Self-adapting air-cooled hydrogen fuel cell system with gas-water-heat synergistic management and control method

Abstract

The present application belongs to the technical field of hydrogen fuel cells, and particularly relates to a self-adaptive air-cooled hydrogen fuel cell system with gas-water thermal cooperative management and a control method. The system comprises an anode gas supply subsystem, a cathode gas supply and thermal management subsystem, an auxiliary heat dissipation cooling subsystem, an electric control subsystem and a tail exhaust device. The anode gas supply subsystem adopts comparison of average voltage value of single stack, pressure difference value of anode inlet and outlet and online continuous monitoring of high-frequency impedance value to monitor and execute anode bidirectional gas supply switching. The cathode gas supply and thermal management subsystem intelligently switches evaporation cooling and waste heat recovery modes according to environmental conditions and stack state, realizes the ability of heating cathode inlet gas in low-temperature environment and cooling inlet gas in high-temperature environment, and recycles tail exhaust water through a gas-liquid separation and recycling subsystem. The present application realizes stable operation in full-temperature range, improves stack output performance and service life, and is suitable for portable power sources, unmanned aerial vehicles, backup power sources and commercial vehicle auxiliary power sources.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrogen fuel cells, and particularly relates to a self-adaptive air-cooled hydrogen fuel cell system with air-water-heat collaborative management and a control method. BACKGROUND

[0002] Proton exchange membrane fuel cells are widely used in many fields due to their high energy conversion efficiency and zero emissions. Among them, the air-cooled hydrogen fuel cell system uses air to directly cool the stack, eliminating the need for a complex liquid cooling circuit, and has the advantages of simple structure, low cost, and no freezing risk. However, as the power level increases and the reliability requirements of the system continue to improve, the traditional air-cooled system exposes core technical defects. The fundamental reason is that the cathode side air bears the responsibilities of "reactant (oxygen) supply", "waste heat discharge", and "membrane electrode hydration regulation", and the anode management, temperature and humidity adaptation, and system collaboration are insufficient.

[0003] The water management and nitrogen accumulation problems on the anode side of the air-cooled hydrogen fuel cell system cannot be ignored. The water produced by the reaction and the nitrogen gas permeated from the cathode side will accumulate in the anode flow channel, especially at the outlet end, causing "flooding" and hydrogen dilution, resulting in uneven local current density and performance fluctuations. Although the conventional periodic pulse exhaust can alleviate this problem, if it is not coordinated with the air-cooled management strategy on the cathode side, it may exacerbate the drying or excessive humidity of the membrane electrode.

[0004] In normal or high-temperature environments, the temperature of the compressed air from the air compressor rises sharply, causing the temperature of the cathode entering the stack to be too high, and the risk of membrane electrode drying increases. In low-temperature environments, the air-cooled fuel cell system has no effective air inlet heating mechanism, making cold start difficult and performance recovery slow. In the prior art, patent CN120565720B discloses a scheme that uses stack waste water to cool the air inlet of the air compressor. However, this scheme has obvious defects: first, its cooling efficiency completely depends on the water production of the stack, and when the system is running at low power (such as unmanned aerial vehicle cruising), the cooling capacity decreases sharply or even fails due to insufficient water production, which cannot meet the continuous cooling demand; second, it lacks a mechanism for heating the air inlet in low-temperature environments, and has poor cold start performance; third, it lacks coordination between anode management, cathode heat management, and system power state, and cannot cope with complex and variable working environments. SUMMARY

[0005] To solve the technical problems existing in the prior art, the purpose of the present application is to provide a self-adaptive air-cooled hydrogen fuel cell system with air-water-heat collaborative management and a control method.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] The application provides a self-adaptive air-cooled hydrogen fuel cell system with gas-water heat synergic management, which comprises an anode gas supply subsystem, a cathode gas supply and heat management subsystem, a gas-liquid separation and recovery subsystem, an electric control subsystem and a tail gas exhaust device.

[0008] The anode gas supply subsystem comprises a high-pressure hydrogen source and two groups of pressure-reducing one-way gas inlet and outlet branches.

[0009] One end of each of the two groups of gas inlet branches is in communication with the inlet end and the outlet end of the anode of the electric pile, and the other end of each of the two groups of gas inlet branches is connected with the high-pressure hydrogen source in parallel; one end of each of the two groups of gas outlet branches is in communication with the inlet end and the outlet end of the anode of the electric pile, and the other end of each of the two groups of gas outlet branches is connected with the tail gas exhaust device in parallel.

[0010] The cathode gas supply and heat management subsystem comprises an air filter device, an air compressor and a heat exchange device which are sequentially connected, the heat exchange device comprises a dry channel and a wet channel which are separated by a partition, the dry channel is connected in series between the air compressor and the inlet of the cathode of the electric pile, and the wet channel is connected with the outlet of the cathode of the electric pile; a plurality of parallel heat dissipation fans are arranged on the outer side of the electric pile along the air flow direction.

[0011] The gas-liquid separation and recovery subsystem comprises a gas-liquid separation device, a micro water pump and a water tank, the input end of the gas-liquid separation device is in communication with the wet channel of the heat exchange device, the output end of the gas-liquid separation device is divided into a gas branch and a liquid branch, the gas branch is in communication with the tail gas exhaust device through a throttle valve, the liquid branch is in communication with a recovery water tank integrated at the bottom of the gas-liquid separation device, the recovery water tank is in communication with the wet channel through the micro water pump, and the water tank is in communication with the recovery water tank for water replenishment.

[0012] The electric control subsystem comprises a pressure monitoring device, a temperature monitoring device, a liquid level sensor and an online impedance spectrum detection unit, the pressure monitoring device is arranged at the outlet of the high-pressure hydrogen source, the inlet and outlet of the anode of the electric pile and the inlet and outlet of the cathode of the electric pile respectively, the temperature monitoring device is arranged on the anode of the electric pile, the cathode of the electric pile, the body of the electric pile and the environment, the liquid level sensor is arranged in the recovery water tank, and the online impedance spectrum detection unit is used for detecting the high-frequency impedance value of the electric pile.

[0013] The intake branch comprises a pressure reducing valve, the exhaust branch comprises a one-way valve and a nitrogen exhaust valve; one set of the pressure reducing one-way intake and exhaust branch comprises a pressure reducing valve I, a one-way valve I and a nitrogen exhaust valve I, the high-pressure hydrogen source is communicated with one end of the anode of the stack through the pressure reducing valve I, the other end of the anode of the stack is communicated with the tail exhaust device through the one-way valve I and the nitrogen exhaust valve I; another set of the pressure reducing one-way intake and exhaust branch comprises a pressure reducing valve II, a one-way valve II and a nitrogen exhaust valve II, the high-pressure hydrogen source is communicated with the other end of the anode of the stack through the pressure reducing valve II, one end of the anode of the stack is communicated with the tail exhaust device through the one-way valve II, the nitrogen exhaust valve II and the tail exhaust device.

[0014] The nitrogen exhaust valve I and the nitrogen exhaust valve II are both periodic exhaust electromagnetic valves.

[0015] The wet channel is filled with a hydrophilic porous medium, and the dry channel and the wet channel are separated by a high-thermal-conductivity metal partition plate.

[0016] The heat dissipation fan is controlled through the temperature sensor signals of different areas on the stack and the cathode inlet temperature monitoring.

[0017] Another aspect of the present application provides a gas-water heat synergistic management control method of the system, which comprises anode bidirectional gas supply switching control and cathode temperature and humidity adaptive control; the anode bidirectional gas supply switching control is controlled according to the average voltage of the stack single section, the anode inlet and outlet pressure difference or the high-frequency impedance value monitored by the electric control subsystem;

[0018] The cathode temperature and humidity adaptive control is adaptively controlled according to the environmental temperature and the air inlet stack temperature monitored by the electric control subsystem.

[0019] The anode bidirectional gas supply switching control comprises the following steps:

[0020] S1-1: after the system is started, one set of the pressure reducing one-way exhaust branch is initially opened, the high-pressure hydrogen source enters the anode of the stack to participate in the reaction after being reduced by the corresponding pressure reducing valve, and the residual gas is periodically discharged to the tail exhaust device through the corresponding one-way valve and the nitrogen exhaust valve;

[0021] S1-2: the electric control subsystem monitors the average voltage of the stack single section, the anode inlet and outlet pressure difference and the high-frequency impedance value in real time;

[0022] S1-3: when the average voltage of the single section is lower than the safety threshold V1, or the anode inlet and outlet pressure difference is higher than the safety threshold P, or the high-frequency impedance continuously is lower than the lower threshold, the system is reduced to the idle speed working condition, the currently opened pressure reducing one-way exhaust branch is closed, another set of the pressure reducing one-way exhaust branch is opened, the water accumulation and the accumulated nitrogen in the anode flow channel are removed through the reverse hydrogen flushing, and the rotation speed of the heat dissipation fan is increased;

[0023] S1-4: When the high-frequency impedance is continuously higher than the upper threshold, the current hydrogen flow direction is maintained or the direction maintaining time is prolonged, and the heat dissipation fan speed is reduced;

[0024] S1-5: Steps S1-2 to S1-4 are repeated to realize the anode gas supply bidirectional switching cycle.

[0025] In step S1-3, during the reverse hydrogen flushing process, the original anode outlet of the stack becomes the inlet, and the original inlet becomes the outlet. Dry high-concentration hydrogen gas flows in the reverse direction to remove accumulated water and nitrogen in the flow channel.

[0026] The cathode temperature and humidity self-adaptive control comprises the following steps:

[0027] S2-1: After the system is started, the ambient temperature sensor detects the ambient temperature T;

[0028] S2-2: When T>0℃, the micro water pump is started to transport the liquid water in the recovery water tank to the hydrophilic porous medium in the wet channel. The high-temperature air compressed by the air compressor flows through the dry channel, and the heat conduction through the partition plate and the evaporation of the water in the wet channel realizes cooling. When the air inlet temperature T1 exceeds the set threshold, the heat dissipation fan is started and the speed is adjusted according to the stack temperature. When the water level in the recovery water tank is too low, the water tank is automatically replenished;

[0029] S2-3: When T≤0℃, the micro water pump is closed, the heat dissipation fan is closed, the cathode tail exhaust high-temperature exhaust gas flows through the wet channel, and the compressed air in the dry channel is preheated through the heat conduction through the partition plate. When the air inlet temperature T1 is monitored to be greater than 0℃, the micro water pump is started. When the air inlet temperature T1 exceeds the set threshold, the heat dissipation fan is started, otherwise step S2-2 is repeated;

[0030] S2-4: The gas-liquid mixture after the cathode reaction of the stack is separated by a gas-liquid separation device. The gas is discharged into the tail exhaust device through the air throttle valve, and the liquid is recovered to the recovery water tank.

[0031] In step S2-2, the air temperature entering the cathode of the stack is adjusted to a range that meets the working requirements of the stack through the heat exchange device. In step S2-3, the preheated air temperature needs to meet the requirements of the cold start condition of the stack.

[0032] The advantages and beneficial effects of the present application are:

[0033] Solve the problems of anode waterlogging and nitrogen accumulation: The present application adopts an anode bidirectional gas supply switching mode, which can actively flush the accumulated water and nitrogen in the stack flow channel. Compared with the traditional pulse exhaust, the water and nitrogen are more thoroughly removed, and local performance fluctuations are avoided.

[0034] Enhance the environmental adaptability of the whole temperature range: the invention recovers the exhaust heat at low temperature to preheat the intake air, shortens the cold start time; at high temperature, it cools down through evaporation, relieves the membrane electrode from drying, and realizes stable operation in low temperature to high temperature environment.

[0035] Realize the optimization of gas-water-heat synergy: the invention coordinates the anode gas supply, cathode temperature and humidity control and heat dissipation strategy through multi-sensor data linkage, solves the coupling contradiction of the three, and improves the overall efficiency and reliability of the system.

[0036] Water resource recycling: the invention recovers the cathode tail liquid water for evaporation cooling, cooperates with water tank water replenishment, gets rid of the dependence on water production of the stack, and guarantees the continuous and effective cooling function.

[0037] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be achieved and obtained by the structure particularly pointed out in the written description and the accompanying drawings.

[0038] The technical solutions of the present application will be further described in detail below by means of the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0039] The accompanying drawings are used to provide further understanding of the present application, and constitute a part of the specification, together with the embodiments of the present application, to explain the present application, and do not constitute a limitation on the present application. In the drawings:

[0040] Figure 1 The structure schematic diagram of the self-adaptive air-cooled hydrogen fuel cell system of the present application for gas-water-heat synergy management;

[0041] Figure 2 The cathode temperature and humidity self-adaptive control flow chart in the embodiment of the present application;

[0042] Figure 3 The anode bidirectional gas supply switching control flow chart in the embodiment of the present application.

[0043] In the figure: 1, high-pressure hydrogen source; 2-1, pressure reducing valve I; 2-2, pressure reducing valve II; 3-1, one-way valve I; 3-2, one-way valve II; 4-1, nitrogen discharge valve I; 4-2, nitrogen discharge valve II; 5, heat dissipation fan; 6, air filter device; 7, air compressor; 8, heat exchange device; 8a, dry channel; 8b, wet channel; 9, gas-liquid separation device; 10, throttle valve; 11, exhaust device; 12, micro water pump; 13, water tank. DETAILED DESCRIPTION

[0044] In the present application, unless specifically defined and limited otherwise, the terms "mounting", "connection", "connecting", "fixed", and the like should be interpreted broadly, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0045] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings, it should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0046] Referring to Figure 1As shown, one aspect of the present application provides a self-adaptive air-cooled hydrogen fuel cell system with gas-water heat synergistic management, which comprises an anode gas supply subsystem, a cathode gas supply and heat management subsystem, a gas-liquid separation and recovery subsystem, an electric control subsystem and a tail gas exhaust device 11; the anode gas supply subsystem comprises a high-pressure hydrogen source 1, two groups of parallelly arranged pressure-reducing one-way gas inlet and outlet branches, each group of pressure-reducing one-way gas inlet and outlet branches comprising a gas inlet branch and a gas outlet branch; one end of the two groups of gas inlet branches is respectively communicated with the inlet end and the outlet end of the anode of the stack, and the other end of the two groups of gas inlet branches is connected with the high-pressure hydrogen source in parallel, and one end of the two groups of gas outlet branches is respectively communicated with the inlet end and the outlet end of the anode of the stack, and the other end of the two groups of gas outlet branches is connected with the tail gas exhaust device in parallel; the cathode gas supply and heat management subsystem comprises an air filter device 6, an air compressor 7 and a heat exchange device 8 which are communicated in sequence, the heat exchange device 8 comprises a dry channel 8a and a wet channel 8b which are isolated by a partition, the dry channel 8a is connected in series between the air compressor 7 and the cathode inlet of the stack, and the wet channel 8b is connected with the cathode outlet of the stack; a plurality of parallelly arranged heat dissipation fans 5 are arranged on the outside of the stack along the air flow direction; the gas-liquid separation and recovery subsystem comprises a gas-liquid separation device 9, a micro water pump 12 and a water tank 13, the input end of the gas-liquid separation device 9 is communicated with the wet channel of the heat exchange device, the output end of the gas-liquid separation device 9 is divided into a gas branch and a liquid branch, the gas branch is communicated with the tail gas exhaust device 11 through a throttle valve 10, the liquid branch is communicated with a recovery water tank integrated at the bottom of the gas-liquid separation device 9, the recovery water tank is communicated with the wet channel 8b through the micro water pump 12, and the water tank 13 is communicated with the recovery water tank for water replenishment; the electric control subsystem comprises a pressure monitoring device, a temperature monitoring device, a liquid level sensor and an online impedance spectrum detection unit, the pressure monitoring device is arranged at the outlet of the high-pressure hydrogen source 1, the inlet and outlet of the anode of the stack and the inlet and outlet of the cathode of the stack respectively, and the pressure monitoring device at the outlet of the high-pressure hydrogen source 1 is used for monitoring whether the outlet pressure meets the use requirement. The temperature monitoring device is arranged on the inlet and outlet of the anode of the stack, the inlet and outlet of the cathode of the stack, the stack body and the environment, the liquid level sensor is arranged in the recovery water tank, and the online impedance spectrum detection unit is used for real-time detection of the high-frequency impedance value of the stack.

[0047] In the embodiment of the present application, the gas inlet branch comprises a pressure-reducing valve, and the gas outlet branch comprises a one-way valve and a nitrogen exhaust valve; one group of pressure-reducing one-way gas inlet and outlet branches comprises a pressure-reducing valve I 2-1, a one-way valve I 3-1 and a nitrogen exhaust valve I 4-1, the high-pressure hydrogen source 1 is communicated with the anode inlet end of the stack through the pressure-reducing valve I 2-1, and the anode outlet end of the stack is communicated with the tail gas exhaust device 11 through the one-way valve I 3-1 and the nitrogen exhaust valve I 4-1; the other group of pressure-reducing one-way gas inlet and outlet branches comprises a pressure-reducing valve II 2-2, a one-way valve II 3-2 and a nitrogen exhaust valve II 4-2, the high-pressure hydrogen source 1 is communicated with the anode outlet end of the stack through the pressure-reducing valve II 2-2, and the anode inlet end of the stack is communicated with the tail gas exhaust device 11 through the one-way valve II 3-2, the nitrogen exhaust valve II 4-2.

[0048] Further, the nitrogen discharge valve I 4-1 and the nitrogen discharge valve II 4-2 are both periodic exhaust valves, and the periodic exhaust frequency of the nitrogen discharge valve I 4-1 and the nitrogen discharge valve II 4-2 is matched with the anode gas supply switching period.

[0049] The fuel cell system adopts bidirectional anode gas supply. In the first working period, hydrogen in the high-pressure hydrogen source 1 is reduced to a suitable pressure by the pressure reducing valve I 2-1 and then enters the anode inlet of the stack to participate in the electrochemical reaction. After the hydrogen participates in the electrochemical reaction, residual hydrogen, nitrogen diffused from the cathode, water vapor and other gases are discharged periodically to the tail gas device 11 through the one-way valve I 3-1 and the nitrogen discharge valve I 4-1, and are discharged together with the cathode tail gas.

[0050] After the system runs for a period of time, when the electronic control subsystem detects that the average voltage of a certain cell density point is lower than the safety threshold V1, the internal reaction of the stack is uneven at this time, and water flooding or nitrogen accumulation may occur at some place of the anode outlet end. The system operation is reduced to the idling point working condition, and the anode bidirectional gas supply switching is performed. The pressure reducing valve II 2-2 is opened, and the pressure reducing valve I 2-1 is closed. The hydrogen in the high-pressure hydrogen source 1 is reduced to a suitable pressure by the pressure reducing valve II 2-2 and then enters the stack to participate in the electrochemical reaction. When the original outlet of the stack becomes an inlet, the dry high-concentration hydrogen gas will reverse flush the flow channel, pushing the accumulated liquid water and accumulated nitrogen to the new outlet, thereby effectively removing the accumulated water and maintaining the uniformity of the hydrogen concentration on the anode side, and ensuring the stability of the stack performance. At this time, the speed of the system cooling fan 5 is increased to strengthen the evaporation and discharge of water on the cathode side. After the residual hydrogen and other gases participating in the electrochemical reaction pass through the new outlet of the stack, the one-way valve II 3-2 and the nitrogen discharge valve II 4-2, they are periodically discharged to the tail gas device 11, and are discharged together with the cathode tail gas. The anode inlet and outlet pressure and temperature are monitored by the anode inlet and outlet pressure and temperature monitoring device. The monitoring subsystem continues to monitor, and when it is detected that the average voltage of a certain cell density point is lower than the safety threshold V1, the above-mentioned bidirectional gas supply switching is performed again, that is, the pressure reducing valve II 2-2 is closed, and the pressure reducing valve I 2-1 is opened.

[0051] If the electronic control subsystem detects that the anode inlet and outlet pressure difference is higher than the safety threshold P, it indicates that the liquid water accumulation in the flow channel increases, and the flow resistance increases. The system operation is reduced to the idling point, and the anode bidirectional gas supply switching is performed. At the same time, the speed of the system cooling fan 5 is increased to strengthen the evaporation and discharge of water on the cathode side.

[0052] The electric control subsystem detects the high-frequency impedance value of the stack in real time through the online impedance spectrum detection unit. When the high-frequency impedance is continuously higher than the upper threshold, the electric control subsystem determines that the membrane electrode has a tendency of dryness, and then executes the water retention strategy. The anode gas supply subsystem maintains the current gas supply channel, maintains the current hydrogen flow direction or prolongs the holding time in this direction, to use the anode water accumulation to humidify the membrane electrode through back diffusion. At the same time, the cathode air cooling subsystem reduces the speed of the cooling fan 5 to reduce water loss. When the high-frequency impedance value is continuously lower than the lower threshold, the controller determines that the membrane electrode has a tendency of over-wetting or flooding, and then executes the water removal strategy to switch the bidirectional gas supply to flush the anode flow channel, and the cooling fan 5 increases the speed to enhance the evaporation and discharge of water on the cathode side.

[0053] Further, the wet channel 8b is filled with a hydrophilic porous medium, and the dry channel 8a and the wet channel 8b are separated by a high-thermal-conductivity metal partition plate to enable rapid heat transfer between the dry channel 8a and the wet channel 8b.

[0054] Further, the cooling fan 5 is controlled by the temperature sensor signals of different areas on the stack and the cathode inlet monitoring temperature.

[0055] On the cathode side of the fuel cell system, the air filtering device 6 multi-stage filter core filters the particulate matter and chemical pollutants in the air, and then the compressed air passes through the air compressor 7 for compression and pressure increase. The high-temperature air after pressure increase passes through the heat exchange device 8 and enters the stack to participate in the electrochemical reaction. The air filtering device 6, the air compressor 7 and the heat exchange device 8 are connected by pipelines. The high-temperature water vapor and nitrogen gas generated after the electrochemical reaction are separated by the gas-liquid separation device 9, and then the separated gas passes through the throttle valve 10 and enters the tail exhaust device 11 to be discharged out of the system. The liquid water separated by the gas-liquid separation device 9 is stored in the recovery water tank integrated at the bottom of the gas-liquid separation device 9, and the recovery water tank is provided with a liquid level sensor.

[0056] The fuel cell system starts, when the ambient temperature sensor detects that the ambient temperature is greater than 0℃, at this time, it is judged that the system needs to be cooled. The micro water pump 12 is opened, and the water originally stored in the gas-liquid separation device 9 is supplied to the porous medium layer in the wet channel 8b of the heat exchange device 8 through the micro water pump 12. At the same time, the high-temperature cathode exhaust gas discharged from the stack flows through the wet channel 8b of the heat exchange device 8, which will continuously “blow away” the liquid water covering the hydrophilic porous medium layer, and the liquid water evaporates and absorbs heat. At this time, the air filtered by the air filter device 6 is compressed by the air compressor 7, and the high-temperature air flows through the dry channel 8a of the heat exchange device 8, and the heat is quickly transferred to the low-temperature wet channel 8b through the intermediate partition plate of the heat exchange device 8, causing the intake air in the dry channel 8a to be significantly cooled, so that the dry air entering the stack meets the use requirements. When the air inlet temperature T1 is monitored to exceed the set threshold value, in this embodiment, T1≥20℃, the cooling fan 5 is opened and the speed is increased to strengthen the evaporation and discharge of water on the cathode side. The exhaust gas flows through the throttle valve 10 and then the exhaust device 11, and is discharged out of the system together with the anode exhaust gas.

[0057] When the water level in the recovery water tank on the gas-liquid separation device 9 is too low, the water tank 13 supplies water to it to meet the evaporation cooling function of the heat exchange device 8 in any environment. The cooling fan 5 is arranged along the air flow direction of the stack, and multiple independent fans are connected in parallel to comprehensively and real-timely perceive the system state through the temperature sensor feedback of different areas of the stack, so as to realize the differentiated air supply of different cooling areas of the stack.

[0058] The system starts, when the ambient temperature sensor detects that the ambient temperature T is less than or equal to 0℃, at this time, it is judged that the stack is in the cold start stage. The micro water pump 12 is closed, the high-temperature cathode exhaust gas discharged from the stack flows through the wet channel 8b of the heat exchange device 8, at this time, there is no water evaporation and heat absorption, the air compressed by the air compressor 7 flows through the dry channel 8a of the heat exchange device 8, and the heat of the wet channel 8b is absorbed through the intermediate partition plate of the heat exchange device 8, so that the air entering the stack is preheated, the cathode inlet air temperature of the stack is increased, the stack can reach the optimal working temperature faster, the cold start time is shortened, and at the same time, the local overcooling, performance fluctuation and water condensation caused by the direct impact of cold air on the stack are avoided. At this time, the cooling fan 5 is not opened, the cathode exhaust gas flows through the throttle valve 10 and then the exhaust device 11, and is discharged out of the system together with the anode exhaust gas. When the ambient temperature T is detected to be greater than 0℃ or the air inlet temperature T1 is monitored to be greater than 0℃, the micro water pump 12 is opened; when the air inlet temperature T1 is monitored to be greater than or equal to 20℃, the cooling fan 5 is opened; if the air inlet temperature T1 is less than 20℃, the system repeats the above steps; until the shutdown purge, the work is ended.

[0059] The anode gas supply subsystem provided by the application monitors the fuel cell system by adopting the average voltage value of the contrast stack single section, the anode inlet and outlet pressure difference value and the online impedance spectrum monitoring, and performs the anode bidirectional gas supply switching. The cathode gas supply and heat management subsystem intelligently switches between the "evaporative cooling" and "waste heat recovery" modes according to the environmental conditions and the stack state, so as to realize the ability of heating the inlet gas in a low-temperature environment and dissipating the inlet gas in a high-temperature environment, and the tail water can be recovered through the gas-liquid separation recovery subsystem, so that the energy utilization maximization is realized. The application can realize stable operation in the full temperature range, improve the output performance and service life of the stack, and is suitable for small and large power scenes such as portable power sources, unmanned aerial vehicles, backup power sources and commercial vehicle auxiliary power sources.

[0060] Another aspect of the application provides a gas-water heat synergistic management control method of the system, including anode bidirectional gas supply switching control and cathode temperature and humidity adaptive control; the anode bidirectional gas supply switching control is controlled according to the single section average voltage, the anode inlet and outlet pressure difference or the high-frequency impedance value monitored by the monitoring subsystem; and the cathode temperature and humidity adaptive control is adaptively controlled according to the environmental temperature and the air inlet stack temperature monitored by the monitoring subsystem.

[0061] Referring to Figure 3 As shown in the figure, the anode bidirectional gas supply switching control includes the following steps:

[0062] S1-1: after the system is started, one of the pressure reduction unidirectional exhaust branches is initially opened, the high-pressure hydrogen source 1 enters the stack anode to participate in the reaction after being reduced by the corresponding pressure reduction valve, and the residual gas after the reaction is periodically discharged to the tail exhaust device 11 through the corresponding unidirectional valve and the nitrogen exhaust valve;

[0063] S1-2: the electric control subsystem monitors the single section average voltage, the anode inlet and outlet pressure difference and the high-frequency impedance value of the stack at different electric density points in real time;

[0064] S1-3: when it is monitored that the single section average voltage is lower than the safety threshold V1, or the anode inlet and outlet pressure difference is higher than the safety threshold P, or the high-frequency impedance continuously is lower than the lower threshold, the system is reduced to the idle speed working condition, the currently opened pressure reduction unidirectional exhaust branch is closed, another pressure reduction unidirectional exhaust branch is opened, the accumulated water and nitrogen in the anode flow channel are removed through the reverse hydrogen flushing, and the rotating speed of the heat dissipation fan 5 is increased;

[0065] S1-4: when it is monitored that the high-frequency impedance continuously is higher than the upper threshold, the current hydrogen flow direction is maintained or the maintaining time in the direction is prolonged, and the rotating speed of the heat dissipation fan 5 is reduced;

[0066] S1-5: steps S1-2 to S1-4 are repeated to realize the anode gas supply bidirectional switching cycle.

[0067] Further, in step S1-3, during the reverse hydrogen flushing process, the original anode outlet of the stack becomes the inlet, and the original inlet becomes the outlet.

[0068] Referring to Figure 2 As shown in the figure, the cathode temperature and humidity self-adaptive control includes the following steps:

[0069] S2-1: After the system is started, the ambient temperature sensor monitors the ambient temperature T;

[0070] S2-2: When T>0℃, the micro water pump 12 is opened to transport the liquid water in the recovery water tank to the hydrophilic porous medium of the wet channel 8b, and the high-temperature air compressed by the air compressor 7 flows through the dry channel 8a, and the heat conduction through the partition plate and the evaporation of the water in the wet channel 8b realizes cooling; when the air inlet temperature T1≥20℃ is monitored, the cooling fan 5 is opened and the rotating speed is adjusted according to the stack temperature; when the water level of the recovery water tank is too low, the water tank 13 is automatically replenished;

[0071] S2-3: When T≤0℃, the micro water pump 12 is closed, the cooling fan 5 is closed, the cathode tail exhaust high-temperature exhaust gas flows through the wet channel 8b, and the compressed air in the dry channel 8a is preheated through the heat conduction through the partition plate; until the air inlet temperature T1>0℃ is monitored, the micro water pump 12 is opened; when the air inlet temperature T1≥20℃ is monitored, the cooling fan 5 is opened, otherwise step S2-2 is repeated;

[0072] S2-4: The gas-liquid mixture after the cathode reaction of the stack is separated by the gas-liquid separation device 9, the gas is discharged into the tail exhaust device 11 through the air throttle 10, and the liquid is recovered to the recovery water tank.

[0073] Further, in step S2-2, the air temperature entering the cathode of the stack is adjusted to a range meeting the working requirements of the stack through the heat exchange device 8; in step S2-3, the preheated air temperature needs to meet the requirements of the cold start working condition of the stack.

[0074] The anode of the application adopts a bidirectional gas supply mode, which can effectively remove the accumulated water and nitrogen in the anode flow channel. By using the comparison of the average voltage value of the single cell, the pressure difference value between the inlet and outlet of the anode, and the on-line impedance spectrum monitoring strategy, the fuel cell system is monitored, and the bidirectional gas supply switching strategy is executed.

[0075] The cathode of the application is provided with a heat exchange device, which can intelligently switch between the "evaporative cooling" and "waste heat recovery" modes according to the environmental conditions and the state of the stack, so as to realize the ability of heating the inlet air in low temperature environment and cooling the inlet air in high temperature environment. At the same time, the water can be recovered through the micro water pump, so as to realize the maximum utilization of energy.

[0076] The application provides a gas-water-heat synergic management adaptive air-cooled hydrogen fuel cell system, which is suitable for small and medium power to high power scenes such as portable power supply, unmanned aerial vehicle, standby power supply and commercial vehicle auxiliary power supply, and in particular for a closed cathode air-cooled hydrogen fuel cell system, solves the coupling contradiction of water, heat and gas management, and improves the output performance, full-temperature environmental adaptability and service life.

[0077] Obviously, various modifications and changes can be made to the present application by those skilled in the art without departing from the spirit and scope of the present application. Thus, if these modifications and changes of the present application fall within the scope of the claims and their equivalents, it is intended to include these modifications and changes in the present application.

Claims

1. An adaptive air-cooled hydrogen fuel cell system with coordinated gas-water-thermal management, characterized in that, It includes an anode gas supply subsystem, a cathode gas supply and thermal management subsystem, a gas-liquid separation and recovery subsystem, an electrical control subsystem, and a tail exhaust device; The anode gas supply subsystem includes a high-pressure hydrogen source and two sets of depressurized unidirectional intake and exhaust branches. Each set of depressurized unidirectional intake and exhaust branches includes an intake branch and an exhaust branch. One end of each of the two sets of air intake branches is connected to the inlet and outlet of the fuel cell anode, respectively. The other ends of the two sets of air intake branches are connected in parallel to the high-pressure hydrogen source. One end of each of the two sets of exhaust branches is connected to the inlet and outlet of the fuel cell anode, respectively. The other ends of the two sets of exhaust branches are connected in parallel to the tailpipe device. The cathode gas supply and thermal management subsystem includes an air filter, an air compressor, and a heat exchanger connected in sequence. The heat exchanger includes a dry channel and a wet channel separated by a partition. The dry channel is connected in series between the air compressor and the cathode inlet of the fuel cell stack, and the wet channel is connected to the cathode outlet of the fuel cell stack. Multiple parallel cooling fans are arranged on the outside of the fuel cell stack along the airflow direction. The gas-liquid separation and recovery subsystem includes a gas-liquid separator, a micro water pump, and a water tank. The input end of the gas-liquid separator is connected to the wet channel of the heat exchange device. The output end of the gas-liquid separator is divided into a gas branch and a liquid branch. The gas branch is connected to the exhaust device via a throttle valve. The liquid branch is connected to the recovery water tank integrated at the bottom of the gas-liquid separator. The recovery water tank is connected to the wet channel via the micro water pump. The connection between the water tank and the recovery water tank is used for water replenishment. The electrical control subsystem includes a pressure monitoring device, a temperature monitoring device, a liquid level sensor, and an online impedance spectroscopy detection unit. The pressure monitoring device is respectively installed at the high-pressure hydrogen source outlet, the anode inlet and outlet of the fuel cell stack, and the cathode inlet and outlet of the fuel cell stack. The temperature monitoring device is installed at the anode inlet and outlet of the fuel cell stack, the cathode inlet and outlet of the fuel cell stack, the fuel cell stack body, and the environment. The liquid level sensor is installed in the recovery water tank. The online impedance spectroscopy detection unit is used to detect the high-frequency impedance value of the fuel cell stack.

2. The adaptive air-cooled hydrogen fuel cell system with gas-water-thermal synergistic management according to claim 1, characterized in that, The intake branch includes a pressure reducing valve, and the exhaust branch includes a check valve and a nitrogen discharge valve; One set of the pressure-reducing one-way inlet and outlet branch includes a pressure-reducing valve I, a one-way valve I and a nitrogen discharge valve I. The high-pressure hydrogen source is connected to the anode inlet of the fuel cell stack via the pressure-reducing valve I, and the anode outlet of the fuel cell stack is connected to the tail exhaust device via the one-way valve I and the nitrogen discharge valve I. Another set of pressure-reducing one-way inlet and outlet branches includes pressure-reducing valve II, one-way valve II and nitrogen discharge valve II. The high-pressure hydrogen source is connected to the anode outlet of the fuel cell stack via pressure-reducing valve II, and the anode inlet of the fuel cell stack is connected to the tail exhaust device via one-way valve II and nitrogen discharge valve II.

3. The adaptive air-cooled hydrogen fuel cell system with gas-water-thermal synergistic management according to claim 2, characterized in that, Both nitrogen venting valve I and nitrogen venting valve II are periodic exhaust solenoid valves.

4. The adaptive air-cooled hydrogen fuel cell system with gas-water-thermal synergistic management according to claim 2, characterized in that, The cooling fan is controlled by temperature sensor signals from different areas of the fuel cell stack and the temperature monitored at the cathode inlet.

5. The adaptive air-cooled hydrogen fuel cell system with gas-water-thermal synergistic management according to claim 2, characterized in that, The wet channel is filled with a hydrophilic porous medium, and the dry channel and the wet channel are separated by a high thermal conductivity metal partition.

6. A gas-water-heat coordinated management and control method using the system described in claim 5, characterized in that, It includes anode bidirectional gas supply switching control and cathode temperature and humidity adaptive control; the anode bidirectional gas supply switching control is based on the average voltage of a single cell of the fuel cell stack, the pressure difference between the anode inlet and outlet, or the high-frequency impedance value monitored by the monitoring subsystem. The cathode temperature and humidity adaptive control is based on the ambient temperature and air inlet temperature monitored by the electronic control subsystem.

7. The gas-water-heat synergistic management and control method according to claim 6, characterized in that, The anode bidirectional gas supply switching control includes the following steps: S1-1: After the system starts, one set of pressure-reducing one-way exhaust branches is initially opened. The high-pressure hydrogen source enters the anode of the fuel cell stack to participate in the reaction after being reduced by the corresponding pressure-reducing valve. The residual gas after the reaction is periodically discharged to the tail exhaust device through the corresponding one-way valve and nitrogen discharge valve. S1-2: The electrical control subsystem monitors the average voltage of a single section, the anode inlet-outlet voltage difference, and the high-frequency impedance value inside the fuel cell stack at different electrical density points in real time. S1-3: When the average voltage of a single section is detected to be lower than the safety threshold V1, or the pressure difference between the anode inlet and outlet is higher than the safety threshold P, or the high-frequency impedance is continuously lower than the lower limit threshold, the system drops to idle speed, closes the currently open pressure-reducing one-way exhaust branch, opens another set of pressure-reducing one-way exhaust branches, removes water and accumulated nitrogen in the anode flow channel by reverse hydrogen flushing, and increases the speed of the cooling fan at the same time. S1-4: When the high-frequency impedance is detected to be continuously higher than the upper limit threshold, maintain the current hydrogen flow direction or extend the time of maintaining this direction, while reducing the speed of the cooling fan. S1-5: Repeat steps S1-2 to S1-4 to achieve bidirectional switching cycle of anode gas supply.

8. The gas-water-heat synergistic management and control method according to claim 7, characterized in that, In steps S1-3, during the reverse hydrogen flushing process, the original anode outlet of the fuel cell stack becomes the inlet, and the original inlet becomes the outlet. Dry, high-concentration hydrogen flows in the reverse direction to remove accumulated water and nitrogen from the flow channel.

9. The gas-water-heat synergistic management and control method according to claim 6, characterized in that, The cathode temperature and humidity adaptive control includes the following steps: S2-1: After the system starts, the ambient temperature sensor detects the ambient temperature T; S2-2: When T > 0℃, the micro water pump turns on, delivering the liquid water in the recovery tank to the hydrophilic porous medium in the wet channel. The high-temperature air compressed by the air compressor flows through the dry channel, and the temperature is reduced by heat conduction through the partition and heat absorption by the evaporation of water in the wet channel. When the air inlet temperature T1 exceeds the set threshold, the cooling fan turns on and adjusts its speed according to the stack temperature. When the water level in the recovery tank is too low, the tank is automatically replenished. S2-3: When T≤0℃, the micro water pump and the cooling fan are turned off. The high-temperature exhaust gas from the cathode flows through the wet channel and preheats the compressed air in the dry channel by conducting heat through the partition until the air inlet temperature T1>0℃ is detected. Then the micro water pump is turned on. When the air inlet temperature T1 exceeds the set threshold, the cooling fan is turned on. Otherwise, repeat step S2-2. S2-4: The gas-liquid mixture after the cathode reaction of the fuel cell stack is separated by a gas-liquid separator. The gas is discharged into the tail exhaust device through the throttle valve, and the liquid is recovered to the recovery water tank.

10. The gas-water-heat coordinated management and control method according to claim 9, characterized in that, In step S2-2, the air temperature entering the cathode of the fuel cell stack is adjusted to meet the operating requirements of the fuel cell stack through a heat exchange device; in step S2-3, the preheated air temperature must meet the requirements of the fuel cell stack cold start condition.

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