Optimization Method for the Flow Channels of SOFC Bipolar Plates Based on Mesoscopic Precise Three-Dimensional Reconstruction

Abstract

The present invention provides an optimization method for the flow channels of the SOFC bipolar plate based on mesoscopic precise three-dimensional reconstruction, belonging to the new energy technology field of solid oxide fuel cells, and includes: establishing a multi-physical field coupling model of SOFC fluid-diffusion-electrochemistry; constructing and verifying an equivalent two-dimensional topology optimization model; improving the consumption topology optimization method based on the SOFC multi-physical field model; performing electrochemical performance calculation and comparative verification on the flow channel structure obtained by topology optimization; and analyzing the optimization results. The present invention integrates the above steps into an independently developed MATLAB main program, realizes finite element theoretical modeling with the help of COMSOL, so as to obtain the consumption of the flow channels in different regions; by correcting the topology optimization material density in MATLAB, the update of the gas consumption in the region during each iteration is realized, improving the overall electrochemical performance of the SOFC, which has important significance for relevant academic research and practical engineering applications.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy of solid oxide fuel cells, and particularly to an optimization method for the flow channels of SOFC bipolar plates based on mesoscopic precise three-dimensional reconstruction. Background Art

[0002] A solid oxide fuel cell is a high-efficiency energy conversion device that directly converts the chemical energy of fuel into electrical energy and has received extensive attention in recent years. In industrial applications, SOFCs are usually assembled into a fuel cell stack to meet the voltage and power requirements in practical applications. Traditional planar SOFC fuel cell stacks are composed of bipolar plates that are sandwiched on both sides of a single cell for gas transportation and current collection. The flow field design in the bipolar plates has an important impact on the performance of the fuel cell stack. To optimize the performance of SOFC fuel cell stacks in industrial applications, researchers have extensively studied the influence of the flow field on SOFC performance.

[0003] Topological optimization is a method that obtains the optimal solution of the design objective equation through constraint equations. Common optimization methods include density-based methods, level set methods, and phase field methods. Among these methods, the density-based topological optimization method is widely used because of its simple interpolation form and characteristics convenient for sensitivity analysis. This method was first proposed by Bendsøe and Kikuchi and was initially used for structural design. Since then, researchers have extended the application of this method to fields such as heat transfer, fluid dynamics, and acoustics.

[0004] Currently, there is an urgent need to establish a numerical simulation method for flow field optimization based on the real microstructure of SOFCs to optimize the cathode flow channel structure of SOFC fuel cell stacks. However, no researcher has been able to systematically carry out research on the optimization of SOFC flow channel structures by using finite element technology and combining the gas consumption in the flow channels under a specific current density. The main reasons are the following challenges faced in the simulation process: (1) the establishment of a three-dimensional macroscopic homogeneous multi-physics field coupling model based on the real microstructure of SOFCs; (2) combining the consumption in different regions of the variable density method with the actual gas consumption through unit density correction. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the present invention proposes an optimization method for the flow channels of SOFC bipolar plates based on mesoscopic precise three-dimensional reconstruction, aiming to achieve precise design and optimization of the flow channel structure through the coupled modeling of fluid-diffusion-electrochemistry multi-physics fields and topological optimization, and calculating and optimizing the gas consumption distribution in different regions through an improved topological optimization method, thereby improving the electrochemical performance of SOFCs, enhancing the efficiency and reliability of the SOFC system, and providing important technical support for academic research and practical engineering applications in related fields.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] An optimization method for the flow channel of a SOFC bipolar plate based on mesoscopic precise three-dimensional reconstruction, comprising the following steps:

[0008] Establish a three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physical field coupling model of SOFC;

[0009] Based on the depth-averaging method, simplify the three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physical field coupling model of SOFC into an equivalent two-dimensional topology optimization model, and use the solid isotropic material penalization method for material property interpolation to provide parameters for subsequent topology optimization;

[0010] Based on the equivalent two-dimensional topology optimization model, define the gas consumption source term by the element density, and adjust the source term distribution in the rib region through the interpolation function to ensure the accurate introduction and consumption of gas, and obtain different topology optimization flow channel structures;

[0011] Calculate and compare and verify the electrochemical performance of the different topology optimization flow channel structures to obtain multiple groups of electrochemical performance data;

[0012] Based on the multiple groups of electrochemical performance data, analyze the performance of the different topology optimization flow channel structures to reveal the influence of different topology optimization flow channel structures on the performance of the SOFC battery.

[0013] Preferably, use COMSOL finite element software to construct the three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physical field coupling model, including:

[0014] Use the Brinkman equation to simulate the fluid field in the flow channel and the porous electrode, and the formula is:

[0015] ;

[0016] ;

[0017] In the formula, is the gas density, is the velocity vector, is the gas mass source, is the pressure, is the unit matrix, T is the transpose symbol of the matrix, and respectively represent the porosity and permeability of the electrode, is the viscosity of the mixed gas;

[0018] Use the diffusion control equation to simulate the diffusion behavior of the mixed gas in the anode or cathode:

[0019] ;

[0020] Wherein, is the gas consumption, is the total reaction current, F is the Faraday constant, and are the effective diffusion coefficient and concentration of component , where the effective diffusion coefficient is defined as:

[0021] ;

[0022] Wherein, is the tortuosity factor, is the porosity of component , is the volume fraction of component , , is the binary diffusion coefficient, is the Knudsen diffusion coefficient; wherein, the binary diffusion coefficient and the Knudsen diffusion coefficient are defined respectively as:

[0023] ;

[0024] ;

[0025] Wherein, T is the operating temperature, R is the gas constant, is the average pore radius, is the gas molar mass, is the intermolecular force constant, is the collision volume of molecular diffusion;

[0026] The charge and ion conduction are calculated using the control equations:

[0027] ;

[0028] ;

[0029] Wherein, is the electron conductivity, is the electrochemical potential of electrons, is the oxygen ion conductivity, is the electrochemical potential of oxygen ions, is the reaction current, is the Faraday constant;

[0030] The Butler-Volmer equation is used to calculate the electrochemical reaction current densities of the anode and cathode.

[0031] Preferably, based on the depth-averaging method, the three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physics field coupling model of the SOFC is simplified into an equivalent two-dimensional topology optimization model, and the solid isotropic material with penalty method is used for material property interpolation to provide parameters for subsequent topology optimization, including:

[0032] Using the depth-averaging method, the three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physics field coupling model of the SOFC is simplified into an equivalent two-dimensional topology optimization model;

[0033] Interpolate the diffusion coefficient, porosity, and permeability of the porous phase using the solid isotropic material with penalty method SIMP;

[0034] Define the objective equation of topology optimization. With the total current density fixed, minimize the total gas consumption by adjusting the layouts of the porous electrodes, flow channels, equivalent channels, and equivalent ribs.

[0035] Preferably, using the depth-averaging method, the three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physics field coupling model of the SOFC is simplified into an equivalent two-dimensional topology optimization model. The specific governing equations are:

[0036] ;

[0037] In the formula, is the average property of the equivalent porous electrode, is the depth, and the subscripts "pe", "fc", "ec", and "er" are the porous electrode, flow channel, equivalent channel, and equivalent rib, respectively.

[0038] Preferably, use the solid isotropic material with penalty method SIMP to interpolate the diffusion coefficient, porosity, and permeability of the porous phase. The interpolation equations are:

[0039] ;

[0040] ;

[0041] ;

[0042] In the formula, is the penalty factor, , and are the two-dimensional equivalent values of the diffusion coefficient, porosity, and permeability, respectively, D , and They are the diffusion coefficient, porosity, and permeability of the electrode, respectively.

[0043] Preferably, the objective equation for the topology optimization is:

[0044] ;

[0045] In the formula, is the optimization region, is the inlet boundary, is the volume fraction.

[0046] Preferably, based on the equivalent two-dimensional topology optimization model, the gas consumption source term is defined by the element density, and the source term distribution in the rib region is adjusted through an interpolation function to ensure the uniform introduction and consumption of gas, and different topology-optimized flow channel structures are obtained, including:

[0047] First, use interpolation to describe the variation of the source term amplitude at the ribs and match it with the actual gas consumption rate; then introduce a linearly decreasing material density parameter within the scale range of half the rib width to accurately represent the transient distribution of gas consumption; finally, use a double Gaussian fitting function to reproduce the distribution of the normalized source term to obtain different topology-optimized flow channel structures;

[0048] Among them, the double Gaussian fitting function is:

[0049] ;

[0050] In the formula, are all fitting parameters, is the linearly decreasing material density parameter.

[0051] Preferably, calculate and compare the electrochemical performances of the different topology-optimized flow channel structures to obtain multiple sets of electrochemical performance data, including:

[0052] First, through the variable density topology optimization method, maximize the gas concentration in the overall region of the SOFC as the optimization goal to obtain the topology-optimized structure of the SOFC battery stack; then correct the relationship between the element density and the consumption term in different regions to further optimize the flow channel structure; finally, calculate the different topology-optimized flow channel structures and conduct a comparative analysis of the electrochemical performances with the traditional parallel flow channel structure to obtain multiple sets of electrochemical performance data.

[0053] Preferably, analyze the performances of the different topology-optimized flow channel structures by integrating the multiple sets of electrochemical performance data to determine the influence of the different topology-optimized flow channel structures on the SOFC battery performance, including:

[0054] According to the multi - group of electrochemical performance data, analyze the current - voltage relationship under different topological flow channel structures, and analyze the influence of different topological flow channel structures on the over - potential and gas diffusion of SOFC.

[0055] Compared with the prior art according to the specific technical solution provided by the present invention, the present invention discloses the following technical effects:

[0056] (1) Precise multi - physical - field coupling modeling: The present invention uses the coupling modeling of fluid, diffusion, and electrochemistry multi - physical fields to accurately simulate the gas transport and electrochemical reaction processes in the flow channel, ensuring the accuracy of the model and providing reliability for the basis of optimization design.

[0057] (2) Topological optimization method correction: The present invention proposes an improved topological optimization algorithm. By correcting the relationship between material density and gas consumption in each iteration, a more efficient optimization process is achieved. Compared with the traditional method, this optimization method has an accurate correlation between gas consumption under ribs and actual consumption, and can optimize the bipolar plate ribs more accurately.

[0058] (3) Improve electrochemical performance: Through the flow channel structure design based on the variable - density topological optimization method, the present invention can optimize the distribution of gas consumption, thereby reducing the gas concentration difference and enhancing the overall electrochemical performance of SOFC. Compared with the traditional design, the optimized flow channel structure can provide a higher current density and power under the same conditions. Brief Description of the Drawings

[0059] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0060] Figure 1 It is a flowchart provided for an optimization method of an SOFC bipolar plate flow channel based on mesoscopic precise three - dimensional reconstruction of the present invention;

[0061] Figure 2 It is a single - flow - channel modeling schematic diagram and model provided for Embodiment 1 of the present invention I-V Curve verification graph;

[0062] Figure 3 It is a unit density correction schematic diagram provided for Embodiment 1 of the present invention; among them, Figure 3 (a) in it is a material density correction schematic diagram, Figure 3 (b) in it is a normalized gas consumption curve graph from the flow channel to the ribs under different current densities;

[0063] Figure 4 This is the topological optimization flow channel structure and comparison result diagram provided in the first embodiment of the present invention; among them, Figure 4 in (a) is the schematic diagram of the parallel flow channel and topological optimization modeling, Figure 4 in (b) is the velocity field comparison diagram, Figure 4 in (c) is when the current density is 0.6 A cm 2 for O 2 concentration comparison diagram, Figure 4 in (d) is when the current density is 0.6 A cm 2 for ion current density comparison diagram, Figure 4 in (e) is between different flow channel structures I-V curve comparison diagram. Specific implementation manner

[0064] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0065] To make the purpose, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0066] Embodiment 1

[0067] Referring to Figure 1 , this embodiment provides an optimization method for the SOFC bipolar plate flow channel based on mesoscopic accurate three-dimensional reconstruction, including the following steps:

[0068] Step 100: Establish a three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physical field coupling model for SOFC;

[0069] Step 200: Based on the depth-averaging method, simplify the three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physical field coupling model of SOFC into an equivalent two-dimensional topological optimization model, and use the solid isotropic material penalization method for material property interpolation to provide parameters for subsequent topological optimization;

[0070] Step 300: Based on the equivalent two-dimensional topological optimization model, use the unit density to define the gas consumption source term, and adjust the source term distribution in the rib region through the interpolation function to ensure the accurate introduction and consumption of gas, and obtain different topological optimization flow channel structures;

[0071] Step 400: Calculate and compare and verify the electrochemical performance of the different topological optimization flow channel structures to obtain multiple sets of electrochemical performance data;

[0072] Step 500: Analyze the performance of the different topologically optimized flow channel structures by synthesizing the multiple sets of electrochemical performance data, and reveal the influence of different topologically optimized flow channel structures on the performance of the SOFC cell.

[0073] In this embodiment, a single flow channel structure with a length of 5.85 cm is selected for simulation, and the width and height of the flow channel are both 1 mm. The preliminary work includes the establishment of a physical model, and the use of commercial finite element software for modeling and solving, as Figure 2 shown.

[0074] The specific steps in this embodiment include the following:

[0075] Use COMSOL finite element software to construct the three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physics coupling model, including:

[0076] Use the Brinkman equation to simulate the fluid field in the flow channel and the porous electrode. The formula is:

[0077] ;

[0078] ;

[0079] In the formula, is the gas density, is the velocity vector, is the gas mass source, is the pressure, is the unit matrix, T is the transpose symbol of the matrix, and respectively represent the porosity and permeability of the electrode, is the viscosity of the mixed gas;

[0080] Use the diffusion control equation to simulate the diffusion behavior of the mixed gas in the anode or cathode:

[0081] ;

[0082] In the formula, is the gas consumption, is the total reaction current, F is the Faraday constant, and are the effective diffusion coefficient and concentration of component , where the effective diffusion coefficient is defined as:

[0083] ;

[0084] In the formula， is the tortuosity factor, is the porosity of component ; is the volume fraction of component ; , is the binary diffusion coefficient, is the Knudsen diffusion coefficient; wherein, the binary diffusion coefficient and the Knudsen diffusion coefficient are respectively defined as:

[0085] ;

[0086] ;

[0087] In the formula, T is the operating temperature, R is the gas constant, is the average pore radius, is the gas molar mass, is the intermolecular force constant, is the collision volume of molecular diffusion;

[0088] The charge and ion conduction are calculated using the control equations of electrons and ions:

[0089] ;

[0090] ;

[0091] In the formula, is the electron conductivity, is the electrochemical potential of electrons, is the oxygen ion conductivity, is the electrochemical potential of oxygen ions, is the reaction current, is the Faraday constant;

[0092] The Butler-Volmer equation is used to calculate the electrochemical reaction current density of the anode and cathode, including:

[0093] In this embodiment, for the electrochemical reaction sites of the anode, it is assumed to be the Ni / YSZ / Pore triple-phase boundary TPBs;

[0094] And in this embodiment, for the electrochemical reaction sites of the cathode, it is assumed that the electrochemical reaction occurs simultaneously at the dual-phase boundary DPBs and the TPB of

[0095] Therefore, the total electrochemical reaction current density at the TPB / DPB is calculated by the Butler-Volmer equation, and the relevant exchange current density is defined by an empirical equation. Both the local activation overpotential and the concentration overpotential are considered in the modeling. The corresponding equations are summarized in Table 1 below.

[0096] Table 1 Electrochemical reaction expression equations

[0097] ;

[0098] Specifically, based on the depth-averaging method, the three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physics field coupling model of the SOFC is simplified to an equivalent two-dimensional topology optimization model, and the solid isotropic material penalization (SIMP) method is used for material property interpolation to provide parameters for subsequent topology optimization, including:

[0099] Using the depth-averaging method, the three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physics field coupling model of the SOFC is simplified to an equivalent two-dimensional topology optimization model;

[0100] Interpolating the diffusion coefficient, porosity, and permeability of the porous phase using the solid isotropic material penalization (SIMP) method;

[0101] Defining the objective equation for topology optimization, and minimizing the total gas consumption by adjusting the layouts of the porous electrodes, flow channels, equivalent channels, and equivalent ribs under the condition of a fixed total current density.

[0102] Specifically, using the depth-averaging method, the three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physics field coupling model of the SOFC is simplified to an equivalent two-dimensional topology optimization model, and the specific governing equations are:

[0103] ;

[0104] where is the average property of the equivalent porous electrode, is the depth, and the subscripts "pe", "fc", "ec", and "er" are the porous electrode, flow channel, equivalent channel, and equivalent rib, respectively.

[0105] Specifically, interpolating the diffusion coefficient, porosity, and permeability of the porous phase using the solid isotropic material penalization (SIMP) method, and the interpolation equations are:

[0106] ;

[0107] ;

[0108] ;

[0109] where is the penalty factor, 、 and are the two-dimensional equivalent values of the diffusion coefficient, porosity, and permeability, respectively, D , and are the diffusion coefficient, porosity, and permeability of the electrode, respectively.

[0110] The objective equation of the topological optimization is:

[0111] ;

[0112] In the formula, is the optimization region, is the inlet boundary, is the volume fraction.

[0113] Specifically, based on the equivalent two-dimensional topological optimization model, the gas consumption source term is defined by the element density, and the source term distribution in the rib region is adjusted through the interpolation function to ensure the accurate introduction and consumption of gas, and different topological optimization flow channel structures are obtained, including:

[0114] First, the interpolation is used to describe the change in the source term amplitude at the ribs and match it with the actual gas consumption rate; then a linearly decreasing material density parameter is introduced within the scale range of half the rib width to accurately express the transient distribution of gas consumption, as shown in (a) of Figure 3 ; finally, the double Gaussian fitting function is used to reproduce the distribution of the normalized source term to obtain different topological optimization flow channel structures;

[0115] Among them, the double Gaussian fitting function is:

[0116] ;

[0117] In the formula, are all fitting parameters, is the linearly decreasing material density parameter.

[0118] Referring to Figure 3 the normalized gas consumption curve from the flow channel to the ribs at different current densities in (b), it can be intuitively found that the gas consumption source term is defined by the element density and the source term distribution in the rib region is adjusted through the interpolation function, realizing the accurate introduction and consumption of gas.

[0119] Specifically, the electrochemical performance of the different topological optimization flow channel structures is calculated and compared for verification to obtain multiple sets of electrochemical performance data, including:

[0120] First, through the variable density topology optimization method, the maximization of the gas concentration in the overall area of the SOFC is taken as the optimization goal to obtain the topology optimization structure of the SOFC stack; then, the relationship between the unit density and the consumption term in different regions is corrected to further optimize the flow channel structure; finally, different topology optimization flow channel structures are calculated, and the electrochemical performance is compared and analyzed with the traditional parallel flow channel structure to obtain multiple sets of electrochemical performance data, and the results are as Figure 4 shown. According to Figure 4 , the modeling diagram provided in (a) shows that the electrochemical performance is significantly improved by optimizing the flow channel structure of the SOFC. And according to Figure 4 , the results in (b), (c) and (d) show that the optimized layout makes the oxygen concentration and ion current density distribution more uniform, and achieves a higher gas transmission efficiency. In addition, according to Figure 4 , the I-V curve provided in (e) shows that the optimized flow channel structure significantly improves the battery performance.

[0121] Specifically, based on the above-mentioned multiple sets of electrochemical performance data, the performance of the different topology optimization flow channel structures is analyzed to reveal the influence of different topology optimization flow channel structures on the SOFC battery performance, including:

[0122] Based on the above-mentioned multiple sets of electrochemical performance data, the current-voltage relationship under different topology flow channel structures is analyzed, and the influence of different topology flow channel structures on the overpotential and gas diffusion of the SOFC is analyzed.

[0123] Therefore, by adopting the above-mentioned optimization method for the SOFC bipolar plate flow channel based on mesoscopic accurate three-dimensional reconstruction, aiming at the precise design and optimization of the flow channel structure through the coupled modeling and topology optimization of fluid-diffusion-electrochemistry multi-physical fields, and calculating and optimizing the gas consumption distribution in different regions through the improved topology optimization method, the electrochemical performance of the SOFC is improved, thereby improving the efficiency and reliability of the SOFC system, providing important technical support for academic research and practical engineering applications in related fields.

[0124] In this article, specific examples are used to elaborate on the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation mode and application scope. To sum up, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A method for optimizing the flow channel of a SOFC bipolar plate based on mesoscopic accurate three-dimensional reconstruction, characterized in that: The following steps are involved: Establishing a three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physics field coupling model for SOFC; using COMSOL finite element software to construct the three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physics field coupling model, including: The Brinkman equation is used to simulate the fluid field in the flow channel and the porous electrode. The formula is: ； ； In the formula, is the gas density, is the velocity vector, is the gas mass source, For pressure, is the identity matrix, is the transpose symbol of the matrix, and represent the porosity and permeability of the electrode, respectively. is the viscosity of the mixed gas; The diffusion control equation is used to simulate the diffusion behavior of the mixed gas in the anode or cathode: ； In the formula, is the gas consumption, is the total reaction current, is the Faraday constant, and For components The effective diffusion coefficient and concentration of is defined as: ； In the formula, is the tortuosity factor, For components The porosity, For components The volume fraction of , is the binary diffusion coefficient, is the Knudsen diffusion coefficient; where the binary diffusion coefficient and the Knudsen diffusion coefficient The definitions are: ； ； In the formula, is the operating temperature, is the gas constant, is the average pore radius, For work pressure, For gas The molar mass of is the intermolecular force constant, is the collision volume for molecular diffusion; The conduction of charges and ions is calculated using the governing equations: ； ； In the formula, is the conductivity of electrons, is the electrochemical potential of electrons, is the conductivity of oxygen ions, is the electrochemical potential of oxygen ions, is the reaction current, is the current in the opposite direction to the reaction current, is the Faraday constant; The Butler-Volmer equation was used to calculate the electrochemical reaction current density at the anode and cathode; Based on the depth averaging method, the SOFC three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physics field coupling model is simplified into an equivalent two-dimensional topology optimization model, and the solid isotropic material penalty method is used to interpolate material properties to provide parameters for subsequent topology optimization; Based on the equivalent two-dimensional topology optimization model, the gas consumption source term is defined by using the unit density, and the source term distribution in the rib area is adjusted by the interpolation function to ensure the accurate introduction and consumption of the gas, thereby obtaining different topology optimized flow channel structures; Calculating and comparing the electrochemical performance of the different topology optimized flow channel structures to obtain multiple sets of electrochemical performance data; The multiple groups of electrochemical performance data are integrated to analyze the performance of the different topology optimized flow channel structures, revealing the effects of different topology optimized flow channel structures on the performance of SOFC cells.

2. The method for optimizing the flow channel of a SOFC bipolar plate based on mesoscopic accurate three-dimensional reconstruction according to claim 1, characterized in that: Based on the depth averaging method, the SOFC three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physics field coupling model is simplified to an equivalent two-dimensional topology optimization model, and the solid isotropic material penalty method is used to interpolate material properties to provide parameters for subsequent topology optimization, including: The SOFC three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physics field coupling model is simplified into an equivalent two-dimensional topology optimization model by using a depth averaging method; The diffusion coefficient, porosity and permeability of the porous phase are interpolated using the solid isotropic material penalty method SIMP. The objective equation of topology optimization is defined to minimize the total gas consumption by adjusting the layout of porous electrodes, flow channels, equivalent channels, and equivalent ribs when the total current density is fixed.

3. The method for optimizing the flow channel of a SOFC bipolar plate based on mesoscopic accurate three-dimensional reconstruction according to claim 2, characterized in that: The depth averaging method is used to simplify the SOFC three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physics field coupling model into an equivalent two-dimensional topology optimization model. The specific control equation is: ； In the formula, is the average characteristic of the equivalent porous electrode, is the depth, and the subscripts "pe", "fc", "ec" and "er" represent the porous electrode, flow channel, equivalent channel and equivalent rib, respectively.

4. The method for optimizing the flow channel of a SOFC bipolar plate based on mesoscopic accurate three-dimensional reconstruction according to claim 3, characterized in that: The solid isotropic material penalty method SIMP is used to interpolate the diffusion coefficient, porosity and permeability of the porous phase. The interpolation equation is: ； ； ； In the formula, is the penalty factor, is the cell density, , and are the two-dimensional equivalent values ​​of diffusion coefficient, porosity and permeability, respectively. , and are the diffusion coefficient, porosity and permeability of the electrode, respectively. is the diffusion coefficient of the equivalent rib, is the diffusion coefficient of the equivalent channel, is the porosity of the equivalent rib, is the porosity of the equivalent channel, is the permeability of the equivalent rib, is the permeability of the equivalent channel.

5. The method for optimizing the flow channel of a SOFC bipolar plate based on mesoscopic accurate three-dimensional reconstruction according to claim 4, characterized in that: The objective equation of the topology optimization is: ； In the formula, To optimize the area, is the entrance boundary, is the volume fraction, is the cell density, For pressure, To constrain pressure, Indicates pressure At the entrance boundary The line integral on , N are discrete points in the computational domain.

6. The method for optimizing the flow channel of a SOFC bipolar plate based on mesoscopic accurate three-dimensional reconstruction according to claim 1, characterized in that: Based on the equivalent two-dimensional topology optimization model, the gas consumption source term is defined by unit density, and the source term distribution in the rib area is adjusted by the interpolation function to ensure uniform introduction and consumption of gas, and different topology optimized flow channel structures are obtained, including: Firstly, interpolation is used to describe the change of the source term amplitude at the ribs and match it with the actual gas consumption rate. Then, a linearly decreasing material density parameter is introduced within the scale range of half the rib width to accurately express the transient distribution of gas consumption. Finally, a double Gaussian fitting function is used to reproduce the distribution of the normalized source term and obtain different topological optimized flow channel structures. Among them, the double Gaussian fitting function is: ； In the formula, are fitting parameters, is a linearly decreasing material density parameter.

7. The method for optimizing the flow channel of a SOFC bipolar plate based on mesoscopic accurate three-dimensional reconstruction according to claim 1, characterized in that: The electrochemical performance of the different topology optimized flow channel structures is calculated and compared to obtain multiple sets of electrochemical performance data, including: Firstly, through the variable density topology optimization method, the maximization of the gas concentration in the overall area of ​​SOFC is taken as the optimization goal to obtain the topological optimization structure of the SOFC battery stack; then, the relationship between the unit density and consumption items in different areas is corrected to further optimize the flow channel structure; finally, different topological optimized flow channel structures are calculated, and the electrochemical performance is compared and analyzed with the traditional parallel flow channel structure to obtain multiple sets of electrochemical performance data.

8. The method for optimizing the flow channel of a SOFC bipolar plate based on mesoscopic accurate three-dimensional reconstruction according to claim 1, characterized in that: The multiple groups of electrochemical performance data are integrated to analyze the performance of the different topology optimized flow channel structures to determine the effects of different topology optimized flow channel structures on the performance of the SOFC battery, including: According to the multiple sets of electrochemical performance data, the current-voltage relationship under different topological flow channel structures is analyzed, and the influence of different topological flow channel structures on SOFC overpotential and gas diffusion is analyzed.

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