Flow cell flow channel optimization design method

Abstract

The invention relates to the technical field of flow batteries, and discloses a flow battery flow channel optimization design method, which comprises the following steps: S1, building an electric leakage model of an electric pile; s2, initializing equivalent flow channel resistance value calculation parameters; calculating an equivalent flow channel resistance value R; calculating leakage loss; s3, if the loss is smaller than a threshold value, executing S5; otherwise, executing S4 after R = R + delta r1; s4, calculating the loss again, and returning to S3; s5, if the equivalent diameter d of the flow channel does not meet the set range, the step S4 is executed after R = R-deltar2; otherwise, executing S6; and S6, outputting a flow channel scheme. The flow channel design precision is improved through an optimization algorithm, evaluation and control of leakage loss are considered through cooperation with a leakage model, the design reliability is improved, flow channel structure parameters are rapidly output through a computer, universality is good, the application range is wide, the method is suitable for various flow batteries, the parameters can be adjusted according to design indexes and actual requirements, and the method is suitable for large-scale popularization and application. The flexibility is high.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid flow batteries, and in particular to a liquid flow battery flow channel optimization design method. Background Art

[0002] Liquid flow battery is a device that converts chemical energy into electrical energy through electrochemical reactions. It has the advantages of high energy density, long life, and good safety. It is widely used in large-scale energy storage systems, power grid peak and frequency regulation, and renewable energy grid connection. The flow channel design method of liquid flow battery mainly focuses on the empirical formula method and numerical simulation method. Both are optimized from the perspective of fluid flow, without considering the factors affecting the circuit. In addition, the empirical formula method has low accuracy and requires experimental verification. It also does not take internal leakage into account and cannot meet the requirements of high-precision and high-reliability design. Although the numerical simulation method has a fast calculation speed, it does not consider the impact of internal leakage in the battery, resulting in the inability to guarantee the system efficiency of the battery. Summary of the invention

[0003] In view of the shortcomings and defects of the prior art, the present invention provides a method for optimizing the flow channel design of a liquid flow battery. Through the optimization algorithm and the leakage model, the influence and control of the internal leakage of the battery are taken into consideration on the basis of improving the accuracy of the flow channel design, thereby improving the reliability of the flow channel design.

[0004] The purpose of the present invention can be achieved through the following technical solutions.

[0005] A flow battery flow channel optimization design method comprises the following steps:

[0006] S1, build a leakage model of the flow battery stack according to the topological parameters of the flow battery stack;

[0007] S2, initializing the calculation parameters of equivalent flow channel resistance value;

[0008] Calculate the equivalent flow path resistance R: Where l is the equivalent length of the flow channel, s is the equivalent cross-sectional area of ​​the flow channel, and ρ is the resistivity of the electrolyte;

[0009] Substitute R into the leakage model to calculate the leakage loss;

[0010] S3, compare the leakage loss with the loss threshold in the design index: if the leakage loss is less than the loss threshold, directly execute step S5; otherwise, set the equivalent flow path resistance value R = R + Δr 1 Then execute step S4;

[0011] S4, substitute R into the leakage model, recalculate the leakage loss, and return to step S3;

[0012] S5, calculate the equivalent diameter d of the flow channel corresponding to the current equivalent flow channel resistance value: Where A and B represent the half-width and half-height of the flow channel;

[0013] Compare whether the equivalent flow channel diameter meets the set range: if not, set the equivalent flow channel resistance value R = R-Δr 2 , then jump to step S4; otherwise, execute step S6;

[0014] S6, outputting a flow channel optimization design solution according to the current corresponding flow channel structure parameters.

[0015] Preferably, the stack topology parameters mentioned in step S1 include the number of stacks, the number of batteries, the average stack voltage, the charge and discharge current density, and the reaction area.

[0016] Preferably, the leakage model is constructed by Kirchhoff's law or an equivalent circuit.

[0017] Preferably, the loss threshold in step S3 is determined according to the actual design and production requirements of the fuel cell stack and the power of the fuel cell stack; the set range in step S5 is determined according to the pressure loss of the fuel cell stack and the actual design and production requirements of the fuel cell stack.

[0018] Preferably, Δr 1 >Δr 2 .

[0019] The beneficial technical effects of the present invention are as follows: the accuracy of the flow channel design is improved through the optimization algorithm, and the collaboration with the leakage model not only takes the evaluation and control of the leakage loss into consideration, thereby improving the reliability of the flow channel design, but also can use a computer to quickly output the flow channel structure parameters. It has good versatility and a wide range of applications, and is suitable for various liquid flow batteries. Since the stack topology parameters and the flow channel structure parameters can be adjusted according to the design indicators and actual needs, it also has high flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is the overall flow chart of the present invention.

[0021] Figure 2 The stack leakage current distribution obtained before and after the flow channel optimization design is performed on the same liquid flow battery in the embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the present invention.

[0023] The leakage loss can be calculated by the leakage model. The leakage model has no clear definition and is defined by technical personnel in this field in combination with existing technologies and actual conditions. For example, the equivalent flow path resistance value is substituted into the leakage model to obtain the average leakage current of the battery stack. The total leakage loss is obtained by multiplying the average leakage current of the battery stack, the number of battery stacks and the average voltage of the battery stack.

[0024] The above method is further described below according to embodiments.

[0025] For the same zinc-based flow battery, before executing this method, the leakage current is tested to obtain a leakage current distribution diagram, and then this method is executed under the same conditions, such as Figure 1 As shown:

[0026] S1, input the number of battery stacks 4, the number of single-stack batteries 30, and the average voltage of the battery stack 1.7V, and use Simulink to build an equivalent circuit leakage model of the battery stack;

[0027] S2, electrolyte resistivity ρ = 0.0296Ω·m, equivalent length of flow channel l = 0.26m, equivalent cross-sectional area of ​​flow channel s = 1.65mm 2 , calculate the equivalent flow channel resistance R:

[0028] Substitute R into the leakage model to obtain the initial leakage current of the current battery stack. Multiply the initial leakage current by the average voltage of the battery stack and the number of battery stacks and sum them up to obtain a leakage loss of 563W.

[0029] S3, the loss threshold in the design index is 250W, the calculated value is greater than the threshold, and the equivalent flow channel resistance value R=R+100Ω;

[0030] S4, update the equivalent flow channel resistance value R in the model to 600Ω, and recalculate the leakage loss to 475W;

[0031] S3, it is found that 475W is still greater than the loss threshold, and the process of "R = R + 100Ω - calculate leakage loss" is repeated until the leakage loss is 234W, which is less than the loss threshold. At this time, the equivalent flow channel resistance value R is 1300Ω, and step S5 is executed;

[0032] S5, calculating that the equivalent diameter d of the flow channel corresponding to the current equivalent flow channel resistance value is 1.2 mm;

[0033] The preset range is ≤1.5 mm, and the value of d meets this range, so step S6 is directly executed;

[0034] S6, according to the current corresponding flow channel structure parameters, output the optimized design scheme of the flow channel structure, and measure the optimized leakage current distribution, and compare it with the leakage current result tested before executing this method, see attached Figure 2 .

[0035] according to Figure 2 From the comparison results, it can be seen that after using this method to optimize the flow channel design, not only the flow channel structure parameters are guaranteed to meet the design standards, but also the overall leakage current is significantly reduced.

[0036] Due to the high precision of the computer algorithm, the accuracy of the flow channel structure parameters obtained using this method is higher than that of the empirical formula method; compared with the numerical simulation method, this method takes into account the influence of the flow channel structure on the internal leakage, improves the reliability of the flow channel design, and ensures the efficiency of the battery stack system; and the new scheme can quickly obtain the maximum equivalent flow channel resistance that meets both loss requirements and structural requirements, greatly improving the design efficiency.

[0037] The above embodiments are descriptions of specific implementation methods of the present invention rather than limitations of the present invention. Technical personnel in the relevant technical field may make various changes and modifications to obtain corresponding equivalent technical solutions without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should be included in the patent protection scope of the present invention.

Claims

1. A flow battery flow channel optimization design method, characterized in that: The following steps are involved: S1, build a leakage model of the flow battery stack according to the topological parameters of the flow battery stack; S2, initializing the calculation parameters of equivalent flow channel resistance value; Calculate the equivalent flow path resistance R: Where l is the equivalent length of the flow channel, s is the equivalent cross-sectional area of ​​the flow channel, and ρ is the resistivity of the electrolyte; Substitute R into the leakage model to calculate the leakage loss; S3, compare the leakage loss with the loss threshold in the design index: if the leakage loss is less than the loss threshold, directly execute step S5; otherwise, set the equivalent flow path resistance value R=R+Δr1 and then execute step S4; S4, substitute R into the leakage model, recalculate the leakage loss, and return to step S3; S5, calculate the equivalent diameter d of the flow channel corresponding to the current equivalent flow channel resistance value: Where A and B represent the half-width and half-height of the flow channel; Compare whether the equivalent flow channel diameter meets the set range: if not, set the equivalent flow channel resistance value R=R-Δr2, and then jump to step S4; otherwise, execute step S6; S6, outputting a flow channel optimization design solution according to the current corresponding flow channel structure parameters.

2. A flow battery flow channel optimization design method according to claim 1, characterized in that: The stack topology parameters mentioned in step S1 include the number of stacks, the number of batteries, the average voltage of the stack, the charge and discharge current density, and the reaction area.

3. A flow battery flow channel optimization design method according to claim 1, characterized in that: Construct leakage model through Kirchhoff's law or equivalent circuit.

4. A flow battery flow channel optimization design method according to claim 1, characterized in that: The loss threshold in step S3 is determined based on the actual design and production requirements of the fuel cell stack and the power of the fuel cell stack; the set range in step S5 is determined based on the pressure loss of the fuel cell stack and the actual design and production requirements of the fuel cell stack.

5. The method for optimizing the flow channel design of a liquid flow battery according to claim 1, characterized in that: Δr1>Δr2.

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