An aircraft powerplant waste heat recovery system and control method

Abstract

This application provides a waste heat recovery system and control method for an aircraft power plant, relating to the field of aircraft technology. The waste heat recovery system comprises a generator module, a control module, and a battery module. The hot end of the generator module is configured to receive waste heat from the exhaust gas of the aircraft engine. The control module is electrically connected to the generator module and is used to acquire the operating parameters of the generator module. The battery module is electrically connected to the control module. The control module is configured to control the charging and discharging state of the battery module based on the operating parameters. This system can efficiently recover waste heat from the aircraft engine exhaust gas, improving the overall energy utilization rate.

Description

Technical Field

[0001] This application relates to the field of aircraft technology, and in particular to an aircraft power plant waste heat recovery system and control method. Background Technology

[0002] In flight propulsion systems, engines include internal combustion engines and gas turbines. During operation, they generate a large amount of waste heat, mainly in the form of exhaust and cylinder cooling. This waste heat is usually directly discharged into the external environment.

[0003] Because the overall thermal efficiency of the engine is relatively low, most of the fuel's energy is wasted due to ineffective conversion, resulting in significant energy loss. The Stirling cycle, as a closed-loop external combustion cycle technology, possesses characteristics such as high operating efficiency, low noise levels, minimal environmental pollution, and strong adaptability to heat source quality. It achieves the conversion of thermal energy into mechanical energy through the periodic expansion and compression of the gaseous working fluid, thus exhibiting unique advantages in waste heat recovery applications.

[0004] Current fuel-powered aircraft power generation systems generally rely on the engine directly driving the generator. This method continuously consumes the engine's shaft power output, reducing the available energy of the propulsion system and negatively impacting the aircraft's endurance and range. The rigid mechanical connection between the generator and the engine causes the power generation frequency to fluctuate with engine speed, making it difficult to maintain stable power quality throughout the flight envelope. Complex dynamic control circuits are required for compensation, which not only increases the complexity of the system hardware but also raises maintenance costs and the risk of failure. Summary of the Invention

[0005] This application provides a waste heat recovery system and control method for an aircraft power plant, in order to at least solve the above-mentioned technical problems.

[0006] The first aspect of this application provides a waste heat recovery system for an aircraft power unit, comprising: a generator module, a control module, and a battery module, wherein the hot end of the generator module is configured to receive waste heat from exhaust gas from the aircraft engine; the control module is electrically connected to the generator module and is used to acquire the operating parameters of the generator module; the battery module is electrically connected to the control module; wherein the control module is configured to control the charging and discharging state of the battery module based on the operating parameters.

[0007] In one embodiment, the generator module includes: an engine exhaust port connected to an aircraft engine; a waste heat recovery outer cavity connected to the engine exhaust port; an exhaust pipe connected to the waste heat recovery outer cavity; an inner cavity at least partially disposed within the waste heat recovery outer cavity; a transmission component sealing cavity connected to the inner cavity; a target generator connected to the transmission component sealing cavity; a linkage transmission mechanism connected to the target generator; and a dual-piston mechanism connected to the linkage transmission mechanism.

[0008] In one embodiment, the engine exhaust port is provided with a honeycomb ceramic filter.

[0009] In one embodiment, the waste heat recovery outer cavity includes: an outer cavity shell, a heat insulation cavity, and a high-radiation heat exchange mechanism; the heat insulation cavity is disposed on the side of the outer cavity shell near the engine exhaust port; the high-radiation heat exchange mechanism is disposed inside the outer cavity shell, and the high-radiation heat exchange mechanism is an arc-shaped structure facing the inner cavity; a high-reflectivity coating is applied to the inner wall surface of the outer cavity shell.

[0010] In one embodiment, the inner cavity includes: a hot-end heat exchange structure, a cold-end heat exchange structure, and a high-absorption coating. The hot-end heat exchange structure is located inside the waste heat recovery outer cavity; the cold-end heat exchange structure is connected to the hot-end heat exchange structure; and the high-absorption coating is applied to the surface of the hot-end heat exchange structure.

[0011] In one embodiment, the dual-piston mechanism includes: an expansion piston and a sealing piston, the sealing piston being connected to the expansion piston; the expansion piston being correspondingly arranged with the hot-end heat exchange structure; and the sealing piston being correspondingly arranged with the cold-end heat exchange structure.

[0012] In one embodiment, one end of the linkage drive mechanism is connected to the double piston mechanism, and the other end of the linkage drive mechanism is connected to the target generator. The target generator includes: a generator output shaft, a hollow cup rotor, and a double-winding stator. The generator output shaft is connected to the linkage drive mechanism; the hollow cup rotor is connected to the generator output shaft, and the double-winding stator is correspondingly arranged with respect to the hollow cup rotor.

[0013] In one possible implementation, the operating parameters include the generator module's rotational speed and / or hot-end temperature; The control module is specifically configured to: control the battery module to enter the charging state when the speed of the generator module is higher than the first preset threshold; and control the battery module to enter the discharging state or stop charging when the speed of the generator module is lower than the second preset threshold.

[0014] A second aspect of this application provides a method for controlling waste heat recovery from an aircraft power plant, comprising: Obtain the operating parameters of the generator module, including speed and / or hot end temperature; Determine the relationship between the operating parameters and the preset threshold; Based on the judgment result, charge and discharge control commands are generated: when the rotation speed is higher than the first preset threshold, a charging command is generated; when the rotation speed is lower than the second preset threshold, a discharging or stop charging command is generated. Execute charge and discharge control commands to control the charge and discharge status of the battery module.

[0015] In one possible implementation, it also includes a waste heat recovery physical process: The engine exhaust is filtered through a honeycomb ceramic filter and then introduced into the waste heat recovery outer cavity; Heat is radiated directionally to the inner cavity through a high-reflectivity coating and a high-radiation heat exchange mechanism; The high-absorption coating absorbs heat, causing the heat transfer medium to expand and drive the movement of the dual-piston mechanism. The target generator is driven to generate electricity through a linkage transmission mechanism.

[0016] As can be seen from the above, the waste heat recovery system and waste heat recovery control method of the aircraft power plant provided in this application drive the generator to generate electricity by recovering the waste heat of the engine exhaust, and intelligently control the charging and discharging state of the battery based on the operating parameters. This solves the problems of waste heat waste and energy loss caused by reliance on engine drive. It has the advantages of efficient recovery of waste heat of aircraft engine exhaust, improved energy utilization efficiency, reduced dependence on engine shaft power, and helps to extend the endurance of the aircraft and stabilize the power supply.

[0017] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0018] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings. Several embodiments of this application are illustrated in the drawings by way of example and not limitation, in which: In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0019] Figure 1 A schematic diagram of the waste heat recovery system of the aircraft power plant provided for this application; Figure 2 This is a schematic diagram of the main structure of the generator module provided in this application; Figure 3 A schematic diagram of the left-side structure of the generator module provided in this application; Figure 4 This is a cross-sectional structural diagram of the generator module provided in this application; Figure 5A partial structural diagram of the internal cavity of the generator module provided in this application. Figure 1 ; Figure 6 A partial structural diagram of the internal cavity of the generator module provided in this application. Figure 2 ; Figure 7 A partial structural diagram of the linkage transmission mechanism provided in this application. Figure 1 ; Figure 8 A partial structural diagram of the linkage transmission mechanism provided in this application. Figure 2 ; Figure 9 A partial cross-sectional view of the generator module provided in this application; Figure 10 The process of the waste heat recovery control method provided in this application Figure 1 ; Figure 11 The process of the waste heat recovery control method provided in this application Figure 2 .

[0020] Reference numerals: 1. Generator module; 2. Control module; 3. Battery module; 11. Engine exhaust port; 12. Honeycomb ceramic filter; 13. Waste heat recovery outer cavity; 14. Exhaust pipe; 15. Inner cavity; 16. Transmission component sealing cavity; 17. Target generator; 18. Dual-piston mechanism; 19. Linkage transmission mechanism; 131. Outer cavity shell; 132. Insulated cavity; 133. High-radiation heat exchange mechanism; 134. High-reflectivity coating; 151. Cold end heat exchange structure; 152. Hot end heat exchange structure; 153. High-absorption coating; 171. Generator output shaft; 172. Hollow cup rotor; 173. Dual-winding stator; 181. Expansion piston; 182. Sealed piston. Detailed Implementation

[0021] To make the objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] like Figures 1-9As shown in the figure, this application provides a waste heat recovery system for an aircraft power unit, including: a generator module 1, a control module 2, and a battery module 3. The hot end of the generator module 1 is configured to receive waste heat from the exhaust of the aircraft engine. The control module 2 is electrically connected to the generator module 1 and is used to acquire the operating parameters of the generator module 1. The battery module 3 is electrically connected to the control module 2. The control module 2 is configured to control the charging and discharging state of the battery module 3 based on the operating parameters.

[0023] The waste heat recovery system for aircraft propulsion is an integrated device whose main function is to capture and convert the waste heat energy generated by the aircraft propulsion system during operation into usable electrical energy, thereby improving overall energy efficiency. Generator module 1 is the core energy conversion unit in this system, responsible for converting the received heat energy into electrical energy. It typically includes a heat receiving component, an energy conversion mechanism, and an electrical output component. Control module 2, as the intelligent hub of the system, is responsible for monitoring, analyzing, and coordinating the operating status of various components within the system. It receives signals from generator module 1 and issues commands to other modules according to preset logic or real-time needs. Battery module 3 is the energy storage unit in the system, used to store the electrical energy generated by generator module 1 and supply power to external loads when needed. It can charge or discharge according to the commands of control module 2. The hot end is the part of generator module 1 that directly contacts the high-temperature heat source and is the initial interface for heat energy to enter the system. Operating parameters are various real-time data generated by generator module 1 during operation, such as temperature, voltage, and current, which reflect the current operating status of the module. The charging / discharging state is the current energy management mode of the battery module 3, including receiving electrical energy for charging, discharging electrical energy for discharging, or being in standby mode.

[0024] like Figure 1 As shown, the hot end of generator module 1 is configured to receive waste heat from the aircraft engine's exhaust. This means that generator module 1 is designed to be thermally coupled to the engine's exhaust path, thereby capturing thermal energy from the high-temperature exhaust gas. For example, the hot end of generator module 1 could be a simple heat exchanger with internal channels connected to the engine exhaust pipe 14, absorbing heat from the exhaust gas through conduction or convection. Alternatively, the hot end could be a radiative receiving surface, directly exposed to the high-temperature exhaust flow, acquiring thermal energy through radiative heat exchange. These configurations enable generator module 1 to use waste heat energy as its operating input, avoiding direct consumption of engine main shaft power.

[0025] The aircraft engine is a closed Stirling engine. By adopting a closed Stirling engine and optimizing the crank-connecting rod mechanism design, mechanical losses during transmission are significantly reduced. The entire process of waste heat collection and energy conversion is optimized, and helium, which has high thermal conductivity, is selected as the working fluid to effectively reduce energy waste. Control module 2 is electrically connected to generator module 1 to acquire its operating parameters. This electrical connection can be via a wire, allowing control module 2 to receive electrical signals from generator module 1 in real time. Operating parameters may include the generator module 1's output voltage, current, or the temperature of its internal key components. By acquiring these parameters, control module 2 can monitor the generator module 1's operating status and energy output in real time. For example, control module 2 may be equipped with a sensor interface to connect to internal temperature or voltage sensors in generator module 1, thereby acquiring relevant operating data.

[0026] The battery module 3 is electrically connected to the control module 2. This electrical connection allows the battery module 3 to receive electrical energy from the generator module 1 for charging, or to discharge to an external load via the control module 2 when needed. For example, the battery module 3 can be a battery pack composed of multiple battery cells connected in series and parallel, connected to the control module 2 via power cables to achieve bidirectional power transmission.

[0027] The control module 2 is configured to control the charging and discharging state of the battery module 3 based on operating parameters. This means that the control module 2 intelligently determines whether the battery module 3 should charge, discharge, or remain in standby mode based on real-time operating data obtained from the generator module 1. For example, when the generator module 1 has sufficient power output and the battery is not fully charged, the control module 2 can issue a charging command; when the system requires additional power or the generator module 1's power output is insufficient, the control module 2 can issue a discharging command. This dynamic control based on operating parameters ensures that the system can optimize energy storage and release according to actual needs, improving the flexibility and efficiency of energy utilization.

[0028] Generator module 1, control module 2, and battery module 3 work closely together to form a highly efficient and intelligent closed-loop system for waste heat recovery and power management. Generator module 1 is responsible for converting waste heat into electrical energy, control module 2 acts as the decision-making center, coordinating energy flow based on real-time data, and battery module 3 provides energy buffering and on-demand power supply capabilities. The entire system works collaboratively to achieve effective recovery and utilization of exhaust heat from the aircraft engine, avoids consuming engine spindle power, and ensures dynamic adaptability of power supply.

[0029] The generator module 1 includes: an engine exhaust port 11 connected to the aircraft engine; a waste heat recovery outer cavity 13 connected to the engine exhaust port 11; an exhaust pipe 14 connected to the waste heat recovery outer cavity 13; an inner cavity 15 at least partially disposed within the waste heat recovery outer cavity 13; a transmission component sealing cavity 16 connected to the inner cavity 15; a target generator 17 connected to the transmission component sealing cavity 16; a linkage transmission mechanism 19 connected to the target generator 17; and a dual piston mechanism 18 connected to the linkage transmission mechanism 19.

[0030] like Figure 2 , Figure 3 and Figure 4 As shown, the engine exhaust port 11 is a key component for introducing the waste heat generated by the aircraft engine into the waste heat recovery system. This port can be designed as a flange port that connects directly to the engine exhaust manifold or exhaust pipe 14, ensuring that high-temperature exhaust gas can be reliably introduced into the system. Alternatively, it can be a bypass port integrated into the engine exhaust system, using control valves to regulate the amount of waste heat introduced to adapt to different operating conditions.

[0031] The waste heat recovery outer cavity 13, as the core structure of waste heat recovery, primarily functions to contain and guide engine exhaust and facilitate heat transfer to the inner cavity 15. This outer cavity can be a metal shell with a specific shape and size, such as a cylindrical or irregularly shaped cavity, and its interior can be designed with flow-guiding structures to optimize airflow distribution. Alternatively, it can employ a multi-layered structure made of high-temperature resistant alloy materials to enhance its thermal stability and heat exchange efficiency.

[0032] The function of the exhaust pipe 14 is to discharge the exhaust gas after it has passed through the waste heat recovery outer cavity 13 into the system, thereby maintaining airflow circulation and pressure balance within the cavity. This exhaust pipe 14 can be connected to a standard exhaust pipe 14 at the outlet of the waste heat recovery outer cavity 13, directly leading to the external environment. Alternatively, it can also be an exhaust pipe 14 integrated with a silencer or purification device to meet specific environmental protection or noise control requirements.

[0033] The inner cavity 15 is a core component of the Stirling engine, used to contain the working medium and to heat and cool it through heat exchange with the waste heat recovery outer cavity 13. This inner cavity 15 can be made of thin-walled metal and filled with a highly thermally conductive working medium such as helium. Alternatively, it can be a cavity with a complex internal flow channel design to optimize the heat transfer and flow characteristics of the working medium, thereby improving the thermodynamic cycle efficiency.

[0034] The transmission component sealing cavity 16 isolates the working medium within the inner cavity 15 from the external environment, protecting the transmission component from the effects of high-temperature or corrosive media and ensuring the sealing of the working medium. This sealing cavity can be made of a high-temperature resistant sealing material to effectively separate the inner cavity 15 from the transmission component. Alternatively, it can employ non-contact sealing technologies such as magnetohydrodynamic sealing or bellows sealing to reduce friction loss and improve system reliability.

[0035] The target generator 17 is a device that converts the mechanical energy generated by the double-piston mechanism 18 into electrical energy. This generator can be a permanent magnet synchronous generator, characterized by its compact structure, high efficiency, and suitability for aerospace environments. Alternatively, an induction generator or a DC generator can be selected depending on the system's requirements for power quality and control complexity.

[0036] The function of the connecting rod transmission mechanism 19 is to convert the reciprocating linear motion of the double-piston mechanism 18 into the rotational motion of the target generator 17. This mechanism can be a traditional crank-connecting rod mechanism, where the rotation of the crankshaft drives the reciprocating motion of the connecting rod and piston. Alternatively, it can be a swashplate mechanism or a swing-arm mechanism to adapt to different spatial layouts and motion characteristics, achieving efficient mechanical energy conversion.

[0037] The dual-piston mechanism 18 is the core actuator of the Stirling engine. It drives the piston to reciprocate through the expansion and compression of the working medium, thereby generating mechanical work. This mechanism can adopt the piston configuration of an Alpha-type Stirling engine, where the expansion piston 181 and the compression piston are located in different cylinders. Alternatively, it can also adopt the piston configuration of a Beta-type or Gamma-type Stirling engine, where the expansion piston 181 and the compression piston are located in the same cylinder and connected by a regenerator.

[0038] The solution of this application achieves efficient recovery and utilization of waste heat from the aircraft engine through the aforementioned structure. Specifically, the engine exhaust port 11 is connected to the aircraft engine, ensuring that the high-temperature exhaust waste heat can be reliably introduced into the system. The waste heat recovery outer cavity 13 is connected to the engine exhaust port 11, forming a closed heat source containment space, effectively collecting and guiding the high-temperature exhaust. At the same time, the exhaust pipe 14 is connected to the waste heat recovery outer cavity 13, ensuring that the exhaust gas can be smoothly discharged after heat transfer, maintaining the airflow circulation and pressure balance inside the system. The inner cavity 15 is at least partially disposed within the waste heat recovery outer cavity 13. This nested structure optimizes the heat transfer efficiency from the outer cavity to the inner cavity 15, allowing the working medium inside the inner cavity 15 to efficiently absorb heat and expand, thereby driving the movement of the dual-piston mechanism 18. The reciprocating linear motion of the dual-piston mechanism 18 is converted into rotational motion through the linkage transmission mechanism 19, which in turn drives the target generator 17 to convert mechanical energy into electrical energy. The transmission component sealing cavity 16 is connected to the inner cavity 15, effectively isolating the high-temperature working medium from the transmission component, protecting the transmission mechanism, and ensuring the sealing of the working medium in the inner cavity 15, maintaining the efficiency of the Stirling cycle. This ingenious structural design allows the entire generator module 1 to operate independently of the main shaft power of the aircraft engine, generating electricity only using exhaust waste heat, thereby avoiding the impact on engine propulsion performance and simplifying the dynamic adaptability requirements of the power generation system.

[0039] Waste heat collection is thorough and efficient, with a net increase in absorption rate of approximately 5% to 13%. Addressing the characteristic that engine exhaust is primarily concentrated in the 4-8μm mid-infrared core band, this application considers a dual-cavity structure. The outer cavity's inner wall employs a high-radiation-angle-factor arc design, significantly improving directional radiation capability. The outer cavity is coated with a metal-based high-reflectivity (90%-99% reflectivity) material, drastically reducing heat loss to the outside and radiating the majority of heat to the heating end of the inner cavity 15. The inner cavity 15 utilizes a dedicated structure combining an exhaust heat exchange shroud and finned heat exchange components. This increases the heat exchange area and improves the efficiency of convective heat transfer. Furthermore, the inner cavity 15, coated with a high-absorption-rate high-temperature blackbody coating (absorption rate between 95% and 98%) or other high-absorption-rate coatings 153, can fully collect the exhaust heat released by the engine. A filter structure is installed to prevent dust and scale buildup on the heat exchange components, thus slowing down the decline in heat exchange efficiency and absorption rate. High stability and high reliability are achieved because there is no complex mechanical transmission mechanism with the engine. This reduces disturbances caused by changes in engine speed while maintaining a constant electrical load, thereby simplifying the rectifier circuit design and improving the system's stability and reliability.

[0040] like Figure 2As shown, the engine exhaust port 11 is equipped with a honeycomb ceramic filter 12. The honeycomb ceramic filter 12 is a ceramic filter element with a porous honeycomb structure, whose main function is to capture solid particles in the fluid. This filter is typically made of high-temperature and corrosion-resistant ceramic materials, such as cordierite, silicon carbide, or alumina. Its internal honeycomb channel design increases the filtration area and allows particles to be trapped on the channel walls or in the pores as gas passes through. As a specific implementation, the honeycomb ceramic filter 12 can adopt a wall-flow structure, where gas enters through one channel, is filtered through the porous walls, and flows out through adjacent channels, thus effectively intercepting particles. Another implementation is a straight-through structure, where gas passes directly through the honeycomb channels, and particles are captured through mechanisms such as inertial collision and diffusion.

[0041] The system includes: an engine exhaust port 11 for connecting engine exhaust to the power generation system; a honeycomb ceramic filter 12 for adsorbing particulate matter and impurities in the engine exhaust to prevent them from entering the heat exchange chamber and affecting its heat exchange efficiency; a waste heat recovery outer chamber 13 for collecting engine exhaust; an exhaust pipe 14 for discharging engine exhaust gas after waste heat recovery; a Stirling cycle hot end inner chamber 15 for absorbing waste heat from the exhaust gas, and filled with helium gas with high thermal conductivity to further improve the efficiency of waste heat recovery; a transmission component sealing chamber 16 for isolating the transmission component from the external environment to prevent impurities and foreign objects from entering the transmission component and causing wear or jamming, thus improving the reliability and lifespan of the transmission component; a hollow cup dual-winding brushless generator for converting kinetic energy into electrical energy, thus converting waste heat from the exhaust gas into usable onboard energy; a dual-piston mechanism 18, a key component for converting thermal energy into kinetic energy; and a connecting rod transmission mechanism 19 for converting the linear motion of the piston into rotational motion, thereby driving the generator to rotate.

[0042] The proposed solution involves installing a honeycomb ceramic filter 12 at the engine exhaust port 11, ensuring that the exhaust gas generated by the aircraft engine is filtered before entering the waste heat recovery system. This filter effectively intercepts solid particles and impurities in the exhaust gas, ensuring that the gas entering the waste heat recovery outer cavity 13 is clean. This pretreatment mechanism prevents impurities from depositing, clogging, or wearing in key components such as the waste heat recovery outer cavity 13, inner cavity 15, and subsequent transmission component sealing cavity 16 and dual-piston mechanism 18, thus guaranteeing the stable operation and efficient heat exchange of the entire generator module 1. By placing the filtration function at the entrance of the waste heat recovery process, this solution addresses the potential negative impact of exhaust impurities on system performance and lifespan from the source, enabling the waste heat recovery system to operate more reliably and for longer, thereby improving the overall efficiency and reliability of the aircraft power plant waste heat recovery system.

[0043] The waste heat recovery outer cavity 13 includes: an outer cavity shell 131, a heat insulation cavity 132, and a high radiation heat exchange mechanism 133; the heat insulation cavity 132 is located on the side of the outer cavity shell 131 near the engine exhaust port 11; the high radiation heat exchange mechanism 133 is located inside the outer cavity shell 131, and the high radiation heat exchange mechanism 133 has an arc-shaped structure facing the inner cavity 15; a high reflectivity coating 134 is coated on the inner wall surface of the outer cavity shell 131.

[0044] Specifically, the outer shell 131 serves as the main structural support and external boundary of the waste heat recovery outer shell 13, accommodating internal components and isolating it from the external environment. The outer shell 131 can be made of high-temperature resistant, high-strength metallic materials, such as stainless steel or nickel-based alloys, to withstand the high temperatures and corrosion from engine exhaust, or it can be made of ceramic matrix composites to further improve heat resistance and reduce weight. The heat-insulating cavity 132 refers to one or more hollow areas formed inside the outer shell 131. Its main function is to utilize air or inert gas as an insulating medium to reduce heat loss through conduction and convection to the external environment. This heat-insulating cavity 132 can be achieved by setting a double-wall structure inside the outer shell 131 and creating a vacuum or filling the space between the two walls with a low thermal conductivity gas (such as argon), or by fixing porous insulating materials (such as ceramic fiber felt or aerogel board) to the inner wall of the outer shell 131 to form a cavity structure with insulating effects. The high-radiation heat exchange mechanism 133 is a structure that can efficiently absorb and radiate heat. Its main function is to efficiently transfer the exhaust waste heat of the engine to the inner cavity 15 in the form of radiation.

[0045] The mechanism can be made of materials with high emissivity and high absorptivity, such as specially treated silicon carbide ceramics or metal plates coated with high emissivity coatings. Alternatively, it can be designed as a finned, corrugated, or porous structure with a large surface area to increase the radiative heat transfer area and efficiency. The arc-shaped structure facing the inner cavity 15 is a specific geometry of the high-radiative heat transfer mechanism 133. Its surface is arc-shaped and faces the inner cavity 15, aiming to concentrate and directionally project radiative heat onto the inner cavity 15, improving the efficiency and uniformity of heat transfer. This arc-shaped structure can be part of a parabola or ellipsoid to achieve a focusing effect on thermal radiation, or it can be multiple interconnected curved surface units that together form an arc-shaped envelope surface roughly facing the inner cavity 15. The high-reflectivity coating 134 is a surface coating material with high infrared reflectivity. Its main function is to reflect heat, reduce heat absorption on the inner wall of the outer cavity shell 131 and heat loss to the outside, thereby guiding heat more effectively to the inner cavity 15. The coating can be a metal-based coating, such as a thin film coating of aluminum, silver, or gold, which has excellent reflectivity in the infrared band. Alternatively, it can be a ceramic-based or composite material coating, such as alumina, zirconium oxide, or a multilayer dielectric film, with improved reflectivity achieved by optimizing its microstructure. Coating the inner wall surface of the outer cavity shell 131 refers to the application of the high-reflectivity coating 134 to the surface of the outer cavity shell 131 that contacts the internal space of the waste heat recovery outer cavity 13. This coating can be uniformly adhered to the inner wall of the shell using processes such as spraying, electroplating, physical vapor deposition (PVD), or chemical vapor deposition (CVD). Alternatively, it can be installed on the inner wall of the shell using prefabricated high-reflectivity sheets or foils, mechanically fixed or adhesively bonded.

[0046] The waste heat recovery system for the aircraft power plant of this application has a generator module 1 whose hot end can receive waste heat from the exhaust of the aircraft engine and control the charging and discharging state of the battery module 3 through the control module 2. In the generator module 1, the waste heat recovery outer cavity 13 is connected to the engine exhaust port 11, and the inner cavity 15 is at least partially disposed within the waste heat recovery outer cavity 13.

[0047] To further optimize the heat transfer efficiency of the waste heat recovery outer cavity 13 and reduce heat loss, this application makes structural improvements to the waste heat recovery outer cavity 13. Specifically, the waste heat recovery outer cavity 13 consists of an outer cavity shell 131, a heat-insulating cavity 132, and a high-radiation heat exchange mechanism 133. The outer cavity shell 131 serves as the external boundary and structural support of the entire waste heat recovery outer cavity 13, ensuring the stability and integrity of the internal heat treatment environment. The heat-insulating cavity 132 is cleverly positioned on the side of the outer cavity shell 131 near the engine exhaust port 11. When high-temperature exhaust gas from the aircraft engine enters the waste heat recovery outer cavity 13 through the engine exhaust port 11, the heat-insulating cavity 132 effectively blocks the conduction and convection loss of heat to the external environment of the outer cavity shell 131. This design ensures that the heat entering the waste heat recovery outer cavity 13 can be retained within the system to the maximum extent, providing a sufficient heat source for the subsequent heat recovery process. Based on this, a high-radiation heat exchange mechanism 133 is disposed inside the outer cavity shell 131 and designed as an arc-shaped structure facing the inner cavity 15. This arc-shaped structure can efficiently and directionally transfer the heat absorbed from the engine exhaust to the inner cavity 15 in the form of radiation. The arc-shaped design allows the heat radiation to be focused or uniformly projected onto the surface of the inner cavity 15, significantly enhancing the efficiency of heat transfer from the outer cavity to the inner cavity 15. Simultaneously, a high-reflectivity coating 134 is applied to the inner wall surface of the outer cavity shell 131. This coating can reflect any heat radiation attempting to dissipate towards the inner wall of the outer cavity shell 131 back into the waste heat recovery outer cavity 13, further reducing heat absorption loss at the cavity wall surface and redirecting it back to the inner cavity 15.

[0048] The outer shell of the waste heat recovery cavity 13 is used to collect and centrally utilize engine exhaust gas; the heat insulation cavity 132 is used to reduce the heat exchange of engine exhaust gas with the external environment and reduce heat loss; the high radiation heat exchange mechanism 133 is an arc-shaped mechanism design to improve the angular coefficient of radiation heat exchange, so that it radiates directionally to the Stirling cycle hot end inner cavity 15, thereby improving the utilization rate of waste heat from exhaust gas; the high reflectivity coating 134 is a metal-based coating used to improve the reflectivity of the wall surface, reduce the absorption of heat, further reduce heat loss, and further improve the utilization rate of waste heat from exhaust gas.

[0049] Through the above structural combination—the outer shell 131 providing a stable environment, the heat-insulating cavity 132 reducing external heat loss, the high-radiation heat exchange mechanism 133 radiating heat efficiently and directionally with its arc-shaped structure, and the high-reflectivity coating 134 reflecting heat—a highly efficient and low-loss waste heat recovery heat transfer path is formed. This ingenious structural design allows the exhaust waste heat from the engine to be more concentrated and effectively guided to the inner cavity 15, thereby providing sufficient thermal energy for the heat transfer medium within the inner cavity 15 to drive the movement of the dual-piston mechanism 18, ultimately achieving power generation by the target generator 17. Compared to relying solely on a simple cavity structure for heat transfer, this solution significantly improves the efficiency of waste heat recovery and reduces heat waste through multiple thermal management methods, thereby improving the energy utilization rate of the entire aircraft power plant waste heat recovery system. The heat-insulating cavity 132 can be a vacuum layer formed between the double-layer stainless steel shell, or it can be filled with an inert gas with low thermal conductivity, such as argon.

[0050] The heat-insulating cavity 132 is located on the side of the outer shell 131 near the engine exhaust port 11 to maximize the prevention of heat loss from the high-temperature exhaust. The high-radiative heat exchange mechanism 133 can be made of silicon carbide ceramic material, with its surface roughened to increase emissivity and machined into a concave parabolic shape, the focal point or focal area of ​​which faces the inner cavity 15. This arcuate structure ensures that thermal radiation can be efficiently focused and projected onto the surface of the inner cavity 15. In addition, the inner wall surface of the outer shell 131 can be coated with a high-reflectivity coating 134 composed of multiple dielectric films, such as sequentially depositing aluminum oxide and silver films on a stainless steel substrate to achieve a reflectivity of over 90% in the infrared band. This coating is uniformly applied to the inner wall surface of the outer shell 131 using a physical vapor deposition (PVD) process to ensure that heat can be effectively reflected back towards the inner cavity 15, further reducing heat loss.

[0051] The thermal insulation cavity 132 significantly reduces heat loss to the external environment, ensuring effective heat accumulation. The arc-shaped structure of the high-radiation heat exchange mechanism 133, combined with the application of the high-reflectivity coating 134, enables directional and efficient heat transfer to the inner cavity 15. This synergistic effect of multiple thermal management mechanisms allows for more complete capture and utilization of engine exhaust waste heat, significantly improving the overall thermal efficiency of the waste heat recovery system. Therefore, this solution can more effectively convert aircraft engine exhaust waste heat into electrical energy, thereby improving fuel energy conversion efficiency, reducing the power consumption of the engine main shaft, and ultimately optimizing the aircraft's flight time and range.

[0052] like Figure 5 , Figure 6As shown, the inner cavity 15 includes: a hot-end heat exchange structure 152, a cold-end heat exchange structure 151, and a high-absorption coating 153. The hot-end heat exchange structure 152 is located inside the waste heat recovery outer cavity 13; the cold-end heat exchange structure 151 is connected to the hot-end heat exchange structure 152; and the high-absorption coating 153 is coated on the surface of the hot-end heat exchange structure 152.

[0053] The hot-end heat exchange structure 152 is a component used to absorb heat from a high-temperature heat source (such as exhaust waste heat from an aircraft engine) and transfer it to the working medium. This structure can employ a tube bundle structure with dense fins to significantly increase the heat exchange area, thereby improving heat capture efficiency; or it can employ a microchannel array to achieve higher heat transfer efficiency and a more compact structural design; or it can be a porous medium structure to enhance heat transfer by increasing surface area and promoting turbulence. Its core function is to efficiently capture the thermal energy from the waste heat recovery outer cavity 13. The cold-end heat exchange structure 151 is a component used to transfer heat from the working medium to a low-temperature heat sink (such as a cooling medium). This structure can employ a plate-fin heat exchanger to achieve efficient heat exchange through a multi-layer plate and fin structure; or it can employ a structure with an internally designed coolant circulation channel to remove heat through flowing coolant; or it can be a structure with external heat sinks to dissipate heat through convection and radiation. Its function is to provide a low-temperature region for the working medium to complete the thermodynamic cycle. The high-absorption coating 153 is a surface coating capable of efficiently absorbing electromagnetic radiation (especially infrared radiation) within a specific wavelength range and converting it into heat energy. This coating can be a carbon nanotube coating, which has extremely high blackness and absorptivity; or a selective absorption coating, such as a black chromium or nickel-based alloy coating, which is widely used in heat harvesting and can effectively absorb thermal radiation; or a specially treated ceramic coating whose surface roughness or microstructure helps to improve the absorptivity. Its function is to enhance the heat absorption capacity of the hot-end heat exchange structure 152. The placement of the hot-end heat exchange structure 152 inside the waste heat recovery outer cavity 13 ensures that the hot-end heat exchange structure 152 is directly exposed to the high-temperature environment generated by engine exhaust, thereby maximizing heat absorption. This provides a direct and efficient path for the transfer of heat from the external heat source to the working medium inside the inner cavity 15. The cold-end heat exchange structure 151 is connected to the hot-end heat exchange structure 152. This connection ensures that a complete, closed heat transfer loop is formed between the hot and cold ends, allowing the working medium to effectively exchange heat between them, thus completing the thermodynamic cycle. This connection can be direct physical contact or indirect connection through a thermally conductive material or fluid medium. A high-absorption coating 153 is applied to the surface of the hot-end heat exchange structure 152. This coating allows the hot-end heat exchange structure 152 to more effectively capture and absorb radiant heat energy from the waste heat recovery outer cavity 13. By increasing the surface's absorption capacity for thermal radiation, the efficiency of heat transfer from the heat source to the working medium can be significantly improved, reducing heat loss.

[0054] Among them, the hot end heat exchange structure 152 is a hot end heat exchange fin, and the cold end heat exchange structure 151 is a cold end heat exchange fin. The heat-conducting fin structure is adopted to increase the convective heat transfer area, thereby increasing the temperature difference between the hot and cold ends and improving the thermal efficiency of the system. The high absorptivity coating 153 is a high-temperature blackbody coating / other high absorptivity coating 153, which improves the heat absorption rate, further increases the hot end temperature, and increases the temperature difference between the hot and cold ends.

[0055] The solution of this application places the hot-end heat exchange structure 152 inside the waste heat recovery outer cavity 13, exposing it directly to the high-temperature exhaust environment. Simultaneously, a high-absorption coating 153 is applied to the surface of the hot-end heat exchange structure 152, greatly enhancing its ability to capture heat radiation. This design, in conjunction with the heat-insulating cavity 132, the high-radiation heat exchange mechanism 133, and the high-reflectivity coating 134 within the waste heat recovery outer cavity 13, enables more effective directional and concentrated radiation of engine exhaust waste heat onto the hot-end heat exchange structure 152 inside the inner cavity 15. The working medium, after efficiently absorbing heat at the hot-end heat exchange structure 152, rapidly expands, powerfully driving the dual-piston mechanism 18. Subsequently, the expanded working medium flows to the cold-end heat exchange structure 151 connected to the hot-end heat exchange structure 152, where it releases heat to the low-temperature heat sink and is compressed, thus completing an efficient thermodynamic cycle. The optimized design of this internal cavity 15 ensures that heat can be captured from the engine exhaust to the maximum extent and effectively transferred to the working medium, thereby providing a stable and sufficient heat source for the generator module 1 to drive the subsequent process of converting mechanical energy into electrical energy.

[0056] Through the above technical solution, this application incorporates a hot-end heat exchange structure 152, a cold-end heat exchange structure 151, and a high-absorption-rate coating 153 within the inner cavity 15, significantly improving the heat exchange efficiency of the waste heat recovery system. The high-absorption-rate coating 153 can more effectively capture radiant heat energy from the aircraft engine exhaust, reducing heat loss and ensuring that the hot-end heat exchange structure 152 can fully absorb heat. The hot-end heat exchange structure 152 is located inside the waste heat recovery outer cavity 13 and is directly exposed to the heat source. Combined with the high-absorption-rate coating 153, this makes heat absorption more thorough. The cold-end heat exchange structure 151 is connected to the hot-end heat exchange structure 152, forming an efficient heat exchange path, promoting the rapid expansion and compression of the heat transfer medium, thereby providing a stronger driving force for the dual-piston mechanism 18. This maximizes the utilization of engine exhaust waste heat, thereby improving the power generation efficiency and energy recovery rate of the entire generator module 1, providing a more stable and efficient auxiliary power source for the aircraft.

[0057] like Figure 4As shown, the dual-piston mechanism 18 includes: an expansion piston 181 and a sealing piston 182, with the sealing piston 182 connected to the expansion piston 181; the expansion piston 181 is correspondingly arranged with the hot end heat exchange structure 152; and the sealing piston 182 is correspondingly arranged with the cold end heat exchange structure 151.

[0058] Specifically, the dual-piston mechanism 18 is a device for converting thermal energy into mechanical energy. Its core lies in driving piston movement through the expansion and compression of the working fluid in different temperature regions. This mechanism typically includes at least two pistons, operating at the hot and cold ends respectively, to achieve a thermodynamic cycle. Its implementation can include, but is not limited to: a piston configuration similar to an Alpha Stirling engine, where the expansion piston 181 and compression piston are located in different cylinders and connected by a connecting rod mechanism; or a piston configuration similar to a Beta Stirling engine, where the expansion piston 181 and compression piston are located in the same cylinder but functionally separated through different motion trajectories. The expansion piston 181 is the main component in the dual-piston mechanism 18 responsible for absorbing heat in the high-temperature region and driving the expansion of the working fluid. This piston needs to possess good high-temperature resistance and a low coefficient of thermal expansion to ensure stable operation in high-temperature environments. The material of the expansion piston 181 can be a high-temperature resistant alloy, ceramic material, or composite material. Its structural design should maximize the contact area with the hot-end heat exchange structure 152 and ensure effective force transmission during expansion. The sealing piston 182 is the main component in the dual-piston mechanism 18 responsible for compressing the working fluid and maintaining the system's seal in the cryogenic region. This piston needs excellent sealing performance and a low coefficient of friction to reduce working fluid leakage and energy loss. The sealing piston 182 can be made of materials such as polymers with good self-lubricating properties, low-friction coated metals, or graphite composites. Its structural design should ensure a reliable seal with the cylinder wall while allowing smooth piston movement.

[0059] The expansion piston 181 is used to follow the airflow changes during the gas heating / cooling process, generate relative motion, and transmit it to the linkage transmission mechanism 19; the sealing piston 182 is used to adjust the volume change of the working gas due to temperature changes, follow the motion, and transmit the motion to the linkage transmission mechanism 19.

[0060] The connection between the sealing piston 182 and the expansion piston 181 is designed to achieve coordination and synchronization of their movements, ensuring the continuous operation of the Stirling cycle. This connection can be achieved using a rigid connecting rod, a flexible connecting rod, or indirectly through a crank-connecting rod mechanism. For example, the movements of the two pistons can be coupled together by one or more connecting rods, or their phase and stroke can be coordinated through a common crankshaft system. The expansion piston 181 is positioned corresponding to the hot-end heat exchange structure 152, meaning that the expansion piston 181 is located at or adjacent to the hot-end heat exchange structure 152 to efficiently absorb heat from it, causing the working fluid to expand rapidly. This corresponding arrangement can manifest as the expansion piston 181 being directly exposed to the thermal field generated by the hot-end heat exchange structure 152, or the movement area of ​​the expansion piston 181 being closely adjacent to the hot-end heat exchange structure 152, ensuring that heat can be quickly transferred to the working fluid. The sealed piston 182 is positioned correspondingly to the cold-end heat exchange structure 151, meaning that the sealed piston 182 is located at or adjacent to the cold-end heat exchange structure 151. This allows for the effective transfer of heat to the cold-end heat exchange structure 151 during the compression of the working fluid, thereby cooling the working fluid. This corresponding arrangement can manifest as the moving area of ​​the sealed piston 182 being closely adjacent to the cold-end heat exchange structure 151, or the cold-end heat exchange structure 151 directly cooling the cylinder wall where the sealed piston 182 is located, thus efficiently removing heat from the working fluid.

[0061] The waste heat recovery system for an aircraft power plant disclosed in this application, wherein the generator module 1 works collaboratively with the waste heat recovery outer cavity 13, inner cavity 15, dual-piston mechanism 18, linkage transmission mechanism 19, and target generator 17 to convert the exhaust waste heat of the aircraft engine into electrical energy. In the above scheme, the inner cavity 15 includes a hot-end heat exchange structure 152 and a cold-end heat exchange structure 151, and is coated with a high-absorption coating 153 for efficient heat absorption. Based on this, in order to efficiently convert the thermal energy of the working fluid in the inner cavity 15 into mechanical energy, this application further proposes a specific design for the dual-piston mechanism 18. The dual-piston mechanism 18 consists of an expansion piston 181 and a sealing piston 182, wherein the expansion piston 181 is correspondingly arranged with the hot-end heat exchange structure 152, and the sealing piston 182 is correspondingly arranged with the cold-end heat exchange structure 151, and the sealing piston 182 is connected to the expansion piston 181. When the hot-end heat exchange structure 152 absorbs heat from the waste heat recovery outer cavity 13, it transfers the heat to the working fluid inside the inner cavity 15 through the high-absorption coating 153, causing the working fluid near the hot-end heat exchange structure 152 to expand due to heat. At this time, the expansion piston 181, which is correspondingly arranged to the hot-end heat exchange structure 152, begins to move under the push of the expanding working fluid, converting thermal energy into mechanical energy. Subsequently, since the sealing piston 182 is connected to the expansion piston 181, the movement of the expansion piston 181 will drive the sealing piston 182 to move.

[0062] The sealed piston 182 is correspondingly positioned to the cold-end heat exchange structure 151. When the working fluid is compressed and comes into contact with the cold-end heat exchange structure 151, the heat is carried away by the cold-end heat exchange structure 151, the working fluid cools and contracts, thus completing a thermodynamic cycle. This dual-piston mechanism 18 design, by precisely corresponding the expansion piston 181 and the sealed piston 182 to the hot-end and cold-end heat exchange structures 151 respectively, ensures that the working fluid fully expands at the hot end and effectively compresses at the cold end. At the same time, the sealed piston 182 maintains the internal pressure of the system and the integrity of the working fluid cycle. The connection between the expansion piston 181 and the sealed piston 182 ensures the coordination of their movements, enabling the entire thermodynamic cycle to proceed continuously and stably, thereby efficiently converting waste heat into mechanical work, and then driving the target generator 17 to generate electricity.

[0063] Through the above technical solution, the expansion piston 181 is correspondingly arranged with the hot-end heat exchange structure 152, ensuring that the working fluid can absorb heat to the maximum extent and expand efficiently in the high-temperature region, thereby improving the efficiency of converting thermal energy into mechanical energy. The sealing piston 182 is correspondingly arranged with the cold-end heat exchange structure 151, ensuring that the working fluid can effectively dissipate heat and compress in the low-temperature region, maintaining the balance of the thermodynamic cycle. At the same time, the presence of the sealing piston 182 significantly improves the sealing performance of the system, effectively preventing working fluid leakage and avoiding energy loss and system efficiency decline. The connection between the expansion piston 181 and the sealing piston 182 ensures that their movements are coordinated and consistent, ensuring the continuity and stability of the Stirling cycle, thereby enabling the entire waste heat recovery system to convert the exhaust waste heat of the aircraft engine into electrical energy more efficiently and stably, further improving the energy utilization efficiency of the aircraft's power plant.

[0064] like Figure 7 , Figure 8 , Figure 9 As shown, one end of the linkage drive mechanism 19 is connected to the double piston mechanism 18, and the other end of the linkage drive mechanism 19 is connected to the target generator 17. The target generator 17 includes: a generator output shaft 171, a hollow cup rotor 172, and a double-winding stator 173. The generator output shaft 171 is connected to the linkage drive mechanism 19; the hollow cup rotor 172 is connected to the generator output shaft 171; and the double-winding stator 173 is correspondingly arranged with respect to the hollow cup rotor 172.

[0065] The hollow cup dual-winding brushless generator eliminates the energy loss caused by eddy currents in the iron core, and significantly reduces the mechanical energy loss of the rotor itself due to the reduction in weight and moment of inertia; the dual-winding design improves the safety of the system. The linkage mechanism 19 is a mechanical device that converts reciprocating or rotary motion into another form of motion. It typically consists of components such as connecting rods, cranks, and rockers. Its function is to efficiently and accurately transmit the mechanical motion generated by the double-piston mechanism 18 to the target generator 17, ensuring a smooth energy conversion process. This mechanism can be implemented in various forms, such as crank-connecting rod mechanisms, slider-connecting rod mechanisms, or planetary gear-connecting rod mechanisms. The target generator 17 is the core component responsible for converting mechanical energy into electrical energy. Its type can include permanent magnet synchronous generators, induction generators, or DC generators. The generator output shaft 171 is a rotating component in the target generator 17 used to receive or output mechanical energy. It is typically made of high-strength materials and can be a solid or hollow shaft. It is connected to the linkage mechanism 19 and the hollow cup rotor 172 via keyed connections, splined connections, or interference fits. The hollow cup rotor 172 is a rotor structure with low rotational inertia. Its windings are typically cup-shaped and coreless or use non-magnetic support materials, enabling rapid response and high dynamic performance. The dual-winding stator 173 is a fixed part of the target generator 17. It contains two independent or interconnected windings, which can provide more flexible power output characteristics, such as two-phase output or more stable single-phase output through a specific connection method. Its windings can adopt star connection, delta connection or orthogonal winding design.

[0066] The proposed solution efficiently and directly transmits the mechanical motion generated by the dual-piston mechanism 18 to the target generator 17 via the linkage mechanism 19. Inside the target generator 17, the generator output shaft 171 receives the rotational input from the linkage mechanism 19 and drives the hollow cup rotor 172 to rotate. The hollow cup rotor 172, with its inherent low moment of inertia, can quickly respond to changes in motion transmitted by the linkage mechanism 19. Even if there are fluctuations in the output speed of the dual-piston mechanism 18, the hollow cup rotor 172 can quickly adjust its operating state, thereby effectively suppressing drastic fluctuations in the power generation frequency. Simultaneously, the design of the dual-winding stator 173 provides greater flexibility and stability for power output. For example, specific winding connection methods or control strategies can further smooth the output voltage and frequency, thereby simplifying the design of the subsequent power management system. This structural combination allows the entire power generation system to better adapt to the dynamic changes that may occur during the recovery of waste heat from aircraft engine exhaust, ensuring the stability and quality of power output and significantly reducing reliance on complex external power management and rectifier circuits.

[0067] In one specific implementation, the linkage mechanism 19 can employ a crank-slider mechanism, where the crank is connected to the output end of the double-piston mechanism 18, and the slider is connected to the generator output shaft 171 of the target generator 17, converting the reciprocating motion of the double-piston mechanism 18 into the rotational motion of the generator output shaft 171. The generator output shaft 171 can be made of high-strength alloy steel and reliably connected to the linkage mechanism 19 and the hollow cup rotor 172 via a spline connection. The hollow cup rotor 172 can be made of copper wire wound on a non-magnetic composite material support cylinder and integrally cured with epoxy resin to ensure its mechanical strength and low moment of inertia. The dual-winding stator 173 can be configured as two independent star-connected windings, each with its own independent power supply line, allowing for flexible power output configuration or parallel connection to enhance output stability according to system requirements.

[0068] Through the above technical solution, the waste heat recovery system of the aircraft power unit of this application can effectively cope with the dynamic changes in the mechanical energy output of the dual-piston mechanism 18, ensuring that the target generator 17 outputs stable and high-quality electrical energy under different operating conditions. This significantly reduces the dependence on external complex power management and rectification circuits, thereby simplifying the overall design of the power generation system, reducing system complexity and hardware costs, and improving the dynamic adaptability and reliability of the system.

[0069] The operating parameters include the rotational speed and / or hot-end temperature of the generator module 1; the control module 2 is specifically configured to: control the battery module 3 to enter the charging state when the rotational speed of the generator module 1 is higher than the first preset threshold; and control the battery module 3 to enter the discharging state or stop charging when the rotational speed of the generator module 1 is lower than the second preset threshold.

[0070] Among these, operating parameters are key indicators for measuring the working status of generator module 1. The rotational speed of generator module 1 refers to the number of revolutions its internal rotating parts make per unit time, directly reflecting its instantaneous power generation capacity. This speed can be monitored in real time by a speed sensor installed on the target generator 17 or the linkage transmission mechanism 19. The hot-end temperature refers to the temperature of the part of generator module 1 in contact with the heat source, such as the temperature at the hot-end heat exchange structure 152 corresponding to the expansion piston 181 of the double-piston mechanism 18. This temperature directly reflects the degree of thermal expansion of the Stirling cycle working fluid and affects the energy conversion efficiency of generator module 1. The hot-end temperature can be measured using temperature sensing devices such as thermocouples, thermistors, or infrared temperature sensors.

[0071] The first preset threshold is a pre-set speed value, representing the minimum speed at which generator module 1 can generate electricity stably and efficiently, producing sufficient surplus energy to charge battery module 3. This threshold can be calibrated and adjusted based on the performance curve of generator module 1, the charging characteristics of battery module 3, and the overall energy management strategy of the system. The charging state refers to the operating mode in which battery module 3 receives and stores electrical energy from generator module 1. Control module 2 activates its internal charging management unit by sending a charging command to battery module 3, causing it to begin absorbing electrical energy. This typically involves closing the power switch in the charging circuit and may adjust the charging current and voltage to optimize the charging process.

[0072] The second preset threshold is another pre-set speed value, usually lower than the first preset threshold. This indicates that the generator module 1's power generation capacity is insufficient to meet the system load demand, or its power generation efficiency is too low, making it unsuitable for continued charging. This threshold can also be set based on the system load, the discharge characteristics of the battery module 3, and the inefficient operating range of the generator module 1. Discharge state refers to the operating mode of the battery module 3 providing electrical energy to the system load. When the generator module 1's power generation is insufficient, the control module 2 will instruct the battery module 3 to enter a discharge state, supplying power to the system through its internal discharge management unit to maintain the continuity of power supply. Stopping charging means that the control module 2 interrupts the charging process of the battery module 3. When the generator module 1's speed is lower than the second preset threshold, even if the generator module 1 is still working, its power generation may be insufficient for effective charging. In this case, the control module 2 will disconnect the charging circuit to prevent ineffective charging or unnecessary damage to the battery module 3.

[0073] The solution in this application continuously acquires the real-time operating parameters of the generator module 1 through the control module 2. When the rotational speed of the generator module 1 is detected to be higher than a preset first threshold, it indicates that the generator module 1 is in a high-efficiency power generation state, and the generated electrical energy not only meets the immediate load of the system but also has surplus energy. At this time, the control module 2 will issue a command to put the battery module 3 into a charging state to store the excess electrical energy. This mechanism ensures that when the power generation capacity is sufficient, the electrical energy converted from waste heat can be recovered and utilized to the maximum extent, avoiding energy waste. Conversely, when the rotational speed of the generator module 1 is lower than a preset second threshold, this usually means that the power generation efficiency of the generator module 1 is reduced, the output power is insufficient, and it may even be unable to charge effectively. In this case, the control module 2 will, according to a preset strategy, instruct the battery module 3 to enter a discharging state, and the battery module 3 will provide power to the system to compensate for the insufficient power of the generator module 1, ensuring the continuity and stability of the system power supply; or, the control module 2 will instruct the battery module 3 to stop charging to avoid ineffective charging in an inefficient power generation state, thereby protecting the battery module 3 and optimizing energy management. Through real-time monitoring of the aforementioned operating parameters and threshold-based intelligent control, this solution enables a dynamically balanced energy management system between generator module 1 and battery module 3. Generator module 1, as the energy producer, has its output affected by the aircraft engine's operating conditions, while battery module 3 acts as an energy buffer and regulator. When generator module 1 generates a large amount of power, battery module 3 absorbs energy; when power generation is low, battery module 3 releases energy. This collaborative working method ensures that the system maintains efficient and reliable energy recovery and power supply under various operating conditions.

[0074] This application realizes the resource recovery and utilization of engine waste heat, converting the originally directly emitted waste heat into electrical energy, reducing energy waste, and simultaneously reducing thermal pollution caused by direct engine waste heat emissions, lowering the ambient temperature around the engine, which aligns with the development trend of energy conservation, emission reduction, and green environmental protection. Furthermore, it is adaptable to different types and power engines, with a wide range of applications. It can serve as a distributed power supply device, reducing reliance on the power grid or the engine's own generator, demonstrating strong practicality and significant economic and environmental benefits. By real-time monitoring of the rotational speed and / or hot-end temperature of generator module 1, and dynamically adjusting the charging and discharging state of battery module 3 based on preset thresholds, the system can store excess electrical energy in a timely manner when generator module 1 has sufficient power generation capacity, maximizing the recovery of waste heat energy. When power generation capacity is insufficient, it can intelligently switch to battery module 3 for power supply or stop ineffective charging, ensuring the continuity and stability of power supply. This not only significantly improves the energy utilization efficiency of the aircraft power plant waste heat recovery system and reduces energy waste, but also optimizes the operating life and reliability of battery module 3, avoiding damage caused by improper charging and discharging, thereby improving the adaptability and robustness of the entire aircraft electrical system.

[0075] like Figure 10 As shown, a method for controlling waste heat recovery from an aircraft propulsion system includes: The system acquires the operating parameters of the generator module, including speed and / or hot-end temperature; compares the operating parameters with preset thresholds; generates charge / discharge control commands based on the comparison results: generates a charging command when the speed is higher than a first preset threshold, and generates a discharging or stop-charging command when the speed is lower than a second preset threshold; and executes the charge / discharge control commands to control the charging and discharging state of the battery module.

[0076] In the step of acquiring the operating parameters of the generator module, including speed and / or hot-end temperature, its role is to provide real-time operating status basis for control decisions, ensuring that control is based on actual data. This step can be achieved by installing speed sensors (e.g., Hall effect sensors, photoelectric encoders) and temperature sensors (e.g., thermocouples, thermistors) on the generator module to collect speed and hot-end temperature data in real time. These sensors transmit analog or digital signals to the control module. Alternatively, the drive circuit or management unit inside the generator module can also directly output its current speed and hot-end temperature information, which the control module receives through communication interfaces (e.g., CAN bus, SPI, I2C, RS422, RS485, etc.).

[0077] In the step of comparing the operating parameters with preset thresholds, its function is to identify the current operating state of the system by comparing the generator module's operating parameters (especially the rotational speed) with the preset thresholds, providing a basis for subsequent charging and discharging control decisions. The microprocessor or digital signal processor (DSP) inside the control module can receive the operating parameter data and compare it numerically with a first preset threshold and a second preset threshold stored in memory. The comparison operation can be greater than, less than, equal to, or within a certain range. Alternatively, a lookup table can be used to indirectly complete the comparison and judgment by searching for the corresponding state or instruction in a pre-defined table based on the received operating parameter value.

[0078] In the step of generating charging and discharging control commands based on the judgment result—generating a charging command when the speed is higher than a first preset threshold, and generating a discharging or stop-charging command when the speed is lower than a second preset threshold—its function is to dynamically generate corresponding control commands based on the operating state of the generator module (determined by the comparison result of the speed and the threshold) to optimize energy recovery and system stability. The software logic of the control module can include conditional judgment statements (e.g., if-else structures). When the speed is detected to meet the condition of "higher than the first preset threshold," a specific charging command signal is generated; when the speed is detected to meet the condition of "lower than the second preset threshold," a discharging command or stop-charging command signal is generated. These commands can be digital signals or specific communication protocol messages. Furthermore, intelligent control algorithms such as fuzzy logic controllers or neural networks can also be used to output corresponding charging and discharging commands based on the input speed and threshold relationship, achieving more refined control.

[0079] In the step of executing the charge and discharge control commands to control the charging and discharging state of the battery module, the control module's role is to translate the generated control commands into actual operations on the battery module, thereby achieving effective management of energy storage and release. The control module can drive the charging management unit (e.g., DC-DC converter, charging controller) or discharging management unit (e.g., inverter, load controller) inside the battery module via a digital output port or PWM (pulse width modulation) signal, causing it to enter charging, discharging, or stop charging states. Simultaneously, the control module can also send commands to the battery management system (BMS) of the battery module via a communication interface (e.g., CAN, RS485), with the BMS responsible for specifically regulating the charging and discharging currents and switching the charging and discharging modes.

[0080] The proposed solution acquires the operating parameters of the generator module, particularly its rotational speed and / or hot-end temperature, providing real-time data for control decisions. Then, by comparing these operating parameters with preset first and second threshold values, the system accurately determines the current operating state of the generator module. Based on this determination, the control module intelligently generates corresponding charging and discharging control commands. For example, it generates charging commands at high rotational speeds to fully recover energy, and generates discharging or stop-charging commands at low rotational speeds to avoid ineffective operations. Finally, these commands are executed to control the charging and discharging state of the battery module. This series of steps forms a closed-loop control system, enabling the control module to dynamically manage the charging and discharging of the battery module, thereby optimizing waste heat recovery efficiency and ensuring the stable operation of the entire aircraft power plant waste heat recovery system. Combined with the aforementioned aircraft power plant waste heat recovery system, this method allows the system to intelligently adjust its energy storage strategy according to the actual operating conditions of the generator module, effectively addressing the shortcomings of traditional control methods in terms of dynamic adaptability and improving the energy management efficiency and reliability of the entire system.

[0081] Through the above technical solution, this application can monitor the operating status of the generator module in real time and intelligently adjust the charging and discharging strategy of the battery module based on the comparison between the rotational speed and a preset threshold. When the generator module is operating efficiently, the system can promptly store the generated electrical energy into the battery module, maximizing waste heat recovery efficiency. When the generator module is operating inefficiently or stops, the system can avoid ineffective charging or promptly switch to discharging mode, thereby effectively preventing energy waste and ensuring the stability and reliability of the entire aircraft power plant waste heat recovery system. This dynamic control mechanism significantly improves the system's adaptability to changes in aircraft engine operating conditions, optimizes energy management, and solves the shortcomings of traditional control methods in terms of dynamic adaptability.

[0082] like Figure 11 As shown, it also includes the physical process of waste heat recovery: the engine exhaust is filtered through a honeycomb ceramic filter and then introduced into the waste heat recovery outer cavity; the heat is radiated directionally to the inner cavity through a high reflectivity coating and a high radiation heat exchange mechanism; the heat is absorbed by the high absorptivity coating, causing the heat transfer medium to expand and drive the double piston mechanism to move; and the target generator is driven to generate electricity through the linkage transmission mechanism.

[0083] The process involves filtering engine exhaust through a honeycomb ceramic filter before introducing it into the waste heat recovery outer cavity. This honeycomb ceramic filter is a ceramic material with a porous honeycomb structure, whose main function is to filter particulate matter, soot, and other impurities from the engine exhaust, protecting the internal components of the subsequent waste heat recovery system from contamination and wear, and ensuring the cleanliness of the heat source entering the system. This can be achieved by using silicon carbide or cordierite materials with different pore sizes and wall thicknesses to adapt to different engine exhaust characteristics and filtration precision requirements. Introducing the filtered engine exhaust into the waste heat recovery outer cavity refers to guiding it into a specially designed cavity, which serves as the inlet for the waste heat recovery system, used for initial heat collection and guidance. This can be achieved through a high-temperature resistant pipe sealed to the waste heat recovery outer cavity, ensuring the continuity of exhaust flow and effective heat transfer.

[0084] In another embodiment, The engine starts, and the engine exhaust preheats the hot end of the Stirling generator module. The generator control module detects the hot-end temperature of the Stirling generator module and determines whether the preset temperature has been reached. Once the preset temperature is reached, the generator control module connects to the battery and uses a small current to control the starter generator module to start it and make it rotate, thus completing the start-up process. The generator control module detects the generator speed and determines whether the preset speed has been reached. Once the generator reaches the preset speed, the generator control module cuts off the input to the battery and switches the generator to power generation mode. After switching to generator mode, the generator control module continues to collect engine exhaust parameters and generator output current, voltage and other parameters, and dynamically adjusts the output status of the generator and battery.

[0085] Heat is directionally radiated to the inner cavity through a high-reflectivity coating and a high-radiation heat exchange mechanism. The high-reflectivity coating is a material layer that efficiently reflects thermal radiation, reducing heat loss to the outside of the waste heat recovery outer cavity and concentrating heat reflection towards the inner cavity, thereby improving heat utilization efficiency. This coating can be made of metal oxides (such as alumina or zirconium oxide) or special metals (such as silver or gold) and uniformly coated on the inner wall of the outer cavity shell. The high-radiation heat exchange mechanism is a structure designed to enhance the efficiency of heat radiation transfer. Its function is to receive heat from engine exhaust and, through its high-radiation characteristics, efficiently transfer the heat to the inner cavity in the form of radiation. This mechanism can be designed as a finned structure with a large surface area, a porous structure, or a special arc-shaped structure, and is manufactured using high-emissivity materials (such as silicon carbide or nickel-based superalloys). Directional radiation refers to the synergistic effect of the high-reflectivity coating and the high-radiation heat exchange mechanism, which concentrates heat primarily in the form of radiation to the inner cavity, minimizing heat loss in other directions and ensuring efficient absorption of thermal energy by the inner cavity.

[0086] The high-absorptivity coating absorbs heat, causing the heat transfer medium to expand and drive the double-piston mechanism. This high-absorptivity coating is a material layer that efficiently absorbs thermal radiation, maximizing the absorption of heat from the high-radiation heat exchange mechanism and transferring it to the heat transfer medium within the inner cavity. This coating is typically black or dark-colored and can be made of nano-carbon materials, selective absorption coatings, or special ceramic materials, and is applied to the surface of the hot-end heat exchange structure within the inner cavity. The expansion of the heat transfer medium (such as helium) refers to the increase in temperature and volume of the heat transfer medium within the inner cavity after absorbing heat, generating an expansion force. This expansion is the core of the Stirling cycle's working principle, converting thermal energy into mechanical energy. Driving the double-piston mechanism means that the expansion force of the heat transfer medium acts on the double-piston mechanism, causing it to reciprocate. The double-piston mechanism typically includes an expanding piston and a sealing piston; the movement of the pistons converts the expansion energy of the working medium into mechanical energy.

[0087] A target generator is driven to generate electricity via a linkage mechanism, which is a mechanical device that converts the reciprocating linear motion of a double-piston mechanism into rotational motion. Its function is to transfer the mechanical work generated by the double-piston mechanism to the target generator. This mechanism can take the form of a crank-connecting rod mechanism, a rocker-arm connecting rod mechanism, or a cam mechanism, and consists of components such as connecting rods and a crankshaft. Driving the target generator to generate electricity means that the linkage mechanism transfers mechanical energy to the target generator, which, driven by this mechanical energy, converts it into electrical energy through electromagnetic induction. The target generator can be a permanent magnet synchronous generator or an induction generator, and its output shaft is connected to the linkage mechanism.

[0088] The proposed solution efficiently converts waste heat from aircraft engine exhaust into electrical energy through the aforementioned waste heat recovery physical process. First, the engine exhaust is filtered through a honeycomb ceramic filter to remove impurities, ensuring the cleanliness of the heat source, which is crucial for protecting subsequent precision components. Then, the filtered exhaust enters the waste heat recovery outer cavity. The high-reflectivity coating inside the outer cavity effectively reduces heat loss to the outside, while a high-radiation heat exchange mechanism efficiently transfers heat to the inner cavity in the form of radiation. The high-absorptivity coating on the surface of the inner cavity maximizes the absorption of this radiant heat, causing the internal heat transfer medium to expand. The expansion force of the medium drives a dual-piston mechanism to reciprocate, converting thermal energy into mechanical energy. Finally, a linkage transmission mechanism converts the reciprocating motion of the dual-piston mechanism into rotational motion, thereby driving the target generator to generate electricity, realizing the conversion of mechanical energy into electrical energy. The entire physical process is closely integrated with the aforementioned waste heat recovery control method. This method acquires the generator module's operating parameters (such as speed and / or hot-end temperature), compares these parameters with preset thresholds, and generates charging and discharging control commands based on the results. This allows for precise control of the battery module's charging and discharging state. This integration enables the waste heat recovery system not only to efficiently convert waste heat into electrical energy but also to intelligently manage the storage and release of electrical energy based on the system's operating status, ensuring the stability and efficiency of the entire system under different operating conditions.

[0089] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of those features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0090] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A waste heat recovery system for an aircraft propulsion system, comprising: A generator module, a control module, and a battery module are characterized in that the hot end of the generator module is configured to receive exhaust waste heat from an aircraft engine; the control module is electrically connected to the generator module and is used to acquire the operating parameters of the generator module; the battery module is electrically connected to the control module; wherein the control module is configured to control the charging and discharging state of the battery module based on the operating parameters.

2. The waste heat recovery system for aircraft propulsion systems according to claim 1, characterized in that, The generator module includes: an engine exhaust port connected to the aircraft engine; a waste heat recovery outer cavity connected to the engine exhaust port; an exhaust pipe connected to the waste heat recovery outer cavity; an inner cavity at least partially disposed within the waste heat recovery outer cavity; a transmission component sealing cavity connected to the inner cavity; a target generator connected to the transmission component sealing cavity; a linkage transmission mechanism connected to the target generator; and a dual-piston mechanism connected to the linkage transmission mechanism.

3. The waste heat recovery system for aircraft propulsion systems according to claim 2, characterized in that, The engine exhaust port is equipped with a honeycomb ceramic filter.

4. The waste heat recovery system for aircraft propulsion systems according to claim 2, characterized in that, The waste heat recovery outer cavity includes: an outer cavity shell, a heat insulation cavity, and a high-radiation heat exchange mechanism; the heat insulation cavity is located on the side of the outer cavity shell near the engine exhaust port; the high-radiation heat exchange mechanism is located inside the outer cavity shell, and the high-radiation heat exchange mechanism is an arc-shaped structure facing the inner cavity; a high-reflectivity coating is applied to the inner wall surface of the outer cavity shell.

5. The waste heat recovery system for aircraft propulsion systems according to claim 2, characterized in that, The inner cavity includes: a hot-end heat exchange structure, a cold-end heat exchange structure, and a high-absorption coating. The hot-end heat exchange structure is located inside the waste heat recovery outer cavity; the cold-end heat exchange structure is connected to the hot-end heat exchange structure; and the high-absorption coating is applied to the surface of the hot-end heat exchange structure.

6. The waste heat recovery system for aircraft propulsion systems according to claim 5, characterized in that, The dual-piston mechanism includes: an expansion piston and a sealing piston, wherein the sealing piston is connected to the expansion piston; the expansion piston is correspondingly arranged with respect to the hot-end heat exchange structure; and the sealing piston is correspondingly arranged with respect to the cold-end heat exchange structure.

7. The waste heat recovery system for aircraft propulsion systems according to claim 2, characterized in that, One end of the linkage transmission mechanism is connected to the double piston mechanism, and the other end of the linkage transmission mechanism is connected to the target generator. The target generator includes: a generator output shaft, a hollow cup rotor, and a double-winding stator. The generator output shaft is connected to the linkage transmission mechanism; the hollow cup rotor is connected to the generator output shaft; and the double-winding stator is arranged correspondingly to the hollow cup rotor.

8. The waste heat recovery system for aircraft propulsion systems according to claim 6, characterized in that, The operating parameters include the rotational speed and / or hot-end temperature of the generator module; The control module is specifically configured to: control the battery module to enter a charging state when the speed of the generator module is higher than a first preset threshold; and control the battery module to enter a discharging state or stop charging when the speed of the generator module is lower than a second preset threshold.

9. A waste heat recovery control method for the system of claim 1, characterized in that, include: Obtain the operating parameters of the generator module, including speed and / or hot end temperature; Determine the relationship between the operating parameters and the preset threshold; Based on the judgment result, charge and discharge control commands are generated: when the rotation speed is higher than the first preset threshold, a charging command is generated; when the rotation speed is lower than the second preset threshold, a discharging or stop charging command is generated. The charge and discharge control commands are executed to control the charge and discharge state of the battery module.

10. The method according to claim 9, characterized in that, It also includes the physical processes of waste heat recovery: The engine exhaust is filtered through a honeycomb ceramic filter and then introduced into the waste heat recovery outer cavity; Heat is radiated directionally to the inner cavity through a high-reflectivity coating and a high-radiation heat exchange mechanism; The high-absorption coating absorbs heat, causing the heat transfer medium to expand and drive the movement of the dual-piston mechanism. The target generator is driven to generate electricity through a linkage transmission mechanism.

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