A liquid hydrogen supply system and supply method for a drone hydrogen fuel cell

Abstract

The present invention discloses a liquid hydrogen supply system and a supply method for a UAV hydrogen fuel cell. The supply system includes a liquid hydrogen storage tank, and an internal tank for containing liquid hydrogen is arranged inside the liquid hydrogen storage tank. A flexible electric heater covering the bottom of the internal tank is provided outside the internal tank; the internal tank determines the gasification mode of the liquid hydrogen in the internal tank based on a pressurization strategy; the hydrogen in the liquid hydrogen storage tank squeezes the liquid hydrogen to pass through a first heat exchanger and a second heat exchanger in sequence under the control of a first regulating valve for gasification, and the gasified hydrogen generated by the second heat exchanger enters two branches; the hydrogen in the first branch reduces the pressure to the hydrogen pressure required by the fuel cell through a pressure reducing valve; the hydrogen in the second branch returns to the internal tank via the third regulating valve and the one-way valve to realize self-pressurization of the internal tank. The supply system simplifies the supply system and improves the storage weight ratio of the whole system.

Description

Technical Field

[0001] The present invention relates to the field of new energy unmanned aerial vehicles, and particularly to a liquid hydrogen gas supply system and a gas supply method for a hydrogen fuel cell of an unmanned aerial vehicle. Background Art

[0002] Compared with lithium batteries, fuel cells have higher energy density. The characteristics of low noise, pollution-free and long flight time of fuel cell unmanned aerial vehicles make them widely used in various fields. Moreover, they have low thermal infrared characteristics and are not easily detected, which is very suitable for long-term reconnaissance missions. Currently, the most commonly used fuel cell on unmanned aerial vehicles is the proton exchange membrane fuel cell, whose reaction temperature is suitable for the working environment of unmanned aerial vehicles, and it has relatively high energy density and power density.

[0003] There are few reports on the research of liquid hydrogen fuel unmanned aerial vehicles, and most of them are in the experimental stage. "Global Observer" is an unmanned aerial vehicle system with high altitude and long endurance developed by AeroVironment, Inc. in the United States, and it is the world's first unmanned aerial vehicle powered by liquid hydrogen fuel. During the test conducted at Edwards Air Force Base in 2011, it used liquid hydrogen fuel throughout the whole process for the first time, with a flight altitude of 1500 m and a continuous flight time of 4 h. In 2010, the unmanned aerial vehicle "Ghost Eye" developed by Boeing completed its first autonomous flight, and in 2013, it achieved a continuous flight of 4.5 h at an altitude of 8400 m. In 2019, MetaVista Company in South Korea jointly developed a four-rotor fuel cell unmanned aerial vehicle with Intelligent Energy, a fuel cell engineering company in the UK, and achieved a flight time of 12 h 7 min 5 s, breaking the world record for the flight time of multi-rotor unmanned aerial vehicles. This four-rotor unmanned aerial vehicle uses a 6L ultra-light liquid hydrogen storage tank and an 800W light fuel cell power module of Intelligent Energy to provide power for the unmanned aerial vehicle.

[0004] At present, domestic enterprises and research institutions have gradually carried out research on unmanned aerial vehicles with high-pressure hydrogen storage fuel cell power systems, but there is no relevant research on unmanned aerial vehicles using liquid hydrogen reported. Currently, there are still many problems with fuel cell unmanned aerial vehicles, such as low power density of fuel cells, slow response speed, low hydrogen storage density, which is not conducive to aircraft design, and the energy control device and control method of fuel cell hybrid unmanned aerial vehicles, etc.

[0005] The present invention designs a liquid hydrogen gas supply system and a gas supply method for a hydrogen fuel cell of an unmanned aerial vehicle, which can comprehensively utilize the waste heat of the hydrogen fuel cell, has a high storage-to-weight ratio, and can be used for the liquid hydrogen gas supply system on unmanned aerial vehicles, filling the technical gap in this field in China. Summary of the Invention

[0006] In view of this, the present invention provides a liquid hydrogen gas supply system and a gas supply method for a hydrogen fuel cell of an unmanned aerial vehicle, which can solve the technical problem of low hydrogen storage density in the liquid hydrogen gas supply system of existing unmanned aerial vehicles.

[0007] To solve the above technical problems, the present invention is implemented as follows.

[0008] A liquid hydrogen supply system for a drone hydrogen fuel cell, comprising:

[0009] A liquid hydrogen storage tank, inside which there is an inner tank for containing liquid hydrogen. The inner tank is used to hold liquid hydrogen, and outside the inner tank there is a flexible electric heater covering the bottom of the inner tank. The electric heater is used to initially vaporize the liquid hydrogen in the liquid hydrogen storage tank according to the pressure change in the inner tank, and determine the heating duration and heating temperature of the inner tank.

[0010] The inner tank generates vaporized hydrogen based on a pressurization strategy, and determines the vaporization mode of the liquid hydrogen in the inner tank based on the pressurization strategy; the electric heater initially vaporizes the liquid hydrogen in the liquid hydrogen storage tank, and the hydrogen in the liquid hydrogen storage tank squeezes the liquid hydrogen to sequentially pass through a first heat exchanger and a second heat exchanger for vaporization under the control of a first regulating valve. The first heat exchanger is used to preheat the squeezed liquid hydrogen using the waste heat of the drone motor; the second heat exchanger uses the waste heat generated by the fuel cell to vaporize the squeezed liquid hydrogen; the vaporized hydrogen generated by the second heat exchanger enters two branches, and the amount of hydrogen entering each branch is adjusted and distributed by the second regulating valve and the third regulating valve according to the amount of hydrogen required by the fuel cell during the actual flight of the drone and the amount of hydrogen required for the self-pressurization of the inner tank; the hydrogen in the first branch is reduced in pressure to the hydrogen pressure required by the fuel cell through a pressure reducing valve, and the volume and speed of the vaporized hydrogen entering the fuel cell are controlled by the second regulating valve; the hydrogen in the second branch returns to the inner tank via the third regulating valve and the one-way valve for realizing the self-pressurization of the inner tank.

[0011] Preferably, the remaining space in the inner tank forms a gas phase space after removing the space occupied by the liquid hydrogen; based on the pressure in the gas phase space, a pressure sensor is deployed in the inner tank to obtain the pressure of the inner tank; based on the reading of the pressure sensor, the pressurization strategy is implemented.

[0012] Preferably, the boosting strategy is as follows: in the initial gas supply stage, direct heating is performed using an electric heater; based on the pressure change in the internal tank, the heating duration and heating temperature of the electric heater are determined; when the pressure in the internal tank reaches dynamic equilibrium, self-boosting of the internal tank is adopted, and at this time, the electric heater is turned off; the hydrogen gas amounts in the two branches are adjusted and distributed by the second regulating valve and the third regulating valve according to the hydrogen gas amount required by the fuel cell during the actual flight of the unmanned aerial vehicle and the hydrogen gas amount required for self-boosting of the internal tank; when the hydrogen gas amount required by the fuel cell is insufficient, a gas supply method combining direct electric heating and self-boosting is adopted, and based on the hydrogen gas amount required by the fuel cell, the heating duration and heating temperature of the electric heater are determined for gasification.

[0013] Preferably, the extruded liquid hydrogen flows through two-stage heat exchange, and its cold energy is respectively used for cooling the superconducting system and dissipating heat from the fuel cell, and the waste heat of the superconducting system and the fuel cell is used to increase the temperature for gasification. After gasification, the hydrogen gas is divided into two paths: one path flows through a pressure reducing valve and a regulating valve to the fuel cell as its raw material, and its flow rate is the hydrogen gas flow rate required by the fuel cell under the current working load; the remaining hydrogen gas flows into the other path and flows back to the upper gas phase space of the liquid hydrogen storage tank through a one-way valve, gradually increasing the pressure in the upper space of the container. When the pressure of the hydrogen gas in this path reaches the boosting pressure of the liquid hydrogen storage tank and is sufficient to maintain the continuous extrusion of the liquid hydrogen in the storage tank, the electric heater is turned off, and all the boosting is carried out by the hydrogen gas in the pipeline.

[0014] Preferably, the liquid hydrogen storage tank adopts an aluminum alloy column tank with an actual geometric volume greater than 20 L and a storage weight greater than 10%, and the liquid hydrogen storage tank is clamped to the head cabin of the unmanned aerial vehicle.

[0015] Preferably, a finned tube vaporizer is deployed at the heat dissipation outlet of the fuel cell. The fuel cell is deployed in the head cabin of the unmanned aerial vehicle, and the finned tube vaporizer is used to convert liquid hydrogen into hydrogen gas.

[0016] A liquid hydrogen gas supply method for a hydrogen fuel cell of an unmanned aerial vehicle, using the liquid hydrogen gas supply system of the hydrogen fuel cell of the unmanned aerial vehicle as described above, the gas supply method includes the following steps:

[0017] Step S1: The electric heater obtains the pressure change in the internal tank of the liquid hydrogen gas supply system of the hydrogen fuel cell of the unmanned aerial vehicle;

[0018] Step S2: Based on the boosting strategy, determine the boosting method of the liquid hydrogen gas supply system of the hydrogen fuel cell of the unmanned aerial vehicle;

[0019] Step S3: Based on the boosting method, adjust the states of the electric heater and the one-way valve, so that a part of the liquid hydrogen in the internal tank is extruded under the action of pressure and gasified;

[0020] Step S4: Determine the amount of hydrogen entering the first branch and the second branch based on the amount of hydrogen required by the fuel cell 8 during the actual flight of the drone and the amount of hydrogen required for self-pressurization of the internal tank.

[0021] Step S5: Supply hydrogen gas from the first branch to the fuel cell.

[0022] Beneficial effects:

[0023] The liquid hydrogen gas supply system and gas supply method for the drone hydrogen fuel cell of the present invention...

[0024] Have the following technical effects:

[0025] (1) The present invention adopts a liquid hydrogen gas supply system, which can provide long-term and stable hydrogen supply.

[0026] (2) The present invention effectively utilizes the waste heat of the superconducting motor and the fuel cell, simplifies the gas supply system, and improves the storage weight ratio of the entire system. The present invention determines the branch for hydrogen rewarming, and uses the waste heat of the superconducting motor and the fuel cell for liquid hydrogen gasification and pressurization through reasonable pipeline design and layout.

[0027] (3) The present invention selects an aluminum alloy column tank with an actual geometric volume greater than 20L, which can meet the airborne requirements of an actual liquid hydrogen drone, not only meets the shape and size of the loading cabin of the liquid hydrogen drone, but also has a high storage weight ratio.

[0028] (4) The present invention designs a finned tube gasification heat exchanger, which is arranged at the heat dissipation outlet of the fuel cell, making the most of the hot air from the fuel cell heat dissipation.

[0029] (5) The present invention is provided with electric heating in the liquid hydrogen storage tank, and the hydrogen supply amount can be changed by adjusting the heating power to ensure stable hydrogen supply. Description of the drawings

[0030] Figure 1(A) is a schematic diagram of the Ghost Eye drone of the prior art.

[0031] Figure 1(B) is a schematic diagram of the liquid hydrogen storage tank of the prior art.

[0032] Figure 2 is a schematic structural diagram of the liquid hydrogen gas supply system for the drone hydrogen fuel cell provided by the present invention.

[0033] Figure 3 is a schematic structural diagram of the heat exchanger provided by the present invention.

[0034] Description of the reference numerals:

[0035] 1: Liquid hydrogen storage tank;

[0036] 2: Electric heater;

[0037] 3: Liquid hydrogen;

[0038] 4: Hydrogen;

[0039] 5: First regulating valve;

[0040] 6: First heat exchanger;

[0041] 7: Second heat exchanger;

[0042] 8: Fuel cell;

[0043] 9: Pressure reducing valve;

[0044] 10: Second regulating valve;

[0045] 11: Third regulating valve;

[0046] 12: Check valve. Detailed implementation mode

[0047] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0048] As Figure 2 shown, the present invention provides a liquid hydrogen supply system for an unmanned aerial vehicle hydrogen fuel cell, including:

[0049] A liquid hydrogen storage tank 1, an internal tank for containing liquid hydrogen is provided inside the liquid hydrogen storage tank 1, the internal tank is used for storing liquid hydrogen, and a flexible electric heater 2 covering the bottom of the internal tank is arranged outside the internal tank. The electric heater 2 is used to initially vaporize the liquid hydrogen 3 in the liquid hydrogen storage tank 1 according to the pressure change in the internal tank, and determine the heating duration and heating temperature of the internal tank;

[0050] The internal tank generates gasified hydrogen based on a pressurization strategy, and determines the gasification method of the liquid hydrogen in the internal tank according to the pressurization strategy; the electric heater 2 initially gasifies the liquid hydrogen 3 in the liquid hydrogen storage tank 1, and the hydrogen gas 4 in the liquid hydrogen storage tank 1 squeezes the liquid hydrogen 3 to sequentially pass through the first heat exchanger 6 and the second heat exchanger 7 under the control of the first regulating valve 5 for gasification. The first heat exchanger 6 is used to preheat the squeezed liquid hydrogen by using the waste heat of the UAV motor; the second heat exchanger 7 gasifies the squeezed liquid hydrogen by using the waste heat generated by the fuel cell 8; the gasified hydrogen generated by the second heat exchanger 7 enters two branches, and the amount of hydrogen gas entering each branch is adjusted and distributed by the second regulating valve 10 and the third regulating valve 11 according to the amount of hydrogen gas required by the fuel cell 8 during the actual flight of the UAV and the amount of hydrogen gas required for the self-pressurization of the internal tank; the hydrogen gas in the first branch is reduced in pressure to the hydrogen gas pressure required by the fuel cell 8 through the pressure reducing valve 9, and the volume and speed of the gasified hydrogen entering the fuel cell 8 are controlled by the second regulating valve 10; the hydrogen gas in the second branch returns to the internal tank through the third regulating valve 11 and the one-way valve 12 for realizing the self-pressurization of the internal tank.

[0051] In the present invention, the remaining space forms a gas phase space after removing the space occupied by the liquid hydrogen in the internal tank. Based on the pressure in the gas phase space, a pressure sensor is deployed in the internal tank to obtain the pressure of the internal tank. Based on the reading of the pressure sensor, the pressurization strategy is implemented.

[0052] The pressurization strategy is as follows: in the initial gas supply stage, direct heating is adopted by the electric heater 2; based on the pressure change in the internal tank, the heating duration and heating temperature of the electric heater 2 are determined; when the pressure in the internal tank reaches dynamic equilibrium, self-pressurization of the internal tank is adopted, and at this time, the electric heater 2 is turned off; the amount of hydrogen gas in the two branches is adjusted and distributed by the second regulating valve 10 and the third regulating valve 11 according to the amount of hydrogen gas required by the fuel cell 8 during the actual flight of the UAV and the amount of hydrogen gas required for the self-pressurization of the internal tank; when the amount of hydrogen gas required by the fuel cell 8 is insufficient, a gas supply mode combining direct electric heating and self-pressurization is adopted, and based on the amount of hydrogen gas required by the fuel cell 8, the heating duration and heating temperature of the electric heater 2 are determined for gasification.

[0053] In the present invention, the extruded liquid hydrogen flows through two-stage heat exchange, and its cooling capacity is respectively used for cooling the superconducting system and dissipating heat from the fuel cell 8, and the waste heat of the superconducting system and the fuel cell 8 is used to heat and vaporize the hydrogen. After vaporization, the hydrogen 4 is divided into two paths: one path flows through the pressure reducing valve 9 and the regulating valve 10 to the fuel cell 8 as its raw material, and its flow rate is the hydrogen flow rate required by the fuel cell 8 under the current working load; the remaining hydrogen flows into the other path and flows back to the upper gas phase space of the liquid hydrogen storage tank 1 through the one-way valve 12, gradually increasing the pressure in the upper space of the container. When the pressure of the hydrogen in this path reaches the pressurization pressure of the liquid hydrogen storage tank 1 and is sufficient to maintain the continuous extrusion of the liquid hydrogen 3 in the storage tank, the electric heater 2 is turned off, and the hydrogen 4 in the pipeline is used for pressurization entirely.

[0054] Furthermore, considering the shape and size of the cabin of the unmanned aerial vehicle comprehensively in the present invention, the liquid hydrogen storage tank 1 adopts an aluminum alloy column tank with an actual geometric volume greater than 20L and a storage weight greater than 10%. The liquid hydrogen storage tank 1 is clamped to the head cabin of the unmanned aerial vehicle. The liquid hydrogen storage tank 1 of the present invention can fully meet the gas supply requirements of the liquid hydrogen unmanned aerial vehicle.

[0055] Furthermore, as Figure 3 shown, a finned tube vaporizer is deployed at the heat dissipation outlet of the fuel cell 8. The fuel cell 8 is deployed in the head cabin of the unmanned aerial vehicle. The finned tube vaporizer is used to convert liquid hydrogen into hydrogen. In the present invention, in combination with the hydrogen fuel cell layout of the unmanned aerial vehicle and using the fuel cell fan for heat dissipation, a liquid hydrogen vaporizer is designed. The vaporizer adopts a finned tube vaporizer, uses copper tubes for heat exchange, and is used to convert liquid hydrogen into hydrogen. The vaporizer is arranged at the fuel cell heat dissipation outlet and uses the hot air from the fuel cell heat dissipation as the heat source.

[0056] The present invention is provided with electric heating in the liquid hydrogen storage tank, which is used for the vaporization of liquid hydrogen during initial startup and when the vaporization capacity of the vaporizer is insufficient, and by adjusting the heating power, the hydrogen supply is increased.

[0057] The present invention provides a method for supplying liquid hydrogen to a hydrogen fuel cell of an unmanned aerial vehicle, which uses the liquid hydrogen supply system of the hydrogen fuel cell of the unmanned aerial vehicle as described above. The gas supply method includes the following steps:

[0058] Step S1: The electric heater obtains the pressure change in the inner tank of the liquid hydrogen supply system of the hydrogen fuel cell of the unmanned aerial vehicle;

[0059] Step S2: Based on the pressurization strategy, determine the pressurization method of the liquid hydrogen supply system of the hydrogen fuel cell of the unmanned aerial vehicle;

[0060] Step S3: Based on the pressurization method, adjust the states of the electric heater and the one-way valve, so that a part of the liquid hydrogen in the inner tank is extruded under the action of pressure and vaporized;

[0061] Step S4: Determine the amounts of hydrogen gas entering the first branch and the second branch based on the amount of hydrogen gas required by the fuel cell 8 during the actual flight of the drone and the amount of hydrogen gas required for self-pressurization of the internal tank body.

[0062] Step S5: Supply hydrogen gas from the first branch to the fuel cell.

[0063] The above specific embodiments only describe the design principle of the present invention. The shapes and names of the components in this description can be different and are not limited. Therefore, those skilled in the art of the present invention can modify or equivalently replace the technical solutions recorded in the foregoing embodiments; and these modifications and replacements do not depart from the gist and technical solutions of the present invention, and should all fall within the protection scope of the present invention.

Claims

1. A liquid hydrogen supply system for a hydrogen fuel cell of an unmanned aerial vehicle, characterized in that, The gas supply system includes: A liquid hydrogen storage tank (1), inside which there is an inner tank for containing liquid hydrogen. Outside the inner tank, there is a flexible electric heater (2) covering the bottom of the inner tank. The electric heater (2) is used to initially vaporize the liquid hydrogen (3) in the liquid hydrogen storage tank (1) according to the pressure change in the inner tank, and determine the heating duration and heating temperature of the inner tank. The inner tank generates vaporized hydrogen based on a pressurization strategy, and determines the vaporization method of the liquid hydrogen in the inner tank according to the pressurization strategy. The hydrogen (4) in the liquid hydrogen storage tank (1) squeezes the liquid hydrogen (3). Controlled by the first regulating valve (5), the squeezed liquid hydrogen sequentially passes through the first heat exchanger (6) and the second heat exchanger (7). The first heat exchanger (6) is used to preheat the squeezed liquid hydrogen using the waste heat of the UAV motor. The second heat exchanger (7) uses the waste heat generated by the fuel cell (8) to vaporize the squeezed liquid hydrogen. The vaporized hydrogen generated by the second heat exchanger (7) enters two branches. The amount of hydrogen entering each branch is adjusted and distributed by the second regulating valve (10) and the third regulating valve (11) according to the amount of hydrogen required by the fuel cell (8) during the actual flight of the UAV and the amount of hydrogen required for the self-pressurization of the inner tank. The hydrogen in the first branch passes through a pressure reducing valve (9) to reduce the pressure to the hydrogen pressure required by the fuel cell (8), and the volume and speed of the vaporized hydrogen entering the fuel cell (8) are controlled by the second regulating valve (10). The hydrogen in the second branch returns to the inner tank via the third regulating valve (11) and the check valve (12) to achieve the self-pressurization of the inner tank.

2. The gas supply system according to claim 1, characterized in that, The remaining space in the inner tank forms a gas phase space after removing the space occupied by the liquid hydrogen. Based on the pressure in the gas phase space, a pressure sensor is deployed in the inner tank to obtain the pressure of the inner tank. Based on the reading of the pressure sensor, the pressurization strategy is implemented.

3. The air supply system according to any one of claims 1-2, characterized in that, The pressurization strategy is as follows: In the initial gas supply stage, direct heating by the electric heater (2) is adopted. Based on the pressure change in the inner tank, the heating duration and heating temperature of the electric heater (2) are determined. When the pressure in the inner tank reaches dynamic equilibrium, self-pressurization of the inner tank is adopted, and at this time, the electric heater (2) is turned off. The amount of hydrogen in the two branches is adjusted and distributed by the second regulating valve (10) and the third regulating valve (11) according to the amount of hydrogen required by the fuel cell (8) during the actual flight of the UAV and the amount of hydrogen required for the self-pressurization of the inner tank. When the amount of hydrogen required by the fuel cell (8) is insufficient, a gas supply method combining direct electric heating and self-pressurization is adopted, and based on the amount of hydrogen required by the fuel cell (8), the heating duration and heating temperature of the electric heater (2) for vaporization are determined.

4. The gas supply system according to any one of claims 1-2, characterized in that, The extruded liquid hydrogen flows through two-stage heat exchange, and its cooling capacity is respectively used for cooling the superconducting system and dissipating heat from the fuel cell (8). The waste heat of the superconducting system and the fuel cell (8) is used to heat up and gasify the liquid hydrogen. After gasification, the hydrogen gas (4) is divided into two paths: one path flows through a pressure reducing valve (9) and a regulating valve (10) to the fuel cell (8) as its raw material, and its flow rate is the hydrogen gas flow rate required by the fuel cell (8) under the current working load; the remaining hydrogen gas flows into the other path and flows back to the upper gas phase space of the liquid hydrogen storage tank (1) through a one-way valve (12), gradually increasing the pressure in the upper space of the container. When the pressure of the hydrogen gas in this path reaches the pressurization pressure of the liquid hydrogen storage tank (1) and is sufficient to maintain the continuous extrusion of the liquid hydrogen (3) in the storage tank, the electric heater (2) is turned off, and the pressurization is entirely carried out by the hydrogen gas (4) in the pipeline.

5. The air supply system according to any one of claims 1-2, characterized in that, The liquid hydrogen storage tank (1) is an aluminum alloy column tank with an actual geometric volume greater than 20L and a storage weight greater than 10%. The liquid hydrogen storage tank (1) is clamped to the head cabin of the unmanned aerial vehicle.

6. The gas supply system according to any one of claims 1-2, characterized in that, A finned tube vaporizer is deployed at the heat dissipation outlet of the fuel cell (8). The fuel cell (8) is deployed in the head cabin of the unmanned aerial vehicle. The finned tube vaporizer is used to convert liquid hydrogen into hydrogen gas.

7. A method for supplying liquid hydrogen to a hydrogen fuel cell of an unmanned aerial vehicle, using the liquid hydrogen supply system for the hydrogen fuel cell of the unmanned aerial vehicle according to any one of claims 1-6, characterized in that, The gas supply method includes the following steps: Step S1: The electric heater obtains the pressure change in the inner tank of the liquid hydrogen gas supply system of the hydrogen fuel cell of the unmanned aerial vehicle. Step S2: Based on the pressurization strategy, determine the pressurization method of the liquid hydrogen gas supply system of the hydrogen fuel cell of the unmanned aerial vehicle. Step S3: Based on the pressurization method, adjust the states of the electric heater and the one-way valve, so that a part of the liquid hydrogen in the inner tank is extruded under the action of pressure and gasified. Step S4: Based on the amount of hydrogen gas required by the fuel cell during the actual flight of the unmanned aerial vehicle and the amount of hydrogen gas required for self-pressurization of the inner tank, determine the amount of hydrogen gas entering the first branch and the second branch. Step S5: Supply gas to the fuel cell from the first branch.

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