Elliptical wave-shaped flow channel structure of solid oxide fuel cell and optimization method of elliptical wave-shaped flow channel structure

Abstract

The invention discloses an elliptical wave-shaped runner structure of a solid oxide fuel cell and an optimization method of the elliptical wave-shaped runner structure, the runner structure comprises a cathode connecting piece, a single cell and an anode connecting piece which are sequentially arranged from top to bottom, the cathode connecting piece is connected with the single cell to form a cathode runner, and the anode connecting piece is connected with the single cell to form an anode runner; the anode connecting piece is connected with the single battery to form an anode flow channel; projections of the cathode flow channels and the anode flow channels on the surfaces of the single cells are rectangular; and the surfaces of one sides, far away from the single cells, of the cathode flow channels and the surfaces of one sides, far away from the single cells, of the anode flow channels are wavy concave-convex curved surfaces. The flow channel structure disclosed by the invention can reduce the pressure drop of the flow channel, improve the non-uniform distribution of gas in the flow channel, improve the mass transfer efficiency, promote heat exchange and improve the performance of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of solid oxide fuel cells, and in particular to an elliptical wave-shaped flow channel structure of a solid oxide fuel cell and an optimization method thereof. Background Art

[0002] A fuel cell is a green power generation device that directly converts the chemical energy of reactants into electrical energy. It has the advantages of being clean, efficient, and having high power density, and has become one of the important research directions in the energy field. Among them, solid oxide fuel cells are one of the most widely used fuel cells. Solid oxide fuel cells have the advantages of wide fuel adaptability, high energy conversion efficiency, all-solid-state, modular assembly, zero pollution, and fuel cell power generation is not limited by the Carlo cycle. Its theoretical conversion efficiency can reach 85% to 90%, and it has broad application prospects in distributed power generation, communications, aerospace, and transportation.

[0003] The gas transmission process inside the fuel cell is referred to as the mass transfer process. The gas inside the fuel cell is transmitted by convection, diffusion, etc., which can be divided into convection transmission of gas in the flow channel and diffusion transmission of gas in the electrode pores. The quality of reactant transmission directly affects the performance of the fuel cell stack. The appropriate material selection and reasonable flow channel structure design of the fuel cell can improve the gas mass transmission performance inside the fuel cell stack and the gas transport in the porous medium, thereby improving the performance of the fuel cell stack.

[0004] At present, the performance optimization of solid oxide fuel cells is mainly divided into two aspects: material optimization and structural optimization. Material optimization targets various components of the battery, including electrolyte materials, electrode materials, interface optimization, etc. Electrode performance can be further optimized through strategies such as material nano-sizing, alloying, or exploring and developing new electrode materials with high electronic and ionic conductivity, and introducing rare earth elements.

[0005] Structural design optimization mainly optimizes the geometry of the flow channel, increases the contact time between the gas and the electrode surface through multi-stage flow channel design, microchannel technology, etc., improves the mass transfer efficiency of the reaction, and reduces the pressure drop and improves the heat and mass transfer efficiency by reducing the flow resistance.

[0006] The traditional direct flow channel design has certain limitations, such as short contact time between gas and electrode surface, uneven distribution of flow channel gas, and large pressure drop of flow channel gas, which have a negative impact on the mass transfer efficiency and output power of the battery. In addition, the uneven distribution of flow channel gas will also cause insufficient fuel and oxidant in the middle and rear sections of the flow channel, which will lead to uneven temperature distribution, increase thermal stress, affect stability and durability, and ultimately affect the performance and life of the battery. Summary of the invention

[0007] Purpose of the invention: The technical problem to be solved by the present invention is to provide an elliptical wave-shaped flow channel structure of a solid oxide fuel cell and an optimization method thereof in view of the deficiencies in the prior art, so as to reduce the pressure drop in the flow channel, improve the uneven distribution of gas in the flow channel, improve the mass transfer efficiency, promote heat exchange, and improve the performance of the battery.

[0008] In order to solve the above technical problems, the first aspect of the present invention discloses an elliptical wavy flow channel structure of a solid oxide fuel cell, which includes a cathode connector, a single cell and an anode connector arranged in sequence from top to bottom, the cathode connector is connected to the single cell to form a cathode flow channel, and the anode connector is connected to the single cell to form an anode flow channel; the projections of the cathode flow channel and the anode flow channel on the surface of the single cell are both rectangular; the surface of the cathode flow channel on one side away from the single cell and the surface of the anode flow channel on one side away from the single cell are both wavy concave-convex surfaces.

[0009] Specifically, the projection curve of the wavy concave-convex curved surface includes a concave curve segment and a convex curve segment, the concave curve segment and the convex curve segment are both semi-elliptical arc segments, and the line between the two end points of the semi-elliptical arc segment is the major axis of the ellipse; along the major axis direction of the ellipse, the concave curve segments and the convex curve segments are alternately arranged and sequentially connected;

[0010] In the cathode flow channel and the anode flow channel, the concave curve segment and the convex curve segment are both semi-elliptical arc segments with the same major axis and the same minor axis; the cathode flow channel and the anode flow channel have the same flow channel height and the same flow channel width.

[0011] Specifically, the cathode flow channel is arranged opposite to the anode flow channel.

[0012] Specifically, a plurality of cathode flow channels are provided, and the plurality of cathode flow channels are arranged side by side.

[0013] Specifically, the anode connector includes an anode surface for connecting to the single cell and a flow channel opened on the anode surface; the cathode connector includes a cathode surface for connecting to the single cell and a flow channel opened on the anode surface; the single cell includes a cathode current collecting layer, a cathode functional layer, an electrolyte layer, an anode functional layer and an anode current collecting layer stacked in sequence, the cathode current collecting layer covers the flow channel of the cathode connector to form the cathode flow channel; the anode current collecting layer covers the flow channel of the anode connector to form the anode flow channel.

[0014] A second aspect of the present invention discloses a method for optimizing the elliptical wave-shaped flow channel structure of the solid oxide fuel cell as described above, the optimization method comprising:

[0015] S1. Establish an objective function according to the optimization goal, determine the optimization variables and the corresponding value range, the optimization goal is the current density and output power when the molar production or consumption rate of oxygen ions caused by the electrochemical reaction in the solid oxide fuel cell is optimal; the objective function is the molar production or consumption rate of oxygen ions caused by the electrochemical reaction, and the optimization variables are the structural parameters of the flow channel structure; establish a three-dimensional structural model of a solid oxide fuel cell having the battery flow channel structure as claimed in claim 1 in COMSOL, and verify the structural performance of the three-dimensional structural model;

[0016] S2, establishing a proxy model of the mapping relationship between the optimization variables and the objective function, so as to establish a relationship between the structural parameters and the objective function of the optimization target;

[0017] S3, using the optimal Latin hypercube sampling method to generate multiple sets of optimized variable parameters, bringing the multiple sets of optimized variable parameters into the three-dimensional structure model for modeling, and obtaining a model database;

[0018] S4. Using the proxy model to simulate the model database, obtain a Pareto optimal solution; the Pareto optimal solution corresponds to structural parameters of the flow channel structure when the molar production or consumption rate of oxygen ions is optimal.

[0019] Specifically, the optimization variables include the major axis length r, the flow channel height h 1 , semi-minor axis length h 2 and flow channel width l 1 .

[0020] Specifically, the value range of the optimization variable is as follows:

[0021] 0≤h 1 ≤1mm;

[0022] 0≤h 2 ≤0.8mm;

[0023] 0≤l 1 ≤1mm;

[0024] 0≤r≤0.8mm;

[0025] r≥h 2 ≥0.

[0026] Specifically, the elliptical flow channel curve of the flow channel structure satisfies the following relationship:

[0027]

[0028]

[0029] Where x and y are the coordinates of the point on the ellipse, c is the distance from the center of the ellipse to the focus, r is the length of the major axis, and h is the distance from the center of the ellipse to the focus. 2 is the flow channel height.

[0030] Specifically, if substance i is used to represent oxygen ions, the total molar flow rate of substance i during the diffusion process is expressed as follows:

[0031]

[0032] Where ci is the molar concentration of substance i; c tot is the total molar concentration of the binary mixture; R is the gas parameter; T is the thermodynamic temperature; p is the total gas pressure; k is the permeability coefficient; x 1 and x 2 are the mole fractions of substance 1 and substance 2, is the concentration gradient, μ is the viscosity coefficient; and are the effective Knudsen diffusion coefficients of substance 1 and substance 2, respectively; are the effective binary diffusion coefficients of species 1 and 2.

[0033] and It can be expressed as follows:

[0034]

[0035]

[0036]

[0037] Where ε is the porosity; τ is the curvature factor; r g is the radius of the hole; V 1 and M 1 are the diffusion volume and molar mass of substance 1, V 2 and M 2 are the diffusion volume and molar mass of substance 2 respectively; r el is the average electron conducting particle radius; r io is the average ion particle radius; is the volume fraction of the conductive electron particles in the composite electrode, is the volume fraction of conductive ion particles in the composite electrode;

[0038] The molar mass conservation equation for substance i transferred during the battery chemical reaction process is as follows:

[0039]

[0040] Among them, ASL represents anode support layer, CCCL represents cathode contact layer, AFL represents anode functional layer, and CFL represents cathode functional layer; represents the flux change of substance i under different conditions: in the anode support layer or cathode contact layer, the flux change is zero; while in the anode functional layer or cathode functional layer, the flux changes Equal to the molar production or consumption rate of oxygen ions R i ;

[0041] The specific relationship between the molar production or consumption rate of oxygen ions caused by electrochemical reactions in SOFC and the current density J and power density P is as follows:

[0042]

[0043] P=2R i FV

[0044] In the formula, R i represents the molar production or consumption rate of oxygen ions, F represents the Faraday constant, I represents the current, A represents the effective reaction area, and V represents the single cell voltage.

[0045] Beneficial effects:

[0046] 1) Compared with the traditional long straight rectangular flow channel, the elliptical wave flow channel structure disclosed in this application can promote the uniform distribution of gas in the reaction gas flow field, thereby having a higher flow rate mass transfer efficiency and a more uniform pressure distribution inside the flow field. The pressure drop loss of gas flowing through the flow channel is small, and the mass fraction of the gas path outlet is also better than that of the traditional flow channel structure. These help to improve the output power and current density of the battery.

[0047] 2) This application uses the SPEA2 multi-objective genetic algorithm using a proxy model to quantify the optimal structural parameters of the flow channel structure to meet the goals of optimal battery power density and oxygen uniformity. The design method is reasonable, the calculation efficiency is high, and the results are highly accurate.

[0048] 3) This application uses the molar rate of oxygen ion production or consumption to characterize the structural performance of the solid oxide fuel cell stack, which can more intuitively reflect the electrochemical reaction activity compared to other structures; it is directly related to the speed of the electrochemical reaction and can intuitively reflect the activity and reaction rate of the electrode. By measuring the molar rate of oxygen ions, the effects of different operating conditions, electrode materials or designs on the reaction rate can be evaluated, thereby optimizing battery performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more clear.

[0050] Figure 1 A three-dimensional structural diagram of an elliptical wavy flow channel structure of a solid oxide fuel cell provided in one embodiment of the present invention.

[0051] Figure 2 for Figure 1 An anatomical side view of an elliptical wavy flow channel structure of a solid oxide fuel cell is shown;

[0052] Figure 3 for Figure 2 A left side view of an elliptical wave-shaped flow channel structure of a solid oxide fuel cell shown;

[0053] Figure 4 For along Figure 3 Sectional view along line AA;

[0054] Figure 5 A flowchart of a method for optimizing the elliptical wave-shaped flow channel structure of a solid oxide fuel cell provided by the present invention.

[0055] Figure 6 4 is a flowchart of the SPEA2 multi-objective optimization method used in an embodiment of the present invention.

[0056] Figure 7 To adopt Figure 1 Current density performance curve of the solid oxide fuel cell with the flow channel structure shown.

[0057] Figure 8 To adopt Figure 1 Output power density performance curve of the solid oxide fuel cell with the channel structure shown.

[0058] The description of the accompanying drawings is:

[0059] r, major axis length; h 1 , flow channel height; h 2 , semi-minor axis length; l 1 , channel width; 1, cathode connector; 11, cathode channel; 2, single cell; 21, cathode current collecting layer; 22, cathode functional layer; 23, electrolyte layer; 24, anode functional layer; 25, anode current collecting layer; 3, anode connector; 31, anode channel. DETAILED DESCRIPTION

[0060] In the flow channel structure of existing solid oxide fuel cells, the cathode flow channel and the anode flow channel are usually long straight rectangular flow channels. This type of flow channel structure has the problems of uneven flow channel gas distribution, low mass transfer efficiency, large flow channel pressure drop loss, and affects stability and durability.

[0061] See also Figures 1 to 3In order to improve the uneven distribution of gas in the flow channel, improve the mass transfer efficiency, promote heat exchange, and improve the performance of the battery, the first aspect of the embodiment of the present invention provides an elliptical wave-shaped flow channel structure of a solid oxide fuel cell, which includes a cathode connector 1, a single cell 2, and an anode connector 3 arranged in sequence from top to bottom. The cathode connector 1 is connected to the single cell 2 to form a cathode flow channel 11, and the anode connector 3 is connected to the single cell 2 to form an anode flow channel 31. The projections of the cathode flow channel 11 and the anode flow channel 31 on the surface of the single cell 2 are both rectangular. The side surface of the cathode flow channel 11 away from the single cell 2 and the side surface of the anode flow channel 31 away from the single cell 2 are both wavy concave-convex curved surfaces.

[0062] In this embodiment, the wavy concave-convex curved surface provides a larger surface area, which helps to increase the contact time and area between the fluid and the flow channel wall, thereby promoting more efficient heat exchange and enhancing disturbance, thereby enhancing mass transfer efficiency.

[0063] At the same time, along the gas flow direction, the gas is periodically decelerated under the action of the convexity, producing a Bernoulli effect, so that the gas pressure drop in the entire flow channel is reduced compared to the straight flow channel, and the gas is more evenly distributed.

[0064] For details, see Figure 3 The projection curve of the wavy concave-convex surface includes a concave curve segment and a convex curve segment, both of which are semi-elliptical arc segments, and the line between the two end points of the semi-elliptical arc segment is the major axis of the ellipse. Along the major axis direction of the ellipse, the concave curve segments and the convex curve segments are alternately arranged and connected in sequence.

[0065] In this embodiment, the concave curve segment and the convex curve segment are both semi-elliptical arc segments, which allows the fluid to pass through the flow channel more smoothly. Compared with the traditional long straight rectangular flow channel, it can reduce the resistance and energy loss in the fluid flow and achieve a more uniform temperature distribution in the flow channel.

[0066] This three-dimensional elliptical wave-shaped flow field effectively improves the uneven distribution of gas in the flow channel, improves mass transfer efficiency, promotes heat exchange, and improves battery performance.

[0067] For details, see Figure 3 In the cathode flow channel 11 and the anode flow channel 31, the concave curve segment and the convex curve segment are both semi-elliptical arc segments with the same major axis and the same minor axis; the cathode flow channel 11 and the anode flow channel 31 have the same flow channel height and the same flow channel width.

[0068] In the present application, the flow channel height refers to the distance from the end point of the semi-elliptical arc segment to the single cell 2 .

[0069] Specifically, see Figure 3 The cathode flow channel 11 and the anode flow channel 31 are arranged opposite to each other.

[0070] Specifically, see Figure 3 There are multiple cathode flow channels 11, and the multiple cathode flow channels 11 are arranged side by side.

[0071] For details, see Figure 1 , the anode connector 3 includes an anode surface for connecting to the single cell 2 and a flow channel groove opened on the anode surface of the anode connector 3. The cathode connector 1 includes a cathode surface for connecting to the single cell 2 and a flow channel groove opened on the anode surface of the cathode connector 1. The single cell 2 includes a cathode current collecting layer 21, a cathode functional layer 22, an electrolyte layer 23, an anode functional layer 24 and an anode current collecting layer 25 stacked in sequence, the cathode current collecting layer 21 covers the flow channel groove of the cathode connector 1 to form a cathode flow channel 11; the anode current collecting layer 25 covers the flow channel groove of the anode connector 3 to form an anode flow channel 31.

[0072] See also Figure 3 and Figure 4 , let the length of the major axis of the semi-ellipse segment be r, and let the length of the semi-minor axis be h 2 , let the flow channel height be h 1 , assuming the channel width is l 1 .

[0073] In order to obtain the optimal solution of the flow channel structure provided by the present invention, the second aspect of the embodiment of the present invention provides an optimization method for the elliptical wave-shaped flow channel structure of a solid oxide fuel cell, see Figure 5 , the optimization method comprises the following steps:

[0074] S1. Establish an objective function according to the optimization goal, determine the optimization variables and the corresponding value range, the optimization goal is the current density and output power when the molar production or consumption rate of oxygen ions caused by the electrochemical reaction in the solid oxide fuel cell is optimal; the objective function is the molar production or consumption rate of oxygen ions caused by the electrochemical reaction, and the optimization variables are the structural parameters of the flow channel structure; establish a three-dimensional structural model of a solid oxide fuel cell having the above-mentioned novel elliptical wavy flow channel structure in COMSOL, and verify the structural performance of the three-dimensional structural model.

[0075] S2, establishing a proxy model of the mapping relationship between the optimization variables and the objective function, so as to establish a relationship between the structural parameters and the objective function of the optimization target;

[0076] S3, using the optimal Latin hypercube sampling method to generate multiple sets of optimized variable parameters, bringing the multiple sets of optimized variable parameters into the three-dimensional structure model for modeling, and obtaining a model database;

[0077] S4. Utilizing the proxy model to simulate the model database, and applying the SPEA2 method to perform multi-objective parameter optimization, to obtain a Pareto optimal solution; the Pareto optimal solution corresponds to the structural parameters of the flow channel structure when the molar production or consumption rate of oxygen ions is optimal.

[0078] The SPEA2 method is a classic multi-objective optimization algorithm. It is an algorithm for fitness value allocation and selection based on the concept of Pareto dominance. The SPEA2 algorithm uses a niche method and an external archive elite retention mechanism. It has a strong convergence ability, and the resulting solution set also has good distribution. The advantage of the SPEA2 algorithm in this field is that it has a clear framework, is easy to implement, can simplify the optimization process, and maintains the diversity and stability of the solution.

[0079] The embodiment of the present invention uses the molar production or consumption rate R of oxygen ions caused by electrochemical reaction i As the objective function. The better the gas transport in the porous medium, the more ideal the electrochemical reaction rate in the functional layer and at the electrode / electrolyte interface, and the better the solid oxide fuel cell performance. The embodiments of the present invention compare the gas flow velocity distribution inside the flow channel when different optimization solutions of the solid oxide fuel cell correspond to the flow channel under a fixed gas flow rate and a constant voltage, and the electrochemical reaction rate occurring in the functional layer and at the interface between the electrode and the electrolyte, which is directly reflected in the current density and output power of the solid oxide fuel cell. The structural parameters corresponding to the current density and output power of the solid oxide fuel cell correspond to the optimal solution.

[0080] Specifically, the optimization variables include the major axis length r, the flow channel height h 1 , semi-minor axis length h 2 and flow channel width l 1 .

[0081] Specifically, the value range of the optimization variable is as follows:

[0082] 0≤h 1 ≤1mm;

[0083] 0≤h 2 ≤0.8mm;

[0084] 0≤l 1 ≤1mm;

[0085] 0≤r≤0.8mm;

[0086] r≥h 2 ≥0.

[0087] Specifically, the elliptical flow channel curve of the flow channel structure satisfies the following relationship:

[0088]

[0089]

[0090] Where x and y are the coordinates of the point on the ellipse, c is the distance from the center of the ellipse to the focus, r is the length of the major axis, and h is the distance from the center of the ellipse to the focus. 2 is the flow channel height.

[0091] Specifically, the objective function is the molar production or consumption rate of oxygen ions caused by the electrochemical reaction. The gas transport process in the flow channel of the solid oxide fuel cell is an important phenomenon involving multiple links. If the substance i represents the oxygen ions, the total molar flow rate of substance i in the diffusion process is expressed as follows:

[0092]

[0093] Where ci is the molar concentration of substance i; c tot is the total molar concentration of the binary mixture; R is the gas parameter; T is the thermodynamic temperature; p is the total gas pressure; k is the permeability coefficient; x 1 and x 2 are the mole fractions of substance 1 and substance 2, is the concentration gradient, μ is the viscosity coefficient; and are the effective Knudsen diffusion coefficients of substance 1 and substance 2, respectively; is the effective binary diffusion coefficient of substance 1 and substance 2; substance 1 and substance 2 represent two different gas or vapor components involved in the porous electrode of the solid oxide fuel cell, for example, substance 1 can be hydrogen and substance 2 can be water vapor.

[0094] and It can be expressed as follows:

[0095]

[0096]

[0097]

[0098] Where ε is the porosity; τ is the curvature factor; r g is the radius of the hole; V 1 and M 1 are the diffusion volume and molar mass of substance 1, V 2 and M 2 are the diffusion volume and molar mass of substance 2 respectively; r el is the average electron conducting particle radius; r io is the average ion particle radius; is the volume fraction of the conductive electron particles in the composite electrode, is the volume fraction of conductive ion particles in the composite electrode.

[0099] The comprehensive transport molar flow rate of substance i in porous media is expressed as follows:

[0100]

[0101] In the formula, is the component of molar flow rate due to friction, is the molar flow component caused by the variation, is the equivalent diffusion coefficient of substance i; is the equivalent permeability coefficient of the binary mixture.

[0102] The molar mass conservation equation for substance i transferred during the battery chemical reaction process is as follows:

[0103]

[0104] Among them, ASL represents anode support layer, CCCL represents cathode contact layer, AFL represents anode functional layer, and CFL represents cathode functional layer; represents the flux change of substance i under different conditions: in the anode support layer or cathode contact layer, the flux change is zero; while in the anode functional layer or cathode functional layer, the flux changes Equal to the molar production or consumption rate of oxygen ions R i .

[0105] It can be seen from this that the total molar flow rate of oxygen ions N i Total molar mass with oxygen ions According to the conservation equation of the molar mass of oxygen ions, it can be known that the conservation equation of the molar mass of oxygen ions is positively correlated with the generation rate R of oxygen ions. i Positive correlation.

[0106] The specific relationship between the molar production or consumption rate of oxygen ions caused by electrochemical reactions in SOFC and the current density J and power density P is as follows:

[0107]

[0108] P=2R i FV

[0109] In the formula, R i represents the molar production or consumption rate of oxygen ions, F represents the Faraday constant, I represents the current, A represents the effective reaction area, and V represents the single cell voltage.

[0110] Specifically, see Figure 6, This embodiment uses SPEA2 as a multi-objective optimization algorithm to obtain the structural parameters corresponding to the current density and output power of the optimal solid oxide fuel cell.

[0111] S41. Initialize the population. Let the initial population be P. o , let the empty data set be , let the maximum number of iterations be T, let the initial number of iterations be t, t=0.

[0112] S42, applying the agent model to calculate the optimization variables and the fitness of the individuals;

[0113]

[0114]

[0115] In the formula, S(i) is a set, M(i) is a summation function, and P i represents the i-th member in the current population, The expression refers to adding or merging the i-th member with itself, depending on P i Data structures and specific implementation algorithms; It is a screening mechanism for set construction, which selects j belonging to And Xiaoi, Limit the range of the sum. YesP t and A collection of .

[0116] S43, environment selection: the tth corresponding P t and Copy all non-dominated solution sets in In, judge Is the number greater than If the data set is larger than , the corresponding pruning operation will be performed; otherwise, P o and P n Add the dominating solution set in P n , proceed to the next step; where P o represents the individuals in the population, P n Represents the combination of individuals in a population.

[0117] S44. If t>T or other termination conditions are met, A is used as P t+1 The decision variable set represented by the non-dominated solution is output, that is, A represents the decision variable set; other termination conditions are selected from any one of the following: the population diversity is too low, a specific performance standard is met, and a time limit predetermined by the algorithm is reached.

[0118] S45, select operation, for P t+1The tournament selection is carried out and placed into the pairing pool for effective genetic operations to produce new individuals, thereby driving the population to evolve towards the optimal solution.

[0119] S46, pair the individuals in the pool for recombination and mutation, and store the results in a collection Iteration number +1 returns to S42;

[0120] S47. Use the multi-objective decision analysis method (Analytic Hierarchy Process, referred to as AHP) to screen the A set, and the oxygen ion molar production or consumption rate corresponding to the optimal solution is the optimal structural parameter.

[0121] The optimal decision variables in the decision variable set A obtained by using the SPEA2 algorithm are the optimal flow field structural parameters of the flow channel structure. The optimal structural parameters of the flow channel structure are shown in Table 1.

[0122] Table 1 Optimal structural parameters of flow channel structure

[0123] Optimal structural parameters of flow channel structure value <![CDATA[Flow channel height h 1 (mm)]]> 0.862 <![CDATA[Half minor axis length h 2 (mm)]]> 0.377 <![CDATA[Flow channel width l 1 (mm)]]> 0.651 Long axis length r(mm) 0.584

[0124] The obtained optimal flow field structure is used to design a solid oxide fuel cell, and its performance is verified as follows.

[0125] The working pressure of the fuel cell is a standard atmospheric pressure, and the working temperature is 750°C. Hydrogen with a relative humidity of 5% and a volume flow rate of 50 mL / min is introduced into the anode, and the stoichiometric ratio of the fuel electrode to the air electrode is 1:3; air is introduced into the cathode, and the intake volume flow rate is 150 mL / min. The results are obtained through COMSOL simulation.

[0126] Figure 7 and Figure 8 The current density performance curve and power density performance curve of solid oxide fuel cells are shown respectively. Figure 7 It can be seen that the current density of the solid oxide fuel cell of this embodiment increases with the decrease of the single cell voltage V. When the voltage is 0.4V, the maximum current density is 0.9341A / cm 2 The flow channel height is h 1 , the channel width is l 1 In a traditional DC channel, when the voltage is 0.4V, the corresponding current density is 0.4723A / cm 2 .from Figure 8 It can be seen that the power density of the solid oxide fuel cell of this embodiment increases with the decrease of the single cell voltage V. When the voltage is 0.4V, the maximum output power density is 0.3762W / cm 2 The flow channel height is h 1 , the channel width is l 1The maximum output power density of the conventional DC channel is 0.1855W / cm at a voltage of 0.4V. 2 It can be seen that, compared with the traditional direct flow channel, the elliptical wave-shaped flow channel structure of the solid oxide fuel cell of this embodiment can improve the mass transfer efficiency and reduce the flow channel pressure drop, thereby effectively improving the output power and current density of the fuel cell.

[0127] The present invention comprehensively considers the mass transfer efficiency and flow channel pressure drop of the solid oxide fuel cell stack, and adopts a wavy flow channel with a semi-elliptical segment to improve the mass transfer capacity of the reaction gas, effectively avoiding excessive attenuation of the flow channel pressure drop at the rear end of the fuel cell flow channel, and improving the battery output power. In addition, the present application also establishes a proxy model that can quickly and accurately evaluate the performance of the solid oxide fuel cell. This comprehensive consideration and optimization method not only improves the overall performance of the battery, but also makes the optimization process more efficient and accurate.

[0128] The present invention provides an elliptical wave-shaped flow channel structure of a solid oxide fuel cell and an idea and method for optimizing the same. There are many methods and ways to implement the technical solution. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention. All components not specified in this embodiment can be implemented by existing technologies.

Claims

1. An elliptical wave-shaped flow channel structure of a solid oxide fuel cell, characterized in that: The invention comprises a cathode connector (1), a single cell (2) and an anode connector (3) which are arranged in sequence from top to bottom, wherein the cathode connector (1) is connected to the single cell (2) to form a cathode flow channel (11), and the anode connector (3) is connected to the single cell (2) to form an anode flow channel (31); the projections of the cathode flow channel (11) and the anode flow channel (31) on the surface of the single cell (2) are both rectangular; and the surface of the cathode flow channel (11) on one side away from the single cell (2) and the surface of the anode flow channel (31) on one side away from the single cell (2) are both wavy concave-convex curved surfaces.

2. The elliptical wave-shaped flow channel structure of a solid oxide fuel cell according to claim 1, characterized in that: The projection curve of the wavy concave-convex curved surface includes a concave curve segment and a convex curve segment, wherein the concave curve segment and the convex curve segment are both semi-elliptical arc segments, and the line connecting the two end points of the semi-elliptical arc segment is the major axis of the ellipse; along the major axis direction of the ellipse, the concave curve segments and the convex curve segments are alternately arranged and sequentially connected; In the cathode flow channel (11) and the anode flow channel (31), the concave curve segment and the convex curve segment are both semi-elliptical arc segments having the same major axis and the same minor axis; the cathode flow channel (11) and the anode flow channel (31) have the same flow channel height and the same flow channel width.

3. The elliptical wave-shaped flow channel structure of the solid oxide fuel cell according to claim 2, characterized in that: The cathode flow channel (11) and the anode flow channel (31) are arranged opposite to each other.

4. The elliptical wave-shaped flow channel structure of the solid oxide fuel cell according to claim 3, characterized in that: A plurality of cathode flow channels (11) are provided, and the plurality of cathode flow channels (11) are arranged side by side.

5. The elliptical wave-shaped flow channel structure of the solid oxide fuel cell according to claim 4, characterized in that: The anode connector (3) comprises an anode surface for connecting to the single cell (2) and a flow channel groove provided on the anode surface; the cathode connector (1) comprises a cathode surface for connecting to the single cell (2) and a flow channel groove provided on the anode surface; the single cell (2) comprises a cathode current collecting layer (21), a cathode functional layer (22), an electrolyte layer (23), an anode functional layer (24) and an anode current collecting layer (25) stacked in sequence, the cathode current collecting layer (21) covers the flow channel groove of the cathode connector (1) to form the cathode flow channel (11); the anode current collecting layer (25) covers the flow channel groove of the anode connector (3) to form the anode flow channel (31).

6. The method for optimizing the elliptical wave-shaped flow channel structure of a solid oxide fuel cell according to claim 1, characterized in that: include: S1. Establish an objective function according to the optimization goal, determine the optimization variables and the corresponding value range, the optimization goal is the current density and output power when the molar production or consumption rate of oxygen ions caused by the electrochemical reaction in the solid oxide fuel cell is optimal; the objective function is the molar production or consumption rate of oxygen ions caused by the electrochemical reaction, and the optimization variables are the structural parameters of the flow channel structure; establish a three-dimensional structural model of a solid oxide fuel cell having the battery flow channel structure as claimed in claim 1 in COMSOL, and verify the structural performance of the three-dimensional structural model; S2, establishing a proxy model of the mapping relationship between the optimization variables and the objective function, so as to establish a relationship between the structural parameters and the objective function of the optimization target; S3, using the optimal Latin hypercube sampling method to generate multiple sets of optimized variable parameters, bringing the multiple sets of optimized variable parameters into the three-dimensional structure model for modeling, and obtaining a model database; S4. Using the proxy model to simulate the model database, obtain a Pareto optimal solution; the Pareto optimal solution corresponds to structural parameters of the flow channel structure when the molar production or consumption rate of oxygen ions is optimal.

7. The optimization method according to claim 6, characterized in that: The optimization variables include the major axis length r, the flow channel height h1, the semi-minor axis length h2 and the flow channel width l1.

8. The optimization method according to claim 7 is characterized in that: The value range of the optimization variable is as follows: 0≤h1≤1mm; 0≤h2≤0.8mm; 0≤l1≤1mm; 0≤r≤0.8mm; r≥h2≥0。 9. The optimization method according to claim 6, characterized in that: The elliptical flow channel curve of the flow channel structure satisfies the following relationship: Where x and y are the coordinates of the point on the ellipse, c is the distance from the center of the ellipse to the focus, r is the length of the major axis, and h2 is the height of the flow channel.

10. The optimization method according to claim 6, characterized in that: If substance i is used to represent oxygen ions, the total molar flow rate of substance i in the diffusion process is expressed as follows: Where ci is the molar concentration of substance i; c tot is the total molar concentration of the binary mixture; R is the gas parameter; T is the thermodynamic temperature; p is the total gas pressure; k is the permeability coefficient; x1 and x2 are the mole fractions of substance 1 and substance 2, is the concentration gradient, μ is the viscosity coefficient; and are the effective Knudsen diffusion coefficients of substance 1 and substance 2, respectively; are the effective binary diffusion coefficients of species 1 and 2; and It is expressed as follows: Where ε is the porosity; τ is the curvature factor; r g is the radius of the pore; V1 and M1 are the diffusion volume and molar mass of substance 1, V2 and M2 are the diffusion volume and molar mass of substance 2, r el is the average electron conducting particle radius; r io is the average ion particle radius; is the volume fraction of the conductive electron particles in the composite electrode, is the volume fraction of conductive ion particles in the composite electrode; The molar mass conservation equation for substance i transferred during the battery chemical reaction process is as follows: Among them, ASL represents anode support layer, CCCL represents cathode contact layer, AFL represents anode functional layer, and CFL represents cathode functional layer; represents the flux change of substance i under different conditions: in the anode support layer or cathode contact layer, the flux change is zero; while in the anode functional layer or cathode functional layer, the flux changes Equal to the molar production or consumption rate of oxygen ions R i ; The specific relationship between the molar production or consumption rate of oxygen ions caused by electrochemical reactions in SOFC and the current density J and power density P is as follows: P=2R i FV In the formula, R i It represents the molar production or consumption rate of oxygen ions, F represents the Faraday constant, I represents the current, A represents the effective reaction area, and V represents the single cell voltage.

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