CN114595561B - Multi-physical parameter unification and dominance evaluation method for capacitive deionization and desalination process - Google Patents
Multi-physical parameter unification and dominance evaluation method for capacitive deionization and desalination process Download PDFInfo
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Abstract
The invention discloses a method for evaluating the unification and dominance of multiple physical parameters in a capacitive deionization and desalination process, which comprises the following steps: determining multiple physical parameters and control equations of the capacitive deionization process; defining dimensionless variables, and carrying out equation analysis based on a similarity principle to obtain dimensionless numbers; defining the adsorption amount of the salt in the unit area of the dimensionless number to prove the effectiveness of the dimensionless number; determining a dominant factor of the capacitive deionization and desalination performance according to the magnitude of the obtained dimensionless number, and determining an evaluation index of the capacitive deionization and desalination performance; determining the variation level of each dominant factor to design an orthogonal experiment; and calculating the signal-to-noise ratio of each evaluation index and the contribution rate of each influence factor, and performing dominant evaluation on each dominant factor according to the contribution rate. By combining the similar principle and parameter sensitivity analysis, multiple physical parameters of the capacitive deionization process can be effectively unified, and the influence degree of all dominant factors on the capacitive deionization desalination performance can be comprehensively analyzed, so that guidance is provided for improving the capacitive deionization desalination performance.
Description
Technical Field
The invention belongs to the technical field of water treatment desalination, and particularly relates to a multi-physical parameter unification and dominance evaluation method for a capacitive deionization desalination process.
Background
The increasing depletion of fresh water is a major challenge in the socioeconomic development process. Desalination of sea water or brackish water is an effective method to solve the problem of shortage of fresh water. For desalting high-salt-concentration salt water such as seawater, the technology of reverse osmosis, electrodialysis, multistage flash evaporation and the like is widely applied. However, for brackish water desalination, the above-described techniques are energy-intensive and costly. As an alternative, capacitive deionization technology removes small amounts of salt ions directly from the feed water, allows ion selection at low potential and has low energy consumption, and thus capacitive deionization is an important way to efficiently desalinate low-concentration salt water.
Capacitive deionization is an electrochemical reaction process that utilizes charged electrodes to remove salts or charged species from a solution, where ion transport is affected by more than ten physical parameters, such as applied voltage, solution concentration, flow rate, ion species, etc. The current experiments are mostly researched by adopting a controlled variable method, and even if each physical parameter is changed for five times and other parameters are kept unchanged, millions of experiments are needed, so that the experimental burden is greatly increased, and the influence of multiple physical parameters on the deionization performance of the capacitor can not be revealed. In addition, the extent of influence of each physical parameter on capacitive deionization desalination performance is not clear. Therefore, there is a lack of effective theory to guide capacitive deionization experiments, promoting performance improvement.
The above information disclosed in the background section is only for enhancement of understanding of the background of the invention and therefore may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a method for evaluating the unification and dominance of multiple physical parameters in the capacitive deionization and desalination process, which can obtain the unification of physical rules and lighten the experimental burden by obtaining the dimensionless number in the capacitive deionization process by utilizing the similar principle; the dominant sorting of multiple physical parameters which can explicitly influence the capacity deionization and desalination performance can be guided by utilizing the parameter sensitivity analysis.
In order to achieve the above purpose, the present invention provides the following technical solutions:
A multi-physical parameter unification and dominance assessment method for capacitive deionization desalination processes, the method utilizing a similarity principle to conduct equation analysis to unify the multi-physical parameters and utilizing parameter sensitivity analysis to explicitly influence multi-physical parameter dominance ordering of capacitive deionization desalination performance, comprising the steps of:
s1: determining multiple physical parameters and control equations of the capacitive deionization process;
s2: defining a dimensionless variable, substituting the dimensionless variable into the control equation to obtain a dimensionless control equation of the capacitive deionization and desalination process;
S3: analyzing the dimensionless control equation based on a similar principle to obtain dimensionless numbers in the capacitive deionization and desalination process, and classifying the dimensionless numbers to unify the multiple physical parameters;
s4: defining the non-dimensional unit area salt adsorption capacity to represent the salt adsorption performance of the capacitive deionization after the unification of the multiple physical parameters, and comparing the salt adsorption capacity with the non-dimensional unit area salt adsorption capacity before the unification of the multiple physical parameters to confirm the effectiveness of the obtained non-dimensional number;
S5: determining each dominant factor of the capacitive deionization and desalination performance according to the numerical value of the dimensionless number, and determining an evaluation index of the capacitive deionization and desalination performance;
S6: according to the actual physical condition, selecting a parameter change range for each dominant factor as a change level thereof;
s7: performing orthogonal experimental design based on the determined dominant factors and the variation level thereof;
s8: and calculating the signal-to-noise ratio of the determined evaluation index of the capacitive deionization desalination performance and the contribution rate of each dominant factor to perform dominant evaluation on each dominant factor.
Further, in step S1, the multiple physical parameters of the capacitive deionization process include physical parameters, working condition parameters, geometric parameters and basic physical constants, which are specifically as follows:
the physical parameters include: dielectric constant ε, density ρ, diffusion coefficient D i (i=1 represents cation, i=2 represents anion), kinetic viscosity μ, ionic valence z i;
The working condition parameters include: electrode potential Initial concentration C 0, initial velocity u c, temperature T, adsorption equilibrium time T c;
the geometric parameters include: calculating the length L of the area and the average aperture d of the electrode by the electrode;
the basic physical constants include: faraday constant F, general gas constant R.
Further, in step S1, the control equation of the capacitive deionization process includes:
Nernst-pluronic equation:
Poisson equation:
Continuity equation:
The Navie-Stokes equation:
wherein, Is a partial differential operator, C is concentration, t is time, epsilon is dielectric constant,/>Is the potential, F is the Faraday constant, z is the number of valence charges, subscript i is the ith ion, u is the velocity, D is the diffusion coefficient, R is the universal gas constant, T is the temperature, p is the pressure, μ is the viscosity coefficient, ρ is the density.
Further, in step S2, the dimensionless variable is expressed as:
Wherein x and x * represent respectively the dimensional and non-dimensional horizontal coordinates, y and y * represent respectively the dimensional and non-dimensional vertical coordinates, t and t * represent respectively the dimensional and non-dimensional times, C i and C5748 Representing the concentration of ions of dimensionless and dimensionless respectively,/>And/>Representing the dimensional potential in the horizontal and vertical directions,/>, respectivelyAnd/>The dimensionless potential in the horizontal and vertical directions, u * represents the dimensionless speed, and p * represent the dimensionless and dimensionless pressure, respectively.
Further, in step S2, the dimensionless control equation of the capacitive deionization and desalination process includes:
non-dimensionalized nernst-pluronic equations describing cations:
non-dimensionalized nernst-pluronic equations describing anions:
Dimensionless poisson equation:
Dimensionless continuity equation:
Dimensionless Navie-Stokes equation:
wherein, The subscript 1 represents a first ion, namely a cation, and the subscript 2 represents a second ion, namely an anion, C is concentration, t is time, ε is dielectric constant,/>For potential, F is Faraday constant, z is valence charge number, subscript i is ith ion, u is velocity, D is diffusion coefficient, R is universal gas constant, T is temperature, p is pressure, μ is viscosity coefficient, ρ is density, D is average electrode pore size, u c is initial velocity, and L is electrode calculated area length.
Further, in step S3, there are eight dimensionless numbers obtained by analyzing the dimensionless control equation based on the similar principle, and the dimensionless numbers are summarized into four classes, including:
ion adsorption characteristics: Π2＝L/d
Ion transport properties: the number of n 3＝ucL/D1,Π4＝D1/D2 is two,
Ion migration driving force: II 6＝ρuc d/mu,
Ion adsorption equilibration time: II 8＝tcuc/d
Wherein,Characterizing ion removal capacity, n 2 = L/d characterizing electrode calculation area length to average pore size, n 3＝ucL/D1 characterizing ion convection to diffusion ratio, n 4＝D1/D2 characterizing cation diffusion coefficient to anion diffusion coefficient ratio,/>Characterization of the ratio of electromigration to diffusion of ions, pi 6＝ρuc d/mu characterization of the ratio of inertial to viscous forces,/>And (3) representing the ratio of the electric field force to the viscous force, wherein pi 8＝tcuc/d represents the transient adsorption time of ions.
Further, in step S4, the non-dimensional unit area salt adsorption amount is expressed as:
Where u c is the initial velocity, C 0 is the initial concentration, Q is the adsorption amount of salt per unit area with dimension, d 0 is the out-of-plane thickness, and t c is the adsorption equilibrium time.
Further, in step S5, the dominant factors of the capacitive deionization and desalination performance include: initial concentration C0, electrode potentialThe initial speed u c and the cation diffusion coefficient D 1, four variation values are selected for each dominant factor, and four-factor four-level orthogonal experiments are designed.
Further, in step S5, the evaluation indexes of the capacitive deionization and desalination performance include: the adsorption amount of salt per unit area, the average salt removal rate and the removal rate.
Further, in step S8, the expression of the signal-to-noise ratio of the evaluation index of the capacitive deionization desalination performance is:
SNRlb＝-101g(sum(1/Y2)/n)
Wherein Y represents the value of the evaluation index, and n represents the number of repeated experiments;
The average signal-to-noise ratio expression is:
Wherein i represents the dominant factor under study, j represents different levels of the influencing factor, k represents 1 to n, n represents the number of times the influencing factor and level occur in the orthogonal experiment;
the range expression of the average signal to noise ratio under different levels of each evaluation index is as follows:
Ri＝max(SNRavg(i,j))-min(SNRavg(i，j))
Wherein i represents the dominant factor under study and j represents different levels of the influencing factor;
the expression of the contribution rate of each dominant factor is as follows:
Wherein i represents the dominant factor in the study, m represents the number of dominant factors, and R i represents the extremely poor average signal-to-noise ratio at different levels of each evaluation index.
Further, the dominant factors affecting the capacitive deionization and desalination performance are ranked as follows:
for the amount of salt adsorption per unit area and the average salt removal rate: for removal rate: /(I)
According to the method for evaluating the multiple physical parameters of the capacitive deionization and desalination process uniformly and mainly, the capacitive deionization processes with the same dimensionless number have similarity, and uniform ion transportation rules can be obtained by analyzing the single capacitive deionization process, so that capacitive deionization experiments are guided, and the desalination performance of the capacitive deionization experiment is improved while the experimental burden is reduced.
Compared with the prior art, the invention has the beneficial effects that:
According to the invention, equation analysis is performed based on a similar principle to obtain the dimensionless number of the capacitive deionization process, the obtained dimensionless number effectively unifies multiple physical parameters of the capacitive deionization process, and an ion transport mechanism of other similar physical processes can be obtained by analyzing a single physical process, so that a basis can be provided for optimization of the capacitive deionization desalination performance, and experimental arrangement and data arrangement of the capacitive deionization process are guided, and experimental burden is greatly reduced. Based on the parameter sensitivity analysis, the dominant factor sequencing of the adsorption quantity, the average salt removal rate and the removal rate of the salt in the unit area of the capacitive deionization is determined, the influence degree of each influence factor on the capacitive deionization desalination performance is comprehensively analyzed, and theoretical guidance is provided for subsequent experimental research.
Drawings
FIG. 1 is a flow chart of a method for evaluating the uniformity and dominance of multiple physical parameters in a capacitive deionization and desalination process provided by the present invention;
FIG. 2 is a schematic diagram of the adsorption amount of a salt with a dimension unit area and the relative deviation thereof under different working conditions in the capacitive deionization process according to the embodiment of the present invention;
FIG. 3 is a schematic diagram of the non-dimensional unit area salt adsorption capacity and the relative error thereof under different working conditions in the capacitive deionization process according to the embodiment of the present invention.
Detailed Description
Specific embodiments of the present invention will be described in detail below with reference to fig. 1 to 3. While specific embodiments of the invention are shown in the drawings, it should be understood that the invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
It should be noted that certain terms are used throughout the description and claims to refer to particular components. Those of skill in the art will understand that a person may refer to the same component by different names. The specification and claims do not identify differences in terms of components, but rather differences in terms of the functionality of the components. As used throughout the specification and claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. The description hereinafter sets forth a preferred embodiment for practicing the invention, but is not intended to limit the scope of the invention, as the description proceeds with reference to the general principles of the description. The scope of the invention is defined by the appended claims.
For the purpose of facilitating an understanding of the embodiments of the present invention, reference will now be made to the drawings, by way of example, and specific examples of which are illustrated in the accompanying drawings.
In one embodiment, as shown in fig. 1, the present invention provides a method for evaluating the unity and dominance of multiple physical parameters in a capacitive deionization desalination process, wherein the method uses a similar principle to perform equation analysis to unify the multiple physical parameters and uses parameter sensitivity analysis to explicitly influence the dominance ordering of the multiple physical parameters of the capacitive deionization desalination performance, and the method comprises the following steps:
S1: determining a plurality of physical parameters of the capacitive deionization process, the plurality of physical parameters being specifically as follows:
Physical parameters: dielectric constant ε, density ρ, diffusion coefficient D i (i=1 represents cation, i=2 represents anion), kinetic viscosity μ, ionic valence z i; working condition parameters: electrode potential Initial concentration C 0, initial velocity u c, temperature T, adsorption equilibrium time T c; geometric parameters: calculating the length L of the area and the average aperture d of the electrode by the electrode; basic physical constants: faraday constant F, general gas constant R.
The control equation for the determined capacitive deionization process is as follows:
Nernst-pluronic equation:
Poisson equation:
Continuity equation:
The Navie-Stokes equation:
wherein, Is a partial differential operator, C is concentration, t is time, epsilon is dielectric constant,/>Is the potential, F is the Faraday constant, z is the number of valence charges, subscript i is the ith ion, u is the velocity, D is the diffusion coefficient, R is the universal gas constant, T is the temperature, p is the pressure, μ is the viscosity coefficient, ρ is the density.
S2: defining dimensionless variables: Wherein x and x * represent respectively the dimensional and non-dimensional horizontal coordinates, y and y * represent respectively the dimensional and non-dimensional vertical coordinates, t and t * represent respectively the dimensional and non-dimensional times, C i and/> Representing the concentration of ions of dimensionless and dimensionless respectively,/>And/>Representing the dimensional potential in the horizontal and vertical directions,/>, respectivelyAnd/>The dimensionless potential in the horizontal and vertical directions, u * represents the dimensionless speed, and p * represent the dimensionless and dimensionless pressure, respectively.
And (3) bringing the defined dimensionless variable into a control equation to obtain the dimensionless control equation of the capacitive deionization and desalination process, wherein the dimensionless control equation is as follows:
non-dimensionalized nernst-pluronic equations describing cations:
non-dimensionalized nernst-pluronic equations describing anions:
Dimensionless poisson equation:
Dimensionless continuity equation:
Dimensionless Navie-Stokes equation:
wherein, The subscript 1 represents a first ion, namely a cation, and the subscript 2 represents a second ion, namely an anion, C is concentration, t is time, ε is dielectric constant,/>For potential, F is Faraday constant, z is valence charge number, subscript i is ith ion, u is velocity, D is diffusion coefficient, R is universal gas constant, T is temperature, p is pressure, μ is viscosity coefficient, ρ is density, D is average electrode pore size, u c is initial velocity, and L is electrode calculated area length.
S3: analyzing the dimensionless control equation based on a similar principle to obtain dimensionless numbers of eight control capacitance deionization processes, wherein the dimensionless numbers can be summarized into four types:
ion adsorption characteristics: Π2＝L/d
Ion transport properties: the number of n 3＝ucL/D1,Π4＝D1/D2 is two,
Ion migration driving force: II 6＝ρuc d/mu,
Ion adsorption equilibration time: II 8＝tcuc/d
Wherein, the physical meaning of each dimensionless number is as follows: Characterizing ion removal capacity, n 2 = L/d characterizing electrode calculation area length to average pore size, n 3＝ucL/D1 characterizing ion convection to diffusion ratio, n 4＝D1/D2 characterizing cation diffusion coefficient to anion diffusion coefficient ratio,/> Characterization of the ratio of electromigration to diffusion of ions, pi 6＝ρuc d/mu characterization of the ratio of inertial to viscous forces,/>And (3) representing the ratio of the electric field force to the viscous force, wherein pi 8＝tcuc/d represents the transient adsorption time of ions.
S4: definition of the non-dimensional unit area of salt adsorptionThe salt adsorption performance of the capacitor deionized after the unification of the multiple physical parameters is characterized, and the salt adsorption capacity is compared with the salt adsorption capacity Q with the dimension unit area before the unification of the multiple physical parameters so as to confirm the effectiveness of the obtained dimensionless number;
The working conditions of different combinations of nine dimensionless parameters and consistent dimensionless numbers are selected in table 1, and the dimensionless and dimensionless unit area salt adsorption amounts are compared to prove the validity of the dimensionless numbers. Table 1 shows the specific values of the parameters of the working condition 1 and the change times of the parameters of the working conditions 2 to 9 based on the working condition 1.
TABLE 1 dimensionless number validity verification parameter Condition
After adsorption balance, the salt adsorption capacity per unit area in different working conditions is shown in figure 2, and the salt adsorption capacity per unit area in the nine working conditions is inconsistent, wherein the relative deviation between the working condition 4 and the working condition 1 is maximum and can reach 100%. As shown in FIG. 3, the salt adsorption capacity of the dimensionless unit area of nine working conditions is kept consistent, and the relative error is only between-0.3% and 0.04%. As can be seen by comparing fig. 2 and fig. 3, the capacitive deionization processes with the same dimensionless number have similarity, and the dimensionless unit area salt adsorption amounts are equal. The obtained dimensionless numbers can effectively unify similar physical processes in capacitive deionization so as to realize unification of multiple physical parameters, for example, for working condition 1 and working condition 2 of any different physical parameter combination, when the dimensionless numbers are kept consistent, the following are:
when the dimensionless numbers are the same, a unified ion transport rule can be obtained by analyzing a single capacitive deionization process, so that a capacitive deionization experiment is guided, and the desalting performance of the capacitive deionization experiment is improved while the experimental burden is reduced.
S5: determining each dominant factor of the capacity deionization desalination performance according to the magnitude of the dimensionless number, table 2 is a specific value of each dimensionless number, wherein, due to the u cL/D1、ρuc d/mu sumThe absolute value of (2) is smaller and can be ignored, and according to the actual physical condition, the initial concentration C 0 and electrode potential/>, among the physical parameters related to the residual dimensionless number, are selectedInitial velocity u c and cation diffusion coefficient D 1 are four dominant factors for parameter sensitivity analysis; the amount of adsorption of salt per unit area, the average salt removal rate and the removal rate were determined as three indicators for evaluating the capacity deionization and desalination performance.
Table 2 specific values of eight dimensionless numbers in operating conditions 1-9
S6: according to the actual physical condition, each dominant factor respectively selects four variation values as variation levels of each dominant factor, as shown in the following table:
TABLE 3 level of variation of capacitive deionization from dominant factors
S7: based on the determined dominant factors and the variation levels of the dominant factors in table 3, four-factor four-level orthogonal experiments were designed as shown in the following table:
TABLE 4 orthogonal experiment table
S8: and calculating the determined signal-to-noise ratio of each evaluation index and the contribution rate of each dominant factor, and performing dominant evaluation on each dominant factor according to the contribution rate.
In the step, the expression of the signal to noise ratio of the evaluation index of the capacitive deionization desalination performance is:
SNRlb＝-10lg(sum(1/Y2)/n)
Wherein Y represents the value of the evaluation index, and n represents the number of repeated experiments;
The average signal-to-noise ratio expression is:
Wherein i represents the dominant factor under study, j represents different levels of the influencing factor, k represents 1 to n, n represents the number of times the influencing factor and level occur in the orthogonal experiment;
the range expression of the average signal to noise ratio under different levels of each evaluation index is as follows:
Ri＝max(SNRavg(i,j))-min(SNRavg(i，j))
Wherein i represents the dominant factor under study and j represents different levels of the influencing factor;
the expression of the contribution rate of each dominant factor is as follows:
Wherein i represents the dominant factor in the study, m represents the number of dominant factors, and R i represents the extremely poor average signal-to-noise ratio at different levels of each evaluation index.
The contribution rates of each dominant factor to the three evaluation indexes are specifically shown in table 5:
TABLE 5 contribution rate of each dominant factor to capacitive deionization and desalination performance
From table 5, it can be obtained: for the adsorption amount of salt per unit area and the average salt removal rate, the contribution rates of the dominant factors are ranked as follows: for the removal rate, the contribution rates of the dominant factors are ordered as:
according to the invention, the dimensionless number obtained by equation analysis based on a similar principle effectively unifies multiple physical parameters in the capacitive deionization process, and realizes unified cognition of an ion transport mechanism in the capacitive deionization process. The parameter sensitivity analysis defines the dominant factor ordering of the capacitive deionization desalination performance. Therefore, the method for evaluating the uniformity and the dominance of the multiple physical parameters in the capacitive deionization and desalination process can effectively guide the experimental arrangement and the data arrangement of the capacitive deionization process, greatly lighten the experimental burden and improve the desalination performance.
The basic principles of the present application have been described above in connection with specific embodiments, but it should be noted that the advantages, benefits, effects, etc. mentioned in the present application are merely examples and not intended to be limiting, and these advantages, benefits, effects, etc. are not to be construed as necessarily possessed by the various embodiments of the application. Furthermore, the specific details disclosed herein are for purposes of illustration and understanding only, and are not intended to be limiting, as the application is not necessarily limited to practice with the above described specific details.
Claims (6)
1. A multi-physical parameter unification and dominance assessment method for capacitive deionization desalination processes, the method utilizing a similarity principle to conduct equation analysis to unify the multi-physical parameters and utilizing parameter sensitivity analysis to explicitly influence multi-physical parameter dominance ordering of capacitive deionization desalination performance, comprising the steps of:
s1: determining multiple physical parameters and control equations of the capacitive deionization process,
The multi-physical parameters comprise physical parameters, working condition parameters, geometric parameters and basic physical constants;
The control equation includes:
Nernst-pluronic equation:
Poisson equation:
Continuity equation:
The Navie-Stokes equation:
wherein, Is a partial differential operator, C is concentration, T is time, epsilon is dielectric constant, phi is potential, F is Faraday constant, z is valence charge number, subscript i is ith ion, u is speed, D is diffusion coefficient, R is general gas constant, T is temperature, p is pressure, mu is viscosity coefficient, and rho is density;
s2: defining dimensionless variables, substituting the dimensionless variables into the control equation to obtain a dimensionless control equation of the capacitive deionization and desalination process,
The dimensionless variable is expressed as:
Wherein x and x * represent respectively the dimensional and non-dimensional horizontal coordinates, y and y * represent respectively the dimensional and non-dimensional vertical coordinates, t and t * represent respectively the dimensional and non-dimensional times, C i and C5748 Represents the ion concentration in the dimension and the non-dimension respectively, phi x and phi y represent the dimension potential in the horizontal and vertical directions respectively,/>And/>The non-dimensional potentials in the horizontal and vertical directions are represented, u * represents a non-dimensional velocity, and p * represent a dimensional and a non-dimensional pressure, respectively;
the dimensionless control equation of the capacitive deionization and desalination process comprises:
non-dimensionalized nernst-pluronic equations describing cations:
non-dimensionalized nernst-pluronic equations describing anions:
Dimensionless poisson equation:
Dimensionless continuity equation:
Dimensionless Navie-Stokes equation:
wherein, The subscript 1 represents a first ion, namely a cation, the subscript 2 represents a second ion, namely an anion, the concentration is C, the time is T, the dielectric constant is epsilon, phi is a potential, F is Faraday constant, z is the number of valence charges, the subscript i is the ith ion, u is a speed, D is a diffusion coefficient, R is a universal gas constant, T is a temperature, p is a pressure, mu is a viscosity coefficient, ρ is a density, D is an electrode average pore diameter, u c is an initial speed, and L is an electrode calculation region length;
S3: analyzing the dimensionless control equation based on a similar principle to obtain dimensionless numbers of the capacitive deionization and desalination process, classifying the dimensionless numbers to unify the multiple physical parameters,
The dimensionless number includes:
ion adsorption characteristics:
Ion transport properties:
Ion migration driving force:
ion adsorption equilibration time:
wherein, Characterizing ion removal capacity, ε is dielectric constant, φ e is electrode potential, d is average pore diameter, C 0 is initial concentration, and F is Faraday constant; /(I)Characterizing the ratio of the electrode calculation region length L to the average pore diameter d; /(I)Characterizing the ratio of ion convection to diffusion, u c is the initial velocity, L is the electrode calculation region length, D 1 is the cation diffusion coefficient D 1; /(I)Characterizing the ratio of the cation diffusion coefficient D 1 to the anion diffusion coefficient D 2; Characterizing the ratio of electromigration to diffusion of ions, Z i is the valence charge number of the ith ion, F is Faraday constant, phi e is electrode potential, R is universal gas constant, and T is temperature; /(I) Characterizing the ratio of inertial force to viscous force, ρ being the density, u c being the initial velocity, d being the average pore size, u being the velocity; /(I)Characterization of the ratio of electric field force to viscous force, F being Faraday constant, phi e being electrode potential, C 0 being initial concentration, d being average pore diameter, u being velocity, u c being initial velocity; /(I)Representing ion transient adsorption time, wherein t c is adsorption equilibrium time, u c is initial speed, and d is average pore diameter;
s4: defining the non-dimensional unit area salt adsorption capacity to represent the salt adsorption performance of the capacitive deionization after the unification of the multiple physical parameters, and comparing the salt adsorption capacity with the non-dimensional unit area salt adsorption capacity before the unification of the multiple physical parameters to confirm the effectiveness of the obtained non-dimensional number;
S5: determining each dominant factor of the capacitive deionization and desalination performance according to the numerical value of the dimensionless number, and determining an evaluation index of the capacitive deionization and desalination performance;
S6: according to the actual physical condition, selecting a parameter change range for each dominant factor as a change level thereof;
s7: performing orthogonal experimental design based on the determined dominant factors and the variation level thereof;
s8: and calculating the signal-to-noise ratio of the determined evaluation index of the capacitive deionization desalination performance and the contribution rate of each dominant factor to perform dominant evaluation on each dominant factor.
2. The method for uniform and dominant evaluation of multiple physical parameters for capacitive deionization and desalination process of claim 1 wherein, in step S1,
The physical parameters include: dielectric constant epsilon, density rho, diffusion coefficient D i, dynamic viscosity mu, ionic electricity valence z i;
The working condition parameters include: electrode potential phi e, initial concentration C 0, initial velocity u c, temperature T, adsorption equilibrium time T c;
the geometric parameters include: calculating the length L of the area and the average aperture d of the electrode by the electrode;
the basic physical constants include: faraday constant F, general gas constant R.
3. The method for evaluating the unity and dominance of multiple physical parameters of a capacitive deionization and desalination process according to claim 1, wherein in step S4, the non-dimensional unit area salt adsorption amount is expressed as:
Where u c is the initial velocity, C 0 is the initial concentration, Q is the amount of salt adsorbed per unit area with dimensions, d 0 is the out-of-plane thickness, t c is the adsorption equilibrium time, and L is the electrode calculation area length.
4. The method for evaluating the uniformity and dominance of multiple physical parameters of a capacitive deionization and desalination process according to claim 1, wherein in step S5, the dominant factors of the capacitive deionization and desalination performance comprise: the initial concentration C 0, the electrode potential phi e, the initial speed u c and the cation diffusion coefficient D 1 are respectively selected from four variation values for each dominant factor, and four-factor four-level orthogonal experiments are designed.
5. The method for evaluating the uniformity and dominance of multiple physical parameters in a capacitive deionization and desalination process according to claim 1, wherein in step S5, the evaluation index of the capacitive deionization and desalination performance comprises: the adsorption amount of salt per unit area, the average salt removal rate and the removal rate.
6. The method for evaluating the uniformity and dominance of multiple physical parameters in a capacitive deionization and desalination process according to claim 1, wherein in step S8, the expression of the signal-to-noise ratio of the evaluation index of the capacitive deionization and desalination performance is:
Wherein Y represents the value of the evaluation index, and n represents the number of repeated experiments;
The average signal-to-noise ratio expression is:
Wherein i represents the dominant factor under study, j represents different levels of the influencing factor, k represents 1 to n, n represents the number of times the influencing factor and level occur in the orthogonal experiment;
the range expression of the average signal to noise ratio under different levels of each evaluation index is as follows:
Wherein i represents the dominant factor under study and j represents different levels of the influencing factor;
the expression of the contribution rate of each dominant factor is as follows:
Wherein i represents the dominant factor in the study, m represents the number of dominant factors, and R i represents the extremely poor average signal-to-noise ratio at different levels of each evaluation index.
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