple different gas analytes using a multi-gas sensing system, according to one embodiment.

[0033] Figure 27 A diagram illustrating the electrical response of the various sensing elements of a multi-gas sensing system according to one embodiment is shown.

[0034] Figure 28 It shows Figure 27 The diagram illustrates the electrical response of the individual sensing elements in the multi-gas sensing system shown.

[0035] Figure 29 A diagram illustrating the response of a metal oxide sensing element to a gas of interest according to one embodiment is shown.

[0036] Figure 30 A diagram illustrating the quantification of gas concentration detected using a dielectric excitation gas according to one embodiment is shown.

[0037] Figure 31 The effect of water vapor on resistance and dielectric excitation response over a range of relative humidity is shown.

[0038] Figure 32 An illustration shows the operation of a multi-gas monitor under dynamic wind conditions according to one embodiment.

[0039] Figure 33 This is an illustration of the response of a sensing element to hydrogen and methane according to one embodiment.

[0040] Figure 34The illustration shows a quantitative representation of gas concentration detected using a dielectric excitation gas according to one embodiment. Detailed Implementation

[0041] Reference will now be made in detail to the present embodiments of this disclosure, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerals and letter reference numerals to denote features in the drawings. Similar or analogous reference numerals in the drawings and description have been used to denote similar or analogous portions of this disclosure.

[0042] The term "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as superior or better than other implementations. Furthermore, unless explicitly stated otherwise, all embodiments described herein should be considered exemplary.

[0043] For the purposes described below, the terms “upper,” “lower,” “vertical,” “horizontal,” “top,” “bottom,” and their derivatives should be associated with the embodiments in which they are oriented in the accompanying drawings. However, it should be understood that various alternative variations may be assumed in the embodiments unless explicitly stated otherwise. It should also be understood that the specific devices shown in the drawings and described in the following description are merely exemplary embodiments of this disclosure. Therefore, the specific dimensions and other physical characteristics associated with the embodiments disclosed herein should not be considered limiting.

[0044] As used herein, the terms “first,” “second,” and “third” are used interchangeably to distinguish one component from another and are not intended to indicate the location or importance of the individual components.

[0045] The terms "front" and "rear" refer to relative positions within a gas turbine engine or vehicle, and specifically to the normal operating posture of the gas turbine engine or vehicle. For example, in the case of a gas turbine engine, "front" refers to the position closer to the engine inlet, while "rear" refers to the position closer to the engine nozzle or exhaust port.

[0046] The terms "upstream" and "downstream" refer to the relative directions of fluid flow within a fluid path. For example, "upstream" refers to the direction from which the fluid flows, and "downstream" refers to the direction from which the fluid flows.

[0047] Unless otherwise specified herein, the terms “connection”, “fixation”, etc., refer to both direct connection, fixation or attachment and indirect connection, fixation or attachment via one or more intermediate components or features.

[0048] Unless the context clearly indicates otherwise, the singular forms “a,” “a,” and “the” include plural references.

[0049] In the context of, for example, “at least one of A, B and C” or “at least one of A, B or C”, the term “at least one” means only A, only B, only C, or any combination of A, B and C.

[0050] As used throughout the specification and claims, approximate language is applied to modify any quantitative expression that allows for variation without altering its underlying function. Therefore, values ​​modified by terms such as “about,” “approximate,” and “substantially” are not limited to specified exact values. In at least some cases, approximate language may correspond to the precision of the instrument used to measure the value, or the precision of the method or machine used to construct or manufacture the component and / or system. For example, approximate language may refer to margins of 1%, 2%, 4%, 10%, 15%, or 20%. These approximate margins may apply to a single value, to either end of a range defining a numerical value, or to margins between two ends, and / or between the ends.

[0051] Throughout this specification and claims, scope limitations are combined and interchanged, and unless the context or language otherwise indicates otherwise, such scopes are identified and include all subscopes contained herein. For example, all scopes disclosed herein include endpoints, and endpoints may be combined independently of each other.

[0052] As used herein, "third stream" refers to a non-mainstream flow that can increase fluid energy to generate a small amount of total propulsion thrust. The pressure ratio of the third stream can be higher than that of the main propulsion flow (e.g., bypass or propeller-driven propulsion flow). Thrust can be generated through dedicated nozzles or by mixing the airflow through the third stream with the main propulsion flow or core flow (e.g., mixing it into a common nozzle).

[0053] In some exemplary embodiments, the operating temperature of the airflow through the third flow can be below the engine's maximum compressor discharge temperature, and more specifically, below 350 degrees Fahrenheit (e.g., below 300 degrees Fahrenheit, below 250 degrees Fahrenheit, below 200 degrees Fahrenheit, and at least as high as ambient temperature). In some exemplary embodiments, these operating temperatures can facilitate heat transfer to or from the airflow through the third flow and the separate fluid flow. Furthermore, in some exemplary embodiments, under takeoff conditions, or more specifically, under operating conditions of sea-level rated takeoff power, static flight speed, and an ambient temperature of 86 degrees Fahrenheit, the airflow through the third flow can contribute less than 50% (and at least, for example, 2%) of the total engine thrust.

[0054] Furthermore, in some exemplary embodiments, the aforementioned exemplary percentage contribution of the third flow's airflow aspects (e.g., airflow, mixing, or exhaust properties) to the total thrust can be passively adjusted during engine operation or purposefully modified by using engine control features (such as fuel flow, motor power, variable stator, variable inlet guide vanes, valves, variable exhaust geometry, or fluid characteristics) to adjust or optimize overall system performance under a wide range of potential operating conditions.

[0055] The term "turbine" refers to a machine that includes one or more compressors, a heating section (e.g., a combustion section), and one or more turbines that together generate torque output.

[0056] The term "gas turbine engine" refers to an engine that has a turbine as its power source, in whole or in part. Examples of gas turbine engines include turbofan engines, turboprop engines, turbojet engines, turboshaft engines, and hybrid electric versions of one or more of these engines.

[0057] When used with compressors, turbines, shafts, or spool components, unless otherwise specified, the terms “low” and “high,” or their respective comparatives (e.g., “lower” and “higher,” where applicable), refer to relative speeds within the engine. For example, “low-speed turbine” or “low-turbine” defines a component constructed to operate at a rotational speed (such as the maximum permissible rotational speed) lower than that of a “high-speed turbine” or “high-turbine” at the engine.

[0058] As will be discussed in more detail below, a fuel cell is an electrochemical device that converts the chemical energy from a fuel (such as hydrogen) into electrical energy through an electrochemical reaction between the fuel and an oxidant (such as oxygen contained in the atmosphere). Fuel cell systems can be advantageously used as energy supply systems because they can be considered environmentally superior and highly efficient compared to at least some existing systems. To improve system efficiency and fuel utilization and reduce external water consumption, fuel cell systems may include an anode recirculation loop. Since a single fuel cell can only generate about 1V of voltage, multiple fuel cells can be stacked together (which may be called a fuel cell stack) to generate a desired voltage. Fuel cells can include solid oxide fuel cells (SOFC), molten carbonate fuel cells (MCFC), phosphoric acid fuel cells (PAFC), and proton exchange membrane fuel cells (PEMFC), which are generally named after their respective electrolytes. Each of these fuel cells may have specific benefits in the form of a preferred operating temperature range, power generation capacity, efficiency, etc.

[0059] Referring now to the accompanying drawings, where the same numbers indicate the same elements throughout all the drawings. Figure 1A schematic cross-sectional view of an engine according to an exemplary embodiment of the present disclosure is provided. The engine can be integrated into a vehicle. For example, the engine can be an aircraft engine integrated into an aircraft. However, alternatively, the engine can be any other suitable type of engine for any other suitable vehicle.

[0060] In the depicted embodiment, the engine is configured as a high-bypass turbofan engine 100. As... Figure 1 As shown, the turbofan engine 100 defines an axial direction A (extending parallel to the centerline axis 101 provided for reference), a radial direction R, and a circumferential direction (extending around the axial direction A; not shown in the diagram). Figure 1 (As shown in the figure). Typically, the turbofan engine 100 includes a fan section 102 and a turbine 104 disposed downstream of the fan section 102.

[0061] The depicted exemplary turbine 104 generally includes a substantially tubular housing 106 defining an annular inlet 108. The housing 106 surrounds, in a series flow relationship: a compressor section including a boost or low-pressure (LP) compressor 110 and a high-pressure (HP) compressor 112; a combustion section 114; a turbine section including a high-pressure (HP) turbine 116 and a low-pressure (LP) turbine 118; and an exhaust nozzle section 120. The compressor section, combustion section 114, and turbine section together at least partially define a core airflow path 121 extending from the annular inlet 108 to the exhaust nozzle section 120. The turbofan engine further includes one or more drive shafts. More specifically, the turbofan engine includes a high-pressure (HP) shaft or spool 122 drivingly connecting the HP turbine 116 to the HP compressor 112, and a low-pressure (LP) shaft or spool 124 drivingly connecting the LP turbine 118 to the LP compressor 110.

[0062] In the depicted embodiment, fan section 102 includes a fan 126 having a plurality of fan blades 128 spaced apart and coupled to disk 130. The plurality of fan blades 128 and disk 130 are rotatable together about a centerline axis 101 via LP shaft 124. Disk 130 is covered by a rotatable front hub 132, which is aerodynamically shaped to facilitate airflow through the plurality of fan blades 128. Furthermore, an annular fan housing or outer nacelle 134 is configured to circumferentially surround at least a portion of fan 126 and / or turbine 104. Nacelle 134 is supported relative to turbine 104 by a plurality of circumferentially spaced outlet guide vanes 136. A downstream section 138 of nacelle 134 extends over the outer portion of turbine 104 to define a bypass airflow passage 140 therebetween.

[0063] In this way, it will be understood that the turbofan engine 100 generally includes a first flow (e.g., a core airflow path 121) and a second flow extending parallel to the first flow (e.g., a bypass airflow passage 140). In some exemplary embodiments, the turbofan engine 100 may further define a third flow, for example, extending from the LP compressor 110 to the bypass airflow passage 140 or to the environment. With this configuration, the LP compressor 110 may generally include a first compressor stage configured as a ducted intermediate fan and a downstream compressor stage. The inlet of the third flow may be located between the first compressor stage and the downstream compressor stage.

[0064] Still referencing Figure 1 The turbofan engine 100 additionally includes an accessory gearbox 142 and a fuel delivery system 146. The fuel delivery system 146 may be an aircraft fuel supply unit, such as an aircraft fuel supply unit for an aircraft propulsion system. In the illustrated embodiment, the accessory gearbox 142 is located within the shroud / casing 106 of the turbine 104. Additionally, it will be understood that for... Figure 1 In the schematically depicted embodiment, accessory gearbox 142 is mechanically coupled to one or more shafts or spools of turbine 104 and is rotatable with one or more shafts or spools of turbine 104. For example, in the depicted exemplary embodiment, accessory gearbox 142 is mechanically coupled to HP shaft 122 via a suitable gear train 144 and is rotatable with HP shaft 122. Accessory gearbox 142 can provide power to one or more suitable accessory systems of turbofan engine 100 during at least some operations and can further provide power back to turbofan engine 100 during other operations. For example, in the illustrated embodiment, accessory gearbox 142 is coupled to starter motor / generator 152. Starter motor / generator can be configured to draw power from accessory gearbox 142 and turbofan engine 100 to generate electricity during some operations and can provide power back to accessory gearbox 142 and turbofan engine 100 (e.g., to HP shaft 122) during other operations to add mechanical work back to turbofan engine 100 (e.g., for starting turbofan engine 100).

[0065] Furthermore, the fuel delivery system 146 generally includes a fuel source 148 (such as a fuel tank) and one or more fuel delivery lines 150. One or more fuel delivery lines 150 supply fuel flow through the fuel delivery system 146 to the combustion section 114 of the turbine 104 of the turbofan engine 100. As will be discussed in more detail below, the combustion section 114 includes an integrated fuel cell and combustor assembly 200. In the described embodiment, one or more fuel delivery lines 150 supply fuel flow to the integrated fuel cell and combustor assembly 200.

[0066] However, it will be understood that, Figure 1 The exemplary turbofan engine 100 depicted is provided by way of example only. In other exemplary embodiments, any other suitable gas turbine engine may be used in conjunction with aspects of this disclosure. For example, in other embodiments, the turbofan engine may be any other suitable gas turbine engine, such as a turboshaft engine, a turboprop engine, a turbojet engine, etc. In this way, it will be further understood that in other embodiments, the gas turbine engine may have any other suitable construction, such as any other suitable number or arrangement of shafts, compressors, turbines, fans, etc. Furthermore, although Figure 1 The exemplary gas turbine engine depicted herein is schematically shown as a direct-drive fixed-pitch turbofan engine, but in other embodiments, the gas turbine engine of this disclosure may be a geared gas turbine engine (i.e., including a gearbox between a fan 126 and a shaft (such as LP shaft 124) driving the fan), a variable-pitch gas turbine engine (i.e., including a fan 126 having a plurality of fan blades 128 capable of rotating about their respective pitch axes), etc. Furthermore, although the exemplary turbofan engine 100 includes a ducted fan 126, in other exemplary aspects, the turbofan engine 100 may include a non-ducted fan 126 (or an open rotor fan) without a nacelle 134. Moreover, although not depicted herein, in other embodiments, the gas turbine engine may be any other suitable type of gas turbine engine, such as a marine gas turbine engine.

[0067] Now for reference Figure 2 The illustration schematically shows a portion of a combustion section 114 according to an embodiment of the present disclosure, which includes... Figure 1 Gas turbine engine 100 (above about Figure 1 Described as part of the integrated fuel cell and burner assembly 200 used in the turbofan engine 100.

[0068] It will be understood that the combustion section 114 includes a compressor diffuser nozzle 202 and extends generally along the axial direction A between an upstream end and a downstream end. The combustion section 114 is fluidly connected via the compressor diffuser nozzle 202 to the compressor section at the upstream end and to the turbine section at the downstream end.

[0069] The integrated fuel cell and burner assembly 200 generally includes fuel cell assembly 204. Figure 2 Only a partial description is provided; see also Figures 3 to 5The combustor 206 includes an inner liner 208, an outer liner 210, a dome assembly 212, a shroud assembly 214, a swirler assembly 216, and a fuel flow line 218. The combustion section 114 generally includes a housing 220 radially outward of the combustor 206 to surround it, and an inner housing 222 radially inward of the combustor 206. The inner housing 222 and the inner liner 208 define an inner passage 224 therebetween, while the outer housing 220 and the outer liner 210 define an outer passage 226 therebetween. The inner housing 222, the outer housing 220, and the dome assembly 212 together at least partially define the combustion chamber 228 of the combustor 206.

[0070] The dome assembly 212 is positioned near the upstream end of the combustion section 114 (i.e., closer to the upstream end than the downstream end) and includes an opening (not labeled) for receiving and retaining the swirler assembly 216. The swirler assembly 216 also includes an opening for receiving and retaining the fuel flow line 218. The fuel flow line 218 is further coupled to a fuel source 148 disposed radially R outside the housing 220 (see [link to fuel source 148]). Figure 1 It is configured to receive fuel from fuel source 148. In this way, fuel flow line 218 can be fluidly connected to the reference above. Figure 1 Describes one or more fuel delivery pipelines 150.

[0071] The swirler assembly 216 may include a plurality of swirlers (not shown) configured to swirl the compressed fluid before it is injected into the combustion chamber 228 to generate combustion gases. In the illustrated embodiment, the shroud assembly 214 is configured to hold the inner liner 208, the outer liner 210, the swirler assembly 216, and the dome assembly 212 together.

[0072] During operation, the compressor diffuser nozzle 202 is configured to direct compressed fluid 230 from the compressor section to the combustor 206, wherein the compressed fluid 230 is configured to mix with fuel within the cyclone assembly 216 and burn within the combustion chamber 228 to generate combustion gases. The combustion gases are supplied to the turbine section to drive one or more turbines of the turbine section (e.g., high-pressure turbine 116 and low-pressure turbine 118).

[0073] During operation of the gas turbine engine 100, which includes an integrated fuel cell and combustor assembly 200, the flame within the combustion chamber 228 is maintained by a continuous flow of fuel and air. To provide ignition of the fuel and air, for example during start-up of the gas turbine engine 100, the integrated fuel cell and combustor assembly 200 further includes an igniter 231. The igniter 231 can provide a spark or initial flame to ignite the fuel and air mixture within the combustion chamber 228. In some exemplary embodiments, the integrated fuel cell and combustor assembly 200 may additionally include a dedicated fuel cell igniter 233 (depicted in dashed lines). Specifically, for Figure 2 In one embodiment, a dedicated fuel cell igniter 233 is positioned downstream of at least a portion of the fuel cell, and particularly downstream of at least a portion of the fuel cell stack (described below). In this way, the dedicated fuel cell igniter 233 can more efficiently combust the fuel cell's output products.

[0074] As mentioned above and Figure 2 The diagram schematically depicts an integrated fuel cell and burner assembly 200, which further includes a fuel cell assembly 204. The depicted exemplary fuel cell assembly 204 includes a first fuel cell stack 232 and a second fuel cell stack 234. More specifically, the first fuel cell stack 232 is constructed together with an outer liner 210, and the second fuel cell stack 234 is constructed together with an inner liner 208. Even more specifically, the first fuel cell stack 232 is integrated with the outer liner 210, and the second fuel cell stack 234 is integrated with the inner liner 208. The operation of the fuel cell assembly 204, and more specifically, the operation of the fuel cell stacks (e.g., the first fuel cell stack 232 or the second fuel cell stack 234) of the fuel cell assembly 204, will be described in more detail below.

[0075] In the described embodiments, fuel cell assembly 204 is configured as a solid oxide fuel cell (“SOFC”) assembly, wherein a first fuel cell stack 232 is configured as a first SOFC fuel cell stack, and a second fuel cell stack 234 is configured as a second SOFC fuel cell stack (each having multiple SOFCs). It will be understood that an SOFC is generally an electrochemical conversion device that generates electricity directly by oxidizing fuel. Generally, fuel cell assemblies, and especially fuel cells, are characterized by the electrolyte material used. The SOFCs of this disclosure generally may include solid oxide or ceramic electrolytes. Such fuel cells generally exhibit high overall thermoelectric efficiency, long-term stability, fuel flexibility, and low emissions.

[0076] Furthermore, the exemplary fuel cell assembly 204 further includes a first power converter 236 and a second power converter 238. The first fuel cell stack 232 is electrically connected to the first power converter 236 via a first plurality of power cables (unlabeled), and the second fuel cell stack 234 is electrically connected to the second power converter 238 via a second plurality of power cables (unlabeled).

[0077] The first power converter 236 controls the current drawn from the corresponding first fuel cell stack 232 and can convert direct current (“DC”) power to DC power or alternating current (“AC”) power at another voltage level. Similarly, the second power converter 238 controls the current drawn from the second fuel cell stack 234 and can convert DC power to DC power or AC power at another voltage level. The first power converter 236, the second power converter 238, or both can be electrically connected to an electrical bus (such as electrical bus 326 described below).

[0078] The integrated fuel cell and burner assembly 200 further includes a fuel cell controller 240, which is operatively communicable with a first power converter 236 and a second power converter 238 to send and receive communications and signals, for example, between the two. For example, the fuel cell controller 240 can send current or power setpoint signals to the first power converter 236 and the second power converter 238, and can receive voltage or current feedback signals, for example, from the first power converter 236 and the second power converter 238. The fuel cell controller 240 can be configured in accordance with the following references. Figure 5 The fuel cell controller 240 described is constructed in the same manner.

[0079] It will be understood that, in at least some exemplary embodiments, the first fuel cell stack 232, the second fuel cell stack 234, or both may extend substantially 360 degrees in the circumferential direction C of the gas turbine engine (i.e., the direction in which it extends about the centerline axis 101 of the gas turbine engine 100). For example, now referring to... Figure 3 A simplified cross-sectional view of an integrated fuel cell and burner assembly 200 is depicted according to an exemplary embodiment of this disclosure. Although for simplicity... Figure 3 Only the first fuel cell stack 232 is depicted, but the second fuel cell stack 234 can be constructed in a similar manner.

[0080] As shown in the figure, the first fuel cell stack 232 extends around the combustion chamber 228 in the circumferential direction C, and in the illustrated embodiment, completely surrounds the combustion chamber 228 around the central axis 101. More specifically, the first fuel cell stack 232 includes a plurality of fuel cells 242 arranged in the circumferential direction C. Figure 3The fuel cell 242 visible in the image can be a single ring of fuel cell 242, wherein fuel cells 242 are stacked together along the axial direction A (see [link]). Figure 2 ( ), to form a first fuel cell stack 232. In another example, multiple additional rings of fuel cell 242 may be placed on top of each other to form a first fuel cell stack 232 extending along the centerline axis 101.

[0081] The following will explain this in more detail; please refer to [reference needed]. Figure 5 In the first fuel cell stack 232, fuel cell 242 is positioned to receive exhaust air 244 from, for example, a compressor section and fuel 246 from a fuel delivery system 146. Fuel cell 242 uses the air 244 and at least some of the fuel 246 to generate an electric current and guides partially oxidized fuel 246 and unused portion of air 248 radially toward the centerline axis 101 into combustion chamber 228. Integrated fuel cell and combustor assembly 200 combusts the partially oxidized fuel 246 and air 248 in combustion chamber 228 into combustion gases, which are then guided downstream into a turbine section to drive or assist in driving one or more turbines therein.

[0082] In addition, now refer to Figure 4 Provided as Figure 2 A schematic perspective view of the first fuel cell stack 232 of the integrated fuel cell and burner assembly 200. The second fuel cell stack 234 can be formed in a similar manner.

[0083] The depicted first fuel cell stack 232 includes a casing 250 having a combustion outlet side 252 and a side 254 opposite to the combustion outlet side 252, a fuel and air inlet side 256 and a side 588 opposite to the fuel and air inlet side 256, and sides 260 and 262. Sides 260, 258, and 254 are... Figure 4 It is not visible in the 3D image.

[0084] It will be understood that the first fuel cell stack 232 may include, for example, multiple fuel cells “stacked” side-by-side from one end of the first fuel cell stack 232 (e.g., fuel and air inlet side 256) to the other end of the first fuel cell stack 232 (e.g., side 258). Therefore, it will be further understood that the combustion outlet side 252 includes multiple combustion outlets 264, each combustion outlet originating from a fuel cell within the first fuel cell stack 232. During operation, combustion gases 266 (also referred to herein as “output products”) are directed from the combustion outlets 264 out of the housing 250. As described herein, the combustion gases 266 are generated using fuel and air not consumed by the fuel cells within the housing 250 of the first fuel cell stack 232. The combustion gases 266 are supplied to the combustion chamber 228 and combusted during operation to generate combustion gases used to generate thrust for the gas turbine engine 100 (and vehicles / aircraft in conjunction with the gas turbine engine 100).

[0085] The fuel and air inlet side 256 includes one or more fuel inlets 268 and one or more air inlets 270. Optionally, one or more of the inlets 268, 270 may be located on the other side of the housing 250. Each of the one or more fuel inlets 268 is fluidly connected to a fuel source (such as hydrogen gas or one or more pressurized containers of a fuel processing unit further described below) for the first fuel cell stack 232. Each of the one or more air inlets 270 is fluidly connected to an air source (such as air discharged from the compressor section and / or the air processing unit also further described below) for the fuel cell. The one or more inlets 268, 270 separately receive fuel and air from external fuel and air sources and separately direct the fuel and air into the fuel cell.

[0086] In some exemplary embodiments, Figures 2 to 4 The first fuel cell stack 232 may be constructed in a manner similar to one or more of the exemplary fuel cell systems (labeled 100) described, for example, in U.S. Patent Application Publication No. 2020 / 0194799A1, filed December 17, 2018, the entire contents of which are incorporated herein by reference. It will be further understood that... Figure 2 The second fuel cell stack 234 can be constructed in a similar manner to the first fuel cell stack 232, or alternatively, it can be constructed in any other suitable manner.

[0087] Now for reference Figure 5 The operation of the integrated fuel cell and burner assembly 200 according to exemplary embodiments of the present disclosure will be described. More specifically, Figure 5A schematic diagram of a gas turbine engine 100 and an integrated fuel cell and combustor assembly 200 according to embodiments of the present disclosure is provided. In some exemplary embodiments, the gas turbine engine 100 and the integrated fuel cell and combustor assembly 200 can be coupled with… Figures 1 to 4 One or more exemplary embodiments are constructed in a similar manner to those described above.

[0088] Therefore, it will be understood that the gas turbine engine 100 generally includes a fan section 102 with a fan 126, an LP compressor 110, an HP compressor 112, a combustion section 114, an HP turbine 116, and an LP turbine 118. The combustion section 114 generally includes an integrated fuel cell and combustor assembly 200 with a combustor 206 and a fuel cell assembly 204.

[0089] The propulsion system including the gas turbine engine 100 further includes a fuel delivery system 146. The fuel delivery system 146 generally includes a fuel source 148 and one or more fuel delivery lines 150. The fuel source 148 may include a supply section for fuel (e.g., hydrocarbon fuel, including, for example, carbon-neutral fuel or synthetic hydrocarbons) for the gas turbine engine 100. Furthermore, it will be understood that the fuel delivery system 146 also includes a fuel pump 272 and a distributor 274, and the one or more fuel delivery lines 150 include a first fuel delivery line 150A, a second fuel delivery line 150B, and a third fuel delivery line 150C. Diverter 274 divides the fuel flow from fuel source 148 and fuel pump 272 into a first fuel flow through a first fuel delivery line 150A to fuel cell assembly 204, a second fuel flow through a second fuel delivery line 150B also to fuel cell assembly 204 (and particularly to the air handling unit described below), and a third fuel flow through a third fuel delivery line 150C to burner 206. Diverter 274 may include a series of valves (not shown) to facilitate this diversion of the fuel flow from fuel source 148, or alternatively, may have a fixed geometry. Additionally, for the illustrated embodiment, fuel delivery system 146 includes a first fuel valve 151A associated with the first fuel delivery line 150A (e.g., for controlling the first fuel flow), a second fuel valve 151B associated with the second fuel delivery line 150B (e.g., for controlling the second fuel flow), and a third fuel valve 151C associated with the third fuel delivery line 150C (e.g., for controlling the third fuel flow).

[0090] The gas turbine engine 100 further includes a compressor exhaust system and an airflow delivery system. More specifically, the compressor exhaust system includes an LP bleed air duct 276 and an associated LP bleed air valve 278, an HP bleed air duct 280 and an associated HP bleed air valve 282, and an HP outlet air duct 284 and an associated HP outlet air valve 286.

[0091] The gas turbine engine 100 further includes an air supply duct 288 (in airflow communication with the air supply unit 290) and an associated air valve 292, which is also in airflow communication with the air delivery system, for providing compressed airflow to the fuel cell assembly 204 of the integrated fuel cell and combustor assembly 200. The air supply unit may be, for example, a second gas turbine engine configured to provide cross-bleed air, an auxiliary power unit (APU) configured to provide bleed air, a ram air turbine (RAT), an ambient location (e.g., free-flowing air), etc. If the compressor air source is insufficient or unavailable, the air supply unit may supplement the compressor exhaust system.

[0092] The compressor discharge system (and air supply duct 288) is in airflow communication with the airflow delivery system for supplying compressed airflow to the fuel cell assembly 204, as will be explained in more detail below.

[0093] Still referencing Figure 5 The fuel cell assembly 204, which integrates the fuel cell and burner assembly 200, includes a fuel cell stack 294, which can be constructed in a manner similar to, for example, the first fuel cell stack 232 described above. The fuel cell stack 294 is schematically depicted as a single fuel cell having a cathode side 296 (also referred to herein as "cathode 296"), an anode side 298 (also referred to herein as "anode 298"), and an electrolyte 300 (also referred to herein as an electrolyte layer) positioned between them. Generally, it will be understood that the electrolyte 300 can conduct negative oxygen ions from the cathode side 296 to the anode side 298 during operation to generate current and electricity.

[0094] In simple terms, it will be understood that the fuel cell assembly 204 further includes a fuel cell sensor 302 configured to sense data indicating operating parameters of the fuel cell assembly, such as the temperature of the fuel cell stack 294 (e.g., the cathode side 296 or anode side 298 of the fuel cell), the pressure within the fuel cell stack 294 (e.g., within the cathode side 296 or anode side 298 of the fuel cell), and / or the composition (e.g., chemical composition) of the output products from the fuel cell assembly 204. In this way, it will be understood that in some exemplary embodiments, the fuel cell sensor 302 may be a gas sensor, such as a multi-gas sensor.

[0095] The anode side 298 can support an electrochemical reaction that generates electricity. Fuel can be oxidized in the anode side 298 via diffusion through the electrolyte 300, utilizing oxygen ions received from the cathode side 296. This reaction can generate heat, vapor, and electricity in the form of free electrons in the anode side 298, which can be used to power energy-consuming devices (such as one or more additional electrical devices 328 described below). Oxygen ions can be generated using electrons returning from the energy-consuming device to the cathode side 296 via oxygen reduction of the cathode oxidant.

[0096] The cathode side 296 can be coupled to a cathode oxidant source, such as atmospheric oxygen. The cathode oxidant is defined as the oxidant supplied to the cathode side 296, which is used by the fuel cell system to generate electricity. The cathode side 296 can be permeable to oxygen ions received from the cathode oxidant.

[0097] Electrolyte 300 can be connected to both the anode side 298 and the cathode side 296. Electrolyte 300 allows oxygen ions to pass from the cathode side 296 to the anode side 298, and can have very low conductivity or no conductivity to prevent free electrons from passing from the cathode side 296 to the anode side 298.

[0098] The anode side of a solid oxide fuel cell (such as anode side 298 of fuel cell stack 294) can be made of nickel / yttrium oxide-stabilized zirconium oxide (Ni / YSZ) cermet. Nickel in the anode side serves as a catalyst for fuel oxidation and as a current conductor. During normal operation of fuel cell stack 294, the operating temperature can be greater than or equal to about 700°C, and the nickel (Ni) in the anode retains its reduced form due to the continuous supply of primarily hydrogen fuel gas. Alternatively, the anode side may include a small amount of nickel, or may be completely or substantially nickel-free.

[0099] The fuel cell stack 294 is located downstream of the LP compressor 110, the HP compressor 112, or both. Furthermore, from the above regarding... Figure 2 As will be understood from the description, fuel cell stack 294 may be coupled to or otherwise integrated with the bushings (e.g., inner liner 208 or outer liner 210) of burner 206. In this way, fuel cell stack 294 may also be arranged upstream of combustion chamber 228, which integrates fuel cell and burner assembly 200, and further upstream of HP turbine 116 and LP turbine 118.

[0100] like Figure 5 As shown, the fuel cell assembly 204 also includes a fuel processing unit 304 and an air processing unit 306. The fuel processing unit 304 can be any suitable structure for generating a hydrogen-rich fuel stream. For example, the fuel processing unit 304 may include a fuel reformer or a catalytic partial oxidation converter (CPO). xAn air handling unit 306 is used to generate a hydrogen-rich fuel stream for the fuel cell stack 294. The air handling unit 306 can be any suitable structure for raising the temperature of the air supplied to it to a temperature sufficiently high to achieve fuel cell temperature control (e.g., about 600°C to about 800°C). For example, in the depicted embodiment, the air handling unit includes a pre-burner system that operates based on the fuel stream via a second fuel delivery line 150B and is configured to raise the air temperature by combustion, for example, during transient conditions such as start-up, shutdown, and abnormal situations.

[0101] In the exemplary embodiment depicted, the fuel processing unit 304 and the air processing unit 306 are manifolded together within the housing 308 to provide conditioned air and fuel to the fuel cell stack 294.

[0102] However, it should be understood that the fuel processing unit 304 may additionally or alternatively include any suitable type of fuel reformer, including but not limited to catalytic partial oxidizers, automatic thermal reformers, or steam reformers, which may require an additional steam inlet stream with a higher hydrogen composition at the reformer outlet stream. Additionally or alternatively, the fuel processing unit 304 may also include a reformer integrated with the fuel cell stack 294. Similarly, it should be understood that... Figure 5 The air handling unit 306 may alternatively be a heat exchanger or another device for raising the temperature of the air supplied thereto to a temperature sufficient to achieve fuel cell temperature control (e.g., about 600°C to about 800°C).

[0103] As described above, the compressor discharge system (and air supply duct 288) is in airflow communication with the airflow delivery system for providing compressed airflow to the fuel cell assembly 204. The airflow delivery system includes an anode airflow duct 310 and associated anode airflow valve 312 for providing airflow to the fuel processing unit 304, a cathode airflow duct 314 and associated cathode airflow valve 316 for providing airflow to the air processing unit 306, and a cathode bypass air duct 318 and associated cathode bypass air valve 320 for providing airflow directly to the fuel cell stack 294 (or more precisely, to the cathode side 296 of the fuel cell). The fuel delivery system 146 is configured to provide a first fuel flow to the fuel processing unit 304 via a first fuel delivery line 150A and a second fuel flow to the air processing unit 306 via a second fuel delivery line 150B (e.g., as fuel for the pre-combustor system, if provided).

[0104] The fuel cell stack 294 outputs electricity as the fuel cell power output 322. In addition, the fuel cell stack 294 directs cathode air emissions and anode fuel emissions (not labeled for clarity) into the combustion chamber 228 of the burner 206.

[0105] In operation, the air treatment unit 306 is configured to heat / cool a portion of the compressed air entering through the cathode airflow duct 314 to generate treated air to be guided into the fuel cell stack 294, thereby facilitating the operation of the fuel cell stack 294. The air treatment unit 306 receives a second fuel flow from the second fuel delivery line 150B and can, for example, combust this second fuel flow to heat the received air to a desired temperature (e.g., about 600°C to about 800°C), thereby facilitating the operation of the fuel cell stack 294. The air treated by the air treatment unit 306 is guided into the fuel cell stack 294. In embodiments of this disclosure, as shown, the cathode bypass air duct 318 and the air treated by the air treatment unit 306 can be combined into a combined airflow to be fed into the cathode 296 of the fuel cell stack 294.

[0106] In addition, such as Figure 5 As shown in the embodiment, a first fuel flow via a first fuel delivery line 150A is directed to a fuel processing unit 304 for generating a hydrogen-rich fuel flow (e.g., optimizing the hydrogen content of the fuel flow), which is also fed into the fuel cell stack 294. It will be understood, and discussed below, that the air (processing air and bypass air) flow to the fuel cell stack 294 (e.g., cathode side 296) and the fuel from the fuel processing unit 304 to the fuel cell stack 294 (e.g., anode side 298) can facilitate power generation.

[0107] Since the inlet air to the fuel cell stack 294 may originate solely from the upstream compressor section without any other separately controlled air source, it will be understood that the inlet air to the fuel cell stack 294 discharged from the compressor section will be affected by air temperature variations occurring at different stages of flight. As an illustrative example only, the air in a specific location within the compressor section of the gas turbine engine 100 may operate at 200°C during idling, 600°C during takeoff, 268°C during cruise, and so on. This type of temperature variation in the inlet air directed to the fuel cell stack 294 can cause significant thermal transient problems (or even thermal shock) to the ceramic material of the fuel cell stack 294, potentially ranging from cracking to failure.

[0108] Therefore, by fluidly connecting the air handling unit 306 between the compressor section and the fuel cell stack 294, the air handling unit 306 can serve as a control device or system to maintain the air processed by the air handling unit 306 and directed into the fuel cell stack 294 within a desired operating temperature range (e.g., ±100°C, or preferably ±50°C, or ±20°C). During operation, the temperature of the air supplied to the fuel cell stack 294 (relative to the temperature of the air discharged from the compressor section) can be controlled by controlling the fuel flow to the air handling unit 306. Increasing the fuel flow to the air handling unit 306 can raise the temperature of the airflow to the fuel cell stack 294. Decreasing the fuel flow to the air handling unit 306 can lower the temperature of the airflow to the fuel cell stack 294. Optionally, fuel cannot be supplied to the air handling unit 306 to prevent the air handling unit 306 from raising and / or lowering the temperature of the air discharged from the compressor section and directed into the air handling unit 306.

[0109] Furthermore, as depicted in dashed lines, the fuel cell assembly 204 further includes an airflow bypass duct 321 extending around the fuel cell to allow part or all of the airflow regulated by the air handling unit 306 (and combined with any bypass air passing through duct 318) to bypass the cathode side 296 of the fuel cell and enter directly into the combustion chamber 228. The airflow bypass duct 321 may be in thermal communication with the fuel cell. The fuel cell assembly further includes a fuel bypass duct 323 extending around the fuel cell to allow part or all of the reformed fuel from the fuel handling unit 304 to bypass the anode side 298 of the fuel cell and enter directly into the combustion chamber 228.

[0110] As briefly mentioned above, fuel cell stack 294 converts the anode fuel stream from fuel processing unit 304 and the air processed by air processing unit 306 into electrical energy in the form of DC current, i.e., fuel cell power output 322. This fuel cell power output 322 is directed to power converter 324 to convert the DC current into DC or AC current that can be efficiently utilized by one or more subsystems. Specifically, in the depicted embodiment, power is supplied from the power converter to electrical bus 326. Electrical bus 326 may be an electrical bus dedicated to gas turbine engine 100, an electrical bus of an aircraft in conjunction with gas turbine engine 100, or a combination thereof. Electrical bus 326 is electrically connected to one or more auxiliary electrical devices 328, which may be a power source, a power sink, or both. For example, auxiliary electrical devices 328 may be energy storage devices (such as one or more batteries), motors (generators, electric motors, or both), electric propulsion devices, etc. For example, one or more auxiliary electrical devices 328 may include a starter motor / generator of gas turbine engine 100.

[0111] Still referencing Figure 5 The gas turbine engine 100 further includes a sensor 330. In the illustrated embodiment, the sensor 330 may be configured to sense data indicating the flame within the combustion section 114 of the gas turbine engine 100, or some other parameter indicating the operating conditions of the gas turbine engine. The sensor 330 may be, for example, a temperature sensor configured to sense data indicating the outlet temperature of the combustion section 114, the inlet temperature of the turbine section, the exhaust temperature, or a combination thereof. Additionally or alternatively, the sensor 330 may be any other suitable sensor, or any suitable combination of sensors, configured to sense one or more gas turbine engine operating conditions or parameters, including data indicating the flame within the combustion section 114 of the gas turbine engine 100.

[0112] In addition, such as Figure 5 Further schematically depicted, the propulsion system, the aircraft including the propulsion system, or both include controller 240. For example, controller 240 may be a standalone controller, a gas turbine engine controller (e.g., a full authority digital engine controller or a FADEC controller), an aircraft controller, a supervisory controller for the propulsion system, or combinations thereof.

[0113] The controller 240 is operatively connected to various sensors, valves, etc., within at least one of the gas turbine engine 100 and the fuel delivery system 146. More specifically, for the exemplary aspects depicted, the controller 240 is operatively connected to valves (valve 278, 282, 286) of the compressor discharge system, valves (valve 312, 316, 320) of the gas flow delivery system, and valves (splitter 274, valves 151A, 151B, 151C) of the fuel delivery system 146, as well as sensors 330 of the gas turbine engine 100 and fuel cell sensor 302. It will be understood from the following description that the controller 240 can communicate wirelessly with these components, either wired or wirelessly. In this way, the controller 240 can receive data from various inputs (including gas turbine engine sensor 330 and fuel cell sensor 302), make control decisions, and provide data (e.g., instructions) to various outputs (including valves of the compressor discharge system that control the airflow discharge from the compressor section, the airflow delivery system that guides the airflow discharge from the compressor section, and the fuel delivery system 146 that guides the fuel flow within the gas turbine engine 100).

[0114] Referring specifically to the operation of controller 240, in at least some embodiments, controller 240 may include one or more computing devices 332. Computing device 332 may include one or more processors 332A and one or more memory devices 332B. The one or more processors 332A may include any suitable processing means, such as a microprocessor, microcontroller, integrated circuit, logic device, and / or other suitable processing means. The one or more memory devices 332B may include one or more computer-readable media, including but not limited to non-transitory computer-readable media, RAM, ROM, hard disk drives, flash drives, and / or other memory devices.

[0115] One or more memory devices 332B may store information accessible by one or more processors 332A, including computer-readable instructions 332C executable by one or more processors 332A. Instructions 332C may be any set of instructions that, when executed by one or more processors 332A, cause one or more processors 332A to operate. In some embodiments, instructions 332C may be executed by one or more processors 332A to cause one or more processors 332A to operate, such as any operations and functions configured for the controller 240 and / or computing device 332, operations for operating the propulsion system as described herein (e.g., methods 700, 800, 900, 1000, 1100, 1300), and / or any other operations or functions of one or more computing devices 332. Instructions 332C may be software written in any suitable programming language or may be implemented in hardware. Additionally and / or alternatively, instructions 332C may be executed in logically and / or virtually decoupled threads on the processor 332A. The memory device 332B may further store data 332D that can be accessed by the processor 332A. For example, data 332D may include data indicating power flow, data indicating operating conditions of the gas turbine engine 100 / aircraft, and / or any other data and / or information described herein.

[0116] The computing device 332 also includes a network interface 332E, which is configured to communicate, for example, with other components of the gas turbine engine 100 (such as valves of the compressor exhaust system (valve 278, 282, 286), valves of the airflow delivery system (valve 312, 316, 320), and valves of the fuel delivery system 146 (splitter 274, valves 151A, 151B, 151C), as well as sensors 330 and fuel cell sensors 302 of the gas turbine engine 100), and with an aircraft associated with the gas turbine engine 100. The network interface 332E may include any suitable components for communication with one or more network interfaces, including, for example, transmitters, receivers, ports, controllers, antennas, and / or other suitable components. In this way, it will be understood that the network interface 332E can utilize any suitable combination of wired and wireless communication networks.

[0117] The techniques discussed in this paper refer to computer-based systems, actions taken by computer-based systems, and information sent to and from computer-based systems. It will be understood that the inherent flexibility of computer-based systems allows for a wide variety of possible configurations, combinations, and divisions of tasks and functionalities between and within components. For example, the processes discussed herein can be implemented using a single computing device or multiple computing devices working in combination. Databases, memory, instructions, and applications can be implemented on a single system or distributed across multiple systems. Distributed components can operate sequentially or in parallel.

[0118] It will be understood that the gas turbine engine 100, the exemplary fuel delivery system 146, the exemplary integrated fuel cell and combustor assembly 200, and the exemplary fuel cell assembly 204 are provided as examples only. In other embodiments, the integrated fuel cell and combustor assembly 200 and the fuel cell assembly 204 may have any other suitable configuration. For example, in other exemplary embodiments, the fuel cell assembly 204 may include any other suitable fuel processing unit 304. Additionally or alternatively, for example when the combustor of the gas turbine engine 100 is configured to burn hydrogen fuel, and the fuel delivery assembly 146 is configured to supply hydrogen fuel to the integrated fuel cell and combustor assembly 200, particularly to the fuel cell assembly 204, the fuel cell assembly 204 may not require the fuel processing unit 304.

[0119] Now for reference Figure 6 The present disclosure provides a schematic diagram of a propulsion system according to another exemplary embodiment. The exemplary propulsion system generally includes a thruster, a turbine 104, and a fuel cell assembly 204, the turbine 104 being operable to drive the thruster to generate thrust during operation, and the fuel cell assembly 204 being configured to add power to the thruster, the turbine 104, or both.

[0120] In particular, for Figure 6 In an embodiment, the propulsion system is to interact with Figure 5 The exemplary propulsion system is constructed in a similar manner. In this way, it will be understood that the thruster and turbine 104 together form a gas turbine engine 100, wherein the thruster is configured as a fan section 102 having a fan 126 driven by the turbine 104 to generate thrust. Similarly, for the illustrated embodiment, a fuel cell assembly 204 is integrated into the gas turbine engine 100. More specifically, for the illustrated embodiment, the turbine 104 includes a combustion section 114 having a combustor 206, and the fuel cell assembly 204 includes a fuel cell stack 294 having fuel cells, wherein the fuel cells define an outlet location to remove output products from the fuel cells and to supply output products to the combustor 206.

[0121] The propulsion system's fuel delivery system 146 is configured to supply fuel flow to the burner 206 via burner fuel delivery line 150C (described above as third fuel line 150C), and is further configured to supply fuel flow to the fuel cell assembly 204 (“FCA”) via fuel delivery line 150A (described above as first fuel line 150A).

[0122] for Figure 6In one embodiment, the fuel cell assembly 204 further includes a pneumatic delivery system and a fuel processing unit 304, which, as will be understood from the above discussion, can be configured as a fuel reformer. The fuel processing unit 304 is configured to receive pneumatic flow from pneumatic delivery conduit 334 of the pneumatic delivery system and fuel flow from FCA fuel delivery line 150A. The fuel processing unit 304 is further configured to supply fuel flow to the fuel cells of the fuel cell stack 294 via a first fuel cell fuel delivery line 336 of the fuel cell assembly 204, and can further bypass the fuel cells of the fuel cell stack 294 by directly supplying fuel flow to the burner 206 via a second fuel cell fuel delivery line 338 of the fuel cell assembly 204.

[0123] It is worth noting that, in order to achieve the desired level of health monitoring, maintenance guidance, control, and / or fault detection for the gas turbine engine 100, fuel cell assembly 204, or both, the propulsion system further includes a gas sensor 350 (generally referred to as "350"). Figure 6 Individually designated 350A-F), gas sensor 350 is capable of operating in conjunction with turbine 104, fuel cell assembly 204, or both, to sense gas composition data of fluid flows into or to turbine 104, fuel cell assembly 204, or both. As used herein, the term "gas composition data" generally refers to data relating to the identification of one or more gases within a fluid flow and the percentage of one or more gases within the fluid flow (e.g., the percentage of fluid flow as gas A (where "gas A" refers to one of the gases disclosed herein)). Unless otherwise stated, gas composition percentages provided herein refer to volume percentages.

[0124] More specifically, for the exemplary embodiment depicted, the gas sensor 350 is configured as a multi-gas sensor such that the gas composition data includes data indicating at least two gas components. The at least two gas components may be two gas components within the same fluid flow or multiple fluid flows.

[0125] More specifically, in the described embodiments, the propulsion system includes multiple multi-gas sensors.

[0126] Specifically, in the described embodiment, the propulsion system includes a fuel gas sensor 350A, which is configured to sense gas composition data of the fuel flow supplied to the burner 206 via the burner fuel delivery line 150C. Specifically, in the illustrated embodiment, the fuel gas sensor 350A is positioned in line with the burner fuel delivery line 150C of the fuel delivery system 146.

[0127] As schematically depicted in circle 6A, the fuel gas sensor 350A is a multi-gas sensor having a sensing circuit 352 with one or more sensing elements 354; a management circuit 356; and one or more processors 358. The management circuit 356 is configured to excite the one or more sensing elements 354 using an alternating current at one or more frequencies, and is further configured to measure one or more electrical responses of the one or more sensing elements 354 in response to excitation by the alternating current at one or more frequencies. The management circuit 356 is configured to determine one or more characteristics of the sensing circuit 352. The one or more processors 358 are configured to receive one or more electrical responses of the one or more sensing elements 354 and one or more characteristics of the sensing circuit 352. The one or more processors 358 are further configured to determine gas composition data based on one or more electrical responses of the one or more sensing elements 354 and one or more characteristics of the sensing circuit 352. (Refer to below...) Figures 23 to 32 A more detailed description of this construction is provided.

[0128] However, it will be understood that in other exemplary embodiments, any other suitable gas sensor technology or multi-gas sensor technology may be used, as discussed in more detail below.

[0129] Referring again to the close-up in circle 6A, as described above, the fuel gas sensor 350A is positioned aligned with the burner fuel delivery line 150C of the fuel delivery system 146. In this way, it will be understood that one or more sensing elements 354 of the sensing circuit 352 of the fuel gas sensor 350A can be directly exposed to the fuel flow through the burner fuel delivery line 150C during operation of the propulsion system.

[0130] It will be understood that by sensing gas composition data of the fuel flow supplied to combustor 206, variations in the fuel flow supplied to combustor 206 can be determined and taken into account through the control of gas turbine engine 100, fuel cell assembly 204, or both. For example, in some exemplary aspects, gas turbine engine 100 may be configured to receive aviation fuel, sustainable fuel, or a combination thereof during operation. In any case, by sensing the gas composition data, variations in fuel composition or other properties of the fuel (which may simply be caused by receiving fuel from different fuel tanks of fuel delivery system 146) can be determined, and the operation of gas turbine engine 100, fuel cell assembly 204, or both can be adjusted to account for such variations. This variation can take into account different calorific values / enthalpy of the fuel.

[0131] Still referencing Figure 6The propulsion system further includes an airflow gas sensor 350B, which operates in conjunction with the airflow delivery assembly to sense gas composition data of the airflow passing through the airflow delivery assembly (and more specifically, through the airflow duct 334) to the fuel processing unit 304. In this way, the airflow gas sensor 350B can be configured to sense gas composition data of the airflow, including the percentage of oxygen in the airflow, the percentage of nitrogen in the airflow, the percentage of air impurities (e.g., carbon dioxide, sulfur, etc.) in the airflow, etc. This gas composition data can be used to control, for example, the fuel cell assembly 204 by allowing a specific volume of oxygen to be supplied to the fuel processing unit 304, the fuel cell stack 294, or both. Furthermore, this gas composition data can be used to inform a baseline for determining fuel cell leaks and fuel cell diagnostic information, as described below.

[0132] Additionally, the propulsion system includes a first fuel cell gas sensor 350C and a second fuel cell gas sensor 350D. The first fuel cell gas sensor 350C is operable with the fuel flow through the first fuel cell fuel delivery line 336, and the second fuel cell gas sensor 350D is operable with the fuel flow through the second fuel cell fuel delivery line 338. In this way, the first fuel cell gas sensor 350C can be configured to sense gas composition data of the fuel flow at locations downstream of the fuel processing unit 304 and upstream of the fuel cell, and the second fuel cell gas sensor 350D can be configured to sense gas composition data of the fuel flow bypassing the fuel cell and fuel cell stack 294 at locations downstream of the fuel processing unit 304 and upstream of the burner 206. The gas composition data sensed by the first fuel cell gas sensor 350C, the second fuel cell gas sensor 350D, or both may include the percentage of hydrogen in the fuel flow to determine, for example, the calorific value / enthalpy of the fuel. Other gas composition data from the first fuel cell gas sensor 350C, the second fuel cell gas sensor 350D, or both include carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), light hydrocarbons such as C2-C4; nitrogen (N2), vapor, ammonia (NH3), non-volatile particulate matter (PM) and volatile PM, other major components of the fuel, other minor components of the fuel, and other components of the fuel.

[0133] Furthermore, the propulsion system includes an output product gas sensor 350E and an oxygen sensor 350F. The output product gas sensor 350E is configured to sense gas composition data of the output product stream from the fuel cell stack 294 at locations downstream of the fuel cell and upstream of the burner 206. The oxygen sensor 350F can be configured to sense gas composition data of the fluid surrounding the fuel cell stack 294, such as the oxygen content of the fluid surrounding the fuel cell stack 294 (e.g., for leak detection and diagnostics), the content of combustible gases (such as hydrogen) in the fluid surrounding the fuel cell stack 294 (e.g., as a safety sensor), etc.

[0134] Similar to the first fuel cell gas sensor 350C and the second fuel cell gas sensor 350D, the output product gas sensor 350E can be configured to sense gas composition data, including the percentage of hydrogen in the output product. This can again allow for determining the calorific value of the output product / how much enthalpy is supplied from the fuel cell to the combustor 206, for example, for controlling the fuel cell assembly 204, the gas turbine engine 100, or both.

[0135] Additionally or alternatively, the output product gas sensor 350E may be configured to sense gas composition data indicating the percentage of H2O, carbon dioxide, nitrogen, etc., in the output products. This gas composition data can be used to control the fuel cell assembly 204, the gas turbine engine 100, or both, for example, for emission purposes and / or to determine health information of the fuel cell assembly 204 (e.g., for diagnosing leaks within the fuel cell assembly 204, etc.).

[0136] Now for reference Figure 7 It depicts Figure 6 A close-up schematic diagram of the fuel cell in the fuel cell stack 294 of the exemplary fuel cell assembly 204, which has an output product gas sensor 350E. It is noteworthy that, for the described embodiment, the fuel cell assembly 204 further includes a housing portion 360 that at least partially surrounds the fuel cell, and although not depicted, the fuel cell stack 294 includes the fuel cell. The housing portion 360 may be formed by one or more walls positioned around the fuel cell (and fuel cell stack 294). For example, when... Figure 7 Exemplary fuel cells incorporated into Figure 2 When depicted in the above-described fuel cell assembly 204, the outer casing 360 can be positioned between the outer liner 210 and the outer casing 220 to protect the fuel cell stack 294 from external passages 226 (see [reference]). Figure 2 The outer casing 360 can further help maintain the temperature of the fuel cell (and fuel cell stack 294) at the desired operating temperature, thus mitigating the influence of airflow.

[0137] Furthermore, for Figure 7 In one embodiment, the gas sensor 350E is configured to sense gas composition data from the output product streams of the fuel cell, and more specifically, gas composition data from the output product streams of the cathode 296 and the anode 298, as well as gas composition data from the fluid 362 (e.g., gas) surrounding the fuel cell, and more specifically, gas composition data from the fluid 362 surrounding the fuel cell within the housing 360. As used herein, the fluid 362 is considered a fluid flow.

[0138] Specifically, the gas sensor 350E includes a node 364 exposed to the output product stream from the cathode 296, a node 366 exposed to the output product stream from the anode 298, and a node 368 exposed to the fluid 362 surrounding the fuel cell. Gas composition data sensed by the output product gas sensor 350E can be used to determine the health information of the fuel cell assembly 204, and further used to diagnose faults or anomalies within the fuel cell assembly 204, such as leaks within the fuel cell assembly 204.

[0139] For example, as will be explained in more detail below, when the gas flow supplied to cathode 296 may not contain any carbon dioxide or H2O and these are components present in anode 298 during operation, the presence of carbon dioxide, H2O, or both, in the output products from cathode 296 can indicate cross-leakage 370 from anode 298 to cathode 296. Figure 7 (Depicted in dashed lines). Similarly, in the absence of an increase in the flow rate of the gas flow supplied to the cathode 296, an increase in the flow rate of the output product from the cathode 296 can indicate cross-leakage 370 from the anode 298 to the cathode 296.

[0140] For example, when the percentage of carbon dioxide in the output product from cathode 296 is greater than 0, such as greater than 0 and up to about 1%, this can indicate cross-leakage 370 from anode 298 to cathode 296. Similarly, when the percentage of H2O in the output product from cathode 296 is greater than 0, such as greater than 0 and up to about 5%, such as up to about 3%, this can also indicate cross-leakage 370 from anode 298 to cathode 296. Alternative methods for diagnosing cross-leakage 370 from anode 298 to cathode 296 can be based on trends in these detected gas components rather than their absolute values. For example, if any of the percentages of CO2, H2O, or flow rate in the output product from cathode 296 increases, the controller (e.g., Figure 6 The controller 240 can determine cross-leakage 370 from anode 298 to cathode 296 and, for example, provide an alarm indicating the cross-leakage 370.

[0141] Similarly, for example, when the fuel stream supplied to anode 298 may not contain any nitrogen, the presence of nitrogen in the output products from anode 298 can indicate cross-leakage 372 from cathode 296 to anode 298. Figure 7 (Depicted in dashed lines; the terms “cross-leakage” and “cross-permeation” are synonymous). Similarly, in the absence of a corresponding increase in the fuel flow to anode 298, an increase in the flow rate of the output product from anode 298 can also indicate cross-permeation 372 from cathode 296 to anode 298.

[0142] For example, when the percentage of nitrogen in the output product from anode 298 is greater than 0, such as greater than 0 and as high as about 1%, this can indicate a cross-leakage 372 from cathode 296 to anode 298. An alternative method for diagnosing cross-leakage 372 could be based on trends in these detected gas components rather than their absolute values. If the nitrogen concentration or the exhaust flow rate of anode 298 increases, the controller can determine a cross-leakage 372 from cathode 296 to anode 298 and, for example, provide an alarm indicating this cross-leakage 372.

[0143] Furthermore, for example, the gas composition data sensed by the gas sensor 350E may further include the percentage of oxygen (O2) in the fluid 362 surrounding the fuel cell. Sensing data relating to the percentage of oxygen in the fluid 362 surrounding the fuel cell may also be provided to the controller, and the controller may be configured to further determine fuel cell leak diagnostic information in response to such sensing data. For example, if the percentage of oxygen in the fluid 362 surrounding the fuel cell is decreasing, and further, if the percentage of oxygen in the fluid 362 surrounding the fuel cell is greater than the percentage of oxygen in the output product from the cathode 296, this may indicate an external leak 374 from the cathode 296. Further, for example, if the percentage of oxygen in the fluid 362 surrounding the fuel cell is decreasing, and further, if the percentage of oxygen in the fluid 362 surrounding the fuel cell is less than the percentage of oxygen in the output product from the cathode 296, this may indicate an external leak 376 from the anode 298.

[0144] However, it will be understood that, despite for Figure 7 In one embodiment, the output product gas sensor 350E is positioned inside the housing portion 360; however, in other exemplary embodiments, the output product gas sensor 350E may alternatively be positioned outside the housing portion 360. Figure 8This configuration is depicted in an exemplary embodiment. The same or similar figures may refer to the same or similar portions. It will be understood that, with this configuration, separate gas sensors 350F can be provided within the housing 360 for detecting the percentage of oxygen within the fluid 362 surrounding the fuel cell.

[0145] Reference Figure 6 It will be understood that, utilizing one or more of the above-described configurations, the included one or more gas sensors 350 can be exposed to relatively harsh environments during the operating conditions of the propulsion system. For example, as will be understood from the above description, the propulsion system is generally configured as an aerospace propulsion system. In order for the gas sensor 350 described herein to operate in a desired manner, the gas sensor 350 needs to be configured to sense (and be able to sense) data on the composition of gas flowing into or to the turbine 104, fuel cell assembly 204, or both, during flight operations of the propulsion system (e.g., takeoff, climb, cruise, descent, landing). Furthermore, it will be understood that the gas sensor 350 described herein will be positioned within the housing (or “under the shroud”) of the turbine 104; see, for example... Figure 1 The integrated fuel cell and burner assembly 206 is located within the casing 106 of the turbine 104. During flight operation of the propulsion system, the environment under the hood can be relatively harsh.

[0146] Therefore, it will be understood that during normal operating conditions of the propulsion system (e.g., takeoff, climb, cruise, descent, landing), the gas sensor 350 may be positioned within the environment of the turbine 104, fuel cell assembly 204, or both, having a temperature of at least 200°C. For example, in some exemplary embodiments, during normal operating conditions of the propulsion system, the gas sensor 350 may be positioned within the environment of the turbine 104, fuel cell assembly 204, or both, having a temperature of at least 400°C and up to 1000°C. This operating temperature range may include... Figures 6 to 8 One or more locations are depicted herein. For example, various locations within the fuel cell assembly 204 (e.g., between the fuel processing unit 304 and the fuel cell stack 294, between the fuel cell stack 294 and the burner 206, within or around the housing 360, etc.) may be at temperatures between 450°C and 1000°C, such as temperatures between 600°C and 900°C, during normal operating conditions. Similarly, various locations along the burner fuel delivery line 150C may be at temperatures of at least 200°C and up to 650°C, such as temperatures between 300°C and 500°C, and at pressures between 100 bar and 300 bar, during normal operating conditions. The gas sensor 350 described herein is configured to withstand these environments.

[0147] Furthermore, it will be understood that one or more exemplary gas sensors 350 described herein can be configured to sense gas composition data including one or more of the following: H2%, CO%, CO2%, CH4%, H2O%, N2%, NH3%, percentage of non-volatile particulate matter, and percentage of volatile particulate matter. In particular, for at least some of the exemplary gas sensors 350 described herein, the gas sensor 350 can be configured as a multi-gas sensor, which is configured to sense gas composition data including two or more of the following: H2%, CO%, CO2%, CH4%, H2O%, N2%, NH3%, percentage of non-volatile particulate matter, and percentage of volatile particulate matter.

[0148] Furthermore, it will be understood that at least the gas sensor 350 can be configured to withstand the aforementioned environment and sense desired gas composition data during normal operating conditions of the propulsion system, while being relatively small and lightweight. In particular, one or more exemplary gas sensors 350, and especially, the sensing elements disclosed herein (see, for example...) Figure 6 The sensing element 354 in the gas sensor 350 may have a length less than about 20 mm (“mm”) multiplied by a width less than about 20 mm multiplied by a thickness less than about 20 mm (i.e., less than about 20 mm × 20 mm × 20 mm). For example, in some exemplary aspects, the sensing element of the gas sensor 350 may have a size less than about 10 mm × 10 mm × 10 mm, such as less than about 5 mm × 5 mm × 5 mm, for example, less than about 4 mm × 4 mm × 2 mm. Further, the sensing element of the gas sensor 350 may have a weight of less than 50 grams. For example, in some exemplary aspects, the sensing element of the gas sensor 350 may have a weight of less than 25 grams, such as less than 10 grams, such as less than 5 grams, such as less than 1 gram, such as less than 0.1 grams. Reference is made below. Figures 23 to 32 Further details are provided regarding an exemplary gas sensor 350 technology capable of operating within the disclosed environment, sensing disclosed gas composition data, and having the disclosed size and / or weight.

[0149] Further, it will be understood that the gas sensor 350, including one or more of these exemplary aspects, can allow the gas sensor 350 to be positioned in or near a fluid flow from which it senses gas composition data. Specifically, the gas sensor 350, including one or more of these exemplary aspects, can allow the gas sensor 350 to be separated from a fluid line having a fluid flow into or towards the turbine 104, fuel cell assembly 204, or both, by no more than about 100 mm. For example, in some exemplary embodiments, the gas sensor 350 can be separated from the fluid line by no more than about 50 mm, such as no more than about 20 mm. More specifically, in at least some exemplary aspects, the gas sensor 350, including one or more of these exemplary aspects, can allow the gas sensor 350 to be positioned aligned with a fluid line (such as fluid delivery line 150C) providing a fluid flow into or towards the turbine 104, fuel cell assembly 204, or both (see, for example...). Figure 6 The gas sensor 350C is designed to be inseparable from the fluid line.

[0150] Now for reference Figure 9 Flowchart 600 is provided. Flowchart 600 graphically depicts the interrelationships of various aspects of the fuel cell assembly integrated into the gas turbine engine. About Figure 9 The aspects described in flowchart 600 are generally applicable to this document, for example, see reference 600. Figures 1 to 8 One or more of the exemplary gas turbine engine 100 and fuel cell assembly 204 described herein.

[0151] More specifically, flowchart 600 relates to the interrelationship of a fuel cell assembly having a fuel processing unit 602 and a fuel cell stack 604. The fuel processing unit 602 may include a fuel reformer or a catalytic partial oxidation converter (CPOx) for producing a hydrogen-rich fuel stream for the fuel cell stack 604. Further, the gas turbine engine may include a combustor 606 and a shaft-driven compressor 608. The shaft-driven compressor 608 may be, for example, a high-pressure compressor. As will be understood, the shaft-driven compressor 608 may be turbine-driven, which extracts power from the combustion gases generated by the combustor 606 during operation.

[0152] As will be understood, the fuel cell assembly defines multiple fuel processing units that can affect the operation of the fuel processing unit 602. Figure 9The fuel processing unit (FPU) input parameter 610. In some exemplary aspects, the fuel processing unit input parameter 610 may include the inlet temperature of the fuel supplied to the fuel processing unit 602, the inlet pressure of the fuel supplied to the fuel processing unit 602, the flow rate of the fuel supplied to the fuel processing unit 602, the percentage of various components (e.g., sulfur) in the fuel supplied to the fuel processing unit 602, the oxygen-to-carbon ratio (e.g., determined based on the percentage of oxygen in the fuel), the steam-to-carbon ratio (e.g., determined based on the percentage of H2O in the fuel), etc.

[0153] Furthermore, the flow from the fuel processing unit 602 to the fuel cell stack 604 defines multiple fuel cell stacks (in) that can affect the operation of the fuel cell stack 604. Figure 9 The input parameters 612 (abbreviated as "FCS") generally include the gas composition of the flow supplied from the fuel processing unit 602 to the fuel cell stack 604; the temperature, pressure, and / or flow rate of the flow supplied from the fuel processing unit 602 to the fuel cell stack 604; and so on.

[0154] Furthermore, the output product stream supplied from fuel cell stack 604 to burner 606 further defines a plurality of output product parameters 614 that can affect the operation of burner 606. Output product parameters 614 may include the gas composition of the stream supplied from fuel cell stack 604 to burner 606 (e.g., percentage H2, indicating the enthalpy of the output product); the temperature, pressure and / or flow rate of the stream supplied from fuel cell stack 604 to burner 606; and so on.

[0155] Furthermore, the combustor 606 and the combustion gases from the combustor 606 define multiple engine parameters 616, which can affect the amount of power supplied to the shaft-driven compressor 608. The engine parameters 616 generally include the temperature within the combustor 606, the turbine inlet temperature, the high-pressure shaft speed, the low-pressure shaft speed, etc.

[0156] Finally, the shaft-driven compressor 608 and the airflow through it define a plurality of compressor parameters 618, which can affect one or more flows supplied to the fuel processing unit 602 and optionally to the fuel cell stack 604. The compressor parameters 618 can generally include the pressure of the airflow through the shaft-driven compressor 608, the temperature of the airflow through the shaft-driven compressor 608, the flow rate of the airflow through the shaft-driven compressor 608, etc.

[0157] In this way, it will be understood that while various parameters 610, 612, 614, 616, and 618 may be specific to one aspect of the fuel cell assembly and gas turbine engine, these parameters may affect other components of the fuel cell assembly and gas turbine engine. Therefore, by sensing gas composition data of the fluid flow into or to the turbine, fuel cell assembly, or both, one or more of these parameters 610, 612, 614, 616, and 618 can be sensed, thereby allowing for a higher level of health monitoring, fuel cell assembly / gas turbine engine control, anomaly detection, and / or fault detection and diagnosis.

[0158] In particular, it will be understood that the various parameters in these parameters 610, 612, 614, 616, and 618 can further indicate certain failure modes within the fuel cell assembly, the gas turbine engine, or both. For example, the various parameters in these parameters 610, 612, 614, 616, and 618 can indicate certain failure modes of a particular component, or certain failure modes of a downstream or upstream component.

[0159] For example, fuel processing unit 602 may be susceptible to failure modes, including carbon deposition, catalyst poisoning, and catalyst oxidation. Carbon deposition can generally be driven by the temperature of the fuel supplied to fuel processing unit 602 and the oxygen-to-carbon ratio of the fuel supplied to fuel processing unit 602. Carbon deposition may result in one or more of the following: catalyst deactivation within the fuel processing unit, blockage within the fuel processing unit, higher pressure losses across the fuel processing unit, and lower hydrogen production from the fuel processing unit (e.g., a reduction in the percentage of hydrogen in the stream supplied from fuel processing unit 602 to fuel cell stack 604). Catalyst poisoning can generally be driven by the percentage of sulfur in the fuel supplied to fuel processing unit 602 and can have similar effects to carbon deposition. Furthermore, catalyst oxidation can be driven by providing excessive air in the stream supplied to fuel processing unit 602 and can further lead to effects similar to carbon deposition.

[0160] Furthermore, the fuel cell stack 604 may be susceptible to failure modes, including cross-leakage between the anode and cathode of the fuel cell in the fuel cell stack 604, external leakage from the anode or cathode of the fuel cell in the fuel cell stack 604, anodic oxidation, and carbon deposition. Cross-leakage between the anode and cathode can generally be caused by cracks located in the electrode layers between them. (Refer to above) Figure 7 and Figure 8The consequences of cross-leakage or external leakage are described. When anodizing occurs, this can lead to lower output voltage from fuel cell stack 604 and cracking of the anode. Carbon deposition in fuel cell stack 604 can be caused by a low vapor-to-carbon ratio in the stream supplied to fuel cell stack 604 and can lead to one or more of the following: catalyst deactivation, blockage within the catalyst (potentially causing hot spots), increased pressure loss across the catalyst, and reduced power output from fuel cell stack 604.

[0161] As should be understood, carbon deposition within fuel cell stack 604 may occur relatively quickly (e.g., within 30 minutes or less) and may further lead to carbon deposition within combustor 606, which may potentially flow into the turbine section of the gas turbine engine, potentially damaging the turbine rotor blades (e.g., causing the thermal barrier coating of one or more turbine rotor blades to peel off). As discussed below, including one or more gas sensors operating at a relatively fast temporal resolution to sense gas composition data including fuel cell stack input parameter 612, output product parameter 614, or both, can provide early notification of potential carbon deposition within fuel cell stack 604 (hereinafter referred to as “early anomaly”), allowing modifications to the operation of the gas turbine engine, fuel cell assembly, or both to minimize any damage.

[0162] Furthermore, combustor 606 may be susceptible to failure modes, including flameout, combustor kinetics, and carbon deposition / damage. Flameout within combustor 606 can generally be a result of the fuel-air ratio supplied to combustor 606, the temperature of the fuel supplied to combustor 606, the pressure of the fuel supplied to combustor, or a combination thereof. Output product parameter 614, engine parameter 616, or both can provide data indicating one or more of these combustor failure modes.

[0163] Now for reference Figure 10 A flowchart of a method 700 for operating a propulsion system according to an exemplary aspect of this disclosure is provided. In particular, method 700 relates to a method for determining a health indicator of a gas turbine engine, a fuel cell assembly, or both, and further to a method for providing a maintenance response, a reporting response, a control response, or a combination thereof in response to the determined health indicator. Method 700 can be used with one or more of the exemplary propulsion systems described above, such as with one or more exemplary fuel cell assemblies and gas turbine engines described herein.

[0164] Method 700 generally includes, at (702), operating a propulsion system to generate thrust for a launch vehicle. The launch vehicle may be an aerospace vehicle, such as an aircraft. The propulsion system generally includes a gas turbine engine and a fuel cell assembly. The fuel cell assembly may, for example, be in one or more of the manner described herein (see example...) Figure 2 The propulsion system is integrated into the gas turbine engine. In at least some exemplary aspects, operating the propulsion system at (702) to generate thrust for the vehicle may include operating the propulsion system under flight conditions such as takeoff flight conditions, climb flight conditions, cruise flight conditions, descent flight conditions, etc.

[0165] Method 700 further includes (704) collecting data. Specifically, collecting data at (704) includes (706) receiving gas composition data from multiple gas sensors on one or more fluid flows flowing into or to a gas turbine engine, fuel cell assembly, or both, while operating the propulsion system at (702). The gas composition data received at (706) may include the data referenced above. Figure 9 The flowchart 600 describes one or more of the parameters 610, 612, 614, 616, and 618. Additionally or alternatively, the gas composition data can be any other suitable gas composition data.

[0166] It is worth noting that, for the exemplary aspect described, data collection at (704) further includes receiving data indicating operating parameters of the propulsion system at (708). The operating parameters of the propulsion system may include one or more of the following: flight conditions, environmental conditions (e.g., ambient temperature, pressure, flight speed, etc.), temperature data (e.g., temperature of the fuel cell assembly, compressor outlet temperature, turbine inlet temperature, etc.), and pressure data (e.g., compressor pressure, fuel cell stack pressure drop).

[0167] Method 700 further includes, at (710), determining baseline data for the gas turbine engine, fuel cell assembly, or both, in response to data collected at (704), and more specifically, in response to operating parameters received at (708). The baseline data for the gas turbine engine, fuel cell assembly, or both determined at (710) may include baseline information for the gas turbine engine, fuel cell assembly, or both for a given flight condition and / or for a given operating condition of the gas turbine engine, fuel cell assembly, or both.

[0168] Still referencing Figure 10Method 700 further includes, at (712), determining a health indicator for a gas turbine engine, a fuel cell assembly, or both, in response to gas composition data received at (706). More specifically, for the exemplary aspects depicted, determining the health indicator at (712) includes at least one of detecting an anomaly at (714), determining a system health parameter at (728), or detecting a component failure at (730).

[0169] As used herein, the term "abnormal" refers to a condition in which an affected component is considered to be operating outside its nominal degradation state, but is still operable to provide beneficial results to the propulsion system. The term "system health parameter" refers to degradation information (e.g., accumulated degradation information, percentage of degradation since new onset, etc.). A component's system health parameter can indicate that the component is operating at less than nominal degradation, that the component has experienced abnormal conditions, or that the component has experienced a failure. The term "failure" refers to a condition in which a component is no longer able to provide beneficial results to the propulsion system.

[0170] Detecting an anomaly at (714) more specifically includes detecting an anomaly at (716) using a fuel cell / engine anomaly detection module, and detecting an anomaly at (716) using the fuel cell / engine anomaly detection module includes using one or more anomaly detection rules at (718). For example, in the exemplary aspect depicted, detecting an anomaly at (714) may include comparing gas composition data received at (706) with baseline data determined using operating parameters received at (708). For example, detecting an anomaly at (714) may include detecting an abnormal level of gas composition in the fluid flow compared to an expected level of gas composition in a specific fluid flow for operating conditions of the propulsion system. An abnormal level may refer to a level that is higher or lower than a predetermined threshold for gas composition in the fluid flow for a given operating condition.

[0171] Still referencing Figure 10 The exemplary method 700, for the illustrated exemplary aspect, further includes determining the health indicator at (712) and determining the anomaly type, the affected portion, or both at (720) for the illustrated exemplary aspect. More specifically, for the illustrated exemplary aspect, determining the anomaly type, the affected portion, or both at (720) includes operating the fuel cell / engine anomaly diagnostic module at (722). Operating the fuel cell / engine anomaly diagnostic module at (722) may include determining the affected portion using fuel cell / engine anomaly location rules at (724) and determining the anomaly type using fuel cell / engine anomaly root cause analysis rules at (726).

[0172] In some exemplary aspects, examples of exception types and exception locations may be found in the references above. Figure 9 One or more exemplary failure modes are identified. See below for reference. Figures 11 to 14 The exemplary method is described in more detail, including further details about determining the anomaly type, the affected portion, or both at (720).

[0173] Still referencing Figure 10 The exemplary method 700, as briefly mentioned above, may further include determining a system health parameter at (728) the health indicator at (712). The system health parameter may indicate the degree of degradation of one or more components of a gas turbine engine, fuel cell assembly, or both. For example, method 700 may determine the system health indicator at (728) based on a comparison of gas composition data received at (706) with baseline gas composition data (e.g., determined using operating parameters received at (708)).

[0174] It is noteworthy that the system health parameters determined at (728) can provide data related to the degradation of the system component before the point at which method 700 will detect an anomaly during the component's operation. For example, the system health parameters determined at (728) can provide data related to the degree of degradation of the component while the component is operating within its normal operating range. More specifically, the system health parameters determined at (728) can provide data on initial anomalies.

[0175] In addition, as briefly mentioned above, please refer to Figure 10 The exemplary method 700, which determines a health indicator at (712), may further include detecting a component failure at (730). A component failure may indicate that a component is no longer able to operate in a manner beneficial to a gas turbine engine, a fuel cell assembly, or both. Method 700 can detect a component failure at (730) by comparing gas composition data received at (706) with baseline gas composition data (e.g., determined using operating parameters received at (708)) and determining that the gas composition data is outside a predetermined failure threshold of the baseline gas composition data. Thus, the failure threshold can be used for specific operating parameters of the gas turbine engine.

[0176] Although not depicted, method 700 may, in response to detecting a component failure at (730), perform one or more diagnostic steps to determine the affected component, the root cause of the component failure, or both.

[0177] Still referencing Figure 10The exemplary method 700 will be understood to further include, in response to a health indicator determined at (712), performing a maintenance response, a reporting response, a control response, or a combination thereof.

[0178] Specifically, method 700 includes, at (732), operating a maintenance module to provide a maintenance response in response to a health indicator determined at (712); at (734), operating a reporting module to provide a reporting response in response to a health indicator determined at (712); at (736), operating a control module to provide a control response in response to a health indicator determined at (712); or a combination thereof.

[0179] First, refer to the operation of the maintenance module at (732). The operation of the maintenance module at (732) may include receiving flight plan data of the current flight of the carrier, including the propulsion system, at (738), and receiving maintenance plan data of one or more components of the fuel cell assembly, gas turbine engine, or both at (740).

[0180] Furthermore, the operation of the maintenance module at (732) includes providing maintenance guidance at (742) in response to a health indicator determined at (712). For example, in some exemplary aspects, providing maintenance guidance at (742) may include providing maintenance guidance in response to an anomaly detected at (714), in response to determining system health parameters at (728), or both. In this way, providing maintenance guidance at (742) may include providing maintenance guidance to the component while the component is still capable of providing beneficial operation for the gas turbine engine, fuel cell assembly, or both.

[0181] The maintenance instructions provided at (742) may include providing an indicator to the operator or controller to perform maintenance actions on components of the fuel cell assembly, gas turbine engine, or both, for example, at the next scheduled maintenance operation. Additionally or alternatively, the maintenance instructions provided at (742) may include flight plan modifications, maintenance schedule modifications, or service guidelines (e.g., guidance on which components require maintenance, what type of maintenance is required, etc.). For example, in some exemplary aspects, in response to a health indicator determined at (712), the maintenance instructions may, for example, indicate the need to change the flight plan based on the type of detected anomaly or malfunction, the component affected by the detected anomaly or malfunction, or both.

[0182] Furthermore, the operation of the reporting module at (734) generally includes providing report content at (744) in response to a health indicator determined at (712). In some exemplary aspects, the report content provided at (744) may be a diagnostic tree indicating the root cause of an anomaly detected at (714). Furthermore, in other example aspects, the report content provided at (744) may include expected partial degradation information, inventory planning, replacement duration, inventory requirements, etc. Providing report content at (744) may include providing report content to the controller of the propulsion system, the vehicle, or both, and may include providing report content to a visual indicator visible to the operator of the propulsion system, etc.

[0183] Furthermore, the operation of the control module at (736) may generally include, at (746), modifying engine operating parameters in response to a health indicator determined at (712); at (748), modifying fuel cell assembly operating parameters in response to a health indicator determined at (712); or both.

[0184] In some exemplary aspects, the operating parameters of the gas turbine engine modified at (746) may include: burner fuel flow rate, burner fuel-air ratio, fuel flow rate ratio between burner fuel flow and fuel cell fuel flow, variable discharge valve, variable guide vane, low-pressure shaft speed, high-pressure shaft speed, variable fan nozzle, engine-driven generator output, or combinations thereof. Further, in some exemplary aspects, the operating parameters modified at (748) may include: fuel flow rate to the fuel cell assembly, fuel pressure, equivalence ratio of the fuel processing unit of the fuel cell assembly, vapor-to-carbon ratio of the fuel processing unit of the fuel cell assembly, air pressure, air flow rate, pressure difference from anode to cathode, anode inlet temperature, cathode inlet temperature, fuel cell stack temperature, fuel cell current, fuel cell utilization rate, fuel cell air utilization rate, or combinations thereof.

[0185] Now, for general reference Figures 11 to 13 The present disclosure provides a flowchart of an example aspect of a method 800 for determining a health indicator of a gas turbine engine, a fuel cell assembly, or both, and further providing a maintenance response, a reporting response, or both in response to the health indicator.

[0186] Now for reference Figure 11 A flowchart of a method 800 for determining diagnostic information of a fuel cell leak, according to an exemplary aspect of this disclosure, is provided. Method 800 can be referenced above. Figures 1 to 8One or more of the exemplary fuel cells and fuel cell assemblies described herein may be used together. Thus, method 800 may be used with a fuel cell assembly having a control system with a gas sensor configured to sense gas composition data of the output product stream from the cathode of the fuel cell (fuel cell stack), gas composition data of the output product stream from the anode of the fuel cell, gas composition data of the fluid surrounding the fuel cell, or a combination thereof.

[0187] Method 800 generally requires receiving gas composition data from the output product stream of the cathode, gas composition data from the output product stream of the anode, gas composition data of the fluid surrounding the fuel cell, or a combination thereof, from a gas sensor; and determining fuel cell leak diagnostic information in response to the received gas composition data.

[0188] More specifically, for an exemplary aspect of the described method 800, method 800 includes, at (802), detecting a trigger. Detecting the trigger at (802) may include detecting anomalies in the fuel cell assembly, such as detecting uncommanded changes in voltage from the fuel cell and / or fuel cell stack, resistance from the fuel cell and / or fuel cell stack, temperature of the fuel cell and / or fuel cell stack, pressure of one or more flows entering or exiting the fuel cell and / or fuel cell stack, or within the fuel cell and / or fuel cell stack.

[0189] Method 800 further includes collecting gas composition data at (804). Specifically, for the aspects described, collecting gas composition data at (804) may be in response to a trigger detected at (802). Collecting gas composition data at (804) may include collecting gas composition data using one or more sensors, such as gas sensors (e.g., multi-gas sensors), dedicated oxygen sensors, etc.

[0190] Method 800 additionally includes initiating external leakage diagnosis at (808) and cross-leakage diagnosis at (810). Reference will be made below. Figure 12 The aspects of external leak diagnosis starting at (808) are described in more detail below, and will be referenced below. Figure 13 The aspects of cross-leakage diagnosis starting at (810) are described in more detail.

[0191] It is noteworthy that, as depicted by the dashed line, method 800 may include, at (806), determining from the collected gas composition data whether the percentage of oxygen within the casing that at least partially surrounds the fuel cell and fuel cell stack is increasing. If, as determined at (806), the percentage of oxygen within the casing is increasing, method 800 may proceed to initiating external leak diagnosis at (808); otherwise, method 800 may rule out external leaks and proceed to cross-leak diagnosis at (810). It is noteworthy that even if, as determined at (806), the percentage of oxygen within the casing is increasing, the method may still proceed to cross-leak diagnosis at (810).

[0192] refer to Figure 12 In response to initiating external leakage diagnosis at (808), method 800 further includes, at (812), determining from the collected gas composition data whether the percentage of oxygen within the housing is greater than the percentage of oxygen in the output product stream from the cathode. If, as determined at (812), the percentage of oxygen within the housing is less than the percentage of oxygen in the output product stream from the cathode, then method 800 determines at (814) that the fuel cell is experiencing an anode external leakage. Conversely, if, as determined at (812), the percentage of oxygen within the housing is greater than the percentage of oxygen in the output product stream from the cathode, then method 800 determines at (816) that the fuel cell is experiencing a cathode external leakage.

[0193] Now for reference Figure 13 In response to initiating cross-leakage diagnosis at (810), the method includes, at (818), determining whether the percentage of nitrogen in the output product stream from the anode of the fuel cell is increasing or exceeds a threshold. If, as determined at (818), the percentage of nitrogen in the output product stream from the anode is increasing or exceeds a threshold, then method 800 further includes, at (820), determining whether the percentage of carbon dioxide in the output product stream from the cathode is increasing or exceeds a threshold, whether the percentage of H2O in the output product stream from the cathode is increasing or exceeds a threshold, or both. If, at (820), it is determined that one or both of the percentages of carbon dioxide or H2O in the output product stream from the cathode are increasing or exceeding a threshold, then method 800 includes, at (822), determining that the fuel cell is experiencing anode-to-cathode cross-leakage and cathode-to-anode cross-leakage.

[0194] Specifically, when nitrogen will not be part of the fuel supplied to the anode of the fuel cell during operation of the fuel cell assembly, an increase in the percentage of nitrogen in the output product stream from the anode, or the presence of nitrogen in the output product stream from the anode exceeding a certain threshold, can indicate cathode-to-anode cross-leakage. Similarly, when neither carbon dioxide nor H2O will be part of the gas stream supplied to the cathode of the fuel cell during operation of the fuel cell assembly, an increase in the percentage of carbon dioxide or H2O in the output product stream from the cathode, or the presence of carbon dioxide or H2O in the output product stream from the cathode exceeding a certain threshold, can indicate anode-to-cathode cross-leakage.

[0195] Still referencing Figure 13 An exemplary aspect of the method 800 described herein will be understood to be that, as determined at (820), if neither the percentage of carbon dioxide nor the percentage of H2O in the output product stream from the cathode increases or exceeds the corresponding threshold, then the method 800 may determine at (824) that the fuel cell is merely experiencing a cathode-to-anode cross-leakage (due to the percentage of nitrogen in the output product stream from the anode, as determined at (818)).

[0196] Furthermore, if at (818) it is determined that the percentage of nitrogen in the output product stream from the anode has not increased or has not exceeded a threshold, method 800 can still check for cathode-to-anode leakage at (826) by determining whether the flow rate of the output product from the anode is increasing. If, as determined at (826), the flow rate of the output product from the anode is increasing, then method 800 can again determine at (824) that the fuel cell is experiencing cathode-to-anode cross-leakage.

[0197] Following the determination at (826), regardless of whether the determination is "yes" or "no", the method includes at (828) determining whether the flow rate of the output product from the cathode is increasing. If it is determined at (828) that the flow rate of the output product from the cathode is increasing, the method includes at (830) determining that the fuel cell is experiencing anode-to-cathode cross-leakage.

[0198] If it is determined at (828) that the flow rate of the output products from the cathode is not increasing, method 800 includes at (832) determining whether the percentage of H2O, carbon dioxide, or both in the output product stream from the cathode is increasing (similar to the determination at (820)). If, as determined at (832), the percentage of H2O, carbon dioxide, or both is increasing, then the method again includes at (830) determining that the fuel cell is experiencing anode-to-cathode cross-leakage.

[0199] However, if it is determined at (832) that the percentage of H2O, carbon dioxide, or both in the output product stream from the cathode has not increased, then the method determines at (834) that the fuel cell has not experienced cross-leakage.

[0200] What will be understood is that the above reference Figures 11 to 13 The exemplary method 800 described is provided by way of example only. In other exemplary aspects of this disclosure, method 800 may not include each step outlined above, and may further include the inquiries outlined above in any other suitable order. For example, in other exemplary aspects where method 800 is capable of operating with fuel cell assemblies that cannot sense gas composition data from the output product stream from the cathode, method 800 may not include one or more of (820), (828), (832), etc. Similarly, in other exemplary aspects where method 800 is capable of operating with fuel cell assemblies that cannot sense gas composition data from the output product stream from the anode, method 800 may not include one or more of (818), (826). Further, in other exemplary aspects where method 800 is capable of operating with fuel cell assemblies that cannot sense gas composition data from the fluid surrounding the fuel cell, the method may not include (808) or Figure 13 Other aspects of the method described in 800.

[0201] Similarly, as described above, in other exemplary aspects, method 800 may include the queries outlined above in any other suitable order. For example, in other exemplary aspects, one or more of (818), (820) and (832), (826), and (828) may be performed in parallel.

[0202] Furthermore, as will be further understood from the description below, method 800 can occur in real time. For example, in some exemplary aspects, receiving gas composition data (or collecting gas composition data at (804)) may include receiving data at a resolution of 1 minute or less. For example, in some exemplary aspects, receiving gas composition data (or collecting gas composition data at (804)) may more specifically include receiving data at a resolution of 30 seconds or less (such as 15 seconds or less, or 5 seconds or less).

[0203] In this way, the method can make control decisions based on data collected one minute or more in advance.

[0204] Now for reference Figure 14 A flowchart is provided for another example aspect of this disclosure, illustrating a method 900 for determining a health indicator of a gas turbine engine, a fuel cell assembly, or both, and further for providing a maintenance response, a reporting response, or both in response to the health indicator. Specifically, for Figure 14 An exemplary aspect of method 900 is that the health indicator relates to carbon deposition within the fuel processing unit of a fuel cell assembly, carbon deposition within the anode of a fuel cell in a fuel cell stack of a fuel cell assembly, or both.

[0205] Method 900 includes, at (902), determining baseline conditions for the fuel cell assembly. Determining baseline conditions may include determining baseline conditions in response to one or more operating conditions or operating parameters of the fuel cell assembly, the gas turbine engine, or both.

[0206] Method 900 further includes, at (904), receiving gas composition data from one or more gas sensors located at various locations within the fuel cell assembly. Specifically, the gas composition data includes gas composition data from a first gas sensor located downstream of the fuel processing unit and upstream of the fuel cell stack, and gas composition data from a second gas sensor located downstream of the fuel cell stack and upstream of the combustor of the gas turbine engine.

[0207] At (906), method 900 determines the fuel source located in the fuel processing unit (in Figure 14 Method 900 determines at (908) whether gas composition data from a first gas sensor located downstream of the fuel cell stack and upstream of the fuel cell stack indicates carbon deposition within the fuel processing unit. If, as determined at (906), the gas composition data indicates carbon deposition within the fuel processing unit, then method 900 further determines at (910) whether gas composition data from a second gas sensor located downstream of the fuel cell stack and upstream of the burner indicates carbon deposition within the anode of the fuel cell in the fuel cell stack. If, as determined at (908), the gas composition data indicates carbon deposition within the anode of the fuel cell in the fuel cell stack, then method 900 further determines at (912) that both the fuel processing unit and the fuel cell include carbon deposition. Conversely, if, as determined at (908), the gas composition data indicates no carbon deposition within the anode of the fuel cell stack, then method 900 determines at (912) that the fuel processing unit includes carbon deposition.

[0208] Returning to the inquiry at (906), if method 900 determines at (906) based on gas composition data from a first gas sensor located downstream of the fuel processing unit and upstream of the fuel cell stack, that there is no indication of carbon deposition within the fuel processing unit, the method continues to the inquiry at (914) to determine whether gas composition data from a second gas sensor located downstream of the fuel cell stack and upstream of the burner indicates carbon deposition within the anode of the fuel cell in the fuel cell stack. If, as determined at (914), the gas composition data indicates carbon deposition within the anode of the fuel cell in the fuel cell stack, method 900 further determines at (916) that the fuel cell includes carbon deposition. In contrast, if, as determined at (914), the gas composition data does not indicate carbon deposition within the anode of the fuel cell stack, method 900 determines at (918) that neither the fuel cell nor the fuel processing unit includes carbon deposition.

[0209] If it is determined at (910), (912) or (916) that the fuel cell, fuel processing unit or both contain carbon deposits, then method 900 may further include at (920) recommending a maintenance response associated with cleaning or inspecting the burner, turbine section or both to ensure that any carbon from the fuel processing unit, fuel cell or both has not traveled to the burner or turbine section and to potential damage to the turbine section (e.g., peeling of the thermal barrier coating on the turbine nozzles or turbine rotor blades).

[0210] Now for reference Figure 15A An example of a reporting module 734 according to an exemplary aspect of this disclosure is provided. In particular, the reporting module 734 can be configured in accordance with the above references. Figure 10 The report module 734 described is constructed in essentially the same way.

[0211] Figure 15A The report content is described in more detail, and report 750, which can be part of the report content, is also described in more detail. Report 750 provides, for example, in Figure 10 The system health parameter information for various components of the fuel cell assembly and gas turbine engine determined at (712) in method 700. Report 750 includes a first column 752 which provides the name of the component in the fuel cell assembly or gas turbine engine; a second column 754 which indicates the health status of the corresponding component (e.g., system health parameters of the component); and a third column 756 which indicates more specific details of the health status of the corresponding component (e.g., cumulative degradation information of system health parameters, such as percentage of life, where shorter bars indicate the early stage of life and longer bars indicate near the end of life).

[0212] As referenced above Figure 10As described, gas composition data from gas sensors, together with component life degradation models, can generate lifespan consumption data based on aging indicators such as carbon deposition thickness, catalyst deactivation status of fuel processing units and / or fuel cells. This information can be transmitted to a flight database, allowing fleet management teams to schedule appropriate inventory preparation and maintenance. Figure 15B It can be based on Figure 15A The information in the report led to the creation of inventory management and maintenance plan 758.

[0213] Now for reference Figure 16 A flowchart of a method 1000 for operating a propulsion system according to another exemplary aspect of this disclosure is provided. In particular, method 1000 relates to a method of operating a propulsion system having a gas turbine engine and a fuel cell assembly. Method 1000 can be used with one or more exemplary propulsion systems described herein, such as with one or more exemplary fuel cell assemblies and gas turbine engines described herein.

[0214] Method 1000 includes operating the propulsion system at (1002) during flight operations. Operating the propulsion system at (1002) during flight operations can include operating the propulsion system during normal flight operations, such as during takeoff operating conditions, climb operating conditions, cruise operating conditions, descent operating conditions, etc.

[0215] Furthermore, Figure 16 An exemplary method 1000 includes receiving, at (1004), gas composition data of the output products of a fuel cell from a fuel cell stack of a fuel cell assembly. Receiving the gas composition data at (1004) may include receiving the gas composition data from a gas sensor located downstream of the fuel cell and upstream of the combustor of a gas turbine engine. The gas sensor may be positioned aligned with the output product stream, or alternatively, may be separated from the output product stream by a gap of less than 100 mm (e.g., less than about 50 mm, such as less than about 20 mm, such as less than about 5 mm). In this way, the gas sensor may be configured to sense gas composition data directly from the output product stream, or may be configured to sample the output product stream.

[0216] Furthermore, for Figure 16 An exemplary aspect of the method 1000 described herein further includes receiving gas composition data of the output products from the fuel cell at (1004) and at (1006) receiving gas composition data of the output products from the fuel cell while operating the propulsion system during flight operations, at (1002).

[0217] As will be understood from the description herein, a gas sensor used to determine gas composition data may be able to sense the gas composition data with a relatively fast temporal resolution. In this way, it will be understood that... Figure 16 In an exemplary aspect, receiving gas composition data at (1004) may further include sensing gas composition data from the fuel cell output product at (1008) with a time resolution of 10 minutes or less, or at (1010) sensing gas composition data from the fuel cell output product with a time resolution of one minute or less. As used herein, the term "time resolution" in the context of sensing gas composition data refers to the time between the initial measurement and when the gas composition data becomes available to a controller, for example, configured to make control decisions in response to the gas composition data. In some example aspects, the time resolution at which the gas sensor senses gas composition data from the fuel cell output product may be less than about 30 seconds, such as less than about 15 seconds, such as less than about 5 seconds, such as less than about 2 seconds. In this way, the gas sensor can be configured to sense gas composition data in real time.

[0218] Still referencing Figure 16 An exemplary aspect of the method 1000 described herein further includes, at (1011), controlling the operation of a fuel cell assembly, a gas turbine engine, or both. More specifically, controlling the operation of the fuel cell assembly, the gas turbine engine, or both at (1011) includes, at (1012), controlling the operation of the fuel cell assembly, the gas turbine engine, or both in response to gas composition data from the output products of the fuel cell received at (1004).

[0219] More specifically, in Figure 16 In one exemplary aspect of the method 1000 described herein, controlling the operation of a fuel cell assembly, a gas turbine engine, or both at (1012) includes controlling the operation of the fuel cell assembly at (1014) in response to received gas composition data from the output products of the fuel cell. Controlling the operation of the fuel cell assembly at (1014) may include modifying operating parameters of the fuel cell assembly at (1016) in response to received gas composition data from the output products of the fuel cell. In some exemplary aspects, the operating parameters modified at (1016) may include: fuel flow rate to the fuel cell assembly, fuel pressure, equivalence ratio of the fuel processing unit of the fuel cell assembly, vapor-to-carbon ratio of the fuel processing unit of the fuel cell assembly, air pressure, air flow rate, pressure difference from anode to cathode, anode inlet temperature, cathode inlet temperature, fuel cell stack temperature, fuel cell current, fuel cell utilization rate, fuel cell air utilization rate, or combinations thereof.

[0220] Furthermore, in Figure 16 In another exemplary aspect of the method 1000 described herein, controlling the operation of the fuel cell assembly, the gas turbine engine, or both at (1012) includes controlling the operation of the gas turbine engine at (1018). Controlling the operation of the gas turbine engine may include modifying the operating parameters of the gas turbine engine at (1020) in response to received gas composition data from the output products of the fuel cell. In some exemplary aspects, the operating parameters of the gas turbine engine may include: burner fuel flow rate, burner fuel-air ratio, fuel flow rate ratio between burner fuel flow and fuel cell fuel flow, variable discharge valve, variable guide vane, low-pressure shaft speed, high-pressure shaft speed, variable fan nozzle, engine-driven generator output, or combinations thereof.

[0221] As will be understood, the gas composition data of the output products received at (1004) from the fuel cell may include data indicating the percentage of hydrogen in the output products. The percentage of hydrogen in the output products can allow for determination of the calorific value of the output products supplied to the combustor of the combustion section of the gas turbine engine. This information can affect the amount of energy supplied to the turbine section of the gas turbine engine, as well as other operating aspects of the gas turbine engine, such as combustor dynamics, emissions, etc.

[0222] In this way, it will be understood that method 1000 can directly control the gas turbine engine in response to the gas composition data received at (1004) to, for example, provide a desired amount of energy to the turbine section, modify combustor dynamics and / or emissions, etc. Additionally or alternatively, method 1000 can modify the operation of the fuel cell assembly in response to the gas composition data received at (1004) to, for example, change the amount of hydrogen supplied to the combustor, thereby changing the amount of energy supplied to the turbine section, modifying combustor dynamics and / or emissions, etc.

[0223] As an example, it will be understood that, in at least some exemplary aspects, controlling the operation of the fuel cell assembly, gas turbine engine, or both at (1011) includes, at (1022), using model-based control to control the operation of the fuel cell assembly, gas turbine engine, or both. Utilizing this exemplary aspect, it will be understood that controlling the operation of the fuel cell assembly, gas turbine engine, or both at (1011) more specifically includes, at (1024), controlling the operation of the fuel cell assembly, gas turbine engine, or both based on gas composition data of the fuel cell output products received at (1004), and using model-based control. Controlling the operation of the fuel cell assembly, gas turbine engine, or both at (1024) includes, at (1026), using a fusion filter to control the operation of the fuel cell assembly, gas turbine engine, or both, the fusion filter being configured to receive gas composition data of the fuel cell output products received at (1004) and being configured to receive data from one or more models of the model-based control.

[0224] It is worth noting that, utilizing this exemplary aspect, method 1000 further includes, at (1028), updating one or more models of model-based control in response to received gas composition data of the fuel cell output products. For example, the received gas composition data of the fuel cell output products can be used to calibrate one or more models of model-based control.

[0225] It will be understood that controlling the operation of a fuel cell assembly, a gas turbine engine, or both according to one or more of these exemplary aspects can update and / or calibrate one or more models of model-based control by utilizing gas composition data sensed at a relatively fast temporal resolution, and further allow for redundancy in the control scheme by utilizing data outputs from one or more models of model-based control to determine whether one or more gas sensors are being used because the gas composition data has failed. It is noteworthy that method 900 can determine that one or more gas sensors are being used because the gas composition data has failed in response to determining that the provided gas composition data is outside a predetermined range of the data outputs of one or more models of model-based control.

[0226] What will be understood is that, for Figure 16 An exemplary aspect of method 1000 is that method 100 uses gas composition data of the output products of a fuel cell / fuel cell stack as the basis for control of a gas turbine engine, fuel cell assembly, or both. This allows control based on the amount of energy supplied from the fuel cell assembly to the combustor, which provides many benefits as described herein.

[0227] However, in other exemplary embodiments, method 1000 may additionally or alternatively be based on control of the gas turbine engine, fuel cell assembly, or both based on gas composition data received from multiple gas sensors of one or more other flows into, towards, or through the gas turbine engine, fuel cell assembly, or both (e.g., at (1011), (1012), (1014), (1016), (1018), (1020), (1022), (1024), (1026), (1028)). In this way, method 1000 can... Figure 10 The method at (736) in 700 is executed by the control module.

[0228] Now for reference Figure 17 Flowcharts of exemplary model-based control systems and methods for fuel cell components and gas turbine engines, based on exemplary aspects of this disclosure, are provided. Figure 17 The exemplary model-based control systems and methods described herein can be used with one or more exemplary gas turbine engine and fuel cell components. Furthermore, Figure 17 The exemplary model-based control systems and methods described herein can be incorporated into one or more other methods (such as...) Figure 16 The model-based control method introduced in Method 1000.

[0229] refer to Figure 17 The exemplary model-based control system and method are more specifically described as a coordinated control system 1100 for a propulsion system. As shown, the coordinated control system 1100 includes a fuel cell system 1102 and a burner 1104. The burner 1104 can be configured in accordance with the above reference, for example... Figure 2 The combustor 206 discussed is constructed in a similar manner to that of the combustor 1104, such that the combustor 1104 may include a swirler assembly 216 configured to deliver an aviation fuel stream 1105 to the combustor 1104. The fuel cell system 1102 may be configured as described herein, for example, with reference to... Figures 2 to 5 Any of the fuel cell components 204 discussed are constructed in a similar manner. That is, the fuel cell system 1102 may be fluidly coupled to the burner 1104 and configured to deliver output product 1106 to the burner 1104. In addition to output product 1106, the fuel cell system 1102 may also generate power output 1118 (such as electrical output) that can be used, for example, in one or more motors in a propulsion system.

[0230] As shown in the figure, the coordination control system 1100 may include a controller 240, which may be the controller mentioned above. Figure 5The controller 240 discussed may be a different controller. Controller 240 may be configured to receive data from one or more sub-controllers or sensors of a coordinated control system 1100 that communicates with fuel cell system 1102 and / or burner 1104. Additionally, controller 240 may be configured to send data, control commands, or other operations on sub-controllers, fuel cell system 1102, and / or burner 1104.

[0231] In many embodiments, the coordinated control system 1100 may include a fuel cell controller 1108 operatively communicating with the controller 240. The fuel cell controller 1108 may be configured to communicate with... Figure 5 The controller 240 shown is constructed in a similar manner (e.g., having one or more processors and a memory), or alternatively, the fuel cell controller 1108 may be constructed as part of the controller 240. The fuel cell controller 1108 may be operable to modify one or more operating parameters of the fuel cell system 1102, such as the fuel flow rate or amount supplied to the fuel cell system 1102, the equivalence ratio (such as the air / fuel ratio supplied to the fuel cell system 1102), fuel utilization (e.g., the amount of fuel converted into electrical energy), the current generated by the fuel cell system 1102, and / or temperature (e.g., fuel and / or air inlet temperature). In particular, the fuel cell controller 1108 may be configured to modify the amount of output product 1106 introduced into the burner 1104 and the composition of the output product 1106 introduced into the burner 1104 (e.g., H2% within the output product 1106). In an exemplary embodiment of the fuel cell controller 1108, the fuel cell controller 1108 may include a power controller 1110 and a fuel utilization rate controller 1112. The power controller 1110 and the fuel utilization rate controller 1112 may be configured as part of the fuel cell controller 1108 or may be independent controllers.

[0232] In various embodiments, the coordinated control system 1100 may include a burner fuel flow rate controller 1114 operably in communication with the controller 240. The burner fuel flow rate controller 1114 may be configured to communicate with... Figure 5The controller 240 shown is constructed in a similar manner (e.g., having one or more processors and memory), or alternatively, the burner fuel flow rate controller 1114 may be constructed as part of the controller 240. The burner fuel flow rate controller 1114 may be operable to modify and / or monitor one or more operating parameters of the burner 1104. Additionally, the burner fuel flow rate controller 1114 may be operable to transmit data indicating the aviation fuel flow (or flow rate) 1105 supplied to the burner 1104. In particular, the burner fuel flow rate controller 1114 may be configured to modify (e.g., increase or decrease) the aviation fuel flow 1105 supplied to the burner 1104.

[0233] like Figure 17 As shown, combustor 1104 can receive combustible products from at least two separate sources (e.g., aviation fuel stream 1105 and output product stream 1106), each of which will generate a certain amount of heat or enthalpy within combustor 1104. Aviation fuel stream 1105 and output product stream 1106 will co-combust within combustor 1104 to generate enthalpy output 1116 at the outlet of combustor 1104. It will be understood that regulating the enthalpy output 1116 from combustor 1104 is important for meeting thrust requirements and minimizing thrust disturbances during operation of the propulsion system.

[0234] like Figure 17 As shown, controller 240 can provide power setpoint 1120 to power controller 1110, which is also referred to as power offtake demand from the aircraft computer or pilot. In response to receiving power setpoint 1120, power controller 1110 can modify the operating conditions of fuel cell system 1102 such that the power output 1118 of fuel cell system 1102 is equal to power setpoint 1120. Similarly, controller 240 can provide requested enthalpy 1122 to combustor fuel flow rate controller 1114 (e.g., based at least in part on the desired thrust of the propulsion system). This requested enthalpy 1122 can be derived from thrust demand from the aircraft computer or pilot. In response to receiving requested enthalpy 1122, combustor fuel flow rate controller 1114 can modify the aviation fuel flow 1105 to combustor 1104 such that enthalpy output 1116 is equal to requested enthalpy 1122.

[0235] The power exhaust demand, or power setpoint 1120, reflects the electrical load requirements of the aircraft, while the requested enthalpy 1122 reflects the aircraft thrust demand, which can be independent of the power setpoint 1120. The coordinated control system 1100 needs to handle both the power setpoint 1120 and the requested enthalpy 1122 in a systematic manner. However, it has been found that fuel cell operation can cause significant coupling effects from the combustor due to variations in fuel cell exhaust composition / enthalpy; on the other hand, variations in combustor and engine operating conditions can, in turn, affect fuel cell operation. Therefore, a coordinated fuel cell and combustor control system is proposed to mitigate the inherent coupling effects.

[0236] In an exemplary embodiment, the coordinated control system 1100 may be configured to determine, at least in part, data indicative of at least one of the enthalpy or composition of the output products 1106 from the fuel cell system 1102, based on a modified fuel cell model 1126. The modified fuel cell model 1126 may utilize memory stored in either controller (such as...). Figure 5 One or more models are stored in the memory 332B of the controller 240 shown, and can be processed by a processor (such as...) Figure 5 The processor 332A shown executes this. Generally, the modified fuel cell model 1126 can provide one or more inputs 1124, and based at least in part on the one or more inputs 1124, the modified fuel cell model 1126 can generate one or more fuel cell model outputs 1128. For example, the fuel cell controller 1108 can provide fuel cell component operating parameters as inputs 1124 to the modified fuel cell model 1126, and based at least in part on the fuel cell component operating parameters, the modified fuel cell model 1126 can generate data (e.g., gas composition data) indicating at least one of the enthalpy or composition of the output product 1106 as the fuel cell model output 1128. (Refer to below...) Figure 18 The operation of the modified fuel cell model 1126 is described in more detail.

[0237] like Figure 17 As shown, based at least in part on the fuel cell model output 1128, the controller 240 can generate or determine an enthalpy trimming 1130. The enthalpy trimming 1130 can be used to adjust and / or modify the value of the requested enthalpy 1122 transmitted to the burner fuel flow rate controller 1114. For example, the enthalpy trimming 1130 can adjust the requested enthalpy 1122 based on the amount of enthalpy added to the burner 1104 via the output product 1106.

[0238] Enthalpy trimming 1130 can be based on a transfer function that describes the steady-state and dynamic relationship between the fuel cell model output 1128 and the combustor enthalpy. Enthalpy trimming 1130 may include an "inverse model" to calculate the expected change in combustor enthalpy that can compensate for potential changes in SOFC exhaust composition or enthalpy. For example, if the fuel cell model output 1128 indicates that the enthalpy of the fuel cell exhaust entering the combustor will increase, enthalpy trimming 1130 can calculate the amount of combustor enthalpy that should be trimmed to mitigate potential disturbances caused by the enthalpy of the fuel cell exhaust entering the combustor. As a non-limiting example, enthalpy trimming 1130 may be a first-order, second-order, or higher-order transfer function that captures the transient time from the time of change in fuel cell operation to the time when the fuel cell exhaust affects the combustor enthalpy.

[0239] In this way, the controller 240 can take into account the enthalpy added to the combustor 704 via the output product 1106 by adjusting the aviation fuel flow 1105 at least in part based on the enthalpy trimming 1130. This feature advantageously allows the fuel cell system 1102 to be operated independently of the combustor 1104 without causing any thrust disturbance.

[0240] In some embodiments, the coordinated control system 1100 may determine data indicating the burner outlet enthalpy based at least in part on data of burner operating parameters and at least one of the enthalpy or composition of the output products. In various embodiments, burner operating parameters may include at least one of the fuel / air ratio, burner pressure, or burner temperature of burner 1104. Burner operating parameters may be received via one or more sensors configured to operatively communicate with burner 1104. At other times, burner operating parameters may be received via calculations from one or more sensors not configured to operatively communicate with burner 1104. For example, the coordinated control system 1100 may include a burner enthalpy model 1132. The burner enthalpy model 1132 may be stored in the memory of any controller (such as...). Figure 5 The controller 240 shown is stored in memory 332B and can be controlled by a processor (such as...). Figure 5The processor 332A shown executes this. Specifically, the burner enthalpy model 1132 can be a first-principles-based model, a data-driven model such as a neural network, fuzzy logic, a lookup table, or any combination thereof. Generally, the burner enthalpy model 1132 can be provided with one or more inputs 1129, 1131, and based at least in part on one or more inputs 1129, 1131, the burner enthalpy model 1132 can generate one or more outputs 1133. For example, the burner enthalpy model 732 can receive the enthalpy of the output product 706 from the modified fuel cell model 1126 as a first input 1129, and can receive burner operating parameters as a second input 1131. Based at least in part on the first input 1129 and the second input 1131, the controller 240 can use the burner enthalpy model 1132 to generate data indicating the burner outlet enthalpy and temperature as output 1133.

[0241] The estimated output 1133 from the combustor enthalpy model 1132 can be used (e.g., via controller 240) to calculate the compressor exhaust flow rate for both fuel cell and combustor control, as well as for combustor performance evaluation and thrust calculation. In aircraft engine operation, the combustor outlet work affects the turbine work, which in turn affects the compressor outlet air conditions via the shaft. This compressor outlet air supplies both the fuel cell and the combustor. Therefore, the compressor outlet air conditions have a direct impact on the operation of both the fuel cell and the combustor. In some applications, the air flow rate at the outlet of compressor 112 can be calculated based on flight and engine conditions. The combustor outlet enthalpy model 1132 described herein takes into account not only the primary aviation fuel effects but also the fuel cell exhaust effects, significantly improving the accuracy of compressor exhaust flow rate calculations, which in turn improves the quality of stoichiometric control of the fuel cell reformer and the air-fuel ratio of the combustor.

[0242] Now for reference Figure 18 This will be described in more detail. Figure 17 The modified fuel cell model 1126 operates as described above. The modified fuel cell model 1126 receives fuel cell operating parameters as input 1124. In many embodiments, the fuel cell assembly operating parameter input 1124 may be at least one of the following: fuel and / or air flow rate, equivalence ratio (e.g., air / fuel ratio provided to fuel cell system 1102), fuel utilization rate (such as the percentage of fuel used by fuel cell system 1102), current (such as the power output 1118 generated by fuel cell system 1102), pressure, or temperature.

[0243] The modified fuel cell model 1126 further includes a fuel cell model 1136, which is configured to receive fuel cell operating parameter input 1124. The fuel cell model 1136 can be a first-principles-based model, a data-driven model such as a neural network, fuzzy logic, a lookup table, or any combination thereof. The fuel cell model 1136 can generally be configured to determine estimated gas composition data 1138 in response to the fuel cell operating parameter input 1124.

[0244] However, in the illustrated embodiment, the modified fuel cell model 1126 is further configured to receive sensed gas composition data 1140 from the gas sensor 1141. The sensed gas composition data 1140 may include the same gas composition data as the estimated gas composition data 1138.

[0245] The modified fuel cell model 1126 further includes a fusion filter 1142, configured to receive estimated gas composition data 1138 and further configured to receive sensed gas composition data 1140. Through one or more control algorithms, rules, etc., the fusion filter 1142 can determine the actual gas composition data to be provided as the fuel cell model output 1128. For example, the fuel cell model output 1128 may include fuel cell exhaust components, including volume percentages of one or more of H2, CO, CO2, H2, N2, O2, etc. An alternative to the fuel cell model output 1128 could be exhaust enthalpy (or the low calorific value of fuel cell exhaust).

[0246] Furthermore, for Figure 18 An exemplary aspect of the modified fuel cell model 1126 depicted herein further includes a calibration module 1144 configured to calibrate the fuel cell model 1136 at least in part based on sensed gas composition data 1140. More specifically, the calibration module 1144 is configured to receive actual gas composition data provided as fuel cell model output 1128 and estimated gas composition data 1138 generated by the fuel cell model 1136. Calibrating the fuel cell model 1136 may include updating one or more multipliers of the fuel cell model 1136, assumptions of the fuel cell model 1136, etc.

[0247] Furthermore, the exemplary modified fuel cell model 1126 further includes a fault detection module 1146. The fault detection module 1146 is configured to receive actual gas composition data and sensed gas composition data 1140 provided as output 1128 of the fuel cell model. The fault detection module 1146 may include one or more algorithms, rules, etc., for comparing the actual gas composition data with the sensed gas composition data 1140 to determine potential faults in the gas sensor 1141.

[0248] However, it will be understood that in other exemplary embodiments, the fault detection module 1146 may be configured to receive the estimated gas composition data 1138 directly from the fuel cell model 1136.

[0249] Furthermore, although the fault detection module 1146 and calibration module 1144 are described as separate from, for example, the fusion filter 1142, in other embodiments, one or more of the fault detection module 1146, calibration module 1144 and fusion filter 1142 may be integrated.

[0250] Briefly back Figure 17 It will be understood that the exemplary burner enthalpy model 1132 can be in accordance with the above reference. Figure 18 The modified burner enthalpy model is constructed in a similar manner to the exemplary modified fuel cell model 1126 described. For example, the burner enthalpy model 1132 may receive a first input 1129 (which may include enthalpy data from the fuel cell's output products) from the modified fuel cell model 1126, and further may receive sensed gas composition data indicative of the enthalpy of the fuel cell's output products from a gas sensor. The burner enthalpy model 1132 may further include a fusion filter for receiving the first input 1129 and the sensed gas composition data, and determining the actual enthalpy data from the fuel cell's output products. Similar calibration and fault detection modules may also be included.

[0251] Now for reference Figure 19 A gas turbine engine 100 and a fuel cell assembly 204 are provided according to another exemplary aspect of this disclosure, which can be referenced above. Figure 16 The exemplary method 1000 operation is discussed.

[0252] With respect to the exemplary aspects depicted, the gas turbine engine 100 and the fuel cell assembly 204 can be in accordance with the above references. Figure 2The exemplary gas turbine engine 100 and fuel cell assembly 204 described are constructed in substantially the same manner. Therefore, the same or similar figures may refer to the same or similar parts. Thus, it will be understood that the fuel cell assembly 204 generally includes a fuel cell stack 294 having one or more fuel cells, and further includes a fuel inlet line 150 and an air inlet line 315. Furthermore, the fuel cell assembly 204 includes a fuel valve 151 for controlling the operation of fuel flow through the fuel inlet line 150 to the fuel cell stack 294, and an air valve 317 for controlling airflow through the air inlet line 315. Although the fuel valve 151 and air valve 317 are depicted aligned with the fuel inlet line 150 and air inlet line 315 directly upstream of the fuel cell stack 294, in other embodiments, the fuel valve 151, air valve 317, or both may be located further upstream, for example, upstream of the fuel processing unit 304, the air processing unit 306, or both (see [link to relevant documentation]). Figure 5 Each of the fuel valve 151 and the air valve 317 is operatively connected to the controller 240.

[0253] Furthermore, it will be understood that, for Figure 19 In the exemplary embodiments depicted, the control system of the propulsion system (including controller 240) may include a safety management control system for the fuel cell assembly 204 and the gas turbine engine 100. Specifically, the fuel cell assembly 204 further includes a fuel cell safety gas line 380 and a fuel cell safety gas valve 382. The fuel cell safety gas line 380 is in fluid communication with the fuel inlet line 150, and more specifically, is in fluid communication with the fuel inlet line 150 at a location downstream of the fuel valve 151.

[0254] The fuel cell assembly 204, the gas turbine engine 100, or both further include a gas sensor 350. The gas sensor 350 can be positioned to sense gas composition data of the fluid 362 surrounding the fuel cell stack 294. For example, the gas sensor 350 can be configured to sense gas composition data including the percentage of oxygen, the percentage of hydrogen, and the percentage of combustible gas in the fluid 362 surrounding the fuel cell stack 294. In this way, the gas sensor 350 can be configured as a low explosion level (LEL) sensor.

[0255] Gas sensor 350 is operatively connected to controller 240 to provide gas composition data to controller 240. Notably, when configured as an LEL sensor, the gas composition data from gas sensor 350 can be a Boolean response, indicating, for example, whether the percentage of combustible gas within fluid 362 surrounding fuel cell stack 294 exceeds a low explosion level threshold.

[0256] In response to receiving data from gas sensor 350 indicating that the percentage of combustible gas in fluid 362 surrounding fuel cell stack 294 exceeds a low explosion level threshold, controller 240 may be configured to actuate fuel valve 151 to cut off fuel flow to fuel cell stack 294, and further actuate fuel cell safety gas valve 382 to provide safety gas flow to fuel cell stack 294. More specifically, actuating fuel cell safety gas valve 382 may provide safety gas flow to fuel inlet line 150 via fuel cell safety gas line 380, and to fuel cell stack 294 via fuel inlet line 150. Safety gas may be, for example, carbon dioxide (e.g., supercritical carbon dioxide), nitrogen, a gas with a combustible gas volume of less than about 10% (e.g., less than about 5%), air, etc.

[0257] In short, it will also be understood that, for the exemplary aspects depicted, the gas turbine engine 100 includes a fire detection sensor 384, which can be operatively connected to the controller 240 to provide data indicating the presence of a fire in the area surrounding the fuel cell stack 294. The controller 240 can be similarly configured to, in response to receiving data from the fire detection sensor 384 indicating the presence of a fire in the area surrounding the fuel cell stack 294, supply safety gas to the fuel inlet line 150 and the fuel cell stack 294 via the fuel cell safety gas line 380.

[0258] Now for reference Figure 20 The present disclosure describes a propulsion system according to another exemplary aspect, which can be used in conjunction with one or more exemplary control systems and methods described herein. Specifically, the propulsion system includes a gas turbine engine 100 and a fuel cell assembly 204. Although only the combustor 206 of the gas turbine engine 100 is depicted for illustrative purposes, the gas turbine engine 100 can be constructed in a manner similar to the one or more exemplary gas turbine engines 100 described above. Similarly, the fuel cell assembly 204 can be constructed in a manner similar to the one or more exemplary fuel cell assemblies 204 described above.

[0259] For example, regarding the gas turbine engine 100, the gas turbine engine 100 generally includes a combustion section 114, which includes a combustor 206. Further, for the depicted embodiment, the fuel cell assembly 204 generally includes a fuel processing unit within a fuel cell stack 294. The fuel cell stack 294 may include a fuel cell with a defined outlet configured to provide output products to the combustor 206.

[0260] However, in the depicted embodiments, the fuel cell assembly 204 is more specifically configured as a modular fuel cell assembly 1200. In particular, Figure 20 The modular fuel cell assembly 1200 generally includes a first fuel cell string 1202, a second fuel cell string 1204, and, for the depicted embodiment, a third fuel cell string 1206 and a fourth fuel cell string 1208.

[0261] The first fuel cell string 1202 includes a first processing unit 1210 and a first fuel cell stack 1212, wherein the first fuel cell stack 1212 includes a first fuel cell with a defined outlet configured to provide output product 1214 from the first fuel cell to the burner 206. Similarly, the second fuel cell string 1204 includes a second processing unit 1216 and a second fuel cell stack 1218. The second fuel cell stack 1218 includes a second fuel cell with a defined outlet configured to provide output product 1220 from the second fuel cell to the burner 206.

[0262] In this way, it will be understood that the first fuel cell string 1202 and the second fuel cell string 1204 include dedicated processing units 1210 and 1216. More specifically, for the depicted embodiment, the first processing unit 1210 may be configured as a first fuel processing unit, and the second processing unit 1216 may be configured as a second fuel processing unit. The first fuel processing unit is dedicated to the first fuel cell string 1202 for providing a first fuel flow 1222 to the first fuel cell stack 1212. The second fuel processing unit is dedicated to the second fuel cell string 1204 for providing a second fuel flow 1224 to the second fuel cell stack 1218. The first and second fuel processing units may be configured in accordance with, for example, referenced above. Figure 5 The exemplary fuel processing unit 304 described is constructed in a similar manner.

[0263] Although not depicted, each of the first fuel cell string 1202 and the second fuel cell string 1204 may further include an air handling unit (similar to...). Figure 5 The air handling unit 306 can be dedicated to the corresponding fuel cell strings 1202 and 1204.

[0264] Furthermore, for the described exemplary aspects, the propulsion system further includes a control system having one or more sensors configured to sense first-order gas composition data passing through the first fuel cell string 1202 and second-order gas composition data passing through the second fuel cell. The first stream may include, for example, a first fuel stream 1222 from the first fuel processing unit to the first fuel cell stack 1212, an output product stream 1214 from the first fuel cell stack 1212 to the combustor 206, and a first air stream (not shown) from the first air processing unit to the first fuel cell stack 1212. Similarly, the second stream may include, for example, a second fuel stream 1224 from the second fuel processing unit to the second fuel cell stack 1218, an output product stream 1220 from the second fuel cell stack 1218 to the combustor 206, and a second air stream (not shown) from the second air processing unit to the second fuel cell stack 1218.

[0265] More specifically, in the illustrated embodiment, one or more sensors include gas sensors, and even more specifically, multiple gas sensors. The gas sensors can be constructed in a manner similar to the exemplary gas sensor 350 described above. More specifically, in the illustrated embodiment, one or more sensors include a first fuel flow gas sensor 1226A and a first output product gas sensor 1228A. The first fuel flow gas sensor 1226A is configured to sense gas composition data of a first fluid flow (e.g., first fuel flow 1222) passing through the first fuel cell string 1202 at a location downstream of the first processing unit 1210 and upstream of the first fuel cell stack 1212. The first output product gas sensor 1228A is configured to sense gas composition data of a first fluid flow (e.g., output product 1214) passing through the first fuel cell string 1202 at a location downstream of the first fuel cell stack 1212. Similarly, in the illustrated embodiment, one or more sensors include a second fuel flow gas sensor 1226B and a second output product gas sensor 1228B. The second fuel flow gas sensor 1226B is configured to sense gas composition data of a second fluid flow (e.g., second fuel flow 1224) passing through the second fuel cell string 1204 at a location downstream of the second processing unit 1216 and upstream of the second fuel cell stack 1218. The second output product gas sensor 1228B is configured to sense gas composition data of a second fluid flow (e.g., output product 1220) passing through the first fuel cell string 1202 at a location downstream of the second fuel cell stack 1218.

[0266] It is worth noting that, for the depicted embodiment, the third fuel cell string 1206 and the fourth fuel cell string 1208 are constructed in a similar manner to the first fuel cell string 1202 and the second fuel cell string 1204 (e.g., having a third processing unit 1230 and a third fuel cell stack 1232, and a fourth processing unit 1234 and a fourth fuel cell stack 1236, respectively). Similarly, the control system further includes a third fuel flow gas sensor 1226C, a third output product gas sensor 1228C, a fourth fuel flow gas sensor 1226D, and a fourth output product gas sensor 1228D.

[0267] It will be understood that although the depicted modular fuel cell assembly 1200 includes four fuel cell strings, in other exemplary embodiments, any other suitable number of fuel cell strings (e.g., between 2, 3, 5, 2, and 20, etc.) may be provided. It will also be understood that, although for Figure 20 In the embodiments depicted, the control system includes two gas sensors for each fuel cell string; however, in other exemplary embodiments, the control system may include only fuel flow gas sensors, such as fuel flow gas sensors 1226A-1226D, or alternatively, it may include only output product gas sensors, such as output product gas sensors 1228A-D.

[0268] It will also be understood that, in at least some exemplary embodiments, the first fuel cell string 1202 and the second fuel cell string 1204 are independently connected within the gas turbine engine 100. In this way, in the event of failure, repair, or maintenance of the respective fuel cell string, the first fuel cell string 1202 or the second fuel cell string 1204 can be individually disconnected and connected from the gas turbine engine 100. This allows for the removal and replacement of one of the fuel cell strings without removing the remaining fuel cell strings.

[0269] Furthermore, it will be understood that, for the depicted exemplary embodiments, one or more sensors include a first sensor (e.g., 1226A, 1228A) positioned aligned with the first fuel cell string 1202 and a second sensor (e.g., 1226B, 1228B) positioned aligned with the second fuel cell string 1204. More specifically, for the depicted embodiments, each of the first fuel flow gas sensor 1226A and the first output product gas sensor 1228A is positioned aligned with the first fuel cell string 1202, and each of the second fuel flow gas sensor 1226B and the second output product gas sensor 1228B is positioned aligned with the second fuel cell string 1204.

[0270] However, it will be understood that in other exemplary embodiments, the control system may have one or more sensors of any other suitable configuration to sense desired gas composition data of the first fluid flow through the first fuel cell string 1202 and desired gas composition data of the second flow through the second fuel cell string 1204. For example, reference will now be made to... Figure 21 A schematic diagram of a modular fuel cell assembly 1200 according to another example aspect of this disclosure is provided. Figure 21 An exemplary modular fuel cell assembly 1200 can be coupled with... Figure 20 The exemplary modular fuel cell assembly is constructed in essentially the same way.

[0271] However, in Figure 21 In an exemplary aspect, the control system includes one or more gas sensors, and more specifically, one or more multi-gas sensors configured to sample a first fluid flow through the first fuel cell string 1202 and a second fluid flow through the second fuel cell string 1204. Particularly for Figure 21 In an exemplary embodiment, one or more multi-gas sensors are spaced apart from a first fluid flow and a second fluid flow and are configured to sense gas composition data from these spaced locations. Specifically, for the depicted embodiment, the control system includes a fuel flow gas sensor 1226 and a fuel flow sampling conduit 1238. The fuel flow sampling conduit 1238 is configured to provide the fuel flow gas sensor 1226 with sampled flows from fuel cell strings 1202, 1204, 1206, and 1208 (e.g., from locations downstream of the respective processing units and upstream of the respective fuel cell stacks). Similarly, for the depicted embodiment, the control system includes an output product gas sensor 1228 and an output product sampling conduit 1240. The output product sampling conduit 1240 is configured to provide the output product gas sensor 1228 with sampled flows from fuel cell strings 1202, 1203, 1206, and 1208 (e.g., from locations downstream of the respective fuel cell stacks). In this way, it will be understood that the first multi-gas sensor (fuel flow gas sensor 1226) and the second multi-gas sensor (output product gas sensor 1228) of the control system can be configured to sample the first fluid flow through the first fuel cell string 1202, the second fluid flow through the second fuel cell string 1204, the third fluid flow through the third fuel cell string 1206, and the fourth fluid flow through the fourth fuel cell string 1208.

[0272] Now refer to the reply Figure 20 As will be understood from the exemplary embodiments described above, the exemplary control system further includes a controller 240. The controller 240 may be configured in accordance with, for example, referenced above. Figure 5One or more exemplary controllers 240 described are constructed in a similar manner. Controller 240 is operatively connected to one or more sensors (1226A-D, 1228A-D), and further, for exemplary embodiments, controller 240 is operatively connected to each of the fuel cell strings 1202, 1204, 1206, 1208 for independent control of each fuel cell string. For example, in the depicted embodiment, the first fuel cell string 1202 is independently controllable relative to the second fuel cell string 1204 (and the third fuel cell string 1206 and the fourth fuel cell string 1208). More specifically, for the depicted exemplary embodiments, a first fluid flow through the first fuel cell string 1202 is independently controllable relative to a second fluid flow through the second fuel cell string 1204. Specifically, for the depicted embodiment, the modular fuel cell assembly includes a first fuel flow valve 1242, a second fuel flow valve 1244, a third fuel flow valve 1246, and a fourth fuel flow valve 1248. The first fuel flow valve 1242 is operable to control one or more aspects of a first fluid flow through the first fuel cell string 1202, the second fuel flow valve 1244 is operable to control one or more aspects of a second fluid flow through the second fuel cell string 1204, the third fuel flow valve 1246 is operable to control one or more aspects of a third fluid flow through the third fuel cell string 1206, and the fourth fuel flow valve 1248 is operable to control one or more aspects of a fourth fluid flow through the fourth fuel cell string 1208.

[0273] The first fuel flow valve 1242 of the first fuel cell string 1202, the second fuel flow valve 1244 of the second fuel cell string 1204, the third fuel flow valve 1246 of the third fuel cell string 1206, and the fourth fuel flow valve 1248 of the fourth fuel cell string 1208 are each operably connected to the controller 240 and are independently controllable by the controller 240.

[0274] In this way, it will be understood that the controller 240 of the control system can be configured to receive gas composition data of a first fluid flow through the first fuel cell string 1202 and gas composition data of a second fluid flow through the second fuel flow string 1224, and can be further configured to modify the operating parameters of the first fuel cell string 1202, the second fuel cell string 1204, or both in response to the received gas composition data.

[0275] It is worth noting that, for the depicted embodiment, controller 240 is further configured to receive operational data from flight database 1250, such as modular fuel cell assembly 1200, gas turbine engine 100, aircraft including modular fuel cell assembly 1200 and gas turbine engine 100, or combinations thereof. Controller 240 may be further configured to make control decisions in response to the received operational data and sensed gas composition data of one or more fuel cell strings 1202, 1204, 1206, 1208. Furthermore, controller 240 may be configured to provide data to engine controller 1252 of gas turbine engine 100 (such as a full authority digital engine control controller (“FADEC”)) to aid in controlling gas turbine engine 100, and may further provide one or more notifications to an operator (such as a pilot's cockpit at 1254).

[0276] Now for reference Figure 22 A flowchart of a method 1300 for operating a propulsion system according to an exemplary aspect of this disclosure is provided. The exemplary method 1300 can be used to control a propulsion system including a modular fuel cell assembly and a gas turbine engine, the modular fuel cell assembly and the gas turbine engine being coupled to... Figure 20 and Figure 21 The exemplary modular fuel cell assembly 1200 and the gas turbine engine 100 are constructed in a similar manner.

[0277] Method 1300 includes, at (1302), providing the output products from a first fuel cell of a first fuel cell string of a modular fuel cell assembly and the output products from a second fuel cell of a second fuel cell string of a modular fuel cell assembly to the combustor of the combustion section of a gas turbine engine. The provision of the output products at (1302) can occur simultaneously with the operation of the propulsion system during flight operations.

[0278] Method 1300 further includes, at (1304), receiving gas composition data of a first fluid flow through a first fuel cell string and gas composition data of a second fluid flow through a second fuel cell string. Receiving the gas composition data at (1304) may include receiving the gas composition data from one or more sensors, such as from one or more gas sensors, such as from one or more multi-gas sensors.

[0279] Furthermore, for the exemplary aspects described, method 1300 includes, at (1306), modifying the operating parameters of the first fuel cell string, the second fuel cell string, or both. More specifically, modifying the operating parameters at (1306) includes, at (1308), modifying the operating parameters of the first fuel cell string, the second fuel cell string, or both in response to gas composition data received at (1304).

[0280] More specifically, for the exemplary aspects described, method 1300 is configured to further utilize operational data to control the modular fuel cell assembly. For example, method 1300 further includes, at (1310), receiving operational data of the fuel cell assembly, the gas turbine engine, an aircraft including the fuel cell assembly and the gas turbine engine, or a combination thereof. The operational data received at (1310) may be a health indicator of the fuel cell assembly, the gas turbine engine, or both. For example, the operational data received at (1310) may include system health indicators, such as accumulated health data or the degree of degradation of one or more aspects of the modular fuel cell assembly. For example, the operational data received at (1310) may include the percentage to end-of-life of one or more of the fuel processing unit, fuel cell stack (and fuel cell) of the modular fuel cell assembly. Similar data may be received for various components of the gas turbine engine. Aircraft-related operational data received at (1310) may include the aircraft's flight plan, the aircraft's maintenance plan, etc.

[0281] Still referencing Figure 22 An exemplary aspect of method 1300, modifying the operating parameters of the first fuel cell string, the second fuel cell string, or both (1306) further includes, at (1312), modifying the operating parameters of the first fuel cell string, the second fuel cell string, or both in response to gas composition data received at (1304) and in response to operating data received at (1310).

[0282] For example, modifying the operating parameters at (1312) includes determining at (1314) that a component of the first fuel cell string exceeds a health threshold. The health threshold may be a lifespan percentage threshold or other accumulated health data threshold. Determining at (1314) that a component of the first fuel cell string exceeds the health threshold may include determining that a component of the first fuel cell string is unlikely to fail in the desired manner beyond the next scheduled maintenance of the aircraft. In response to determining at (1314) that a component of the first fuel cell string exceeds the health threshold, modifying the operating parameters at (1312) further includes increasing the power output of the first fuel cell string at (1316). Increasing the power output of the first fuel cell string at (1316) may include increasing the fuel flow to the first fuel cell stack relative to the fuel flow to the second fuel cell stack.

[0283] In this way, method 1300 can accelerate the lifespan of the first fuel cell string, allowing it to be replaced during the next scheduled maintenance of the aircraft, rather than failing during subsequent flight missions.

[0284] In an alternative exemplary aspect of method 1300, modifying the operating parameters at (1312) includes detecting an anomaly within the fuel cell assembly at (1318). Detecting an anomaly within the fuel cell assembly may include detecting an anomaly within the first fuel cell string. This anomaly may indicate that an affected component may continue to provide the desired output, but that component has degraded beyond its nominal level. In response to detecting an anomaly at (1318), modifying the operating parameters at (1312) further includes reducing the power output of the first fuel cell string at (1320). Reducing the power output of the first fuel cell string at (1320) may include reducing the fuel flow to the first fuel cell stack relative to the fuel flow to the second fuel cell stack. In some exemplary aspects, reducing the power output of the first fuel cell string at (1320) may further include increasing the fuel flow to the second fuel cell stack, or alternatively, may include increasing the power extraction from a separate power source (e.g., a motor driven by a gas turbine engine) of the gas turbine engine, the fuel cell assembly, or the aircraft.

[0285] In this way, method 1300 can prevent the components of the first fuel cell string from failing until the first fuel cell string can receive maintenance to resolve the detected anomaly.

[0286] It will be understood that the gas sensor described above can be any suitable gas sensor used to detect data on the composition of gas flowing into, toward, or through a fluid flow into a gas turbine engine, fuel cell assembly, or both.

[0287] In particular, in some exemplary embodiments, the gas sensor can be configured to sense gas composition data of a single component of the fluid (e.g., the percentage of nitrogen in the output product stream from the anode). This can allow for simpler and more cost-effective detection, maintenance, reporting, and / or control systems while still providing gas composition data.

[0288] Alternatively, gas sensors can be configured to sense gas composition data of multiple components in a single fluid (e.g., the percentage of CO2 and H2O in the output product stream from the cathode). This configuration can provide more versatile detection, maintenance, reporting, and / or control systems, offering valuable gas composition data.

[0289] Alternatively, the gas sensor can be configured to sense gas composition data of one or more components of multiple fluids (e.g., the percentage of CO2 and / or H2O in the output product stream from the cathode, the percentage of nitrogen in the output product stream from the anode, and / or the percentage of oxygen in the fluid surrounding the fuel cell). This configuration can provide more versatile detection, maintenance, reporting, and / or control systems that offer valuable gas composition data.

[0290] In this way, it will be understood that a gas sensor can be a multi-gas sensor having multiple sensing nodes and being configured to sense multiple unique responses (e.g., multiple unique electrical responses, vibration responses, etc.).

[0291] For example, in one exemplary embodiment, the gas sensor may use Raman spectroscopy, an optical analysis technique that relies on measurements of the vibrational and rotational properties of molecules. Raman spectroscopy produces a unique spectral fingerprint that can identify the chemical composition and molecular structure data of a fluid. Raman spectroscopy can be performed using a laser pointed at the fluid. The spectrometer collects and measures Raman scattered photons, creating a unique spectral fingerprint. Raman measurements are non-destructive and can be collected within seconds (e.g., less than 10 seconds, less than 5 seconds, or less than 3 seconds, depending on the laser power and the required detection resolution). Raman signals are easily interpreted: the distribution of spectral peaks describes the composition of the molecules, and the signal intensity is linearly correlated with concentration. Overlapping Raman peaks can be resolved using known data analysis techniques.

[0292] In some exemplary aspects, a gas sensor (multi-gas sensor or single-gas sensor) configured to sense the percentage of nitrogen can use Raman spectroscopy, as this technique is well-suited for determining the concentration of nitrogen at relatively low levels disclosed herein.

[0293] In another embodiment, the gas sensor configured as a multi-gas sensor can be a multi-response sensor, also known as a multivariable sensor, a multi-output sensor, or a multi-parameter sensor. Such a sensor has one or more variable control parameters that predictably affect the sensor's multi-gas sensing capability. Non-limiting examples of such variable control parameters include the sensor's operating frequency, operating wavelength, operating temperature, and energy sources applied to the sensor, such as optical illumination of the sensor at different wavelengths and intensities, or acoustic excitation of the sensor at different frequencies. Optionally, the multivariable gas sensor can be a sensor array.

[0294] Non-limiting examples of multi-gas sensors include impedance sensors, optical sensors, thermal conductivity sensors, electromechanical sensors, and field-effect transistor sensors.

[0295] Additionally or alternatively, in other exemplary embodiments, the gas sensor may use any other suitable technology. For example, now referring to... Figure 23 A gas sensor is provided according to another exemplary aspect of this disclosure. Figure 23 The gas sensor can be integrated into the above reference. Figures 1 to 22 In one or more exemplary systems and methods described.

[0296] In particular, Figure 23 An embodiment of a gas sensor configured as a multi-gas sensing system 1400 (i.e., a multi-gas sensor) is shown. The multi-gas sensing system 1400 examines a fluid in contact with it. The fluid can be a gas, liquid, gas-liquid mixture, solid, particulate or microparticle material, etc., containing one or more analyte gases to determine gas composition data.

[0297] The multi-gas sensing system 1400 may represent one or more different versions of the sensing system described herein. The multi-gas sensing system 1400 includes sensing circuitry 1500, modifier assembly 1422, and management circuitry 1410, which controls the operation of modifier assembly 1422 and sensing circuitry 1500. In one or more embodiments, sensing circuitry 1500 may be a resistor-capacitor RC circuit, including one or more resistor R and capacitor C components that may change in response to the presence of one or more analyte gases of interest. For example, management circuitry 1410 may change the resistance and / or capacitance of sensing circuitry 1500. In one or more embodiments, the circuitry of multi-gas sensing system 1400 is capable of performing impedance measurements to determine the impedance response to one or more analyte gases of interest. Impedance measurements may be performed at one or more different frequencies or at one or more different RC configurations of sensing circuitry 1500. For example, the sensing circuit 1500 of the multi-gas sensing system 1400 can measure the impedance response of the multi-gas sensing system 1400 at different frequencies, with different resistances of the RC circuit, with different capacitances of the RC circuit, or with any combination of two or more of these.

[0298] As used herein, the term impedance can be a non-limiting term for any electrical response of a sensing system to an alternating current applied to the sensing system. This response can be measured in various electrical properties. Non-limiting examples of these commonly measured electrical responses of a sensing system to an alternating current include impedance, admittance, reactance, susceptance, etc. In this specification, examples of responses are given as impedance; however, other electrical responses of the sensing system to an alternating current can be equally derived.

[0299] In one embodiment, the electrical response of the sensing system can be monitored at the gas modulation shoulder of the dielectric relaxation peak of the sensing material.

[0300] The impedance of the multi-gas sensing system 1400 can be measured at a single frequency, at discrete frequencies, or at multiple scan frequencies using an impedance analyzer or impedance analyzer circuit. The impedance analyzer or impedance analyzer circuit may be part of or connected to the management circuit 1410 and / or the system controller 1420, and is electrically connected to the sensing circuit 1500. Optionally, the management circuit 1410 of the multi-gas sensing system 1400 may also be referred to as a spectrum analyzer, analyzer, AC current response analyzer, etc.

[0301] In one or more embodiments, the impedance analyzer may be part of the management circuitry 1410 and may measure the electrical responses of at least two sensing elements in a multi-gas sensing system, wherein the two sensing elements are based on different detection principles. A non-limiting example of the first sensing element may be an electrode pair coated with a sensing material and positioned on a substrate. The impedance analyzer may measure the gas response of the first sensing element at a frequency near or at a single frequency of the dielectric relaxation peak of the sensing material. A non-limiting example of the second sensing element may be a mechanical resonator coated with a sensing material, such as a tuning fork resonator, a thickness shear mode resonator, or a surface acoustic wave resonator. The impedance analyzer may measure the location of the resonant peak frequency of the resonant second sensing element.

[0302] The multi-gas sensing system 1400 may include a system controller 1420. The system controller 1420 may include one or more devices, such as, but not limited to, a power supply 1430, a data analysis unit 1432, an output device 1434 (e.g., a security alarm), and a communication system 1436. One or more components of the system controller 1420 may include one or more processors, including one or more microprocessors, field-programmable gate arrays, and / or integrated circuits. In one or more embodiments, the multi-gas sensing system 1400 may be a battery-operated device and / or may be powered using energy obtainable from a main control system or by using energy obtained from environmental sources (e.g., light, vibration, heat, electromagnetic energy, etc.). In one or more embodiments, management circuitry 1410 and / or modifier component 1422 may be part of the system controller 1420. For example, one or more processors of the system controller 1420 may operate in a manner similar to that of management circuitry 1410 and / or modifier component 1422.

[0303] The data analysis unit 1432 may be in the form of an integrated circuit controller, positioned on the same board as the sensing elements. As an example, the multi-gas sensing system 1400 may operate with a power requirement of approximately 30 mA per hour or less for essentially continuous operation. The data analysis unit 1432 may receive data directly from one or more sensing elements 1402A-C, or via management circuitry 1410 from other sensing elements (such as temperature and / or ambient humidity sensing elements) positioned on the same board. The data analysis unit 1432 may also wirelessly receive data directly from one or more sensing elements 1402A-C, or wirelessly receive data via management circuitry 1410 from one or more sensing elements 1402A-C, or wirelessly receive data from other sensing elements located at or around the multi-gas sensing system 1400, etc.

[0304] Data can be stored in short-term and / or long-term memory storage devices (such as archived communication systems), which can be located within or away from the multi-gas sensing system 1400, and / or reconstructed and displayed for the operator, such as at an operator workstation, via an output device of the multi-gas sensing system 1400, etc. The data analysis unit 1432 can include one or more processors for analyzing data received from the management circuitry 1410. For example, the one or more processors can be one or more computer processors, controllers (e.g., microcontrollers), or other logic-based devices that operate based on one or more sets of instructions (e.g., software). The instructions for the operation of the one or more processors can be stored on a tangible and non-transitory computer-readable storage medium (such as a memory device). The memory device can include a hard disk drive, flash drive, RAM, ROM, EEPROM, etc. Alternatively, the set of instructions that directs the operation of the one or more processors can be hardwired into the logic of the one or more processors, such as by becoming hardwired logic formed and / or stored in the hardware of the one or more processors.

[0305] Figure 24 It shows Figure 23One embodiment of the sensing circuit 1500 of a multi-gas sensing system 1400. The sensing circuit 1500 includes one or more sensing elements 1402A-C. Each sensing element 1402A-C is operatively contacted with a fluid that may contain one or more analyte gases. The sensing elements 1402A-C include a common material, such as a dielectric material, for their respective substrates 1502. Notably, in other embodiments, a single substrate 1502 may be included for two or more sensing elements 1402A-C. Suitable materials for the substrate 1502 may include alumina, ceramics, etc. Each sensing element 1402A-C also includes a sensing film or sensing material 1508 coupled to the substrate 1502, and sensing electrodes 1510, 1512. Suitable examples of sensing materials or sensing films include metal oxide materials, composite materials, semiconductor materials, n-type semiconductor materials, p-type semiconductor materials, combinations of n-type and p-type semiconductor materials, nanocomposite materials, inorganic materials, any known sensing material capable of operating at temperatures up to 900°C, etc. Non-limiting examples of sensing materials operating at around 900°C include gallium oxide and silicon carbide. Suitable electrodes can be formed using metal etching, screen printing, inkjet printing, and mask-based metal deposition techniques. The thickness of the electrodes fabricated on substrate 1502 can range from about 10 nanometers to about 1000 micrometers. The materials used for the formation methods of substrate 1502, sensing layer 1508, and sensing electrodes 1510, 1512 can be selected, at least in part, based on application-specific parameters.

[0306] Sensing material 1508 is exposed to, in contact with, or indirectly in contact with at least one analyte gas. One or more heating elements 1504 (such as high resistivity elements) are coupled to different sides of substrate 1502 relative to sensing material 1508. Heating elements 1504 receive current from heater controller 1506, which represents hardware circuitry that conducts heater current or voltage to heating elements 1504 to heat substrate 1502 and, consequently, to sensing film or sensing material 1508 coupled to the other side of substrate 1502. For example, in one or more embodiments of the subject matter described herein, sensing material 1508 uses a metal oxide sensing film. Management circuitry 1410 can manage the temperature of each sensing element 1402A-C by controlling the operation of heater controller 1506 to control each heating element 1504. Sensing material 1508 may include one or more materials deposited on substrate 1502 to predictably and repeatably influence the impedance sensor response when interacting with the environment. For example, metal oxides (such as gallium oxide and silicon carbide) or any other material can be deposited as sensing material 1508.

[0307] In one or more embodiments, one or more filters (not shown) may be disposed above one or more sensing elements 1402A-C. For example, the one or more filters may be barriers or alternative protective mechanisms or devices that can block or reduce the amount of gaseous, liquid, and / or solid particles that may come into contact with the sensing material 1508, sensing electrodes 1510, 1512, etc. As an example, a single filter may be disposed above one or more sensing elements, or alternatively, each sensing element may include a separate filter disposed on top of the respective sensing element. The one or more filters may be gas-permeable membrane filters, such that the filter allows the gas of interest to pass through the filter from one side to the other and can block or reduce the amount of interfering gas or solid particles that may pass through the filter from one side to the other. In one or more embodiments, the gas-permeable membrane filter may include a fluoropolymer or a fluoropolymer coating. Optionally, the filter may include alternative coatings, such as flame retardants.

[0308] In the illustrated embodiments, the sensing electrodes 1510, 1512 of each sensing element 1402A-C are coupled to and / or disposed in the sensing material 1508 and connected to the substrate 1502. The sensing electrodes 1510, 1512 are conductors electrically connected to one or more of the modifier assembly 1422, transducers 1524A-C, and management circuitry 1410. In one or more embodiments, the transducers 1524A-C are electrode structures connected to an impedance detector system, and the sensor is a transducer coated with sensing material. The management circuitry 1410 may include an impedance detector system or a resistance detector system. Each of the modifier assembly 1422, transducers 1524A-C, and management circuitry 1410 may have one or more processors including one or more microprocessors, field-programmable gate arrays, and / or integrated circuits.

[0309] exist Figure 24 In the illustrated embodiment, each sensing element 1402A-C is operatively coupled to transducers 1524A-C, respectively. Alternatively, the sensing circuit 1500 may include a single transducer electrically coupled to each sensing element 1402, which can receive the electrical response from each sensing element 1402A-C and convert changes in the electrical response into a physical quantity.

[0310] In one or more embodiments, sensing electrodes 1510, 1512 may be coated with a sensing material that responds to one or more analyte gases of interest. One or more processors of management circuitry 1410 may direct the application of electrical stimulation to sensing electrodes 1510, 1512 at a frequency (such as an electrical excitation frequency or a single excitation frequency). For example, management circuitry 1410 may excite sensing elements 1402A-C with alternating current at at least one predetermined frequency, within a predetermined frequency range, etc.

[0311] One or more processors of management circuitry 1410 may receive electrical signals from sensing electrodes 1510, 1512 of each sensing element 1402A-C, the electrical signals representing the impedance or resistivity response of sensing element 1402A-C during exposure of sensing material 1508 to a fluid sample. For example, one or more processors of management circuitry 1410 may measure one or more electrical responses of sensing elements 1402A-C in response to excitation of sensing electrodes 1510, 1512 with an alternating current at at least one frequency or frequency range.

[0312] Management circuitry 1410 can determine one or more characteristics of sensing circuitry 1500 based on the electrical response from each of the different sensing elements 1402A-C. The characteristics of sensing circuitry 1500 may include the temperature of one or more sensing elements, temperature variation between two or more sensing elements, the state of sensing circuitry 1500 based on the configuration of sensing elements 1402, one or more environmental conditions (e.g., ambient temperature, humidity, etc.) in a predetermined area adjacent to sensing circuitry 1500, etc. In one or more embodiments, management circuitry 1410 can manage the configuration of each of the one or more sensing elements 1402A-C such that management circuitry 1410 can manage the resistor-capacitor configuration of at least one sensing element. Management circuitry 1410 can determine the state of sensing circuitry 1500 based on the resistor-capacitor configuration of each sensing element of the sensing circuit. Optionally, the state of sensing circuitry 1500 may be based on another configuration of the sensing circuit.

[0313] In one or more embodiments, the management circuitry 1410 may be referred to as a frequency impedance source and detector system. The management circuitry 1410 examines the impedance of the sensing elements 1402A-C to determine the presence and / or amount (e.g., concentration) of one or more analyte gases in the environment to which the sensing material 1508 of each sensing element 1402A-C is exposed, as described herein. The management circuitry 1410 may provide scanning capability to measure the sensor impedance response at single or multiple discrete frequencies. Alternatively, the system controller 1420 may provide the capability to measure the sensor impedance response across a frequency range.

[0314] Sensing circuitry 1500 may be operatively coupled to modifier assembly 1422, which may include a multiplexer. The multiplexer may be a single multi-frequency scan signal analyzer that can operate with a power requirement of less than 10 milliwatts (mW), less than 5 mW, or, in a more preferred embodiment, less than 1 mW. In one or more embodiments, each sensing element 1402A-C may be electrically coupled to modifier assembly 1422. System controller 1420 and / or management circuitry 1410 may direct one or more sensing elements 1402A-C to change the impedance of the electrical stimulation applied to the corresponding sensing material 1508 without changing the excitation frequency. As an example, modifier assembly 1422 may include a group of circuits (not shown) to change the impedance of each sensing element 1402A-C based on which circuits are electrically coupled or disconnected from the management circuitry. Optionally, the modifier assembly 1422 may include a single circuit, which may be a variable circuit or a variable device, capable of altering the impedance of each sensing element 1402A-C. In alternative embodiments, the modifier assembly may include a multiplexer having any alternative construction, one or more circuits, or any combination thereof.

[0315] The management circuitry 1410 and / or system controller 1420 can control the modifier assembly 1422 to apply electrical stimulation to each sensing element 1402A-C with a single or discrete impedance, or with varying impedance within a predetermined range, to interrogate the sensing material 1508 of each corresponding sensing element 1402A-C and at what interrogation time the stimulation is applied, so as to measure the sensor response at each frequency. For example, a multiplexer of the modifier assembly can electrically connect and / or disconnect one or more different sensing elements 1402A-C from the management circuitry 1410 and corresponding sensing electrodes 1510, 1512 to change which sensing element 1402A-C of the sensing circuitry 1500 is electrically connected and disconnected from the modifier assembly 1422 and the management circuitry 1410. For example, the modifier assembly 1422 can change the impedance of each sensing element 1402A-C without changing the electrical excitation frequency of the electrical stimulation applied to the sensing electrodes 1510, 1512.

[0316] The multiplexer of modifier component 1422 can combine multiple electrical response signals received from each sensing element 1402A-C into a single output, which is directed to management circuitry 1410. Management circuitry 1410 receives the electrical response signals in response to exciting sensing electrodes 1510, 1512 with alternating current at at least one predetermined frequency, and determines one or more characteristics of sensing circuitry 1500. Management circuitry 1410 can transmit or otherwise transmit the electrical response signals and the determined characteristics of sensing circuitry 1500 to one or more processors of system controller 1420. The concentration of at least one gas analyte can be determined based on the electrical responses of sensing elements 1402A-C and the characteristics of sensing circuitry 1500. For example, data analysis unit 1432 of system controller 1420 can convert the sensor responses into analytically useful gas composition data, such as the concentration of detected gases. Additionally, the data analysis unit 1432 can determine the concentration of at least one gaseous analyte based on one or more temperatures of each sensing element 1402A-C, environmental conditions near the sensing circuit 1500 (e.g., within a predetermined proximity or area of ​​the sensing circuit, such as within 1 meter, 5 meters, 10 meters, 100 meters, etc.).

[0317] As an example, system controller 1420 can determine the concentration of at least one analyte gas based on the electrical responses from two or more different sensing elements (e.g., sensing elements 1402A, 1402B). The first sensing element 1402A can operate at a first substantially constant temperature, and the second sensing element 1402B can operate at a different second substantially constant temperature. For example, management circuitry 1410 can control heating element 1504 such that the first sensing element 1402A can operate at the first temperature, and the second sensing element 1402B can operate at a different temperature, which may be greater than or less than the first temperature.

[0318] As another example, system controller 1420 can determine the concentration of one or more gaseous analytes based on the electrical responses from two or more different sensing elements, such as sensing elements 1402A and 1402B. Management circuitry 1410 can control the operation of heating element 1504 to operate the first sensing element 1402A at a periodically varying temperature, and can operate the second sensing element 1402B at a different periodically varying temperature. For example, heating element 1504 can change the temperature of the first sensing element 1402A (e.g., within a temperature range), raising and / or lowering the temperature to a predetermined value at predetermined times, for a predetermined duration, or any combination thereof. Additionally, heating element 1504 can change the temperature of the second sensing element 1402B (e.g., within different or the same temperature range), raising and / or lowering the temperature to different predetermined values ​​at different predetermined times, for different predetermined durations, or any combination thereof. Optionally, the first sensing element 1402A and the second sensing element 1402B can operate within similar temperature ranges for different durations, or operate within similar durations but different temperature ranges, or operate within similar temperatures and durations but at different times, etc.

[0319] Sensing elements 1402A-C, including sensing material 1508 and substrate 1502, heating element 1504, heater controller 1506, modifier assembly 1422, and transducers 1524A-C, are disposed within housing 1514. Housing 1514 can be operatively coupled to substrate or circuit board 1404 of multi-gas system 1400. Optionally, one or more sensing elements 1402A-C can be disposed in separate housings to separate each sensing element from the others. Optionally, one or more of the modifier assembly 1422, heater controller 1506, one or more transducers 1524, or management circuitry 1410 can be operatively coupled to circuit board 1404 of multi-gas sensing system 1400 and can be disposed outside or separate from housing 1514. Optionally, one or more components of the multi-gas sensing system 1400 may be disposed together with or contained within a housing with any other component of the multi-gas sensing system 1400, or disposed separately from or contained within a housing with any other component of the multi-gas sensing system 1400.

[0320] Figure 25A system layout of a multi-gas sensing system 1600 according to one embodiment is shown. Components and devices of the multi-gas sensing system 1600 are disposed on a substrate or circuit board 1404. In one or more embodiments, one or more components or devices of the multi-gas sensing system 1600 may be disposed on one or both sides of the circuit board 1404. The multi-gas sensing system 1600 may include one or more power devices or components (such as a power supply 1430 or a power switch), a power regulator 1630, non-volatile memory or other memory or storage device 1606, a charging source 1608 (such as a micro USB), or a charger or charging device 1610. In one or more embodiments, the power supply 1430 may be a battery source or any alternative untethered power source, or may include a battery source or any alternative untethered power source. The multi-gas sensing system 1600 may include processing components, such as management circuitry 1410, a system controller 1420, and a modifier assembly 1422. Management circuitry 1410 may include one or more processors, including one or more microprocessors, field-programmable gate arrays, and / or integrated circuits that can operate or function as an impedance analyzer, resistor detector system, etc. System controller 1420 may include one or more processors that can operate as a data analysis unit, memory system (e.g., memory 1606), etc. Modifier component 1422 is shown separate from system controller 1420 and management circuitry 1410, but alternatively, it may include one or both of management circuitry 1410 and system controller 1420.

[0321] The multi-gas sensing system 1600 includes two distinct sensing elements 1402A and 1402B. In one or more embodiments, sensing elements 1402A and 1402B may each be designed to sense or otherwise detect the presence of one or more of nitrogen (N2), oxygen (O2), carbon dioxide (CO2), water (H2O), methane (CH4), carbon monoxide (CO), etc. Optionally, the different sensing elements may be designed to sense or otherwise detect different gases. The multi-gas sensing system 1600 includes a sensing element 1602, which may be designed to sense or otherwise detect environmental conditions such as ambient temperature, ambient humidity, ambient pressure, etc. For example, sensing elements 1402A and 1402B may transmit an electrical response to a management circuit 1410 in response to a management circuit exciting sensing elements 1402A and 1402B with an alternating current at at least one predetermined frequency. The management circuit 1410 may measure the electrical response from sensing elements 1402A and 1402B to determine one or more characteristics of the sensing circuit. Additionally, the sensing element 1602 can detect environmental conditions in the area approaching the multi-gas sensing system 1400, and the management circuitry 1410 can determine characteristics of the multi-gas sensing system 1400 based on the environmental conditions detected by the sensing element 1602. One or more processors of the system controller 1420 can receive the electrical response and characteristics of the sensing circuitry, and determine the concentration of at least one gas analyte (such as the gas analyte of interest) based on the electrical response and characteristics of the sensing circuitry.

[0322] In one or more embodiments, the multi-gas sensing system 1600 may include an output device 1604. As an example, the output device 1604 may be shown as an LED light. For example, the LED light may illuminate based on the electrical response of the sensing element, characteristics of the sensing circuit, etc. Alternatively, the output device 1604 may be any alternative safety device that can illuminate, issue an alarm, vibrate, or otherwise communicate with the operator of the multi-gas sensing system 1400 if the system controller 1420 determines that the gas of interest exceeds a predetermined threshold.

[0323] Figure 26 A flowchart is shown of one embodiment of a method 1700 for sensing multiple different gas analytes using a multi-gas sensing system, according to one embodiment. The multi-gas sensing system may be... Figure 23The system is shown. At (1702A-C), each of the sensing elements 1402A-C can be operated. For example, the management circuitry can excite each sensing element using an alternating current at at least one predetermined frequency. The management circuitry can excite sensing element 1402A at a first predetermined frequency, and can excite sensing elements 1402B, 1402C at different, unique, or common frequencies relative to each other and sensing element 1402A. Optionally, one or more sensing elements 1402A-C can be excited within a predetermined frequency range. Figure 22 and Figure 23 In the illustrated embodiment, the system includes three sensing elements. Alternatively, the system may include fewer than three or more sensing elements. Alternatively, the system may include only one sensing element.

[0324] In one or more embodiments, the management circuit can manage the temperature of one or more sensing elements by controlling the heating element. For example, the management circuit can control the operation of the heating element such that one or more sensing elements operate at a predetermined temperature, operate within a predetermined temperature range, or that different sensing elements operate at different temperatures or within different temperature ranges. In one embodiment, the management circuit can control the heating element to periodically change the temperature of the first sensing element 1402A and substantially maintain the temperatures of the second sensing element 1402B and the third sensing element 1402C. For example, the management circuit can control the heating element such that the first sensing element 1402A operates at a first constant or a first variable temperature, and the second sensing element 1402B operates at a different second constant or a second variable temperature. As another example, the management circuit can control the heating element such that the first sensing element 1402A operates at a periodically variable temperature, and the second sensing element 1402B operates at a different periodically variable temperature. The different periodic temperatures of the second sensing element can be substantially the same temperature, but are heated at different periodic times than the first sensing element. Alternatively, the first sensing element and the second sensing element may be heated for substantially the same or common period of time, but the first sensing element may be heated to a temperature different from that of the second sensing element.

[0325] The management circuitry can synchronize the temperature of one or more sensing elements with the excitation of one or more sensing elements. For example, the management circuitry can synchronously control a heating element to control the temperature of one or more sensing elements to a predetermined value at substantially the same time or within a predetermined time window when one or more sensing elements are excited by an alternating current at a predetermined frequency. Alternatively, the management circuitry can synchronize the temperature change of one or more sensing elements with the duration of the excitation of the sensing elements. Alternatively, the management circuitry can substantially synchronously maintain the temperature range of one or more sensing elements while stimulating the sensing elements at a predetermined frequency or a frequency range that is variable. Alternatively, the management circuitry can otherwise synchronize the temperature of the sensing elements with the excitation of the sensing elements in any alternative configuration or based on one or more predetermined rules.

[0326] At (1704), one or more processors and / or system controllers of the management circuitry can analyze the electrical response from the sensing element in response to the excitation of the sensing electrode of the sensing element. The electrical response can be represented as a signal output from each of the one or more sensing elements. Alternating current can be applied to each of the one or more sensing elements at one or more different frequencies or with one or more different resistor-capacitor configurations for each sensing element. For example, a first sensing element can have a first resistor-capacitor configuration, and a first frequency can be applied to the sensing electrode of the first sensing element to excite the first sensing element. Alternatively, a second sensing element can have a second different resistor-capacitor configuration, and a different second frequency can be applied to the sensing electrode of the second sensing element. Alternatively, one or more sensing elements can have a common resistor-capacitor configuration, or a common frequency can be applied to excite one or more sensing elements.

[0327] Figure 27 A diagram illustrating the electrical responses of various sensing elements in a multi-gas sensing system according to one embodiment is shown. Graph A represents the electrical response from a first sensing element, which may be designed to detect the presence of methane (CH4). Graph B represents the electrical response from a second sensing element, which may be designed to detect the presence of carbon monoxide (CO). Alternatively, the electrical response may be received from a single sensing element, which may be configured to operate to detect the presence of CH4, CO, and any other gas. Graphs A and B are illustrated with a common horizontal axis 1802 representing time and vertical axes 1804 and 1806, respectively, representing the impedance of the sensing circuit 1500.

[0328] Measurements of one or more real parts Z' or imaginary parts Z” of the impedance of the sensing circuit 1500 can be performed within the dielectric relaxation region of the sensing circuit 1500. The dielectric relaxation region of the multi-gas sensing system 1400 can be a frequency range within a specified threshold of the measured impedance of the sensing circuit 1500 where a relaxation peak occurs, and / or a relaxation point frequency or inflection point frequency range of the imaginary part Z” of the impedance. For example, a relaxation peak (also called a relaxation frequency) can be identified as the location along the imaginary part of the impedance spectrum where the impedance response changes from concave to convex, or from convex to concave. An inflection point frequency is the frequency or frequency range where an inflection point occurs. Alternatively, an inflection point can be determined by examining the real part of the measured impedance of the sensing material 1508 to locate the position where the curvature of the real part of the impedance changes from concave to convex, or from convex to concave. In one or more embodiments, the electrical response of the sensing system is monitored at the gas-modulated leading shoulder of the dielectric relaxation peak of the semiconductor sensing material. For n-type semiconductor sensing materials, the leading shoulder can be a high-frequency region of the relaxation peak. For p-type semiconductor sensing materials, the leading edge shoulder can be the low-frequency region of the relaxation peak.

[0329] As an example, the sensing circuit can be exposed to approximately 11.36% by volume CH4 and 1090 ppm CO. As shown in Figures A and B, the second sensing element (e.g., a CO sensor) detects an increase in impedance in the presence of CO as shown in the first section 1810, but the first sensing element (e.g., a CH4 sensor) only indicates the minimum increase in impedance in the presence of CO. Similarly, the second sensing element detects an increase in impedance in the presence of CO as shown in the third section 1814, but the first sensing element only shows the minimum increase. Alternatively, the first sensing element detects an increase in impedance in the presence of CH4 as shown in the second section 1812, but the second sensing element only shows the minimum increase. Figures A and B illustrate the distinction between CH4 and CO by the first and second sensing elements of the sensing circuit.

[0330] Return to Figure 26At (1706), electrical responses at multiple frequencies received from one or more sensing elements are converted into analytically useful concentrations of the analyte gas. For example, the management circuitry and / or data analysis unit of the multi-gas sensing system 1400 can analyze the electrical responses received from the sensing elements to determine one or more concentrations of the one or more sensed analyte gases. The analysis can be based on one or more electrical responses of the sensing elements; characteristics of the sensing circuit, such as, but not limited to, the temperature of the sensing elements; the state of the sensing circuit based on the construction of the sensing elements; environmental conditions near the sensing circuit; or any combination of two or more of these. In one or more embodiments, the analysis can be based on one or more sensing elements operating at periodically variable temperatures, one or more sensing elements operating at common or unique substantially constant temperatures, different discrete frequencies or frequency ranges used to excite the sensing elements, etc.

[0331] For example, Figure 28 It shows Figure 27 The diagram illustrates the results of the analysis data of the electrical response of the two sensing elements in the multi-gas sensing system shown.

[0332] One or more different statistical analysis tools can be used to evaluate the electrical response, such as principal component analysis (PCA) of the electrical response and other characteristics obtained from the system controller. Alternatively, the concentrations of one or more gases can be calculated from a multivariate transfer function, which can be constructed based on the electrical response to the AC current of the management system, the temperature of the sensing element, the state of the resistor-capacitor configuration of the sensing element, information from the sensing circuitry or other sensors regarding environmental conditions surrounding the multi-gas sensing system, etc. Alternatively, alternative statistical analyses can be used to evaluate the data obtained from the system controller.

[0333] Chart A shows the results of the analysis data of the combined electrical response using PCA and expressed as the fraction of principal component #1 as a function of experimental time.

[0334] Chart B shows the results of the analysis data of the combined electrical response using PCA and expressed as the fraction of principal component #2 as a function of experimental time.

[0335] Charts A and B are shown as having a common horizontal axis 1902 representing the experimental time and vertical axes 1904 and 1906 representing the linear scales of principal components #1 and #2 of the developed PCA classification, respectively.

[0336] As shown in Table A, the first section 1910 and the third section 1914 indicate increased CO concentration, and the second section 1912 indicates increased CH4 concentration. For example, the first and third sections indicate the increase in CO concentration. Figure 27The PCA principal component #1 response of CO gas (e.g., sections 1810, 1814 of Figure B), and the second section indicates the response to... Figure 27 The PCA principal component #1 response of CH4 gas (e.g., section 1812 of Figure A).

[0337] As shown in Table B, the first section 1910 and the third section 1914 indicate increased CO concentration, and the second section 1912 indicates increased CH4 concentration. For example, the first section 1910 and the third section 1914 indicate the increase in CO concentration. Figure 27 The PCA principal component #2 response of CO gas (e.g., sections 1810, 1814 of Figure B), and the second section 1912 indicates the response to... Figure 27 The PCA principal component #2 response of CH4 gas (e.g., section 1812 of Figure A).

[0338] In one or more embodiments, one or more processors of the system controller may provide baseline correction for the sensing element. Baseline correction may be performed periodically, at scheduled intervals (e.g., after a certain number of minutes, hours, days, years, etc.). Baseline correction may also be referred to as calibration of the sensing element. The amount of correction, or the method of correcting or verifying the baseline, may be based on the electrical response received from the sensing element, the temperature of the sensing element, the state of the resistor-capacitor configuration of the sensing element, information about environmental conditions surrounding or near the multi-gas sensing system (e.g., ambient temperature, humidity, pressure, etc.), information received from other sensors or sensing devices, information wirelessly transmitted to the multi-gas sensing system (e.g., from a workstation separate from the multi-gas sensing system), information or protocols stored within the multi-gas sensing system, etc.

[0339] Optionally, one or more processors can vary the selectivity, sensitivity, or linearity of the electrical response of the multi-gas sensing system 1400 to allow the system to be more sensitive to one analyte gas than another at different times or under different operating conditions. In one or more embodiments, one or more processors can dynamically vary the selectivity, sensitivity, or linearity such that one or more processors can vary one or more of the selectivity, sensitivity, or linearity while the sensing system is operating. Optionally, one or more processors can vary one or more of the selectivity, sensitivity, or linearity of the electrical response of the sensing system when the system is not sensing. For example, one or more processors can determine the relaxation region of the impedance response of the sensing circuit. Both the real part and the imaginary part of impedance have relaxation regions. As an example, this relaxation region can be determined by examining the real part of the measured impedance of the sensing material 1508 according to frequency to locate where the real part of the impedance changes from a high impedance value with essentially zero slope at low frequencies to a decreasing impedance value with a relatively high slope at higher frequencies and a decreasing impedance value with a relatively low slope at even higher frequencies, as well as where the impedance value is close to zero at the highest frequency.

[0340] One or more processors can determine the location of the relaxation peak in the relaxation region of the imaginary part of the sensor impedance by identifying the inflection point frequency of the sensing circuit 1500. The inflection point frequency can be determined as the frequency of the current associated with the inflection point.

[0341] One or more processors can determine a frequency range for sensor operation that is below and above the relaxation peak of the imaginary part of the sensor impedance, and at or near the relaxation peak of the imaginary part of the sensor impedance (e.g., within 11%, within 3%, within 5%, or within 110% in different embodiments). Current can be applied to the sensing material 1508 via the sensing electrodes 1510, 1512 of one or more sensing elements only at frequencies greater than the inflection point frequency and / or within a frequency range greater than the inflection point frequency. Operating the sensing circuit 1500 at these frequencies can improve the selective sensing of one or more analytes of interest in a second sample relative to one or more other analytes (and relative to operating the sensing circuit 1500 at or below the inflection point frequency). The sensitivity of the sensing circuit 1500 includes the measurement of the sensor response signal per unit of analyte concentration.

[0342] As another example, one or more processors can selectively sense at least one analyte of interest by utilizing improved interference suppression. The resistive and capacitive properties of the sensing circuit 1500 are measured during exposure to a first gas sample and during exposure to a second gas sample. One or more processors determine the capacitance value or range of capacitance values ​​of one or more passive electrical components (e.g., capacitive elements) to vary the capacitance of one or more sensing elements of the sensing circuit 1500 to match the frequency range or discrete frequency response of the system controller within the dielectric relaxation region of the sensing circuit 1500. Varying the capacitance of the sensing circuit 1500 coupled to the system controller allows the system controller to selectively sense the analyte of interest (e.g., methane, ethane, another hydrocarbon, hydrogen, carbon monoxide, etc.) by utilizing interference suppression.

[0343] Selective sensing of one or more analytes of interest is performed using sensing circuitry 1500, which operates within the dielectric relaxation region of sensing circuitry, to match the discrete frequency response or frequency response range of system controller 1420. For example, the sensing material 1508 of each sensing element of sensing circuitry 1500 may be exposed to a gas sample in which one or more analytes of interest may potentially be present. System controller 1420 may transmit control signals to management circuitry 1410 to direct management circuitry 1410 to apply alternating current to sensing material 1508 via sensing electrodes 1510, 1512 within a specified frequency response range or at a specified discrete frequency of system controller 1420 within the dielectric relaxation region of sensing circuitry 1500. Operating sensing circuitry 1500 at these frequencies can increase the selective sensing of one or more analytes of interest in a sample (e.g., the sensing sensitivity of multi-gas sensing system 1400) relative to one or more other analytes (and relative to operating sensing circuitry 1500 at different frequencies or different frequency ranges of system controller 1420). The sensitivity of the sensing circuit 1500 includes the measurement sensor response signal per unit of analyte concentration.

[0344] Return to Figure 26 The process determines whether the resistor-capacitor configuration of one of the sensing elements needs to be changed. If the configuration does need to be changed, the procedure proceeds to (1712), where the management circuitry changes the resistor-capacitor configuration of one or more sensing elements. The procedure then returns to (1702A-C), where the procedure restarts. Alternatively, if no resistor-capacitor configuration of any sensing element needs to be changed, the procedure moves to (1714).

[0345] At (1714), it is determined whether the amount of at least one gas exceeds a predetermined threshold. For example, the system controller may determine, based on the analysis performed in steps (1704) to (1708), that there is a gas amount exceeding the predetermined threshold and that the concentration of that gas may be hazardous to the operator or user of the multi-gas sensing system. Optionally, the gas concentration may be hazardous to the operator performing a specific task, such as, but not limited to, driving or operating motorized equipment, using inflammatory equipment, or remaining in the environment without wearing appropriate safety equipment. In one or more embodiments, it may be determined whether any amount of a particular gas is present. For example, any trace or minimal amount of a particular gas may be hazardous to the operator continuing to operate or remaining in the environment.

[0346] In one or more embodiments, one or more processors of the system controller can determine the asset's response action based on the electrical response of the multi-gas sensing system. For example, the system controller can determine at (1714) whether the concentration of at least one gas analyte exceeds a predetermined threshold.

[0347] If the amount or concentration of the gas analyte does not exceed a predetermined threshold, the procedure returns to (1702), and the procedure repeats for a predetermined amount of time while the operator remains in the environment until the operator disables the multi-gas sensing system, etc. Alternatively, if the amount or concentration of the gas exceeds a predetermined threshold, the procedure proceeds to (1716). At (1716), a notification is sent at least to the controller or other system that integrates the multi-gas sensing system.

[0348] Figure 29 A diagram illustrating the response of a metal oxide sensing element to a gas of interest, such as methane, according to an experiment is shown. In this experiment, the sensing element is a surface-mount ceramic package structure with an integrated heater formed on a silicon substrate and a metal oxide semiconductor material layer formed on the sensing chip using microelectromechanical systems (MEMS) technology. The sensing element requires only about 15 mW of heater power consumption. In this experiment, methane was presented to the sensing element at concentrations of 1087 ppm, 2174 ppm, 3261 ppm, 4348 ppm, 5435 ppm, 6522 ppm, 7609 ppm, and 8696 ppm.

[0349] Charts A, B, and C are shown with a common horizontal axis 2002 representing the experimental time. Chart A is shown with a vertical axis 2004 representing resistance, and charts B and C are shown with vertical axes 2006 and 2008 representing impedance, respectively. Figure 29Graph A depicts the electrical response of the sensing element as measured by conventional resistance. The resistive response of the sensing element to methane concentration is nonlinear. Additionally, the sensitivity decreases with increasing methane gas concentration. Graphs B and C show the electrical response of the sensing element as measured by a dielectric excitation method. The results shown in Graph B were obtained using a benchtop impedance analyzer. The results shown in Graph C were obtained using an integrated circuit impedance analyzer. The very similarity in response linearity and noise levels in Graphs B and C indicates that the mass of methane sensed using an integrated circuit impedance analyzer is approximately the same as that sensed using a benchtop impedance analyzer.

[0350] The developed sensor system can measure the electrical response of a sensing element in response to an alternating current applied to the sensing element at one or more different frequencies and / or one or more different resistor-capacitor configurations. To quantify the gas of interest over a wide concentration range using the linear sensor response and its desired resolution, a dielectric excitation method can be applied at several frequencies. Figure 30 The graphs (Figures A, B, and C) show the responses of three measurement sensors at three frequencies ranging from relatively high to medium and to relatively low frequencies. Figures A, B, and C are shown with a common horizontal axis 2102 representing the experimental time and vertical axes 2104, 2106, and 2108 representing the impedance.

[0351] While the response can be measured at all three frequencies of the measurement system, the calibration curve can be started at the highest frequency to determine the gas concentration. If the sensor response is above approximately the bottom 20% of the sensor response at that frequency (e.g., sensor response #1), a linear calibration curve at that frequency can be observed and correlated with the gas concentration (Figure A). If the sensor response is below the bottom 20% of the sensor response at that frequency (e.g., sensor responses #2 and #3), detection can be switched to a gas concentration ten times lower by using a linear calibration curve at a lower frequency and correlating the sensor response with the gas concentration (e.g., sensor response #2, as shown in Figure B). If sensor response 3 is below approximately 10% of the sensor response at that frequency, detection can be further switched to a gas concentration ten times lower, and the corresponding calibration curve can be used (e.g., Figure C). Therefore, these sensor responses at different frequencies allow for high-resolution determination of gas concentrations over a wide range of gas concentrations using linear responses.

[0352] Another experiment showed that variable air humidity affects the response of conventional chemiluminescence sensors based on metal oxide sensing materials by altering their baseline and gas sensitivity. For example, Figure 31The effects of water vapor in the range of 0–80% relative humidity (RH) on the resistivity and impedance (dielectric response) of ethanol (as model vapor) at concentrations of 4, 8, 12, 16, and 20 ppm are shown. Graphs A and B are shown with a common horizontal axis 2202 representing the experimental time. Graph A is shown with a vertical axis 2204 representing resistance, and Graph B is shown with a vertical axis 2206 representing impedance.

[0353] With increasing RH, the resistance response exhibits a known significant baseline decrease and a reduction in gas sensitivity (Figure A). Meanwhile, dielectric excitation and impedance measurement offer three advantages over resistance measurement (shown in Figure B). First, the response baseline is less affected by humidity changes. Second, sensor sensitivity can increase with increasing RH. Third, response linearity can be improved in the presence of water vapor.

[0354] In another experiment, the response of the multi-gas monitor to methane gas was measured outdoors under dynamic field conditions. Figure 32 Graphical results of monitoring a dynamic methane plume outdoors using a developed multi-gas monitor are shown. Time is on the horizontal axis 2302, and impedance is on the vertical axis 2304. Uncontrolled wind conditions can produce response patterns for the monitor that can be affected by variable wind direction and speed. Therefore, the detected gas concentration can be the result of a convolution between variable wind direction and speed. Thus, this result can provide knowledge about the maximum gas concentration reaching the detector at a given time.

[0355] In another experiment, the responses of a multi-gas sensor were measured to monitor the responses of H2 and CH4. Figure 33 The graphical results of these measurements are shown. In particular, Figure 33 The response speeds for H2 and CH4 detection using a multi-gas sensor according to one or more exemplary aspects of this disclosure are depicted. In the top graph (Graph A), H2 sensor data is collected every 15 seconds, and one or two data points are required to achieve a 90% sensor-balanced response for H2. In the bottom graph (Graph B), CH4 sensor data is collected every 5 seconds, and one data point is required to achieve a 90% sensor-balanced response for CH4.

[0356] In tests using H2, sensor data was collected every 15 seconds (Figure A), and it was observed that the multi-gas sensor required only one or two data points to achieve its 90% equilibrium response to increased H2 concentration. However, the response to CH4 was even faster. Sensor data for CH4 was collected every 5 seconds (Figure B), and it was observed that the multi-gas sensor required only one data point to achieve its 90% equilibrium response to increased CH4 concentration.

[0357] Figure 34 The results depict the detection of three gases, H2, CH4, and CO, at their relevant high concentrations associated with SOFC monitoring. Specifically, refer to... Figure 34 The excitation parameters (also known as variable control parameters) are identified from the multi-gas sensor to detect and quantify H2, CO and CH4 gases using a single multi-gas sensor. Figure 34 The quantitative results for H2, CO, and CH4 gases using a single multi-gas sensor are shown. Figure 34 Charts A, B, and C depict the three steady-state responses of a single multi-gas sensor to three gases, recorded at different excitation frequencies (also known as variable control parameters). The dashed horizontal lines highlight the different response patterns to the three gases at the three frequencies. Furthermore, machine learning tools, such as Support Vector Machines (SVMs), were applied to cross-validate the quantification of H2, CO, and CH4 gases using this multi-gas sensor, as shown in Charts D, E, and F.

[0358] In one or more embodiments of the subject matter described herein, a multi-gas sensing system includes sensing circuitry comprising one or more sensing elements. Each of the one or more sensing elements includes a sensing material configured to detect at least one gaseous analyte. Management circuitry is configured to excite the one or more sensing elements using an alternating current at at least one predetermined frequency. In response to exciting the one or more sensing elements using an alternating current at at least one predetermined frequency, the management circuitry measures one or more electrical responses of the one or more sensing elements. The management circuitry determines one or more characteristics of the sensing circuitry. One or more processors receive the one or more electrical responses of the one or more sensing elements and the one or more characteristics of the sensing circuitry. Based on the one or more electrical responses of the one or more sensing elements and the one or more characteristics of the sensing circuitry, the one or more processors determine the concentration of at least one gaseous analyte.

[0359] This written description uses examples to disclose this disclosure, including best practices, and also enables any person skilled in the art to practice this disclosure, including making and using any device or system and methods of making any combination. The patent scope of this disclosure is defined by the claims, but may include other examples that would occur to a person skilled in the art. Such other examples are intended to fall within the scope of the claims if they include structural elements that are not indistinguishable from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims.

[0360] Further aspects are provided by the subject matter of the following clauses:

[0361] A propulsion system includes: a thruster; a turbine operable to drive the thruster to generate thrust during operation; a fuel cell assembly configured to add power to the thruster, the turbine, or both; and a multi-gas sensor operable in conjunction with the turbine, the fuel cell assembly, or both for sensing gas composition data of fluid flows into or to the turbine, the fuel cell assembly, or both, the gas composition data including data indicating at least two gases and their concentrations.

[0362] The propulsion system according to any one of the foregoing clauses, wherein the turbine includes a combustion section with a burner, wherein the fuel cell assembly includes a fuel cell stack with a fuel cell, the fuel cell defining an outlet positioned to remove output products from the fuel cell and supply the output products to the burner.

[0363] The propulsion system according to any one of the foregoing clauses, wherein the fluid flow is the output product flow from the fuel cell.

[0364] The propulsion system according to any one of the foregoing clauses, wherein the fuel cell assembly includes a fuel processing unit, and wherein the fluid flow is a fuel processing unit flow from the fuel processing unit.

[0365] The propulsion system according to any one of the foregoing clauses, wherein the fuel cell assembly further includes a fuel cell stack having fuel cells, wherein the fuel processing unit flow is provided to the fuel cells.

[0366] The propulsion system according to any one of the foregoing clauses, wherein the fuel cell assembly includes a fuel cell stack and a housing portion that at least partially surrounds the fuel cell stack, wherein the fluid flow is air within the housing portion.

[0367] The propulsion system according to any one of the foregoing clauses further includes: a fuel delivery assembly, wherein the turbine includes a combustion section having a combustor, wherein the fuel delivery assembly is configured to provide a fuel flow to the combustion section, and wherein the fluid flow is the fuel flow provided to the combustor.

[0368] The propulsion system according to any one of the foregoing clauses, wherein the propulsion system is an aerospace propulsion system, and wherein the multi-gas sensor is configured to sense gas composition data of the fluid flow into or to the turbine, the fuel cell assembly, or both during flight operation of the propulsion system.

[0369] The propulsion system according to any one of the foregoing clauses, wherein the multi-gas sensor is located within the environment of the turbine, the fuel cell assembly, or both, which has a temperature of at least 400 degrees Celsius and up to 1000 degrees Celsius during normal operating conditions of the propulsion system.

[0370] The propulsion system according to any one of the foregoing clauses, wherein the at least two gases and their concentrations include two or more of the following: H2, CO, CO2, CH4, H2O, N2, NH3, non-volatile particulate matter, and volatile particulate matter.

[0371] The propulsion system according to any one of the foregoing clauses, wherein the multi-gas sensor weighs less than about 50 grams and has a size less than the following: a length of less than about 20 mm multiplied by a width of less than about 20 mm multiplied by a thickness of less than about 20 mm.

[0372] The propulsion system according to any one of the foregoing clauses, wherein the propulsion system includes a fluid pipeline through which fluid flow into or to the turbine, the fuel cell assembly, or both is provided, and wherein the multi-gas sensor is positioned aligned with the fluid pipeline.

[0373] The propulsion system according to any one of the foregoing clauses, wherein the turbine includes a housing, and wherein the multi-gas sensor is located within the housing of the turbine.

[0374] The propulsion system according to any one of the foregoing clauses, wherein the multi-gas sensor is located within the environment of the turbine, the fuel cell assembly, or both, which has a temperature of at least 200 degrees Celsius during normal operating conditions of the propulsion system.

[0375] The propulsion system according to any one of the foregoing clauses, wherein the propulsion system further includes a fluid pipeline through which the fluid flow into or to the turbine, the fuel cell assembly, or both is provided, and wherein the multi-gas sensor is not separated from the fluid pipeline.

[0376] The propulsion system according to any one of the foregoing clauses, wherein the multi-gas sensor comprises: a sensing circuit including one or more sensing elements; a management circuit configured to excite the one or more sensing elements with an alternating current at a certain frequency, the management circuit being configured to measure one or more electrical responses of the one or more sensing elements in response to exciting the sensing elements with the alternating current at the frequency, the management circuit being configured to determine one or more characteristics of the sensing circuit; and one or more processors configured to receive the one or more electrical responses of the one or more sensing elements and the one or more characteristics of the sensing circuit, wherein the one or more processors are further configured to determine the gas composition data based on the one or more electrical responses of the one or more sensing elements and the one or more characteristics of the sensing circuit.

[0377] In a propulsion system according to any one of the foregoing clauses, the gas composition data is the type and concentration of the gas.

[0378] The propulsion system according to any one of the foregoing clauses, wherein the gas composition data is provided in real time during operation of the propulsion system according to one or more of these clauses.

[0379] The propulsion system according to any one of the foregoing clauses, wherein the multi-gas sensor comprises: a sensing circuit including one or more sensing elements; a management circuit configured to excite the one or more sensing elements using variable control parameters, the management circuit being configured to measure one or more electrical responses of the one or more sensing elements in response to exciting the sensing elements using the variable control parameters, the management circuit being configured to determine one or more characteristics of the sensing circuit; and one or more processors configured to receive the one or more electrical responses of the one or more sensing elements and the one or more characteristics of the sensing circuit, wherein the one or more processors are further configured to determine the gas composition data based on the one or more electrical responses of the one or more sensing elements and the one or more characteristics of the sensing circuit.

[0380] A method of operating a propulsion system, the method comprising: receiving from a multi-gas sensor gas composition data of a fluid flow into or to a turbine of the propulsion system, a fuel cell assembly of the propulsion system, or both, the gas composition data including data indicating at least two gas components; and controlling the operation of the fuel cell assembly, a gas turbine engine including the turbine, or both, in response to the gas composition data received from the multi-gas sensor.

[0381] A method for operating a propulsion system, the propulsion system including a gas turbine engine and a fuel cell assembly, the method comprising operating the propulsion system to generate thrust for a vehicle; simultaneously operating the propulsion system, receiving gas composition data from multiple gas sensors of one or more fluid flows flowing into or to the gas turbine engine, the fuel cell assembly, or both; and, in response to the received gas composition data, determining a health indicator for the gas turbine engine, the fuel cell assembly, or both.

[0382] The method according to any one of the foregoing clauses further includes: receiving data indicating operating parameters of the propulsion system; wherein determining the health indicator includes detecting an anomaly, wherein detecting the anomaly includes comparing the received gas composition data with the received operating parameters.

[0383] The method according to any one of the foregoing clauses, wherein detecting the anomaly includes detecting an initial anomaly, wherein receiving gas composition data of one or more fluid flows flowing into or to the gas turbine engine, the fuel cell assembly, or both from the multi-gas sensor includes receiving gas composition data of one or more fluid flows flowing into or to the gas turbine engine, the fuel cell assembly, or both from the multi-gas sensor at a time resolution of one minute or less, and wherein the method further includes: modifying the operation of the gas turbine engine, the fuel cell assembly, or both in response to the gas composition data of the one or more fluid flows to mitigate the effects of the initial anomaly.

[0384] The method according to any one of the foregoing clauses, wherein determining the health indicator further includes determining the type of abnormality, determining the affected portion, or both.

[0385] The method according to any one of the foregoing clauses, wherein the anomaly type is carbon deposition in the fuel processing unit of the fuel cell assembly, catalyst poisoning in the fuel processing unit, catalyst oxidation in the fuel processing unit, carbon deposition in the fuel cell of the fuel cell assembly, carbon deposition in the combustor of the gas turbine engine, fuel cell leakage, anodizing, or a combination thereof.

[0386] The method according to any one of the foregoing clauses, wherein determining the health indicator of the gas turbine engine, the fuel cell assembly, or both includes determining system health parameters.

[0387] The method according to any one of the foregoing clauses further includes: providing maintenance guidance based on the system health parameters.

[0388] The method described according to one or more of these terms, wherein determining the health indicator includes detecting component failure.

[0389] The method according to any one of the foregoing clauses, wherein determining the health indicator of the gas turbine engine, the fuel cell assembly, or both includes determining system health parameters, and wherein the method further includes: modifying the operating parameters of the gas turbine engine, the fuel cell assembly, or both in response to the system health parameters.

[0390] The method according to any one of the foregoing clauses, wherein determining the health indicator includes detecting a component failure, and wherein the method further includes: controlling the operation of the fuel cell assembly, the gas turbine engine, or both in response to detecting the component failure.

[0391] The method according to any one of the foregoing clauses, wherein the multi-gas sensor comprises: a sensing circuit including one or more sensing elements; a management circuit configured to excite the one or more sensing elements with an alternating current at a certain frequency, the management circuit being configured to measure one or more electrical responses of the one or more sensing elements in response to exciting the sensing elements with the alternating current at the frequency, the management circuit being configured to determine one or more characteristics of the sensing circuit; and one or more processors configured to receive the one or more electrical responses of the one or more sensing elements and the one or more characteristics of the sensing circuit, wherein the one or more processors are further configured to determine data of one or more fluid flows based on the one or more electrical responses of the one or more sensing elements and the one or more characteristics of the sensing circuit.

[0392] A control system for a propulsion system having a gas turbine engine and a fuel cell assembly, the control system comprising: multiple gas sensors; and a controller including one or more processors and a memory, the memory storing instructions configured to control one or more operations of the propulsion system when executed by the one or more processors, the memory including: a data collection module configured to receive data indicating gas composition data of one or more fluid flows flowing into or to the gas turbine engine, the fuel cell assembly, or both during operation of the propulsion system; and an inference module configured to determine a health indicator of the gas turbine engine, the fuel cell assembly, or both in response to the gas composition data received from the data collection module.

[0393] The control system according to any one of the foregoing clauses, wherein the memory further includes: a reporting module configured to provide reporting information in response to the determined health indicator.

[0394] The control system according to any one of the foregoing clauses, wherein the memory further includes: a maintenance service module configured to provide maintenance guidance in response to the determined health indicator.

[0395] The control system according to any one of the foregoing clauses, wherein the memory further comprises: a control module configured to modify operating parameters of the fuel cell assembly, the gas turbine engine, or both in response to a determined health indicator.

[0396] A propulsion system includes: a gas turbine engine including a combustion section having a combustor; and a modular fuel cell assembly including a first fuel cell string including a first processing unit and a first fuel cell stack including a first fuel cell defining an outlet configured to provide output products from the first fuel cell to the combustor; and a second fuel cell string including a second processing unit and a second fuel cell stack including a second fuel cell defining an outlet configured to provide output products from the second fuel cell to the combustor.

[0397] The propulsion system according to any one of the foregoing clauses further includes: a control system comprising one or more sensors configured to sense gas composition data of a first fluid flow through the first fuel cell string and gas composition data of a second fluid flow through the second fuel cell string.

[0398] The propulsion system according to any one of the foregoing clauses, wherein the control system further includes a controller, wherein the controller is configured to receive gas composition data of a first fluid flow through the first fuel cell string and gas composition data of a second fluid flow through the second fuel cell string; and to modify operating parameters of the first fuel cell string, the second fuel cell string, or both in response to the received gas composition data.

[0399] The propulsion system according to any one of the foregoing clauses, wherein the one or more sensors include a first sensor and a second sensor, the first sensor being positioned aligned with the first fuel cell string and the second sensor being positioned aligned with the second fuel cell string.

[0400] The propulsion system according to any one of the foregoing clauses, wherein the one or more sensors include one or more multi-gas sensors.

[0401] The propulsion system according to any one of the foregoing clauses, wherein the one or more sensors include a multi-gas sensor configured to sample the first fluid flow through the first fuel cell string and the second fluid flow through the second fuel cell string.

[0402] The propulsion system according to any one of the foregoing clauses, wherein the one or more sensors are configured to sense the gas composition data of the first fluid flow through the first fuel cell string at a location downstream of the first processing unit and upstream of the first fuel cell stack, and the gas composition data of the second fluid flow through the second fuel cell string at a location downstream of the second processing unit and upstream of the second fuel cell stack.

[0403] The propulsion system according to any one of the foregoing clauses, wherein the one or more sensors are configured to sense gas composition data of the first fluid flow through the first fuel cell string at a location downstream of the first fuel cell stack, and gas composition data of the second fluid flow through the second fuel cell string at a location downstream of the second fuel cell stack.

[0404] The propulsion system according to any one of the foregoing clauses, wherein the modular fuel cell assembly further includes a third fuel cell string.

[0405] In any of the preceding clauses, the propulsion system wherein the first fuel cell string is independently controllable relative to the second fuel cell string.

[0406] The propulsion system according to any one of the foregoing clauses, wherein the first fluid flow through the first fuel cell string is independently controllable relative to the second fluid flow through the second fuel cell string.

[0407] The propulsion system according to any one of the foregoing clauses, wherein the first fuel cell string and the second fuel cell string are independently connected within the gas turbine engine.

[0408] A method of operating a propulsion system, the propulsion system including a modular fuel cell assembly and a gas turbine engine, the method comprising: providing output products from a first fuel cell of a first fuel cell string of the modular fuel cell assembly and output products from a second fuel cell of a second fuel cell string of the modular fuel cell assembly to a combustor in a combustion section of the gas turbine engine; receiving gas composition data of a first fluid flow through the first fuel cell string and gas composition data of a second fluid flow through the second fuel cell string; and modifying operating parameters of the first fuel cell string, the second fuel cell string, or both in response to the received gas composition data.

[0409] The method according to any one of the foregoing clauses further includes: receiving operational data of the modular fuel cell assembly, the gas turbine engine, an aircraft including the modular fuel cell assembly and the gas turbine engine, or a combination thereof, and wherein modifying the operational parameters includes modifying the operational parameters of the first fuel cell string, the second fuel cell string, or both in response to the received gas composition data and the received operational data.

[0410] The method according to any one of the foregoing clauses, wherein the operational data includes: a health indicator of the fuel cell assembly, the gas turbine engine, or both; a flight plan of the aircraft including the fuel cell assembly and the gas turbine engine; a maintenance plan of the aircraft; or a combination thereof.

[0411] In any of the preceding clauses, the health indicator of the fuel cell assembly, the gas turbine engine, or both includes accumulated health information.

[0412] The method according to any one of the foregoing clauses, wherein modifying the operating parameters includes determining that a component of the first fuel cell string exceeds a health threshold; and in response to determining that the component of the first fuel cell string exceeds the health threshold, increasing the power output of the first fuel cell string.

[0413] The method according to any one of the foregoing clauses, wherein modifying the operating parameters includes detecting an anomaly within the fuel cell assembly; and in response to detecting the anomaly within the fuel cell assembly, reducing the power output of the first fuel cell string.

[0414] The method according to any one of the foregoing clauses, wherein detecting the anomaly within the fuel cell assembly includes detecting the anomaly within the first fuel cell string.

[0415] The method according to any one of the foregoing clauses, wherein receiving the gas composition data of the first fluid flow through the first fuel cell string and the gas composition data of the second fluid flow through the second fuel cell string includes receiving the gas composition data from one or more gas sensors.

[0416] The method according to any one of the foregoing clauses, wherein the one or more gas sensors include one or more multi-gas sensors.

[0417] A method of operating a propulsion system having a gas turbine engine and a fuel cell assembly, the fuel cell assembly including a fuel cell, the method comprising: receiving gas composition data of the output products of the fuel cell; and controlling the operation of the fuel cell assembly, the gas turbine engine, or both in response to the received gas composition data of the output products of the fuel cell.

[0418] The method according to any one of the foregoing clauses further includes: operating the propulsion system during flight operations; wherein receiving gas composition data from the output products of the fuel cell includes receiving gas composition data from the output products of the fuel cell while operating the propulsion system during the flight operations.

[0419] The method according to any one of the foregoing clauses, wherein receiving gas composition data from the output products of the fuel cell further comprises sensing the composition data from the output products of the fuel cell at a time resolution of ten minutes or less.

[0420] The method according to any one of the foregoing clauses, wherein receiving gas composition data from the output products of the fuel cell further comprises sensing composition data from the output products of the fuel cell at a time resolution of one minute or less.

[0421] The method according to any one of the foregoing clauses, wherein controlling the operation of the fuel cell assembly, the gas turbine engine, or both includes controlling the operation of the fuel cell assembly.

[0422] The method according to any one of the foregoing clauses, wherein controlling the operation of the fuel cell assembly includes modifying the operating parameters of the fuel cell assembly in response to received gas composition data of the output products from the fuel cell.

[0423] The method according to any one of the foregoing clauses, wherein the operating parameters include: fuel flow rate to the fuel cell assembly, fuel pressure, equivalence ratio of the fuel processing unit of the fuel cell assembly, steam carbon ratio of the fuel processing unit of the fuel cell assembly, air pressure, air flow rate, pressure difference from anode to cathode, anode inlet temperature, cathode inlet temperature, fuel cell stack temperature, fuel cell current, fuel cell utilization rate, fuel cell air utilization rate, or a combination thereof.

[0424] The method according to any one of the foregoing clauses, wherein controlling the operation of the fuel cell assembly, the gas turbine engine, or both includes controlling the gas turbine engine.

[0425] The method according to any one of the foregoing clauses, wherein controlling the operation of the gas turbine engine includes modifying the operating parameters of the gas turbine engine in response to received gas composition data of the output products from the fuel cell.

[0426] According to any one of the preceding clauses, the operating parameters of the gas turbine engine include: burner fuel flow rate, burner fuel-air ratio, fuel flow rate ratio between burner fuel flow and fuel cell fuel flow, variable exhaust valve, variable guide vane, low-pressure shaft speed, high-pressure shaft speed, variable fan nozzle, engine-driven generator output, or a combination thereof.

[0427] The method according to any one of the foregoing clauses, wherein receiving the gas composition data includes receiving the gas composition data from a gas sensor, and wherein controlling the operation of the fuel cell assembly, the gas turbine engine, or both in response to the received composition data includes: using model-based control to control the operation of the fuel cell assembly, the gas turbine engine, or both, and wherein using the model-based control includes: using a model to determine estimated gas composition data; and using a fusion filter to determine actual gas composition data based on the determined estimated gas composition data and the received gas composition data.

[0428] The method according to any one of the foregoing clauses further includes: calibrating the model in response to the received gas composition data.

[0429] The method according to any one of the foregoing clauses further includes: detecting a fault in the gas sensor based on the determined estimated gas composition data.

[0430] The method according to any one of the foregoing clauses, wherein the gas composition data of the output product includes the percentage of hydrogen in the output product.

[0431] A propulsion system includes: a gas turbine engine including a combustion section having a combustor; a fuel cell assembly including a fuel cell stack having a fuel cell defining an outlet configured to provide output products from the fuel cell to the combustor; and a control system including a gas sensor positioned to determine gas composition data of the output products at locations downstream of the fuel cell and upstream of the combustor, the control system being configured to control operation of the fuel cell assembly, the gas turbine engine, or both, in response to the determined gas composition data of the output products from the fuel cell.

[0432] The propulsion system according to any one of the foregoing clauses, wherein the control system is further configured to determine the gas composition data of the output products from the fuel cell while operating the propulsion system during flight operations.

[0433] The propulsion system according to any one of the foregoing clauses, wherein the control system is configured to determine the gas composition data from the output products of the fuel cell at a time resolution of one minute or less.

[0434] The propulsion system according to any one of the foregoing clauses, wherein the control system is configured to control the operation of the fuel cell assembly by modifying the operating parameters of the fuel cell assembly, and wherein the operating parameters include: fuel flow rate to the fuel cell assembly, fuel pressure, equivalence ratio of the fuel processing unit of the fuel cell assembly, vapor-to-carbon ratio of the fuel processing unit of the fuel cell assembly, air pressure, air flow rate, pressure difference from anode to cathode, anode inlet temperature, cathode inlet temperature, fuel cell stack temperature, fuel cell current, fuel cell utilization rate, fuel cell air utilization rate, or a combination thereof.

[0435] The propulsion system according to any one of the foregoing clauses, wherein the control system is configured to control the operation of the gas turbine engine by modifying the operating parameters of the gas turbine engine, and wherein the operating parameters include: burner fuel flow rate, burner fuel-air ratio, fuel flow rate ratio between burner fuel flow and fuel cell fuel flow, variable exhaust valve, variable guide vane, low-pressure shaft speed, high-pressure shaft speed, variable fan nozzle, engine-driven generator output, or a combination thereof.

[0436] The propulsion system according to any one of the foregoing clauses, wherein the gas composition data includes the percentage of hydrogen in the output products.

[0437] The method according to any one of the foregoing clauses, wherein receiving gas composition data from the output products of the fuel cell further comprises sensing composition data from the output products of the fuel cell at a time resolution of one second or less.

[0438] The method according to any one of the foregoing clauses, wherein receiving gas composition data from the output products of the fuel cell further comprises using a multi-gas sensor to sense the composition data from the output products of the fuel cell, the multi-gas sensor being operated using variable control parameters.

[0439] The propulsion system according to any one of the foregoing clauses, wherein the one or more multi-gas sensors are located in an environment with a temperature of at least 600 degrees Celsius and up to 1000 degrees Celsius during normal operating conditions of the propulsion system.

[0440] In a propulsion system according to any one of the foregoing clauses, the one or more multi-gas sensors are configured to sense gas composition data having at least two types of gases and their concentrations.

[0441] The propulsion system according to any one of the foregoing clauses, wherein the one or more sensors include one or more multi-gas sensors configured to sense the gas composition data in real time and operate using variable control parameters.

Claims

1. A method of operating a propulsion system having a gas turbine engine and a fuel cell assembly, the fuel cell assembly comprising a fuel cell, characterized in that, The method includes: Receive gas composition data from the output products of the fuel cell; and In response to received gas composition data of the output products from the fuel cell, control the operation of the fuel cell assembly, the gas turbine engine, or both; Receiving the gas composition data includes receiving the gas composition data from a gas sensor, and controlling the operation of the fuel cell assembly, the gas turbine engine, or both in response to the received composition data includes: Using model-based control to control the operation of the fuel cell assembly, the gas turbine engine, or both, and wherein using the model-based control includes: Using the model, the estimated gas composition data were determined; and Using a fusion filter, actual gas composition data is determined based on the estimated gas composition data and the received gas composition data.

2. The method according to claim 1, characterized in that, Further includes: Operate the propulsion system during flight operations. Receiving gas composition data from the output products of the fuel cell includes receiving gas composition data from the output products of the fuel cell while operating the propulsion system during the flight operation.

3. The method according to claim 2, characterized in that, Receiving gas composition data from the output products of the fuel cell further includes sensing the composition data of the output products from the fuel cell at a time resolution of ten minutes or less.

4. The method according to claim 2, characterized in that, Receiving gas composition data from the output products of the fuel cell further includes sensing the composition data of the output products from the fuel cell at a time resolution of one minute or less.

5. The method according to claim 2, characterized in that, Receiving gas composition data from the output products of the fuel cell further includes sensing the composition data of the output products from the fuel cell at a time resolution of one second or less.

6. The method according to claim 1, characterized in that, Receiving gas composition data from the output products of the fuel cell further includes using a multi-gas sensor to sense the composition data from the output products of the fuel cell, the multi-gas sensor being operated using variable control parameters.

7. The method according to claim 1, characterized in that, Controlling the operation of the fuel cell assembly, the gas turbine engine, or both includes controlling the operation of the fuel cell assembly.

8. The method according to claim 7, characterized in that, The operation of controlling the fuel cell assembly includes modifying the operating parameters of the fuel cell assembly in response to received gas composition data of the output products from the fuel cell.

9. The method according to claim 8, characterized in that, The operating parameters mentioned therein include: fuel flow rate to the fuel cell assembly, fuel pressure, equivalence ratio of the fuel processing unit of the fuel cell assembly, steam carbon ratio of the fuel processing unit of the fuel cell assembly, air pressure, air flow rate, pressure difference from anode to cathode, anode inlet temperature, cathode inlet temperature, fuel cell stack temperature, fuel cell current, fuel cell utilization rate, fuel cell air utilization rate, or a combination thereof.

10. The method according to claim 1, characterized in that, The operation of controlling the fuel cell assembly, the gas turbine engine, or both includes controlling the gas turbine engine.

11. The method according to claim 10, characterized in that, The operation of controlling the gas turbine engine includes modifying the operating parameters of the gas turbine engine in response to received gas composition data of the output products from the fuel cell.

12. The method according to claim 11, characterized in that, The operating parameters of the gas turbine engine include: burner fuel flow rate, burner fuel-air ratio, fuel flow rate ratio between burner fuel flow and fuel cell fuel flow, variable exhaust valve, variable guide vane, low-pressure shaft speed, high-pressure shaft speed, variable fan nozzle, engine-driven generator output, or a combination thereof.

13. The method according to claim 1, characterized in that, Further includes: The model is calibrated based on the received gas composition data.

14. The method according to claim 13, characterized in that, Further includes: The model is calibrated in response to the received gas composition data.

15. The method according to claim 14, characterized in that, Further includes: Based on the determined estimated gas composition data, a fault in the gas sensor is detected.

16. The method according to claim 1, characterized in that, The gas composition data of the output product includes the percentage of hydrogen in the output product.

17. A propulsion system, characterized in that, include: A gas turbine engine, the gas turbine engine including a combustion section with a burner; A fuel cell assembly, comprising a fuel cell stack having a fuel cell, the fuel cell defining an outlet configured to provide output products from the fuel cell to the burner; and A control system, comprising a gas sensor positioned to determine gas composition data of the output products at locations downstream of the fuel cell and upstream of the burner, the control system being configured to control the operation of the fuel cell assembly, the gas turbine engine, or both, in response to the determined gas composition data of the output products from the fuel cell. The operation of the fuel cell assembly, the gas turbine engine, or both, in response to received component data includes: Using model-based control to control the operation of the fuel cell assembly, the gas turbine engine, or both, and wherein using the model-based control includes: Using the model, the estimated gas composition data were determined; and Using a fusion filter, actual gas composition data is determined based on the estimated gas composition data and the received gas composition data.

18. The propulsion system according to claim 17, characterized in that, The control system is further configured to determine the gas composition data of the output products from the fuel cell while operating the propulsion system during flight operations.

19. The propulsion system according to claim 18, characterized in that, The control system is configured to determine the gas composition data from the output products of the fuel cell at a time resolution of one minute or less.

20. The propulsion system according to claim 17, characterized in that, The control system is configured to control the operation of the fuel cell assembly by modifying the operating parameters of the fuel cell assembly, and the operating parameters include: fuel flow rate to the fuel cell assembly, fuel pressure, equivalence ratio of the fuel processing unit of the fuel cell assembly, vapor carbon ratio of the fuel processing unit of the fuel cell assembly, air pressure, air flow rate, pressure difference from anode to cathode, anode inlet temperature, cathode inlet temperature, fuel cell stack temperature, fuel cell current, fuel cell utilization rate, fuel cell air utilization rate, or a combination thereof.

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