Methods and systems for improving temperature uniformity in air-cooled proton exchange membrane fuel cell stacks

Abstract

This invention belongs to the field of fuel cell technology and discloses a method for improving the temperature uniformity of an air-cooled proton exchange membrane fuel cell stack. The method includes: S1, configuring an adjustable-direction fan assembly and other functional components such as temperature sensors and controllers for the cathode-open air-cooled proton exchange membrane fuel cell stack as the working object; S2, starting the stack and controlling the fan assembly to run in the initial direction; S3, acquiring real-time temperature data at the inlet and outlet of the stack and calculating the current absolute value of the temperature gradient; S4, combining the real-time absolute value of the temperature gradient with a preset uniformity threshold to determine whether to switch the rotation direction of the fan assembly. This invention also discloses a corresponding system. Through this invention, the fixed temperature gradient at the cathode of the air-cooled fuel cell stack caused by traditional unidirectional cooling is broken, thereby improving the overall temperature uniformity inside the air-cooled fuel cell stack and extending its service life.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell technology, and more specifically, relates to a method and system for improving the temperature uniformity of an air-cooled proton exchange membrane fuel cell stack. Background Technology

[0002] Open-cathode air-cooled proton exchange membrane fuel cells (PEMFCs) have broad application prospects in fields such as drones and portable power supplies due to their compact structure and minimal auxiliary equipment. Their core feature is the use of a fan to drive air through the cathode channel, where this air simultaneously serves the dual functions of providing oxidant and removing waste heat from the reaction.

[0003] In existing technologies, the fans in air-cooled fuel cell stacks typically operate in a single mode, namely a constant "blowing" or "suction": (a) Blowing mode: The fan is installed at the inlet, and air is blown into the fuel cell stack. At this time, the air temperature at the inlet is low (ambient temperature), resulting in strong cooling; however, as the air flows through the fuel cell stack, it absorbs a large amount of heat, and the air temperature rises significantly upon reaching the outlet, reducing cooling capacity. This leads to a low inlet temperature and a high outlet temperature. (b) Suction mode: The fan is installed at the outlet, and air is drawn into the fuel cell stack. This also results in a cold inlet and a hot fan end.

[0004] Extensive practical experience has shown that this fixed flow direction leads to a significant temperature gradient within the fuel cell stack along the cathode gas flow direction. Prolonged operation under non-uniform temperature conditions results in the following problems: on the high-temperature side, the proton exchange membrane is prone to dehydration, leading to increased ohmic impedance and even mechanical damage to the membrane and catalyst degradation; on the low-temperature side, flooding is likely to occur, hindering gas transport. This polarized operating state severely limits the overall performance output and lifespan of the fuel cell stack.

[0005] Patent searches revealed that existing technologies have proposed several solutions to the aforementioned technical challenges, as detailed below: Chinese patent document CN116505018A discloses a fuel cell cooling system device and method for improving battery temperature uniformity. This solution is for water-cooled fuel cells, which reduces the temperature difference between the two sides of the bipolar plates by setting independent first and second temperature regulation branches on both sides and using solenoid valves and water pumps to precisely regulate the flow rate of coolant on both sides. However, this technology is mainly applicable to water-cooled fuel cell stacks with complex coolant circulation systems. The system includes radiators, water pumps, water tanks, and multiple solenoid valves, resulting in a complex structure, large size, and high cost. For air-cooled fuel cell systems that pursue lightweight and portability, introducing such a complex liquid cooling regulation loop is obviously impractical and cannot solve the inherent temperature gradient problem along the airflow direction of the air-cooled fuel cell stack.

[0006] Chinese patent document CN112687911A discloses a method for improving the uniformity of heat distribution inside a water-cooled proton exchange membrane fuel cell stack. This method reduces temperature differences inside the stack by optimizing the flow field arrangement, particularly by adopting a design that arranges the cooling water flow field and the air flow field in opposite directions. Although this flow field design optimization improves temperature uniformity to some extent, it is essentially still a passive thermal management method based on unidirectional flow. Under fixed inlet and outlet conditions, the temperature change trend of the working fluid along the flow channel is inevitable, so it can only alleviate but not fundamentally eliminate the temperature gradient along the flow direction. In addition, this method is also aimed at water-cooled systems, and its core lies in the heat exchange matching between cooling water and reactant gases. For air-cooled stacks that directly utilize air for cooling and reaction, it is impossible to achieve the same effect of temperature uniformity by directly adjusting the flow field arrangement. Summary of the Invention

[0007] To address one or more of the above-mentioned defects or needs of existing technologies, this invention provides a method and system for improving the temperature uniformity of air-cooled proton exchange membrane fuel cell stacks. By closely combining the compact structure and liquid-free cooling loop of the open cathode air-cooled proton exchange membrane fuel cell stack, an innovative real-time temperature monitoring and feedback mechanism for the air-cooled stack is introduced and used to control the adjustable airflow fan assembly. This allows for dynamic and flexible switching between blowing and suction modes during operation, and periodically reversing the airflow direction inside the stack. Consequently, it breaks the inherent temperature distribution pattern of "constantly cold inlet and constant hot outlet" caused by traditional unidirectional cooling from a time perspective. This active bidirectional flow field control scheme does not require the addition of complex flow channel structures or additional cooling media. It can significantly reduce the overall temperature gradient of the air-cooled fuel cell stack simply by controlling the low-cost fan. This effectively avoids damage to the membrane electrode caused by local overheating or overcooling. Thus, while maintaining the lightweight advantage of the air-cooled system, it improves the temperature uniformity and service life of the air-cooled fuel cell stack. Therefore, it is particularly suitable for specific applications of open-cathode air-cooled proton exchange membrane fuel cells.

[0008] To achieve the above objectives, according to one aspect of the present invention, a method for improving the temperature uniformity of an air-cooled proton exchange membrane fuel cell stack is provided, characterized in that the method comprises the following steps: S1, Setting of fan assembly and supporting functional components For a cathode-open air-cooled proton exchange membrane fuel cell stack, which is the working object, a fan assembly with adjustable airflow direction is configured to maintain the airflow channel. The airflow channel has a first port and a second port opposite to each other. The fan assembly is installed at the first or second port and is designed to switch between forward and reverse modes according to control commands, thereby generating a forward airflow from the first port to the second port or a reverse airflow from the second port to the first port in the airflow channel. In addition, a first temperature sensor is installed in the battery stack area near the first port to detect the temperature of the first end. T 1. Simultaneously, a second temperature sensor is installed in the battery stack area near the second port to detect the temperature of the second end. T 2; Simultaneously, the controller is electrically connected to the fan assembly, the first temperature sensor, and the second temperature sensor, respectively, and is used to adjust the temperature... T 1 and T The difference between 2 and 2 is used to control the fan assembly to perform commutation operations; S2, Initial startup of the fuel cell stack Start the cathode open-type air-cooled proton exchange membrane fuel cell stack, control the fan assembly to run in the initial direction, and accordingly provide the fuel cell stack with reactive oxidant and cooling airflow. S3. Temperature monitoring and calculation of fuel cell stack After the cathode-open air-cooled proton exchange membrane fuel cell stack has been operating for a period of time, the temperatures of the first and second ends are acquired in real time using the first and second temperature sensors. T 1 and T 2. And calculate the absolute value of the current temperature gradient. ; S4. Wind direction adjustment and fuel cell stack uniformity control of the wind turbine assembly Determine the absolute value of the calculated temperature gradient. Does it exceed the preset uniformity threshold? , among which when Furthermore, the current wind direction has been in operation for longer than the minimum holding time. Then, the controller causes the fan assembly to perform a reversing operation, reversing the airflow direction; and when Or the current wind direction has not reached the minimum holding time. If the wind direction remains unchanged, the current wind direction will be maintained.

[0009] Based on the above concepts, for the cathode-open air-cooled proton exchange membrane fuel cell stack designed in this invention, after the stack operates in a single airflow direction (e.g., blowing air) for a period of time, the outlet temperature will be significantly higher than the inlet temperature. When the temperature difference between the two ends is monitored... When the set threshold is exceeded, the controller instructs the fan to reverse (switch to suction). At this time, the original air outlet becomes an air inlet, drawing in cold air, and the temperature in that area begins to drop; the original air inlet becomes an air outlet, and the temperature begins to rise. Through this alternating cycle, the temperature on both sides of the battery stack is kept at a similar level.

[0010] As a further preferred embodiment of the present invention, in step S1, the fan assembly is preferably a reversible axial flow fan, and its motor drive circuit has a commutation function or a bidirectional electric adjustment function.

[0011] As a further preferred embodiment of the present invention, in step S1, the controller preferably has a preset fan speed compensation map, which is used to adjust the speed of the fan assembly when switching the rotation direction, so as to compensate for the flow loss caused by the difference in aerodynamic efficiency between forward and reverse rotation.

[0012] As a further preferred embodiment of the present invention, in step S1, the first temperature sensor and the second temperature sensor are preferably thermocouples or thermistors, and there are one or more of them, which are respectively embedded in the membrane electrode surface at a selected position inside the air-cooled proton exchange membrane fuel cell stack.

[0013] As a further preferred embodiment of the present invention, in step S4, the reversing operation process is preferably designed as follows: the controller issues a command to stop the fan assembly from rotating and waits for the fan blade speed to drop to zero or below the safe speed; then, the controller outputs a reverse drive signal to make the fan assembly rotate in the opposite direction, completing the switch from blowing mode to suction mode, or from suction mode to blowing mode.

[0014] As a further preferred embodiment of the present invention, in step S4, if the highest temperature of the cathode open-air-cooled proton exchange membrane fuel cell stack is detected ( Exceeding the preset overheat protection threshold If the fan assembly is forced to operate at its maximum speed and commutation is temporarily prohibited, the temperature will drop to a safe range.

[0015] According to a second aspect of the present invention, a corresponding system for improving the temperature uniformity of an air-cooled proton exchange membrane fuel cell stack is also provided, characterized in that the system includes a wind direction adjustable fan assembly, a first temperature sensor, a second temperature sensor, and a controller, wherein: The fan assemblies are configured for cathode open-air-cooled proton exchange membrane fuel cell stacks as the working objects. They are respectively installed at the first and second ports of the air flow channels that are kept open in the fuel cell stack, and are designed to switch between forward and reverse modes according to control commands, thereby generating a forward airflow from the first port to the second port or a reverse airflow from the second port to the first port in the air flow channels. The first temperature sensor is located in the battery stack area near the first port and is used to detect the temperature of the first end. T 1; The second temperature sensor is located in the battery stack area near the second port and is used to detect the temperature at the second end. T 2; The controller is used to determine the temperature. T 1 and T The difference between 2 is the absolute value of the current temperature gradient. At the same time, combined with a preset uniformity threshold To control the wind turbine assembly to perform a commutation operation, wherein when Furthermore, the current wind direction has been in operation for longer than the minimum holding time. This causes the fan assembly to perform a reversing operation, reversing the airflow direction; and when Or the current wind direction has not reached the minimum holding time. If the wind direction remains unchanged, the current wind direction will be maintained.

[0016] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages: (1) Improve temperature uniformity: It breaks the inherent pattern of "one end is always cold and the other end is always hot" caused by traditional unidirectional cooling. Through periodic reversal, the temperature distribution inside the cathode open air-cooled proton exchange membrane fuel cell stack reaches dynamic equilibrium on the time scale, effectively reducing the overall temperature gradient. (2) Improve battery performance and lifespan: Uniform temperature distribution is conducive to uniform distribution of membrane electrode humidity, avoiding membrane degradation caused by local overheating and water flooding caused by local overcooling, thereby improving the output power stability of the cathode open air-cooled proton exchange membrane fuel cell stack and extending its lifespan. (3) Low cost implementation: The overall system of the present invention does not require the addition of a complex liquid cooling system or additional hardware equipment. It only requires the use of a fan that supports reversal and the addition of a temperature sensor, and can be implemented through various algorithms. Therefore, it is particularly suitable for specific applications of cathode open air-cooled proton exchange membrane fuel cell stacks that are sensitive to cost and weight. Attached Figure Description

[0017] Figure 1 This is a process flow diagram of a method for improving the temperature uniformity of an air-cooled proton exchange membrane fuel cell stack according to the present invention; Figure 2 This is a schematic diagram of a blowing system used to demonstrate the improvement of temperature uniformity in an air-cooled proton exchange membrane fuel cell stack according to the present invention; Figure 3 This is a schematic diagram of the air intake system used to demonstrate the improvement of temperature uniformity in an air-cooled proton exchange membrane fuel cell stack according to the present invention; In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1-Cathode open-type air-cooled proton exchange membrane fuel cell stack; 2-Wind turbine assembly; 3-First temperature sensor; 4-Second temperature sensor; 5-Controller. Detailed Implementation

[0018] 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. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0019] It should be understood that expressions such as "comprising" and "may include" as used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "comprising" and / or "having" may be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or combination thereof, but should not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0020] It should be understood that the terms “center,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application 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 application.

[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0022] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., 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 direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0023] Figure 1 This is a process flow diagram of a method for improving the temperature uniformity of an air-cooled proton exchange membrane fuel cell stack according to the present invention. The following will refer to... Figure 1 This will be explained in more detail to illustrate the present invention.

[0024] like Figure 1 As shown, the method for improving the temperature uniformity of an air-cooled proton exchange membrane fuel cell stack according to the present invention mainly includes the following steps: Step 1: Setting up the fan assembly and supporting functional components In this step, for the cathode open air-cooled proton exchange membrane fuel cell stack that is the object of work, a wind direction adjustable fan assembly is configured for the air flow channel that is kept open. The air flow channel has a first port and a second port that are opposite to each other. The fan assembly is installed at the first or second port and is designed to switch between forward and reverse modes according to control commands, thereby generating a forward airflow from the first port to the second port or a reverse airflow from the second port to the first port in the air flow channel. In addition, a first temperature sensor is installed in the battery stack area near the first port to detect the temperature of the first end. T 1. Simultaneously, a second temperature sensor is installed in the battery stack area near the second port to detect the temperature of the second end. T 2; Simultaneously, the controller is electrically connected to the fan assembly, the first temperature sensor, and the second temperature sensor, respectively, and is used to adjust the temperature... T 1 and T The difference between 2 is used to control the fan assembly to perform commutation operations.

[0025] More specifically, the fan assembly is preferably a reversible axial flow fan in this invention, and its motor drive circuit has a commutation function or a bidirectional electronic speed control function. The controller preferably has a preset fan speed compensation diagram, used to adjust the speed of the fan assembly when switching rotation directions to compensate for flow loss caused by the difference in aerodynamic efficiency between forward and reverse rotation.

[0026] Furthermore, the first and second temperature sensors are preferably thermocouples or thermistors in this invention, and there may be one or more of them, which are respectively embedded in the membrane electrode surface at selected locations inside the air-cooled proton exchange membrane fuel cell stack.

[0027] Step 2: Initial Start-up of the Fuel Cell Stack In this step, the cathode open-type air-cooled proton exchange membrane fuel cell stack is started, and the fan assembly is controlled to run in the initial direction, thereby simultaneously providing reactive oxidant and cooling airflow to the fuel cell stack.

[0028] Step 3: Temperature Monitoring and Calculation of Fuel Cell Stack In this step, after the cathode open-type air-cooled proton exchange membrane fuel cell stack has been running for a period of time, the temperatures of the first and second ends are acquired in real time through the first and second temperature sensors. T 1 and T 2. And calculate the absolute value of the current temperature gradient. ; Step 4: Wind direction adjustment of wind turbine components and uniformity control of fuel cell stack In this step, the absolute value of the calculated temperature gradient is determined. Does it exceed the preset uniformity threshold? , among which when Furthermore, the current wind direction has been in operation for longer than the minimum holding time. Then, the controller causes the fan assembly to perform a reversing operation, reversing the airflow direction; and when Or the current wind direction has not reached the minimum holding time. If the wind direction remains unchanged, the current wind direction will be maintained.

[0029] More specifically, according to a preferred embodiment of the present invention, the reversing operation process is preferably designed as follows: the controller issues a command to stop the fan assembly from rotating and waits for the fan blade speed to drop to zero or below the safe speed; then, the controller outputs a reverse drive signal to make the fan assembly rotate in the opposite direction, completing the switch from blowing mode to suction mode, or from suction mode to blowing mode.

[0030] According to another preferred embodiment of the present invention, if the highest temperature of the cathode open-air-cooled proton exchange membrane fuel cell stack is detected ( Exceeding the preset overheat protection threshold If the fan assembly is forced to operate at its maximum speed and commutation is temporarily prohibited, the temperature will drop to a safe range.

[0031] This invention also provides a corresponding system for improving the temperature uniformity of air-cooled proton exchange membrane fuel cell stacks. Besides the cathode-open air-cooled proton exchange membrane fuel cell stack 1, which serves as the working object, this system also includes an adjustable-direction fan assembly 2, a first temperature sensor 3, a second temperature sensor 4, and a controller 5. The following will describe the system in conjunction with... Figure 2 and Figure 3 Let's explain each one in detail.

[0032] As one of the key components of the present invention, the fan assembly 2 is configured for the cathode open air-cooled proton exchange membrane fuel cell stack 1, which is the working object. They are respectively installed at the first port and the second port of the air flow channel that is kept open in the fuel cell stack, and are designed to switch between forward and reverse modes according to control commands, thereby generating a forward airflow from the first port to the second port or a reverse airflow from the second port to the first port in the air flow channel. Accordingly, the first temperature sensor 3 is disposed in the battery stack area near the first port and is used to detect the temperature of the first end. T 1; The second temperature sensor 4 is located in the battery stack area near the second port and is used to detect the temperature of the second end. T 2; Meanwhile, controller 5 is used to adjust the temperature. T 1 and T The difference between 2 is the absolute value of the current temperature gradient. At the same time, combined with a preset uniformity threshold To control the wind turbine assembly to perform a commutation operation, wherein when Furthermore, the current wind direction has been in operation for longer than the minimum holding time. This causes the fan assembly to perform a reversing operation, reversing the airflow direction; and when Or the current wind direction has not reached the minimum holding time. If the wind direction remains unchanged, the current wind direction will be maintained.

[0033] More specifically, when the temperature difference exceeds the preset uniformity threshold, the controller adjusts the rotation direction of the fan, switching the current blowing mode to the suction mode, or switching the suction mode to the blowing mode, thereby changing the airflow direction inside the air-cooled fuel cell stack.

[0034] In summary, the method and system for improving the temperature uniformity of air-cooled proton exchange membrane fuel cells designed according to this invention innovatively introduces a real-time temperature monitoring and feedback mechanism for the air-cooled fuel cell stack, which is used to drive an adjustable airflow fan assembly. By dynamically switching between blowing and suction modes during operation and periodically reversing the airflow direction inside the fuel cell stack, this invention breaks the inherent temperature distribution pattern of "constantly cold inlet and constantly hot outlet" caused by traditional unidirectional cooling from a time perspective. This active bidirectional flow field control strategy does not require the addition of complex flow channel structures or additional cooling media. It can significantly reduce the overall temperature gradient of the air-cooled fuel cell stack simply through low-cost fan control, effectively avoiding membrane electrode damage caused by local overheating or overcooling. Thus, while maintaining the lightweight advantage of the air-cooled system, it improves the temperature uniformity and service life of the air-cooled fuel cell stack. Therefore, it is particularly suitable for specific applications of cost- and weight-sensitive cathode-open air-cooled proton exchange membrane fuel cells and has good versatility and promotional value.

[0035] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for improving the temperature uniformity of an air-cooled proton exchange membrane fuel cell stack, characterized in that, The method includes the following steps: S1, Setting of fan assembly and supporting functional components For a cathode-open air-cooled proton exchange membrane fuel cell stack, which is the working object, a fan assembly with adjustable airflow direction is configured to maintain the airflow channel. The airflow channel has a first port and a second port opposite to each other. The fan assembly is installed at the first or second port and is designed to switch between forward and reverse modes according to control commands, thereby generating a forward airflow from the first port to the second port or a reverse airflow from the second port to the first port in the airflow channel. In addition, a first temperature sensor is installed in the battery stack area near the first port to detect the temperature of the first end. T 1. Simultaneously, a second temperature sensor is installed in the battery stack area near the second port to detect the temperature of the second end. T 2; Simultaneously, the controller is electrically connected to the fan assembly, the first temperature sensor, and the second temperature sensor, respectively, and is used to adjust the temperature... T 1 and T The difference between 2 and 2 is used to control the fan assembly to perform commutation operations; S2, Initial startup of the fuel cell stack Start the cathode open-type air-cooled proton exchange membrane fuel cell stack, control the fan assembly to run in the initial direction, and accordingly provide the fuel cell stack with reactive oxidant and cooling airflow. S3. Temperature monitoring and calculation of fuel cell stack After the cathode-open air-cooled proton exchange membrane fuel cell stack has been operating for a period of time, the temperatures of the first and second ends are acquired in real time using the first and second temperature sensors. T 1 and T 2. And calculate the absolute value of the current temperature gradient. ; S4. Wind direction adjustment and fuel cell stack uniformity control of the wind turbine assembly Determine the absolute value of the calculated temperature gradient. Does it exceed the preset uniformity threshold? , among which when Furthermore, the current wind direction has been in operation for longer than the minimum holding time. Then, the controller causes the fan assembly to perform a reversing operation, reversing the airflow direction; and when Or the current wind direction has not reached the minimum holding time. If the wind direction remains unchanged, the current wind direction will be maintained.

2. The method as described in claim 1, characterized in that, In step S1, the fan assembly is preferably a reversible axial flow fan, and its motor drive circuit has a commutation function or a bidirectional electric adjustment function.

3. The method as described in claim 1 or 2, characterized in that, In step S1, the controller preferably has a preset fan speed compensation map, which is used to adjust the speed of the fan assembly when switching the rotation direction, so as to compensate for the flow loss caused by the difference in aerodynamic efficiency between forward and reverse rotation.

4. The method according to any one of claims 1-3, characterized in that, In step S1, the first temperature sensor and the second temperature sensor are preferably thermocouples or thermistors, and there are one or more of them, which are respectively embedded in the membrane electrode surface at a selected location inside the air-cooled proton exchange membrane fuel cell stack.

5. The method according to any one of claims 1-4, characterized in that, In step S4, the reversing operation is preferably designed as follows: the controller issues a command to stop the fan assembly from rotating and waits for the fan blade speed to drop to zero or below the safe speed; then, the controller outputs a reverse drive signal to make the fan assembly rotate in the opposite direction, completing the switch from blowing mode to suction mode, or from suction mode to blowing mode.

6. The method as described in any one of claims 1-5, characterized in that, In step S4, if the highest temperature of the cathode open-air-cooled proton exchange membrane fuel cell stack is detected ( Exceeding the preset overheat protection threshold If the fan assembly is forced to operate at its maximum speed and commutation is temporarily prohibited, the temperature will drop to a safe range.

7. A system for improving the temperature uniformity of an air-cooled proton exchange membrane fuel cell, characterized in that, The system includes a wind direction adjustable fan assembly (2), a first temperature sensor (3), a second temperature sensor (4), and a controller (5), wherein: The fan assembly (2) is configured for the cathode open air-cooled proton exchange membrane fuel cell stack as the working object. They are respectively installed at the first port and the second port of the air flow channel that is kept open in the fuel cell stack, and are designed to switch between forward and reverse modes according to control commands, thereby generating a forward airflow from the first port to the second port or a reverse airflow from the second port to the first port in the air flow channel. The first temperature sensor (3) is located in the battery stack area near the first port and is used to detect the temperature of the first end. T 1; The second temperature sensor (4) is located in the battery stack area near the second port and is used to detect the temperature at the second end. T 2; The controller (5) is used to adjust the temperature according to the temperature. T 1 and T The difference between 2 is the absolute value of the current temperature gradient. At the same time, combined with a preset uniformity threshold To control the wind turbine assembly to perform a commutation operation, wherein when Furthermore, the current wind direction has been in operation for longer than the minimum holding time. This causes the fan assembly to perform a reversing operation, reversing the airflow direction; and when Or the current wind direction has not reached the minimum holding time. If the wind direction remains unchanged, the current wind direction will be maintained.

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