An online fault diagnosis method for active area of ​​fuel cell catalyst

Abstract

This invention relates to an online fault diagnosis method for the active area of ​​fuel cell catalysts, comprising the following steps: S1. Selecting and executing an online fault diagnosis mode for the active area of ​​fuel cell catalysts; S2. Monitoring and recording the single-electrode voltage of each membrane electrode using a single-electrode voltage monitor (CVM); S3. After each recording of the single-electrode voltage of each membrane electrode in the stack, calculating the catalyst active area of ​​each membrane electrode accordingly; S4. Determining whether the fuel cell has malfunctioned due to catalyst activity loss based on the calculated catalyst active area of ​​the membrane electrodes. Using the existing single-electrode voltage monitor (CVM) for fuel cells, and based on a precise algorithm, the catalyst active area of ​​each membrane electrode in the stack can be calculated simply and effectively. The catalyst activity loss of the fuel cell can be determined based on the catalyst active area of ​​the membrane electrodes, and online detection of the catalyst active area is also achieved, providing strong support for accurately locating factors contributing to the lifespan degradation of fuel cell stacks.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and specifically to an online fault diagnosis method for the active area of ​​a fuel cell catalyst. Background Technology

[0002] Due to its advantages such as high efficiency, environmental friendliness, and renewability, fuel cells, as a new energy source, have become an important direction for future energy development. High-quality catalysts are essential for the long-term stable operation of fuel cells, and the active area of ​​the catalyst is a crucial indicator of catalyst activity, significantly impacting fuel cell efficiency and lifespan. Catalyst active area refers to the number of available catalytic active sites per unit mass of catalyst surface, and is a fundamental parameter of the reaction rate. Under the same conditions, a larger active area results in a faster reaction rate and better fuel cell performance.

[0003] Fuel cells are complex systems involving multiple physics fields and dimensions, and are prone to failure. In the laboratory stage, we typically use high-end equipment to test the electrochemical performance of the cells for fault diagnosis. However, most experimental equipment is expensive and cannot be used outside of experimental scenarios. Furthermore, general diagnostics are mostly for single cells and not applicable to stacks with multiple individual cells. In practical applications, frequent load variations lead to catalyst activity loss in fuel cells, affecting stack lifespan and performance. However, current technology lacks a method for real-time monitoring of catalyst active area.

[0004] Therefore, there is an urgent need to design an online fault diagnosis method for the active area of ​​fuel cell catalysts to solve the problems existing in the above-mentioned technologies. Summary of the Invention

[0005] In view of this, the present invention provides an online fault diagnosis method for the active area of ​​fuel cell catalysts. The purpose is to calculate the active area of ​​the catalyst for each membrane electrode in the fuel cell stack by designing a detection method and a precise algorithm, and at the same time realize the online detection of the active area of ​​the catalyst.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for online fault diagnosis of active area of ​​fuel cell catalyst includes the following steps:

[0008] S1. Select and execute the online fault diagnosis mode for the active area of ​​the fuel cell catalyst;

[0009] S2. Monitor and record the individual voltage of each membrane electrode using a single-electrode voltage monitor (CVM). Where n represents the nth film electrode in the stack, and the value of n is {1, 2, 3, 4, 5, ...}; x represents the xth record, and the value of x is {1, 2, 3, 4, 5, ...};

[0010] S3. After recording the voltage of each individual membrane electrode in the fuel cell stack, calculate the catalyst active area of ​​each membrane electrode accordingly. Where n represents the nth film electrode in the stack, and the value of n is {1, 2, 3, 4, 5, ...}; x represents the xth record, and the value of x is {1, 2, 3, 4, 5, ...};

[0011] S4. Based on the calculated catalyst active area of ​​the membrane electrode. Determine if the fuel cell is malfunctioning due to catalyst activity loss.

[0012] Furthermore, in step S3, the catalyst active area of ​​each membrane electrode is calculated accordingly. Specifically as follows:

[0013] The active surface area A of the catalyst is directly proportional to the exchange current density I, that is:

[0014] A = k * I (1);

[0015] In the formula, k is the corresponding coefficient; the corresponding coefficient k is related to the composition of the catalyst used in the fuel cell stack, and the corresponding coefficient k is obtained based on the initial exchange current density I0 and the initial electrochemical active area A0.

[0016] Furthermore, the exchange current density I is calculated by the following formula:

[0017]

[0018] In the formula, R is the gas constant with a value of 8.314 J / mol / K; T is the stack operating temperature, measured by a temperature sensor placed at the stack coolant inlet; F is the Faraday constant with a value of 96485; i is the operating current density, obtained through measurement; V act To activate the loss voltage.

[0019] Furthermore, when the operating current density is i, the activation loss voltage V act Calculated by the following formula:

[0020] V act =V r -V i (3);

[0021] In the formula, V r V represents the ideal potential of a fuel cell; iThe operating voltage is i, which is monitored and recorded by a single-chip voltage monitor (CVM).

[0022] Furthermore, the ideal potential V of the fuel cell r Calculated by the following formula:

[0023]

[0024] In the formula, T is the operating temperature of the fuel cell stack, which is measured by a temperature sensor placed at the coolant inlet of the fuel cell stack; The partial pressure of hydrogen is calculated by measuring and using pressure and temperature / humidity sensors located at the anode inlet of the fuel cell stack. The oxygen partial pressure is calculated by measuring and using pressure and temperature / humidity sensors located at the cathode inlet of the fuel cell stack.

[0025] Furthermore, the partial pressure of hydrogen The specific calculation method is as follows: The partial pressure of water at the anode inlet of the fuel cell stack is calculated using the temperature and humidity sensor readings. The total gas pressure of the gas entering the anode is measured using the pressure sensor at the anode inlet. The partial pressure of hydrogen is then obtained by subtracting the partial pressure of water at the anode inlet from the total gas pressure entering the anode. oxygen partial pressure The specific calculation method is as follows: The partial pressure of water at the cathode inlet of the fuel cell stack is calculated using the temperature and humidity sensor readings. The total gas pressure of the gas entering the cathode is measured using the pressure sensor at the cathode inlet. The partial pressure of water at the cathode inlet is subtracted from the total gas pressure entering the cathode. This difference is multiplied by the oxygen proportion coefficient of 0.21 to obtain the partial pressure of oxygen.

[0026] Furthermore, the specific method for calculating the corresponding coefficient k is as follows:

[0027] For a brand new membrane electrode, the initial electrochemical active area A0 is obtained by consulting the membrane electrode parameter table; through normal load testing, the operating current density of the stack is set to i0 = 0.1 A / cm². 2 ;

[0028] Record the stack operating temperature T0 and hydrogen partial pressure under the current initial operating conditions. oxygen partial pressure The ideal potential V of the fuel cell can be calculated using formula (4). r ;

[0029] Simultaneously, the current voltage of each membrane electrode is monitored and recorded using a single-chip voltage monitor (CVM). Where n represents the nth film electrode in the stack, and the value of n is {1, 2, 3, 4, 5, ...}; the corresponding activation loss V is calculated according to formula (3). act ;

[0030] Then, the initial exchange current density I0 is calculated according to formula (2);

[0031] Substitute the initial exchange current density I0 and the initial electrochemical active area A0 into formula (1) to obtain the corresponding coefficient k.

[0032] Furthermore, in step S1, the fuel cell catalyst active area is in online fault diagnosis mode, i.e., maintaining the same initial operating conditions and keeping the stack's operating current density at i0 = 0.1 A / cm². 2 The fuel cell stack operating temperature is T0, and the hydrogen partial pressure is... The partial pressure of oxygen is

[0033] Furthermore, step S4 is detailed as follows:

[0034] Real-time measurement of the catalyst active area of ​​each membrane electrode With respect to the initial catalyst active area of ​​the membrane electrode In contrast, when at least one membrane electrode has a catalyst active area The fuel cell then stops operating normally, indicating severe performance loss of the membrane electrode assembly (MEA), and enters fuel cell maintenance mode, replacing the corresponding MEA. When the catalyst active area of ​​all MEAs reaches its maximum value... This indicates that the membrane electrode assembly of the fuel cell is functioning normally. The online fault diagnosis mode for the active area of ​​the fuel cell catalyst is then turned off, and the fuel cell enters normal operation mode. After a fixed experimental cycle, steps S1-S4 are repeated.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] The above-described online fault diagnosis method for fuel cell catalyst active area eliminates the need for complex and expensive experimental equipment or placing the fuel cell in a specific experimental environment. Using the existing single-cell voltage monitor (CVM) of the fuel cell, the catalyst active area of ​​each membrane electrode in the stack can be calculated simply and effectively based on a precise algorithm. The catalyst active area of ​​the membrane electrode can then be used to determine the catalyst activity loss of the fuel cell. This method also enables online detection of the catalyst active area, providing strong support for accurately locating the factors that cause fuel cell stack lifespan degradation.

[0037] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 A flowchart of an online fault diagnosis method for the active area of ​​a fuel cell catalyst according to an embodiment of the present invention is shown. Detailed Implementation

[0040] 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 embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] This invention proposes an online fault diagnosis method for the active area of ​​a fuel cell catalyst, as shown in the attached figure. Figure 1 As shown, it includes the following steps:

[0042] S1. Select and execute the online fault diagnosis mode for the active area of ​​the fuel cell catalyst;

[0043] S2. Monitor and record the individual voltage of each membrane electrode using a single-electrode voltage monitor (CVM). Where n represents the nth membrane electrode in the fuel cell stack, and the value of n is {1, 2, 3, 4, 5, ...}; x represents the xth record, and the value of x is {1, 2, 3, 4, 5, ...}; for example, the voltage of each membrane electrode recorded in the first record is...

[0044] S3. After recording the voltage of each individual membrane electrode in the fuel cell stack, calculate the catalyst active area of ​​each membrane electrode accordingly. Where n represents the nth membrane electrode in the fuel cell stack, and the value of n is {1, 2, 3, 4, 5, ...}; x represents the xth record, and the value of x is {1, 2, 3, 4, 5, ...}; for example, the catalyst active area of ​​each membrane electrode calculated after the first record is...

[0045] S4. Based on the calculated catalyst active area of ​​the membrane electrode. Determine if the fuel cell is malfunctioning due to catalyst activity loss.

[0046] In step S3, the catalyst active area of ​​each membrane electrode is calculated accordingly. Specifically as follows:

[0047] The active surface area A of the catalyst is directly proportional to the exchange current density I, that is:

[0048] A = k * I;

[0049] In the formula, k is the corresponding coefficient; the corresponding coefficient k is related to the composition of the catalyst used in the fuel cell stack, and the corresponding coefficient k is obtained based on the initial exchange current density I0 and the initial electrochemical active area A0.

[0050] In a fuel cell, the activation loss voltage V act Calculated by the following formula:

[0051]

[0052] In the formula, R is the gas constant with a value of 8.314 J / mol / K; T is the stack operating temperature, which is measured by a temperature sensor placed at the stack coolant inlet; F is the Faraday constant with a value of 96485; i is the operating current density, which is obtained by measurement; and I is the exchange current density.

[0053] As can be seen from the above equation, under the same operating conditions, the magnitude of the exchange current density I is related to the activity of the catalyst.

[0054] According to the above formula, the exchange current density I is calculated by the following formula:

[0055]

[0056] In the formula, R is the gas constant with a value of 8.314 J / mol / K; T is the stack operating temperature, measured by a temperature sensor placed at the stack coolant inlet; F is the Faraday constant with a value of 96485; i is the operating current density, obtained through measurement; V act To activate the loss voltage.

[0057] When the operating current density is i, the activation loss voltage Vact Calculated by the following formula:

[0058] V act =V r -V i ;

[0059] In the formula, V r V represents the ideal potential of a fuel cell; i The operating voltage is i, which is monitored and recorded by a single-chip voltage monitor (CVM).

[0060] Ideal potential V of fuel cell r Calculated by the following formula:

[0061]

[0062] In the formula, T is the operating temperature of the fuel cell stack, which is measured by a temperature sensor placed at the coolant inlet of the fuel cell stack; The partial pressure of hydrogen is calculated by measuring and using pressure and temperature / humidity sensors located at the anode inlet of the fuel cell stack. The oxygen partial pressure is calculated by measuring and using pressure and temperature / humidity sensors located at the cathode inlet of the fuel cell stack.

[0063] hydrogen partial pressure The specific calculation method is as follows: The partial pressure of water at the anode inlet of the fuel cell stack is calculated using the temperature and humidity sensor readings. The total gas pressure of the gas entering the anode is measured using the pressure sensor at the anode inlet. The partial pressure of hydrogen is then obtained by subtracting the partial pressure of water at the anode inlet from the total gas pressure entering the anode. oxygen partial pressure The specific calculation method is as follows: The partial pressure of water at the cathode inlet of the fuel cell stack is calculated using the temperature and humidity sensor readings. The total gas pressure of the gas entering the cathode is measured using the pressure sensor at the cathode inlet. The partial pressure of water at the cathode inlet is subtracted from the total gas pressure entering the cathode. This difference is multiplied by the oxygen proportion coefficient of 0.21 to obtain the partial pressure of oxygen.

[0064] The specific method for calculating the corresponding coefficient k is as follows:

[0065] For a brand new membrane electrode, the initial electrochemical active area A0 is obtained by consulting the membrane electrode parameter table; through normal load testing, the operating current density of the stack is set to i0 = 0.1 A / cm². 2 ;

[0066] Record the stack operating temperature T0 and hydrogen partial pressure under the current initial operating conditions. oxygen partial pressure Find the ideal potential V of the corresponding fuel cell. r ;

[0067] Simultaneously, the current voltage of each membrane electrode is monitored and recorded using a single-chip voltage monitor (CVM). Where n represents the nth membrane electrode in the fuel cell stack, and the value of n is {1, 2, 3, 4, 5, ...}; for example, the single-electrode voltage of each membrane electrode is recorded as... Calculate the corresponding activation loss V act ;

[0068] Then the initial exchange current density I0 is calculated;

[0069] The corresponding coefficient k is obtained based on the initial exchange current density I0 and the initial electrochemical active area A0.

[0070] In step S1, the fuel cell catalyst active area is in online fault diagnosis mode, i.e., the initial operating conditions are maintained, and the stack's operating current density is maintained at i0 = 0.1 A / cm². 2 The fuel cell stack operating temperature is T0, and the hydrogen partial pressure is... The partial pressure of oxygen is

[0071] Step S4 is as follows:

[0072] Real-time measurement of the catalyst active area of ​​each membrane electrode With respect to the initial catalyst active area of ​​the membrane electrode In contrast, when at least one membrane electrode has a catalyst active area The fuel cell then stops operating normally, indicating severe performance loss of the membrane electrode assembly (MEA), and enters fuel cell maintenance mode, replacing the corresponding MEA. When the catalyst active area of ​​all MEAs reaches its maximum value... This indicates that the membrane electrode assembly of the fuel cell is functioning normally. The online fault diagnosis mode for the active area of ​​the fuel cell catalyst is then turned off, and the fuel cell enters normal operation mode. After a fixed experimental cycle, steps S1-S4 are repeated.

[0073] The above-described online fault diagnosis method for fuel cell catalyst active area eliminates the need for complex and expensive experimental equipment or placing the fuel cell in a specific experimental environment. Using the existing single-cell voltage monitor (CVM) of the fuel cell, the catalyst active area of ​​each membrane electrode in the stack can be calculated simply and effectively based on a precise algorithm. The catalyst active area of ​​the membrane electrode can then be used to determine the catalyst activity loss of the fuel cell. This method also enables online detection of the catalyst active area, providing strong support for accurately locating the factors that cause fuel cell stack lifespan degradation.

[0074] 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; and these modifications or substitutions do 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 method for online fault diagnosis of active area of ​​fuel cell catalyst, characterized in that, Includes the following steps: S1. Select and execute the online fault diagnosis mode for the active area of ​​the fuel cell catalyst; S2. Monitor and record the individual voltage of each membrane electrode using a single-electrode voltage monitor (CVM). Where n represents the nth film electrode in the stack, and the value of n is {1, 2, 3, 4, 5, ...}; x represents the xth record, and the value of x is {1, 2, 3, 4, 5, ...}; S3. After recording the voltage of each individual membrane electrode in the fuel cell stack, calculate the catalyst active area of ​​each membrane electrode accordingly. Specifically as follows: The active surface area A of the catalyst is directly proportional to the exchange current density I, that is: A = k * I (1); In the formula, k is the corresponding coefficient; the corresponding coefficient k is related to the composition of the catalyst used in the fuel cell, and the corresponding coefficient k is obtained based on the initial exchange current density I0 and the initial electrochemical active area A0. The exchange current density I is calculated by the following formula: In the formula, R is the gas constant with a value of 8.314 J / mol / K; T is the stack operating temperature, measured by a temperature sensor placed at the stack coolant inlet; F is the Faraday constant with a value of 96485; i is the operating current density, obtained through measurement; V act To activate the loss voltage; When the operating current density is i, the activation loss voltage V act Calculated by the following formula: V act =V r -V i (3); In the formula, V r V represents the ideal potential of a fuel cell; i The operating voltage corresponding to the operating current density of i is monitored and recorded by a single-chip voltage monitor (CVM). Ideal potential V of fuel cell r Calculated by the following formula: In the formula, T is the operating temperature of the fuel cell stack, which is measured by a temperature sensor placed at the coolant inlet of the fuel cell stack; The partial pressure of hydrogen is calculated by measuring and using pressure and temperature / humidity sensors located at the anode inlet of the fuel cell stack. The oxygen partial pressure is calculated by measuring and then measuring the pressure sensor and temperature and humidity sensor located at the cathode inlet of the fuel cell stack. S4. Based on the calculated catalyst active area of ​​the membrane electrode. Determine if the fuel cell is malfunctioning due to catalyst activity loss.

2. The online fault diagnosis method for the active area of ​​a fuel cell catalyst as described in claim 1, characterized in that, hydrogen partial pressure The specific calculation method is as follows: The partial pressure of water at the anode inlet of the fuel cell stack is calculated using the temperature and humidity sensor readings. The total gas pressure of the gas entering the anode is measured using the pressure sensor at the anode inlet. The partial pressure of hydrogen is then obtained by subtracting the partial pressure of water at the anode inlet from the total gas pressure entering the anode. oxygen partial pressure The specific calculation method is as follows: The partial pressure of water at the cathode inlet of the fuel cell stack is calculated using the temperature and humidity sensor readings. The total gas pressure of the gas entering the cathode is measured using the pressure sensor at the cathode inlet. The partial pressure of water at the cathode inlet is subtracted from the total gas pressure entering the cathode. This difference is multiplied by the oxygen proportion coefficient of 0.21 to obtain the partial pressure of oxygen.

3. The online fault diagnosis method for the active area of ​​a fuel cell catalyst as described in claim 2, characterized in that, The specific method for calculating the corresponding coefficient k is as follows: For a brand new membrane electrode, the initial electrochemical active area A0 is obtained by consulting the membrane electrode parameter table; through normal load testing, the operating current density of the stack is set to i0 = 0.1 A / cm². 2 ; Record the stack operating temperature T0 and hydrogen partial pressure under the current initial operating conditions. oxygen partial pressure The ideal potential V of the fuel cell can be calculated using formula (4). r ; Simultaneously, the current voltage of each membrane electrode is monitored and recorded using a single-chip voltage monitor (CVM). Where n represents the nth film electrode in the stack, and the value of n is {1, 2, 3, 4, 5, ...}; the corresponding activation loss V is calculated according to formula (3). act ; Then, the initial exchange current density I0 is calculated according to formula (2); Substitute the initial exchange current density I0 and the initial electrochemical active area A0 into formula (1) to obtain the corresponding coefficient k.

4. The online fault diagnosis method for the active area of ​​a fuel cell catalyst as described in claim 3, characterized in that, In step S1, the fuel cell catalyst active area is in online fault diagnosis mode, i.e., the initial operating conditions are maintained, and the stack's operating current density is maintained at i0 = 0.1 A / cm². 2 The fuel cell stack operating temperature is T0, and the hydrogen partial pressure is... The partial pressure of oxygen is 5. The online fault diagnosis method for the active area of ​​a fuel cell catalyst as described in claim 4, characterized in that, Step S4 is as follows: Real-time measurement of the catalyst active area of ​​each membrane electrode With respect to the initial catalyst active area of ​​the membrane electrode In contrast, when at least one membrane electrode has a catalyst active area The fuel cell then stops operating normally, indicating severe performance loss of the membrane electrode assembly (MEA), and enters fuel cell maintenance mode, replacing the corresponding MEA. When the catalyst active area of ​​all MEAs reaches its maximum value... This indicates that the membrane electrode assembly of the fuel cell is functioning normally. The online fault diagnosis mode for the active area of ​​the fuel cell catalyst is then turned off, and the fuel cell enters normal operation mode. After a fixed experimental cycle, steps S1-S4 are repeated.

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