Membrane electrode electrolytic cell multi-physical field modeling method and device

Abstract

The invention discloses a modeling method and device for multiple physical fields of a membrane electrode electrolytic cell. The modeling method comprises the following steps: S1, obtaining related structural parameters, physical property parameters and chemical reaction parameters of a device; s2, according to the obtained physical property parameters, constructing an MEA multi-physical field numerical model; s3, analyzing a calculation result of the numerical model, and determining salting-out potential and salting-out current density of the CO2 membrane electrode assembly under working condition operation; s4, various design parameters of the MEA are adjusted, and the most suitable design parameters are determined according to the salting-out occurrence condition and the combination of the comprehensive performance of the device; and S5, under the corresponding salting-out potential, inhibiting salting-out by regulating and controlling related input parameters. The MEA multi-physical field model constructed by the method reflects information of various design parameters MEA more truly under working conditions or non-working conditions, is beneficial to deepening understanding of substance transfer on an MEA electrochemical performance influence factor mechanism, and provides guidance for practical application of CO2MEA.

Description

Technical Field

[0001] The present invention relates to the field of electrolyzers, and in particular to a multi-physical field modeling method and device for a membrane electrode electrolyzer. Background Art

[0002] In the context of new energy, it is urgent to develop new and efficient energy conversion technologies. Among the many energy conversion technologies, electrolysis is one of the most promising approaches. In actual operation, there are three electrochemical devices used for electrolysis, namely H-type electrolyzer, flow-type electrolyzer and membrane electrode assembly (MEA). H-type electrolyzer and flow-type electrolyzer are the two types of electrolyzers used in most laboratories for electrolysis experiments. The H-type electrolyzer has a simple structure and is easy to assemble. The cathode chamber and the anode chamber are separated by an ion exchange membrane, which can quickly evaluate the reaction performance of the catalyst. However, due to the limitations of solubility and mass transfer processes, the reaction current density on the H-type electrolyzer is usually limited to 20 mA cm -2 Around, far from the commercial level, limiting its practical application. In order to overcome the mass transfer limitation, the flow-type electrolyzer uses a gas diffusion electrode, which greatly shortens the gas diffusion distance. During the reaction, the reactants are directly transported to the back of the cathode through the gas phase, and quickly penetrate the gas diffusion electrode to reach the catalyst surface for reaction, which significantly increases the current density. However, due to the significant ohmic resistance of the electrolyte layer in the flow tank, its energy efficiency has not been high. MEA has lower ohmic losses and no electrolyte at the cathode, so it is expected to further improve the electrolysis performance.

[0003] However, due to the complex structure of MEA, there are also some problems in the application of MEA, such as CO 2 For example, MEA, salt precipitation has always been CO 2 A problem in MEA. Salt precipitation causes the porosity of the catalyst layer and porous electrode to decrease, inhibiting the CO 2 The mass transfer at the reaction site decreases, the reaction current decreases, and the hydrogen evolution reaction intensifies, which reduces the Faraday efficiency of the product. - reaction, so at high current density, the pH value of the cathode catalyst layer will increase, CO 2 With OH - The homogeneous reaction intensified, accelerating the CO 3 2- and HCO 3 - On the other hand, the cations in the anolyte migrate to the cathode through the anion exchange membrane under the action of the electric field. When the limit concentration is reached, that is, the product of the ion concentration exceeds the solubility product, salt precipitation will occur in theory. 2The electro-reduction process provides an essential local electric field effect, and MEA has practical application value only when it operates at a higher current density, which inevitably leads to salting out.

[0004] In view of the problems existing in the actual application of MEA, it is necessary to reasonably design the parameters of MEA to avoid many problems to the greatest extent and to deal with the problems in MEA operation through certain strategies. Summary of the invention

[0005] The object of the present invention is to provide a method and device for modeling multi-physical fields of a membrane electrode electrolyzer to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above-mentioned object of the invention, one aspect of the present invention provides a modeling method for multi-physical fields of a membrane electrode electrolyzer, comprising the following steps:

[0007] Step S1, obtaining device-related structural parameters, physical property parameters and chemical reaction parameters;

[0008] Step S2, constructing a MEA multi-physical field numerical model according to the acquired physical property parameters, wherein the multi-physical fields include gas phase concentration field, liquid phase concentration field, gas phase pressure field, liquid phase pressure field, ionomer water mass transfer, solid phase potential field, liquid phase potential field, and salt precipitation occurrence field;

[0009] Step S3: Analyze the calculation results of the numerical model to determine the CO 2 Salting-out potential and salting-out current density of membrane electrode assembly;

[0010] Step S4, adjusting various design parameters of MEA, and determining the most suitable design parameters according to the occurrence of salt precipitation and the comprehensive performance of the device;

[0011] Step S5, suppressing the occurrence of salting out by adjusting relevant input parameters under the corresponding salting out potential.

[0012] Furthermore, the gas phase concentration field is a mixture average model, which is used to describe the mass transfer process of gas phase substances inside the anode and cathode, and its expression is:

[0013]

[0014] Where n j is the flux of gas phase species j, ρ g is the density of the gas phase, is the effective diffusion coefficient of gas phase species j, ω j is the mass fraction of gas phase species j, M n is the average molar mass of the gas mixture, ρ i is the partial density of the gas phase, u gis the convection velocity of the gas phase.

[0015] Furthermore, the liquid concentration field is the Nernst–Planck equation, which is used to describe the mass transfer process of liquid substances inside the anode and cathode, and its expression is:

[0016]

[0017] Where n i is the flux of liquid species i, is the effective diffusion coefficient of liquid phase substance i, c i is the molar concentration of liquid substance i, z i is the charge number of liquid substance i, F is the Faraday constant, R is the molar gas constant, T is the temperature, φ l is the liquid phase potential.

[0018] Furthermore, the gas-liquid phase pressure field is described by Darcy's law, which is expressed as follows:

[0019]

[0020] Among them, u m is the convection velocity of medium m, is the effective permeability of medium m, μ m is the dynamic viscosity of the medium, p m is the pressure of medium m.

[0021] Furthermore, the solid-liquid phase potential satisfies Ohm's law, which is expressed as follows:

[0022]

[0023] i l =F∑ i z i n i

[0024]

[0025] Among them, i s is the solid phase current density, i l is the liquid phase current density, is the effective specific surface area, i k is the current density of the electrode reaction k.

[0026] Furthermore, the reaction rate of the salting-out substance is expressed as follows:

[0027]

[0028] Where R is the salting-out reaction rate, ε is the volume fraction of salt, k is the deposition rate constant, K sp is the solubility product of the salt and s is the stoichiometric number.

[0029] Furthermore, the analysis process of step S3 includes comparing the ion concentration product under the steady-state model with the salt solubility product. If the ion concentration product is greater than the salt solubility product, it is considered that salting out will occur, and the potential and current density under this condition are the salting out potential and the salting out current density.

[0030] Furthermore, the design parameters regulated in step S4 include the thickness of the catalyst layer, the specific surface area of ​​the catalyst layer, the thickness of the anion exchange membrane, and the ion exchange capacity of the anion exchange membrane.

[0031] Furthermore, the response strategy of step S5 includes regulating the concentration of the anode electrolyte and the voltage applied to the device, and by changing the above input conditions, the occurrence of salt precipitation is suppressed and the current density of the device is maintained.

[0032] Another aspect of the present invention provides a modeling device for a membrane electrode electrolyzer multi-physical field, comprising a parameter acquisition module, a model building module, a numerical analysis module, a parameter adjustment module, and an application module, wherein:

[0033] Parameter acquisition module, used to obtain device-related structural parameters, physical property parameters and chemical reaction parameters;

[0034] A model building module is used to build a MEA multi-physical field numerical model based on the acquired physical property parameters, wherein the multi-physical fields include gas phase concentration field, liquid phase concentration field, gas phase pressure field, liquid phase pressure field, ionomer water mass transfer, solid phase potential field, liquid phase potential field, and salt precipitation occurrence field;

[0035] The numerical analysis module is used to analyze the calculation results of the numerical model and determine the CO 2 Salting-out potential and salting-out current density of membrane electrode assembly;

[0036] Parameter adjustment module, used to adjust various design parameters of MEA, and determine the most suitable design parameters according to the occurrence of salt precipitation and the comprehensive performance of the device;

[0037] The application module is used to inhibit the occurrence of salting out by adjusting relevant input parameters under the corresponding salting out potential.

[0038] Compared with the prior art, the present system and method have the following advantages:

[0039] 1. The present invention adopts a multi-physical field numerical model and provides the MEA device performance and its material concentration distribution, pressure distribution, and potential distribution under different design parameters through finite element calculation.

[0040] 2. The present invention predicts the salting-out potential and salting-out current density of MEA under the design parameters by comparing the ion concentration product with the solubility product of the salt, and inhibits the occurrence of salting-out and maintains good electrochemical performance through relevant strategies.

[0041] 3. The present invention has excellent calculation efficiency and accurate calculation results, which provides convenience for the research on the design of reasonable MEA structure and is conducive to promoting the commercialization process of MEA. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A flow chart of a multi-physics modeling method for a membrane electrode electrolyzer.

[0043] Figure 2 Schematic diagram of the one-dimensional model of MEA under example parameters.

[0044] Figure 3 Figure 2 is the polarization curve of MEA under example parameters.

[0045] Figure 4 The graph shows the result of changing the anolyte concentration at a constant voltage to inhibit salting out and maintain the electrochemical performance of MEA.

[0046] Figure 5 The graph shows the results of suppressing salt precipitation and maintaining the electrochemical performance of MEA by changing the applied voltage under constant anolyte concentration.

[0047] Figure 6 This is the wettability diagram corresponding to the capillary pressure of different materials in this model. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] like Figure 1 The method flow chart of the present invention is shown in FIG. 2 The MEA process is used as an example to construct CO 2 MEA multi-physics numerical model. The modeling and analysis method mainly includes the following five steps.

[0050] Step S1, obtaining device-related structural parameters, physical property parameters and chemical reaction parameters.

[0051] The structural parameters include the porosity, thickness, and cross-sectional area of ​​the material; the physical parameters include conductivity, permeability, diffusion coefficient, viscosity, ion exchange capacity of the ion exchange membrane, and membrane density of the ion exchange membrane; the chemical reaction parameters include the forward and reverse rate constants of the homogeneous reaction, the equilibrium coefficient, the exchange current density of the BV equation, the transfer coefficient, and the reference equilibrium potential. The specific parameters are shown in Table 1.

[0052]

[0053]

[0054]

[0055]

[0056] Step S2, constructing a MEA multi-physics field numerical model according to the acquired physical property parameters.

[0057] According to the geometric parameters of step S1, the following can be constructed: Figure 2 The one-dimensional model shown in the figure has a multi-physics field setting including control equations and boundary conditions. The specific expressions are as follows.

[0058] In the model, the mass conservation equation of each substance is as follows:

[0059]

[0060] Among them, c i / j and n i / j Represent the concentration and flux of substances, respectively. The subscript i represents liquid substances, j represents gaseous substances, and ε m represents the phase volume fraction, the subscript m can represent the gas phase (g), liquid phase (l), ionomer phase (i) and solid phase (s), R B,i represents the homogeneous reaction source term, which only occurs in the liquid phase and the ionomer phase, R CT,i / j represents the electrode reaction source term, R PT,i / j Represents the phase-transferred mass source term.

[0061] In this example, the gas phase species involved in the model are H 2 O (g) , CO 2(g) , CO (g) , H 2(g) , O 2(g) and N 2(g) , where N 2(g) It is calculated by the principle of mass conservation. The specific gas distribution is that there is H at the cathode. 2 O (g) , CO 2(g) , CO (g) , H2(g) and N 2(g) , CO at the anode 2(g) , O 2(g) and N 2(g) The gas phase mass transfer model uses the mixture average model, and the description equation of each gas phase material flux is

[0062]

[0063] Among them, ρ g is the density of the gas phase, is the effective diffusion coefficient of gas phase species j, ω j is the mass fraction of gas phase species j, M n is the average molar mass of the gas mixture, given by the equation M j is the molar mass of substance j, ρ i is the partial density of the gas phase, through the equation ρ j =ρ g ω j Calculate, u g is the convection velocity of the gas phase. The binary diffusion coefficient D of species j and k jk , calculated by the following relationship

[0064]

[0065] v p is the diffusion volume of the substance, which can be found in the parameter table. Effective diffusion coefficient Volume fraction of the medium used ε m and tortuosity v m , corrected by the Bruggeman relation

[0066]

[0067] The pressure fields in the gas and liquid phases are governed by Darcy's law

[0068]

[0069] Among them, u m is the convection velocity of medium m, Q m is the mass source term, is the effective permeability of medium m, μ m is the dynamic viscosity of the medium, p m is the pressure of medium m.

[0070] In this example, the liquid substances involved in the model are CO 2(l) , and Found in ion exchange membranes, ionomers and liquid water.

[0071] The liquid phase mass transfer model uses the dilute solution theory, and the flux of each liquid phase substance is described by the Nernst–Planck equation

[0072]

[0073] in, is the effective diffusion coefficient of liquid phase substance i, c i is the molar concentration of liquid substance i, z i is the charge number of liquid substance i, F is the Faraday constant, 96485C / mol, φ l is the liquid phase potential.

[0074] The water flux in the ionomer consists of two phases, one is the concentration gradient contribution phase, and the other is the electrodialysis contribution phase. The specific expression is as follows

[0075]

[0076] D w is the diffusion coefficient of water, and ξ is the electroosmotic coefficient of water.

[0077] In this case, the entire liquid concentration field has the following homogeneous reaction

[0078]

[0079] Among them, k i and k -i are the forward and reverse reaction rates, is the equilibrium constant, which can be calculated based on the entropy change (ΔS i ) and enthalpy change (ΔH i ) is calculated by the van't Hoff equation:

[0080]

[0081] The general expression for the source term of a homogeneous reaction is as follows

[0082]

[0083] Among them, s i is the stoichiometric coefficient corresponding to substance i in the equation.

[0084] In this case, the oxygen evolution reaction (OER) occurs at the anode of the membrane electrode assembly, and the hydrogen evolution reaction (HER) and the most important CO 2 The reaction current density of the electrode reaction above the reduction reaction (also known as CO evolution reaction, COER) is given by the BV equation:

[0085]

[0086] Among them, c ref =1[M] is the reference concentration, α is the transfer coefficient, i 0,k is the exchange current density of reaction k, η k is the overpotential of reaction k, i 0,k and η k The expression is as follows

[0087]

[0088] Among them, A k is the pre-exponential factor of reaction k, E a,k is the apparent activation energy of reaction k, φ s is the solid phase potential, is the reference equilibrium potential of reaction k. The electron transfer in the solid phase (including the catalyst layer and the porous diffusion layer) is controlled by the following equation:

[0089]

[0090] Among them, i s is the solid phase current density, i l is the liquid phase current density, and its expressions are

[0091]

[0092] in, is the effective conductivity.

[0093] The general expression for the electrode reaction source term is as follows

[0094]

[0095] in, is the effective specific surface area, S is the wettability, which can be calculated based on Figure 6 Capillary pressure (p c =p l -p g ) corresponds to the wetting curve to obtain, n k is the number of electrons transferred in reaction k.

[0096] In this case, the phase mass transfer includes the anode CO 2 Mass transfer and cathode CO 2 , H 2 O mass transfer. The general expression of the mass transfer source term is as follows

[0097]

[0098] Among them, k MT,j is the mass transfer rate.

[0099] For CO 2 MEA, there is a special case of salting out. In this case, K 2 CO 3 Salt precipitation

[0100]

[0101] The source term corresponding to the substance is

[0102]

[0103] in K 2 CO 3 The volume fraction of is the deposition rate constant, K 2 CO 3 The solubility product of .

[0104] Deposition K 2 CO 3 The volume fraction of

[0105]

[0106] The volume fraction of each phase is calculated as follows:

[0107]

[0108] ε l =ε m S m

[0109] ε l =ε m (1-S m )

[0110] in is the intrinsic porosity of the medium, f i,m is the content of ionomer in the pores.

[0111] Due to the presence of ionomers, there are differences in charge density between different domains, resulting in a discontinuous distribution of ion concentrations that follows the Donnan boundary condition, i.e.

[0112]

[0113] The boundary condition of the electric potential is K obtained from the electrical neutrality. + The boundary conditions of concentration are given by Donnan potential, as shown in the following table

[0114]

[0115]

[0116] Other boundary conditions such as potential, concentration, pressure, etc. are shown in the following table

[0117]

[0118] Among them, k MT,i The mass transfer coefficient associated with the Sherwood–Reynold–Schmidt number is expressed as follows:

[0119]

[0120] Among them, L elec is the electrode thickness, ρ l is the electrolyte density, v l =q l / A elec is the electrolyte flow rate, q l is the electrolyte flow rate, A elec is the cross-street area of ​​the flow channel, μ l is the dynamic viscosity of the electrolyte.

[0121] The simulation platform of this embodiment is COMSOL Multiphysics multi-physics field simulation platform, and a suitable grid is manually constructed: a grid of 0.1 μm size is set on all domains, and a grid of 1 nm size is set on all boundaries.

[0122] Step S3: Analyze the calculation results of the numerical model to determine the CO 2 The salt precipitation potential and salt precipitation current density of the membrane electrode assembly. The criterion for judging whether salt precipitation occurs in the membrane electrode assembly under this working condition is the solubility product of the salt (i.e. Is it greater than If the solubility product is greater than This means that the membrane electrode assembly has reached the conditions for salt precipitation under this condition, and the corresponding voltage and current density can be considered as the salt precipitation potential and salt precipitation current density of the membrane electrode assembly. More accurately, when the solubility product of the salt initially exceeds In a short period of time, salt precipitation may not occur in the membrane electrode assembly, because the rate of salt precipitation is related to the volume fraction ε of the salt in the system, the reaction rate constant k, and the solubility product. Therefore, the salting out problem will have an observable impact on the membrane electrode assembly when the operating conditions are slightly higher than the salting out potential and the salting out current density. The higher the potential and current density, the greater the impact of salting out on the membrane electrode assembly, and the greater the deviation between its theoretical performance and actual performance. The numerical model in step S3 is a steady-state model, that is, it does not consider the impact of salting out on the device, and only predicts the potential at which salting out occurs and its electrochemical performance. Its polarization curve is as follows Figure 3 shown.

[0123] Step S4, adjusts various design parameters of MEA to determine the most suitable design parameters. The design parameters include parameters such as catalyst layer thickness, catalyst layer specific surface area, ion exchange capacity of ion exchange membrane, ion exchange membrane thickness, and repeat the analysis method of step S3. In the actual operation process, the specific means is to modify the parameters to be optimized in the parameter list of step S1. In order to realize the control variable, only one parameter is enlarged or reduced at a time, and then the calculation is solved. The influence of the change of the parameter on the salting-out potential and salting-out current of the membrane electrode assembly is determined by the discrimination method of step S3. After several iterations of this step, the most suitable design parameters for the membrane electrode assembly can be determined.

[0124] Step S5, the MEA with the optimal design parameters is subjected to transient model calculation under the condition slightly higher than the salting-out potential, simulating the salting-out process of the MEA under the working condition, and suppressing the occurrence of salting-out through a variety of strategies (regulating relevant input parameters), and maintaining the good electrochemical performance of the device. The numerical model is a transient model, that is, the applied voltage exceeds the salting-out potential, taking into account the effect of salting-out on the device, and suppressing salting-out through the strategy of regulating the input parameters including the anode electrolyte concentration and the applied voltage, and maintaining the electrochemical performance of the device. Figure 4 The graph shows the result of changing the anolyte concentration at a constant voltage to inhibit salting out and maintain the electrochemical performance of MEA. From 0 to 1000 seconds, the anolyte feed concentration was 0.5M. At this feed concentration, MEA showed obvious salting out (dashed line) after 800 seconds, and the current density (solid line) also showed a significant decrease; at 1000 seconds, the anolyte concentration was switched to 0.2M, and the volume fraction of salting out decreased significantly, while the current density continued to decrease for a period of time and then only increased slightly; at 1500 seconds, the anolyte concentration was switched to 0.5M, and the volume fraction of salting out increased again, while the current density also increased significantly and then decreased slightly. Figure 5 As shown, it is the result of changing the applied voltage to suppress salting out and maintain the electrochemical performance of MEA under constant anode electrolyte concentration. From 0 to 1000 seconds, the voltage applied to the anode is 3.25V. Under this voltage, MEA showed obvious salting out (dashed line) after 800 seconds, and the current density (solid line) also showed a significant decrease; at 1000 seconds, the voltage applied to the anode was switched to 3.2V, the volume fraction of salting out decreased significantly, and the current density dropped instantly at 1000 seconds and then continued to rise slightly; at 1500 seconds, the voltage applied to the anode was switched to 3.25V, the volume fraction of salting out increased again, and the current density rose instantly at 1500 seconds and then dropped slightly.

[0125] The present invention is built on the COMSOL Multiphysics platform. Through the COMSOL Multiphysics model developer, the multi-physical fields of MEA are set, including gas-liquid phase concentration field, gas-liquid phase pressure field, solid-liquid phase potential field, reasonable initial values ​​and boundary conditions are set, the grid is divided using the built-in grid division function of the software, and a steady-state research module is added to solve the concentration field, pressure field and potential field of the model under different parameters. At this time, the salting-out module is temporarily disabled, and the CO 2 The salting-out potential of MEA is then calculated by adding a transient study module and enabling the salting-out module to solve the effect of salting-out on MEA at different times and the changes in system performance after applying the strategy.

[0126] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A modeling method for multi-physical fields of a membrane electrode electrolyzer, characterized in that: The following steps are involved: Step S1, obtaining device-related structural parameters, physical property parameters and chemical reaction parameters; Step S2, constructing a MEA multi-physical field numerical model according to the acquired physical property parameters, wherein the multi-physical fields include gas phase concentration field, liquid phase concentration field, gas phase pressure field, liquid phase pressure field, ionomer water mass transfer, solid phase potential field, liquid phase potential field, and salt precipitation occurrence field; Step S3, analyzing the calculation results of the numerical model to determine the salting-out potential and salting-out current density of the CO2 membrane electrode assembly under operating conditions; Step S4, adjusting various design parameters of MEA, and determining the most suitable design parameters according to the occurrence of salt precipitation and the comprehensive performance of the device; Step S5, suppressing the occurrence of salting out by adjusting relevant input parameters under the corresponding salting out potential.

2. A membrane electrode electrolyzer multi-physical field modeling method according to claim 1, characterized in that: The gas phase concentration field is a mixture average model, which is used to describe the mass transfer process of gas phase substances inside the anode and cathode. Its expression is: where n j is the flux of gas phase species j, ρ g is the density of the gas phase, is the effective diffusion coefficient of gas phase species j, ω j is the mass fraction of gas phase species j, M n is the average molar mass of the gas mixture, ρ i is the partial density of the gas phase, u g is the convection velocity of the gas phase.

3. A membrane electrode electrolyzer multi-physical field modeling method according to claim 1, characterized in that: The liquid concentration field is the Nernst–Planck equation, which is used to describe the mass transfer process of liquid substances inside the anode and cathode. Its expression is: where n i is the flux of liquid species i, is the effective diffusion coefficient of liquid phase substance i, c i is the molar concentration of liquid substance i, z i is the charge number of liquid substance i, F is the Faraday constant, R is the molar gas constant, T is the temperature, φ l is the liquid phase potential.

4. A membrane electrode electrolyzer multi-physical field modeling method according to claim 1, characterized in that: The gas-liquid phase pressure field is described by Darcy's law, which is expressed as follows: Among them, u m is the convection velocity of medium m, is the effective permeability of medium m, μ m is the dynamic viscosity of the medium, p m is the pressure of medium m.

5. The modeling method of a membrane electrode electrolyzer multi-physical field according to claim 1, characterized in that: The solid-liquid phase potential satisfies Ohm's law, and its expression is as follows: Among them, i s is the solid phase current density, i l is the liquid phase current density, is the effective specific surface area, i k is the current density of the electrode reaction k.

6. A membrane electrode electrolyzer multi-physical field modeling method according to claim 1, characterized in that: The reaction rate of the salting-out substance is expressed as follows: Where R is the salting-out reaction rate, ε is the volume fraction of salt, k is the deposition rate constant, K sp is the solubility product of the salt and s is the stoichiometric number.

7. The modeling method of a membrane electrode electrolyzer multi-physical field according to claim 1, characterized in that: The analysis process of step S3 includes comparing the ion concentration product under the steady-state model with the salt solubility product. If the ion concentration product is greater than the salt solubility product, it is considered that salting out will occur. The potential and current density under this condition are the salting out potential and the salting out current density.

8. The modeling method of a membrane electrode electrolyzer multi-physical field according to claim 1, characterized in that: The design parameters regulated in step S4 include the thickness of the catalyst layer, the specific surface area of ​​the catalyst layer, the thickness of the anion exchange membrane, and the ion exchange capacity of the anion exchange membrane.

9. A membrane electrode electrolyzer multi-physical field modeling method according to claim 1, characterized in that: The response strategy of step S5 includes regulating the concentration of the anode electrolyte and the voltage applied to the device. By changing the above input conditions, the occurrence of salt precipitation is suppressed and the current density of the device is maintained.

10. A modeling device for multi-physical fields of a membrane electrode electrolyzer, characterized in that: It includes parameter acquisition module, model building module, numerical analysis module, parameter adjustment module and application module, among which: Parameter acquisition module, used to obtain device-related structural parameters, physical property parameters and chemical reaction parameters; A model building module is used to build a MEA multi-physical field numerical model based on the acquired physical property parameters, wherein the multi-physical fields include gas phase concentration field, liquid phase concentration field, gas phase pressure field, liquid phase pressure field, ionomer water mass transfer, solid phase potential field, liquid phase potential field, and salt precipitation occurrence field; Numerical analysis module, used to analyze the calculation results of the numerical model and determine the salting-out potential and salting-out current density of the CO2 membrane electrode assembly under operating conditions; Parameter adjustment module, used to adjust various design parameters of MEA, and determine the most suitable design parameters according to the occurrence of salt precipitation and the comprehensive performance of the device; The application module is used to inhibit the occurrence of salting out by adjusting relevant input parameters under the corresponding salting out potential.

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