Hydrogen-air-hydrogen-oxygen dual-mode critical space fuel cell system

Abstract

The invention belongs to the technical field of hydrogen energy power systems and near space aviation engineering, and particularly relates to a hydrogen-air-hydrogen-oxygen dual-mode critical space fuel cell system. The hydrogen-air-hydrogen-oxygen dual-mode critical space fuel cell system comprises a hydrogen-air supply module, a hydrogen-oxygen supply module, a hydrogen fuel cell system, an open type waste heat recovery device, a heat conduction layer, a hydrogen closed flow channel heat exchanger, an oxygen closed flow channel heat exchanger and a four-opening type gas interface, the hydrogen-air supply module comprises a hydrogen storage bottle, a hydrogen inlet electromagnetic valve device and an air compressor, the hydrogen-oxygen supply module comprises an oxygen bottle and an oxygen conveying control valve, and the hydrogen fuel cell system comprises a hydrogen fuel cell stack, a control system, a hydrogen-air outlet electromagnetic valve, an air compressor electronic speed controller and a lithium battery; the system has higher high-altitude adaptability and energy utilization efficiency, so that the problems of insufficient high-altitude oxygen supply, difficulty in maintaining low temperature, attenuation of galvanic pile efficiency and the like in the prior art are solved.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen energy power system and near-space aerospace engineering technology, and more specifically, it is a hydrogen-air-hydrogen-oxygen dual-modal critical space fuel cell system. Background Technology

[0002] Existing hydrogen fuel cell power systems are mainly designed for ground transportation or low-altitude drone scenarios, and are mostly based on proton exchange membrane fuel cell structures, relying on ambient air oxygen supply to provide the reaction gas. In low-altitude environments of hundreds to thousands of meters, this type of air intake, hydrogen supply, thermal management, and stack operation system built on atmospheric pressure can achieve stable power generation. However, when the aircraft enters near space, the external environment changes significantly. The rapid drop in atmospheric pressure leads to a sharp decrease in oxygen partial pressure, while the ambient temperature drops sharply and the convective heat transfer capacity weakens. This causes a significant decline in the air intake efficiency, reaction rate, and temperature maintenance capability of traditional fuel cell systems. The stack not only cannot continuously output rated power, but also faces problems such as decreased reaction rate, increased risk of water freezing, and difficulty in maintaining system thermal balance. Existing oxygen supply and thermal management schemes that rely on hydrogen-air mode can no longer guarantee the continuous and stable output of the stack.

[0003] To improve oxygen supply in high-altitude environments, some studies have attempted to increase oxygen supply through mechanical pressurization and oxygen tank replenishment. However, these solutions consume too much energy and are limited by the capacity of the oxygen cylinders, making it difficult to meet the needs of long-duration missions. Other technologies have attempted to introduce bottled oxygen into hydrogen-oxygen fuel cells, but this has not yet solved the problem of overall energy efficiency loss in high-altitude environments. The root cause lies in the ineffective recovery and utilization of waste heat in the fuel cell stack's exhaust gas. Hydrogen and oxygen are at low temperatures before entering the reaction, resulting in slow stack heating, reduced reaction activity, and even failure to start or a sudden drop in output in critical environments.

[0004] Meanwhile, existing systems generally employ a single hydrogen-air mode, lacking a comprehensive energy structure capable of being compatible with both hydrogen-air and hydrogen-oxygen dual modes and automatically switching oxygen supply methods according to different altitude conditions. This results in inconsistent operating modes for UAVs in low-altitude and near-space environments. In terms of thermal management and heat exchange, existing technologies often rely on external electric heating devices, failing to establish effective waste heat recovery and reverse heating pathways for exhaust gases. This leads to low thermal management efficiency and low energy utilization. Furthermore, existing heat exchange structures are mostly shell-and-tube or simple flat-plate types, which cannot simultaneously achieve efficient heat exchange, large-area heat conduction, and coordinated design with the hydrogen and oxygen dual-channel structure on weight-constrained aircraft platforms. They also fail to address the structural challenge of achieving a closed and independent hydrogen-oxygen channel while sharing waste heat. Ultimately, this results in prominent problems when hydrogen fuel cell systems are applied in critical spaces, such as unstable oxygen acquisition under rarefied air conditions, difficulty in maintaining the operating temperature range at extremely low temperatures at high altitudes, and significant waste of waste heat in the hydrogen-air mode. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a hydrogen-air and hydrogen-oxygen dual-modal critical space fuel cell system. This invention constructs a hydrogen-air and hydrogen-oxygen dual-modal coupled gas supply system and arranges a sinusoidal waveform open waste heat recovery device on the fuel cell stack exhaust side. This allows the exhaust heat to be transferred via a heat-conducting layer to independent hydrogen and oxygen plate-type flow channels, achieving continuous power output by using hydrogen-air mode at low altitudes and switching to hydrogen-oxygen mode at high altitudes. The plate-type closed flow channel structure described in this invention ensures the isolation between the hydrogen and oxygen pathways. Simultaneously, the stable heat source provided by the sinusoidal waste heat recovery layer maintains the gas temperature, giving the system higher high-altitude adaptability and energy utilization efficiency. This overcomes the problems of insufficient high-altitude oxygen supply, difficulty in maintaining low temperatures, and fuel cell stack efficiency degradation in existing technologies.

[0006] The technical solution adopted by this invention to solve its technical problem is:

[0007] A hydrogen-air-hydrogen-oxygen dual-modal critical space fuel cell system includes a hydrogen-air supply module, a hydrogen-oxygen supply module, a hydrogen fuel cell system, an open waste heat recovery device, a heat-conducting layer, a hydrogen closed-loop heat exchanger, an oxygen closed-loop heat exchanger, and a four-port gas interface.

[0008] The hydrogen-air supply module includes a hydrogen storage cylinder, a hydrogen inlet solenoid valve device and an air compressor; the hydrogen-oxygen supply module includes an oxygen cylinder and an oxygen delivery control valve; the hydrogen fuel cell system includes a hydrogen fuel cell stack, a control system, a hydrogen-air outlet solenoid valve, an air compressor electronic control and a lithium battery; the hydrogen fuel cell stack is provided with a stack cathode side air inlet channel, a stack anode side air inlet channel and a stack exhaust gas outlet channel.

[0009] The open waste heat recovery device has a sinusoidal waveform channel inside. The heat-conducting layer is attached between the open waste heat recovery device and the hydrogen closed flow channel heat exchanger and the oxygen closed flow channel heat exchanger. The hydrogen closed flow channel heat exchanger and the oxygen closed flow channel heat exchanger are assembled back to back and sealed and isolated from each other.

[0010] The four-port gas interface is a circular interface, with hydrogen inlet and outlet and oxygen inlet and outlet respectively, used to realize unidirectional heat exchange and transportation of gas, and avoid backflow or disturbance of hot and cold gas.

[0011] Furthermore, the hydrogen storage cylinder is connected to the hydrogen heat exchange inlet of the hydrogen closed-loop heat exchanger via a hydrogen inlet solenoid valve device, and the hydrogen heat exchange outlet of the hydrogen closed-loop heat exchanger is connected to the anode side air inlet channel of the hydrogen fuel cell stack; the air compressor is selectively connected to the cathode side air inlet channel of the hydrogen fuel cell stack, forming a hydrogen-air supply loop.

[0012] Furthermore, the oxygen cylinder is connected to the oxygen heat exchange inlet of the oxygen closed-loop heat exchanger via an oxygen delivery control valve, and the oxygen heat exchange outlet of the oxygen closed-loop heat exchanger is connected to the inlet channel on the cathode side of the hydrogen fuel cell stack, forming a hydrogen-oxygen supply circuit; the hydrogen-air supply circuit and the hydrogen-oxygen supply circuit are selectively connected through a control system.

[0013] Furthermore, the exhaust gas discharge channel of the hydrogen fuel cell stack is connected to the waste heat side gas inlet of the open waste heat recovery device, and the waste heat side gas outlet of the open waste heat recovery device is set to be open; the sinusoidal waveform channel is used to increase the exhaust gas disturbance and heat exchange area, so that the exhaust gas heat is synchronously transferred to the gas in the hydrogen closed flow channel heat exchanger and the oxygen closed flow channel heat exchanger through the heat conduction layer.

[0014] Furthermore, the flow channel structure of the hydrogen closed-channel heat exchanger and the oxygen closed-channel heat exchanger is a plate design, and both have a closed channel with a baffle path inside. The gas flows in the closed channel in an upward and downward direction, forming a unidirectional flow driven by pressure difference, which avoids gas bag residue.

[0015] Furthermore, the heat-conducting layer is a metal heat-conducting sheet made of high thermal conductivity aluminum, used to evenly diffuse the heat of the exhaust gas absorbed by the open waste heat recovery device, form a stable hot surface and transfer it to the hydrogen closed-loop heat exchanger and the oxygen closed-loop heat exchanger, preventing the hydrogen closed-loop heat exchanger and the oxygen closed-loop heat exchanger from generating thermal stress due to local overheating.

[0016] Furthermore, the control system is electrically connected to the hydrogen inlet solenoid valve, air compressor, oxygen delivery control valve, hydrogen outlet solenoid valve, air compressor electronic speed controller, and lithium battery. It is used to detect environmental parameters and control the switching between the hydrogen-air supply circuit and the hydrogen-oxygen supply circuit, as well as the start and stop of the waste heat recovery function.

[0017] Furthermore, the environmental parameters include atmospheric pressure, oxygen partial pressure, and ambient temperature. When the environment is at low altitude, with sufficient atmospheric pressure and moderate temperature, the control system controls the hydrogen-air supply circuit to be turned on, the hydrogen-oxygen supply circuit to be turned off, and the waste heat recovery function to be on standby, only undertaking a small part of temperature equalization. When the environment is in near-space and the oxygen partial pressure drops to the point where it cannot maintain the fuel cell stack reaction rate, the control system turns off the hydrogen-air supply circuit and turns on the hydrogen-oxygen supply circuit, forming a closed-loop gas supply structure. When the ambient temperature is below zero degrees Celsius, the control system activates the waste heat recovery function.

[0018] Furthermore, the hydrogen exhaust solenoid valve is located on the exhaust side of the hydrogen fuel cell stack and is used to control exhaust in accordance with different operating modes; the lithium battery is used to provide power for system startup and auxiliary equipment operation.

[0019] Furthermore, the open-type waste heat recovery device is located on the outermost layer of the system, and the sinusoidal waveform channel allows the exhaust gas to scour the metal wall under thin-layer turbulence, avoiding the risk of condensation or ice blockage; the hydrogen closed-channel heat exchanger and the oxygen closed-channel heat exchanger obtain heat only through the heat conduction layer, and do not exchange heat with each other, so there is no risk of cross-contamination.

[0020] The beneficial effects of the hydrogen-air-hydrogen-oxygen dual-modal critical space fuel cell system of the present invention are as follows:

[0021] An innovative hydrogen-air and hydrogen-oxygen dual-modal coupled gas supply system is constructed, which can adaptively switch oxygen supply modes according to changes in oxygen partial pressure in the adjacent space. This effectively breaks through the oxygen supply bottleneck in the thin air environment at high altitudes, ensures the continuous and stable output of the fuel cell system under extreme low oxygen conditions, and significantly improves the system's high-altitude adaptability.

[0022] By adopting a sinusoidal waveform open waste heat recovery device and a heat-conducting layer in synergy, the waste heat of the fuel cell stack tail gas is efficiently recovered and directionally transferred, providing a stable heat source for the preheating of hydrogen and oxygen, significantly improving the temperature maintenance effect of the reaction gas in the high-altitude and extremely low-temperature environment, and significantly enhancing the system's thermal management efficiency and low-temperature adaptability.

[0023] The hydrogen-oxygen dual-path sealed plate heat exchanger adopts a back-to-back sealed assembly structure, which ensures complete isolation between the hydrogen and oxygen flow channels and eliminates the risk of cross-contamination. At the same time, the plate flow channel and baffle path design expand the heat exchange contact area, improve heat exchange uniformity and efficiency, and take into account both system safety and energy utilization efficiency.

[0024] It enables seamless switching between low-altitude hydrogen-air mode and high-altitude hydrogen-oxygen mode, and can adapt to different altitude operating conditions without interrupting power output. This solves the problem of disconnect between the low-altitude and near-space operating modes of traditional systems, and effectively extends the mission range and operational coverage of the aircraft.

[0025] By relying on exhaust gas waste heat recovery to replace the traditional external electric heating solution, additional energy consumption is reduced, the temperature control load of the system in extreme environments is reduced, waste heat is avoided, and the energy utilization efficiency of the entire power system is significantly improved, thus achieving energy saving and consumption reduction.

[0026] Based on the principle of hydrogen electrochemical reaction, it emits no pollutants during operation, meeting the environmental protection requirements of low-emission and zero-emission high-altitude platforms, providing a clean and efficient power solution for near-space vehicles, and has good environmental compatibility and application prospects. Attached Figure Description

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and specific implementation methods.

[0028] Figure 1 This is a schematic diagram of a hydrogen-air-hydrogen-oxygen dual-modal critical space fuel cell system.

[0029] Figure 2 This is a partial structural schematic diagram of a hydrogen-air-hydrogen-oxygen dual-modal critical space fuel cell system.

[0030] Figure 3 This is a schematic diagram of an open-type waste heat recovery device.

[0031] Figure 4 This is a schematic diagram of the heat-conducting layer.

[0032] Figure 5 This is a schematic diagram of a closed-loop heat exchanger for hydrogen.

[0033] Figure 6 This is a schematic diagram of a closed-circuit oxygen heat exchanger.

[0034] Figure 7 This is a schematic diagram of an open-type waste heat recovery device.

[0035] Figure 8 This is a schematic diagram of a hydrogen fuel cell system.

[0036] In the diagram: 1. Hydrogen storage cylinder; 2. Hydrogen inlet solenoid valve device; 3. Air compressor; 4. Oxygen cylinder; 5. Oxygen delivery control valve; 6. Control system; 7. Hydrogen outlet solenoid valve; 8. Air compressor electronic controller; 9. Lithium battery; 10. Hydrogen fuel cell stack; 11. Cathode side air inlet channel; 12. Anode side air inlet channel; 13. Exhaust gas outlet channel; 14. Open waste heat recovery device; 15. Sine wave channel; 16. Heat-conducting layer; 17. Hydrogen closed-loop heat exchanger; 18. Oxygen closed-loop heat exchanger; 19. Hydrogen heat exchange inlet; 20. Hydrogen heat exchange outlet; 21. Oxygen heat exchange inlet; 22. Oxygen heat exchange outlet; 23. Waste heat side gas inlet; 24. Waste heat side gas outlet. Detailed Implementation

[0037] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. These embodiments are only used to explain the present invention and are not intended to limit the scope of protection of the present invention.

[0038] like Figure 1-8As shown, this invention discloses a hydrogen-air-hydrogen-oxygen dual-modal critical space fuel cell system, comprising a hydrogen-air supply module, a hydrogen-oxygen supply module, a hydrogen fuel cell system, an open waste heat recovery device 14, a heat-conducting layer 16, a hydrogen closed-loop heat exchanger 17, an oxygen closed-loop heat exchanger 18, and a four-port gas interface; wherein, the hydrogen-air supply module includes a hydrogen storage cylinder 1, a hydrogen inlet solenoid valve device 2, and an air compressor 3; the hydrogen-oxygen supply module includes an oxygen cylinder 4 and an oxygen delivery control valve 5; the hydrogen fuel cell system includes a hydrogen fuel cell stack 10, a control system 6, a hydrogen outlet and air outlet solenoid valve 7, an air compressor electronic control 8, and a lithium battery 9; and the hydrogen fuel cell system... The battery stack 10 is provided with a cathode-side air inlet channel 11, an anode-side air inlet channel 12, and a tail gas outlet channel 13. The open waste heat recovery device 14 is provided with a sinusoidal waveform channel 15. The heat-conducting layer 16 is attached between the open waste heat recovery device 14 and the hydrogen closed-loop heat exchanger 17 and the oxygen closed-loop heat exchanger 18. The hydrogen closed-loop heat exchanger 17 and the oxygen closed-loop heat exchanger 18 are assembled back to back and sealed and isolated from each other. The four-port gas interface is a circular interface, which is the hydrogen inlet and outlet and the oxygen inlet and outlet, respectively, to realize unidirectional heat exchange and transportation of gas and avoid backflow or disturbance of hot and cold gas.

[0039] In this embodiment, the hydrogen storage cylinder 1 is connected to the hydrogen heat exchange inlet 19 of the hydrogen closed-loop heat exchanger 17 via the hydrogen inlet solenoid valve device 2, and the hydrogen heat exchange outlet 20 of the hydrogen closed-loop heat exchanger 17 is connected to the anode side air intake channel 12 of the hydrogen fuel cell stack 10; the air compressor 3 is selectively connected to the cathode side air intake channel 11 of the hydrogen fuel cell stack 10, forming a hydrogen-air supply loop to ensure a stable supply of hydrogen and air in low-altitude environments. The oxygen cylinder 4 is connected to the oxygen heat exchange inlet 21 of the oxygen closed-loop heat exchanger 18 via the oxygen delivery control valve 5, and the oxygen heat exchange outlet 22 of the oxygen closed-loop heat exchanger 18 is connected to the cathode side air intake channel 11 of the hydrogen fuel cell stack 10, forming a hydrogen-oxygen supply loop; the hydrogen-air supply loop and the hydrogen-oxygen supply loop are selectively activated by the control system 6 to ensure orderly switching of oxygen supply modes at different altitudes.

[0040] The exhaust gas outlet 13 of the hydrogen fuel cell stack 10 is connected to the waste heat side gas inlet 23 of the open waste heat recovery device 14, and the waste heat side gas outlet 24 of the open waste heat recovery device 14 is open. The sinusoidal waveform channel 15 is used to increase the exhaust gas disturbance and heat exchange area, so that the exhaust gas heat is simultaneously transferred to the gas in the hydrogen closed flow channel heat exchanger 17 and the oxygen closed flow channel heat exchanger 18 through the heat-conducting layer 16, realizing the efficient recovery and utilization of waste heat. The flow channel structure of the hydrogen closed flow channel heat exchanger 17 and the oxygen closed flow channel heat exchanger 18 is a plate design, and both have closed channels with baffle paths inside. The gas flows in the closed channel in an upward and downward direction, forming a pressure difference-driven unidirectional flow, avoiding gas bag residue, and improving heat exchange uniformity.

[0041] The heat-conducting layer 16 is a metal heat-conducting sheet made of high thermal conductivity aluminum. It is used to evenly diffuse the heat from the exhaust gas absorbed by the open waste heat recovery device 14, forming a stable hot surface and transferring it to the hydrogen closed-loop heat exchanger 17 and the oxygen closed-loop heat exchanger 18. This prevents thermal stress caused by local overheating in the hydrogen closed-loop heat exchanger 17 and the oxygen closed-loop heat exchanger 18, ensuring the stability of the system structure. The control system 6 is electrically connected to the hydrogen inlet solenoid valve device 2, the air compressor 3, the oxygen delivery control valve 5, the hydrogen outlet air solenoid valve 7, the air compressor electronic speed controller 8, and the lithium battery 9. It is used to detect environmental parameters and control the switching between the hydrogen-air supply circuit and the hydrogen-oxygen supply circuit, as well as the start and stop of the waste heat recovery function. The hydrogen outlet air solenoid valve 7 is located on the exhaust side of the hydrogen fuel cell stack 10 and is used to achieve exhaust control in accordance with different working modes. The lithium battery 9 is used to provide power for system startup and auxiliary equipment operation.

[0042] The open-type waste heat recovery device 14 is located on the outermost layer of the system. The sinusoidal waveform channel 15 allows the exhaust gas to scour the metal wall under thin-layer turbulence, avoiding the risk of condensation or ice blockage. The hydrogen closed-channel heat exchanger 17 and the oxygen closed-channel heat exchanger 18 obtain heat only through the heat-conducting layer 16, and do not exchange heat with each other, so there is no risk of cross-contamination, ensuring the safety of the hydrogen and oxygen transportation process.

[0043] The specific workflow of this system is as follows:

[0044] Low-altitude phase: When the UAV is in a low-altitude environment of hundreds to thousands of meters, the atmospheric pressure is sufficient and the temperature is moderate. The control system 6 detects that the environmental parameters meet the operating conditions of the hydrogen-air mode, controls the hydrogen-air supply circuit to be turned on, the hydrogen-oxygen supply circuit to be turned off, and the waste heat recovery function is on standby, only undertaking a small part of temperature equalization. At this time, the hydrogen in the hydrogen storage tank 1 enters the hydrogen closed flow channel heat exchanger 17 through the hydrogen inlet solenoid valve device 2, and is discharged from the hydrogen heat exchange outlet 20 and enters the hydrogen fuel cell stack 10 through the anode side air inlet channel 12. The air compressor 3 starts and pressurizes the outside air, which is then sent to the cathode side of the hydrogen fuel cell stack 10 through the cathode side air inlet channel 11. The hydrogen and air undergo an electrochemical reaction in the stack to generate electricity, which powers the UAV. The heat generated by the stack is maintained by normal heat dissipation to keep the system running stably.

[0045] The critical phase from low to high altitude: As the drone ascends, the external atmospheric pressure drops rapidly, and the oxygen partial pressure decreases significantly. The control system 6 monitors the oxygen partial pressure parameter in real time. When it determines that the air supply cannot maintain the fuel cell stack reaction rate, it immediately issues a control command to close the linkage between the hydrogen inlet solenoid valve device 2 and the air compressor 3, cutting off the hydrogen-air supply circuit. Simultaneously, it opens the oxygen delivery control valve 5, connecting the hydrogen-oxygen supply circuit. Pure oxygen from the oxygen cylinder 4 enters the oxygen closed-loop heat exchanger 18, is discharged through the oxygen heat exchange outlet 22, and then enters the hydrogen fuel cell stack 10 through the fuel cell stack cathode side air inlet channel 11. There, it continues to undergo an electrochemical reaction with the hydrogen supplied through the hydrogen closed-loop heat exchanger 17, forming a closed-loop gas supply structure to ensure continuous power output.

[0046] High-altitude phase: When the drone enters near space, the ambient temperature is generally below zero. The control system 6 detects that the ambient temperature is below the preset threshold and activates the waste heat recovery function. The high-temperature exhaust gas generated by the hydrogen fuel cell stack 10 enters the sinusoidal waveform channel 15 of the open waste heat recovery device 14 through the stack exhaust gas discharge channel 13 and the waste heat side gas inlet 23. The sinusoidal waveform structure increases the turbulence of the exhaust gas and the heat exchange area, causing the exhaust gas to continuously wash against the metal wall under thin-layer turbulence. The heat is fully absorbed and transferred to the heat-conducting layer 16 that is close to the channel. The heat-conducting layer 16 evenly diffuses the instantaneous local high temperature into a smooth and stable hot surface, which is simultaneously transferred to the hydrogen closed-loop heat exchanger 17 and the oxygen closed-loop heat exchanger 18. Hydrogen and oxygen flow in their respective closed channels in a deflected flow path. The pressure difference created by the upward and downward flow direction drives the hydrogen to fully contact and exchange heat with the heat-conducting layer 16, reaching a suitable reaction temperature before entering the fuel cell stack. This avoids the decrease in membrane electrode reaction rate and water management disorder caused by low temperature, ensuring that the hydrogen fuel cell stack 10 can maintain stable reaction activity in the extremely low temperature and low pressure environment of near space, and achieve long-term continuous power supply.

[0047] Throughout the entire operation, the hydrogen exhaust solenoid valve 7 adjusts the exhaust status in real time according to the exhaust requirements of different working modes to ensure the internal pressure balance of the system; the air compressor ESC 8 adjusts the power supply parameters in coordination with the working status of the air compressor 3 to ensure the efficient operation of the air compressor 3; the lithium battery 9 provides starting power and operational support for the control system 6, various solenoid valves, air compressor ESC 8 and other auxiliary equipment, ensuring that all components of the entire system work together to achieve continuous power output from low altitude to high altitude, effectively overcoming the problems of insufficient oxygen supply at high altitude, difficulty in maintaining low temperature, and degradation of fuel cell stack efficiency in existing technologies.

Claims

1. A hydrogen-air-hydrogen-oxygen dual-modal critical space fuel cell system, characterized in that, It includes a hydrogen-air supply module, a hydrogen-oxygen supply module, a hydrogen fuel cell system, an open waste heat recovery device (14), a heat-conducting layer (16), a hydrogen closed-loop heat exchanger (17), an oxygen closed-loop heat exchanger (18), and a four-port gas interface. The hydrogen-air supply module includes a hydrogen storage cylinder (1), a hydrogen inlet solenoid valve device (2), and an air compressor (3). The hydrogen-oxygen supply module includes an oxygen cylinder (4) and an oxygen delivery control valve (5). The hydrogen fuel cell system includes a hydrogen fuel cell stack (10), a control system (6), a hydrogen outlet solenoid valve (7), an air compressor electronic control (8), and a lithium battery (9). The hydrogen fuel cell stack (10) is provided with a stack cathode side air inlet channel (11), a stack anode side air inlet channel (12), and a stack exhaust gas outlet channel (13). The open waste heat recovery device (14) is provided with a sinusoidal waveform channel (15) inside. The heat-conducting layer (16) is attached between the open waste heat recovery device (14) and the hydrogen closed flow channel heat exchanger (17) and the oxygen closed flow channel heat exchanger (18). The hydrogen closed flow channel heat exchanger (17) and the oxygen closed flow channel heat exchanger (18) are assembled back to back and sealed and isolated from each other. The four-port gas interface is a circular interface, with hydrogen inlet and outlet and oxygen inlet and outlet respectively, used to realize unidirectional heat exchange and transportation of gas, and avoid backflow or disturbance of hot and cold gas.

2. The hydrogen-air-hydrogen-oxygen dual-modal critical space fuel cell system according to claim 1, characterized in that, The hydrogen storage cylinder (1) is connected to the hydrogen heat exchange inlet (19) of the hydrogen closed flow channel heat exchanger (17) via the hydrogen inlet solenoid valve device (2). The hydrogen heat exchange outlet (20) of the hydrogen closed flow channel heat exchanger (17) is connected to the anode side air intake channel (12) of the hydrogen fuel cell stack (10). The air compressor (3) is selectively connected to the cathode side air intake channel (11) of the hydrogen fuel cell stack (10), forming a hydrogen-air supply circuit.

3. The hydrogen-air-hydrogen-oxygen dual-modal critical space fuel cell system according to claim 1, characterized in that, The oxygen cylinder (4) is connected to the oxygen heat exchange inlet (21) of the oxygen closed flow channel heat exchanger (18) through the oxygen delivery control valve (5). The oxygen heat exchange outlet (22) of the oxygen closed flow channel heat exchanger (18) is connected to the fuel cell cathode side air intake channel (11) of the hydrogen fuel cell stack (10), forming a hydrogen-oxygen supply circuit. The hydrogen-air supply circuit and the hydrogen-oxygen supply circuit are selectively connected through the control system (6).

4. The hydrogen-air-hydrogen-oxygen dual-modal critical space fuel cell system according to claim 1, characterized in that, The tail gas exhaust channel (13) of the hydrogen fuel cell stack (10) is connected to the waste heat side gas inlet (23) of the open waste heat recovery device (14), and the waste heat side gas outlet (24) of the open waste heat recovery device (14) is open; the sinusoidal waveform channel (15) is used to increase the tail gas disturbance and heat exchange area, so that the tail gas heat is synchronously transferred to the gas in the hydrogen closed flow channel heat exchanger (17) and the oxygen closed flow channel heat exchanger (18) through the heat conduction layer (16).

5. The hydrogen-air-hydrogen-oxygen dual-modal critical space fuel cell system according to claim 1, characterized in that, The flow channel structure of the hydrogen closed-channel heat exchanger (17) and the oxygen closed-channel heat exchanger (18) is a plate design, and both have a closed channel with a baffle path inside. The gas flows in the closed channel in an upward and downward direction, forming a unidirectional flow driven by pressure difference, thus avoiding gas bag residue.

6. The hydrogen-air-hydrogen-oxygen dual-modal critical space fuel cell system according to claim 1, characterized in that, The heat-conducting layer (16) is a metal heat-conducting sheet made of high thermal conductivity aluminum. It is used to evenly diffuse the heat of the exhaust gas absorbed by the open waste heat recovery device (14), form a stable hot surface and transfer it to the hydrogen closed flow channel heat exchanger (17) and the oxygen closed flow channel heat exchanger (18), so as to prevent the hydrogen closed flow channel heat exchanger (17) and the oxygen closed flow channel heat exchanger (18) from generating thermal stress due to local overheating.

7. The hydrogen-air-hydrogen-oxygen dual-modal critical space fuel cell system according to claim 1, characterized in that, The control system (6) is electrically connected to the hydrogen inlet solenoid valve device (2), air compressor (3), oxygen delivery control valve (5), hydrogen outlet solenoid valve (7), air compressor electric regulator (8) and lithium battery (9), and is used to detect environmental parameters and control the switching between hydrogen air supply circuit and hydrogen oxygen supply circuit, as well as the start and stop of waste heat recovery function.

8. The hydrogen-air-hydrogen-oxygen dual-modal critical space fuel cell system according to claim 7, characterized in that, The environmental parameters include atmospheric pressure, oxygen partial pressure and ambient temperature. When the environment is at low altitude, the atmospheric pressure is sufficient and the temperature is moderate, the control system (6) controls the hydrogen-air supply circuit to be turned on, the hydrogen-oxygen supply circuit to be turned off, the waste heat recovery function is on standby, and only undertakes a small amount of temperature equalization function. When the environment is near space and the oxygen partial pressure drops to the point that it cannot maintain the reaction rate of the fuel cell stack, the control system (6) turns off the hydrogen-air supply circuit and turns on the hydrogen-oxygen supply circuit to form a closed-loop gas supply structure. When the ambient temperature is below zero degrees, the control system (6) starts the waste heat recovery function.

9. The hydrogen-air-hydrogen-oxygen dual-modal critical space fuel cell system according to claim 1, characterized in that, The hydrogen exhaust solenoid valve (7) is located on the exhaust side of the hydrogen fuel cell stack (10) and is used to control exhaust in different working modes; the lithium battery (9) is used to provide power for system startup and auxiliary equipment operation.

10. The hydrogen-air-hydrogen-oxygen dual-modal critical space fuel cell system according to claim 1, characterized in that, The open-type waste heat recovery device (14) is located on the outermost layer of the system. The sinusoidal waveform channel (15) allows the exhaust gas to scour the metal wall under thin-layer turbulence, avoiding the risk of condensation or ice blockage. The hydrogen closed-channel heat exchanger (17) and the oxygen closed-channel heat exchanger (18) obtain heat only through the heat-conducting layer (16) and do not exchange heat with each other, so there is no risk of cross-contamination.

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