Fuel cell double stack consistency evaluation method

Abstract

The present application relates to a kind of fuel cell double stack consistency evaluation method, comprising: the single cell of dense screening qualified, after activation according to standard procedure, assemble to fuel cell double stack;Measure the voltage signal of single section battery under rated current;According to the adjustment amplitude set, adjust the gas admission metering ratio of fuel gas / oxidation gas;Again measure the voltage signal of single section battery under rated current;Group processing is carried out to two voltage signals, and the average voltage of upper and lower stack, single body voltage fluctuation rate and single body voltage change rate are output, wherein, the average voltage of upper and lower stack corresponds to the consistency evaluation result of upper and lower stack, single body voltage fluctuation rate corresponds to the consistency evaluation result of single cell, and single body voltage change rate corresponds to the consistency evaluation result of fluid distribution.Compared with prior art, the present application can comprehensively and systematically evaluate the consistency of fuel cell double stack, data processing is simple, result is more intuitive, can provide reference and data support for stack structure design and optimization.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a method for evaluating the consistency of dual-stack fuel cells. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) are energy conversion devices that directly convert the chemical energy of fuel into electrical energy. They offer advantages such as high energy conversion efficiency, fast response speed, and environmental friendliness, and are currently widely used in transportation, stationary power plants, aerospace, and other fields. Dual fuel cell stacks, composed of two single stacks, can provide greater power to meet the needs of specialized applications. To ensure the efficient and reliable operation of dual fuel cell stacks, it is often necessary to evaluate the consistency of the fuel cell stacks.

[0003] The consistency of a fuel cell stack mainly includes: 1) consistency of individual cell performance, and 2) consistency of fluid distribution. Inappropriate structural design, differences in electrode plates, or stack assembly errors can cause varying resistance drops in the flow field, leading to inconsistent fluid distribution. Material differences and molding processes can cause inconsistencies in individual cells. Stack consistency is crucial for the overall performance of the fuel cell stack; inconsistencies will affect the stability, reliability, and durability of the stack. The voltage of each cell in a fuel cell stack varies to varying degrees and should be kept as consistent as possible. Excessive voltage fluctuations in individual cells can lead to excessively high local current densities, easily causing hot spots or even reverse polarity, resulting in stack failure. Therefore, providing a complete and comprehensive method for evaluating the consistency of dual stacks is of great significance.

[0004] Currently, the commonly used evaluation methods for fuel cell consistency are: single cell volatility, root mean square value of single cell voltage change, amplitude of single cell voltage change, and graphical method. Among these, single cell volatility is the most widely used, while the graphical method can intuitively and vividly reflect the consistency of single cells in the fuel cell stack.

[0005] For example, Chinese patent CN105789660A describes a method for determining the consistency of fluid distribution in a proton exchange membrane fuel cell stack by introducing a mixture of hydrogen and inert gas into the anode or cathode inlet of the stack and applying the same voltage for hydrogen oxidation between the electrodes of each cell. The consistency of the oxidation current in each cell is then tested and compared to determine the uniformity of fluid distribution in the stack. However, this method has the following drawbacks: the testing process is cumbersome, and it cannot guarantee the consistency of operating conditions for each cell within the stack.

[0006] Chinese patent CN114512695A proposes a method for calculating the overall consistency of a fuel cell stack. This method estimates the manufacturing consistency variation of the membrane electrode by calculating the mean square deviation of the voltage within each voltage group, and finally calculates the consistency caused by the stack design structure based on the calculated manufacturing consistency variation. However, the aforementioned single-cell volatility only reflects the consistency of the entire stack and cannot determine whether the voltage difference is caused by inconsistent single-cell performance or inconsistent flow distribution. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a method for evaluating the consistency of dual fuel cell stacks. This method can provide a simple and intuitive systemic evaluation of dual fuel cell stacks and avoid the adverse effects of individual cell performance differences on the evaluation results.

[0008] The objective of this invention can be achieved through the following technical solution: a method for evaluating the conformity of dual-stack fuel cells, comprising the following steps:

[0009] S1. After the qualified single cells are activated according to the standard procedure, they are assembled into the fuel cell stack.

[0010] S2. Measure the voltage signal of a single battery cell under rated current;

[0011] S3. Adjust the fuel gas / oxidizing gas intake metering ratio according to the set adjustment range;

[0012] S4. Measure the voltage signal of a single cell at the rated current again;

[0013] S5. The voltage signal data obtained in steps S2 and S4 are grouped and processed to output the average voltage of the upper and lower stacks, the voltage fluctuation rate of a single cell, and the voltage change rate of a single cell. The average voltage of the upper and lower stacks corresponds to the consistency evaluation result of the upper and lower stacks, the voltage fluctuation rate of a single cell corresponds to the consistency evaluation result of a single cell, and the voltage change rate of a single cell corresponds to the consistency evaluation result of fluid distribution.

[0014] Furthermore, the rated current in steps S2 and S4 is specifically 200 to 800 A.

[0015] Furthermore, steps S2 and S4 specifically involve measuring and acquiring voltage signals through a test inspection method.

[0016] Furthermore, the adjustment range in step S3 is specifically 1% to 5%.

[0017] Furthermore, step S5 specifically includes the following steps:

[0018] S51. The voltage signal data obtained in steps S2 and S4 are grouped and processed.

[0019] S52. Calculate the average voltage V of the upper stack, the lower stack, and the entire stack. Ave-U V Ave-D and V Ave ;

[0020] S53. Calculate the mean square ripple rate C of the voltage of the upper and lower stacks and the entire stack. V-U C V-D and C V ;

[0021] S54. Calculate the rate of change of single-cell voltage. And record the cell number i of the single cell whose volatility is greater than the preset threshold;

[0022] S55, V under different gas volume ratios Ave-U V Ave-D The value is used to evaluate the consistency between the upper and lower heaps;

[0023] C under different gas volume ratios V-U C V-D C V The value is used to evaluate the consistency of the individual cells in the entire stack;

[0024] The consistency of gas distribution is evaluated by the dispersion of single cell numbers whose single cell volatility exceeds a preset threshold under different gas volume ratios.

[0025] Furthermore, the average voltage of the upper and lower stacks in step S52 is specifically as follows:

[0026]

[0027] Among them, V Ave-U V is the average voltage of the upper pile. i-U This represents the voltage information of the i-th section of the stack, where n is the number of stack sections; V Ave-D Similarly, Vi - D represents the voltage information of the i-th section of the lower stack.

[0028] Furthermore, the formula for calculating the mean square volatility in step S53 is as follows:

[0029]

[0030]

[0031] Among them, C v-U C represents the mean square voltage fluctuation of a single chip in the stack. v-D Similarly, C is calculated. V This represents the mean square voltage fluctuation rate of the entire stack.

[0032] Furthermore, the rate of change of the single-cell voltage in step S54 is specifically as follows:

[0033]

[0034] in, Let V be the rate of change of single-cell voltage, and Vi and Vi' be the voltages of the i-th single cell before and after the change of the intake metering ratio, respectively. mean The average voltage of all individual cells before and after changing the intake metering ratio.

[0035] Furthermore, the preset threshold in step S54 is specifically 5%.

[0036] Furthermore, in step S55, if the average single-plate voltage V of the upper and lower stacks is changed before and after the intake metering ratio is changed... Ave-U and V Ave-D If the difference is less than or equal to the first set difference value, it indicates that the consistency between the upper and lower stacks is good;

[0037] If the intake metering ratio is changed, the mean square fluctuation rate C of the voltage of the upper and lower stacks and the entire stack will change. V-U and C V-D C V If the difference is less than or equal to the second set difference value, it indicates that the consistency of the single chip is good;

[0038] If, before and after changing the intake metering ratio, there is no continuity in the cell numbers whose single-cell fluctuation rate exceeds the preset threshold, it indicates that the gas distribution consistency is good.

[0039] Compared with existing technologies, this invention adjusts the fuel gas / oxidant gas inlet metering ratio and obtains the voltage signal of a single cell at rated current through two measurements. By grouping and processing the two voltage signals, the average voltage of the upper and lower stacks, the mean square fluctuation rate of the voltage of the upper and lower stacks and the entire stack, and the rate of change of the single cell are calculated. This enables the evaluation of the consistency of the upper and lower stacks, the consistency of the single cells, and the consistency of fluid distribution. The operation process of this invention is simple and reliable, enabling a systematic and comprehensive evaluation of dual fuel cell stacks. It avoids the adverse effects of individual cell performance differences on the consistency evaluation of the entire stack, and the evaluation results are simple and intuitive. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the method flow of the present invention;

[0041] Figure 2 This is a schematic diagram illustrating the application process of the present invention. Detailed Implementation

[0042] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0043] like Figure 1 As shown, a method for evaluating the conformity of dual-stack fuel cells includes the following steps:

[0044] S1. After the qualified single cells are activated according to the standard procedure, they are assembled into the fuel cell stack.

[0045] S2. Measure the voltage signal of a single battery cell under rated current;

[0046] S3. Adjust the fuel gas / oxidizing gas intake metering ratio according to the set adjustment range;

[0047] S4. Measure the voltage signal of a single cell at the rated current again;

[0048] S5. The voltage signal data obtained in steps S2 and S4 are grouped and processed to output the average voltage of the upper and lower stacks, the voltage fluctuation rate of a single cell, and the voltage change rate of a single cell. The average voltage of the upper and lower stacks corresponds to the consistency evaluation result of the upper and lower stacks, the voltage fluctuation rate of a single cell corresponds to the consistency evaluation result of a single cell, and the voltage change rate of a single cell corresponds to the consistency evaluation result of fluid distribution.

[0049] The above technical solution is applied in practice, and the specific application process is as follows: Figure 2 As shown, it mainly includes:

[0050] Step 1: After the qualified single cells are activated according to the standard procedure, they are assembled into the fuel cell stack.

[0051] Step 2: Obtain the voltage signal of a single battery cell at the rated current;

[0052] Step 3: Fine-tune the fuel gas / oxidizer intake metering ratio;

[0053] Step 4: Obtain the voltage signal of a single battery cell at the rated current again;

[0054] Step 5: Group the voltage signals acquired in the two transactions;

[0055] Step 6: Calculate the average voltage V of the upper and lower stacks and the entire stack. Ave-U V Ave-D and V Ave ;

[0056] Step 7: Calculate the mean square ripple rate C of the voltage between the upper and lower stacks and the entire stack. V-U C V-D and C V ;

[0057] Step 8: Calculate the rate of change of a single cell Record the cell number i of the single cell with volatility > 5%;

[0058] Step 9: V under different gas volume ratios Ave-U V Ave-D The value of C is used to evaluate the consistency between the upper and lower stacks; the C value is used to evaluate the consistency between the upper and lower stacks under different gas ratios. V-U and C V-D C V The value is used to evaluate the consistency of the individual cells in the entire stack; the consistency of gas distribution is evaluated by the discreteness of the cell numbers with large fluctuations under different gas flow ratios.

[0059] In step 2, the operating current is between 200 and 800A;

[0060] In steps 2 and 4, the voltage signals are obtained through testing and inspection.

[0061] In step 3, the intake metering ratio is fine-tuned by 1-5%.

[0062] Furthermore, the formula for calculating the average voltage of the upper and lower stacks in step 6 is as follows:

[0063]

[0064] In the formula, V Ave-U V is the average voltage of the upper pile. i-U This represents the voltage information of the i-th section of the stack, where n is the number of stack sections; V Ave-D Similarly, Vi - D represents the voltage information of the i-th section of the lower stack;

[0065] The formula for calculating the mean square volatility in step 7 is:

[0066]

[0067]

[0068] In the formula, C v-U C represents the mean square voltage fluctuation of a single chip in the stack. v-D Similarly, C is calculated. V The mean square voltage fluctuation of the entire stack;

[0069] The formula for calculating the rate of change of a single cell in step 8 is:

[0070]

[0071] in Let V be the rate of change of single-cell voltage, and Vi and Vi' be the voltages of the i-th single cell before and after the change of the intake metering ratio, respectively. mean To change the average voltage of all individual cells before and after the intake metering ratio, the rate of change was recorded. More than 5% of the single cell numbers.

[0072] If the intake metering ratio is changed before and after, the average single-plate voltage V of the upper and lower stacks is... Ave-U and V Ave-D Small differences indicate good consistency between the upper and lower stacks; if the intake metering ratio is changed, the mean square fluctuation rate C of the voltage of the upper and lower stacks and the entire stack will change. V-U and C V-D C V Small differences indicate good consistency of individual cells; if the cell numbers with large changes in the rate of change of the intake metering ratio are not continuous before and after the change, it indicates good consistency of gas distribution.

[0073] Example 1

[0074] This embodiment applies the above technical solution, setting the fine-tuning intake metering ratio to 2%. The main process is as follows:

[0075] Step 1: After the qualified single cells are activated according to the standard procedure, they are assembled into the fuel cell stack.

[0076] Step 2: Obtain the voltage signal of a single battery cell at the rated current;

[0077] Step 3: Fine-tune the fuel gas / oxidizer intake metering ratio by 2%;

[0078] Step 4: Obtain the voltage signal of a single battery cell at the rated current again;

[0079] Step 5: Group the voltage signals acquired in the two transactions;

[0080] Step 6: Calculate the average voltage V between the upper and lower stacks. Ave-U V Ave-D ;

[0081] Step 7: Calculate the mean square ripple rate C of the voltage between the upper and lower stacks and the entire stack. V-U C V-D C V ;

[0082] Step 8: Calculate the rate of change of a single cell And record the cell number i of the single cell with volatility > 5%;

[0083] Step 9: V under different gas volume ratios Ave-U V Ave-D The value of C is used to evaluate the consistency between the upper and lower stacks; the C value is used to evaluate the consistency between the upper and lower stacks under different gas ratios. V-U C V-D C V The value is used to evaluate the consistency of the individual cells in the entire stack; the consistency of gas distribution is judged by the discreteness of the cell numbers with large fluctuations under different gas flow ratios.

[0084] Example 2

[0085] The main process of this embodiment is the same as that of Embodiment 1, except that the intake humidity is adjusted to 50%.

[0086] Example 3

[0087] The main process of this embodiment is the same as that of Embodiment 1, except that the fuel gas is adjusted to be an H2 / Ar mixture with an H2 content of 50%.

[0088] In summary, this technical solution evaluates the consistency of the upper and lower stacks by grouping the individual cell voltage signals under rated current, assesses the consistency of individual cells by the difference in average individual cell voltage between the upper and lower stacks, evaluates the consistency of individual cells by the difference in the mean square fluctuation rate of voltage between the upper and lower stacks and the entire stack, and evaluates the consistency of gas distribution by the continuity of cell numbers with large rate of change in individual cells. Compared with existing technologies, this invention can more comprehensively evaluate the consistency of dual fuel cell stacks, with simpler data processing and more intuitive results, providing reference and data support for stack structure design and optimization.

Claims

1. A method for evaluating consistency of a fuel cell double stack, characterized by, The method comprises the following steps: S1, after screening qualified single cells, assembling the single cells into a fuel cell double stack after activation according to a standard process; S2, measuring a voltage signal of the single cell under a rated current; S3, adjusting a fuel gas / oxidizing gas intake metering ratio according to a set adjustment range; S4, measuring the voltage signal of the single cell under the rated current again; S5, grouping the two voltage signal data obtained in steps S2 and S4, and outputting average voltages of the upper and lower stacks, a single cell voltage fluctuation rate, and a single cell voltage change rate, wherein the average voltages of the upper and lower stacks correspond to an upper and lower stack consistency evaluation result, the single cell voltage fluctuation rate corresponds to a single cell consistency evaluation result, and the single cell voltage change rate corresponds to a fluid distribution consistency evaluation result; Step S5 specifically comprises the following steps: S51, grouping the two voltage signal data obtained in steps S2 and S4; S52, calculate the average voltage V of the upper, lower and whole stacks Ave-U , V Ave-D and V Ave ; S53, calculate the mean square fluctuation rate C of the upper and lower stack voltages and the whole stack voltage V-U , C V-D and C V ; S54, calculate the rate of change of the single cell voltage and record the single cell sheet number i with the fluctuation rate greater than the preset threshold value S55, evaluate the consistency of the upper and lower stacks by the value of V Ave-U , V Ave-D under different air volume ratios; The consistency of the whole stack of single cells was evaluated by the values of C V-U , C V-D , C V under different gas volume ratios. The consistency of the gas distribution is evaluated by the discreteness of the single cell sheet numbers of the single cells with a fluctuation rate greater than a preset threshold under different gas quantity ratios; The average voltages of the upper and lower stacks in step S52 are specifically as follows: , wherein, V is the average voltage of the upper stack, i-U V is the voltage information of the i-th section of the upper stack, and n is the number of sections of the stack; The calculation of V is the same, i-D V is the voltage information of the i-th section of the lower stack. The calculation formula of the mean square fluctuation rate in step S53 is as follows: , , Wherein, C V-U is the single piece voltage mean square fluctuation rate of the upper stack, C V-D is calculated in the same way, is the voltage mean square fluctuation rate of the whole stack; The rate of change of the single cell voltage in step S54 is specifically: , wherein, is the rate of change of the voltage of the single cell, and are the voltages of the ith section single cell before and after changing the intake air metering ratio, respectively, is the average voltage of all single cells before and after changing the intake air metering ratio.

2. The method for evaluating the consistency of a fuel cell double stack according to claim 1, wherein The rated current in steps S2 and S4 is specifically 200-800 A.

3. The method of claim 1, wherein the method is characterized by: Steps S2 and S4 are specifically for measuring and obtaining the voltage signal by means of test inspection.

4. The method of claim 1, wherein the method is characterized by: The adjustment range in step S3 is specifically 1%-5%.

5. The method of claim 1, wherein the method is characterized by: The preset threshold in step S54 is specifically 5%.

6. The method of claim 1, wherein the method is a method for evaluating consistency of a fuel cell double stack, characterized by In the step S55, if the average single sheet voltage V of the upper and lower stacks before and after the change of the intake metering ratio is less than or equal to a first set difference, it indicates that the upper and lower stacks are consistent. Ave-U and V Ave-D the difference is less than or equal to a first set difference, it indicates that the upper and lower stacks are consistent. If the intake metering ratio is changed, the mean square fluctuation rate C of the voltage of the upper and lower stacks and the entire stack will change. V-U and C V-D C V If the difference is less than or equal to the second set difference value, it indicates that the consistency of the single chip is good; If there is no continuity in the single cell sheet numbers of the single cells with a fluctuation rate greater than a preset threshold before and after changing the intake metering ratio, it indicates that the gas distribution consistency is good.

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