A mass transfer kinetics simulation method, system and medium for electrosorption desalination

Abstract

The present invention discloses a mass transfer kinetics simulation method, system and medium for electrosorption desalination, which includes measuring the impedance of electrodes of CDI equipment at different frequencies, generating Nyquist diagrams or Bode diagrams of the electrode electrochemical reaction process; establishing a Randles equivalent circuit for simulating the electrode electrochemical reaction process and fitting equivalent parameters according to the impedance data in the Nyquist diagram or Bode diagram; constructing a CDI equivalent circuit for correcting the conductivity parameters of the electrolyte solution in a transient state, combining the fitted equivalent parameters of the Randles equivalent circuit to correct and calculate the equivalent circuit parameters of the CDI equivalent circuit, and calculating the parameter indicators of the CDI equipment through mass transfer kinetics simulation in the simulation software. The present invention aims to realize the simulation prediction of CDI equipment to provide guidance on flow channel design, structural layout and durability for CDI equipment in the research and development and optimization stages.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment and desalination, and in particular to a mass transfer kinetics simulation method, system and medium for electric adsorption desalination. Background Art

[0002] At present, there are many technologies applied to the desalination of aqueous solutions, such as reverse osmosis (RO) technology, multi-stage flash evaporation (MSF) technology, electrodialysis (ED) technology, capacitive deionization (CDI) technology, etc. Among them, capacitive deionization (CDI) technology is a new desalination technology. By applying external electric field conditions, ions in the solution are directed to move toward electrodes with opposite electrical properties, and a stable electrical double layer (EDL) is formed on the surface of the electrode. The ions are temporarily stored in the double layer, thereby achieving the CDI desalination effect. As desalination proceeds, when the double layer adsorption capacity of the electrode reaches saturation, the electrode desorption regeneration effect can be achieved by simply disconnecting the external power supply or reversing the power supply. Due to its low energy consumption, environmental friendliness, simple operation and regenerative nature of the electrode, it shows great potential in the field of water treatment and desalination. With the continuous improvement of technology, CDI is expected to play a more important role in future water treatment applications.

[0003] CDI equipment is a desalination equipment that uses capacitive deionization (CDI) technology. Generally, CDI equipment has two high-surface porous carbon-based electrodes, electrolyte channels, external power supplies, and connecting brackets and external shells. At the same time, control systems, water flow systems, regeneration systems, etc. are used to control and monitor CDI working conditions. The brine to be treated first undergoes simple pretreatment to remove impurities such as suspended matter and organic matter. When CDI enters the working cycle, it first provides DC voltage to the electrodes, and the equipment adsorbs and desalinates the electrolyte solution. The equipment produces fresh water. When the expected desalination treatment and double-layer adsorption capacity are achieved, the electrode regeneration mode is entered, and the equipment produces concentrated water. After the electrode regeneration is completed, the above operations can be repeated to enter the next working cycle. By modeling the geometric shape and dividing the corresponding calculation domain, the full cycle simulation of the CDI equipment can be realized in the finite element software through input parameters such as potential boundary conditions, concentration boundary constraints, and flow rate. Although the working principle of CDI technology is similar to the charging and discharging process of a capacitor, it is not easy to correctly predict and judge the working conditions, internal flow field distribution, mass transfer effect and adsorption and desalination capacity of CDI equipment. The main external variable factors of CDI equipment in the actual operation process are: external potential, electrolyte solution flow rate, electrolyte substance concentration, electrode materials with different high specific surface areas and different adsorption characteristics of different materials. Any variable may cause adsorption differences in CDI. Reasonable design of CDI equipment needs to focus on the main mass transfer processes occurring in the electrolyte solution: convection, diffusion, electromigration, and the adsorption and storage of ions by the double electric layer at the interface between the electrode and the electrolyte solution. Due to the characteristics of low cost and no additional pollution, CDI technology has been used in application scenarios such as wastewater treatment and seawater desalination. Further development of CDI technology is of great practical significance. Using multi-physics simulation software such as COMSOL Multiphysics to perform virtual simulation of CDI equipment, the working conditions and production efficiency of CDI equipment can be predicted, which can improve the operating efficiency of the CDI system. Existing simulation models implemented using multi-physics software such as COMSOL have problems such as long simulation calculation time, poor simulation accuracy, and poor simulation convergence. Most simulations are still in the two-dimensional scale and only use relatively simple electrostatic adsorption. Currently, there are a few models that can achieve three-dimensional full-scale simulation, and they only consider convection and diffusion in the mass transfer process. They lack the time-varying internal spatial concentration distribution reflected by electromigration, and cannot provide guidance for CDI equipment in terms of flow channel design, structural layout, and durability during the R&D and optimization stages.

[0004] At present, there are works using equivalent circuit methods to simulate CDI devices. For example, the prior art discloses a method for simulating CDI devices based on Randles equivalent circuits. This method constructs a circuit based on a simplified Randles circuit and is directly used for CDI equivalent by adding resistors and capacitors. The value of the current in the double-layer capacitor charging process of the circuit during the charging response process (i.e., transient process) is decoupled, and the amount of ions adsorbed by the double layer formed on the interface between the electrode and the electrolyte solution during the operation of the CDI device is converted using the law of conservation of charge. The diffusion and convection of substances in the electrode and the electrolyte solution are calculated by the Nernst-Planck equation that ignores electromigration. It is worth noting that the method for establishing the Randles equivalent circuit in this method is not based on the electrochemical reaction process to model the amount of ions adsorbed by the double layer under the electric drive response, because the most critical step in the entire decoupling process is to obtain the amount of ions adsorbed by the double layer under the electric drive response. Instead, the entire circuit is modeled from the perspective of the circuit. The circuit elements used include series circuit resistance, current leakage resistance, and double-layer capacitance. The circuit element characteristics of resistance and capacitance under transient response are combined with the established circuit to deduce: the function expression of the external voltage Vext and the total current i changing with time t. The data of the external voltage Vext and the total current i changing with time t are then measured experimentally, and the exact values ​​of the series circuit resistance, current leakage resistance, and double-layer capacitance are obtained by fitting with numerical calculation software such as MATLAB. Using this equivalent decoupling method from the perspective of circuit, the double-layer adsorption formed on the interface of the electrode and the electrolyte solution during the operation of the CDI device can be simulated more accurately, and the obtained material adsorption concentration curve that describes the material adsorption can also achieve good results as expected. However, this prior art has some fatal defects: 1. The model cannot describe the phenomenon of ion electromigration in the electrolyte solution caused by electroadsorption, resulting in the inability to obtain the spatial concentration distribution of ions changing with time, which is crucial for optimizing the CDI device through simulation technology; 2. It does not take into account that the conductivity of the electrolyte solution will change periodically with the operation of the CDI device. Since the values ​​of each component in the equivalent circuit are fixed, there is no way to reflect the dynamic process of CDI operation; 3. The equivalent process is an equivalent replacement of the effect of the entire charging process of the CDI device, and the fitted result is also a comprehensive effect within a single charging cycle. Therefore, the effect of decoupling when simulating in the simulation software is also uniformly and averagely applied to the transient calculation process; 4. The universality of the equivalent circuit model extracted by relying on the circuit response needs to be investigated. This method is more accurate at lower voltages, but less accurate for higher voltages. This is mainly because the method uses 0.6V voltage measurement to predict numerical artifacts for the entire data range instead of fitting all data simultaneously, and the physical error is mainly attributed to nonlinear capacitance. Summary of the invention

[0005] Technical problem to be solved by the present invention: In view of the above-mentioned problems in the prior art, a mass transfer kinetics simulation method, system and medium for electrosorption desalination are provided. The present invention aims to realize simulation prediction of CDI equipment to provide guidance on flow channel design, structural layout and durability for CDI equipment in the research and development and optimization stages.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A mass transfer kinetics simulation method for electrosorption desalination comprises the following steps:

[0008] Measuring the impedance of the electrodes of the CDI device at different frequencies;

[0009] Generate Nyquist diagram or Bode diagram of the electrochemical reaction process of the electrode according to the impedance of the electrode at different frequencies;

[0010] Establish a Randles equivalent circuit for simulating the electrochemical reaction process of the electrode, and obtain the fitting equivalent parameters of the Randles equivalent circuit according to the impedance data in the Nyquist diagram or Bode diagram;

[0011] Construct a CDI equivalent circuit for correcting the conductivity parameters of the electrolyte solution in the transient state, and correct and calculate the equivalent circuit parameters of the CDI equivalent circuit by combining the fitted equivalent parameters of the Randles equivalent circuit;

[0012] The parameter indicators of CDI equipment are calculated by mass transfer kinetics simulation in the simulation software according to the CDI equivalent circuit.

[0013] Optionally, the Randles equivalent circuit consists of a first series circuit resistor R s , the first parallel circuit and the impedance Warburg are connected in series. The fitting equivalent parameters of the Randles equivalent circuit include the first series circuit resistance R s , polarization resistance R L and the first double layer capacitance C dl1 Parameter value.

[0014] Optionally, fitting the fitting equivalent parameters of the Randles equivalent circuit according to the impedance data in the Nyquist diagram or the Bode diagram includes: fitting the fitting equivalent parameters of the Randles equivalent circuit according to the impedance data in the Nyquist diagram or the Bode diagram, and if the fitting is successful, determining the fitting equivalent parameters of the Randles equivalent circuit; otherwise, readjusting the fitting equivalent parameters of the Randles equivalent circuit and fitting the fitting equivalent parameters of the Randles equivalent circuit again according to the impedance data in the Nyquist diagram or the Bode diagram until the fitting is successful.

[0015] Optionally, the CDI equivalent circuit is composed of a power supply, a second series circuit resistor R s0 , the second parallel circuit, the electrolyte solution resistance R s(c) and another second parallel circuit connected end to end to form a loop, wherein the second parallel circuit is composed of a charge transfer resistor R ct and the second double layer capacitance C dl The second series circuit resistor R s0 It is used to equalize various fixed resistances or resistances that are not easy to cause fluctuations generated by the circuit wires and interfaces, collectors, and porous media contacts between collectors and electrodes during the operation of CDI equipment, charge transfer resistance R ct Used to equalize the resistance of charge transfer process at the interface between electrode and electrolyte in electrochemical process, double layer capacitance C dl For charge storage characteristics at the interface between equivalent electrodes and electrolytes, the electrolyte solution resistance R s(c) Used to equalize the resistance of the electrolyte solution filled between the electrode plates when the CDI device is running.

[0016] Optionally, the equivalent circuit parameters of the CDI equivalent circuit are calculated by correcting the equivalent parameters of the fitted Randles equivalent circuit, including: s The resistance value of the second series circuit is obtained by subtracting the resistance value of the electrolyte solution used to measure the impedance of the electrode at different frequencies. s0 resistance value; when measuring the impedance of the electrode at different frequencies, the polarization resistance R in the Randles equivalent circuit obtained by fitting is used L The value of the charge transfer resistance R ct The value of the first double-layer capacitance C is obtained by dividing the surface area of ​​the electrode used to measure the impedance of the electrode at different frequencies by the preset surface area. dl1 The parameter value is multiplied by the linear correction coefficient to obtain the second double-layer capacitance C dl If the voltage of the power supply is different from the voltage used to measure the impedance of the electrode at different frequencies, the second double-layer capacitance C dl The parameter value is interpolated to the voltage of the power supply according to the voltage; the concentration of the electrolyte solution at each location is arithmetic averaged when measuring the impedance of the electrode at different frequencies to obtain the electrolyte solution concentration c, and then the electrolyte solution concentration c is substituted into the electrolyte solution concentration c and the electrolyte solution resistance R s(c) The electrolyte solution resistance R is obtained by the relationship function s(c) Parameter value.

[0017] Optionally, the second double-layer capacitor C dlThe parameter value of is interpolated to the voltage of the power supply according to the voltage, including: calculating the impedance of the measuring electrode at different frequencies respectively under two reference voltages, one high and one low, multiplied by the linear correction coefficient to obtain the second double-layer capacitance C dl The parameter value is then combined with the interpolation calculation formula to calculate the interpolated second double-layer capacitance C under the voltage of the CDI equivalent circuit. dl Parameter value.

[0018] Optionally, the parameter index of the CDI device calculated by mass transfer kinetics simulation in simulation software according to the CDI equivalent circuit includes:

[0019] According to the constructed CDI equivalent circuit and Ohm's law, the boundary potential V applied to the electrode of the CDI device is calculated with the help of ordinary differential equations in the simulation software, and the boundary potential V and ground zero potential are input on the corresponding electrodes by calling the modules related to electric field distribution in the simulation software;

[0020] In the porous electrode property node of the electrode of the CDI device in the finite element software, set the charge transfer resistance R ct and the second double layer capacitance C dl Parameter value of

[0021] Calculating the Conductivity of Electrolyte Solutions Using Ordinary Differential Equations in Simulation Software , and the conductivity of the electrolyte solution is Input to the Electrolyte Solution Conductivity node in the Current Distribution module;

[0022] The electrolyte potential phil is used for coupling calculation in the electrolyte solution calculation domain, and the potential phis is used for coupling calculation in the porous electrode domain of the electrode;

[0023] The simulation software is used to calculate the flow field of porous media containing electrodes using the Brinkman equation. The Darcy flow calculation principle is used in the porous media to couple the flow field data to the dilute material transfer field calculation.

[0024] Set the second double-layer capacitance C in the electrode under the current distribution node of the finite element software dl , and set up an electrode reaction coupling to convert the double-layer capacitance current data into ion reaction adsorption flux for statistics, so as to couple the adsorption and desorption of the double layer in the dilute material transfer field with the current distribution calculation field in both directions;

[0025] Set the boundary and perform the solution in the simulation software: first, perform the steady-state operation of the flow field Brinkman equation, and the solution settings all use the system default "physical field control", and use the steady-state data set solved and calculated as the initial value of the next transient operation; wherein the transient operation needs to include: current distribution physical field, dilute species transfer physical field, ordinary differential equations, and select "full coupling" calculation and solution in the solver configuration, set the external voltage during adsorption and desorption of the CDI device, solve and calculate a complete adsorption and desorption operation cycle, and obtain the solution result, which includes the concentration change diagram at the outlet of the CDI device over time, the ion spatial concentration distribution change diagram over time, the double layer current source, and part or all of the porous electrode adsorption ion amount change diagram over time;

[0026] The solution result is processed to extract parameter indicators of the CDI device, including part or all of the parameter indicators of the CDI device, such as desalination capacity, desalination rate, energy efficiency and operation efficiency.

[0027] In addition, the present invention also provides a mass transfer kinetics simulation system for electrosorption desalination, comprising a microprocessor and a memory connected to each other, wherein the microprocessor is programmed or configured to execute the mass transfer kinetics simulation method for electrosorption desalination.

[0028] In addition, the present invention also provides a computer-readable storage medium, in which a computer program or instruction is stored. The computer program or instruction is programmed or configured to execute the mass transfer kinetics simulation method of electrosorption desalination through a processor.

[0029] In addition, the present invention also provides a computer program product, including a computer program or instructions, wherein the computer program or instructions are programmed or configured to execute the mass transfer kinetics simulation method for electrosorption desalination through a processor.

[0030] Compared with the prior art, the present invention mainly has the following advantages: the present invention comprises measuring the impedance of the electrode of the CDI device at different frequencies, generating a Nyquist diagram or a Bode diagram of the electrode electrochemical reaction process; establishing a Randles equivalent circuit for simulating the electrode electrochemical reaction process and fitting equivalent parameters according to the impedance data in the Nyquist diagram or the Bode diagram; constructing a CDI equivalent circuit for correcting the conductivity parameters of the electrolyte solution in a transient state, combining the fitted equivalent parameters of the Randles equivalent circuit to correct and calculate the equivalent circuit parameters of the CDI equivalent circuit, and simulating and calculating the parameter indicators of the CDI device in the simulation software. The present invention can realize the simulation prediction of the CDI device, can effectively consider the adsorption differences caused by various key variables in the operation of the CDI device and achieve three-dimensional full-scale simulation accuracy, can effectively output parameters such as the material adsorption concentration curve, the spatial concentration distribution of ions changing with time, and the current response in the transient state of operation, thereby providing guidance on flow channel design, structural layout and durability for the CDI device in the research and development and optimization stages. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the basic flow of the method of the embodiment of the present invention.

[0032] Figure 2 It is the Randles equivalent circuit in the embodiment of the present invention.

[0033] Figure 3 It is an applicable CDI equivalent circuit in the embodiment of the present invention.

[0034] Figure 4 This is a CDI simulation flow chart in an embodiment of the present invention.

[0035] Figure 5 Schematic diagram of the geometric configuration of the CDI device in the embodiment of the present invention.

[0036] Figure 6 is the outlet ion concentration varying with time in the embodiment of the present invention.

[0037] Figure 7 This is the ion concentration distribution of the CDI device in the embodiment of the present invention at the 10th second of operation.

[0038] Figure 8 This is the ion concentration distribution of the CDI device in the embodiment of the present invention at the 500th second of operation.

[0039] Fig. 9 This is the ion concentration distribution at the 2000th second of operation of the CDI device in the embodiment of the present invention.

[0040] Fig.10 This is the ion concentration distribution at the 3300th second of the operation of the CDI device in the embodiment of the present invention.

[0041] Fig.11 This is the ion concentration distribution of the CDI device in the embodiment of the present invention at the 5000th second of operation. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. The present embodiment provides a method, system and structure for simulating mass transfer kinetics of electrosorption desalination, which can effectively consider the adsorption differences caused by key variables in the operation of CDI (Capacitive Deionization), and achieve three-dimensional full-scale simulation accuracy, and can effectively output parameters such as material adsorption concentration curves, spatial concentration distribution of ions over time, and current response in transient operation. Existing models that use equivalent circuit theory to simulate CDI equipment do not consider the problem that the conductivity of the electrolyte solution will show periodic changes with the operation of the CDI equipment, and cannot characterize the electrical migration phenomenon of ions in the electrolyte solution caused by electrosorption, and cannot obtain the spatial concentration distribution of ions over time. Figure 1 As shown, the mass transfer kinetics simulation method for electrosorption desalination in this embodiment includes the following steps:

[0043] Measuring the impedance of the electrodes of the CDI device at different frequencies;

[0044] Generate Nyquist diagram or Bode diagram of the electrochemical reaction process of the electrode according to the impedance of the electrode at different frequencies;

[0045] Establish a Randles equivalent circuit for simulating the electrochemical reaction process of the electrode, and obtain the fitting equivalent parameters of the Randles equivalent circuit according to the impedance data in the Nyquist diagram or Bode diagram;

[0046] Construct a CDI equivalent circuit for correcting the conductivity parameters of the electrolyte solution in the transient state, and correct and calculate the equivalent circuit parameters of the CDI equivalent circuit by combining the fitted equivalent parameters of the Randles equivalent circuit;

[0047] The parameter indicators of CDI equipment are calculated by mass transfer kinetics simulation in the simulation software according to the CDI equivalent circuit.

[0048] In this embodiment, the impedance of the electrode of the CDI device at different frequencies is measured by electrochemical impedance spectroscopy (EIS). Electrochemical impedance spectroscopy (EIS) is a technology used to study the dynamics of electrochemical systems. It obtains information about electrode processes and electrolyte behaviors by measuring the impedance of the system at different frequencies. EIS analysis technology provides a powerful method for revealing the properties of electrode materials and the mechanisms within electrochemical systems. It is usually combined with an equivalent circuit model to further study and understand the electrochemical reaction process occurring at the interface between the electrode and the electrolyte solution. Through EIS analysis technology and fitting equivalent circuits, the electrochemical system can be optimized in a targeted manner, thereby improving the stability and performance of the entire system. EIS (electrochemical impedance spectroscopy) analysis and measurement technology is to obtain the impedance data of the electrode response at different frequencies by applying a very small alternating current frequency to the electrode when performing electrochemical impedance spectroscopy measurements (the amplitude of this alternating voltage signal is usually very small, generally in the range of a few millivolts to tens of millivolts). Frequency response can be divided into low frequency band, medium frequency band and high frequency band. The frequency used in the test has no clear upper and lower boundaries, usually ranging from very low frequency (such as millihertz level) to very high frequency (such as kilohertz level). EIS analysis measurement can be performed by an electrochemical workstation and the Nyquist Diagram or Bode Diagram can be exported. The impedance data will be included in the Nyquist Diagram or Bode Diagram for subsequent use.

[0049] like Figure 2 As shown, the Randles equivalent circuit of this embodiment consists of a first series circuit resistor R s , the first parallel circuit and the impedance Warburg are connected in series. The fitting equivalent parameters of the Randles equivalent circuit include the first series circuit resistance R s , polarization resistance R L and the first double layer capacitance C dl1Parameter values. The Randles equivalent circuit is a classic simplified circuit model that simulates the electrochemical process of electrodes. It can reliably study and simulate various electrochemical systems and processes. Using EIS analysis technology to test CDI equipment and modeling the Randles equivalent circuit can predict the performance of CDI under different working conditions, and quickly and accurately evaluate system parameters while effectively reducing complexity. The Randles equivalent circuit usually includes the following basic components: electrolyte resistance, polarization resistance (charge transfer resistance), double layer capacitance, and fixed resistance. If the impedance caused by ion diffusion needs to be described, the Warburg impedance can be connected in series on the basis of the electrolyte resistance. It is understandable that the results of obtaining the Nyquist diagram and Bode diagram through the electrochemical analysis measurement technology EIS, and then using the circuit data fitting software to establish the equivalent circuit are not single. Different equivalent circuits can be established according to the possible electrochemical processes. This case uses the classic simplified Randles equivalent circuit to fit the polarization resistance and double layer capacitance of the electrode surface.

[0050] In this embodiment, fitting the Randles equivalent circuit according to the impedance data in the Nyquist diagram or the Bode diagram includes: fitting the Randles equivalent circuit according to the impedance data in the Nyquist diagram or the Bode diagram, and determining the fitting equivalent parameters of the Randles equivalent circuit if the fitting is successful; otherwise, readjusting the fitting equivalent parameters of the Randles equivalent circuit and fitting the Randles equivalent circuit according to the impedance data in the Nyquist diagram or the Bode diagram again until the fitting is successful. There is a strong correlation between the equivalent circuit parameters obtained by fitting the impedance data in the Nyquist diagram and the equivalent circuit established and used. Only by establishing a reasonable and applicable equivalent circuit can the impedance data in the Nyquist diagram be well fitted. If the established equivalent circuit is reasonable, then the Nyquist diagrams obtained by the equivalent circuit at different frequency responses and the Nyquist diagrams obtained by the original EIS analysis test have a high degree of overlap, and the fitting is completed; if the established equivalent circuit is unreasonable, then the Nyquist diagrams obtained by the equivalent circuit at different frequency responses and the Nyquist diagrams obtained by the original EIS analysis test cannot overlap well, or only partially overlap, and it is necessary to return to adjust the fitting equivalent parameters of the equivalent Randles circuit.

[0051] like Figure 3 As shown, the CDI equivalent circuit in this embodiment is composed of a power supply, a second series circuit resistor R s0 , the second parallel circuit, the electrolyte solution resistance R s(c)and another second parallel circuit connected end to end to form a loop, wherein the second parallel circuit is composed of a charge transfer resistor R ct and the second double layer capacitance C dl The parallel circuit is used to characterize the electrochemical reactions occurring simultaneously at the double electrical layer interface, where the second series circuit resistor R s0 It is used to equalize various fixed resistances or resistances that are not easy to cause fluctuations generated by the circuit wires and interfaces, collectors, and porous media contacts between collectors and electrodes during the operation of CDI equipment, charge transfer resistance R ct Used to equalize the resistance of charge transfer process at the interface between electrode and electrolyte in electrochemical process, double layer capacitance C dl For charge storage characteristics at the interface between equivalent electrodes and electrolytes, the electrolyte solution resistance R s(c) Used to equalize the resistance of the electrolyte solution filled between the electrode plates when the CDI device is running. Two sets of charge transfer resistors R ct and the second double layer capacitance C dl The parallel circuit is used to characterize the electrochemical reactions occurring on the cathode and anode sides of a typical CDI device. If necessary, the different properties and values ​​of the cathode and anode can be set differently.

[0052] Since the environment in which the EIS electrode is tested is different from the environment in which the CDI equipment is running, it is necessary to correct the parameters of the constructed CDI equivalent circuit. s It is used to equal various fixed resistances or resistances that are not easy to cause fluctuations generated by the circuit wires and interfaces, collectors, and the contact between collectors and porous media during CDI operation. This value can be indirectly approximated using the value obtained in the EIS analysis test: subtract the resistance value of the electrolyte solution used in the EIS test from the resistance value of the series circuit in the fitted Randles equivalent circuit. The resistance value of the electrolyte solution used in the EIS test can be directly measured by a conductivity meter. Electrolyte solution resistance R s(c) It is used to equal the resistance of the electrolyte solution filled between the electrode plates when the CDI device is running. Since the ions are unevenly distributed in the internal space when the CDI device is running, and the spatial position and quantity will change in real time as the desalination progresses, in order to accurately calculate and correct the resistance in real time during the CDI simulation process, the ion valence, ion diffusion coefficient, ion concentration and other values ​​in the electrolyte solution and the assumption of neutrality of the electrolyte solution are used to appropriately simplify and derive the real-time corrected electrolyte solution resistance. Ignoring the resistance change caused by diffusion in the electrolyte solution, the Nernst-Einstein relationship is used: ( is the diffusion coefficient of an ion in the electrolyte solution, R is the universal gas constant, Tis the thermodynamic temperature), using the diffusion coefficient To replace mobility in electromigration Through a series of simplifications, the calculation formula for the conductivity of the electrolyte solution is obtained:

[0053] ,

[0054] Among them, Z i It represents the valence of an ion in an electrolyte solution. F is the Faraday constant, is the diffusion coefficient of an ion in the electrolyte solution, It is expressed as the concentration of a certain ion in the electrolyte solution, R is the universal gas constant, and T is the thermodynamic temperature. By calling the data coupling interface of the simulation software and the above principle formula, the electrolyte solution resistance R can be calculated in real time. s(c) , to achieve the effect of automatically correcting the equivalent circuit resistance value with the transient calculation of the simulation. Charge transfer resistance R ct It is used to equalize the resistance of the charge transfer process at the interface between the electrode and the electrolyte in the electrochemical process. This resistance is closely related to the kinetics of the electrode reaction. In electrochemical impedance spectroscopy (EIS) analysis, it is usually determined by fitting the semicircle on the Nyquist plot, which reflects the impedance of the charge transfer process. Charge transfer resistance R ct The double layer capacitance C dl They are usually connected in parallel in the equivalent circuit model to describe the electrode process together. In the constructed CDI equivalent circuit, the charge transfer resistance R ct The polarization resistance R obtained by EIS analysis can be directly used L In order to obtain the solution accuracy, at the expense of some computational efficiency, a more complex model with nonlinear characteristics can also be used to describe the resistance, such as the Butler-Volmer equation and Tafel equation that describe the electrochemical reaction kinetics. The second double layer capacitance C dl Used to store charge at the interface between the equivalent electrode and electrolyte. Different electrode materials have different double-layer capacitance characteristics, and the size of the double-layer capacitance is related to the surface area of ​​the electrode. The larger the surface area, the more charge can be stored. Since the electrode used in the EIS test has the same material properties as the electrode in the CDI device, but the surface area is different. In the constructed CDI equivalent circuit, the second double-layer capacitance C dl The value of the second double-layer capacitance C is obtained by EIS analysis. dl The value of is linearly corrected according to the surface area. Therefore, in this embodiment, the equivalent circuit parameters of the CDI equivalent circuit calculated by correcting the equivalent parameters of the Randles equivalent circuit fitting include:

[0055] The first series circuit resistance R in the fitted Randles equivalent circuit s The resistance value of the second series circuit is obtained by subtracting the resistance value of the electrolyte solution used to measure the impedance of the electrode at different frequencies. s0 The resistance value;

[0056] The polarization resistance R in the Randles equivalent circuit obtained by fitting is used to measure the impedance of the electrode at different frequencies. L The value of the charge transfer resistance R ct The value of

[0057] The surface area of ​​the electrode used to measure the impedance of the electrode at different frequencies is divided by the preset surface area to obtain a linear correction coefficient, and the first double-layer capacitance C dl1 The parameter value is multiplied by the linear correction coefficient to obtain the second double-layer capacitance C dl If the voltage of the power supply is different from the voltage used to measure the impedance of the electrode at different frequencies, the second double-layer capacitance C dl The parameter value is interpolated to the voltage of the power supply according to the voltage;

[0058] The concentration of the electrolyte solution at each location is calculated by taking the arithmetic average of the impedance of the measuring electrode at different frequencies to obtain the electrolyte solution concentration c, and then substituting the electrolyte solution concentration c into the electrolyte solution concentration c and the electrolyte solution resistance R. s(c) The electrolyte solution resistance R is obtained by the relationship function s(c) Parameter value.

[0059] When the electrode potential changes, the charge state of the electrode surface will change, which in turn affects the number and type of ions adsorbed on the electrode surface, resulting in the second double layer capacitance C dl By changing the potential scanning rate of cyclic voltammetry (CV test) or the potential conditions applied in EIS test, the second double layer capacitance C under different potential conditions can be obtained. dl When the simulation experiment of CDI equipment only explores various predicted requirements under a certain constant voltage, the potential condition test can be directly used in the EIS analysis test to obtain the second double-layer capacitance C according to the above Randles equivalent circuit. dl The value of is corrected and inserted into the constructed CDI equivalent circuit; when the simulation of CDI equipment has various prediction requirements under different constant voltages, two appropriate potential conditions (one high and one low) can be selected for testing during EIS analysis and testing, and the corresponding second double-layer capacitance C can be obtained according to the above Randles equivalent circuit. dl The value of the second double-layer capacitance C under other potential conditions is then obtained by linear interpolation. dlThe value of is corrected and inserted into the constructed CDI equivalent circuit. If experimental conditions permit, multiple sets of experiments can also be performed to extract the second double-layer capacitance C dl Parameters, build a corresponding database or get the fitting function under different voltages, and directly call the second double-layer capacitance C in the simulation. dl In some applicable scenarios, you can also query the empirical formula in the relevant literature to make numerical corrections. In this embodiment, the second double-layer capacitor C dl The parameter value of is interpolated to the voltage of the power supply according to the voltage, including: calculating the impedance of the measuring electrode at different frequencies respectively under two reference voltages, one high and one low, multiplied by the linear correction coefficient to obtain the second double-layer capacitance C dl The parameter value is then combined with the interpolation calculation formula to calculate the interpolated second double-layer capacitance C under the voltage of the CDI equivalent circuit. dl Parameter value.

[0060] In this embodiment, the parameter indicators of the CDI device calculated by mass transfer kinetics simulation in the simulation software according to the CDI equivalent circuit include:

[0061] Step 1: According to the constructed CDI equivalent circuit and Ohm's law, the boundary potential V applied to the electrode of the CDI device is calculated with the help of ordinary differential equations in the simulation software, and the boundary potential V and ground zero potential are input on the corresponding electrodes by calling the modules related to electric field distribution in the simulation software;

[0062] Step 2: In the porous electrode property node of the electrode of the CDI device in the finite element software, set the charge transfer resistance R ct and the second double layer capacitance C dl Parameter value of

[0063] Step 3: Calculate the conductivity of the electrolyte solution using ordinary differential equations in the simulation software , and the conductivity of the electrolyte solution is Input to the Electrolyte Solution Conductivity node in the Current Distribution module;

[0064] Step 4, use the electrolyte potential phil to perform coupling calculations in the electrolyte solution calculation domain, and use the potential phis to perform coupling calculations in the porous electrode domain of the electrode;

[0065] Step 5, using simulation software to calculate the flow field of the porous medium containing the electrode using the Brinkman equation, using the Darcy flow calculation principle in the porous medium to couple the flow field data to the dilute material transfer field calculation;

[0066] Step 6: Set the second double-layer capacitance C in the electrode under the current distribution node of the finite element software. dl, and set up an electrode reaction coupling to convert the double-layer capacitance current data into ion reaction adsorption flux for statistics, so as to couple the adsorption and desorption of the double layer in the dilute material transfer field with the current distribution calculation field in both directions;

[0067] Step 7, set the boundary in the simulation software and perform the solution: first, perform the steady-state operation of the flow field Brinkman equation, and the solution settings all use the system default "physical field control", and use the steady-state data set solved and calculated as the initial value of the next transient operation; wherein the transient operation needs to include: current distribution physical field, dilute species transfer physical field, ordinary differential equation, and select "full coupling" calculation and solution in the solver configuration, set the external voltage of the CDI device during adsorption and the external voltage during desorption (in this embodiment, the external voltage of the CDI device during adsorption is set to 0.6V, and the external voltage during desorption is set to 0V), solve and calculate a complete adsorption and desorption operation cycle (in this case, the finite element software is used to calculate the transient calculation of 6000s, and the power supply is short-circuited at 3000s), and obtain the solution result, which includes the concentration change diagram at the outlet of the CDI device over time, the ion space concentration distribution change diagram over time, the double layer current source, and the porous electrode adsorption ion amount change diagram over time. Part or all;

[0068] Step 8, extract the parameter indicators of the CDI equipment from the solution results, including some of the parameter indicators of the CDI equipment, such as desalination capacity, desalination rate, energy efficiency and operating efficiency. On this basis, the structural parameters of the CDI equipment can be selected according to the parameter indicators of the CDI equipment to obtain the optimal structural parameters, thereby realizing the structural parameter optimization of the CDI equipment, and providing guidance on flow channel design, structural layout and durability for the research and development and optimization stages of CDI. After the finite element software is solved, data post-processing is performed. According to the needs of the research problem, the data that need to be output generally include: the concentration change graph at the outlet of the CDI equipment over time, the ion spatial concentration distribution change graph over time, and if more problems need to be studied, the following data can also be output: double layer current source, porous electrode adsorption ion amount change graph over time, etc. Based on these output results, we can obtain parameter indicators such as desalination capacity, desalination rate, energy efficiency, and operating efficiency of the CDI equipment. According to the above data and indicators, the size design parameters of CDI, such as the length and width of the porous electrode plate, the plate spacing (electrolyte solution flow channel width), the thickness of the porous electrode plate, etc., can be adjusted and optimized; according to the time-varying situation and law of the ion spatial concentration distribution, the most suitable inlet solution flow rate and concentration range of the CDI device can be adjusted and selected. The post-processing and design parameters here refer to a wide range of contents, which can be used in many ways according to the results of finite element output. The above are just examples.

[0069] It should be noted that in order to improve computational efficiency and ensure that the simulation model has a stable performance, appropriate simplification is required in the solution of the multi-physics simulation software, and the built-in calculator of the simulation software should be used as much as possible. Since the material transfer process has little effect on the change of the flow field during the complete desalination and adsorption process of the CDI device, the interference of material transfer can be ignored in fluid simulation. The fluid calculation modules such as the Brinkman equation are used to perform transient or steady-state solutions and calculations on the fluids in the calculation domain of the porous electrode and the electrolyte solution to obtain the velocity field and pressure values. The calculated results are unidirectionally coupled to the physical field responsible for material transfer in the simulation software, so that the convection, diffusion, and electromigration in the mass transfer can be solved and calculated. According to the constructed CDI equivalent circuit and Ohm's law, the value of the boundary potential V applied to the porous electrode is calculated with the help of the ordinary differential equations in the simulation software. Call the modules related to the electric field distribution in the simulation software, input the boundary potential V and the ground zero potential on the corresponding porous electrode, and use the above formula to directly calculate the electrolyte conductivity in the simulation software. , and the electrolyte conductivity Coupled into ordinary differential equations for real-time correction of equivalent circuits; added electrode reactions and double-layer capacitances containing electrode kinetics in porous electrodes and input of charge transfer resistance R ct and the corrected second double layer capacitance C dl By changing the boundary constraints in the simulation software, such as external voltage Vext, electrolyte solution inlet concentration C0, electrolyte solution inlet flow rate V0 and other parameters, and performing another transient solution operation, the simulation of the CDI device under different variable constraints can be realized. Through post-processing, the material adsorption concentration curve, the spatial concentration distribution of ions changing with time, and the current response in the transient operation can be obtained. Parameter results such as the current response in the transient state can be obtained, thereby realizing the simulation prediction of the CDI device and providing guidance on flow channel design, structural layout and durability in the R&D and optimization stages of the CDI device.

[0070] In one embodiment, using Figure 4 The process of the mass transfer kinetics simulation method based on electrosorption desalination shown in the figure is as follows: first, the porous medium material used for the electrode in the CDI device is obtained, and the Nyquist diagram or Bode diagram reflecting the electrochemical reaction process at the interface between the electrode and the electrolyte solution is obtained according to the EIS analysis technology, and a Randles equivalent circuit that can simulate the electrochemical process of the electrode is established. The circuit fitting software is used to extract the following: the first series circuit resistance R s , polarization resistance R L , the first double layer capacitance C dl1Then, according to the actual working conditions of the CDI equipment, a CDI equivalent circuit is constructed that can correct the conductivity parameters of the electrolyte solution in the transient state. Since the environment when the EIS test electrode is different from the environment when the CDI equipment is running, it is necessary to correct the parameters of the constructed CDI equivalent circuit to obtain the corrected second series circuit resistance R s0 , charge transfer resistance R ct , the second double layer capacitance C dl , and use the low concentration electrolyte solution concentration to convert and correct the electrolyte solution resistance R s(c) Finally, the circuit information is decoupled into the finite element software for simulation calculation. After the solution is completed, the data is post-processed, and the optimized design parameters are obtained through analysis. For example, an EIS electrochemical analysis test is performed on a certain electrode material, and the circuit fitting software is used to fit the Figure 2 In the Randles equivalent circuit constructed in , a set of initial equivalent parameters are obtained: the first series circuit resistance R s =381.1Ω, polarization resistance R L =105.3Ω, the first double-layer capacitance C dl1 =41.1F. In order to more reasonably correct the relevant parameters in the CDI equivalent circuit, it is also necessary to pay attention to the test environment in the EIS measurement, including: the conductivity of the electrolyte solution used in the electrochemical experiment, which can be directly measured using a conductivity meter at a lower electrolyte solution concentration, and the surface area of ​​the electrode used in the measurement also needs to be recorded.

[0071] Exemplarily, the result extracted after fitting the Randles circuit of the EIS measurement is corrected and then substituted into the equivalent circuit of the applicable CDI device. Specifically, the second series circuit resistor R s0 The charge transfer resistance R is obtained by subtracting the resistance of the electrolyte solution used in the EIS test from the resistance of the series circuit in the fitted Randles equivalent circuit. ct The polarization resistance R obtained by EIS analysis can be directly used L The resistance R of the electrolyte solution can be replaced by an equivalent value. At the expense of some calculation efficiency, a more complex model with nonlinear characteristics can also be used to describe the resistance value, such as the Butler-Volmer equation and Tafel equation that describe the electrochemical reaction kinetics. s(c) Using the derived theoretical formula The conductivity of the electrolyte solution can be obtained based on the concentration and can be corrected in real time. The first double-layer capacitance C is obtained by EIS analysis. dl1 The value of is linearly corrected according to the surface area. For example, a set of corrected CDI equivalent circuit parameters are obtained: the series circuit resistance R s0 =5.2Ω, polarization resistance RL =105.3Ω, double layer capacitance C dl =41.1F, and the double layer area is set to a=1×10 6 1 / m. Figure 5 The CDI device geometry shown in the figure is used to simulate the CDI device, where the size of the cavity of the CDI device is 100×10×0.68mm, the size of the cathode and anode electrodes is 100×10×0.8mm, and other parameters of the cathode and anode electrodes are set as follows: porosity 0.7, electrode volume fraction 0.85, and electrolyte volume fraction 0.5. It is worth noting that in the calculation process in the finite element software, it is necessary to manually establish a mathematical model for calculating the conductivity of the electrolyte solution. Under the relevant current distribution calculation physical field, the interface of the electrolyte conductivity needs to be selected as "user defined", and the output dependent variable of the relevant material physical field is called to calculate and update the electrolyte conductivity in real time according to the theoretical formula. At the same time, in order to accurately calculate the mass transfer process of "electric field migration", it is necessary to call the potential information under the relevant current distribution calculation physical field to couple to the relevant material physical field to perform mass transfer calculation of ions under the action of the electric field. The electrolyte potential phil is used for calculation in the electrolyte solution calculation domain, and the potential phis is used for calculation in the porous electrode domain. In this case setting, the flow field calculation module of the finite element software is used to output the velocity field and pressure, and the normal inflow velocity V0 is set to 0.42ml / min, and the concentration of the inflowing electrolyte solution C0 is set to 20mol / m 3 . Exemplarily, after the various boundary settings are completed in the simulation software, the solution calculation is performed. For numerical stability, the steady-state operation of the flow field is first performed, and the calculated data set is used as the initial value of the transient operation. The external voltage of the CDI device is set to 0.6V during adsorption and 0V during desorption, and a complete adsorption and desorption operation cycle is solved and calculated. In this case, finite element software is used to calculate the transient calculation for 6000s. In one embodiment, after the finite element software solves, post-processing operations are performed, such as Figure 6The graph shown is the concentration variation over time at the outlet of the CDI device. During the time from 0 to 500 s, the ion concentration at the outlet drops significantly due to the adsorption and desalination effect of the CDI device. During the time from 500 to 3000 s, the ion concentration at the outlet gradually increases due to the gradual weakening of the adsorption effect of the CDI device until it reaches "saturation". It is almost the same as the inlet concentration at around 3000 s, and it can be considered that the adsorption stage of the CDI device has been completed. At 3000 s, the external voltage is set to 0V (i.e. short-circuited) through the transition function, and the CDI device enters the desorption stage. The ion concentration at the outlet increases sharply from 3000 to 3300 s, and the ion concentration at the outlet drops to be almost the same as the inlet concentration from 3300 to 4000 s. The ion concentration at the outlet reaches the same concentration as the inlet concentration in less than 5000 s, and it can be considered that the operation cycle of the CDI device has ended. In one embodiment, Figure 7 The figure shows the ion concentration distribution at the 10th second of the CDI device operation. It can be seen from the figure that since the ions in the electrolyte solution are evenly distributed when the CDI device starts to operate, the concentration difference of the ions in the x-axis direction is not obvious. Since the desalination adsorption capacity is large when the external voltage is first applied, the concentration difference in the z-axis direction is more obvious, and the adsorbed ion concentration is mainly concentrated at the boundary between the electrode domain and the electrolyte solution domain. The adsorption of ions inside the porous electrode is relatively uniform. Figure 8 The figure shows the ion concentration distribution at the 500th second of the CDI equipment operation. The ion concentration at the outlet at this operating moment reached the minimum value of about 4 mol / m 3 ,Due to the obvious effect of desalination adsorption during the time from 0 to 500s, it can be seen from the figure that the concentration distribution in the x-axis direction in the electrolyte solution domain at this moment is uneven, the ion concentration on the inlet side is greater than the concentration distribution on the outlet side, and the ion concentration difference on the z-axis direction is smaller than the distribution result of the 10th second. Fig. 9 The figure shows the ion concentration distribution at the 2000th second when the CDI device is running. The ion concentration at the outlet at this operating moment is close to the ion concentration at the inlet, which can be considered as the end of the adsorption stage in the CDI operation cycle. It can be seen from the figure that in the electrolyte solution domain, the ion concentration on the inlet side and the concentration distribution on the outlet side in the x-axis direction are basically the same. The concentration difference in the z-axis direction near the inlet side is not large, while the concentration difference in the z-axis direction near the outlet side is obvious. In the porous electrode domain, the ion concentration on the inlet side is smaller than the concentration distribution on the outlet side, indicating that the electrode area that mainly plays the role of adsorption and desalination at this moment of the CDI device operation is closer to the outlet side. At the same time, the ion concentration difference in the z-axis direction of the porous electrode domain is further reduced, and the ion distribution inside the porous electrode is more uniform. Fig.10The figure shows the ion concentration distribution at 3300s when the CDI equipment was running. The ion concentration at the outlet reached the maximum value of about 59 mol / m 3 It is worth noting that at this moment, the highest ion concentration in the porous electrode domain is located at one corner between the electrode plates. Fig.11 The figure shows the ion concentration distribution at the 5000s when the CDI equipment is running. The ion concentration at the outlet at this operating moment is close to the ion concentration at the inlet, which can be considered as the end of the desorption stage in the CDI operation cycle. It can be seen from the figure that the concentration distribution difference in the CDI equipment is further reduced, and the ion aggregation area at the 3300s is further expanded.

[0072] In summary, the mass transfer kinetics simulation method for electrosorption desalination in this embodiment uses EIS electrochemical testing technology to obtain relevant electrode processes and electrolyte behaviors, extracts equivalent parameters of equivalent electrochemical reaction processes by establishing Randles equivalent circuits, and then corrects the Randles equivalent parameters in combination with the actual operation of the CDI device and inserts them into equivalent circuits suitable for CDI devices. The constructed equivalent circuit suitable for CDI devices can be suitable for transient simulation operations, and can correct the influence of changes in the resistance of the electrolyte solution on the equivalent circuit in real time, and can well decouple the current and potential information in the circuit, so that the double-layer adsorption-desorption amount and the spatial concentration distribution information of ions that change with time during the simulation process can be well fitted, thereby realizing the simulation prediction of CDI equipment and the parameter indicators of CDI equipment, and can provide guidance on flow channel design, structural layout and durability for the research and development and optimization stages of CDI. Moreover, the method of this embodiment obtains the Nyquist Diagram reflecting the electrochemical reaction process at the interface between the electrode and the electrolyte solution according to the EIS analysis technology, establishes a Randles equivalent circuit that can simulate the electrochemical process of the electrode, and extracts the series circuit resistance R through the circuit fitting software. s , polarization resistance R L , the second double layer capacitance C dl Fitting equivalent parameters. According to the working principle and electrochemical process of the CDI device, a CDI equivalent circuit is constructed that can correct the conductivity parameters of the electrolyte solution in transient calculations, and the electrode inherent property parameters are used to reasonably reflect the electrochemical processes occurring on the surface of the electrode and the electrolyte solution. Since the equivalent principle is based on the inherent properties of the electrode itself in the CDI device, the complete Nernst-Planck equation can be solved in the transient simulation to obtain the spatial concentration distribution of ions that changes with time. At the same time, the resistance changes of the equivalent components in the equivalent circuit during the transient calculation process are not ignored, and the conductivity of the electrolyte solution is corrected in real time, thereby realizing the simulation of the mass transfer kinetics of electrosorption desalination, which can solve the shortcomings and limitations of the prior art mentioned in the background technology.

[0073] In addition, this embodiment also provides a mass transfer kinetics simulation system for electrosorption desalination, comprising a microprocessor and a memory connected to each other, wherein the microprocessor is programmed or configured to execute the mass transfer kinetics simulation method for electrosorption desalination.

[0074] In addition, this embodiment also provides a computer-readable storage medium, in which a computer program or instruction is stored. The computer program or instruction is programmed or configured to execute the mass transfer kinetics simulation method of electrosorption desalination through a processor.

[0075] In addition, this embodiment also provides a computer program product, including a computer program or instructions, which are programmed or configured to execute the mass transfer kinetics simulation method for electrosorption desalination through a processor.

[0076] Those skilled in the art should understand that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application can take the form of a computer program product implemented on one or more computer-readable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the process Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing device to work in a specific way, so that the instructions stored in the computer-readable memory produce a product including an instruction device, which implements the functions specified in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide for implementing the process in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0077] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A mass transfer kinetics simulation method for electrosorption desalination, characterized in that: The steps include: Measuring the impedance of the electrodes of the CDI device at different frequencies; Generate Nyquist diagram or Bode diagram of the electrochemical reaction process of the electrode according to the impedance of the electrode at different frequencies; Establish a Randles equivalent circuit for simulating the electrochemical reaction process of the electrode, and obtain the fitting equivalent parameters of the Randles equivalent circuit according to the impedance data in the Nyquist diagram or Bode diagram; Construct a CDI equivalent circuit for correcting the conductivity parameters of the electrolyte solution in the transient state, and correct and calculate the equivalent circuit parameters of the CDI equivalent circuit by combining the fitted equivalent parameters of the Randles equivalent circuit; Calculate the parameter index of CDI equipment through mass transfer kinetics simulation in simulation software according to CDI equivalent circuit; The equivalent circuit parameters of the CDI equivalent circuit are calculated by correcting the equivalent parameters of the CDI equivalent circuit in combination with the fitted equivalent parameters of the Randles equivalent circuit, including: s The resistance value of the second series circuit is obtained by subtracting the resistance value of the electrolyte solution used to measure the impedance of the electrode at different frequencies. s0 resistance value; when measuring the impedance of the electrode at different frequencies, the polarization resistance R in the Randles equivalent circuit obtained by fitting is used L The value of the charge transfer resistance R ct The value of the first double-layer capacitance C is obtained by dividing the surface area of ​​the electrode used to measure the impedance of the electrode at different frequencies by the preset surface area. dl1 The parameter value is multiplied by the linear correction coefficient to obtain the second double-layer capacitance C dl If the voltage of the power supply is different from the voltage used to measure the impedance of the electrode at different frequencies, the second double-layer capacitance C dl The parameter value is interpolated to the voltage of the power supply according to the voltage; the concentration of the electrolyte solution at each location is arithmetic averaged when measuring the impedance of the electrode at different frequencies to obtain the electrolyte solution concentration c, and then the electrolyte solution concentration c is substituted into the electrolyte solution concentration c and the electrolyte solution resistance R s(c) The electrolyte solution resistance R is obtained by the relationship function s(c) Parameter value of The parameter indicators of the CDI equipment calculated by mass transfer kinetics simulation in the simulation software according to the CDI equivalent circuit include: According to the constructed CDI equivalent circuit and Ohm's law, the boundary potential V applied to the electrode of the CDI device is calculated with the help of ordinary differential equations in the simulation software, and the boundary potential V and ground zero potential are input on the corresponding electrodes by calling the modules related to electric field distribution in the simulation software; In the porous electrode property node of the electrode of the CDI device in the finite element software, set the charge transfer resistance R ct and the second double layer capacitance C dl Parameter value of Calculating the Conductivity of Electrolyte Solutions Using Ordinary Differential Equations in Simulation Software , and the conductivity of the electrolyte solution is Input to the Electrolyte Solution Conductivity node in the Current Distribution module; The electrolyte potential phil is used for coupling calculation in the electrolyte solution calculation domain, and the potential phis is used for coupling calculation in the porous electrode domain of the electrode; The simulation software is used to calculate the flow field of porous media containing electrodes using the Brinkman equation. The Darcy flow calculation principle is used in the porous media to couple the flow field data to the dilute material transfer field calculation. Set the second double-layer capacitance C in the electrode under the current distribution node of the finite element software dl , and set up an electrode reaction coupling to convert the double-layer capacitance current data into ion reaction adsorption flux for statistics, so as to couple the adsorption and desorption of the double layer in the dilute material transfer field with the current distribution calculation field in both directions; Set boundaries and perform solutions in the simulation software: first, perform steady-state operations on the Brinkman equation of the flow field. The solution settings all use the system default "physical field control", and use the steady-state data set that has been solved and calculated as the initial value for the next transient operation; the transient operation needs to include: current distribution physics field, dilute species transfer physics field, ordinary differential equations, and select "full coupling" calculation and solution in the solver configuration, set the external voltage during adsorption and desorption of the CDI device, solve and calculate a complete adsorption and desorption operation cycle, and obtain the solution results, which include part or all of the concentration variation diagram at the outlet of the CDI device over time, the ion spatial concentration distribution variation diagram over time, the double-layer current source, and the porous electrode adsorption ion amount variation diagram over time; The solution result is processed to extract parameter indicators of the CDI device, including part or all of the parameter indicators of the CDI device, such as desalination capacity, desalination rate, energy efficiency and operation efficiency.

2. The mass transfer kinetics simulation method for electrosorption desalination according to claim 1, characterized in that: The Randles equivalent circuit consists of a first series circuit resistor R s , the first parallel circuit and the impedance Warburg are connected in series. The fitting equivalent parameters of the Randles equivalent circuit include the first series circuit resistance R s , polarization resistance R L and the first double layer capacitance C dl1 Parameter value.

3. The mass transfer kinetics simulation method for electrosorption desalination according to claim 1, characterized in that: The fitting equivalent parameters of the Randles equivalent circuit obtained by fitting the impedance data in the Nyquist diagram or the Bode diagram include: fitting the Randles equivalent circuit according to the impedance data in the Nyquist diagram or the Bode diagram, and if the fitting is successful, determining the fitting equivalent parameters of the Randles equivalent circuit; otherwise, re-adjusting the fitting equivalent parameters of the Randles equivalent circuit and fitting the Randles equivalent circuit again according to the impedance data in the Nyquist diagram or the Bode diagram until the fitting is successful.

4. The mass transfer kinetics simulation method for electrosorption desalination according to claim 2, characterized in that: The CDI equivalent circuit is composed of a power supply, a second series circuit resistor R s0 , the second parallel circuit, the electrolyte solution resistance R s(c) and another second parallel circuit connected end to end to form a loop, wherein the second parallel circuit is composed of a charge transfer resistor R ct and the second double layer capacitance C dl The second series circuit resistor R s0 It is used to equalize various fixed resistances or resistances that are not easy to cause fluctuations generated by the circuit wires and interfaces, collectors, and porous media contacts between collectors and electrodes during the operation of CDI equipment, charge transfer resistance R ct Used to equalize the resistance of charge transfer process at the interface between electrode and electrolyte in electrochemical process, double layer capacitance C dl For charge storage characteristics at the interface between equivalent electrodes and electrolytes, the electrolyte solution resistance R s(c) Used to equalize the resistance of the electrolyte solution filled between the electrode plates when the CDI device is running.

5. The mass transfer kinetics simulation method for electrosorption desalination according to claim 4, characterized in that: The second double-layer capacitance C dl The parameter value of is interpolated to the voltage of the power supply according to the voltage, including: calculating the impedance of the measuring electrode at different frequencies respectively under two reference voltages, one high and one low, multiplied by the linear correction coefficient to obtain the second double-layer capacitance C dl The parameter value is then combined with the interpolation calculation formula to calculate the interpolated second double-layer capacitance C under the voltage of the CDI equivalent circuit. dl Parameter value.

6. A mass transfer kinetics simulation system for electrosorption desalination, comprising a microprocessor and a memory connected to each other, characterized in that: The microprocessor is programmed or configured to execute the mass transfer kinetics simulation method for electrosorption desalination according to any one of claims 1 to 5.

7. A computer-readable storage medium having a computer program or instruction stored therein, characterized in that: The computer program or instruction is programmed or configured to execute the mass transfer kinetics simulation method for electrosorption desalination according to any one of claims 1 to 5 through a processor.

8. A computer program product comprising a computer program or instructions, characterized in that The computer program or instruction is programmed or configured to execute the mass transfer kinetics simulation method for electrosorption desalination according to any one of claims 1 to 5 through a processor.

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