A method for optimizing the performance of a rotating proton exchange membrane fuel cell

Abstract

The present invention discloses a method for optimizing the performance of a rotating proton exchange membrane fuel cell, comprising the following steps: firstly, three-dimensional modeling is performed according to the geometric structure of the proton exchange membrane fuel cell; the grid model is imported into the computational fluid dynamics software for simulation calculation by grid division; the oxygen distribution cloud map and its uniformity coefficient at the interface between the cathode diffusion layer and the catalyst layer of the fuel cell are obtained by post-processing the calculation results; the convective diffusion of reactants in the fuel cell and the uniformity of oxygen distribution are improved by adjusting the rotation angular velocity, so as to achieve the purpose of optimizing the output performance of the proton exchange membrane fuel cell. The present invention can optimize the uniform distribution of reactants in the fuel cell, improve its output performance, save time and economic costs, and provide a new idea for improving the performance of the proton exchange membrane fuel cell.

Description

Technical Field

[0001] The invention belongs to the field of proton exchange membrane fuel cells, and in particular relates to a method for optimizing the performance of a rotating proton exchange membrane fuel cell. Background Art

[0002] As an advanced hydrogen energy conversion device, proton exchange membrane fuel cells have the advantages of high efficiency, zero emissions, fast startup speed, and low operating noise, and have received much attention in the energy field. They are widely used in vehicle power supply, distributed power generation, and aerospace. However, existing proton exchange membrane fuel cells have the main disadvantages of uneven oxygen distribution on the membrane electrode surface and difficulty in discharging liquid water, which leads to unsatisfactory output performance and service life of proton exchange membrane fuel cell systems, and also becomes a key factor restricting its large-scale industrial production.

[0003] To solve the above problems, the commonly used method is to improve the flow field structure of the proton exchange membrane fuel cell. However, the effect of improving the flow field structure on improving the uniform distribution of reactants in the fuel cell and improving its output performance is limited. At the same time, the flow field with a complex structure has negative problems such as high manufacturing cost and high pressure drop during operation. The present invention provides a method for optimizing the performance of a rotating proton exchange membrane fuel cell. By optimizing the rotation speed of the fuel cell, the uniform distribution of reactants inside the fuel cell is achieved, thereby improving its output performance. This provides a new idea for improving the performance of proton exchange membrane fuel cells.

[0004] Computational fluid dynamics is a discipline that uses computers and numerical methods to solve the governing equations of fluid mechanics and simulate and analyze fluid mechanics problems. Computational fluid dynamics analysis can not only reduce the high cost of actual experiments, but also better understand the physical phenomena of fluid flow in a qualitative and quantitative way. Therefore, the application of computational fluid dynamics methods to the research of proton exchange membrane fuel cells has the advantages of low cost, high efficiency, and the ability to truly reflect the mass transfer characteristics inside the battery, providing a basis for the improved design of fuel cells and shortening the design cycle. At present, there is a certain basis for applying numerical simulation to the flow field design of proton exchange membrane fuel cells, but there is no optimization method for rotating proton exchange membrane fuel cells based on the uniform distribution of oxygen. Summary of the invention

[0005] The present invention provides a method for optimizing the performance of a rotating proton exchange membrane fuel cell, which improves the convective diffusion of reactants in the fuel cell and the uniformity of oxygen distribution by increasing the rotational angular velocity, thereby achieving the purpose of optimizing the output performance of the proton exchange membrane fuel cell.

[0006] The specific technical solutions adopted by the present invention are as follows:

[0007] S1: According to the geometric structure of the proton exchange membrane fuel cell, a three-dimensional structural model of the proton exchange membrane fuel cell is constructed by three-dimensional modeling software, wherein the model includes an anode part and a cathode part of the fuel cell, and a proton exchange membrane arranged between the anode and cathode parts of the fuel cell; the anode part includes an anode plate, an anode reactant flow channel, an anode gas diffusion layer and an anode catalyst layer; the cathode part includes a cathode catalyst layer, a cathode gas diffusion layer, a cathode reactant flow channel and a cathode plate; wherein the anode diffusion layer, the anode catalyst layer, the proton exchange membrane, the cathode catalyst layer and the cathode diffusion layer are sequentially combined to form a membrane electrode assembly;

[0008] By using meshing software, the geometric model of the proton exchange membrane fuel cell is meshed and associated according to the structural features of the geometric model to obtain a mesh model. Finally, the network model in msh format is output and imported into computational fluid dynamics software to simulate the proton exchange membrane fuel cell;

[0009] S2: On the basis of S1, a PEMFC numerical model is established in the computational fluid dynamics software; at the same time, the boundary conditions of the network model are set and then the calculation is performed; when the calculation converges, the calculation results are post-processed, the distribution of the reactants in the calculation results is selected, and the interface between the cathode diffusion layer and the catalyst layer of the proton exchange membrane fuel cell is taken as the object, the oxygen distribution cloud map of the interface is drawn, and its uniformity coefficient is calculated;

[0010] S3: Execute S31 or S32 according to the oxygen distribution cloud map and uniformity coefficient in S2.

[0011] S31: If the oxygen distribution uniformity coefficient in S2 is greater than K, the proton exchange membrane fuel cell model does not need to be optimized, and S5 is executed;

[0012] S32: If the oxygen distribution uniformity coefficient in S2 is less than K, the proton exchange membrane fuel cell is further optimized and S4 is executed;

[0013] S4: Taking the center of the proton exchange membrane fuel cell disk as the rotation center, adjust the rotation angular velocity ω according to the situation;

[0014] S41: If the oxygen distribution uniformity coefficient in S2 is less than K, the initial rotation angular velocity of the proton exchange membrane fuel cell is recorded as ω0;

[0015] S42: setting the rotation angular velocity to ω1 (ω0<ω1); repeating S2 in the case of the rotational proton exchange membrane fuel cell model to determine whether the oxygen distribution uniformity coefficient is greater than K when the rotation angular velocity is ω1;

[0016] S43: If the oxygen distribution uniformity coefficient in S42 is greater than K, execute S5;

[0017] S44: If the oxygen distribution uniformity coefficient in S42 is less than K, the rotation angular velocity is changed to ω i+1 =2ω i -ω i-1 , the initial value of i is 1; repeat S2 in the case of the rotating proton exchange membrane fuel cell model, and determine when the rotation angular velocity is ω i+1 Whether the oxygen distribution uniformity coefficient is greater than K;

[0018] S45: If the oxygen distribution uniformity coefficient in S44 is greater than K, execute S5;

[0019] S46: If the oxygen distribution uniformity coefficient in S44 is less than K, execute S44 to add 1 to i until the uniformity coefficient is greater than K, and execute S5;

[0020] S47: If the optimization is invalid, the rotation angular velocity is changed to ω i+1 =ω i -0.5ω i-1 , the initial value of i is 1; repeat S2 in the case of the rotating proton exchange membrane fuel cell model, and determine when the rotation angular velocity is ω i+1 Whether the oxygen distribution uniformity coefficient is greater than K;

[0021] S48: If the oxygen distribution uniformity coefficient in S47 is greater than K, execute S5;

[0022] S49: If the oxygen distribution uniformity coefficient in S47 is less than K, execute S44;

[0023] S5: Based on the numerical simulation results, compare the polarization curves and output power density curves of the proton exchange membrane fuel cell before and after optimization. Then, determine whether the optimization is effective by calculating the net output power;

[0024] S51: If the net power after optimization in S5 is greater than or equal to the net power after the previous optimization, the optimization is effective and ends;

[0025] S52: If the net power after optimization in S5 is less than the net power after the previous optimization, the optimization is invalid and S47 is executed until the net power after optimization is greater than or equal to the net power after the previous optimization, and the optimization ends.

[0026] Preferably, in S1, when the structure of the proton exchange membrane fuel cell is geometrically symmetrical relative to the center of the disk, the three-dimensional structural model is a complete model or a 1 / n model relative to the center of the disk; when the structure of the proton exchange membrane fuel cell is asymmetrical relative to the center of the disk, the three-dimensional structural model is a complete model.

[0027] Preferably, in S1, the geometric model is grouped and established according to different components and boundary conditions of the proton exchange membrane fuel cell, and is segmented and associated according to the structural characteristics of the geometric model; the generation parameters of the geometric grid are set, the network model of the proton exchange membrane fuel cell is established, and the grid parameters are adjusted according to the network quality of the geometric model. After the network quality meets the simulation conditions, the grid is converted into a structured grid or an unstructured grid according to the calculation requirements.

[0028] Preferably, in S2, if the three-dimensional structural model is a complete proton exchange membrane fuel cell model, a no-slip wall boundary condition is set for the inner wall of the network model; if the three-dimensional structural model is a 1 / n proton exchange membrane fuel cell model relative to the center of the disk, a no-slip wall boundary condition is set for the inner wall of the network model, and a symmetric boundary condition is set for the proton exchange membrane fuel cell section.

[0029] Furthermore, in S2, the boundary conditions include one or more of mass flow inlet boundary conditions, pressure outlet boundary conditions, velocity inlet boundary conditions and velocity outlet boundary conditions.

[0030] Furthermore, in S2, by monitoring relevant variables such as the average current density on the anode and cathode plates of the proton exchange membrane fuel cell and the average mass fraction of oxygen in the cathode diffusion layer, when the rate of change between two consecutive iterations is less than 0.01%, it can be considered that the convergence condition has been reached and the iterative calculation is terminated.

[0031] Furthermore, in S2, the oxygen mass fraction at the interface between the cathode diffusion layer and the catalyst layer of the proton exchange membrane fuel cell is numerically sampled according to the grid points, and is calculated according to the following formula to obtain its oxygen distribution uniformity coefficient:

[0032] { U = 1 − ∑ i = 1 n [ ( | X i − X A | ) A ] 2 | X A | ∑ i = 1 n A X A = ∑ i = 1 n X i A ∑ i = 1 n A i

[0033] Among them, U is the uniformity coefficient, the closer it is to 1, the more uniform the distribution is, and A is the effective surface area, cm 2 ;X i is the oxygen mass fraction at the i-th grid point; X A is the average mass fraction of oxygen on the surface.

[0034] Furthermore, in S3 and S4, K can be set to any value between 0.8 and 0.95 according to actual needs, and used as a criterion for determining whether the optimization is completed.

[0035] Furthermore, in S5, the calculation formula of the net output power is as follows:

[0036]

[0037] Among them, P net is the net output power, W; P FC is the output power, W; P P is the pumping work, W; P r is the power consumption of the rotating motor, W; I FC is the working current density, A·cm -2 ; V FC is the working voltage, V; ΔP is the pressure difference between the inlet and outlet of the flow channel, Pa; A inlet is the cross-sectional area of ​​the air inlet, cm 2 ;u inlet is the average velocity at the air inlet, m·s -1 ; T is the motor circumferential torque, N·m.

[0038] Preferably, the 3D modeling software is one of Solidworks, Creo, Inventor, UG / NX, CATIA, ANSYS Workbench DesigModeler or ANASYS Workbench SpaceClaim.

[0039] Preferably, the meshing software is one of ICEM CFD, HyperMesh, TGrid, PointWise, ANSA, GridPro or ANSYS Workbench Mesh.

[0040] Preferably, the computational fluid dynamics software is one of ANSYS Fluent, AVE-Fire, STARCCM+ or Comsol Multiphysics.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) The present invention realizes an improved design for the uniformity of oxygen distribution in proton exchange membrane fuel cells without the need for repeated theoretical calculations and experimental corrections, which is beneficial to the uniform distribution of reactants in industrialized proton exchange membrane fuel cells.

[0043] (2) The present invention proposes a rotating proton exchange membrane fuel cell for improving the uniformity of oxygen mass distribution, and quantitatively defines the uniformity of oxygen distribution at the interface between the cathode diffusion layer and the catalyst layer; by changing the angular velocity of rotation, the convective diffusion of reactants in the proton exchange membrane fuel cell is improved, thereby improving the uniformity of oxygen distribution and optimizing the output performance of the proton exchange membrane fuel cell.

[0044] (3) Based on the numerical simulation method, the present invention intuitively presents the details of oxygen distribution at the interface between the cathode diffusion layer and the catalyst layer of the proton exchange membrane fuel cell, thereby clarifying the distribution law of oxygen in the fuel cell; at the same time, by changing the rotational angular velocity of the fuel cell, the uniformity of oxygen distribution is improved, the convection diffusion of reactants in the fuel cell is enhanced, and tedious and complicated theoretical calculations and experimental corrections are avoided, providing a new idea for improving the uniformity of oxygen distribution and improving the output performance of proton exchange membrane fuel cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram of the steps of the method of the present invention;

[0046] Figure 2 A three-dimensional structural model of a proton exchange membrane fuel cell in an embodiment;

[0047] Figure 3 A 1 / 4 proton exchange membrane fuel cell network model is established according to the three-dimensional structure model in the embodiment;

[0048] Figure 4 The oxygen distribution cloud diagram and uniformity coefficient of the interface between the cathode diffusion layer and the catalyst layer of the proton exchange membrane fuel cell in the initial state in the embodiment;

[0049] Figure 5 The oxygen distribution cloud diagram and uniformity coefficient of the interface between the cathode diffusion layer and the catalyst layer of the proton exchange membrane fuel cell after the first optimization in the embodiment;

[0050] Figure 6 The oxygen distribution cloud diagram and uniformity coefficient of the interface between the cathode diffusion layer and the catalyst layer of the proton exchange membrane fuel cell after the second optimization in the embodiment;

[0051] Figure 7 This is a comparison diagram of the output performance of the proton exchange membrane fuel cell before and after optimization in the embodiment;

[0052] In the figure: 1. anode plate; 2. anode reactant flow channel; 3. cathode reactant flow channel; 4. cathode plate; 5. anode diffusion layer; 6. anode catalyst layer; 7. proton exchange membrane; 8. cathode catalyst layer; 9. cathode diffusion layer. Specific implementation plan

[0053] In order to make the purpose, technical method and advantages of the embodiments of the present invention clearer, the technical method in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] In view of the distribution of oxygen in the fuel cell, the present invention proposes a rotating proton exchange membrane fuel cell for improving the uniformity of oxygen distribution at the interface between the diffusion layer and the catalyst layer. By increasing the rotational angular velocity, the convective diffusion of reactants in the fuel cell is improved, the uniformity of oxygen distribution is improved, and the output performance of the proton exchange membrane fuel cell is optimized.

[0055] The optimization method of the rotating proton exchange membrane fuel cell is specifically performed as follows:

[0056] S1: proceed in sequence according to steps 1) to 3), as follows:

[0057] 1) According to the geometric structure of the proton exchange membrane fuel cell, a three-dimensional structural model of the proton exchange membrane fuel cell is constructed by three-dimensional modeling software. In the process of constructing the three-dimensional structural model, when the structure of the rotating proton exchange membrane fuel cell is geometrically symmetrical relative to the center of the disk, the three-dimensional structural model can use a complete fuel cell model or a 1 / n model relative to the center of the disk. When the structure of the rotating proton exchange membrane fuel cell is geometrically asymmetrical relative to the center of its disk, the three-dimensional structural model can only use a complete fuel cell model.

[0058] 2) Group components according to different components and boundary conditions of the proton exchange membrane fuel cell, and segment and associate them according to the structure of the geometric model; set the geometric mesh generation parameters, establish the network model of the proton exchange membrane fuel cell, and adjust it according to the network quality parameters of the geometric model. After the network quality meets the simulation conditions, convert the mesh into a structured mesh or an unstructured mesh according to the calculation requirements.

[0059] 3) The obtained network model of the proton exchange membrane fuel cell is exported in msh format and imported into computational fluid dynamics software to perform simulation calculations on the proton exchange membrane fuel cell.

[0060] S2: On the basis of S1, a PEMFC numerical model is established in the computational fluid dynamics software, and the boundary conditions of the network model are set to perform calculations. When the calculation converges, the oxygen distribution in the calculation results is selected, and the interface between the cathode diffusion layer and the catalyst layer of the proton exchange membrane fuel cell is taken as the object, and the oxygen distribution cloud map of the interface is drawn, and its uniformity coefficient is calculated, wherein the uniformity coefficient calculation formula is as follows:

[0061] { U = 1 − ∑ i = 1 n [ ( | X i − X A | ) A ] 2 | X A | ∑ i = 1 n A X A = ∑ i = 1 n X i A ∑ i = 1 n A i

[0062] Among them, U is the uniformity coefficient, the closer it is to 1, the more uniform the distribution is, and A is the effective surface area, cm 2 ;X i is the oxygen mass fraction at the i-th grid point; X Ais the average mass fraction of oxygen on the surface;

[0063] S3: Execute S31 or S32 according to the oxygen distribution cloud map and uniformity coefficient in S2;

[0064] S31: If the oxygen distribution uniformity coefficient in S2 is greater than K, execute S5;

[0065] S32: If the oxygen distribution uniformity coefficient in S2 is less than K, the proton exchange membrane fuel cell is further optimized and S4 is executed;

[0066] S4: Taking the center of the proton exchange membrane fuel cell disk as the rotation center, adjust the rotation angular velocity ω according to the situation;

[0067] S41: If the oxygen distribution uniformity coefficient in S2 is less than K, the initial rotation angular velocity of the proton exchange membrane fuel cell is recorded as ω0;

[0068] S42: setting the rotation angular velocity to ω1 (ω0<ω1); repeating S2 in the case of the rotational proton exchange membrane fuel cell model to determine whether the oxygen distribution uniformity coefficient is greater than K when the rotation angular velocity is ω1;

[0069] S43: If the oxygen distribution uniformity coefficient in S42 is greater than K, execute S5;

[0070] S44: If the oxygen distribution uniformity coefficient in S42 is less than K, the rotational angular velocity of the rotary proton exchange membrane fuel cell is changed to ω2=2ω1-ω0. The operation of S2 is repeated according to the rotational angular velocity at this time to determine whether the oxygen distribution uniformity coefficient reaches K when the rotational angular velocity is ω2;

[0071] S4i+1: If the oxygen distribution uniformity coefficient in S4i is greater than K, execute S5;

[0072] If the oxygen distribution uniformity coefficient in S4i+1 is less than K, the rotation angular velocity is changed to ω i+1 =2ω i -ω i-1 Repeat the operation of S2 according to the rotation angular velocity at this time to determine that the current rotation angular velocity is ω i+1 Whether the oxygen distribution uniformity coefficient is greater than K. The initial value of i is 1;

[0073] S4i+2: If the oxygen distribution uniformity coefficient in S4i+1 is greater than K, execute S5;

[0074] If the oxygen distribution uniformity coefficient of S4i+1 is less than K, then the operation of adding 1 is performed on i, and the rotation angular velocity is continuously optimized according to the operation of S4i+1 until the oxygen distribution uniformity coefficient is greater than K, and S5 is executed;

[0075] Among them, K can be set to any value between 0.8 and 0.95 according to actual needs, and used as a criterion for determining whether the optimization is completed;

[0076] S4i+3: If the optimization in S5 is invalid, the rotation angular velocity is changed to ω i+1 =ω i -0.5ω i-1 , the initial value of i is 1; repeat S2 in the case of the rotating proton exchange membrane fuel cell model, and determine when the rotation angular velocity is ω i+1 Whether the oxygen distribution uniformity coefficient is greater than K;

[0077] If the oxygen distribution uniformity coefficient in S4i+3 is greater than K, execute S5;

[0078] If the oxygen distribution uniformity coefficient in S4i+3 is less than K, execute S44;

[0079] S5: Based on the numerical simulation results, compare the polarization curve and output power density curve of the proton exchange membrane fuel cell before and after optimization. Then, determine whether the optimization is effective by calculating the net output power. The net power calculation formula is as follows:

[0080]

[0081] Among them, P net is the net output power, W; P FC is the output power, W; P P is the pumping work, W; P r is the power consumption of the rotating motor, W; I FC is the working current density, A·cm -2 ; V FC is the working voltage, V; ΔP is the pressure difference between the inlet and outlet of the flow channel, Pa; A inlet is the cross-sectional area of ​​the air inlet, cm 2 ;u inlet is the average velocity at the air inlet, m·s -1 ; T is the motor circumferential torque, N·m.

[0082] S51: If the net power after optimization in S5 is greater than or equal to the net power after the previous optimization, the optimization is effective and ends;

[0083] S52: If the net power after optimization in S5 is less than the net power after the previous optimization, the optimization is invalid and S4i+3 is executed until the net power after optimization is greater than or equal to the net power after the previous optimization, and the optimization ends.

[0084] In actual application, the 3D modeling software can be one of Solidworks, Creo, Inventor, UG / NX, CATIA, ANSYS Workbench DesigModeler or ANASYS Workbench SpaceClaim. The meshing software can be one of ICEM CFD, HyperMesh, TGrid, PointWise, ANSA, GridPro or ANSYSWorkbench Mesh. The computational fluid dynamics software can be one of ANSYS Fluent, AVE-Fire, STARCCM+ or Comsol Multiphysics.

[0085] Example

[0086] S1: Figure 2 As shown in the figure, a three-dimensional structural model of a proton exchange membrane fuel cell is constructed using Solidworks modeling software. Figure 2 It can be seen that the structure of the proton exchange membrane fuel cell is geometrically symmetrical about the center of the disk, so a 1 / 4 fuel cell calculation model symmetrical about the center of the disk can be established, and its geometric parameters are shown in Table 1. Through the meshing software Hypermesh, the components are grouped according to the different components and boundary conditions of the proton exchange membrane fuel cell, divided and associated according to its geometric structure, and the geometric network generation parameters are set to establish a network model. In order to ensure that the simulation results are independent of the number of grids, the network model is encrypted, and four groups of models with grid numbers of 339,768, 532,864, 817,872 and 954,184 are established. Through simulation verification, considering the current computing power and the accuracy of the results, the model with a grid number of 532,864 was finally selected for numerical simulation calculations. The specific grid size is as follows Figure 3 The obtained 1 / 4 proton exchange membrane fuel cell network model was imported into the computational fluid dynamics software Fluent.

[0087] Table 1 Specific parameters

[0088] Parameter name Numeric Plate inner radius, outer radius (mm) 3，15 Flow channel width (mm) 1 Flow channel height (mm) 1 Rib width(mm) 1 Film thickness(mm) 0.05 Diffusion layer thickness (mm) 0.2 Catalytic layer thickness (mm) 0.01

[0089] S2: In the computational fluid dynamics software Fluent, a PEMFC numerical model was established in the computational fluid dynamics software. The simulation parameters of the proton exchange membrane fuel cell were set as shown in Table 2. The inner wall of the network model was set to a no-slip wall boundary condition, and the cross section of the proton exchange membrane fuel cell was set to a symmetric boundary condition before the calculation began.

[0090] Table 2 Specific parameters

[0091] Parameter name Numeric Anode air intake mass flow rate (kg / s) 3.69e-07 Cathode air intake mass flow rate (kg / s) 3.67e-06 Outlet pressure (atm) 0 Working pressure(Pa) 1.10e+06 Air temperature (K) 353 Working temperature(K) 353 <![CDATA[Reference current density (A·m -2 )]]> 13000 <![CDATA[Membrane equivalent (kg·kmol -1 )]]> 1100 Anode relative humidity 100% Cathode relative humidity 100% <![CDATA[Anodic exchange current density (A·m -2 )]]> 4450 <![CDATA[Cathodic exchange current density (A·m -2 )]]> 0.05 <![CDATA[Anodic reference concentration (kmol·m -3 )]]> 0.04 <![CDATA[Cathode reference concentration (kmol·m -3 )]]> 0.04 Anode concentration index 0.5 Cathode concentration index 1 Anode transfer coefficient 0.5 Cathode transfer coefficient 1

[0092] By monitoring the relevant variables such as the average current density on the surface of the anode and cathode plates of the proton exchange membrane fuel cell and the average oxygen concentration in the cathode diffusion layer. When the rate of change between two consecutive iterations is less than 0.01%, it can be considered that the convergence condition has been reached and the iterative calculation is terminated. Then, the calculation results are post-processed in the computational fluid dynamics software Fluent or its supporting post-processing software Tecplot.

[0093] The post-processing steps are as follows: select the oxygen mass fraction distribution in the calculation results, select the interface between the cathode diffusion layer and the catalyst layer of the proton exchange membrane fuel cell as the object, and draw the oxygen distribution cloud map of the interface; in addition, the oxygen mass fraction of the interface is numerically sampled according to the grid points, and calculated according to the following formula to obtain its oxygen distribution uniformity coefficient. The result is as follows Figure 4 shown.

[0094] { U = 1 − ∑ i = 1 n [ ( | X i − X A | ) A ] 2 | X A | ∑ i = 1 n A X A = ∑ i = 1 n X i A ∑ i = 1 n A i

[0095] Among them, U is the uniformity coefficient, the closer it is to 1, the more uniform the distribution is, and A is the effective surface area, cm 2 ;X i is the oxygen mass fraction at the i-th grid point; X A is the average surface oxygen mass fraction.

[0096] S3: Figure 4 The figure shows the oxygen distribution cloud diagram at the interface between the cathode diffusion layer and the catalyst layer in the initial state. The uniformity coefficient is 0.9146, which is less than 0.95. Therefore, the proton exchange membrane fuel cell needs to be optimized.

[0097] S4: Apply a rotational angular velocity ω1=360 rpm to the proton exchange membrane fuel cell. Repeat S2 at this rotational angular velocity to determine whether the oxygen distribution uniformity coefficient is greater than 0.95 when the rotational angular velocity is ω2. The oxygen distribution cloud map and uniformity coefficient after the first optimization are as follows: Figure 5 shown.

[0098] from Figure 5 It can be seen that the oxygen distribution uniformity coefficient is 0.9322, which is still less than 0.95. Then the rotation angular velocity is changed to ω2, and the value of ω2 is ω2=ω1+ω0. Repeat S2 at this rotation angular velocity to determine whether the oxygen distribution uniformity coefficient is greater than 0.95 when the rotation angular velocity is ω2. The oxygen distribution cloud map and uniformity coefficient after the first optimization are as follows: Figure 6 shown.

[0099] from Figure 6It can be seen that the oxygen distribution uniformity coefficient at this rotation angular velocity is 0.9542, which is greater than 0.95, thus achieving the optimization goal.

[0100] S5: Figure 7 The figure shows the comparison of the polarization curve and output power density of the initial state of the proton exchange membrane fuel cell and after two optimizations. It can be seen from the figure that when the operating voltage is 0.5 V, the output power density after the first optimization is increased by 4.0% compared with the initial state, and the output power density after the second optimization is increased by 8.5% compared with the initial state. That is, the optimized rotating proton exchange membrane fuel cell has a significant effect on performance improvement. In addition, considering the additional pumping power and rotating motor power consumption required when the rotating proton exchange membrane fuel cell is working, the net output power after the second optimization calculated by the following formula is 0.9347 W, which is greater than the net output power after the first optimization (0.8984 W), so it can be considered that the optimization is effective and the optimization is completed.

[0101]

[0102] Among them, P net is the net output power, W; P FC is the output power, W; P P is the pumping work, W; P r is the power consumption of the rotating motor, W; I FC is the working current density, A·cm -2 ; V FC is the working voltage, V; ΔP is the pressure difference between the inlet and outlet of the flow channel, Pa; A inlet is the cross-sectional area of ​​the air inlet, cm 2 ;u inlet is the average velocity at the air inlet, m·s -1 ; T is the motor circumferential torque, N·m.

[0103] The present invention provides a method for optimizing the performance of a rotating proton exchange membrane fuel cell. By increasing the rotational angular velocity, the convection diffusion of reactants in the fuel cell is improved, and the uniformity of oxygen distribution is improved, thereby achieving the purpose of improving the output performance of the proton exchange membrane fuel cell, while avoiding repeated theoretical calculations and experimental corrections.

[0104] The above embodiment is only a preferred solution of the present invention, but it is not intended to limit the present invention. A person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. A method for optimizing the performance of a rotating proton exchange membrane fuel cell, characterized in that: The details are as follows: S1: According to the geometric structure of the proton exchange membrane fuel cell, a three-dimensional structural model of the proton exchange membrane fuel cell is constructed by three-dimensional modeling software, wherein the model includes an anode part and a cathode part of the fuel cell, and a proton exchange membrane arranged between the anode and cathode parts of the fuel cell; the anode part includes an anode plate, an anode reactant flow channel, an anode gas diffusion layer and an anode catalyst layer; the cathode part includes a cathode catalyst layer, a cathode gas diffusion layer, a cathode reactant flow channel and a cathode plate; wherein the anode diffusion layer, the anode catalyst layer, the proton exchange membrane, the cathode catalyst layer and the cathode diffusion layer are sequentially combined to form a membrane electrode assembly; By using meshing software, the geometric model of the proton exchange membrane fuel cell is segmented and associated according to the structural features of the geometric model, and the geometric model is meshed to obtain a network model; finally, the mesh file in msh format is output and imported into computational fluid dynamics software to perform simulation calculation on the proton exchange membrane fuel cell; S2: On the basis of S1, a PEMFC numerical model is established in the computational fluid dynamics software; at the same time, the boundary conditions of the network model are set and then the calculation is performed; when the calculation converges, the calculation results are post-processed, the distribution of the reactants in the calculation results is selected, and the interface between the cathode diffusion layer and the catalyst layer of the proton exchange membrane fuel cell is taken as the object, the oxygen distribution cloud map of the interface is drawn, and its uniformity coefficient is calculated; S3: Execute S31 or S32 according to the oxygen distribution cloud map and uniformity coefficient in S2; S31: If the oxygen distribution uniformity coefficient in S2 is greater than K, the proton exchange membrane fuel cell model does not need to be optimized, and S5 is executed; S32: If the oxygen distribution uniformity coefficient in S2 is less than K, the proton exchange membrane fuel cell is further optimized and S4 is executed; S4: Taking the center of the proton exchange membrane fuel cell disk as the rotation center, adjust the rotation angular velocity ω according to the situation; S41: If the oxygen distribution uniformity coefficient in S2 is less than K, the initial rotation angular velocity of the proton exchange membrane fuel cell is recorded as ω0; S42: setting the rotation angular velocity to ω1, ω0<ω1; repeating S2 in the case of the rotating proton exchange membrane fuel cell model to determine whether the oxygen distribution uniformity coefficient is greater than K when the rotation angular velocity is ω1; S43: If the oxygen distribution uniformity coefficient in S42 is greater than K, execute S5; S44: If the oxygen distribution uniformity coefficient in S42 is less than K, the rotation angular velocity is changed to ω i+1 =2ω i -ω i-1 , the initial value of i is 1; In the case of the rotating proton exchange membrane fuel cell model, S2 is repeated to determine when the rotation angular velocity is ωi +1 Whether the oxygen distribution uniformity coefficient is greater than K; S45: If the oxygen distribution uniformity coefficient in S44 is greater than K, execute S5; S46: If the oxygen distribution uniformity coefficient in S44 is less than K, execute S44 to add 1 to i until the uniformity coefficient is greater than K, and execute S5; S47: If the optimization is invalid, the rotation angular velocity is changed to ω i+1 =ω i -0.5ω i-1 , the initial value of i is 1; In the case of the rotating proton exchange membrane fuel cell model, S2 is repeated to determine when the rotation angular velocity is ω i+1 Whether the oxygen distribution uniformity coefficient is greater than K; S48: If the oxygen distribution uniformity coefficient in S47 is greater than K, execute S5; S49: If the oxygen distribution uniformity coefficient in S47 is less than K, execute S44; S5: Based on the numerical simulation results, compare the polarization curve and output power density curve of the proton exchange membrane fuel cell before and after optimization; and then determine whether the optimization is effective by calculating the net output power; S51: If the net power after optimization in S5 is greater than or equal to the net power after the previous optimization, the optimization is effective and ends; S52: If the net power after optimization in S5 is less than the net power after the previous optimization, the optimization is invalid and S47 is executed until the net power after optimization is greater than or equal to the net power after the previous optimization, and the optimization ends.

2. A method for optimizing the performance of a rotating proton exchange membrane fuel cell according to claim 1, characterized in that: In S1, when the structure of the proton exchange membrane fuel cell is geometrically symmetrical relative to the center of the disk, the three-dimensional structural model is a complete model or a 1 / n model relative to the center of the disk; when the structure of the proton exchange membrane fuel cell is asymmetrical relative to the center of the disk, the three-dimensional structural model is a complete model.

3. The method for optimizing the performance of a rotating proton exchange membrane fuel cell according to claim 1, characterized in that: In S1, the geometric model is grouped and established according to different components and boundary conditions of the proton exchange membrane fuel cell, and is segmented and associated according to the structural characteristics of the geometric model; the generation parameters of the geometric grid are set, the network model of the proton exchange membrane fuel cell is established, and the grid parameters are adjusted according to the network quality of the geometric model. After the network quality meets the simulation conditions, the grid is converted into a structured grid or an unstructured grid according to the calculation requirements.

4. The method for optimizing the performance of a rotating proton exchange membrane fuel cell according to claim 1, characterized in that: In S2, if the three-dimensional structural model is a complete proton exchange membrane fuel cell model, a no-slip wall boundary condition is set for the inner wall of the network model; if the three-dimensional structural model is a 1 / n proton exchange membrane fuel cell model relative to the center of the disk, a no-slip wall boundary condition is set for the inner wall of the network model, and a symmetric boundary condition is set for the proton exchange membrane fuel cell section.

5. The method for optimizing the performance of a rotating proton exchange membrane fuel cell according to claim 1, characterized in that: In S2, the boundary conditions include one or more of a mass flow inlet boundary condition, a pressure outlet boundary condition, a velocity inlet boundary condition, and a velocity outlet boundary condition.

6. The method for optimizing the performance of a rotating proton exchange membrane fuel cell according to claim 1, characterized in that: In said S2, by monitoring relevant variables such as the average current density on the surface of the anode and cathode plates of the proton exchange membrane fuel cell and the average oxygen concentration in the cathode diffusion layer; When the rate of change between two consecutive iterations is less than 0.01%, it can be considered that the convergence condition has been reached and the iterative calculation is terminated.

7. The method for optimizing the performance of a rotating proton exchange membrane fuel cell according to claim 1, characterized in that: In S2, the oxygen mass fraction at the interface between the cathode diffusion layer and the catalyst layer of the proton exchange membrane fuel cell is numerically sampled according to the grid points, and is calculated according to the following formula to obtain its oxygen distribution uniformity coefficient; Among them, U is the uniformity coefficient, the closer it is to 1, the more uniform the distribution is, and A is the effective surface area, cm 2 ;X i is the oxygen mass fraction at the i-th grid point; X A is the average mass fraction of oxygen on the surface.

8. The method for optimizing the performance of a rotating proton exchange membrane fuel cell according to claim 1, characterized in that: In S3 and S4, K can be set to any value between 0.8 and 0.95 according to actual needs, and used as a criterion for determining whether the optimization is completed.

9. The method for optimizing the performance of a rotating proton exchange membrane fuel cell according to claim 1, characterized in that: In S5, the calculation formula of the net output power is as follows: Among them, P net is the net output power, W; P FC is the output power, W; P P is the pumping work, W; P r is the power consumption of the rotating motor, W; I FC is the working current density, A·cm -2 ; V FC is the working voltage, V; ΔP is the pressure difference between the inlet and outlet of the flow channel, Pa; A inlet is the cross-sectional area of ​​the air inlet, cm 2 ;u inlet is the average velocity at the air inlet, m·s -1 ; T is the motor circumferential torque, N·m.

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