Alkaline electrolytic cell stretching net flow channel optimization method based on simulation analysis

Abstract

The invention relates to a simulation analysis-based alkaline electrolytic cell stretching net flow channel optimization method. The method comprises the following steps: 1, establishing a zero-clearance stretching net flow channel alkaline electrolytic cell numerical simulation model; 2, a free tetrahedral mesh is adopted to divide a computational domain, a boundary layer mesh is divided near a flow boundary, and angle refinement is set in a whole flow area to encrypt the density of the mesh; 3, initializing an electric field; 4, calculating a flow field; 5, thermal field calculation; 6, post-processing a result; 7, analyzing the influence of different stretching net structures on the working characteristics of the alkaline water electrolyser through multi-physics field coupling simulation, and optimizing the design scheme on the experimental basis; according to the method, the tensile net alkaline electrolytic cell model is established, the electrochemical field, the flow field and the thermal field are distributed and coupled, the reaction gas production process is simplified through the step function, the simulation calculation amount is reduced, the model convergence is better improved, the method acts on tensile net flow channel structure optimization, and the performance of the tensile net flow channel alkaline electrolytic cell is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen energy equipment structure optimization and numerical simulation, and relates to a method for optimizing the flow channel of an alkaline electrolytic cell stretching network based on simulation analysis. Background Art

[0002] Alkaline electrolyzer simulation is a technical approach that uses mathematical models and simulation tools to quantitatively analyze the physical and chemical processes within an alkaline electrolyzer. Its core goal is to predict electrolyzer performance parameters (such as hydrogen production efficiency, energy consumption, and temperature distribution) under different operating conditions and to optimize design and operation strategies.

[0003] However, existing alkaline electrolyzer simulation calculation methods pay little attention to the interaction between multiple physical fields and complex structures. Most studies focus on simulation studies of small-scale, simple flow channels. The traditional method of calculating the working characteristics of alkaline water electrolyzers based on finite element analysis uses relatively simple models, has a large amount of calculation for complex models, and has poor coupling of multi-physical field iterative analysis. For example: CN113111550B discloses a method and system for analyzing the working characteristics of alkaline water electrolyzers based on finite element analysis, and establishes a finite element simulation model, electrochemical model, flow field model and thermal field model of the alkaline water electrolyzer; the calculation amount is large and the coupling is poor. In addition, due to the complex electrode structure of the alkaline water electrolyzer, it is difficult to achieve fine coupling modeling of the evolution of the gas-liquid interface and the electrochemical reaction behavior, resulting in certain limitations in the simulation results.

[0004] Therefore, a calculation method with low computational complexity and strong convergence is needed to solve the above technical problems. Summary of the Invention

[0005] To solve the above problems, the present invention addresses the contradiction between the modeling accuracy and computational efficiency of the multi-physical field coupling mechanism in the alkaline water electrolysis process in the existing alkaline electrolyzer simulation calculation. In previous simulation studies, the generation, desorption and migration process of bubbles and their dynamic influence on the electrode reaction behavior were difficult to accurately characterize, especially in terms of the bubble coverage on the effective reaction area of the electrode surface, the current density distribution and the IV characteristic changes. Traditional models mostly use simplified processing, resulting in a significant deviation between the simulation results and the actual working conditions. In addition, the strong coupling relationship between gas-liquid two-phase flow, heat conduction and structural response has not been systematically integrated in most studies, affecting the adaptability and predictive reliability of the model at an industrial scale. At the same time, the simulation of complex flow channel structures must take into account both the electrochemical kinetic behavior at the microscopic scale and the flow distribution law at the macroscopic scale. It is necessary to solve the highly nonlinear multi-field coupling control equations, and perform fine grid division and multi-parameter collaborative solution, which greatly increases the computational cost and convergence difficulty.

[0006] The technical solution adopted by the present invention to solve the technical problem is: a method for optimizing the flow channel of an alkaline electrolytic cell stretching network based on simulation analysis, comprising the following steps:

[0007] Step 1: Establish a numerical simulation model of the zero-gap stretched mesh flow channel alkaline electrolytic cell. The numerical simulation model includes, from top to bottom, the anode free flow area, the anode nickel mesh electrode, the diaphragm, the cathode nickel mesh electrode, and the cathode free flow area.

[0008] Step 2: Use free tetrahedral mesh to divide the computational domain and divide the boundary layer mesh near the flow boundary. Set angle refinement in the entire flow area to increase the density of the mesh.

[0009] Step 3: Electric field initialization: When the electrolyzer is initially powered off, the liquid phase volume fraction is set to 1 and the gas phase volume fraction is set to 0. The initial value of the gas production flux is determined by initializing the current distribution of the electrolysis physical field and performing electrochemical steady-state calculations.

[0010] Step 4: Flow field calculation: A mixture model is used to calculate the gas-liquid two-phase flow. As the gas production process progresses, the gas phase volume fraction gradually increases, and the gas production rate is controlled by a step function. The flow field is initialized first, and then a transient solution is performed to ensure good model convergence and high calculation accuracy.

[0011] Step 5: Thermal field calculation: Based on the reaction heat calculated by electric field initialization, during the transient calculation process, the reaction rate is controlled by the gas phase volume fraction, and the thermal conductivity of the two-phase field is dynamically adjusted to accurately simulate the heat transfer of the system.

[0012] Step 6: Post-process the results, calculate the electrolyte conductivity by weighting the gas-liquid phase volume fraction, and calculate the electrolytic cell current density;

[0013] Step 7: Through multi-physics field coupling simulation, analyze the impact of different stretched mesh structures on the working characteristics of the alkaline water electrolyzer, provide data support, and optimize the design scheme based on experiments.

[0014] Preferably, in step 1, the structure of the numerical simulation model is composed of quadrilateral basic units, and a complete stretching mesh model is formed by constructing quadrilateral basic units and periodically arranging the quadrilateral basic units in an array manner.

[0015] Preferably, in step 2, the nickel mesh electrode and the main body of the diaphragm domain are divided using a structured grid, and the corner details are supplemented with a free tetrahedral grid.

[0016] Preferably, in step 3, the relationship between current density and reaction rate is approximately described by the Butler-Volmer equation, the electrode overpotential η is calculated by the Nernst equation, and the current density and potential distribution satisfy the current conservation equation.

[0017] Preferably, in step 4, the basic model of the mixture model includes: continuity equation, momentum conservation equation, phase component transport equation, and main driving force of bubble motion.

[0018] Preferably, in step 4, variables are defined on the anode side and the cathode side during model calculation, and the variables are used to describe the mass flux of oxygen, the mass flux of oxygen and KOH solution, and the volume flow rates of different phases (gas phase and liquid phase). The variables on the anode side include: oxygen mass flux, solvent mass flux, gas phase volume flow rate, and the total volume flow rate of the gas-liquid mixed flow. The variables on the cathode side include: hydrogen mass flux, solvent mass flux, gas phase volume flow rate, and the total volume flow rate of the gas-liquid mixed flow.

[0019] Preferably, in step 5, the control equations include: energy conservation equation, ohmic heat, and solid thermal conduction equation.

[0020] Preferably, the step 6 specifically includes:

[0021] First, the electrolyte conductivity σ is described by the empirical formula eff :

[0022] σ eff =σ KOH (T)·(1-α g )

[0023]

[0024] Among them, σ KOH (T) represents the conductivity of KOH solution, A, B, m are fitting parameters, C KOH represents the KOH mass concentration, T represents the temperature, α g represents the gas phase volume fraction;

[0025] Next, the current density distribution is calculated using the current conservation equation:

[0026]

[0027] J=σ eff E

[0028] Where φ represents the electric potential distribution, E represents the electric potential, and J represents the current density distribution. represents the spatial gradient of the electric potential φ, represents the gradient operator; the boundary conditions are usually that the anode and cathode electrode voltages or the current density are known. By solving the electric potential field, the electric field strength can be calculated, and then the current density distribution can be obtained.

[0029] Preferably, in step 6, the boundary conditions are further modified, and the overpotential of the electrode surface is calculated using the Tafel equation or the Butler-Volmer equation, so as to calculate the change of current density at different positions.

[0030] Preferably, in step 7, when analyzing the effects of different stretched mesh structures on the working characteristics of the alkaline water electrolyzer, different calculation examples include: different stretched mesh unit major axis lengths, different stretched mesh unit minor axis lengths, and different stretched mesh heights.

[0031] The beneficial effects of the present invention are:

[0032] 1. The present invention establishes a stretched mesh alkaline electrolytic cell model, distributes and couples the electrochemical field, flow field, and thermal field, simplifies the reaction gas production process through a step function, reduces the amount of simulation calculations, improves the model convergence, acts on the stretched mesh flow channel structure optimization, and improves the performance of the stretched mesh flow channel alkaline electrolytic cell.

[0033] 2. This invention encompasses finite element analysis, two-phase flow modeling, electrode equivalent modeling, electrochemical reaction kinetics, and heat transfer theory, and constructs a three-dimensional physical model of an alkaline electrolyzer. Through integrated modeling and analysis of multi-physics mechanisms such as gas-liquid two-phase flow, fluid-solid thermal coupling, and electrochemical reactions, the computational accuracy and reliability of the constructed AWE model were verified. The simulation results closely matched the experimental data within the voltage range of 1.6-2.3V, with an overall error of less than 5%, providing a solid theoretical foundation for subsequent research on operating condition control and structural optimization.

[0034] 3. The present invention systematically evaluates three key factors in optimizing the structural parameters of the stretched mesh: at 1.8 V, reducing the major axis of the mesh can increase the current density by 22 mA·cm-2 and the flow field uniformity by 31.15%, but the pressure drop increases by 26.31%, with significant performance improvement and high cost performance; reducing the minor axis length can increase the current density by 36 mA·cm-2, the flow field uniformity by 8.75%, and the pressure drop by 24.27%, with significant performance improvement, but the flow resistance increase is more sensitive, and it is recommended to prioritize the optimization of the major axis size; moderately reducing the mesh height is conducive to disturbance enhancement and bubble discharge. Simulation shows that the current density can reach 263 mA·cm-2 at the optimal mesh height, but uneven liquid supply and poor exhaust should be avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a comparison diagram between the actual object and the modeling of a flow channel optimization method for an alkaline electrolytic cell stretching network based on simulation analysis of the present invention;

[0036] Figure 2 Modeling and parameter annotation diagram of the stretched mesh unit of the present invention;

[0037] Figure 3This is a diagram of the physical model for the simulation calculation of the stretched mesh flow channel alkaline electrolytic cell of the present invention;

[0038] Figure 4 Schematic diagram of mesh division of the present invention;

[0039] Figure 5 A comparison diagram of IV characteristic curves of the experimental results and the calculated results of the present invention;

[0040] Figure 6 is the electrolyte current density distribution diagram of the present invention;

[0041] Figure 7 is the gas phase volume fraction distribution diagram of the present invention;

[0042] Figure 8 This is a temperature distribution diagram of the electrolytic cell of the present invention;

[0043] Figure 9 Polarization curves of the electrolytic cells with stretched mesh flow channels of different major axis lengths according to the present invention;

[0044] Figure 10 Polarization curves of the electrolytic cells with stretched mesh flow channels of different short axis lengths of the present invention;

[0045] Figure 11 Polarization curves of the electrolytic cells with stretched mesh flow channels of different heights according to the present invention;

[0046] Figure 12 Schematic diagram of the optimization method steps of the present invention. DETAILED DESCRIPTION

[0047] The following will provide a clear and complete description of the relevant technologies in the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0048] refer to Figures 1 to 12As shown in the figure, in this specific embodiment, a three-dimensional multi-physics field coupled simulation model of an alkaline water electrolyzer with a stretched mesh flow channel under a zero-gap structure was first established. The model structure includes, from top to bottom, the anode free flow domain, the anode nickel mesh electrode, the diaphragm, the cathode nickel mesh electrode, and the cathode free flow domain. After the geometric modeling is completed, the computational domain is divided using a free tetrahedral mesh, and a boundary layer mesh is applied near the flow boundary. At the same time, angle refinement is set in the entire flow area to improve mesh accuracy. In the simulation initialization stage, the electric field is first initialized. In the initial state without power, the liquid phase volume fraction is set to 1 and the gas phase volume fraction is set to 0. Subsequently, the initial boundary conditions for the gas production flux are determined through a two-step solution of the electrolysis physical field (current distribution initialization and electrochemical steady-state calculation). In terms of the flow field, a mixture model is used to describe the gas-liquid two-phase flow. As the electrolysis reaction proceeds, the gas phase volume fraction gradually increases, and the gas production rate is controlled by a step function. During the simulation process, the flow field is initialized first, and then a transient solution is performed to ensure that the model has good convergence and high computational accuracy. During the thermal field calculation process, the reaction heat obtained in the electric field initialization stage is used as the heat source term, the effect of the gas phase volume fraction on the reaction rate is considered in the transient solution, and the thermal conductivity of the gas-liquid mixing area is dynamically adjusted to achieve a fine simulation of the heat conduction behavior. After completing the solution of each physical field, the gas-liquid phase volume fraction distribution is obtained through post-processing analysis, and the electrolyte conductivity is weighted and calculated based on this, and the current density distribution characteristics of the electrolytic cell are further deduced. Through the above-mentioned complete multi-physical field coupling simulation process, this embodiment analyzes the influence mechanism of the mesh shape, size and arrangement of the stretched mesh on the electrolytic performance, provides reliable data support and theoretical basis, and helps to optimize the application of the stretched mesh spoiler structure in experimental design.

[0049] The multi-physics field coupling calculation method for an alkaline electrolyzer of this embodiment includes the following steps:

[0050] (1) Modeling the stretched mesh structure. The structure is composed of a quadrilateral basic unit. By constructing the basic unit and arranging it periodically in an array, a complete stretched mesh model is formed.

[0051] Figure 3 The structural diagram and parameter annotation of the stretched mesh unit used in the calculation are shown.

[0052] Figure 4This paper demonstrates the physical model used for multi-physics coupling of an alkaline water electrolyzer with a stretched mesh flow channel. The model consists of a cathode flow channel, a cathode nickel mesh electrode, an anode flow channel, an anode nickel mesh electrode, a diaphragm, and cathode and anode inlet and outlet manifolds. Due to the stretched mesh occupying the flow space, the flow channel exhibits a complex but regular structure. The entire physical model has a diameter of 100 mm. The flow channel is the same height as the inlet and outlet manifolds, which are 10 mm wide and approximately 15 mm long. The cathode nickel mesh electrode is 0.7 mm thick, the diaphragm is 0.8 mm thick, and the anode nickel mesh electrode is 0.7 mm thick.

[0053] (2) A free tetrahedron mesh was used for meshing, and a boundary layer mesh was created near the flow boundary. Angle refinement was applied to the entire flow domain to increase mesh density. The nickel mesh electrode and diaphragm domains were meshed using a structured mesh, with corner details supplemented with a free tetrahedron mesh. Verification of flow field independence and electrochemical field mesh independence was performed, and the computational accuracy met the requirements when the number of meshes was 7,761,267.

[0054] (3) The first step in the simulation calculation is to initialize the electrochemical field. When the electrolyzer is initially unpowered, the liquid phase volume fraction is 1 and the gas phase volume fraction is 0. The initial value of the gas flux is determined by the chemical reaction model (electrolyzer physical field).

[0055] The relationship between current density and reaction rate can be approximately described by the Butler-Volmer equation. The electrode overpotential η is calculated using the Nernst equation. Furthermore, the current density and potential distribution must satisfy the current conservation equation.

[0056]

[0057] η=VV eq -IR

[0058]

[0059] where j0 is the exchange current density, αa and αc are the electron transfer coefficients at the anode and cathode, respectively, F is the Faraday constant, η is the overpotential, R is the gas constant, T is the absolute temperature, V is the applied voltage, Veq is the equilibrium potential, IR is the ohmic polarization term (calculated from the electrolyte conductivity), σ is the conductivity of the electrolyte, and φ is the potential distribution.

[0060] (4) The second step is to calculate the flow and thermal fields. A mixture model is used to calculate the two-phase flow. As the gas production process progresses, the gas phase volume fraction gradually increases, and the gas production rate is controlled by a step function. The calculation process is divided into two steps: first, the flow field is initialized, and then a transient calculation is performed to ensure good convergence and high calculation accuracy.

[0061] Gas-liquid two-phase flow is handled using a mixture model, in which a certain velocity difference exists between the gas phase (hydrogen and oxygen) and the liquid phase (KOH solution). The basic mathematical model includes the continuity equation (mass conservation), the momentum conservation equation (Navier-Stokes equation), the phase component transport equation (describing the gas phase volume fraction αg), and the main driving forces of bubble motion (buoyancy and pressure gradient).

[0062]

[0063] F b =ρ g V g g

[0064] Where ρm is the mixture density, um is the mass average velocity, p is the pressure, μm is the mixture dynamic viscosity, F is the volume force (including gravity, buoyancy, etc.), ug is the gas phase velocity, Sg is the gas phase source term, which is calculated from the gas flux generated by the electrolysis reaction, Fb is the bubble buoyancy, ρg is the gas phase density, Vg is the bubble volume, and g is the acceleration due to gravity.

[0065] (5) The model calculation requires the definition of some variables on the anode side and the cathode side, which are used to describe the mass flux of oxygen, oxygen and KOH solution, and the volume flow rate of different phases (gas phase and liquid phase).

[0066] The geometric entity defined by the anode side variables is the anode side free flow domain, and four main variables are defined:

[0067] (5-1) Oxygen mass flux O 2 flux , is the total oxygen mass flow rate Normalized to unit area:

[0068]

[0069] Where: ——the oxygen mass flow rate of the entire electrolyzer; S——the contact area between the anode electrode and the free flow channel. The variable is used to calculate the local oxygen mass flow rate. In addition, the oxygen flux is multiplied by two correction factors, step (φd) and rm (t·1s -1 In step(φd), a step function is defined to set the oxygen flux locally to zero when the volume fraction of the gas approaches 1 (smoothing is very important to avoid discrete jumps in the flux); in rm(t·1s -1 ), which is a time-varying correction factor. Considering the time evolution, after the transient solver is started, the ramp function is used to increase the oxygen flux from zero, which can shorten the calculation time.

[0070] (5-2) Solvent mass flux H2 O flux :

[0071]

[0072] Where: M H2O 、M O2 ——The molar masses of the solvent water and oxygen are 18 g·mol respectively -1 and 16 g·mol -1 Since 2 mol of H2 O are consumed to generate 1 mol of O2 during the electrolysis process, according to the law of conservation of mass: Water is consumed, so the minus sign is added. The variable is used to calculate the local water consumption flux.

[0073] (5-3) Gas phase volume flow rate disp flow :

[0074]

[0075] It is calculated as the mass flux of oxygen divided by the density of oxygen (ρ d ), which is used to calculate the volume flow rate of oxygen and characterize the spatial proportion of oxygen.

[0076] (5-4) Total volume flow rate of gas-liquid mixture flow :

[0077]

[0078] Where: - volume flow rate of oxygen (oxygen flow per unit area); ——The volume flow rate of water (the amount of water flowing per unit area). This variable is used to calculate the total flow rate of the gas-liquid mixed flow, taking into account the contributions of both oxygen and water.

[0079] (5-5) The geometric entity defined by the cathode side variables is the cathode side free flow domain. Four main variables are also defined, similar to the anode side, namely, hydrogen mass flux H 2 flux , solvent mass flux H2 O flux , gas phase volume flow rate disp flow , the total volume flow rate of the gas-liquid mixture flow .

[0080] (6) Based on the reaction heat calculated from the electric field initialization, during the transient calculation process, the reaction rate is controlled by the gas phase volume fraction, and the thermal conductivity of the two-phase field is dynamically adjusted to accurately simulate the heat transfer of the system. During the electrolysis process, the polarization of the electrode and the conductivity of the electrolyte will cause heat generation, so heat transfer needs to be considered. The main governing equations are the energy conservation equation (fluid), ohmic heat (Joule heat), and the solid heat conduction equation (electrode, tank).

[0081]

[0082] Where T is the temperature distribution, c p is the specific heat capacity, k is the thermal conductivity, Q is the heat source term (ohmic heat, electrode reaction heat, etc.), T s is the solid temperature, k s is the solid thermal conductivity, Q s It is a solid internal heat source.

[0083] (7) Finally, in COMSOL, given the gas-liquid phase volume fraction, temperature distribution, and initial current density distribution, the electrolyte conductivity can be calculated according to the following steps, and the current density distribution of the electrolytic cell can be further calculated.

[0084] First, the electrolyte conductivity σ eff Affected by the concentration of KOH solution, temperature and gas phase volume fraction, it can be described by the empirical formula:

[0085] σ eff =σ KOH (T)·(1-α g )

[0086]

[0087] Among them, σ KOH (T) is the conductivity of KOH solution, which can be fitted using the empirical formula, where A, B, and m are fitting parameters, and C KOH is the KOH mass concentration, T is the temperature, α g is the volume fraction of the gas phase, considering that the presence of bubbles will reduce the effective conductivity of the local electrolyte.

[0088] Next, the current density distribution is calculated using the current conservation equation:

[0089]

[0090] J=σ eff E

[0091] Where φ is the electric potential distribution. Boundary conditions typically require known anode and cathode electrode voltages or current densities. By solving for the electric potential field, the electric field strength can be calculated, and thus the current density distribution.

[0092] Since the coverage effect of bubbles on the electrode surface will cause the local current density to decrease, the boundary conditions can be further modified and the overpotential of the electrode surface can be calculated using the Tafel equation or the Butler-Volmer equation to calculate the current density changes at different locations.

[0093] (8) By constructing different simulation models and applying multi-physics field coupling calculation methods, the effects of different stretching mesh structures on the working characteristics of alkaline water electrolyzers are analyzed. The different calculation examples include: different stretching mesh unit major axis lengths, different stretching mesh unit minor axis lengths, and different stretching mesh heights.

[0094] Example 1:

[0095] This example studies the effect of the major axis length on the performance of the electrolytic cell by changing the major axis length of the mesh unit. sw , mesh slope length m osl It is jointly determined that the slope length of each stretching mesh is the main factor affecting the major axis length. A group of embodiments of a stretching mesh flow channel alkaline electrolytic cell are constructed by setting the mesh slope length to 5mm, 7mm, 9mm, and 11mm.

[0096] Example 2:

[0097] This example studies the effect of the short axis length on the performance of the electrolytic cell by changing the short axis length of the mesh unit. vs A set of embodiments of a stretched mesh flow channel alkaline electrolytic cell is constructed by setting the semi-minor axis length to 2 mm, 3.5 mm, and 5 mm.

[0098] Example 3:

[0099] This example explores the effect of stretched mesh height on electrolytic cell performance by varying the mesh unit height. A set of examples of stretched mesh flow channel alkaline electrolytic cells were constructed by setting the stretched mesh height to 1.42 mm, 2.38 mm, and 3.34 mm.

[0100] The key points of this embodiment are:

[0101] 1. Develop a multi-physics coupled modeling method for alkaline water electrolyzers with high computational efficiency and excellent convergence performance. Addressing the highly coupled multi-physics processes in alkaline water electrolyzers, including fluid flow, electrochemical reactions, bubble generation and migration, and heat transfer, a modeling strategy that balances accuracy and computational efficiency is proposed. By optimizing the modeling strategy, initial field settings, meshing and local refinement, and improving the coupling strategy, this method is suitable for engineering-scale simulations.

[0102] 2. The effects of different stretch mesh structural parameters on the multi-physical field distribution of alkaline electrolyzers were systematically explored. The influence of key geometric parameters of the stretch mesh structure (such as pore size, mesh shape, thickness, height, flow direction, etc.) on the multi-physical field distribution within the alkaline water electrolyzer was fully considered. The effects of gas-liquid distribution, current density uniformity, thermal field regulation, and performance trade-off analysis were fully considered.

[0103] 3. In view of the modeling complexity brought about by the regular and three-dimensional configuration of the stretched mesh structure, a simplified modeling method suitable for the stretched mesh spoiler flow channel is proposed to improve the modeling efficiency and versatility.

[0104] In summary, the present invention establishes a stretched mesh alkaline electrolytic cell model, distributes and couples the electrochemical field, flow field, and thermal field, simplifies the reaction gas production process through a step function, reduces the amount of simulation calculations, improves the model convergence, acts on the stretched mesh flow channel structure optimization, and improves the performance of the stretched mesh flow channel alkaline electrolytic cell.

[0105] It should be emphasized that the above are only preferred embodiments of the present invention and do not limit the present invention in any form. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for optimizing the flow channel of an alkaline electrolytic cell stretching network based on simulation analysis, characterized in that: The following steps are involved: Step 1: Establish a numerical simulation model of a zero-gap stretched mesh flow channel alkaline electrolytic cell, wherein the numerical simulation model includes, from top to bottom, an anode free flow area, an anode nickel mesh electrode, a diaphragm, a cathode nickel mesh electrode, and a cathode free flow area; Step 2: Use free tetrahedral mesh to divide the computational domain and divide the boundary layer mesh near the flow boundary. Set angle refinement in the entire flow area to increase the density of the mesh. Step 3: Electric field initialization: When the electrolyzer is initially powered off, the liquid phase volume fraction is set to 1 and the gas phase volume fraction is set to 0. The initial value of the gas production flux is determined by initializing the current distribution of the electrolysis physical field and performing electrochemical steady-state calculations. Step 4: Flow field calculation: A mixture model is used to calculate the gas-liquid two-phase flow. As the gas production process progresses, the gas phase volume fraction gradually increases, and the gas production rate is controlled by a step function. The flow field is initialized first, and then a transient solution is performed. Step 5: Thermal field calculation: Based on the reaction heat calculated by electric field initialization, the reaction rate is controlled by the gas phase volume fraction during the transient calculation process, and the thermal conductivity of the two-phase field is dynamically adjusted; Step 6: Post-process the results, calculate the electrolyte conductivity by weighting the gas-liquid phase volume fraction, and calculate the electrolytic cell current density; Step 7: Through multi-physics field coupling simulation, analyze the impact of different stretched mesh structures on the working characteristics of the alkaline water electrolyzer, and optimize the design scheme based on the experiment.

2. The method for optimizing the flow channel of an alkaline electrolytic cell stretching network based on simulation analysis according to claim 1, characterized in that: In the step 1, the structure of the numerical simulation model is composed of quadrilateral basic units, and the stretching mesh model is formed by constructing the quadrilateral basic units and periodically arranging the quadrilateral basic units in an array manner.

3. The method for optimizing the flow channel of an alkaline electrolytic cell stretching network based on simulation analysis according to claim 1, characterized in that: In step 2, the nickel mesh electrode and the diaphragm domain are divided into structured grids, and the corner details are supplemented with free tetrahedral grids.

4. The method for optimizing the flow channel of an alkaline electrolytic cell stretching network based on simulation analysis according to claim 1, characterized in that: In step 3, the relationship between current density and reaction rate is described by the Butler-Volmer equation, the electrode overpotential η is calculated by the Nernst equation, and the current density and potential distribution satisfy the current conservation equation.

5. The method for optimizing the flow channel of an alkaline electrolytic cell stretching network based on simulation analysis according to claim 1, characterized in that: In step 4, the basic model of the mixture model includes: continuity equation, momentum conservation equation, phase component transport equation, and main driving force of bubble motion.

6. The method for optimizing the flow channel of an alkaline electrolytic cell stretching network based on simulation analysis according to claim 1, characterized in that: In step 4, variables are defined on the anode side and the cathode side during model calculation, respectively. The variables are used to describe the mass flux of oxygen, the mass flux of oxygen and KOH solution, and the volume flow rates of different phases. The variables on the anode side include: oxygen mass flux, solvent mass flux, gas phase volume flow rate, and the total volume flow rate of the gas-liquid mixed flow. The variables on the cathode side include: hydrogen mass flux, solvent mass flux, gas phase volume flow rate, and the total volume flow rate of the gas-liquid mixed flow.

7. The method for optimizing the flow channel of an alkaline electrolytic cell stretching network based on simulation analysis according to claim 1, characterized in that: In step 5, the control equations include: energy conservation equation, ohmic heat, and solid thermal conduction equation.

8. The method for optimizing the flow channel of an alkaline electrolytic cell stretching network based on simulation analysis according to claim 1, characterized in that: The step 6 specifically includes: First, the electrolyte conductivity σ is described by the empirical formula eff : s eff =s KOH (T)·(1-a g ) Among them, σ KOH (T) represents the conductivity of KOH solution, A, B, m are fitting parameters, C KOH represents the KOH mass concentration, T represents the temperature, α g represents the gas phase volume fraction; Next, the current density distribution is calculated using the current conservation equation: J=σ eff AND Where φ represents the electric potential distribution, E represents the electric potential, and J represents the current density distribution.

9. The method for optimizing the flow channel of an alkaline electrolytic cell stretching network based on simulation analysis according to claim 1, characterized in that: In step 6, the boundary conditions are further modified, and the overpotential of the electrode surface is calculated using the Tafel equation or the Butler-Volmer equation, so as to calculate the change of current density at different positions.

10. The method for optimizing the flow channel of an alkaline electrolytic cell stretching network based on simulation analysis according to claim 1, characterized in that: In step 7, when analyzing the effects of different stretched mesh structures on the working characteristics of the alkaline water electrolyzer, different calculation examples include: different stretched mesh unit major axis lengths, different stretched mesh unit minor axis lengths, and different stretched mesh heights.

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