Liquid hydrogen emergency discharge system for recovering engine waste heat and control method

Abstract

The application provides a liquid hydrogen emergency discharge system for recovering engine waste heat and a control method, and relates to the technical field of liquid hydrogen application. The application provides a liquid hydrogen emergency discharge system for recovering engine waste heat and a control method, and relates to the technical field of liquid hydrogen application. The liquid hydrogen storage tank assembly, the liquid hydrogen storage tank exhaust pipeline, the liquid hydrogen storage tank emergency exhaust pipeline, the liquid hydrogen storage tank safety valve exhaust pipeline, the engine high-temperature tail gas cooling exhaust pipeline, the liquid hydrogen rewarming heat insulation pipeline, the engine high-temperature tail gas introduction control valve, the liquid hydrogen cabin external discharge port, the liquid hydrogen storage tank emergency liquid discharge pipeline and the liquid hydrogen storage tank normal liquid delivery pipeline are connected with the liquid hydrogen storage tank assembly. The liquid hydrogen storage tank emergency exhaust pipeline and the liquid hydrogen storage tank safety valve exhaust pipeline are connected with the gas outlet end of the liquid hydrogen storage tank exhaust pipeline. Through the liquid hydrogen discharge system, the tail gas waste heat of the aero-engine is utilized to rewarm the low-temperature hydrogen gas discharged in an emergency, so that the low-temperature freezing damage of other equipment caused by the low-temperature hydrogen gas discharged in an emergency is avoided.

Description

Technical Field

[0001] This invention relates to the field of liquid hydrogen application technology, specifically to a liquid hydrogen emergency emission system and control method for recovering waste heat from engines. Background Technology

[0002] The development of aerial platforms such as unmanned aerial vehicles, low-altitude rotary-wing aircraft, and large aircraft using liquid hydrogen fuel is one of the important development directions for low-carbon, environmentally friendly, and advanced aviation technologies.

[0003] However, when an aircraft experiences an in-flight emergency and needs to evacuate fuel and reduce weight for a safe landing, the large amount of cold energy carried by the fuel system in its compact space layout during the emergency evacuation of liquid hydrogen can cause the ambient temperature in and around the evacuation system to drop too low, which may affect the safe operation of other equipment on the aircraft. Therefore, it is necessary to introduce a heat source to reheat the liquid hydrogen before evacuation.

[0004] The exhaust temperature of aircraft engines is generally above 500°C. Some of the heat can be recovered and introduced into the liquid hydrogen emission system to reheat the liquid hydrogen discharged in emergencies. To achieve this heat recovery and reheating process, there is an urgent need to design a highly efficient heat exchange system between the aircraft engine exhaust port and the liquid hydrogen emission system. Summary of the Invention

[0005] In view of this, the embodiments of this specification provide a liquid hydrogen emergency discharge system and control method for recovering engine waste heat, so as to utilize the waste heat carried by the exhaust gas of the aircraft engine to reheat the liquid hydrogen to be discharged in an emergency, thereby avoiding low temperature freezing damage to other aircraft equipment during the emergency discharge of liquid hydrogen.

[0006] The embodiments in this specification provide the following technical solutions: An emergency liquid hydrogen emission system for recovering waste heat from an engine includes: Liquid hydrogen storage tank components, liquid hydrogen storage tank exhaust pipe, liquid hydrogen storage tank emergency exhaust pipe, liquid hydrogen storage tank safety valve outlet pipe, engine high temperature exhaust gas cooling exhaust pipe, liquid hydrogen reheating insulation pipe, engine high temperature exhaust gas inlet control valve, liquid hydrogen engine compartment external exhaust port, liquid hydrogen storage tank emergency drain pipe and liquid hydrogen storage tank normal liquid delivery pipe. The inlet end of the venting pipe of the liquid hydrogen storage tank, the outlet end of the normal liquid delivery pipe of the liquid hydrogen storage tank, and the inlet end of the emergency drain pipe of the liquid hydrogen storage tank are all connected to the liquid hydrogen storage tank assembly. The inlet end of the emergency vent pipe of the liquid hydrogen storage tank and the inlet end of the outlet pipe of the safety valve of the liquid hydrogen storage tank are both connected to the outlet end of the vent pipe of the liquid hydrogen storage tank. The liquid outlet of the emergency drain pipeline of the liquid hydrogen storage tank, the gas outlet of the safety valve of the liquid hydrogen storage tank, and the gas outlet of the emergency exhaust pipeline of the liquid hydrogen storage tank are all connected to the first gas inlet of the liquid hydrogen reheating and heat insulation pipeline, and the liquid hydrogen engine room external discharge port is connected to the first gas outlet of the liquid hydrogen reheating and heat insulation pipeline. The outlet of the engine high-temperature exhaust gas inlet control valve is connected to the second inlet of the liquid hydrogen reheating and heat insulation pipeline. After the engine high-temperature exhaust gas is cooled down, the inlet of the exhaust pipeline is connected to the second outlet of the liquid hydrogen reheating and heat insulation pipeline.

[0007] Furthermore, the liquid hydrogen rewarming insulation pipeline includes: The reheating and insulation pipeline consists of a cryogenic hydrogen pipeline, an engine exhaust pipeline, an insulation layer, and a vacuum tube, arranged sequentially from the center outwards. The reheated and insulated pipeline for engine exhaust gas is attached to the reheated and insulated pipeline for low-temperature hydrogen exchange. The rewarm insulated pipeline for low-temperature hydrogen is used as an exhaust pipeline to supply low-temperature hydrogen, while the rewarm insulated pipeline for engine exhaust is used as an intake pipeline to supply high-temperature exhaust gas from the engine. The airflow direction of the rewarm insulated pipeline for engine exhaust is opposite to that of the rewarm insulated pipeline for low-temperature hydrogen.

[0008] Furthermore, the insulation layer of the reheat insulation pipeline includes multiple layers of insulation material; The thermal insulation layer of the thermal insulation pipeline and the vacuum tube of the thermal insulation pipeline constitute a vacuum multi-layer thermal insulation structure. The vacuum multi-layer thermal insulation structure is used to prevent the high temperature of the engine exhaust gas and the low temperature of the low temperature hydrogen from being transferred to the outer surface of the liquid hydrogen thermal insulation pipeline. The outlet of the cryogenic hydrogen pipeline with thermal insulation is equipped with a cryogenic temperature sensor, which is used to measure the temperature of cryogenic hydrogen.

[0009] Furthermore, the liquid hydrogen emission system also includes: Safety valve for liquid hydrogen storage tank, emergency vent control valve for liquid hydrogen storage tank, emergency drain control valve for liquid hydrogen storage tank, and normal liquid delivery system for liquid hydrogen storage tank; The safety valve of the liquid hydrogen storage tank is installed on the gas outlet pipeline of the liquid hydrogen storage tank safety valve. The emergency vent control valve for the liquid hydrogen storage tank is installed on the emergency vent pipeline of the liquid hydrogen storage tank. The emergency drainage pipeline for liquid hydrogen storage tanks includes an emergency drainage pipeline for a first liquid hydrogen storage tank and an emergency drainage pipeline for a second liquid hydrogen storage tank. An emergency drainage control valve for liquid hydrogen storage tanks is located between the emergency drainage pipelines for the first liquid hydrogen storage tank and the emergency drainage pipelines for the second liquid hydrogen storage tank. The outlet end of the normal liquid delivery pipeline of the liquid hydrogen storage tank is connected to the normal liquid delivery system of the liquid hydrogen storage tank.

[0010] Furthermore, the liquid hydrogen storage tank assembly includes: Liquid hydrogen storage tank outer shell and liquid hydrogen storage tank inner liner; The outer shell of the liquid hydrogen storage tank is fitted onto the outside of the inner liner of the liquid hydrogen storage tank.

[0011] A control method for a liquid hydrogen emergency emission system, the method being used to control a liquid hydrogen emergency emission system that recovers waste heat from an engine, includes the following steps: The opening or closing of the liquid hydrogen storage tank emergency vent control valve, the liquid hydrogen storage tank emergency drain control valve, and the liquid hydrogen storage tank safety valve is determined based on the pressure value inside the liquid hydrogen storage tank and the aircraft operating conditions. The temperature of the low-temperature hydrogen is measured by a low-temperature temperature sensor, and the opening and closing of the control valve for introducing high-temperature exhaust gas from the engine is controlled based on the temperature of the low-temperature hydrogen.

[0012] Furthermore, the opening or closing of the liquid hydrogen storage tank emergency vent control valve, the liquid hydrogen storage tank emergency drain control valve, and the liquid hydrogen storage tank safety valve are determined based on the pressure value inside the liquid hydrogen storage tank and the aircraft operating conditions, including: When the aircraft is operating under normal liquid hydrogen delivery conditions, the emergency vent control valve and the emergency drain control valve of the liquid hydrogen storage tank are closed, and the fuel liquid hydrogen enters the normal liquid delivery system of the liquid hydrogen storage tank through the normal liquid delivery pipeline of the liquid hydrogen storage tank. When the pressure inside the liquid hydrogen storage tank exceeds the opening pressure of the emergency exhaust control valve, the emergency exhaust control valve automatically opens. The cryogenic hydrogen enters the liquid hydrogen reheating and heat insulation pipeline through the liquid hydrogen storage tank safety valve outlet pipeline, exchanges heat with the high-temperature exhaust gas of the engine, and then enters the liquid hydrogen engine compartment exhaust port and is discharged outside the engine compartment. If the pressure inside the liquid hydrogen storage tank exceeds the safe working pressure after the emergency vent control valve is opened, the cryogenic hydrogen will enter the liquid hydrogen reheating insulation pipeline through the liquid hydrogen storage tank emergency vent line and the liquid hydrogen storage tank emergency vent control valve. After exchanging heat with the high-temperature exhaust gas from the engine, the hydrogen will enter the liquid hydrogen engine compartment exhaust port and be discharged outside the engine compartment.

[0013] Furthermore, it also includes: When the aircraft is in an emergency, the emergency drain control valve of the liquid hydrogen storage tank is opened. The cryogenic hydrogen passes through the emergency drain pipeline of the second liquid hydrogen storage tank, the emergency drain control valve of the liquid hydrogen storage tank, and the emergency drain pipeline of the first liquid hydrogen storage tank. After entering the liquid hydrogen reheating insulation pipeline, it exchanges heat with the high-temperature exhaust gas of the engine and then enters the liquid hydrogen external discharge port of the cabin and is discharged outside the cabin.

[0014] Furthermore, the temperature of the cryogenic hydrogen is measured using a cryogenic temperature sensor, and the opening and closing of the engine's high-temperature exhaust gas introduction control valve is controlled based on the cryogenic hydrogen temperature, including: When the emitted low-temperature hydrogen enters the rewarm insulation pipeline, the engine high-temperature exhaust gas enters the rewarm insulation pipeline through the engine high-temperature exhaust gas introduction control valve. The temperature of the cryogenic hydrogen is measured by a cryogenic temperature sensor. The opening of the engine high-temperature exhaust gas inlet control valve is controlled by a PID controller. If the temperature of the cryogenic hydrogen is lower than the target temperature, the opening of the engine high-temperature exhaust gas inlet control valve is increased; if the temperature of the cryogenic hydrogen is higher than the target temperature, the opening of the engine high-temperature exhaust gas inlet control valve is decreased.

[0015] Furthermore, the opening degree of the engine high-temperature exhaust gas introduction control valve is controlled by a PID controller, including: Calculate the output of the PID controller ,in, This represents the difference between the temperature of the cryogenic hydrogen gas measured by the cryogenic temperature sensor and the target temperature value. The proportional gain of the PID controller. The integral coefficient of the PID controller. The derivative coefficients of the PID controller are... To find the differential, and All times are time; The output of the PID controller This is used as the opening value of the control valve for the introduction of high-temperature exhaust gas from the engine.

[0016] Compared with the prior art, the beneficial effects that at least one technical solution adopted in the embodiments of this specification can achieve include at least: A liquid hydrogen emission system that recovers waste heat from aircraft engines is constructed. By utilizing the waste heat from the exhaust gas of aircraft engines, the liquid hydrogen (cryogenic hydrogen) to be discharged in an emergency is reheated. At the same time, a vacuum insulation structure is adopted to further reduce the amount of cold entering the outer wall of the liquid hydrogen emergency emission pipeline, thereby avoiding low-temperature freezing damage to other equipment during the emergency emission of liquid hydrogen. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the liquid hydrogen emergency emission system for recovering engine waste heat according to an embodiment of the present invention.

[0019] The attached diagram shows the following labels: 1. Liquid hydrogen storage tank outer shell; 2. Liquid hydrogen storage tank inner liner; 3. Liquid hydrogen storage tank exhaust pipe; 4. Liquid hydrogen storage tank safety valve; 5. Liquid hydrogen storage tank emergency exhaust pipe; 6. Liquid hydrogen storage tank emergency exhaust control valve; 7. Liquid hydrogen storage tank safety valve outlet pipe; 8. Engine high-temperature exhaust gas cooling exhaust pipe; 9. Liquid hydrogen reheating insulation pipe; 901. Reheating insulation pipe vacuum tube; 902. Reheating insulation pipe insulation layer; 903. Reheating insulation pipe engine exhaust gas pipe; 904. Reheating insulation pipe cryogenic hydrogen pipe; 10. Engine high-temperature exhaust gas inlet control valve; 11. Liquid hydrogen engine compartment external vent; 12. First liquid hydrogen storage tank emergency drain pipe; 13. Liquid hydrogen storage tank emergency drain control valve; 14. Second liquid hydrogen storage tank emergency drain pipe; 15. Liquid hydrogen storage tank normal delivery pipe; 16. Liquid hydrogen storage tank normal delivery system. Detailed Implementation

[0020] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] Liquid hydrogen exhaust systems that recover engine waste heat must be resistant to high temperatures and corrosion, and possess excellent thermal conductivity to ensure stable operation under extreme working conditions and effectively transfer heat from exhaust gases to liquid hydrogen. Simultaneously, the size and weight of the device must be considered to meet the stringent requirements of aircraft for lightweight and compact design.

[0023] The liquid hydrogen emission system for recovering engine waste heat in this invention differs from ground-based emergency liquid hydrogen emission systems, which are typically installed in open, unopen locations where the large amount of cooling generated during emission does not cause fatal damage to surrounding equipment. However, in the space-constrained and compact aviation field, the cooling generated during emergency liquid hydrogen emission can lead to excessively low temperatures in the emission pipeline and surrounding environment, affecting the safe operation of other equipment.

[0024] like Figure 1 As shown, a liquid hydrogen emergency discharge system for recovering engine waste heat includes: a liquid hydrogen storage tank assembly, a liquid hydrogen storage tank exhaust pipe 3, a liquid hydrogen storage tank emergency exhaust pipe 5, a liquid hydrogen storage tank safety valve outlet pipe 7, an exhaust pipe 8 for engine high-temperature exhaust gas after cooling, a liquid hydrogen reheating and heat insulation pipe 9, an engine high-temperature exhaust gas inlet control valve 10, a liquid hydrogen engine compartment external discharge port 11, a liquid hydrogen storage tank emergency drain pipe, a liquid hydrogen storage tank normal liquid delivery pipe 15, a liquid hydrogen storage tank safety valve 4, a liquid hydrogen storage tank emergency exhaust control valve 6, a liquid hydrogen storage tank emergency drain control valve 13, and a liquid hydrogen storage tank normal liquid delivery system 16.

[0025] The liquid hydrogen storage tank assembly includes: a liquid hydrogen storage tank outer shell 1 and a liquid hydrogen storage tank inner liner 2. The liquid hydrogen storage tank outer shell 1 is fitted over the outer side of the liquid hydrogen storage tank inner liner 2. That is, the liquid hydrogen storage tank outer shell 1 and the liquid hydrogen storage tank inner liner 2 form a vacuum multi-layered insulated liquid hydrogen storage tank. Other insulation methods can also be used for liquid hydrogen storage tanks, as long as they meet the usage requirements. The tank body material can be stainless steel, aluminum alloy, titanium alloy, or composite material.

[0026] The inlet of the vent pipe 3 of the liquid hydrogen storage tank, the outlet of the normal liquid delivery pipe 15 of the liquid hydrogen storage tank, and the inlet of the emergency drain pipe of the liquid hydrogen storage tank are all connected to the liquid hydrogen storage tank assembly. The inlet of the emergency vent pipe 5 of the liquid hydrogen storage tank and the inlet of the safety valve outlet pipe 7 of the liquid hydrogen storage tank are both connected to the outlet of the vent pipe 3 of the liquid hydrogen storage tank. The liquid outlet of the emergency drain pipeline of the liquid hydrogen storage tank, the gas outlet of the safety valve of the liquid hydrogen storage tank 7, and the gas outlet of the emergency exhaust pipeline of the liquid hydrogen storage tank 5 are all connected to the first gas inlet of the liquid hydrogen reheating and heat insulation pipeline 9, and the liquid hydrogen engine room external discharge port 11 is connected to the first gas outlet of the liquid hydrogen reheating and heat insulation pipeline 9. The outlet of the engine high-temperature exhaust gas inlet control valve 10 is connected to the second inlet of the liquid hydrogen reheating and heat insulation pipe 9. After the engine high-temperature exhaust gas is cooled down, the inlet of the exhaust pipe 8 is connected to the second outlet of the liquid hydrogen reheating and heat insulation pipe 9.

[0027] The safety valve 4 of the liquid hydrogen storage tank is installed on the outlet pipeline 7 of the safety valve of the liquid hydrogen storage tank. The safety valve 4 is a cryogenic safety valve, which can automatically open and close according to the pressure in the inner tank 2 of the liquid hydrogen storage tank. The safety valve 4 can automatically release pressure when the pressure in the inner tank 2 of the liquid hydrogen storage tank exceeds the limit, and automatically close after releasing pressure to a certain level, without the need for electronic control system control.

[0028] The emergency venting control valve 6 for the liquid hydrogen storage tank is installed on the emergency venting pipeline 5 of the liquid hydrogen storage tank.

[0029] The emergency drainage pipeline for the liquid hydrogen storage tank includes a first liquid hydrogen storage tank emergency drainage pipeline 12 and a second liquid hydrogen storage tank emergency drainage pipeline 14. The emergency drainage control valve 13 for the liquid hydrogen storage tank is located between the first liquid hydrogen storage tank emergency drainage pipeline 12 and the second liquid hydrogen storage tank emergency drainage pipeline 14.

[0030] The liquid hydrogen storage tank venting pipeline 3, the liquid hydrogen storage tank emergency venting pipeline 5, the liquid hydrogen storage tank safety valve venting pipeline 7, the first liquid hydrogen storage tank emergency drain pipeline 12, the second liquid hydrogen storage tank emergency drain pipeline 14, and the liquid hydrogen storage tank normal delivery pipeline 15 are all cryogenic transmission pipelines with a vacuum multi-layer insulation structure. They can also be cryogenic transmission pipelines with other insulation methods, as long as they meet the usage requirements. The pipeline body material can be stainless steel, aluminum alloy, titanium alloy, or composite material. It can be a rigid pipe or a flexible pipe, and cryogenic joints can be installed in the middle as needed.

[0031] Both the emergency venting control valve 6 and the emergency draining control valve 13 of the liquid hydrogen storage tank are cryogenic control valves, while the high-temperature exhaust gas inlet control valve 10 of the engine is a high-temperature control valve. It can be understood that the cryogenic control valves 6 and 13, which can be pneumatically or electrically operated, meet the requirements for liquid hydrogen use and are controlled by the control system. The high-temperature exhaust gas inlet control valve 10, which can be pneumatically or electrically operated, meets the pressure and temperature requirements for engine exhaust gas.

[0032] After the engine exhaust gas cools down at high temperatures, exhaust pipe 8 is a single-layer pipe, which only needs to meet the pressure and temperature requirements after the exhaust gas cools down. The outlet of the normal liquid delivery pipeline 15 of the liquid hydrogen storage tank is connected to the normal liquid delivery system 16 of the liquid hydrogen storage tank.

[0033] like Figure 1 As shown, the principle of the liquid hydrogen rewarming insulation pipeline 9 is to utilize a vacuum multi-layer insulation structure with a small overall heat transfer coefficient and good insulation performance to reduce the impact of low temperature on external equipment. Simultaneously, it utilizes the heat exchange principle of a shell-and-tube heat exchanger to achieve the rewarming of liquid hydrogen and low-temperature hydrogen gas. The liquid hydrogen rewarming insulation pipeline 9 includes: The following components are arranged sequentially from the center outwards: low-temperature hydrogen pipeline 904, engine exhaust pipeline 903, insulation layer 902, and vacuum tube 901. The reheat insulation pipeline engine exhaust pipeline 903 and the reheat insulation pipeline low temperature hydrogen pipeline 904 are attached and exchange heat.

[0034] The rewarming insulated low-temperature hydrogen pipeline 904 is used as an exhaust pipeline to provide low-temperature hydrogen (liquid hydrogen), and the rewarming insulated engine exhaust pipeline 903 is used as an intake pipeline to provide high-temperature exhaust gas from the engine. The airflow direction of the rewarming insulated engine exhaust pipeline 903 is opposite to that of the rewarming insulated low-temperature hydrogen pipeline 904.

[0035] The thermal insulation layer 902 of the reheat insulation pipeline comprises multiple layers of insulation material. This multi-layer insulation material is a composite of a highly reflective radiant screen and lightweight, low-thermal-conductivity spacers. The radiant screen can be aluminum foil or aluminized film with aluminum spraying on both sides (or one side); the spacers are mainly composed of low-thermal-conductivity, lightweight, and thin materials, such as fiberglass cloth, nylon mesh, fiber paper, and mesh-type spacers. Multiple layers of radiant screens and spacers are alternately stacked to form a multi-layer insulation material with low thermal conductivity.

[0036] The thermal insulation layer 902 and the vacuum tube 901 of the thermal insulation pipeline form a vacuum multi-layer insulation structure. This structure prevents the high temperature of the engine exhaust gas and the low temperature of the hydrogen from being transferred to the outer surface of the liquid hydrogen thermal insulation pipeline 9. The pipeline body can be made of stainless steel, aluminum alloy, titanium alloy, or composite materials. The thermal insulation layer 902 and the vacuum tube 901 together ensure that the high temperature of the engine exhaust gas and the low temperature of the emitted hydrogen are not transferred to the outer surface of the pipeline.

[0037] To prevent the exhaust temperature from causing frost damage to the equipment, a low-temperature temperature sensor is installed at the outlet of the cryogenic hydrogen pipeline 904 in the reheat insulation pipeline. The low-temperature temperature sensor is used to measure the temperature of the cryogenic hydrogen gas. The low-temperature temperature sensor can measure the temperature range of liquid hydrogen to room temperature (20-310 K).

[0038] A method for controlling a liquid hydrogen emission system includes the following steps: The opening or closing of the liquid hydrogen storage tank emergency vent control valve 6, the liquid hydrogen storage tank emergency drain control valve 13, and the liquid hydrogen storage tank safety valve 4 is determined based on the pressure value inside the inner liner 2 of the liquid hydrogen storage tank and the aircraft operating conditions. The temperature of the low-temperature hydrogen is measured by a low-temperature temperature sensor, and the opening and closing size of the engine high-temperature exhaust gas introduction control valve 10 is controlled based on the temperature of the low-temperature hydrogen.

[0039] Specifically, the opening or closing of the liquid hydrogen storage tank emergency vent control valve 6, the liquid hydrogen storage tank emergency drain control valve 13, and the liquid hydrogen storage tank safety valve 4 is determined based on the pressure value inside the liquid hydrogen storage tank liner 2 and the aircraft operating conditions, including: When the aircraft is operating under normal liquid hydrogen delivery conditions, the emergency vent control valve 6 and the emergency drain control valve 13 of the liquid hydrogen storage tank are closed, and the fuel liquid hydrogen enters the normal liquid delivery system 16 of the liquid hydrogen storage tank through the normal liquid delivery pipeline 15 of the liquid hydrogen storage tank. When the pressure inside the inner liner 2 of the liquid hydrogen storage tank exceeds the opening pressure of the emergency exhaust control valve 6 of the liquid hydrogen storage tank, the emergency exhaust control valve 6 of the liquid hydrogen storage tank will open automatically. The cryogenic hydrogen will enter the liquid hydrogen reheating and heat insulation pipeline 9 through the outlet pipeline 7 of the liquid hydrogen storage tank safety valve. After exchanging heat with the high temperature exhaust gas of the engine, it will enter the liquid hydrogen engine compartment exhaust port 11 and be discharged outside the engine compartment. If the pressure inside the inner liner 2 of the liquid hydrogen storage tank is greater than the safe working pressure after the emergency exhaust control valve 6 of the liquid hydrogen storage tank is opened, the cryogenic hydrogen gas enters the liquid hydrogen reheating and heat insulation pipeline 9 through the emergency exhaust pipeline 5 and the emergency exhaust control valve 6 of the liquid hydrogen storage tank and exchanges heat with the high temperature exhaust gas of the engine before entering the liquid hydrogen engine compartment external discharge port 11 and being discharged outside the engine compartment. When the aircraft is in an emergency, the emergency drain control valve 13 of the liquid hydrogen storage tank is opened. The cryogenic hydrogen passes through the emergency drain pipeline 14 of the second liquid hydrogen storage tank, the emergency drain control valve 13 of the liquid hydrogen storage tank, and the emergency drain pipeline 12 of the first liquid hydrogen storage tank. After exchanging heat with the high-temperature exhaust gas of the engine, the hydrogen enters the liquid hydrogen external discharge port 11 and is discharged outside the cabin.

[0040] Specifically, the temperature of the cryogenic hydrogen is measured by a cryogenic temperature sensor, and the opening and closing of the engine's high-temperature exhaust gas introduction control valve 10 is controlled based on the temperature of the cryogenic hydrogen, including: When the emitted low-temperature hydrogen enters the low-temperature hydrogen pipeline 904 of the thermal insulation pipeline, the high-temperature exhaust gas from the engine enters the engine exhaust gas pipeline 903 of the thermal insulation pipeline through the engine high-temperature exhaust gas introduction control valve 10. The temperature of the low-temperature hydrogen is measured by a low-temperature temperature sensor. The opening of the engine high-temperature exhaust gas inlet control valve 10 is controlled by a PID controller. If the temperature of the low-temperature hydrogen is lower than the target temperature, the opening of the engine high-temperature exhaust gas inlet control valve 10 is increased. If the temperature of the low-temperature hydrogen is higher than the target temperature (the target temperature is generally set between 0-30℃), the opening of the engine high-temperature exhaust gas inlet control valve 10 is decreased.

[0041] Specifically, the opening degree of the engine high-temperature exhaust gas introduction control valve 10 is controlled by a PID controller, including: Calculate the output of the PID controller ,in, This represents the difference between the temperature of the cryogenic hydrogen gas measured by the cryogenic temperature sensor and the target temperature value. The proportional gain of the PID controller. The integral coefficient of the PID controller. The derivative coefficients of the PID controller are... To find the differential, and All times are time; The output of the PID controller The opening value of the engine high-temperature exhaust gas introduction control valve 10.

[0042] In a PID controller, a suitable tuning is achieved. , and This enables the controller to quickly and stably control the exhaust temperature, ensuring that other equipment will not be damaged by freezing during emergency liquid hydrogen discharge.

[0043] Beneficial effects of the embodiments of the present invention: This invention provides a liquid hydrogen emission system that recovers waste heat from aircraft engines. By utilizing the waste heat from the engine exhaust to reheat the liquid hydrogen being emitted in an emergency, it avoids the low-temperature hazards of direct emission of cryogenic liquid hydrogen and recovers the engine's waste heat, improving energy efficiency. Simultaneously, the system employs a vacuum multi-layer insulation structure with a low overall heat transfer coefficient and excellent insulation performance to further reduce the amount of cold entering the outer wall of the emergency liquid hydrogen emission pipeline, preventing low-temperature freezing damage to other equipment during emergency emission. Utilizing the heat exchange principle of a shell-and-tube heat exchanger, and through precise control of the heat exchange process, it ensures that the liquid hydrogen reaches a suitable temperature before emergency emission, thereby guaranteeing the safe operation of other equipment on the aircraft and promoting the further development of low-carbon, environmentally friendly, and advanced aviation technologies.

[0044] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any substitution of equivalent components or equivalent changes and modifications made within the scope of protection of this patent should still fall within the scope of this patent. Furthermore, the technical features, technical features and technical solutions, and technical solutions in this invention can be freely combined and used.

Claims

1. A liquid hydrogen emergency discharge system for recovering engine waste heat, characterized in that, include: Liquid hydrogen storage tank assembly, liquid hydrogen storage tank exhaust pipe (3), liquid hydrogen storage tank emergency exhaust pipe (5), liquid hydrogen storage tank safety valve outlet pipe (7), engine high temperature exhaust gas cooling exhaust pipe (8), liquid hydrogen reheating insulation pipe (9), engine high temperature exhaust gas inlet control valve (10), liquid hydrogen engine compartment external discharge port (11), liquid hydrogen storage tank emergency drain pipe and liquid hydrogen storage tank normal liquid delivery pipe (15). The air inlet of the liquid hydrogen storage tank exhaust pipe (3), the liquid outlet of the liquid hydrogen storage tank normal liquid delivery pipe (15), and the liquid inlet of the liquid hydrogen storage tank emergency drain pipe are all connected to the liquid hydrogen storage tank assembly. The inlet end of the emergency exhaust pipe (5) of the liquid hydrogen storage tank and the inlet end of the safety valve exhaust pipe (7) of the liquid hydrogen storage tank are both connected to the outlet end of the exhaust pipe (3) of the liquid hydrogen storage tank. The liquid outlet of the emergency drain pipe of the liquid hydrogen storage tank, the gas outlet of the safety valve of the liquid hydrogen storage tank (7), and the gas outlet of the emergency exhaust pipe of the liquid hydrogen storage tank (5) are all connected to the first gas inlet of the liquid hydrogen reheating and heat insulation pipe (9), and the liquid hydrogen engine room external discharge port (11) is connected to the first gas outlet of the liquid hydrogen reheating and heat insulation pipe (9). The outlet of the engine high-temperature exhaust gas inlet control valve (10) is connected to the second inlet of the liquid hydrogen reheating insulation pipe (9), and the inlet of the engine high-temperature exhaust gas after cooling is connected to the second outlet of the liquid hydrogen reheating insulation pipe (9). The liquid hydrogen reheating insulation pipeline (9) includes: The following are arranged sequentially from the center outwards: low-temperature hydrogen pipeline (904), engine exhaust pipeline (903), insulation layer (902), and vacuum tube (901). The reheat insulation pipeline engine exhaust pipeline (903) and the reheat insulation pipeline low temperature hydrogen pipeline (904) are attached to each other and exchange heat. The rewarming insulated low-temperature hydrogen pipeline (904) is used as an exhaust pipeline to provide low-temperature hydrogen, and the rewarming insulated engine exhaust pipeline (903) is used as an intake pipeline to provide high-temperature exhaust gas from the engine. The airflow direction of the rewarming insulated engine exhaust pipeline (903) is opposite to the airflow direction of the rewarming insulated low-temperature hydrogen pipeline (904). The thermal insulation layer (902) of the reheat insulation pipeline includes multiple layers of thermal insulation material; The thermal insulation layer (902) of the thermal insulation pipeline and the vacuum tube (901) of the thermal insulation pipeline constitute a vacuum multilayer thermal insulation structure. The vacuum multilayer thermal insulation structure is used to prevent the high temperature of the engine exhaust gas and the low temperature of the low temperature hydrogen gas from being transferred to the outer surface of the liquid hydrogen thermal insulation pipeline (9).

2. The liquid hydrogen emergency emission system for recovering engine waste heat according to claim 1, characterized in that, The outlet of the cryogenic hydrogen pipeline (904) of the reheat insulation pipeline is equipped with a cryogenic temperature sensor, which is used to measure the temperature of cryogenic hydrogen.

3. The liquid hydrogen emergency emission system for recovering engine waste heat according to claim 1, characterized in that, The liquid hydrogen emergency discharge system also includes: Liquid hydrogen storage tank safety valve (4), liquid hydrogen storage tank emergency vent control valve (6), liquid hydrogen storage tank emergency drain control valve (13) and liquid hydrogen storage tank normal liquid delivery system (16). The safety valve (4) of the liquid hydrogen storage tank is installed on the gas outlet pipeline (7) of the safety valve of the liquid hydrogen storage tank; The emergency venting control valve (6) of the liquid hydrogen storage tank is installed on the emergency venting pipeline (5) of the liquid hydrogen storage tank; The liquid hydrogen storage tank emergency drainage pipeline includes a first liquid hydrogen storage tank emergency drainage pipeline (12) and a second liquid hydrogen storage tank emergency drainage pipeline (14), and the liquid hydrogen storage tank emergency drainage control valve (13) is located between the first liquid hydrogen storage tank emergency drainage pipeline (12) and the second liquid hydrogen storage tank emergency drainage pipeline (14). The outlet end of the normal liquid delivery pipeline (15) of the liquid hydrogen storage tank is connected to the normal liquid delivery system (16) of the liquid hydrogen storage tank.

4. The liquid hydrogen emergency emission system for recovering engine waste heat according to claim 1, characterized in that, Liquid hydrogen storage tank components include: Liquid hydrogen storage tank outer shell (1) and liquid hydrogen storage tank inner liner (2); The outer shell (1) of the liquid hydrogen storage tank is fitted onto the outside of the inner liner (2) of the liquid hydrogen storage tank.

5. A control method for a liquid hydrogen emergency emission system, the control method being used to control the liquid hydrogen emergency emission system for recovering engine waste heat as described in any one of claims 1 to 4, characterized in that, Includes the following steps: The opening or closing of the liquid hydrogen storage tank emergency vent control valve (6), the liquid hydrogen storage tank emergency drain control valve (13), and the liquid hydrogen storage tank safety valve (4) is determined based on the pressure value inside the liquid hydrogen storage tank liner (2) and the aircraft operating conditions. The temperature of the low-temperature hydrogen is measured by a low-temperature temperature sensor, and the opening and closing size of the engine high-temperature exhaust gas introduction control valve (10) is controlled based on the temperature of the low-temperature hydrogen.

6. The control method for the liquid hydrogen emergency discharge system according to claim 5, characterized in that, The opening or closing of the liquid hydrogen storage tank emergency vent control valve (6), the liquid hydrogen storage tank emergency drain control valve (13), and the liquid hydrogen storage tank safety valve (4) is determined based on the pressure value inside the liquid hydrogen storage tank liner (2) and the aircraft operating conditions, including: When the aircraft is operating under normal liquid hydrogen delivery conditions, the emergency exhaust control valve (6) and the emergency drain control valve (13) of the liquid hydrogen storage tank are closed, and the fuel liquid hydrogen enters the normal delivery system (16) of the liquid hydrogen storage tank through the normal delivery pipeline (15). When the pressure inside the liquid hydrogen storage tank liner (2) is greater than the opening pressure of the liquid hydrogen storage tank emergency exhaust control valve (6), the liquid hydrogen storage tank emergency exhaust control valve (6) will open automatically. Low-temperature hydrogen gas will enter the liquid hydrogen reheating insulation pipeline (9) through the liquid hydrogen storage tank safety valve outlet pipeline (7), exchange heat with the engine high-temperature exhaust gas, and then enter the liquid hydrogen engine compartment external discharge port (11) and be discharged outside the engine compartment. If the pressure value inside the inner liner (2) of the liquid hydrogen storage tank is greater than the safe working pressure value after the emergency exhaust control valve (6) of the liquid hydrogen storage tank is opened, the cryogenic hydrogen gas enters the liquid hydrogen reheating insulation pipeline (9) through the emergency exhaust pipeline (5) and the emergency exhaust control valve (6) of the liquid hydrogen storage tank, exchanges heat with the high temperature exhaust gas of the engine, and then enters the liquid hydrogen engine compartment external discharge port (11) and is discharged outside the engine compartment.

7. The control method for the liquid hydrogen emergency discharge system according to claim 6, characterized in that, Also includes: When the aircraft is in an emergency, the emergency drain control valve (13) of the liquid hydrogen storage tank is opened. The cryogenic hydrogen passes through the emergency drain pipeline (14) of the second liquid hydrogen storage tank, the emergency drain control valve (13) of the liquid hydrogen storage tank, and the emergency drain pipeline (12) of the first liquid hydrogen storage tank. It then enters the liquid hydrogen reheating insulation pipeline (9) to exchange heat with the high-temperature exhaust gas of the engine and reheats before entering the liquid hydrogen cabin exhaust port (11) and being discharged outside the cabin.

8. The control method for the liquid hydrogen emergency discharge system according to claim 5, characterized in that, The temperature of the cryogenic hydrogen is measured by a cryogenic temperature sensor. Based on the temperature of the cryogenic hydrogen, the opening and closing of the engine high-temperature exhaust gas introduction control valve (10) is controlled, including: When the emitted low-temperature hydrogen enters the low-temperature hydrogen pipeline (904) of the thermal insulation pipeline, the high-temperature exhaust gas of the engine enters the thermal insulation pipeline engine exhaust gas pipeline (903) through the engine high-temperature exhaust gas introduction control valve (10). The temperature of the low-temperature hydrogen is measured by a low-temperature temperature sensor. The opening of the engine high-temperature exhaust gas inlet control valve (10) is controlled by a PID controller. If the temperature of the low-temperature hydrogen is lower than the target temperature, the opening of the engine high-temperature exhaust gas inlet control valve (10) is increased. If the temperature of the low-temperature hydrogen is higher than the target temperature, the opening of the engine high-temperature exhaust gas inlet control valve (10) is decreased.

9. The control method for the liquid hydrogen emergency discharge system according to claim 8, characterized in that, The opening degree of the engine high-temperature exhaust gas introduction control valve (10) is controlled by a PID controller, including: Calculate the output of the PID controller ,in, The deviation between the temperature of the cryogenic hydrogen gas measured by the cryogenic temperature sensor and the target temperature value. The proportional gain of the PID controller. The integral coefficient of the PID controller. The derivative coefficients of the PID controller are... To find the differential, and All times are time; The output of the PID controller This is the opening value of the engine high-temperature exhaust gas introduction control valve (10).

Images