Compact medium temperature fuel cell ramjet multimode split-body hybrid propulsion system

Abstract

The application provides a compact medium-temperature fuel cell jet engine multi-mode split hybrid propulsion system, aiming to improve the efficiency of aircraft propulsion system and reduce environmental pollution. Compared with traditional engines, the engine adopts a parallel double-shaft design, realizes flexible power transmission and distribution through bevel gears and clutches, supports two working modes to drive the fan: shaft driving mode and electric driving mode. In the medium-temperature mode, the engine discards the high-pressure compressor, and the air treated by the low-pressure compressor is directly sent to the fuel cell cathode, and the mixed gas after combustion of hydrogen and oxygen is heated and enters the anode. The application also considers the configuration of the stack, adopts a hollow cylindrical configuration to improve the reaction area and improve the heat management. At the same time, the slender structure optimizes the space utilization, so that the overall layout is more compact. The coupling type lower structure allows the integration of multiple motors, which is convenient for heat dissipation and maintenance. The shell cover provides protection for the internal structure, enhances the durability and safety. Through these innovative designs, the engine of the application has significant advantages in improving thermal efficiency, reducing fuel consumption and reducing NO x emissions, which is of great significance to environmental protection and the development of aviation propulsion technology.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aviation propeller, in particular, to a compact medium-temperature fuel cell jet engine multi-modal split hybrid propulsion system. BACKGROUND

[0002] With the increasing awareness of environmental protection and the increasingly severe energy crisis, the aviation industry is facing the dual challenges of reducing fuel consumption and reducing harmful emissions. The aviation propulsion system, as the core component of the aircraft, its performance is directly related to the fuel economy and environmental level of the aircraft. According to statistics, the carbon emissions of the aviation industry account for 2% to 3% of the total global emissions. Therefore, it is of great significance to develop new high-efficiency and low-emission aviation propulsion systems.

[0003] Traditional aviation engines mainly rely on fossil fuels, and through the combustion process, the chemical energy of the fuel is converted into mechanical energy to generate thrust. However, this conversion process is accompanied by significant energy loss, resulting in an overall efficiency of only about 35% at a relatively low level. In contrast, proton exchange membrane fuel cells (PEMFC) exhibit a clear efficiency advantage, with an energy conversion efficiency of about 50%. Such fuel cells not only can effectively convert the chemical energy of fuel into electrical energy, thereby improving the efficiency of the entire system, but also have high environmental protection characteristics, and do not produce a large amount of nitrogen oxides (NOx) and other greenhouse gases during operation, causing less negative impact on the environment, and are of great significance for alleviating the current serious exhaust 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 developed increasingly stringent environmental regulations. In this context, 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 (PEMFC) are considered a strong candidate for future aviation propulsion systems due to their moderate operating temperature, fast startup, small size, and excellent thermal management capabilities. However, the application of fuel cell technology in 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 with 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 and others focus on the development and application of ultra-light and high-efficiency heat exchangers for aircraft engines, and their research provides new ideas and directions for aircraft engine heat exchanger design. Wenqi, Pei Xinyan and others evaluate the application effect of air-oil heat exchangers in variable cycle engines by establishing a performance simulation model. Xu Guoqiang and others are committed to the thermal protection research of high-temperature components and have made important achievements in the field of aircraft heat exchangers. In addition, Zhu Kun and others summarize the coking heat exchange of aviation kerosene under supercritical pressure. And Suresh and others optimize the performance of small-sized air-oil heat exchangers through experiments and simulations. These researches show the research progress in the field of aircraft engine heat exchangers, and also point out the problem of increasing the weight and complexity of the system by heat exchangers in the prior art. In the international community, NASA and industry partners in the United States jointly developed thin-walled channels, which demonstrated possible design options, various machining path strategies and determined process geometry limitations, further promoting the development of heat exchanger technology. Dr. Ali Nabavi and others made in-depth research on computational fluid dynamics (CFD) modeling of heat exchangers, and Xuan Tao and others studied the heat transfer and frictional pressure drop prediction model of ammonia condensation in plate heat exchangers. German research institutions are also exploring new heat exchanger technologies, such as the research of Lei Yong and others mainly focusing on nano-structured heat exchangers to further improve heat transfer efficiency.

[0006] However, most of the previous researches focus on the optimization of heat exchangers, without in-depth exploration of heat exchanger-free designs. Therefore, the present invention studies a heat exchanger-free fuel cell turbine dual-mode combined engine technology, which eliminates the traditional heat exchanger, reduces heat loss in the energy conversion process, improves the thermal efficiency of the engine, and simplifies the system structure, reduces the 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 difficulties and achieve high efficiency, environmental protection and economy of the aircraft propulsion system is a key problem that needs to be broken through in the current field of aircraft propulsion technology. SUMMARY

[0008] Therefore, 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 introduces high-temperature proton exchange membrane fuel cell packs, and realizes efficient propulsion through dual modes of electric drive and shaft drive.

[0009] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme: the compact medium-temperature fuel cell jet engine multi-mode split hybrid propulsion system of the application comprises a multi-gas dynamic delivery 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 direct current conversion device, a low-pressure turbine, a tail nozzle and a lubricating oil circuit system arranged in the inner shell.

[0010] The inner shell is fixed in the outer shell by a fixed support to form a closed engine core structure.

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

[0012] The connecting shaft penetrates the inner shell and adopts a parallel double-shaft design. The power is flexibly transmitted and distributed by using bevel gears and clutches to support two working modes to drive the fan, i.e., shaft driving mode and electric driving mode.

[0013] More specifically, the parallel double-shaft structure comprises shaft I and shaft II. The low-pressure compressor, the combustion chamber, the low-temperature pump, the medium-temperature proton membrane exchange cell, the low-pressure turbine and the tail nozzle are connected by shaft I. The fan and the electric motor are connected by shaft II. Shaft I and shaft II adopt a parallel double-shaft design. The combination of the vertical connecting shaft, the bevel gear and the clutch is used to flexibly distribute and transmit the power between the two parallel shafts. More importantly, the power transmission between shaft I and shaft II is unidirectional. Such a design ensures that the engine can be switched between the two modes of operation according to actual needs.

[0014] Furthermore, the lubricating oil circuit system comprises a lubricating oil pump. The lubricating oil pump is arranged on the parallel double shafts. An accessory gear box is fixed at the tail of the inner shell. The accessory gear box is connected with the lubricating system of the engine. All shafts are lubricated by oil. The lubricating oil pump pumps the lubricating oil up for recycling.

[0015] Furthermore, the high-temperature proton exchange membrane fuel cell integrates three high-temperature proton exchange membrane fuel cell stacks. The high-temperature proton exchange membrane fuel cell adopts an elongated structure. Each cell stack is connected in parallel and has a small cross-sectional area and is fixed on shaft I. 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. Hydrogen and oxygen are burned in the combustion chamber and then mixed with additional hydrogen to be heated and enter the anode of the high-temperature proton exchange membrane fuel cell. In this electrochemical reaction process, the cell stack generates direct current.

[0016] Further, the motor system adopts a coupling type lower structure, in which the four motors are connected through shaft II. The stator and heat exchange device are arranged at the rear of the fan to exchange heat with the incoming air, thereby achieving effective heat dissipation. The motor system is connected with the mechanical load through an accessory gear box.

[0017] In particular, the compact intermediate-temperature fuel cell jet engine multi-modal split hybrid propulsion system has the following advantages:

[0018] (1) Compared with the traditional aviation gas turbine engine, the compact intermediate-temperature fuel cell jet engine multi-modal split hybrid propulsion system adopts a special parallel double-shaft design, which is connected through the ingenious combination of a vertical connecting shaft, a bevel gear and a clutch, thereby realizing flexible distribution and transmission of power between the two parallel shafts. This design enables the ducted fan to have two working modes, and the engine can freely switch between the electric drive mode and the shaft drive mode according to the flight conditions, thereby optimizing fuel consumption and improving the overall performance of the engine.

[0019] (2) The compact intermediate-temperature fuel cell jet engine multi-modal split hybrid propulsion system adopts a design without a heat exchanger, thereby reducing the need for a traditional heat exchanger, reducing heat loss during energy conversion, and improving the overall thermal efficiency of the engine.

[0020] (3) The compact intermediate-temperature fuel cell jet engine multi-modal split hybrid propulsion system adopts high-temperature proton exchange membrane fuel cell technology, thereby reducing the dependence on fossil fuels compared with the traditional aviation gas turbine engine.

[0021] (4) The compact intermediate-temperature fuel cell jet engine multi-modal split hybrid propulsion system adopts a hollow cylindrical design for the fuel cell stack, which utilizes the small hole spiral channels at the edge of the hollow cylindrical fuel cell stack to introduce anode gas and cathode gas. 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 intermediate-temperature fuel cell stack, which is beneficial to more complete electrochemical reaction of the fuel cell. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to further clearly illustrate the structure and working principle of the compact intermediate-temperature fuel cell jet engine multi-modal split hybrid propulsion system of the present application, the following will combine the drawings and specific implementation examples to make a detailed description of the present application. Please refer to the drawings:

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

[0024] Figure 2 Figure 1 is a schematic diagram of the cross section of the high-temperature proton exchange membrane fuel cell according to the present application.

[0025] Figure 1 is a schematic diagram of the cross section of the high-temperature proton exchange membrane fuel cell according to the present application. DETAILED DESCRIPTION

[0026] In order to fully understand the above technical solutions, the following will be combined with the description of the drawings and its implementation details, and will be described in detail. It should be clear that the embodiments mentioned are only a part of the examples of the present application, rather than all. Based on these examples, other embodiments that can be deduced by those skilled in the art without creative changes are all within the protection scope of the present application.

[0027] In order to deeply understand the technical points of the present application, the following will analyze several embodiments thereof in detail. These examples are intended to demonstrate the practicability and operability of the present application, rather than limit its application scope. Based on a full understanding of the present application, the skilled person can exercise creativity to explore more forms of embodiments, and these new forms also belong to the protection scope of the present application.

[0028] The drawings in the specification are intended to visually demonstrate the technical content of the present application, and help the professionals to better grasp the key points. The sizes and information of these figures should not be regarded as a limitation on the scope of implementation, but as a tool to assist understanding. Any technically feasible improvement, adjustment or optimization, as long as it does not change the core function and purpose of the present application, should be regarded as within the protection scope of the present application.

[0029] It should be noted that in the embodiments of the present application, the terms used are intended to describe specific embodiments, rather than limit them. The singular forms "a", "said" and "the" also include the plural forms, unless the context clearly indicates otherwise. In addition, the word "plurality" generally refers to at least two.

[0030] Furthermore, it is to be understood that the terms "including", "comprising", or any variation thereof, are intended to cover a non-exclusive inclusion. This means that a product or a process that includes a list of elements can not only include those elements but can also include other elements not expressly listed or inherent to such product or process. An element proceeded by "comprises a..." does not, without more constraints, preclude the existence of additional identical elements in the process or product that contains the identified element.

[0031] Referring to Figure 1 To illustrate the specific circumstances of the present embodiment, the compact medium-temperature fuel cell jet engine multi-modal split hybrid propulsion system described in the present embodiment includes a multi-gas dynamic delivery pipeline system, a vertical connecting shaft 24, an inner casing 1, an outer casing 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, a direct current conversion device 17, a low-pressure turbine 22, a tail nozzle 23, and a lubricating oil circuit system arranged in the inner casing 1.

[0032] The inner casing 1 is fixed in the outer casing 2 by a fixed support, forming a closed engine core structure. The air inlet is located at the front end of the inner casing, used to guide air into the low-pressure compressor. The outer duct 7 is located at the rear of the fan 4, used to guide the outer duct airflow, improving engine efficiency. The low-pressure turbine 22 and the tail nozzle 23 are located at the rear end of the inner casing 1, used to guide the exhaust gas after combustion to generate thrust.

[0033] The connecting shaft 6 penetrates the inner casing 1, adopts a parallel double-shaft design, and uses bevel gears 9 and clutches 18 to achieve flexible power transmission and distribution, supporting two working modes to drive the fan: shaft driving mode and electric driving mode. The parallel double-shaft structure includes parallelly arranged shaft I and shaft II; the low-pressure compressor 5, the combustion chamber 12, 20, the high-temperature proton exchange membrane fuel cell, the low-pressure turbine 22, and the tail nozzle 23 are connected through the shaft I; the fan 4 and the electric motor 8 are connected through the shaft II. The shaft I and the shaft II adopt a parallel double-shaft design, which ingeniously uses the combination of the vertical connecting shaft 24, the bevel gear 9, and the clutch 18 to achieve flexible power allocation and transmission between the two parallel shafts. More importantly, the power transmission between the shaft I and the shaft II is unidirectional, which ensures that the engine can switch between the two modes of operation according to actual needs.

[0034] In the present embodiment, after air is introduced through the air inlet, it is first compressed by the low-pressure compressor 5. Then, the compressed air is distributed into three parts and enters the multi-gas dynamic delivery pipeline system.

[0035] The multi-gas dynamic delivery pipeline system includes a first delivery pipeline 10, a second delivery pipeline 11, a third delivery pipeline 13, a fourth delivery pipeline 15, and a fifth delivery pipeline 19. The first delivery pipeline 10, the second delivery pipeline 11, and the third delivery pipeline 13 are input pipelines, and the fourth delivery pipeline 15 and the fifth delivery pipeline 19 are output pipelines. A first portion of the gas enters the second delivery pipeline 11 and is directly delivered to the cathode of the high-temperature proton exchange membrane fuel cell to provide raw materials for the electrochemical reaction; a second portion of the gas is compressed and introduced into the hydrogen-rich combustion chamber 12, mixed with hydrogen, and combusted to generate high-temperature gas, which is mixed with additional hydrogen and delivered to the anode of the high-temperature proton exchange membrane fuel cell through the third delivery pipeline 13; a third portion of the gas that does not participate in combustion enters the first delivery pipeline 10, and the exhaust gas from the high-temperature proton exchange membrane fuel cell is introduced into the combustion chamber 20 through the fourth delivery pipeline 15 and the fifth delivery pipeline 19 for secondary combustion to improve energy utilization efficiency and generate additional thrust to meet specific operating requirements.

[0036] The lubricating oil circuit system includes a lubricating oil pump 21, wherein four lubricating oil pumps are arranged on two parallel connecting shafts, and an accessory gear box is fixed at the tail of the inner casing 1, which is connected with the lubricating system of the engine to ensure 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 lubricating oil and timely circulation through the lubricating oil pump 21 to ensure that the lubricating oil can smoothly flow to each component that needs lubrication. The lubricating oil pump 21 drives the lubricating oil to circulate in the entire engine shaft system through cooperation with the accessory gear box. The accessory gear box is fixed at the tail of the inner casing 1, which is not only a key node of the lubricating oil circulation system but also an important hub connecting the engine lubricating system. When the lubricating oil pump is working, it pumps lubricating oil from the oil tank through the oil channel inside the gear box, and the lubricating oil is guided to each shaft system of the engine, including shaft I, shaft II, and all vertical connecting shafts 24.

[0037] During the flow through the shaft system, the lubricating oil first provides lubrication for key components such as the low-pressure compressor 5, the high-temperature proton exchange membrane fuel cell, the low-pressure turbine 22, and the tail nozzle 23, reducing wear and friction and ensuring smooth operation of these components. Subsequently, the lubricating oil carries heat to the motor system and exchanges heat with the incoming air through the stator as a heat exchange device, achieving effective heat dissipation and protecting the motor system from overheating damage. After completing lubrication and heat dissipation for each component of the engine, the lubricating oil returns to the lubricating oil pump 21 through the oil channel and is pumped again to the circulation system, realizing closed-loop circulation. This design not only improves the utilization efficiency of lubricating oil but also reduces the consumption of lubricating oil and operating costs.

[0038] The high temperature proton exchange membrane fuel cell engine integrates three high temperature proton exchange membrane fuel cell stacks 14 in an elongated configuration, each stack connected in parallel, with a small cross-sectional area, and fixed to shaft I.

[0039] Air enters the engine through the air inlet 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. Meanwhile, hydrogen is burned in the hydrogen-rich combustion chamber 12, and the high-temperature gas produced by the combustion of hydrogen is mixed with additional hydrogen to increase the temperature before entering the anode of the high temperature proton exchange membrane fuel cell. This design allows hydrogen to be used 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, hydrogen and oxygen undergo an electrochemical reaction between the anode and the cathode, generating water and releasing electrons, thereby generating direct current. These direct currents are transmitted to the motor system through the wires 16 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 does not participate in the 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 nozzle 23, generating additional thrust. The engine of the present embodiment realizes one of the ducted fan working modes: shaft drive mode, by controlling the clutch 18 of the transmission system.

[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, and the membrane channel is arranged between the cathode channel and the anode channel. An efficient sandwich structure is formed. The design of the hollow cylindrical fuel cell stack 14 allows the anode gas and the cathode gas to enter the inside of the stack through the anode and cathode small hole spiral channels at the edge, 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 stack. This is conducive to more complete electrochemical reaction, so that the fuel cell can more effectively convert chemical energy into electrical energy. This design improves the utilization of fuel, reduces operating costs, and helps to improve the thermal efficiency of the engine. During the electrochemical reaction, hydrogen loses electrons in the anode channel, electrons flow through the external circuit to form current, and hydrogen ions migrate to the cathode channel through the membrane channel to combine with oxygen and electrons to form water. The electrical energy generated in this process is used to drive the motor, which in turn drives the ducted fan 4 to generate thrust.

[0041] As an additional embodiment, the electric motor system of the present invention employs a coupled lower structure, in which the four electric motors 8 are connected in series through shaft II, forming an efficient power transmission chain. The stator is placed as a heat exchange device behind the fan 4, directly exchanging heat with the incoming air. The electric motor system is connected to the mechanical load through an accessory gearbox.

[0042] The electric motor system receives direct current generated from the high-temperature proton exchange membrane fuel cell stack 14. These direct currents are transmitted to the electric motor system through wires 16, driving the four electric motors to rotate in series. The rotation of the electric motors is transmitted to the fan through shaft II, causing the fan 4 to generate thrust, propelling the aircraft forward. The stator, as a heat exchange device, is located behind the fan 4, directly contacting the incoming air. This design utilizes the airflow entering the engine to achieve heat dissipation of the electric motors. After passing through the fan 4, the air increases its kinetic and potential energy, and while passing through the electric motor system, it helps to carry away the heat generated by the electric motors 8, achieving cooling through heat exchange, ensuring that the electric motors 8 operate at an appropriate temperature. The electric motor system is connected to the mechanical load through an accessory gearbox, which means that the output torque of the electric motors can be adjusted through the gearbox to adapt to different flight conditions and power requirements. The design of the gearbox allows precise control of the torque, thereby optimizing the performance and efficiency of the engine. In the dual-mode combined engine, the electric motor system can work in tandem with the low-pressure turbine in shaft drive mode or operate independently in electric drive mode. This flexibility allows the engine to switch between modes according to flight conditions and power requirements, optimizing performance and efficiency.

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

[0044] The engine adopts a special parallel double-shaft up-down layout design, achieving flexible power distribution and transmission through bevel gears and clutches, supporting shaft drive mode and electric drive mode. Among them: shaft I is on the top, and shaft II is on the bottom.

[0045] In shaft I shaft drive mode, after the air enters the compact medium-temperature fuel cell jet engine multi-modal split hybrid propulsion system through the air inlet, 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 and reacts with hydrogen gas, and after sufficient mixing and heating, it is sent to the anode of the high-temperature proton exchange membrane fuel cell; while the third part is directly guided to the combustion chamber behind the high-temperature proton exchange membrane fuel cell for pre-rotation combustion. The high-speed airflow after combustion is ejected backward to generate thrust, while driving 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 stable.

[0046] In the electric drive mode, the shaft I high-temperature proton exchange membrane fuel cell generates direct current, which is transmitted to the motor system through the wire, and the motor directly drives the large-diameter fan of the shaft II to rotate, thereby generating a huge thrust in a short time, and the problem of power shortage in take-off is solved to a certain extent.

[0047] The lubricating oil pump draws lubricating oil from the oil tank, provides lubrication for each shaft system of the engine through the accessory gear box, reduces wear and friction, and takes away the heat of the bearing to ensure that the ETG does not overheat. The lubricating oil carries heat during the lubrication process, flows to the motor system through the lubricating oil of the hydrogen fuel, lubricates the bearing system of the shaft II. The stator is used as a heat exchange device to exchange heat with air to achieve heat dissipation. Finally, the iron filings and other waste in the lubricating oil are screened out through the lubricating oil filter to purify the lubricating oil. After completing the lubrication and heat dissipation, the lubricating oil returns to the lubricating oil pump to realize closed-loop circulation.

[0048] The compact medium-temperature fuel cell jet engine multi-modal split hybrid propulsion system of the application converts the chemical energy of hydrogen and oxygen into electrical energy through high-temperature proton exchange membrane fuel cells (HT-PEMFC) based on electrochemical reactions. Specifically, hydrogen undergoes an oxidation reaction at the anode, decomposing 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. In 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 and achieve propulsion of the ducted fan. The HT-PEMFC has high efficiency and environmental protection characteristics, and its energy conversion efficiency is greatly improved compared to traditional fuel. In addition, the high-temperature proton exchange membrane fuel cell stack used in the application adopts a special hollow cylindrical configuration combined with a spiral channel design, and the internal structure includes a cathode channel, a membrane channel and an anode channel, forming an efficient sandwich structure to further improve the utilization rate of fuel, and the only emission is water without pollution. The high-temperature operating environment of the high-temperature proton exchange membrane fuel cell improves the electrochemical reaction rate of the electrode, reduces the dependence on noble metal catalysts, and improves the tolerance to impurities in the fuel. The application discards the traditional single-shaft structure of the turbine gas engine and adopts a parallel double-shaft design. Through the cone gear and the clutch of the control transmission system, the engine can freely switch between two working modes (shaft drive and electric drive) to achieve propulsion of the aircraft to adapt to different flight conditions and power requirements. The engine of the application also eliminates the traditional heat exchanger, reduces heat loss in the energy conversion process, and improves the thermal efficiency of the engine.

[0049] The above described embodiments are only the preferred schemes of the present application, and do not constitute limitation to the protection scope of the present application. The implementation and application of the present application has flexibility for any skilled person in the art, and allows various changes and adjustments without deviating from the core concept and basic principles of the present application. Therefore, any modification, equivalent replacement or improvement within the spirit and principle of the present application shall be considered as part of the protection scope of the present application.

Claims

1. A compact, intermediate-temperature fuel cell jet engine multimodal split-type hybrid propulsion system, characterized in that, include: A multi-gas dynamic delivery pipeline system, the system comprising a first delivery pipeline (10), a second delivery pipeline (11), a third delivery pipeline (13), a fourth delivery pipeline (15) and a fifth delivery pipeline (19), a vertical connecting shaft (24), an inner shell (1), an outer shell (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, a DC-DC converter (17), a low-pressure turbine (22), a tail nozzle (23), and a lubricating oil circuit system; The inner shell (1) is fixed inside the outer shell (2) by a fixed support member to form a closed engine core structure; The intake duct (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 intake duct (3) and is compressed by the low-pressure compressor (5) and then 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; After the second gas is compressed, it is guided to the hydrogen-rich combustion chamber (12), where it is mixed with hydrogen and burned. The resulting high-temperature gas is mixed with additional hydrogen and heated up. It is then transported to the anode of the high-temperature proton exchange membrane fuel cell via the third delivery pipeline (13). The gas that did not participate in combustion in the third channel enters the first delivery pipeline (10). At the same time, the exhaust gas of the high-temperature proton exchange membrane fuel cell is guided to the combustion chamber (20) through the fourth delivery pipeline (15) and the fifth delivery pipeline (19) for secondary combustion. The duct (7) is located at the rear of the fan (4) and is used to guide the airflow of the duct. The low-pressure turbine exhaust 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 shell (1) and adopts a parallel dual-shaft design, including shaft I and shaft II; the low-pressure compressor (5), hydrogen-rich combustion chamber (12), combustion chamber (20), high-temperature proton exchange membrane battery, low-pressure turbine (22) and tail nozzle (23) are connected through shaft I; the fan (4) and motor (8) are connected through shaft II; shaft I and shaft II are parallel to each other and are connected through vertical connecting shaft (24), bevel gear (9) and clutch (18), supporting dual-mode operation and realizing flexible power transmission and distribution. In shaft drive mode, hybrid drive is adopted. The mechanical work of shaft I is transmitted to shaft II through bevel gear (9) via vertical connecting shaft (24). At the same time, the electrical energy output by the high-temperature proton exchange membrane fuel cell drives the motor (8) through DC conversion device (17). The motor (8) and shaft I drive shaft II to rotate together to realize hybrid drive of fan (4); in electric drive mode, shaft II is only driven by motor (8) to realize pure electric drive of fan (4).

2. The compact, intermediate-temperature fuel cell jet engine multimodal split-type 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), adopting a slender structure. The three stacks are connected in parallel, have a small cross-sectional area, and are fixed on shaft I. 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 located in the middle of the cathode channel and the anode channel, forming a highly efficient sandwich structure. Each channel adopts a spiral design, which increases the contact area and prolongs the reaction time. The air compressed by the low-pressure compressor (5) enters the cathode channels of the three high-temperature proton exchange membrane fuel cell stacks (14) simultaneously through the second delivery pipeline (11); the gas after combustion in the hydrogen-rich combustion chamber enters the anode channel of the high-temperature proton exchange membrane fuel cell simultaneously through the third delivery pipeline (13); after the gas has 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, respectively.

3. The compact, intermediate-temperature fuel cell jet engine multimodal split-type 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. Three key gases enter the combustion chamber through specific delivery paths: gas delivered via the first delivery pipeline (10), gas guided via the fourth delivery pipeline (15), and gas supplied by the fifth delivery pipeline (19).

4. The compact, intermediate-temperature fuel cell jet engine multimodal split-type hybrid propulsion system according to claim 1, characterized in that: The hydrogen-rich combustion chamber (12) is arranged in a ring shape. A portion of the air enters the hydrogen-rich combustion chamber (12) and reacts with hydrogen to raise the temperature of the hydrogen, thereby meeting the oxygen inlet conditions of the fuel cell.

5. A compact, intermediate-temperature fuel cell jet engine multimodal split-type hybrid propulsion system according to claim 1, characterized in that: The electric motor system adopts a coupled lower structure, in which four electric motors (8) are connected by shaft II; the stator is placed at the rear of the fan as a heat exchange device to exchange heat with the incoming air; the electric motor system is connected to the mechanical load through an accessory gearbox.

6. The compact intermediate-temperature fuel cell jet engine multimodal split-type hybrid propulsion system according to claim 1, characterized in that: The lubricating oil circuit system includes a lubricating oil pump (21); four lubricating oil pumps are installed on two parallel connecting shafts (6), and an accessory gearbox is fixed at the tail of the inner housing (1). The accessory gearbox is connected to the lubrication system of the engine. All shafts are lubricated by oil, and the lubricating oil pumps then draw the lubricating oil up for circulation.

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