A combined power system based on methanol fuel cell auxiliary power unit and turbofan engine

Abstract

The application provides a combined power system based on a methanol fuel cell auxiliary power device and a turbofan main engine, which is applied to the field of aviation power technology and comprises a fuel supply system, a heat exchanger, a preheater, a methanol fuel cell auxiliary power device system and a turbofan engine core system; the fuel supply system is connected with the methanol fuel cell auxiliary power device system and the heat exchanger respectively; the heat exchanger and the methanol fuel cell auxiliary power device system are connected with the preheater; and the preheater is connected with the turbofan engine core system. The methanol fuel cell auxiliary power device can utilize the electric power generated by the fuel cell to drive an electric auxiliary turbocharger to generate high-pressure gas when the main engine is started, so that the high-pressure gas is led to the combustion chamber of the main engine and the combustion efficiency is improved; on the other hand, the electric power generated by the fuel cell can be utilized to preheat the fuel led to the main engine, so that the atomization quality of the fuel is improved and the combustion efficiency is further improved.

Description

Technical Field

[0001] This invention belongs to the field of aviation power technology, and in particular relates to a combined power system based on a methanol fuel cell auxiliary power unit and a turbofan engine. Background Technology

[0002] With the continuous development of the aviation industry, aircraft energy and power systems are gradually moving towards higher efficiency, environmental friendliness, and lower emissions. Traditional aircraft engines generally rely on aviation kerosene, resulting in high energy consumption. In addition, aircraft energy efficiency is also affected by multiple factors such as flight phase, power distribution, and auxiliary power systems. How to improve the energy efficiency of aircraft and reduce carbon emissions has become an important issue in the current development of aviation technology. Summary of the Invention

[0003] In view of this, and to address the problems of high carbon emissions, high NOx emissions, and low energy efficiency of traditional auxiliary power units (APUs), this invention provides an aircraft energy and propulsion system based on a methanol fuel cell APU combined with a turbofan engine. The aim is to fully utilize the advantages of methanol fuel cells and effectively combine them with the turbofan engine's power system to form a synergistic and complementary integrated power system. Through this system, the aircraft can reduce the fuel consumption of traditional turbofan engines during different flight phases, especially during takeoff, taxiing, and in-flight refueling, thereby improving the overall energy efficiency of the aircraft, reducing environmental pollution, and ultimately promoting the aviation industry towards a more environmentally friendly and sustainable development direction.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: a combined power system based on a methanol fuel cell auxiliary power unit and a turbofan engine, comprising a fuel supply system, a heat exchanger, a preheater, a methanol fuel cell auxiliary power unit system, and a turbofan engine core engine system. The fuel supply system is connected to both the methanol fuel cell auxiliary power unit system and the heat exchanger. The heat exchanger and the methanol fuel cell auxiliary power unit system are both connected to the preheater. The preheater is connected to the turbofan engine core engine system.

[0005] The methanol fuel cell auxiliary power unit system includes a water tank, a premixing chamber, a fuel cell, a battery, a power distribution device, and an electric auxiliary turbocharger. The anode inlet of the fuel cell is connected to the outlet of the premixing chamber, and the anode outlet is connected to a heat exchanger. The cathode inlet of the fuel cell is connected to air, and the cathode outlet is connected to the water tank. The outlet of the water tank is connected to the inlet of the premixing chamber. The power output from the fuel cell goes to the battery and then to the power distribution device. Part of the power is used to drive the electric auxiliary turbocharger to provide compressed air. The outlet of the electric auxiliary turbocharger is connected to the inlet of the combustion chamber.

[0006] The turbofan engine core system includes an intake duct, a fan, a low-pressure compressor, a high-pressure compressor, a high-pressure turbine, a low-pressure turbine, and an exhaust nozzle connected in sequence. The combustion chamber is connected to the preheater, the high-pressure compressor, and the high-pressure turbine, respectively.

[0007] The fuel supply system includes a fuel tank, a control valve, a fuel pump, and a fuel distributor connected in sequence. The fuel distributor is connected to a premixing chamber and a heat exchanger, respectively.

[0008] Furthermore, the inlet of the air intake is connected to the outside atmosphere, and the outlet is connected to the inlet of the fan.

[0009] Furthermore, the fan has two outlets: an inner duct and an outer duct. The air flowing into the outer duct is compressed and then discharged to provide power for the aircraft, while the air flowing into the inner duct is connected to the inlet of the low-pressure compressor.

[0010] Furthermore, the inlet of the tail nozzle is connected to the outlet of the low-pressure turbine, and the outlet of the tail nozzle is connected to the outside atmosphere.

[0011] Furthermore, the power distribution device adjusts the power supplied to the preheater and the electrically auxiliary drive turbine compressor according to the power demand of the aircraft under different operating conditions.

[0012] Furthermore, the fan is coaxially arranged with the low-pressure compressor and the low-pressure turbine, and the low-pressure turbine drives the fan and the low-pressure compressor to work through a rotating shaft.

[0013] Furthermore, the high-pressure turbine is coaxially arranged with the high-pressure compressor, and the high-pressure turbine drives the high-pressure compressor to work through a rotating shaft.

[0014] A method for using a combined power system based on a methanol fuel cell auxiliary power unit and a turbofan engine specifically includes the following steps:

[0015] Step 1: In the methanol fuel cell auxiliary power unit system, after the fuel is depressurized by the control valve, it is drawn by the fuel pump and then split by the fuel distributor. Part of the fuel enters the premixing chamber and mixes with a certain proportion of water released from the water tank. Then it enters the anode of the methanol fuel cell and undergoes an oxidation reaction. The heat from the high-temperature CO2 generated at the anode is used to preheat the fuel. Air undergoes a reduction reaction at the cathode of the methanol fuel cell. The water produced enters the water tank for recycling. The electricity generated by the methanol fuel cell is transmitted to the battery and then distributed by the power distribution device. Part of the electricity is used to drive the electric auxiliary turbocharger to generate high-pressure gas, which is supplied to the combustion chamber of the main engine. The other part of the electricity is used for the preheater to preheat the fuel going to the main engine.

[0016] Step 2: Outside the turbofan engine, ambient air is drawn into the intake duct and then into the fan. The air is split into two streams by the fan. Most of the gas enters the outer bypass duct, where it is depressurized and accelerated by the duct wall before being ejected from the outlet to power the aircraft. The remaining gas enters the inner bypass duct and then the low-pressure compressor. The air in the low-pressure compressor then enters the high-pressure compressor for further pressurization. The resulting high-temperature, high-pressure gas enters the combustion chamber and mixes thoroughly with the fuel. The resulting high-temperature, high-pressure combustion gas enters the high-pressure turbine, driving it to perform work and powering the high-pressure compressor. After completing its work in the high-pressure turbine, the gas enters the low-pressure turbine to perform work, powering the fan and the low-pressure compressor. Finally, the gas exiting the low-pressure turbine enters the tailpipe, where it is depressurized and accelerated before being ejected to power the aircraft.

[0017] Compared with the prior art, the beneficial effects of the combined power system based on a methanol fuel cell auxiliary power unit and a turbofan engine described in this invention are:

[0018] (1) The combined power system based on a methanol fuel cell auxiliary power unit and a turbofan engine described in this invention uses methanol as fuel. Compared with aviation kerosene used in traditional aircraft power systems, the carbon and NOx emissions are as follows: When methanol fuel is completely burned, only 87.6 grams of carbon dioxide are produced per liter, while the carbon emissions after combustion of traditional aviation kerosene are significantly higher. Methanol has an oxygen content of up to 50%, resulting in more complete combustion. The emissions of hydrocarbons (HC) and carbon monoxide (CO) are reduced by an average of 70% compared to aviation kerosene. If renewable methanol is used (such as through biomass or carbon dioxide synthesis), its carbon emissions over its entire life cycle can be reduced by 95%, achieving a near-carbon neutrality effect. The nitrogen oxide (NOx) emissions from methanol combustion are reduced by an average of 45% compared to aviation kerosene, mainly due to its lower combustion temperature. Aviation kerosene combustion requires a high-temperature and high-pressure environment, which easily leads to the reaction of nitrogen and oxygen in the air to generate NOx, especially under high engine load conditions.

[0019] (2) The combined power system based on a methanol fuel cell auxiliary power unit and a turbofan engine described in this invention uses an electrically driven electric auxiliary turbocharger in the methanol fuel cell auxiliary power unit, which has the characteristic of faster response and start-up compared with traditional auxiliary power units. Traditional auxiliary power units are essentially small gas turbine engines, which usually need to burn fuel in the combustion chamber of the APU before driving the subsequent compressor to work and provide the high-pressure gas required by the main engine combustion chamber. However, the electric auxiliary turbocharger can quickly provide the high-pressure air required for combustion in the main engine.

[0020] (3) The combined power system based on methanol fuel cell auxiliary power unit and turbofan engine described in this invention fully utilizes the heat of CO2 generated by the anode of the fuel cell to heat the fuel leading to the main engine, and uses the electric power generated by the fuel cell to drive the heating device to heat the fuel, which can achieve higher fuel atomization quality and thus improve combustion efficiency. Attached Figure Description

[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0022] Figure 1 This is a schematic diagram of the combined power system based on a methanol fuel cell auxiliary power unit and a turbofan engine, as described in this invention.

[0023] In the diagram: 1-Fuel tank; 2-Control valve; 3-Fuel pump; 4-Fuel distributor; 5-Water tank; 6-Premixing chamber; 7-Fuel cell; 8-Heat exchanger; 9-Battery; 10-Power distribution device; 11-Preheater; 12-Electric auxiliary turbocharger; 13-Intake duct; 14-Fan; 15-Low-pressure compressor; 16-High-pressure compressor; 17-Combustion chamber; 18-High-pressure turbine; 19-Low-pressure turbine; 20-Exhaust nozzle. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0025] See Figure 1 This embodiment describes a combined power system based on a methanol fuel cell auxiliary power unit and a turbofan engine, comprising a fuel supply system, a heat exchanger 8, a preheater 11, a methanol fuel cell auxiliary power unit system, and a turbofan engine core engine system. The fuel supply system is connected to both the methanol fuel cell auxiliary power unit system and the heat exchanger 8. Both the heat exchanger 8 and the methanol fuel cell auxiliary power unit system are connected to the preheater 11, and the preheater 11 is connected to the turbofan engine core engine system.

[0026] The methanol fuel cell auxiliary power unit system includes a water storage tank 5, a premixing chamber 6, a fuel cell 7, a storage battery 9, a power distribution device 10, and an electric auxiliary turbocharger 12.

[0027] The turbofan engine core system includes an intake duct 13, a fan 14, a low-pressure compressor 15, a high-pressure compressor 16, a high-pressure turbine 18, a low-pressure turbine 19, and an exhaust nozzle 20 connected in sequence. The combustion chamber 17 is connected to the preheater 11, the high-pressure compressor 16, and the high-pressure turbine 18, respectively.

[0028] The fuel supply system includes a fuel tank 1, a control valve 2, a fuel pump 3, and a fuel distributor 4 connected in sequence. The fuel distributor 4 is connected to a premixing chamber 6 and a heat exchanger 8. The inlet of the control valve 2 is connected to the outlet of the fuel tank 1, and the outlet of the control valve 2 is connected to the inlet of the fuel pump 3. The inlet of the fuel distributor 4 is connected to the outlet of the fuel pump 3, and the outlet is connected to the inlets of the premixing chamber 6 and the heat exchanger 8.

[0029] The outlet of the heat exchanger 8 is connected to the inlet of the preheater 11, and the outlet of the preheater 11 is connected to the inlet of the combustion chamber 17.

[0030] The anode inlet of the fuel cell 7 is connected to the outlet of the premixing chamber 6, and the anode outlet is connected to the heat exchanger 8. The cathode inlet of the fuel cell 7 is connected to air, and the cathode outlet is connected to the water storage tank 5. The outlet of the water storage tank 5 is connected to the inlet of the premixing chamber 6. The power output from the fuel cell 7 goes to the battery 9, and then to the power distribution device 10. Part of the power is used to drive the electrically assisted turbocharger 12 to provide compressed air. The outlet of the electrically assisted turbocharger 12 is connected to the inlet of the combustion chamber 17. The power distribution device 10 provides part of the power to the preheater 11 to preheat methanol.

[0031] The inlet of the air intake 13 is connected to the outside atmosphere, and the outlet is connected to the inlet of the fan 14. The fan 14 has two outlets: an inner duct and an outer bypass duct. The air flowing into the outer bypass duct is compressed and then discharged to provide power for the aircraft. The air flowing into the inner duct is connected to the inlet of the low-pressure compressor 15.

[0032] The inlet of the high-pressure compressor 16 is connected to the outlet of the low-pressure compressor 15, and the outlet is connected to the inlet of the combustion chamber 17. The inlet of the high-pressure turbine 18 is connected to the outlet of the combustion chamber 17, and the outlet is connected to the inlet of the low-pressure turbine 19. The inlet of the tail nozzle 20 is connected to the outlet of the low-pressure turbine 19, and the outlet is connected to the outside atmosphere.

[0033] The fuel splitter 4 divides the fuel into two streams: one stream goes to the fuel cell 7 for power generation, and the other stream goes to the combustion chamber 17 for combustion. The heat from the combustion is used to power the aircraft.

[0034] The CO2 product from the anode of the fuel cell 7 goes to the heat exchanger 8, where its heat can be used to preheat the fuel. The water product from the cathode goes to the water storage tank 5, where it is mixed with methanol in the premixing chamber 6, and then goes to the anode to react.

[0035] The power distribution device 10 can adjust the power supplied to the preheater 11 and the electrically assisted drive turbine compressor 12 according to the power demand of the aircraft under different operating conditions.

[0036] The fan 14 is coaxially arranged with the low-pressure compressor 15 and the low-pressure turbine 19. The low-pressure turbine 19 drives the fan 14 and the low-pressure compressor 15 through a rotating shaft to provide them with power.

[0037] The high-pressure turbine 18 is arranged coaxially with the high-pressure compressor 16. The high-pressure turbine 18 drives the high-pressure compressor 16 to work through the rotating shaft, providing it with power.

[0038] The working process of the combined power system based on a methanol fuel cell auxiliary power unit and a turbofan engine described in this invention is as follows:

[0039] Step 1: In the methanol fuel cell auxiliary power unit (APU) system, fuel is depressurized by control valve 2, then pumped by fuel pump 3, and then split by fuel distributor 4. A portion enters premixing chamber 5 and mixes with a certain proportion of water released from water tank 5 before entering the anode of methanol fuel cell 7, where an oxidation reaction occurs. The heat from the high-temperature CO2 generated at the anode can be used to preheat the fuel. Air undergoes a reduction reaction at the cathode of methanol fuel cell 7, and the resulting water can be recycled in water tank 5. The electricity generated by methanol fuel cell 7 is transmitted to battery 9, and then distributed by power distribution device 10. A portion of the electricity is used to drive electric auxiliary turbocharger 12 to generate high-pressure gas, which is supplied to the combustion chamber of the main engine. The other portion of the electricity is used in the preheater to preheat the fuel destined for the main engine.

[0040] Step 2: Outside the turbofan engine, ambient air is drawn into the intake duct 13 and then into the fan 14. After passing through the fan 14, the air is divided into two paths. Most of the gas enters the bypass duct, where it is depressurized and accelerated by the bypass duct wall before being ejected from the outlet to power the aircraft. The remaining gas enters the inner duct and then into the low-pressure compressor 15. The air in the low-pressure compressor 15 then enters the high-pressure compressor 16 for further pressurization. The resulting high-temperature, high-pressure gas enters the combustion chamber 17 and mixes thoroughly with the fuel. The resulting high-temperature, high-pressure gas enters the high-pressure turbine 18, driving it to perform work and power the high-pressure compressor 16. After completing its work in the high-pressure turbine 18, the gas enters the low-pressure turbine 19 to perform work, powering the fan 14 and the low-pressure compressor 15. The gas exiting the low-pressure turbine finally enters the tail nozzle 20, where it is depressurized and accelerated before being ejected to power the aircraft.

[0041] Fuel cells, as a clean and efficient energy conversion technology, are gradually entering the aviation field. Methanol fuel cells, with their high energy density (15.8 MJ / L), environmental friendliness, and ability to generate electricity through efficient chemical reactions at room temperature, are increasingly being recognized as a key technology in the auxiliary power unit (APU) field. They can meet the electrical needs of aircraft for both ground operation and flight without relying on traditional fossil fuels, thus significantly reducing aircraft carbon emissions.

[0042] Meanwhile, turbofan engines, as the mainstay engines of modern aircraft, are widely used in commercial flights due to their high thrust and high efficiency. The core advantages of turbofan engines lie in the thrust and fuel efficiency they provide.

[0043] This invention fully utilizes the advantages of methanol fuel cells, effectively combining them with the power system of turbofan engines to form a synergistic and complementary integrated power system. Through this system, aircraft can reduce the fuel consumption of traditional turbofan engines during different flight phases, especially takeoff, taxiing, and in-flight refueling, thereby improving the overall energy efficiency of the aircraft, reducing environmental pollution, and ultimately promoting the aviation industry towards a more environmentally friendly and sustainable development direction.

[0044] The embodiments of the present invention disclosed above are merely illustrative of the invention. These embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A combined power system based on a methanol fuel cell auxiliary power unit and a turbofan engine, characterized in that: It includes a fuel supply system, a heat exchanger (8), a preheater (11), a methanol fuel cell auxiliary power unit system and a turbofan engine core system. The fuel supply system is connected to the methanol fuel cell auxiliary power unit system and the heat exchanger (8) respectively. The heat exchanger (8) and the methanol fuel cell auxiliary power unit system are both connected to the preheater (11). The preheater (11) is connected to the turbofan engine core system. The methanol fuel cell auxiliary power unit system includes a water tank (5), a premixing chamber (6), a fuel cell (7), a storage battery (9), a power distribution device (10), and an electric auxiliary turbocharger (12). The anode inlet of the fuel cell (7) is connected to the outlet of the premixing chamber (6), and the anode outlet is connected to the heat exchanger (8). The cathode inlet of the fuel cell (7) is connected to the air, and the cathode outlet is connected to the water tank (5). The outlet of the water tank (5) is connected to the inlet of the premixing chamber (6). The power output by the fuel cell (7) goes to the storage battery (9) and then enters the power distribution device (10). Part of the power is used to drive the electric auxiliary turbocharger (12) to provide compressed air. The outlet of the electric auxiliary turbocharger (12) is connected to the inlet of the combustion chamber (17). The turbofan engine core system includes an intake duct (13), a fan (14), a low-pressure compressor (15), a high-pressure compressor (16), a high-pressure turbine (18), a low-pressure turbine (19), and a tail nozzle (20) connected in sequence. The combustion chamber (17) is connected to the preheater (11), the high-pressure compressor (16), and the high-pressure turbine (18) respectively. The fuel supply system includes a fuel tank (1), a control valve (2), a fuel pump (3) and a fuel distributor (4) connected in sequence. The fuel distributor (4) is connected to the premixing chamber (6) and the heat exchanger (8) respectively. The fan (14) is divided into two outlets: an inner duct and an outer duct. The air flowing into the outer duct is compressed and then discharged to provide power for the aircraft. The air flowing into the inner duct is connected to the inlet of the low-pressure compressor (15). The fan (14) is arranged coaxially with the low-pressure compressor (15) and the low-pressure turbine (19). The low-pressure turbine (19) drives the fan (14) and the low-pressure compressor (15) to work through the rotating shaft. The high-pressure turbine (18) and the high-pressure compressor (16) are arranged coaxially, and the high-pressure turbine (18) drives the high-pressure compressor (16) to work through the rotating shaft.

2. The combined power system based on a methanol fuel cell auxiliary power unit and a turbofan engine according to claim 1, characterized in that: The inlet of the air intake (13) is connected to the outside atmosphere, and the outlet is connected to the inlet of the fan (14).

3. The combined power system based on a methanol fuel cell auxiliary power unit and a turbofan engine according to claim 1, characterized in that: The inlet of the tail nozzle (20) is connected to the outlet of the low-pressure turbine (19), and the outlet of the tail nozzle (20) is connected to the outside atmosphere.

4. The combined power system based on a methanol fuel cell auxiliary power unit and a turbofan engine according to claim 1, characterized in that: The power distribution device (10) adjusts the power supplied to the preheater (11) and the electric auxiliary turbocharger (12) according to the power demand of the aircraft under different operating conditions.

5. A method of using a combined power system based on a methanol fuel cell auxiliary power unit and a turbofan engine according to any one of claims 1-4, characterized in that: Specifically, the following steps are included: Step 1: In the methanol fuel cell auxiliary power system, after the fuel is depressurized by the control valve (2), it is pumped by the fuel pump (3) and then split by the fuel splitter (4). Part of it enters the premixing chamber (6) and mixes with a certain proportion of water released from the water tank (5). Then it enters the anode of the fuel cell (7) and undergoes an oxidation reaction. The heat of the high temperature CO2 generated by the anode is used to preheat the fuel. The air undergoes a reduction reaction at the cathode of the fuel cell (7). The water generated enters the water tank (5) for recycling. The electricity generated by the fuel cell (7) is transmitted to the battery (9) and then the power is distributed by the power distribution device (10). Part of the electricity is used to drive the electric auxiliary turbocharger (12) to generate high pressure gas, which is supplied to the combustion chamber of the main engine. The other part of the electricity is used for the preheater (11) to preheat the fuel going to the main engine. Step 2: Outside the turbofan engine, outside air is drawn into the intake duct (13) and then into the fan (14). After passing through the fan (14), the air is divided into two paths. Most of the gas enters the outer bypass duct, and after being depressurized and accelerated by the outer bypass duct wall, it is ejected from the outlet to provide power for the aircraft. The remaining gas enters the inner duct and then enters the low-pressure compressor (15). The air in the low-pressure compressor (15) then enters the high-pressure compressor (16) for further pressurization. The resulting high-temperature and high-pressure gas enters the combustion chamber (17). The gas is fully mixed with the fuel and reacts to produce high-temperature and high-pressure gas. The gas enters the high-pressure turbine (18) and drives the high-pressure turbine (18) to do work, providing power for the high-pressure compressor (16). After the gas has done work in the high-pressure turbine (18), it enters the low-pressure turbine (19) to do work, providing power for the fan (14) and the low-pressure compressor (15). The gas coming out of the low-pressure turbine finally enters the tail nozzle (20), and after being depressurized and accelerated in the tail nozzle (20), it is ejected to provide power for the aircraft.

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