Self-humidifying fuel cell system and control method thereof

Abstract

The present application relates to the technical field of fuel cell, and discloses a self-humidifying fuel cell system and a control method thereof, wherein the self-humidifying fuel cell system comprises a hydrogen supply and circulation subsystem, an air supply and humidification subsystem, a cooling subsystem, a liquid recovery and supply subsystem, a fuel cell stack and a central controller; the hydrogen supply and circulation subsystem is used for supplying hydrogen to the anode of the fuel cell stack and carrying out gas-liquid separation and hydrogen recycling on the anode tail gas; the air supply and humidification subsystem is used for supplying air with adaptive temperature and humidity to the cathode of the fuel cell stack and recovering energy and waste heat from the cathode tail gas; the cooling subsystem is used for regulating the operating temperature of the fuel cell stack and providing heat exchange medium for the air supply and humidification subsystem; and the liquid recovery and supply subsystem is used for recovering liquid water generated by the system and providing humidification water supply for the air supply and humidification subsystem. The present application can realize the collaborative management and intelligent control of water, heat and gas.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a self-humidifying fuel cell system and its control method. Background Technology

[0002] The stable and efficient operation of proton exchange membrane fuel cells (PEMFCs) is highly dependent on their hydrothermal management. The membrane electrode assembly (MEA) requires appropriate humidity to ensure proton conductivity. The proton conductivity of the membrane increases with the degree of ionomer hydration, which explains the reduced oxygen reduction reaction (ORR) kinetics at low relative humidity (RH). However, when the fuel cell is not adequately humidified, the proton exchange membrane is dry, significantly reducing its proton conductivity and potentially degrading the stack's performance, leading to irreversible voltage loss. Conversely, excessive humidification results in flooding, submerging the MEA and preventing gas from entering the catalyst layer, thus hindering the battery reaction. Both of these conditions can cause the fuel cell stack to fail to start normally. Therefore, proper gas humidification allows the proton exchange membrane to exhibit higher proton conductivity, enabling the fuel cell stack to maximize its high energy conversion efficiency. Current humidification technologies suffer from low integration, low precision, low energy efficiency, low environmental adaptability, and safety hazards.

[0003] In terms of humidification, mainstream technologies are divided into membrane humidifiers and direct-injection humidifiers. While membrane humidifiers are compact, they are expensive, have limited lifespan, and suffer from poor dynamic matching between humidification capacity and power. For example, Chinese invention patent application CN118588975A proposes an integrated circulating direct-injection humidification fuel cell system that recovers moisture from the cathode exhaust gas and uses an external water tank for integrated water management, effectively improving water utilization and reducing costs. However, this solution still has room for improvement in terms of space utilization, power consumption, water vapor separation effect, and precise control of air humidity. In harsh environments, the amount of water recovered alone cannot meet the air humidification demand. Furthermore, the recovery of moisture in the hydrogen path and the mitigation of potential hydrogen safety risks mainly rely on complex physical structure design and passive pressure differentials, requiring further robustness improvement.

[0004] In terms of safety, the core challenge of direct injection systems is how to completely prevent hydrogen from entering the cathode airflow path or cooling water path when recovering moisture carried by unreacted hydrogen from the anode circuit. The aforementioned solution in CN118588975A mitigates the risk through a sophisticated liquid seal design, but this design places extremely high demands on the precision of component machining and the sealing performance of the system during long-term operation. Furthermore, pressure fluctuations during system start-up, shutdown, or sudden load changes may cause temporary failure of the liquid seal, posing a safety hazard. Summary of the Invention

[0005] To address the aforementioned issues, this invention proposes a self-humidifying fuel cell system and its control method. By deeply integrating efficient water recovery and replenishment, precise control of air humidity and temperature with active and safe hydrogen emission technology, the system achieves coordinated management and intelligent control of water, heat, and gas.

[0006] The technical solution adopted in this invention is as follows: A self-humidifying fuel cell system includes: a hydrogen supply and circulation subsystem, an air supply and humidification subsystem, a cooling subsystem, a liquid recovery and replenishment subsystem, a fuel cell stack, and a central controller; The hydrogen supply and circulation subsystem is connected to the anode flow channel of the fuel cell stack, and is used to supply hydrogen to the anode and to perform gas-liquid separation and hydrogen recycling of the anode tail gas. The air supply and humidification subsystem is connected to the cathode flow channel of the fuel cell stack, and is used to supply air with appropriate temperature and humidity to the cathode, and to recover energy and waste heat from the cathode exhaust gas. The cooling subsystem is connected to the cooling channel of the fuel cell stack, and is used to regulate the operating temperature of the fuel cell stack and provide a heat exchange medium for the air supply and humidification subsystem. The liquid recovery and replenishment subsystem is connected to the hydrogen supply and circulation subsystem and the air supply and humidification subsystem, respectively, and is used to recover the liquid water generated by the system and provide humidification and water replenishment to the air supply and humidification subsystem; The central controller is electrically connected to each subsystem and is used to regulate the coordinated operation of each subsystem.

[0007] Furthermore, the air supply and humidification subsystem includes an air compressor, a venturi mixer, a multi-stage heat exchanger, and a temperature and humidity sensor connected sequentially along the air intake direction. The probe of the temperature and humidity sensor is connected to the cathode inlet of the fuel cell stack. The cathode outlet of the fuel cell stack is connected sequentially to an air-water separator, the multi-stage heat exchanger, and an expander. The expander is coaxially connected to the air compressor to recover energy from the cathode exhaust gas. The temperature and humidity sensor is electrically connected to the central controller.

[0008] Furthermore, the multi-stage heat exchanger includes a primary cooling chamber and a secondary cooling chamber that are interconnected; the primary cooling chamber includes a high-temperature air chamber and a loop air cooling chamber, the high-temperature air chamber is connected to the outlet of the Venturi mixer, the loop air cooling chamber is provided with a first heat exchange coil, the two ends of the first heat exchange coil are respectively connected to the outlet of the air-water separator and the inlet of the expander; the secondary cooling chamber is provided with a second heat exchange coil, the second heat exchange coil is connected to the air cooling loop of the cooling subsystem.

[0009] Furthermore, the throat of the Venturi mixer is provided with a water injection port, which is connected to the water storage box of the liquid recovery and replenishment subsystem through a pipeline. A second throttle valve is provided on the pipeline between the water injection port and the water storage box. The central controller can control the water flow rate into the Venturi mixer by adjusting the opening of the second throttle valve.

[0010] Furthermore, the hydrogen supply and circulation subsystem includes a hydrogen source and a hydrogen supply module connected sequentially along the hydrogen supply direction. The outlet of the hydrogen supply module is connected to the anode inlet of the fuel cell stack, and the anode outlet of the fuel cell stack is connected to a hydrogen-water separator. The gas outlet of the hydrogen-water separator flows back to the inlet of the hydrogen supply module, and the liquid outlet of the hydrogen-water separator is connected to the liquid recovery and replenishment subsystem via an intelligent drain valve unit.

[0011] Furthermore, the intelligent drainage valve unit includes a micro-hydrogen concentration sensor and a normally closed solenoid valve connected in series. Both the micro-hydrogen concentration sensor and the normally closed solenoid valve are electrically connected to the central controller. The central controller can receive the hydrogen concentration signal in the drainage flow detected in real time by the micro-hydrogen concentration sensor. Only when the detected hydrogen concentration is lower than a preset safety threshold and remains below it for a predetermined time will the central controller control the normally closed solenoid valve to open and drain the water.

[0012] Furthermore, the cooling subsystem includes a main coolant circulation loop and an air cooling loop; the main coolant circulation loop includes a main circulating water pump and a main radiator, and the main coolant circulation loop flows through the cooling channel of the fuel cell stack to achieve temperature regulation of the fuel cell stack; the air cooling loop includes a first throttle valve and a multi-stage heat exchanger, the first throttle valve is located at the coolant outlet of the main radiator, the heat exchange medium inlet of the multi-stage heat exchanger is connected to the liquid water outlet of the first throttle valve, and the first throttle valve is electrically connected to the central controller.

[0013] Furthermore, the liquid recovery and replenishment subsystem includes a water storage box, a second throttle valve, a third throttle valve, an external water tank, and a drain valve; the inlet of the water storage box is connected to the drain outlet of the hydrogen-water separator of the hydrogen supply and circulation subsystem and the drain outlet of the air-water separator of the air supply and humidification subsystem, respectively; the external water tank is connected to the water supply port of the water storage box via the third throttle valve, and the outlet of the water storage box is connected to the air supply and humidification subsystem via the second throttle valve; the drain outlet of the water storage box is connected via the drain valve; the second throttle valve, the third throttle valve, and the drain valve are all electrically connected to the central controller.

[0014] Furthermore, the central controller is configured to: receive the temperature and humidity signals of the cathode inlet air detected in real time by the temperature and humidity integrated sensor in the air supply and humidification subsystem; and, in conjunction with the operating load of the fuel cell stack, adjust the opening of the first throttle valve in the cooling subsystem to regulate the inlet air temperature, and adjust the opening of the second throttle valve in the liquid recovery and replenishment subsystem to regulate the inlet air humidity, so that the temperature and humidity of the cathode inlet air are adapted to the operating requirements of the fuel cell stack.

[0015] A control method for a self-humidifying fuel cell system, comprising: The air supply and humidification subsystem uses a temperature and humidity integrated sensor to detect the temperature and humidity of the air at the cathode inlet of the fuel cell stack in real time, and uses a micro hydrogen concentration sensor to detect the hydrogen concentration in the drain flow to be discharged from the anode of the fuel cell stack in real time. The central controller adjusts the opening of the second throttle valve in the liquid recovery and replenishment subsystem according to the detected humidity data to control the intake air humidification, and adjusts the opening of the first throttle valve in the cooling subsystem according to the detected temperature data to control the intake air heat exchange temperature; only when the detected hydrogen concentration is lower than the preset safety threshold and continues for a predetermined time, the normally closed solenoid valve in the air supply and humidification subsystem is controlled to open for drainage. The liquid recovery and replenishment subsystem regulates the liquid level in the water storage box through a third throttle valve and a drain valve.

[0016] The beneficial effects of this invention are as follows: 1) High-efficiency synergistic management of water, heat, and gas: This invention deeply integrates cathode exhaust gas energy recovery (multi-stage heat exchanger, air compressor) with high-efficiency heat dissipation (Venturi mixing device, multi-stage cooling) to achieve the recycling of system energy and materials. The exhaust gas waste heat is preheated by the primary cooling chamber and then recovered by the air compressor; the pressurized and heated air undergoes phase change cooling with atomized water at the throat of the Venturi mixer, and is then conditioned by the multi-stage heat exchanger, significantly reducing the radiator load and improving overall energy efficiency.

[0017] 2) Intelligent Active Hydrogen Removal Safety Mechanism: To overcome the limitations of traditional passive liquid seal safety design, this invention incorporates an intelligent drainage valve unit based on a high-precision micro-hydrogen concentration sensor at a critical node in the anode water path drainage. By monitoring the hydrogen concentration in the water flow in real time, drainage is only initiated when the concentration falls below a safe threshold. This transforms passive blocking into active monitoring and control, fundamentally preventing hydrogen from entering the cathode or other subsystems via the water path, significantly improving safety and reliability, and reducing reliance on high-precision liquid seal structures.

[0018] (3) Improved air inlet humidity accuracy: This invention uses a Venturi mixer to achieve low-pressure, high-efficiency atomization humidification, combined with the closed-loop regulation of the throttling valve in the secondary cooling circuit of the multi-stage heat exchanger, to achieve precise control of the inlet air humidity. The central controller integrates the regulating throttling valve, temperature and humidity sensor and water replenishment unit, dynamically responding to changes in the fuel cell load and environment, ensuring that the membrane electrode is always in the optimal humidity window, thus improving output performance and stability.

[0019] (4) Enhanced system integration and reliability: Through architectural innovation, this invention deeply integrates multiple traditional independent functional modules such as intercooling, humidification, and heat recovery, reducing the number of components and piping connections, and improving system compactness and reliability. The multi-stage heat exchanger design further enhances energy recovery efficiency and system adaptability under different operating conditions and environmental conditions. Attached Figure Description

[0020] Figure 1 This is a self-humidifying fuel cell system according to Embodiment 2 of the present invention.

[0021] Figure 2 This is a schematic diagram of a multi-stage heat exchanger according to Embodiment 2 of the present invention.

[0022] Figure 3 This is a schematic diagram of a water storage box structure according to Embodiment 2 of the present invention.

[0023] Figure labels: 1-Hydrogen source; 2-Hydrogen supply module; 3-Hydrogen-water separator; 4-Intelligent drain valve unit; 4a-Micro hydrogen concentration sensor; 4b-Normally closed solenoid valve; 5-Fuel cell stack; 6-Main circulating water pump; 7-Thermostat; 8-Main radiator; 9-Heater; 10-First throttle valve; 11-Air filter; 12-Air compressor; 13-Venturi mixer; 14-Multi-stage heat exchanger; 14a-First-stage cooling system 14b-Secondary cooling chamber; 15-Air-water separator; 16-Water storage box; 161-Water inlet; 162-Breath port; 163-Water outlet; 164-Water replenishment port; 165-High level gauge; 166-Low level gauge; 167-Drain outlet; 17-Second throttle valve; 18-Third throttle valve; 19-External water tank; 20-Expander; 21-Temperature and humidity sensor; 22-Drain valve; 23-Central controller. Detailed Implementation

[0024] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments are now described. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of the invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0025] Example 1 This embodiment provides a self-humidifying fuel cell system, including a hydrogen supply and circulation subsystem, an air supply and humidification subsystem, a cooling subsystem, a liquid recovery and replenishment subsystem, a fuel cell stack 5, and a central controller 23. The hydrogen supply and circulation subsystem is connected to the anode flow channel of the fuel cell stack 5, supplying hydrogen to the anode and performing gas-liquid separation and hydrogen recycling on the anode exhaust gas. The air supply and humidification subsystem is connected to the cathode flow channel of the fuel cell stack 5, supplying air with appropriate temperature and humidity to the cathode and recovering energy and waste heat from the cathode exhaust gas. The cooling subsystem is connected to the cooling flow channel of the fuel cell stack 5, regulating the operating temperature of the fuel cell stack 5 and providing a heat exchange medium for the air supply and humidification subsystem. The liquid recovery and replenishment subsystem is connected to both the hydrogen supply and circulation subsystem and the air supply and humidification subsystem, recovering liquid water generated by the system and providing humidification and replenishment water to the air supply and humidification subsystem. The central controller 23 is electrically connected to each subsystem, regulating the coordinated operation of each subsystem.

[0026] Preferably, the air supply and humidification subsystem includes an air compressor 12, a venturi mixer 13, a multi-stage heat exchanger 14, and a temperature and humidity sensor 21 connected sequentially along the air intake direction. The probe of the temperature and humidity sensor 21 is connected to the cathode inlet of the fuel cell stack 5. The cathode outlet of the fuel cell stack 5 is connected sequentially to an air-water separator 15, the multi-stage heat exchanger 14, and an expander 20. The expander 20 is coaxially connected to the air compressor 12 to recover the energy of the cathode exhaust gas. The temperature and humidity sensor 21 is electrically connected to the central controller 23.

[0027] Specifically, outside air is filtered and then enters the air compressor 12. After being pressurized and heated by the air compressor 12, it is sent to the Venturi mixer 13. In the Venturi mixer 13, it is mixed with atomized water to complete the initial humidification and cooling. Then, it enters the multi-stage heat exchanger 14 to complete precise temperature regulation. After temperature and humidity parameters are detected by the temperature and humidity sensor 21, the air is sent to the cathode inlet of the fuel cell stack 5 to participate in the electrochemical reaction. The high-temperature and high-humidity exhaust gas discharged from the cathode of the fuel cell stack 5 first enters the air-water separator 15 to complete gas-liquid separation. The separated liquid water is sent to the liquid recovery and replenishment subsystem, and the separated gas enters the multi-stage heat exchanger 14 to exchange heat with the high-temperature air on the intake side. The cooling capacity of the exhaust gas is used to pre-cool the intake air. The exhaust gas after heat exchange is sent to the expander 20. The expander 20 uses the pressure energy of the exhaust gas to drive the coaxially connected air compressor 12 to complete the recovery of exhaust gas energy. Finally, the exhaust gas system with recovered energy is discharged.

[0028] It should be noted that this structural design deeply integrates the pressurization, humidification, and temperature regulation of the cathode intake air with the waste heat recovery and energy recovery of the cathode exhaust gas. The cooling capacity of the cathode exhaust gas is used to pre-cool the intake air, while the pressure energy of the exhaust gas provides auxiliary power to the air compressor 12. This significantly reduces the power consumption of the air compressor 12 and the heat exchange load of the system radiator. At the same time, the temperature and humidity integrated sensor 21 collects the intake air parameters in real time, providing data support for the precise control of the intake air temperature and humidity, and ensuring the long-term stability of the cathode intake air parameters.

[0029] More preferably, the multi-stage heat exchanger 14 includes a primary cooling chamber 14a and a secondary cooling chamber 14b that are interconnected; the primary cooling chamber 14a includes a high-temperature air chamber and a loop air cooling chamber, the high-temperature air chamber is connected to the outlet of the Venturi mixer 13, the loop air cooling chamber is provided with a first heat exchange coil, the two ends of the first heat exchange coil are respectively connected to the outlet of the air-water separator 15 and the inlet of the expander 20; the secondary cooling chamber 14b is provided with a second heat exchange coil, the second heat exchange coil is connected to the air cooling loop of the cooling subsystem.

[0030] Specifically, the air processed by the Venturi mixer 13 first enters the first-stage cooling chamber 14a of the multi-stage heat exchanger 14, where it exchanges heat with the first heat exchange coil of the loop air cooling chamber in the high-temperature air chamber. The first heat exchange coil carries the low-temperature cathode exhaust gas separated by the air-water separator 15, and the coldness of the cathode exhaust gas is used to perform a first-stage cooling of the intake air. The air that has completed the first-stage cooling enters the second-stage cooling chamber 14b, where it exchanges heat with the second heat exchange coil in the second-stage cooling chamber 14b. The second heat exchange coil carries the low-temperature coolant supplied by the cooling subsystem, and the coolant performs a second-stage precise cooling of the intake air. After completing the two-stage cooling, the air is detected by the temperature and humidity sensor 21 and then sent to the cathode of the fuel cell stack 5.

[0031] It should be noted that through the staged heat exchange design of the two-stage cooling chamber, the waste heat of the cathode exhaust gas is first used to pre-cool the intake air, and then the coolant in the cooling circuit is used to achieve precise temperature control. This maximizes the recovery of waste heat and cold inside the system, reduces the heat exchange load of the cooling subsystem, and at the same time improves the accuracy and stability of intake air temperature control, avoids the temperature fluctuation problem caused by single-stage heat exchange, and ensures the adaptability of the intake air temperature of fuel cell stack 5 under different load conditions.

[0032] More preferably, the throat of the Venturi mixer 13 is provided with a water injection port, which is connected to the water storage box 16 of the liquid recovery and replenishment subsystem through a pipeline. A second throttle valve 17 is provided on the pipeline between the water injection port and the water storage box 16. The central controller 23 can control the water flow rate into the Venturi mixer 13 by adjusting the opening of the second throttle valve 17.

[0033] Specifically, the recycled water buffered in the water storage box 16 is transported through pipeline to the water injection port at the throat of the Venturi mixer 13. The central controller 23 controls the water flow rate entering the Venturi mixer 13 by adjusting the opening of the second throttle valve 17 based on the humidity detection data at the cathode inlet. The water is sprayed into the throat of the Venturi mixer 13 through the water injection port. The negative pressure generated by the high-speed airflow in the throat atomizes the liquid water. The atomized water droplets are fully mixed with the high-speed airflow. At the same time, the water droplets absorb heat through vaporization phase change, achieving preliminary cooling and humidification of the pressurized and heated air.

[0034] It should be noted that the negative pressure characteristic of the throat of the Venturi mixer 13 is used to achieve low-pressure and high-efficiency atomization of liquid water. The atomization and humidification of water replenishment can be completed without the need for an additional booster pump and atomizing nozzle, which simplifies the humidification structure and improves the humidification efficiency. The opening degree of the second throttle valve 17 is adjusted to achieve precise control of the water replenishment flow rate. The humidification amount can be dynamically adjusted according to the system load and the humidity requirements of the inlet air, ensuring that the humidity of the cathode inlet air is always within the optimal operating range of the fuel cell stack 5, avoiding the dry film or water flooding problem of the membrane electrode, and improving the output performance and service life of the stack.

[0035] Preferably, the hydrogen supply and circulation subsystem includes a hydrogen source 1 and a hydrogen supply module 2 connected sequentially along the hydrogen supply direction. The outlet of the hydrogen supply module 2 is connected to the anode inlet of the fuel cell stack 5, and the anode outlet of the fuel cell stack 5 is connected to a hydrogen-water separator 3. The gas outlet of the hydrogen-water separator 3 flows back to the inlet of the hydrogen supply module 2, and the liquid outlet of the hydrogen-water separator 3 is connected to the liquid recovery and replenishment subsystem via an intelligent drain valve unit 4.

[0036] Specifically, the high-pressure hydrogen output from hydrogen source 1 is reduced, stabilized, and its flow rate regulated by hydrogen supply module 2 before being sent to the anode inlet of fuel cell stack 5 to participate in the electrochemical reaction. The exhaust gas discharged from the anode carries unreacted hydrogen and liquid water generated by the electrochemical reaction into hydrogen-water separator 3, where gas-liquid separation is completed. The separated hydrogen flows back to the inlet of hydrogen supply module 2 through a pipeline, mixes with fresh hydrogen, and is sent back to the anode to participate in the reaction, realizing the recycling of hydrogen. The separated liquid water is transported through a pipeline to intelligent drain valve unit 4, and after being controlled by intelligent drain valve unit 4, it is sent to the water storage box 16 of liquid recovery and replenishment subsystem.

[0037] It should be noted that the hydrogen recycling design significantly improves the utilization rate of hydrogen and reduces hydrogen emissions and waste. The hydrogen-water separator 3 achieves gas-liquid separation of the anode tail gas, avoiding the accumulation of liquid water in the anode channel and preventing anode flooding, thus ensuring the stability of the anode hydrogen supply. At the same time, the separated liquid water is recycled to the water storage box 16, providing a water source for system humidification and realizing closed-loop utilization of water resources within the system.

[0038] More preferably, the intelligent drain valve unit 4 includes a micro hydrogen concentration sensor 4a and a normally closed solenoid valve 4b connected in series. Both the micro hydrogen concentration sensor 4a and the normally closed solenoid valve 4b are electrically connected to the central controller 23. The central controller 23 can receive the hydrogen concentration signal in the drain flow detected in real time by the micro hydrogen concentration sensor 4a, and only controls the normally closed solenoid valve 4b to open and drain when the detected hydrogen concentration is lower than a preset safety threshold for a predetermined time.

[0039] Specifically, the liquid water separated by the hydrogen-water separator 3 first flows through the micro-hydrogen concentration sensor 4a. The micro-hydrogen concentration sensor 4a detects the concentration of dissolved and carried hydrogen in the water flow in real time and transmits the detection signal to the central controller 23 in real time. The central controller 23 judges the received hydrogen concentration signal. When the detected hydrogen concentration is lower than the preset safety threshold and this state continues for a predetermined time, the central controller 23 outputs a control signal to drive the normally closed solenoid valve 4b to open. After the drainage flows through the opened normally closed solenoid valve 4b, it is sent into the water storage box 16. When the detected hydrogen concentration is higher than the preset safety threshold, the central controller 23 controls the normally closed solenoid valve 4b to remain closed, blocking the drainage path.

[0040] It should be noted that the above improvements break through the safety design limitations of the passive liquid seal for anode drainage in traditional fuel cells. Through real-time monitoring by the micro hydrogen concentration sensor 4a, the passive barrier is upgraded to active monitoring and precise control, fundamentally eliminating the risk of hydrogen entering the cathode or other subsystems through the drainage path, and significantly improving the safety and reliability of system operation. At the same time, it reduces the dependence of the anode drainage structure on the high-precision liquid seal structure, simplifies the design and processing difficulty of the drainage structure, and improves the long-term stability of the system.

[0041] Preferably, the cooling subsystem includes a main coolant circulation loop and an air cooling loop; the main coolant circulation loop includes a main circulating water pump 6 and a main radiator 8, and the main coolant circulation loop flows through the cooling channel of the fuel cell stack 5 to achieve temperature regulation of the fuel cell stack 5; the air cooling loop includes a first throttle valve 10 and a multi-stage heat exchanger 14, the first throttle valve 10 is located at the coolant outlet of the main radiator 8, the heat exchange medium inlet of the multi-stage heat exchanger 14 is connected to the liquid water outlet of the first throttle valve 10, and the first throttle valve 10 is electrically connected to the central controller 23.

[0042] Specifically, when the main coolant circulation loop is running, the main circulating water pump 6 drives the coolant to circulate within the loop. When the coolant flows through the cooling channel of the fuel cell stack 5, it absorbs the heat generated by the electrochemical reaction of the stack. The heated coolant flows into the main radiator 8, where it exchanges heat with the outside air and cools down. Part of the cooled coolant flows back to the inlet of the cooling channel of the fuel cell stack 5, completing the coolant circulation of the main circulation loop. The other part of the cooled coolant flows through the first throttle valve 10 and, after throttling and adjustment by the first throttle valve 10, is sent into the second heat exchange coil of the multi-stage heat exchanger 14. In the second heat exchange coil, it exchanges heat with the cathode air. The heated coolant returns to the main coolant circulation loop, merges with the high-temperature coolant at the stack outlet, and re-enters the main radiator 8 for cooling.

[0043] It should be noted that the dual-loop design of the main coolant circulation loop and the air cooling loop not only achieves stable control of the operating temperature of the fuel cell stack 5, but also provides an independent heat exchange medium path for precise temperature control of the cathode intake air. By adjusting the opening of the first throttle valve 10, the flow rate of coolant entering the air cooling loop can be precisely controlled, thereby precisely controlling the heat exchange and cooling amplitude of the cathode intake air, and realizing closed-loop control of the intake air temperature. At the same time, the dual-loop design decouples the stack temperature control from the intake air temperature control, avoiding mutual interference between the two and improving the temperature control accuracy and adaptability of the system under different load conditions.

[0044] Preferably, the liquid recovery and replenishment subsystem includes a water storage box 16, a second throttle valve 17, a third throttle valve 18, an external water tank 19, and a drain valve 22; the inlet of the water storage box 16 is connected to the drain outlet of the hydrogen-water separator 3 of the hydrogen supply and circulation subsystem and the drain outlet of the air-water separator 15 of the air supply and humidification subsystem, respectively; the external water tank 19 is connected to the water replenishment port of the water storage box 16 via the third throttle valve 18, and the outlet of the water storage box 16 is connected to the air supply and humidification subsystem via the second throttle valve 17; the drain outlet of the water storage box 16 is connected via the drain valve 22; the second throttle valve 17 and the third throttle valve 18 are both electrically connected to the central controller 23.

[0045] Specifically, the liquid water separated by the hydrogen-water separator 3 and the air-water separator 15 is transported through pipelines to the water storage box 16 for buffering. The liquid water in the water storage box 16 is then regulated by the second throttle valve 17 and transported to the Venturi mixer 13 to provide humidification and replenishment for the cathode air intake. The central controller 23 monitors the liquid level in the water storage box 16 in real time. When the liquid level in the water storage box 16 is lower than the set lower limit, the central controller 23 adjusts the opening of the third throttle valve 18 to increase the opening, and pure water from the external water tank 19 is replenished into the water storage box 16 through the third throttle valve 18, raising the liquid level in the water storage box 16. When the liquid level in the water storage box 16 is higher than the set upper limit, the central controller 23 adjusts the opening of the third throttle valve 18 to decrease or close it, stopping the external water replenishment, while simultaneously increasing the opening of the second throttle valve 17 to accelerate the water consumption in the water storage box 16, causing the liquid level to drop back to the normal range.

[0046] It should be noted that by uniformly recycling and buffering the liquid water separated from the anode and cathode of the system through the water storage box 16, the closed-loop utilization of water resources within the system is realized. The system can meet its self-humidification water demand without continuous reliance on external water replenishment, which greatly reduces the system's dependence on external water sources. Through the coordinated regulation of the second throttle valve 17 and the third throttle valve 18, both the precise control of the humidification water replenishment flow rate and the stability of the liquid level in the water storage box 16 are achieved, avoiding overflow problems caused by excessively high liquid levels or humidification interruption problems caused by excessively low liquid levels, thus improving the long-term stability of the system's self-humidification function.

[0047] Preferably, the central controller 23 is configured to: receive the temperature and humidity signals of the cathode inlet air detected in real time by the temperature and humidity integrated sensor 21 in the air supply and humidification subsystem, and adjust the opening of the first throttle valve 10 in the cooling subsystem to regulate the inlet air temperature in conjunction with the operating load of the fuel cell stack 5, and adjust the opening of the second throttle valve 17 in the liquid recovery and replenishment subsystem to regulate the inlet air humidity, so that the temperature and humidity of the cathode inlet air are adapted to the operating requirements of the fuel cell stack 5.

[0048] Specifically, during the operation of the fuel cell system, the central controller 23 collects the current operating load data of the fuel cell stack 5 in real time, and simultaneously receives the real-time temperature and humidity data of the cathode inlet air transmitted by the temperature and humidity integrated sensor 21. Based on the current operating load, the central controller 23 matches the target values ​​of the inlet air temperature and humidity required for the optimal operation of the stack under that load, and compares the real-time detected temperature and humidity data with the target values. When the real-time humidity is lower than the target value, the central controller 23 increases the opening of the second throttle valve 17, increasing the water flow rate of the Venturi mixer 13 and increasing the inlet air humidification. When the real-time humidity is higher than the target value, the central controller 23 decreases the opening of the second throttle valve 17, reducing the water flow rate and decreasing the inlet air humidification. When the real-time temperature is higher than the target value, the central controller 23 increases the opening of the first throttle valve 10, increasing the coolant flow rate into the multi-stage heat exchanger 14 and enhancing the inlet air heat exchange and cooling effect. When the real-time temperature is lower than the target value, the central controller 23 decreases the opening of the first throttle valve 10, reducing the coolant flow rate and weakening the heat exchange and cooling effect.

[0049] It should be noted that, through the closed-loop control of the central controller 23, independent and precise control of cathode inlet temperature and humidity is achieved. It can dynamically match the optimal inlet temperature and humidity parameters according to the operating load of the fuel cell stack, ensuring that the membrane electrode is always in the optimal humidity window and temperature environment, which greatly improves the output performance and operational stability of the fuel cell stack under different load conditions. At the same time, the temperature control and humidity control are decoupled, avoiding mutual interference in the temperature and humidity adjustment process, and improving the control accuracy and response speed.

[0050] This embodiment also provides a control method for a self-humidifying fuel cell system, including: The air supply and humidification subsystem uses a temperature and humidity integrated sensor 21 to detect the temperature and humidity of the air at the cathode inlet of the fuel cell stack 5 in real time, and uses a micro hydrogen concentration sensor 4a to detect the hydrogen concentration in the drain flow at the anode of the fuel cell stack 5 in real time. The central controller 23 adjusts the opening of the second throttle valve 17 in the liquid recovery and replenishment subsystem according to the detected humidity data to control the intake air humidification, and adjusts the opening of the first throttle valve 10 in the cooling subsystem according to the detected temperature data to control the intake air heat exchange temperature; only when the detected hydrogen concentration is lower than the preset safety threshold and remains below it for a predetermined time, the normally closed solenoid valve 4b in the hydrogen supply and circulation subsystem is controlled to open for drainage; the liquid recovery and replenishment subsystem adjusts the liquid level of the water storage box 16 through the third throttle valve 18.

[0051] Specifically, after the system starts up and enters the operating state, the temperature and humidity sensor 21 continuously collects the temperature and humidity data of the air at the cathode inlet of the fuel cell stack 5, and the micro-hydrogen concentration sensor 4a continuously collects the hydrogen concentration data in the water to be discharged from the anode hydrogen-water separator 3, and synchronously transmits the collected real-time data to the central controller 23; the central controller 23 compares the received humidity data with the target humidity value, and controls the water supply flow into the Venturi mixer 13 by adjusting the opening of the second throttle valve 17, thereby realizing closed-loop control of the cathode inlet air humidity; the central controller 23 compares the received temperature data with the target temperature value, and controls the water supply flow into the Venturi mixer 13 by adjusting the opening of the first throttle valve 17. The opening degree of 10 controls the flow rate of coolant entering the multi-stage heat exchanger 14, realizing closed-loop regulation of the cathode inlet temperature; the central controller 23 judges the received hydrogen concentration data, and only when the hydrogen concentration is lower than the preset safety threshold and the state continues for a predetermined time, it controls the normally closed solenoid valve 4b to open to complete the anode drainage, otherwise the normally closed solenoid valve 4b is kept closed; the central controller 23 monitors the liquid level of the water storage box 16 in real time, and controls the water replenishment of the external water tank 19 by adjusting the opening degree of the third throttle valve 18 to maintain the liquid level of the water storage box 16 within the normal working range, and at the same time recovers the liquid water generated on both sides of the anode and cathode of the system into the water storage box 16 to provide water source for system humidification.

[0052] It should be noted that this control method achieves the coordinated operation of precise closed-loop regulation of inlet temperature and humidity of the fuel cell system, active safety control of anode drainage, and closed-loop management of system water resources, ensuring the stable, efficient, and safe operation of the system under full load conditions. At the same time, through the linkage and regulation of multiple parameters, it achieves efficient coordinated management of system water-heat-gas, maximizing the system's energy utilization efficiency and operational reliability, and reducing the system's failure rate and maintenance costs.

[0053] Example 2 like Figure 1 As shown, this embodiment provides a self-humidifying fuel cell system, including a fuel cell stack 5, a central controller 23, a hydrogen supply and circulation subsystem, an air supply and humidification subsystem, a cooling subsystem, and a liquid recovery and replenishment subsystem.

[0054] In the air supply and humidification subsystem, ambient air passes through air filter 11, is pressurized and heated by air compressor 12, and then enters the intake duct of Venturi mixer 13. Water in water storage box 16 is atomized and sprayed into the water supply nozzle at the throat of Venturi mixer 12 through second throttle valve 17, mixing with the pressurized and heated air for humidification. Subsequently, the gas-water mixture undergoes phase change vaporization and is initially cooled, then cooled again through the first-stage cooling chamber 14a of multi-stage heat exchanger 14, and finally further cooled through the second-stage cooling chamber 14b of multi-stage heat exchanger 14. After reaching a suitable temperature by adjusting the opening of first throttle valve 10, the mixture enters the cathode of fuel cell stack 5 to participate in the reaction. Specifically, the principle of multi-stage heat exchanger 14 is as follows: Figure 2 As shown.

[0055] The high-temperature and high-humidity exhaust gas discharged from the cathode of the fuel cell stack 5 enters the air-water separator 15 for gas-liquid separation. The separated liquid is collected at the bottom of the separator and flows into the water storage box 16. After separation, the exhaust gas is heated by the first-stage cooling chamber 14a of the multi-stage heat exchanger 14. The energy of the gas is recovered by the expander 20 to drive the coaxial air compressor 12.

[0056] Preferably, the cooling subsystem includes a main coolant circulation loop and an air cooling loop. In the main coolant circulation loop, the main circulating water pump 6 drives the coolant to flow through the fuel cell stack 5, carrying away the reaction heat and becoming a high-temperature coolant. Controlled by the thermostat 7, the high-temperature coolant flows to the main radiator 8. The cooled coolant returns to the fuel cell stack 5 to complete the circulation. In the air cooling loop, after being cooled by the main radiator 8, the flow rate of the coolant flowing into the secondary cooling chamber 14b of the multi-stage heat exchanger 14 is controlled by adjusting the opening of the first throttle valve 10, thereby precisely controlling the relative humidity and temperature of the air flowing into the stack. The air then merges with the high-temperature coolant of the fuel cell stack 5 at the outlet of the secondary cooling chamber 14b of the multi-stage heat exchanger 14.

[0057] In the hydrogen supply and circulation subsystem, hydrogen, after being regulated, is supplied to the anode of the fuel cell stack 5 by the hydrogen supply module 2. The mixture of unreacted hydrogen and generated water is separated by the hydrogen-water separator 3. The hydrogen is recycled by the hydrogen supply module 2, and the separated liquid water enters the intelligent drain valve unit 4. Only when the micro-hydrogen concentration sensor 4a confirms that the hydrogen concentration in the water is extremely low will the central controller 23 instruct the normally closed solenoid valve 4b to open, safely draining the water into the water storage box 16.

[0058] In the liquid recovery and replenishment subsystem, the drain outlets of hydrogen-water separator 3 and air-water separator 15 merge and connect to the inlet 161 of water storage box 16. The amount of liquid flowing from the outlet 163 of water storage box 16 into Venturi mixer 12 is regulated by controlling the opening of the second throttle valve 17. For example... Figure 3As shown, the water level in the water storage box 16 is detected by a level gauge. When the water level reaches the low level gauge 166 alarm value, the opening of the third throttle valve 18 is controlled, and the liquid in the external water tank 19 flows into the water storage box 16 from the water inlet 164 until the high level gauge 165 alarms. Then, the third throttle valve 18 is closed. The water in the external water tank 19 is deionized water. When the high level gauge 165 alarm value is reached, the drain valve 22 is opened, and the liquid is discharged from the drain outlet 167 until the liquid level is lower than the high level gauge 165. Then, the drain valve is closed, and the vent 162 is directly connected to the air.

[0059] The central controller 23 receives signals from various sensors and coordinates the control of the air compressor 14 speed, the opening of the first throttle valve 10, the opening of the second throttle valve 17, the opening of the third throttle valve 18, the main radiator 8 fan speed, the main circulating water pump 6 speed, and the intelligent drain valve 4 and other actuators through algorithms to achieve the global optimal control of the system's water, heat and air.

[0060] This embodiment also provides a control method for a self-humidifying fuel cell system, including: During the operation of the fuel cell system, the pressure in the system is at an ideal value, and the temperature and humidity sensor 21 is used to detect the temperature and humidity of the air entering the stack. Determine if the measured humidity is the required value under the target temperature and pressure. If it is, maintain the opening of the second throttle valve 17; if it is too high, decrease the opening of the second throttle valve 17; if it is too low, increase the opening of the second throttle valve 17. Determine if the measured temperature at the reactor core is the required value. If it is, maintain the opening of the first throttle valve 10. If it is too high, increase the opening of the first throttle valve 10. If it is too low, decrease the opening of the first throttle valve 10.

[0061] A combined control method using a high level gauge 165, a low level gauge 166, a third throttle valve 18, and an exhaust valve 22 is employed to ensure a healthy liquid level in the water storage box. When the high level gauge 165 alarms, the opening of the third throttle valve 18 is reduced, while the drain valve 22 is opened until the high level gauge 165 alarm ends and the drain valve 22 closes. When the low level gauge 166 alarms, the opening of the third throttle valve 18 is increased. When the system shuts down, the third throttle valve 17 and the drain valve 22 are closed.

[0062] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

[0063] It should be noted that, for the sake of simplicity, the foregoing method embodiments are described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0064] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship conventionally placed when using this invention. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0065] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set", "install", and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a wired connection or a wireless connection.

Claims

1. A self-humidifying fuel cell system, characterized in that, Includes: hydrogen supply and circulation subsystem, air supply and humidification subsystem, cooling subsystem, liquid recovery and replenishment subsystem, fuel cell stack (5) and central controller (23); The hydrogen supply and circulation subsystem is connected to the anode flow channel of the fuel cell stack (5) and is used to supply hydrogen to the anode and to perform gas-liquid separation and hydrogen recycling of the anode tail gas. The air supply and humidification subsystem is connected to the cathode flow channel of the fuel cell stack (5) and is used to supply air with suitable temperature and humidity to the cathode and to recover energy and waste heat from the cathode exhaust gas. The cooling subsystem is connected to the cooling channel of the fuel cell stack (5) and is used to regulate the operating temperature of the fuel cell stack (5) and provide a heat exchange medium for the air supply and humidification subsystem. The liquid recovery and replenishment subsystem is connected to the hydrogen supply and circulation subsystem and the air supply and humidification subsystem, respectively, and is used to recover the liquid water generated by the system and provide humidification and water replenishment to the air supply and humidification subsystem; The central controller (23) is electrically connected to each subsystem and is used to regulate the coordinated operation of each subsystem.

2. The self-humidifying fuel cell system according to claim 1, characterized in that, The air supply and humidification subsystem includes an air compressor (12), a venturi mixer (13), a multi-stage heat exchanger (14), and a temperature and humidity sensor (21) connected sequentially along the air intake direction. The probe of the temperature and humidity sensor (21) is connected to the cathode inlet of the fuel cell stack (5). The cathode outlet of the fuel cell stack (5) is connected sequentially to an air-water separator (15), the multi-stage heat exchanger (14), and an expander (20). The expander (20) is coaxially connected to the air compressor (12) to recover the energy of the cathode exhaust gas. The temperature and humidity sensor (21) is electrically connected to the central controller (23).

3. The self-humidifying fuel cell system according to claim 2, characterized in that, The multi-stage heat exchanger (14) includes a primary cooling chamber (14a) and a secondary cooling chamber (14b) that are interconnected. The primary cooling chamber (14a) includes a high-temperature air chamber and a loop air cooling chamber. The high-temperature air chamber is connected to the outlet of the Venturi mixer (13). The loop air cooling chamber is provided with a first heat exchange coil. The two ends of the first heat exchange coil are respectively connected to the outlet of the air-water separator (15) and the inlet of the expander (20). The secondary cooling chamber (14b) is provided with a second heat exchange coil. The second heat exchange coil is connected to the air cooling loop of the cooling subsystem.

4. The self-humidifying fuel cell system according to claim 2, characterized in that, The venturi mixer (13) has a water injection port at its throat. The water injection port is connected to the water storage box (16) of the liquid recovery and replenishment subsystem through a pipeline. A second throttle valve (17) is provided on the pipeline between the water injection port and the water storage box (16). The central controller (23) can control the water flow rate into the venturi mixer (13) by adjusting the opening of the second throttle valve (17).

5. The self-humidifying fuel cell system according to claim 1, characterized in that, The hydrogen supply and circulation subsystem includes a hydrogen source (1) and a hydrogen supply module (2) connected sequentially along the hydrogen supply direction. The outlet of the hydrogen supply module (2) is connected to the anode inlet of the fuel cell stack (5), and the anode outlet of the fuel cell stack (5) is connected to a hydrogen-water separator (3). The gas outlet of the hydrogen-water separator (3) flows back to the inlet of the hydrogen supply module (2), and the liquid outlet of the hydrogen-water separator (3) is connected to the liquid recovery and replenishment subsystem via an intelligent drain valve unit (4).

6. The self-humidifying fuel cell system according to claim 5, characterized in that, The intelligent drainage valve unit (4) includes a micro hydrogen concentration sensor (4a) and a normally closed solenoid valve (4b) connected in series. Both the micro hydrogen concentration sensor (4a) and the normally closed solenoid valve (4b) are electrically connected to the central controller (23). The central controller (23) can receive the hydrogen concentration signal in the drainage flow detected in real time by the micro hydrogen concentration sensor (4a). Only when the detected hydrogen concentration is lower than a preset safety threshold and continues for a predetermined time, the normally closed solenoid valve (4b) is controlled to open for drainage.

7. The self-humidifying fuel cell system according to claim 1, characterized in that, The cooling subsystem includes a main coolant circulation loop and an air cooling loop; the main coolant circulation loop includes a main circulating water pump (6) and a main radiator (8), the main coolant circulation loop flows through the cooling channel of the fuel cell stack (5) to achieve temperature regulation of the fuel cell stack (5); the air cooling loop includes a first throttle valve (10) and a multi-stage heat exchanger (14), the first throttle valve (10) is located at the coolant outlet of the main radiator (8), the heat exchange medium inlet of the multi-stage heat exchanger (14) is connected to the liquid water outlet of the first throttle valve (10), and the first throttle valve (10) is electrically connected to the central controller (23).

8. The self-humidifying fuel cell system according to claim 1, characterized in that, The liquid recovery and replenishment subsystem includes a water storage box (16), a second throttle valve (17), a third throttle valve (18), an external water tank (19), and a drain valve (22). The inlet of the water storage box (16) is connected to the drain outlet of the hydrogen-water separator (3) of the hydrogen supply and circulation subsystem and the drain outlet of the air-water separator (15) of the air supply and humidification subsystem. The external water tank (19) is connected to the water replenishment port of the water storage box (16) via the third throttle valve (18), and the outlet of the water storage box (16) is connected to the air supply and humidification subsystem via the second throttle valve (17). The drain outlet of the water storage box (16) is connected via the drain valve (22). The second throttle valve (17), the third throttle valve (18), and the drain valve (22) are all electrically connected to the central controller (23).

9. The self-humidifying fuel cell system according to claim 1, characterized in that, The central controller (23) is configured to receive the temperature and humidity signals of the cathode inlet air detected in real time by the temperature and humidity sensor (21) in the air supply and humidification subsystem, and adjust the opening of the first throttle valve (10) in the cooling subsystem to regulate the inlet air temperature in conjunction with the operating load of the fuel cell stack (5), and adjust the opening of the second throttle valve (17) in the liquid recovery and replenishment subsystem to regulate the inlet air humidity, so that the temperature and humidity of the cathode inlet air are adapted to the operating requirements of the fuel cell stack (5).

10. A control method for a self-humidifying fuel cell system, applied to the self-humidifying fuel cell system as described in claim 1, characterized in that, The control method includes: The air supply and humidification subsystem uses a temperature and humidity sensor (21) to detect the temperature and humidity of the air at the cathode inlet of the fuel cell stack (5) in real time, and uses a micro hydrogen concentration sensor (4a) to detect the hydrogen concentration in the drained water at the anode of the fuel cell stack (5) in real time. The central controller (23) adjusts the opening of the second throttle valve (17) in the liquid recovery and replenishment subsystem according to the detected humidity data to control the intake air humidification, and adjusts the opening of the first throttle valve (10) in the cooling subsystem according to the detected temperature data to control the intake air heat exchange temperature; only when the detected hydrogen concentration is lower than the preset safety threshold and continues for a predetermined time, the normally closed solenoid valve (4b) in the air supply and humidification subsystem is controlled to open for drainage. The liquid recovery and replenishment subsystem regulates the liquid level of the water storage box (16) through the third throttle valve (18) and the drain valve (22).

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