Compact medium-temperature fuel cell jet engine multi-mode split hybrid propulsion system

Abstract

The invention provides a compact medium-temperature fuel cell jet engine multi-mode split hybrid propulsion system, and aims to improve the efficiency of an aircraft propulsion system and reduce environmental pollution. Compared with a traditional engine, the engine adopts the parallel double-shaft design, flexible transmission and distribution of power are achieved through the bevel gears and the clutches, and two working modes are supported to drive a fan, namely, a shaft driving mode and an electric driving mode. And in the medium temperature mode, the engine abandons a high-pressure compressor, and air treated by a low-pressure compressor is directly sent to the cathode of the fuel cell, is heated together with mixed gas obtained after combustion of hydrogen and oxygen, and then enters the anode. The invention also considers the configuration of the galvanic pile, and adopts a hollow cylinder configuration, so as to increase the reaction area and improve the thermal management. And meanwhile, the slender structure optimizes the space utilization, so that the overall layout is more compact. The coupled lower structure allows integration of a plurality of motors, facilitating heat dissipation and maintenance. And the shell cover provides protection for the internal structure, so that the durability and the safety are enhanced. Through the innovative design, the engine has remarkable advantages in the aspects of improving the heat efficiency, reducing the oil consumption rate and reducing NOx emission, and has important significance on environmental protection and development of the aviation propulsion technology.

Description

Technical Field

[0001] The present invention relates to the technical field of aviation propulsion, and in particular, to a compact medium-temperature fuel cell jet engine multimodal split hybrid propulsion system. Background Art

[0002] With the increasing global awareness of environmental protection and the growing severity of the energy crisis, the aviation industry is facing the dual challenges of reducing fuel consumption and harmful emissions. As the core component of an aircraft, the performance of an aviation propulsion system directly affects the fuel economy and environmental friendliness of the aircraft. According to statistics, the carbon emissions of the aviation industry account for 2% to 3% of the global total emissions. Therefore, developing new types of efficient and low-emission aviation propulsion systems is of great significance.

[0003] Traditional aviation engines mainly rely on fossil fuels, and convert the chemical energy of the fuel into mechanical energy through the combustion process to generate propulsion force. However, significant energy losses occur during this conversion process, resulting in an overall efficiency that only remains at a relatively low level of approximately 35%. In contrast, proton exchange membrane fuel cells (PEMFCs) exhibit significant efficiency advantages, with an energy conversion efficiency of up to approximately 50%. Such fuel cells can not only effectively convert the chemical energy of the fuel directly into electrical energy, thereby improving the efficiency of the entire system, but they also have highly environmentally friendly characteristics and do not produce large amounts of nitrogen oxides (NOx) and other greenhouse gases during operation, causing less negative impact on the environment, which is of great significance for alleviating the current severe exhaust gas pollution problem.

[0004] In addition, many countries around the world have put forward more stringent requirements for the fuel efficiency and pollution emissions of new-generation aircraft and have formulated increasingly strict environmental protection regulations. Against this background, fuel cells, as a clean energy conversion technology, have attracted much attention due to their high efficiency and low emission characteristics. In particular, proton exchange membrane fuel cells (PEMFCs) are considered to be strong candidates for future aviation propulsion systems due to their moderate operating temperature, fast startup, small size, and relatively excellent thermal management capabilities. However, applying fuel cell technology to the aviation field faces a series of technical challenges, including system integration, durability, and cost-effectiveness.

[0005] In the prior art, the combination of fuel cells and turbine engines has made some progress, but most designs still rely on complex heat exchanger systems to manage heat, which increases the weight and complexity of the system. In China, Deng Hongwu et al. focused on the development and application of ultra-light and efficient heat exchangers for aeroengines, and their research provided new ideas and directions for the design of aeroengine heat exchangers. Wen Qi, Pei Xinyan et al. evaluated the application effect of air-oil heat exchangers in variable cycle engines by establishing a performance simulation model. Xu Guoqiang et al. were committed to the thermal protection research of high-temperature components and achieved important results in the field of aeroengine heat exchangers. In addition, Zhu Kun et al. reviewed the coking heat transfer of aviation kerosene under supercritical pressure. And Su Lei et al. optimized the performance of small-sized air-oil heat exchangers through experiments and simulations. These studies demonstrated the research progress in the field of aeroengine heat exchangers, and also pointed out the problem that heat exchangers in the prior art increase the weight and complexity of the system. Internationally, NASA in the United States and industry partners jointly developed the design of thin-walled channels, which demonstrated possible design options, various processing path strategies and determined process geometry limitations, further promoting the development of heat exchanger technology. Dr Ali Nabavi et al. conducted in-depth research on the computational fluid dynamics (CFD) modeling of heat exchangers, and Xuan Tao et al. studied the heat transfer and friction pressure drop prediction models for ammonia condensation in plate heat exchangers. German research institutions are also exploring new heat exchanger technologies. For example, Lei Yong et al.'s research mainly focused on the research of nanostructured heat exchangers to further improve the heat transfer efficiency.

[0006] However, most of the previous studies focused on the optimization of heat exchangers and did not delve deeply into the design without heat exchangers. Therefore, the present invention studies a fuel cell turbine dual-mode combined engine technology without a heat exchanger. This design reduces heat loss during the energy conversion process and improves the thermal efficiency of the engine by eliminating the traditional heat exchanger. At the same time, it simplifies the system structure, reduces weight and complexity. This innovative design is expected to fully utilize the potential of fuel cells, improve the efficiency of the overall propulsion system, reduce dependence on fossil fuels, and reduce environmental impact.

[0007] Therefore, how to overcome the above technical problems and achieve the high efficiency, environmental protection and economy of the aviation propulsion system is the key issue that urgently needs to be broken through in the current field of aviation propulsion technology. Summary of the Invention

[0008] In view of this, in order to improve the efficiency of the aircraft propulsion system and reduce environmental pollution, the present invention proposes a compact medium-temperature fuel cell jet engine multi-mode split hybrid propulsion system, which does not rely on traditional fossil fuels, but instead introduces a high-temperature proton exchange membrane fuel cell stack and achieves efficient propulsion through a dual mode of electric drive and shaft drive.

[0009] In order to achieve the above-mentioned objectives, the present invention adopts the following technical scheme: the compact medium-temperature fuel cell jet engine multi-mode split hybrid propulsion system of the present invention includes a multi-gas dynamic transmission pipeline system, a vertical connecting shaft, an inner shell, an outer shell, and an air inlet, a fan, a low-pressure compressor, a connecting shaft, an outer duct, a hydrogen-rich combustion chamber, a combustion chamber, an electric motor system, a high-temperature proton exchange membrane fuel cell, a DC conversion device, a low-pressure turbine, a tail nozzle, and a lubricating oil circuit system arranged in the inner shell.

[0010] The inner casing is fixed in the outer casing by means of fixed supports to form a closed engine core structure.

[0011] The inlet is located at the front end of the inner casing and is used to guide air into the low-pressure compressor. The duct is located at the rear of the fan and is used to guide the duct airflow to improve engine efficiency. The low-pressure turbine tail nozzle is located at the rear end of the inner casing and is used to guide the exhaust of the combusted gas to generate thrust.

[0012] The connecting shaft runs through the inner shell and adopts a parallel double-shaft design. It uses bevel gears and clutches to achieve flexible transmission and distribution of power, and supports two working modes to drive the fan: shaft drive mode and electric drive mode.

[0013] More specifically, the parallel dual-axis structure includes axis 1 and axis 2; the low-pressure compressor, combustion chamber, cryogenic pump, medium-temperature proton membrane exchange cell, low-pressure turbine and tail nozzle are connected through axis 1; the fan and electric motor are connected through axis 2. Axis 1 and axis 2 adopt a parallel dual-axis design, which cleverly utilizes the combination of vertical connecting shafts, bevel gears and clutches to achieve flexible power allocation and transmission between the two parallel shafts. What is particularly important is that the power transmission between axis 1 and axis 2 is unidirectional, that is, axis 1 does not transmit power to axis 2. This design ensures that the engine can switch freely between dual-mode working modes according to actual needs.

[0014] Furthermore, the lubricating oil circuit system includes a lubricating oil pump, which is arranged on parallel double shafts. An accessory gear box is fixed to the tail of the inner shell, and the accessory gear box is connected to the lubrication system of the engine. All shaft systems are lubricated with oil, and the lubricating oil pump then pumps up the lubricating oil for recycling.

[0015] Furthermore, the high-temperature proton exchange membrane fuel cell integrates three high-temperature proton exchange membrane fuel cell stacks, adopting a slender structure. Each fuel cell stack is connected in parallel, has a small cross-sectional area, and is fixed on shaft 1. The high-temperature proton exchange membrane fuel cell stack adopts a special hollow cylindrical structure. The air passing through the low-pressure compressor can be directly sent to the cathode of the high-temperature proton exchange membrane fuel cell. After hydrogen and oxygen burn in the combustion chamber and are mixed with additional hydrogen, the temperature rises and then enters the anode of the high-temperature proton exchange membrane fuel cell. During this electrochemical reaction process, the fuel cell stack generates direct current.

[0016] Furthermore, the motor system adopts a coupled lower structure, in which four motors are connected by shaft 2. The stator and heat exchange device are arranged behind the fan and conduct heat exchange with the incoming air to achieve effective heat dissipation. The motor system is connected to the mechanical load through an accessory gearbox.

[0017] Particularly, the beneficial effects of the compact medium-temperature fuel cell jet engine multimodal split hybrid propulsion system described in the present invention are as follows:

[0018] (1) For the compact medium-temperature fuel cell jet engine multimodal split hybrid propulsion system described in the present invention, compared with the traditional aviation gas turbine engine, it adopts a special coaxial double-shaft design and is connected through the ingenious combination of a vertical connecting shaft, bevel gears, and a clutch, realizing the flexible distribution and transmission of power between the two coaxial shafts. This design enables the ducted fan to have two working modes, and thus the engine can freely switch between the electric drive and shaft drive modes according to flight conditions, thereby optimizing fuel consumption and enhancing the overall performance of the engine.

[0019] (2) For the compact medium-temperature fuel cell jet engine multimodal split hybrid propulsion system described in the present invention, it adopts a design without a heat exchanger, reducing the need for a traditional heat exchanger, thereby reducing heat loss during the energy conversion process and further improving the overall thermal efficiency of the engine.

[0020] (3) For the compact medium-temperature fuel cell jet engine multimodal split hybrid propulsion system described in the present invention, it adopts high-temperature proton exchange membrane fuel cell technology, reducing the dependence on fossil fuels compared with the traditional aviation gas turbine engine.

[0021] (4) The compact medium-temperature fuel cell jet engine multi-modal split hybrid propulsion system described in the present invention. The fuel cell stack of the present invention adopts a hollow cylindrical design, and the anode gas and cathode gas are introduced through the spiral channels of the small holes on the edge of the hollow cylindrical fuel cell stack. Compared with the traditional straight channel design, the pressure loss is greatly reduced. At the same time, the spiral channel design increases the contact area of the gas and prolongs the residence time of the gas in the medium-temperature fuel cell stack, which is beneficial to more sufficient electrochemical reactions of the fuel cell. Description of the Drawings

[0022] In order to further clearly elaborate the structure and working principle of the compact medium-temperature fuel cell jet engine multi-modal split hybrid propulsion system of the present invention, the present invention will be described in detail below in conjunction with the drawings and specific implementation examples. Please refer to the drawings:

[0023] Figure 1 is the overall structure schematic diagram of the present invention.

[0024] Figure 2 is the cross-sectional schematic diagram of the high-temperature proton exchange membrane fuel cell described in the present invention.

[0025] In the figure: 1 - inner housing; 2 - outer housing; 3 - intake duct; 4 - fan; 5 - low-pressure compressor; 6 - connecting shaft; 7 - bypass duct; 8 - motor; 9 - bevel gear; 10 - first delivery pipeline; 11 - second delivery pipeline; 12 - hydrogen-rich combustion chamber; 13 - third delivery pipeline; 14 - high-temperature proton exchange membrane fuel cell stack; 15 - fourth delivery pipeline; 16 - electric wire; 17 - DC conversion device; 18 - clutch; 19 - fifth delivery pipeline; 20 - combustion chamber; 21 - lubricating oil pump; 22 - low-pressure turbine; 23 - tail nozzle; 24 - vertical connecting shaft. Detailed Description of the Invention

[0026] In order to fully understand the above technical solution, the following will be elaborated in detail in conjunction with the drawings of the specification and its implementation details. It should be clear that the described embodiments are only a part of the examples of the present invention, not all of them. Based on these examples, other implementation manners that can be deduced by those skilled in the art without creative changes belong to the protection scope of the present invention.

[0027] In order to deeply understand the technical key points of the present invention, several embodiments thereof will be analyzed in detail below. These examples are intended to demonstrate the practicability and operability of the present invention, rather than limiting its application scope. Those skilled in the art can explore more forms of embodiments with creativity on the basis of fully understanding the present invention, and these new forms also belong to the protection scope of the present invention.

[0028] The attached drawings in the specification are intended to visually display the technical content of the present invention and help professionals better grasp the key points. The sizes and information of these figures should not be regarded as limitations on the scope of implementation, but rather as tools to assist understanding. Any technically feasible improvements, adjustments, or optimizations, as long as they do not change the core functions and purposes of the present invention, should be considered within the protection scope of the present invention.

[0029] It should be noted that in the embodiments of the present invention, the terms used are intended to describe specific embodiments and not to limit them. The singular forms of "a", "the", and "said" also include the plural forms unless the context clearly indicates otherwise. In addition, the term "a plurality of" generally means at least two.

[0030] In addition, it should be noted that the term "comprising", "including", or any variant thereof is intended to express a non-exclusive inclusion relationship. This means that a product or device containing a series of elements not only contains these explicitly listed elements, but may also contain other elements not explicitly listed, or elements inherent in the product or device. Without further limitations, an element defined by "comprising one..." does not exclude the possibility of the existence of other identical elements in the product or device containing this element.

[0031] Referring to Figure 1 To explain the specific situation of this embodiment, a compact medium-temperature fuel cell jet engine multimodal split hybrid propulsion system described in this embodiment includes a multi-gas dynamic delivery pipeline system, a vertical connecting shaft 24, an inner housing 1, an outer housing 2, and an air intake duct 3, a fan 4, a low-pressure compressor 5, a connecting shaft 6, an outer bypass duct 7, a hydrogen-rich combustion chamber 12, a combustion chamber 20, an electric motor system, a high-temperature proton exchange membrane fuel cell 14, a DC conversion device 17, a low-pressure turbine 22, a tail nozzle 23, and a lubricating oil circuit system provided in the inner housing 1;

[0032] The inner housing 1 is fixed within the outer housing 2 by fixing supports to form a closed engine core structure. The air intake duct is located at the front end of the inner housing and is used to guide air into the low-pressure compressor. The outer bypass duct 7 is located behind the fan 4 and is used to guide the outer bypass airflow to improve the engine efficiency. The low-pressure turbine 22 and the tail nozzle 23 are located at the rear end of the inner housing 1 and are used to guide the exhausted combustion gases to generate thrust.

[0033] The connecting shaft 6 runs through the inner housing 1 and adopts a parallel dual-axis design. The flexible transmission and distribution of power are achieved by using bevel gears 9 and a clutch 18, supporting two working modes to drive the fan: the shaft drive mode and the electric drive mode. The parallel dual-axis structure includes shafts 1 and 2 arranged in parallel; the low-pressure compressor 5, combustion chambers 12, 20, high-temperature proton exchange membrane fuel cell, low-pressure turbine 22 and tail nozzle 23 are connected through shaft 1; the fan 4 and the motor 8 are connected through shaft 2. The shafts 1 and 2 adopt a parallel dual-axis design, and the combination of the vertical connecting shaft 24, bevel gears 9 and the clutch 18 is cleverly used to achieve flexible power allocation and transmission between the two parallel shafts. Particularly importantly, the power transmission between shaft 1 and shaft 2 is unidirectional, that is, shaft 1 does not transmit power to shaft 2. Such a design ensures that the engine can switch freely between the dual-mode working modes according to actual needs.

[0034] In this implementation scheme, after the air is introduced through the air inlet duct, it is first preliminarily compressed by the low-pressure compressor 5. Subsequently, the compressed air is divided into three parts and enters the multi-gas dynamic conveying pipeline system.

[0035] The multi-gas dynamic conveying pipeline system includes a first conveying pipeline 10, a second conveying pipeline 11, a third conveying pipeline 13, a fourth conveying pipeline 15, and a fifth conveying pipeline 19. Among them, the first conveying pipeline 10, the second conveying pipeline 11 and the third conveying pipeline 13 are input pipelines, and the fourth conveying pipeline 15 and the fifth conveying pipeline 19 are output pipelines. The first part of the gas enters the second conveying pipeline 11 and is directly conveyed to the cathode of the high-temperature proton exchange membrane fuel cell 14 to provide raw materials for the electrochemical reaction; the second part of the gas is compressed and then guided to the hydrogen-rich combustion chamber 12, where it is mixed with hydrogen and burned. The generated high-temperature gas is mixed with additional hydrogen and heated up, and is conveyed to the anode of the high-temperature proton exchange membrane fuel cell 14 through the third conveying pipeline 13; the third part of the gas that does not participate in combustion enters the first conveying pipeline 10. At the same time, the exhaust gas of the high-temperature proton exchange membrane fuel cell 14 is guided to the combustion chamber 20 through the fourth conveying pipeline 15 and the fifth conveying pipeline 19 for secondary combustion to improve the energy utilization efficiency and generate additional thrust to meet specific operating requirements.

[0036] The lubricating oil circuit system includes a lubricating oil pump 21. Four lubricating oil pumps are arranged on two parallel connecting shafts. An accessory gearbox is fixed to the tail of the inner housing 1, and the accessory gearbox is connected to the engine's lubrication system, ensuring the efficient operation and maintenance of the engine. The core component of the lubricating oil circuit system is the lubricating oil pump 21, which is distributed around to form a circuit. Such a layout is conducive to the gravity flow of the lubricating oil and enables timely circulation through the lubricating oil pump 21, ensuring that the lubricating oil can smoothly flow to all components that need lubrication. The lubricating oil pump 21 drives the lubricating oil to circulate in the entire engine shafting through coordinated work with the accessory gearbox. The accessory gearbox is fixed to the tail of the inner housing 1. It is not only a key node of the lubricating oil circulation system but also an important hub connecting the engine's lubrication system. When the lubricating oil pump is working, it pumps the lubricating oil out of the fuel tank. Through the oil passages inside the gearbox, the lubricating oil is guided to all shaftings of the engine, including shaft 1, shaft 2, and all vertical connecting shafts 24.

[0037] During the process of flowing through the shafting, the lubricating oil first provides lubrication for key components such as the low-pressure compressor 5, high-temperature proton exchange membrane fuel cell 14, low-pressure turbine 22, and tail pipe 23, reducing wear and friction and ensuring the smooth operation of these components. Subsequently, the lubricating oil carries heat and flows to the motor system. Through the stator as a heat exchange device, it conducts heat exchange with the incoming air to achieve effective heat dissipation and protect the motor system from overheating damage. After the lubricating oil completes lubrication and heat dissipation for all components of the engine, it returns to the lubricating oil pump 21 through the oil passages and is pumped into the circulation system again to achieve a closed-loop circulation. This design not only improves the utilization efficiency of the lubricating oil but also reduces the consumption of the lubricating oil and lowers the operating cost.

[0038] The high-temperature proton exchange membrane fuel cell integrates three high-temperature proton exchange membrane fuel cell stacks 14, adopts an elongated structure, and each fuel cell stack is connected in parallel, having a smaller cross-sectional area and being fixed to shaft 1.

[0039] Air enters the engine through the intake duct and is compressed by the low-pressure compressor 5. The compressed air is directly sent to the cathode of the high-temperature proton exchange membrane fuel cell to provide the necessary oxygen for the electrochemical reaction. At the same time, hydrogen burns in the hydrogen-rich combustion chamber 12. After the high-temperature gas generated is mixed with additional hydrogen and heated up, it enters the anode of the high-temperature proton exchange membrane fuel cell. This design allows hydrogen to be utilized in two stages: first as fuel in the combustion chamber and then as a reactant in the fuel cell. Inside the high-temperature proton exchange membrane fuel cell, an electrochemical reaction occurs between hydrogen and oxygen at the anode and cathode, generating water and releasing electrons, thus producing direct current. These direct currents are transmitted through the wire 16 to the motor system to drive the ducted fan 4 to generate thrust. In addition, the exhaust gas of the high-temperature proton exchange membrane fuel cell system and the air that did not participate in combustion are guided to the combustion chamber for secondary combustion. This process not only improves the energy utilization efficiency of hydrogen but also accelerates the ejection through the tail pipe 23 to generate additional thrust. The engine of this embodiment realizes one of the working modes of the ducted fan through the clutch 18 of the control drive system: the shaft drive mode.

[0040] In the above structure, the high-temperature proton exchange membrane fuel cell stack adopts a hollow cylindrical configuration, and its internal structure includes a cathode channel, a membrane channel, and an anode channel. The membrane channel is arranged in the middle position between the cathode channel and the anode channel, forming an efficient sandwich structure. The design of the hollow cylindrical fuel cell stack 14 allows the anode gas and the cathode gas to enter the interior of the fuel cell stack through the spiral channels of the anode and cathode small holes at the edges respectively. The design of the spiral channel also increases the contact area of the gas in the fuel cell stack 14 and prolongs the residence time of the gas in the fuel cell stack. This is conducive to a more complete electrochemical reaction, enabling the fuel cell to convert chemical energy into electrical energy more effectively. This design improves the fuel utilization rate, reduces the operating cost, and helps to improve the thermal efficiency of the engine. During the electrochemical reaction process, hydrogen loses electrons in the anode channel, and the electrons flow through the external circuit to form an electric current, while the hydrogen ions migrate through the membrane channel to the cathode channel, combine with oxygen and electrons to generate water. The electrical energy generated during this process is used to drive the motor, and then drive the ducted fan 4 to generate thrust.

[0041] As another embodiment, the motor system of the present invention adopts a coupled lower structure, in which four motors 8 are connected in sequence through the shaft 2 to form an efficient power transmission chain. The stator is arranged as a heat exchange device at the rear of the fan 4 and directly exchanges heat with the incoming air. The motor system is connected to the mechanical load through an accessory gearbox.

[0042] The motor system receives direct current generated by the high-temperature proton exchange membrane fuel cell stack 14. This direct current is transmitted to the motor system through wire 16 to drive the four motors to rotate in sequence. The rotation of the motors is transmitted to the fan through shaft 2, causing the fan 4 to generate thrust and propel the aircraft forward. The stator, as a heat exchange device, is located behind the fan 4 and is in direct contact with the incoming air. This design utilizes the air flow entering the engine to achieve heat dissipation of the motor. After passing through the fan 4, the kinetic energy and potential energy of the air increase, and at the same time, when passing through the motor system, it helps to carry away the heat generated by the motor 8, achieving cooling through heat exchange and ensuring that the motor 8 operates at an appropriate temperature. The motor system is connected to the mechanical load through an accessory gearbox, which means that the output torque of the motor can be adjusted through the gearbox to adapt to different flight conditions and power requirements. The design of the gearbox allows for precise control of the torque, thereby optimizing the performance and efficiency of the engine. In the dual-mode combined engine, the motor system can work in coordination with the low-pressure turbine in the shaft drive mode or operate independently in the electric drive mode. This flexibility enables the engine to flexibly switch the working mode according to the flight state and power requirements, optimizing performance and efficiency.

[0043] The specific operation process and working principle of a compact medium-temperature fuel cell jet engine multi-mode split hybrid propulsion system according to the present invention are as follows:

[0044] The engine adopts a special parallel dual-axis upper and lower layout design, and realizes flexible distribution and transmission of power through bevel gears and clutches, supporting the shaft drive mode and the electric drive mode. Among them: Shaft 1 is on the upper side, and shaft 2 is on the lower side.

[0045] In the shaft drive mode of shaft 1, after the air enters the compact medium-temperature fuel cell jet engine multi-mode split hybrid propulsion system through the intake duct, it is first compressed by the low-pressure compressor. Subsequently, the compressed air is divided into three parts: The first part is directly guided to the cathode of the high-temperature proton exchange membrane fuel cell for use; the second part enters the combustion chamber, reacts with hydrogen to burn, and after sufficient mixing and temperature increase, is sent to the anode of the high-temperature proton exchange membrane fuel cell; while the third part directly leads to the combustion chamber located behind the high-temperature proton exchange membrane fuel cell for pre-rotating combustion. The high-speed airflow after combustion is ejected backward to generate thrust, and at the same time drives the low-pressure turbine to rotate, driving the front-mounted fan and compressor on the shaft to rotate, allowing more gas to enter, making the combustion more complete, and the operation more stable.

[0046] In the electric drive mode, the high-temperature proton exchange membrane fuel cell on shaft 1 generates direct current, which is transmitted to the motor system through wires. The motor directly drives the large-diameter fan on shaft 2 to rotate, generating a huge thrust in a short time, which solves the problem of lack of power for takeoff to a certain extent. At the same time, it drives shaft 1 to work through a bevel gear clutch, and starts to supply hydrogen and burn to start the main engine on shaft 1 in the stable state, ensuring the stable thrust during cruise.

[0047] The lubricating oil pump draws lubricating oil from the fuel tank and provides lubrication for each shaft system of the engine through the accessory gearbox, reducing wear and friction, and at the same time taking away the heat of the bearings to ensure that the ETG does not overheat. The lubricating oil carries heat during the lubrication process. The lubricating oil of the hydrogen fuel flows to the motor system to lubricate the bearing system of shaft 2. Heat exchange is carried out with the air through the stator as a heat exchange device to achieve heat dissipation. Finally, the iron filings and other wastes in the lubricating oil are screened out through the lubricating oil filter to purify the lubricating oil. After the lubricating oil completes lubrication and heat dissipation, it returns to the lubricating oil pump to achieve a closed-loop cycle.

[0048] The compact medium-temperature fuel cell jet engine multi-modal split hybrid propulsion system of the present invention directly converts the chemical energy of hydrogen and oxygen into electrical energy through a high-temperature proton exchange membrane fuel cell (HT-PEMFC) based on an electrochemical reaction. Specifically, hydrogen undergoes an oxidation reaction at the anode and decomposes into protons (H + ) and electrons (e - ). The protons are transferred to the cathode through the proton exchange membrane, while the electrons flow through the external circuit to form an electric current. At the cathode, oxygen, electrons and protons combine to undergo a reduction reaction to generate water, while releasing electrical energy to directly drive the motor system to achieve the propulsion of the ducted fan. The HT-PEMFC has the characteristics of high efficiency and environmental protection, and its energy conversion efficiency is greatly improved compared with traditional fuels. In addition, the high-temperature proton exchange membrane fuel cell stack adopted in the present invention adopts a special hollow cylindrical configuration and combines a spiral channel design. The internal structure includes a cathode channel, a membrane channel and an anode channel, forming an efficient sandwich structure, further improving the fuel utilization rate, and the emissions are only water without pollution. The high-temperature operating environment of the high-temperature proton exchange membrane fuel cell improves the electrochemical reaction rate of the electrodes, reduces the dependence on precious metal catalysts, and improves the tolerance to impurities in the fuel. The present invention abandons the single-shaft structure of the traditional turbo gas engine and instead adopts a parallel two-shaft design. Through the bevel gear and the clutch of the control drive system, the engine can freely switch between two working modes (shaft drive and electric drive) to achieve the propulsion of the aircraft to adapt to different flight conditions and power requirements. The engine of the present invention also reduces the heat loss during the energy conversion process and improves the thermal efficiency of the engine by canceling the traditional heat exchanger.

[0049] The embodiments described above are only the preferred solutions of the present invention and do not constitute a limitation on the protection scope of the present invention. For any professional person familiar with the technical field, the implementation and application of the present invention have flexibility and allow various changes and adjustments without departing from the core concept and basic principle of the present invention. Therefore, any modification, equivalent replacement or improvement made within the spirit and principle of the present invention shall be regarded as part of the protection scope of the present invention.

Claims

1. A compact medium-temperature fuel cell jet engine multi-mode split hybrid propulsion system, characterized in that: include: A multi-gas dynamic transport pipeline system (the system comprises a first transport pipeline (10), a second transport pipeline (11), a third transport pipeline (13), a fourth transport pipeline (15) and a fifth transport pipeline (19)), a vertical connecting shaft (24), an inner shell (1), an outer shell (2), and an air inlet (3), a fan (4), a low-pressure compressor (5), a connecting shaft (6), an outer duct (7), a hydrogen-rich combustion chamber (12), a combustion chamber (20), an electric motor system, a high-temperature proton exchange membrane fuel cell (14), a DC conversion device (17), a low-pressure turbine (22), a tail nozzle (23), and a lubricating oil circuit system arranged in the inner shell (1); The inner casing (1) is fixed in the outer casing (2) via a fixing support member to form a closed engine core structure; The air inlet (3) is located at the front end of the inner casing (1) and is used to guide air into the low-pressure compressor (5). The air enters the engine through the air inlet (3) and is compressed by the low-pressure compressor (5) before being divided into three paths. The first gas enters the second delivery pipeline (11) and is directly delivered to the cathode of the high-temperature proton exchange membrane fuel cell (14); The second gas is compressed and guided to a hydrogen-rich combustion chamber (12), mixed with hydrogen and then burned, and the generated high-temperature gas is mixed with additional hydrogen to increase its temperature and is transported to the anode of a high-temperature proton exchange membrane fuel cell (14) through a third transport pipeline (13); The third gas not involved in combustion enters the first delivery pipeline (10), and at the same time, the tail gas of the high-temperature proton exchange membrane fuel cell (14) is guided to the combustion chamber (20) through the fourth delivery pipeline (15) and the fifth delivery pipeline (19) for secondary combustion; The outer duct (7) is located at the rear of the fan (4) and is used to guide the outer duct airflow; The low-pressure turbine tail nozzle (23) is located at the rear end of the inner casing (1) and is used to guide the exhaust of the combusted gas to generate thrust; The connecting shaft (6) passes through the inner casing (1), and the low-pressure compressor (5), the hydrogen-rich combustion chamber (12), the combustion chamber (20), the high-temperature proton membrane exchange battery, the low-pressure turbine (22) and the tail nozzle (23) are connected through the shaft 1; the fan (4) and the motor (8) are connected through the shaft 2. The connecting shaft (6) adopts a parallel double-shaft design, and the upper and lower parallel shafts are connected through a vertical connecting shaft (24), a bevel gear (9) and a clutch (18) to achieve flexible power transmission and distribution; wherein, the shaft 1 does not transmit power to the shaft 2, and supports a dual-mode working mode.

2. The compact medium-temperature fuel cell jet engine multi-mode split hybrid propulsion system according to claim 1, characterized in that: The high temperature proton exchange membrane fuel cell integrates three high temperature proton exchange membrane fuel cell stacks (14) and adopts a slender structure. The three battery stacks are connected in parallel, have a small cross-sectional area, and are fixed on the shaft 1. Each high temperature proton exchange membrane fuel cell stack (14) adopts a special hollow cylindrical structure, and its internal structure includes a cathode channel, a membrane channel and an anode channel. The membrane channel is arranged in the middle of the cathode channel and the anode channel to form an efficient sandwich structure. Each channel adopts a spiral design to increase the contact area and prolong the reaction time. The air compressed by the low-pressure compressor (5) simultaneously enters the cathode channels of three high-temperature proton exchange membrane fuel cell stacks (14) through the second delivery pipeline (11); the gas after combustion in the hydrogen-rich combustion chamber simultaneously enters the anode channels of the high-temperature proton exchange membrane fuel cell (14) through the third delivery pipeline (13); after the gas is fully reacted in the three high-temperature proton exchange membrane fuel cell stacks (14), it is transported to the combustion chamber (20) at the rear of the high-temperature proton exchange membrane fuel cell through the fourth delivery pipeline (15) connected to the cathode channel and the fifth delivery pipeline (19) connected to the anode channel.

3. The compact medium-temperature fuel cell jet engine multi-mode split hybrid propulsion system according to claim 1, characterized in that: The combustion chamber (20) is located at the rear of the high-temperature proton exchange membrane fuel cell (14), and three key gases enter the combustion chamber through specific delivery paths, namely, the gas delivered via the first delivery pipeline (10), the gas guided through the fourth delivery pipeline (15), and the gas provided by the fifth delivery pipeline (19).

4. The compact medium-temperature fuel cell jet engine multi-mode split hybrid propulsion system according to claim 1, characterized in that: The hydrogen-rich combustion chamber (12) is distributed in an annular shape, and a portion of the air enters the hydrogen-rich combustion chamber (12) to react with the hydrogen, thereby increasing the temperature of the hydrogen to meet the oxygen inlet conditions of the fuel cell.

5. The compact medium-temperature fuel cell jet engine multi-mode split hybrid propulsion system according to claim 1, characterized in that: The motor system adopts a coupled lower structure, wherein four motors (8) are connected via shaft 2. The stator is arranged at the rear of the fan as a heat exchange device to exchange heat with the incoming air. The motor system is connected to the mechanical load via an accessory gearbox.

6. The compact medium-temperature fuel cell jet engine multi-mode split hybrid propulsion system according to claim 1, characterized in that: The lubricating oil circuit system comprises a lubricating oil pump (21); four lubricating oil pumps are arranged on two parallel connecting shafts (6); an accessory gear box is fixed to the rear of the inner housing (1); the accessory gear box is connected to the lubrication system of the engine; all shaft systems are lubricated with oil, and the lubricating oil pump then pumps up the lubricating oil for recycling.

Images