A fuel cell stack air tightness rapid detection system and method

Abstract

The present application relates to a kind of fuel cell stack air tightness detection system and method, the system includes: anode pipeline, with the anode cavity of fuel cell stack to be measured connection, including anode pipeline gas inlet, anode pipeline exhaust and anode pipeline flow pressure control;Cathode pipeline, with the cathode cavity of fuel cell stack to be measured connection, including cooling pipeline gas inlet, cooling pipeline exhaust and cooling pipeline flow pressure control;Cooling pipeline, with the cooling cavity of fuel cell stack to be measured connection, including cathode pipeline gas inlet, cathode pipeline exhaust and cathode pipeline flow pressure control;Gas source, including the gas source of multiple different kinds of gas, different kind of gas source is connected with each pipeline respectively;CVM inspection, with the each polar plate of fuel cell connection, for testing single cell voltage in stack.The present application can select different test gas according to need, and more accurately judge leakage point in combination with pressure variation and CVM inspection data, shorten the production cycle of product and repair cost.

Description

Technical Field

[0001] This invention relates to the field of fuel cell stack testing technology, and in particular to a rapid testing system and method for the airtightness of fuel cell stacks. Background Technology

[0002] The airtightness of a fuel cell stack is crucial to its performance and reliability, and has become a key indicator for evaluating the long-term stable operation of a fuel cell. A fuel cell stack is formed by stacking several individual cells, containing three independent fluid flow chambers: the cathode, anode, and cooling chamber. Airtightness failures are mainly caused by external leakage due to encapsulation failure and internal leakage within the three chambers due to CCM (cathode, anode, and cooling chamber) damage. External leakage refers to the leakage of the oxidation gas chamber, fuel gas chamber, and cooling chamber within the stack to the atmosphere. Internal leakage refers to leakage between the oxidation gas chamber, fuel gas chamber, and cooling chamber within the stack. However, current fuel cell stack airtightness testing procedures are complex, cumbersome, and have poor detection accuracy, making it impossible to pinpoint the location of the failure. Commonly used airtightness testing systems on the market include single-cell bipolar plate testing stations and whole-stack external leakage testing stations. Single-cell bipolar plate airtightness testing systems have a large market share, but they cannot detect plate damage or seal failure that occurs during the stacking process; while stack airtightness testing stations test external leakage within the chambers based on the pressure holding method, which cannot locate the failed individual cells.

[0003] Chinese invention patent application number CN202211509309.4, entitled "A Leak Detection and Diagnostic System and Control Method for Fuel Cell Stacks," is a diagnostic system for detecting leaks in fuel cell stacks. This invention includes a tailpipe liquid water collection function and also possesses gas, pressure, and flow control functions. It provides pressure and flow for detecting cross-leakage between the three chambers and enables rapid factory diagnostics of the stack through single-cell voltage detection. However, this technology has limitations in terms of the single inlet gas species, which cannot meet a wider range of testing needs, and it also consumes a significant amount of hydrogen during testing.

[0004] Chinese invention patent application CN202211440088.X, entitled "A Method and Apparatus for Detecting the Airtightness of a Fuel Cell Stack," utilizes a flexible inflatable airbag to prevent gas flow, thereby accurately locating leak points in the fuel cell stack. This allows for precise identification of bipolar plates with cross-leakage within the stack, improving detection efficiency. The flexible inflatable airbag used in the detection process effectively isolates the gas without damaging the internal structure of the stack. The method is simple in principle, easy to implement, and effectively reduces detection costs. However, this technology requires changing the position and size of the airbag for each test, resulting in low detection efficiency and unsuitability for batch testing.

[0005] The existing patented airtightness detection schemes are inflexible and cannot achieve high-precision and rapid diagnosis of leak locations. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects of the prior art by providing a leak detection and diagnosis system and control method for fuel cell stacks.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] As a first aspect of the present invention, a fuel cell stack airtightness testing system is provided for testing fuel cell stacks, the system comprising:

[0009] The anode line is connected to the anode cavity of the fuel cell stack under test, and includes anode line air intake, anode line exhaust, and anode line flow and pressure control;

[0010] The cathode pipeline is connected to the cathode cavity of the fuel cell stack under test, and includes cooling pipeline air inlet, cooling pipeline exhaust and cooling pipeline flow and pressure control;

[0011] The cooling pipeline is connected to the cooling chamber of the fuel cell stack under test, and includes cathode pipeline air inlet, cathode pipeline exhaust and cathode pipeline flow and pressure control;

[0012] The gas source includes multiple gas sources of different types, which are respectively connected to the anode pipeline, cathode pipeline and cooling pipeline to provide test gases of different gas components.

[0013] CVM (Continuous Monitoring Machine) is connected to each electrode plate of the fuel cell and is used to test the voltage of individual cells in the stack.

[0014] Furthermore, the gas source includes one or more of the following: hydrogen, air, oxygen, nitrogen, and helium.

[0015] Furthermore, the flow and pressure control of the anode pipeline, cathode pipeline, and cooling pipeline includes a pressure sensor and a flow meter installed at the inlet of the fuel cell stack under test.

[0016] Furthermore, the anode pipeline, cathode pipeline and cooling pipeline are each equipped with an intake solenoid valve, and the number of intake solenoid valves is consistent with the type of air source connected to the air source.

[0017] The anode pipeline, cathode pipeline, and cooling pipeline are each equipped with an exhaust solenoid valve.

[0018] Furthermore, the types of air sources connected to the anode pipeline, cathode pipeline, and cooling pipeline are greater than or equal to 3.

[0019] Furthermore, each type of gas source is equipped with an electric pressure regulating valve.

[0020] As a second aspect of the present invention, a method for detecting the airtightness of a fuel cell stack is provided. The method employs any of the detection systems described above, and the specific steps are as follows:

[0021] S1: Connect the anode cavity, cathode cavity, and cooling cavity of the fuel cell stack under test to the corresponding anode pipeline, cooling pipeline and cathode pipeline, and fix the CVM inspection line to each bipolar plate of the stack.

[0022] S2: Open the inlet solenoid valves of the anode line, cathode line and cooling line, and close the outlet solenoid valves of the anode line, cathode line and cooling line to introduce gas into the anode chamber, cathode chamber and cooling chamber of the fuel cell stack.

[0023] When the specified value is reached, the intake solenoid valves of the anode pipeline, cathode pipeline and cooling pipeline are closed, wherein the set pressure of the cooling chamber is greater than that of the anode chamber and cathode chamber;

[0024] Record the pressure changes in the three chambers within a segment, and subtract the pressure value at the end from the initial pressure value P0 of each chamber. x The difference ΔP is used as the basis for judgment;

[0025] S3: Open the inlet and outlet solenoid valves of the anode pipeline, cathode pipeline and cooling pipeline to perform three-chamber purging;

[0026] After purging, close the outlet solenoid valves of the anode, cathode and cooling pipelines, and adjust the gas pressure and flow rate so that the single-chip voltage recorded by CVM exceeds 0.85V.

[0027] Close the air intake solenoid valves of the anode and cathode pipelines, record the voltage changes of each section of the test stack over a period of time, and at this time maintain the flow of gas into the cooling chamber and keep the pressure in the cooling chamber greater than or equal to the pressure in the anode and cathode chambers.

[0028] Record CVM data. The location of the single cell in the stack under test where the voltage V drops rapidly is the location of gas leakage between the anode and cathode chambers. The difference ΔV between the initial voltage value V0 and the voltage value V1 after the test is completed for each single cell is used as the criterion.

[0029] S4: Repeat S3 n times. During the test, the gas pressure in the cooling chamber is gradually reduced. Record the voltage change of each section of the stack under test at the end of the nth test as ΔVn. In each test, the pressure in the cooling chamber must be greater than or equal to the pressure in the anode chamber and cathode chamber. If a single cell shows a significant decrease in ΔVn, it is determined that there is leakage between the corresponding anode chamber or cathode chamber and the cooling water chamber.

[0030] S5: After completing tests S2 to S4, determine the location of the leak: If S2 indicates a leak, but S3 and S4 do not, the diagnosis is external pipe sealing failure; if S2 indicates no leak, S3 indicates a leak, and S4 indicates no leak, the diagnosis is anode-cathode cavity leakage caused by membrane electrode damage; if S2 and S3 indicate a leak, and S4 indicates a leak, the diagnosis is leakage between the anode cavity, cathode cavity, and cooling cavity caused by electrode plate damage; if S2 and S3 indicate a leak, and S4 indicates no leak, the diagnosis is good fuel cell stack airtightness.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1) The system provided by this invention can provide multiple gas sources for a single chamber, and can select different test gases as needed to meet different testing requirements. By adjusting the composition of the incoming gas, gas costs during testing can be saved, and special requirements such as hydrogen-hydrogen, hydrogen-oxygen, nitrogen purging, and dual-hydrogen rapid activation can be met.

[0033] 2) The testing method provided by this invention can complete the diagnosis in as little as 10 minutes. The detection system, which combines pressure change and CVM inspection data, can more accurately determine the leak point, shorten the product production cycle and reduce repair costs. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of the rapid detection system for the airtightness of the fuel cell stack of the present invention;

[0035] Figure 2 This is a schematic diagram showing the relationship between oxygen concentration and time at the interface between the cathode catalyst and the proton exchange membrane of the present invention.

[0036] As shown in the attached diagram: 101, Hydrogen pressure regulating valve; 102, Anode line flow meter; 103, Anode line pressure sensor; 201, Nitrogen pressure regulating valve; 202, Cathode line flow meter; 203, Cathode line pressure sensor; 301, Air pressure regulating valve; 302, Cooling line flow meter; 303, Cooling line pressure sensor; HI2, Anode line hydrogen inlet solenoid valve; HI1, Cathode line hydrogen inlet solenoid valve; HI3, Cooling line... Hydrogen inlet solenoid valve; NI1, nitrogen inlet solenoid valve for anode line; NI2, nitrogen inlet solenoid valve for cathode line; NI3, nitrogen inlet solenoid valve for cooling line; AI1, air inlet solenoid valve for anode line; AI2, air inlet solenoid valve for cooling line; AI3, air inlet solenoid valve for cathode line; HO, exhaust solenoid valve for anode line; NO, exhaust solenoid valve for cooling line; AO, exhaust solenoid valve for cathode line; CVM, single-chip voltage monitoring instrument. Detailed Implementation

[0037] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0038] Example 1

[0039] As a first embodiment of the present invention, the present invention provides a rapid testing system for the airtightness of a fuel cell stack, used to test the airtightness of a fuel cell stack, including a gas source, an anode piping system, a cathode piping system, a cooling piping system, and a CVM (Continuous Valve Monitoring) system. The gas source provides gas that meets the testing requirements; the gas can be one or more of hydrogen, air, oxygen, nitrogen, and helium. The anode piping system is connected to the anode cavity of the fuel cell stack under test, the cathode piping system is connected to the cathode cavity of the fuel cell stack under test, the cooling piping system is connected to the cooling cavity of the fuel cell stack under test, and the CVM system is connected to each electrode plate of the fuel cell for testing the voltage of a single cell in the stack. Figure 1 An implementation case of a rapid testing system for the airtightness of a fuel cell stack is presented.

[0040] Furthermore, the anode piping system consists of an anode piping intake system, an anode piping exhaust system HO, and an anode piping flow and pressure control system (102, 103); the cooling piping system consists of a cooling piping intake system, a cooling piping exhaust system AO, and a cooling piping flow and pressure control system (202, 203); and the cathode piping system consists of a cathode piping intake system, a cathode piping exhaust system AO, and a cathode piping flow and pressure control system (302, 303).

[0041] Furthermore, each pipeline air intake system is composed of solenoid valves, with the number of solenoid valves matching the type of gas source. To meet the requirements of accurate airtightness testing, the number of gas source types should be ≥3. The gas can be one or more of hydrogen, air, oxygen, nitrogen, and helium, and each gas should be equipped with an electric pressure regulating valve. The gas source shown in Example 1 consists of hydrogen and a hydrogen pressure regulating valve, nitrogen and a nitrogen pressure regulating valve, and air and an air pressure regulating valve. The anode pipeline air intake system consists of an anode pipeline hydrogen intake solenoid valve HI2, an anode pipeline nitrogen intake solenoid valve NI1, and an anode pipeline air intake solenoid valve AI1; the cooling pipeline air intake system consists of a cooling pipeline hydrogen intake solenoid valve HI1, a cooling pipeline nitrogen intake solenoid valve NI2, and a cooling pipeline air intake solenoid valve AI3; the cathode pipeline air intake system consists of a cathode pipeline hydrogen intake solenoid valve HI3, a cathode pipeline nitrogen intake solenoid valve NI3, and a cathode pipeline air intake solenoid valve AI2.

[0042] As a second embodiment of the present invention, this embodiment also provides a testing method based on the above system, the specific steps of which are as follows:

[0043] S1: Place the fuel cell stack on the test bench, connect the anode cavity, cathode cavity and cooling cavity of the fuel cell stack under test to the corresponding interfaces of the test bench, and fix the CVM inspection line to each bipolar plate of the fuel cell stack to ensure that the test bench can collect the voltage of each single cell in real time.

[0044] S2: Open solenoid valves NI1, NI2, and NI3, and close battery valves HO, NO, and AO to introduce nitrogen gas into the anode, cathode, and cooling chambers of the fuel cell stack. When the specified value is reached, close solenoid valves NI1, NI2, and NI3. The set pressure in the cooling chamber should be higher than that in the anode and cathode chambers. Record the pressure changes in the three chambers over a period of time. The pressure change is calculated by subtracting the initial pressure value P0 from the final pressure value P in each chamber. x The difference ΔP is used as the basis for judgment.

[0045] S3: Open solenoid valves HI2, AI2, NI1, NI2, HO, NO, and AO to introduce a hydrogen-nitrogen mixture into the anode chamber, air into the cathode chamber, and nitrogen into the cooling chamber to complete the three-chamber purging. After purging, close solenoid valves HO, NO, and AO, and adjust the gas pressure and flow rate so that the single-cell voltage recorded by CVM exceeds 0.85V. Close solenoid valves HI2 and AI3, and record the voltage changes of each section of the test stack over a period of time. At this time, maintain the flow of nitrogen in the cooling chamber and keep the pressure in the cooling chamber greater than or equal to the pressure in the anode and cathode chambers. Record the CVM data. The location of the single cell in the test stack where the single-cell voltage V drops rapidly is the location of gas leakage between the anode and cathode chambers. The difference ΔV between the initial voltage value V0 and the voltage value V1 after the test of each single cell is used as the criterion.

[0046] S4: Repeat S3 n times, gradually decreasing the gas pressure in the cooling chamber during the test. For example, set the nitrogen pressure to P for the first test. N -p, the nitrogen pressure is set to P for the nth test. N -np, n≥2, 1≤p≤20, record the voltage change of each section in the stack under test at the end of the nth test as ΔVn. Each test must maintain the pressure in the cooling chamber greater than or equal to the pressure in the anode and cathode chambers. If a single cell shows a significant decrease in ΔVn, it is determined to be a leakage between the anode chamber and the cooling water chamber (or between the cathode chamber and the cooling water chamber).

[0047] S5: After completing tests S2 to S4, the program begins to determine the location of the leak. If S2 determines a leak, but S3 and S4 do not, the diagnosis is an external pipe seal failure. If S2 determines no leak, S3 determines a leak, and S4 determines no leak, the diagnosis is a cross-flow between the anode and cathode chambers caused by membrane electrode damage. If S2 and S3 both determine a leak, and S4 both determine a leak, the diagnosis is a cross-flow between the anode, cathode, and cooling chambers caused by electrode plate damage. If S2 and S3 both determine no leak, the diagnosis is that the fuel cell stack is airtight and it can proceed to the next process.

[0048] The simulation results related to the above testing methods are as follows: Figure 2 In S4, the cooling chamber pressure is set to 30 kPa and the cathode chamber pressure is set to 20 kPa. After closing the cathode chamber air intake solenoid valve, if there is a leak point between the cathode chamber and the cooling water chamber, the oxygen concentration at the cathode electrochemical reaction interface will decrease by 50% within 5 seconds.

[0049] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for detecting the airtightness of a fuel cell stack, used to detect fuel cell stacks, characterized in that, The following testing system is used for testing, and the testing system includes: The anode line is connected to the anode cavity of the fuel cell stack under test, and includes anode line air intake, anode line exhaust, and anode line flow and pressure control; The cathode line is connected to the cathode cavity of the fuel cell stack under test, and includes cathode line air intake, cathode line exhaust and cathode line flow and pressure control; The cooling pipeline is connected to the cooling chamber of the fuel cell stack under test, and includes cooling pipeline air inlet, cooling pipeline exhaust and cooling pipeline flow and pressure control; The gas source includes multiple gas sources of different types, which are respectively connected to the anode pipeline, cathode pipeline and cooling pipeline to provide test gases of different gas components. CVM inspection, connected to each electrode plate of the fuel cell, is used to test the voltage of individual cells in the stack; The method steps include: S1: Connect the anode cavity, cathode cavity, and cooling cavity of the fuel cell stack under test to the corresponding anode pipeline, cooling pipeline and cathode pipeline, and fix the CVM inspection line to each bipolar plate of the fuel cell stack under test. S2: Open the inlet solenoid valves of the anode line, cathode line and cooling line, and close the outlet solenoid valves of the anode line, cathode line and cooling line to introduce gas into the anode chamber, cathode chamber and cooling chamber of the fuel cell stack. When the specified value is reached, the intake solenoid valves of the anode pipeline, cathode pipeline and cooling pipeline are closed, wherein the set pressure of the cooling chamber is greater than that of the anode chamber and cathode chamber; Record the pressure changes in the three chambers within a segment, and subtract the pressure value at the end from the initial pressure value P0 of each chamber. x The difference ΔP is used as the basis for judgment; S3: Open the inlet and outlet solenoid valves of the anode pipeline, cathode pipeline and cooling pipeline to perform three-chamber purging; After purging, close the outlet solenoid valves of the anode, cathode and cooling pipelines, and adjust the gas pressure and flow rate so that the single-chip voltage recorded by CVM exceeds 0.85V. Close the air intake solenoid valves of the anode and cathode pipelines, record the voltage changes of each section of the test stack over a period of time, and at this time maintain the flow of gas into the cooling chamber and keep the pressure in the cooling chamber greater than or equal to the pressure in the anode and cathode chambers. Record CVM data. The location of the single cell in the stack under test where the voltage V drops rapidly is the location of gas leakage between the anode and cathode chambers. The difference ΔV between the initial voltage value V0 and the voltage value V1 after the test is completed for each single cell is used as the criterion. S4: Repeat S3 n times. During the test, the gas pressure in the cooling chamber is gradually reduced. Record the voltage change of each section of the stack under test at the end of the nth test as ΔVn. In each test, the pressure in the cooling chamber must be greater than or equal to the pressure in the anode chamber and cathode chamber. If a single cell shows a significant decrease in ΔVn, it is determined that there is leakage between the corresponding anode chamber or cathode chamber and the cooling water chamber. S5: After completing tests S2 to S4, determine the location of the leak: If S2 indicates a leak, but S3 and S4 do not, the diagnosis is external pipe sealing failure; if S2 indicates no leak, S3 indicates a leak, and S4 indicates no leak, the diagnosis is anode-cathode cavity leakage caused by membrane electrode damage; if S2 and S3 indicate a leak, and S4 indicates a leak, the diagnosis is leakage between the anode cavity, cathode cavity, and cooling cavity caused by electrode plate damage; if S2 and S3 indicate a leak, and S4 indicates no leak, the diagnosis is good fuel cell stack airtightness.

2. The method for detecting the airtightness of a fuel cell stack according to claim 1, characterized in that, The gas source includes one or more of the following: hydrogen, air, oxygen, nitrogen, and helium.

3. The method for detecting the airtightness of a fuel cell stack according to claim 1, characterized in that, The flow and pressure control of the anode pipeline, cathode pipeline and cooling pipeline includes a pressure sensor and a flow meter installed at the inlet of the fuel cell stack under test.

4. The method for detecting the airtightness of a fuel cell stack according to claim 1, characterized in that, The anode pipeline, cathode pipeline and cooling pipeline are each equipped with an intake solenoid valve, and the number of intake solenoid valves is consistent with the type of air source connected to the gas source. The anode pipeline, cathode pipeline, and cooling pipeline are each equipped with an exhaust solenoid valve.

5. The method for detecting the airtightness of a fuel cell stack according to claim 1, characterized in that, The types of air sources connected to the anode pipeline, cathode pipeline, and cooling pipeline are greater than or equal to 3.

6. The method for detecting the airtightness of a fuel cell stack according to claim 1, characterized in that, Each type of gas source is equipped with an electric pressure regulating valve.

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