Patent ID: 12209533

The figures are not to scale. In general, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts.

DETAILED DESCRIPTION

“Including” and “comprising” (and all forms and tenses thereof) are used herein to be open ended terms. Thus, whenever a claim employs any form of “include” or “comprise” (e.g., comprises, includes, comprising, including, having, etc.) as a preamble or within a claim recitation of any kind, it is to be understood that additional elements, terms, etc., may be present without falling outside the scope of the corresponding claim or recitation. As used herein, when the phrase “at least” is used as the transition term in, for example, a preamble of a claim, it is open-ended in the same manner as the term “comprising” and “including” are open ended. The term “and/or” when used, for example, in a form such as A, B, and/or C refers to any combination or subset of A, B, C such as (1) A alone, (2) B alone, (3) C alone, (4) A with B, (5) A with C, (6) B with C, or (7) A with B and with C. As used herein in the context of describing structures, components, items, objects and/or things, the phrase “at least one of A and B” is intended to refer to implementations including any of (1) at least one A, (2) at least one B, or (3) at least one A and at least one B. Similarly, as used herein in the context of describing structures, components, items, objects and/or things, the phrase “at least one of A or B” is intended to refer to implementations including any of (1) at least one A, (2) at least one B, or (3) at least one A and at least one B. As used herein in the context of describing the performance or execution of processes, instructions, actions, activities and/or steps, the phrase “at least one of A and B” is intended to refer to implementations including any of (1) at least one A, (2) at least one B, or (3) at least one A and at least one B. Similarly, as used herein in the context of describing the performance or execution of processes, instructions, actions, activities and/or steps, the phrase “at least one of A or B” is intended to refer to implementations including any of (1) at least one A, (2) at least one B, or (3) at least one A and at least one B.

As used herein, singular references (e.g., “a”, “an”, “first”, “second”, etc.) do not exclude a plurality. The term “a” or “an” object, as used herein, refers to one or more of that object. The terms “a” (or “an”), “one or more”, and “at least one” are used interchangeably herein. Furthermore, although individually listed, a plurality of means, elements or method actions may be implemented by, e.g., the same entity or object. Additionally, although individual features may be included in different examples or claims, these may possibly be combined, and the inclusion in different examples or claims does not imply that a combination of features is not feasible and/or advantageous.

As used herein, connection references (e.g., attached, coupled, connected, and joined) may include intermediate members between the elements referenced by the connection reference and/or relative movement between those elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and/or in fixed relation to each other. As used herein, stating that any part is in “contact” with another part is defined to mean that there is no intermediate part between the two parts.

Unless specifically stated otherwise, descriptors such as “first,” “second,” “third,” etc., are used herein without imputing or otherwise indicating any meaning of priority, physical order, arrangement in a list, and/or ordering in any way, but are merely used as labels and/or arbitrary names to distinguish elements for ease of understanding the disclosed examples. In some examples, the descriptor “first” may be used to refer to an element in the detailed description, while the same element may be referred to in a claim with a different descriptor such as “second” or “third.” In such instances, it should be understood that such descriptors are used merely for identifying those elements distinctly that might, for example, otherwise share a same name.

Approximating language, as used herein throughout the specification and claims, is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about”, “approximately”, “substantially”, and “just” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, the precision of a first position relative to a second position, or the precision of the methods or machines for constructing or manufacturing the components and/or systems. For example, the approximating language may refer to being within a ten percent margin.

The terms “upstream” and “downstream” refer to the relative direction with respect to a flow in a pathway. For example, with respect to a fluid flow, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows.

As used herein, in the context of describing the position and/or orientation of a first object relative to a second object, the term “substantially orthogonal” encompasses the term orthogonal and more broadly encompasses a meaning whereby the first object is positioned and/or oriented relative to the second object at an absolute angle of no more than five degrees (5°) from orthogonal. For example, a first axis that is substantially orthogonal to a second axis is positioned and/or oriented relative to the second axis at an absolute angle of no more than five degrees (5°) from orthogonal.

As used herein, “radially” is used to express a point or points along a radial vector originating at a central axis of a rotating body and pointing perpendicularly outward from the central axis. For example, fluid is said to accelerate radially outward from an impeller, meaning that the fluid flows outward from a central axis (axis of rotation) of the impeller at a direction that is substantially orthogonal to the central axis.

Some aircraft generate thrust using gas turbine engines and include thermal management system(s) (TMS(s)) to transfer heat to/from accessory systems in the engine(s). Such a TMS includes a thermal transport bus (TTB) to transmit a heat exchange fluid and/or a working fluid (e.g., fuel, oil, air, supercritical carbon dioxide (sCO2), etc.) between the accessory systems and/or engine components. The working fluid absorbs heat from and/or transfers heat to the systems and/or components. Such gas turbine engines can be described as operating according to a Brayton cycle, which consists of adiabatic compression (in a compression stage), isobaric heat addition (in a combustion stage), adiabatic expansion (in a turbine stage), and isobaric heat rejection (in an exhaust stage). As such, thermal management systems described herein and included in aircraft with gas turbine engines can be referred to as advanced Brayton cycle loops, apparatus, or systems.

In some examples, a TMS uses sCO2 as the working fluid due to its low viscosity and high specific heat, which makes sCO2 more thermally conductive than other heat exchange fluids (e.g., water, air, etc.), and enables heat exchangers to efficiently transfer heat to and/or from the sCO2. In such examples, the TMS includes an sCO2 pump to pressurize the working fluid within the TTB. The pump can be centrifugal pump that uses an electric motor to rotate a shaft coupled to an impeller, which draws the working fluid into an inlet and accelerates the working fluid radially outward into an outlet. In some examples, the turbine stages of the gas turbine engine generate electricity and provide electrical power to the motor. The motor transfers the electrical energy into mechanical work to rotate the shaft and pump the working fluid. However, there can be electrical losses associated with such a configuration. For example, electrical connections within a generator unit of the turbine engines, electrical connections between the generator unit and the pump motor, and electrical connections within the motor can lose electrical energy in the form of waste heat generation due to electrical resistances therein. Therefore, the electrical power of the motor can experience substantial losses before being converted into mechanical work at the pump shaft. Furthermore, since the motor uses a portion of the electrical energy that the engines generate, that portion of energy is unable to be supplied to other systems within the aircraft. For example, other auxiliary power systems, such as, cabin lighting, air conditioning, ventilation, etc., could use electrical power that the pump motor otherwise consumes.

Furthermore, the pump and the motor can be a significant contributor to weight and space consumption within the engines and/or onboard the aircraft. In some examples, the size and weight of the pump can be increase proportionally with a size (e.g., thrust class) of the engine. For example, the TMS can be used to add heat to fuel upstream of a fuel injector of the gas turbine engine to improve the efficiency of combustion. Thus, when the engine is of a relatively large size, the motorized pump of the TMS can also be of a relatively large size (e.g., 40 pounds (lbs.), 50 lbs., 60 lbs., etc.) to provide the working fluid at a flowrate corresponding to a flowrate of the fuel flowing into the injector. As the pump and motor sizes increase, so does the amount of waste heat generation. Since the pump motor generates waste heat, cooling systems are included in and/or around the pump to absorb the heat, increase the efficiency of the motor, and inhibit thermal damage from occurring. Such cooling systems can further increase the real estate consumption of the pump. In some examples, the working fluid itself is used as the coolant to absorb heat from the motor. In such examples, less working fluid is utilized in the TMS since a portion of the working fluid is diverted to the motor.

Example heat driven thermal management systems (e.g., heat driven advanced Brayton cycle loops, heat driven advanced Brayton cycle apparatus, heat driven advanced Brayton cycle systems, etc.) disclosed herein include a turbomachine rather than an electrically powered pump to pressurize and accelerate the working fluid in the TTB. The turbomachine of example systems disclosed herein includes a turbine rotatably interlocked with a compressor via a shaft. Example systems disclosed herein include a first flowline that branches from the TTB at a point where temperature and thermal energy values of the working fluid are substantially high and leads to an inlet of the turbine. In some examples, the point where the flowline diverts from the TTB is just downstream (e.g., within one meter) of a heat source exchanger. In some other examples, a plurality of (e.g., two, three, etc.) heat source exchangers are included in the TMS in serial order, and the point where the flowline diverges from the TTB is just downstream of a last (e.g., furthest downstream) heat source exchanger in the TTB. Examples systems disclosed herein includes the turbine to expand the working fluid, extract thermal energy, and convert the thermal energy into mechanical work. The mechanical work causes the shaft to rotate, which causes the compressor of example systems disclosed herein to rotate, which compresses, pressurizes, and/or accelerates the working fluid in the TTB.

Example heat driven TMSs disclosed herein eliminate the need for a motor driven pump to drive the flow of the working fluid in the TTB. As such, electrical energy that the gas turbine engines generate can be conserved and allocated to other onboard systems. Furthermore, example systems disclosed herein can have substantial weight reductions (e.g., 40 lbs., 50 lbs., 60 lbs., etc.) and space reductions (e.g., 30 cubic inches (in3), 40 in3, 50 in3, etc.) due to the replacement of the pump with the turbomachine. For example, overall system volume (or space) is conserved when the turbomachine replaces the housing that structures the pump and motor, the cooling system that cools the motor, the control system of the motor, etc. Example systems disclosed herein can be assembled and/or packaged into smaller spaces due to the fewer components and/or systems associated with electric sCO2 pumps. Example heat driven TMSs disclosed herein can also operate more efficiently by eliminating electrical losses associated with motor driven pumps. In other words, example systems disclosed herein operate are more efficiently because the mechanical energy losses (e.g., vibrations, friction, etc.) of the turbomachine are substantially less than the electrical energy losses described above. Furthermore, example heat driven TMSs disclosed herein reduce the complexity of the TMS since the pump is not utilized. For example, pumps designed to pressurize sCO2 in the TTB can be costly to design, manufacture, and maintain, especially when the pumps include supplementary systems (e.g., self-lubricating systems, dynamic axial loading systems, dynamic radial bearing systems, etc.) to optimize pump performance. Example heat drive TMSs disclosed herein can include a turbomachine with a motor-generator unit (M-G unit) connected to the shaft. In some examples, the motor of the M-G unit can supplement the power transferred to the compressor from the turbine when needed, or the generator of the M-G unit can produce electrical energy based on the rotation of the shaft. The electricity that example systems disclosed herein generate can be stored in batteries already onboard the aircraft. Therefore, not only can example heat driven TMSs disclosed herein operate as a self-powered systems that do not consume aircraft power, but such example systems can also operate as power plants that supply energy to various onboard systems.

It should be appreciated that, although examples disclosed herein refer primarily to sCO2 as the working fluid, other types of working fluids are also applicable, such as liquid helium, helium-xenon mixtures, etc.

For the figures disclosed herein, identical numerals indicate the same elements throughout the figures. Referring now to the drawings,FIG.1is a side view of an example aircraft10. As shown inFIG.1, the aircraft10includes a fuselage12and a pair of wings14(one is shown) extending outward from the fuselage12. In the illustrated example, a gas turbine engine100is supported on each wing14to propel the aircraft through the air during flight. Additionally, the aircraft10includes a vertical stabilizer16and a pair of horizontal stabilizers18(one is shown). However, in some examples, the aircraft10includes engines of different types and/or in different positions than the illustrative example ofFIG.1.

Furthermore, the aircraft10can include an example first thermal management system300(TMS300) for transferring heat between fluids supporting the operation of the aircraft10. More specifically, the aircraft10can include one or more accessory systems configured to support the operation of the aircraft10. For example, such accessory systems include a lubrication system that lubricates components of the engines100, a cooling system that provides cooling air to components of the engines100, an environmental control system that provides cooled air to the cabin of the aircraft10, and/or the like. In such examples, the TMS300is configured to transfer heat from one or more fluids supporting the operation of the aircraft10(e.g., the oil of the lubrication system, the air of the cooling system and/or the environmental control system, and/or the like) to one or more other fluids supporting the operation of the aircraft10(e.g., the fuel supplied to the engines100). However, in some other examples, the TMS300is configured to transfer heat between another fluid or component supporting the operation of the aircraft10.

Although examples disclosed herein are described with reference to the aircraft10ofFIG.1, examples disclosed herein can be applicable to another type or configuration of aircraft that uses a thermal management system substantially similar to the TMS300ofFIGS.1-3. Thus, the present subject matter can be readily adaptable to another aircraft and/or another heat transfer application associated with another type of vehicle.

FIG.2is a schematic cross-sectional view of an example gas turbine engine100. In the illustrated example, the engine100is configured as a high-bypass turbofan engine. However, in some examples, the engine100is configured as a propfan engine, a turbojet engine, a turboprop engine, a turboshaft gas turbine engine, etc.

In general, the engine100extends along an axial centerline102and includes a fan104, a low-pressure (LP) spool106, and a high pressure (HP) spool108at least partially encased by an annular nacelle110. More specifically, the fan104can include a fan rotor112and a plurality of fan blades114(one is shown) coupled to the fan rotor112. In this respect, the fan blades114are circumferentially spaced apart and extend radially outward from the fan rotor112. Moreover, the LP and HP spools106,108are positioned downstream from the fan104along the axial centerline102. As shown, the LP spool106is rotatably coupled to the fan rotor112, which permits the LP spool106to rotate the fan blades114. Additionally, a plurality of outlet guide vanes or struts116circumferentially spaced apart from each other and extend radially between an outer casing118surrounding the LP and HP spools106,108and the nacelle110. As such, the struts116support the nacelle110relative to the outer casing118such that the outer casing118and the nacelle110define a bypass airflow passage120positioned therebetween.

The outer casing118generally surrounds or encases, in serial flow order, a compressor section122, a combustion section124, a turbine section126, and an exhaust section128. In some examples, the compressor section122includes a low-pressure (LP) compressor130of the LP spool106and a high-pressure (HP) compressor132of the HP spool108positioned downstream from the LP compressor130along the axial centerline102. Each compressor130,132can, in turn, include one or more rows of compressor stator vanes134interdigitated with one or more rows of compressor rotor blades136. As such, the compressors130,132define a compressed air flow path133extending therethrough. Moreover, in some examples, the turbine section126includes a high-pressure (HP) turbine138of the HP spool108and a low-pressure (LP) turbine140of the LP spool106positioned downstream from the HP turbine138along the axial centerline102. Each turbine138,140can, in turn, include one or more rows of turbine stator vanes142interdigitated with one or more rows of turbine rotor blades144.

Additionally, the LP spool106includes the low-pressure (LP) shaft146and the HP spool108includes a high-pressure (HP) shaft148positioned concentrically around the LP shaft146. In such examples, the HP shaft148rotatably couples the turbine rotor blades144of the HP turbine138and the compressor rotor blades136of the HP compressor132such that rotation of the turbine rotor blades144of the HP turbine138rotatably drives the compressor rotor blades136of the HP compressor132. As shown, the LP shaft146is directly coupled to the turbine rotor blades144of the LP turbine140and the compressor rotor blades136of the LP compressor130. Furthermore, the LP shaft146is coupled to the fan104via a gearbox150. In this respect, the rotation of the turbine rotor blades144of the LP turbine140rotatably drives the compressor rotor blades136of the LP compressor130and the fan blades114.

In some examples, the engine100generates thrust to propel an aircraft. More specifically, during operation, air152enters an inlet portion154of the engine100. The fan104supplies a first portion156of the air152to the bypass airflow passage120and a second portion158of the air152to the compressor section122. The second portion158of the air152first flows through the LP compressor130in which the compressor rotor blades136therein progressively compress the second portion158of the air152. Next, the second portion158of the air152flows through the HP compressor132in which the compressor rotor blades136therein continue to progressively compress the second portion158of the air152. The compressed second portion158of the air152is subsequently delivered to the combustion section124. In the combustion section124, the second portion158of the air152mixes with fuel and burns to generate high-temperature and high-pressure combustion gases160. Thereafter, the combustion gases160flow through the HP turbine138which the turbine rotor blades144of the HP turbine138extract a first portion of kinetic and/or thermal energy therefrom. This energy extraction rotates the HP shaft148, which drives the HP compressor132. The combustion gases160then flow through the LP turbine140in which the turbine rotor blades144of the LP turbine140extract a second portion of kinetic and/or thermal energy therefrom. This energy extraction rotates the LP shaft146, which drives the LP compressor130and the fan104via the gearbox150. The combustion gases160then exit the engine100through the exhaust section128.

As mentioned above, the aircraft10can include the TMS300for transferring heat between fluids supporting the operation of the aircraft10. In this respect, the TMS300can be positioned within the engine100. For example, as shown inFIG.2, the TMS300is positioned within the outer casing118of the engine100. However, in some other examples, the TMS300is positioned at another location within the engine100.

Furthermore, in some examples, the engine100defines a third-stream flow path170. In general, the third-stream flow path170extends from the compressed air flow path133defined by the compressor section122to the bypass airflow passage120. In this respect, the third-stream flow path170allows compressed a portion of the second portion158of the air152from the compressor section122to bypass the combustion section124. More specifically, in some examples, the third-stream flow path170defines a concentric or non-concentric passage relative to the third-stream flow path170downstream of one or more of the compressors130,132or the fan104. The third-stream flow path170can be configured to selectively remove the second portion158of the air152from the third-stream flow path170via one or more variable guide vanes, nozzles, or other actuable flow control structures. In addition, as will be described below, in some examples, the TMS300transfers heat to the air flowing through the third-stream flow path170. However, a pressure and/or a flow rate of a fluid (e.g., a heat exchange fluid such as a supercritical fluid (e.g., supercritical carbon dioxide (sCO2), etc.)) within the TMS300limits a rate at which thermal energy is transferred between the air and the heat exchange fluid. Additionally, it is advantageous for the TMS300to produce the pressure and/or the flow rate with pumps that support axial thrusts of the shaft within the pump to improve the lifespan and/or efficiency of the pump(s) and the TMS300.

Although examples disclosed herein are described with reference to the gas turbine engine100ofFIG.2, examples disclosed herein can be applicable to another type or configuration of engine that uses a thermal management system substantially similar to the TMS300ofFIGS.1-3. Thus, the present subject matter can be readily adaptable to another engine and/or another heat transfer application associated with another type of vehicle.

FIG.3is a schematic diagram of an example implementation of the TMS300for transferring heat between fluids. In general, the TMS300is discussed in the context of the aircraft10and the gas turbine engine100described above and shown inFIGS.1and2. However, the TMS300can be implemented within another type of aircraft and/or another gas turbine engine of another configuration.

As shown, the TMS300includes a thermal transport bus302. Specifically, in some examples, the thermal transport bus302is configured as one or more fluid conduits through which a fluid (e.g., a heat exchange fluid) flows. As described below, the heat exchange fluid flows through various heat exchangers such that heat is added to and/or removed from the heat exchange fluid. In this respect, the heat exchange fluid can be a working fluid, such as supercritical carbon dioxide, oil, liquid helium, etc. Moreover, in such examples, the TMS300includes a pump304configured to pump the heat exchange fluid through the thermal transport bus302.

Additionally, the TMS300includes one or more heat source exchangers306arranged along the thermal transport bus302. More specifically, the heat source exchangers306are fluidly coupled to the thermal transport bus302such that the heat exchange fluid flows through the heat source exchangers306. In this respect, the heat source exchangers306are configured to transfer heat from fluids supporting the operation of the aircraft10to the heat exchange fluid, which cools the fluids supporting the operation of the aircraft10. Thus, the heat source exchangers306add heat to the heat exchange fluid. Although two heat source exchangers306are illustrated inFIG.3, the TMS300can include a single heat source exchanger306or multiple (e.g., two, three, five, etc.) heat source exchangers306.

The heat source exchangers306can correspond to many configurations of heat exchangers that cool a fluid supporting the operation of the aircraft10. In some examples, at least one of the heat source exchangers306is a heat exchanger of the lubrication system of the engine100. In such examples, the heat source exchanger306transfers heat from the oil lubricating the engine100to the heat transfer fluid. In some other examples, at least one of the heat source exchangers306is a heat exchanger of the cooling system of the engine100. In such examples, the heat source exchanger306transfers heat from the cooling air bled from the compressor section122(or a compressor discharge plenum) of the engine100to the heat transfer fluid. However, in some other examples, the heat source exchangers306correspond to other types of heat exchangers that cool a fluid supporting the operation of the aircraft10.

Furthermore, the TMS300includes a plurality of heat sink exchangers308arranged along the thermal transport bus302. More specifically, the heat sink exchangers308are fluidly coupled to the thermal transport bus302such that the heat exchange fluid flows through the heat sink exchangers308. In this respect, the heat sink exchangers308are configured to transfer heat from the heat exchange fluid to other fluids supporting the operation of the aircraft10, which heats the other fluids supporting the operation of the aircraft10. Thus, the heat sink exchangers308remove heat from the heat exchange fluid. Although two heat sink exchangers308are illustrated inFIG.3, the TMS300can include a single heat sink exchanger308or multiple (e.g., two, three, five, etc.) heat sink exchangers308.

The heat sink exchangers308can correspond to many configurations of exchangers that heat a fluid supporting the operation of the aircraft10. For example, at least of one of the heat sink exchangers308is a heat exchanger of the fuel system of the engine100. In such examples, the fuel system heat sink exchanger308transfers heat from the heat transfer fluid to the fuel supplied to the engine100. In some other examples, at least one of the heat sink exchangers308is a heat exchanger in contact with the first portion156of the air152flowing through the bypass airflow passage120of the engine100. In such examples, the heat sink exchanger308transfers heat from the heat exchange fluid to the first portion156of the air152flowing through the bypass airflow passage120.

In some examples, one or more of the heat sink exchangers308are configured to transfer heat to the air flowing through the third-stream flow path170. In such examples, the heat exchanger(s)308is/are in contact with the air flow through the third-stream flow path170. Thus, heat from the heat exchange fluid flowing through the thermal transport bus302can be transferred to the air flow through the third-stream flow path170. The use of the third-stream flow path170as a heat sink for the TMS300provides one or more technical advantages. For example, the third-stream flow path170provides greater cooling than other sources of bleed air because a larger volume of air flows through the third-stream flow path170than other bleed air flow paths. Moreover, the air flowing through third-stream flow path170is cooler than the air flowing through other bleed air flow paths and the compressor bleed air. Additionally, the air in the third-stream flow path170is pressurized, which allows the heat sink exchangers308to be smaller than heat exchangers relying on other heat sinks within the engine. Furthermore, in examples in which the engine100is unducted, using the third-stream flow path170as a heat sink does not increase drag on the engine100, unlike the use of ambient air (e.g., a heat exchanger in contact with air flowing around the engine100). However, in some other examples, the heat sink exchangers308correspond to other types of heat exchangers that heat a fluid supporting the operation of the aircraft10.

Moreover, in some examples, the TMS300includes one or more bypass conduits310. Specifically, as shown, each bypass conduit310is fluidly coupled to the thermal transport bus302such that the bypass conduits310allow at least a portion of the heat exchange fluid to bypass the heat source exchangers306and/or the heat sink exchangers308. In some examples, the heat exchange fluid bypasses one or more of the heat source exchangers306and/or the heat sink exchangers308to adjust the temperature of the heat exchange fluid within the thermal transport bus302. The flow of example heat exchange fluid through the bypass conduits310is controlled to regulate the pressure of the heat exchange fluid within the thermal transport bus302. In the illustrated example ofFIG.3, each heat source exchanger306and/or each heat sink exchanger308has a corresponding bypass conduit310. However, in some other examples, other numbers of heat source exchangers306and/or heat sink exchangers308can have a corresponding bypass conduit310so long as there is at least one bypass conduit310.

Additionally, in some examples, the TMS300includes one or more heat source valves312and one or more heat sink valves314. In general, each heat source valve312is configured to control the flow of the heat exchange fluid through the corresponding bypass conduit310to bypass the corresponding heat source exchanger306. Similarly, each heat sink valve314is configured to control the flow of the heat exchange fluid through the corresponding bypass conduit310to bypass the corresponding heat sink exchanger308. In this respect, the valves312,314are fluidly coupled to the thermal transport bus302and the corresponding bypass conduits310. As such, the valves312,314can be moved between fully and/or partially opened and/or closed positions to selectively occlude the flow of heat exchange through the bypass conduit310.

The valves312,314can be controlled based on the pressure and/or temperature of the heat exchange fluid within the thermal transport bus302. More specifically, as indicated above, in certain instances, the pressure of the heat exchange fluid flowing through the thermal transport bus302can fall outside of a desired pressure range (examples provided below). When the pressure of the heat exchange fluid is too high, the TMS300can incur accelerated wear. In this respect, when the pressure of the heat exchange fluid within the thermal transport bus302exceeds a maximum or otherwise increased pressure value, one or more heat source valves312open. In such examples, at least a portion of the heat exchange fluid flows through the bypass conduits310instead of the heat source exchangers306. Thus, less heat is added to the heat exchange fluid by the heat source exchangers306, which reduces the temperature and, thus, the pressure of the fluid. In some examples, the maximum pressure value is between 3800 and 4000 pounds per square inch or less. In some examples, the maximum pressure value is between 2700 and 2900 pounds per square inch, such as 2800 pounds per square inch. In some other examples, the maximum pressure value is between 1300 and 1500 pounds per square inch, such as 1400 pounds per square inch. Such maximum pressure values generally prevent the TMS300from incurring accelerated wear.

In some examples, the maximum pressure value is set prior to and/or during operation based on parameters (e.g., materials utilized, pump304design, aircraft10design, gas turbine engine100design, heat exchange fluid, etc.) associated with the TMS300. The example maximum pressure value can be adjusted relative to the pressure capacities of the thermal transport bus302, the pump304, the heat source exchangers306, the heat sink exchangers308, the bypass conduits310, and/or the valves312,314.

Conversely, when the pressure of the heat exchange fluid is too low, the pump304can experience operability problems and increased wear. As such, when the pressure of the heat exchange fluid within the thermal transport bus falls below a minimum or otherwise reduced pressure value, one or more heat sink valves314open. In such examples, at least a portion of the heat exchange fluid flows through the bypass conduits310instead of the heat sink exchangers308. Thus, less heat is removed from the heat exchange fluid by the heat sink exchangers308, which increases the temperature and, thus, the pressure of the fluid. In some examples, the minimum pressure value is 1070 pounds per square inch or more. In some examples, the minimum pressure value is between 1150 and 1350 pounds per square inch, such as 1250 pounds per square inch. In some other examples, the minimum pressure value is between 2400 and 2600 pounds per square inch, such as 2500 pounds per square inch. Such minimum pressure values are generally utilized when the heat exchange fluid in a supercritical state (e.g., when the heat exchange fluid is carbon dioxide).

As such, the TMS300can be configured to operate such that the pressure of the heat transport fluid is maintained with a range extending between the minimum and maximum pressure values. In some examples, the range extends from 1070 to 4000 pounds per square inch. Specifically, in one example, the range extends from 1250 to 1400 pounds per square inch. In some other examples, the range extends from 2500 to 2800 pounds per square inch.

Accordingly, the operation of the pump304and the valves312,314allows the TMS300to maintain the pressure of the heat exchange fluid within the thermal transport bus302within a specified range of values as the thermal load placed on the TMS300varies.

Furthermore, the example pump304drives the flow of the heat exchange fluid through the TMS300. In some examples, the TMS300includes one pump304or multiple pumps304depending on the desired flow rate, delta pressure across the pump304, and/or the kinetic energy loss of the heat exchange fluid in the thermal transport bus302. For example, the pump304can increase the output pressure head to accelerate the flow of the heat exchange fluid to a first flowrate. As the heat exchange fluid passes through the thermal transport bus302, the example kinetic energy of the heat exchange fluid dissipates due to friction, temperature variations, etc. Due to the kinetic energy losses, the heat exchange fluid decelerates to a second flow rate at some point upstream of the pump304. When the example second flow rate is below a desired operating flow rate of the heat exchange fluid, the pump304can either be of a different architecture that outputs a higher first flow rate, or one or more additional pumps304can be included in the TMS300.

FIG.4is a schematic diagram of an example implementation of a second thermal management system400(TMS400) for transferring heat between fluids. In general, the TMS400is discussed in the context of the aircraft10and the gas turbine engine100described above and shown inFIGS.1and2. However, the TMS400can be implemented within another type of aircraft and/or another gas turbine engine of another configuration.

As shown, the TMS400generally includes a first flow loop302aand a second flow loop302b. The first and second flow loops302a-bfurther include a first pump304aand a second pump304bto move the heat exchange fluid (e.g., supercritical carbon dioxide, etc.) through the first and second flow loops302a-b, respectively. The first flow loop302afurther includes at least one first heat source exchanger306aand at least one first heat sink exchanger308a. The second flow loop302bfurther includes at least one second heat source exchanger306band at least one second heat sink exchanger308b. The first pump304a(first flow loop302a) and the second pump304b(second flow loop302b) generate a closed-loop flow of the heat exchange fluid in the TMS400. Although three first and second heat source exchangers306a-bare illustrated inFIG.4, more or fewer (e.g., one, two, five, etc.) first and second heat source exchangers306a-bcan be included in the TMS400. Similarly, although two first and second heat sink exchangers308a-bare illustrated inFIG.4, more or fewer (e.g., one, three, five, etc.) first and second heat sink exchangers308a-bcan be included in the TMS400. In general, it can be appreciated that the first and second flow loops302a-brun parallel to each other, and that the TMS400ofFIG.4includes substantially similar elements as the TMS300ofFIG.3, as shown with like reference numbers.

As depicted inFIG.4, the first and second heat source exchangers306a-bare configured with common heat sources402such that each of the first heat source exchangers306aand the second heat source exchangers306bprovide independent and isolated heat removal capability (via the heat exchange fluid) to the common heat sources402. The common heat sources402can include, for example, a main lubrication system heat exchanger for transferring heat from the main lubrication system; a compressor cooling air (CCA) system heat source exchanger for transferring heat from the compressor (e.g., high-pressure compressor) of gas turbine engines; an active thermal clearance control (ACC) system heat source exchanger for transferring heat from the turbine casing of the gas turbine engines; a generator lubrication system heat source exchanger for transferring heat from the electric machine thermal system; an environmental control system (ECS) heat exchanger for transferring heat from air supplied to the main cabin; and/or an electronics cooling system heat exchanger for transferring heat from the electronics cooling system.

Although, the common heat sources402associated with each of the pairs of first and second heat source exchangers306a-bare identified by same reference numbers, the common heat sources402can be the same and/or different types of heat sources described above. Additionally or alternatively, one common heat source402can transfer heat to two or more pairs of first and second heat source exchangers306a-b. Similarly, two or more common heat sources402can transfer heat to one pair of first and second heat source exchangers306a-b. Thus, although three common heat sources402are illustrated inFIG.4, there can be a single common heat source402or multiple common heat sources402included in the TMS400.

In general, the first and second heat source exchangers306a-bare configured with the common heat sources402and are arranged in parallel. The hot medium (labeled “H” in the figures) splits and flows through the first and second heat source exchangers306a-bin parallel, and subsequently combines into a single cold medium flow (labeled “C” in the figures). In some examples, the common heat sources402can include an output/bleed port and in input port (not shown in the example view ofFIG.4). The bleed port can provide a flow of hot fluid to the first and second heat source exchangers306a-bin parallel, and the input port can receive cooled fluid from the first and second heat source exchangers306a-b. However, in some examples, the first and second heat source exchangers306a-bare arranged in series with each of the common heat sources402.

The first and second flow loops302a-binclude the heat sink exchangers308a-bto transfer heat from the heat exchange fluid to another fluid (e.g., atmosphere, fuel, compressed air stream, expanded air stream, etc.). For example, the heat sink exchangers308a-bcan include at least one of a ram air heat exchanger, a fuel heat exchanger, a fan stream heat exchanger, and/or a bleed air heat exchanger. The ram air heat exchanger can be configured as an “air to heat exchange fluid” heat exchanger integrated into one or both of the engine100and/or the aircraft10. During operation, the ram air heat exchanger may remove heat from the heat exchange fluid by flowing a certain amount of intake air over the ram air heat exchanger. Additionally, the fuel heat exchanger can be configured as a “liquid to heat exchange fluid” heat exchanger wherein heat from the heat exchange fluid is transferred to a stream of liquid fuel for the engine100. Moreover, the fan stream heat exchanger can generally be an “air to heat exchange fluid” heat exchanger to transfer heat from the heat exchange fluid to bypass air in the engine100. Further, the bleed air heat exchanger can generally be an “air to heat exchange fluid” heat exchanger to transfer heat from the heat exchange fluid to bleed air from the LP compressor section of the engine100.

As illustrated inFIG.4, the first heat sink exchangers308aare configured in series and the second heat sink exchangers308bare configured in series within the first and second flow loops302a-b, respectively. In some examples, two or more of the first and second heat sink exchangers308a-bare arranged in parallel flow within the first and second flow loops302a-b, respectively. As also illustrated inFIG.4, the heat exchange fluid flowing through the first heat sink exchangers308adoes not mix with the heat exchange fluid flowing through the second heat sink exchangers308b. Thus, it can be appreciated that the first and second flow loops302a-bprovide redundant and isolated heat removal capacity to the plurality of common heat sources402.

As depicted inFIG.4, the first and second flow loops302a-binclude first bypass conduits310a, second bypass conduits310b, first heat source valves312a, second heat source valves312b, first heat sink valves314a, and second heat sink valves314b. Similar to the TMS300ofFIG.3, the first and second bypass conduits310a-b, the first and second heat source valves312a-b, and the first and second heat sink valves314a-bprovide the TMS400with the capability to selectively isolate one or more of the first and/or second heat source and/or sink exchangers306a,306b,308a,308bto regulate the pressure the TMS400or to account for failures therein.

The first flow loop302ais isolated from the second flow loop302bsuch that the heat exchange fluid moving through the first flow loop302adoes not mix with the heat exchange fluid moving through the second flow loop302b. For example, although the first heat source exchangers306aand the second heat source exchangers306bcan be configured to remove heat from the same common heat sources402, the first and second heat source exchangers306a-bare structurally independent and fluidly isolated such that the heat exchange fluid moving through the respective first and second heat source exchangers306a-bdoes not mix.

Referring still toFIG.4, the example thermal management system400may utilize a refrigeration cycle to remove heat more efficiently from the various first and second heat source exchangers306a-b. Specifically, the first and second pumps304a-bcan be configured as first and second compressors to compress gaseous or supercritical heat exchange fluid, and the first and second flow loops302a-bcan include first and second expansion devices404a-b, respectively. The first and second expansion devices404a-bare included in the TMS400to expand the heat exchange fluid, which reduces the pressure and temperature thereof. In some examples, the first and second pumps304a-bare each powered by drive systems406a-b, respectively. In some examples, the drive systems406a-bare electric motors, such as direct current (DC) motors. In some other examples, the drive systems406a-binclude a gearing system (gearbox) mechanically coupled to a rotary component of the engine100, such as the LP spool106or the HP spool108. Although separate first and second drive systems406a-bare depicted, in some examples, a single drive system (such as a single electric motor) can provide mechanical power to both the first and second pumps304a-b.

Turning toFIG.5, a schematic diagram of an example first heat driven thermal management system500(TMS500) is provided in accordance with teachings disclosed herein. In general, the TMS500is discussed in the context of the aircraft10and the gas turbine engine100described above and shown inFIGS.1and2. However, the TMS500can be implemented within another type of aircraft and/or another gas turbine engine of another configuration.

The TMS500is configured in a single loop and includes the thermal transport bus (TTB)302, the heat source exchangers306, the heat sink exchangers308, the bypass conduits310, the heat source valves312, and the heat sink valves314similar to the TMS300ofFIG.3. In some examples, the TMS500can be configured in a parallel flow loop similar to the TMS400and can include the same elements illustrated inFIG.4. The TMS500includes a turbomachine502having a turbine504that takes in high temperature (e.g., 1300 degrees Rankine (° R) (722 Kelvin (K)), 1400° R (778 K), 1500° R (833 K), etc.) and high pressure (e.g., 2950 pounds per square inch (psi), 3000 psi, 3050 psi, etc.) heat exchange fluid (e.g., sCO2, He—Xe, LHe2, etc.), extracts power from the heat exchange fluid, and discharges low temperature (e.g., 600° R, 700° R, 800° R, etc.) and low pressure (e.g., 2900 psi, 2950 psi, 3000 psi, etc.) heat exchange fluid.

Upstream of the turbine504, the heat exchange fluid is diverted from the TTB302at a first point at which the pressure and temperature of the heat exchange fluid is substantially high, such as just downstream (e.g., within one meter) of one of the heat source exchangers306. In some examples, the first point is just downstream of a last one of the heat source exchangers306in flow serial order. In general, the first point is positioned downstream of the heat source exchangers306and upstream of the heat sink exchangers308. It can be appreciated that the first point is positioned where the thermal energy of the heat exchange fluid is most likely to be at optimum (highest) level(s) such that the turbine504can extract the maximum amount of (highest possible) energy for power generation.

The TMS500includes a compressor to pressurize the heat exchange fluid in the TTB302. The turbine504and the compressor506are rotatably interlocked and/or mounted on a shaft508. Thus, the turbine504extracts the power from the heat exchange fluid and transfers the power to the compressor506via the shaft508. In other words, the turbine504can convert thermal energy of the heat exchange fluid into mechanical work to rotate the compressor506via the shaft508. A portion (e.g., 50%, 60%, 70%, etc.) of the heat exchange fluid in the TTB302is diverted to the turbine504, which converts thermal energy (heat) of the heat exchange fluid into mechanical energy (work) to be used to power a pump (e.g., the compressor506). The turbine504can extract enough power (e.g. 3200 Watts (W), 3240 W, 3500 W, etc.) to cause the compressor506to sufficiently pressurize and drive the heat exchange fluid through the TTB302. Furthermore, the turbine504can extract sufficient power such that the compressor506can overcome pressure drops within the TMS500due to friction in the TTB302, energy loss in the heat sink exchangers308, etc. Thus, it can be appreciated that the turbomachine502enables the TMS500to start-up, operate, or otherwise be powered self-sufficiently using the heat that the heat exchange fluid absorbs. More specifically, the turbine504can power the compressor506rather than an electric motor to conserve weight and operate the TMS500more efficiently, relative to the TMS300and/or the TMS400, which use electric motors or other external power sources to drive the pump(s)304,304a, and/or304b. In some examples, the turbine504extracts an excessive amount of power (e.g., 4000 W, 5000 W, 6000 W, etc.), which can cause the compressor506to operate at excessive speeds. Such speeds may cause the heat exchange fluid to be over pressurized, which may cause damage to the TMS500. In some examples (described below), the turbomachine502can convert some of such excess mechanical power into electrical power for concurrent or future use.

In some examples, the turbine504is said to “expand” the heat exchange fluid, meaning that the pressure of the heat exchange fluid reduces (decompresses) while flowing through the turbine504, which also causes the temperature to decrease. In general, the turbine504expands the diverted portion of the heat exchange fluid and reintroduces the portion back to the TTB302at a second point at which the pressure and temperature of the heat exchange fluid is substantially low. In some examples, the second point is just upstream (e.g., within one meter) of the compressor506. In some other examples, the second point is just downstream of a last one of the heat sink exchangers308in flow serial order. In general, the second point is positioned downstream of the heat sink exchangers308and upstream of the compressor506.

The heat exchange fluid expands while flowing through the turbine504from a first inlet510to a first outlet512. In some examples, the turbine504is an axial turbine and the heat exchange fluid enters the first inlet510and exits the first outlet512parallel to the shaft508. In such examples, the turbine504includes consecutive stages of rotor blades and stator vanes. The first inlet510can be one or more stages substantially optimized for high pressures (e.g., 3000 psi, 3100 psi, 3200 psi, etc.), and the first outlet512can be one or more stages substantially optimized for low pressures (e.g., 2800 psi, 2900 psi, 3000 psi, etc.). The rotor blades can be mounted on a rotor disk coupled to the shaft508, and the stator vanes can be mounted on a stationary stator disk or another static structure in the turbine504. In some examples, the turbine504is a centrifugal turbine in which the heat exchange fluid enters the first inlet510radial to the impeller shaft508and exits the first outlet512parallel to the shaft508. In such examples, the turbine504can include an expeller coupled to the shaft508that rotates when high pressure fluid encounters the expeller substantially orthogonal to an axis of rotation. In some examples, the first outlet512is connected to the second point of the TTB302via one or more outlets and/or flowlines.

In general, the heat exchange fluid can compress while flowing through the compressor506from a second inlet514to a second outlet516. In some examples, the compressor506is an axial compressor and the heat exchange fluid enters the second inlet514and exits the second outlet516parallel to the shaft508. In such examples, the second inlet514can be one or more stages (set(s) of one stator disk following one rotor disk) substantially optimized for low pressures (e.g., 2800 psi, 2900 psi, 3000 psi, etc.), and the second outlet516can be one or more stages substantially optimized for high pressures (e.g., 2900 psi, 3000 psi, 3100 psi, etc.). When the turbine504and the compressor506are of example axial configurations, the shaft508can from the a distal end of the turbine504(e.g., the first outlet512) to a distal end of the compressor506(e.g., the second inlet514). In some examples, the compressor506is a centrifugal compressor and the heat exchange fluid enters the second inlet514axially (substantially parallel to the shaft508) and exits the second outlet516radially (substantially perpendicular to the shaft508). In such examples, the second inlet514includes a port (e.g., pipe, flowline, tube, etc.) connected to an impeller, which includes impeller vanes to pressurize and accelerate the fluid radially outward into in the second outlet516(e.g., volute chamber). In some examples, the first outlet512is connected to the TTB302via one or more outlets and/or flowlines.

Whether the turbine504and/or the compressor506have axial or centrifugal configurations, the turbomachine502can be designed as a thrust balanced system. In other words, axial thrust generated by fluid pressure on the first inlet510of the turbine504acts in a first direction, and axial thrust generated by fluid pressure on the second inlet514of the compressor506acts in a second direction opposite the first direction. Therefore, the axial thrusts at the turbine504and the compressor506offset each other, and the turbomachine502does not generate a substantially large thrust in either the first direction or the second direction. In some examples, the turbomachine502is completely thrust balanced, and no thrust is generated in either the first direction or the second direction due to fluid pressures. In some other examples, a substantially small thrust is generated such that structures to support the turbomachine502do not become strained beyond a yield stress point.

Generally, it should be appreciated that, although arrows leading to/from the turbine504and the compressor506are illustrated as substantially orthogonal to the shaft508, flowlines leading to/from the inlets510,514and the outlets512,516can be substantially orthogonal or parallel to the shaft508and/or another combination thereof. Although the illustrated example ofFIG.5shows the first inlet510and second outlet516proximal to the shaft508and the first outlet512and the second inlet514distal to the shaft508, in some examples, the turbine504and the compressor506(axial turbine and axial compressor) can be oriented such that the first inlet510and second outlet516are distal to the shaft508, the first outlet512and the second inlet514are proximal to the shaft508, and/or another combination thereof.

In terms of a primary flow path of the heat exchange fluid, the TTB302(primary flowline) originates at the second outlet516and terminates (loops back to) at the second inlet514of the compressor506. As mentioned previously, a portion of the heat exchange fluid diverts from the TTB302at the first point, at which point the portion of the fluid enters a secondary flowline518(secondary flowline). Since the pressure at the first point is higher than the pressure at the second point, the portion of the heat exchange fluid is pulled into the secondary flowline518via pressure driven flow. The heat exchange fluid in the secondary flowline518is permitted to the turbine504at a flowrate, and the flowrate is determined based on opening of a control valve520, the diameter(s) of the secondary flowline518, the properties of the heat exchange fluid (e.g., temperature, pressure, density, viscosity, etc.), etc. The flowrate of the heat exchange fluid at the turbine504can determine the rate at which the turbomachine502operates, and thus, the pressure output of the compressor506. In general, the rotational speed of the turbomachine502, the flowrate of the heat exchange fluid in the TTB302, and/or the pressure of the heat exchange fluid in the TTB302can determine a position (e.g., opened, closed, partially opened, etc.) of the control valve520.

In some examples, the control valve520is a pneumatic valve that is hydraulically actuated via the pressure of the heat exchange fluid in the TTB. The term “pneumatic” is used herein to describe a mechanism containing or being operated by a supercritical fluid under pressure. The term “hydraulic” is used herein to describe a movement or a force caused by supercritical fluid under pressure. A hydraulic supply line can lead from the TTB302and/or the secondary flowline518to the control valve520such that if the pressure within the TTB302satisfies (e.g., exceeds) a pressure threshold, the hydraulic force of the heat exchange fluid can cause the control valve520to close. In the illustrated example ofFIG.5, the control valve520is an electronic valve operated by a control system522(discussed below with reference toFIG.8). For example, the control valve520is an automatic valve, such as a quick opening valve, that can switch between fully open and fully closed states substantially instantaneously to essentially turn the flow on or off. In another example, the control valve520is a proportional valve that can generate variable apertures (e.g., partial effective areas) ranging from a fully open area to a fully closed area to adjust the flowrate gradually.

The TMS500illustrated inFIG.5includes a speed sensor524to measure an angular velocity of the turbomachine502. In some examples, the speed sensor524is a tachometer coupled to the shaft508to detect the rotations per minute (rpm) of the turbine504and/or the compressor506. The control system522can be an automatic and/or closed loop controller (e.g., proportional-integral-derivative (PLD) controller, full authority digital electronics controller (FADEC), etc.) that obtains an input signal (e.g., electronic signal, etc.) from the speed sensor524representing the speed of the turbomachine502and sends an output (e.g., control signal, etc.) to the control valve520representing a position of an actuator (e.g., plunger, shaft, valve, gate, ball, globe, etc.). In other words, the control system522causes the control valve520to open or close (fully or partially) based on the speed of the shaft508, the turbine504, and/or the compressor506.

In an example use case, the aircraft10begins operation and the engine100and/or other onboard elements begin heating the heat exchange fluid in the TMS500via the heat source exchangers306. As the temperature rises, the fluid pressure increases and causes the heat exchange fluid to flow in the direction of the arrows as illustrated inFIG.5. Before operation or during startup of the TMS500, the control system522can cause the control valve to open and permit the heat exchange fluid to enter the first inlet510via the secondary flowline518. As the turbine504extracts energy from the fluid, rotates the shaft508, and powers the compressor506, the control system522obtains rotational speed measurements from the speed sensor524. When the turbomachine502(e.g., the shaft508) spins at a rate that satisfies (e.g., exceeds) a first speed threshold (e.g., 35000 rpm, 40000 rpm, 45000 rpm, etc.), the control system522causes the control valve520to close. In some examples, the control system522causes the control valve520to partially close, reduce the flowrate in the secondary flowline518, and progressively reduce the rotational speed of the turbomachine502. However, in general, the control valve520fully closes when the rotational speed satisfies the first speed threshold to slow the turbine504as quickly as possible to avoid damages to the TMS500and the elements therein. In some examples, the first speed threshold corresponds to a rotational speed of the compressor506at which the output pressure and/or flowrate of the compressor506can cause accelerated wear and/or catastrophic damage to the TTB302, the heat source exchangers306, heat sink exchangers308, etc.

The TMS500further includes a check valve526to ensure that the heat exchange fluid flows in one direction and to prevent backflow in the secondary flowline518. As illustrated inFIG.5, the check valve526is positioned upstream of the control valve520such that, if the turbomachine502, the control system522, and/or the control valve520cease operation and cause a pressure build up in the secondary flowline518, the heat exchange fluid does not reverse flow toward the first point of the TTB302. Thus, if fluid pressure downstream of the check valve526is equal to or greater than the fluid pressure upstream, the check valve526closes and obstructs the reversed flow. The check valve can be a two-port valve that operates automatically without aid of the control system522, such as a ball check valve, a diaphragm check valve, a lift-check valve, an in-line check valve, etc.

Turning now toFIG.6, a schematic diagram of an example second heat driven thermal management system600(TMS600) is provided in accordance with teachings disclosed herein. In general, the TMS600is discussed in the context of the aircraft10and the gas turbine engine100described above and shown inFIGS.1and2. However, the TMS600can be implemented within another type of aircraft and/or another gas turbine engine of another configuration.

The TMS600is configured in a single loop and includes a first thermal transport bus (TTB)602a, a second TTB602b, and a third TTB602c. Similar to the TMS500ofFIG.5, the first TTB602aoriginates at the second outlet516and loops back to the second inlet514of the compressor506. The TMS600also includes the second TTB602bto branch off the first TTB602asuch that a portion of the first TTB602aruns concurrently with a portion of the second TTB602b. Additionally, the TMS600includes a third TTB602cthat can run parallel to the first TTB602a.

The TMS600includes first heat source exchangers306a, a second heat source exchanger306b, and a third the heat source exchanger306c. In some examples the first heat source exchangers306aare CCA heat exchangers that operate concurrently, absorb heat from compressed bleed air at the compressor section122of the gas turbine engine100, and direct cooled compressed air to the turbine section126of the engine100. In some examples, the second heat source exchanger306bis a waste heat recovery (WHR) heat exchanger that draws heat from other, hotter element(s) of the engine100(e.g., the combustion section124, HP turbine138, etc.). As such, the first point at which the secondary flowline518diverts from the second TTB602bis just downstream of the second heat source exchanger306bbecause the second heat source exchanger306bcan transfer the most heat to the heat exchange fluid. However, in some other examples, the second heat source exchanger306bis not included in the TMS600, and the first point is located just downstream of the first heat source exchangers306a. Similar to the TMS300, TMS400, and/or the TMS500, the TMS600includes the heat source valve312to selectively bypass the first or second heat source exchangers306a-b.

In some examples, the third heat source exchanger306cis a fuel cooled oil cooler (FCOC) heat exchanger that is connected to the third TTB602cand the heat sink valve314. The third heat source exchanger can heat fuel (e.g., Jet A, Jet A-1, etc.) via heated oil and transmit the heated fuel to the heat sink valve314. The heat sink valve314can either send the heated fuel to a combustor (e.g., the combustion section124) or to a first heat sink exchanger308ato be further heated before flowing to the combustor. The TMS600also includes a second heat sink exchanger308bto further remove heat from the heat exchange fluid in the first TTB602aand to add said heat to bleed air in the engine100, the compressor section122, etc. In parallel with the second heat sink exchanger308b, the TMS600includes a third heat sink exchanger308cto remove heat from the oil and further add heat to the bleed air.

Other than those mentioned above with reference toFIG.6, the TMS600includes the same elements as the TMS500ofFIG.5. Thus, the TMS600includes the turbomachine502, which further includes the turbine504and the compressor506mounted on the shaft508. Moreover, the turbine504of the TMS600includes the first inlet510and the outlet512, and the compressor506of the TMS600includes the second inlet514and the second outlet516. The TMS600also includes the secondary flowline518to transmit the high energy heat exchange fluid to the turbine504, the control valve520to permit/restrict flow to the turbine504, and the control system522to determine when to open/close the control valve520based on the rotational speed of the shaft508measured with the speed sensor524. Lastly, the TMS600includes the check valve526in the secondary flowline518to prevent backflow of the heat exchange fluid therein.

Although the first, second, and third heat source exchangers306a-cand the first, second, and third heat sink exchangers308a-care included in the TMS600, more or fewer heat source and/or heat sink exchangers can be included therein. Similarly, the TMS600can include more or fewer TTBs than the first, second, and third TTBs602a-cbased on the operational requirements of the engine100, aircraft10, or another gas turbine engine or aircraft. As such, it should be appreciated that example heat driven thermal management systems disclosed herein can include one turbomachine502to drive one or more concurrent TTBs, such as the first and second TTB602a-bofFIG.6. Additionally or alternatively, example heat driven thermal management systems disclosed herein can include a plurality of turbomachines502to drive the heat exchange fluid through a plurality of TTBs that run in parallel.

Turning now toFIG.7, a schematic diagram of an example third heat driven thermal management system700(TMS700) is provided in accordance with teachings disclosed herein. In general, the TMS700is discussed in the context of the aircraft10and the gas turbine engine100described above and shown inFIGS.1and2. However, the TMS700can be implemented within another type of aircraft and/or another gas turbine engine of another configuration.

In general, the TMS700ofFIG.7includes the same elements as the TMS600ofFIG.6. However, the TMS700ofFIG.7includes a turbomachine702with similar elements as the turbomachine502, but the turbomachine702also includes a motor and generator unit704(M/G unit704) coupled to the shaft508. In general, the turbomachine702includes the M/G unit704to supplement the power that the turbine504provides to the compressor506and/or to draw power from the turbine504itself. For example, when the turbomachine702of is operating at a rotational speed that is below a second speed threshold (e.g., 25000 rpm, 30000 rpm, 35000 rpm), the M/G unit704can function as a motor to bring the compressor506up to operating speeds (e.g., 32000 rpm, 35000 rpm, 37000 rpm, etc.) faster than the turbine504(or a motor) can independently. Furthermore, since the turbine504provides a portion of the power used to bring the compressor506to the operating speeds, the M/G unit704can operate more efficiently, consume less electrical energy, rely on less maintenance, and can be of a lesser size or weight than, for example, a motor associated with the pump304ofFIG.3and/or the first and second pumps304a-bofFIG.4.

The M/G unit704ofFIG.7can be configured similarly to a motor (e.g., brushed direct current (DC) motor, brushless DC motor, permanent magnet motor, etc.) wherein an armature with multiple windings of an electrically conductive wire (e.g., copper wire) is affixed to the shaft508, and a stator surrounds the armature. When an electric current is supplied to the windings in the armature of the M/G unit704, magnetic fields are generated, and permanent magnets in the stator apply a magnetic force on the windings, which rotates the shaft. Alternating electrical currents are supplied to each of the windings in the armature to cause the shaft508to continually rotate. Furthermore, the speed of the current alternation and the amount of voltage associated with the electrical currents can influence the amount of torque the shaft508generates. Additionally, when electrical current is not supplied to the M/G unit704, and an external mechanical power (e.g., from the turbine504) causes the armature to rotate within the stator, electrical currents are generated in the windings. In other words, based on Faraday's law of induction, the M/G unit704can convert electrical power into mechanical power and can also convert mechanical power into electrical power.

The control system522can cause a power source, such as a battery or a generator (e.g., gas turbine engine100) on the aircraft10, to supply electrical power to the M/G unit704when the turbomachine702operates at a rotational speed that does not satisfy (e.g., is below) the second speed threshold. More specifically, when the compressor506does not convert a sufficient amount of mechanical power into kinetic energy of the heat exchange fluid, the rotational speed is said to not satisfy the second speed threshold, and the control system522causes the power source to supply electrical power to the M/G unit704. Alternatively, when the turbomachine702operates at rotational speeds that satisfy (e.g., match or exceed) the second speed threshold, the control system522causes the power source to cease transmission of electrical power to the M/G unit704and routes the current of electrical power from the M/G unit704to a power sink, such as onboard system(s) (e.g., cabin lighting, cabin air conditioning, fuel management system, etc.), electromechanical component(s) (e.g., pumps, heaters, actuators, etc.), and/or a battery. In some examples, the M/G unit704is electrically connected to a demultiplexer (not shown) that leads to a plurality of power sinks, and the control system522can cause the demultiplexer to switch between the plurality of power sinks based on a command input or written instructions and/or operations stored on storage device(s) and/or on a machine readable medium (discussed below). In such examples, the control system522can cause the demultiplexer to switch to a battery to store electrical power when the charge of the battery depletes to a particular level.

Turning now toFIG.8, a block diagram of the control system522to open and close (fully and/or partially) the control valve520based on the rotational speed of the turbomachine502ofFIGS.5and6and/or the turbomachine702ofFIG.7is provided. The control system522of the illustrated example ofFIG.8includes example interface circuitry802, example rotational speed loop circuitry804, example valve controller circuitry806, example operating mode determination circuitry808, and example data storage810. The control system522ofFIGS.5-8may be instantiated (e.g., creating an instance of, bring into being for any length of time, materialize, implement, etc.) by processor circuitry such as a central processing unit executing instructions. Additionally or alternatively, the control system522ofFIGS.5-8may be instantiated (e.g., creating an instance of, bring into being for any length of time, materialize, implement, etc.) by application specific integrated circuit(s) (ASIC(s)) or Field Programmable Gate Array(s) (FPGA(s)) structured to perform operations corresponding to the instructions. It should be understood that some or all of the circuitry ofFIG.8may, thus, be instantiated at the same or different times. Some or all of the circuitry may be instantiated, for example, in one or more threads executing concurrently on hardware and/or in series on hardware. Moreover, in some examples, some or all of the circuitry ofFIG.8may be implemented by microprocessor circuitry executing instructions to implement one or more virtual machines and/or containers.

The control system522includes the interface circuitry802to synchronize operation between input/output device(s) and circuitry (e.g., processor circuitry) of the control system522. In some examples, the interface circuitry802is instantiated by processor circuitry executing interface instructions and/or configured to perform operations such as those represented by the flowchart ofFIG.9. In some examples, the aircraft10includes the input device(s) (e.g., switch(es), dial(s), button(s), knob(s), keyboard(s), touchpad(s), etc.) in a cockpit or another control center onboard. Using such input device(s), the operator can cause the TMS(s)500,600, and/or700to begin pumping the heat exchange fluid through the TTB(s)302and/or602a. For example, when the aircraft10has begun or is preparing to begin operation, the pilot can provide an input to the control system indicating that the turbomachine(s)502and/or702is/are to begin pumping. In such an example, the interface circuitry802can generate and/or direct a signal to other circuitry of the control system522, which can cause the control valve520to open.

The control system522includes the rotational speed loop circuitry804(“speed circuitry804”) to obtain data (e.g., speed measurements) from the speed sensor524and to determine whether the measured speed of the turbomachine(s)502and/or702(e.g., shaft508) satisfies the first speed threshold. In some examples, the speed circuitry804is instantiated by processor circuitry executing rotational speed loop instructions and/or configured to perform operations such as those represented by the flowchart ofFIG.9. The speed circuitry804can function as a closed loop controller that obtains input feedback (e.g., rotational speed of the shaft508) from the speed sensor524and sends output data (e.g., position of the control valve520) to the valve controller circuitry806of the control system522. For example, at predetermined intervals (e.g., 1 second (s), 5 s, 10 s, etc.) the speed circuitry804can query the speed sensor524to detect the current (most up to date) rotational speed of the shaft508, the turbine504, etc. In such an example, the speed circuitry804compares the rotational speed of the shaft508(shaft speed) to the first speed threshold to determine whether the shaft speed satisfies (e.g., matches or exceeds) the first speed threshold. When the speed circuitry804determines, processes, and/or verifies that the shaft speed satisfies the first speed threshold, the rotational speed loop circuitry804can send a signal to the valve controller circuitry806to close the control valve520, which causes the flow of the heat exchange fluid in the secondary flowline518to cease, the shaft speed of turbine504to slow down, and the output pressure of the compressor506to reduce, thus reducing the flowrate of the heat exchange fluid in the primary flowline(s) (e.g., TTB(s)302,602a, and/or602b).

The control system522of the example ofFIG.8includes the valve controller circuitry806(“valve circuitry806”) to receive signals indicating a desired valve position from the speed circuitry804, determine a current state of the control valve520, and cause the position of the control valve520to change based on the received signals and the current state of the control valve520. In some examples, the valve circuitry806is instantiated by processor circuitry executing valve controller instructions and/or configured to perform operations such as those represented by the flowchart ofFIG.9. In some examples, the speed circuitry804sends a signal to the valve circuitry806to close the control valve520due to excessive shaft speeds. When the valve circuitry806receives such a signal, the valve circuitry806determines whether the control valve520is currently set to an open or a closed state. For example, the valve circuitry806can query the control valve520to detect a position of a mechanism (e.g., plunger, ball, gate, etc.) therein. In some examples, the valve circuitry806detects one of an open state or a closed state when the control valve520is a quick opening valve or another valve of the like. In some other examples, the valve circuitry806detects one of an open state, a closed state, or a partially closed state when the control valve520is a proportional valve or another valve of the like. In such examples, the partially closed state can be represented as 20% open, 50% open, etc. Furthermore, in such examples, the valve controller circuitry806can be configured as a closed loop controller that receives positional feedback from the control valve520and continues to send output signals that cause the control valve520to actuate until the valve circuitry806determines that the control valve520is at the proper position based on a predetermined flowrate (e.g., reduced flowrate) in the secondary flowline518. In general, the speed circuitry804determines when the shaft speed of the turbine504satisfies the first speed threshold, indicates to the valve circuitry806that the turbine504is rotating at excessive speeds, and the valve circuitry806causes the control valve520to close. Moreover, when the speed circuitry804determines that the speed of the turbomachine(s)502and/or702no longer satisfies the first speed threshold, the speed circuitry804sends a signal to the valve circuitry806, which causes the control valve520to open again.

The control system522of the example ofFIG.8includes the operating mode determination circuitry808(“mode circuitry808”) to determine whether the M/G unit704is to operate as a motor or a generator and to cause the M/G unit704to “change modes” accordingly. In some examples, the mode circuitry808is instantiated by processor circuitry executing operating mode determination instructions and/or configured to perform operations such as those represented by the flowcharts ofFIGS.9and/or10. Similarly to the speed circuitry804, the mode circuitry808functions as a closed loop controller that continually obtains (e.g., at predetermined intervals) speed measurements from the speed sensor524and compares the rotational speed of the shaft508to the second speed threshold. When the shaft speed does not satisfy the second speed threshold, the M/G unit704is to operate as a motor (in a “motor mode”) to supplement the mechanical power that the turbine504provides to the compressor506. To cause the M/G unit704to operate in the motor mode, the mode circuitry808and/or the interface circuitry802can send a signal to a controller (e.g., programmable circuitry, etc.) of an electrical power source (e.g., battery, generator, etc.) to transmit electrical power to the M/G unit704. In some examples, the mode circuitry808commands a controller of the M/G unit704to utilize electrical energy from the power source to generate electric current in the windings of the armature coupled to the shaft508. In some other examples, the control system522directly controls the M/G unit704, and the mode circuitry808operates the M/G unit704as a motor by causing electrical power to transmit to the armature of the M/G unit704. In such examples, the mode circuitry808can trigger a first switch to permit electrical current to flow from the power source to the windings of the armature.

In some examples, when the M/G unit704operates as a motor, the mode circuitry808can cause the M/G unit704to supply a variable amount of mechanical power to the shaft508. For example, when a first shaft speed is detected, the mode circuitry808can cause the M/G unit704to supply a first amount of mechanical power to the shaft508. In such an example, when a second shaft speed is detected, the mode circuitry808can cause the M/G unit704to supply a second amount of mechanical power to the shaft508. The first amount of mechanical power is greater than the second amount of mechanical power, and the first shaft speed less than the second shaft speed. Thus, as the rotational speed of the turbomachine(s)502and/or702increase(s) from startup speeds to the second speed threshold, the mode circuitry808can cause the M/G unit704to gradually reduce the amount of supplemental power provided to further conserve energy and operate the M/G unit704more efficiently.

When the shaft speed satisfies the second speed threshold, the M/G unit704is to operate as a generator (in a “generator mode”) to produce electrical power induced from rotation of the shaft508. In some examples, the second speed threshold corresponds to an operating speed that is less than the first speed threshold and that is sufficient for the compressor506to overcome pressure drops across the TMS(s)500,600, and/or700. As such, when the turbomachine(s)502and/or702operate(s) at shaft speeds that satisfy the second speed threshold, the turbine504transfers an excess of mechanical power to the compressor506. Rather than wasting the excess of mechanical power on the compressor506, the M/G unit704can use the excess mechanical power to generate electrical power to be used elsewhere. The generated electrical power can be routed to a power sink, such as an onboard system (e.g., environmental control systems, flight instruments, engine instruments, etc.), a battery to store the electrical energy for later use, etc. To cause the M/G unit704to operate in the generator mode, the mode circuitry808and/or the interface circuitry802can send a signal to the controller of the electrical power source to cease transmission of electrical power to the M/G unit704. In some examples, the mode circuitry808commands the controller of the M/G unit704to transmit electrical energy from the windings of the armature to the power sink. In some other examples, the control system522directly controls the M/G unit704, and the mode circuitry808operates the M/G unit704as a generator by causing electrical power to transmit from the armature of the M/G unit704. In such examples, the mode circuitry808can trigger a second switch to permit electrical current to flow from the windings of the armature to the power sink.

The control system522includes the data storage810to store data (e.g., speed measurements, thresholds, current operating conditions, etc.) or any information associated with the interface circuitry802, the rotational speed loop circuitry804, the valve controller circuitry806, and/or the operating mode determination circuitry808. The example data storage810of the illustrated example ofFIG.8can be implemented by any memory, storage device and/or storage disc for storing data, such as flash memory, magnetic media, optical media, etc. Furthermore, the data stored in the example data storage810can be in any data format such as binary data, comma delimited data, tab delimited data, structured query language (SQL) structures, image data, etc.

While an example manner of implementing the control system522ofFIGS.5-8is illustrated inFIG.8, one or more of the elements, processes, and/or devices illustrated inFIG.8may be combined, divided, re-arranged, omitted, eliminated, and/or implemented in another way. Further, the example interface circuitry802, the example rotational speed loop circuitry804, the example valve controller circuitry806, the example operating mode determination circuitry808, and/or, more generally, the example control system522ofFIGS.5-8, may be implemented by hardware alone or by hardware in combination with software and/or firmware. Thus, for example, any of the example interface circuitry802, the example rotational speed loop circuitry804, the example valve controller circuitry806, the example operating mode determination circuitry808, and/or, more generally, the example control system522, could be implemented by processor circuitry, analog circuit(s), digital circuit(s), logic circuit(s), programmable processor(s), programmable microcontroller(s), graphics processing unit(s) (GPU(s)), digital signal processor(s) (DSP(s)), ASIC(s), programmable logic device(s) (PLD(s)), and/or field programmable logic device(s) (FPLD(s)) such as FPGA(s). Further still, the example control system522ofFIGS.5-8may include one or more elements, processes, and/or devices in addition to, or instead of, those illustrated inFIG.8, and/or may include more than one of any or all of the illustrated elements, processes and devices.

Flowcharts representative of example machine readable instructions, which may be executed to configure processor circuitry to implement the control system522ofFIGS.5-8, are shown inFIGS.9and10. The machine readable instructions may be one or more executable programs or portion(s) of an executable program for execution by processor circuitry, such as processor circuitry1112shown in an example processor platform1100discussed below in connection withFIG.11. The program may be embodied in software stored on one or more non-transitory computer readable storage media such as a compact disk (CD), a floppy disk, a hard disk drive (HDD), a solid-state drive (SSD), a digital versatile disk (DVD), a Blu-ray disk, a volatile memory (e.g., Random Access Memory (RAM) of any type, etc.), or a non-volatile memory (e.g., electrically erasable programmable read-only memory (EEPROM), FLASH memory, an HDD, an SSD, etc.) associated with processor circuitry located in one or more hardware devices, but the entire program and/or parts thereof could alternatively be executed by one or more hardware devices other than the processor circuitry and/or embodied in firmware or dedicated hardware. The machine readable instructions may be distributed across multiple hardware devices and/or executed by two or more hardware devices (e.g., a server and a client hardware device). For example, the client hardware device may be implemented by an endpoint client hardware device (e.g., a hardware device associated with a user) or an intermediate client hardware device (e.g., a radio access network (RAN)) gateway that may facilitate communication between a server and an endpoint client hardware device). Similarly, the non-transitory computer readable storage media may include one or more mediums located in one or more hardware devices. Further, although the example program is described with reference to the flowcharts illustrated inFIGS.9and10, many other methods of implementing the example control system522may alternatively be used. For example, the order of execution of the blocks may be changed, and/or some of the blocks described may be changed, eliminated, or combined. Additionally or alternatively, any or all of the blocks may be implemented by one or more hardware circuits (e.g., processor circuitry, discrete and/or integrated analog and/or digital circuitry, an FPGA, an ASIC, a comparator, an operational-amplifier (op-amp), a logic circuit, etc.) structured to perform the corresponding operation without executing software or firmware. The processor circuitry may be distributed in different network locations and/or local to one or more hardware devices (e.g., a single-core processor (e.g., a single core central processor unit (CPU)), a multi-core processor (e.g., a multi-core CPU, an XPU, etc.) in a single machine, multiple processors distributed across multiple servers of a server rack, multiple processors distributed across one or more server racks, a CPU and/or a FPGA located in the same package (e.g., the same integrated circuit (IC) package or in two or more separate housings, etc.).

The machine readable instructions described herein may be stored in one or more of a compressed format, an encrypted format, a fragmented format, a compiled format, an executable format, a packaged format, etc. Machine readable instructions as described herein may be stored as data or a data structure (e.g., as portions of instructions, code, representations of code, etc.) that may be utilized to create, manufacture, and/or produce machine executable instructions. For example, the machine readable instructions may be fragmented and stored on one or more storage devices and/or computing devices (e.g., servers) located at the same or different locations of a network or collection of networks (e.g., in the cloud, in edge devices, etc.). The machine readable instructions may require one or more of installation, modification, adaptation, updating, combining, supplementing, configuring, decryption, decompression, unpacking, distribution, reassignment, compilation, etc., in order to make them directly readable, interpretable, and/or executable by a computing device and/or other machine. For example, the machine readable instructions may be stored in multiple parts, which are individually compressed, encrypted, and/or stored on separate computing devices, wherein the parts when decrypted, decompressed, and/or combined form a set of machine executable instructions that implement one or more operations that may together form a program such as that described herein.

In another example, the machine readable instructions may be stored in a state in which they may be read by processor circuitry, but require addition of a library (e.g., a dynamic link library (DLL)), a software development kit (SDK), an application programming interface (API), etc., in order to execute the machine readable instructions on a particular computing device or other device. In another example, the machine readable instructions may need to be configured (e.g., settings stored, data input, network addresses recorded, etc.) before the machine readable instructions and/or the corresponding program(s) can be executed in whole or in part. Thus, machine readable media, as used herein, may include machine readable instructions and/or program(s) regardless of the particular format or state of the machine readable instructions and/or program(s) when stored or otherwise at rest or in transit.

The machine readable instructions described herein can be represented by any past, present, or future instruction language, scripting language, programming language, etc. For example, the machine readable instructions may be represented using any of the following languages: C, C++, Java, C #, Perl, Python, JavaScript, HyperText Markup Language (HTML), Structured Query Language (SQL), Swift, etc.

As mentioned above, the example operations ofFIGS.9and10may be implemented using executable instructions (e.g., computer and/or machine readable instructions) stored on one or more non-transitory computer and/or machine readable media such as optical storage devices, magnetic storage devices, an HDD, a flash memory, a read-only memory (ROM), a CD, a DVD, a cache, a RAM of any type, a register, and/or any other storage device or storage disk in which information is stored for any duration (e.g., for extended time periods, permanently, for brief instances, for temporarily buffering, and/or for caching of the information). As used herein, the terms non-transitory computer readable medium, non-transitory computer readable storage medium, non-transitory machine readable medium, and non-transitory machine readable storage medium are expressly defined to include any type of computer readable storage device and/or storage disk and to exclude propagating signals and to exclude transmission media. As used herein, the terms “computer readable storage device” and “machine readable storage device” are defined to include any physical (mechanical and/or electrical) structure to store information, but to exclude propagating signals and to exclude transmission media. Examples of computer readable storage devices and machine readable storage devices include random access memory of any type, read only memory of any type, solid state memory, flash memory, optical discs, magnetic disks, disk drives, and/or redundant array of independent disks (RAID) systems. As used herein, the term “device” refers to physical structure such as mechanical and/or electrical equipment, hardware, and/or circuitry that may or may not be configured by computer readable instructions, machine readable instructions, etc., and/or manufactured to execute computer readable instructions, machine readable instructions, etc.

FIG.9is a flowchart representative of example machine readable instructions and/or example operations900that may be executed and/or instantiated by processor circuitry to adjust a mechanical power output of the turbine504based on the shaft speed of the turbomachine(s)502and/or702. The machine readable instructions and/or the operations900ofFIG.9begin at block902, at which the control system522determines whether the control valve520is open. For example, the valve controller circuitry806(“valve circuitry806”) can query the control valve520on a position of mechanism(s) therein to determine whether the control valve520is in an open or a closed state. When the valve circuitry806determines that the control valve520is open, the example operations900proceed to block906. When the valve circuitry806determines that the control valve520is closed, the example operations900proceed to block904.

At block904, the control system522opens the control valve520. For example, the valve circuitry806can send an electrical command signal to the control valve520to cause the mechanism(s) therein to actuate and open the control valve520. As mentioned previously, in some examples, the control valve520can be variably opened based on a desired output flowrate.

At block906, the control system522detects the shaft speed of the turbomachine(s)502and/or702. For example, the rotational speed loop circuitry804(“speed circuitry804”) queries the speed sensor524for the current and/or most recent shaft speed measurement. As mentioned previously, the shaft speed measurement corresponds to the rotational speed and/or the angular velocity of the turbomachine(s)502and/or702, and more specifically, the turbine504, the compressor506, and the shaft508.

At block908, the control system522determines an operating mode of the M/G unit704. For example, the operating mode determination circuitry808(“mode circuitry808”) can cause the M/G unit704to operate as a motor or as a generator based on the measured shaft speed. Further details of the operations of block908are described below with connection toFIG.10.

At block910, the control system522determines whether the shaft speed satisfies the first speed threshold. For example, the speed circuitry804compares the shaft speed to the first speed threshold to determine whether the shaft speed is greater than, less than, or equal to the first speed threshold. When the speed circuitry804determines that the shaft speed does not satisfy (e.g., is less than) the first speed threshold, the operations900proceed to block916. When the speed circuitry804determines that the shaft speed satisfies (e.g., is greater than or equal to) the first speed threshold, the operations900proceed to block912.

At block912, the control system522determines whether the control valve520is closed. For example, the valve circuitry806queries the control valve520regarding a position of the mechanism(s) therein to determine whether the control valve520is in an open or a closed state. When the valve circuitry806determines that the control valve520is closed, the example operations900return to block910. When the valve circuitry806determines that the control valve520is open, the example operations900proceed to block914.

At block914, the control system522closes the control valve520. For example, the valve circuitry806can send an electrical command signal to the control valve520to cause the mechanism(s) therein to actuate and close the control valve520. As mentioned previously, in some examples, the control valve520can be variably closed based on a desired output flowrate.

At block916, the control system522determines whether the TMS(s)500,600, and/or700is/are to continue pumping the heat exchange fluid (e.g., sCO2, liquid helium, helium-xenon, etc.) through the TTB(s)302,602a,602b, and/or602c. For example, the interface circuitry802can detect whether an input signal was received via the input device(s) mentioned previously. The input signal is a command from an operator indicating that the turbomachine(s)502and/or702is/are to cease the pressurization of the heat exchange fluid. When the interface circuitry802determines that the TMS(s)500,600, and/or700is/are to continue pumping, the operations900return to block902. When the interface circuitry802determines that the TMS(s)500,600, and/or700is/are not to continue pumping, the operations900end and the valve circuitry806can cause the control valve520to close.

FIG.10is a flowchart representative of example machine readable instructions and/or example operations1000that may be executed and/or instantiated by processor circuitry to cause the M/G unit704to determine an operating mode (e.g., a motor mode or a generator mode) based on the shaft speed of the turbomachine(s)502and/or702(e.g., block908of the example ofFIG.9). The machine readable instructions and/or the operations1000ofFIG.10begin at block1002, at which the control system522determines whether the shaft speed satisfies the second speed threshold. For example, the mode circuitry808compares the shaft speed to the second speed threshold to determine whether the shaft speed is greater than, less than, or equal to the second speed threshold. When the mode circuitry808determines that the shaft speed does not satisfy (e.g., is less than) the second speed threshold, the operations1000proceed to block1004. When the mode circuitry808determines that the shaft speed satisfies (e.g., is greater than or equal to) the second speed threshold, the operations1000proceed to block1008.

At block1004, the control system522determines whether the M/G unit704is operating as a motor. For example, the mode circuitry808determines whether electrical power is being supplied to armature windings of the M/G unit704from a power source. In some examples, one or more sensors is/are coupled to circuitry connection(s) between the M/G unit704and the power source. In such examples, the mode circuitry808queries the sensor(s) to detect whether electrical current is flowing to the M/G unit704. Additionally or alternatively, the M/G unit704can include a first circuit switch to regulate flow of electrical current incoming to the M/G unit704and a second circuit switch to regulate flow of electrical current outgoing from the M/G unit704. Thus, in some examples, the mode circuitry808determines whether the first circuit switch is active based on a query to the M/G unit704.

At block1006, the control system522causes the M/G unit704to operate as a motor. For example, the mode circuitry808can cause the power source to transmit electrical power to the M/G unit704. Additionally or alternatively, the mode circuitry808can activate the first circuit switch, allow electrical current to flow to the armature windings of the M/G unit704, and deactivate the second circuit switch if already activated.

At block1008, the control system522determines whether the M/G unit704is operating as a generator. For example, the mode circuitry808determines whether electrical power is being supplied to a power sink from the armature windings of the M/G unit704. In some examples, the mode circuitry808queries the sensor(s) to detect whether electrical current is flowing to the power sink. Additionally or alternatively, the mode circuitry808can determine whether the second circuit switch is activated based on a query to the M/G unit704.

At block1010, the control system522causes the M/G unit704to operate as a generator. For example, the mode circuitry808can cause the M/G unit704to transmit electrical power to the power sink. Additionally or alternatively, the mode circuitry808can activate the second circuit switch, allow electrical current to flow from the armature windings of the M/G unit704, and deactivate the first circuit switch if already activated. Following completion of one or more of the blocks1002-1010, the example operations1000return to block910ofFIG.9.

FIG.11is a block diagram of an example processor platform1100structured to execute and/or instantiate the machine readable instructions and/or the operations ofFIGS.9and10to implement the control system522ofFIGS.5-8. The processor platform1100can be, for example, a personal computer, a workstation, a self-learning machine (e.g., a neural network), a mobile device (e.g., a cell phone, a smart phone, a tablet such as an iPad™), a headset (e.g., an augmented reality (AR) headset, a virtual reality (VR) headset, etc.) or other wearable device, a full authority digital engine (or electronics) control (FADEC), an avionics system, or another type of computing device.

The processor platform1100of the illustrated example includes processor circuitry1112. The processor circuitry1112of the illustrated example is hardware. For example, the processor circuitry1112can be implemented by one or more integrated circuits, logic circuits, FPGAs, microprocessors, CPUs, GPUs, DSPs, and/or microcontrollers from any desired family or manufacturer. The processor circuitry1112may be implemented by one or more semiconductor based (e.g., silicon based) devices. In this example, the processor circuitry1112implements the example interface circuitry802, the example rotational speed loop circuitry804, the example valve controller circuitry806, the example operating mode determination circuitry808, and/or, more generally, the example control system522.

The processor circuitry1112of the illustrated example includes a local memory1113(e.g., a cache, registers, etc.). The processor circuitry1112of the illustrated example is in communication with a main memory including a volatile memory1114and a non-volatile memory1116by a bus1118. The volatile memory1114may be implemented by Synchronous Dynamic Random Access Memory (SDRAM), Dynamic Random Access Memory (DRAM), RAMBUS® Dynamic Random Access Memory (RDRAM®), and/or any other type of RAM device. The non-volatile memory1116may be implemented by flash memory and/or any other desired type of memory device. Access to the main memory1114,1116of the illustrated example is controlled by a memory controller1117.

The processor platform1100of the illustrated example also includes interface circuitry1120. The interface circuitry1120may be implemented by hardware in accordance with any type of interface standard, such as an Ethernet interface, a universal serial bus (USB) interface, a Bluetooth® interface, a near field communication (NFC) interface, a Peripheral Component Interconnect (PCI) interface, and/or a Peripheral Component Interconnect Express (PCIe) interface.

In the illustrated example, one or more input devices1122are connected to the interface circuitry1120. The input device(s)1122permit(s) a user to enter data and/or commands into the processor circuitry1112. The input device(s)1122can be implemented by, for example, a keyboard, a button, a mouse, a touchscreen, a track-pad, a trackball, an isopoint device, and/or a control panel.

One or more output devices1124are also connected to the interface circuitry1120of the illustrated example. The output device(s)1124can be implemented, for example, by display devices (e.g., a light emitting diode (LED), an organic light emitting diode (OLED), a liquid crystal display (LCD), a cathode ray tube (CRT) display, an in-place switching (IPS) display, a touchscreen, etc.), a control panel, and/or speaker. The interface circuitry1120of the illustrated example, thus, typically includes a graphics driver card, a graphics driver chip, and/or graphics processor circuitry such as a GPU.

The interface circuitry1120of the illustrated example also includes a communication device such as a transmitter, a receiver, a transceiver, a modem, a residential gateway, a wireless access point, and/or a network interface to facilitate exchange of data with external machines (e.g., computing devices of any kind) by a network1126. The communication can be by, for example, an Ethernet connection, a digital subscriber line (DSL) connection, a telephone line connection, a coaxial cable system, a satellite system, a line-of-site wireless system, a cellular telephone system, an optical connection, etc.

The processor platform1100of the illustrated example also includes one or more mass storage devices1128to store software and/or data. Examples of such mass storage devices1128include magnetic storage devices, optical storage devices, floppy disk drives, HDDs, CDs, Blu-ray disk drives, redundant array of independent disks (RAID) systems, solid state storage devices such as flash memory devices and/or SSDs, and DVD drives.

The machine readable instructions1132, which may be implemented by the machine readable instructions ofFIGS.9and10, may be stored in the mass storage device1128, in the volatile memory1114, in the non-volatile memory1116, and/or on a removable non-transitory computer readable storage medium such as a CD or DVD.

Example heat driven thermal management systems (TMSs) are disclosed herein that include a turbomachine to power the flow of a heat exchange fluid (e.g., sCO2, liquid helium, helium-xenon, etc.) through a thermal transport bus. The turbomachine of example heat driven TMSs disclosed herein replaces a motor of a pump/compressor to reduce the weight and size of the TMS. For example, the mass and volume of the turbomachine is less than the combined mass and volume of a pump/motor housing, the cooling system(s) of the motor, the control system(s) of the motor, etc. In other words, example systems disclosed herein are assembled and/or packaged into smaller spaces by removing components and/or systems associated with electric sCO2 pumps.

Example heat driven TMSs disclosed herein utilize the turbomachine to operate more efficiently and eliminate electrical losses associated with motor driven pumps. Furthermore, since the turbomachine is a thrust balanced system, the turbomachine experiences fewer mechanical losses (e.g., vibration, friction, etc.) than the motorized pump. Turbomachines of example heat driven TMSs disclosed herein are also less complex than motorized pumps. For example, pumps designed to pressurize sCO2 in the TTB can be costly to design, manufacture, and maintain, especially when the pumps include supplementary systems (e.g., self-lubricating systems, dynamic axial loading systems, dynamic radial bearing systems, etc.) to optimize pump performance.

Example heat driven TMSs disclosed can include a motor and generator unit (M/G) coupled to a shaft between a turbine and a compressor of the turbomachine. The M/G can be of a smaller size than a typical sCO2 pump motor to maintain the reduced weight and size of the example heat driven TMSs. The M/G can operate as a motor to supplement the mechanical power the turbine transfers to the compressor or as a generator to draw electrical power from the turbine. Thus, example heat driven TMSs disclosed herein can use the M/G with the turbomachine to operate more efficiently than fully motorized and/or fully heat driven TMSs. Furthermore, example heat driven TMSs that include the M/G can power other onboard systems in addition to powering the flow of the heat exchange fluid.

Example methods, apparatus, systems, and articles of manufacture to power thermal management systems with heat of a working fluid therein are disclosed herein. Further examples and combinations thereof include the following:

Example 1 includes a thermal management system comprising a thermal transport bus loop fluidly coupled to at least one heat source exchanger and at least one heat sink exchanger, a turbomachine including a turbine and a compressor, the turbine and the compressor rotatably interlocked via a shaft, the compressor coupled to the thermal transport bus loop, the compressor to pressurize a heat exchange fluid in the thermal transport bus loop, the turbine including an inlet and an outlet, the inlet connected to a first point of the thermal transport bus loop via a first flowline, the outlet connected to a second point of the thermal transport bus loop via a second flowline, and a control valve coupled to the first flowline, the control valve to adjust a mass flowrate of the heat exchange fluid in the first flowline based on a speed of the shaft.

Example 2 includes the thermal management system of any preceding clause, wherein the at least one heat source exchanger includes a first heat source exchanger and a second heat source exchanger, and the at least one heat sink exchanger includes a first heat sink exchanger and a second heat sink exchanger, the first heat source exchanger positioned downstream of the compressor, the second heat source exchanger positioned downstream of the first heat source exchanger, the first heat sink exchanger positioned downstream of the second heat source exchanger, the second heat sink exchanger positioned downstream of the first heat sink exchanger.

Example 3 includes the thermal management system of any preceding clause, wherein the first point is positioned downstream of the second heat source exchanger and upstream of the first heat sink exchanger.

Example 4 includes the thermal management system of any preceding clause, wherein the second point is positioned downstream of the second heat sink exchanger and upstream of the compressor.

Example 5 includes the thermal management system of any preceding clause, wherein the first flowline includes a check valve upstream of the control valve and downstream of the first point.

Example 6 includes the thermal management system of any preceding clause, wherein the heat exchange fluid is supercritical carbon dioxide.

Example 7 includes the thermal management system of any preceding clause, wherein the turbine and the compressor are mounted on the shaft.

Example 8 includes the thermal management system of any preceding clause, wherein the turbine is an axial turbine, and the compressor is an axial compressor.

Example 9 includes the thermal management system of any preceding clause, wherein the shaft extends from a distal end of the turbine to a distal end of the compressor.

Example 10 includes the thermal management system of any preceding clause, wherein the turbine is a centrifugal turbine, and the compressor is a centrifugal compressor.

Example 11 includes the thermal management system of any preceding clause, further including a control system and a speed sensor, the speed sensor coupled to the turbomachine, the control system is to detect the speed of the shaft, determine whether the speed of the shaft satisfies a threshold, cause the control valve to increase an output flowrate when the speed of the shaft does not satisfy the threshold, and cause the control valve to decrease the output flowrate when the speed of the shaft satisfies the threshold.

Example 12 includes the thermal management system of any preceding clause, wherein the control system is to cause the control valve to fully open when the speed of the shaft does not satisfy the threshold, and cause the control valve to fully close when the speed of the shaft satisfies the threshold.

Example 13 includes the thermal management system of any preceding clause, wherein the speed sensor is a tachometer.

Example 14 includes the thermal management system of any preceding clause, wherein the thermal transport bus loop is a first thermal transport bus loop, the thermal management system further includes a second thermal transport bus loop, and the first and second thermal transport bus loops are configured to operate in parallel.

Example 15 includes the thermal management system of any preceding clause, wherein the turbomachine is a first turbomachine coupled to the first thermal transport bus loop, the thermal management system further includes a second turbomachine coupled to the second thermal transport bus loop.

Example 16 includes the thermal management system of any preceding clause, wherein the control valve is a pneumatic valve hydraulically actuated based on pressure of the heat exchange fluid in the thermal transport bus loop.

Example 17 includes a heat driven advanced Brayton cycle apparatus comprising a thermal transport bus to transmit a working fluid within the heat driven advanced Brayton cycle apparatus, a turbomachine including a turbine and a compressor mounted on a shaft, an inlet of the turbine fluidly coupled to the thermal transport bus via a flowline, the turbine to convert thermal energy of a portion of the working fluid to mechanical power, the shaft to transfer the mechanical power to the compressor, the compressor to convert the mechanical power into kinetic energy of the working fluid, and a control system to detect a speed of the shaft via a speed sensor, the speed sensor coupled to the turbomachine, determine whether the speed of the shaft satisfies a threshold, cause a control valve to reduce a mass flowrate in the flowline when the speed of the shaft satisfies the threshold, and cause the control valve to increase the mass flowrate in the flowline when the speed of the shaft does not satisfy the threshold.

Example 18 includes the heat driven advanced Brayton cycle apparatus of any preceding clause, wherein the thermal transport bus includes a heat source exchanger and a heat sink exchanger, the flowline coupled to the thermal transport bus at a point, the point positioned downstream of the heat source exchanger and upstream of the heat sink exchanger.

Example 19 includes the heat driven advanced Brayton cycle apparatus of any preceding clause, wherein the flowline is a first flowline, and the point is a first point, further including a second flowline fluidly coupled to an outlet of the turbine and a second point of the thermal transport bus, the second point positioned just upstream of the compressor.

Example 20 includes the heat driven advanced Brayton cycle apparatus of any preceding clause, wherein the control system is to cause the control valve to fully close when the speed of the shaft satisfies the threshold, and cause the control valve to fully open when the speed of the shaft does not satisfy the threshold.

Example 21 includes the heat driven advanced Brayton cycle apparatus of any preceding clause, further including a motor and generator unit coupled to the shaft.

Example 22 includes the heat driven advanced Brayton cycle apparatus of any preceding clause, wherein the threshold is a first threshold, and the control system is to cause the motor and generator unit to operate in a motor mode when the speed of the shaft does not satisfy a second threshold, and cause the motor and generator unit to operate in a generator mode when the speed of the shaft satisfies the second threshold.

Example 23 includes the heat driven advanced Brayton cycle apparatus of any preceding clause, wherein the control system is to cause the motor and generator unit to generate the mechanical power based on electrical power when the speed of the shaft does not satisfy the second threshold, the electrical power obtained from a power source, and cause the motor and generator unit to generate the electrical power based on the mechanical power when the speed of the shaft satisfies the second threshold, the electrical power transmitted to a power sink.

Example 24 includes the heat driven advanced Brayton cycle apparatus of any preceding clause, wherein the turbine extracts an excessive amount of power when the speed of the shaft satisfies the second threshold, the excessive amount of power to be converted to the electrical power.

Example 25 includes a method comprising detecting a shaft speed based on a measurement obtained from a speed sensor, the shaft speed corresponding to a rotational speed of a turbomachine, the turbomachine including a turbine coupled to a compressor via a shaft, the compressor integrated into a first flowline, the turbine integrated into a second flowline, determining whether the shaft speed satisfies a threshold, opening a control valve when the shaft speed does not satisfy the threshold, the control valve integrated into the second flowline, and closing the control valve when the shaft speed satisfies the threshold.

Example 26 includes the method of any preceding clause, wherein the opening of the control valve includes fully opening the control valve, and the closing of the control valve includes fully closing the control valve.

Example 27 includes the method of any preceding clause, wherein the opening of the control valve includes partially opening the control valve to a first area, and the closing of the control valve includes partially closing the control valve to a second area, the first and second areas based on a predetermined flowrate in the second flowline.

Example 28 includes the method of any preceding clause, further including determining an operating mode of a motor and generator unit coupled to the turbomachine.

Example 29 includes the method of any preceding clause, wherein the threshold is a first threshold, and the determining of the operating mode includes determining whether the shaft speed satisfies a second threshold, causing the motor and generator unit to operate as a motor when the shaft speed does not satisfy the second threshold, and causing the motor and generator unit to operate as a generator when the shaft speed satisfies the second threshold.

Example 30 includes a thermal management system comprising a thermal transport bus to transmit a working fluid between at least one heat source exchanger and at least one heat sink exchanger, the thermal transport bus including a flowline branching from the thermal transport bus at a first point, the flowline reconnecting to the thermal transport bus at a second point, a turbomachine including a turbine coupled to a compressor via a shaft, the turbine fluidly coupled to the flowline, the turbine to convert thermal energy of the working fluid to mechanical energy of the shaft, the compressor fluidly coupled to the thermal transport bus, the compressor to convert the mechanical energy of the shaft to kinetic energy of the working fluid, the turbomachine including a motor and generator unit mounted on the shaft, and a control system configured to detect a speed of the shaft via a speed sensor, determine whether the speed of the shaft satisfies a threshold, operate the motor and generator unit as a motor when the speed of the shaft does not satisfy the threshold, and operate the motor and generator unit as a generator when the speed of the shaft satisfies the threshold.

Example 31 includes the thermal management system of any preceding clause, wherein the at least one heat source exchanger includes a first heat source exchanger and a second heat source exchanger, and the at least one heat sink exchanger includes a first heat sink exchanger and a second heat sink exchanger, the first heat source exchanger positioned downstream of the compressor, the second heat source exchanger positioned downstream of the first heat source exchanger, the first heat sink exchanger positioned downstream of the second heat source exchanger, the second heat sink exchanger positioned downstream of the first heat sink exchanger.

Example 32 includes the thermal management system of any preceding clause, wherein the first point is positioned downstream of the second heat source exchanger and upstream of the first heat sink exchanger.

Example 33 includes the thermal management system of any preceding clause, wherein the second point is positioned downstream of the second heat sink exchanger and upstream of the compressor.

Example 34 includes the thermal management system of any preceding clause, wherein the flowline includes a check valve downstream of the first point.

Example 35 includes the thermal management system of any preceding clause, wherein the working fluid is supercritical carbon dioxide.

Example 36 includes the thermal management system of any preceding clause, wherein the turbine and the compressor are mounted on the shaft.

Example 37 includes the thermal management system of any preceding clause, wherein the turbine is an axial turbine, and the compressor is an axial compressor.

Example 38 includes the thermal management system of any preceding clause, wherein the shaft extends from a distal end of the turbine to a distal end of the compressor.

Example 39 includes the thermal management system of any preceding clause, wherein the turbine is a centrifugal turbine, and the compressor is a centrifugal compressor.

Example 40 includes the thermal management system of any preceding clause, wherein the threshold is a first threshold, further including a control valve coupled to the flowline and positioned upstream of the turbine, the control system to detect the speed of the shaft, determine whether the speed of the shaft satisfies a second threshold, open the control valve when the speed of the shaft does not satisfy the second threshold, and close the control valve when the speed of the shaft satisfies the second threshold.

Example 41 includes the thermal management system of any preceding clause, wherein the control valve is a pneumatic valve, the control valve hydraulically actuated based on pressure of the working fluid in the thermal transport bus.

Example 42 includes the thermal management system of any preceding clause, wherein the speed sensor is a tachometer.

Example 43 includes the thermal management system of any preceding clause, wherein the thermal transport bus is a first thermal transport bus, further including a second thermal transport bus, the first and second thermal transport buses configured to operate in parallel.

Example 44 includes the thermal management system of any preceding clause, wherein the turbomachine is a first turbomachine coupled to the first thermal transport bus, further including a second turbomachine coupled to the second thermal transport bus.

The following claims are hereby incorporated into this Detailed Description by this reference. Although certain example systems, methods, apparatus, and articles of manufacture have been disclosed herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all systems, methods, apparatus, and articles of manufacture fairly falling within the scope of the claims of this patent.