A hydrogen leak ventilation system and method for hydrogen-powered aircraft

Abstract

This invention discloses a hydrogen leakage ventilation system and method for hydrogen-powered aircraft, relating to the field of hydrogen safety in hydrogen-powered aircraft. The system's liquid hydrogen pipeline is sequentially connected to a liquid hydrogen Dewar flask, a third cryogenic shut-off valve, a liquid hydrogen primary heat exchanger, a first cryogenic shut-off valve, a liquid hydrogen secondary heat exchanger, a third shut-off valve, and the engine; the coolant outflow pipeline is sequentially connected to the engine, a fourth shut-off valve, and the liquid hydrogen secondary heat exchanger; the coolant return pipeline is sequentially connected to the liquid hydrogen secondary heat exchanger, the first shut-off valve, and the engine; the engine exhaust pipeline is sequentially connected to the engine, a fifth shut-off valve, a liquid hydrogen primary heat exchanger, a second cryogenic shut-off valve, a dryer, and an exhaust gas buffer tank; a low-flow purging pipeline is sequentially connected to the exhaust gas buffer tank, a back pressure valve, and an vent; and a high-flow purging pipeline is sequentially connected to the buffer tank, the second shut-off valve, and the exhaust port. This invention has the functions of passively and actively venting oxygen-deficient exhaust gas, used for dilution purging in the absence of significant hydrogen leakage and in the event of significant hydrogen leakage, respectively.

Description

Technical Field

[0001] This invention relates to the field of hydrogen safety in hydrogen-powered aircraft, and specifically to a hydrogen leakage ventilation system and method for hydrogen-powered aircraft. Background Technology

[0002] Using hydrogen as fuel for aircraft offers significant advantages and broad prospects. Hydrogen-powered aircraft can reduce carbon emissions, improve air quality, possess high energy efficiency and extended range, and meet the requirements of environmental protection and sustainable development. With continuous technological advancements and supportive policies, hydrogen-powered aircraft are expected to become an important development direction for the future aviation industry.

[0003] The safe use of hydrogen is one of the key technological requirements for hydrogen-powered aircraft, especially when liquid hydrogen is used as an energy storage form. Its extremely low temperature places higher demands on storage tanks, valves, and pipelines, posing a significant risk of leakage during storage and transportation. Rapidly diluting and dispersing leaked hydrogen is an effective way to eliminate hydrogen explosion accidents. Reducing oxygen concentration can also significantly narrow the concentration range for hydrogen explosions. These measures will ensure the safe operation of hydrogen-powered aircraft after a leak. Summary of the Invention

[0004] The purpose of this invention is to overcome the deficiencies in the prior art and provide a hydrogen leakage ventilation system and method for hydrogen-powered aircraft. This invention uses liquid hydrogen as a cold source to cool the high-temperature exhaust gas generated by the engine, and after removing moisture from the exhaust gas through a dryer, stores the exhaust gas in a buffer tank. This system has the functions of passively and actively discharging oxygen-deficient exhaust gas, used for dilution and purging when there is no obvious hydrogen leakage and when obvious hydrogen leakage occurs, respectively.

[0005] The specific technical solution adopted in this invention is as follows:

[0006] In a first aspect, the present invention provides a hydrogen leakage ventilation system for a hydrogen-powered aircraft, including a liquid hydrogen pipeline, a coolant outflow pipeline, a coolant return pipeline, an engine exhaust pipeline, a low-flow purging pipeline, and a high-flow purging pipeline;

[0007] The liquid hydrogen pipeline is connected in sequence to a liquid hydrogen Dewar flask, a third cryogenic shut-off valve, a liquid hydrogen primary heat exchanger, a first cryogenic shut-off valve, a liquid hydrogen secondary heat exchanger, a third shut-off valve, and an engine. It is used to absorb heat from the liquid hydrogen primary heat exchanger and the liquid hydrogen secondary heat exchanger to vaporize the liquid hydrogen and raise its temperature, thereby providing fuel for the engine.

[0008] The coolant outflow pipeline is connected in sequence to the engine, the fourth shut-off valve and the liquid hydrogen secondary heat exchanger, and is used to transport the coolant at a higher temperature to the liquid hydrogen secondary heat exchanger to provide heat for the liquid hydrogen vaporization and temperature rise.

[0009] The coolant return pipeline is connected in sequence to the liquid hydrogen secondary heat exchanger, the first shut-off valve and the engine, and is used to deliver coolant at a lower temperature to the engine to cool it down.

[0010] The engine exhaust pipeline is connected in sequence to the engine, the fifth shut-off valve, the liquid hydrogen primary heat exchanger, the second cryogenic shut-off valve, the dryer, and the exhaust gas buffer tank. It is used to cool the high-temperature exhaust gas generated by the engine to room temperature and then store it in the exhaust gas buffer tank.

[0011] The low-flow purging pipeline is connected in sequence to the exhaust gas buffer tank, the back pressure valve, and the vent, and is used to passively discharge the purging gas at a low flow rate; the high-flow purging pipeline is connected in sequence to the buffer tank, the second shut-off valve, and the exhaust port, and is used to actively discharge the purging gas at a high flow rate.

[0012] Preferably, all components of the system are located in the equipment compartment of the hydrogen-powered aircraft.

[0013] Furthermore, a hydrogen concentration sensor interlocked with the second shut-off valve is installed on the top of the equipment compartment. The opening and closing of the second shut-off valve can be controlled based on the signal value obtained from the hydrogen concentration sensor.

[0014] Preferably, both the liquid hydrogen primary heat exchanger and the liquid hydrogen secondary heat exchanger are plate-fin heat exchangers, which can exchange heat with the high-temperature exhaust gas and coolant respectively, and then vaporize and heat up to meet the engine intake air temperature requirements.

[0015] Preferably, both the liquid hydrogen Dewar flask and the liquid hydrogen pipeline are insulated with polyurethane foam.

[0016] Preferably, the set pressure of the back pressure valve is the engine exhaust pressure.

[0017] Preferably, the liquid hydrogen Dewar flask uses a self-pressurizing method to increase the internal pressure to supply liquid hydrogen, and its inner cavity is connected to a safety valve through a pipeline to ensure the safety of the internal pressure.

[0018] Preferably, the high-temperature exhaust gas produced by the engine comes from the combustion of hydrogen fuel.

[0019] Preferably, the high-temperature exhaust gas generated by the engine is cooled by a liquid hydrogen primary heat exchanger, and its temperature is slightly higher than the dew point temperature.

[0020] Secondly, the present invention provides a method for diluting and purging hydrogen leaks using any of the hydrogen leak ventilation systems for hydrogen-powered aircraft described in the first aspect, as follows:

[0021] The third, first, and third cryogenic shut-off valves are pre-opened. Utilizing the initial heat from the liquid hydrogen pipeline, a small amount of liquid hydrogen in the liquid hydrogen Dewar flask is vaporized and heated sequentially through the third cryogenic shut-off valve, the first-stage liquid hydrogen heat exchanger, the first cryogenic shut-off valve, the second-stage liquid hydrogen heat exchanger, and the third shut-off valve before entering the engine. Upon engine ignition and start-up, the fifth and second shut-off valves are opened. The high-temperature exhaust gas generated by the engine enters the first-stage liquid hydrogen heat exchanger through the engine exhaust pipeline, where it exchanges heat with the liquid hydrogen, lowering its temperature to above the dew point. It then passes through a dryer to remove moisture and is finally stored in the exhaust gas buffer tank. Simultaneously, the engine's cooling system is activated, opening the fourth and first shut-off valves. Coolant flows through the circulation loop formed by the engine, the coolant outlet pipeline, the second-stage liquid hydrogen heat exchanger, and the coolant return pipeline. This transfers the heat generated by the engine to the liquid hydrogen in the liquid hydrogen pipeline via the second-stage liquid hydrogen heat exchanger, causing the liquid hydrogen to vaporize and heat up to meet the engine's intake requirements.

[0022] Under conditions where there is no obvious leakage in the liquid hydrogen pipeline, the exhaust gas generated by the engine continuously enters the exhaust gas buffer tank through the engine exhaust gas pipeline for storage, and the pressure inside the tank continuously increases. When the pressure inside the exhaust gas buffer tank reaches the set pressure of the back pressure valve, the back pressure valve opens, and the exhaust gas buffer tank discharges oxygen-deficient exhaust gas through a small-flow purging pipeline to the vent located at the top of the equipment compartment. The reduction in oxygen content will significantly reduce the range of flammable and explosive hydrogen concentrations. Ultimately, the equipment compartment is filled with oxygen-deficient exhaust gas, which serves as a protective gas to prevent hydrogen combustion and explosion accidents.

[0023] In the event of a significant leak in the liquid hydrogen pipeline, the hydrogen concentration inside the equipment compartment increases dramatically. The second shut-off valve, interlocked with the hydrogen concentration sensor inside the equipment compartment, automatically opens, releasing a large amount of oxygen-deficient exhaust gas to the exhaust port located at the bottom of the equipment compartment through a high-flow-rate purging pipeline. This rapidly dilutes and disperses the leaked hydrogen, reducing the risk of combustion and explosion. At this time, the third cryogenic shut-off valve must also be closed promptly to stop the supply of liquid hydrogen.

[0024] The outstanding and beneficial technical effects of this invention compared to existing technologies are as follows: It utilizes the high-quality sensible heat of engine exhaust gas and coolant as the heat source for the vaporization and heating of liquid hydrogen, and the latent heat of vaporization of liquid hydrogen as the cold source for cooling engine exhaust gas and coolant, thus avoiding dependence on external energy input. After cooling, the exhaust gas is dried by a dryer and stored in a buffer tank. In the absence of significant hydrogen leakage, the exhaust gas is released from the back pressure valve as a protective gas to fill the entire equipment compartment. In the event of a significant leak, the valve can be actively opened to quickly release a large amount of oxygen-deficient exhaust gas, diluting and dispersing the leaked hydrogen, reducing the risk of combustion and explosion, and ensuring the safe operation of the aircraft.

[0025] The following will further explain the concept, specific structure and technical effects of the present invention with reference to the accompanying drawings, so as to fully understand the purpose, features and effects of the present invention. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a hydrogen leakage ventilation system for a hydrogen-powered aircraft according to the present invention.

[0027] In the diagram: 1. Hydrogen concentration sensor; 2. Vent port; 3. Back pressure valve; 4. Exhaust gas buffer tank; 5. First shut-off valve; 6. Small flow purging line; 7. Liquid hydrogen secondary heat exchanger; 8. First cryogenic shut-off valve; 9. Large flow purging line; 10. Safety valve; 11. Second cryogenic shut-off valve; 12. Dryer; 13. Second shut-off valve; 14. Liquid hydrogen Dewar flask; 15. Third shut-off valve; 16. Fourth shut-off valve; 17. Coolant outlet line; 18. Liquid hydrogen primary heat exchanger; 19. Third cryogenic shut-off valve; 20. Liquid hydrogen line; 21. Coolant return line; 22. Engine; 23. Engine exhaust line; 24. Fifth shut-off valve; 25. Exhaust port; 26. Equipment compartment. Detailed Implementation

[0028] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. Technical features in the various embodiments of the present invention can be combined accordingly without mutual conflict.

[0029] In the description of this invention, it should be understood that when an element is considered to be "connected" to another element, it can be a direct connection to the other element or an indirect connection, i.e., there is an intermediate element. Conversely, when an element is said to be "directly" connected to another element, there is no intermediate element.

[0030] like Figure 1 As shown, this invention provides a hydrogen leak ventilation system for a hydrogen-powered aircraft. The system mainly includes a hydrogen concentration sensor 1, an vent 2, a back pressure valve 3, an exhaust gas buffer tank 4, a first shut-off valve 5, a low-flow purging pipeline 6, a liquid hydrogen secondary heat exchanger 7, a first cryogenic shut-off valve 8, a high-flow purging pipeline 9, a safety valve 10, a second cryogenic shut-off valve 11, a dryer 12, a second shut-off valve 13, a liquid hydrogen Dewar flask 14, a third shut-off valve 15, a fourth shut-off valve 16, a coolant outflow pipeline 17, a liquid hydrogen primary heat exchanger 18, a third cryogenic shut-off valve 19, a liquid hydrogen pipeline 20, a coolant return pipeline 21, an engine 22, an engine exhaust pipeline 23, a fifth shut-off valve 24, and an exhaust port 25. All components of the above system should be installed within the equipment compartment 26 of the hydrogen-powered aircraft.

[0031] The specific connection methods and working principles of each component in this ventilation system are described in detail below.

[0032] In this invention, the liquid hydrogen pipeline 20 is sequentially connected to the liquid hydrogen Dewar flask 14, the third cryogenic shut-off valve 19, the liquid hydrogen primary heat exchanger 18, the first cryogenic shut-off valve 8, the liquid hydrogen secondary heat exchanger 7, the third shut-off valve 15, and the engine 22. It is used to absorb heat from the liquid hydrogen primary heat exchanger 18 and the liquid hydrogen secondary heat exchanger 7 to vaporize and heat the liquid hydrogen, providing fuel for the engine 22. That is, the outlet of the liquid hydrogen Dewar flask 14 is sequentially connected to the third cryogenic shut-off valve 19, a heat exchange channel of the liquid hydrogen primary heat exchanger 18, the first cryogenic shut-off valve 8, a heat exchange channel of the liquid hydrogen secondary heat exchanger 7, the third shut-off valve 15, and the engine 22 via the liquid hydrogen pipeline 20. Both the liquid hydrogen primary heat exchanger 18 and the liquid hydrogen secondary heat exchanger 7 have two heat exchange channels that can form heat exchange contact.

[0033] In practical use, the liquid hydrogen pipeline 20 is used to supply hydrogen fuel to the engine 22. The liquid hydrogen working fluid is supplied by the liquid hydrogen Dewar flask 14 through a self-pressurization method. The liquid hydrogen enters the liquid hydrogen primary heat exchanger 18 and the liquid hydrogen secondary heat exchanger 7, utilizing its latent heat of vaporization to provide cooling to the heat exchangers. Finally, it enters the engine 22 in a normal temperature gas state for combustion to generate heat. A buffer tank can be installed between the third shut-off valve 15 and the engine 22 to ensure a stable supply of hydrogen to the engine 22 during different flight phases. The liquid hydrogen pipeline 20 also needs to be wrapped with high-performance insulation material to reduce cooling loss and prevent icing on the outside of the pipeline. The opening and closing of the liquid hydrogen pipeline 20 is controlled by the third cryogenic shut-off valve 19, the first cryogenic shut-off valve 8, and the third shut-off valve 15.

[0034] As a preferred embodiment of the present invention, both the liquid hydrogen primary heat exchanger 18 and the liquid hydrogen secondary heat exchanger 7 adopt plate-fin heat exchangers. The design calculations were carried out according to the heat exchange requirements of cold and hot flow. After the liquid hydrogen exchanges heat with the high-temperature exhaust gas and coolant through the liquid hydrogen primary heat exchanger 18 and the liquid hydrogen secondary heat exchanger 7 respectively, it vaporizes and rises to the intake temperature requirement of the engine 22.

[0035] In a preferred embodiment of the present invention, the entire liquid hydrogen Dewar flask 14 should be kept sealed and wrapped with high-performance insulation material. Since the liquid hydrogen Dewar flask 14 contains liquid hydrogen and the Dewar flask is prone to heat leakage, a safety valve 10 is installed on the liquid hydrogen Dewar flask 14 to ensure safe internal pressure and prevent danger caused by excessive internal pressure. The safety valve 10 is externally connected to the inner cavity of the liquid hydrogen Dewar flask 14 via a pipeline. When the pressure in the inner cavity exceeds the safe range, the safety valve 10 automatically opens to release the overpressure hydrogen gas inside the liquid hydrogen Dewar flask 14.

[0036] In this invention, engine 22 requires coolant to control its temperature and maintain it within its normal operating range. Specifically, coolant outlet pipe 17 is sequentially connected to engine 22, fourth shut-off valve 16, and liquid hydrogen secondary heat exchanger 7, used to deliver higher-temperature coolant to liquid hydrogen secondary heat exchanger 7 to provide heat for liquid hydrogen vaporization and heating. That is, engine 22 is connected to another heat exchange channel of liquid hydrogen secondary heat exchanger 7 via coolant outlet pipe 17, which is sequentially connected to fourth shut-off valve 16. Coolant return pipe 21 is sequentially connected to liquid hydrogen secondary heat exchanger 7, first shut-off valve 5, and engine 22, used to deliver lower-temperature coolant to engine 22 to cool it down. That is, the outlet of the pipe in liquid hydrogen secondary heat exchanger 7 connected to coolant outlet pipe 17 is sequentially connected to first shut-off valve 5 and engine 22 via coolant return pipe 21, i.e., engine 22, coolant outlet pipe 17, liquid hydrogen secondary heat exchanger 7, and coolant return pipe 21 are sequentially connected and form a coolant circulation loop.

[0037] In this invention, the engine exhaust pipe 23 is sequentially connected to the engine 22, the fifth shut-off valve 24, the liquid hydrogen primary heat exchanger 18, the second cryogenic shut-off valve 11, the dryer 12, and the exhaust gas buffer tank 4, and is used to cool the high-temperature exhaust gas generated by the engine 22 to room temperature and store it in the exhaust gas buffer tank 4. That is, the exhaust gas generating end of the engine 22 is sequentially connected to the fifth shut-off valve 24, another heat exchange pipe of the liquid hydrogen primary heat exchanger 18, the second cryogenic shut-off valve 11, the dryer 12, and the exhaust gas buffer tank 4 through the engine exhaust pipe 23.

[0038] In a preferred embodiment of the present invention, the high-temperature exhaust gas generated by the engine 22 originates from the combustion of hydrogen fuel. The main components of the high-temperature exhaust gas are water vapor, nitrogen, a small amount of nitrogen oxides, and oxygen. The high-temperature exhaust gas enters the liquid hydrogen primary heat exchanger 18 from the engine 22 to provide heat to the heat exchanger. Then, at a temperature higher than the water vapor dew point, it passes through the second low-temperature shut-off valve 11 into the dryer 12 to remove moisture, preventing the water vapor from reacting with nitrogen oxides after liquefaction to generate acidic substances that could damage pipelines and equipment. Finally, the exhaust gas is stored in the exhaust gas buffer tank 4.

[0039] In this invention, to prevent hydrogen leaks in the aircraft equipment compartment from causing combustion and explosion accidents that endanger aircraft safety, it is necessary to dilute and disperse the leaked hydrogen in a timely manner. This invention provides two oxygen-deficient exhaust gas discharge lines on the exhaust gas buffer tank 4, including a small-flow purging line 6 and a large-flow purging line 9. The small-flow discharge line 6 is connected sequentially to the exhaust gas buffer tank 4, the back pressure valve 3, and the vent 2, and is used to passively discharge purging gas at a small flow rate. The back pressure valve 3 automatically opens and releases exhaust gas from the top of the equipment compartment 26 through the vent 2 when the pressure inside the exhaust gas buffer tank 4 exceeds a specific pressure, i.e., when it exceeds the set pressure of the back pressure valve 3. In actual use, when the pressure inside the buffer tank 4 exceeds the set pressure of the back pressure valve 3, the oxygen-deficient exhaust gas is discharged through the vent 2 to the top of the aircraft equipment compartment 26, diluting the hydrogen gas that has accumulated at the top after leaking from the pipeline, and filling the equipment compartment as a protective gas. The high-flow discharge pipeline 9 is connected in sequence to the buffer tank 4, the second shut-off valve 13, and the exhaust port 25, and is used to actively discharge purge gas at a high flow rate. The second shut-off valve 13 can be remotely controlled and is used to actively and quickly discharge exhaust gas from the bottom of the equipment compartment 26 in the event of a large hydrogen leak, so as to dilute and purge the leaked hydrogen.

[0040] In a preferred embodiment of the present invention, a hydrogen concentration sensor 1 is installed on the top of the equipment compartment 26 for real-time monitoring of the hydrogen concentration inside the equipment compartment. The hydrogen concentration sensor 1 can be interlocked with the second shut-off valve 13, and the opening and closing of the second shut-off valve 13 can be controlled based on the signal value obtained from the hydrogen concentration sensor 1. For example, when the hydrogen concentration sensor reading exceeds 0.5%, the second shut-off valve 13 will automatically open. When the hydrogen concentration sensor reading is below 0.5%, the second shut-off valve 13 will automatically close.

[0041] In a preferred embodiment of the present invention, both the liquid hydrogen Dewar flask 14 and the liquid hydrogen pipeline 20 are insulated with polyurethane foam.

[0042] Utilizing the aforementioned hydrogen leak ventilation system for hydrogen-powered aircraft, this invention also provides a method for diluting and purging hydrogen leaks, the method of which is as follows:

[0043] The third cryogenic shut-off valve 19, the first cryogenic shut-off valve 8, and the third shut-off valve 15 are pre-opened. Utilizing the initial heat from the liquid hydrogen pipeline 20, a small amount of liquid hydrogen in the liquid hydrogen Dewar flask 14 is vaporized and heated sequentially through the third cryogenic shut-off valve 19, the first-stage liquid hydrogen heat exchanger 18, the first cryogenic shut-off valve 8, the second-stage liquid hydrogen heat exchanger 7, and the third shut-off valve 15 before entering the engine 22. The engine 22 is ignited and started. The fifth shut-off valve 24 and the second cryogenic shut-off valve 11 are opened. The high-temperature exhaust gas generated by the engine 22 enters the first-stage liquid hydrogen heat exchanger 18 through the engine exhaust pipeline 23. After exchanging heat with the liquid hydrogen, the temperature drops to above the dew point temperature. It then passes through the dryer 12 to remove moisture and finally enters the exhaust gas buffer tank 4 for storage. At the same time, the cooling system of engine 22 is started, opening the fourth shut-off valve 16 and the first shut-off valve 5. The coolant flows between the engine 22, the coolant outlet pipe 17, the liquid hydrogen secondary heat exchanger 7 and the coolant return pipe 21 to form a circulation loop. The heat generated by engine 22 is transferred to the liquid hydrogen in liquid hydrogen pipe 20 through liquid hydrogen secondary heat exchanger 7, causing the liquid hydrogen to vaporize and heat up to meet the intake requirements of engine 22.

[0044] Under conditions where there is no obvious leakage in the liquid hydrogen pipeline 20, the exhaust gas generated by the engine 22 continuously enters the exhaust gas buffer tank 4 through the engine exhaust gas pipeline 23 for storage, and the pressure inside the tank continuously increases. When the pressure inside the exhaust gas buffer tank 4 reaches the set pressure of the back pressure valve 3, the back pressure valve 3 opens, and the exhaust gas buffer tank 4 discharges oxygen-deficient exhaust gas through the small-flow purging pipeline 6 to the vent 2 located at the top of the equipment compartment. The reduction in oxygen content will significantly narrow the range of flammable and explosive hydrogen concentrations. Ultimately, the equipment compartment 26 is filled with oxygen-deficient exhaust gas, which serves as a protective gas to prevent hydrogen combustion and explosion accidents.

[0045] In the event of a significant leak in the liquid hydrogen pipeline 20, the hydrogen concentration inside the equipment compartment 26 increases dramatically. The second shut-off valve 13, interlocked with the hydrogen concentration sensor 1 inside the equipment compartment 26, automatically opens, releasing a large amount of oxygen-deficient exhaust gas through the high-flow-rate purging pipeline 9 to the exhaust port 25 located at the bottom of the equipment compartment 26. This rapidly dilutes and disperses the leaked hydrogen, reducing the risk of combustion and explosion. At this point, the third cryogenic shut-off valve 19 must also be closed promptly to stop the liquid hydrogen supply.

[0046] In other words, the present invention is based on the above. Figure 1 The hydrogen leak ventilation system shown can be further described as a hydrogen leak dilution and purging method using the ventilation system. This method has two operating modes based on the severity of the hydrogen leak: Mode 1 is used when there is no obvious hydrogen leak in the equipment compartment, and Mode 2 is used when there is an obvious hydrogen leak in the equipment compartment. The two operating modes are as follows:

[0047] (1) Operating Mode 1: The third cryogenic shut-off valve 19, the first cryogenic shut-off valve 8, and the third shut-off valve 15 are pre-opened. The initial heat from the liquid hydrogen pipeline 20 is used to vaporize a small amount of liquid hydrogen and raise its temperature before it enters the engine 22. The engine 22 is ignited and started. The fifth shut-off valve 24 and the second cryogenic shut-off valve 11 are opened. The exhaust gas generated enters the liquid hydrogen primary heat exchanger 18 through the engine exhaust pipeline 23 and exchanges heat with the liquid hydrogen. After exchanging heat with the liquid hydrogen, the temperature drops to above the dew point temperature. Then, the dryer 12 removes moisture and the exhaust gas is stored in the exhaust gas buffer tank. At the same time, the engine cooling system is started. The fourth shut-off valve 16 and the first shut-off valve 5 are opened. The coolant circulates between the engine 22, the coolant outlet pipeline 17, the coolant return pipeline 21, and the liquid hydrogen secondary heat exchanger 7. The heat generated by the engine is transferred to the liquid hydrogen through the liquid hydrogen secondary heat exchanger 7, causing the liquid hydrogen to vaporize and raise its temperature to meet the intake requirements of the engine 22. The exhaust gas produced by the engine continuously enters the exhaust gas buffer tank 4, causing the pressure inside the tank to rise steadily. When the pressure reaches the set pressure of the back pressure valve 3, the back pressure valve 3 opens, and the exhaust gas buffer tank 4 discharges oxygen-deficient exhaust gas to the top of the equipment compartment through the small-flow purging pipeline 6, the back pressure valve 3, and the vent 2. The reduced oxygen content significantly narrows the range of flammable and explosive hydrogen concentrations. Ultimately, the equipment compartment is filled with oxygen-deficient exhaust gas, which acts as a protective gas to prevent hydrogen combustion and explosion accidents.

[0048] (2) Operating Mode Two: The third cryogenic shut-off valve 19, the first cryogenic shut-off valve 8, and the third shut-off valve 15 are pre-opened. The initial heat from the liquid hydrogen pipeline 20 is used to vaporize a small amount of liquid hydrogen and raise its temperature before it enters the engine 22. The engine 22 is ignited and started. The fifth shut-off valve 24 and the second cryogenic shut-off valve 11 are opened. The exhaust gas generated enters the liquid hydrogen primary heat exchanger 18 through the engine exhaust pipeline 23 and exchanges heat with the liquid hydrogen. After exchanging heat with the liquid hydrogen, the temperature drops to above the dew point temperature. Then, the dryer 12 removes moisture and the exhaust gas is stored in the exhaust gas buffer tank. At the same time, the engine cooling system is started. The fourth shut-off valve 16 and the first shut-off valve 5 are opened. The coolant circulates between the engine 22, the coolant outlet pipeline 17, the coolant return pipeline 21, and the liquid hydrogen secondary heat exchanger 7. The heat generated by the engine is transferred to the liquid hydrogen through the liquid hydrogen secondary heat exchanger 7, causing the liquid hydrogen to vaporize and raise its temperature to meet the intake requirements of the engine 22. In the event of a significant leak in the hydrogen pipeline, the hydrogen concentration inside the equipment compartment increases dramatically. The second shut-off valve 13 of the high-flow-rate discharge pipeline, interlocked with hydrogen concentration sensor 1, automatically opens, releasing a large amount of oxygen-deficient exhaust gas through exhaust port 25 at the bottom of the equipment compartment in a short period. This rapidly dilutes and disperses the leaked hydrogen, reducing the risk of combustion and explosion. At this time, the third cryogenic shut-off valve 19 at the liquid hydrogen Dewar outlet must also be closed promptly to stop the liquid hydrogen supply.

[0049] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A hydrogen leak ventilation system for hydrogen-powered aircraft, characterized in that, Including liquid hydrogen pipeline (20), coolant outflow pipeline (17), coolant return pipeline (21), engine exhaust pipeline (23), low flow purging pipeline (6), and high flow purging pipeline (9); The liquid hydrogen pipeline (20) is connected in sequence to the liquid hydrogen Dewar flask (14), the third cryogenic shut-off valve (19), the liquid hydrogen primary heat exchanger (18), the first cryogenic shut-off valve (8), the liquid hydrogen secondary heat exchanger (7), the third shut-off valve (15), and the engine (22). It is used to absorb heat from the liquid hydrogen primary heat exchanger (18) and the liquid hydrogen secondary heat exchanger (7) to vaporize the liquid hydrogen and raise its temperature, so as to provide fuel for the engine (22). The coolant outlet pipe (17) is connected in sequence to the engine (22), the fourth shut-off valve (16) and the liquid hydrogen secondary heat exchanger (7), and is used to transport the coolant at a higher temperature to the liquid hydrogen secondary heat exchanger (7) to provide heat for the liquid hydrogen vaporization and heating. The coolant return pipeline (21) is connected in sequence to the liquid hydrogen secondary heat exchanger (7), the first shut-off valve (5) and the engine (22), and is used to deliver coolant at a lower temperature to the engine (22) to cool it down; The engine exhaust pipe (23) is connected in sequence to the engine (22), the fifth shut-off valve (24), the liquid hydrogen primary heat exchanger (18), the second low temperature shut-off valve (11), the dryer (12) and the exhaust gas buffer tank (4), and is used to cool the high temperature exhaust gas generated by the engine (22) to room temperature and store it in the exhaust gas buffer tank (4). The low-flow purging pipeline (6) is connected in sequence to the tail gas buffer tank (4), the back pressure valve (3) and the vent (2), and is used to passively discharge the purging gas at a low flow rate; the high-flow purging pipeline (9) is connected in sequence to the buffer tank (4), the second shut-off valve (13) and the exhaust port (25), and is used to actively discharge the purging gas at a high flow rate.

2. A hydrogen leak ventilation system for a hydrogen-powered aircraft according to claim 1, characterized in that, All components of the system are located in the equipment compartment (26) of the hydrogen-powered aircraft.

3. A hydrogen leakage ventilation system for a hydrogen-powered aircraft according to claim 2, characterized in that, The top of the equipment compartment (26) is equipped with a hydrogen concentration sensor (1) that is interlocked with the second shut-off valve (13). The opening and closing of the second shut-off valve (13) can be controlled based on the signal value obtained by the hydrogen concentration sensor (1).

4. A hydrogen leak ventilation system for a hydrogen-powered aircraft according to claim 1, characterized in that, Both the liquid hydrogen primary heat exchanger (18) and the liquid hydrogen secondary heat exchanger (7) are plate-fin heat exchangers, which can exchange heat with the high-temperature exhaust gas and coolant respectively and then vaporize and heat up to meet the intake temperature requirements of the engine (22).

5. A hydrogen leak ventilation system for a hydrogen-powered aircraft according to claim 1, characterized in that, Both the liquid hydrogen Dewar flask (14) and the liquid hydrogen pipeline (20) are insulated with polyurethane foam.

6. A hydrogen leak ventilation system for a hydrogen-powered aircraft according to claim 1, characterized in that, The set pressure of the back pressure valve (3) is the exhaust pressure of the engine (22).

7. A hydrogen leak ventilation system for a hydrogen-powered aircraft according to claim 1, characterized in that, The liquid hydrogen dewar (14) uses a self-pressurizing method to increase the pressure inside the tank to supply liquid hydrogen, and its inner cavity is connected to a safety valve (10) through a pipeline to ensure the safety of the internal pressure.

8. A hydrogen leak ventilation system for a hydrogen-powered aircraft according to claim 1, characterized in that, The high-temperature exhaust gas produced by the engine (22) comes from the combustion of hydrogen fuel.

9. A hydrogen leak ventilation system for a hydrogen-powered aircraft according to claim 1, characterized in that, The high-temperature exhaust gas generated by the engine (22) is cooled by the liquid hydrogen primary heat exchanger (18) and its temperature is slightly higher than the dew point temperature.

10. A method for diluting and purging hydrogen leaks using the hydrogen leak ventilation system for hydrogen-powered aircraft as described in any one of claims 1 to 9, characterized in that, Specifically as follows: The third cryogenic shut-off valve (19), the first cryogenic shut-off valve (8), and the third shut-off valve (15) are opened in advance. Using the initial heat of the liquid hydrogen pipeline (20), a small amount of liquid hydrogen in the liquid hydrogen Dewar flask (14) is vaporized and heated through the third cryogenic shut-off valve (19), the first-stage liquid hydrogen heat exchanger (18), the first cryogenic shut-off valve (8), the second-stage liquid hydrogen heat exchanger (7), and the third shut-off valve (15) and then enters the engine (22). When the engine (22) is ignited and started, the fifth shut-off valve (24) and the second low-temperature shut-off valve (11) are opened. The high-temperature exhaust gas generated by the engine (22) enters the liquid hydrogen primary heat exchanger (18) through the engine exhaust pipe (23) and exchanges heat with liquid hydrogen. After the temperature drops to above the dew point temperature, it passes through the dryer (12) to remove moisture and finally enters the exhaust gas buffer tank (4) for storage. At the same time, the cooling system of the engine (22) is started and the fourth shut-off valve (16) and the first shut-off valve (5) are opened. The coolant flows between the engine (22), the coolant outlet pipe (17), the liquid hydrogen secondary heat exchanger (7) and the coolant return pipe (21) to form a circulation loop. The heat generated by the engine (22) is transferred to the liquid hydrogen in the liquid hydrogen pipe (20) through the liquid hydrogen secondary heat exchanger (7) to vaporize the liquid hydrogen and raise its temperature to meet the intake requirements of the engine (22). Under the condition that there is no obvious leakage in the liquid hydrogen pipeline (20), the exhaust gas generated by the engine (22) continuously enters the exhaust gas buffer tank (4) through the engine exhaust gas pipeline (23) and is stored there. The pressure inside the tank continues to rise. When the pressure inside the exhaust gas buffer tank (4) reaches the set pressure of the back pressure valve (3), the back pressure valve (3) opens and the exhaust gas buffer tank (4) discharges oxygen-deficient exhaust gas to the vent (2) located at the top of the equipment compartment through the small flow purging pipeline (6). The reduction in oxygen content will significantly reduce the range of flammable and explosive hydrogen concentration. Finally, the equipment compartment (26) is filled with oxygen-deficient exhaust gas, which serves as a protective gas to prevent hydrogen combustion and explosion accidents. When a significant leak occurs in the liquid hydrogen pipeline (20), the hydrogen concentration in the equipment compartment (26) increases dramatically. The second shut-off valve (13), which is interlocked with the hydrogen concentration sensor (1) in the equipment compartment (26), automatically opens and releases a large amount of oxygen-deficient tail gas to the exhaust port (25) at the bottom of the equipment compartment (26) through the high-flow purging pipeline (9) in a short time. This rapidly dilutes and diffuses the leaked hydrogen, reducing the risk of combustion and explosion. At this time, the third cryogenic shut-off valve (19) must also be closed in time to stop the supply of liquid hydrogen.

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