SOFC bipolar plate flow channel optimization method based on mesoscopic precise three-dimensional reconstruction

Abstract

The invention provides an SOFC bipolar plate flow channel optimization method based on mesoscopic precise three-dimensional reconstruction, and belongs to the technical field of solid oxide fuel cell new energy, and the SOFC bipolar plate flow channel optimization method comprises the following steps: establishing an SOFC fluid-diffusion-electrochemical multi-physics field coupling model; constructing and verifying an equivalent two-dimensional topological optimization model; improving a consumption topological optimization method based on the SOFC multi-physics field model; performing electrochemical performance calculation and comparison verification on the flow channel structure obtained by topological optimization; and analyzing an optimization result. According to the method, the steps are integrated in a self-developed MATLAB main program, finite element theoretical modeling is achieved by means of COMSOL, and therefore the consumption of the runners in different areas is obtained; according to the method, the topological optimization material density is corrected in MATLAB, so that the gas consumption in a region in each iteration process is updated, the electrochemical performance of the whole SOFC is improved, and the method is of great significance to related academic research and practical engineering application.

Description

Technical Field

[0001] The invention relates to the field of solid oxide fuel cell new energy technology, and in particular to a method for optimizing a SOFC bipolar plate flow channel based on mesoscopic precise three-dimensional reconstruction. Background Art

[0002] Solid oxide fuel cells are highly efficient energy conversion devices that directly convert the chemical energy of fuel into electrical energy, and have received widespread attention in recent years. In industrial applications, SOFCs are usually assembled into cell stacks to meet the voltage and power requirements in practical applications. Traditional planar SOFC cell stacks consist of bipolar plates that are sandwiched on both sides of a single cell for gas transport and current collection. The flow field design in the bipolar plates has an important influence on the performance of the cell stack. In order to optimize the performance of SOFC cell stacks in industrial applications, researchers have conducted extensive studies on the effect of flow field on SOFC performance.

[0003] Topology optimization is a method that uses constraint equations to obtain the optimal solution to the design objective equation. Common optimization methods include density-based methods, level set methods, and phase field methods. Among these methods, density-based topology optimization methods are widely used because of their simple interpolation form and the characteristics of being easy to perform sensitivity analysis. This method was first proposed by Bendsøe and Kikuchi and was originally used for structural design. Since then, researchers have extended this method to fields such as heat transfer, fluid dynamics, and acoustics.

[0004] At present, there is an urgent need to establish a numerical simulation method for flow field optimization based on the real microstructure of SOFC to optimize the cathode flow channel structure of SOFC battery stack. However, no researcher has been able to use finite element technology to systematically carry out SOFC flow channel structure optimization research in combination with flow channel gas consumption under specific current density. The main reason is that the simulation process faces the following challenges: (1) Establishment of a three-dimensional macroscopic homogeneous multi-physics field coupling model based on the real microstructure of SOFC; (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 shortcomings of the prior art, the present invention proposes an optimization method for SOFC bipolar plate flow channels based on mesoscopic precise three-dimensional reconstruction, aiming to achieve precise design and optimization of the flow channel structure through coupled modeling and topological optimization of fluid-diffusion-electrochemical multi-physical fields, and calculate and optimize the gas consumption distribution in different areas through an improved topological optimization method, thereby improving the electrochemical performance of SOFC, thereby improving 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: A method for optimizing a SOFC bipolar plate flow channel based on mesoscopic accurate three-dimensional reconstruction comprises the following steps: Establish a three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physics field coupling model for SOFC; 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.

[0007] Preferably, the three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physics field coupling model is constructed using COMSOL finite element software, 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, T 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, F 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, T is the operating temperature, R is the gas constant, is the average pore radius, 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 Faraday constant; The Butler-Volmer equation was used to calculate the electrochemical reaction current density at the anode and cathode.

[0008] Preferably, 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.

[0009] Preferably, 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, and 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.

[0010] Preferably, the diffusion coefficient, porosity and permeability of the porous phase are interpolated using the solid isotropic material penalty method SIMP, and the interpolation equation is: ; ; ; In the formula, is the penalty factor, , and are the two-dimensional equivalent values ​​of diffusion coefficient, porosity and permeability, respectively. D , and are the diffusion coefficient, porosity and permeability of the electrode, respectively.

[0011] Preferably, the objective equation of topology optimization is: ; In the formula, To optimize the area, is the entrance boundary, is the volume fraction.

[0012] Preferably, 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 uniform introduction and consumption of the gas, thereby obtaining different topology optimized flow channel structures, 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.

[0013] Preferably, 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.

[0014] Preferably, the multiple groups of electrochemical performance data are integrated to analyze the performance of the different topology optimized flow channel structures to determine the influence of different topology optimized flow channel structures on the performance of the SOFC cell, 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.

[0015] According to the specific technical solution provided by the present invention, compared with the prior art, the present invention discloses the following technical effects: (1) Accurate multi-physics coupling modeling: The present invention uses the coupling modeling of fluid, diffusion and electrochemical multi-physics 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 optimization design basis.

[0016] (2) Modification of topology optimization method: The present invention proposes an improved topology optimization algorithm, which achieves a more efficient optimization process by correcting the relationship between material density and gas consumption in each iteration. Compared with the traditional method, this optimization method has an accurate correlation between the gas consumption under the rib and the actual consumption, and can optimize the bipolar plate ribs more accurately.

[0017] (3) Improved electrochemical performance: Through the design of the flow channel structure based on the variable density topology optimization method, the present invention can optimize the distribution of gas consumption, thereby reducing the difference in gas concentration and improving the overall electrochemical performance of SOFC. Compared with the traditional design, the optimized flow channel structure can provide higher current density and power under the same conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0019] Figure 1 A flow chart provided for a method for optimizing a SOFC bipolar plate flow channel based on mesoscopic accurate three-dimensional reconstruction according to the present invention; Figure 2 Single channel modeling schematic diagram and model provided for embodiment 1 of the present invention IV Curve verification curve graph; Figure 3 This is a schematic diagram of unit density correction provided in Example 1 of the present invention; wherein, Figure 3 (a) is a schematic diagram of material density correction. Figure 3 (b) is the normalized gas consumption curve from the flow channel to the rib under different current densities; Figure 4 The topology optimization flow channel structure and comparison result diagram provided in the first embodiment of the present invention; wherein, Figure 4 (a) is a schematic diagram of parallel flow channels and topology optimization modeling. Figure 4 (b) is a velocity field comparison diagram. Figure 4 (c) is the current density of 0.6 A cm 2 Time 2 Concentration comparison chart, Figure 4 (d) is the current density of 0.6 A cm 2 Comparison of ion current density at 200 Hz and 200 Hz, Figure 4 (e) in the figure is the difference between different flow channel structures. IV Curve comparison chart. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] Embodiment 1 Reference Figure 1This embodiment provides a method for optimizing a SOFC bipolar plate flow channel based on mesoscopic accurate three-dimensional reconstruction, comprising the following steps: Step 100: Establishing a three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physics field coupling model for SOFC; Step 200: 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; Step 300: 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; Step 400: Calculating and comparing the electrochemical performance of the different topology optimized flow channel structures to obtain multiple sets of electrochemical performance data; Step 500: Integrate the multiple groups of electrochemical performance data, analyze the performance of the different topology optimized flow channel structures, and reveal the influence of different topology optimized flow channel structures on the SOFC battery performance.

[0023] In this embodiment, a single channel structure with a length of 5.85 cm is selected for simulation, and the width and height of the channel are both 1 mm. The preliminary work includes the establishment of a physical model and the use of finite element commercial software for modeling and solving, such as Figure 2 shown.

[0024] In this embodiment, the specific steps include the following: The three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physics field coupling model is constructed using COMSOL finite element software, 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, T 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, F 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, T is the operating temperature, R is the gas constant, is the average pore radius, 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 for electrons and ions: ; ; 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 Faraday constant; The Butler-Volmer equation is used to calculate the electrochemical reaction current density at the anode and cathode, including: In this embodiment, the electrochemical reaction sites of the anode are assumed to be Ni / YSZ / Pore three-phase boundaries TPBs; In this embodiment, for the electrochemical reaction sites of the cathode, it is assumed that the electrochemical reactions occur simultaneously at Dual-phase DPBs and on TPB.

[0025] Therefore, the total electrochemical reaction current density at TPB / DPB is calculated by the Butler-Volmer equation, and the related 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.

[0026] Table 1 Electrochemical reaction equations ;

[0027] Specifically, 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.

[0028] Specifically, 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 the depth averaging method. 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.

[0029] Specifically, 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, 、 and are the two-dimensional equivalent values ​​of diffusion coefficient, porosity and permeability, respectively. D , and are the diffusion coefficient, porosity and permeability of the electrode, respectively.

[0030] The objective equation of the topology optimization is: ; In the formula, To optimize the area, is the entrance boundary, is the volume fraction.

[0031] Specifically, 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, and different topology optimized flow channel structures are obtained, including: First, 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 of half the rib width to accurately express the transient distribution of gas consumption, such as Figure 3 As shown in (a); finally, the double Gaussian fitting function is used to reproduce the distribution of the normalized source term to 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.

[0032] Reference Figure 3 (b) The normalized gas consumption curve from the flow channel to the rib under different current densities shows intuitively that 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, thus achieving accurate introduction and consumption of gas.

[0033] Specifically, 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, the variable density topology optimization method is used to maximize the gas concentration in the overall area of ​​SOFC and obtain the topology optimization structure of SOFC battery stack. Then, the relationship between unit density and consumption items in different areas is corrected to further optimize the flow channel structure. Finally, different topology optimized flow channel structures are calculated and compared with the traditional parallel flow channel structure for electrochemical performance analysis to obtain multiple sets of electrochemical performance data. The results are as follows: Figure 4As shown. Figure 4 The modeling diagram (a) in Figure 2 shows that the electrochemical performance is significantly improved by optimizing the flow channel structure of SOFC. Figure 4 The results of (b), (c) and (d) show that the optimized layout makes the oxygen concentration and ion current density more uniform and achieves higher gas transmission efficiency. Figure 4 (e) provides IV The curve shows that the optimized flow channel structure significantly improves battery performance.

[0034] Specifically, 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 SOFC battery performance, 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.

[0035] Therefore, the above-mentioned optimization method of SOFC bipolar plate flow channels based on mesoscopic precise three-dimensional reconstruction is adopted, aiming to achieve precise design and optimization of the flow channel structure through coupled modeling and topological optimization of fluid-diffusion-electrochemical multi-physical fields, and calculate and optimize the gas consumption distribution in different areas through an improved topological optimization method, thereby improving the electrochemical performance of SOFC, thereby improving the efficiency and reliability of the SOFC system, and providing important technical support for academic research and practical engineering applications in related fields.

[0036] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting 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: Establish a three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physics field coupling model for SOFC; 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: The three-dimensional homogeneous equivalent fluid-diffusion-electrochemical multi-physics field coupling model is constructed using COMSOL finite element software, 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, T 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, F 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, T is the operating temperature, R is the gas constant, is the average pore radius, 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 Faraday constant; The Butler-Volmer equation was used to calculate the electrochemical reaction current density at the anode and cathode.

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: 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.

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 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.

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 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, , and are the two-dimensional equivalent values ​​of diffusion coefficient, porosity and permeability, respectively. D , and are the diffusion coefficient, porosity and permeability of the electrode, respectively.

6. The method for optimizing the flow channel of a SOFC bipolar plate based on mesoscopic accurate three-dimensional reconstruction according to claim 5, 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.

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: 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.

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 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.

9. 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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