CN115642269B - A solid oxide fuel cell structure and its optimal design method - Google Patents

Abstract

The invention discloses a structure of a solid oxide fuel cell, which comprises an anode base body, and the upper and lower surfaces of the anode base body are sequentially provided with an anode current collecting bar, an electrolyte, a cathode and a cathode connector; two layers of wells are arranged inside the anode base body The gas channel of the type structure, each layer of the gas channel is connected to each other; the anode collector bar is arranged along the centerline of the width direction of the anode substrate; the cathode connector is provided with multiple ribs arranged at intervals on the side facing the cathode, and the ribs The width gradually expands along the direction of gas flow, so that the width of the air channel in the direction of gas flow gradually decreases. The battery structure of the present invention enhances the battery strength to a certain extent, reduces the ohmic loss of current transmission on the anode substrate, effectively increases the air flow velocity and the oxygen molar concentration, and improves the battery output performance and durability. At the same time, the invention also discloses a battery structure optimization design method, which can further improve the output performance of the battery by optimizing the key structural parameters of the battery.

Description

A solid oxide fuel cell structure and its optimal design method

technical field

The invention belongs to the field of fuel cells, in particular to a solid oxide fuel cell structure and an optimization design method thereof.

Background technique

Solid oxide fuel cell (Solid oxide fuel cell, SOFC) is a ceramic electrochemical conversion device that directly converts fuel chemical energy into electrical energy. It has an all-solid-state battery structure, high energy utilization rate, no need for noble metal catalysts, and strong fuel adaptability. And other advantages, has a relatively broad development prospects.

The basic composition of a solid oxide fuel cell includes at least one layer of dense solid electrolyte, at least one anode, at least one cathode, electrode connectors and several gas channels. When the battery is working, the anode is fed with gas, and the cathode is fed with oxidant gas represented by air. Oxygen undergoes a reduction reaction on the cathode side to generate oxygen ions. Under the action of electrochemical potential energy, it passes through the electrolyte and enters the anode side, where it undergoes an oxidation reaction with the gas. Water is generated, and electrons migrate from the anode to the cathode through an external circuit to form a loop.

The traditional electrolyte-supported plate solid oxide fuel cell has an asymmetric structure in the thickness direction. Due to the uneven internal temperature distribution during the working process of the battery and the mismatch of thermal expansion coefficients among the components of the battery, thermal stress occurs, thermal deformation occurs, and affects battery operating life. Both the cathode and anode sides of the battery need to be equipped with high-cost connectors to complete the distribution of the reaction gas and realize the collection of current at the same time. The inside of the connecting body is provided with an airway groove with a fixed cross-sectional size for the reaction gas to flow through the entire electrode; the external convex ribs of the connecting body are attached to the electrode to realize the collection and transmission of the reaction current on the highly conductive connecting body. At the structural design level of the connector, it is necessary to deal with the competitive relationship between the airway size and the rib size in the connector: the wider rib design increases the contact area between the connector and the electrode, and at the same time shortens the current flow from the three-phase region to the electrode. The flow path of the connecting body, thereby reducing the ohmic loss caused by the current transmission on the electrode (the electrode conductance is lower than the current collector); but on the other hand, the wider rib design reduces the direct contact area between the reactant gas and the electrode, and the reaction The diffusion of gas in the electrode area under the rib is limited, the reaction gas concentration in the three-phase area under the rib is low, and even a gas-free area will appear, which significantly affects the effective reaction area of the battery and reduces the output performance of the battery.

Optimizing the design of the solid oxide fuel cell structure can improve the overall output performance of the cell. Existing studies have explored structural factors affecting battery performance output based on experimental design and three-dimensional numerical simulation. Each parameter combination is used for processing experiments or modeling simulations. The economic cost in the processing experiments and the time cost in the modeling and simulation process are very high, and it is impossible to optimize the battery structure quickly and economically to achieve the purpose of further improving the performance of solid oxide fuel cells.

Contents of the invention

The invention provides a solid oxide fuel cell structure, which can realize the secondary distribution of gas inside the battery, enhance the strength of the battery to a certain extent; at the same time, reduce the ohmic loss of current transmission on the anode substrate; effectively increase the flow velocity of the air in the rear and oxygen molar concentration, thereby improving battery output performance and improving battery durability to a certain extent.

A solid oxide fuel cell structure, including an anode base body, the upper and lower surfaces of the anode base body are sequentially provided with an anode current collector, an electrolyte, a cathode and a cathode connector, and the overall structure is symmetrical;

The inside of the anode base is provided with two layers of well-shaped gas channels, and the inside of each layer of gas channels is connected to each other; the electrolyte is coated on the upper and lower surfaces of the anode base, and the anode current collector bar is clamped Between the electrolyte and the anode base; the anode current collector bar is arranged along the centerline of the width direction of the anode base; the cathode is coated on the outer surface of the electrolyte;

The cathode connecting body is provided with a plurality of ribs arranged at intervals on the side facing the cathode, and the width of the ribs gradually expands along the direction of gas flow, so that the air channel in the direction of gas flow gradually decreases.

In the present invention, by improving the structure of the solid oxide fuel cell, the built-in gas channel of the anode is set as two layers of intercommunicating gas channels arranged in a well shape, and the horizontal gas channels arranged at intervals are designed to connect the originally independent longitudinal through gas channels to achieve Secondary distribution of gas inside the battery. Compared with the existing built-in air channels of the anode, the cross-section of the built-in air channels arranged in a well-shaped arrangement is circular, smaller in size, and symmetrically arranged in double layers inside the anode. The built-in air channel of the anode enhances the strength of the battery to a certain extent, effectively increases the gas flow velocity in the air channel, increases the molar fraction of the reaction gas, thereby improving the battery output performance, and the well-shaped air channel configuration can achieve a more uniform gas flow configuration , to make the anode reaction more fully, to achieve a more uniform anode current distribution, thereby improving the uneven distribution of electrochemical reaction heat in the battery reaction zone, reducing the internal temperature gradient of the battery, reducing the internal thermal stress of the battery, and improving the durability of the battery to a certain extent .

The invention improves the structure of the solid oxide fuel cell, and arranges the anode collector bar to be sandwiched between the anode base body and the electrolyte on both sides. The anode current collector bar is arranged along the center line of the battery width direction, and is attached to the outer surface of the anode, which can reduce the transmission path of the current on the anode substrate and reduce the ohmic loss of the current transmission on the anode substrate.

In the present invention, by improving the structure of the solid oxidation fuel cell, the ribs of the cathode connecting body are set as a gradual change structure whose width gradually expands along the direction of gas flow. Correspondingly, the width of the air channel gradually decreases along the direction of gas flow, thereby realizing the widened air channel design . The structure of the cathode connector ensures a certain contact area with the cathode, and at the same time effectively increases the flow velocity of the rear air and the molar concentration of oxygen, and enhances the diffusion capacity of the air rear, thereby improving the output performance of the battery. Realize a more uniform cathode current distribution, thereby improving the uneven distribution of electrochemical reaction heat in the battery reaction zone, reducing the internal temperature gradient of the battery, reducing the internal thermal stress of the battery, and improving the durability of the battery to a certain extent.

Further, the anode substrate and the cathode are porous media, which are both electron and ion conductors. The electrolyte shown is a solid gas-impermeable medium that is an ion conductor.

Further, the anode substrate and the cathode are made of porous metal-ceramic composite materials, the electrolyte is made of ceramic materials, and the cathode connector and the anode current collector are made of highly conductive metal or alloy materials. The electrical conductivity of the cathode connecting body is higher than that of the cathode, and it can withstand high temperature; the cross-sectional shape of the rib is set to be rectangular, and the corresponding cross-sectional shape of the air channel is also rectangular, so that the air can flow evenly inside the air channel. Among them, the anode matrix is further subdivided into an intermediate support layer for support and built-in gas channels, and active layers on both sides that contact the electrolyte for electrochemical reactions. The material composition of different functional layers is consistent, and the distribution ratio of each component is different.

Furthermore, the interior of each layer of gas channels is connected to the original independent longitudinal channels by setting intervals arranged horizontal channels, thereby forming interconnected gas channels of a well-shaped structure. The two layers of gas channels arranged in a well-shaped shape are respectively arranged close to the surfaces of both sides of the anode, so as to shorten the path of gas diffusion in the porous medium of the anode to the three-phase reaction zone. Since the material strength of the anode porous material itself is lower than that of the metal connector, the cross-sectional shape of the gas gas channel is set to be circular to avoid stress concentration in the hollow structure inside the anode. The spacing between the longitudinal airway and the transverse airway is an independent structural design parameter.

Further, the anode current collector bar is an elongated narrow bar, one end of which is flush with the end face of the anode base in the length direction, and the other end extends to the battery reaction zone between the anode base and the electrolyte, and its conductivity is higher than that of the anode. This setting can reduce the transmission path of the current on the anode base body, and reduce the ohmic loss of the current transmission on the anode base body.

Further, the cathode connecting body includes a body and a plurality of ribs arranged at intervals inside the body; the outer end surfaces of the ribs are in close contact with the surface of the cathode, and the space between the ribs and the surface of the cathode form several air channels;

The inside of the body is provided with an air distribution groove and an air collection groove at both ends of the length direction; one end of the air distribution groove is provided with an air intake hole through the body, and the air collection groove is provided at an end far away from the air intake hole. There are vent holes running through the body.

Preferably, the width of the ribs on the air inlet side is 1-2 mm, and the width of the ribs on the air outlet side is 2-3 mm. Each air channel and its adjacent ribs are an internal unit of a connecting body, and the sum of the cross-sectional widths of the two is constant. , which is the interval between two adjacent airways. The length, width and height of the anode current collector bar are 5-90mm×2-10mm×0.015mm. In the anode matrix, the cross-sectional radius of the gas gas channel is 0.2-0.6 mm, the interval between the longitudinal air channels is 1.5-2.5 mm, and the interval between the transverse air channels is 5-15 mm.

The present invention also provides a method for optimizing the design of the structure of the solid oxide fuel cell, aiming at the physical parameters and electrochemical characteristics of the battery, optimizing the structure of the solid oxide fuel cell to further improve the output performance of the battery, including the following steps:

S1: Based on the three-dimensional size parameters of each component of the solid oxide fuel cell structure, perform parametric modeling to obtain the battery geometric model;

S2: Construct the optimization problem, determine the objective function, determine the optimization variables and design space, and determine the constraints;

S3: Based on the experimental design method, construct the sample set and test set sampling points in the design space of S2;

S4: Based on the battery geometric model established in S1, set the corresponding physical and electrochemical control equations and boundary conditions, build a simulation model and verify the rationality of the simulation results based on the performance curve data measured by the experiment; call the simulation model to calculate the sample set and test respectively Set the response value of each sampling point;

S5: Based on the Kriging proxy model approximation method, call the input-output relationship of the sample set in S4 to construct the proxy model; call the input-output relationship of the test set in S4 to evaluate the accuracy of the proxy model, and judge the response value of the proxy model at each sampling point of the test set. Whether the simulation results meet the error requirements, if not, re-do the S3 test design and increase the number of sampling points in the sample set;

S6: Based on the gray wolf intelligent optimization algorithm, call the proxy model built in S5 to solve the optimization problem of S2, update the battery geometric structure according to the obtained optimal parameter combination, perform 3D simulation calculation, and check whether the error between the prediction result of the proxy model and the simulation result satisfies Requirements, if the error requirements are met, the optimization will end, and the optimal structural parameter combination of the battery will be output; if not, the simulation data of this group will be added to the sample set, the proxy model will be rebuilt, and the optimization will continue until the error requirements are met.

Further, in step S1, the parametric modeling object is the structure of the solid oxide fuel cell, and the parameters include the three-dimensional size parameters of each component of the battery. By changing each parameter variable, the adjustment of the battery structure is realized.

Further, in step S2, the output power is determined as the objective function; respectively select the rib width of the air inlet side of the cathode connector, the rib width of the air outlet side of the cathode connector, the width of the anode collector bar, the length of the anode collector bar, the anode The inner diameter of the gas channel in the matrix, the arrangement interval of the longitudinal air channel and the arrangement interval of the transverse air channel in the anode matrix are optimization variables; based on the overall structural requirements of the battery, the value range of each optimization variable is designed to determine the corresponding constraints.

Further, in step S3, the optimal Latin hypercube test design method is used to generate the sampling points of the sample set and the test set respectively, and the optimal Latin hypercube test method obtains a more uniform distribution of samples in the design space by adding a criterion point. The sampling points of the sample set and the test set are obtained through two independent optimal Latin hypercube experiments, and the sampling points of both of them fill the entire design space and do not overlap with each other. The concrete steps of step S3 are:

S31: Perform normalization processing on the value range of each optimization variable, and map the range of each variable to the interval [0,1];

S32: In the 7-dimensional sample space composed of 7 optimization variables, divide each dimension into m intervals, so that the probability of each interval is the same;

S33: random sampling in each interval of each optimization variable;

S34: Randomly pair the values to ensure that each level of a factor is studied only once, and apply an orthogonality criterion to achieve better space filling characteristics, and generate a sample set containing m sampling points;

S35: Denormalize the extracted points according to the value range of each variable, and map them to the real design space;

S36: Repeat the above steps to generate test set sampling points.

Further, in step S4, the simulation model is a multi-physics coupling model, and the specific steps for constructing the simulation model are:

S41: Define the physical parameters corresponding to the materials of gas, air and battery components;

S42: Set corresponding control equations and boundary conditions on different domains and boundaries of the parametric model of the solid oxide fuel cell structure;

S43: Mesh the geometric structure of the model, and calculate the numerical solution of the partial differential equation problem for each sub-region after meshing based on the finite element method; carry out grid independence analysis, and determine the grid according to the error of the simulation results under different grid numbers quantity;

S44: Carry out a battery performance experiment, obtain the current-voltage polarization curve of the battery at the working temperature, and check the accuracy of the simulation model based on the experimental curve;

S45: According to the combination of structural parameters of each sampling point in the sample set and test set in S3, update the model structure and adaptively adjust the grid, solve the response value of each sampling point based on multi-physics coupling simulation, and construct the sample set and test set. power mapping.

Compared with the prior art, the present invention has the following beneficial effects:

1. By improving the structure of the solid oxide fuel cell, the present invention sets the built-in gas channel of the anode as a two-layer intercommunicating gas channel structure arranged in a well shape. The built-in gas channel structure of the anode reduces the size of the gas channel and sets the cross-sectional shape of the gas channel to be circular, which enhances the battery strength to a certain extent, effectively increases the gas flow velocity in the gas channel, and increases the mole fraction of the reaction gas, thereby improving the battery output performance. At the same time, the well-shaped gas channel structure can achieve a more uniform gas flow configuration, make the anode reaction more complete, and achieve a more uniform anode current distribution, thereby improving the uneven distribution of electrochemical reaction heat in the battery reaction zone, reducing the internal temperature gradient of the battery, and reducing the temperature gradient. The internal thermal stress of the small battery improves the durability of the battery to a certain extent.

2. The present invention improves the structure of the solid oxide fuel cell, and arranges the anode current collector bar sandwiched between the anode base body and the electrolyte on both sides. The structure of the anode current collector bar can reduce the transmission path of the current on the anode base body and reduce the ohmic loss of the current transmission on the anode base body.

3. By improving the structure of the solid oxidation fuel cell, the present invention sets the gas channel of the cathode connecting body as a gradient structure whose width gradually decreases along the direction of gas flow, so as to realize the widened gas channel design. The cathode connecting body structure effectively increases the flow velocity and molar concentration of oxygen in the back-end of the air, enhances the diffusion ability of the air in the back-end, thereby improving the output performance of the battery, and at the same time, the cathode air channel structure with a wide front and a narrow back can achieve a more uniform cathode current distribution, thereby improving the uneven distribution of electrochemical reaction heat in the battery reaction zone, reducing the internal temperature gradient of the battery, reducing the internal thermal stress of the battery, and improving the durability of the battery to a certain extent.

4. The present invention keeps the formula of each component material of the prior art battery unchanged, and only improves the battery structure to achieve the purpose of improving the battery output performance and durability; on this basis, based on the proxy model and intelligent optimization algorithm, through optimization The key structural parameters of battery output performance have further improved battery performance. Under the premise of ensuring accuracy, this optimal design method has low time cost, high reliability, no need for expensive and repeated processing tests, and has wider engineering application prospects. .

Description of drawings

Fig. 1 is a schematic structural diagram of a solid oxide fuel cell according to an embodiment of the present invention;

Fig. 2 is a schematic diagram of the structure of the anode current collector and the structure of the anode built-in airway in the embodiment of the present invention;

3 is a schematic diagram of the structure of the cathode connector in the embodiment of the present invention;

Fig. 4 is a schematic flow chart of an optimal design method for a solid oxide fuel cell structure according to an embodiment of the present invention.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be noted that the following embodiments are intended to facilitate the understanding of the present invention, but do not limit it in any way.

It should be pointed out that the same numerals appearing in different drawings represent the same item, and the terms "upper", "lower", "upper surface", "lower surface", "side" and other descriptions of positional relationships that appear are all Based on the orientation relationship in the drawings, the term "interval" refers to the distance between the center points of two components, and the length is expressed in millimeters (mm).

As shown in Figure 1, a solid oxide fuel cell structure includes an anode base 5, and the upper and lower surfaces of the anode base 5 are sequentially provided with an anode current collector bar 4, an electrolyte 3, a cathode 2 and a cathode connector 1, and the whole It is distributed in a symmetrical double electrolyte-double cathode structure. The anode substrate 5 is thicker than the electrolyte and the cathode, and serves as a battery support layer. The main body of the battery adopts an anode support plate structure, and the rest of the components are processed and formed on the upper and lower surfaces of the anode according to the assembly sequence. The anode current collector bar 4 is sandwiched between the anode matrix 5 and the electrolyte 3 in parallel, and serves as a current collector for the anode reaction current.

The anode substrate and the cathode are made of porous metal-ceramic composite materials, the electrolyte 3 is made of ceramic materials, the cathode connecting body 1 and the anode current collector bar 4 are made of high-conductivity metal or alloy materials, which can withstand high temperature. The anode substrate 5 can be further subdivided into an intermediate support layer for support and a built-in gas channel, and active layers on both sides that contact the electrolyte for electrochemical reactions; the material composition of the different functional layers of the anode is consistent, and the distribution ratio of each component is different. Better electrochemical reactions while ensuring battery strength.

As shown in Figure 2, the anode base 5 is built with two layers of gas channels 10 in a well-shaped structure, and the interior of each layer of gas channels 10 is connected to each other. Figure 2 shows the structure cut along the central section of the gas channel. Compared with the existing built-in air channels of the anode, the cross-sectional size of the built-in air channels arranged in a well-shaped arrangement is smaller, symmetrically arranged inside the anode, and close to the outer surface of the anode. The built-in air channels of the anode include several longitudinal air channels 10-1 arranged along the gas flow direction and several horizontal air channels 10-2 arranged at intervals. The gas channels of each layer communicate with each other, and the section of the gas channel is circular, wherein the longitudinal channel 10-1 is a through hole penetrating through the anode, and the transverse channel 10-2 is an internal channel of the anode, wherein the longitudinal channel 10-1 and The interval of the transverse air passage 10-2 is an independent structural design parameter. The upper and lower surfaces of the anode base 5 are coated with narrow and long anode current collector bars 4, which are arranged along the center line in the width direction, one end of which is flush with the anode end surface, and the other end is introduced into the battery reaction area, thereby reducing the current flow on the anode base. transmission path.

As shown in FIG. 3 , the body 11 of the cathode connector 1 is a plate-shaped cover plate. The inside of the body 11 is provided with an air distribution groove 6 and an air collection groove 7 at both ends of the length direction; One end is provided with an air outlet hole 13 penetrating through the body 11 . The interior of the body 11 is provided with a plurality of ribs 8 that protrude downward. The ribs 8 are a quadrangular body with a gradual change structure and a rectangular cross section. The width of the ribs 8 gradually increases along the flow direction. The ribs 8 are arranged at intervals to form an air channel 9 , to realize the widened flow channel design that the air channel gradually narrows along the flow direction.

In this embodiment, the air channel 9 only refers to the transverse air channel along the air flow direction shown in FIG. 2 , and does not include the longitudinal channel of the air distribution groove 6 and the air collection groove 7 . The lower end surfaces of all the ribs 8 are flush with the lower end surfaces of the body 11, that is, the height of the ribs and the height of the air passage are the same as the depths of the air distribution grooves and air collection grooves on both sides; The air channel 9 is formed by the lower end surface of the connector rib and the surface of the cathode.

As shown in Figure 4, a solid oxide fuel cell structure optimization design method, based on the existing solid oxide fuel cell structure, further optimizes the structural parameters that affect the performance of the battery, so that the output performance of the battery includes the following steps:

S1: Based on the three-dimensional size parameters of each component of the solid oxide fuel cell structure, perform parametric modeling to obtain the battery geometric model;

S2: Construct the optimization problem, determine the objective function, determine the optimization variables and design space, and determine the constraints;

S3: Based on the experimental design method, construct the sample set and test set sampling points in the S2 design space;

S4: Based on the S1 battery geometric model, set the corresponding physical and chemical control equations and boundary conditions, build a simulation model and verify the rationality of the simulation results based on the performance curve data measured by the experiment; call the simulation model to calculate the samples of the sample set and the test set respectively point response value;

S5: Based on the proxy model approximation method, call the sample set input-output relationship in S4 to construct a proxy model; select the maximum relative error as the model accuracy evaluation index, and call the test set input-output relationship in S4 to evaluate the accuracy of the established proxy model;

S6: Based on the intelligent optimization algorithm, the proxy model in S5 is called to solve the optimization problem of S2, and the optimal structural parameter combination of the solid oxide fuel cell is calculated, so as to further improve the output performance of the battery on the basis of the structure of the solid oxide fuel cell promote.

In step S1, the parametric modeling object is the solid oxide fuel cell structure, and the overall three-dimensional size (length, width and height) is 90×43×11.6 mm. The main dimensions include the three-dimensional size of the anode base 90×43×4.5mm, the three-dimensional size of the electrolyte 90×38×0.03mm, the three-dimensional size of the cathode 80×38×0.02mm, and the three-dimensional size of the cathode connector 90×43×3.55mm. Among them, the rib width on the air inlet side is 1.4mm, the rib width on the air outlet side is 2.6mm, the rib height is 1.5mm, and the rib length is 80mm. The three-dimensional size of the anode collector bar is 45×4×0.015mm.

Step S2 constructs an optimization problem by determining the objective function, the number of optimization variables and their value ranges, and constraints, and the specific form is:

maxP _cell (x)

x=(d ₁ ,d ₂ ,d ₃ ,d ₄ ,d ₅ ,d ₆ )

std ₁ ∈ [1,2); d ₂ ∈ [2,3];

d ₃ ∈ [2,10]; d ₄ ∈ [5,90];

d ₅ ∈ [0.2,0.6]; d ₆ =[1.5,2.5]; d ₇ =[5,15];

d ₁ +d ₂ =4

The optimization problem constructed takes the battery output power under operating temperature and operating voltage as the objective function, and determines the structural parameters of the rib width d ₁ on the air inlet side of the cathode connector, the rib width d ₂ on the air outlet side of the cathode connector, and the anode current collector The strip width d ₃ , the length of the anode collector bar d ₄ , the inner diameter of the gas channel in the anode matrix d ₅ , the vertical air channel arrangement interval d ₆ in the anode matrix, and the transverse air channel arrangement interval d ₇ are optimization variables. Within the design range, the value range of each structural parameter is determined separately, and the total cross-sectional size of the ribs is controlled to be consistent through equational constraints. It should be noted that the number of longitudinal air channels and the number of horizontal air channels built into the anode are used as intermediate variables, which are determined by the aperture and interval.

Step S3 uses the optimal Latin hypercube test design method to generate sampling points for the sample set and the test set respectively, and the specific steps are:

S31: Perform normalization processing on the value range of each optimization variable, and map the range of each variable to the interval [0,1];

S32: In the 7-dimensional sample space composed of 7 optimization variables, divide each dimension into m intervals, so that the probability of each interval is the same;

S33: random sampling in each interval of each optimization variable;

S34: Randomly pair the values to ensure that each level of a factor is studied only once, and apply an orthogonality criterion to achieve better space filling characteristics, and generate a sample set containing m sampling points;

S35: Denormalize the extracted points according to the value range of each variable, and map them to the real design space;

S36: Repeat the above steps to generate test set sampling points.

In step S4, the simulation model is a multi-physics coupling model, and the specific steps for constructing the simulation model are:

S41: Define the physical parameters corresponding to the materials of gas, air and battery components;

S42: Set corresponding control equations and boundary conditions on different domains and boundaries of the parametric model of the solid oxide fuel cell structure;

Among them, the control equation comprehensively considers the coupling relationship between the electrochemical reaction, charge transfer, mass transfer, momentum transfer, and energy transfer process; further, the electrochemical reaction process takes into account the contact resistance between the cathode connector and the cathode; the mass transfer process is in On the basis of mutual diffusion between molecules, the Knudsen diffusion between gas molecules and porous medium (electrode) pore walls is also considered; the energy transfer process is based on heat conduction and heat convection, and the surface-to-surface heat between the battery and the connector is also considered radiation effect. The flow inlet boundary condition and the pressure outlet boundary condition are selected for the gas flow. At the same time, the corresponding gas component mole fraction is set at the gas inlet and outlet, the corresponding potential boundary condition is set at the cathode and anode boundaries, and the corresponding temperature boundary conditions are set on each boundary of the battery. ;

S43: Mesh the geometric structure of the model, and calculate the numerical solution of the partial differential equation problem for each sub-region after meshing based on the finite element method; carry out grid-independent analysis, and determine the appropriate value according to the error of the simulation results under different mesh numbers number of grids;

S44: Carry out a battery performance experiment, obtain the current-voltage polarization curve of the battery at the working temperature, and check the accuracy of the simulation model based on the experimental curve;

S45: According to the combination of structural parameters of each sampling point in the sample set and test set in S3, update the model structure and adaptively adjust the grid, solve the response value of each sampling point based on multi-physics coupling simulation, and construct the sample set and test set. power mapping.

In step S5, the proxy model approximation method is the Kriging approximation method, and the constructed Kriging approximation model is a semi-parametric difference model. The general idea of Kriging is to predict the unknown point based on the weighted summation of the information of other points around the unknown point The response value of , through the action of the correlation function, has the characteristics of local estimation, and the specific steps are:

S51: Construct a proxy model through each sampling point X={x ₁ ,x ₂ ,…,x _m } ^T in the sample set and its corresponding response value y={y ₁ ,y ₂ ,…,y _m } ^T to realize the The response value of the unknown point x _new is predicted. Determine the Kriging model form y(x)=f(x) ^T β+Z(x), where y(x) is the response function, determined by the deterministic regression function f(x) ^T β and the random process function Z(x) ; Z(x) obeys normal distribution, its mean value is 0, variance is σ ² ;

为数据点之间的相关函数，固定基函数指数值为2，n＝7表示优化变量的个数，

表示样本集数据点中任意两点中第k个分量之间的距离，θ_k为待估计的用于拟合模型的相关性参数；S52: Define the covariance function Cov[z(x _i ), z(x _j )]=σ ² R(θ,x _i ,x _j ) provides an approximation to a certain local deviation in the design space, where R(θ,x _i , x _j ) is the correlation function of any two data points. This embodiment provides Gauss basis functions

is the correlation function between data points, the fixed basis function index value is 2, n=7 represents the number of optimization variables,

Indicates the distance between the kth component of any two points in the sample set data points, θ _k is the correlation parameter to be estimated for fitting the model;

S53: Determine θ based on maximum likelihood estimation;

S54: call the constructed Kriging approximate model, predict the response value of each sampling point on the test set based on the spatial correlation between the point to be predicted and each sample point, and judge whether the prediction results and simulation results of each point meet the error requirements, if not If it is satisfied, re-do the S3 experimental design and increase the number of sampling points in the sample set.

In step S6, the intelligent optimization algorithm is the gray wolf intelligent optimization algorithm, which is a swarm intelligent optimization algorithm that simulates the cooperative hunting of prey by wolves (the optimal solution). The algorithm takes the optimal solution with the best current fitness as α, and the second optimal The solution and the suboptimal solution are regarded as β and δ, and the remaining candidate solutions are classified as ω. The hunting (search) process is led by α, β and δ cooperate, and ω follows. The main steps in the optimization process are as follows:

S61: Randomly initialize the wolf pack X;

S62: Calculate the fitness of gray wolf individuals, and set the top three wolf individuals with the best fitness in the current step as α, β and δ;

S63: Update the current position of the wolf pack, and the wolf pack moves closer to the head wolf;

S64: Calculate the fitness of all gray wolves;

S65: update α, β and δ;

S66: Satisfy the tolerance criterion or the maximum number of iterations, and output the optimization result.

In step S6, the battery geometric structure is updated according to the optimal parameter combination obtained by the optimization algorithm, and the three-dimensional simulation calculation is performed to check whether the error between the prediction result of the proxy model and the simulation result meets the requirements. If the error requirements are met, the optimization ends and the battery optimal Structural parameters and corresponding battery output performance; if not satisfied, add this group of simulation data to the sample set, rebuild the proxy model, and continue to optimize until the error requirements are met.

The embodiments described above have described the technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. All within the scope of the principles of the present invention Any modifications, supplements and equivalent replacements should be included within the protection scope of the present invention.

Claims (9)

1. The solid oxide fuel cell structure is characterized by comprising an anode matrix (5), wherein the upper surface and the lower surface of the anode matrix (5) are respectively provided with an anode current collecting strip (4), an electrolyte (3), a cathode (2) and a cathode connector (1) in sequence, and the whole structure is symmetrical;

the inside of the anode matrix (5) is provided with two layers of gas passages (10) with a well-shaped structure, and the inside of each layer of gas passage (10) is communicated with each other; the electrolyte (3) is coated on the upper surface and the lower surface of the anode matrix (5), and the anode current collecting strip (4) is clamped between the electrolyte (3) and the anode matrix (5); the anode current collecting strips (4) are arranged along the central line of the width direction of the anode matrix (5); the cathode (2) is coated on the outer surface of the electrolyte (3);

the cathode connector (1) is provided with a plurality of ribs (8) which are arranged at intervals on one side facing the cathode (2), and the width of the ribs (8) is gradually enlarged along the gas flow direction, so that the width of an air passage (9) in the gas flow direction is gradually reduced.

2. The solid oxide fuel cell structure according to claim 1, wherein the anode substrate (5) and the cathode (2) are made of porous metal ceramic composite materials, the electrolyte (3) is made of ceramic materials, and the cathode connector (1) and the anode current collector (4) are made of high-conductivity metal or alloy materials and are resistant to high temperature; the anode substrate (5) is further subdivided into a middle supporting layer for supporting and internally arranging a gas flue (10), and two side active layers which are in contact with the electrolyte (3) for electrochemical reaction, wherein the material compositions of different functional layers are consistent, and the component proportions of the materials in the different functional layers are different.

3. The solid oxide fuel cell structure according to claim 1, wherein the inside of each layer of gas passages (10) is communicated with the originally independent longitudinal gas passages (10-1) by arranging transverse gas passages (10-2) which are arranged at intervals, thereby forming the gas passages (10) of the mutually communicated cross-shaped structure;

the radius of the section of the gas air passage (10) is 0.2-0.6 mm, the interval of the longitudinal air passages (10-1) is 1.5-2.5 mm, and the interval of the transverse air passages (10-2) is 5-15 mm.

4. The solid oxide fuel cell structure according to claim 1, characterized in that the anode collector bar (4) is an elongated narrow bar, one end of which is flush with the end face in the length direction of the anode base body (5), and the other end of which extends to the cell reaction zone between the anode base body (5) and the electrolyte (3), and the electrical conductivity of which is higher than that of the anode.

5. The solid oxide fuel cell structure according to claim 1, characterized in that the cathode connector (1) comprises a body (11) and a plurality of ribs (8) arranged at intervals inside the body (11); the outer end surfaces of the ribs (8) are closely attached to the surface of the cathode (2), and a plurality of air passages (9) are formed between the spacing areas among the ribs (8) and the surface of the cathode (2); the cross sections of the ribs (8) and the air passages (9) are rectangular;

an air distribution groove (6) and an air collection groove (7) are respectively arranged at two ends of the inside of the body (11) in the length direction; one end of the air distribution groove (6) is provided with an air inlet hole (12) penetrating through the body (11), and one end of the air collection groove (7) far away from the air inlet hole (12) is provided with an air outlet hole (13) penetrating through the body (11).

6. A solid oxide fuel cell structure according to claim 1, characterized in that the rib width on the air inlet side is 1-2 mm and the rib width on the air outlet side is 2-3 mm, and the sum of the sectional widths of each air passage (9) and its adjacent ribs (8) is fixed.

7. A method for optimizing the design of a solid oxide fuel cell structure according to any one of claims 1 to 6, comprising the steps of:

s1: based on three-dimensional size parameters of each component of the solid oxide fuel cell structure, parametric modeling is carried out to obtain a cell geometric model;

s2: constructing an optimization problem, determining an objective function, determining an optimization variable and a design space, and determining constraint conditions;

specifically, determining output power as an objective function; respectively selecting the width of the rib at the air inlet side of the cathode connector, the width of the rib at the air outlet side of the cathode connector, the width of the anode current collecting strip, the length of the anode current collecting strip, the inner diameter of the gas channel in the anode matrix, the arrangement interval of the longitudinal gas channel in the anode matrix and the arrangement interval of the transverse gas channel as optimization variables; based on the overall structure requirement of the battery, designing the value range of each optimized variable, and determining corresponding constraint conditions;

s3: based on a test design method, a sample set and a test set sampling point are constructed in a design space of S2;

s4: setting corresponding physical and electrochemical control equations and boundary conditions based on the battery geometric model established in the step S1, constructing a simulation model, and verifying the rationality of a simulation result based on the performance curve data measured by experiments; calling a simulation model to respectively calculate response values of sampling points of a sample set and a test set;

s5: based on a Kriging proxy model approximation method, invoking a sample set input-output relation in S4 to construct a proxy model; invoking the input-output relation of the test set in S4 to evaluate the accuracy of the proxy model, judging whether the response value and the simulation result of the proxy model on each sampling point of the test set meet the error requirement, if not, carrying out S3 test design again, and increasing the sampling point number of the sample set;

s6: based on a gray wolf intelligent optimization algorithm, invoking the agent model constructed in the step S5 to solve the optimization problem of the step S2, updating the battery geometric structure according to the obtained optimal parameter combination, performing three-dimensional simulation calculation, checking whether the error between the agent model prediction result and the simulation result meets the requirement, and if the error meets the error requirement, finishing optimization, and outputting the optimal structure parameter combination of the battery; if the error requirement is not met, adding the simulation data of the group into the sample set, reconstructing the proxy model, and continuing to optimize until the error requirement is met.

8. The optimization design method according to claim 7, wherein in step S3, the sample points of the sample set and the test set are generated by using the optimal latin hypercube design method, respectively, and the specific steps are as follows:

s31: normalizing the value range of each optimized variable, and mapping each variable range into a [0,1] interval;

s32: equally dividing each dimension into m intervals in a 7-dimensional sample space consisting of 7 optimization variables, so that the probability of each interval is the same;

s33: randomly sampling in each interval of each optimization variable;

s34: the values are randomly paired, each level of a factor is guaranteed to be researched only once, an orthogonality criterion is applied to achieve better space filling characteristics, and a sample set containing m sampling points is generated;

s35: inversely normalizing the extracted points according to the value range of each variable, and mapping the extracted points into a real design space;

s36: repeating the steps to generate test set sampling points.

9. The optimization design method according to claim 7, wherein in step S4, the simulation model is a multi-physical field coupling model, and the specific steps of constructing the simulation model are as follows:

s41: defining physical parameters corresponding to materials of each part of the fuel gas, the air and the battery;

s42: setting corresponding control equations and boundary conditions on different domains and boundaries of a parameterized model of the solid oxide fuel cell structure;

s43: performing grid division on the model geometric structure, and calculating partial differential equation problem numerical solutions for all subareas after grid division based on a finite element method; performing grid independence analysis, and determining the grid number according to simulation result errors under different grid numbers;

s44: performing a battery performance experiment, obtaining a current-voltage polarization curve of the battery at the working temperature, and checking the accuracy of a simulation model based on the experimental curve;

s45: and (3) updating the simulation model structure and adaptively adjusting grids according to the structural parameter combination of each sampling point in the sample set and the test set in the S3, solving the response value of each sampling point based on multi-physical field coupling simulation, and constructing the mapping relation between each sampling point and power in the sample set and the test set.

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