A cathode closed air-cooled electric pile system capable of reliable starting at -20 DEG C

Abstract

This invention discloses a closed-loop air-cooled fuel cell stack system with reliable start-up at -20℃, relating to the field of hydrogen fuel cells. It includes: a heating module, in which a fitted heating component is installed at the cathode inlet of the stack for directional heating of the cathode gas input to the stack; and a circulation module, which features a closed cathode gas loop for circulating the cathode gas within the stack via a blower component. This invention ensures stable and reliable start-up of the stack at -20℃. Its closed gas circulation structure effectively isolates external environmental interference, and the directional heating combined with optimized flow channel design significantly improves gas heat exchange efficiency, allowing the internal temperature and humidity of the stack to quickly reach operating standards.

Description

Technical Field

[0001] This invention relates to the field of hydrogen fuel cell technology, specifically to a cathode closed-loop air-cooled fuel cell stack system that can reliably start at -20°C. Background Technology

[0002] Cathode-closed air-cooled fuel cell stacks are compact, highly integrated, and feature simple and efficient heat dissipation and gas supply systems, making them core hydrogen energy conversion devices for portable hydrogen power supplies, vehicle auxiliary power supplies, and other scenarios. With the continuous expansion of hydrogen energy applications, the demand for these stacks in harsh environments such as high-altitude outdoor environments and low-temperature commuting is rapidly increasing. Operating at -20℃ is a key indicator for evaluating the environmental adaptability of fuel cell stacks and a significant technological hurdle for large-scale application in cold-weather scenarios. Cathode-closed air-cooled fuel cell stack technology, adapted for reliable low-temperature startup, has become a core research and development direction for the industry.

[0003] Patent application No. 202110856008.8 discloses a low-temperature start-up system and control method for a fuel cell cathode recirculation system. This application aims to address the problem that "existing technologies can be divided into methods of heat preservation and heating. Heat preservation maintains the battery temperature above 0°C to prevent cold start, but this method is energy-intensive and requires additional system complexity. Heating generally uses PTC or hydrogen catalysis to heat the coolant, such as using the exothermic reaction of hydrogen / oxygen to heat the coolant, but the high-temperature heat flow cannot be fully utilized, resulting in a large amount of waste, and the hydrogen concentration may cause safety issues."

[0004] However, existing fuel cell stacks suffer from single preheating methods, uneven temperature rise, and high flow resistance. They cannot start up quickly and reliably at -20°C and are prone to damaging the membrane electrode.

[0005] To this end, we propose a cathode-closed air-cooled fuel cell stack system that can reliably start at -20℃. Summary of the Invention

[0006] In view of the above-mentioned shortcomings of the prior art, the present invention provides a cathode closed-loop air-cooled fuel cell stack system that can reliably start at -20℃, which can effectively solve the problems of the prior art.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions; This invention discloses a cathode-closed air-cooled fuel cell stack system with reliable start-up at -20℃, comprising: The heating module is fitted with a heating element at the cathode inlet of the fuel cell stack to directionally heat the cathode gas input to the stack. The circulation module has a closed cathode gas circuit to drive the cathode gas to circulate within the stack via a blower. The gas guiding module has micro-ribbed flow channels built into the stack plates to guide the cathode gas to flow and contact directionally. The acquisition module is used to collect real-time operating parameters such as stack temperature, cathode gas humidity, and stack voltage. The startup module is used to control the sequential switching of the three-level startup conditions based on the collected operating parameters. The control module is used to match the startup condition levels and control the progressive loading of the electrode reaction load. The heating module is interconnected with a circulation module and a gas guiding module via a local area network. The gas guiding module is interconnected with a data acquisition module via a local area network. The data acquisition module is interconnected with a start-up module and a control module via a local area network.

[0008] Furthermore, the bonding heating component is a positive temperature coefficient thermistor heating element, which is fully bonded and encapsulated on the outer wall of the fuel cell cathode inlet flow channel; The heating module is connected to the closed cathode gas circuit of the circulation module, and the control terminal of the heating module is electrically connected to the control module.

[0009] Furthermore, the closed cathode gas circuit of the circulation module is connected in series with the cathode cavity of the fuel cell stack, the blower component and the heating module. The blower component is a frequency conversion drive structure. The blower component adjusts the cathode gas circulation flow rate according to the real-time temperature of the fuel cell stack. The closed cathode gas circuit is a closed structure that isolates the external environment. Among them, the cathode gas circulation velocity of the blower component is negatively correlated with the real-time temperature of the fuel cell stack collected by the acquisition module.

[0010] Furthermore, the flow channel of the gas guiding module with microrib structure is a wide and shallow integrated structure. The microrib structure is arranged in an array at equal intervals along the gas flow direction on the inner wall of the flow channel. The convective heat transfer coefficient between the cathode gas and the electrode plate in the flow channel is determined by the following formula: ; In the formula: The convective heat transfer coefficient between the cathode gas and the electrode plate within the flow channel; The thermal conductivity of the cathode gas; The Nusselt number represents the gas flow rate in the flow channel. The Reynolds number for gas flow in the flow channel; The Prünter number of the cathode gas; The hydraulic diameter of the flow channel; , This is the low-temperature heat transfer correction factor corresponding to the micro-rib structure.

[0011] Furthermore, the thermal conductivity of the cathode gas ; In the formula: The reference thermal conductivity of the cathode gas under standard operating conditions; This refers to the real-time thermodynamic temperature of the cathode gas. Standard thermodynamic temperature; Real-time static pressure for a closed cathode gas circuit; Standard atmospheric pressure; This is the thermal conductivity correction index for temperature. The pressure thermal conductivity correction index; Low-temperature heat transfer correction factor The preset value range is [0.25, 0.45], which is the low-temperature heat transfer correction coefficient. The value range is [0.30, 0.5]. When the height of the microrib structure increases or the cathode gas flow rate decreases, When the value increases, the height of the microrib structure decreases, or the cathode gas flow rate increases. When the value decreases; when the width-to-depth ratio of the flow channel increases or the cathode gas temperature decreases, When the value increases, the width-to-depth ratio of the flow channel decreases, or the cathode gas temperature increases, The value decreases.

[0012] Furthermore, the acquisition module integrates a temperature sensing unit, a humidity sensing unit, and a voltage detection unit; The temperature sensing units are distributed across the fuel cell plates, membrane electrodes, and cathode inlet. The humidity sensing unit is embedded in the closed cathode gas circuit. The voltage detection unit collects the voltage of a single fuel cell plate and the total voltage. The signal output terminal of the acquisition module is connected to the signal input terminal of the start-up module and the control module, respectively.

[0013] Furthermore, the three-level startup conditions of the startup module are preheating condition, low-load response condition, and load stabilization condition, respectively. The triggering parameter for the condition switching is determined by the following formula: ; In the formula: This is the trigger factor for the change of operating conditions; This refers to the real-time temperature of the fuel cell stack. The preset operating condition switching temperature threshold; This is the lowest real-time voltage of a single cell in the fuel cell stack. The preset operating condition switching voltage threshold; Real-time relative humidity of the cathode gas; The humidity threshold is set to switch between preset operating conditions. It is a symbolic function; Among them, the sign function The function value is 1 when the independent variable is greater than 0, 0 when the independent variable is equal to 0, and -1 when the independent variable is less than 0. When the trigger factor S equals the preset judgment value, the startup module completes the single-level condition switching in a fixed sequence of preheating condition, low-load response condition, and load stabilization condition.

[0014] Furthermore, the control module uses the real-time temperature of the membrane electrode as the load matching parameter, and the load current for the progressive loading of the electrode response is determined by the following formula: ; In the formula: Apply load current to the fuel cell stack in real time; This is the low-temperature no-load base current of the fuel cell stack. This is a correction factor for low-temperature electrochemical reaction activity; The average temperature of the membrane electrode; This is the standard reaction reference temperature for the fuel cell stack. The control module is based on the real-time load current applied to the fuel cell stack. The load on the fuel cell stack is increased step by step according to the preset step size to complete the progressive loading of the load.

[0015] Furthermore, if either the stack temperature or the cathode gas humidity exceeds a preset safety range, the control module stops loading the load and adjusts the operating power of the blower component. When the fuel cell stack temperature exceeds the preset upper limit of temperature or the cathode gas humidity exceeds the preset upper limit of humidity, the control module stops loading the load and increases the operating power of the blower component. When the fuel cell stack temperature falls below the preset lower limit of temperature, the control module stops loading the load and reduces the operating power of the blower component, so that the fuel cell stack temperature and cathode gas humidity gradually return to the corresponding preset safe range.

[0016] Compared with the known prior art, the technical solution provided by this invention has the following beneficial effects: 1. This invention ensures reliable startup of the fuel cell stack in a low-temperature environment of -20℃ by setting a fitted heating component at the cathode inlet, constructing a closed cathode gas circuit, adopting an electrode flow channel with built-in micro-rib structure, and combining real-time acquisition of operating parameters with three-stage startup and progressive load loading control.

[0017] 2. In this invention, the closed cathode gas circuit can isolate external environmental interference and ensure stable cathode gas circulation. The attached heating component can preheat the gas in a directional manner, improve the heat exchange efficiency at low temperatures, and the micro-rib structure flow channel optimizes the gas flow path, enhances the convective heat exchange effect between the gas and the electrode plate, and makes the heat distribution inside the stack more uniform. The three-level startup mode can be switched in an orderly manner to adapt to the reaction characteristics of cryogenic fuel cell stacks, avoid component damage caused by sudden load increases, and the progressive load loading is precisely controlled according to the real-time status of the fuel cell stack to ensure startup efficiency and operational safety. At the same time, the gas circulation flow rate can be adjusted in real time according to temperature and humidity parameters to stabilize the operating parameters within a safe range, effectively improving the reliability of cryogenic startup and the stability of operation of the fuel cell stack. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0019] Figure 1 This is a schematic diagram of a cathode-closed air-cooled fuel cell stack system that can reliably start at -20℃. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] The present invention will be further described below with reference to embodiments. Example

[0022] This embodiment describes a cathode-closed air-cooled fuel cell stack system that can reliably start at -20°C, such as... Figure 1 As shown, it includes: The heating module is equipped with a fitted heating component at the cathode gas inlet of the fuel cell stack, which is used to perform directional heating of the cathode gas input to the fuel cell stack. The bonding heating element is a positive temperature coefficient thermistor heating element, which is fully bonded to the outer wall of the flow channel of the cathode of the fuel cell stack. The heating module is connected to the closed cathode gas circuit of the circulation module, and the control terminal of the heating module is electrically connected to the control module. The circulation module is equipped with a closed cathode gas circuit, which is used to drive the cathode gas to circulate and transport within the fuel cell stack through the blower component. The closed cathode gas circuit of the circulation module is connected in series with the cathode cavity of the fuel cell stack, the blower component and the heating module. The blower component is a frequency conversion drive structure. The blower component adjusts the cathode gas circulation flow rate according to the real-time temperature of the fuel cell stack. The closed cathode gas circuit is a closed structure that isolates the external environment. Among them, the cathode gas circulation velocity of the blower component has a negative correlation with the real-time temperature of the fuel cell stack collected by the acquisition module: ; In the formula: The real-time circulation velocity of the cathode gas; The reference circulation velocity for the cathode gas; This is the flow rate-temperature adjustment coefficient; Preset a reference temperature for the fuel cell stack; The real-time temperature of the fuel cell stack is collected by the acquisition module. Flow rate-temperature regulation coefficient The value ranges from 0.05 m / (s・℃) to 0.30 m / (s・℃), with the value increasing during the low-temperature startup phase of the fuel cell stack and decreasing during the steady-state operation phase. The above formula adjusts the cathode gas circulation flow rate based on the difference between the real-time temperature of the fuel cell stack and the preset reference temperature. Combined with the flow rate-temperature adjustment coefficient, it realizes the negative correlation between flow rate and temperature. During the low-temperature start-up stage, the flow rate is automatically increased to ensure heat exchange. During the steady-state operation stage, the flow rate is reduced to adapt to the operating conditions, so that the airflow circulation accurately matches the needs of different low-temperature operation stages of the fuel cell stack. The gas guiding module has a flow channel with a micro-rib structure built into the electrode plate of the fuel cell stack, which is used to guide the cathode gas to flow in a directional manner along the flow channel to make contact. The gas guiding module features a shallow, integrated flow channel with microribs. The microribs are evenly spaced along the gas flow direction on the inner wall of the flow channel. The convective heat transfer coefficient between the cathode gas and the electrode plate within the flow channel is determined by the following formula: ; In the formula: The convective heat transfer coefficient between the cathode gas and the electrode plate within the flow channel; The thermal conductivity of the cathode gas; The Nusselt number represents the gas flow rate in the flow channel. The Reynolds number for gas flow in the flow channel; The Prünter number of the cathode gas; The hydraulic diameter of the flow channel; , This is the low-temperature heat transfer correction coefficient corresponding to the micro-rib structure; The above formula integrates the gas thermal conductivity, flow characteristic number and flow channel hydraulic diameter, and introduces a low-temperature heat transfer correction coefficient specific to micro-rib structure to accurately calculate the convective heat transfer efficiency between cathode gas and electrode plate. It is well adapted to the low-temperature heat transfer characteristics of wide and shallow micro-rib flow channel, and effectively improves the fit and accuracy of heat transfer calculation in low-temperature environment. Cathode gas thermal conductivity ; In the formula: The reference thermal conductivity of the cathode gas under standard operating conditions; This refers to the real-time thermodynamic temperature of the cathode gas. Standard thermodynamic temperature; Real-time static pressure for a closed cathode gas circuit; Standard atmospheric pressure; This is the thermal conductivity correction index for temperature. The pressure thermal conductivity correction index; This formula uses the standard operating condition thermal conductivity as a benchmark, and combines the ratio of real-time gas temperature, loop static pressure and standard parameters. It completes the coefficient correction through temperature and pressure thermal conductivity correction index, accurately reflects the influence of temperature and pressure changes in the closed loop on the gas thermal conductivity, and makes the thermal conductivity calculation under special low temperature conditions more in line with the actual operating conditions. Reynolds number of gas flow in the flow channel The Nusselt number of the flow path gas is determined by calculations based on the real-time flow velocity of the cathode gas, the hydraulic diameter of the flow path, and the kinematic viscosity of the cathode gas. Based on the correlation of the microribbed flow channel configuration, the Prandtl number of the cathode gas is determined. Determined by the gas physical properties parameters corresponding to the real-time thermodynamic temperature of the cathode gas; Low-temperature heat transfer correction factor The preset value range is [0.25, 0.45], which is the low-temperature heat transfer correction coefficient. The value range is [0.30, 0.5]. When the height of the microrib structure increases or the cathode gas flow rate decreases, When the value increases, the height of the microrib structure decreases, or the cathode gas flow rate increases. When the value decreases; when the width-to-depth ratio of the flow channel increases or the cathode gas temperature decreases, When the value increases, the width-to-depth ratio of the flow channel decreases, or the cathode gas temperature increases, The value decreases; Among them, the temperature thermal conductivity correction index The preset value range is 0.15~0.35, and the preset value range for the pressure thermal conductivity correction index δ is 0.10~0.25; the greater the deviation of the real-time cathode gas temperature from the standard thermodynamic temperature, The larger the value, the closer the real-time temperature of the cathode gas approaches the standard thermodynamic temperature. The smaller the value, the greater the deviation of the real-time static pressure of the closed cathode gas circuit from the standard atmospheric pressure. The larger the value, the closer the real-time static pressure of the closed cathode gas circuit approaches the standard atmospheric pressure. The smaller the value; The data acquisition module is used to collect real-time operating parameters such as stack temperature, cathode gas humidity, and stack voltage. The data acquisition module integrates a temperature sensing unit, a humidity sensing unit, and a voltage detection unit. Temperature sensing units are distributed on the stack plates, membrane electrodes and cathode air inlet, humidity sensing units are embedded in the closed cathode gas circuit, voltage detection units collect the voltage of individual stack plates and the total voltage, and the signal output terminals of the acquisition modules are connected to the signal input terminals of the start-up module and the control module respectively. The startup module is used to control the sequential switching of the three-level startup conditions of the fuel cell stack based on the collected operating parameters; The three startup conditions of the startup module are preheating condition, low-load response condition, and load stabilization condition, respectively. The triggering parameters for condition switching are determined by the following formula: ; In the formula: This is the trigger factor for the change of operating conditions; This refers to the real-time temperature of the fuel cell stack. The preset operating condition switching temperature threshold; This is the lowest real-time voltage of a single cell in the fuel cell stack. The preset operating condition switching voltage threshold; Real-time relative humidity of the cathode gas; The humidity threshold is set to switch between preset operating conditions. It is a symbolic function; The above formula integrates the differences between the stack temperature, the minimum voltage of a single cell, the cathode gas humidity and the corresponding threshold through a symbolic function to generate a unified operating condition switching judgment factor, thereby realizing the orderly automatic switching of the three operating conditions of preheating, low load response and load stabilization. The multi-parameter collaborative judgment ensures the accuracy and stability of the low temperature start-up operating condition switching. Among them, the sign function The function value is 1 when the independent variable is greater than 0, 0 when the independent variable is equal to 0, and -1 when the independent variable is less than 0. When the trigger factor S equals the preset judgment value, the start module completes the single-level condition switching in a fixed sequence of preheating condition, low-load response condition, and load stabilization condition. The control module is used to match the startup operating condition level and control the progressive loading and operation of the electrode reaction load; The control module uses the real-time temperature of the membrane electrode as the load matching parameter, and the load current for the progressive loading of the electrode reaction is determined by the following formula: ; In the formula: Apply load current to the fuel cell stack in real time; This is the low-temperature no-load base current of the fuel cell stack. This is a correction factor for low-temperature electrochemical reaction activity; The average temperature of the membrane electrode; This is the standard reaction reference temperature for the fuel cell stack. The above formula uses the low-temperature no-load base current as a reference, and combines the difference between the average temperature of the membrane electrode and the standard reference temperature to calculate the real-time load current through the reaction activity correction coefficient, so that the load can be dynamically increased with the temperature of the membrane electrode, thereby matching the change law of the stack reaction activity at low temperature and ensuring the smooth and progressive loading of the load. The control module applies load current to the fuel cell stack in real time. The load on the fuel cell stack is increased step by step according to the preset step size to complete the progressive loading of the load; Among them, the low-temperature electrochemical reaction activity correction coefficient The preset value range is [0.02℃⁻¹, 0.08℃⁻¹]; the preset step size is determined by the real-time change in the average temperature of the membrane electrode, specifically 0.2 to 0.8 times the change in the average temperature of the membrane electrode. If either the fuel cell stack temperature or the cathode gas humidity exceeds the preset safe range, the control module will stop the load loading and adjust the operating power of the blower component. When the fuel cell stack temperature exceeds the preset upper limit of temperature or the cathode gas humidity exceeds the preset upper limit of humidity, the control module stops loading the load and increases the operating power of the blower component. When the fuel cell stack temperature falls below the preset lower limit of temperature, the control module stops loading the load and reduces the operating power of the blower component, so that the fuel cell stack temperature and cathode gas humidity gradually return to the corresponding preset safe range. The heating module is interconnected with the circulation module and the air guiding module via a local area network. The air guiding module is interconnected with the data acquisition module via a local area network. The data acquisition module is interconnected with the start-up module and the control module via a local area network.

[0023] In this embodiment, the heating module performs directional heating of the cathode gas input to the fuel cell stack, the circulation module simultaneously drives the cathode gas to circulate and transport within the fuel cell stack through the blower component, the gas guiding module guides the cathode gas to flow directionally along the flow channel in real time, the acquisition module collects real-time operating parameters of the fuel cell stack temperature, cathode gas humidity and fuel cell stack voltage, and then the start-up module controls the fuel cell stack to perform sequential switching of three-level start-up conditions based on the collected operating parameters, and finally the control module matches the start-up condition level and controls the progressive loading and operation of the electrode reaction load.

[0024] In the above embodiments, the system can ensure stable and reliable startup of the fuel cell stack in a low-temperature environment of -20℃. Its closed gas circulation structure can effectively isolate external environmental interference. Directional heating combined with optimized flow channel design greatly improves gas heat exchange efficiency, allowing the internal temperature and humidity of the fuel cell stack to quickly reach the operating standard. The three-stage progressive startup combined with precise load control can avoid damage to the fuel cell stack caused by low-temperature startup, ensure stable and efficient electrode response, and at the same time adjust the operating parameters in real time to maintain system stability, effectively extend the service life of the fuel cell stack, and ensure long-term reliability in low-temperature scenarios.

[0025] It should be explained; The wide and shallow flow channel with microrib structure has a microrib height of 0.3mm to 0.8mm, a width of 0.2mm to 0.5mm, a center-to-center distance of 1.5mm to 3.0mm between adjacent microribs, a width-to-depth ratio of 8:1 to 15:1, a depth of 0.5mm to 1.2mm, and a width of 4.0mm to 12.0mm. The hydraulic diameter of the flow channel is calculated and determined according to conventional formulas.

[0026] The closed cathode gas circuit uses corrosion-resistant insulated pipelines to connect the cathode chamber, blower components and heating module of the fuel cell stack in series. The interfaces are sealed with fluororubber sealing rings. The cathode gas is dry compressed air. The static pressure of the circuit is controlled at 105 kPa to 120 kPa. The volume is 1.2 to 1.5 times the effective reaction volume of the fuel cell stack. A pressure balancing valve is provided to maintain pressure stability.

[0027] The positive temperature coefficient thermistor has a rated power of 50W to 200W and a heating temperature of 20℃ to 80℃. It is fully encapsulated on the outer wall of the cathode air inlet channel with 0.1mm to 0.3mm thick thermally conductive silicone. The heating power is precisely controlled by the control module through PID adjustment.

[0028] The blower unit uses a DC inverter centrifugal fan with a rated air volume of 10m³ / h to 30m³ / h and an air pressure of 500Pa to 1500Pa. It uses PWM frequency conversion speed regulation and automatically adjusts the speed according to the negative correlation between temperature and flow rate. It speeds up when starting at low temperature and slows down after heating up.

[0029] The system modules communicate with each other via a CAN bus with a communication rate of 125kbps to 500kbps. Each module is equipped with a CAN communication interface to achieve real-time transmission and coordination of operating parameters and control commands.

[0030] In the above embodiments, all correction coefficients, adjustment coefficients and reference parameters in the system are determined through low-temperature performance calibration tests; the operating condition switching threshold and safety range are set according to the rated power of the fuel cell stack and the tolerance parameters of the membrane electrode; the reference temperature, reference flow rate and no-load base current are taken according to the conventional low-temperature start-up standard.

[0031] The preset judgment value of the operating condition switching trigger factor S is 1. When the temperature, voltage and humidity threshold conditions are met, the operating condition is automatically switched. In the preheating operating condition, only heating and circulation are started. In the low load reaction operating condition, 5% to 10% of the rated load is loaded. In the load stabilization operating condition, the load is gradually increased to the rated load in steps of 0.5 times the temperature change.

[0032] All calculation formulas are applicable to low-temperature start-up conditions from -40℃ to 25℃. Before calculation, the calculations are calibrated according to the fuel cell stack model and gas physical parameters. The Reynolds number, Nusselt number, and Prandtl number are calculated using conventional gas dynamics methods. The calculation results can be directly used for heat exchange efficiency assessment and load control.

[0033] Application examples of the system: The portable hydrogen fuel cell power supply device is designed for use in low-temperature outdoor environments. Equipped with this proprietary system, the device can reliably start up and stably supply power to the fuel cell stack in outdoor working environments with ambient temperatures as low as -20°C, without the need for external auxiliary heating equipment. It can meet the low-temperature continuous power supply needs of scenarios such as field exploration, emergency communication, and outdoor scientific research.

[0034] In this application scenario, the initial ambient temperature of the fuel cell stack is -20℃. After the system starts up, the acquisition module collects temperature data of the fuel cell stack plates, membrane electrodes, and cathode inlet, as well as gas humidity data in the sealed cathode circuit and individual stack voltage and total voltage data in real time through distributed temperature sensing units, humidity sensing units, and voltage detection units. The above operating parameters are synchronously transmitted to the start-up module and control module to provide a basis for system operating condition switching and load regulation.

[0035] The heating module employs a fully bonded positive temperature coefficient thermistor at the cathode gas inlet of the fuel cell stack to preheat the cathode gas entering the stack. This heating module is connected to a closed cathode gas circuit, and the control module precisely adjusts the heating power based on real-time operating parameters to ensure that the cathode gas temperature rises rapidly to the appropriate reaction range. The circulation module uses a frequency-controlled blower to drive the cathode gas to circulate within the closed circuit formed by the fuel cell stack cathode cavity, the blower, and the heating module. The blower adjusts the gas circulation flow rate according to the real-time temperature of the fuel cell stack. During the low-temperature start-up phase, the flow rate is maintained at a high level. As the fuel cell stack temperature gradually increases, the flow rate decreases according to a preset rule to ensure rapid and uniform heat transfer at low temperatures.

[0036] The gas guiding module adopts a wide and shallow integrated flow channel with micro-rib structure built into the electrode plate. The micro-rib structure is evenly distributed in an array along the gas flow direction, which effectively improves the convective heat transfer efficiency between the cathode gas and the electrode plate. According to calculations, this flow channel can make the convective heat transfer coefficient reach the ideal value in the initial stage of startup at -20℃, meeting the requirements for rapid heat transfer at low temperatures.

[0037] Based on the parameters acquired by the acquisition module, the startup module switches between three operating modes in sequence: preheating, low-load reaction, and load stabilization. When the stack temperature, minimum single-cell voltage, and cathode gas humidity all reach preset switching thresholds, the system automatically advances to the next operating mode without manual intervention. In preheating mode, the system only activates heating and circulation functions to rapidly increase the overall stack temperature. In low-load reaction mode, the stack begins a low-power reaction, maintaining a gentle balance between heat generation and humidity. In load stabilization mode, the stack gradually increases its output capacity, entering a stable operating state.

[0038] The control module uses the real-time temperature of the membrane electrode as the core matching parameter and progressively loads the electrode reaction load according to preset rules. The load current gradually increases as the membrane electrode temperature rises, and the loading step size is dynamically adjusted based on real-time changes in the membrane electrode temperature to avoid membrane electrode damage caused by rapid loading at low temperatures. During operation, if the stack temperature or cathode gas humidity exceeds the preset safe range, the control module immediately stops loading the load and adjusts the power of the blower component: increasing the blower power to accelerate heat dissipation and dehumidification when the temperature or humidity is too high, and decreasing the blower power to reduce heat loss when the temperature is too low, so that all parameters quickly return to the safe range and ensure long-term stable operation of the system.

[0039] In this application example, the system completed startup and entered steady-state operation in a short time at -20℃. There were no abnormalities such as icing, voltage drop, or reaction interruption during the startup process. After operation, the stack temperature, humidity, and output voltage remained within a stable range, continuously providing power to outdoor equipment.

[0040] In summary, the system in the above embodiments ensures reliable startup of the fuel cell stack at -20°C by setting a fitted heating component at the cathode inlet, constructing a closed cathode gas circuit, adopting an electrode channel with an internal microrib structure, and combining real-time acquisition of operating parameters with three-stage startup and progressive load loading control. Its closed cathode gas circuit isolates external environmental interference, ensuring stable cathode gas circulation. The fitted heating component preheats the incoming gas in a directional manner, improving heat exchange efficiency at low temperatures. The microrib structure optimizes the gas flow path, enhancing the convective heat exchange effect between the gas and the electrode, resulting in a more uniform heat distribution within the fuel cell stack. The orderly switching of the three-stage startup conditions adapts to the reaction characteristics of the low-temperature fuel cell stack, avoiding component damage caused by sudden load increases. The progressive load loading is precisely controlled based on the real-time status of the fuel cell stack, ensuring startup efficiency and operational safety. Simultaneously, the gas circulation rate can be adjusted in real-time according to temperature and humidity parameters, stabilizing operating parameters within a safe range, effectively improving the reliability and stability of the fuel cell stack's low-temperature startup.

[0041] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A cathode-closed air-cooled fuel cell stack system with reliable start-up at -20℃, characterized in that, include: The heating module is equipped with a fitted heating component at the cathode gas inlet of the fuel cell stack, which is used to perform directional heating of the cathode gas input to the fuel cell stack. The circulation module is equipped with a closed cathode gas circuit, which is used to drive the cathode gas to circulate and transport within the fuel cell stack through the blower component. The gas guiding module has a flow channel with a micro-rib structure built into the electrode plate of the fuel cell stack, which is used to guide the cathode gas to flow in a directional manner along the flow channel to make contact. The data acquisition module is used to collect real-time operating parameters such as stack temperature, cathode gas humidity, and stack voltage. The startup module is used to control the sequential switching of the three-level startup conditions of the fuel cell stack based on the collected operating parameters; The control module is used to match the startup operating condition level and control the progressive loading and operation of the electrode reaction load.

2. The cathode-closed air-cooled fuel cell stack system with reliable start-up at -20℃ according to claim 1, characterized in that, The bonding heating element is a positive temperature coefficient thermistor heating element, which is fully bonded to the outer wall of the fuel cell cathode inlet flow channel. The heating module is connected to the closed cathode gas circuit of the circulation module, and the control terminal of the heating module is electrically connected to the control module.

3. The cathode-closed air-cooled fuel cell stack system with reliable start-up at -20℃ according to claim 2, characterized in that, The closed cathode gas circuit of the circulation module is connected in series with the cathode cavity of the fuel cell stack, the blower component and the heating module. The blower component is a frequency conversion drive structure. The blower component adjusts the cathode gas circulation flow rate according to the real-time temperature of the fuel cell stack. The closed cathode gas circuit is a closed structure that isolates the external environment. Among them, the cathode gas circulation velocity of the blower component is negatively correlated with the real-time temperature of the fuel cell stack collected by the acquisition module.

4. The cathode-closed air-cooled fuel cell stack system with reliable start-up at -20℃ according to claim 1, characterized in that, The gas guiding module has a shallow, integrated flow channel with microribs. The microribs are arranged in an array at equal intervals along the gas flow direction on the inner wall of the flow channel. The convective heat transfer coefficient between the cathode gas and the electrode plate in the flow channel is determined by the following formula: ； In the formula: The convective heat transfer coefficient between the cathode gas and the electrode plate within the flow channel; The thermal conductivity of the cathode gas; The Nusselt number represents the gas flow rate in the flow channel. The Reynolds number for gas flow in the flow channel; The Prünter number of the cathode gas; The hydraulic diameter of the flow channel; , This is the low-temperature heat transfer correction factor corresponding to the micro-rib structure.

5. A cathode-closed air-cooled fuel cell stack system with reliable start-up at -20℃ as described in claim 4, characterized in that, Cathode gas thermal conductivity ; In the formula: The reference thermal conductivity of the cathode gas under standard operating conditions; This refers to the real-time thermodynamic temperature of the cathode gas. Standard thermodynamic temperature; Real-time static pressure for a closed cathode gas circuit; Standard atmospheric pressure; This is the thermal conductivity correction index for temperature. The pressure thermal conductivity correction index; Low-temperature heat transfer correction factor The preset value range is [0.25, 0.45], which is the low-temperature heat transfer correction coefficient. The value range is [0.30, 0.5]. When the height of the microrib structure increases or the cathode gas flow rate decreases, When the value increases, the height of the microrib structure decreases, or the cathode gas flow rate increases. When the value decreases; when the width-to-depth ratio of the flow channel increases or the cathode gas temperature decreases, When the value increases, the width-to-depth ratio of the flow channel decreases, or the cathode gas temperature increases, The value decreases.

6. The cathode-closed air-cooled fuel cell stack system with reliable start-up at -20℃ according to claim 1, characterized in that, The acquisition module integrates a temperature sensing unit, a humidity sensing unit, and a voltage detection unit. The temperature sensing units are distributed across the fuel cell plates, membrane electrodes, and cathode inlet. The humidity sensing unit is embedded in the closed cathode gas circuit. The voltage detection unit collects the voltage of a single fuel cell plate and the total voltage. The signal output terminal of the acquisition module is connected to the signal input terminal of the start-up module and the control module, respectively.

7. A cathode-closed air-cooled fuel cell stack system with reliable start-up at -20℃ as described in claim 1, characterized in that, The three-level startup conditions of the startup module are preheating condition, low-load response condition, and load stabilization condition, respectively. The triggering parameter for the condition switching is determined by the following formula: ； In the formula: This is the trigger factor for the change of operating conditions; This refers to the real-time temperature of the fuel cell stack. The preset operating condition switching temperature threshold; This is the lowest real-time voltage of a single cell in the fuel cell stack. The preset operating condition switching voltage threshold; Real-time relative humidity of the cathode gas; The humidity threshold is set to switch between preset operating conditions. It is a symbolic function; Among them, the sign function The function value is 1 when the independent variable is greater than 0, 0 when the independent variable is equal to 0, and -1 when the independent variable is less than 0. When the trigger factor S equals the preset judgment value, the startup module completes the single-level condition switching in a fixed sequence of preheating condition, low-load response condition, and load stabilization condition.

8. The cathode-closed air-cooled fuel cell stack system with reliable start-up at -20℃ according to claim 1, characterized in that, The control module uses the real-time temperature of the membrane electrode as the load matching parameter, and the load current for the progressive loading of the electrode response is determined by the following formula: ； In the formula: Apply load current to the fuel cell stack in real time; This is the low-temperature no-load base current of the fuel cell stack. This is a correction factor for low-temperature electrochemical reaction activity; The average temperature of the membrane electrode; This is the standard reaction reference temperature for the fuel cell stack. The control module is based on the real-time load current applied to the fuel cell stack. The load on the fuel cell stack is increased step by step according to the preset step size to complete the progressive loading of the load.

9. A cathode-closed air-cooled fuel cell stack system with reliable start-up at -20℃ according to claim 1, characterized in that, When either the fuel cell stack temperature or the cathode gas humidity exceeds a preset safety range, the control module stops load loading and adjusts the operating power of the blower component. When the fuel cell stack temperature exceeds the preset upper limit of temperature or the cathode gas humidity exceeds the preset upper limit of humidity, the control module stops loading the load and increases the operating power of the blower component. When the fuel cell stack temperature falls below the preset lower limit of temperature, the control module stops loading the load and reduces the operating power of the blower component, so that the fuel cell stack temperature and cathode gas humidity gradually return to the corresponding preset safe range.

10. A cathode-closed air-cooled fuel cell stack system with reliable start-up at -20℃ according to claim 1, characterized in that, The heating module is interconnected with a circulation module and a gas guiding module via a local area network. The gas guiding module is interconnected with a data acquisition module via a local area network. The data acquisition module is interconnected with a start-up module and a control module via a local area network.

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