CN116467913A - Numerical simulation method of solid oxide fuel cell - Google Patents
Numerical simulation method of solid oxide fuel cell Download PDFInfo
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Abstract
The invention discloses a numerical simulation method of a solid oxide fuel cell, which comprises the following steps: adding a physical field preliminarily according to the requirements; defining the geometric dimensions and material physical parameters of the solid oxide fuel cell; constructing a three-dimensional physical model of the solid oxide fuel cell according to the defined geometric dimension; selectively adding a physical field which is the same as the actual operation into the constructed three-dimensional physical model, defining the added physical field, setting the material property and boundary condition of the physical field, and selecting a control equation; performing grid division on the structural component of the constructed three-dimensional physical model; and carrying out steady-state calculation on the three-dimensional physical model with the divided grids based on a control equation, and displaying a calculation result in a preset format. The numerical simulation process is more convenient and efficient, and has high precision.
Description
Technical Field
The invention relates to the technical field of fuel cells, in particular to a numerical simulation method of a solid oxide fuel cell.
Background
Along with the increasingly severe environmental protection situation, the pressure for reducing carbon emission is continuously increased, the traditional fossil energy sources can only be continuously sought to be transformed, and the Solid Oxide Fuel Cell (SOFC) has wide application scenes in the fields of large power stations, household, transportation, military and the like. Solid oxide fuel cells have been widely studied as a key physical quantity for studying SOFCs because of their advantages of environmental protection and high fuel utilization efficiency, and their relationship with the service life, efficiency, etc. However, due to high experimental research cost caused by the experimental environment, experimental materials, experimental period and other reasons of the SOFC, the experimental research is difficult to directly develop, and the internal performance parameters of the SOFC are difficult to measure, so that the research progress of the SOFC is severely restricted.
Because SOFC is in the high temperature environment for a long time when actually running, and internal structure is complicated, the internal part is extremely easy to cause deformation and fracture because of the high temperature. The heat resistance of the internal components of the battery determines, to a large extent, the service life of the battery, and the power generation efficiency thereof. Key to research SOFCs is the long-term performance of electrochemical reactions under high temperature conditions to test the performance of internals. The SOFC internally relates to the coupling action of electrochemical, temperature field, flow field, material diffusion, hydrodynamics and other physical fields. Due to the characteristics of the SOFC, the SOFC is difficult to study through experiments, and a large number of researchers study through a numerical simulation method, so as to guide the structural design, material selection and the like of the SOFC stack.
At present, some traditional simulation methods can realize simulation of temperature distribution, gas concentration distribution, current density distribution and the like in an SOFC, but the modeling simulation process of the SOFC related to various physical field coupling conditions is complex, and the traditional simulation has the problems of complicated steps and insufficient accuracy. Firstly, defining boundary conditions, physical parameters and the like by self-writing UDF functions, and having complicated and complex modeling process operation; and secondly, neglecting the anisotropy of the battery material in the simulation scheme, namely considering the two layers of materials of the electrode activation layer and the support layer as an electrode for integral modeling, and neglecting the deformation of the internal material of the battery due to thermal stress. Both ignored factors may affect the simulation accuracy, resulting in inaccurate calculation of the current density and affected performance of the battery, and may cause a large deviation between the simulation calculation and the actual situation.
Therefore, it is a need for those skilled in the art to provide a numerical simulation method for a solid oxide fuel cell that is both fast and highly accurate.
Disclosure of Invention
In view of the above, the invention provides a numerical simulation method for a solid oxide fuel cell, which has the advantages of more convenient and efficient numerical simulation process and high precision.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a method of numerical simulation of a solid oxide fuel cell, comprising:
adding a physical field preliminarily according to the requirements;
defining the geometric dimensions and material physical parameters of the solid oxide fuel cell;
constructing a three-dimensional physical model of the solid oxide fuel cell according to the defined geometric dimension;
selectively adding a physical field which is the same as the actual operation into the constructed three-dimensional physical model, defining the added physical field, setting the material property and boundary condition of the physical field, and selecting a control equation;
performing grid division on the structural component of the constructed three-dimensional physical model;
and carrying out steady-state calculation on the three-dimensional physical model with the divided grids based on a control equation, and displaying a calculation result in a preset format.
Further, the added physical field includes: physical field interfaces of hydrogen fuel cells in electrochemistry, free and porous media flow physical field interfaces in fluid flow, porous media heat transfer physical field interfaces in heat transfer, and solid mechanical physical field interfaces in structural mechanics.
Further, the defined geometry includes: the length, the height and the width of the anode gas flow channel and the cathode gas flow channel of the cell piece, the width of a cell rib plate, the thicknesses of a cathode support layer, an anode support layer, a cathode active layer and an anode active layer, and the thickness and the width of electrolyte;
the defined physical parameters of the material include: the cathode support layer, the cathode active layer, the anode support layer, the anode active layer and the electrolyte have the advantages of heat conductivity, effective conductivity, density and specific heat capacity, porosity, young's modulus, poisson's ratio and thermal expansion coefficient of the electrode and the electrolyte material, and inlet temperature, pressure, mass fraction, speed and viscosity of gas.
Further, the three-dimensional physical model is constructed as a geometry consisting of anode channels, cathode channels, anode active layers, anode support layers, cathode active layers, cathode support layers, electrolyte, and outermost current collectors.
Further, the defining the added physical field includes:
the definition of the physical field interface of the hydrogen fuel cell includes: adding materials, wherein air is input into a cathode, and hydrogen is input into an anode; defining the conductivity, porosity and initial polarization voltage of the electrode and electrolyte and exchanging current density; wherein, the physical field area of the hydrogen fuel cell is a cathode gas flow channel and an anode gas flow channel;
the definition of free and porous media flow physical field interfaces includes: defining physical properties of the gas, including effective diffusion coefficient, speed, temperature, pressure and viscosity of the gas; wherein the regions of free and porous media flow physical fields are all parts except the current collector and electrolyte layer;
the porous media heat transfer physical field interface definition includes: defining the thermal conductivity, specific heat and density of the solid material; the porous medium heat transfer physical field area is all areas except the current collector;
the solid mechanics physical field definition includes: defining poisson's ratio, coefficient of thermal expansion and young's modulus of the solid material; the area of the solid mechanical physical field is all the constituent structures of the three-dimensional physical model.
Further, the defining the added physical field further includes:
setting the pressure and temperature of boundary conditions of the gas inlet;
setting the boundary condition of the gas outlet as convection flux and the gas pressure as standard atmospheric pressure;
setting the fluid to a compressible flow;
setting the boundary potential of the anode current collector to 0V; setting the boundary potential of the cathode current collector to be the battery voltage;
providing the boundaries except the inlet and the outlet as thermal insulation and electric insulation;
all directions in which the battery material is arranged are not constrained, and all directions can generate displacement.
Further, a control equation of the physical field interface of the hydrogen fuel is used for describing the current density distribution condition of the solid oxide fuel cell according to the change of concentration;
the control equation of the free and porous medium flow physical field interface is used for describing the velocity distribution, the pressure distribution and the concentration distribution of gas inside the solid oxide fuel cell;
the control equation of the porous medium heat transfer physical field interface is used for calculating the temperature distribution inside the solid oxide fuel cell;
the control equation of the solid mechanical physical field interface is used for describing the relationship between the material mechanical property and the thermal stress of the solid oxide fuel cell.
Further, the meshing of the structural component of the constructed three-dimensional physical model includes:
selecting one surface of a cathode inlet and an anode outlet of a three-dimensional physical model, and carrying out grid division by using a mapping and distribution mode in grid division;
gradually thinning and then densifying along the contact surfaces of the cathode active layer, the anode active layer and the electrolyte; the grids of the cathode support layer and the anode support layer are uniformly distributed; the grids of the electrolyte layer are uniformly distributed;
and (3) taking one surface of the divided grids as a source surface, and finishing grid division after sweeping.
Further, the calculation result is displayed in a graph, a three-dimensional distribution diagram or a chart.
Compared with the prior art, the invention discloses a numerical simulation method of a solid oxide fuel cell, which has the following beneficial effects:
1. the invention has structural division aiming at parameter setting, boundary condition definition, physical field selection and the like, forms a defined parameter file, can rapidly select physical fields, setting parameters, boundary condition and other externally input physical quantities according to requirements during actual operation, realizes rapid simulation of the solid oxide fuel cell, and solves the problems of complex operation, complicated simulation calculation process, slow calculation speed and the like of the traditional modeling. Meanwhile, simulation calculation can be carried out on a plurality of control groups at the same time, and calculation results of the plurality of control groups are displayed through a post-processing chart, so that the simulation method is more convenient and efficient compared with the traditional numerical simulation. And the comparison simulation calculation of several groups of models can be easily realized by controlling a certain variable, so that the efficiency of verification simulation can be improved, and references are provided for improvement of a simulation method of a battery and actual structural design of the battery.
2. According to the invention, a plurality of physical fields are added, so that the heat transfer, mass transfer and electrochemical reaction of the internal coupling of the solid oxide fuel cell stack are realized, the influences of grid division, electrode material anisotropy characteristics, thermal stress and the like on the cell are considered, and the rapid and accurate simulation calculation of the SOFC is realized. And simultaneously, more accurate consideration is made on the structure and the material of the battery, and physical models of an active layer and a supporting layer of the electrode are respectively built. The structural difference of electrode materials or the change of the property of the electrode caused by internal thermal stress are considered, so that the conductivity is changed, and the influence caused by factors such as current density distribution, temperature distribution and the like is further influenced, so that modeling is faster and more accurate.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a numerical simulation method of a solid oxide fuel cell provided by the invention;
fig. 2 is a schematic plan view of a planar convection SOFC single cell provided by the present invention;
fig. 3 is a schematic plan view of a single flow channel of a planar convection SOFC according to the present invention;
fig. 4 is a schematic three-dimensional structure of a single flow channel of a planar convection SOFC according to the present invention;
fig. 5 is a schematic diagram of three-dimensional meshing of a planar convection SOFC provided by the present invention;
FIG. 6 is a graph showing power output as a function of battery voltage for steady state calculations in accordance with the present invention;
fig. 7 is a graph of current density vector distribution of an electrolyte layer according to the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
As shown in fig. 1, the embodiment of the invention discloses a numerical simulation method of a solid oxide fuel cell, which comprises the following steps:
firstly, adding a physical field preliminarily according to requirements;
defining the geometric dimension and the physical parameters of materials of the solid oxide fuel cell;
step three, constructing a three-dimensional physical model of the solid oxide fuel cell according to the defined geometric dimension;
step four, selectively adding a physical field which is the same as the actual operation into the constructed three-dimensional physical model, defining the added physical field, setting the material property and boundary condition of the physical field, and selecting a control equation;
step five, carrying out grid division on the structural component of the constructed three-dimensional physical model;
and step six, performing steady-state calculation on the three-dimensional physical model with the divided grids based on a control equation, and displaying a calculation result in a preset format.
In the embodiment of the invention, a single flow channel of a flat convection type solid oxide fuel cell is taken as an example, as shown in fig. 2, a three-dimensional physical model is established based on the actual condition of the flat convection type solid oxide fuel cell running under a steady state condition according to the geometric parameters, physical properties of materials and boundary conditions, various physical fields which are the same as the actual running are added through software simulation, the physical model is subjected to grid division by adopting a finite element method, a solver is called for calculation, and finally the obtained simulation data is processed and analyzed. In terms of simulation accuracy, the structural difference of electrode materials and the change of the properties of the electrode due to deformation caused by thermal stress are considered, so that conductivity change can be caused, and further current density distribution and battery performance are affected. In the aspect of simulation speed, the definition parameters are directly imported through an external file, and the rapid simulation modeling is realized in a structured grid division mode.
In one embodiment, it is known from the operating principles of SOFCs that there are multiple physical field coupling effects in actual operation, requiring simulation of their electrochemical, heat transfer, mass transfer and thermal stress fields. Specifically, the physical field added in the first step includes: physical field interfaces of hydrogen fuel cells in electrochemistry, free and porous media flow physical field interfaces in fluid flow, porous media heat transfer physical field interfaces in heat transfer, and solid mechanical physical field interfaces in structural mechanics.
In the second step, when defining the geometric dimension and physical parameters of the material, each data is defined by naming, text description and the like, and the data can be directly input into the parameters under the global definition in the model developer of the software interface through external import (files in txt, xlsx and the like), and in the embodiment, the parameter definition is quickly performed through the direct import of the external files.
Wherein the defined geometry comprises: the length, the height and the width of the anode gas flow channel and the cathode gas flow channel of the cell piece, the width of a cell rib plate, the thicknesses of a cathode support layer, an anode support layer, a cathode active layer and an anode active layer, and the thickness and the width of electrolyte;
the defined physical parameters of the material include: the cathode support layer, the cathode active layer, the anode support layer, the anode active layer and the electrolyte have the advantages of heat conductivity, effective conductivity, density and specific heat capacity, porosity, young's modulus, poisson's ratio and thermal expansion coefficient of the electrode and the electrolyte material, and inlet temperature, pressure, mass fraction, speed and viscosity of gas.
Through global definition of input parameters, the defined parameters can be directly called in the next step of building a three-dimensional physical model, so that modeling is more convenient and rapid.
In one embodiment, in step three, the cell structure of the actual SOFC is very complex, and many simplifying assumptions are made in the modeling process. In view of simulation accuracy, the three-dimensional physical model constructed in this embodiment is a geometric structure composed of anode channels, cathode channels, anode active layers, anode support layers, cathode active layers, cathode support layers, electrolytes and outermost current collectors, in order to ensure the accuracy of calculation results as much as possible, due to the porosity of different electrode materials and their anisotropic properties, and the influence of thermal stress on the cell structure.
Because the geometric dimension of the battery is defined in the second step, the step directly inputs the name call defined by the geometric dimension, and the establishment of the three-dimensional physical model can be completed. The planar structure of the three-dimensional physical model of the SOFC single runner is shown in fig. 3, and the three-dimensional structure is shown in fig. 4. Since all physical field calculations do not involve the current collector component during simulation, this part is not considered in the subsequent creation of the three-dimensional physical model and grid partitioning.
In a specific embodiment, in the fourth step, after the three-dimensional physical model is built, the built model and the added physical field are defined, including adding material properties, setting boundary conditions and initial values, and selecting a control equation. In order to completely simulate a plurality of physical fields of the SOFC, four physical field interfaces of (1) a hydrogen fuel cell, (2) free and porous medium flow, (3) porous medium heat transfer and (4) solid mechanics are added into a three-dimensional physical model, and the four physical fields are respectively defined.
Specifically, defining the added physical field includes:
the definition of the physical field interface of the hydrogen fuel cell includes: adding materials, wherein air is input into a cathode, and hydrogen is input into an anode; defining the conductivity, porosity and initial polarization voltage of the electrode and electrolyte and exchanging current density; wherein, the physical field area of the hydrogen fuel cell is a cathode gas flow channel and an anode gas flow channel;
the definition of free and porous media flow physical field interfaces includes: defining physical properties of the gas, including effective diffusion coefficient, speed, temperature, pressure and viscosity of the gas; wherein the regions of free and porous media flow physical fields are all parts except the current collector and electrolyte layer;
the porous media heat transfer physical field interface definition includes: defining the thermal conductivity, specific heat and density of the solid material; the porous medium heat transfer physical field area is all areas except the current collector;
the solid mechanics physical field definition includes: defining poisson's ratio, coefficient of thermal expansion and young's modulus of the solid material; the area of the solid mechanical physical field is all the constituent structures of the three-dimensional physical model.
In other embodiments, in step four, the interface for some physical fields requires definition of initial values, such as:
setting the pressure and temperature of boundary conditions of the gas inlet;
setting the boundary condition of the gas outlet as convection flux and the gas pressure as standard atmospheric pressure;
setting the fluid to a compressible flow; in most modeling, compressibility is assumed to be incompressible, in this example compressible flow is provided, and slip is selected between the fluid and the wall.
The boundary potential of the anode current collector is set to 0V; the boundary potential of the cathode current collector is set as the battery voltage;
setting the boundary conditions except the inlet and the outlet as thermal insulation and electric insulation; because only a single flow channel of the battery is simulated, the heat loss of the battery to the outside is not considered, namely, the rest boundary conditions except the inlet and the outlet are all heat insulation and electric insulation.
All directions in which the battery material is arranged are not constrained, and all directions can generate displacement.
In one embodiment, step four calculates the four physical fields by the following control equations, respectively, to obtain the distribution of the speed, the temperature, the current, and the like.
(1) The control equation of the physical field interface of the hydrogen fuel is used for describing the current density distribution situation of the solid oxide fuel cell which varies with the concentration; the method specifically comprises the following steps:
the activation overpotential, which is an unavoidable loss in solid oxide fuel cells, can be analyzed, and the relationship between charge transfer and overpotential is described by the following control equation, which is expressed mathematically as follows:
where v represents the gradient operator, σ i Representing electrolysisConductivity of mass or gas ions, phi i Representing the potential of the electrode or electrolyte, Q i Representing the charge source term. Since the electrolyte of SOFC has the property of being able to transfer ions only and not conduct electrons, the conductivity of electrons and ions needs to be modified as follows:
in the above formula, θ represents the volume fraction of the conductor, ε represents the porosity of the electrode material,representing the effective conductivity, sigma e θ represents the conductivity. This gives the effective conductivity of ions and electrons.
The activation polarization loss is the inevitable loss of the SOFC in the electrochemical reaction process, and can influence the current density, the charge transfer current density is described by utilizing Butler-Volmer charge transfer dynamics, and the cathode and anode polarization currents are calculated by the following formula:
in the above, i a 、i c Representing the polarization current densities, i, of the anode and cathode, respectively 0,a 、i 0,c The exchange current density of the anode and the cathode is respectively represented, R is a gas constant, T is the temperature during operation, and F is a Faraday constant;is the partial pressure of hydrogen;is the reference partial pressure of hydrogen; η is the overpotential; p is p h2o Is the partial pressure of water vapor; p is p h2o，ref Is the reference partial pressure of water vapor;is the partial pressure of oxygen; />Is the reference partial pressure of oxygen. The above is a control equation needed to calculate the current density distribution using the hydrogen fuel cell physical field interface, which is used in part to calculate the current density distribution profile over concentration in a SOFC.
(2) The control equation of the free and porous medium flow physical field interface is used for describing the distribution of the speed, the concentration and the pressure of the gas in the solid oxide fuel cell; specifically, the compressible Navie-Stokes equation controls flow in an open channel, describing the flow of an internal gas in conjunction with Darcy's Law. The momentum equation expression is as follows:
in the above formula, ρ represents the density,representing a velocity vector, ψ representing the viscosity tensor in the flow path; n represents a volume force vector, and P represents the total pressure of the mixed gas; mu (mu) e Representing the effective viscosity coefficient; and represents a gradient operator. Since the fluid material will flow and diffuse in three dimensions inside the SOFC, a velocity distribution of the gas inside the cell is obtained.
(3) The control equation of the porous medium heat transfer physical field interface is used for calculating the temperature field inside the solid oxide fuel cell; the porous medium transfers heat and selects the law of conservation of energy, and the expression of the control equation is as follows:
wherein C is p v represents the constant pressure specific heat capacity of the substance, h eff Representing the effective heat transfer coefficient between objects, ρ is the density, Q heat source term. The heat source item is from the electrochemical reaction heating inside the SOFC and ohmic resistance heat generated by current passing through the conductor, and the internal heat transfer is mainly through three modes of heat convection heat conduction heat radiation. The heat convection between the gas and the electrode, the heat conduction between the electrode and the electrolyte, neglecting the heat radiation between the electrode and the current collector, assuming that the battery has no heat loss to the outside.
(4) The control equation of the solid mechanical physical field interface is used to describe the relationship between the material mechanical properties and thermal stress of a solid oxide fuel cell. Physical parameters of materials can be rapidly defined through COMSOL, so that thermal stress distribution of different material types of the same battery structure and influence of deformation of the battery on current density distribution caused by thermal stress are obtained.
The high temperatures inside solid oxide fuel cells can cause thermal expansion of the materials that can ultimately lead to deformation. In the material of SOFC, the overall pressure is due to elastic and thermal stresses, and the relationship between linear material stress and pressure can be expressed as:
σ＝Dε el +σ 0
initial stress sigma 0 Which is considered herein as the residual stress,
wherein E represents Young's modulus of the material, v represents Poisson's ratio of the material, D represents elastic matrix of the material, ε el Representing the elastic stress.
The actual SOFC electrode structure is divided into an active layer and a support layer, so it is assumed in the solid mechanical physical field that the mechanical properties of the active layer are similar to those of the support layer and the electrolyte layer. Considering that the two current collectors of the cell are fixed in the stack, the face of the cell in contact with the current collectors adds a fixed constraint, the remaining boundaries being free. The stresses generated are mainly concentrated between the interfaces. The solid mechanics part is used for calculating stress calculation and analysis in the battery, and is a result of unidirectional coupling of two physical fields of porous medium heat transfer and solid mechanics.
In a specific embodiment, in the fifth step, after the definition of the physical field interface of the SOFC three-dimensional physical model is completed, the three-dimensional model is subjected to grid division processing, and in the numerical simulation process, the grid division is directly related to the time and the precision of the simulation calculation. So a simple verification is performed on the divided grids at this step, ensuring that the simulation is fast and accurate. There are three ways of COMSOL meshing: physical field control, manual dissection and file importing.
The specific steps for grid division are as follows:
adopting a mapping grid swept along the channel direction, selecting one surface of a cathode inlet and an anode outlet of a three-dimensional physical model, and carrying out grid division by using a mapping and distribution mode in the grid division;
gradually thinning and then densifying along the contact surfaces of the cathode active layer, the anode active layer and the electrolyte; the grids of the cathode support layer and the anode support layer are uniformly distributed; the grids of the electrolyte layer are uniformly distributed;
and (3) taking one surface of the divided grids as a source surface, and finishing grid division after sweeping.
The divided three-dimensional physical model is shown in fig. 5, and the grid division mode has the advantages of improving the calculation precision and the simulation speed.
In one embodiment, in step six, a selection solver is set to begin solving. The calculation is completed, and the calculation result is processed through the drawing group and the drawing type, so that the calculation result can be displayed in a graph, a three-dimensional distribution diagram or a chart form and the like. Some default drawings are generated when the calculation is completed, and are automatically generated after the software selects the physical field.
The graph may also be plotted according to its own needs, for example to obtain a plot of the power output of the battery as a function of the battery voltage. By adding a one-dimensional drawing group, the drawn chart is named in a setting window, the X axis and the Y axis are named, and the Y axis data are defined as V.times.I. Clicking the plot results in the case where the output power of the battery varies with the battery voltage, as shown in fig. 6.
The calculation of the current density distribution is described in detail as an example: the simulation method of the invention calculates aiming at the state of the battery under steady-state operation, so that the steady-state is selected, a physical field interface of the hydrogen fuel cell is selected, auxiliary scanning setting is carried out, the initial electrode polarization voltage is taken as a parameter, and a starting value, a simulation step length and an ending value are set. All the settings of the simulation calculation are completed, the calculation is clicked, and the simulation result is waited, and the result is shown in a current density vector distribution schematic diagram of the electrolyte layer in fig. 7.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (9)
1. A numerical simulation method of a solid oxide fuel cell, comprising:
adding a physical field preliminarily according to the requirements;
defining the geometric dimensions and material physical parameters of the solid oxide fuel cell;
constructing a three-dimensional physical model of the solid oxide fuel cell according to the defined geometric dimension;
selectively adding a physical field which is the same as the actual operation into the constructed three-dimensional physical model, defining the added physical field, setting the material property and boundary condition of the physical field, and selecting a control equation;
performing grid division on the structural component of the constructed three-dimensional physical model;
and carrying out steady-state calculation on the three-dimensional physical model with the divided grids based on a control equation, and displaying a calculation result in a preset format.
2. The method for numerical simulation of a solid oxide fuel cell according to claim 1, wherein the added physical field includes: physical field interfaces of hydrogen fuel cells in electrochemistry, free and porous media flow physical field interfaces in fluid flow, porous media heat transfer physical field interfaces in heat transfer, and solid mechanical physical field interfaces in structural mechanics.
3. The method for numerical simulation of a solid oxide fuel cell of claim 1, wherein the defined geometry comprises: the length, the height and the width of the anode gas flow channel and the cathode gas flow channel of the cell piece, the width of a cell rib plate, the thicknesses of a cathode support layer, an anode support layer, a cathode active layer and an anode active layer, and the thickness and the width of electrolyte;
the defined physical parameters of the material include: the cathode support layer, the cathode active layer, the anode support layer, the anode active layer and the electrolyte have the advantages of heat conductivity, effective conductivity, density and specific heat capacity, porosity, young's modulus, poisson's ratio and thermal expansion coefficient of the electrode and the electrolyte material, and inlet temperature, pressure, mass fraction, speed and viscosity of gas.
4. The method of claim 1, wherein the three-dimensional physical model is constructed as a geometric structure consisting of anode channels, cathode channels, anode active layers, anode support layers, cathode active layers, cathode support layers, electrolyte, and outermost current collector.
5. The method for numerical simulation of a solid oxide fuel cell according to claim 1, wherein the defining of the added physical field includes:
the definition of the physical field interface of the hydrogen fuel cell includes: adding materials, wherein air is input into a cathode, and hydrogen is input into an anode; defining the conductivity, porosity and initial polarization voltage of the electrode and electrolyte and exchanging current density; wherein, the physical field area of the hydrogen fuel cell is a cathode gas flow channel and an anode gas flow channel;
the definition of free and porous media flow physical field interfaces includes: defining physical properties of the gas, including effective diffusion coefficient, speed, temperature, pressure and viscosity of the gas; wherein the regions of free and porous media flow physical fields are all parts except the current collector and electrolyte layer;
the porous media heat transfer physical field interface definition includes: defining the thermal conductivity, specific heat and density of the solid material; the porous medium heat transfer physical field area is all areas except the current collector;
the solid mechanics physical field definition includes: defining poisson's ratio, coefficient of thermal expansion and young's modulus of the solid material; the area of the solid mechanical physical field is all the constituent structures of the three-dimensional physical model.
6. The method for numerical simulation of a solid oxide fuel cell according to claim 1, wherein the defining of the added physical field further comprises:
setting the pressure and temperature of boundary conditions of the gas inlet;
setting the boundary condition of the gas outlet as convection flux and the gas pressure as standard atmospheric pressure;
setting the fluid to a compressible flow;
setting the boundary potential of the anode current collector to 0V; setting the boundary potential of the cathode current collector to be the battery voltage;
providing the boundaries except the inlet and the outlet as thermal insulation and electric insulation;
all directions in which the battery material is arranged are not constrained, and all directions can generate displacement.
7. The method of claim 1, wherein the control equation of the physical field interface of the hydrogen fuel is used to describe the current density distribution of the solid oxide fuel cell as a function of concentration;
the control equation of the free and porous medium flow physical field interface is used for describing the velocity distribution, the pressure distribution and the concentration distribution of gas inside the solid oxide fuel cell;
the control equation of the porous medium heat transfer physical field interface is used for calculating the temperature distribution inside the solid oxide fuel cell;
the control equation of the solid mechanical physical field interface is used for describing the relationship between the material mechanical property and the thermal stress of the solid oxide fuel cell.
8. The numerical simulation method of a solid oxide fuel cell according to claim 1, wherein the meshing of the structural members of the constructed three-dimensional physical model comprises:
selecting one surface of a cathode inlet and an anode outlet of a three-dimensional physical model, and carrying out grid division by using a mapping and distribution mode in grid division;
gradually thinning and then densifying along the contact surfaces of the cathode active layer, the anode active layer and the electrolyte; the grids of the cathode support layer and the anode support layer are uniformly distributed; the grids of the electrolyte layer are uniformly distributed;
and (3) taking one surface of the divided grids as a source surface, and finishing grid division after sweeping.
9. The numerical simulation method of a solid oxide fuel cell according to claim 1, wherein the calculation result is displayed in the form of a graph, a three-dimensional distribution map, or a graph.
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