Peripheral critical fluid system assembly for turbine engine

Abstract

A weekly critical fluid system of a thermal management system associated with a turbine engine may include one or more sensors configured to generate a sensor output corresponding to one or more phase properties of a weekly critical fluid flowing through a cooling circuit of the thermal management system, and a controller configured to control the one or more sensors to generate a sensor output corresponding to one or more phase properties of the weekly critical fluid flowing through the cooling circuit of the thermal management system. The controller is configured to generate a control command based at least in part on the sensor output, the control command being configured to control one or more controllable components of the thermal management system. The one or more sensors may include one or more phase detection sensors, such as acoustic sensors.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is a continuation-in-part of U.S. application No. 17 / 687,960, filed on March 7, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure generally relates to monitoring and controlling the phase properties of pericritical fluids, including supercritical fluids and near-supercritical fluids. More particularly, the present disclosure generally relates to pericritical fluids used in conjunction with engines, such as turbine engines, including thermal management systems and fuel systems using pericritical fluids. Background Art

[0004] Engines such as turbine engines can use pericritical fluids for various purposes. Such pericritical fluids can be used when they exhibit a near supercritical or supercritical phase. For example, the pericritical fluid can be used in a near supercritical or supercritical state to cool various fluid streams or components of the engine. As another example, the engine can use a fuel having a pericritical state (such as a near supercritical or supercritical phase).

[0005] One or more operations of the engine may be affected by the phase of such a circumcritical fluid. For example, the engine may be configured for a circumcritical fluid used in a circumcritical phase (such as in a near-supercritical phase and / or a supercritical phase). Additionally or alternatively, one or more operations of the engine may be affected by changes in one or more phase properties of the circumcritical fluid (such as changes corresponding to phase changes of the circumcritical fluid and / or changes that may occur in the corresponding phase of the circumcritical fluid). BRIEF DESCRIPTION OF THE DRAWINGS

[0006] A complete and enabling disclosure, including the best mode thereof, to one of ordinary skill in the art is set forth in the specification with reference to the accompanying drawings, in which:

[0007] Figure 1 An exemplary power generation system including an engine and a pericritical fluid system is schematically depicted.

[0008] Figure 2A-2E Schematically depicting an exemplary thermal management system that may use or include, for example, Figure 1 A pericritical fluid system in combination with a power generation system and / or an engine.

[0009] Figure 3A and 3B An exemplary fuel system is schematically depicted, which may use or include, for example, Figure 1A pericritical fluid system in combination with a power generation system and / or an engine.

[0010] Figure 4 An exemplary pericritical fluid system is schematically depicted, which may be composed of Figure 2A-2E An exemplary thermal management system uses or includes Figure 2A-2E In an exemplary thermal management system of Figure 3A and 3B An exemplary fuel system for use or included in Figure 3A and 3B In an exemplary fuel system of.

[0011] Figures 5A-5D An exemplary phase diagram of a fluid with respect to temperature and pressure is schematically depicted.

[0012] Figure 5E An exemplary phase diagram of a fluid with respect to pressure and density is schematically depicted.

[0013] Figure 6 An exemplary control system that may be used to perform control operations according to the present disclosure is schematically depicted.

[0014] Figure 7 A flow chart depicting an exemplary method of controlling the phase state of a fluid, such as in conjunction with a thermal management system or a fuel system, is shown.

[0015] Figure 8 is a schematic cross-sectional view of a turbine engine including a steam system according to the present disclosure, taken along a longitudinal centerline axis of the turbine engine.

[0016] Fig. 9 is a schematic diagram of a turbine engine and a steam system with a heat transfer system according to an embodiment of the present disclosure.

[0017] Fig.10 is a schematic diagram of a turbine engine and a steam system with a heat transfer system according to an embodiment of the present disclosure.

[0018] Fig.11 is a schematic diagram of a turbine engine and a steam system with a heat transfer system according to an embodiment of the present disclosure.

[0019] Fig.12 is a schematic diagram of a turbine engine and a steam system with a heat transfer system according to an embodiment of the present disclosure.

[0020] Fig.13 is a schematic diagram of a turbine engine and a steam system with a heat transfer system according to an embodiment of the present disclosure.

[0021] Fig.14is a schematic diagram of a turbine engine and a steam system with a heat transfer system according to an embodiment of the present disclosure.

[0022] Fig.15A is a schematic diagram of a turbine engine and a steam system with a heat transfer system according to an embodiment of the present disclosure.

[0023] Fig. 15B is a schematic diagram of a turbine engine and a steam system with a heat transfer system according to an embodiment of the present disclosure.

[0024] Fig.16 is a schematic diagram of a turbine engine and a steam system with a heat transfer system according to an embodiment of the present disclosure.

[0025] Fig.17 is a schematic diagram of a turbine engine and a steam system with a heat transfer system according to an embodiment of the present disclosure.

[0026] Fig.18 is a schematic diagram of a turbine engine and a steam system with a heat transfer system according to an embodiment of the present disclosure.

[0027] Fig.19 is a schematic diagram of a heat transport system according to an embodiment of the present disclosure.

[0028] Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the present disclosure. DETAILED DESCRIPTION

[0029] Reference will now be made in detail to embodiments of the present disclosure, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation of the present disclosure rather than limitation thereof. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made to the present disclosure without departing from the scope or spirit of the present disclosure. For example, a feature illustrated or described as part of one embodiment may be used together with another embodiment to produce yet another embodiment. Therefore, the present disclosure is intended to encompass such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0030] The word "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 preferred or advantageous over other implementations. Additionally, all embodiments described herein should be considered exemplary unless explicitly stated otherwise.

[0031] As used herein, the terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another, and are not intended to indicate the position or importance of each component.

[0032] The terms "upper", "lower", "right", "left", "vertical", "horizontal", "top", "bottom", "lateral", "longitudinal", etc. should be related to the disclosure as it is oriented in the accompanying drawings. However, it should be understood that the present disclosure can assume various alternative orientations unless expressly indicated to the contrary. It should also be understood that the specific devices shown in the drawings and described in the following specification are merely exemplary embodiments of the present disclosure. Therefore, specific dimensions and other physical characteristics related to the embodiments disclosed herein should not be regarded as limiting.

[0033] The terms "fore" and "aft" refer to relative positions within a turbine engine, with front referring to a position closer to the engine inlet and aft referring to a position closer to the engine nozzle or exhaust.

[0034] The terms "upstream" and "downstream" refer to relative directions relative to the flow of a fluid in a fluid path. For example, "upstream" refers to the direction from which the fluid is flowing, while "downstream" refers to the direction toward which the fluid is flowing.

[0035] The singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

[0036] Unless otherwise specified herein, the terms "coupled," "fixed," "attached to," and the like refer to both direct coupling, fixing, or attachment as well as indirect coupling, fixing, or attachment through one or more intermediate components or features.

[0037] Approximate language used throughout the specification and claims is applied to modify any quantitative representation that can be allowed to vary without causing a change in the basic function to which it is related. Therefore, values ​​modified by terms such as "about", "approximately" and "substantially" are not limited to the precise values ​​specified. In at least some cases, approximate language can correspond to the accuracy of an instrument used to measure a value, or the accuracy of a method or machine used to construct or manufacture a component and / or system. For example, approximate language can refer to within a margin of 1%, 2%, 4%, 10%, 15% or 20%.

[0038] Here and throughout the specification and claims, range limitations are combined and interchanged, and unless context or language indicates otherwise, such ranges are identified and include all sub-ranges contained therein. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.

[0039] The term "at least one" in a context such as "at least one of A, B, and C" means only A, only B, only C, or any combination of A, B, and C.

[0040] Additionally, unless otherwise specified, the terms "low", "high" or their corresponding comparatives (e.g., lower, higher, where applicable) each refer to a relative speed within the engine. For example, a "low-pressure turbine" operates at a pressure that is substantially lower than a "high-pressure turbine". Alternatively, unless otherwise specified, the above terms may be understood in their highest order. For example, a "low-pressure turbine" may refer to the lowest maximum pressure turbine within a turbine section, while a "high-pressure turbine" may refer to the highest maximum pressure turbine within a turbine section.

[0041] The term "turbomachine" refers to a machine that includes a combustor section and a turbine section having one or more turbines that together generate thrust output and / or torque output. In some embodiments, the turbomachine may include a compressor section having one or more compressors that compress air or gas that flows to the combustor section.

[0042] As used herein, the term "turbine engine" refers to an engine that may include a turbine as all or part of its power source. Example turbine engines include gas turbine engines and hybrid electric turbine engines such as turbofan engines, turboprop engines, turbojets, turboshaft engines, etc.

[0043] As used herein, the terms "axial" and "axially" refer to directions and orientations extending substantially parallel to the centerline of the turbine engine. Additionally, the terms "radial" and "radially" refer to directions and orientations extending substantially perpendicular to the centerline of the turbine engine. Additionally, as used herein, the terms "circumferential" and "circumferentially" refer to directions and orientations extending in an arc around the centerline of the turbine engine.

[0044] As used herein, the "bypass ratio" of a turbine engine is the ratio of bypass air passing through the bypass of the turbine engine to the core air passing through the core inlet of the turbine of the turbine engine. For example, the bypass ratio is the ratio of bypass air 62 entering the bypass airflow passage 56 to the core air 64 entering the turbine 16.

[0045] As used herein, the "compression ratio" of a compressor is the ratio of the compressor outlet pressure at the outlet of the compressor to the compressor inlet pressure at the inlet of the compressor. The compressor outlet pressure and the compressor inlet pressure are measured as static air pressures perpendicular to the direction of core air flow through the compressor.

[0046] As used herein, the "pressure expansion ratio" of a turbine is the ratio of the pressure at the inlet of the turbine to the pressure at the outlet of the turbine.

[0047] One or more components of the engine described herein may be manufactured or formed using any suitable process, such as an additive manufacturing process, such as a 3-D printing process. The use of such a process may allow such components to be formed in one piece, as a single integral component, or as any suitable number of subcomponents. In particular, the additive manufacturing process may allow such components to be formed in one piece and include various features that would not be possible using prior manufacturing methods. For example, the additive manufacturing methods described herein may allow the manufacture of channels, ducts, cavities, openings, housings, manifolds, double walls, heat exchangers, or other components having unique features, configurations, thicknesses, materials, densities, fluid pathways, headers, and mounting structures that may be impossible or impractical using prior manufacturing methods, or the specific positioning and integration of such components. Some of these features are described herein.

[0048] Suitable additive manufacturing techniques according to the present disclosure include, for example, selective laser melting (SLM), direct metal laser melting (DMLM), fused deposition modeling (FDM), selective laser sintering (SLS), 3D printing such as by inkjet, laser jetting and binder jetting, stereolithography (SLA), direct selective laser sintering (DSLS), electron beam sintering (EBS), electron beam melting (EBM), laser engineered net shaping (LENS), laser net shape manufacturing (LNSM), direct metal deposition (DMD), digital light processing (DLP), direct selective laser melting (DSLM) and other known processes.

[0049] Suitable powder materials for making the structure provided in this article as an integral single structure include metal alloys, polymers or ceramic powders. Exemplary metal powder materials are stainless steel alloys, cobalt-chromium alloys, aluminum alloys, titanium alloys, nickel-based superalloys and cobalt-based superalloys. In addition, suitable alloys may include those alloys designed to have good oxidation resistance, referred to as "superalloys", which have acceptable strength at the elevated operating temperatures in turbine engines, such as Hastelloy, Inconel alloys (e.g., IN 738, IN 792, IN 939), Rene alloys (e.g., Rene N4, Rene N5, Rene 80, Rene 142, Rene 195), Haynes alloys, Mar M, CM 247, CM 247LC, C263, 718, X-850, ECY 768, 282, X45, PWA 1483 and CMSX (e.g., CMSX-4) single crystal alloys. The fabricated objects of the present disclosure may be formed with one or more selected crystalline microstructures, such as directionally solidified ("DS") or single crystal ("SX").

[0050] As used herein, the terms "integral," "unitary," or "monolithic" used to describe a structure means that the structure is formed integrally from a continuous material or group of materials without seams, connecting joints, etc. The integral, unitary structures described herein may be formed by additive manufacturing to have the structure, or alternatively, by a casting process, etc.

[0051] The present disclosure generally provides systems and methods for monitoring and / or controlling the phase properties of a pericritical fluid, including supercritical fluids and near-supercritical fluids. Such pericritical fluids can be used in conjunction with an engine (such as a turbine engine), for example as a cooling fluid and / or as a fuel. The present disclosure provides a pericritical fluid system that can be used to monitor and / or control one or more phase properties of a pericritical fluid, such as the phase state of the pericritical fluid. In some embodiments, the pericritical fluid system can be used by a thermal management system associated with an engine and / or can be included as part of a thermal management system associated with an engine. The thermal management system can use the pericritical fluid, for example, to cool one or more fluid flows associated with the engine and / or to cool one or more components on the engine. Additionally or alternatively, in some embodiments, the pericritical fluid system can be used by a fuel system associated with an engine and / or can be included as part of a fuel system associated with an engine. The fuel system can use the pericritical fluid as a fuel source for the engine. The pericritical fluid system can include one or more sensors that are configured to generate a sensor output, and the control system can use the sensor output to perform a control operation, such as a control operation associated with the pericritical fluid system. The sensor output may be used to monitor one or more phase properties of the pericritical fluid.The control system may provide control commands to one or more controllable components, for example, to control one or more phase properties of the pericritical fluid.

[0052] According to the present disclosure, one or more sensors used in the pericritical fluid system may include a phase detection sensor, which is configured to generate a sensor output, and the sensor output may be related to one or more phase properties of the pericritical fluid (such as the phase state of the pericritical fluid). In some embodiments, the sensor output from the phase detection sensor can be used to determine one or more phase properties of the fluid. Additionally or alternatively, the sensor output from the phase detection sensor can be used in combination with further sensor outputs from one or more temperature sensors and / or pressure sensors. For example, the sensor output from the phase detection sensor can indicate a change in one or more phase properties of the pericritical fluid, and the sensor output from one or more temperature sensors and / or pressure sensors can be used to associate the change in one or more phase properties of the pericritical fluid with the phase state of the pericritical fluid. In other words, in some embodiments, the sensor output from the phase detection sensor can be used to indicate that some changes in one or more phase properties of the pericritical fluid have occurred, and the sensor output from one or more temperature sensors and / or pressure sensors can be used to associate the change with a specific phase state of the pericritical fluid. Additionally or alternatively, in some embodiments, for example, one or more sensor outputs from a phase detection sensor may be used to determine one or more phase properties of a pericritical fluid, such as the phase state of the pericritical fluid, without reference to other sensor outputs such as from a temperature sensor and / or a pressure sensor.

[0053] As used herein, the term "pericritical fluid" refers to a fluid having a supercritical phase or a near supercritical phase. The term "pericritical fluid" includes fluids that constitute supercritical fluids or near supercritical fluids. When a fluid has a temperature and pressure corresponding to the pericritical phase of the fluid, the fluid can be said to have a pericritical phase.

[0054] As used herein, the term "supercritical fluid" refers to a fluid having a temperature and pressure exceeding the critical point of the fluid. When a fluid has a temperature exceeding the critical temperature of the fluid and a pressure exceeding the critical pressure of the fluid, the fluid can be referred to as having a supercritical phase.

[0055] As used herein, the term "near supercritical fluid" refers to a fluid other than a supercritical fluid having a temperature of at least 70% of the critical temperature of the fluid calculated based on absolute temperature, and a pressure of at least 70% of the critical pressure of the fluid calculated based on absolute pressure. A near supercritical fluid may have a temperature higher than the critical temperature of the fluid and a pressure lower than the critical pressure of the fluid, or a near supercritical fluid may have a pressure higher than the critical pressure of the fluid and a temperature lower than the critical temperature of the fluid. When a fluid has a temperature and pressure corresponding to a near supercritical phase of the fluid, the fluid may be referred to as having a near supercritical phase. A near supercritical fluid may have a liquid phase or a gas phase.

[0056] As used herein, the term "critical temperature" refers to the temperature above which a gas cannot be liquefied by pressure alone. As used herein, the term "critical pressure" refers to the pressure required to liquefy a gas at its critical temperature. As used herein, the term "critical point" with respect to a fluid refers to the point defined by the critical temperature and critical pressure of the fluid.

[0057] As used herein, the term "phase property" refers to the phase state of a fluid, or the physical properties of a fluid that depend on the phase state of a fluid, and includes the phase state of a fluid, or the physical properties of a fluid that depend on the phase state of a fluid. The phase properties of a fluid may be different between different phases, for example, between at least two of the following: a liquid phase, a gas phase, a near supercritical phase, and a supercritical phase. Additionally or alternatively, the phase properties of a fluid may be different between different phases, including between different phases within a given phase. As an example, the physical properties of a fluid that depend on the phase state of a fluid and are covered by the term "phase property" include: density, heat capacity, refractive index, thermal conductivity, viscosity, and thermal expansion coefficient.

[0058] As used herein, the term "phase state" refers to the condition of a fluid relative to the phase of the fluid and / or relative to a region within the phase of the fluid. As an example, the phase state of a fluid can include and refer to the condition of a fluid relative to a pericritical phase or a region within a pericritical phase, a supercritical phase or a region within a supercritical phase, a near supercritical phase or a region within a near supercritical phase, a gas phase or a region within a gas phase, or a liquid phase or a region within a liquid phase.

[0059] In some embodiments, the fluid may include a single component. In some embodiments, the fluid may include at least two components. A fluid having two components may sometimes be referred to as a bimodal fluid. Such a combination of two fluid components may sometimes be referred to as a bimodal combination. A fluid having at least two components may sometimes be referred to as a multimodal fluid. The term multimodal fluid includes a bimodal fluid. A combination of at least two fluid components may sometimes be referred to as a multimodal combination.

[0060] As used herein, the term "multiphase" refers to a fluid comprising a plurality of components having different phases, respectively. As used herein, the term "multiphase region" refers to a region of a phase diagram of a multimodal fluid in which a fluid has a multiphase state. For example, a fluid having a multiphase state may include a first fluid component and a second fluid component, and the first fluid component and the second fluid component may respectively have: a liquid phase and a gas phase, a liquid phase and a pericritical phase, a gas phase and a pericritical phase, a liquid phase and a supercritical phase, a liquid phase and a near supercritical phase, a gas phase and a supercritical phase, a gas phase and a near supercritical phase, or a supercritical phase and a near supercritical phase.

[0061] As an example, suitable fluids that can be used according to the present disclosure include carbon monoxide, carbon dioxide, ammonia, methane, methanol, ethanol, ethylene, propane, propylene, heptane, 1-octanol, 2-octanol, 2-propanol, difluoromethane, ethane, difluoroethane, tetrafluoroethylene, acetone, nitrous oxide, argon, bromine, neon, hydrogen, oxygen or water, and combinations of these. In some embodiments, the bimodal or multimodal fluid may include one or more of the above exemplary fluids, such as at least two of the above exemplary fluids. As an example, the bimodal or multimodal fluid may include at least one of the following: carbon dioxide and nitrogen; carbon dioxide and hydrogen; carbon dioxide and oxygen; carbon dioxide and methane; carbon dioxide and heptane; carbon dioxide and 1-octanol; carbon dioxide and 2-octanol; carbon dioxide, nitrogen and ethane; carbon dioxide, hydrogen and ethane; and carbon dioxide, 2-propanol and nitrogen.

[0062] As an example, some critical points of some exemplary fluids are as follows: carbon monoxide: about 133.2K and about 3.5MPa; carbon dioxide: about 304.2K and about 7.4MPa; ammonia: about 405.5K and about 11.3MPa; methane: about 190.6K and about 4.6MPa; methanol: about 512.6K and about 8.1MPa; ethanol: about 516.3K and about 6.4MPa; ethylene: about 282.4K and about 5.1MPa; propane: about 369.9K and about 4.3MPa; propylene: about 365.6K and about 4.7MPa; heptane: about 540.6K and about 2.7MPa; 1-octanol: about 655.1K and about 2.7MPa; 2-octanol: about 632.7K and about 2. 8MPa; 2-propanol: about 508.8K and 5.4MPa; difluoromethane: about 304.1K and about 7.38MPa; ethane: about 3.5.5K and about 4.9MPa; difluoroethane: about 351K and about 5.8MPa; tetrafluoroethylene: about 306.5K and about 3.8MPa; acetone: about 508K and about 4.8MPa; nitrous oxide: about 309.6K and about 7.3MPa; argon: about 150.7K and about 4.9MPa; bromine: about 588K and about 10.3MPa; neon: about 44.4K and about 2.8MPa; hydrogen: about 33.2K and about 1.3MPa; oxygen: about 154.6K and about 5.1MPa; and water: about 647.1K and about 22.1MPa.

[0063] Exemplary embodiments of the present disclosure will now be described in more detail. Figure 1, an exemplary power generation system 100 is shown. The exemplary power generation system 100 may include an engine 102, such as a turbine engine. The engine 102 may be mounted to an aircraft, such as a fixed-wing or rotary-wing aircraft. The power generation system 100 may be configured to provide propulsion and / or thrust, such as during flight and / or during ground maneuvers, thereby providing power to the aircraft. The engine 102 may be mounted to the aircraft, such as in an underwing configuration or a tail-mounted configuration. In other embodiments, the engine 102 may be configured as a rocket engine, a ramjet engine, a turborocket engine including a combination of a turbine and a rocket engine, a turboramjet engine including a combination of a turbine and a ramjet engine, or a rocket ramjet engine including a combination of a rocket engine and a ramjet engine.

[0064] like Figure 1 As shown, in some embodiments, the power generation system 100 and / or the engine 102 may include a thermal management system 200. The thermal management system 200 may be configured to transfer heat from one or more heat sources associated with the engine 102 and / or the power generation system 100. The thermal management system 200 may be configured to circulate a cooling fluid through a cooling circuit, and heat from the one or more heat sources may be transferred to the cooling fluid. In some embodiments, the cooling fluid may have a pericritical phase, such as a supercritical phase and / or a near supercritical phase, when circulating through the cooling circuit. Further as shown Figure 1 As shown, in some embodiments, the power generation system 100 and / or the engine 102 may include a fuel system 300. The fuel system 300 may be configured to supply fuel to the engine 102. In some embodiments, the fuel may be a cryogenic fuel. According to the present disclosure, the power generation system 100 and / or the engine 102 may include a pericritical fluid system 400, such as Figure 1 In some embodiments, the pericritical fluid system 400 can be used in conjunction with the thermal management system 200 . Additionally or alternatively, the pericritical fluid system 400 can be used in conjunction with the fuel system 300 .

[0065] The presently disclosed subject matter may be implemented in any desired setting including power generation system 100 and / or engines, such as a land vehicle, a marine vessel, a power generation facility, a manufacturing facility, an industrial machine, etc. In the context of an aircraft, the presently disclosed subject matter may be implemented in any desired fixed-wing or rotary-wing aircraft, including commercial, military, or civilian aircraft, as well as unmanned aircraft, such as unmanned aerial vehicles, drones, etc. The presently disclosed subject matter may be useful in numerous other settings, and it is intended that the presently disclosed subject matter may be implemented in any setting without departing from the intended scope of the present disclosure.

[0066] Reference now Figure 2A-2E, further describing an exemplary thermal management system 200. Figure 2A-2E As shown, an exemplary thermal management system 200 may include one or more heat exchangers 202, each of which is configured to cool a fluid flow 204 associated with the engine 102 and / or the power generation system 100. The fluid flow 204 flowing through the corresponding heat exchanger 202 may be cooled by a cooling fluid 206 flowing through a cooling circuit 208. The cooling fluid 206 may be a pericritical fluid, such as a supercritical fluid or a near-supercritical fluid. The cooling circuit 208 may include one or more cooling conduits 210. The one or more cooling conduits 210 may be configured to supply the cooling fluid 206 to the one or more heat exchangers 202, for example, the cooling fluid 206 has a pericritical phase, such as a supercritical phase and / or a near-supercritical phase. The one or more cooling conduits 210 may be at least partially defined by the structure of the one or more heat exchangers 202 (such as the overall structure of the one or more heat exchangers 202). The cooling circuit 208 may include one or more cooling conduits 210, and may be configured to receive the cooling fluid 206 discharged from the one or more heat exchangers 202.

[0067] During operation, the cooling fluid 206 may be supplied to the one or more heat exchangers 202 and / or circulated through the cooling loop 208 in a pericritical phase. Additionally or alternatively, the cooling fluid 206 may have a pericritical phase when flowing through the one or more heat exchangers 202 and / or circulating through the cooling loop 208. The cooling loop 208 may include a pump 212 configured to circulate the cooling fluid 206 through the cooling loop 208. In some embodiments, the thermal management system 200 and / or the cooling loop 208 may include a refrigeration system 214 configured to bring the cooling fluid 206 into a pericritical phase and / or maintain the cooling fluid 206 in a pericritical phase, such as a supercritical phase and / or a near supercritical phase. The refrigeration system 214 may include components configured to perform any suitable refrigeration cycle, such as evaporative cooling, absorption refrigeration, thermoelectric refrigeration or mechanical compression refrigeration, cryogenic refrigeration, and combinations thereof. Additionally or alternatively, the refrigeration system 214, such as a refrigeration system 214 configured to perform low temperature refrigeration, may include a cryogenic cooler, such as a Stirling type cooler, a Gifford-McMahon cooler, a pulse tube cooler, or a Joule-Thomson cooler, and combinations thereof. Additionally or alternatively, the cooling circuit 208 may include any other suitable source of cooling fluid 206, such as a tank or container configured to supply cooling fluid 206 to the cooling circuit 208, for example, the cooling fluid 206 having a pericritical phase. The cooling circuit 208 may include one or more cooling fluid control valves 224, the one or more cooling fluid control valves 224 being configured to control the flow rate of the cooling fluid 206 flowing through the cooling circuit 208. Additionally or alternatively, the thermal management system 200 may include one or more fluid flow control valves 226, the one or more fluid flow control valves 226 being configured to control the flow rate of the fluid stream 204 flowing through the corresponding heat exchanger 202.

[0068] For example, Figure 2AAs shown, in some embodiments, the thermal management system 200 may include a plurality of heat exchangers 202. As an example, the thermal management system 200 may include a first heat exchanger 216 configured to cool a first fluid flow 204 flowing through a first fluid conduit 218. The first fluid conduit 218 may be at least partially defined by a structure of the first heat exchanger 216, such as an overall structure of the first heat exchanger 216. The first fluid conduit 218 may include one or more fluid supply lines that are in fluid communication with the first heat exchanger 216 and are configured to supply the first fluid 204 to the first heat exchanger 216 and / or receive the first fluid 204 flowing out of the first heat exchanger 216. Additionally or alternatively, the thermal management system 200 may include a second heat exchanger 220 configured to cool a second fluid flow 204 flowing through a second fluid conduit 222. The second fluid conduit 222 may be at least partially defined by a structure of the second heat exchanger 220, such as an overall structure of the second heat exchanger 220. The second fluid conduit 222 may include one or more fluid supply lines in fluid communication with the second heat exchanger 220 and configured to supply the second fluid 204 to the second heat exchanger 220 and / or receive the second fluid 204 out of the second heat exchanger 220 .

[0069] In some embodiments, for example, Figure 2A As shown, the cooling circuit 208 can be configured as a heat transfer bus that includes a plurality of heat exchangers 202, such as a first heat exchanger 216 and a second heat exchanger 220 that are respectively configured to transfer heat from the fluid flow 204 to the cooling fluid 206. As an example, a corresponding one of the plurality of heat exchangers 202 can include a fuel system heat exchanger, a lubrication system heat exchanger, a sump heat exchanger, a bleed air heat exchanger, a compressor cooling air heat exchanger, a thermal clearance control heat exchanger, an engine case heat exchanger, an environmental control system heat exchanger, or an auxiliary system heat exchanger. Additionally or alternatively, the thermal management system 200 can include any other heat exchanger used in conjunction with the power generation system 100, the engine 102, and / or a vehicle powered by the engine 102.

[0070] For example, Figure 2BAs shown, in some embodiments, the fluid flow 204 cooled by the one or more heat exchangers 202 may include a working fluid used by the engine 102 and / or the power generation system 100. In some embodiments, the engine 102 may be configured as a turbine engine, and the fluid flow 204 may include intake air 230 flowing into a compressor section of the turbine engine. The one or more heat exchangers 202 may include a precooler 232 that is configured to precool the intake air 230 supplied to the compressor section of the turbine engine. As shown, a fluid flow control valve 226, such as a variable geometry inlet duct 234, may be configured to control the flow of the intake air 230 flowing through the precooler 232. Additionally or alternatively, for example, Figure 2C As shown, in some embodiments, the engine 102 can be configured as a turbine engine, and the fluid flow 204 can include compressor bleed air 236 from the compressor section of the turbine engine. The compressor bleed air 236 can be used to cool components of the turbine engine, such as blades, hubs, and / or casings of the turbine section of the turbine engine. The compressor bleed air 236 can be used in addition or alternatively by one or more auxiliary systems associated with the engine 102 and / or the power generation system 100. For example, the fluid flow 204 can be used by an environmental control system, which is configured, for example, to provide pressurization and / or temperature control to other areas of the cabin or aircraft. One or more heat exchangers 202 can include a bleed air heat exchanger 238, which is configured to cool the compressor bleed air 236 before being used to cool such components of the turbine engine and / or before being used by such an environmental control system. As shown, the fluid flow control valve 226, such as the bleed air control valve 240, can be configured to control the flow of the compressor bleed air 236 flowing through the bleed air heat exchanger 238.

[0071] For example, Figure 2D and 2E As shown, in some embodiments, the cooling fluid 206 may be used to cool one or more components 242 of the engine 102. In some embodiments, as shown in FIG. Figure 2D As shown, one or more components 242 of the engine 102 may define at least a portion of one or more cooling conduits 210 of the cooling circuit 208. For example, the cooling fluid 206 may flow through the one or more cooling conduits 210, and the one or more cooling conduits 210 are defined by the structure of the one or more components 242 of the engine 102 (such as the overall structure of the one or more components of the engine 102). Additionally or alternatively, the one or more components 242 of the engine 102 cooled by the cooling fluid 206 may define a heat exchanger 202 through which the cooling fluid 206 may flow. For example, the heat exchanger 202 may be defined by the structure of the one or more components 242 of the engine 102 (such as the overall structure of the one or more components of the engine 102).

[0072] In some embodiments, one or more components 242 of the engine cooled by the cooling fluid 206 may include an engine casing. For example, in some embodiments, the engine 102 may be configured as a hybrid electric turbine engine, and the one or more components 242 cooled by the cooling fluid 206 may include one or more components of an electric motor, such as a rotor, a stator, and / or a casing of the electric motor. As another example, the engine 102 may be configured as a turbine engine, and the one or more components 242 cooled by the cooling fluid 206 may include a plurality of turbine blades, a plurality of stator blades, a plurality of turbine hubs, and / or one or more casing elements surrounding a turbine section of the turbine engine.

[0073] In some embodiments, Figure 2E As shown, the thermal management system 200 may include a primary cooling circuit 244 and an intermediate cooling circuit 246. The primary cooling circuit 244 may be configured to cool one or more components 242 of the engine 102 by transferring heat to a primary cooling fluid 248 flowing through the primary cooling circuit 244. As examples, the primary cooling fluid 248 may include oil, liquid hydrocarbon-based materials, dielectric fluids, liquid metals, or any other fluid that may be suitable for use as the primary cooling fluid 248.

[0074] One or more components 242 of the engine 102 may define one or more heat exchangers 202 through which a primary cooling fluid 248 may flow. For example, the heat exchanger 202 may be defined by the structure of the one or more components 242 of the engine 102 (such as the overall structure of the one or more components of the engine 102). Additionally or alternatively, the primary cooling circuit 244 may include one or more primary cooling conduits 250. The one or more primary cooling conduits 250 may be configured to supply the primary cooling fluid 248 to the one or more heat exchangers 202. The one or more primary cooling conduits 250 may be at least partially defined by the structure of the one or more heat exchangers 202 (such as the overall structure of the one or more heat exchangers 202). The one or more primary cooling conduits 250 may be configured to receive the primary cooling fluid 248 discharged from the one or more heat exchangers 202. In some embodiments, the primary cooling circuit 244 may include a primary pump 252, which is configured to circulate the primary cooling fluid 248 through the primary cooling circuit 244. Additionally or alternatively, the primary cooling circuit 244 may include one or more primary cooling fluid control valves 254 configured to control a flow rate of the primary cooling fluid 248 flowing through the primary cooling circuit 244 .

[0075] The primary cooling circuit 244 and / or the intermediate cooling circuit 246 may include an intermediate heat exchanger 256 configured to transfer heat from the primary cooling fluid 248 flowing through the primary cooling circuit 244 to the intermediate cooling fluid 258 flowing through the intermediate cooling circuit 246. During operation, the intermediate cooling fluid 258 may be supplied to the intermediate heat exchanger 256 and / or circulate through the intermediate cooling circuit 246 in a pericritical phase, such as a supercritical phase and / or a near-supercritical phase. Additionally or alternatively, when the intermediate cooling fluid 258 flows through the intermediate heat exchanger 256 and / or circulates through the intermediate cooling circuit 246, the intermediate cooling fluid 258 may have a pericritical phase.

[0076] The intermediate cooling circuit 246 may include one or more intermediate cooling conduits 260. The one or more intermediate cooling conduits 260 may be configured to supply an intermediate cooling fluid 258 to the intermediate heat exchanger 256. The one or more intermediate cooling conduits 260 may be at least partially defined by a structure of the intermediate heat exchanger 256, such as an integral structure of the intermediate heat exchanger 256. The one or more intermediate cooling conduits 260 may be configured to receive the intermediate cooling fluid 258 exhausted from the one or more heat exchangers 202.

[0077] In some embodiments, the intercooling circuit 246 may include an intercooling pump 262 configured to circulate the intercooling fluid 258 through the intercooling circuit 246. In some embodiments, the thermal management system 200 and / or the intercooling circuit 246 may include a refrigeration system 214 configured to bring the intercooling fluid 258 into a pericritical phase, such as a supercritical phase and / or a near supercritical phase. Additionally or alternatively, the intercooling circuit 246 may include any other suitable source of the intercooling fluid 258, such as a tank or container configured to supply the intercooling fluid 258 to the intercooling circuit 246, for example, the intercooling fluid 258 having a pericritical phase. The intercooling circuit 246 may include one or more intercooling fluid control valves 264 configured to control the flow of the intercooling fluid 258 flowing through the intercooling circuit 246.

[0078] Still reference Figure 2A-2EAs shown, the cooling circuit 208 or the intermediate cooling circuit 246 may include a pericritical fluid system 400. In some embodiments, the pericritical fluid system 400 may define a portion of the thermal management system 200. The pericritical fluid system 400 may be configured to determine one or more phase properties of the cooling fluid 206 and / or the intermediate cooling fluid 258. The one or more phase properties of the cooling fluid 206 and / or the intermediate cooling fluid 258 may include a phase state, a transition to or from a phase state to another phase state, and / or one or more physical properties that depend on such a phase state.

[0079] Reference now Figure 3A and 3B , further describing an exemplary fuel system 300. Figure 3A and 3B As shown, an exemplary fuel system 300 may include a fuel path 302. The fuel path 302 may include one or more fuel conduits 304. The fuel conduits 304 may be configured to supply fuel 306 to the engine 102, for example, the fuel 306 having a pericritical phase, such as a supercritical phase and / or a near supercritical phase. For example, the fuel 306 may be supplied to the engine 102 in a pericritical phase. Additionally or alternatively, the fuel path 302 may include a cooling circuit 208 ( Figure 2A-2E ). As examples, exemplary fuels 306 may include hydrogen, methane, liquid natural gas, kerosene, kerosene-type jet fuels (e.g., Jet A, Jet A-1, JP-5, JP-8), and combinations thereof. In some embodiments, thermal management system 200 may define at least a portion of fuel system 300. Additionally or alternatively, fuel system 300 may include thermal management system 200. In some embodiments, cooling fluid 206 used by thermal management system 200 may include fuel 306. Additionally or alternatively, in some embodiments, power generation system 100 and / or engine 102 may separately include thermal management system 200 and fuel system 300.

[0080] like Figure 3A and 3B As shown, in some embodiments, the fuel system 300 may include a fuel tank 308 configured to store fuel 306 in a near-critical phase (such as a supercritical phase and / or a near-supercritical phase). Additionally or alternatively, the fuel system 300 may include a pump 212 ( Figure 2A-2E ), the pump 212 is configured to supply fuel 306 to the fuel path 302 in this pericritical phase. The fuel path 302 may include one or more fuel control valves 310, which are configured to control the flow of fuel 306 flowing through the fuel path 302.

[0081] For example, Figure 3A As shown, in some embodiments, the fuel system 300 may include one or more heat exchangers 202, and the one or more heat exchangers 202 are respectively configured to cool the fluid flow 204 associated with the engine 102 and / or the power generation system 100. The fluid flow 204 flowing through the corresponding heat exchanger 202 can be cooled by the fuel 306 flowing through the fuel path 302. The fuel path 302 may include one or more fuel conduits 304, and the one or more fuel conduits 304 are configured to supply fuel 306 to the one or more heat exchangers 202, for example, the fuel 306 has a pericritical phase. The one or more fuel conduits 304 may be at least partially defined by the structure of the one or more heat exchangers 202 (such as the overall structure of the one or more heat exchangers 202). Additionally or alternatively, the fuel path 302 may include one or more fuel conduits 304, and the one or more fuel conduits 304 may be configured to receive the fuel 306 discharged from the one or more heat exchangers 202. In some embodiments, the fuel system 300 may include one or more fluid flow control valves 226 configured to control the flow rate of the fluid stream 204 flowing through the corresponding heat exchanger 202 .

[0082] In some embodiments, for example, Figure 3B As shown, the fluid flow 204 cooled by the one or more heat exchangers 202 may include a working fluid used by the engine 102 and / or the power generation system 100. In some embodiments, the engine 102 may be configured as a turbine engine, and the fluid flow 204 may include an intake air 230 flowing into a compressor section of the turbine engine. The one or more heat exchangers 202 may include a precooler 232, which is configured to use a fuel 306 to precool the intake air 230 supplied to the compressor section of the turbine engine. As shown, a fluid flow control valve 226, such as a variable geometry inlet duct 234, may be configured to control the flow of the intake air 230 flowing through the precooler 232. The fuel leaving the precooler 232 may flow to the combustion section 312 of the engine 102. At the combustion section 312, the fuel 306 may be combined with the intake air 230, and the resulting combination may be combusted to generate thrust.

[0083] Still reference Figure 3A and 3BAs shown, the fuel system 300 may include a pericritical fluid system 400. In some embodiments, the pericritical fluid system 400 may define a portion of the fuel system 300. The pericritical fluid system 400 may be configured to determine one or more phase properties of the fuel 306. The one or more phase properties of the fuel 306 may include a phase state, a transition to or from a phase state to another phase state, and / or one or more physical properties that depend on such a phase state.

[0084] Reference now Figure 4 , further describing an exemplary pericritical fluid system 400. The exemplary pericritical fluid system 400 may be included in and / or used by the thermal management system 200 and / or the fuel system 300. In some embodiments, the first pericritical fluid system 400 may define a portion of the thermal management system 200, and the second pericritical fluid system 400 may define a portion of the fuel system 300. Figure 4 As shown, the pericritical fluid system 400 may include one or more sensors 402 configured to generate a sensor output 404 corresponding to one or more phase properties of a fluid 401. The fluid 401 may include a cooling fluid 206 associated with the thermal management system 200, such as the one described herein with reference to Figure 2A-2E Additionally or alternatively, fluid 401 may include fuel 306 associated with fuel system 300, such as described herein with reference to Figure 3A and 3B As described. Fluid 401 may include a pericritical fluid, such as a supercritical fluid and / or a near supercritical fluid. Additionally or alternatively, fluid 401 may include a liquid and / or a gas. Additionally or alternatively, fluid 401 may include a multimodal fluid.

[0085] The sensor output 404 may be transmitted to the control system 600. The one or more sensors 402 and / or the control system 600 may generate fluid monitoring data 406 based at least in part on the sensor output 404. Additionally or alternatively, the fluid monitoring data 406 may include the sensor output 404. The sensor output 404 and / or the fluid monitoring data 406 may be used, for example, by the control system 600 to determine one or more phase properties of the fluid 401. The fluid monitoring data 406 may include one or more phase properties of the fluid 401, such as one or more phase properties of the fluid 401 determined from the sensor output 404. Additionally or alternatively, the control system 600 may use the fluid monitoring data 406 to control one or more controllable components 408, for example, to adjust and / or maintain desired phase properties of the fluid 401.

[0086] like Figure 4As shown, the one or more sensors 402 may include one or more phase detection sensors 410. Additionally or alternatively, the one or more sensors 402 may include one or more temperature sensors 412. Additionally or alternatively, the one or more sensors 402 may include one or more pressure sensors 414. The one or more sensors 402 may be respectively configured to generate a sensor output 404, which may be transmitted to the control system 600. The sensor outputs 404 from respective sensors in the plurality of sensors 402 may be combined, for example, to generate fluid monitoring data 406. Additionally or alternatively, the fluid monitoring data 406 may be generated based at least in part on the sensor outputs 404 from the plurality of sensors 402. Additionally or alternatively, the fluid monitoring data 406 may be generated based at least in part on a comparison of the one or more sensor outputs 404 with other data (such as a lookup table, a model, etc.), and / or based at least in part on one or more operations performed on the one or more sensor outputs 404, for example, based at least in part on such a lookup table, a model, etc.

[0087] The one or more phase detection sensors 410 may include any suitable sensor configured to generate a sensor output 404 from which one or more phase properties of the fluid 401 may be determined. In some embodiments, for example, the one or more phase properties of the fluid 401 may be determined from the sensor output 404 generated by the phase detection sensor 410 without reference to other data. Additionally or alternatively, the one or more phase properties of the fluid 401 may be determined based at least in part on the sensor output 404 generated by the phase detection sensor 410 and at least in part on data from another source, such as additional sensor outputs 404 from one or more other sensors 402, fluid monitoring data 406, a lookup table, a model, etc.

[0088] In some embodiments, when a phase boundary is crossed due to a change in temperature and / or pressure, the sensor output 404 generated by the phase detection sensor 410 may exhibit a change in the sensor output 404 value, such as a sudden change in the sensor output 404 value. The change in the sensor output 404 value exhibited by the sensor output 404 generated by the phase detection sensor 410 may include the sensor output 404 value being above an upper threshold, the sensor output 404 value being below a lower threshold, the sensor output 404 value exhibiting a rate of change value above an upper threshold rate of change value, the sensor output 404 value exhibiting a rate of change value below an upper threshold rate of change value, etc., and combinations thereof.

[0089] In some embodiments, the phase detection sensor 410 may include an acoustic sensor, such as a sound velocity sensor or a sound wave sensor. An exemplary sound velocity sensor may be configured to determine the speed of a sound wave propagating through the fluid 401. The sound velocity sensor may include a transducer (such as an ultrasonic transducer) configured to emit sound waves (such as ultrasonic sound waves). The sound velocity sensor may include a receiver configured to receive sound waves and convert the sound waves into electrical signals. The transducer and the receiver may be integrated into a common component or may be provided as separate components. The sensor output 404 from the phase detection sensor 410 (such as a sound velocity sensor) may include an electrical signal corresponding to the sound wave received by the sound velocity sensor. In some embodiments, the speed of the sound wave (such as an ultrasonic sound wave) propagating through the fluid may depend at least in part on one or more phase properties of the fluid. In some embodiments, the speed of the sound wave may be close to a minimum value at about the critical point of the fluid. One or more phase properties of the fluid 401 may be related to the sensor output 404 from the phase detection sensor 410 (such as a sound velocity sensor).

[0090] The acoustic wave sensor can be configured to apply an oscillating electric field to generate an acoustic wave that propagates through a piezoelectric substrate. Suitable piezoelectric substrates can include quartz, lithium tantalate, lithium niobate, gallium arsenide, silicon carbide, lanthanum gallium silicate, zinc oxide, aluminum nitride, lead zirconium titanate, polyvinylidene fluoride, and combinations of these. The acoustic wave is converted back into an electrical signal. Exemplary acoustic wave sensors include bulk acoustic wave sensors, surface acoustic wave sensors, and the like. Exemplary acoustic wave sensors can include piezoelectric substrates. The sensor output 404 from the phase detection sensor 410 (such as an acoustic wave sensor) can include an electrical signal corresponding to the acoustic wave propagating through the piezoelectric substrate. Exemplary acoustic wave sensors include bulk acoustic wave sensors, such as thickness shear mode sensors, horizontal shear acoustic plate mode sensors, and horizontal shear surface acoustic wave sensors. Thickness shear mode sensors are sometimes referred to as quartz crystal microbalance resonators. Advantageously, the acoustic wave generated by such a bulk acoustic wave sensor propagates in the horizontal shear direction, which avoids radiating considerable acoustic energy into the fluid 401. In some embodiments, the surface acoustic wave sensor may radiate acoustic waves into the fluid 401 , causing the acoustic waves to attenuate.

[0091] One or more properties of the acoustic waves propagating through the piezoelectric substrate, such as frequency, amplitude, or phase, and combinations of these, may depend at least in part on one or more phase properties of the fluid 401. The one or more phase properties of the fluid 401 may be related to the sensor output 404 from the phase detection sensor 410, such as an acoustic wave sensor. The impedance minimum of the equivalent circuit of the acoustic wave sensor may be proportional to the density and viscosity of the fluid 401. In some embodiments, the impedance minimum exhibited by the acoustic wave sensor may be proportional to the density and viscosity of the fluid 401 according to the following relationship: min ∝(ρη)1 / 2 , where Z min is the impedance minimum, ρ is the density of the fluid 401, and η is the viscosity of the fluid.

[0092] In some embodiments, the impedance values ​​from the phase detection sensor 410 (such as an acoustic wave sensor) may respectively exhibit different characteristics with respect to a vaporization curve (such as a liquid saturation curve and / or a vapor saturation curve of the fluid 401). For example, when the fluid 401 reaches a bubble point (liquid saturation point), the impedance value from the acoustic wave sensor may exhibit an inflection point indicating a moderate increase. The moderate increase in the impedance value may be attributed to bubbles formed on the surface of the acoustic wave sensor (such as on the surface of the piezoelectric substrate). Additionally or alternatively, when the fluid 401 reaches a dew point (vapor saturation point), the impedance value from the acoustic wave sensor may exhibit an inflection point indicating a significant increase. The significant increase in the impedance value may be attributed to condensate formed on the surface of the acoustic wave sensor (such as on the surface of the piezoelectric substrate). For a bimodal or multimodal fluid 401, the impedance value from the acoustic wave sensor may exhibit multiple inflection points corresponding to the components of the bimodal or multimodal fluid 401, respectively.

[0093] An exemplary phase detection sensor 410, such as an acoustic wave sensor, is sensitive to very small changes in the amount of bubbles or condensate in the fluid 401. For example, such bubbles or condensate may accumulate on the surface of the acoustic wave sensor. Such changes in the amount of bubbles or condensate may produce a noticeable change in the sensor output 404 (such as an impedance value) from the phase detection sensor 410. In some embodiments, the bubble point may be distinguished from the dew point based at least in part on a change in the sensor output 404 value (such as a change in the impedance value). Additionally or alternatively, a critical point may be determined based at least in part on a change in the sensor output 404 value, such as a change in the impedance value. Additionally or alternatively, the proximity of the bubble point or dew point to the critical point may be determined based at least in part on a change in the sensor output 404 value, such as a change in the impedance value. For example, respectively, the closer the bubble point or dew point is to the critical point, the smaller the change in the sensor output 404 value when the bubble point or dew point is reached. In some embodiments, the change in the sensor output 404 value at the critical point may be approximately zero.

[0094] In some embodiments, the phase detection sensor 410 may include an optical sensor, such as a fiber optic reflectometer or an infrared spectrometer. An exemplary fiber optic reflectometer may include a light source, an optical fiber, and a photodiode, the light source being configured to generate a probe beam, the optical fiber being configured to introduce the probe beam into a measurement chamber, and the photodiode being configured to measure the intensity of the probe beam. The probe beam may pass through the fluid 401 and then may be incident on the photodiode. The transmission, reflection, and / or refraction of the probe beam may depend at least in part on one or more phase properties of the fluid 401. The intensity of the probe beam may be compared with a reference value and / or a reference beam emitted by a light source. As an example, the reference beam may be separated from the probe beam by a beam splitter and may be incident on a photodiode. The reference beam may be monitored by a reference photodiode, for example, to compensate for intensity variations, etc. In some embodiments, the fiber optic reflectometer may include one or more microstructured optical fibers, the one or more microstructured optical fibers including a core material and a plurality of channels defined within the core material, and the light may be guided through the plurality of channels by total internal reflection and / or constructive interference of scattered light. Exemplary microstructured optical fibers include photonic crystal fibers, photonic bandgap fibers, holey fibers, hole-assisted fibers, and Bragg fibers.

[0095] The sensor response of the phase detection sensor 410 (such as a fiber optic reflectometer) can depend at least in part on one or more phase properties of the fluid 401. The one or more phase properties of the fluid 401 can be related to the sensor output 404 from the phase detection sensor 410 (such as a fiber optic reflectometer). In some embodiments, the one or more phase properties of the fluid 401 can be determined based at least in part on the sensor output 404 value from the phase detection sensor 410 (such as a fiber optic reflectometer). For example, the fluid 401 can exhibit different refractive indices depending on the phase state of the fluid 401. For example, the refractive index of the fluid 401 can be different between at least two of the following: a liquid phase, a gas phase, a pericritical phase, a supercritical phase, and a near supercritical phase. Additionally or alternatively, the refractive index of the fluid 401 can be different between at least two different phases within a phase (such as within a liquid phase, a gas phase, a pericritical phase, a supercritical phase, and / or a near supercritical phase). Additionally or alternatively, the refractive index of fluid 401 may depend at least in part on one or more other phase properties of fluid 401 , such as the density of fluid 401 .

[0096] Additionally or alternatively, one or more phase properties of the fluid 401 may be determined based at least in part on a noise or bias level of sensor output 404 values ​​from a phase detection sensor 410 (such as a fiber optic reflectometer). For example, the noise or bias level of the sensor output 404 values ​​may increase due to phase separation. The increase in noise or bias may be attributed to, for example, differences in refractive index between bubbles and condensate in the fluid 401, between a phase of the fluid 401 and bubbles present in the phase of the fluid 401, and / or between a phase of the fluid 401 and condensate present in the phase of the fluid 401. For a fluid 401 having a multi-phase state, the noise or bias level of the sensor output 404 values ​​may additionally or alternatively increase, for example, due to phase separation of one or more components in the fluid 401. In some embodiments, the refractive index of the fluid 401 may increase when the phase of the fluid 401 reaches a vaporization curve and / or a vapor point on the vaporization curve (such as a liquid saturation curve and / or a bubble point on the liquid saturation curve), such as when the phase of the fluid 401 crosses the vaporization curve. Additionally or alternatively, the refractive index of the fluid 401 may increase when the phase of the fluid 401 reaches the vapor saturation curve and / or the dew point on the vapor saturation curve, such as when the phase of the fluid 401 crosses the vapor saturation curve from the gaseous state. Advantageously, the noise or deviation level of the sensor output 404 values ​​from the phase detection sensor 410 (such as a fiber optic reflectometer) may be used to separately represent different phases of a multimodal fluid (such as a multimodal fluid exhibiting multiple phases).

[0097] An exemplary infrared spectrometer may include a transmission infrared spectrometer or an attenuated total reflection infrared spectrometer. An exemplary infrared spectrometer may include an infrared light source, a measurement window, and an infrared detector, the measurement window being configured to contact the fluid 401, and an infrared detector (such as a photodiode) being configured to detect infrared light transmitted through the measurement window. An infrared spectrometer, such as an attenuated total reflection infrared spectrometer, may be configured to detect total internal reflection. An infrared beam generates an evanescent wave at a reflection node, and the infrared beam is reflected from the inner surface of the measurement window in contact with the fluid 401 at the reflection node. The penetration depth of the evanescent wave may depend at least in part on one or more phase properties of the fluid 401. As an example, the penetration depth of the fluid 401 in the gas phase may be greater than the penetration depth of the fluid 401 in the liquid phase. The intensity change detected by the infrared detector may indicate a phase change. Additionally or alternatively, the absorbance intensity may correspond to a wave number that depends at least in part on one or more phase properties of the fluid 401. For example, the respective different phases of the fluid 401 may exhibit peak absorbance at respective different wave numbers. Additionally or alternatively, the absorbance intensity may depend, at least in part, on the proximity of the phase state of the fluid 401 to a vaporization curve, such as a vapor saturation curve and / or a liquid saturation curve. For example, the absorbance intensity may increase as the phase state of the fluid 401 approaches a vaporization curve, such as a vapor saturation curve and / or a liquid saturation curve. Additionally or alternatively, a fluid combination, such as a bimodal and / or multimodal fluid, may exhibit respective different absorbance intensity values ​​and / or peak absorbances at respective different wave numbers, such that one or more phase properties of respective portions of the bimodal and / or multimodal fluid 401 may be determined from a sensor output 404 from a phase detection sensor 410, such as an attenuated total reflection infrared spectrometer or other infrared spectrometer.

[0098] In some embodiments, the phase detection sensor 410 may include a pressure drop sensor, such as a microchannel pressure drop sensor or a packed bed pressure drop sensor. The pressure drop sensor may include a sample path through which the fluid 401 may flow. The fluid 401 may exhibit a pressure drop due to friction of the fluid interacting with the surface of the microchannel, packed bed, etc. The pressure drop across the sample path may depend at least in part on one or more phase properties of the fluid 401. One or more phase properties of the fluid 401 may be associated with a sensor output 404 from the phase detection sensor 410 (such as a pressure drop sensor). In some embodiments, the fluid 401 may exhibit a defined pressure drop change when undergoing a phase transition. For example, a liquid phase may exhibit a greater pressure drop than a gas phase. Additionally or alternatively, a supercritical phase may exhibit a relatively low pressure drop, for example due to a lack of surface tension in the fluid 401. Additionally or alternatively, a multimodal fluid exhibits a greater pressure drop in a multiphase state relative to a single phase state, for example due to surface tension interactions between the respective different phases of the fluid components. Additionally or alternatively, the pressure drop of the fluid 401 may depend at least in part on the density of the fluid 401.

[0099] In some embodiments, one or more phase properties of the fluid 401 may be determined based at least in part on the sensor output 404 from the one or more phase detection sensors 410, regardless of the type of phase detection sensor 410 used by the pericritical fluid system 400. For example, the control system 600 may be configured to determine one or more phase properties of the fluid 401 based at least in part on a correlation between the sensor output 404 from the one or more phase detection sensors 410 and the one or more phase properties of the fluid 401. As an example, the control system 600 may include one or more models, lookup tables, etc. that correlate the sensor output 404 from the one or more phase detection sensors 410 to the one or more phase properties of the fluid 401. Additionally or alternatively, in some embodiments, the sensor output 404 from the one or more phase detection sensors 410 may be used in combination with the sensor output 404 from the one or more temperature sensors 412 and / or the one or more pressure sensors 414. For example, the one or more phase properties of the fluid 401 are based at least in part on a correlation between the sensor output 404 from the one or more phase detection sensors 410 and the sensor output 404 from the one or more temperature sensors 412 and / or the one or more pressure sensors 414. In some embodiments, for example, without correlating the sensor output 404 from the one or more phase detection sensors 410 with the determined phase property of the fluid 401, the sensor output 404 from the one or more temperature sensors 412 and / or the one or more pressure sensors 414 may be used in combination with the sensor output 404 from the one or more phase detection sensors 410 to determine one or more phase properties of the fluid 401. For example, a change in the value of the sensor output 404 from the phase detection sensor 410 may indicate the occurrence of a phase change, and the sensor output 404 from the one or more temperature sensors 412 and / or the one or more pressure sensors 414 may be used to determine a phase state corresponding to the phase change indicated by the change in the value of the sensor output 404 from the phase detection sensor 410. In some embodiments, the controller may be configured to determine whether the phase state corresponding to the phase change includes a liquid phase state, a gas phase state, a pericritical phase state, a supercritical phase state, a near-supercritical phase state, or a multi-phase state based at least in part on the sensor output 404 from the one or more temperature sensors 412 and / or the one or more pressure sensors 414. As another example, sensor output 404 from one or more temperature sensors 412 and / or one or more pressure sensors 414 can be used in combination with sensor output 404 from one or more phase detection sensors 410 to distinguish between one or more of: vapor saturation curve and liquid saturation curve, dew point and bubble point, critical point and dew point or bubble point, bubble point and critical condensate pressure (cricondenbar), and / or dew point and circumcenter.Additionally or alternatively, in some embodiments, the phase state corresponding to the phase change indicated by the change in the value of the sensor output 404 from the phase detection sensor 410 may be determined without reference to the sensor output 404 from the one or more temperature sensors 412 and / or the one or more pressure sensors 414, for example, by correlation between the one or more phase properties of the fluid 401 and the sensor output from the phase detection sensor 410. Additionally or alternatively, in some embodiments, the one or more phase properties of the fluid 401 may be determined at least in part based on the sensor output 404 from the one or more phase detection sensors 410 without requiring the sensor output 404 from the one or more temperature sensors 412 or the one or more pressure sensors 414.

[0100] Regardless of the particular configuration of the pericritical fluid system 400 according to the present disclosure, the control system 600 can be configured to determine one or more phase properties of the fluid 401 based at least in part on one or more sensor outputs 404, such as sensor outputs 404 from one or more phase detection sensors 410, and / or based at least in part on sensor outputs 404 from one or more phase detection sensors 410 in combination with sensor outputs 404 from one or more temperature sensors 412 and / or pressure sensors 414. One or more phase properties of the fluid 401 can be determined based at least in part on correlations between one or more sensor outputs 404 from one or more phase detection sensors 410 and one or more phase properties of the fluid 401, alone and / or in combination with one or more sensor output 404 values ​​from one or more temperature sensors 412 and / or one or more pressure sensors 414. One or more phase properties of the fluid 401 can be determined based at least in part on a model, a lookup table, or the like, for example, which uses one or more sensor outputs 404 as input for determining one or more phase properties of the fluid 401.

[0101] In some embodiments, the control system 600 can be configured to determine the phase of the fluid 401, such as whether the fluid 401 exhibits a liquid phase, a gas phase, a pericritical phase, a supercritical phase, a near-supercritical phase, and / or a multiphase state, and / or the proximity of the phase of the fluid 401 to such a phase based at least in part on the sensor output 404. Additionally or alternatively, the control system 600 can be configured to determine the phase of the fluid 401 is consistent with and / or close to one or more of the following: a vaporization curve, a vapor point, a vapor saturation curve, a dew point, a liquid saturation curve, a bubble point, a critical point, a critical condensate pressure, and / or an exocenter. In some embodiments, the control system 600 can be configured to determine the density of the fluid 401 based at least in part on such sensor output 404. In some embodiments, for a bimodal or multimodal fluid 401, the control system 600 may be configured to determine the phase states of respective components of the bimodal or multimodal fluid 401, such as whether one and / or more respective portions of the fluid 401 exhibit a liquid phase, a gas phase, a pericritical phase, a supercritical phase, a near-supercritical phase, and / or a multi-phase state, and / or the proximity of the phase state of one and / or more respective portions of the fluid 401 to such a phase state. Additionally or alternatively, for a bimodal or multimodal fluid 401, the control system 600 may be configured to determine the proximity of the phase state of one and / or more respective portions of the fluid 401 to one or more of the following: a vaporization curve, a vapor point, a vapor saturation curve, a dew point, a liquid saturation curve, a bubble point, a critical point, a critical condensate pressure, and / or an exocenter. Additionally or alternatively, for a bimodal or multimodal fluid 401 , the control system 600 may be configured to determine a bulk density of the bimodal or multimodal fluid 401 , and / or densities of components of the bimodal or multimodal fluid 401 based at least in part on the sensor output 404 .

[0102] In some embodiments, the control system 600 may be configured to control one or more controllable components 408 based at least in part on one or more sensor outputs 404, and / or based at least in part on one or more phase properties of the fluid 401 determined from such sensor output 404 values. For example, the controllable components 408 may be configured to control one or more phase properties of the fluid 401 based at least in part on control commands 409 from the control system 600. In some embodiments, the one or more controllable components 408 may be configured to change the temperature and / or pressure of the fluid 401. Additionally or alternatively, the one or more controllable components 408 may be configured to change the flow rate of the fluid 401. The changes in the temperature, pressure, and / or flow rate of the fluid 401 applied by the control system 600 may be effective to change and / or maintain the phase state of the fluid 401. Additionally or alternatively, the changes in the temperature, pressure, and / or flow rate of the fluid 401 applied by the control system 600 may be effective to change and / or maintain the density of the fluid 401, for example, relative to the corresponding phase state of the fluid 401. In some embodiments, the control system 600 can be configured to maintain the fluid 401 in a pericritical phase (such as a supercritical phase and / or a near supercritical phase), for example, by controlling a controllable component. Additionally or alternatively, the control system 600 can be configured to maintain the phase of the fluid 401 within a specified control range. The specified control range may include an upper control limit and / or a lower control limit. The desired range can be selected at least in part based on the desired density range of the fluid. Additionally or alternatively, the desired range can be selected at least in part based on one or more of the following: vaporization curve, vapor point, vapor saturation curve, dew point, liquid saturation curve, bubble point, critical point, critical condensate pressure and / or exocenter. For example, the desired range can be selected at least in part to maintain the fluid 401 in a desired phase, such as a phase with a desired proximity relative to such a vapor saturation curve, dew point, liquid saturation curve, bubble point, critical point, critical condensate pressure and / or exocenter. This desired proximity may be selected, at least in part, to avoid phase changes in fluid 401 due to, for example, changes in operating conditions of power generation system 100 and / or engine 102 .

[0103] Exemplary controllable components 408 that may be controlled by the control system 600 may include any component that may be controlled to change the temperature, pressure, and / or flow rate of a fluid. For example, the controllable components 408 may include one or more of the following: a control valve, a compressor, a pump, and / or an accumulator. In some embodiments, the controllable components 408 may include one or more cooling fluid control valves 224 configured to control the flow of a fluid 401, such as a cooling fluid 206 flowing through the cooling circuit 208. Additionally or alternatively, the controllable components 408 may include one or more fuel control valves 310 configured to control the flow of fuel 306 flowing through the fuel path 302. Additionally or alternatively, in some embodiments, the controllable components 408 may include a pump 212 configured to circulate the fluid 401, such as a pump 212 configured to circulate the cooling fluid 206 through the cooling circuit 208, and / or a pump 212 configured to supply fuel 306 to the fuel path 302. In some embodiments, the controllable components 408 may include one or more components of the refrigeration system 214 configured to bring the fuel 306 into a pericritical phase and / or maintain the fuel 306 in a pericritical phase, such as a supercritical phase and / or a near supercritical phase. Additionally or alternatively, in some embodiments, the controllable components 408 may include one or more fluid flow control valves 226 configured to control the flow of the fluid stream 204 flowing through the heat exchanger 202, such as a variable geometry inlet duct 234 configured to control the flow of the intake air 230 flowing through the precooler 232, or such as a bleed air control valve 240 configured to control the flow of the compressor bleed air 236 flowing through the bleed air heat exchanger 238, or such as a primary cooling fluid control valve 254 configured to control the flow of the primary cooling fluid 248 flowing through the primary cooling circuit 244.

[0104] Reference now Figures 5A-5E , depicts an exemplary phase diagram 500 for a fluid 401. The fluid 401 may be the cooling fluid 206 and / or the fuel 306. Figures 5A-5D A phase diagram of fluid 401 with respect to temperature and pressure is shown. Figure 5EThe phase diagram of the fluid about pressure and density is shown. As shown, the phase diagram of the fluid 401 can include a vaporization curve 502 defined by a plurality of vapor points 504. At a pressure higher than the vaporization curve, the fluid can have a liquid phase. At a pressure lower than the vaporization curve, the fluid can have a gas phase. At a temperature on the right side of the vaporization curve, the fluid can have a gas phase. At a temperature on the left side of the vaporization curve, the fluid can have a liquid phase. The vaporization curve 502 can terminate at a critical point 506. When the fluid has a temperature and pressure exceeding the critical point of the fluid, the fluid 401 can have a supercritical phase. In addition to when the fluid 401 exhibits a supercritical phase, when the fluid 401 has a temperature of at least 70% of the critical temperature of the fluid 401 and a pressure of at least 70% of the critical pressure of the fluid 401, the fluid 401 can exhibit a near supercritical phase. When the fluid exhibits a supercritical phase or a near supercritical phase, the fluid 401 can have a pericritical phase.

[0105] Figure 5A The phase diagram shown in may correspond to a fluid 401 having a single component, such as a first component. As an example, in some embodiments, the first fluid component may be carbon dioxide. Figure 5B and 5C The phase diagram shown in may correspond to a bimodal fluid 401. The bimodal fluid 401 may include a first fluid component and a second fluid component. As an example, in some embodiments, the first fluid component may be carbon dioxide and the second fluid component may be nitrogen. Figure 5D The phase diagram shown in may correspond to a multimodal fluid 401. The multimodal fluid 401 may include a first fluid component, a second fluid component, and a third fluid. As an example, in some embodiments, the first fluid component may be carbon dioxide, the second fluid component may be nitrogen, and the third fluid may be ethane. Figures 5B-5D As shown, the bimodal fluid 401 or the multimodal fluid 401 may include a multiphase region 508, and the fluid 401 may include a liquid phase and a gas phase within the multiphase region 508. The multiphase region may be bounded by a liquid saturation curve 510 and a vapor saturation curve 512. The liquid saturation curve 510 may be defined by a plurality of bubble points representing the transition from the liquid phase to the vapor phase. The plurality of bubble points may include a critical condensate pressure 514 representing a maximum pressure, above which no gas may be formed regardless of the temperature. The temperature corresponding to the critical condensate pressure 514 may be referred to as a critical condensate pressure temperature. The vapor saturation curve 512 may be defined by a plurality of dew points representing the transition from the gas phase to the liquid phase. The plurality of dew points may include a critical condensate temperature (cricondentherm) 516 representing a maximum temperature, above which no liquid may be formed regardless of the pressure. The pressure corresponding to the critical condensate temperature 516 may be referred to as a critical condensate temperature pressure. For a single component fluid, for example, Figure 5AAs shown, liquid saturation curve 510 and vapor saturation curve 512 may be consistent with vaporization curve 502 , and plurality of vapor points 504 correspond to a plurality of bubble points and a plurality of dew points, respectively.

[0106] like Figure 5B As shown, bimodal fluid 401 may include a first fluid component and a second fluid component. Multiphase region 508 of bimodal fluid 401 may be defined by vapor saturation curve 512 and liquid saturation curve 510, wherein vapor saturation curve 512 is defined by a plurality of dew points representing a transition of the first fluid component from a gas phase to a liquid phase, and liquid saturation curve 510 is defined by a plurality of bubble points representing a transition of the second fluid component from a liquid phase to a gas phase. In some embodiments, Figure 5B In the multiphase region 508 shown, the first fluid component may have a liquid phase and the second fluid component may have a gas phase. Additionally or alternatively, as Figure 5C As shown, bimodal fluid 401 may include a first fluid component and a third fluid. A multiphase region 508 of bimodal fluid 401 may be defined by a liquid saturation curve 510 and a vapor saturation curve 512, wherein the liquid saturation curve 510 is defined by a plurality of bubble points representing a transition of the first fluid component from a liquid phase to a vapor phase, and the vapor saturation curve 512 is defined by a plurality of dew points representing a transition of the third fluid from a vapor phase to a liquid phase. In some embodiments, Figure 5C Within the illustrated multiphase region 508 , the first fluid component may have a gas phase and the third fluid component may have a liquid phase.

[0107] Additionally or alternatively, such as Figure 5D As shown, the multiphase region 508 of the multimodal fluid 401 can be bounded by a liquid saturation curve 510 and a vapor saturation curve 512, wherein the liquid saturation curve 510 is defined by a plurality of bubble points representing a transition of a second fluid component from a liquid phase to a vapor phase, and the vapor saturation curve 512 is defined by a plurality of dew points representing a transition of a third fluid component from a vapor phase to a liquid phase. In some embodiments, the multiphase region 508 of the multimodal fluid 401 can include a first multiphase region 518 and a second multiphase region 520, for example, as Figure 5D The first multiphase region 518 can be defined by a liquid saturation curve 510 and a vaporization curve 502, wherein the liquid saturation curve 510 represents the transition of the second fluid component from the liquid phase to the vapor phase, and the vaporization curve 502 represents the transition of the first fluid component from the vapor phase to the liquid phase. Figure 5D In the illustrated first multiphase region 518, the first fluid component may have a liquid phase, the second fluid component may have a gas phase, and the third fluid component may have a liquid phase. The second multiphase region 520 may be defined by a vaporization curve 502 and a vapor saturation curve 512, wherein the vaporization curve 502 represents the transition of the first fluid component from a liquid phase to a gas phase, and the vapor saturation curve 512 represents the transition of the third fluid component from a gas phase to a liquid phase. Figure 5DWithin the illustrated second multiphase region 520 , the first fluid component may have a gas phase, the second fluid component may have a gas phase, and the third fluid component may have a liquid phase.

[0108] In some embodiments, the control system 600 may be configured to determine one or more phase properties of the bimodal or multimodal fluid 401 corresponding to a multiphase region of the bimodal or multimodal fluid 401, for example based at least in part on one or more sensor outputs 404 from one or more phase detection sensors 410. For example, referring to Figure 5B and 5D , the bimodal or multimodal fluid 401 may include a first fluid component and a second fluid component, and the control system 600 may be configured to determine, for example, one or more phase properties, such as a phase state, of the second fluid component with respect to a liquid saturation curve 510, the liquid saturation curve 510 representing a transition of the second fluid component from a liquid phase to a gas phase. In some embodiments, the control system 600 may be configured to determine whether the second fluid component has a liquid phase state and / or whether the second fluid component has a gas phase state. Additionally or alternatively, the control system 600 may be configured to determine whether the phase state of the second fluid component crosses the liquid saturation curve 510 and / or the proximity of the phase state of the second fluid component with respect to the liquid saturation curve 510. Additionally or alternatively, the control system 600 may be configured to determine one or more phase properties, such as a phase state, of the second fluid component with respect to a critical condensate pressure 514.

[0109] As another example, see Figure 5C and 5D , the bimodal or multimodal fluid 401 may additionally or alternatively include a first fluid component and a third fluid component, and the control system 600 may be configured to determine one or more phase properties, such as phase state, of the third fluid component, for example, with respect to a vapor saturation curve 512, the vapor saturation curve 512 representing the transition of the third fluid component from a gas phase to a liquid phase. In some embodiments, the control system 600 may be configured to determine whether the third fluid component has a gas phase state and / or whether the third fluid component has a liquid phase state. Additionally or alternatively, the control system 600 may be configured to determine whether the phase state of the third fluid component crosses the vapor saturation curve 512 and / or the proximity of the phase state of the third fluid component with respect to the vapor saturation curve 512. Additionally or alternatively, the control system 600 may be configured to determine one or more phase properties, such as phase state, of the third fluid component with respect to a critical condensation temperature 516.

[0110] In some embodiments, control system 600 may be configured to determine one or more phase properties, such as phase state, of a first fluid component relative to bimodal or multimodal fluid 401 based at least in part on one or more phase properties, such as phase state, of a second fluid component and / or a third fluid component of bimodal or multimodal fluid 401. Figure 4 and Figures 5B-5D , the control system 600 can be configured to determine one or more phase properties of the first fluid component based at least in part on one or more sensor outputs 404 from one or more phase detection sensors 410 corresponding to one or more phase properties (such as phase state or phase change) relative to the second fluid component. For example, the phase state or phase change of the second fluid component can be related to the liquid saturation curve 510, such as a phase change of the second fluid component from a liquid phase to a vapor phase. In some embodiments, when the second fluid component undergoes a phase change from a liquid phase to a vapor phase, the first fluid component can have a pericritical state, such as a supercritical state or a near-supercritical state. Additionally or alternatively, the control system 600 can determine one or more phase properties of the first fluid component based at least in part on one or more sensor outputs 404 from one or more phase detection sensors 410 indicating one or more phase properties (such as phase state or phase change) relative to a third fluid component. For example, the phase state or phase change of the third fluid component can be related to the vapor saturation curve 512, such as a phase change of the third fluid component from a vapor phase to a liquid phase. In some embodiments, the first fluid component may have a pericritical state, such as a supercritical state or a near supercritical state, when the third fluid component undergoes a phase change from a gas phase to a liquid phase.

[0111] In some embodiments, the control system 600 can be configured to determine the phase state of the first fluid component based at least in part on whether the second fluid component has a liquid phase or a vapor phase, and / or whether the phase state of the second fluid component crosses the liquid saturation curve 510 and / or the proximity of the phase state of the second fluid component to the liquid saturation curve 510. Additionally or alternatively, the control system 600 can be configured to determine the proximity of the phase state of the first fluid component to the vaporization curve 502 based at least in part on the proximity of the phase state of the second fluid component to the liquid saturation curve 510. For example, the control system 600 can be configured to determine that the first fluid component has a phase state close to the vaporization curve 502 based at least in part on determining that the fluid 401 has a multiphase state corresponding to the first multiphase region 518. The control system 600 can determine that the fluid 401 has a multiphase state corresponding to the first multiphase region 518 based at least in part on one or more sensor outputs 404 indicating that the second fluid component has a vapor phase.

[0112] In some embodiments, the control system 600 can be configured to determine the phase state of the first fluid component based at least in part on whether the third fluid component has a gas phase or a liquid phase, and / or whether the phase state of the third fluid component crosses the vapor saturation curve 512 and / or the proximity of the phase state of the third fluid component to the vapor saturation curve 512. Additionally or alternatively, the control system 600 can be configured to determine the proximity of the phase state of the first fluid component to the vaporization curve 502 based at least in part on the proximity of the phase state of the third fluid component to the vapor saturation curve 512. For example, the control system 600 can be configured to determine that the first fluid component has a phase state close to the vaporization curve 502 based at least in part on determining that the fluid 401 has a multiphase state corresponding to the second multiphase region 520. The control system 600 can determine that the fluid 401 has a multiphase state corresponding to the second multiphase region 520 based at least in part on one or more sensor outputs 404 indicating that the third fluid component has a liquid phase.

[0113] In some embodiments, the control system 600 can use one or more phase properties, such as phase state, of the second fluid component and / or the third fluid component of the bimodal or multimodal fluid 401 as an indicator or warning of one or more phase properties, such as phase state, of the first fluid component. Figure 5D As shown, the second fluid component and / or the third fluid component may be selected to be combined with the first fluid component such that the vaporization curve of the first fluid component may be at least partially surrounded by the liquid saturation curve 510 and / or the vapor saturation curve 512, wherein the liquid saturation curve 510 represents the transition of the second fluid component from the liquid phase to the vapor phase, and the vapor saturation curve 512 represents the transition of the third fluid from the vapor phase to the liquid phase. Additionally or alternatively, the second fluid component and / or the third fluid component may be selected to be combined with the first fluid component such that the critical point of the first fluid component is located within the multiphase region 508 of the multimodal fluid 401.

[0114] For example, the proximity of the phase state of the second fluid component with respect to the liquid saturation curve 510, such as determining that the fluid 401 has a multiphase state corresponding to the first multiphase region 518, can be used as an indicator or warning that the first fluid component has a phase state close to the vaporization curve 502. In some embodiments, at respective corresponding temperatures, a corresponding bubble point in a plurality of bubble points defining at least a portion of the liquid saturation curve 510 of the second fluid component can have a greater pressure than a corresponding vapor point in a plurality of vapor points 504 defining at least a portion of the vaporization curve 502 of the first fluid component. Additionally or alternatively, in some embodiments, the critical condensate pressure 514 of the liquid saturation curve 510 can correspond to a pressure greater than a corresponding pressure of the critical point 506 of the first fluid component.

[0115] As another example, the proximity of the phase state of the third fluid component with respect to the vapor saturation curve 512, such as determining that the fluid 401 has a multiphase state corresponding to the second multiphase region 520, can be used as an indicator or warning that the first fluid component has a phase state close to the vaporization curve 502. In some embodiments, at respective corresponding pressures, respective dew points of the plurality of dew points defining at least a portion of the vapor saturation curve 512 of the third fluid component can have a greater temperature than respective vapor points of the plurality of vapor points 504 defining at least a portion of the vaporization curve 502 of the first fluid component. Additionally or alternatively, in some embodiments, the critical condensation temperature 516 of the vapor saturation curve 512 can correspond to a temperature greater than the corresponding temperature of the critical point 506 of the first fluid component.

[0116] The control system 600 may provide one or more control commands 409 to the one or more controllable components 408 based at least in part on the one or more sensor outputs 404, the one or more sensor outputs 404 indicating, for example, a phase state relative to the second fluid component and / or the third fluid component. For example, in the event that the fluid 401 is determined to have a multiphase state corresponding to the first multiphase region 518, the control system 600 may provide one or more control commands 409 to the one or more controllable components 408, the one or more controllable components 408 being configured to increase the temperature and / or pressure of the fluid 401. In some embodiments, in response to determining that the fluid 401 has a multiphase state corresponding to the first multiphase region 518, the one or more control commands 409 may be configured to cause the one or more controllable components 408 to increase the pressure of the fluid 401 to be above the critical condensate pressure 514 and / or to increase the temperature of the fluid 401 to be above the critical condensate pressure temperature. Additionally or alternatively, the control system 600 may provide one or more control commands 409 to one or more controllable components 408, the one or more controllable components 408 being configured to increase the temperature and / or pressure of the fluid 401 upon determining that the fluid 401 has a multiphase state corresponding to the second multiphase region 520. In some embodiments, in response to determining that the fluid 401 has a multiphase state corresponding to the second multiphase region 520, the one or more control commands 409 may be configured to cause the one or more controllable components 408 to increase the temperature of the fluid 401 to above the critical condensation temperature 516 and / or increase the pressure of the fluid 401 to above the critical condensation temperature pressure.

[0117] In some embodiments, the concentration of the first fluid component may constitute a majority of the total composition of the fluid 401. The second fluid component and / or the third fluid component may constitute a substantial minority of the total composition of the fluid 401. In some embodiments, the first fluid component may represent the majority of the composition of the fluid 401 used by the thermal management system 200 and / or the fuel system 300, when applicable. In some embodiments, the second fluid component and / or the third fluid component may not provide an appreciable effect on the thermal management system 200 and / or the fuel system 300, when applicable, for example, relative to the purpose for which the fluid 401 is used. Additionally or alternatively, the second fluid component and / or the third fluid component may be included in the fluid 401 at a concentration sufficient to serve as a tracer, such as a concentration corresponding to a trace amount sufficient to determine one or more phase properties thereof, such as a phase state. In other embodiments, the second fluid component and / or the third fluid component may be included in the fluid 401 for purposes other than tracers, such as when applicable to serve as a supplement or replacement for a tracer, in order to have a beneficial effect on the thermal management system 200 and / or the fuel system 300. Such a second fluid component and / or the third fluid component may still serve as a tracer.

[0118] In some embodiments, the first fluid component can be included in the fluid 401 in the following amount: from about 30 mol.% to about 100 mol.%, such as from about 50 mol.% to about 100 mol.%, such as from about 80 mol.% to about 100 mol.%, such as from about 80 mol.% to about 90 mol.%, such as from about 90 mol.% to about 95 mol.%, such as from about 95 mol.% to about 99 mol.%, such as from about 99 mol.% to 99.8 mol.%, such as from about 99 mol.% to 99.9 mol.%, such as from about 99 mol.% to 99.998 mol.%, or such as from about 99 mol.% to 99.999 mol.%. In some embodiments, the second fluid component may be included in the fluid 401 in an amount from about 0.001 mol.% to about 50 mol.%, such as from about 1 mol.% to about 20 mol.%, such as from about 1 mol.% to about 10 mol.%, such as from about 1 mol.% to about 5 mol.%, such as from about 0.1 mol.% to about 1 mol.%, or such as from about 0.001 mol.% to about 1 mol.%. In some embodiments, the third fluid component may be included in the fluid 401 in an amount from about 0.001 mol.% to about 50 mol.%, such as from about 1 mol.% to about 20 mol.%, such as from about 1 mol.% to about 10 mol.%, such as from about 1 mol.% to about 5 mol.%, such as from about 0.1 mol.% to about 1 mol.%, or such as from about 0.001 mol.% to about 1 mol.%. In some embodiments, the concentration of the second fluid component or the third fluid component corresponding to a trace amount sufficient to determine one or more phase properties (such as phase state) can be a concentration from about 0.001 mol.% to about 5 mol.%, such as from about 0.1 mol.% to about 1 mol.%, or such as from about 0.001 mol.% to about 1 mol.%.

[0119] Further references Figure 5E , shows another exemplary phase diagram of fluid 401. Figure 5E As shown, the density of fluid 401 can depend on the pressure of fluid 401. In some embodiments, an isothermal change in pressure can produce a significant change in density. Figure 5EPhase diagram 500 shown includes multiple isotherms (T1, T2, T3, T4 and T5) of the first fluid component of fluid 401. As shown, the first fluid component has a vaporization curve 502 defined by multiple vapor points 504. In some embodiments, for example, as indicated by isotherm T3, the isothermal change of the pressure of the first fluid component can produce significant density changes in the pericritical phase, such as in the supercritical phase and / or in the near supercritical phase. For example, at variable density region 522, the first fluid component can show significant density changes due to relative nominal pressure and / or temperature changes. The range of interest of variable density region 522 can be selected at least in part based on one or more phase properties of fluid 401, and / or at least in part based on one or more desired operating conditions of thermal management system 200 and / or fuel system 300.

[0120] In some embodiments, it may be desirable to avoid significant changes in the density of fluid 401. In some embodiments, control system 600 may be configured to determine one or more phase properties of a first fluid component, such as the density of the first fluid component, based at least in part on whether the second fluid component has a liquid phase or a gas phase, and / or whether the second fluid component undergoes a phase change. In some embodiments, the second fluid component may be used as a tracer for determining one or more phase properties of the first fluid component, such as density. Figure 5E As shown, the first fluid component can have a first vaporization curve 502, and the second fluid component can have a second vaporization curve 524. The second fluid component can be selected based at least in part on the relationship between the pressure and density of the first fluid component, and / or based at least in part on the range of interest of the variable density region 522 of the first fluid component. In some embodiments, where applicable, the thermal management system 200 and / or the fuel system 300 can be operated so that the fluid 401 exhibits a first phase 526, and a pressure reduction, such as an isothermal pressure reduction, can cause a phase change, such as a phase transition, of the second fluid component. For example, the second fluid component can undergo a phase change from a liquid phase to a gas phase. The phase change of the second fluid component can be determined by the control system 600 based at least in part on one or more sensor outputs 404 from one or more phase detection sensors 410. The phase change of the second fluid component determined by the control system 600 can provide an indicator or warning that further changes in the phase of the fluid 401, such as further reductions in pressure and / or increases in temperature, may result in a significant change in the density of the first fluid component. For example, a change in the phase of the second fluid component may provide an indication or warning that the phase of the first fluid component may be approaching the variable density region 522 .

[0121] The control system 600 can provide one or more control commands 409 to the one or more controllable components 408 based at least in part on the one or more sensor outputs 404, the one or more sensor outputs 404 providing an indication or warning that the phase state of the first fluid component may be approaching the variable density region 522. For example, the control system 600 can provide one or more control commands 409 to the one or more controllable components 408, the one or more controllable components 408 being configured to increase the temperature and / or pressure of the fluid 401, such as increasing the pressure and / or temperature of the fluid 401 above the critical condensate pressure 514 and / or the critical condensate temperature 516.

[0122] Still reference Figures 5A-5E In some embodiments, fluid 401 may include a first fluid component selected from the following: carbon monoxide, carbon dioxide, ammonia, methane, methanol, ethanol, ethylene, propane, propylene, heptane, 1-octanol, 2-octanol, 2-propanol, difluoromethane, ethane, difluoroethane, tetrafluoroethylene, acetone, nitrous oxide, argon, bromine, neon, hydrogen, oxygen, water, liquid natural gas, kerosene, kerosene-type jet fuel (e.g., Jet A, Jet A-1, JP-5, JP-8). Additionally or alternatively, in some embodiments, fluid 401 may include a second fluid component and / or a third fluid component selected from the above fluids.

[0123] In some embodiments, fluid 401, such as cooling fluid 206, may include a first fluid component and a second fluid component and / or a third fluid component, the first fluid component being carbon dioxide, the second fluid component and / or the third fluid component being selected from the following: carbon monoxide, ammonia, methane, methanol, ethanol, ethylene, propane, propylene, heptane, 1-octanol, 2-octanol, 2-propanol, difluoromethane, ethane, difluoroethane, tetrafluoroethylene, acetone, nitrous oxide, argon, bromine, neon, hydrogen, oxygen, and water. As an example, in some embodiments, the first fluid component may be carbon dioxide, and the second fluid component may be hydrogen. As another example, in some embodiments, the first fluid component may be carbon dioxide, the second fluid component may be nitrous oxide, and the third fluid component may be ethane. As another example, the first fluid component may be carbon dioxide, the second fluid component may be 2-propanol, and the third fluid component may be nitrogen. As another example, the first fluid component may be carbon dioxide, the second fluid component may be difluoromethane, and the third fluid component may be tetrafluoroethylene. As another example, the first fluid component may be argon, and the second fluid component may be oxygen.

[0124] As another example, in some embodiments, fluid 401, such as fuel 306, can include a first fluid component and a second fluid component and / or a third fluid component, the first fluid component being hydrogen, the second fluid component and / or the third fluid component can be selected from the following: carbon monoxide, carbon dioxide, ammonia, methane, methanol, ethanol, ethylene, propane, propylene, heptane, 1-octanol, 2-octanol, 2-propyl alcohol, difluoromethane, ethane, difluoroethane, tetrafluoroethylene, acetone, nitrous oxide, argon, bromine, neon, oxygen, water, hydrogen, methane, liquid natural gas, kerosene and kerosene-type jet fuel (e.g., Jet A, Jet A-1, JP-5, JP-8). As an example, the first fluid component can be hydrogen, and the second fluid component can be neon. As another example, the first fluid component can be 1-octanol, and the second fluid component can be 2-octanol. As another example, the first fluid component can be kerosene, and the second fluid component can be 1-octanol. As another example, the first fluid component can be propane, and the second fluid component can be propylene. As another example, the first fluid component may be kerosene, the second fluid component may be 1-octanol, and the third fluid component may be 2-octanol.

[0125] Reference now Figure 6 , further describing an exemplary control system 600. The exemplary control system 600 may be used to monitor and / or control various features of the power generation system 100, such as various features of the engine 102, the thermal management system 200, the fuel system 300, and / or the pericritical fluid system 400. According to the present disclosure, the control system 600 may be configured to perform any desired control operation. Figure 6 As shown, exemplary control system 600 may include a controller 602 , such as an electric engine controller, a full authority digital engine control (FADEC) device, or the like.

[0126] The controller 602 may include one or more computing devices 604 configured to perform desired control operations. The one or more computing devices 604 may be located locally or remotely relative to the power generation system 100 and / or the engine 102. The control operations may include determining, generating, transmitting, and / or receiving sensor outputs 404 from one or more sensors 402. Additionally or alternatively, the control operations may include, for example, determining, generating, transmitting, and / or receiving fluid monitoring data 406 based at least in part on the sensor outputs 404. Additionally or alternatively, the control operations may include, for example, determining, generating, transmitting, and / or receiving one or more control commands 409 based at least in part on the fluid monitoring data 406 and / or the sensor outputs 404. The control commands 409 may be transmitted to one or more controllable components 408.

[0127] The computing device 604 may be communicatively coupled to the one or more sensors 402 and / or to the one or more controllable components 408. The computing device 604 may include one or more control modules 606 configured to cause the controller 602 to perform one or more control operations, e.g., based at least in part on one or more models, lookup tables, etc.

[0128] The one or more computing devices 604 may include one or more processors 608 and one or more memory devices 610. The one or more processors 608 may include any suitable processing device, such as a microprocessor, a microcontroller, an integrated circuit, a logic device, and / or other suitable processing device. The one or more memory devices 610 may include one or more computer-readable media, including but not limited to non-transitory computer-readable media, RAM, ROM, hard drives, flash drives, and / or other memory devices 610. The one or more control modules 606 may be implemented at least in part by the one or more processors 608 and / or the one or more memory devices 610.

[0129] As used herein, the terms "processor" and "computer" and related terms, such as "processing device" and "computing device", are not limited to those integrated circuits known in the art as computers, but refer broadly to microcontrollers, microcomputers, programmable logic controllers (PLCs), application-specific integrated circuits, and other programmable circuits, and these terms are used interchangeably herein. The memory device 610 may include, but is not limited to, non-transitory computer-readable media, such as random access memory (RAM), and computer-readable non-volatile media, such as hard disk drives, flash memory, and other memory devices. Alternatively, a floppy disk, a read-only compact disk memory (CD-ROM), a magneto-optical disk (MOD), and / or a digital versatile disk (DVD) may also be used.

[0130] As used herein, the term "non-transitory computer-readable medium" is intended to mean any tangible computer-based device implemented in any method or technology for short-term and long-term storage of information (such as computer-readable instructions, data structures, program modules and submodules, or other data in any device). The methods described herein may be encoded as executable instructions embodied in a tangible non-transitory computer-readable medium, including but not limited to a storage device and / or a memory device. Such instructions, when executed by a processor, cause the processor to perform at least a portion of the methods described herein. In addition, as used herein, the term "non-transitory computer-readable medium" includes all tangible computer-readable media, including but not limited to non-transitory computer storage devices, including but not limited to volatile and non-volatile media, and removable and non-removable media, such as firmware, physical and virtual storage, CD-ROM, DVD, and any other digital source such as a network or the Internet, as well as digital means yet to be developed, with the sole exception of transient propagation signals.

[0131] The one or more memory devices 610 may store information accessible by the one or more processors 608, including computer executable instructions 612 that may be executed by the one or more processors 608. The instructions 612 may include any set of instructions that, when executed by the one or more processors 608, cause the one or more processors 608 to perform operations including control operations. The one or more memory devices 610 may store data 614 accessible by the one or more processors 608, such as data associated with the power generation system 100, the engine 102, the thermal management system 200, the fuel system 300, and / or the pericritical fluid system 400. The data 614 may include fluid monitoring data 406. The data 614 may include current or real-time data 614, past data 614, or a combination thereof. The data 614 may be stored in a database 616. The data 614 may also include other data sets, parameters, outputs, information associated with the power generation system 100, the engine 102, the thermal management system 200, the fuel system 300, and / or the pericritical fluid system 400.

[0132] The one or more computing devices 604 may also include a communication interface 618 configured to communicate with various nodes on a communication network 620 via wired or wireless communication links 622. The communication interface 618 may include any suitable components for interfacing with one or more networks, including, for example, transmitters, receivers, ports, controllers, antennas, and / or other suitable components. The communication network 620 may include, for example, a local area network (LAN), a wide area network (WAN), a SATCOM network, a VHF network, a HF network, a Wi-Fi network, a WiMAX network, a gatelink network, and / or any other suitable communication network 620 for transmitting messages to and / or from the computing device 604 via the communication links 622. The communication links 622 of the communication network 620 may include a data bus or a combination of wired and / or wireless communication links.

[0133] The control system 600 may include a management system 624 that is located locally or remotely relative to the power generation system 100 and / or the engine 102. The management system 624 may include a server 626 and / or a data warehouse 628. As an example, at least a portion of the data 614 may be stored in the data warehouse 628, and the server 626 may be configured to transmit the data 614 from the data warehouse 628 to one or more computing devices 604, and / or receive the data 614 from the one or more computing devices 604 and store the received data 614 in the data warehouse 628 for further purposes. The server 626 and / or the data warehouse 628 may be implemented as part of the one or more computing devices 604 and / or as part of the management system 624. The control system 600 may also include a user interface 630 that is configured to allow a user to interact with various features of the control system 600, such as through the communication interface 618. The communication interface 618 may allow the one or more computing devices 604 to communicate with various nodes associated with the power generation system 100 and / or the engine 102 , the management system 624 , and / or the user interface 630 .

[0134] Reference now Figure 7 , further describing an exemplary method according to the present disclosure. As an example, exemplary method 700 may include a method of controlling the phase state of a fluid. Exemplary method 700 may be performed in conjunction with thermal management system 200 and / or fuel system 300. Additionally or alternatively, exemplary method 700 may be performed in conjunction with one or more operations of power generation system 100 and / or engine 102 (such as a turbine engine).

[0135] like Figure 7As shown, the exemplary method 700 may include, at block 702, determining a sensor output 404 generated by one or more sensors 402. The sensor output may correspond to one or more phase properties of the fluid 401. The fluid 401 may be a pericritical fluid, such as a supercritical fluid or a near supercritical fluid. In some embodiments, the fluid 401 may be a cooling fluid 206. The fluid 401, such as the cooling fluid 206, may flow through a cooling circuit 208 of a thermal management system 200. The sensor output 404 may be determined relative to the fluid 401, such as the cooling fluid 206, while the fluid 401, such as the cooling fluid 206, flows through the cooling circuit 208, such as while flowing through one or more cooling conduits 210, or while in a tank or container configured to supply the cooling fluid 206 to the cooling circuit 208. Additionally or alternatively, the fluid 401 may be a fuel 306. The fluid 401, such as the fuel 306, may flow through a fuel path 302 of a fuel system 300. Sensor output 404 may be determined relative to fluid 401 , such as fuel 306 , as fluid 401 flows through fuel path 302 , such as through one or more fuel conduits 304 , or in a fuel tank 308 configured to store fuel 306 .

[0136] At block 704, exemplary method 700 may include generating control commands 409 based at least in part on sensor output 404, control commands 409 being configured to control one or more controllable components 408. In some embodiments, controllable component 408 may be associated with thermal management system 200. In some embodiments, controllable component 408 may be associated with fuel system 300. One or more sensors may include one or more phase detection sensors 410. In some embodiments, one or more phase detection sensors may include acoustic sensors, such as a sonic velocity sensor or a sonic wave sensor. In some embodiments, one or more phase detection sensors may include optical sensors or pressure drop sensors.

[0137] Thus, the presently disclosed systems and methods may be used to monitor and / or control the phase state of a fluid, such as within a pericritical phase, a supercritical phase, and / or a near-supercritical phase.

[0138] As mentioned above, the burner is arranged in the core section to generate combustion gases for driving the turbine in the core section of the turbine engine. The energy and heat generated by the burner are not all used to drive the turbine of the turbine section. Instead, some waste heat is discharged through the jet exhaust nozzle section in the conventional turbine engine. The turbine engine discussed herein includes a steam system, which is used to recover some energy from waste heat by generating steam and driving a steam turbine. Therefore, the steam system includes hot water, which can be used as a heat transfer medium to transfer heat between various fluids and systems of the turbine engine. More specifically, in the embodiment discussed herein, the fuel is heated by water from the steam system. When the fuel is a low-temperature fuel (such as hydrogen fuel), this system may be particularly beneficial. Water can be used to transfer heat to the fuel and heat (or vaporize) the fuel.

[0139] Reference now Figure 8 , Figure 8 8 is a schematic cross-sectional view of turbine engine 710 including steam system 800 taken along longitudinal centerline axis 712 (provided for reference) of turbine engine 710 according to an embodiment of the present disclosure. Figure 8 As shown, turbine engine 710 has an axial direction A (extending parallel to longitudinal centerline axis 712 ) and a radial direction R perpendicular to axial direction A. Generally, turbine engine 710 includes a fan section 714 and a turbine 716 disposed downstream of fan section 714 .

[0140] The turbine 716 includes a housing 718 that is substantially tubular and defines an annular core inlet 720. Figure 8 As shown schematically, the casing 718 encloses in series flow relationship: a compressor section 721, which includes a supercharger or low-pressure compressor (LPC) 722, followed downstream by a high-pressure compressor (HPC) 724; a combustor 726; a turbine section 727, which includes a high-pressure turbine (HPT) 728, followed downstream by a low-pressure turbine (LPT) 730; and one or more core exhaust nozzles 732. A high-pressure (HP) shaft 734 or spool drivingly connects the HPT 728 to the HPC 724 so that the HPT 728 and the HPC 724 rotate in unison. The HPT 728 is drivingly coupled to the HP shaft 734 so that when the HPT 728 rotates, the HP shaft 734 rotates. A low-pressure (LP) shaft 736 drivingly connects the LPT 730 to the LPC 722 so that the LPT 730 and the LPC 722 rotate in unison. LPT 730 is drivingly coupled to LP shaft 736 to rotate LP shaft 736 when LPT 730 rotates. Compressor section 721 , combustor 726 , turbine section 727 , and one or more core exhaust nozzles 732 together define a core air flow path 733 .

[0141] for Figure 8 In the embodiment depicted in FIG. 1 , fan section 714 includes a fan 738 (eg, a variable pitch fan) having a plurality of fan blades 740 coupled to a disk 742 in a spaced-apart manner. Figure 8 As depicted, fan blades 740 extend outwardly from disk 742 generally in a radial direction R. Each fan blade 740 is rotatable relative to disk 742 about a pitch axis P due to fan blade 740 being operably coupled to actuator 744, which is configured to collectively and in unison change the pitch of fan blade 740. Fan blades 740, disk 742, and actuator 744 are rotatable together about longitudinal centerline axis 712 via fan shaft 745, which is powered by LP shaft 736 across a power gearbox (also referred to as gearbox assembly 746). Figure 8 Gearbox assembly 746 is schematically shown. Gearbox assembly 746 includes a plurality of gears for adjusting the speed of fan shaft 745, and therefore the speed of fan 738 relative to LP shaft 736.

[0142] Still reference Figure 8 In an exemplary embodiment of the present invention, the disk 742 is covered by a rotatable fan hub 748 having an aerodynamic profile to facilitate airflow through a plurality of fan blades 740. In addition, the fan section 714 includes an annular fan case or nacelle 750 that circumferentially surrounds at least a portion of the fan 738 and / or the turbine 716. The nacelle 750 is supported relative to the turbine 716 by a plurality of circumferentially spaced outlet guide vanes 752. In addition, a downstream section 754 of the nacelle 750 extends over an outer portion of the turbine 716 to define a bypass airflow channel 756 therebetween. One or more core exhaust nozzles 732 may extend through the nacelle 750 and be formed therein. In this embodiment, the one or more core exhaust nozzles 732 include one or more discrete nozzles that are spaced circumferentially around the nacelle 750. The core exhaust nozzle 732 may use other configurations, including, for example, a single core exhaust nozzle that is annular or partially annular around the nacelle 750.

[0143] During operation of turbine engine 710, a certain amount of air 758 enters turbine engine 710 through inlet 760 of nacelle 750 and / or fan section 714. When a certain amount of air 758 passes through fan blades 740, a first portion of air (bypass air 762) is directed or directed into bypass airflow passage 756, and a second portion of air (core air 764) is directed or directed into an upstream section of core air flow path 733, or more specifically, directed or directed into core inlet 720. The ratio between the first portion of air (bypass air 762) and the second portion of air (core air 764) is referred to as a bypass ratio. In some embodiments, the bypass ratio is greater than 18:1, which is achieved by steam system 800, which will be further described below. The LPC 722 then increases the pressure of the core air 764, generating compressed air 765, and the compressed air 765 is directed through the HPC 724 and further compressed before being directed into the combustor 726, where the compressed air 765 is mixed with fuel 767 and combusted to generate combustion gases 766 (combustion products). One or more stages may be used in each of the LPC 722 and the HPC 724, with each subsequent stage further compressing the compressed air 765. The HPC 724 has a compression ratio greater than 20:1, preferably, a compression ratio in the range of 20:1 to 40:1. The compression ratio is the ratio of the pressure of the last stage of the HPC 724 to the pressure of the first stage of the HPC 724. The compression ratio greater than 20:1 is achieved by the steam system 800, as described in further detail below.

[0144] The combustion gases 766 are directed into and expanded through the HPT 728, where a portion of the heat and / or kinetic energy from the combustion gases 766 is extracted through successive stages of HPT stator vanes 768 coupled to the casing 718 and HPT rotor blades 770 coupled to the HP shaft 734, thereby causing the HP shaft 734 to rotate, thereby supporting the operation of the HPC 724. The combustion gases 766 are then directed into and expanded through the LPT 730. There, a second portion of the heat and / or kinetic energy is extracted via successive stages of LPT stators 772 coupled to the casing 718 and LPT rotor blades 774 coupled to the LP shaft 736, thereby causing the LP shaft 736 to rotate, thereby supporting the operation of the LPC 722 and the rotation of the fan 738 via the gearbox assembly 746. One or more stages may be used in each of the HPT 728 and the LPT 730. The HPC 724 having a compression ratio in the range of 20:1 to 40:1 enables the HPT 728 to have a pressure expansion ratio in the range of 1.5:1 to 4:1, and the LPT 730 to have a pressure expansion ratio in the range of 4.5:1 to 28:1.

[0145] The combustion gases 766 are then directed through one or more core exhaust nozzles 732 of the turbine 716 to provide propulsive thrust. While the core air 764 flows through the core air flow path 733, the bypass air 762 is directed through the bypass airflow passage 756 before being discharged from the fan bypass nozzle 776 of the turbine engine 710, also providing propulsive thrust. The HPT 728, the LPT 730, and the one or more core exhaust nozzles 732 at least partially define a hot gas path 778 for directing the combustion gases 766 through the turbine 716.

[0146] As described above, compressed air 765 (core air 764) is mixed with fuel 767 in combustor 726 to generate a fuel and air mixture, and burns to generate combustion gases 766 (combustion products). Fuel 767 may include any type of fuel for turbine engines, for example, such as sustainable aviation fuel (SAF), including biofuel, JetA or other hydrocarbon fuels. Fuel 767 may also be a hydrogen-based fuel (H2), and although hydrogen-based fuels may include a mixture with hydrocarbon fuels, the fuel 767 used herein is preferably unmixed and is referred to herein as hydrogen fuel. In some embodiments, hydrogen fuel may include substantially pure hydrogen molecules (i.e., diatomic hydrogen). Fuel 767 may also be a cryogenic fuel. For example, when using hydrogen fuel, the hydrogen fuel may be stored in a liquid phase at cryogenic temperatures.

[0147] Turbine engine 710 includes a fuel system 780 for providing fuel 767 to combustor 726. Fuel system 780 includes a fuel tank 782 for storing fuel 767 therein and a fuel delivery assembly 784. Fuel tank 782 may be located on an aircraft (not shown) to which turbine engine 710 is attached. Figure 8764. A single fuel tank 782 is shown in FIG. 764, but the fuel system 780 may include any number of fuel tanks 82 as desired. A fuel delivery assembly 784 delivers fuel 767 from the fuel tank 782 to the combustor 726. The fuel delivery assembly 784 includes one or more lines, conduits, tubes, pipes, etc., which are configured to carry the fuel 767 from the fuel tank 782 to the combustor 726. The fuel delivery assembly 784 also includes a pump 786 to direct the flow of fuel 767 to the combustor 726 through the fuel delivery assembly 784. Steam 878 injected directly into the combustor 726 or upstream of the combustor 726 adds mass flow to the core air 764, so that less core air 764 is required to produce the same amount of work through the turbine section 727. In this way, the pump 786 pumps the fuel 767 from the fuel tank 782 through the fuel delivery assembly 784 and into the combustor 726. Fuel system 780 , and more specifically, fuel tank 782 and fuel delivery assembly 784 , may collectively or individually serve as a fuel source for combustor 726 .

[0148] In some embodiments, for example, when the fuel 767 is hydrogen fuel, the fuel system 780 includes one or more vaporizers 788 (shown in dashed lines) and a metering valve 790 (shown in dashed lines) in fluid communication with the fuel delivery assembly 784. In this example, the hydrogen fuel is stored in the fuel tank 782 as liquid hydrogen fuel. One or more vaporizers 788 heat the liquid hydrogen fuel flowing through the fuel delivery assembly 784. One or more vaporizers 788 are positioned in the flow path of the fuel 767 between the fuel tank 782 and the burner 726, and are located downstream of the pump 786. One or more vaporizers 788 are thermally connected to at least one heat source, for example, a heat source such as waste heat from the turbine engine 710 and / or from one or more systems (not shown) of the aircraft. One or more vaporizers 788 heat the liquid hydrogen fuel and convert the liquid hydrogen fuel into gaseous hydrogen fuel in one or more vaporizers 788. The fuel delivery assembly 784 guides the gaseous hydrogen fuel to the burner 726.

[0149] The metering valve 790 is positioned downstream of the one or more vaporizers 788 and the pump 786. The metering valve 790 receives the hydrogen fuel substantially completely in the gas phase or substantially completely in the supercritical phase. The metering valve 790 provides the fuel flow to the burner 726 in a desired manner. More specifically, the metering valve 790 provides a desired volume of hydrogen fuel at, for example, a desired flow rate to a fuel manifold, which includes one or more fuel injectors that inject the hydrogen fuel into the burner 726. The fuel system 780 can include any components for supplying the fuel 767 from the fuel tank 782 to the burner 726 as desired.

[0150] Turbine engine 710 includes a steam system 800 in fluid communication with one or more core exhaust nozzles 732 and fan bypass nozzles 776. Steam system 800 extracts steam from combustion gases 766 as they flow through steam system 800, as described in further detail below.

[0151] Figure 8 The turbine engine 710 depicted in is only an example. In other exemplary embodiments, the turbine engine 710 can have any other suitable configuration. For example, in other exemplary embodiments, the fan 738 can be configured in any other suitable manner (e.g., as a fixed pitch fan), and can be further supported using any other suitable fan frame configuration. In addition, in other exemplary embodiments, any other suitable number or configuration of compressors, turbines, shafts, or combinations thereof can be provided. In other exemplary embodiments, aspects of the present disclosure can be incorporated into any other suitable turbine engine, for example, such as a turbofan engine, a propeller fan engine, and / or a turboprop engine.

[0152] Fig. 9 A heat transfer system 900 according to the present disclosure Figure 8 Schematic diagram of turbine engine 710 and steam system 800. For clarity of other heat transfer systems discussed herein, heat transfer system 900 of this embodiment will be referred to as first heat transfer system 900. Fig. 9 A turbine engine 710 is schematically shown in FIG. Fig. 9 The steam system 800 includes a boiler 802 , a condenser 804 , a water separator 806 , a water pump 808 , and a steam turbine 810 .

[0153] Boiler 802 is a heat exchanger that vaporizes liquid water from a water source to generate steam or water vapor, as described in further detail below. Thus, boiler 802 is a steam source. In particular, boiler 802 is an exhaust gas-water heat exchanger. Boiler 802 is coupled to hot gas path 778 ( Figure 8 ) and is positioned downstream of the LPT 730. The boiler 802 is also in fluid communication with a water pump 808, as described in further detail below. The boiler 802 may include any type of boiler or heat exchanger for extracting heat from the combustion gases 766 and vaporizing the liquid water into steam or water vapor as the liquid water and combustion gases 766 flow through the boiler 802.

[0154] The condenser 804 is a heat exchanger that further cools the combustion gases 766 as they flow through the condenser 804, as described in further detail below. In particular, the condenser 804 is an air-exhaust heat exchanger. The condenser 804 is in fluid communication with the boiler 802 and, in the present embodiment, is positioned within the bypass airflow channel 756. However, the condenser 804 can be positioned elsewhere and thermally connected to other cooling sources, such as thermally connected to the fuel 767, to transfer heat to the fuel 767, particularly when the fuel 767 is a cryogenic fuel such as hydrogen fuel. The condenser 804 can include any type of condenser for condensing water from the exhaust (e.g., the combustion gases 766).

[0155] The water separator 806 is in fluid communication with the condenser 804 for receiving the cooled exhaust gas (combustion gas 766) having condensed water therein. The water separator 806 is also in fluid communication with one or more core exhaust nozzles 732 and a water pump 808. The water separator 806 includes any type of water separator for separating water from the exhaust gas. For example, the water separator 806 may include a cyclone separator that uses vortex separation to separate water from air. In such an embodiment, the water separator 806 generates a cyclonic flow within the water separator 806 to separate water from the cooled exhaust gas. Fig. 9 , water separator 806 is schematically depicted as being in nacelle 750, but water separator 806 may be located elsewhere within turbine engine 710, such as radially inward of nacelle 750, closer to turbine 716, for example. Water separator 806 may be driven to rotate by one of the engine shafts, such as HP shaft 734 or LP shaft 736. As described above, boiler 802 receives liquid water from a water source to generate steam or water vapor. Fig. 9 In the depicted embodiment, condenser 804 and water separator 806 , either individually or collectively, are sources of water for boiler 802 .

[0156] Water pump 808 is in fluid communication with water separator 806 and boiler 802. Water pump 808 is in fluid communication with condenser 804 via water separator 806. Water pump 808 can be any suitable pump, such as a centrifugal pump or a positive displacement pump. Water pump 808 directs the separated liquid water through boiler 802 where it is converted back into steam. The steam is sent through steam turbine 810 and then injected into core air flow path 733, such as into burner 726.

[0157] In operation, combustion gases 766 (also referred to as exhaust) flow from LPT 730 into boiler 802. Combustion gases 766 transfer heat to water 874 (e.g., in liquid form) within boiler 802, as described in further detail below. Combustion gases 766 then flow into condenser 804. Condenser 804 condenses water 874 (e.g., in liquid form) from combustion gases 766. Bypass air 762 flows through bypass airflow passage 756 and flows through or through condenser 804, and extracts heat from combustion gases 766, cools combustion gases 766, and condenses water 874 from combustion gases 766 to generate exhaust-water mixture 870. Bypass air 762 then is discharged from turbine engine 710 through fan bypass nozzle 776 to generate thrust, as described in detail above. Thus, condenser 804 may be positioned in bypass airflow passage 756.

[0158] The exhaust-water mixture 870 flows into the water separator 806. The water separator 806 separates water 874 from the exhaust in the exhaust-water mixture 870 to generate separated exhaust 872 and water 874. The exhaust 872 is discharged from the turbine engine 710 through one or more core exhaust nozzles 732 to generate thrust, as described in detail above. Thus, the boiler 802, the condenser 804, and the water separator 806 also define a hot gas path 778 (see Figure 8 ) for directing combustion gases 766, exhaust-water mixture 870 and exhaust gas 872 through the steam system 800 of the turbine engine 710.

[0159] The water pump 808 pumps water 874 (e.g., in liquid form) through one or more water lines (e.g., Fig. 9 874 in the boiler 802), and the water 874 flows through the boiler 802. As the water 874 flows through the boiler 802, the combustion gases 766 flowing through the boiler 802 transfer heat to the water 874 to vaporize the water 874 and generate steam 876 (e.g., steam). The steam turbine 810 includes one or more stages of steam turbine blades (not shown) and a steam turbine stator (not shown). The steam 876 is transferred from the boiler 802 through one or more steam lines (e.g., steam). Fig. 9 Steam 876 in the steam turbine 810 (indicated by the arrow) flows into the steam turbine 810, causing the steam turbine blades of the steam turbine 810 to rotate, thereby generating additional work in the output shaft (e.g., one of the core shafts) connected to the turbine blades of the steam turbine 810.

[0160] As described above, the turbine 716 includes a shaft, also referred to as a core shaft, to which the various rotating components of the turbine 716 and other thrust generating components (such as the fan 738) are coupled. Figure 8In the illustrated turbine 716, these core shafts include an HP shaft 734 and an LP shaft 736. The steam turbine 810 is coupled to one of the core shafts of the turbine 716, such as the HP shaft 734 or the LP shaft 736. In the illustrated embodiment, the steam turbine 810 is coupled to the LP shaft 736. When steam 876 flows from the boiler 802 through the steam turbine 810, the kinetic energy of the gas is converted into mechanical work in the LP shaft 736 by the steam turbine 810. The desuperheated steam (as steam 878) leaving the steam turbine 810 is then injected into the core air flow path 733, such as into the combustor 726, upstream of the combustor 726, or downstream of the combustor 726. The steam 878 flows from the steam turbine 810 to the core air flow path 733 through one or more steam lines. The steam 878 injected into the core air flow path 733 adds mass flow to the core air 764, so that less core air 764 is required to produce the same amount of work through the turbine section 727. In this way, the steam system 800 can extract additional work from the heat in the exhaust gas that would otherwise be wasted. The steam 878 injected into the core air flow path 733 is in the range of 20% to 50% of the mass flow through the core air flow path 733 .

[0161] The steam turbine 810 can have a pressure expansion ratio in the range of 2:1 to 6:1. The pressure expansion ratio is the ratio of the pressure at the inlet of the steam turbine 810 to the pressure at the outlet of the steam turbine 810. When the steam system 800 recovers approximately 70% of the water 874 and converts the water 874 into steam 876, the steam turbine 810 can contribute approximately 25% of the power to the LP shaft 736 (or to the HP shaft 734). The steam turbine 810 has a pressure expansion ratio in the range of 2:1 to 6:1, the LPT 730 has a pressure expansion ratio in the range of 4.5:1 to 28:1, and the steam 878 contributes 20% to 50% of the mass flow through the core air flow path 733. The steam turbine 810 expands the steam 876, thereby reducing the energy of the steam 878 leaving the steam turbine 810, and reduces the temperature of the steam 878 to approximately that of the compressed air 765 discharged from the HPC 724 (see Figure 8 ) temperature. This configuration enables the steam 878 to reduce hot spots in the combustor 726 caused by the combustion of the fuel (e.g., particularly when the fuel is supercritical hydrogen or gaseous hydrogen).

[0162] The steam 878 injected into the core air flow path 733 also enables the HPT 728 to have a greater energy output with fewer stages of the HPT 728 than an HPT without the benefit of the present disclosure. For example, the additional mass flow of the steam 878 from passing through the turbine section 727 helps to produce a greater energy output. In this way, the HPT 728 may have only one stage that can continuously drive a higher number of stages of the HPC 724 (e.g., 10, 11, or 12 stages of the HPC 724) due to the higher mass flow (caused by the steam injection) leaving the combustor 726. The steam 878 injected into the core air flow path 733 enables the HPT 728 to have only one stage to drive multiple stages of the HPC 724, without reducing the amount of work produced by the HPT 728 compared to an HPT without the benefit of the present disclosure, while also reducing the weight of the HPT 728 and increasing the efficiency of the HPT 728 compared to an HPT without the benefit of the present disclosure.

[0163] Due to the added mass flow from steam 876, less core air 764 is required (see Figure 8 ), the compression ratio of the HPC 724 can be increased compared to an HPC without the benefit of the present disclosure. In this way, the HPC 724 has a compression ratio greater than 20:1. In some embodiments, the compression ratio of the HPC 724 is in the range of 20:1 to 40:1. Therefore, the compression ratio of the HPC 724 is increased, thereby increasing the thermal efficiency of the turbine engine 710 compared to an HPC and a turbine engine without the benefit of the present disclosure. Further, the HPC 724 can have a reduced throat area due to the added mass flow provided in the turbine 716 by the steam 876, 878 injected into the turbine 716. Therefore, the HPC 724 has a reduced size (e.g., outer diameter) and reduced weight compared to a turbine engine without the benefit of the present disclosure.

[0164] In some embodiments, the HPC stator blades of at least two stages of the HPC 724 are variable stator blades that are controlled to pitch about a pitch axis to change the pitch of the HPC stator blades. In some embodiments, the HPC 724 includes one or more compressor bleed valves that are controlled to open to discharge compressed air 765 from the HPC 724 (see Figure 8) is a portion of the HPC 724. One or more compressor bleed valves are preferably positioned between the fourth stage of the HPC 724 and the last stage of the HPC 724. The HPC stator vanes, which are variable stator vanes, and the one or more compressor bleed valves help balance the air flow (e.g., compressed air 765) through all stages of the HPC 724. This balance, combined with the steam 878 injected into the core air flow path 733, enables the number of stages of the HPC 724 to include ten to twelve stages for a compression ratio greater than 20:1, and preferably in the range of 20:1 to 40:1.

[0165] The additional work extracted by steam system 800 and the steam 878 injected into core air flow path 733 enables turbine 716 ( Figure 8 ) can be reduced in size, thereby increasing the bypass ratio of turbine engine 710. In this manner, turbine engine 710 has a bypass ratio greater than 18:1, preferably, a bypass ratio in the range of 18:1 to 100:1, more preferably, a bypass ratio in the range of 25:1 to 85:1, and most preferably, a bypass ratio in the range of 28:1 to 70:1. In this manner, steam system 800 can achieve an increased bypass ratio, wherein turbine engine 710 can move a greater amount of air through the bypass, reduce the pressure ratio of fan 738, and increase the efficiency of turbine engine 710 as compared to a turbine engine without the benefit of the present disclosure.

[0166] The turbine engine 710 may also include an engine controller 820. The engine controller 820 is configured to operate various aspects of the turbine engine 710, including, in this embodiment, a water pump 808, a fuel bypass valve 914, a selector valve 928, a first heater 932, a second heater 934, and a third heater 936. The engine controller 820 may be a full authority digital engine control (FADEC). In this embodiment, the engine controller 820 is a computing device having one or more processors 812 and one or more memories 814. The processor 822 may be any suitable processing device, including but not limited to a microprocessor, a microcontroller, an integrated circuit, a logic device, a programmable logic controller (PLC), an application specific integrated circuit (ASIC), and / or a field programmable gate array (FPGA). The memory 824 may include one or more computer-readable media, including but not limited to non-temporary computer-readable media, computer-readable non-volatile media (e.g., flash memory), RAM, ROM, a hard drive, a flash drive, and / or other storage devices.

[0167] The memory 824 can store information accessible to the processor 822, including computer-readable instructions that can be executed by the processor 822. The instructions can be any set of instructions or sequence of instructions that, when executed by the processor 822, cause the processor 822 and the engine controller 820 to operate. In some embodiments, the instructions can be executed by the processor 822 so that the processor 822 completes any operation and function that the engine controller 820 is configured for, as will be further described below. The instructions can be software written in any suitable programming language, or can be implemented in hardware. Additionally and / or alternatively, the instructions can be executed in logically and / or virtually separated threads on the processor 822. The memory 824 can further store data accessible to the processor 822.

[0168] The technology discussed herein refers to computer-based systems and actions taken by computer-based systems, as well as information sent to and from computer-based systems. Those of ordinary skill in the art will recognize that the inherent flexibility of computer-based systems allows for various possible configurations, combinations, and division of tasks and functions between and among components. For example, the processes discussed herein can be implemented using a single computing device or a combination of computing devices. Databases, memories, instructions, and applications can be implemented on a single system, or can be distributed on multiple systems. Distributed components can operate sequentially or in parallel.

[0169] The fuel 767 is heated before being injected into the burner 726 ( Figure 8 ) can be used for a variety of reasons. Some fuels, such as hydrocarbon-based fuels, can be heated, for example, to prevent freezing or for performance benefits. Other fuels, such as cryogenic fuels, can be heated and vaporized (converted from a liquid state in which the cryogenic fuel is stored to a vapor state for combustion) before being injected into the combustor 726. As described above, the embodiments discussed herein utilize a heat transfer system to transfer heat from the turbine engine 710 and use that heat to help heat the fuel 767. More specifically, in the embodiments discussed herein, water 874 is used as a heat transfer fluid to transfer heat from the steam system 800 to the fuel 767 in the fuel system 780. The following discussion refers to cryogenic fuels, and more specifically, to hydrogen fuels, but the heat transfer systems discussed herein may be applicable to other fuel systems.

[0170] Fuel tank 782 is configured to at least partially maintain hydrogen fuel in a liquid phase, and is configured to provide hydrogen fuel that is substantially completely in a liquid phase (such as completely in a liquid phase) to fuel delivery assembly 784. Fuel tank 782 has a fixed volume and contains a certain volume of hydrogen fuel in a liquid phase (e.g., liquid hydrogen fuel). When fuel tank 782 provides hydrogen fuel that is substantially completely in a liquid phase to fuel delivery assembly 784, the volume of liquid hydrogen fuel in fuel tank 782 decreases, and the remaining volume in fuel tank 782 is composed of, for example, hydrogen that is substantially completely in a gas phase (gaseous hydrogen). As used herein, the term "substantially completely" used to describe the phase of hydrogen fuel means that at least 99% of the mass of the described portion of hydrogen fuel is in the phase, such as at least 97.5%, such as at least 95%, such as at least 92.5%, such as at least 90%, such as at least 85%, or such as at least 75% of the mass of the described portion of hydrogen fuel is in the phase.

[0171] In order to store hydrogen fuel that is substantially completely in liquid phase, hydrogen fuel is stored in fuel tank 782 at very low (cryogenic) temperature, and therefore, fuel tank 782 may also be referred to as cryogenic fuel tank in this article. For example, hydrogen fuel may be stored in fuel tank 782 at about -253 degrees Celsius (twenty Kelvin) or lower at atmospheric pressure, or stored in fuel tank 782 at other temperatures and pressures to maintain hydrogen fuel that is substantially completely in liquid phase. In some embodiments, hydrogen fuel may be stored in fuel tank 782 at a temperature of -259 degrees Celsius (fourteen Kelvin) to -243 degrees Celsius (thirty Kelvin), and more preferably at a temperature of -253 degrees Celsius (twenty Kelvin) to -243 degrees Celsius (thirty Kelvin). In order to store hydrogen fuel in liquid phase, fuel tank 782 stores and maintains hydrogen at low temperature, and may be a cryostat. Therefore, fuel tank 782 may be, for example, a double-walled box, including an inner container (e.g., an inner cryogenic liquid tank) and an outer container (e.g., a vacuum container). The inner container may be positioned within the outer container, and a gap may be formed between the inner container and the outer container. The gap may be under vacuum conditions to provide thermal isolation for the inner container. The gap may include void space or be completely void space, but alternatively, for example, the gap may include a multi-layer insulator (MLI), such as aluminized polyester film (e.g., aluminized polyester film). ).

[0172] Fig. 9The turbine engine 710 shown in the figure includes a first heat transfer system 900, which can be used to transfer heat from the steam system 800 to the fuel system 780. The first heat transfer system 900 includes a fuel heat exchanger 910 connected to the fuel delivery assembly 784 fluid. The fuel heat exchanger 910 of this embodiment is a fuel / water heat exchanger, and when the fuel 767 flows from the fuel tank 782 to the burner 726, the fuel 767 absorbs (receives) heat from the water 874 of the steam system 800 and is heated. In some embodiments, the fuel heat exchanger 910 can be one of the vaporizers 788 discussed above. Although the fuel heat exchanger 910 can also be a supplement to the vaporizer 788. The fuel heat exchanger 910 can be any suitable heat exchanger, including, for example, a plate heat exchanger or a tubular heat exchanger, such as a shell and tube heat exchanger. Therefore, the fuel heat exchanger 910 includes a fluid flow path for a heat transfer fluid.

[0173] There may be situations where it is not desirable to heat the fuel 767 with the water 874 or to remove heat from the water 874. Such situations include startup, as discussed further below, when the water 874 is not hot enough to flow through the fuel heat exchanger 910 and heat the fuel 767. Therefore, the fuel system 780 of the present embodiment includes a fuel bypass line 912 (i.e., a fuel bypass flow path) that fluidly connects a portion of the fuel delivery assembly 784 upstream of the fuel heat exchanger 910 with a portion of the fuel delivery assembly 784 downstream of the fuel heat exchanger 910, thereby bypassing the fuel heat exchanger 910. Therefore, the fuel system 780 is selectively operable to redirect the fuel 767 or a portion thereof and bypass the fuel heat exchanger 910. The fuel bypass line 912 includes a fuel bypass valve 914, which is located in the fuel bypass line 912 and the fuel delivery assembly 784. The fuel bypass valve 914 is operable to open and direct the fuel 767 through the fuel bypass line 912, bypassing the fuel heat exchanger 910, and thus, the fuel bypass valve 914 selectively operates the fuel system 780 to bypass the fuel heat exchanger 910. The fuel bypass valve 914 can be any suitable valve, including a three-way valve. The fuel bypass valve 914 can also be a flow control valve (e.g., a proportional control valve) that directs a portion of the fuel 767 and / or controls the flow of the fuel 767 through the fuel heat exchanger 910 and the fuel bypass line 912. The fuel bypass valve 914 can be any suitable valve, including, for example, an electrically operable valve, a hydraulically operable valve, or a pneumatically operable valve. When the fuel bypass valve 914 is hydraulically operable, the hydraulic fluid can be a suitable fluid of the turbine engine 710, including, for example, the fuel 767, lubricating oil, etc.

[0174] The first heat transfer system 900 includes a heat transfer loop 920 that thermally couples the condenser 804 to the fuel heat exchanger 910 to transfer heat from the condenser 804 using the fuel heat exchanger 910. More specifically, water 874 flows through the heat transfer loop 920 to transfer heat from the condenser 804 to the fuel heat exchanger 910. The heat transfer loop 920 includes a supply line 922. The supply line 922 is fluidly connected to a line that transports the water 874 between the water pump 808 and the boiler 802. Thus, the supply line 922 is fluidly connected downstream of the water pump 808 and upstream of the boiler 802. As described above, the water pump 808 directs the separated liquid water 874 through the boiler 802, and by virtue of the position of the water pump 808 relative to the supply line 922, the water pump 808 can also be used to direct the flow of water 874 through the first heat transfer system 900. Thus, water 874 flows from water pump 808 to fuel heat exchanger 910 through supply line 922 .

[0175] Although the exhaust-water mixture 870 has been cooled to a temperature low enough to condense water from the combustion gases 766, the temperature of the water 874 may still be relatively high, such as from one hundred degrees Fahrenheit (100°F) (thirty-eight degrees Celsius (38°C)) to two hundred and twelve degrees Fahrenheit (212°F) (one hundred degrees Celsius (100°C)), and more likely, from one hundred and fifty degrees Fahrenheit (150°F) (sixty-six degrees Celsius (66°C)) to two hundred and twelve degrees Fahrenheit (212°F) (one hundred degrees Celsius (100°C)). In particular, when the fuel is a cryogenic liquid fuel (such as hydrogen fuel) stored at a cryogenic temperature in the fuel tank 782, these temperatures are still higher than the temperature of the fuel 767. Therefore, as the water 874 flows through the fuel heat exchanger 910, heat from the water 874 is transferred from the water 874 to the fuel 767, and the fuel 767 absorbs heat from the water 874. Thus, the fuel 767 is heated and may be vaporized by heat from the water 874, and the water 874 is cooled.

[0176] The water 874 then flows from the fuel heat exchanger 910 back to the boiler 802, where it can then be heated to form steam 876 in the manner discussed above. Thus, the first heat transport system 900 includes a return line 926 through which the water 874 flows from the fuel heat exchanger 910 into the boiler 802. Fig. 9 802 , the return line 926 is shown as being fluidly connected to the boiler 802 , but alternatively, the return line 926 may be fluidly connected to a water line upstream of the boiler 802 , such as a water line directly connecting the water pump 808 and the boiler 802 .

[0177] The water 874 that has been cooled by the fuel 767 can be preheated before flowing into the boiler 802. A preheating heat exchanger can be located in the return line 926 to preheat the water 874. In this embodiment, the preheating heat exchanger is the condenser 804. The first heat transport system 900 includes an intermediate return line 924 that fluidly connects the fuel heat exchanger 910 to the flow channel within the condenser 804, and the return line 926 that fluidly connects the flow channel of the condenser 804 to the boiler 802. Therefore, the water 874 can be preheated by the combustion gas 766 flowing through the condenser 804 before being introduced into the boiler 802.

[0178] The heat transfer loop 920 can be selectively operated so that the heat transfer loop 920 can be isolated or so that only a portion of the water 874 flows through the heat transfer loop 920. The heat transfer loop 920 includes a selector valve 928, which is located in the water line between the water pump 808 and the boiler 802. The selector valve 928 is operable to open and direct the water 874 through the supply line 922 and to the fuel heat exchanger 910. The selector valve 928 can be any suitable valve, including a three-way valve. The selector valve 928 can also be a flow control valve (e.g., a proportional control valve) that directs a portion of the water 874 and / or controls the flow of the water 874 through the heat transfer loop 920. As with the fuel bypass valve 914 discussed above, the selector valve 928 can be an electrically operable valve, a hydraulically operable valve, or a pneumatically operable valve.

[0179] Water 874 is used as the heat transfer medium of the heat transfer loop 920 of the present embodiment. To prevent the water 874 from freezing, the first heat transfer system 900 includes a plurality of heaters, the plurality of heaters including a first heater 932, a second heater 934, and a third heater 936. Any suitable heater may be used, including, for example, one or more resistive heaters, catalytic heaters, or combustion furnaces. In certain environments, startup of the turbine engine 710 may occur at cold temperatures (e.g., as low as negative forty degrees Fahrenheit (-40°F) (negative forty degrees Celsius (-40°C))). At startup, the turbine engine 710, and more specifically, the combustor 726 has not yet begun operation, and therefore, the hot gas path 778 ( Figure 8) are closer to ambient conditions. With components of the steam system 800 and / or the first heat transfer system 900 at these cold temperatures, the water 874 within the steam system 800 and the first heat transfer system 900 may freeze when the water 874 comes into contact with these components. To avoid such freezing, the heaters 932, 934, 936 are used to increase the temperature of these components to above the freezing point of water (thirty-two degrees Fahrenheit (32°F) (zero degrees Celsius (0°C))), such as from thirty-five degrees Fahrenheit (35°F) (one degree Celsius (1°C)) to fifty degrees Fahrenheit (50°F) (ten degrees Celsius (10°C)). The first heater 932 can be located in the fuel heat exchanger 910 and used to increase the temperature of the fuel heat exchanger 910. The second heater 934 can be located in the water separator 806 and used to increase the temperature of the water separator 806. The third heater 936 can be located in the condenser 804 and used to increase the temperature of the condenser 804.

[0180] One or more temperature sensors (e.g., a first temperature sensor 940, a second temperature sensor 942, a third temperature sensor 944, and a fourth temperature sensor 946) may be used with the heaters 932, 934, 936 to provide input to operate the heaters 932, 934, 936 to heat the components, as discussed above. The second temperature sensor 942 may be located within the fuel heat exchanger 910 and used to detect the temperature of the fuel heat exchanger 910. The second temperature sensor 942 may be communicatively coupled to the first heater 932 and, therefore, provide input to operate the first heater 932 based on the temperature sensed by the second temperature sensor 942. Similarly, the fourth temperature sensor 946 is located within the condenser 804 and may be used to detect the temperature of the condenser 804. The third heater 936 may be operated to increase the temperature of the condenser 804 based on the temperature sensed by the fourth temperature sensor 946. Thus, the first heater 932 and the third heater 936 may be operated to increase the temperature of the fuel heat exchanger 910 and the third heater 936, respectively, thereby increasing the temperature of these components, as discussed above.

[0181] When the temperature of the fuel heat exchanger 910 and the condenser 804 has increased sufficiently, the water 874 can be circulated through the water line and the heat transfer loop 920 that connects the water separator 806 to the boiler 802. The water 874 can be initially heated by the second heater 934 within the water separator 806. The first temperature sensor 940 can be located in the supply line 922 to determine the temperature of the supply line 922 and the water 874 flowing therein. Similarly, the third temperature sensor 944 can be located in the water line located downstream of the water separator 806 and upstream of the boiler 802 to determine the temperature of the water line and the water 874 flowing therein. The second heater 934 located in the water separator 806 can be used to increase the temperature of the water separator 806 and also increase the temperature of the water 874 before the water 874 flows through the steam system 800 and the first heat transport system 900. Thus, the first temperature sensor 940 and the third temperature sensor 944 may be used to monitor the temperature of the water 874 and provide input to operate the heaters 932 , 934 , 936 based on these temperatures.

[0182] When the fuel 767 is a cryogenic fuel, during startup operation, the fuel 767 may be directed through the fuel bypass line 912 to avoid cooling the fuel heat exchanger 910 and eliminate the effects of the first heater 932. When the temperature of the water 874 detected by, for example, the first temperature sensor 940 increases, the fuel bypass valve 914 may be operated to slowly introduce the fuel 767 into the fuel heat exchanger 910.

[0183] Since it may be below freezing temperatures, the method of starting the turbine engine 710 can begin with the steam injection system shut down. The fuel bypass valve 914 can be positioned to bypass the fuel heat exchanger 910 and cause the fuel 767 to flow through the fuel bypass line 912. The selector valve 928 is also positioned to direct all of the water 874 to the boiler 802 and bypass the heat transfer loop 920. The turbine engine 710 is started with the water pump 808 shut down. The turbine engine 710 is brought to idle using, for example, a starter motor. The temperature of the fuel heat exchanger 910 is measured using a second temperature sensor 942. If the temperature of the fuel heat exchanger 910 is not above the heater threshold temperature, the first heater 932 is used to heat the fuel heat exchanger 910 to the temperature discussed above. Preferably, the heater threshold temperature is greater than the freezing temperature of water (i.e., greater than thirty-two degrees Fahrenheit (32°F) (zero degrees Celsius (0°C))), such as from thirty-five degrees Fahrenheit (35°F) (one degree Celsius (1°C)) to fifty degrees Fahrenheit (50°F) (ten degrees Celsius (10°C)). If (or once) the temperature of the fuel heat exchanger 910 reaches the heater threshold temperature, the water pump 808 and / or the selector valve 928 are regulated (controlled) to send at least some of the water 874 through the heat transfer loop 920.

[0184] Once the water 874 flowing through the fuel heat exchanger 910 is above the minimum threshold value measured by the first temperature sensor 940, the fuel bypass valve 914 is used to regulate (i.e., control) the flow of the fuel 767 into the fuel heat exchanger 910. The fuel bypass valve 914 can be used to regulate the fuel 767 to maintain the water 874 above the minimum threshold temperature. Before the fuel 767 is introduced into the fuel heat exchanger, the water 874 is preferably at least eighty degrees Fahrenheit (80°F) (twenty-six degrees Celsius (26°C)) to prevent the water 874 from freezing instantly, and thus the minimum threshold value can be, for example, eighty degrees Fahrenheit (80°F) (twenty-six degrees Celsius (26°C)) or higher, preferably, such as from eighty degrees Fahrenheit (80°F) (twenty-six degrees Celsius (26°C)) to one hundred sixty degrees Fahrenheit (160°F) (seventy-one degrees Celsius (71°C)). A water 874 temperature at the inlet of the fuel heat exchanger 910 of one hundred sixty degrees Fahrenheit (160°F) (seventy one degrees Celsius (71°C)) or less minimizes potential foil boiling at high altitudes. As the temperature of the water 874 increases due to operation of the turbine engine 710, the selector valve 928 and / or the water pump 808 may be controlled to increase the flow of water 874 through the first heat transfer system 900 to a maximum position. As the flow of water 874 through the heat transfer loop 920 increases, the fuel bypass valve 914 may be used to regulate the flow of fuel 767 into the fuel heat exchanger 910. The flow of water 874 and the flow of fuel 767 increase until the turbine engine 710 reaches full idle operation.

[0185] Once the combustor 726 generates the combustion gases 766, the condenser 804 and the water separator 806 will flow these hot combustion gases 766 therethrough, thereby providing heat to these components. During the startup process, particularly for startups when the turbine engine 710 has been exposed to subfreezing temperatures while shut down, the second heater 934 and the third heater 936 can be used to heat the water separator 806 and the condenser 804, respectively, to a temperature above the freezing point of water (thirty-two degrees Fahrenheit (32°F)), such as from thirty-five degrees Fahrenheit (35°F) (one degree Celsius (1°C)) to fifty degrees Fahrenheit (50°F) (ten degrees Celsius (10°C)). Therefore, the method of starting the turbine engine 710 can also include using a fourth temperature sensor 946 to measure the temperature of the condenser 804. If the temperature of the condenser 804 is not above the heater threshold temperature (as discussed above), the fourth temperature sensor 946 is used to heat the condenser 804 to the temperature discussed above. If (or once) the temperature of condenser 804 reaches the heater threshold temperature, turbine engine 710 may be started, such as by igniting fuel 767 in combustor 726. Once combustor ignition has occurred, second heater 934 and third heater 936 may be turned off. In some embodiments, a third temperature sensor 944 positioned in a water line fluidly connecting water separator 806 to water pump 808 may be used to control second heater 934 during startup and determine when to turn second heater 934 off.

[0186] The method of shutting down the turbine engine 710 may include decelerating the turbine engine 710 to ground idle thrust. Then, the fuel bypass valve 914 is positioned around the fuel heat exchanger 910 and bypasses all fuel 767 through the fuel bypass line 912. Then, the selector valve 928 is positioned to direct all water 874 directly to the boiler 802, bypassing the heat transfer loop 920. Then, the water pump 808 is turned off. With the water pump 808 turned off, the combustion gases 766 continue to flow through the hot gas path 778, allowing the condenser 804 and the water separator 806 to be dried at a temperature above freezing. Once dry, the pump 786 that pumps the fuel 767 from the fuel tank 782 through the fuel delivery assembly 784 can be turned off to shut down the turbine engine 710.

[0187] As described above, engine controller 820 is configured to operate various aspects of turbine engine 710, including, in this embodiment, the components described in the above method. Therefore, in some embodiments, engine controller 820 is configured to perform the steps of the method discussed above. More specifically, for example, processor 822 can execute a sequence of instructions stored on memory 824 to operate turbine engine 710 in the manner described above.

[0188] Fig.10is a heat transfer system 902 according to the present disclosure Figure 8 Schematic diagram of turbine engine 710 and steam system 800. For clarity of other heat transfer systems discussed herein, heat transfer system 902 of this embodiment will be referred to as second heat transfer system 902. Second heat transfer system 900 is similar to the above referenced Fig. 9 The same reference numerals will be used for components of the second heat transport system 902 that are the same or similar to the components of the first heat transport system 900 discussed above. The above description of these components also applies to this embodiment, and a detailed description of these components is omitted here.

[0189] Reference above Fig. 9 The water 874 in the heat transfer loop 920 of the first heat transfer system 900 discussed is directed between the fuel heat exchanger 910 and the condenser 804. However, the water 874 can be directed to other components to transfer heat to these components or receive heat from these components. Therefore, the heat transfer loop 920 of the second heat transfer system 902 includes an additional heat exchanger. In this embodiment, the additional heat exchanger is a water / oil heat exchanger 950. The water / oil heat exchanger 950 is positioned in the return line 926 downstream of the condenser 804 and upstream of the boiler 802. The water / oil heat exchanger 950 can be located at other positions within the heat transfer loop 920, including being fluidly connected to the intermediate return line 924 downstream of the fuel heat exchanger 910 and upstream of the condenser 804. After flowing through the condenser 804, the water 874 is further heated by extracting heat (i.e., absorbing heat) from the oil (such as lubricating oil) flowing through the turbine engine 710. Thus, water / oil heat exchanger 950 may be used as a heat sink (e.g., an oil coil) for lubricating oil to cool lubricating oil flowing through turbine engine 710. Other (or additional) engine components may also include electrical devices, including motors, generators, and controllers. The additional heat exchanger may be a heat exchanger or heat sink for turbine engine 710 or other systems of the aircraft, such as, for example, a cooler for an environmental control system (ECS) of the aircraft.

[0190] Fig.11 is a heat transfer system 904 according to the present disclosure Figure 8 Schematic diagram of turbine engine 710 and steam system 800. For clarity of other heat transfer systems discussed herein, heat transfer system 904 of this embodiment will be referred to as third heat transfer system 904. Third heat transfer system 904 is similar to the above referenced Fig. 9 The same reference numerals will be used for components of the third heat transport system 904 that are the same or similar to the components of the first heat transport system 900 discussed above. The above description of these components also applies to this embodiment, and a detailed description of these components is omitted here.

[0191] A single heat transfer medium or working fluid (water 874) is used in the first heat transfer system 900. When the fuel 767 is at a cryogenic temperature and the water 874 is at a relatively hot temperature (as discussed above), it may be advantageous to use an additional working fluid (e.g., an intermediate heat transfer medium). Therefore, the third heat transfer system 904 of the present embodiment includes an intermediate heat transfer loop 960 through which the intermediate heat transfer medium flows. When the fuel 767 is at a cryogenic temperature, the intermediate heat transfer medium may be a fluid other than water, and suitable intermediate heat transfer media include, for example, helium, nitrogen, or carbon dioxide. When carbon dioxide is used, the carbon dioxide is preferably gaseous carbon dioxide, and more preferably supercritical carbon dioxide.

[0192] Instead of being directed to the fuel heat exchanger 910, the water 874 flows through the heat transfer loop 920 (referred to as the first heat transfer loop or the water heat transfer loop in this embodiment) into the intermediate heat exchanger 970. The intermediate heat exchanger 970 may be similar to the fuel heat exchanger 910 discussed above, but instead of having the fuel 767 flow therethrough, an intermediate heat transfer medium flows through the intermediate heat exchanger 970 and heat from the water 874 is transferred from the water 874 and absorbed by the intermediate heat transfer medium.

[0193] The intermediate heat transfer loop 960 includes a supply line 962 that fluidly connects the intermediate heat exchanger 970 with the fuel heat exchanger 910. The intermediate heat transfer medium flows from the intermediate heat exchanger 970 to the fuel heat exchanger 910 after being heated in the fuel heat exchanger 910. In the fuel heat exchanger 910, heat is transferred from the intermediate heat transfer medium to the fuel 767 in a similar manner as discussed above for the water 874. The intermediate heat transfer loop 960 also includes a return line 964 that fluidly connects the fuel heat exchanger 910 with the intermediate heat exchanger 970. After transferring heat to the fuel 767 and being cooled, the intermediate heat transfer medium flows from the fuel heat exchanger 910 to the intermediate heat exchanger 970 through the return line 964.

[0194] The intermediate heat transfer loop 960 includes an intermediate fluid pump 966. The intermediate fluid pump 966 directs the flow of the intermediate heat transfer medium between the fuel heat exchanger 910 and the intermediate heat exchanger 970 through the intermediate heat transfer loop 960. The intermediate fluid pump 966 can be located at any suitable position within the intermediate heat transfer loop 960, but in the present embodiment, the intermediate fluid pump 966 is located in the return line 964.

[0195] The turbine engine 710 of the embodiment discussed herein includes a steam system 800. The turbine engine 710 also includes a heat transfer system that can be used to transfer heat from the steam system 800 to the fuel 767 and heat (or vaporize) the fuel 767. The use of the water 874 and heat transfer system discussed herein has the advantage of reducing the size of the boiler 802 by raising the temperature of the water 874 at the inlet of the boiler 802. If the cryogenic fuel is heated by being directed through the condenser 804, the condenser 804 will be at risk of freezing due to the extreme cold of the cryogenic fuel. The use of the water 874 and heat transfer system discussed herein mitigates the risk of freezing in the condenser 804, where ice may block the bypass air 762 from the fan 738, thereby reducing thrust.

[0196] Reference now Fig.12 , another exemplary embodiment of a turbine engine 7100 of the present disclosure is provided. Fig.12 The turbine engine 7100 can be used in the same manner as in the above example reference Fig. 9 The one or more gas turbine engines 800 described are constructed in substantially the same manner.

[0197] For example, the gas turbine engine 7100 includes a first heat transport system 900. However, because the first heat transport system 900 may be fluidly separated from the water / steam flow through the gas turbine engine 100, the heat transfer fluid of the first heat transport system 900 may not be water.

[0198] For the illustrated embodiment, the first heat transport system 900 includes a heat transfer loop 920 that thermally couples the condenser 804 with the fuel heat exchanger 910 to transfer heat from the condenser 804 with the fuel heat exchanger 910. More specifically, a heat transfer fluid flows through the heat transfer loop 920, and the heat transfer loop 920 is fluidly connected to the fuel heat exchanger 910 and the condenser 804 to circulate the heat transfer fluid between the fuel heat exchanger 910 and the condenser 804. The condenser 804 includes a fluid flow path for the heat transfer fluid, and when the heat transfer fluid flows through the condenser 804, the heat transfer fluid is heated by the combustion gas 766 that also flows through the condenser 804. Therefore, the heat transfer fluid R absorbs heat from the combustion gas 766.

[0199] The heat transfer loop 920 includes a supply line 922. The supply line 922 is fluidly connected to each of the condenser 804 and the fuel heat exchanger 910. The heat transfer fluid, after being heated by the combustion gases 766, flows from the condenser 804 through the supply line 922 to the fuel heat exchanger 910, where heat is transferred from the heat transfer fluid to the fuel 767, as discussed above.

[0200] The heat transfer loop 920 also includes a return line 924 that is fluidly connected to each of the fuel heat exchanger 910 and the condenser 804. The heat transfer fluid flows from the fuel heat exchanger 910 to the condenser 804 through the return line 924 after transferring heat to the fuel 767, where heat is transferred from the combustion gases 766 to the heat transfer fluid as discussed above.

[0201] The heat transfer loop 920 also includes a heat transfer fluid pump 927. The heat transfer fluid pump 927 directs the heat transfer fluid flow through the heat transfer loop 920 between the fuel heat exchanger 910 and the condenser 804. The heat transfer fluid pump 927 can be located at any suitable location within the heat transfer loop 920, but in the present embodiment, the heat transfer fluid pump 927 is located in the supply line 922. Any pump suitable for heat transfer fluids can be used, such as, for example, a positive displacement pump, a centrifugal pump, or a compressor. The heat transfer fluid can be a suitable working fluid for transferring heat between the combustion gases 766 and the environment of the fuel 767. Suitable heat transfer fluids include, for example, helium, nitrogen, supercritical carbon dioxide, silicon-based heat transfer fluids (e.g., Syltherm TM 800 or Syltherm TM XLT, each produced by Dow of Midland, Michigan, USA) or sulfur hexafluoride.

[0202] Fig.13 According to the present disclosure, there is a heat transfer system 901 Figure 8 Schematic diagram of turbine engine 710 and steam system 800. For clarity of other heat transfer systems discussed herein, heat transfer system 901 of this embodiment will be referred to as second heat transfer system 901. Second heat transfer system 901 is similar to the above referenced Fig.12 The same reference numerals will be used for components of the second heat transport system 901 that are the same or similar to the components of the first heat transport system 900 discussed above. The above description of these components also applies to this embodiment, and a detailed description of these components is omitted here.

[0203] Reference now Fig.13 , another exemplary embodiment of the present disclosure is provided. Fig.13 An exemplary embodiment may be described with Fig.12 The exemplary embodiments of the present invention are constructed in a similar manner, and the same or similar numerals may refer to the same or similar parts.

[0204] However, Fig.13910. The embodiment of the fuel system 780 includes a fuel bypass line 912 (i.e., a fuel bypass flow path) that fluidly connects a portion of the fuel delivery assembly 784 upstream of the fuel heat exchanger 910 with a portion of the fuel delivery assembly 784 downstream of the fuel heat exchanger 910, thereby bypassing the fuel heat exchanger 910. Thus, the fuel system 780 is selectively operable to redirect the fuel 767 or a portion thereof and bypass the fuel heat exchanger 910. The fuel bypass line 912 includes a fuel bypass valve 914 located in the fuel bypass line 912 and the fuel delivery assembly 784.

[0205] Reference now Fig.14 , another exemplary embodiment of the present disclosure is provided. Fig.14 An exemplary embodiment may be described with Fig.12 The exemplary embodiments of the present invention are constructed in a similar manner, and the same or similar numerals may refer to the same or similar parts.

[0206] However, for Fig.14 In an embodiment of the present invention, the heat transfer loop 920 of the gas turbine engine 7100 further includes an accumulator 931. The accumulator 931 can be used to regulate the volume of the heat transfer fluid within the heat transfer loop 920 and / or the pressure of the heat transfer fluid within the heat transfer loop 920. The accumulator 931 may be particularly advantageous when the heat transfer fluid is a heat transfer fluid that has a tendency to change phase under the operating conditions of the heat transfer loop 920 discussed herein. The accumulator 931 can be used to regulate the pressure of the heat transfer fluid and maintain the heat transfer fluid in a desired phase.

[0207] For example, supercritical carbon dioxide is one such heat transfer fluid that has a tendency to change phases, and the accumulator 931 can be used to regulate the pressure of the heat transfer fluid in the heat transfer loop 920 to maintain the carbon dioxide in a supercritical state. The accumulator 931 includes a fluid reservoir 933, such as a tank that is fluidly connected to the heat transfer loop 920 via an accumulator line 934. The accumulator 931 can be fluidly connected via the accumulator line 934 at any suitable location within the heat transfer loop 920, but in the present embodiment, the accumulator 931 is fluidly connected to the return line 924.

[0208] The accumulator 931 may be a variable volume accumulator including, for example, a diaphragm 937 or other suitable movable component to change the volume of the fluid reservoir 933. The diaphragm 937 may be moved by a moving mechanism 938. For example, the diaphragm 937 may be actively controlled by an actuator as the moving mechanism 938 to move the diaphragm 937. Suitable actuators include, for example, electric actuators or hydraulic actuators. When a hydraulic actuator is used, the hydraulic fluid may be a suitable fluid of the turbine engine 710, including, for example, fuel 767, lubricating oil, etc. When the diaphragm 937 is actively controlled, a pressure sensor or other sensor is located within the heat transfer loop 920 and is communicatively connected to the engine controller 820. The engine controller 820 communicates and is operatively connected to the moving mechanism 938, and the engine controller 820 is configured to operate the moving mechanism 938 and move the diaphragm 937 based on input received from the sensor. Alternatively, the diaphragm 937 can be passively controlled, in which case the moving mechanism 938 is a passive mechanism (e.g., a biasing member) such as a spring or bellows that exerts a desired force (i.e., a biasing force) on the diaphragm 937 so that the volume of the accumulator 931 increases in response to an increase in the pressure of the heat transfer fluid in the heat transfer loop 920, and decreases in response to a decrease in the pressure of the heat transfer fluid in the heat transfer loop 920.

[0209] Fig.15A is a heat transfer system 903 according to the present disclosure Figure 8 Schematic diagram of turbine engine 710 and steam system 800. For clarity of other heat transfer systems discussed herein, heat transfer system 903 of this embodiment will be referred to as fourth heat transfer system 903. Fourth heat transfer system 903 is similar to the above reference Fig.12 The same reference numerals will be used for components of the fourth heat transport system 903 that are the same or similar to the components of the first heat transport system 900 discussed above. The above description of these components also applies to this embodiment, and a detailed description of these components is omitted here.

[0210] The heat transfer fluid and heat transfer loop 920 can also be used to transfer heat to or from other components of the turbine engine 710. The temperature of the heat transfer fluid leaving the condenser 804 can be, for example, less than two hundred and twelve degrees Fahrenheit (212°F), and therefore can be suitable for use as a heat sink for other systems (such as lubricating oil systems) within the turbine engine 710. Therefore, the heat transfer loop 920 is fluidly connected to another device or system, and more specifically, to the secondary heat exchanger 941 of the other device or system. The heat transfer fluid flows through the secondary heat exchanger 941 and transfers heat to or absorbs heat from the other device or system. The secondary heat exchanger 941 is located in series with the condenser 804. The secondary heat exchanger 941 can be located at any suitable position within the heat transfer loop 920, but in this embodiment, the secondary heat exchanger 941 is located in the supply line 922, downstream of the condenser 804 and upstream of the fuel heat exchanger 910. The secondary heat exchanger 941 is also located upstream of the heat transfer fluid pump 927. The heat transfer fluid can be used to absorb heat from other devices or systems and, therefore, to cool the other devices or systems. The other devices can be, for example, electric generators. Other systems can include, for example, an oil system, where the secondary heat exchanger 941 is an oil cooler for cooling oil (such as lubricating oil), a cooling air system, or a heat exchanger located downstream of the HPC 724 or in the rear stage of the HPC 724 to cool compressed air.

[0211] Fig. 15B is a heat transfer system 904 according to the present disclosure Figure 8 Schematic diagram of turbine engine 710 and steam system 800. For clarity of other heat transfer systems discussed herein, heat transfer system 904 of this embodiment will be referred to as fifth heat transfer system 904. Fifth heat transfer system 904 is similar to the above reference Fig.15A The same reference numerals will be used for components of the fifth heat transport system 904 that are the same or similar to the components of the fourth heat transport system 903 discussed above. The above description of these components also applies to this embodiment, and a detailed description of these components is omitted here. Fig.15A In the fourth heat transfer system 903 of FIG. 8 , the secondary heat exchanger 941 is located in the supply line 922, downstream of the condenser 804 and upstream of the fuel heat exchanger 910. However, as described above, the secondary heat exchanger 941 can be located at other locations within the heat transfer loop 920. The secondary heat exchanger 941 of this embodiment is located in the return line 924, downstream of the fuel heat exchanger 910 and upstream of the condenser 804.

[0212] Fig.16 is a heat transfer system 905 according to the present disclosure Figure 8Schematic diagram of turbine engine 710 and steam system 800. For clarity of other heat transfer systems discussed herein, heat transfer system 905 of this embodiment will be referred to as sixth heat transfer system 905. Sixth heat transfer system 905 is similar to the above reference Fig.15A The same reference numerals will be used for components of the sixth heat transport system 905 that are the same or similar to the components of the fourth heat transport system 903 discussed above. The above description of these components also applies to this embodiment, and a detailed description of these components is omitted here.

[0213] In the fourth heat transfer system 903, the secondary heat exchanger 941 is located in series with the condenser 804, but other arrangements of the secondary heat exchanger 941 may also be used. In the present embodiment, the secondary heat exchanger 941 is located in parallel with the condenser 804. The secondary heat exchanger 941 may be fluidly connected to the return line 924 via a secondary input line 943. The heat transfer fluid flows out of the fuel heat exchanger 910 and flows into the secondary heat exchanger 941 via the secondary input line 943. After absorbing heat in the secondary heat exchanger 941, the heat transfer fluid flowing through the secondary heat exchanger 941 then flows back to the supply line 922 of the heat transfer loop 920 via a secondary output line 945. The secondary output line 945 is fluidly connected to the supply line 922 at a position upstream of the condenser 804 and downstream of the fuel heat exchanger 910, and more specifically, at a position upstream of the heat transfer fluid pump 927.

[0214] The flow of the heat transfer fluid through the secondary heat exchanger 941 and the condenser 804 can be regulated by one or more flow control valves. More specifically, in the present embodiment, the secondary flow control valve 947 is located in the secondary input line 943 to control the flow of the heat transfer fluid flowing through the secondary heat exchanger 941. Similarly, the primary flow control valve 948 is located in the return line 924 to control the flow of the heat transfer fluid flowing through the condenser 804. The primary flow control valve 948 can be located upstream of the condenser 804 and downstream of the position where the secondary input line 943 fluid is connected to the return line 924. Any suitable flow control valve can be used as the secondary flow control valve 947 or the primary flow control valve 948. Such a flow control valve can have a closed position and a plurality of open positions including a fully open position. The flow control valve can be an electrically operable valve, a hydraulically operable valve, or a pneumatically operable valve. When the flow control valve is hydraulically operable, the hydraulic fluid can be a suitable fluid of the turbine engine 710, including, for example, fuel 767, lubricating oil, etc.

[0215] Fig.17 is a heat transfer system 906 according to the present disclosure Figure 8Schematic diagram of turbine engine 710 and steam system 800. For clarity of other heat transfer systems discussed herein, heat transfer system 906 of this embodiment will be referred to as seventh heat transfer system 906. Seventh heat transfer system 906 is similar to the above reference Fig.15A The same reference numerals will be used for components of the seventh heat transport system 906 that are the same or similar to the components of the fourth heat transport system 903 discussed above. The above description of these components also applies to this embodiment, and a detailed description of these components is omitted here.

[0216] In other arrangements, the secondary heat exchanger 941 may also be fluidly connected to the secondary heat exchanger 941. In the present embodiment, the fuel heat exchanger 910 includes multiple outlets for the heat transfer fluid. The return line 924 may be fluidly connected to one outlet to supply the heat transfer fluid to the condenser 804 as discussed above, and the secondary input line 943 may be connected to the second outlet to supply the heat transfer fluid to the secondary heat exchanger 941 as discussed above. The outlets may be connected to different locations of the flow path of the heat transfer fluid through the fuel heat exchanger 910 to provide the heat transfer fluid to the condenser 804 and the secondary heat exchanger 941. For example, the first outlet may be connected to the return line 924 at a location upstream of the second outlet connected to the secondary input line 943 to provide the heat transfer fluid to the condenser 804 at a lower temperature than the secondary heat exchanger 941. Although Figure 7 Not shown, but in this embodiment, a secondary flow control valve 947 and a primary flow control valve 948 may be used.

[0217] Fig.18 is a heat transfer system 907 according to the present disclosure Figure 8 Schematic diagram of turbine engine 710 and steam system 800. For clarity of other heat transfer systems discussed herein, heat transfer system 907 of this embodiment will be referred to as eighth heat transfer system 907. Eighth heat transfer system 907 is similar to the above reference Fig.12 The same reference numerals will be used for components of the eighth heat transport system 907 that are the same or similar to the components of the first heat transport system 900 discussed above. The above description of these components also applies to this embodiment, and a detailed description of these components is omitted here.

[0218] The eighth heat transfer system 907 of the present embodiment includes a heat transfer loop 951, which is similar to the heat transfer loop 920 and has a supply line 922 and a return line 924 that fluidly connect the fuel heat exchanger 910 and the condenser 804. The description of the heat transfer loop 920 above is also applicable to the heat transfer loop 951 of the present embodiment.

[0219] The heat transfer fluid can be a single-phase fluid, but a two-phase fluid can also be used. The eighth heat transfer system 907 of the present embodiment uses a two-phase fluid. Suitable two-phase fluids include, for example, refrigerants, such as chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs) or hydrofluorocarbons (HFCs). When the heat transfer fluid flows through the condenser 804, the fluid is heated and the phase is changed (i.e., vaporized) into a gas phase. Then, the heat transfer fluid flows into the fuel heat exchanger 910 in the gas phase through the supply line 922. In the fuel heat exchanger 910, the heat transfer fluid is cooled and condensed, and the phase is changed back to the liquid phase.

[0220] The heat transfer loop 920 of this embodiment includes a heat transfer fluid pump 952 to direct the heat transfer fluid flow between the fuel heat exchanger 910 and the condenser 804 through the heat transfer loop 951. The heat transfer fluid pump 952 of this embodiment can be similar to the heat transfer fluid pump 927 discussed above and is located at any suitable position within the heat transfer loop 951.

[0221] In some embodiments, a heat transfer fluid pump 952 may be located in the return line 924 to pump the heat transfer fluid in the liquid phase, but in the Fig.18 In the illustrated embodiment, the heat transfer fluid pump 952 is located in the supply line 922 and operates as a compressor. Therefore, the heat transfer fluid pump 952 is referred to herein as a compressor 954. With the compressor 954 located in the supply line 922, the compressor 954 also increases the pressure of the heat transfer fluid in the gas phase, superheating the heat transfer fluid. When the compressor 954 is used, the heat transfer loop 951 can also include an expansion valve 956, which is located in the return line 924 to maintain the high pressure on the inlet side (i.e., the fuel heat exchanger 910 side) while also expanding the liquid refrigerant and reducing the pressure on the outlet side (i.e., the condenser 804 side).

[0222] Fig.19 A heat transfer system 908 according to the present disclosure that can be used in the turbine engine 710 and steam system 800 discussed above is shown. For clarity with respect to other heat transfer systems discussed herein, the heat transfer system 908 of this embodiment will be referred to as the ninth heat transfer system 908. The ninth heat transfer system 908 is similar to the above-mentioned reference Fig.12 The same reference numerals will be used for components of the ninth heat transport system 908 that are the same or similar to the components of the first heat transport system 900 discussed above. The above description of these components also applies to this embodiment, and a detailed description of these components is omitted here.

[0223] The combustion gas 766 ( Fig.12 ) and the fuel 767 ( Figure 8 ) may have a relatively large temperature difference, particularly when the fuel is a cryogenic fuel such as hydrogen fuel. For example, hydrogen fuel may have the cryogenic temperature discussed above, and the combustion gases 766 entering the condenser 804 during operation may have a temperature from five hundred degrees Fahrenheit (500°F) (two hundred sixty degrees Celsius (260°C)) to one thousand six hundred degrees Fahrenheit (1600°F) (eight hundred seventy-one degrees Celsius (871°C)). It may be difficult to accommodate these extreme cold and hot conditions with a single working fluid (i.e., heat transfer fluid), and therefore, in the present embodiment, two working fluids (e.g., a first heat transfer fluid and a second heat transfer fluid) may be used.

[0224] The ninth heat transfer system 908 of the present embodiment includes an intermediate heat exchanger 1010. The intermediate heat exchanger 1010 is fluidly connected to each of the condenser 804 and the fuel heat exchanger 910. The intermediate heat exchanger 1010 can be any suitable heat exchanger, such as, for example, a tubular heat exchanger or a plate heat exchanger having flow paths for a first heat transfer fluid and a second heat transfer fluid. As each fluid flows through the intermediate heat exchanger 1010, the intermediate heat exchanger 1010 transfers heat from the first heat transfer fluid to the second heat transfer fluid. As discussed further below, when the first heat transfer fluid flows through the condenser 804, the first heat transfer fluid receives heat from the combustion gases 766, and the second heat transfer fluid receives heat from the combustion gases 766 as described above with reference to FIG. Fig.12 The heat is transferred to the fuel 767 in the manner described. The first heat transfer fluid is a working fluid selected for use in high temperature environments such as those experienced in the turbine engine 710 and may include, for example, a silicon-based heat transfer fluid (e.g., Syltherm TM 800 or Syltherm TM XLT, each produced by Dow of Midland, Michigan, USA) or supercritical carbon dioxide. The second heat transfer fluid is in thermal contact with the cryogenic fuel and can be selected for these extremely low temperatures. Non-limiting examples include helium, nitrogen or sulfur hexafluoride.

[0225] The intermediate heat exchanger 1010 is fluidly connected to the condenser 804 through a first heat transfer loop 1020. The first heat transfer loop 1020 is similar to the heat transfer loop 920 discussed above, and the discussion of the heat transfer loop 920 also applies to the first heat transfer loop 1020. The first heat transfer loop 1020 includes a supply line 1022 similar to the supply line 922 discussed above. The supply line 1022 is fluidly connected to each of the condenser 804 and the intermediate heat exchanger 1010. The first heat transfer fluid flows through the fluid passage of the condenser 804 and, after being heated by the combustion gas 766, flows from the condenser 804 to the intermediate heat exchanger 1010 through the supply line 1022, wherein, as discussed above, heat is transferred from the first heat transfer fluid to the second heat transfer fluid. The first heat transfer loop 1020 also includes a return line 1024, which is fluidly connected to each of the intermediate heat exchanger 1010 and the condenser 804. The first heat transfer fluid flows from the intermediate heat exchanger 1010 to the condenser 804 through the return line 1024 after transferring heat to the second heat transfer fluid, where the heat was transferred from the combustion gases 766 as discussed above.

[0226] The first heat transfer loop 1020 also includes a first heat transfer fluid pump 1026. The first heat transfer fluid pump 1026 can be similar to the heat transfer fluid pump 927 discussed above, and the discussion of the heat transfer fluid pump 927 is applicable to this embodiment. The first heat transfer fluid pump 1026 directs the first heat transfer fluid flow between the condenser 804 and the intermediate heat exchanger 1010 through the first heat transfer loop 1020. The first heat transfer fluid pump 1026 can be located at any suitable location within the first heat transfer loop 1020, but in this embodiment, the first heat transfer fluid pump 1026 is located in the supply line 1022.

[0227] The intermediate heat exchanger 1010 is fluidly connected to the fuel heat exchanger 910 through a second heat transfer loop 1030. The second heat transfer loop 1030 is similar to the heat transfer loop 920 discussed above, and the discussion of the heat transfer loop 920 also applies to the second heat transfer loop 1030. The second heat transfer loop 1030 includes a supply line 1032 similar to the supply line 922 discussed above. The supply line 1032 is fluidly connected to each of the intermediate heat exchanger 1010 and the fuel heat exchanger 910. The second heat transfer fluid flows through the fluid channel of the intermediate heat exchanger 1010 and, after being heated by the first heat transfer fluid, flows from the intermediate heat exchanger 1010 to the fuel heat exchanger 910 through the supply line 1032, wherein, as discussed above, heat is transferred from the second heat transfer fluid to the fuel 767. The second heat transfer loop 1030 also includes a return line 1034 that is fluidly connected to each of the fuel heat exchanger 910 and the intermediate heat exchanger 1010. The second heat transfer fluid flows from the fuel heat exchanger 910 to the intermediate heat exchanger 1010 through the return line 1034 after transferring heat to the fuel 767, wherein heat is transferred from the first heat transfer fluid to the second heat transfer fluid as discussed above.

[0228] The second heat transfer loop 1030 also includes a second heat transfer fluid pump 1036. The second heat transfer fluid pump 1036 can be similar to the heat transfer fluid pump 927 discussed above, and the discussion of the heat transfer fluid pump 927 is applicable to this embodiment. The second heat transfer fluid pump 1036 directs the second heat transfer fluid flow through the second heat transfer loop 1030 between the intermediate heat exchanger 1010 and the second heat transfer loop 1030. The second heat transfer fluid pump 1036 can be located at any suitable location within the second heat transfer loop 1030, but in this embodiment, the second heat transfer fluid pump 1036 is located in the supply line 1032.

[0229] The foregoing discussion includes various components in different embodiments of heat transport systems. However, the components and features of each of these heat transport systems are not mutually exclusive, and one or more components shown and described in one heat transport system may be applied to another heat transport system.

[0230] The turbine engine 710 of the embodiment discussed herein includes a steam system 800. The turbine engine 710 also includes a heat transfer system that can be used to transfer heat from the steam system 800, more specifically, from the combustion gases 766 to the fuel 767 and heat (i.e., or vaporize) the fuel 767. If the cryogenic fuel is heated by being directed through the condenser 804, the condenser 804 is at risk of freezing due to the extreme coldness of the cryogenic fuel. The use of the water 874 and heat transfer system discussed herein can mitigate the risk of ice formation in the condenser 804, where ice may block the bypass air 762 from the fan 738, thereby reducing thrust.

[0231] Generally speaking Figures 8 to 19 It will be appreciated that the depicted exemplary turbine engines 710 each also include a pericritical fluid sensor assembly operable with a fluid system of the turbine engine 710. In one or more of these embodiments, the fluid system may be a fuel delivery assembly, a heat transfer assembly, or both.

[0232] Further, the pericritical fluid sensor assembly includes one or more pericritical fluid sensors 1100, wherein each pericritical fluid sensor 1100 is similar to the above reference Figures 1 to 7 One or more of the exemplary pericritical fluid sensors discussed above are constructed in a similar manner. Figures 8 to 19 Not depicted in the embodiments of the present invention, the one or more pericritical fluid sensors 1100 of the pericritical fluid sensor assembly may generally include one or more sensors configured to generate sensor outputs corresponding to one or more phase properties of the pericritical fluid flowing through the fluid system; and a controller communicatively coupled to the one or more sensors. The controller may be configured to generate control commands based at least in part on the sensor outputs, the control commands being configured to control one or more controllable components of the fluid system. The one or more sensors may include one or more phase detection sensors, and the one or more phase detection sensors may include acoustic sensors.

[0233] exist Figures 8 to 19 In an exemplary embodiment of the present invention, a pericritical fluid sensor assembly including one or more pericritical fluid sensors 1100 may allow for more precise control of a fluid system, more efficient operation, and / or other desired operational results.

[0234] Further aspects of the disclosure are provided by the subject matter of the following clauses:

[0235] A pericritical fluid system of a thermal management system associated with a turbine engine, the pericritical fluid system comprising: one or more sensors, the one or more sensors being configured to generate sensor outputs corresponding to one or more phase properties of a pericritical fluid flowing through a cooling circuit of the thermal management system; and a controller, the controller being communicatively coupled to the one or more sensors, the controller being configured to generate control commands based at least in part on the sensor outputs, the control commands being configured to control one or more controllable components of the thermal management system; wherein the one or more sensors include one or more phase detection sensors, the one or more phase detection sensors including acoustic sensors.

[0236] A pericritical fluid system according to any of the preceding clauses, comprising: the one or more controllable components, wherein the one or more controllable components are respectively configured to change one or more of the following: the temperature of the pericritical fluid, the pressure of the pericritical fluid and / or the flow rate of the pericritical fluid.

[0237] A pericritical fluid system according to any preceding clause, wherein the acoustic sensor comprises a sonic velocity sensor, the sonic velocity sensor comprising an ultrasonic transducer and a receiver, the ultrasonic transducer being configured to emit sonic waves, the receiver being configured to receive the sonic waves and convert the sonic waves into electrical signals.

[0238] A pericritical fluid system according to any preceding clause, wherein the acoustic sensor comprises an acoustic wave sensor configured to apply an oscillating electric field to generate acoustic waves that propagate through a piezoelectric substrate.

[0239] A pericritical fluid system according to any preceding clause, wherein the acoustic wave sensor comprises a bulk acoustic wave sensor.

[0240] A pericritical fluid system according to any preceding clause, wherein the acoustic wave sensor comprises a surface acoustic wave sensor.

[0241] A pericritical fluid system according to any preceding clause, wherein the controller is configured to determine one or more phase properties of the pericritical fluid based at least in part on the sensor output.

[0242] A pericritical fluid system according to any preceding clause, wherein the controller is configured to determine one or more phase properties of the pericritical fluid based at least in part on a correlation between the sensor output and the one or more phase properties of the pericritical fluid.

[0243] A pericritical fluid system according to any preceding clause, wherein the controller is configured to determine one or more phase properties of the pericritical fluid based at least in part on a noise or bias level of a sensor output.

[0244] A pericritical fluid system according to any preceding clause, wherein the one or more sensors comprise one or more temperature sensors and / or one or more pressure sensors.

[0245] A pericritical fluid system according to any preceding clause, wherein the sensor output includes a phase detection sensor output generated by the one or more phase detection sensors, and at least one of: a temperature sensor output generated by the one or more temperature sensors, and a pressure sensor output generated by the one or more pressure sensors; and wherein the controller is configured to determine one or more phase properties of the pericritical fluid based at least in part on the phase detection sensor output in combination with at least one of: the temperature sensor output and the pressure sensor output.

[0246] A pericritical fluid system according to any preceding clause, wherein the one or more phase properties of the pericritical fluid include a phase change and a phase state corresponding to the phase change, and wherein the controller is configured to determine the occurrence of the phase change based at least in part on the phase detection sensor output, and wherein the controller is configured to determine the phase state corresponding to the phase change based at least in part on at least one of: the temperature sensor output and the pressure sensor output.

[0247] A pericritical fluid system according to any preceding clause, wherein the pericritical fluid comprises at least one of: carbon monoxide, carbon dioxide, ammonia, methane, methanol, ethanol, ethylene, propane, propylene, heptane, 1-octanol, 2-octanol, 2-propanol, difluoromethane, ethane, difluoroethane, tetrafluoroethylene, acetone, nitrous oxide, argon, bromine, neon, hydrogen, oxygen and water.

[0248] A pericritical fluid system according to any preceding clause, wherein the pericritical fluid comprises a multimodal fluid comprising a first fluid component and a second fluid component, and wherein the sensor output corresponds to one or more phase properties relative to the second fluid component, and wherein the controller is configured to determine one or more phase properties relative to the first fluid component based at least in part on the sensor output corresponding to the one or more phase properties relative to the second fluid component.

[0249] A pericritical fluid system according to any preceding clause, wherein the one or more phase properties relative to the second fluid component include a phase state or phase change with respect to a liquid saturation curve, the liquid saturation curve representing a transition of the second fluid component from a liquid phase to a gas phase.

[0250] A pericritical fluid system according to any preceding clause, wherein the multimodal fluid comprises a third fluid component, and wherein the sensor output comprises an additional sensor output corresponding to one or more phase properties relative to the third fluid component, and wherein the controller is configured to determine one or more phase properties relative to the first fluid component based at least in part on the additional sensor output corresponding to the one or more phase properties relative to the third fluid component; wherein the one or more phase properties relative to the third fluid component comprise a phase state or phase change with respect to a vapor saturation curve, the vapor saturation curve representing a transition of the third fluid component from a gas phase to a liquid phase; and wherein the vaporization curve of the first fluid component is at least partially enclosed by the liquid saturation curve and the vapor saturation curve.

[0251] A pericritical fluid system according to any preceding clause, wherein the second fluid component and / or the third fluid component has a concentration corresponding to a trace amount sufficient for determining the one or more phase properties.

[0252] A pericritical fluid system according to any preceding clause, wherein the first fluid component comprises carbon dioxide, and the second fluid component and / or the third fluid component comprises at least one of the following: carbon monoxide, ammonia, methane, methanol, ethanol, ethylene, propane, propylene, heptane, 1-octanol, 2-octanol, 2-propanol, difluoromethane, ethane, difluoroethane, tetrafluoroethylene, acetone, nitrous oxide, argon, bromine, neon, hydrogen, oxygen, water.

[0253] A liquid fuel system for a turbine engine, the liquid fuel system comprising: one or more sensors, the one or more sensors being configured to generate sensor outputs corresponding to one or more phase properties of a fuel supplied to the turbine engine through a fuel path; and a controller, the controller being communicatively coupled to the one or more sensors, the controller being configured to generate control commands based at least in part on the sensor outputs, the control commands being configured to control one or more controllable components of the liquid fuel system, wherein the one or more sensors include one or more phase detection sensors; and wherein the fuel includes hydrogen, and wherein the fuel has a liquid phase.

[0254] A liquid fuel system according to any preceding clause, wherein the one or more phase detection sensors comprise: an acoustic sensor, an optical sensor or a pressure drop sensor.

[0255] A liquid fuel system according to any preceding clause, wherein the one or more phase detection sensors include the acoustic sensor, wherein the acoustic sensor includes a sound velocity sensor, the sound velocity sensor includes an ultrasonic transducer and a receiver, the ultrasonic transducer is configured to emit sound waves, the receiver is configured to receive the sound waves and convert the sound waves into electrical signals.

[0256] A liquid fuel system according to any preceding clause, wherein the one or more phase detection sensors include the acoustic sensor, wherein the acoustic sensor includes an acoustic wave sensor configured to apply an oscillating electric field to generate acoustic waves that propagate through a piezoelectric substrate.

[0257] A liquid fuel system according to any preceding clause, wherein the acoustic wave sensor comprises a bulk acoustic wave sensor.

[0258] A liquid fuel system according to any preceding clause, wherein the acoustic wave sensor comprises a surface acoustic wave sensor.

[0259] A liquid fuel system according to any preceding clause, wherein the one or more phase detection sensors include the optical sensor, wherein the optical sensor includes a fiber optic reflectometer, the fiber optic reflectometer including a light source, an optical fiber and a photodiode, the light source being configured to generate a detection beam, the optical fiber being configured to introduce the detection beam into a measurement chamber, and the photodiode being configured to measure the intensity of the detection beam.

[0260] A liquid fuel system according to any preceding clause, wherein the fiber optic reflectometer comprises one or more microstructured optical fibers, each of which comprises a core material and a plurality of channels defined within the core material, wherein the fiber optic reflectometer is configured to guide light through the plurality of channels by total internal reflection and / or constructive interference of scattered light.

[0261] A liquid fuel system according to any preceding clause, wherein the one or more phase detection sensors include the optical sensor, wherein the optical sensor includes an infrared spectrometer, the infrared spectrometer includes an infrared light source, a measuring window and an infrared detector, the measuring window is configured to contact the fuel, and the infrared detector is configured to detect infrared light transmitted through the measuring window.

[0262] A liquid fuel system according to any preceding clause, wherein the infrared spectrometer comprises an attenuated total reflection infrared spectrometer configured to detect total internal reflection.

[0263] A liquid fuel system according to any preceding clause, wherein the one or more phase detection sensors include the pressure drop sensor, wherein the pressure drop sensor includes a microchannel pressure drop sensor or a packed bed pressure drop sensor.

[0264] A liquid fuel system according to any preceding clause, comprising: one or more controllable components, wherein the one or more controllable components are respectively configured to change one or more of the following: the temperature of the fuel, the pressure of the fuel and / or the flow rate of the fuel.

[0265] A liquid fuel system according to any preceding clause, wherein the controller is configured to determine one or more phase properties of the fuel based at least in part on the sensor output.

[0266] A liquid fuel system according to any preceding clause, wherein the controller is configured to determine one or more phase properties of the fuel based at least in part on a correlation between the sensor output and the one or more phase properties of the fuel.

[0267] A liquid fuel system according to any preceding clause, wherein the controller is configured to determine one or more phase properties of the fuel based at least in part on a noise or bias level of a sensor output.

[0268] A liquid fuel system according to any preceding clause, wherein the one or more sensors comprise one or more temperature sensors and / or one or more pressure sensors.

[0269] A liquid fuel system according to any preceding clause, wherein the sensor output includes a phase detection sensor output generated by the one or more phase detection sensors, and at least one of: a temperature sensor output generated by the one or more temperature sensors, and a pressure sensor output generated by the one or more pressure sensors; and wherein the controller is configured to determine one or more phase properties of the fuel based at least in part on the phase detection sensor output in combination with at least one of: the temperature sensor output and the pressure sensor output.

[0270] A liquid fuel system according to any preceding clause, wherein the one or more phase properties of the fuel include a phase change and a phase state corresponding to the phase change, and wherein the controller is configured to determine the occurrence of the phase change based at least in part on the phase detection sensor output, and wherein the controller is configured to determine the phase state corresponding to the phase change based at least in part on at least one of: the temperature sensor output and the pressure sensor output.

[0271] A liquid fuel system according to any preceding clause, comprising: a pericritical fluid system according to any preceding clause.

[0272] A turbine engine comprises: a thermal management system configured to circulate a pericritical fluid through a cooling circuit, the thermal management system comprising one or more controllable components; one or more sensors configured to generate sensor outputs corresponding to one or more phase properties of the pericritical fluid; and a controller communicatively coupled to the one or more sensors, the controller configured to generate control commands based at least in part on the sensor outputs, the control commands configured to control the one or more controllable components; wherein the one or more sensors include one or more phase detection sensors, the one or more phase detection sensors including acoustic sensors.

[0273] A turbine engine, comprising: a liquid fuel system, the liquid fuel system being configured to supply fuel to the turbine engine through a fuel path, the liquid fuel system comprising one or more controllable components; one or more sensors, the one or more sensors being configured to generate sensor outputs, the sensor outputs corresponding to one or more phase properties of the fuel; and a controller, the controller being communicatively coupled to the one or more sensors, the controller being configured to generate control commands based at least in part on the sensor outputs, the control commands being configured to control the one or more controllable components, wherein the one or more sensors include one or more phase detection sensors; wherein the fuel includes hydrogen.

[0274] A turbine engine according to any preceding clause, wherein the turbine engine comprises a pericritical fluid system according to any preceding clause.

[0275] A turbine engine according to any preceding clause, wherein the turbine engine comprises a liquid fuel system according to any preceding clause.

[0276] A non-transitory computer-readable medium comprising computer-executable instructions, which, when executed by a processor, cause the processor to perform a method of controlling one or more phase properties of a pericritical fluid associated with a thermal management system of a turbine engine, the method comprising: determining sensor outputs generated by one or more sensors, the sensor outputs corresponding to one or more phase properties of the pericritical fluid flowing through a cooling circuit of the thermal management system; and generating control commands based at least in part on the sensor outputs, the control commands being configured to control one or more controllable components of the thermal management system; wherein the one or more sensors include one or more phase detection sensors, the one or more phase detection sensors including acoustic sensors.

[0277] A non-transitory computer-readable medium comprising computer-executable instructions which, when executed by a processor, cause the processor to perform a method of controlling one or more phase properties of a fuel associated with a liquid fuel system of a turbine engine, the method comprising: determining sensor outputs generated by one or more sensors, the sensor outputs corresponding to one or more phase properties of a fuel supplied to the turbine engine through a fuel path; and generating control commands based at least in part on the sensor outputs, the control commands being configured to control one or more controllable components of the liquid fuel system, wherein the one or more sensors include one or more phase detection sensors; wherein the fuel includes hydrogen, and wherein the fuel has a liquid phase.

[0278] A method for controlling one or more phase properties of a pericritical fluid associated with a thermal management system of a turbine engine, the method comprising: determining sensor outputs generated by one or more sensors, the sensor outputs corresponding to one or more phase properties of the pericritical fluid flowing through a cooling circuit of the thermal management system; and generating control commands based at least in part on the sensor outputs, the control commands being configured to control one or more controllable components of the thermal management system; wherein the one or more sensors include one or more phase detection sensors, the one or more phase detection sensors including acoustic sensors.

[0279] A method for controlling one or more phase properties of a fuel associated with a liquid fuel system of a turbine engine, the method comprising: determining sensor outputs generated by one or more sensors, the sensor outputs corresponding to one or more phase properties of the fuel supplied to the turbine engine through a fuel path; and generating control commands based at least in part on the sensor outputs, the control commands being configured to control one or more controllable components of the liquid fuel system, wherein the one or more sensors include one or more phase detection sensors; and wherein the fuel includes hydrogen, and wherein the fuel has a liquid phase.

[0280] A method according to any preceding clause, wherein the method is performed using a pericritical fluid system according to any preceding clause.

[0281] A method according to any preceding clause, wherein the method is performed using a liquid fuel system according to any preceding clause.

[0282] A method as described in any preceding clause, wherein the method is performed using a non-transitory computer-readable medium as described in any preceding clause.

[0283] This written description uses exemplary embodiments to describe the subject matter of the present disclosure, including the best mode, and also to enable any person skilled in the art to practice the subject matter, including making and using any device or system, and performing any combined methods. The patentable scope of the presently disclosed subject matter is defined by the claims, and may include other examples that occur to one skilled in the art. Such other examples are intended to fall within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that do not differ substantially from the literal language of the claims.

[0284] A turbine engine for an aircraft. The turbine engine includes a fuel delivery assembly for flowing fuel therethrough. The turbine engine also includes a turbine and a fan, the fan having a fan shaft, the fan shaft being coupled to the turbine so that the fan shaft rotates. The turbine engine includes a core air flow path for flowing core air therethrough, a burner, a core shaft, and a turbine. The burner is located in the core air flow path to receive compressed air and is fluidly coupled to the fuel delivery assembly to receive fuel from the fuel delivery assembly. The fuel is injected into the burner to mix with the compressed air to generate a fuel and air mixture. The fuel and air mixture is burned in the burner to generate combustion gases. The turbine is located downstream of the burner to receive the combustion gases and to rotate the turbine. The turbine is coupled to the core shaft so that when the turbine rotates, the core shaft rotates. The turbine engine further includes a condenser, a fuel heat exchanger, a boiler, and a steam turbine. The condenser is located downstream of the turbine to receive the combustion gases and condense water from the combustion gases. The fuel heat exchanger is thermally coupled to the condenser to receive heat from the water. The fuel heat exchanger is located in the fuel delivery assembly to receive the fuel and transfer the heat received from the water to the fuel. A boiler is located downstream of the fuel heat exchanger. The boiler receives the water and is fluidly connected to the burner to receive the combustion gases and boil the water to generate steam. The steam turbine is fluidly coupled to the boiler to receive the steam from the boiler and rotate the steam turbine. The steam turbine is coupled to the core shaft so that the core shaft rotates when the steam turbine rotates.

[0285] The turbine engine according to the preceding clause, further comprising a fuel tank in which fuel is retained, the fuel delivery assembly being fluidly connected to the fuel tank to receive fuel therefrom.

[0286] A turbine engine according to any preceding clause, wherein the combustor is fluidly coupled to the boiler to receive the steam from the boiler and to inject the steam into the combustor.

[0287] A turbine engine according to any preceding clause, wherein the combustor is fluidly coupled to the steam turbine to receive the steam from the steam turbine and to inject the steam into the combustor.

[0288] A turbine engine according to any preceding clause, wherein the fuel is a cryogenic fuel and the fuel tank is a cryogenic fuel tank for storing the fuel in the liquid phase.

[0289] A turbine engine according to any preceding clause, wherein the fuel is hydrogen fuel.

[0290] A turbine engine according to any preceding clause, further comprising a fuel bypass flow path selectively operable to redirect the fuel and bypass the fuel heat exchanger.

[0291] A turbine engine according to any preceding clause, further comprising a fuel bypass valve positioned in the fuel delivery assembly upstream of the fuel heat exchanger and selectively operable to redirect at least a portion of the fuel through the fuel bypass flow path.

[0292] A turbine engine according to any preceding clause, wherein the fuel heat exchanger comprises a heater.

[0293] A turbine engine according to the preceding clause, wherein the heater is an electric heater.

[0294] A turbine engine according to any preceding clause, wherein the condenser comprises a heater.

[0295] A turbine engine according to the preceding clause, wherein the heater is an electric heater.

[0296] A turbine engine according to any preceding clause, wherein the fuel heat exchanger is fluidly coupled to the condenser to receive the water condensed by the condenser.

[0297] A turbine engine according to any preceding clause, further comprising a heat transfer loop comprising a supply line to supply the fuel heat exchanger with water condensed by the condenser.

[0298] A turbine engine according to any preceding clause, further comprising a water pump in fluid communication with the boiler to direct a flow of water into the boiler, the supply line being fluidly connected to the water pump at a location downstream of the water pump.

[0299] A turbine engine according to any preceding clause, further comprising a valve in fluid communication with the supply line and a water line fluidly connecting the water pump to the boiler, the valve being operable to direct at least a portion of the water through the supply line and to the fuel heat exchanger.

[0300] A turbine engine according to any of the preceding clauses, wherein the condenser generates an exhaust-water mixture when condensing the water from the combustion gases, the turbine engine further comprising a water separator located downstream of the condenser, the water separator separating the water from the exhaust-water mixture, the supply line being fluidly connected to the water separator at a position downstream of the water separator.

[0301] A turbine engine according to any preceding clause, further comprising a water pump, said water pump being fluidly connected to said water separator to receive said water from said water separator and being fluidly connected to said boiler to direct the water flow into said boiler, said supply line being fluidly connected to said water separator at a position downstream of said water pump.

[0302] A turbine engine according to any preceding clause, wherein the water separator comprises a heater.

[0303] Turbine engine according to any preceding clause, wherein the heat transfer loop comprises a return line fluidly connecting the fuel heat exchanger with the boiler for flowing the water from the fuel heat exchanger to the boiler.

[0304] A turbine engine according to any preceding clause, further comprising a preheating heat exchanger located in the return line and fluidly coupled to the return line upstream of the boiler to heat the water flowing through the preheating heat exchanger.

[0305] A turbine engine according to any preceding clause, wherein the preheat heat exchanger is a condenser, the condenser comprising flow passages for the water to flow therethrough and be preheated by the combustion gases flowing through the condenser.

[0306] A turbine engine according to any preceding clause, wherein the heat transfer loop further comprises an additional heat exchanger to heat or cool the water flowing through the heat transfer loop.

[0307] Turbine engine according to any preceding clause, wherein the additional heat exchanger is located in the return line downstream of the condenser and upstream of the boiler and heats the water flowing therethrough.

[0308] A turbine engine according to any preceding clause, wherein the additional heat exchanger is a water / oil heat exchanger.

[0309] The turbine engine according to any of the preceding clauses further comprises an intermediate heat exchanger, the intermediate heat exchanger being fluidly connected to the condenser to receive the water condensed by the condenser, heat being transferred from the water to an intermediate heat transfer medium in the intermediate heat exchanger, and the fuel heat exchanger being fluidly connected to the intermediate heat exchanger to receive the intermediate heat transfer medium.

[0310] A turbine engine according to any preceding clause, wherein the intermediate heat transfer medium is a fluid other than water.

[0311] A turbine engine according to any preceding clause, wherein the intermediate heat transfer medium is one of helium, nitrogen or carbon dioxide.

[0312] A turbine engine according to any preceding clause, wherein the intermediate heat transfer medium is one of gaseous carbon dioxide or supercritical carbon dioxide.

[0313] A turbine engine according to any preceding clause, further comprising an intermediate heat transfer loop fluidly connecting the intermediate heat exchanger with the fuel heat exchanger to circulate the intermediate heat transfer medium.

[0314] A turbine engine according to any preceding clause, wherein the intermediate heat transfer loop comprises an intermediate fluid pump to direct a flow of an intermediate heat transfer medium through the intermediate heat transfer loop.

[0315] A turbine engine according to any preceding clause, wherein the intermediate heat transfer loop comprises a supply line to supply the intermediate heat transfer medium from the intermediate heat exchanger to the fuel heat exchanger, and a return line to supply the intermediate heat transfer medium from the fuel heat exchanger to the intermediate heat exchanger.

[0316] A turbine engine according to any preceding clause, wherein the intermediate fluid pump is located in the return line.

[0317] Turbine engine according to any preceding clause, further comprising a first heat transfer loop comprising a supply line to supply the intermediate heat exchanger with the water condensed by the condenser.

[0318] A turbine engine according to any preceding clause, further comprising a water pump in fluid communication with the boiler to direct a flow of water into the boiler, the supply line being fluidly connected to the water pump at a location downstream of the water pump.

[0319] A turbine engine according to any preceding clause, further comprising a valve located in the supply line and in a water line connecting the water pump to the boiler fluid, the valve being operable to direct at least a portion of the water through the supply line and to the intermediate heat exchanger.

[0320] A turbine engine according to any of the preceding clauses, wherein the condenser generates an exhaust-water mixture when condensing the water from the combustion gases, the turbine engine further comprising a water separator located downstream of the condenser, the water separator separating the water from the exhaust-water mixture, the supply line being fluidly connected to the water separator at a position downstream of the water separator.

[0321] A turbine engine according to any preceding clause, further comprising a water pump, said water pump being fluidly connected to said water separator to receive said water from said water separator and being fluidly connected to said boiler to direct the water flow into said boiler, said supply line being fluidly connected to said water separator at a position downstream of said water pump.

[0322] Turbine engine according to any preceding clause, wherein the first heat transfer loop comprises a return line fluidly connecting the intermediate heat exchanger with the boiler for flowing the water from the fuel heat exchanger to the boiler.

[0323] A turbine engine according to any preceding clause, further comprising a preheating heat exchanger located in the return line and fluidly coupled to the return line upstream of the boiler to heat the water flowing through the preheating heat exchanger.

[0324] A turbine engine according to any preceding clause, wherein the preheat heat exchanger is a condenser, the condenser comprising flow passages for the water to flow therethrough and be preheated by the combustion gases flowing through the condenser.

[0325] A turbine engine according to any preceding clause, wherein the first heat transfer loop further comprises an additional heat exchanger to heat or cool the water flowing through the heat transfer loop.

[0326] Turbine engine according to any preceding clause, wherein the additional heat exchanger is located in the return line downstream of the condenser and upstream of the boiler to heat the water flowing therethrough.

[0327] A turbine engine according to any preceding clause, wherein the additional heat exchanger is a water / oil heat exchanger.

[0328] A turbine engine according to any preceding clause, wherein the core shaft is a low pressure shaft and the turbine is a low pressure turbine.

[0329] A turbine engine according to any preceding clause, further comprising a low-pressure compressor connected to the low-pressure shaft to be driven by the low-pressure turbine and the steam turbine.

[0330] A turbine engine according to any preceding clause, wherein the fan comprises a plurality of blades.

[0331] A turbine engine according to any preceding clause, wherein the fan shaft is coupled to the low pressure shaft so as to be driven by the low pressure shaft.

[0332] A turbine engine according to any preceding clause, further comprising a bypass airflow passage. A first portion of the air flowing into the fan flows through the bypass airflow passage as bypass air, and a second portion of the air flowing into the fan flows through the core air flow path as core air. The condenser is positioned downstream of the boiler and in the bypass airflow passage for bypass air to cool the combustion gases and condense water from the combustion gases.

[0333] A turbine engine according to any preceding clause, further comprising a low-pressure compressor positioned in the core air flow path upstream of the combustor, the low-pressure compressor being driven by the low-pressure shaft to compress the core air flowing through the core air flow path and generate the compressed air.

[0334] The turbine engine according to any preceding clause, further comprising a high-pressure shaft, a high-pressure turbine and a high-pressure compressor. The high-pressure turbine is positioned downstream of the combustor to receive the combustion gases and rotate the high-pressure turbine. The high-pressure turbine is coupled to the high-pressure shaft to rotate the high-pressure shaft when the high-pressure turbine rotates. The high-pressure compressor is positioned in the core air flow path upstream of the combustor and downstream of the low-pressure compressor. The high-pressure compressor is driven by the high-pressure shaft to compress the core air flowing through the core air flow path and generate the compressed air.

[0335] A turbine engine according to any preceding clause, further comprising a bypass airflow passage for bypass air, said condenser being positioned in said bypass airflow passage for bypass air to cool said combustion gases and condense water therefrom to generate cooled exhaust gas.

[0336] A turbine engine according to any preceding clause, wherein the water separator is a cyclone separator.

[0337] A turbine engine according to any preceding clause, further comprising a turbine and a steam system. The turbine includes the burner and the turbine. The burner and the turbine define a core air flow path. The steam system extracts water from the combustion gas using the condenser, vaporizes the water using the boiler to generate steam, and injects the steam into the core air flow path to add mass flow to the core air.

[0338] The turbine engine according to the preceding clause, further comprising a nacelle and a steam system. The fan comprises a plurality of fan blades that rotate to generate a volume of air. The nacelle circumferentially surrounds the fan. The nacelle defines a bypass airflow channel between the nacelle and the turbine. The volume of air from the fan is separated and flows into the bypass airflow channel as bypass air and into the core air flow path as the core air.

[0339] A turbine engine according to the preceding clause, wherein the bypass ratio of the bypass air to the core air is greater than 18:1.

[0340] A turbine engine according to any preceding clause, wherein the bypass ratio is in the range of 18:1 to 100:1.

[0341] A turbine engine according to any preceding clause, wherein the bypass ratio is in the range of 25:1 to 85:1.

[0342] A turbine engine according to any preceding clause, wherein the bypass ratio is in the range of 28:1 to 70:1.

[0343] A turbine engine according to any preceding clause, wherein the turbine further comprises a compressor, the compressor compressing the core air to generate the compressed air.The compressor is coupled to the core shaft and defines a portion of the core air flow path.

[0344] A turbine engine according to the preceding clause, wherein the compressor comprises a high pressure compressor and comprises a compression ratio greater than 20:1.

[0345] A turbine engine according to the preceding clause, wherein said plurality of stages of said compressor comprises ten to twelve stages.

[0346] A turbine engine according to any preceding clause, wherein the turbine comprises a high pressure turbine (HPT) and comprises only one stage of HPT rotor blades and HPT stator vanes.

[0347] A turbine engine according to any preceding clause, further comprising a low pressure turbine.

[0348] Turbine engine according to the preceding clause, wherein the low-pressure turbine has a low-pressure shaft coupled to the fan.

[0349] A turbine engine according to any preceding clause, further comprising a low-pressure compressor coupled to the low-pressure shaft to be driven by the low-pressure turbine and the steam turbine.

[0350] A turbine engine as claimed in any preceding clause, wherein the low pressure turbine has a pressure expansion ratio in the range of 4.5:1 to 28:1.

[0351] A turbine engine as claimed in any preceding clause, wherein the high pressure turbine has a pressure expansion ratio in the range 1.5:1 to 4:1.

[0352] A method of starting a turbine engine, the turbine engine comprising a turbine engine as described in any of the preceding clauses. The method comprises flowing fuel from a fuel storage tank to a combustor, directing the fuel to bypass a fuel heat exchanger, measuring a temperature of the fuel heat exchanger, when the measured temperature of the fuel heat exchanger is less than a first threshold temperature, operating a first heater located within the fuel heat exchanger to heat the fuel heat exchanger to the first threshold temperature, and when the measured temperature of the fuel heat exchanger is greater than the first threshold temperature, flowing water through the fuel heat exchanger.

[0353] Method for starting a turbine engine according to the preceding clause, wherein said fuel is a cryogenic fuel and said fuel tank is a cryogenic fuel tank for storing said fuel in a liquid phase.

[0354] A method of starting a turbine engine according to any preceding clause, wherein the fuel is hydrogen fuel.

[0355] A method of starting a turbine engine according to any preceding clause, further comprising flowing the fuel through the fuel heat exchanger after flowing the water through the fuel heat exchanger.

[0356] A method of starting a turbine engine according to any preceding clause, wherein directing the fuel to bypass the fuel heat exchanger comprises positioning a fuel bypass valve to direct the fuel through a bypass flow path to bypass the fuel heat exchanger.

[0357] A method of starting a turbine engine according to any preceding clause, wherein flowing the water through a fuel heat exchanger comprises positioning a water bypass valve to direct water into the fuel heat exchanger.

[0358] A method of starting a turbine engine according to any preceding clause, wherein flowing the water through the fuel heat exchanger comprises operating a water pump to direct water into the fuel heat exchanger.

[0359] A method of starting a turbine engine according to any preceding clause, further comprising regulating water flow to increase the amount of water flowing through the fuel heat exchanger.

[0360] A method of starting a turbine engine according to any preceding clause, further comprising regulating fuel flow to increase the amount of fuel flowing through the fuel heat exchanger.

[0361] A method of starting a turbine engine according to any preceding clause, further comprising bringing the turbine engine to idle speed.

[0362] A turbine engine according to any preceding clause, further comprising a controller configured to operate the turbine engine according to the method of starting a turbine engine according to any preceding clause.

[0363] A method of shutting down a turbine engine comprising a turbine engine as described in any preceding clause, the method comprising flowing fuel from a fuel storage tank to a combustor, directing all of the fuel to bypass a fuel heat exchanger, and directing a flow of water to a boiler to bypass the fuel heat exchanger.

[0364] A turbine engine according to any preceding clause, further comprising a controller configured to operate the turbine engine according to the method of shutting down a turbine engine according to the preceding clause.

[0365] A turbine engine for an aircraft. The turbine engine includes a fuel delivery assembly for flowing fuel therethrough. The turbine engine also includes a turbine and a fan, the fan having a fan shaft, the fan shaft being coupled to the turbine to rotate the fan shaft. The turbine engine includes a core air flow path for flowing core air therethrough, a burner, a core shaft, and a turbine. The burner is located in the core air flow path to receive compressed air and is fluidly coupled to the fuel delivery assembly to receive fuel from the fuel delivery assembly. The fuel is injected into the burner to mix with the compressed air to generate a fuel and air mixture. The fuel and air mixture is burned in the burner to generate combustion gases. The turbine engine further includes a condenser, a fuel heat exchanger, and at least one heat transfer loop. The condenser is located downstream of the burner to receive the combustion gases and condense water from the combustion gases. The fuel heat exchanger is thermally coupled to the condenser to receive heat from the condenser. The fuel heat exchanger is located in the fuel delivery assembly to receive the fuel and transfer heat received from the condenser. The at least one heat transfer loop thermally couples the condenser to the fuel heat exchanger to transfer heat from the condenser to the fuel heat exchanger. The at least one heat transfer loop includes a heat transfer fluid flowing therethrough. The at least one heat transfer loop is fluidly connected to a passage of the condenser for the heat transfer fluid to receive heat from the combustion gases and is thermally connected to the fuel heat exchanger for the heat transfer fluid to transfer heat from the heat transfer fluid to the fuel and cool the heat transfer fluid.

[0366] The turbine engine according to the preceding clause, further comprising a fuel tank in which fuel is retained, the fuel delivery assembly being fluidly connected to the fuel tank to receive fuel therefrom.

[0367] A turbine engine according to any preceding clause, wherein the at least one heat transfer loop is fluidly coupled to the fuel heat exchanger to transfer heat from the heat transfer fluid to the fuel and to cool the heat transfer fluid.

[0368] A turbine engine according to any preceding clause, wherein the heat transfer fluid is one of helium, nitrogen, supercritical carbon dioxide, a silicon-based heat transfer fluid or sulfur hexafluoride.

[0369] A turbine engine according to any preceding clause, wherein the heat transfer fluid is a fluid other than water.

[0370] A turbine engine according to any preceding clause, wherein the at least one heat transfer loop comprises a supply line fluidly connected to each of the condenser and the fuel heat exchanger to supply the heat transfer fluid heated by the condenser to the fuel heat exchanger; and a return line fluidly connected to each of the fuel heat exchanger and the condenser to return cooled heat transfer fluid from the fuel heat exchanger to the condenser.

[0371] A turbine engine according to any preceding clause, further comprising a secondary heat exchanger, which is fluidly connected to the fuel heat exchanger via a secondary input pipeline to receive the cooled heat transfer fluid from the fuel heat exchanger, wherein the fuel heat exchanger includes a plurality of outlets, the return pipeline is fluidly connected to one of the plurality of outlets, and the secondary input pipeline is fluidly connected to another of the plurality of outlets.

[0372] A turbine engine according to the preceding clause, wherein the secondary input line is connected to the fuel heat exchanger at a position upstream or downstream of the return line relative to the flow of the heat transfer fluid to provide the secondary heat exchanger with the heat transfer fluid at a temperature different from the temperature of the heat transfer fluid provided to the condenser.

[0373] A turbine engine according to any preceding clause, wherein the at least one heat transfer loop comprises a heat transfer fluid pump in fluid communication with the at least one heat transfer loop to direct the flow of heat transfer fluid into the at least one heat transfer loop.

[0374] A turbine engine according to any preceding clause, wherein the heat transfer fluid pump is located in the supply line.

[0375] A turbine engine according to any preceding clause, wherein the heat transfer fluid is a two-phase heat transfer fluid and the heat transfer fluid pump is a compressor.

[0376] Turbine engine according to any preceding clause, wherein the at least one heat transfer loop comprises an expansion valve, the expansion valve being located in the return line.

[0377] A turbine engine according to any preceding clause, wherein the at least one heat transfer loop comprises an accumulator having a fluid reservoir to store the heat transfer fluid therein.

[0378] A turbine engine according to any preceding clause, wherein the fluid reservoir has an adjustable volume for storing the heat transfer fluid.

[0379] Turbine engine according to the preceding clause, wherein the volume of the fluid reservoir is actively adjustable by an actuator, the actuator being operable to adjust the volume of the fluid reservoir.

[0380] A turbine engine according to any preceding clause, further comprising a controller operably coupled to the actuator to move the actuator and adjust the volume of the fluid reservoir.

[0381] A turbine engine according to any preceding clause, wherein the controller is configured to receive an input and to adjust the volume of the fluid reservoir based on the input received.

[0382] A turbine engine according to any preceding clause, further comprising a sensor communicatively coupled to provide input to the controller.

[0383] Turbine engine according to the preceding clause, wherein the sensor is a pressure sensor positioned to provide an input indicative of the pressure of the heat transfer fluid in the at least one heat transfer loop.

[0384] A turbine engine according to any preceding clause, wherein the volume of the fluid reservoir is passively adjustable by a biasing member which applies a biasing force to adjust the volume of the fluid reservoir in response to pressure changes within the fluid reservoir.

[0385] A turbine engine according to any preceding clause, wherein the accumulator comprises a movable diaphragm to adjust the volume of the fluid reservoir.

[0386] A turbine engine according to any preceding clause, further comprising a secondary heat exchanger fluidly connected to the at least one heat transfer loop to exchange heat with the heat transfer fluid flowing through the at least one heat transfer loop.

[0387] A turbine engine as claimed in any preceding clause, wherein the secondary heat exchanger is fluidly connected in series with the condenser with respect to the flow of heat transfer fluid.

[0388] A turbine engine according to any preceding clause, wherein the secondary heat exchanger is fluidly connected in parallel with the condenser with respect to the flow of heat transfer fluid.

[0389] A turbine engine according to any preceding clause, wherein the at least one heat transfer loop comprises a supply line and a return line. The supply line is fluidly connected to each of the condenser and the fuel heat exchanger to supply the heat transfer fluid heated by the condenser to the fuel heat exchanger. The return line is fluidly connected to each of the fuel heat exchanger and the condenser to return cooled heat transfer fluid from the fuel heat exchanger to the condenser. The secondary heat exchanger is fluidly connected to one of the supply line or the return line via a secondary input line to receive the heat transfer fluid from one of the supply line or the return line.

[0390] A turbine engine according to any preceding clause, wherein the secondary input line is fluidly connected to the return line.

[0391] A turbine engine according to any preceding clause, wherein the secondary heat exchanger is fluidly connected to the supply line by a secondary output line for flowing the heat transfer fluid from the secondary heat exchanger to the supply line.

[0392] A turbine engine according to any preceding clause, further comprising at least one flow control valve, the at least one flow control valve controlling the flow of the heat transfer fluid.

[0393] Turbine engine according to the preceding clause, wherein said at least one flow control valve is located in said heat transfer loop to control the flow of said heat transfer fluid in said heat transfer loop.

[0394] A turbine engine according to any preceding clause, further comprising a secondary flow control valve positioned to control the flow of the heat transfer fluid into the secondary heat exchanger.

[0395] A turbine engine according to any preceding clause, wherein the secondary flow control valve is located in the secondary input line.

[0396] A turbine engine according to any preceding clause, further comprising a primary flow control valve located in the heat transfer loop downstream of the secondary input line to control the flow of the heat transfer fluid into the condenser.

[0397] The turbine engine of any preceding clause, further comprising a plurality of heat transfer loops thermally coupling the condenser to the fuel heat exchanger to transfer heat from the condenser to the fuel heat exchanger. The at least one heat exchanger is a first heat transfer loop of the plurality of heat transfer loops, and the heat transfer fluid flowing through the first heat transfer loop is a first heat transfer fluid.

[0398] A turbine engine according to any preceding clause, further comprising an intermediate heat exchanger fluidly connected to the first heat transfer loop to receive the first heat transfer fluid heated by the condenser, heat being transferred from the first heat transfer fluid to a second heat transfer fluid in the intermediate heat exchanger.

[0399] A turbine engine according to the preceding clause, wherein the first heat transfer fluid and the second heat transfer fluid are different.

[0400] A turbine engine according to any preceding clause, wherein the first heat transfer fluid is one of a silicon-based heat transfer fluid or supercritical carbon dioxide.

[0401] A turbine engine according to any preceding clause, wherein the second heat transfer fluid is one of helium, nitrogen or sulfur hexafluoride.

[0402] A turbine engine according to any preceding clause, wherein the plurality of heat transfer loops includes a second heat transfer loop coupling the intermediate heat exchanger to the fuel heat exchanger fluid, the second heat transfer fluid flowing through the second heat transfer loop to transfer heat from the second heat transfer fluid to the fuel and cool the heat transfer fluid.

[0403] A turbine engine according to any preceding clause, wherein the first heat transfer loop comprises a first fluid pump to direct a first heat transfer fluid flow through the first heat transfer loop.

[0404] A turbine engine according to any preceding clause, wherein the first heat transfer loop comprises a supply line to supply the first heat transfer medium from the condenser heat exchanger to the intermediate heat exchanger, and a return line to supply the first heat transfer medium from the intermediate heat exchanger to the condenser.

[0405] A turbine engine according to any preceding clause, wherein the first fluid pump is located in the supply line.

[0406] A turbine engine according to any preceding clause, wherein the second heat transfer loop comprises a second fluid pump to direct a flow of a first heat transfer fluid through the first heat transfer loop.

[0407] A turbine engine according to any preceding clause, wherein the second heat transfer loop comprises a supply line to supply the second heat transfer medium from the intermediate heat exchanger to the fuel heat exchanger, and a return line to supply the second heat transfer medium from the fuel heat exchanger to the intermediate heat exchanger.

[0408] A turbine engine according to any preceding clause, wherein the second fluid pump is located in the supply line.

[0409] A turbine engine according to any preceding clause, wherein the fuel is a cryogenic fuel and the fuel tank is a cryogenic fuel tank for storing the fuel in a liquid phase.

[0410] A turbine engine according to any preceding clause, wherein the fuel is hydrogen fuel.

[0411] A turbine engine according to any preceding clause, further comprising a fuel bypass flow path selectively operable to redirect the fuel and bypass the fuel heat exchanger.

[0412] The turbine engine according to the preceding clause, further comprising a fuel bypass valve positioned in the fuel delivery assembly upstream of the fuel heat exchanger and selectively operable to redirect at least a portion of the fuel through the fuel bypass flow path.

[0413] The turbine engine according to any preceding clause, further comprising a boiler and a steam turbine. The turbine is located downstream of the burner to receive the combustion gases and rotate the turbine. The turbine is coupled to the core shaft to rotate the core shaft when the turbine rotates. The condenser is located downstream of the turbine to receive the combustion gases from the turbine. The boiler is fluidly connected to the condenser to receive the water and is fluidly connected to the burner to receive the combustion gases and boil the water to generate steam. The steam turbine is fluidly coupled to the boiler to receive the steam from the boiler and rotate the steam turbine. The steam turbine is coupled to the core shaft to rotate the core shaft when the steam turbine rotates.

[0414] A turbine engine according to any preceding clause, wherein the combustor is fluidly coupled to the steam turbine to receive the steam from the steam turbine and to inject the steam into the combustor.

[0415] A turbine engine according to any preceding clause, wherein the core shaft is a low pressure shaft and the turbine is a low pressure turbine.

[0416] A turbine engine according to any preceding clause, further comprising a low-pressure compressor connected to the low-pressure shaft to be driven by the low-pressure turbine and the steam turbine.

[0417] A turbine engine according to any preceding clause, wherein the fan shaft is coupled to the low pressure shaft so as to be driven by the low pressure shaft.

[0418] A turbine engine according to any preceding clause, further comprising a bypass airflow passage, a first portion of the air flowing into the fan and flowing through the bypass airflow passage as bypass air, and a second portion of the air flowing into the fan and flowing through the core air flow path as core air, the condenser being located in the bypass airflow passage for bypass air to cool the combustion gases and condense water from the combustion gases.

[0419] Turbine engine according to the preceding clause, wherein the combustor is fluidly coupled to the boiler to receive the steam from the boiler and to inject the steam into the combustor.

[0420] A turbine engine according to any preceding clause, further comprising a water pump in fluid communication with the boiler to direct a flow of water into the boiler.

[0421] A turbine engine according to any preceding clause, wherein the condenser generates an exhaust-water mixture when condensing the water from the combustion gases, the turbine engine further comprising a water separator located downstream of the condenser, the water separator separating the water from the exhaust-water mixture.

[0422] The turbine engine according to the preceding clause, further comprising a water pump in fluid communication with the water separator to receive the water therefrom and in fluid communication with the boiler to direct a flow of water into the boiler.

[0423] A turbine engine according to any preceding clause, further comprising a water pump in fluid communication with the boiler to direct a flow of water into the boiler.

[0424] The turbine engine according to any preceding clause, further comprising a high-pressure shaft, a high-pressure turbine and a high-pressure compressor. The high-pressure turbine is positioned downstream of the combustor to receive the combustion gases and rotate the high-pressure turbine. The high-pressure turbine is coupled to the high-pressure shaft to rotate the high-pressure shaft when the high-pressure turbine rotates. The high-pressure compressor is positioned in the core air flow path upstream of the combustor and downstream of the low-pressure compressor. The high-pressure compressor is driven by the high-pressure shaft to compress the core air flowing through the core air flow path and generate the compressed air.

[0425] A turbine engine according to any preceding clause, further comprising a bypass airflow passage for bypass air, said condenser being positioned in said bypass airflow passage for bypass air to cool said combustion gases and condense water therefrom to generate cooled exhaust gas.

[0426] A turbine engine according to any preceding clause, wherein the water separator is a cyclone separator.

[0427] A turbine engine, comprising: a fuel delivery assembly configured to provide a fuel flow therethrough; a turbine, the turbine comprising a compressor, a combustor, and a turbine in a series flow sequence and defining a core air flow path extending through the compressor, the combustor, and the turbine; a steam system operable with the turbine; a heat transfer assembly configured to transfer heat from the steam system to the fuel flow; and a pericritical fluid sensor assembly operable with a fluid system, the fluid system being the fuel delivery assembly, the heat transfer assembly, or both, the pericritical fluid sensor assembly comprising: one or more sensors configured to generate sensor outputs corresponding to one or more phase properties of a pericritical fluid flowing through the fluid system; and a controller communicatively coupled to the one or more sensors, the controller configured to generate control commands based at least in part on the sensor outputs, the control commands configured to control one or more controllable components of the fluid system; wherein the one or more sensors include one or more phase detection sensors, the one or more phase detection sensors including acoustic sensors.

[0428] A turbine engine according to any preceding clause, wherein the steam system comprises a water source and a boiler, the boiler being fluidly connected to the water source to receive water, the boiler being further fluidly connected to the core air flow path to receive combustion gases to boil the water and generate steam.

[0429] The turbine engine of any preceding clause, wherein the steam system further comprises a condenser in fluid communication with the boiler and in thermal communication with the heat transfer assembly, the condenser being configured to condense the steam.

[0430] A turbine engine according to any preceding clause, wherein the steam system further comprises a steam turbine in fluid communication with the boiler to receive the steam from the boiler and to rotate the steam turbine.

[0431] A turbine engine according to any preceding clause, wherein the turbine comprises a shaft rotatable together with the turbine, and wherein the steam turbine is rotatable together with the shaft.

[0432] A turbine engine according to any preceding clause, wherein the combustor is fluidly coupled to the steam turbine to receive the steam from the steam turbine and to inject the steam into the combustor.

[0433] A turbine engine according to any preceding clause, wherein the fluid system is the heat transfer assembly, wherein the heat transfer assembly comprises a working fluid, and wherein the working fluid is in a pericritical state or a supercritical state during operation of the turbine engine.

[0434] A turbine engine according to any preceding clause, wherein the working fluid is supercritical carbon dioxide.

[0435] A turbine engine as described in any preceding clause, wherein the fluid system is the fuel delivery assembly, and wherein the fuel delivery assembly includes a cryogenic fuel.

[0436] A turbine engine according to any preceding clause, wherein the cryogenic fuel is hydrogen fuel.

[0437] A turbine engine according to any preceding clause, wherein the heat transfer assembly is a heat transfer loop, wherein the steam system further includes a condenser, and wherein the turbine engine further includes: a fuel heat exchanger, wherein the fuel heat exchanger is thermally coupled to the fuel flow through the fuel delivery assembly and is thermally coupled to the condenser through the heat transfer loop.

[0438] A turbine engine according to any preceding clause, wherein the heat transfer loop fluid is connected to a passage of the condenser for the heat transfer fluid to receive heat from the combustion gases and is thermally connected to the fuel heat exchanger for the heat transfer fluid to transfer heat from the heat transfer fluid to the fuel and cool the heat transfer fluid.

[0439] A turbine engine according to any of the preceding clauses, wherein the steam system further includes a condenser, and wherein the turbine engine further includes: a fuel heat exchanger, which is thermally coupled to the fuel flow through the fuel delivery assembly and is thermally coupled to the condenser through the heat transfer assembly, and wherein the heat transfer assembly includes: a plurality of heat transfer loops, which thermally couple the condenser to the fuel heat exchanger to transfer heat from the condenser to the fuel heat exchanger, wherein at least one of the heat transfer loops is a first heat transfer loop among the plurality of heat transfer loops, and the heat transfer fluid flowing through the first heat transfer loop is a first heat transfer fluid; and an intermediate heat exchanger, which is fluidly coupled to the first heat transfer loop to receive the first heat transfer fluid heated by the condenser, wherein heat is transferred from the first heat transfer fluid to a second heat transfer fluid in the intermediate heat exchanger.

[0440] A turbine engine according to any preceding clause, wherein the plurality of heat transfer loops includes a second heat transfer loop coupling the intermediate heat exchanger to the fuel heat exchanger fluid, the second heat transfer fluid flowing through the second heat transfer loop to transfer heat from the second heat transfer fluid to the fuel and cool the heat transfer fluid.

[0441] A turbine engine according to any preceding clause, wherein the acoustic sensor comprises a sonic velocity sensor comprising an ultrasonic transducer configured to transmit sonic waves and a receiver configured to receive the sonic waves and convert them into electrical signals.

[0442] A turbine engine according to any preceding clause, wherein the controller is configured to determine one or more phase properties of the pericritical fluid based at least in part on the sensor output.

[0443] A turbine engine according to any preceding clause, wherein the one or more sensors comprise one or more temperature sensors and / or one or more pressure sensors.

[0444] A turbine engine according to any preceding clause, wherein the sensor output comprises a phase detection sensor output generated by the one or more phase detection sensors, and at least one of: a temperature sensor output generated by the one or more temperature sensors, and a pressure sensor output generated by the one or more pressure sensors; and wherein the controller described herein is configured to determine one or more phase properties of the pericritical fluid based at least in part on a combination of the phase detection sensor output and at least one of: the temperature sensor output and the pressure sensor output.

[0445] A turbine engine according to any preceding clause, wherein the one or more phase properties of the pericritical fluid include a phase change and a phase state corresponding to the phase change, and wherein the controller is configured to determine the occurrence of the phase change based at least in part on the phase detection sensor output, and wherein the controller is configured to determine the phase state corresponding to the phase change based at least in part on at least one of: the temperature sensor output and the pressure sensor output.

[0446] A turbine engine according to any preceding clause, wherein the acoustic sensor comprises a sonic velocity sensor comprising an ultrasonic transducer configured to transmit sonic waves and a receiver configured to receive the sonic waves and convert them into electrical signals.

Claims

1. A turbine engine, characterized in that: include: a fuel delivery assembly configured to provide a flow of fuel therethrough; a turbomachine including, in series flow order, a compressor, a combustor, and a turbine and defining a core air flow path extending through the compressor, the combustor, and the turbine; a steam system operable with the turbine; a heat transfer assembly configured to transfer heat from the steam system to the fuel flow; and A pericritical fluid sensor assembly, the pericritical fluid sensor assembly being operable with a fluid system, the fluid system being the fuel delivery assembly, the heat transfer assembly, or both, the pericritical fluid sensor assembly comprising: one or more sensors configured to generate a sensor output corresponding to one or more phase properties of a pericritical fluid flowing through the fluid system; and a controller communicatively coupled to the one or more sensors, the controller configured to generate control commands based at least in part on the sensor outputs, the control commands configured to control one or more controllable components of the fluid system; Wherein the one or more sensors include one or more phase detection sensors, and the one or more phase detection sensors include acoustic sensors.

2. The turbine engine according to claim 1, characterized in that The steam system includes a water source and a boiler in fluid communication with the water source to receive water, the boiler further in fluid communication with the core air flow path to receive combustion gas to boil the water and generate steam.

3. The turbine engine according to claim 2, characterized in that: The steam system further includes a condenser in fluid communication with the boiler and in thermal communication with the heat transfer assembly, the condenser being configured to condense the steam.

4. The turbine engine according to claim 2, characterized in that: The steam system further includes a steam turbine in fluid communication with the boiler to receive the steam from the boiler and rotate the steam turbine.

5. The turbine engine according to claim 4, characterized in that Wherein the turbine comprises a shaft rotatable together with the turbine, and wherein the steam turbine is rotatable together with the shaft.

6. The turbine engine according to claim 4, characterized in that Wherein the combustor is fluidly coupled to the steam turbine to receive the steam from the steam turbine and inject the steam into the combustor.

7. The turbine engine according to claim 1, characterized in that The fluid system is the heat transfer assembly, wherein the heat transfer assembly includes a working fluid, and wherein the working fluid is in a pericritical state or a supercritical state during operation of the turbine engine.

8. The turbine engine according to claim 7, characterized in that The working fluid is supercritical carbon dioxide.

9. The turbine engine according to claim 1, characterized in that Wherein the fluid system is the fuel delivery assembly, and wherein the fuel delivery assembly includes a cryogenic fuel.

10. The turbine engine according to claim 9, characterized in that The cryogenic fuel is hydrogen fuel.

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