Fuel cell bipolar plate cooling flow field structure and fast optimization method

Abstract

The application discloses a fuel cell bipolar plate cooling flow field structure, comprising a heat exchange area, an inlet manifold and an outlet manifold, wherein a throttle structure is arranged on a main flow channel of the heat exchange area, and the throttle structure realizes contraction throttling by compressing a flow cross section, so as to avoid the non-uniformity of coolant flowing in the cooling flow field. The fuel cell bipolar plate cooling flow field structure has the throttle structure arranged on the main flow channel of the heat exchange area, the throttle structure of the heat exchange area can play a role of flow disturbance, increase the turbulence of the coolant flowing in the heat exchange area, improve the heat exchange effect and avoid local hot spots. The application further discloses a method for quickly optimizing a bipolar plate cooling flow field.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell technology. Specifically, this invention relates to a cooling flow field structure for a fuel cell bipolar plate and a rapid optimization method. Background Technology

[0002] Energy is the material foundation of human production and life, and the driving force of social development. With the increasing depletion of resources and environmental pollution faced by traditional energy sources, the development and utilization of clean energy is a common challenge for humanity and a crucial way to solve the fossil fuel crisis. Fuel cells are characterized by high conversion efficiency, low operating noise, low operating temperature, and pollution-free products. Based on the type of electrolyte, they can be classified into proton exchange membrane fuel cells, alkaline fuel cells, solid oxide fuel cells, and phosphoric acid fuel cells, among others. Proton exchange membrane fuel cells use a solid ion exchange membrane as their electrolyte, specifically an ion exchange membrane that allows hydrated hydrogen ions to pass through. Using hydrogen as fuel and oxygen from the air as an oxidant, they can operate within a temperature range of -40℃ to 95℃, and feature high volumetric power, long service life, and wide applicability. They are currently widely used in transportation, backup power, and other fields.

[0003] The power generation device stack of a proton exchange membrane fuel cell consists of bipolar plates, membrane electrode assemblies, current collectors, and encapsulation components. The bipolar plates, as the core component of the stack, primarily function to transport reactants and products, transfer heat, and conduct electrons. The chemical reactions in a proton exchange membrane fuel cell mainly include oxidation at the anode: H₂ → 2H⁺ + e⁻, and reduction at the cathode: O₂ + 4H⁺ → 2H₂O. Besides water (H₂O), the reaction products also generate heat. Typically, the rated operating voltage of a single unit in the stack is 0.6–0.75V, with a conversion efficiency of approximately 50%–65%. The remaining energy is the waste heat released from the electrochemical reactions. To maintain the internal temperature balance of the stack, especially when the heat dissipated through thermal radiation during high-power output is limited, an external coolant is needed to remove the waste heat from the stack.

[0004] A bipolar plate typically consists of two monopolar plates: an anode plate and a cathode plate. The anode plate has an anodic flow field for anodic gas flow, and similarly, the cathode plate has a cathode flow field for cathodic gas flow. Depending on the structural characteristics of the monopolar plates, a cooling flow field for coolant flow is located on the opposite side of either the anode or cathode plate. The two monopolar plates are joined using appropriate techniques based on their materials (e.g., metal bipolar plates are welded, while graphite bipolar plates are glued together) to ensure a closed cooling flow field. During operation, the circulating coolant ensures uniform operating temperature and prevents localized overheating that could affect the safety of the fuel cell stack. The cooling flow field consists of the inlet manifold, distribution zone, heat exchange zone, junction zone, and outlet manifold. Typically, the bipolar plate flow field has a rotationally symmetric structure; therefore, the inlet and outlet manifolds have the same structure, and the distribution and junction zones have the same structure.

[0005] In existing technologies, the cooling flow field of bipolar plates is less effective at delivering coolant compared to the anode and cathode flow fields due to limitations in the layout of the inlet and outlet manifolds. This is manifested in excessive flow resistance and poor distribution uniformity. Furthermore, the design of bipolar plate cooling flow fields often employs an empirical design followed by simulation analysis and optimization. The lack of mathematical calculations based on physical models in the initial design phase, relying solely on empirical design, leads to repeated calculations and iterations to arrive at the final cooling solution. This design optimization method requires multiple adjustments and computational optimizations, consuming significant time and economic resources. In addition, some existing technologies lack detailed explanations of simulation analysis methods or optimize simulation parameters merely to optimize the simulation model, rather than aiming at obtaining a final product, thus contradicting the essential purpose of simulation. Furthermore, some methods that do provide explanations perform overall calculations on a large model. In reality, during simulation, local structures already optimized to the target do not require further optimization. Continuing to use the overall model as the simulation object increases computing power, compresses development cycles, and hinders the rapid release of engineering products.

[0006] Chinese patent application number 202410484363.0 discloses a bipolar plate for a fuel cell, comprising an anode plate and a cathode plate stacked together. In the projection plane, the end projections of multiple main channels of any one plate lie within the projection of the distribution cavity of the other plate. The ends of the main channels of any one plate that are far from the distribution cavity of the other plate include at least two connected inclined sections. This invention increases the flow resistance of some main channels by adjusting the angle between the extension direction of each inclined section and a first direction to be less than or equal to 90°, and by sequentially increasing the angle between at least two inclined sections in the direction far from the distribution cavity of the other plate. This allows the distribution cavity to evenly distribute the cooling medium into the multiple main channels, preventing temperature differences in the bipolar plate during operation. However, the structure of this invention is relatively heavy, and the distribution cavities of the anode plate and cathode plate within the projection plane are not the same in shape and size. In order to achieve uniform distribution of the cooling medium into the main channel, a refined structural design is required. Furthermore, the multi-segment inclined scheme will increase the proportion of local flow resistance loss in the overall flow resistance composition, resulting in the cooling flow field only achieving uniform distribution under specific flow rates, and the structure has poor robustness.

[0007] Chinese patent application number 202121738409.5 discloses a bipolar plate flow field structure for a proton exchange membrane fuel cell. Regarding coolant flow, it employs an alternating lattice structure in the electrochemically active region of the bipolar plate to achieve uniform coolant flow velocity distribution, efficient heat dissipation, and stable operation of the proton exchange membrane fuel cell. The alternating lattice shapes include circular, rectangular, and irregular lattices. The irregular lattice adopts a streamlined design to minimize flow resistance. This utility model's alternating lattice structure design has been verified through computational fluid dynamics simulation and experiments, determining the optimal longitudinal spacing, transverse spacing, and lattice shape through optimized design. However, it does not provide specific details on the fluid dynamics simulation calculation methods, thus lacking process reliability.

[0008] Chinese Patent Application No. 202311436434.1 discloses a testing method and apparatus for the fluid distribution uniformity of a bipolar plate. The testing method includes: Step 1: Performing a flow-pressure drop experiment on the bipolar plate under test to obtain its flow-pressure drop curve; Step 2: Obtaining multiple actual flow data for multiple test channels based on the flow-pressure drop curve; Step 3: Simulating the bipolar plate under test to obtain a simulation model, performing simulation tests on the model to obtain multiple simulated flow data for multiple test simulated channels, and comparing the multiple actual flow data with the multiple simulated flow data to determine if the simulation model meets the requirements; Step 4: If the simulation model meets the requirements, obtaining the test result for the fluid distribution uniformity of the bipolar plate under test based on the simulation model. While this invention provides some explanation of fluid dynamics calculation simulation, it focuses on establishing the simulation model and verifying its accuracy through comparative testing. It has limited reference value for the design and optimization of the bipolar plate cooling flow field.

[0009] Chinese patent application number 202210459626.3 discloses a method for optimizing the flow channel design of a fuel cell bipolar plate, comprising: Step 1, determining the gas flow rate based on the current density and the active area of ​​the bipolar plate; Step 2, calculating the heat flow generated by the reaction based on the gas flow rate; Step 3, calculating the lower limit mass flow rate of the required cooling water based on the heat flow rate; Step 4, preliminary design of the flow channel dimensions; Step 5, calculating the cooling water pressure drop based on the flow channel dimensions; Step 6, if the cooling water pressure drop is within a set threshold range, the cooling effect meets the requirements, the flow channel dimensions are reasonably designed, further modeling and simulation are performed, and the flow channel dimensions are precisely optimized through accurate calculation; otherwise, return to Step 4. This invention details the optimization of bipolar plate flow channels using fluid dynamics simulation calculation methods. However, this method is based on existing bipolar plate flow channels, and the source of the flow channel parameters is not specifically explained in the early design stage. This design optimization method requires repeated iterative calculations to achieve the final goal. Moreover, the model used in the iteration process is a whole structure, without designing specific optimization steps for specific structures. This method of using a whole model for calculation simulation requires high computing power, has a long calculation iteration time, low efficiency, high economic cost, and is not conducive to engineering development.

[0010] A cooling flow field structure for a fuel cell bipolar plate is provided, particularly regarding how to increase the turbulence of the coolant flowing in the heat exchange zone to improve the heat exchange effect. Summary of the Invention

[0011] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention provides a cooling flow field structure for a fuel cell bipolar plate, the purpose of which is to increase the turbulence of the coolant flowing in the heat exchange zone and improve the heat exchange effect.

[0012] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a fuel cell bipolar plate cooling flow field structure, including a heat exchange zone, an inlet manifold and an outlet manifold, wherein a throttling structure is provided on the main flow channel of the heat exchange zone, and the throttling structure achieves contraction and throttling by compressing the flow cross section, which is used to avoid the non-uniformity of coolant flow in the cooling flow field.

[0013] The throttling structure is rhomboid or elliptical in shape.

[0014] The inlet manifold and outlet manifold are located at the center of the vertical direction of the electrode plates, so that when the coolant flows in the cooling flow field, the coolant flow path at the top and bottom has a longer flow path than the coolant flow path in the middle.

[0015] This invention also provides a method for rapidly optimizing the cooling flow field of a bipolar plate, comprising the following steps:

[0016] S1, Cooling flow field structure topology construction;

[0017] S2. Obtain the characteristic length distribution curve of the flow channel in the flow field region;

[0018] S3. Based on the one-dimensional flow resistance model, match the distribution of the throttling structure in the cooling flow field structure and establish the initial data model;

[0019] S4. In the initial data model, the cooling flow field fluid domain of the cooling flow field structure is extracted and divided into the coolant inlet region, coolant distribution region, coolant heat exchange region, coolant confluence region and coolant outlet region; then the coolant heat exchange region of the cooling flow field fluid domain is extracted as an independent data model to establish the heat exchange zone data model.

[0020] S5. Based on the heat exchange zone data model, calculate the flow resistance of the coolant heat exchange zone and determine whether the throttling structure meets the design target. If the throttling structure does not meet the target, return to the previous step; if the throttling structure meets the target, proceed to the next step.

[0021] S6. Based on the flow resistance calculation results of the coolant heat exchange region, establish a porous medium data model for the heat exchange region; based on the input porous medium data model for the heat exchange region, establish a simulation calculation model for the coolant distribution region and the coolant heat exchange region; perform flow resistance calculations for the coolant distribution region and the coolant heat exchange region, and determine whether the coolant distribution region and the coolant heat exchange region meet the design objectives. If the coolant distribution region and the coolant heat exchange region do not meet the design objectives, return to step S4; if the coolant distribution region and the coolant heat exchange region meet the design objectives, proceed to the next step.

[0022] S7. Establish a porous medium data model for the cooling flow field, check the uniformity of coolant distribution in the fuel cell stack, and iteratively adjust the model based on the check results until all design objectives are met.

[0023] Step S3 includes:

[0024] Calculate the heat generation of a single cell based on the power requirements of the fuel cell, and determine the required coolant volume flow rate.

[0025] Assuming that the distribution area and the merging area achieve ideal distribution results, calculate the flow characteristics of each main channel separately;

[0026] The flow characteristics of coolant in the main channel are determined by the Reynolds number Re.

[0027] The flow path is split into its characteristic lengths according to the main flow channel and the throttling structure, and then summed for calculation. The flow resistance of each flow path is calculated based on the pressure drop formula, and the distribution of the throttling structure is fitted.

[0028] The determination of coolant flow characteristics in the main channel by Reynolds number:

[0029] When Re≤2300, the flow characteristics of the coolant in the main flow channel are determined to be laminar flow;

[0030] When 2300 < Re < 10000, the flow characteristics of the coolant in the main flow channel are determined to be transitional flow;

[0031] When Re≥100000, the flow characteristics of the coolant in the main flow channel are determined to be turbulent.

[0032] The pressure drop formula Where v i l is velocity; f is the coefficient of friction, f = 64 / Re; i ρ is the characteristic length of each segment; D is the density of the coolant; i It is the hydraulic diameter.

[0033] When fitting the throttling structure distribution:

[0034] Preliminary theoretical calculations show that the throttling structure is a rhomboid structure.

[0035] By increasing the sample size of the flow traces for further fitting, the resulting throttling structure is an elliptical structure.

[0036] Step S7 includes:

[0037] The cooling flow field structure is equivalent to a porous medium data model of the cooling flow field.

[0038] The rationality of the cooling flow field structure is demonstrated from top to bottom by simulating the coolant distribution effect of the entire fuel cell stack. If there are defects in the cooling flow field structure, return to step S4 to optimize the heat exchange zone data model.

[0039] The fuel cell bipolar plate cooling flow field structure of the present invention sets a throttling structure in the main channel of the heat exchange zone. The throttling structure in the heat exchange zone can play a turbulence role, increase the turbulence of the coolant when it flows in the heat exchange zone, improve the heat exchange effect, and avoid local hot spots. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the throttling structure of the cooling flow field;

[0041] Figure 2 This is a schematic diagram of a bipolar plate structure;

[0042] Figure 3 This is a schematic diagram of the bipolar plate structure;

[0043] Figure 4 This is a schematic diagram of the cooling flow field structure;

[0044] Figure 5 This is a schematic diagram of the coolant flow.

[0045] Figure 6 This is a schematic diagram of the cooling flow field fluid domain;

[0046] Figure 7 This is a schematic diagram of the throttling region in the fluid domain;

[0047] Figure 8 This is a schematic diagram of the heat exchange zone model;

[0048] Figure 9 This is a schematic diagram of the equivalent model of the heat exchange zone;

[0049] Figure 10 This is a schematic diagram of the equivalent model of the cooling flow field region;

[0050] Figure 11 This is a schematic diagram of the equivalent model of coolant distribution in the fuel cell stack.

[0051] Figure 12 This is a flowchart of rapid design and optimization of bipolar plate cooling flow field;

[0052] Figure 13 It is a mass flow statistics chart;

[0053] Figure 14 It is a statistical chart of flow uniformity;

[0054] The labels in the above figures are as follows: 1-Bipolar plate; 2-Anode plate; 3-Cathode plate; 30-Cooling flow field structure; 31-Inlet manifold; 32-Distribution zone; 33-Heat exchange zone; 34-Confluence zone; 35-Outlet manifold; 331-Throttling structure; 332-Main flow channel; 4-Cooling flow field fluid domain; 41-Coolant inlet region; 42-Coolant distribution region; 43-Coolant heat exchange region; 44-Coolant confluence zone; 45-Coolant outlet region; 431-Coolant throttling region; 432-Coolant main flow channel region; 433-Porous media data model of heat exchange zone; 4321-Top coolant flow trajectory; 4322-Bottom coolant flow trajectory; 4323-Middle coolant flow trajectory; 5-Porous media data model of cooling flow field. Detailed Implementation

[0055] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, in order to help those skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solutions of the present invention, and to facilitate its implementation.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly associated with those skilled in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0057] Firstly, such as Figures 1 to 4 As shown, this embodiment of the invention provides a fuel cell bipolar plate cooling flow field structure 30, including an inlet manifold, a distribution area, a heat exchange area, a confluence area, and an outlet manifold. A throttling structure 331 is provided on the main flow channel of the heat exchange area. The throttling structure 331 achieves throttling by compressing the flow cross section.

[0058] Specifically, in this embodiment of the invention, the throttling structure 331 of the bipolar plate is located in the heat exchange zone. The throttling structure 331 in the heat exchange zone can have a turbulence-inducing effect, increasing the turbulence of the coolant flowing in the heat exchange zone, improving the heat exchange effect, and avoiding local hot spots. Moreover, the throttling structure 331 of the bipolar plate is located in the heat exchange zone, which can reduce the complexity of the cold field design compared to throttling in the distribution zone, while providing a certain guarantee for the accuracy of theoretical calculations. A structure close to the final product form can be obtained in the initial data model stage. The throttling structure 331 in the heat exchange zone can also have a turbulence-inducing effect, increasing the turbulence of the coolant flowing in the heat exchange zone, improving the heat exchange effect, and avoiding local hot spots.

[0059] In embodiments of the present invention, such as Figures 1 to 4As shown, the bipolar plates, serving as the framework of the fuel cell stack, support the membrane electrode assembly, transport fluid, and dissipate reaction heat. They mainly consist of an anode plate 2 and a cathode plate 3. To dissipate the heat generated by the reaction, a cooling flow field structure 30 is typically provided between the anode plate 2 and the cathode plate 3 to facilitate the removal of residual heat. In the cooling flow field structure 30, a distribution zone distributes the coolant flowing in from the inlet manifold to the heat exchange zone. A confluence zone collects the coolant from the heat exchange zone and collects it at the outlet manifold. The various components of the cooling flow field are connected by specific channels to form the coolant flow path.

[0060] like Figures 1 to 4 As shown, the distribution area and the confluence area are located between the inlet manifold and the outlet manifold, and the heat exchange area is located between the distribution area and the confluence area. A throttling structure 331 is set in the main flow channel of the heat exchange area, and the coolant flows along the main flow channel. A top coolant flow path 4321, a bottom coolant flow path 4322, and a middle coolant flow path 4323 are formed in the heat exchange area. The middle coolant flow path 4323 is located between the top coolant flow path 4321 and the bottom coolant flow path 4322. The lengths of the top coolant flow path 4321 and the bottom coolant flow path 4322 are greater than the length of the middle coolant flow path 4323.

[0061] Since the inlet manifold and outlet manifold are located at the center of the vertical direction of the electrode plates, when the coolant flows in the cooling flow field structure 30, the top coolant flow path 4321 and the bottom coolant flow path 4322 have a longer flow path than the middle coolant flow path 4323. This results in the top coolant flow path 4321 and the bottom coolant flow path 4322 having a larger flow resistance than the middle coolant flow path 4323. The coolant tends to flow closer to the middle coolant flow path 4323. Ultimately, the mass flow rate is large at the center of the cooling flow field structure 30 and small at both ends, resulting in uneven heat dissipation. Therefore, in order to avoid the non-uniformity of coolant flow in the cooling flow field structure 30, in this embodiment of the invention, a throttling structure 331 is provided on the main flow channel 332 of the cooling flow field structure 30. The coolant entering the main flow channel 332 flows through the throttling structure 331. The throttling structure 331 achieves the effect of contraction and throttling by compressing the flow cross section, which is used to avoid the non-uniformity of coolant flow in the cooling flow field. The throttling structure 331 has a rhomboid or elliptical structure.

[0062] Secondly, such as Figure 12 As shown, this embodiment of the invention provides a method for rapidly optimizing the cooling flow field of a bipolar plate, comprising the following steps:

[0063] S1, Cooling flow field structure 30 topology construction;

[0064] S2. Obtain the characteristic length distribution curve of the flow channel in the flow field region;

[0065] S3. Based on the one-dimensional flow resistance model, match the distribution of the throttling structure 331 in the cooling flow field structure 30, and establish the initial data model;

[0066] S4. In the initial data model, the cooling flow field fluid domain of the cooling flow field structure 30 is extracted and divided into the coolant inlet region, coolant distribution region, coolant heat exchange region, coolant confluence region and coolant outlet region; then the coolant heat exchange region of the cooling flow field fluid domain is extracted as an independent data model to establish the heat exchange zone data model.

[0067] S5. Based on the heat exchange zone data model, calculate the flow resistance of the coolant heat exchange zone and determine whether the throttling structure 331 meets the design target. If the throttling structure 331 does not meet the target, return to the previous step; if the throttling structure 331 meets the target, proceed to the next step.

[0068] S6. Based on the flow resistance calculation results of the coolant heat exchange region, establish a porous medium data model for the heat exchange region; based on the input porous medium data model for the heat exchange region, establish a simulation calculation model for the coolant distribution region and the coolant heat exchange region; perform flow resistance calculations for the coolant distribution region and the coolant heat exchange region, and determine whether the coolant distribution region and the coolant heat exchange region meet the design objectives. If the coolant distribution region and the coolant heat exchange region do not meet the design objectives, return to step S4; if the coolant distribution region and the coolant heat exchange region meet the design objectives, proceed to the next step.

[0069] S7. Establish a porous medium data model for the cooling flow field, check the uniformity of coolant distribution in the fuel cell stack, and iteratively adjust the model based on the check results until all design objectives are met.

[0070] To address the shortcomings of existing technologies, such as the lack of physical models and mathematical calculations in the early design stages for bipolar plate cooling flow fields, which rely solely on empirical design and require repeated calculations and iterations to arrive at the final freezing solution, resulting in significant time and economic costs, and the increased computational demands due to unclear simulation methods and overly complex simulation data models, which compress development cycles and hinder rapid product release, this invention proposes a rapid optimization method for bipolar plate cooling flow fields.

[0071] Specifically, regarding the bipolar plate cooling flow field structure 30 provided in this embodiment of the invention, the throttling structure 331 of the bipolar plate is located in the heat exchange zone. Compared with the throttling in the distribution zone, this reduces the complexity of the cooling field design and provides a certain guarantee for the accuracy of theoretical calculations. A structure close to the final product form can be obtained in the initial data model stage. The throttling structure 331 in the heat exchange zone also has a turbulence effect, increasing the turbulence of the coolant flowing in the heat exchange zone, improving the heat exchange effect, and avoiding local hot spots. This embodiment of the invention also provides a method for rapidly optimizing the bipolar plate cooling flow field:

[0072] First, the topology of the structure is constructed based on the coolant inlet and outlet manifold positions of the bipolar plate, thereby obtaining the characteristic length distribution curve of the flow field channel. The distribution of the throttling structure 331 in the flow field is matched using a one-dimensional flow resistance model, completing the theoretical calculations in the early stage of design and creating the data model. Second, the heat exchange zone of the bipolar plate is used as an independent model to simulate the flow characteristics of the heat exchange zone and analyze whether the throttling effect achieves the goal of the same flow resistance. Then, the heat exchange zone is equivalent to a flow resistance model, and the flow characteristics of the distribution zone and the confluence zone are calculated to examine the flow resistance and distribution uniformity of the distribution zone and the flow resistance and confluence uniformity of the confluence zone. Finally, the entire flow field is equivalent to a flow resistance model to check the uniformity of coolant distribution throughout the entire stack until all optimization objectives are achieved, completing the rapid optimization design of the bipolar plate cooling flow field structure 30.

[0073] This method uses a one-dimensional flow resistance model for theoretical calculations during the initial product design phase, improving the accuracy of the initial data model and making it closer to the final product form, thus saving significant time in later optimization stages. Furthermore, this method employs a goal-based multi-step optimization approach, dividing the data model into functional blocks for targeted simulation optimization. Small and large models are rationally configured according to computational requirements, simplifying calculations while reducing the amount of computational data, significantly lowering the computational power requirements, enabling rapid simulation, improving computational convergence, and saving time costs in project development. This design optimization method is simple, reliable, highly practical, and can be executed in a streamlined manner, making it suitable for widespread application in fuel cell bipolar plate cooling channels.

[0074] In step S1 above, based on the bipolar plate coolant inlet and outlet manifold positions as the starting and constraint benchmarks for topology construction, the connection relationships and layout framework of each functional area of ​​the cooling flow field structure 30 (such as the inlet manifold, distribution area, heat exchange area, confluence area and outlet manifold) are planned, the initial flow field structure topology "skeleton" is built, the general direction of the flow channel and the regional division are clarified, and the topology construction is completed.

[0075] In step S2 above, based on the topologically constructed cooling flow field structure 30, coolant flow traces are defined and extracted at different positions of the electrode plates (top, bottom, and middle). The length of each extracted flow trace is measured as the characteristic length of the corresponding flow channel. For example, the length values ​​of the flow traces at the top, bottom, and middle are obtained separately, and the characteristic length distribution curve of the flow field region is fitted to reflect the distribution law of the characteristic length of the flow channel at different positions, providing a basis for subsequent one-dimensional flow resistance model calculations.

[0076] In this embodiment of the invention, step S3 includes:

[0077] Calculate the heat generation of a single cell based on the power requirements of the fuel cell, and determine the required coolant volume flow rate.

[0078] Assuming that the distribution area and the merging area achieve ideal distribution results, calculate the flow characteristics of each main channel separately;

[0079] The flow characteristics of coolant in the main channel are determined by the Reynolds number Re.

[0080] The flow path is split into the characteristic lengths of the main channel and the throttling structure 331 and then summed. The flow resistance of each flow path is calculated based on the pressure drop formula. The pressure drop (pressure loss ΔP) of each flow path is calculated and the distribution of the throttling structure 331 is fitted.

[0081] In this embodiment of the invention, in step S3 above, the flow characteristics of the coolant in the main channel are determined by the Reynolds number Re:

[0082] When Re≤2300, the flow characteristics of the coolant in the main flow channel are determined to be laminar flow;

[0083] When 2300 < Re < 10000, the flow characteristics of the coolant in the main flow channel are determined to be transitional flow;

[0084] When Re≥100000, the flow characteristics of the coolant in the main flow channel are determined to be turbulent.

[0085] In this embodiment of the invention, the flow path includes a top coolant flow path 4321, a middle coolant flow path 4323, and a bottom coolant flow path 4322. In step S3 above, the pressure drop ΔP of each flow path is calculated according to the following formula, and the total pressure drop is obtained by summing them up:

[0086]

[0087] Among them, v i l is velocity; f is the coefficient of friction, f = 64 / Re; iρ represents the characteristic length of each flow path segment (e.g., the length of the top coolant flow path, the middle coolant flow path, and the bottom coolant flow path); ρ is the density of the coolant; D i It is the hydraulic diameter.

[0088] In this embodiment of the invention, during step S3 above, when fitting the distribution of the throttling structure 331:

[0089] Preliminary theoretical calculations show that the throttling structure 331 is a rhomboid structure.

[0090] By increasing the sample size of the flow traces for further fitting, the resulting throttling structure 331 is an elliptical structure.

[0091] To calculate the dimensional parameters of the throttling structure 331, this invention uses a one-dimensional flow resistance model for theoretical calculation, as follows: First, the heat generation of a single cell is calculated based on the power requirements of the fuel cell, thereby obtaining the required coolant volume flow rate for a single cell. Since one of the design goals of the cooling flow field structure 30 is that the coolant can flow uniformly in each main channel 332, it is assumed that the distribution and return effects of the distribution area and the confluence area reach the target value, and the flow characteristics of each main channel 332 are calculated separately.

[0092] In theoretical calculations, the flow characteristics of the coolant in the main flow channel are first determined by the Reynolds number: when Re ≤ 2300, the flow is laminar; when 2300 < Re < 10000, the flow is transitional; and when Re ≥ 100000, the flow is turbulent. The flow velocity of the fuel cell coolant is typically between 0.5 m / s and 2.5 m / s, and the flow interface of the main flow channel 332 is 0.2 mm. 2 ~0.5mm 2 The characteristic length is within 300mm. In this example, the characteristic length is obtained based on the lengths of the top coolant flow path 4321, the bottom coolant flow path 4322, and the middle coolant flow path 4323. When more characteristic lengths are needed, the flow paths can be extracted in the same way, and then the characteristic lengths can be measured. The flow of fuel cell coolant is mostly laminar. This example uses laminar flow to illustrate the theoretical calculation method. The flow path is divided according to the characteristic lengths of the main channel 332 and the throttling structure 331 and then summed for calculation. The pressure drop ΔP is calculated according to the formula. Based on the goal of equal ΔP, the flow resistance of the top coolant flow path 4321, the bottom coolant flow path 4322, and the middle coolant flow path 4323 is calculated respectively to obtain the required length of the throttling structure 331 for each segment. Thus, the distribution of the throttling structure 331 in the cooling flow field is fitted, and the preliminary theoretical calculation is completed. At this time, the distribution of the throttling structure 331 on the cooling flow field structure 30 is a rhomboid structure.

[0093] To more accurately calculate the length of the throttling structure 331, flow traces can be further extracted from the top coolant flow trace 4321, the middle coolant flow trace 4323, the bottom coolant flow trace 4322, and the middle coolant flow trace 4323. This increases the sample size and allows for a more precise fitting of the throttling structure 331. The resulting throttling structure 331 is distributed in an elliptical shape on the cooling flow field structure 30. This completes the theoretical calculations for the initial design phase and establishes the data model.

[0094] In this embodiment of the invention, after the data model is created in step S4, the cooling flow field fluid domain 4 of the cooling flow field structure 30 is extracted and divided into functional areas: coolant inlet region 41, coolant distribution region 42, coolant heat exchange region 43, coolant confluence region 44, and coolant outlet region 45, as follows. Figure 6 As shown. Finally, the coolant heat transfer region 43 of the cooling flow field fluid domain 4 is extracted as an independent data model.

[0095] In this embodiment of the invention, in step S5 above, the flow resistance of the coolant heat exchange region 43 is calculated. This calculation is used to further evaluate whether the throttling structure 331 meets the design target. If the throttling structure 331 does not meet the design target, the process returns to the previous step S4 to adjust the data model.

[0096] In this embodiment of the invention, after the throttling structure 331 meets the design target, in step S6 above, a porous medium data model 433 for the heat exchange zone is created based on the calculation results. The porous medium data model 433 for the heat exchange zone is used as the boundary input to the next step of the calculation of the coolant distribution region 42 and the coolant heat exchange region 43. Based on the input porous medium data model 433 for the heat exchange zone, a simulation calculation model of the coolant distribution region 42 and the coolant heat exchange region 43 is established. Through the calculation in this step, it is used to evaluate whether the coolant distribution region 42 and the coolant heat exchange region 43 meet the design target. If the coolant distribution region 42 and the coolant heat exchange region 43 do not meet the design target, the process returns to step S4 to adjust the data model. After adjustment, the flow resistance calculation of the cooling flow field fluid domain 4 in step S5 is skipped, and the flow characteristics calculation of the coolant distribution region 42 and the coolant heat exchange region 43 is performed directly.

[0097] In this embodiment of the invention, step S7 includes:

[0098] The cooling flow field structure 30 is equivalent to a porous medium data model of the cooling flow field.

[0099] The rationality of the cooling flow field structure 30 is demonstrated from top to bottom by simulating the coolant distribution effect of the entire fuel cell stack. If the cooling flow field structure 30 has defects, the process returns to step S4 to optimize the heat exchange zone data model.

[0100] In this embodiment of the invention, since the heat exchange zone is equivalent to a porous medium data model 433 of the heat exchange zone by multiple main channels 332, its data structure is reduced, which greatly reduces the computational resources required for mesh creation and physical model solving, and allows for rapid optimization design of the coolant distribution region 42 and the coolant heat exchange region 43. Using the same method, the cooling flow field structure 30 is equivalent to a porous medium data model 5 of the cooling flow field. The rationality of the cooling flow field structure 30 is further demonstrated from top to bottom by simulating the coolant distribution effect of the entire fuel cell stack. If there are defects in the structure, the process returns to step S4 to perform simulation calculations of the coolant distribution region 42 and the coolant heat exchange region 43 to optimize the data model. If the cooling flow field structure 30 achieves the design goal, the design optimization process ends, and the data model is frozen.

[0101] The fluid flow characteristics obtained using the above method are as follows: Figure 13 Mass flow statistics chart and Figure 14 As shown in the flow uniformity chart, the overall coolant flow is high near the middle coolant flow path 4323, and near the top coolant flow path 4321 and the bottom coolant flow path 4322. At the edges, due to their proximity to the boundary, natural convection with the air can remove some heat. The center, being farther from the boundary, has higher heat levels, and a larger flow rate ultimately achieves uniform heat dissipation. Furthermore, the flow deviation is controlled within 6%, indicating good performance.

[0102] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A bipolar plate cooling flow field structure for a fuel cell, comprising a heat exchange zone, an inlet manifold, and an outlet manifold, characterized in that, A throttling structure is provided on the main flow channel of the heat exchange zone, which achieves throttling by compressing the flow cross section.

2. The fuel cell bipolar plate cooling flow field structure according to claim 1, characterized in that, The throttling structure is rhomboid or elliptical in shape.

3. The fuel cell bipolar plate cooling flow field structure according to claim 1, characterized in that, The inlet manifold and outlet manifold are located at the center of the vertical direction of the electrode plates, so that when the coolant flows in the cooling flow field, the coolant flow path at the top and bottom has a longer flow path than the coolant flow path in the middle.

4. A method for rapidly optimizing the cooling flow field of a bipolar plate, characterized in that, Including the following steps: S1, Cooling flow field structure topology construction; S2. Obtain the characteristic length distribution curve of the flow channel in the flow field region; S3. Based on the one-dimensional flow resistance model, match the distribution of the throttling structure in the cooling flow field structure and establish the initial data model; S4. In the initial data model, the cooling flow field fluid domain of the cooling flow field structure is extracted and divided into the coolant inlet region, coolant distribution region, coolant heat exchange region, coolant confluence region and coolant outlet region; then the coolant heat exchange region of the cooling flow field fluid domain is extracted as an independent data model to establish the heat exchange zone data model. S5. Based on the heat exchange zone data model, calculate the flow resistance of the coolant heat exchange zone and determine whether the throttling structure meets the design target. If the throttling structure does not meet the target, return to the previous step; if the throttling structure meets the target, proceed to the next step. S6. Based on the flow resistance calculation results of the coolant heat exchange region, establish a porous medium data model for the heat exchange region; based on the input porous medium data model for the heat exchange region, establish a simulation calculation model for the coolant distribution region and the coolant heat exchange region; perform flow resistance calculations for the coolant distribution region and the coolant heat exchange region, and determine whether the coolant distribution region and the coolant heat exchange region meet the design objectives. If the coolant distribution region and the coolant heat exchange region do not meet the design objectives, return to step S4; if the coolant distribution region and the coolant heat exchange region meet the design objectives, proceed to the next step. S7. Establish a porous medium data model for the cooling flow field, check the uniformity of coolant distribution in the fuel cell stack, and iteratively adjust the model based on the check results until all design objectives are met.

5. The method for rapidly optimizing the cooling flow field of a bipolar plate according to claim 4, characterized in that, Step S3 includes: Calculate the heat generation of a single cell based on the power requirements of the fuel cell, and determine the required coolant volume flow rate. Assuming that the distribution area and the merging area achieve ideal distribution results, calculate the flow characteristics of each main channel separately; The flow characteristics of coolant in the main channel are determined by the Reynolds number Re. The flow path is split into its characteristic lengths according to the main flow channel and the throttling structure, and then summed for calculation. The flow resistance of each flow path is calculated based on the pressure drop formula, and the distribution of the throttling structure is fitted.

6. The method for rapidly optimizing the cooling flow field of a bipolar plate according to claim 5, characterized in that, The determination of coolant flow characteristics in the main channel by Reynolds number: When Re≤2300, the flow characteristics of the coolant in the main flow channel are determined to be laminar flow; When 2300 < Re < 10000, the flow characteristics of the coolant in the main flow channel are determined to be transitional flow; When Re≥100000, the flow characteristics of the coolant in the main flow channel are determined to be turbulent.

7. The method for rapidly optimizing the cooling flow field of a bipolar plate according to claim 5, characterized in that, The pressure drop formula Where v i l is velocity; f is the coefficient of friction, f = 64 / Re; i ρ is the characteristic length of each segment; ρ is the density of the coolant; D i It is the hydraulic diameter.

8. The method for rapidly optimizing the cooling flow field of a bipolar plate according to claim 5, characterized in that, When fitting the throttling structure distribution: Preliminary theoretical calculations show that the throttling structure is a rhomboid structure. By increasing the sample size of the flow traces for further fitting, the resulting throttling structure is an elliptical structure.

9. The method for rapidly optimizing the cooling flow field of a bipolar plate according to any one of claims 5 to 8, characterized in that, Step S7 includes: The cooling flow field structure is equivalent to a porous medium data model of the cooling flow field. The rationality of the cooling flow field structure is demonstrated from top to bottom by simulating the coolant distribution effect of the entire fuel cell stack. If there are defects in the cooling flow field structure, return to step S4 to optimize the heat exchange zone data model.

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