A multi-physics coupling simulation analysis method for fuel cells under inhomogeneous compression state

Abstract

The present invention discloses a multi-physical field coupling simulation and analysis method for a fuel cell under a non-homogeneous compression state, establishes a three-dimensional simulation model of a proton exchange membrane fuel cell with semi-channel symmetry, couples a solid mechanics module, and analyzes the compression amount of the gas diffusion layer and the optimal assembly pressure of the pores under the non-homogeneous compression; then, according to the non-homogeneous porosity of the gas diffusion layer, couples with the secondary current, concentrated material, and Brinkman equation modules to analyze the material flow, mass transfer, and electrochemical physical and chemical phenomena of the battery in an isothermal steady state to analyze the optimal assembly pressure under the working state of the battery; utilizes the simulated data set to couple with the solid heat transfer module to calculate the temperature field distribution of the heat generated by the battery and analyze the temperature distribution under the working state of the battery. The present invention realizes a more comprehensive analysis of the influence of the assembly pressure on the mass transfer concentration, velocity field distribution, battery performance, and temperature field distribution of the fuel cell under a non-homogeneous compression state, thereby improving the performance of the proton exchange membrane fuel cell.

Description

Technical Field

[0001] The present invention relates to the field of fuel cells, and in particular to a multi-physical field coupling simulation method for proton exchange membrane fuel cells under a non-homogeneous compression state. Background Art

[0002] Proton exchange membrane fuel cell (PEMFC) is a power generation device that directly converts the chemical energy in the chemical bonds of reactants into electrical energy without the need for a combustion reaction. The conversion efficiency is over 50%, and it also has the characteristics of low noise, low infrared radiation, high power density and wide application.

[0003] Relevant research on proton exchange membrane fuel cells is also increasingly concentrated, because proton exchange membrane fuel cells are a large and complex system with multiple physical fields coupled to each other, including the flow of reaction gases in the flow channel and diffusion in the porous medium under working conditions, which in turn causes electrochemical reactions in the electrode catalyst layer, the transmission of the product water in the proton exchange membrane, the transfer of electrons and ions in different media, and heat conduction, and other complex physical and chemical transformations and mutual influences.

[0004] At present, the internal operation of fuel cells is mainly studied through experimental and simulation methods in order to better optimize fuel cells. Compared with experimental research, fuel cell simulation can save costs, shorten the experimental cycle, and get rid of the limitations of experimental equipment, and can explore the working performance of fuel cells from multiple dimensions.

[0005] In simulation studies, the current simulation methods have two problems with the impact of assembly stress on the physical structure and chemical properties of fuel cells. First, when assembly stress is applied, the gas diffusion layer is more prone to deformation because its Young's modulus is much lower than that of other components. The deformation often occurs below the flow ridge, and the gas diffusion layer below the flow channel is not deformed. At this time, the porosity of the gas diffusion layer should be uneven. However, in current simulations, the porosity is often consistent. On the other hand, since only a single physical field is solved when simulating a fuel cell or multiple physics are not coupled, there is a large deviation from the actual working conditions of the battery, which has become an urgent problem to be solved. Summary of the invention

[0006] In order to solve the problems of the prior art, the purpose of the present invention is to overcome the shortcomings of the existing technology and provide a multi-physical field coupling simulation analysis method for a fuel cell under a non-homogeneous compression state. In view of the defects of the existing simulation method, the complex physical and chemical phenomena caused by non-homogeneous compression in the proton exchange membrane fuel cell are analyzed. Under the non-homogeneous compression state, a more comprehensive analysis is made of the effect of assembly pressure on the mass transfer concentration of substances inside the fuel cell, the velocity field distribution, the battery performance and the temperature field distribution, so as to improve the analysis accuracy, facilitate the exploration and acquisition of suitable assembly pressure, optimize the operating parameters, structural design and material properties of the proton exchange membrane fuel cell, and make the proton exchange membrane fuel cell have higher performance.

[0007] In order to achieve the above invention purpose, the present invention adopts the following technical solution:

[0008] A multi-physics coupling simulation analysis method for a fuel cell under a non-homogeneous compression state comprises the following steps:

[0009] S1. Construct a proton exchange membrane fuel cell with a semi-channel symmetric model. Under steady-state working conditions, couple the solid mechanics physical field to establish a performance model of the semi-channel symmetric proton exchange membrane fuel cell affected by assembly pressure, and simulate the porosity change and compression displacement change of the gas diffusion layer under inhomogeneous compression;

[0010] S2. Based on the change of gas diffusion layer parameters during heterogeneous compression obtained in step S1, a multi-physics field coupled simulation is performed to establish a proton exchange membrane fuel cell model coupled with multi-physics fields under heterogeneous compression, and calculate the change of battery performance under different pressures;

[0011] S3. Combine the solid mechanics heat transfer physical field and the battery performance change results obtained in S2 to calculate the battery heat generation temperature distribution under isothermal working conditions.

[0012] Compared with the existing solution of directly solving the steady-state working condition of the fuel cell under the homogeneous compression state by using multiple physical fields such as solid mechanics physical field and heat transfer physical field, the solution of the present invention has significantly improved convergence and significantly reduced calculation amount.

[0013] Preferably, in step S1, under heterogeneous compression, a performance model of the semi-channel symmetric proton exchange membrane fuel cell affected by assembly pressure is established, characterized in that it includes the following steps:

[0014] S101. Establish a three-dimensional simulation model of a proton exchange membrane fuel cell, the model includes a battery anode part and a battery anode part, and a proton exchange membrane arranged between the battery anode part and the battery anode part; the battery anode part includes an anode cooling water flow channel, an anode plate, an anode reactant flow channel, an anode gas diffusion layer, and an anode catalyst layer; the battery anode part includes a cathode catalyst layer, a cathode diffusion layer, a cathode reactant flow channel, a cathode plate, and a cathode cooling water flow channel; wherein the anode diffusion layer, the anode catalyst layer, the proton exchange membrane, the cathode catalyst layer, and the cathode diffusion layer are sequentially combined to form a membrane electrode assembly; in order to reduce the number of finite element calculation units of the three-dimensional simulation model, a symmetric boundary is used in the symmetric domain in the three-dimensional simulation model;

[0015] S102. Add a solid mechanics module to calculate the compression of the gas diffusion layer and the porosity changes at each position under different assembly pressure states, and obtain the changes in gas diffusion layer parameters during inhomogeneous compression.

[0016] In step S1, the solid mechanics module is used to simulate the situation where the PEMFC applies a preload to the cathode and anode gas diffusion layers. This module can calculate the stress and displacement changes of the gas diffusion layer after being squeezed. From this, the change in porosity is derived, and the change in porosity can be coupled to the definition of the porous matrix properties in the Brinkman equation. In addition, the change in porosity will also cause changes in the permeability, electrical conductivity, thermal conductivity of the gas diffusion layer, and the contact resistance between the gas diffusion layer and the bipolar plate surface. Therefore, it is the basis for the parameters required for the multi-physics field below.

[0017] Preferably, in step S2, establishing a proton exchange membrane fuel cell model with multi-physical field coupling under inhomogeneous compression comprises the following steps:

[0018] S201. Add a series of physical field interfaces including Brinkman equation interface, concentrated species transport interface, and secondary current distribution interface, couple the physical fields to each other, and calculate the reactant flow, reactant transport, and electrochemical reaction in the fuel cell respectively;

[0019] S202. Define the parameters required for the physical field interface of the proton exchange membrane fuel cell, including the assembly pressure, the change of the corresponding physical parameters caused by the change of the porosity calculated in step S1, and the global operating temperature, the physical parameters required for the physical field, the solution variables, the initial values ​​and the boundary conditions;

[0020] S203. Meshing the three-dimensional geometric simulation model of the proton exchange membrane fuel cell using Comsol, performing steady-state solution on the divided three-dimensional simulation model, and obtaining a data set of solution variables of the simulation model;

[0021] S204. Perform visual post-processing on the work result data set, and complete the numerical simulation of the flow field, mass transfer and electrochemical physical and chemical phenomena of the isothermal steady-state proton exchange membrane fuel cell in a visual post-processing manner.

[0022] Preferably, the Brinkman equation interface, i.e., the porous media mass transfer module is used to simulate the mass transfer process in the proton exchange membrane fuel cell, including the momentum transfer and diffusion behavior of the reactants hydrogen, oxygen and the product water, acting on the flow channel, gas diffusion layer and catalyst layer of the anode part of the cell and the anode part of the cell, thereby obtaining the velocity and pressure distribution of the reactants, and coupling with the concentrated species transfer interface.

[0023] Preferably, the concentrated species transfer interface is used to describe the concentration distribution of the anode and cathode reactants in each effective domain.

[0024] Preferably, the mutual coupling between physical fields refers to calculating the convective mass transfer flux of the corresponding domain by using the velocity or pressure of the physical field of the Brinkman equation interface with the corresponding domain.

[0025] Preferably, for the secondary current distribution interface, the secondary current distribution module is used to simulate the charge transfer process in the proton exchange membrane fuel cell, acting on the proton exchange membrane and the gas diffusion layer and catalyst layer of the battery anode part. The electrode current density distribution and membrane current density distribution can be calculated through the secondary current distribution module, and the potential, potential and current trend can be analyzed. The electrode layer reactant concentration distribution obtained by the concentrated species transfer physical field calculation is used to calculate the overpotential of the electrode reaction kinetics.

[0026] In step S204, the final post-processing obtains visualized simulation results including a gas diffusion layer compression variation diagram of a proton exchange membrane fuel cell, a porosity and assembly pressure relationship diagram, a voltage-current density performance curve under various assembly stresses, and three-dimensional distribution cloud diagrams of reactant and product concentration fields, velocity fields, etc.

[0027] In order to reduce the corresponding amount of calculation, the steady state is solved step by step:

[0028] 1. Solve the physical field of secondary current distribution;

[0029] 2. Solve the Brinkman equation to obtain the velocity field distribution;

[0030] 3. Couple all physical fields to obtain the solution variables.

[0031] Preferably, in step S3, a proton exchange membrane fuel cell model with multi-physical field coupling under inhomogeneous compression is established, characterized in that it includes the following steps:

[0032] S301. Add solid heat transfer physical field interface to calculate the heat generation temperature field distribution of fuel cell isothermal operation;

[0033] S302. Define the physical property parameters, solution variables, initial values ​​and boundary conditions required for the solid heat transfer physical field interface of the proton exchange membrane fuel cell;

[0034] S303. Couple the simulation results of step S2 and the solid heat transfer physical field interface to calculate the temperature distribution of heat generated under different assembly stresses of the battery.

[0035] Preferably, the solid heat transfer physical field is used to describe the temperature field distribution of heat generation in an isothermal proton exchange membrane fuel cell, and the solid heat transfer physical field is coupled with the total power consumption density in the simulation results of the secondary current distribution physical field to calculate the temperature distribution of the solid heat transfer physical field.

[0036] Preferably, when adding a solid heat transfer physical field interface, the physical property parameters required for adding the physical field mainly include thermal conductivity, density, constant-pressure heat capacity, electrolyte of the porous domain, electrode and pore percentage parameters.

[0037] Compared with the prior art, the present invention has the following obvious outstanding substantive features and significant advantages:

[0038] 1. The simulation method provided by the present invention adds a solid mechanics module to the proton exchange membrane fuel cell model to describe the influence of assembly stress on the compression and porosity of the fuel cell gas diffusion layer, so as to explore the influence of assembly pressure on the fuel cell performance;

[0039] 2. The simulation method provided by the present invention simulates and calculates the material flow field, mass transfer, electrochemical and physical chemical processes in the heterogeneous compressed proton exchange membrane fuel cell, which can optimize the operating parameters, structural design, and material properties of the proton exchange membrane fuel cell, so that the proton exchange membrane fuel cell has higher performance;

[0040] 3. The simulation method provided by the present invention adopts a semi-channel symmetrical structure modeling, which reduces a large amount of calculation;

[0041] 4. The present invention establishes a multi-physical field coupling simulation method for fuel cells under heterogeneous compression state, which can be used to explore the influence of assembly pressure on the structural parameters of the gas diffusion layer of the fuel cell, and at the same time optimize the reactant flow field structure of the battery, providing a theoretical basis for the physical and chemical phenomena inside the proton exchange membrane fuel cell;

[0042] 5. The method of the present invention provides a reference for the heat generation of the battery during isothermal operation through temperature field correlation; it can solve the influence of the assembly pressure on the internal performance changes and thermal energy changes of the fuel cell during the actual assembly process of the battery, thereby exploring the appropriate assembly pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic structural diagram of a three-dimensional simulation model of a proton exchange membrane fuel cell of the present invention.

[0044] Figure 2 The following is a cross-sectional view of the structure of a three-dimensional simulation model of a proton exchange membrane fuel cell according to the present invention. Figure 2 middle:

[0045] One part is the anode part of the battery: 1-1, anode reactant flow channel; 1-2, anode gas diffusion layer; 1-3, anode cooling water flow channel; 1-4, anode plate; 1-5, anode catalyst layer;

[0046] 2-1 Proton exchange membrane;

[0047] The other part is the cathode part of the battery: 3-1, cathode catalyst layer; 3-2, cathode diffusion layer; 3-3, cathode reactant flow channel; 3-4, cathode plate; 3-5, cathode cooling water flow channel.

[0048] Figure 3 is the compression amount of the gas diffusion layer corresponding to different assembly pressures.

[0049] Figure 4 Figure 3 is a graph showing the porosity variation of the gas diffusion layer at various locations under different assembly pressures.

[0050] Figure 5 This is a relationship diagram between the current density and output power density of the fuel cell during the discharge process under different assembly pressures. DETAILED DESCRIPTION

[0051] The above scheme is further described below in conjunction with specific implementation examples. The preferred embodiments of the present invention are described in detail as follows:

[0052] Embodiment 1:

[0053] In this embodiment, a multi-physics field coupling simulation analysis method for a fuel cell under a non-homogeneous compression state includes the following steps:

[0054] S1. Construct a proton exchange membrane fuel cell with a semi-channel symmetric model. Under steady-state working conditions, couple the solid mechanics physical field to establish a performance model of the semi-channel symmetric proton exchange membrane fuel cell affected by assembly pressure, and simulate the porosity change and compression displacement change of the gas diffusion layer under inhomogeneous compression;

[0055] Wherein, under non-homogeneous compression, a performance model of the semi-channel symmetric proton exchange membrane fuel cell affected by assembly pressure is established, characterized in that it includes the following steps:

[0056] S101.See Figure 1and Figure 2 , establish a three-dimensional simulation model of a proton exchange membrane fuel cell, the model includes a battery anode part and a battery anode part, and a proton exchange membrane 2-1 arranged between the battery anode part and the battery anode part; the battery anode part includes an anode cooling water channel 1-3, an anode plate 1-4, an anode reactant flow channel 1-1, an anode gas diffusion layer 1-2, and an anode catalyst layer 1-5; the battery anode part includes a cathode catalyst layer 3-1, a cathode diffusion layer 3-2, a cathode reactant flow channel 3-3, a cathode plate 3-4 and a cathode cooling water channel 3-5; wherein the anode diffusion layer 1-2, the anode catalyst layer 1-5, the proton exchange membrane 2-1, the cathode catalyst layer 3-1 and the cathode diffusion layer 3-2 are sequentially combined to form a membrane electrode assembly; in order to reduce the number of finite element calculation units of the three-dimensional simulation model, a symmetric boundary is used in the symmetric domain in the three-dimensional simulation model;

[0057] S102. Add a solid mechanics module to calculate the compression of the gas diffusion layer and the porosity change at each position under different assembly pressure states, and obtain the parameter changes of the gas diffusion layer during inhomogeneous compression;

[0058] S2. Based on the change of gas diffusion layer parameters during heterogeneous compression obtained in step S1, a multi-physics field coupled simulation is performed to establish a proton exchange membrane fuel cell model coupled with multi-physics fields under heterogeneous compression, and calculate the change of battery performance under different pressures;

[0059] Among them, establishing a proton exchange membrane fuel cell model with multi-physics field coupling under inhomogeneous compression includes the following steps:

[0060] S201. Add a series of physical field interfaces including Brinkman equation interface, concentrated species transport interface, and secondary current distribution interface, couple the physical fields to each other, and calculate the reactant flow, reactant transport, and electrochemical reaction in the fuel cell respectively;

[0061] S202. Define the parameters required for the physical field interface of the proton exchange membrane fuel cell, including the assembly pressure, the change of the corresponding physical parameters caused by the change of the porosity calculated in step S1, and the global operating temperature, the physical parameters required for the physical field, the solution variables, the initial values ​​and the boundary conditions;

[0062] S203. Meshing the three-dimensional geometric simulation model of the proton exchange membrane fuel cell using Comsol, performing steady-state solution on the divided three-dimensional simulation model, and obtaining a data set of solution variables of the simulation model;

[0063] S204. Performing visualization post-processing on the work result data set, and completing the numerical simulation of the flow field, mass transfer and electrochemical physical and chemical phenomena of the isothermal steady-state proton exchange membrane fuel cell in a visualization post-processing manner;

[0064] , S3. Combine the solid mechanics heat transfer physical field and the battery performance change results obtained in S2 to calculate the battery heat generation temperature distribution under isothermal working conditions.

[0065] Among them, establishing a proton exchange membrane fuel cell model with multi-physics field coupling under inhomogeneous compression includes the following steps:

[0066] S301. Add solid heat transfer physical field interface to calculate the heat generation temperature field distribution of fuel cell isothermal operation;

[0067] S302. Define the physical property parameters, solution variables, initial values ​​and boundary conditions required for the solid heat transfer physical field interface of the proton exchange membrane fuel cell;

[0068] S303. Couple the simulation results of step S2 and the solid heat transfer physical field interface to calculate the temperature distribution of heat generated under different assembly stresses of the battery.

[0069] The multi-physics coupling simulation and analysis method of the fuel cell under the inhomogeneous compression state of this embodiment establishes a three-dimensional simulation model of a proton exchange membrane fuel cell with semi-channel symmetry, couples the solid mechanics module, and analyzes the compression of the gas diffusion layer and the optimal assembly pressure of the pores under the inhomogeneous compression; then, according to the obtained inhomogeneous porosity of the gas diffusion layer, it is coupled with the secondary current, concentrated material, and Brinkman equation modules to analyze the material flow, mass transfer, electrochemical physical and chemical phenomena of the battery in the isothermal steady state to analyze the optimal assembly pressure under the working state of the battery; then, the simulated data set is coupled with the solid heat transfer module to calculate the temperature field distribution of the battery heat generation and analyze the temperature distribution under the working state of the battery. The method of this embodiment realizes a more comprehensive analysis of the effect of assembly pressure on the mass transfer concentration, velocity field distribution, battery performance and temperature field distribution of the fuel cell under the inhomogeneous compression state. The method of this embodiment adds a solid mechanics module to the proton exchange membrane fuel cell model to describe the influence of assembly stress on the compression and porosity of the fuel cell gas diffusion layer, so as to explore the influence of assembly pressure on the performance of the fuel cell; the simulation analysis method of this embodiment simulates and calculates the material flow field, mass transfer, electrochemical and physical and chemical processes in the heterogeneous compressed proton exchange membrane fuel cell, which can optimize the operating parameters, structural design, and material properties of the proton exchange membrane fuel cell, so that the proton exchange membrane fuel cell has higher performance.

[0070] Embodiment 2

[0071] This embodiment is basically the same as the first embodiment, except that:

[0072] In this embodiment,

[0073] This embodiment establishes a three-dimensional model of multi-physics coupling simulation of a fuel cell under a non-homogeneous compression state based on COMSOL Multiphysics software, then adds the physical field modules that meet the requirements provided by the software, and assigns the physical property parameters, solution variables, initial values ​​and boundary conditions required for each physical field, then divides the three-dimensional geometric model into grids, sets the solution steps of the solver, and finally performs visualization post-processing on the calculated data set. Specifically, the following steps are included:

[0074] (1) Establish a three-dimensional structure diagram of a proton exchange membrane fuel cell, input the corresponding structural parameters of each region, namely, length, height and width, as well as the Poisson's ratio, elastic modulus and Poisson's ratio of the gas diffusion layer; specific regions such as Figure 1 and 2 As shown; the model mainly includes 1-1, anode reactant flow channel; 1-2, anode gas diffusion layer; 1-3, anode cooling water flow channel; 1-4, anode plate; 1-5, anode catalyst layer; 2-1 proton exchange membrane; 3-1, cathode catalyst layer; 3-2, cathode gas diffusion layer; 3-3, cathode reactant flow channel; 3-4, cathode plate; 3-5, cathode cooling water flow channel, one part of which is the anode area, the other part is the cathode area, and the middle part is the proton exchange membrane;

[0075] (2) Add a solid mechanics module to determine relevant parameters such as pressure size, pressure surface, pressure direction, and boundary conditions, and calculate the compression and porosity of the gas diffusion layer caused by the assembly pressure;

[0076] (3) Add secondary current distribution, concentrated material transfer, and Brinkman equation modules to simulate the effects of different assembly stresses on the reactant flow field, mass transfer, and electrochemical reaction inside the fuel cell under isothermal conditions; globally define the physical properties required for the above physical fields, and define the initial values ​​and boundary conditions of each physical field under the required physical field interface;

[0077] (4) Among them, the Brinkman equation is a model that describes mass transfer. For material transfer in the flow channel, the velocity field and pressure field are modeled and solved by the Navier-Stokes equation. For material transfer in the porous gas diffusion layer and the electrode layer, the velocity field and pressure field in the porous medium domain are modeled and solved by the Brinkman equation. The concentrated species transport interface is a model that describes the mass transfer of gas and liquid mixtures with the same order of magnitude of material concentration. The reactant concentrations in the flow channel and porous medium domain are modeled and solved by the Maxwell-Stefan equation. The secondary current module uses the Butler-Volmer equation to couple the reactant concentration and the current size of the electrochemical reaction.

[0078] (5) The calculation results of the solid mechanics module, i.e., the gas diffusion layer compression and the inhomogeneous porosity, are coupled with step (3); wherein the inhomogeneous porosity mainly changes the conductivity, permeability and contact resistance of the gas diffusion layer with the metal bipolar plate. The compression changes as Figure 3 As shown in the figure, the relationship between heterogeneous porosity and assembly pressure is shown in Figure 4 As shown;

[0079] (6) Using the built-in grid division of Comsol, important areas such as the gas diffusion layer and membrane electrode are encrypted, and different areas can be divided into different densities;

[0080] (7) Solving: Visualizing the data set; including Figure 5 The performance curve of the proton exchange membrane fuel cell shown in the figure can also be exported to show the concentration field of reactants and products, velocity field distribution diagrams, and current density distribution of different cross sections, so as to visualize the data to be analyzed.

[0081] (8) After the above simulation is completed, add the solid heat transfer physical field interface, add the physical property parameters required by the physical field, including thermal conductivity, density, constant pressure heat capacity, electrolyte, electrode and pore percentage in the porous domain, and define the initial conditions and boundary conditions of the physical field. Finally, perform simulation calculations and visualize the result data set.

[0082] This embodiment can not only analyze the influence of different assembly pressures on the porosity and deformation of the gas diffusion layer under heterogeneous compression, but also reflect the trend of physical and chemical changes in the fuel cell caused by heterogeneous compression under different assembly pressures. The semi-channel symmetric model used can also reduce the amount of calculation. Finally, it can truly reflect the internal influence of different assembly pressures on the isothermal steady-state operation of the proton exchange membrane fuel cell.

[0083] The specific embodiments described in the above embodiments are merely examples of the spirit of the present invention. A person skilled in the art of the above embodiments of the present invention may make various modifications or additions to the specific embodiments described, or replace them in a similar manner, but they will not deviate from the spirit of the present invention or exceed the scope defined by the attached claims. The above embodiments use the terms "isothermal" and "steady state" only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional limitation is contrary to the spirit of the present invention.

[0084] The above describes the embodiments of the present invention in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes can be made according to the purpose of the invention. Any changes, modifications, substitutions, combinations or simplifications made according to the spirit and principle of the technical solution of the present invention should be equivalent replacement methods. As long as they meet the purpose of the invention and do not deviate from the technical principles and inventive concepts of the present invention, they belong to the protection scope of the present invention.

Claims

1. A multi-physics coupling simulation analysis method for a fuel cell under a non-homogeneous compression state, characterized in that: The following steps are involved: S1. Construct a semi-channel symmetric proton exchange membrane fuel cell model. Under steady-state working conditions, couple the solid mechanics physical field to establish a performance model of the semi-channel symmetric proton exchange membrane fuel cell affected by assembly pressure, and simulate the porosity change and compression displacement change of the gas diffusion layer under inhomogeneous compression; S2. According to the change of the gas diffusion layer parameters during the heterogeneous compression obtained in step S1, a multi-physics field coupled simulation is performed to establish a proton exchange membrane fuel cell model coupled with multi-physics fields under heterogeneous compression, and calculate the change of battery performance under different pressures; S3. Combining the solid mechanics heat transfer physical field and the battery performance change results obtained in S2, calculate the battery heat generation temperature distribution under isothermal working conditions; In the step S1, under non-homogeneous compression, a performance model of the semi-channel symmetric proton exchange membrane fuel cell is established in which the assembly pressure affects the performance of the semi-channel symmetric proton exchange membrane fuel cell, characterized in that it includes the following steps: S101. Establishing a three-dimensional simulation model of a proton exchange membrane fuel cell, the model comprising a battery anode part and a battery cathode part, and a proton exchange membrane (2-1) disposed between the battery anode part and the battery cathode part; the battery anode part comprises an anode cooling water flow channel (1-3), an anode plate (1-4), an anode reactant flow channel (1-1), an anode gas diffusion layer (1-2), and an anode catalyst layer (1-5); the battery anode part comprises a cathode catalyst layer (3-1), a cathode diffusion layer (3-2), a cathode reactant flow channel (3-3), a cathode plate (3-4), and a cathode cooling water flow channel (3-5); wherein the anode diffusion layer (1-2), the anode catalyst layer (1-5), the proton exchange membrane (2-1), the cathode catalyst layer (3-1), and the cathode diffusion layer (3-2) are sequentially combined to form a membrane electrode assembly; in order to reduce the number of finite element calculation units of the three-dimensional simulation model, a symmetric boundary is used in the symmetric domain in the three-dimensional simulation model; S102. Add a solid mechanics module to calculate the compression of the gas diffusion layer and the porosity change at each position under different assembly pressure states, and obtain the parameter changes of the gas diffusion layer during inhomogeneous compression; In the step S2, a proton exchange membrane fuel cell model with multi-physical field coupling under heterogeneous compression is established, comprising the following steps: S201. Add a series of physical field interfaces including Brinkman equation interface, concentrated species transport interface, and secondary current distribution interface, couple the physical fields to each other, and calculate the reactant flow, reactant transport, and electrochemical reaction in the fuel cell respectively; S202. Defining the parameters required for the physical field interface of the proton exchange membrane fuel cell, including the assembly pressure, the change of the corresponding physical parameters caused by the change of the porosity calculated in step S1, and the global operating temperature, the physical parameters required for the physical field, the solution variables, the initial values ​​and the boundary conditions; S203. Meshing the three-dimensional geometric simulation model of the proton exchange membrane fuel cell using comsol, performing a steady-state solution on the divided three-dimensional simulation model to obtain a data set of solution variables for the simulation model; S204. Performing visualization post-processing on the work result data set, and completing the numerical simulation of the flow field, mass transfer and electrochemical physical and chemical phenomena of the isothermal steady-state proton exchange membrane fuel cell in the visualization post-processing manner; In step S3, the heat transfer physical field of solid mechanics and the battery performance change result obtained in step S2 are combined to calculate the heat generation temperature distribution of the battery under isothermal working conditions, including the following steps: S301. Add the solid heat transfer physics interface to calculate the heat generation temperature field distribution of the fuel cell isothermal operation; S302. Define the physical parameters, solution variables, initial values ​​and boundary conditions required for the solid heat transfer physical field interface of the proton exchange membrane fuel cell; S303. Coupling the simulation result of step S2 and the solid heat transfer physical field interface, calculate the temperature distribution of heat generated under different assembly stresses of the battery.

2. The multi-physical field coupling simulation analysis method for a fuel cell under a non-homogeneous compression state according to claim 1, characterized in that: The Brinkman Equations interface uses the Porous Media Species Transfer Module to simulate mass transfer in a proton exchange membrane fuel cell, including momentum transfer and diffusion of the reactants hydrogen and oxygen and the product water, acting on the anode portion of the cell and the flow channels, gas diffusion layer, and catalyst layer of the anode portion of the cell, thereby obtaining the velocity and pressure distribution of the reactants, coupled with the Concentrated Species Transport interface.

3. The multi-physical field coupling simulation analysis method for a fuel cell under a non-homogeneous compression state according to claim 1, characterized in that: The Transport of Concentrated Species interface is used to describe the concentration distribution of the anode and cathode reactants in each effective domain.

4. The multi-physical field coupling simulation analysis method for a fuel cell under a non-homogeneous compression state according to claim 1, characterized in that: The mutual coupling between physical fields refers to the calculation of the convective mass transfer flux of the corresponding domain by using the velocity or pressure of the Brinkman equation interface physical field of the corresponding domain.

5. The multi-physical field coupling simulation analysis method for a fuel cell under a non-homogeneous compression state according to claim 1, characterized in that: For the secondary current distribution interface, the secondary current distribution module is used to simulate the charge transfer process in the proton exchange membrane fuel cell, acting on the proton exchange membrane and the gas diffusion layer and catalyst layer of the battery anode part. The secondary current distribution module can calculate the electrode current density distribution and membrane current density distribution, and analyze the potential, electric potential and current trend.

6. The multi-physical field coupling simulation analysis method for a fuel cell under a non-homogeneous compression state according to claim 1, characterized in that: Solid heat transfer physics is used to describe the temperature field distribution of heat generation in isothermal proton exchange membrane fuel cells. The solid heat transfer physics is coupled with the total power consumption density in the simulation results of the secondary current distribution physics field to calculate the temperature distribution of the solid heat transfer physics field.

7. The multi-physical field coupling simulation analysis method for a fuel cell under a non-homogeneous compression state according to claim 1, characterized in that: When adding the Solid Heat Transfer physics interface, the physical property parameters required to add this physics field mainly include thermal conductivity, density, constant pressure heat capacity, electrolyte, electrode and pore percentage parameters of the porous domain.

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