Thermal Regulation Penetration Energy Conversion Analysis Method for a Salinity Gradient Power Generation Device

Abstract

The present disclosure discloses a method for analyzing the thermoregulated osmotic energy conversion of a salinity gradient power generation device, including: describing the physical and mathematical characteristics of the thermoregulated osmotic energy conversion of the salinity gradient power generation device, where the physical and mathematical characteristics include physical fields, governing equations, physical parameters, and output performance; performing similarity analysis on the governing equations using the similarity principle to obtain a dimensionless control parameter group π i ; performing dimensional analysis on the physical parameters using the Pi theorem to obtain a dimensionless control parameter group Π i ; analyzing the dimensionless control parameter group π i and the dimensionless control parameter group Π i to determine the dimensionless numbers of the thermoregulated osmotic energy conversion in the nanochannels of the salinity gradient power generation device and clarify the relationship between the two dimensionless control parameter groups; analyzing the output performance through the similarity principle to define dimensionless physical quantities, so as to unify multiple groups of experimental samples into one dimensionless sample, or expand one group of dimensionless samples into multiple groups of different experimental samples.

Description

Technical Field

[0001] The present disclosure belongs to the technical field of new energy, and particularly relates to an analysis method for thermoregulated osmotic energy conversion of a salinity gradient power generation device. Background Art

[0002] Osmotic energy conversion in nanochannels uses the salinity difference of electrolyte solutions as the driving force to drive the selective directional migration of ion carriers through the nanochannels to form an ion flux, directly converting salinity energy into electrical energy. This energy conversion method can provide a new way for the efficient utilization of low-grade salinity energy. The surface of the nanochannels is charged to form an electric double layer. When the electrolyte flows through the nanochannels, the presence of the electric double layer affects the ion distribution. Due to the extremely small size of the nanochannels, the overlapping effect of the electric double layer formed on the surface exhibits ion selectivity. Due to the ion selectivity of the nanochannels, the mixing Gibbs free energy between salt solutions of different concentrations is converted in the form of the potential difference across the nanochannels.

[0003] To improve the power generation effect of osmotic energy conversion in nanochannels, thermoregulation is the most common means. Uniformly increasing the overall operating temperature of osmotic energy conversion affects physical property parameters such as the ion diffusion coefficient and dielectric constant, thereby affecting the power generation effect. Non-uniformly increasing the operating temperature of osmotic energy conversion, such as having a temperature difference at both ends, on the one hand affects the physical property parameters, and on the other hand, the temperature difference can also serve as a part of the driving force for ion migration. Generally speaking, whether uniformly or non-uniformly increasing the operating temperature of osmotic energy conversion, the power generation system exhibits better performance.

[0004] In experimental research, there is a lack of a unified understanding of the physical process of thermoregulated osmotic energy conversion in nanochannels, and there is no unified standard for the power generation effect of thermoregulated osmotic energy conversion in nanochannels. A large number of samples are required to obtain the I-V curve of the power generation system or calculate the maximum output power, which will incur extremely high economic and time costs. Summary of the Invention

[0005] Aiming at the deficiencies in the prior art, the purpose of the present disclosure is to provide an analysis method for thermoregulated osmotic energy conversion of a salinity gradient power generation device. Through similarity principle analysis, this method obtains a dimensionless control parameter group for thermoregulated osmotic energy conversion. This parameter group covers the physical laws of non-uniform thermoregulation, uniform thermoregulation, and non-thermoregulated osmotic energy conversion in nanochannels, thus being able to provide universal guidance for the osmotic energy conversion of nanochannels.

[0006] To achieve the above purpose, the present disclosure provides the following technical solutions:

[0007] An analysis method for thermoregulated osmotic energy conversion of a salinity gradient power generation device, comprising the following steps:

[0008] S100: Describe the physical and mathematical characteristics of the thermal regulation osmotic energy conversion of the salinity gradient power generation device, where the physical and mathematical characteristics include physical fields, governing equations, physical parameters, and output performance;

[0009] S200: Use the similarity principle to conduct a similarity analysis on the governing equations to obtain a dimensionless control parameter group π for characterizing the non-uniform thermal regulation, uniform thermal regulation, and non-thermal regulation osmotic energy conversion of the salinity gradient power generation device i ;

[0010] S300: Use the Pi theorem to conduct a dimensional analysis on the physical parameters to obtain a dimensionless control parameter group Π i ;

[0011] S400: Analyze the dimensionless control parameter group π i and the dimensionless control parameter group Π i to determine the dimensionless number of the thermal regulation osmotic energy conversion in the nanochannels of the salinity gradient power generation device, and clarify the relationship between the dimensionless control parameter group π i and the dimensionless control parameter group ∏ i ;

[0012] S500: Analyze the output performance through the similarity principle to define the dimensionless electric potential and dimensionless current, so as to unify multiple groups of experimental samples into one dimensionless sample, or expand one group of dimensionless samples into multiple groups of different experimental samples.

[0013] Preferably, in step S100, the physical fields include a concentration field, an electric potential field, a velocity field, and a temperature field, and there is a coupling effect between the concentration field, the electric potential field, the velocity field, and the temperature field.

[0014] Preferably, in step S100, the governing equations include:

[0015] Poisson equation:

[0016] Flux continuity equation:

[0017] Nernst - Planck equation:

[0018] Velocity continuity equation:

[0019] Navier - Stokes equation:

[0020] Energy equation:

[0021] Nanochannel boundary equation:

[0022] Among them, is the partial differential operator, ε is the dielectric constant, φ is the electric potential, F is the Faraday constant, c is the concentration, z is the valence charge number, i is the i-th ion, n is the total number of ion species, J is the ion flux, u is the velocity, D is the diffusion coefficient, R is the universal gas constant, T is the temperature, S T is the Soret coefficient, p is the pressure, μ is the viscosity coefficient, E is the electric field strength, ρ is the density, C p is the specific heat, λ is the thermal conductivity, σ f is the electrical conductivity, and σ is the surface charge density.

[0023] Preferably, in step S100, the physical parameters include: working fluid parameters, channel parameters, operating conditions parameters, and constants. Among them,

[0024] The working fluid parameters include: dielectric constant ε, diffusion coefficient D, Soret coefficient S T , viscosity coefficient μ, thermal diffusivity α, thermal conductivity λ, electrical conductivity σ f ;

[0025] The channel parameters include: characteristic length l, surface charge density σ;

[0026] The operating conditions parameters include: electric potential φ, concentration c, velocity u, temperature T, pressure p;

[0027] The constants include: Faraday constant F, universal gas constant R.

[0028] Preferably, in step S100, the output performance includes: I-V curve, diffusion potential, permeation current, and output power.

[0029] Preferably, in step S200, the dimensionless control parameter group π i includes:

[0030] π5 = TS T ,

[0031] Among them, characterizes the relative magnitude of the amount of electricity collected by the spatial electric potential in the nanochannel and the amount of spatial electric charge; characterizes the electrical relative magnitude of the amount of electricity collected by the surface electric potential of the nanochannel and the amount of electricity collected by the surface charge density; characterizes the relative strength of ion convection and ion diffusion; characterizes the relative strength of ion electromigration and ion diffusion; π5 = TS T characterizes the relative strength of ion thermomigration and ion diffusion; characterizes the relative magnitude of pressure and viscous force; Characterize the relative magnitudes of the electrostatic force and the viscous force; Characterize the relative strengths of heat convection and heat diffusion; Characterize the relative magnitudes of Joule heat and heat diffusion.

[0032] Preferably, in step S300, the dimensionless control parameter group Π i includes:

[0033] ∏5 = TS T 、

[0034] Preferably, in step S400, the dimensionless control parameter group π i and the dimensionless control parameter group Π i after conversion are expressed as:

[0035] π2 = ∏1, π5 = ∏5, π9 = ∏9;

[0036] Or it can also be expressed as:

[0037] ∏1 = π2, ∏5 = π5, ∏9 = π9.

[0038] Preferably, in step S500,

[0039] the dimensionless electric potential is defined as:

[0040]

[0041] the dimensionless current is defined as:

[0042]

[0043] where φ * is the dimensionless electric potential, I * is the dimensionless current, L is the length of the nanochannel, R is the radius of the nanochannel, φ is the electric potential, σ is the charge density, ε is the dielectric constant, I is the current, F is the Faraday constant, c is the concentration, R is the universal gas constant, and D is the diffusion coefficient.

[0044] Preferably, in step S500, it is also necessary to perform normalization processing on the defined dimensionless electric potential and dimensionless current to obtain the normalized dimensionless electric potential and the normalized dimensionless current;

[0045] The normalized dimensionless electric potential is expressed as:

[0046]

[0047] The normalized dimensionless current is expressed as:

[0048]

[0049] Wherein, is the normalized dimensionless electric potential, is the normalized dimensionless current, φ * is the dimensionless electric potential, I * is the dimensionless current, φ0 * is the dimensionless diffusion electric potential, I0 * is the dimensionless osmotic current.

[0050] Compared with the prior art, the beneficial effects brought by the present disclosure are as follows:

[0051] 1. By means of the similarity principle analysis method, a dimensionless control parameter group for thermally regulated osmotic energy conversion is obtained, the physical meanings of each dimensionless control parameter are clarified, and the equations and parameters of the concentration field, electric potential field, velocity field, and temperature field are unified.

[0052] 2. By ensuring that the dimensionless control parameters remain unchanged, multiple groups of different samples can be unified into a group of dimensionless samples under the guidance of the similarity principle to explain the inherently unified physical laws; or a group of dimensionless samples can be expanded into multiple groups of different samples to conduct modeling experiments on thermally regulated osmotic energy conversion in nanochannels.

[0053] 3. The obtained dimensionless control parameter group covers the physical laws of non-uniform thermal regulation, uniform thermal regulation, and non-thermal regulation osmotic energy conversion in nanochannels. The dimensionless control parameter group can be simplified according to the actual situation to match the corresponding physical process, which has universal guiding value for the osmotic energy conversion of nanochannels. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 is a flowchart of an analysis method for thermally regulated osmotic energy conversion of a salinity gradient power generation device provided by an embodiment of the present disclosure;

[0055] Figure 2 is a schematic diagram of a dimensional I-V curve of a similarity experiment for thermally regulated osmotic energy conversion provided by another embodiment of the present disclosure;

[0056] Figure 3 is a schematic diagram of a dimensionless normalized I-V curve of a similarity experiment for thermally regulated osmotic energy conversion provided by another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0057] The following will refer to the attached Figures 1 to 3Specific embodiments of the present disclosure are described in detail. Although specific embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art.

[0058] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different terms to refer to the same component. The specification and claims do not distinguish components by the difference in terms, but by the difference in functions of the components. As used throughout the specification and claims, the term "comprising" or "including" is an open-ended term and should be interpreted as "including but not limited to". The following description of the embodiments of the present disclosure is for the purpose of general principles of the specification and is not intended to limit the scope of the present disclosure. The scope of protection of the present disclosure shall be determined by the claims appended hereto.

[0059] For the convenience of understanding the embodiments of the present disclosure, the following will further explain with specific embodiments as examples in conjunction with the drawings, and each drawing does not constitute a limitation on the embodiments of the present disclosure.

[0060] In one embodiment, as Figure 1 shown, the present disclosure provides a method for analyzing the thermoregulated osmotic energy conversion of a salinity gradient power generation device, including the following steps:

[0061] S100: Describe the physical and mathematical characteristics of the thermoregulated osmotic energy conversion of the salinity gradient power generation device, where the physical and mathematical characteristics include physical fields, governing equations, physical parameters, and output performance;

[0062] S200: Perform similarity analysis on the governing equations using the similarity principle to obtain a dimensionless control parameter group π for characterizing the non-uniform thermoregulation, uniform thermoregulation, and non-thermoregulated osmotic energy conversion of the salinity gradient power generation device i ;

[0063] S300: Perform dimensional analysis on the physical parameters using the Pi theorem to obtain a dimensionless control parameter group Π i ;

[0064] S400: Analyze the dimensionless control parameter group π i and the dimensionless control parameter group Π i to determine the dimensionless number of thermoregulated osmotic energy conversion in the nanochannels of the salinity gradient power generation device and clarify the relationship between the dimensionless control parameter group π i and the dimensionless control parameter group П i ;

[0065] S500: Analyze the output performance through the similarity principle to define dimensionless electric potential and dimensionless current, so as to unify multiple groups of experimental samples into a dimensionless sample, or expand a group of dimensionless samples into multiple groups of different experimental samples.

[0066] The above embodiments constitute the complete technical solution of the present disclosure. The dimensionless parameter group obtained through similarity principle analysis covers the physical laws of non-uniform heat regulation, uniform heat regulation, and heat-free regulation osmotic energy conversion in the nanochannel. The dimensionless control parameter group can be simplified according to the actual situation to match the corresponding physical process. Guided by the similarity principle, the modeling experiment of heat-regulated osmotic energy conversion in the nanochannel ensures that the dimensionless control parameters remain unchanged through different parameter combinations. Physically, multiple groups of experimental samples can be unified into a dimensionless sample, and in engineering applications, a group of dimensionless samples can be expanded into multiple groups of different experimental samples under the guidance of the similarity principle.

[0067] In another embodiment, in step S100, the physical fields include a concentration field, an electric potential field, a velocity field, and a temperature field, and there is a coupling effect between the concentration field, the electric potential field, the velocity field, and the temperature field.

[0068] In another embodiment, in step S100, the control equations include:

[0069] Poisson's equation:

[0070] Flux continuity equation:

[0071] Nernst-Planck equation:

[0072] Velocity continuity equation:

[0073] Navier-Stokes equation:

[0074] Energy equation:

[0075] Nanochannel boundary equation:

[0076] Where is the partial differential operator, ε is the dielectric constant, φ is the electric potential, F is the Faraday constant, c is the concentration, z is the valence charge number, the subscript i is the i-th ion, the superscript n is the total number of ion species, J is the ion flux, u is the velocity, D is the diffusion coefficient, R is the universal gas constant, T is the temperature, S T is the Soret coefficient, p is the pressure, μ is the viscosity coefficient, E is the electric field strength, ρ is the density, Cp where \(C\) is the specific heat, \(\lambda\) is the thermal conductivity, \(\sigma\) f is the electrical conductivity, and \(\sigma\) is the surface charge density.

[0077] In another embodiment, in step S100, the physical parameters include: working fluid parameters, channel parameters, operating conditions parameters, and constants, where

[0078] the working fluid parameters include: dielectric constant \(\varepsilon\), diffusion coefficient \(D\), Soret coefficient \(S\) T , viscosity coefficient \(\mu\), thermal diffusivity \(\alpha(\alpha=\lambda / \rho C\) p ), thermal conductivity \(\lambda\), electrical conductivity \(\sigma\) f ;

[0079] the channel parameters include: characteristic length \(l\), surface charge density \(\sigma\);

[0080] the operating conditions parameters include: electric potential \(\varphi\), concentration \(c\), velocity \(u\), temperature \(T\), pressure \(p\);

[0081] the constants include: Faraday constant \(F\), universal gas constant \(R\).

[0082] In another embodiment, in step S100, the output performance includes: I-V curve, diffusion potential, permeation current, and output power.

[0083] In another embodiment, in step S200, the dimensionless control parameter group \(\pi\) i includes:

[0084] \(\pi_5 = TS\) T ,

[0085] where characterizes the relative magnitude of the collected charge of the spatial electric potential in the nanochannel and the spatial charge quantity; characterizes the electrical relative magnitude of the collected charge of the surface electric potential in the nanochannel and the collected charge quantity of the surface charge density; characterizes the relative strength of ion convection and ion diffusion; characterizes the relative strength of ion electromigration and ion diffusion; \(\pi_5 = TS\) T characterizes the relative strength of ion thermomigration and ion diffusion; characterizes the relative magnitude of pressure and viscous force; characterizes the relative magnitude of electrostatic force and viscous force; characterizes the relative strength of heat convection and heat diffusion; characterizes the relative magnitude of Joule heat and heat diffusion.

[0086] In this embodiment, taking the Poisson equation as an example, the process of dimensional analysis using the similarity principle is as follows:

[0087] Suppose there are operating condition 1 and operating condition 2, where

[0088] Operating condition 1:

[0089] Operating condition 2:

[0090] To satisfy the similarity between operating condition 1 and operating condition 2, the equation is further transformed:

[0091] Operating condition 1:

[0092] Operating condition 2:

[0093] In the above formula, l is the characteristic length. Then, if is ensured, the physical fields of the Poisson equation under different operating conditions can be ensured to be consistent. Therefore is the dimensionless control parameter of the Poisson equation.

[0094] In another embodiment, the dimensionless control parameter group П i includes:

[0095] ∏5 = TS T 、

[0096] In this embodiment, the physical parameters have 6 basic dimensions, including M, L, T, N, I, Θ. Using the {MLTNIΘ} dimension system, the dimensions of each parameter are as follows:

[0097] Working fluid parameters: ε{M -1 L -3 T 4 I 2}, D{L 2 T 1}, S T {Θ -1}, μ{ML -1 T 1}, α{L 2 T 1}, σ f / λ{M 2 L -4 T 6 I 2 Θ}

[0098] Operating condition parameters: φ{ML 2 T 3 I -1}, c{L -3 N}, u{LT-1}, T{Θ}, p{ML -1 T -2}

[0099] Channel parameters: l{L}, σ{L -2 TI}

[0100] Constant: F{TN -1 I}, R{ML 2 T 2 N -1 Θ -1}

[0101] To simplify the number of parameters, the thermal conductivity λ, density ρ, and specific heat capacity C in the energy equation p are combined to form the combined parameter thermal diffusivity α, and the thermal conductivity λ and electrical conductivity are combined to form σ f / λ. Select φ, F, l, σ, u, T as the basic dimension groups, and use the basic dimension groups to perform power multiplication and division combinations with the remaining parameters one by one to form the Pi groups. The dimensions of the Pi groups are all 1, and the Pi groups are the dimensionless control parameter groups.

[0102] In another embodiment, in step S400, the dimensionless control parameter group π i and the dimensionless control parameter group Π i After conversion, it is expressed as:

[0103] π5 = ∏5, π9 = ∏9;

[0104] Or it can also be expressed as:

[0105] ∏1 = π2, ∏5 = π5, ∏9 = π9.

[0106] In another embodiment, in step S500,

[0107] The dimensionless electric potential is defined as:

[0108]

[0109] The dimensionless current is defined as:

[0110]

[0111] Among them, φ * is the dimensionless electric potential, I *is the dimensionless current, L is the length of the nanochannel, R is the radius of the nanochannel, φ is the electric potential, σ is the charge density, ε is the dielectric constant, I is the current, F is the Faraday constant, c is the concentration, R is the universal gas constant, and D is the diffusion coefficient.

[0112] Furthermore, the dimensionless electric potential and the dimensionless current are normalized. The normalized dimensionless electric potential is expressed as:

[0113]

[0114] The normalized dimensionless current is expressed as:

[0115]

[0116] where is the normalized dimensionless electric potential, is the normalized dimensionless current, φ * is the dimensionless electric potential, I * is the dimensionless current, φ0 * is the dimensionless diffusion potential, I0 * is the dimensionless osmotic current.

[0117] For the I-V curves under different working conditions, they are normalized with the dimensionless diffusion potential and the dimensionless osmotic current. The working conditions with the overlapping dimensionless normalized I-V curves indicate that they have the same physical laws and the same dimensionless control parameter sets.

[0118] Figure 2 is the schematic diagram of the dimensional I-V curve of the similarity experiment of thermally regulated osmotic energy conversion; Figure 3 is the schematic diagram of the dimensionless normalized I-V curve of the similarity experiment of thermally regulated osmotic energy conversion. For a known dimensional working condition, through the above definitions of the dimensionless electric potential and current, the dimensionless form of this working condition can be obtained. For other parameter combinations with the same values of the dimensionless control parameter sets, their dimensionless forms are the same as those of the known working condition. That is Figure 3 The dimensionless I-V curve of a working condition reflects the dimensionless I-V curves of these working conditions. Using the inverse process of the definition of the dimensionless numbers,

[0119]

[0120]

[0121] Substituting different dimensional parameters, the dimensional electric potential and current of these working conditions can be obtained, and then Figure 2 the dimensional I-V curve is obtained, achieving the purpose of expanding the sample. Comparing Figure 2 and Figure 3, when different parameter combinations are selected to keep the values of the dimensionless control parameter group unchanged, Figure 2 the dimensional I-V curves of each working condition are very different, while Figure 3 the dimensionless normalized I-V curves are completely coincident. Thus, it can be seen that the dimensionless control parameter group of the similarity principle reveals the internal law between the dimensional physical field parameters. When keeping it unchanged, one dimensionless working condition can be expanded into multiple working conditions, thus greatly reducing the experimental cost.

[0122] In one embodiment, to study the physical laws of non-uniform thermal regulation, uniform thermal regulation, and non-thermal regulation osmotic energy conversion of a salinity gradient power generation device, the dimensionless control parameter group is analyzed.

[0123] The physical phenomenon of non-uniform thermal regulation osmotic energy conversion can directly apply the above dimensionless control parameter group.

[0124] The physical phenomena of uniform thermal regulation and non-thermal regulation osmotic energy conversion do not involve heat transfer phenomena and their derived heat diffusion and heat migration problems, and their control equations are the same, as follows:

[0125] Poisson's equation:

[0126] Flux continuity equation:

[0127] Nernst-Planck equation:

[0128] Velocity continuity equation:

[0129] Navier-Stokes equation:

[0130] Nanopore boundary equation:

[0131] The parameter meanings are the same as above. The obtained dimensionless control parameter group is simplified to a total of 6 dimensionless numbers. Although the dimensionless control parameter groups of uniform thermal regulation and non-thermal regulation osmotic energy conversion in the nanopore are the same, the specific values are different. The uniform thermal regulation involves the values of physical properties parameters affected by temperature.

[0132] In a specific embodiment, to quantitatively measure the guiding significance of the similarity principle for the modeling experiment of thermal regulation osmotic energy conversion in the nanopore, on the premise of ensuring that the values of the dimensionless control parameter group remain unchanged, numerical simulations are carried out on working conditions A, B, C, and D of thermal regulation osmotic energy conversion in the nanopore. Using the finite element method, the Poisson-Nernst-Planck equation, momentum equation, energy equation, and boundary equation are solved. The calculation formula for the power generation is:

[0133] P = I0φ0 / 4

[0134] Where P is the output power (W) of the thermal regulation osmotic energy conversion in the nanochannel.

[0135] The dimensionless output power expression is:

[0136]

[0137] The output power, osmotic current, diffusion potential and their dimensionless parameter values under different working conditions are shown in Table 1 and Table 2:

[0138] Table 1 Dimensional physical parameter values and errors under different working conditions

[0139]

[0140] Table 2 Dimensionless physical parameter values and errors under different working conditions

[0141]

[0142] It can be seen from Table 1 and Table 2 that although the physical fields under different working conditions are very different and the maximum error of the output characteristic physical quantity is as high as 145.88%, because the values of the dimensionless control parameter sets are the same, the dimensionless physical fields of these working conditions show the same law, and the maximum error of the dimensionless physical quantity is only 10 -9 order of magnitude. The results fully prove the correctness of the dimensionless control parameters and can be used to guide the modeling experiment.

[0143] The above has introduced the present disclosure in detail. Specific examples are used in this article to elaborate on the principle and implementation manner of the present disclosure. The description of the above embodiments is only used to help understand the method and its core idea of the present disclosure; at the same time, for those skilled in the art, according to the idea of the present disclosure, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present disclosure.

Claims

1. A method for analyzing the thermal regulation osmotic energy conversion of a salinity gradient power generation device, comprising the following steps: S100: Describe the physical and mathematical characteristics of the thermal regulation osmotic energy conversion of the salinity gradient power generation device, where the physical and mathematical characteristics include physical fields, control equations, physical parameters, and output performance; S200: Conduct a similarity analysis on the control equation using the similarity principle to obtain a dimensionless control parameter group π for characterizing the osmotic energy conversion of non-uniform thermal regulation, uniform thermal regulation, and non-thermal regulation of the salinity gradient power generation device i ; S300: Perform dimensional analysis on the physical parameters using the Pi theorem to obtain a dimensionless control parameter set Π i ; S400: Analyze the dimensionless control parameter group π i and the dimensionless control parameter group Π i to determine the dimensionless number of thermoregulated osmotic energy conversion in the nanochannels of the salinity gradient power generation device, and clarify the relationship between the dimensionless control parameter group π i and the dimensionless control parameter group Π i ; S500: Analyze the output performance through the similarity principle to define dimensionless electric potential and dimensionless current, so as to unify multiple groups of experimental samples into one dimensionless sample, or expand one group of dimensionless samples into multiple groups of different experimental samples; Among them, In step S100, the control equations include: Poisson's equation: ; Flux continuity equation: ; Nernst-Planck equation: ; Velocity continuity equation: ; Navier-Stokes equations: ; Energy equation: ; Boundary equation of nanochannel: ; Among them, is a partial differential operator, ε is the permittivity, is the electric potential, F is the Faraday constant, c is the concentration, z is the number of valence charges, i is the i-th ion, n is the total number of ion species, J is the ion flux, u is the velocity, D is the diffusion coefficient, R is the universal gas constant, T is the temperature, S T is the Soret coefficient, p is the pressure, μ is the viscosity coefficient, E is the electric field strength, ρ is the density, C p is the specific heat, λ is the thermal conductivity, σ f is the conductivity, and σ is the surface charge density; In step S100, the physical parameters include: working medium parameters, channel parameters, operating condition parameters, and constants, where The working fluid parameters include: dielectric constant ε, diffusion coefficient D, Soret coefficient S T , viscosity coefficient μ, thermal diffusivity α, thermal conductivity λ, electrical conductivity σ f ; The channel parameters include: characteristic length , surface charge density σ; Operating parameters include: electric potential , concentration c, velocity u, temperature T, pressure p; The constants include: Faraday constant F, universal gas constant R; In step S200, the dimensionless control parameter group π i includes: 、 、 、 、 、 、 、 、 ； Among them, Characterize the relative magnitude of the collected electric quantity of the spatial electric potential in the nanochannel and the spatial electric charge quantity; Characterize the relative electrical magnitude of the collected electric quantity of the surface electric potential of the nanochannel and the collected electric quantity of the surface charge density; Characterize the relative strength of ion convection and ion diffusion; Characterize the relative strength of ion electromigration and ion diffusion; Characterize the relative strength of ion thermomigration and ion diffusion; Characterize the relative magnitude of pressure and viscous force; Characterize the relative magnitude of electrostatic force and viscous force; Characterize the relative strength of heat convection and heat diffusion; Characterize the relative magnitude of Joule heat and heat diffusion; In step S300, the dimensionless control parameter group Π i includes: 、 、 、 、 、 、 、 、 。 2. The method according to claim 1, wherein In step S100, the physical fields include a concentration field, an electric potential field, a velocity field, and a temperature field, and there is a coupling effect among the concentration field, the electric potential field, the velocity field, and the temperature field.

3. The method according to claim 1, wherein, In step S100, the output performance includes: I-V curve, diffusion potential, osmotic current, and output power.

4. The method according to claim 1, wherein In step S400, the dimensionless control parameter group π i and the dimensionless control parameter group Π i After conversion, they are expressed as: ， ， ， ， ， ， ， ， ； Or it can be expressed as: ， ， ， ， ， ， ， ， 。 5. The method according to claim 1, wherein In step S500, The dimensionless electric potential is defined as: ； The dimensionless current is defined as: ； wherein, is the dimensionless electric potential, I * is the dimensionless current, L is the length of the nanochannel, R is the radius of the nanochannel, is the electric potential, is the charge density, is the dielectric constant, I is the current, F is the Faraday constant, c is the concentration, R is the universal gas constant, D is the diffusion coefficient.

6. The method according to claim 1, wherein In step S500, it is also necessary to perform normalization processing on the defined dimensionless electric potential and dimensionless current to obtain the normalized dimensionless electric potential and the normalized dimensionless current; The normalized dimensionless electric potential is expressed as: ； The normalized dimensionless current is expressed as: ； Among them, is the dimensionless potential after normalization, is the dimensionless current after normalization, is the dimensionless potential, I * is the dimensionless current, is the dimensionless diffusion potential, I0 * is the dimensionless osmotic current.

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