Fuel cell gas cavity and cooling liquid cavity blowby detection method
By using detection methods in fuel cell stacks, using the test bench and voltage inspection module CVM to obtain voltage data, combined with the nitrogen purge system, the leakage between the single-cell air chamber and the coolant chamber in the stack is accurately identified, which solves the problem of inaccurate identification of leakage in the existing technology, improves the replacement efficiency of the leakage bipolar plate, and extends the service life of the stack.
Patent Information
- Application Number
- CN202411685414.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-22
- Publication Date
- 2025-02-28
AI Technical Summary
The prior art cannot accurately identify whether there is leakage in the air cavity and coolant cavity of a single cell in a fuel cell stack, and it is impossible to accurately replace the leakage bipolar plate.
A detection method is adopted to connect hydrogen source, air source and coolant source through the test bench, and voltage data is obtained using the stack voltage patrol module CVM, combined with the nitrogen purge system, leakage tests are carried out between the coolant chamber and the air chamber, the coolant chamber and the hydrogen chamber, and the leakage area is quickly judged through the process capability index Cpk calculation.
It realizes accurate identification of leakage of single-cell air chambers and coolant chambers in fuel cell stacks, quickly locks leakage single-cells, improves the replacement efficiency of leakage bipolar plates, and extends the service life of the stack.
Smart Images
Figure CN119533817A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of fuel cells, and in particular to a method for detecting leakage of a fuel cell gas cavity and a cooling liquid cavity. Background Art
[0002] A fuel cell stack (hereinafter referred to as the "stack") is composed of multiple fuel cell cells connected in series. Each cell consists of a bipolar plate and a membrane electrode. The bipolar plate provides reaction gas and coolant, and the membrane electrode provides a place for the reaction to occur. If there is leakage between the hydrogen cavity, air cavity and coolant cavity of the bipolar plate, on the one hand, the coolant will enter the hydrogen cavity or air cavity, covering the active sites of the membrane electrode reaction, reducing performance and affecting the service life of the stack; on the other hand, the gas in the hydrogen cavity and air cavity enters the coolant cavity, which will cause uneven temperature distribution in the stack, forming local hot spots and affecting the service life of the stack. Therefore, during the production process of the stack, it is necessary to strictly control whether there is leakage between the air cavity and the coolant cavity.
[0003] In the prior art, after the stack is assembled and used, an air tightness test is generally performed to determine whether there is leakage between the two air cavities and the coolant cavity. However, it is not possible to accurately identify which single cell has leakage between the air cavity and the coolant cavity, and it is not possible to accurately replace the leaking bipolar plate. Therefore, a detection method is needed that can accurately identify whether a single cell in the stack has leakage between the air cavity and the coolant cavity, so as to accurately complete the replacement of the leaking bipolar plate. Summary of the invention
[0004] The problem to be solved by the present invention is to provide a detection method for accurately identifying leakage between two air cavities and a coolant cavity of a single cell in a battery stack.
[0005] In view of the deficiencies of the prior art, the technical solution adopted by the present invention to solve the technical problems is: a method for detecting leakage of the gas cavity and the cooling liquid cavity of a fuel cell, wherein the gas cavity of the battery includes a hydrogen cavity and an air cavity, the inlets and outlets of the hydrogen cavity, the air cavity and the cooling liquid cavity are all connected to a test bench, the test bench is provided with a hydrogen source, an air source, a cooling liquid source, a hydrogen exhaust port, an air exhaust port and a cooling liquid exhaust port, the test bench is provided with a fuel cell stack (hereinafter referred to as "the stack") battery voltage inspection module CVM, the stack battery voltage inspection module CVM is connected to the stack, the stack includes a single cell, and comprises the following steps,
[0006] Step 1: Use nitrogen to purge the hydrogen cavity, air cavity and coolant cavity before testing;
[0007] Step 2: Coolant cavity and air cavity leakage test, at this time, the test bench hydrogen source is connected to the stack coolant inlet, hydrogen is introduced into the test bench hydrogen source; the test bench air source is connected to the stack hydrogen inlet, air is introduced into the test bench air source, and the stack air inlet is not connected to the pipeline; the stack battery voltage inspection module CVM obtains the first group a voltage data;
[0008] Step 3: Between step 2 and step 4, use nitrogen to purge the hydrogen cavity, air cavity and coolant cavity to discharge all the residual gas in step 2;
[0009] Step 4: Coolant cavity and hydrogen cavity leakage test, at this time, the test bench hydrogen source is connected to the stack coolant inlet, hydrogen is introduced into the test bench hydrogen source; the test bench air source is connected to the stack air inlet, air is introduced into the test bench air source, and the stack hydrogen inlet is not connected to the pipeline; the stack battery voltage inspection module CVM obtains the second group a voltage data;
[0010] Step 5: After the test, use nitrogen to purge the hydrogen cavity, air cavity and coolant cavity.
[0011] Preferably, it is characterized in that: the nitrogen flow rate in step 1, step 3 and step 5 is 1nlpm / cell, the purge time is 10min and there is no pressure, and after the purge is completed, the voltage of each single cell in the data displayed by the battery voltage inspection module CVM is lower than 0.001V.
[0012] Preferably, in step 2, the hydrogen outlet of the fuel cell stack is connected to the air exhaust port of the test bench, the coolant outlet of the fuel cell stack is connected to the hydrogen exhaust port of the test bench, and the air outlet of the fuel cell stack is not connected to the pipeline; in step 4, the coolant outlet of the fuel cell stack is connected to the hydrogen exhaust port of the test bench, the air outlet of the fuel cell stack is connected to the air exhaust port of the test bench, and the hydrogen outlet of the fuel cell stack is not connected to the pipeline.
[0013] Preferably, the first group of a voltage data obtained in step 2 and the second group of a voltage data obtained in step 4 are respectively subjected to process capability index Cpk calculation, and the process capability index Cpk calculation process is as follows: a voltage data are equally divided into b groups according to the order of single cell numbers, each group has c data ("c" data is not less than 30), and each group of data is subjected to Cpk calculation to obtain b Cpk values, Cpk = min[(USL-μ) / 3σ, (μ-LSL) / 3σ], wherein USL represents the upper limit specification value of the leakage voltage, LSL represents the lower limit specification value of the leakage voltage, μ represents the average value of c leakage voltages, and σ represents the standard deviation of c leakage voltages; the group corresponding to Cpk ≥ 1.33 indicates that the leakage voltage of the group meets the requirements and there is no leakage; the group corresponding to Cpk < 1.33 indicates that the leakage voltage of the group does not meet the requirements and there is leakage, and the single cell in the group that exceeds the upper and lower limit voltage values of the leakage voltage is a problem single cell.
[0014] The beneficial effects of the present invention are as follows: the present invention uses a purge system to obtain voltage data between the air cavity and the cooling liquid cavity, and uses nitrogen for purging before self-detection to remove potential reaction gases. The obtained voltage data is used to calculate the process capability index Cpk, and the area where the leakage occurs is quickly determined based on the Cpk calculation. The leaking single cell number is determined within the leakage area based on the upper and lower limit voltage values of the leakage voltage, and the judgment of whether the single cell air cavity and the cooling liquid cavity are leaking is completed quickly. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 is a connection diagram of the test system of the present invention;
[0016] Figure 2 This is a test connection diagram of the cooling liquid chamber and the air chamber of the present invention;
[0017] Figure 3 This is a test connection diagram of the cooling liquid chamber and the hydrogen chamber of the present invention;
[0018] Figure 4 A test flow chart of the present invention;
[0019] Figure 5 Statistics for the embodiments of the present invention Figure 1 ;
[0020] Figure 6 Statistics for the embodiments of the present invention Figure 2 . DETAILED DESCRIPTION
[0021] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments of the present invention are provided for the purpose of illustration and description, and are not intended to be exhaustive or to limit the present invention to the disclosed forms. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present invention, and to enable those of ordinary skill in the art to understand the present invention and thereby design various embodiments with various modifications suitable for specific uses.
[0022] The testing method of the present invention utilizes the principle of converting chemical energy of hydrogen-oxygen reaction into electrical energy, combined with the existing CVM (electrical stack battery voltage inspection module), CVM can measure the real-time voltage value of each single cell in the electric stack, because the bipolar plate with leakage will have voltage changes, hydrogen with pressure is introduced into the cooling liquid cavity, and air with pressure is introduced into the hydrogen cavity or the air cavity. When the hydrogen in the cooling liquid cavity leaks into the hydrogen cavity or the air cavity through the bipolar plate, a hydrogen-oxygen reaction will occur, and the corresponding bipolar plate will detect the voltage value. The battery air cavity includes a hydrogen cavity and an air cavity, and the entrances and exits of the hydrogen cavity, the air cavity and the cooling liquid cavity are all connected to the test bench. The test bench is provided with a hydrogen source, an air source, a cooling liquid source, a hydrogen exhaust port, an air exhaust port and a cooling liquid exhaust port. The test bench is provided with an electric stack battery voltage inspection module CVM, and the electric stack battery voltage inspection module CVM is connected to the electric stack, and the electric stack includes a single cell. The specific method of detection is as follows:
[0023] Test step 1: Use nitrogen to purge the hydrogen cavity, air cavity and coolant cavity before testing; Before testing, it is necessary to purge all liquids in the channels (hydrogen cavity, air cavity, coolant cavity) to keep the stack dry and free of hydrogen in all cavities. Use nitrogen for purging, with a nitrogen flow rate of 1nlpm / cell and no pressure. For nitrogen purging pipe connections, refer to Figure 1 At this time, the hydrogen source, air source, and coolant source all provide nitrogen. The recommended nitrogen purge time is 10 minutes. All purge conditions are only recommended values. The actual values can be adjusted according to the actual test conditions. Dry the hydrogen cavity, air cavity, and coolant cavity of the fuel cell stack. The CVM (battery voltage inspection module) is well connected and can record and store all CVM data. After step one is completed, the CVM data are all within the upper and lower limits of the leakage voltage. The upper and lower limits of the leakage voltage include USL and LSL. USL represents the upper limit specification value of the leakage voltage, and LSL represents the lower limit specification value of the leakage voltage.
[0024]
[0025]
[0026] Test step 2: Coolant cavity and air cavity leakage test
[0027] according to Figure 2The pipelines are connected. At this time, the test bench hydrogen source is connected to the stack coolant inlet, and hydrogen is introduced into the test bench hydrogen source; the test bench air source is connected to the stack hydrogen inlet, and air is introduced into the test bench air source. The stack air inlet is not connected to the pipeline. After the pipeline connection is completed, hydrogen is introduced into the test bench hydrogen source. The hydrogen pressure is 100kPag and the flow rate is 1nlpm / cell. The test bench air source introduces air. The air pressure is 100kPag and the flow rate is 1nlpm / cell. The duration is recommended to be 5min. All test conditions are only recommended values, and the actual values can be adjusted according to the actual test conditions. The stack battery voltage inspection module CVM obtains the first group a voltage data.
[0028]
[0029] The process capability index Cpk is calculated for the first group a of voltage data obtained above. The calculation process of the process capability index Cpk is as follows: the a voltage data are equally divided into b groups according to the order of the single cell numbers. There are c data in each group (the number of "c" data is not less than 30). Cpk is calculated for each group of data to obtain b Cpk values, Cpk = min[(USL-μ) / 3σ, (μ-LSL) / 3σ], where USL represents the upper specification value of the leakage voltage, LSL represents the lower specification value of the leakage voltage, μ represents the average value of c leakage voltages, and σ represents the standard deviation of c leakage voltages; whether the leakage voltage within the group meets the requirements is determined based on the calculation result of the process capability index Cpk; the group corresponding to Cpk ≥ 1.33 indicates that the leakage voltage of the group meets the requirements and there is no leakage; the group corresponding to Cpk < 1.33 indicates that the leakage voltage of the group does not meet the requirements and there is leakage, and the single cell in the group that exceeds the upper and lower limit voltage values of the leakage voltage is a problem single cell.
[0030] Test step three: nitrogen is used to purge the hydrogen chamber, air chamber and coolant chamber during the test; the process is the same as step one, and all the residual gas in step two is discharged. After step three is completed, the CVM data are within the upper and lower limits of the leakage voltage.
[0031] Test step 4: Coolant chamber and hydrogen chamber leakage test;
[0032] according to Figure 3The pipelines are connected. At this time, the test bench hydrogen source is connected to the stack coolant inlet, and hydrogen is introduced into the test bench hydrogen source; the test bench air source is connected to the stack air inlet, and air is introduced into the test bench air source. The stack hydrogen inlet is not connected to the pipeline. After the pipeline connection is completed, the test bench hydrogen source is introduced with a pressure of 100kPag and a flow rate of 1nlpm / cell of hydrogen, and the test bench air source is introduced with a pressure of 100kPag and a flow rate of 1nlpm / cell of air. The duration is recommended to be 5 minutes. All test conditions are only recommended values, and the actual values can be adjusted according to the actual test conditions. The stack battery voltage inspection module CVM obtains the second group a of voltage data.
[0033]
[0034] The second group a of voltage data obtained above are respectively calculated for process capability index Cpk. The process of calculating process capability index Cpk is as follows: a voltage data are equally divided into b groups according to the order of single cell numbers. There are c data in each group. Each group of data is respectively calculated for Cpk to obtain b Cpk values, Cpk = min[(USL-μ) / 3σ, (μ-LSL) / 3σ], where USL represents the upper specification value of the leakage voltage, LSL represents the lower specification value of the leakage voltage, μ represents the average value of c leakage voltages, and σ represents the standard deviation of c leakage voltages; according to the calculation result of process capability index Cpk, it is determined whether the leakage voltage within the group meets the requirements; the group corresponding to Cpk ≥ 1.33 indicates that the leakage voltage of the group meets the requirements and there is no leakage; the group corresponding to Cpk < 1.33 indicates that the leakage voltage of the group does not meet the requirements and there is leakage. The single cell in the group that exceeds the upper and lower limit voltage values of the leakage voltage is the problem cell. The stack detection is quickly completed by locking the group first and then locking the single leaking battery.
[0035] Test step five: Purge after the test. Use nitrogen to purge the hydrogen cavity, air cavity and coolant cavity after the test.
[0036] After the test is completed, press Figure 1 The pipelines are connected in the connection mode and the stack is purged. Nitrogen is used for purging. At this time, the hydrogen source, air source, and coolant source all provide nitrogen. The flow rate is 1nlpm / cell, there is no pressure, and the recommended purge time is 5 minutes. All purge conditions are only recommended values. The actual values can be adjusted according to the actual test situation. Purging is considered completed when the single cell voltage is less than 0.001V.
[0037] Stack hydrogen inlet Stack air inlet Stack coolant inlet Gas Type Nitrogen Nitrogen Nitrogen Flow rate nlpm / cell 1 1 1 Pressure kPag 0 0 0 Time min 5 5 5
[0038] Example
[0039] According to the above steps, a fuel cell stack with 150 cells was tested for leakage in the air cavity and coolant cavity on the fuel cell test bench. Figure 5 The figure shows the leakage test results of the coolant chamber and hydrogen chamber of the stack. The average value of the data of the last 10s of CVM is taken as the leakage voltage of each cell, in V. Based on the test statistics of the stack, the upper and lower limits of the leakage voltage are ±0.002V. USL represents the upper limit specification value of the leakage voltage, in this case USL=0.002V; LSL represents the lower limit specification value of the leakage voltage, in this case LSL=-0.002V. The 150 cells are divided into groups of 30, that is, c=30, b=5. In the calculation of the general process capability index Cpk, c≥30, μ represents the average value of the 30 leakage voltages, and σ represents the standard deviation of the 30 leakage voltages. Take the first group of 150 voltage data as an example:
[0040] Process capability index Cpk calculation formula:
[0041] Cpk=min[(USL-μ) / 3σ,(μ-LSL) / 3σ]
[0042] Calculation results: 1-30 pieces Cpk = 0.051, 31-60 pieces Cpk = 1.394, 61-90 pieces Cpk = 1.352, 91-120 pieces Cpk = 1.495, 121-150 pieces Cpk = 2.213. The calculation results show that 1-30 pieces Cpk = 0.051 < 1.33, which does not meet the requirements; the voltage of the 27th cell is greater than USL, so the 27th cell is a leaking cell in the hydrogen cavity and the coolant cavity.
[0043] like Figure 6 The following are the leakage test results of the coolant chamber and air chamber of the stack, divided into groups and Figure 5 Similarly, USL = 0.002V; LSL = -0.002V; bring each group voltage data into the process capability index Cpk calculation formula:
[0044] Cpk=min[(USL-μ) / 3σ,(μ-LSL) / 3σ]
[0045] Calculation results: 1-30 pieces Cpk = 0.082, 31-60 pieces Cpk = 1.423, 61-90 pieces Cpk = 0.012, 91-120 pieces Cpk = 1.696, 121-150 pieces Cpk = 1.334; From the calculation results, it can be seen that 1-30 pieces Cpk = 0.082 < 1.33, 61-90 pieces Cpk = 0.012 < 1.33, which does not meet the requirements; Among them, the voltage of the 8th and 78th batteries is less than LSL, so the 8th and 78th cells are leaking single cells in the air cavity and the coolant cavity.
[0046] The following is the calculation process of the leakage test results of the stack coolant chamber and hydrogen chamber:
[0047]
[0048]
[0049]
[0050] The following is the calculation process of the stack coolant chamber and air chamber leakage test results:
[0051]
[0052]
[0053]
Claims
1. A method for detecting leakage of a fuel cell gas cavity and a coolant cavity, wherein the gas cavity of the battery comprises a hydrogen cavity and an air cavity, the inlets and outlets of the hydrogen cavity, the air cavity and the coolant cavity are all connected to a test bench, the test bench is provided with a hydrogen source, an air source, a coolant source, a hydrogen exhaust port, an air exhaust port and a coolant exhaust port, the test bench is provided with a fuel cell stack (hereinafter referred to as "the stack") battery voltage inspection module CVM, the stack battery voltage inspection module CVM is connected to the stack, the stack comprises a single cell, and is characterized in that: The following steps are included: Step 1: Use nitrogen to purge the hydrogen cavity, air cavity and coolant cavity before testing; Step 2: Coolant cavity and air cavity leakage test, at this time, the test bench hydrogen source is connected to the stack coolant inlet, hydrogen is introduced into the test bench hydrogen source; the test bench air source is connected to the stack hydrogen inlet, air is introduced into the test bench air source, and the stack air inlet is not connected to the pipeline; the stack battery voltage inspection module CVM obtains the first group a voltage data; Step 3: Between step 2 and step 4, use nitrogen to purge the hydrogen cavity, air cavity and coolant cavity to discharge all the residual gas in step 2; Step 4: Coolant cavity and hydrogen cavity leakage test, at this time, the test bench hydrogen source is connected to the stack coolant inlet, hydrogen is introduced into the test bench hydrogen source; the test bench air source is connected to the stack air inlet, air is introduced into the test bench air source, and the stack hydrogen inlet is not connected to the pipeline; the stack battery voltage inspection module CVM obtains the second group a voltage data; Step 5: After the test, use nitrogen to purge the hydrogen cavity, air cavity and coolant cavity.
2. The method for detecting leakage of the fuel cell gas cavity and the cooling liquid cavity according to claim 1, characterized in that: The nitrogen flow rate in step 1, step 3 and step 5 is 1nlpm / cell, the purge time is 10min and there is no pressure. After the purge is completed, the voltage of each single cell in the data displayed by the battery voltage inspection module CVM is lower than 0.001V.
3. The method for detecting leakage of the fuel cell gas cavity and cooling liquid cavity as claimed in claim 2, characterized in that: In step 2, the hydrogen outlet of the fuel cell stack is connected to the exhaust air outlet of the test bench, the coolant outlet of the fuel cell stack is connected to the hydrogen exhaust port of the test bench, and the air outlet of the fuel cell stack is not connected to the pipeline; in step 4, the coolant outlet of the fuel cell stack is connected to the hydrogen exhaust port of the test bench, the air outlet of the fuel cell stack is connected to the exhaust air outlet of the test bench, and the hydrogen outlet of the fuel cell stack is not connected to the pipeline.
4. The method for detecting leakage of the fuel cell gas cavity and the cooling liquid cavity according to claim 1, characterized in that: The process capability index Cpk is calculated for the first group a voltage data obtained in step 2 and the second group a voltage data obtained in step 4 respectively. The process capability index Cpk calculation process is as follows: the a voltage data are equally divided into b groups according to the order of the single cell number, and there are c data in each group (the "c" data is not less than 30). The Cpk is calculated for each group of data to obtain b Cpk values, Cpk = min[(USL-μ) / 3σ, (μ-LSL) / 3σ], where USL represents the upper limit specification value of the leakage voltage, LSL represents the lower limit specification value of the leakage voltage, μ represents the average value of the c leakage voltages, and σ represents the standard deviation of the c leakage voltages; the group corresponding to Cpk ≥ 1.33 indicates that the leakage voltage of the group meets the requirements and there is no leakage; the group corresponding to Cpk < 1.33 indicates that the leakage voltage of the group does not meet the requirements and there is leakage. The single cell in the group that exceeds the upper and lower limit voltage values of the leakage voltage is a problem single cell.