Dual-fuel aircraft combined power system and operation method

Abstract

The invention belongs to the technical field of aviation second power systems, and provides a dual-fuel aircraft combined power system which comprises an air compressor, a heat regenerator, a main combustion chamber, a gas turbine, a PEM fuel cell and a starting / power generator, the starting / power generator, the air compressor and the gas turbine are of a coaxial structure, air compressed by the air compressor is divided into two paths, and the two paths are communicated with each other. One path of compressed air enters the main combustion chamber through the cold end of the heat regenerator, and the rear end of the main combustion chamber is connected with a gas turbine; the other path of compressed air enters the PEM fuel cell, the PEM fuel cell supplies power to the electric bus bar, and the reaction rear end of the PEM fuel cell is connected with the gas turbine; the gas turbine is jointly driven by the main combustion chamber and the PEM fuel cell, and an exhaust channel of the gas turbine passes through the hot end of the heat regenerator. The fuel cell power generation unit composed of the H2 fuel tank, the PEM fuel cell and the secondary combustion chamber is used for receiving high-temperature compressed gas from the gas compressor, the high-temperature and high-pressure gas of the gas compressor can conduct hot air purging on cold start of the fuel cell, low-temperature start of the PEM fuel cell is helped, and the fuel cell power generation efficiency is improved. And meanwhile, high-temperature and high-pressure air at the outlet of the compressor is humidified and cooled through cooling of liquid water, and the requirement for system accessories is simplified.

Description

Technical Field

[0001] The present invention belongs to the technical field of aviation secondary power systems, and relates to a power system of a dual-fuel aircraft and an operating method thereof, and specifically to a combined power system and an operating method of a dual-fuel aircraft. Background Art

[0002] The secondary power system of aircraft usually uses APU to provide airborne power. The performance of APU drops significantly with the increase of flight altitude during use. Its maximum operating altitude is generally not higher than 12,000m, and the overall thermal efficiency of airborne APU is low, generally not exceeding 20%. At present, it is proposed to use a combined power system based on PEM fuel cells and combustion engines to replace the traditional APU. Since PEM fuel cells are less affected by high altitude, they can be used at altitudes above 12,000m. However, the auxiliary components of PEM fuel cells alone are many and complex, the low-temperature starting effect is poor, and hydrogen is difficult to store in large quantities on the aircraft. Therefore, it is necessary to adopt a combined power design concept and use dual fuel to drive the aircraft's APU, or as the main power of small aircraft. Summary of the invention

[0003] In order to solve the above problems, a power system and operation method of a combination of a gas engine and a PEM fuel cell are provided, which has the characteristics of flexible working mode adjustment, high efficiency and low-temperature working characteristics. The present invention can provide multi-electric long-flight hybrid power technology for low-altitude economic aircraft, and can also be used as a second power energy generation solution onboard the aircraft.

[0004] The technical solution of the present invention is as follows:

[0005] A dual-fuel aircraft combined power system includes an air compressor, a regenerator, a main combustion chamber, a gas turbine, a PEM fuel cell, and a starter / generator. The starter / generator, the air compressor and the gas turbine are coaxial structures. The air compressed by the air compressor is divided into two paths. One path of compressed air enters the main combustion chamber through the cold end of the regenerator, and the rear end of the main combustion chamber is connected to the gas turbine; the other path of compressed air enters the PEM fuel cell, the PEM fuel cell supplies power to the electric bus bar, and the reaction rear end of the PEM fuel cell is connected to the gas turbine; the gas turbine is driven by the main combustion chamber and the PEM fuel cell, and the exhaust channel of the gas turbine passes through the hot end of the regenerator.

[0006] Furthermore, it also includes a secondary combustion chamber, which is arranged between the PEM fuel cell and the gas turbine, and the fuel and air that are not completely reacted in the PEM fuel cell are burned in the secondary combustion chamber.

[0007] Furthermore, it also includes an H2 fuel tank and a fuel tank, the fuel tank is connected to the main combustion chamber, and the H2 fuel tank is connected to the PEM fuel cell.

[0008] Furthermore, it also includes a system controller and a starter, the starter is powered by an electrical bus bar, and the starter is connected to a starter / generator; the system controller connects and controls the starter, the starter / generator and the PEM fuel cell.

[0009] Furthermore, it also includes a DC / DC power conversion unit and an AC / DC power conversion unit. The generator supplies power to the electric bus through the AC / DC power conversion unit, and the PEM fuel cell supplies power to the electric bus through the DC / DC power conversion unit.

[0010] Furthermore, it also includes a water cooling circuit, which cools the starter, AC / DC power conversion unit, and DC / DC power conversion unit before and after, and then enters the PEM fuel cell. Part of the water enters the cathode of the PEM fuel cell for humidification, and the other part of the water cools the PEM fuel cell as a whole and then enters the main combustion chamber.

[0011] A method for operating a dual-fuel aircraft combined power system, using the aforementioned dual-fuel aircraft combined power system, includes the following methods:

[0012] The system controller switches the working mode according to the aircraft status and system working requirements. When the gas turbine is started, the gas turbine unit composed of the air compressor, starter / generator and gas turbine is started first to achieve rapid start of the gas turbine and prepare low-temperature starting conditions for the PEM fuel cell. When the aircraft is in cruising mode, the PEM fuel cell is mainly used to achieve higher fuel efficiency for the entire system.

[0013] Furthermore, the system controller adjusts the speed of the air compressor by controlling the generator, thereby adjusting the high-pressure air entering the cathode of the PEM fuel cell and stabilizing the working conditions of the fuel cell.

[0014] Furthermore, the system controller controls the generator. When the aircraft is on the ground, the generator is controlled to operate at a low speed to save energy. When the aircraft is at a high altitude, the system controller controls the generator to operate at a high speed and opens the water cooling circuit to assist with water cooling and humidification to maintain the working environment temperature of the PEM fuel cell at low and high altitudes.

[0015] Beneficial effects of the present invention:

[0016] 1. The present invention relates to a dual-fuel aircraft combined power system, which is a combustion engine unit composed of a compressor, a gas turbine, a starter / generator, a regenerator, and a main combustion chamber. The compressor, gas turbine, and starter / generator are installed on the same shaft, eliminating the traditional gear reduction transmission device, greatly simplifying the system structure. The heat recovery of the exhaust gas at the outlet of the gas turbine is improved through the regenerator. The main combustion chamber can accept portable fuels such as kerosene and convert them into steam by water cooling, avoiding the performance degradation caused by the use of cooling air.

[0017] 2. The invention relates to a dual-fuel aircraft combined power system, which is a fuel cell power generation unit composed of an H2 fuel tank, a PEM fuel cell, and a secondary combustion chamber. The PEM fuel cell receives high-temperature compressed gas from the compressor. The high-temperature and high-pressure gas of the compressor can be used for hot air purge of the fuel cell for cold start, helping the PEM fuel cell to start at low temperature. At the same time, the high-temperature and high-pressure air at the outlet of the compressor is humidified and cooled by liquid water cooling, which simplifies the requirements for system accessories.

[0018] 3. The dual-fuel aircraft combined power system of the present invention is flexible in adjusting the system working mode, and the system can be quickly started by the combustion engine unit during the starting process. The fuel cell changes with the ambient atmospheric conditions at different flight altitudes, and the performance is unstable. By adjusting the speed of the compressor by the system controller, stable fuel cell working conditions can be provided, so the system has little attenuation of high-altitude performance.

[0019] 4. The present invention relates to a dual-fuel aircraft combined power system that adopts dual fuels. The PEM fuel cell uses high-purity hydrogen provided by an H2 tank, and the combustion engine unit uses portable fuel provided by a fuel tank. On the one hand, it solves the problem that H2 is difficult to carry on aircraft to a certain extent. On the other hand, the fuel tank carries portable fuels such as kerosene to increase the working time of the system.

[0020] 5. The dual-fuel aircraft combined power system of the present invention switches the working mode through the system controller according to the state and system working requirements. When starting, the combustion engine unit is started first to achieve rapid start-up and prepare low-temperature starting conditions for the PEM fuel cell. In the cruising working state, the PEM fuel cell is mainly used to achieve a higher fuel efficiency of the entire system.

[0021] 6. The invention includes a high-speed direct-drive motor to simplify the gearbox, simplify the system structure and weight, and the use of fuel cells improves the fuel thermal efficiency of the system. This system solution has the characteristics of fast start-up, high efficiency, and low attenuation at high altitudes. It can greatly improve the performance of the airborne two-power system and provide long-term endurance power for low-altitude aircraft such as drones, and has great application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solution of the implementation method of the patent of the present invention, the following is a brief introduction to the drawings required for use in the implementation method. It should be understood that the following drawings only show certain embodiments of the patent of the present invention and should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 It is a structural schematic diagram of a dual-fuel aircraft combined power system of the present invention;

[0024] Among them, 1-air compressor, 2-regenerator, 3-fuel tank, 4-main combustion chamber, 5-gas turbine, 6-secondary combustion chamber, 7-PEM fuel cell, 8-H2 fuel tank, 9-DC / DC power conversion unit, 10-AC / DC power conversion unit, 11-system controller, 12-starter, 13-starter / generator. DETAILED DESCRIPTION

[0025] This section is an embodiment of the present invention, which is used to explain and illustrate the technical solution of the present invention. In the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0026] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate directions or positional relationships as given in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or case referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implying the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0027] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be interpreted in a broad sense, for example, it can be a fixed connection, a detachable connection or an integrated connection; it can be a mechanical connection or a point connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0028] Embodiment 1:

[0029] A dual-fuel aircraft combined power system includes an air compressor 1, a regenerator 2, a main combustion chamber 4, a gas turbine 5, a PEM fuel cell 7, and a generator / starter 13. The generator / starter 13, the air compressor 1 and the gas turbine 5 are coaxial structures. The air compressed by the air compressor 1 is divided into two paths. One path of compressed air enters the main combustion chamber 4 through the cold end of the regenerator 2, and the rear end of the main combustion chamber 4 is connected to the gas turbine 5; the other path of compressed air enters the PEM fuel cell 7, the PEM fuel cell 7 supplies power to the electric bus bar, and the reaction rear end of the PEM fuel cell 7 is connected to the gas turbine 5; the gas turbine 5 is driven by the main combustion chamber 4 and the PEM fuel cell 7, and the exhaust channel of the gas turbine 5 passes through the hot end of the regenerator 2.

[0030] The system further comprises a secondary combustion chamber 6 , which is arranged between the PEM fuel cell 7 and the gas turbine 5 , and the fuel and air which are not completely reacted in the PEM fuel cell 7 are burned in the secondary combustion chamber 6 .

[0031] It also includes an H2 fuel tank 8 and a fuel tank 3 , wherein the fuel tank 3 is connected to the main combustion chamber 4 , and the H2 fuel tank 8 is connected to the PEM fuel cell 7 .

[0032] It also includes a system controller 11 and a starter 12 . The starter 12 is powered by an electrical bus and connected to a starter / generator 13 . The system controller 11 connects and controls the starter 12 , the starter / generator 13 and the PEM fuel cell 7 .

[0033] It also includes a DC / DC power conversion unit 9 and an AC / DC power conversion unit 10 . The generator 13 supplies power to the electric bus through the AC / DC power conversion unit 10 , and the PEM fuel cell 7 supplies power to the electric bus through the DC / DC power conversion unit 9 .

[0034] It also includes a water cooling circuit, which cools the starter 12, AC / DC power conversion unit 10, and DC / DC power conversion unit 9 before and after entering the PEM fuel cell 7, wherein a portion of the water enters the cathode of the PEM fuel cell 7 for humidification, and the other portion of the water cools the PEM fuel cell 7 as a whole and then enters the main combustion chamber 4.

[0035] A method for operating a dual-fuel aircraft combined power system, using the aforementioned dual-fuel aircraft combined power system, includes the following methods:

[0036] The system controller 11 switches the working mode according to the aircraft status and system working requirements. When the gas turbine is started, the gas turbine unit composed of the air compressor 1, the starter / generator 13 and the gas turbine 5 is started first to achieve rapid starting of the gas turbine and prepare low-temperature starting conditions for the PEM fuel cell 7; when the aircraft is in cruising working state, the PEM fuel cell 7 is mainly used to achieve higher fuel efficiency of the entire system.

[0037] The system controller 11 adjusts the speed of the air compressor 1 by controlling the generator 13, thereby adjusting the high-pressure air entering the cathode of the PEM fuel cell 7 and stabilizing the working conditions of the fuel cell.

[0038] The system controller 11 controls the generator 13. When the aircraft is on the ground, the generator 13 is controlled to operate at a low speed to save energy and at a rated speed below 60%. When the aircraft is at a high altitude, the system controller 4 controls the generator 13 to operate at a high speed to a rated speed above 90%, and at the same time opens the water cooling circuit to assist with water cooling and humidification to maintain the working environment temperature of the PEM fuel cell 7 at low and high altitudes.

[0039] Embodiment 2:

[0040] A dual-fuel aircraft combined power system, characterized in that the system includes an air compressor 1, a regenerator 2, a fuel tank 3, a main combustion chamber 4, a gas turbine 5, a secondary combustion chamber 6, a PEM fuel cell 7, an H2 fuel tank 8, a DC / DC power conversion unit 9, an AC / DC power conversion unit 10, a system controller 11, a starter 12 and a starter / generator 13.

[0041] The combustion engine unit consists of a compressor 1, a gas turbine 5, a generator 13, a regenerator 2, and a main combustion chamber 4. The compressor 1, the gas turbine 5, and the generator 13 are installed on the same shaft, removing the traditional gear reduction transmission device, greatly simplifying the system structure. The heat recovery of the exhaust gas at the outlet of the gas turbine 5 is performed through the regenerator 2 to improve the efficiency. The main combustion chamber 4 can accept portable fuels such as kerosene and use water cooling to convert it into steam, avoiding the performance degradation caused by the use of cooling air.

[0042] The fuel cell power generation unit is composed of an H2 fuel tank 8, a PEM fuel cell 7, and a secondary combustion chamber 6. The PEM fuel cell 7 receives high-temperature compressed gas from the compressor 1. The high-temperature and high-pressure gas of the compressor can be used for hot air purge for cold start of the fuel cell, helping the PEM fuel cell 7 to start at low temperature. At the same time, the high-temperature and high-pressure air at the outlet of the compressor is humidified and cooled by cooling with liquid water, simplifying the requirements for system accessories.

[0043] The DC / DC power conversion unit 9 transforms and stabilizes the DC power of the fuel cell, and the AC / DC power conversion unit 10 converts the AC power generated by the combustion engine unit into DC power. The rectified power that meets the power requirements of the DC / DC power conversion unit 9 and the AC / DC power conversion unit 10 is connected to the power bus. The starter 12 directly draws power from the power bus, and adjusts the speed of the starter / generator 13 through the system controller, thereby controlling the working state of the combustion engine unit and the fuel cell unit.

[0044] The system controller 11 switches the working mode according to the state and system working requirements. When starting, the combustion engine unit is started first to achieve rapid system start-up and prepare low-temperature starting conditions for the PEM fuel cell 7. In the cruising working state, the PEM fuel cell 7 is mainly used to achieve a higher fuel efficiency of the entire power system.

[0045] The system is designed with water treatment, using water as the main heat transfer medium. On the one hand, it cools the DC / DC power conversion unit 9, AC / DC power conversion unit 10, system controller 11, and starter 12. On the other hand, it humidifies and cools the inlet air of the PEM fuel cell 7, simplifying the complex water treatment system of the fuel cell.

[0046] The system working mode can be adjusted flexibly, and the system can be started quickly through the combustion engine unit during the starting process. The fuel cell changes with the ambient atmospheric conditions at different flight altitudes, and the performance is unstable. By adjusting the speed of the compressor 1 by the system controller 11, stable fuel cell working conditions can be provided, so the system performance at high altitude is less attenuated.

[0047] The system adopts dual fuel. The PEM fuel cell 7 uses high-purity hydrogen provided by the H2 tank 8, and the combustion engine unit uses the portable fuel provided by the fuel tank 3. On the one hand, it solves the problem that H2 is difficult to carry on aircraft to a certain extent. On the other hand, the fuel tank 3 carries portable fuels such as kerosene to increase the working time of the system.

[0048] The system controller 4 controls the motor starter through the control cable respectively. It works at a lower speed on the ground. In the high altitude, due to the decrease in atmospheric temperature and pressure, the system controller 4 controls the starter / generator to work at a higher speed, and assists with water cooling and humidification. In this way, the air intake conditions of the fuel cell at low altitude and high altitude are maintained unchanged, thereby providing stable output performance.

[0049] A dual-fuel aircraft combined power system, characterized in that the system includes an air compressor 1, a regenerator 2, a fuel tank 3, a main combustion chamber 4, a gas turbine 5, a secondary combustion chamber 6, a PEM fuel cell 7, an H2 fuel tank 8, a DC / DC power conversion unit 9, an AC / DC power conversion unit 10, a system controller 11, a starter 12 and a generator 13. The air compressor 1, the gas turbine 5, and the generator 13 are installed on the same transmission shaft. The compressor 1 and the gas turbine 5 are installed back to back, which can effectively balance the axial force. The generator 13 is installed before the compressor, so that the air intake of the compressor 1 can be used to cool the generator 13. The air compressor 1 of the system provides compressed air for the main combustion chamber 4 of the combustion unit and the PEM fuel cell 7 at the same time. The high-pressure air at the outlet of the air compressor 1 of the combustion unit and the high-temperature combustion gas at the outlet of the gas turbine 5 are recovered through the regenerator 2 to improve the system performance. The system adopts the PEM fuel cell 7, which has a high degree of technical maturity and has reached a usable state. The anode of the PEM fuel cell 7 receives high-purity hydrogen from the H2 tank 8, and the cathode receives compressed air from the compressor 1. The high-purity hydrogen and compressed air react through the fuel cell and enter the secondary combustion chamber 6 for combustion to recover the unreacted part of the fuel hydrogen. At the same time, after the hydrogen is burned, the impact of hydrogen emissions on the safety of the system can be eliminated. The secondary combustion chamber 6 can process oxygen-depleted air and unreacted hydrogen, and the combustion mixture recovers part of the energy through the gas turbine 5. The alternating current generated by the starter / generator 12 is converted into direct current through the AC / DC power conversion unit 10, and then enters the electric bus. The starter / generator 13 is pneumatically and speed-controlled through the starter 12. The direct current output by the PEM fuel cell 7 enters the electric bus after the voltage is converted by the DC / DC power conversion unit 9. The starter 12, the AC / DC power conversion unit 10, the DC / DC power conversion unit 9, and the system controller 11 can be integrated in the whole machine controller. The cooling water used in the cooling system first passes through the controller to cool the starter 12, AC / DC power conversion unit 10, and DC / DC power conversion unit 9, and then cools the PEM fuel cell 7. The cooled high-temperature water continues to humidify the inlet air of the PEM fuel cell 7 and cools the main combustion chamber 4 or the gas turbine 5, thereby avoiding the demand for cooling air for the gas turbine and optimizing the system performance.

[0050] It also includes a combustion engine unit consisting of a compressor 1, a gas turbine 5, a starter / generator 13, a regenerator 2, and a main combustion chamber 4, and a fuel cell power generation unit consisting of an H2 fuel tank 8, a PEM fuel cell 7, and a secondary combustion chamber 6, forming a hybrid power system. The hybrid power system improves the efficiency and working range of the entire power system.

[0051] The compressor 1, gas turbine 5, and generator 13 are installed on the same shaft, removing the traditional gear reduction transmission device, greatly simplifying the system structure. The heat recovery of the exhaust gas at the outlet of the gas turbine 5 is carried out through the regenerator 2 to improve the efficiency. The main combustion chamber 4 can accept portable fuels such as kerosene and convert them into steam by water cooling, avoiding the performance degradation caused by the use of cooling air.

[0052] The PEM fuel cell 7 receives high-temperature compressed air from the compressor 1, which alleviates the problem of slow cold start. The high-temperature and high-pressure air at the compressor outlet is humidified and cooled by liquid water cooling, which simplifies the requirements for system accessories.

[0053] The fuel cell power generation unit adopts a secondary combustion chamber, which can effectively process the fuel cell tail gas and convert it into heat energy to recover part of the energy through the gas turbine 5 and the regenerator 2.

[0054] The combined power system can achieve rapid start-up through the combustion engine unit during the start-up process, and has the characteristics of fast response speed. After the fuel cell is started, the compressor 1 provides high-temperature and high-pressure air for the fuel cell power generation unit. The compressor speed can be adjusted according to different flight altitudes, thereby stabilizing the fuel cell inlet air state and greatly reducing the high-altitude performance attenuation of the combined power system.

[0055] The above is only a specific embodiment of the present invention, and the present invention is described in detail. The unexplained part is a conventional technology. However, the protection scope of the present invention is not limited to this. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A dual-fuel aircraft combined power system, characterized in that: The invention comprises an air compressor (1), a regenerator (2), a main combustion chamber (4), a gas turbine (5), a PEM fuel cell (7), and a generator (13). The generator (13), the air compressor (1), and the gas turbine (5) are coaxial structures. The air compressed by the air compressor (1) is divided into two paths. One path of compressed air enters the main combustion chamber (4) through the cold end of the regenerator (2). The rear end of the main combustion chamber (4) is connected to the gas turbine (5); the other path of compressed air enters the PEM fuel cell (7). The PEM fuel cell (7) supplies power to the electric bus bar. The reaction rear end of the PEM fuel cell (7) is connected to the gas turbine (5); the gas turbine (5) is driven by the main combustion chamber (4) and the PEM fuel cell (7). The exhaust passage of the gas turbine (5) passes through the hot end of the regenerator (2).

2. A dual-fuel aircraft combined power system according to claim 1, characterized in that: The invention also comprises a secondary combustion chamber (6), which is arranged between the PEM fuel cell (7) and the gas turbine (5), wherein the fuel and air which are not completely reacted in the PEM fuel cell (7) are burned in the secondary combustion chamber (6), and the gas in the secondary combustion chamber (6) drives the gas turbine (5).

3. A dual-fuel aircraft combined power system according to claim 1, characterized in that: It also includes an H2 fuel tank (8) and a fuel tank (3), wherein the fuel tank (3) is connected to the main combustion chamber (4), and the H2 fuel tank (8) is connected to the PEM fuel cell (7).

4. A dual-fuel aircraft combined power system according to claim 1, characterized in that: It also includes a system controller (11) and a starter (12), wherein the starter (12) is powered by an electrical bus bar and connected to a starter / generator (13); the system controller (11) connects and controls the starter (12), the starter / generator (13) and the PEM fuel cell (7).

5. A dual-fuel aircraft combined power system according to claim 4, characterized in that: It also includes a DC / DC power conversion unit (9) and an AC / DC power conversion unit (10), the generator (13) supplies power to the electric bus bar through the AC / DC power conversion unit (10), and the PEM fuel cell (7) supplies power to the electric bus bar through the DC / DC power conversion unit (9).

6. A dual-fuel aircraft combined power system according to claim 5, characterized in that: The invention also includes a water cooling circuit, which cools the starter (12), the AC / DC power conversion unit (10), and the DC / DC power conversion unit (9) before and after entering the PEM fuel cell (7), wherein a part of the water enters the cathode of the PEM fuel cell (7) for humidification, and another part of the water cools the PEM fuel cell (7) as a whole and then enters the main combustion chamber (4).

7. A method for operating a dual-fuel aircraft combined power system, using a dual-fuel aircraft combined power system as claimed in any one of claims 1 to 6, characterized in that: The following methods are included: The working mode is switched according to the aircraft state and the system working requirements. When the engine is started, the engine unit composed of the air compressor (1), the starter / generator (13) and the gas turbine (5) is started first to achieve rapid starting of the engine and prepare low-temperature starting conditions for the PEM fuel cell (7). When the aircraft is in a cruising state, the PEM fuel cell (7) is mainly used to work, so that the entire system achieves a higher fuel efficiency.

8. The method for operating a dual-fuel aircraft combined power system according to claim 7, characterized in that: The rotation speed of the air compressor (1) is regulated by controlling the generator (13), thereby regulating the high-pressure air entering the cathode of the PEM fuel cell (7) and stabilizing the working conditions of the fuel cell.

9. The method for operating a dual-fuel aircraft combined power system according to claim 8, characterized in that: The generator (13) is controlled to operate at a low speed (less than 60% of the rated speed) to save energy when the aircraft is on the ground; when the aircraft is at a high altitude, the system controller (4) controls the generator (13) to operate at a high speed (more than 90% of the rated speed), and at the same time opens a water cooling circuit to assist with water cooling and humidification, thereby maintaining the working environment temperature of the PEM fuel cell (7) at low altitude and high altitude.

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