Fuel cell stack assembly sealing stress simulation analysis method

Abstract

The application discloses a fuel cell stack assembly sealing stress simulation analysis method, comprising the following steps: constructing a fuel cell stack three-dimensional model through three-dimensional software, and cutting the gas flow field in the stack into single cell flow fields; performing CFD calculation through MATLAB and Fluent software, and extracting the gas force of the gas sealing cavity in the single cell flow field; simplifying and cutting the stack model, and performing CAE simulation of the assembly process in ABAQUS to obtain first simulation calculation results; taking the gas force as secondary external boundary conditions, performing CAE simulation of the fuel cell stack power generation process based on the first simulation calculation results to obtain second simulation calculation results; and evaluating the sealing performance of the sealing element in the fuel cell stack working process by comparing the second simulation calculation results of multiple sealing element models.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell stack assembly technology, and specifically relates to a simulation analysis method for the sealing stress of fuel cell stack assembly. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) generate electricity through the chemical reaction of hydrogen and oxygen. They are characterized by small size, high energy density, and low noise, making them widely applicable and a hot research topic in the new energy field. A fuel cell stack consists of multiple individual cells assembled in a sealed manner, and its sealing design directly affects the safety, reliability, and durability of the fuel cell. However, in practical applications, it has been found that the seals of each individual cell often suffer varying degrees of damage or even failure due to design or assembly problems, leading to stack leakage and significantly shortening the battery's lifespan. Therefore, research on fuel cell sealing is particularly important. Research on the sealing performance of fuel cell stacks mainly involves the material properties of the seals themselves and the overall stack structure, such as the shape of the contact surface between the two sealing bipolar plates. These factors all affect the contact stress distribution on the sealing surface of the fuel cell stack, thus impacting the battery's sealing performance. Therefore, simulation analysis of the fuel cell stack seal is crucial after design. However, currently, there is no simulation analysis method specifically for fuel cell stack seals. To address this, this invention provides a simulation analysis method for the assembly and sealing stress of a fuel cell stack. Through sensor detection and operational testing during the actual assembly of the fuel cell stack, the deformation and assembly force variation range of the sealing components are obtained. These deformation and assembly force are used as two external conditions in the sealing component press-fit simulation process. Specifically, by comparing these conditions, the accelerated convergence condition in the sealing simulation process, namely the press-fit displacement, is extracted to replace the external force input during simulation, ensuring better simulation convergence and reliable results. This effectively solves the problems of uneven contact stress distribution on the fuel cell stack sealing surface and the stress on the assembled seal.

[0003] Currently, there are gaps in simulation analysis methods for fuel cell stack sealing. First, verifying the sealing performance mainly relies on experiments and assembly tests. During fuel cell stack testing, only the gas pressure in the main pipe can generally be extracted. Sensors inside the stack are difficult to access. After the gas undergoes diversion and cross-sectional area changes, the gas pressure has already changed, making it difficult to extract simulation data for minute geometric positions in flow field simulation. Only through co-simulation methods and specific self-defined editing at the operational language level can simulation data for target positions be extracted relatively well. Second, there is currently no suitable simulation evaluation method for fuel cell stack sealing. The bipolar plate model has a complex structure, poor model mesh quality, and difficulty in convergence. If a complete bipolar plate and adhesive wire model is used for sealing simulation, the number of meshes is huge, making the calculation difficult to complete. Summary of the Invention

[0004] This application method starts from the perspective of fuel cell stack assembly, combines flow field and MATLAB co-simulation, extracts the lateral force boundary conditions of the seal during the fuel cell stack operation, and extracts the deformation of the seal under multiple actions through joint simulation of force boundary conditions and vertical displacement boundary conditions. The sealing performance of the corresponding seal is judged by the peel strength standard.

[0005] The technical solution of this invention patent application is as follows:

[0006] A simulation analysis method for the sealing stress of a fuel cell stack assembly includes:

[0007] Using 3D software, a 3D model of the fuel cell stack is constructed, and the gas flow field inside the stack is divided into the flow field of individual cells.

[0008] CFD calculations were performed using MATLAB and Fluent software to extract the gas forces within the gas-sealed cavity of the single-cell flow field.

[0009] The fuel cell stack model is simplified and meshed, and the assembly process is simulated in ABAQUS to obtain the first simulation results, which include the optimal computational convergence.

[0010] Using the gas force as a secondary external boundary condition, CAE simulation of the fuel cell stack gas supply and power generation process is performed based on the first simulation calculation results to obtain the second simulation calculation results, which include the overall force form and deformation of the sealing component.

[0011] By comparing the second simulation calculation results among multiple sealing component models, the sealing performance of the sealing component during the operation of the fuel cell stack is evaluated. The evaluation includes determining whether the sealing performance meets the preset sealing component peel strength requirements. If it does, the simulation results are output.

[0012] The process of constructing a 3D model of the fuel cell stack using 3D software and dividing the gas flow field inside the stack into individual cell flow fields includes:

[0013] The gas flow field structure inside the fuel cell stack is modeled and meshed to obtain the flow field of a single cell. The flow field of the single cell is simulated using Fluent software to obtain the gas flow situation inside the fuel cell stack under steady-state conditions.

[0014] The step of extracting the gas forces within the gas-sealed cavity of the single-cell battery flow field through CFD calculations using MATLAB and Fluent software includes: generating a joumal file using MATLAB software. This joumal file is primarily used to obtain gas force data within the flow field space of the single-cell battery. Specific steps include:

[0015] Create an Iso-Surface, set its width in the program, divide the Iso-Surface into multiple small sections, name them, and obtain the gas force of each section.

[0016] The location of the sealed gas cavity is located by using the gas flow field model inside the fuel cell stack. A journal file is generated using MATLAB and imported into the calculation results of Fluent. Fluent then extracts the gas force values ​​in the gas cavity near the seal during the fluid simulation based on the journal file.

[0017] Before performing CAE simulation of the assembly process in ABAQUS, experimental tests are conducted during the stack assembly process to obtain the assembly displacement and assembly force of individual cells during compression.

[0018] The fuel cell stack model was simplified and meshed. CAE simulation of the assembly process was performed in ABAQUS, and the first simulation results were obtained, including:

[0019] The fuel cell stack model is simplified and segmented to obtain a simplified model including upper and lower bipolar plate sealing grooves, upper and lower sealing components, and membrane electrode frame. The model is then meshed, and the assembly displacement and assembly force are used as boundary conditions. The assembly process is simulated in ABAQUS using CAE simulation. The convergence of the calculation results of the two boundary conditions is compared, and the CAE simulation result with better convergence is selected as the basis for the second CAE simulation.

[0020] The step of using the gas force as a secondary external boundary condition, and based on the first simulation calculation results, performing CAE simulation of the fuel cell stack gas supply and power generation process to obtain the second simulation calculation results includes:

[0021] Based on the first simulation calculation results, the gas supply process of the fuel cell is simulated. The gas force obtained in the CFD calculation is used as a secondary external boundary condition and applied to the inner surface of the seal. A secondary CAE simulation is performed to calculate the overall stress form and deformation of the seal.

[0022] The beneficial effects of this invention are as follows:

[0023] (1) During the fuel cell stack test, only the gas pressure in the main pipe can be extracted. It is difficult for the internal sensors of the stack to intervene. After the gas is split and the cross-sectional area changes, the gas pressure has already changed. It is difficult to extract the simulation data of small geometric positions in the flow field simulation. The simulation data of the target position can be extracted better through joint simulation.

[0024] (2) There is currently no suitable simulation evaluation method for fuel cell stack sealing. The bipolar plate model of fuel cell stack has a complex structure, poor model mesh quality, and is difficult to converge in calculation. If a complete bipolar plate and glue wire model is used for sealing simulation, the number of meshes is huge and the calculation is difficult to complete. The invention method submitted in this application has a simple model structure, good mesh quality, and a small number of meshes, and has good convergence in the calculation process.

[0025] (3) This method uses the pressure displacement to replace the external force input in the simulation process, which ensures that the simulation calculation convergence effect is better and the result is reliable.

[0026] (4) There is currently no mature method to evaluate the sealing performance of bipolar plate seals during operation. This method starts from the perspective of fuel cell assembly, combines flow field and MATLAB co-simulation, extracts the lateral force boundary conditions of the seals during fuel cell operation, and extracts the deformation of the seals under multiple actions through joint simulation of force boundary conditions and vertical displacement boundary conditions. The sealing performance of the corresponding seals is judged by the peel strength standard. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating an embodiment of a simulation analysis method for the sealing of a fuel cell stack assembly provided in this application.

[0028] Figure 2 This is a schematic diagram illustrating the specific steps of an embodiment of a simulation analysis method for the sealing of a fuel cell stack provided in this application.

[0029] Figure 3 A schematic diagram of the fuel cell stack structure simulation model in the simulation analysis method for the sealing of fuel cell stack assembly provided in this application;

[0030] Figure 4 A schematic diagram of the gas cavity structure inside the seal in a simulation analysis method for the sealing of a fuel cell stack assembly provided in this application. Detailed Implementation

[0031] The invention will be further described below with reference to the accompanying drawings. The invention provides a simulation analysis method for the sealing stress of a fuel cell stack assembly, such as... Figure 1 , Figure 2 As shown, it includes:

[0032] As shown in S201, a three-dimensional model of the fuel cell stack is constructed using 3D software, and the gas flow field inside the stack is divided into the flow field of a single cell:

[0033] As shown in S202, the gas flow field structure inside the stack is modeled and meshed to obtain the flow field of a single cell. The flow field of the single cell is simulated using Fluent software to obtain the gas flow situation inside the stack under steady-state conditions.

[0034] CFD calculations were performed using MATLAB and Fluent software to extract the gas forces within the gas-sealed cavity of the single-cell flow field.

[0035] As shown in S203, a program is written using MATLAB software to generate a journal file. This journal file is primarily used to obtain gas force data within the flow field space of a single battery cell. Specific steps include:

[0036] Create an Iso-Surface, set its width in the program, divide the Iso-Surface into multiple small sections, and name them to facilitate obtaining the gas force of each section.

[0037] As shown in S204, the location of the sealed gas cavity is located by the gas flow field model inside the fuel cell stack. A journal file is generated by combining the MATLAB program and imported into the calculation results of Fluent. Fluent extracts the gas force values ​​in the gas cavity near the seal during the fluid simulation based on the journal file.

[0038] The simulation of the fuel cell stack includes two processes: assembly and use. Therefore, the first simulation involves pressing the fuel cell stack using a press, and this simulation needs to extract the stress on the seals during the pressing process. After assembly, the stack is secured with components, and the stack remains in a pressed state. Then, gas is introduced for use, at which point the fuel cell begins generating electricity. After gas is introduced, the gas exerts a lateral force on the seals. Therefore, the second simulation needs to add the gas force as a boundary condition based on the results of the first simulation to simulate the fuel cell's gas-feeding process.

[0039] As shown in S205, experimental tests are conducted during the stack assembly process to obtain the assembly displacement and assembly force of individual cells during compression.

[0040] The fuel cell stack model is simplified and meshed. CAE simulation of the assembly process is performed in ABAQUS to obtain the first simulation results, which include optimal computational convergence.

[0041] As shown in S206, the fuel cell stack model is simplified and segmented to obtain a simplified model including the upper and lower bipolar plate sealing grooves, upper and lower sealing components, and the membrane electrode frame, as shown in the figure. Figure 3 As shown, the model is meshed, and the assembly displacement and assembly force obtained during the test are used as boundary conditions. The assembly process is simulated in the commercial software ABAQUS. The convergence of the CAE simulation is affected by the boundary conditions. The second CAE simulation adds gas boundary conditions, which is more complex and has higher requirements for convergence. As shown in S207, the convergence of the two boundary conditions in the first simulation is compared. The CAE simulation result with better convergence is selected as the basis for the second CAE simulation to ensure the convergence of the second simulation.

[0042] As shown in S208 and S209, the gas force is used as a secondary external boundary condition. Based on the first simulation calculation results, a CAE simulation of the fuel cell stack gas supply and power generation process is performed to obtain the second simulation calculation results:

[0043] like Figure 4 As shown, based on the first simulation calculation results, the gas supply process of the fuel cell is simulated. The gas force obtained in the CFD calculation is used as a secondary external boundary condition and applied to the inner surface of the seal. A secondary CAE simulation is performed to calculate the overall stress form and deformation of the seal.

[0044] Based on the seal peel strength requirements specified in the design documents, the sealing performance of the seals during the operation of the fuel cell stack is evaluated by comparing the secondary CAE calculation results among multiple seal models. The evaluation includes determining whether the sealing performance meets the preset seal peel strength requirements. If it does, the simulation results are output. During the evaluation process, the fuel cell structure design optimization and modification are guided.

[0045] This method starts from the perspective of fuel cell stack assembly, and combines flow field and MATLAB co-simulation to extract the lateral force boundary conditions of the seal during the operation of the fuel cell stack. By performing co-simulation of force boundary conditions and vertical displacement boundary conditions, the deformation of the seal under multiple actions is extracted, and the sealing performance of the corresponding seal is evaluated by the peel strength standard.

Claims

1. A method for simulation analysis of the sealing stress in a fuel cell stack assembly, characterized in that, include: Using 3D software, a 3D model of the fuel cell stack is constructed, and the gas flow field inside the stack is divided into the flow field of individual cells. The gas forces within the gas-sealed cavity inside the flow field of the single-cell battery were extracted using CFD calculations performed jointly by MATLAB and Fluent software. The extraction process included: writing a program in MATLAB to generate a journal file, which was used to obtain gas force data within the flow field space of the single-cell battery. Specific steps included: creating an Iso-Surface, setting its width in the program, dividing the Iso-Surface into multiple small sections and naming them, obtaining the gas forces at each section, locating the sealed gas cavity using a gas flow field model inside the battery stack, generating a journal file using the MATLAB program, importing the journal file into the Fluent calculation results, and using Fluent to extract the gas force values ​​within the gas cavity near the seal during fluid simulation based on the journal file. The fuel cell stack model is simplified and meshed, and the assembly process is simulated in ABAQUS to obtain the first simulation results, which include the optimal computational convergence. Using the gas force as a secondary external boundary condition, CAE simulation of the fuel cell stack gas supply and power generation process is performed based on the first simulation calculation results to obtain the second simulation calculation results, which include the overall force form and deformation of the sealing component. By comparing the second simulation calculation results among multiple sealing component models, the sealing performance of the sealing component during the operation of the fuel cell stack is evaluated. The evaluation includes determining whether the sealing performance meets the preset sealing component peel strength requirements. If it does, the simulation results are output.

2. The method for simulation analysis of the sealing stress of fuel cell stack assembly according to claim 1, characterized in that, The process of constructing a 3D model of the fuel cell stack using 3D software and dividing the gas flow field inside the stack into individual cell flow fields includes: The gas flow field structure inside the fuel cell stack is modeled and meshed to obtain the flow field of a single cell. The flow field of the single cell is simulated using Fluent software to obtain the gas flow situation inside the fuel cell stack under steady-state conditions.

3. The method for simulation analysis of the sealing stress of fuel cell stack assembly according to claim 1, characterized in that, Before performing CAE simulation of the assembly process in ABAQUS, experimental tests are conducted during the stack assembly process to obtain the assembly displacement and assembly force of individual cells during compression.

4. The method for simulation analysis of the sealing stress of fuel cell stack assembly according to claim 1, characterized in that, The fuel cell stack model was simplified and meshed. CAE simulation of the assembly process was performed in ABAQUS, and the first simulation results were obtained, including: The fuel cell stack model was simplified and divided to obtain a simplified model including upper and lower bipolar plate sealing grooves, upper and lower sealing components, and membrane electrode frame. The model was then meshed, and the assembly displacement and assembly force were used as boundary conditions. The assembly process was simulated in ABAQUS using CAE simulation. The convergence of the two boundary condition calculation results was compared, and the CAE simulation result with better convergence was selected as the basis for the second CAE simulation.

5. The method for simulation analysis of the sealing stress of fuel cell stack assembly according to claim 1, characterized in that, The step of using the gas force as a secondary external boundary condition, and based on the first simulation calculation results, performing CAE simulation of the fuel cell stack gas supply and power generation process to obtain the second simulation calculation results includes: Based on the first simulation calculation results, the gas supply process of the fuel cell is simulated. The gas force obtained in the CFD calculation is used as a secondary external boundary condition and applied to the inner surface of the seal. A secondary CAE simulation is performed to calculate the overall stress form and deformation of the seal.

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