Bipolar plate cooling plate and design method thereof

Abstract

The invention discloses a bipolar plate cooling plate and a design method thereof, and the bipolar plate cooling plate comprises a bipolar plate which comprises a cathode plate and an anode plate, and the cathode plate and the anode plate are enclosed to form the bipolar plate; the cooling flow field is formed between the cathode plate and the anode plate; the cooling flow field comprises primary flow areas located on the two sides and a secondary flow area located near the middle. The primary flow area is of a branch structure; the secondary flow area is of a parallel structure, and a coolant is controlled to uniformly flow in a cooling flow field through the refined flow passage cross section size, so that efficient heat exchange is realized, proper temperature conditions during reaction are provided, and the power generation efficiency of the fuel cell stack is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen fuel cells, and in particular relates to a bipolar plate cooling plate and a design method thereof. Background Art

[0002] In the process of implementing the present invention, the inventors discovered that the prior art has at least the following problems:

[0003] As a key approach to achieving carbon neutrality and carbon peak targets, the development and utilization of clean energy is an important means to resolve the fossil energy crisis. Hydrogen fuel cells have the advantages of high energy conversion efficiency, stable power output, green environmental protection, zero emissions, and low noise. They are an energy conversion technology that uses hydrogen as fuel gas. In order to achieve the conversion of chemical energy into electrical energy and provide various conditions for the reaction to occur, the specific energy conversion device of the hydrogen fuel cell is a fuel cell stack. The fuel cell stack mainly consists of two parts: bipolar plates and membrane electrodes. The bipolar plates play the role of transporting gas, collecting current, conducting heat, and supporting structures. The membrane electrode provides a place for chemical reactions to occur, and it plays the role of catalyzing reactions and conducting protons. The fuel cell stack generates heat while generating electricity.

[0004] In the prior art, plate cooling flow fields primarily include serpentine and parallel flow fields. Serpentine flow fields offer superior flow characteristics, facilitating uniform coolant delivery and avoiding dead zones. However, their high flow resistance can increase cooling water pump power consumption, reducing system efficiency. Furthermore, the large inlet / outlet pressure differential inevitably leads to high coolant pressure on one side, potentially causing coolant leakage and posing risks to stack safety and stability. Parallel flow fields effectively address the high flow resistance of serpentine flow fields. They are typically used in conjunction with a distribution zone: coolant flows through the coolant inlet, is distributed through the inlet distribution zone, and then enters the cooling flow field. Due to their unforced flow characteristics, coolant flow characteristics vary within each flow channel, leading to uneven distribution. This can result in poor stack performance and localized hot spots during stack operation, which can easily burn out the membrane electrode, leading to poor stack durability and even safety incidents. Additionally, some bipolar plate flow field structures with specialized structures exist, but these generally have limited application scenarios, high molding quality, and high manufacturing costs, making them unsuitable for engineering applications. In addition, the structure of the cooling flow field is currently mostly designed based on qualitative experience. How to quickly iterate the design of the cooling flow field, improve cooling performance, and shorten the development cycle is also a current problem.

[0005] For example, a patent for a metal bipolar plate with a convective coolant flow field (publication number 104900886A, publication date 2015-09-09) provides a metal bipolar plate with a convective coolant flow field: it is composed of a hydrogen plate and an oxygen plate that are relatively superimposed, bonded or welded with the coolant flow channel surface, the coolant inlet and the coolant outlet are located in the middle of the two ends of the hydrogen plate and the oxygen plate, the coolant inlets of the hydrogen plate and the oxygen plate are connected, and the coolant outlets of the hydrogen plate and the oxygen plate are connected; the hydrogen plate and the oxygen plate are stamped with a coolant inlet, a coolant outlet and a coolant flow channel with an S-shaped serpentine direction, and a centrally symmetrical hydrogen plate coolant flow channel and an oxygen plate coolant flow channel are formed between the hydrogen plate and the oxygen plate. This invention uses a YSY type flow field structure to ensure the flow uniformity of the coolant in the cooling flow field. However, due to the repeated bending of the flow channel in the flow field, the along-the-line resistance and local resistance of the coolant when flowing in the flow field are greatly increased, and the pressure drop is increased, which leads to an increase in the power consumption of the external water pump that drives the coolant flow, indirectly resulting in a decrease in the efficiency of the fuel cell system.

[0006] For example, the patented fuel cell bipolar plate cooling flow field structure (publication number CN 108155400 A, publication date 2017-12-29) provides a fuel cell bipolar plate cooling flow field structure: its anode and cathode plates are both graphite plates, with a coolant inlet and outlet, and a flow channel connecting the coolant inlet and outlet. The flow channel consists of an inlet transition cooling flow channel, a coolant main flow channel, and an outlet transition cooling flow channel connected in sequence. The inlet transition cooling flow channel and the outlet transition cooling flow channel adopt an arc-shaped structure with a high center and a low outside to achieve uniform distribution of the fluid. This structure can achieve uniform distribution of the coolant in the cooling flow field with low flow resistance loss. However, the structure is in the form of an arc surface with a high center and a low outside. Due to the characteristics of graphite, the arc transition surface is difficult to process, which is not conducive to molding quality and production cost.

[0007] For example, a patent for a fuel cell bipolar plate cooling flow field structure (publication number CN 219286457 U, publication date 2023-02-04) provides a fuel cell bipolar plate cooling flow field structure: it consists of a coolant inlet manifold and a coolant outlet manifold, a main cooling flow field flow channel, and an inlet and outlet distribution flow channel. One end of the main cooling flow field flow channel is connected to the inlet distribution area flow channel through the inlet distribution area flow channel, and the other end is connected to the outlet distribution area flow channel through the outlet distribution area flow channel. The cooling fluid is transmitted from the inlet manifold through the inlet distribution area flow channel, the main cooling flow field flow channel, and the outlet distribution area flow channel to the outlet manifold and flows out. This bipolar plate cooling flow field structure can also evenly distribute the coolant under low resistance conditions, but its coolant inlet manifold and coolant outlet manifold occupy too large an area, which makes the area utilization of the bipolar plate low, thereby reducing the volume power density of the fuel cell stack.

[0008] For example, a patent for a fuel cell cooling flow field plate (publication number CN 110247076 A, publication date 2019-05-25) provides a fuel cell cooling flow field plate: the outer wall of the cooling flow field plate is circular, and an outer ring of the flow field plate is arranged on the periphery. The upper and lower sides of the flow field plate are respectively arranged with a variable diameter inlet flow channel and a variable diameter outlet flow channel to avoid the negative pressure caused by the backflow of the coolant at the outlet. A cylindrical cooling flow channel is arranged in the cooling flow field plate so that the coolant is evenly distributed in various positions in the flow channel. The cooling flow field plate can make the heat exchange between the coolant and the bipolar plate more uniform and the flow resistance is lower. However, the cooling flow field is a circular structure. In engineering, due to limitations such as installation conditions, the usual bipolar plate shape is mostly a rectangular structure. The circular structure is not conducive to the expansion of usage scenarios. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a bipolar plate cooling plate and a design method thereof, which controls the uniform flow of coolant in the cooling flow field by refining the flow channel cross-sectional dimensions, thereby achieving efficient heat exchange and providing suitable temperature conditions for the reaction to occur, thereby improving the efficiency of the fuel cell stack when generating electricity.

[0010] In order to solve the above technical problems, the technical solution adopted by the present invention is: a bipolar plate cooling plate having:

[0011] A bipolar plate, comprising a cathode plate and an anode plate, wherein the cathode plate and the anode plate form a bipolar plate;

[0012] A cooling flow field is formed between the cathode plate and the anode plate;

[0013] The cooling flow field includes primary flow areas located on both sides and a secondary flow area located near the middle;

[0014] The primary flow region is a branched structure; the secondary flow region is a parallel structure.

[0015] The primary flow region includes an inlet primary flow region located at the inlet and an outlet primary flow region located at the outlet. The inlet primary flow region is a centrally symmetrical structure with the outlet primary flow region.

[0016] The secondary flow area includes a plurality of block areas, and each block area includes a plurality of flow channels parallel to each other.

[0017] The plurality of divided areas are evenly distributed in the direction perpendicular to the coolant flow.

[0018] The bipolar plates are further provided with an inlet manifold and an outlet manifold on both sides; the inlet primary flow region diverts the coolant introduced from the plate inlet manifold to the secondary flow region, and then converges the coolant to the outlet manifold through the outlet primary flow region.

[0019] The above-mentioned design method of the bipolar plate cooling plate includes the following steps:

[0020] 1) Determine the initial flow field structure;

[0021] 2) Calculation of initial flow field flow characteristics;

[0022] 3) Optimization of resistance along the way;

[0023] 4) Calculation of flow characteristics after optimization of flow resistance;

[0024] 5) Local resistance optimization;

[0025] 6) Calculation of flow characteristics after local resistance optimization;

[0026] 7) The target flow field structure is frozen.

[0027] In the above step 1), a data model of the initial bipolar plate cooling flow field is established using CAD three-dimensional modeling software. This model includes the basic characteristics of the cooling flow field. In the above step 2), the data model is imported into CFD fluid simulation calculation software to calculate the flow field characteristics of the initial bipolar plate cooling flow field. The results are imported into data processing software, and after processing, the mass flow rate and uniformity parameters of each flow channel in the flow field are obtained.

[0028] In the above step 3), based on the flow field characteristic diagram of the initial bipolar plate cooling flow field, the cross-section of the flow channel with poor uniformity is adjusted in the CAD three-dimensional modeling software, and the effect of one round of optimization is achieved by optimizing the along-line resistance loss; the optimization direction includes the plane direction - that is, the flow channel width direction; in the above step 4), after the round of optimization is completed, the data model after the along-line resistance optimization is imported into the CFD fluid simulation calculation software, and the flow field characteristics of the bipolar plate cooling flow field after the along-line resistance optimization are calculated, and the results are imported into the data processing software. After processing, the mass flow rate and uniformity parameters of each flow channel in the flow field are obtained.

[0029] In step 5) above, based on the flow characteristic diagram of the cooling flow field after the along-line resistance is optimized, the turning angle or radius of the flow channel with poor uniformity is adjusted in the CAD three-dimensional modeling software, and a second round of optimization is achieved by optimizing the local resistance loss.

[0030] In step 6) above, after the two rounds of optimization are completed, the data model after the optimized along-line resistance is imported into the CFD fluid simulation calculation software, and the flow field characteristics of the bipolar plate cooling flow field after the local resistance optimization are calculated. The results are imported into the data processing software, and after processing, the mass flow rate and uniformity parameters of each flow channel in the flow field are obtained to finally determine whether the target requirements are met.

[0031] One of the above technical solutions has the following advantages or beneficial effects: by refining the flow cross-sectional dimensions of the flow channel, the coolant is controlled to flow uniformly in the cooling flow field, thereby achieving efficient heat exchange and providing suitable temperature conditions for the reaction to occur, thereby improving the efficiency of the fuel cell stack when generating electricity. At the same time, the cooling flow field adopts a technical solution that is conducive to engineering implementation, and can complete the processing and production of the bipolar plate cooling flow field at low cost and high controllability. The bipolar plate cooling flow field adopts a closed-loop design method of flow channel topology design, empirical structure optimization, numerical calculation optimization, and final data freezing to complete the complete design of the refined flow channel, quickly perform design optimization, improve the cooling performance of the cooling flow field, and shorten the development cycle. In the above manner, a low-resistance, uniform-flow bipolar plate cooling flow field structure can be developed at low cost and high efficiency to provide cooling for the fuel cell stack and improve the performance and reliability of the stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic structural diagram of a bipolar plate cooling plate provided in an embodiment of the present invention;

[0033] Figure 2 for Figure 1 A schematic structural diagram of a bipolar plate cooling plate;

[0034] Figure 3 for Figure 1 A schematic structural diagram of a bipolar plate cooling plate;

[0035] Figure 4 for Figure 1 A schematic structural diagram of a bipolar plate cooling plate;

[0036] Figure 5 for Figure 1 A schematic structural diagram of a bipolar plate cooling plate;

[0037] Figure 6 for Figure 1 A schematic structural diagram of a bipolar plate cooling plate;

[0038] Figure 7 for Figure 1 A schematic structural diagram of a bipolar plate cooling plate;

[0039] Figure 8 for Figure 1 Schematic diagram of the design method of the bipolar plate cooling plate;

[0040] The marks in the above figures are: 1. bipolar plate, 11. cathode plate, 12. anode plate, 2. cooling flow field, 21. primary flow area, 211. inlet primary flow area, 212. outlet primary flow area, 22. secondary flow area, 221. blocking area, 222. flow channel, 2221. flow channel width, 2222. flow channel turning radius, 23. inlet manifold, 24. outlet manifold. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 making creative efforts are within the scope of protection of the present invention.

[0042] Example 1

[0043] The actual output voltage of the battery is: According to the thermodynamic Nernst equation: And the reaction kinetic equation: It can be seen that temperature has a huge impact on the performance and efficiency of the fuel cell stack. In order to ensure continuous operation, the temperature of the stack needs to be maintained at a constant and uniform level.

[0044] According to the cooling method, the cooling method of the fuel cell stack can be divided into air cooling and liquid cooling according to the power density and application. At present, the air cooling solution is generally suitable for small-power stacks. It simplifies the water pump, humidification, and air compressor systems, and uses the fan to dissipate heat and supply oxygen through the structural design of the special flow channel. Compared with the air cooling solution, the bipolar plate heat dissipation effect of the liquid cooling solution is more stable and more efficient, and is suitable for medium and high power stacks. Liquid cooling generally uses a circulating coolant to dissipate heat. On one side of the bipolar plate is an air flow field, and on the other side is a hydrogen flow field. There is an interlayer flow field between the two flow fields for the circulation of the coolant, thereby achieving a cooling effect. At present, the application scenarios of fuel cell vehicles are gradually locked in the field of long-distance and heavy-load applications. Therefore, the demand for liquid-cooled stacks is gradually increasing, and the demand for the cooling structure of the bipolar plate is also more stringent.

[0045] When the coolant flows in the cooling flow field, the main losses are along-the-line loss and local loss. During the coolant flow process, the head loss caused by the friction resistance generated by the blockage of the flow channel is the along-the-line loss. It is proportional to the length of the flow path and inversely proportional to the hydraulic diameter of the flow channel. The calculation formula is: When the coolant changes direction, the flow velocity and direction change, and the local energy loss caused is called the along-the-line loss. It is related to parameters such as the flow area and the turning radius. The calculation formula is: A good cooling flow field needs to balance the along-the-line loss and local loss of the matching flow channel while taking into account the cooling requirements of the fuel cell stack, and ultimately obtain a cooling flow field structure that meets the requirements.

[0046] See also Figures 1 to 8 A bipolar plate 1 cooling plate comprises: a bipolar plate 1, which includes a cathode plate 11 and an anode plate 12, the cathode plate 11 and the anode plate 12 enclosing the bipolar plate 1; a cooling flow field 2, formed between the cathode plate 11 and the anode plate 12; the cooling flow field 2 includes a primary flow region 21 located on both sides and a secondary flow region 22 located near the middle; the primary flow region 21 is a branching structure; and the secondary flow region 22 is a parallel structure. The basic form of the flow field is a combination of the primary flow region 21 and the secondary flow region 22. The primary flow region 21 is a forked structure, and this form of flow field has the basic characteristics of uniform fluid distribution and low flow resistance. The primary flow region 21 is divided into an inlet primary flow region 21211 and an outlet primary flow region 21212, and is a rotationally symmetrical structure; the secondary flow region 22 is a parallel structure, consisting of a plurality of block regions 221 with similar structures, each block region 221 being composed of flow channels of different cross-sections, arranged in sequence perpendicular to the flow of the coolant. The inlet primary flow region 21211 diverts the coolant introduced from the plate inlet manifold 23 to the secondary flow region 22, where it absorbs heat generated in the active reaction area of ​​the bipolar plate 1 through heat exchange. The coolant is then directed to the outlet manifold 24 through the outlet primary flow region 21212. After being cooled by the external cooling components, the coolant re-enters the cooling flow field 2 through the inlet manifold 23, completing a heat exchange cycle.

[0047] The primary flow region 21 includes an inlet primary flow region 21211 at the inlet and an outlet primary flow region 21212 at the outlet. The inlet primary flow region 21211 is centrally symmetrical with the outlet primary flow region 21212. The secondary flow region 22 includes multiple block regions 221, each of which includes multiple parallel flow channels. The multiple block regions 221 are evenly distributed perpendicular to the coolant flow direction. Inlet manifolds 23 and outlet manifolds 24 are also provided on both sides of the bipolar plate 1. The inlet primary flow region 21211 diverts the coolant introduced by the plate inlet manifold 23 to the secondary flow region 22, and then converges the coolant through the outlet primary flow region 21212 to the outlet manifold 24. The basic form of this flow field is a bifurcated + parallel structure. Through refined flow channel cross-sectional dimensions, the coolant is controlled to flow uniformly in the cooling flow field 2, thereby achieving efficient heat exchange and providing suitable temperature conditions for the reaction to occur, thereby improving the efficiency of the fuel cell stack during power generation. At the same time, the cooling flow field 2 adopts a technical solution that is conducive to engineering implementation, which can complete the processing and production of the bipolar plate 1 cooling flow field 2 at low cost and high controllability. The bipolar plate 1 cooling flow field 2 adopts a closed-loop design method of flow channel topology design, empirical structural optimization, numerical calculation optimization, and final data freezing to complete the complete design of the refined flow channel, quickly perform design optimization, improve the cooling performance of the cooling flow field 2, and shorten the development cycle. Through the above methods, a low-flow resistance, uniform flow bipolar plate 1 cooling flow field 2 structure can be developed at low cost and high efficiency to provide cooling for the fuel cell stack and improve the performance and reliability of the stack.

[0048] Example 2

[0049] A design method for a bipolar plate cooling plate comprises the following steps: 1) determining an initial flow field structure; 2) calculating flow characteristics of the initial flow field; 3) optimizing along-line resistance; 4) calculating flow characteristics after optimizing along-line resistance; 5) optimizing local resistance; 6) calculating flow characteristics after optimizing local resistance; and 7) freezing a target flow field structure.

[0050] In step 1), CAD 3D modeling software was used to create an initial data model of the bipolar plate cooling flow field. This model encompasses the basic characteristics of the cooling flow field. This data model facilitates data exchange and, subsequently, importing it into CFD fluid simulation software, supporting discretization and facilitating rapid data processing.

[0051] In step 2) above, the data model is imported into the CFD fluid simulation calculation software to calculate the flow field characteristics of the initial bipolar plate cooling flow field, and the results are imported into the data processing software. After processing, the mass flow rate and uniformity parameters of each flow channel in the flow field are obtained. Through the analysis and processing of the mass flow rate and uniformity parameters, the single flow channel with poor uniformity is identified, and the target is determined for the next step of the process structure, which facilitates rapid improvement.

[0052] In step 3) above, based on the flow field characteristic diagram of the initial bipolar plate cooling flow field, the cross-section of the flow channel with poor uniformity is adjusted in the CAD three-dimensional modeling software, and the effect of a round of optimization is achieved by optimizing the resistance loss along the process; the optimization direction includes the plane direction - that is, the flow channel width direction. By adjusting the flow channel width, the fluid flow characteristics are changed, thereby playing a throttling role and improving the flow uniformity between the flow channels.

[0053] In the above step 4), after the wheel optimization is completed, the data model after the along-line resistance optimization is imported into the CFD fluid simulation calculation software, and the flow field characteristics of the bipolar plate cooling flow field after the along-line resistance optimization are calculated. The results are imported into the data processing software, and after processing, the mass flow rate and uniformity parameters of each flow channel in the flow field are obtained. Through further analysis and processing of the mass flow rate and uniformity parameters, the single flow channel with poor uniformity is identified in the flow field after the preliminary optimization, so as to determine the target for the next step of local structure optimization, so as to facilitate rapid improvement.

[0054] In the above step 5), according to the flow characteristic diagram of the cooling flow field after the optimization of the resistance along the flow path, the turning angle or radius of the flow channel with poor uniformity is adjusted in the CAD three-dimensional modeling software, and the two-round optimization is achieved by optimizing the local resistance loss. The adjustment of the flow channel turning angle or radius changes the fluid flow characteristics, thereby playing a throttling role and improving the flow uniformity between the flow channels.

[0055] In step 6) above, after the two rounds of optimization are completed, the data model after the optimized along-line resistance is imported into the CFD fluid simulation calculation software, and the flow field characteristics of the bipolar plate cooling flow field after the local resistance optimization are calculated. The results are imported into the data processing software, and after processing, the mass flow and uniformity parameters of each flow channel in the flow field are obtained, and finally it is judged whether the target requirements are met. After two rounds of structural optimization, a flow field structure that meets the mass flow and uniformity requirements is finally obtained. This flow field is applied to the fuel cell bipolar plate to provide an efficient cooling effect when the fuel cell is generating electricity, thereby ensuring the stable operation of the fuel cell.

[0056] In actual operation, multiple rounds of optimization may be required. These optimizations may also require alternating the order of along-the-line resistance and local resistance, but they basically follow the above optimization process.

[0057] The basic form of this flow field is a fork + parallel structure. By refining the flow cross-sectional dimensions of the flow channel, the coolant is controlled to flow uniformly in the cooling flow field, thereby achieving efficient heat exchange and providing suitable temperature conditions for the reaction to occur, thereby improving the efficiency of the fuel cell stack when generating electricity. At the same time, the cooling flow field adopts a technical solution that is conducive to engineering implementation, and can complete the processing and production of the bipolar plate cooling flow field at low cost and high controllability. The bipolar plate cooling flow field adopts a closed-loop design method of flow channel topology design, empirical structure optimization, numerical calculation optimization, and final data freezing to complete the complete design of the refined flow channel, quickly perform design optimization, improve the cooling performance of the cooling flow field, and shorten the development cycle. Through the above methods, a low-resistance, uniform-flow bipolar plate cooling flow field structure can be developed at low cost and high efficiency to provide cooling for the fuel cell stack and improve the performance and reliability of the stack.

[0058] Example 3

[0059] To solve the problem in the prior art that the serpentine flow field resistance is too large and tends to increase the power consumption of the cooling water pump, thereby reducing the efficiency of the system. At the same time, due to the excessive pressure difference between the inlet and outlet, the coolant pressure on one side will inevitably be too high, causing the coolant to leak out, and there are certain risks to the safety and stability of the operation of the battery stack. Due to the non-forced flow characteristics of the parallel flow field, the flow characteristics of the coolant in each flow channel have certain differences, which is prone to uneven distribution. The performance of the battery stack is therefore poor, and due to the occurrence of local hot spots during the operation of the battery stack, the membrane electrode is easily burned, resulting in poor durability of the battery stack and even causing safety accidents. The bipolar plate flow field structure with an irregular structure usually has fewer usage scenarios, high molding quality and production cost, which is not conducive to engineering applications. At this stage, the structure of the cooling flow field mostly relies on qualitative design based on experience. How to quickly iterate the design of the cooling flow field, improve cooling performance, and shorten the development cycle is also a current problem. The present invention provides a bipolar plate cooling flow field and an optimization method thereof.

[0060] Specifically, the bipolar plate cooling flow field 2 is located between the bipolar plates 1, with the cathode plate 11 and the anode plate 12 on either side. The basic form of the cooling flow field 2 is a combination of a primary flow region 21 and a secondary flow region 22. The primary flow region 21 is a bifurcated structure. This type of flow field has the basic characteristics of uniform fluid distribution and low flow resistance. The primary flow region 21 is composed of an inlet primary flow region 211 and an outlet primary flow region 212, and is a rotationally symmetrical structure; the secondary flow region 22 is a parallel structure, consisting of multiple block regions 221 with similar structures. Each block region 221 is composed of flow channels 222 of different cross-sections, arranged in sequence perpendicular to the coolant flow direction. The inlet primary flow region 211 diverts the coolant introduced by the plate inlet manifold 23 to the secondary flow region 22, absorbs the heat generated in the bipolar plate active reaction area through heat exchange, and then converges the coolant to the outlet manifold 24 through the outlet primary flow region 212. After being cooled by the external cooling components, the coolant enters the cooling flow field 2 again through the inlet manifold, completing a heat exchange cycle.

[0061] In order to ensure that the coolant is more evenly distributed in the flow field, the present invention proposes a bipolar plate cooling flow field optimization method. The stack generates heat while generating electricity. The actual output voltage of the battery is: According to the thermodynamic Nernst equation: And the reaction kinetic equation: It can be seen that: temperature has a huge impact on the performance and efficiency of the fuel cell stack. In order to ensure continuous operation, the temperature of the stack needs to be maintained at a constant and uniform level. In order to meet the timely discharge of waste heat from the stack during power generation, a cooling flow field 2 for cooling is provided between the bipolar plates 1. After decomposing the heat dissipation requirements of the stack by theoretical calculation, the heat dissipation requirements of the single bipolar plate 1 are matched, and the CAD three-dimensional modeling software is used to establish the data model of the initial bipolar plate 1 cooling flow field 2. This model contains the basic characteristics of the cooling flow field 2; secondly, the data model is imported into the CFD fluid simulation calculation software to calculate the flow field characteristics of the initial bipolar plate cooling flow field, and the results are imported into the data processing software. After processing, the mass flow rate and uniformity parameters of each flow channel in the flow field are obtained. By Figure 3 The initial flow field flow characteristics diagram shows that the flow channels within each block have similar flow characteristics. The mass flow rate is highest in channel 11, and lowest in channel 5. Uniformity analysis shows that the uniformity deviation for channel 11 is 15.16%, while the uniformity deviation for channel 5 is -10.58%. This does not meet the cooling flow field uniformity target (≤5%), and the deviation is significant. The primary head loss generated by the coolant during flow is along-the-line loss, with a value of: Along-the-line loss is the head loss caused by the friction resistance due to the obstruction of the flow channel. It is proportional to the length of the process and inversely proportional to the hydraulic diameter of the flow channel. It is the main head loss, so it is taken as the main optimization factor for the first round of optimization. According to the flow field characteristic diagram of the initial bipolar plate cooling flow field, the cross-section of the flow channel with poor uniformity is adjusted in the CAD three-dimensional modeling software. Because the flow channels in each block area have similar flow characteristics, the flow channels in each block area are adjusted according to certain cross-sectional coefficients λ1, λ2, λ3, λ4, and λ5 according to the similar characteristics of the block area. The effect of one round of optimization is achieved by optimizing the along-the-line resistance loss. At the same time, in order to ensure the feasibility of processing and manufacturing, adjustments are mainly made in the plane direction (i.e., the flow channel width). After a round of optimization is completed, the data model after the along-the-line resistance optimization is imported into the CFD fluid simulation calculation software, and the flow field characteristics of the bipolar plate cooling flow field after the along-the-line resistance optimization are calculated. The results are imported into the data processing software, and the mass flow rate and uniformity parameters of each flow channel in the flow field are obtained after processing. By Figure 5 The flow characteristics of the cooling flow field after the optimization of the flow resistance along the cooling flow field show that after one round of optimization, the mass flow of the cooling flow field flow channel numbered 11 and the flow channel numbered 5 has improved significantly. The new highest mass flow rate is located in the cooling flow field flow channel numbered 10, and the lowest mass flow rate is located in the cooling flow field flow channel numbered 1. Through uniformity analysis, the uniformity deviation of the flow channel numbered 10 is 7.14%; the uniformity deviation of the flow channel numbered 1 is -7.61%. After one round of optimization, the flow uniformity of the cooling flow field has improved compared to the initial flow field (the uniformity has been optimized from about 15% to about 7%), but it still does not meet the uniformity target of the cooling flow field, and the deviation value is close (≤5%). The secondary head loss generated by the coolant during the flow process is a local loss, and its value is: Local loss is a secondary head loss, so it is taken as the secondary optimization factor for the second round of optimization. According to the flow characteristic diagram of the cooling flow field after the optimization of the along-line resistance, the turning angle / radius of the flow channel with poor uniformity is adjusted in the CAD three-dimensional modeling software. Because the flow channels in each block area have similar flow characteristics, the fillets in each block area are adjusted according to certain size coefficients η1, η2, η3, η4, η5, and η6 based on the block area as a similar feature. The effect of the second round of optimization is achieved by optimizing the local resistance loss. After the second round of optimization is completed, the data model after the optimization of the along-line resistance is imported into the CFD fluid simulation calculation software, and the flow field characteristics of the bipolar plate cooling flow field after the local resistance optimization are calculated. The results are imported into the data processing software. After processing, the mass flow rate and uniformity parameters of each flow channel in the flow field are obtained, and finally it is determined whether the target requirements are met. After the second round of optimization is completed, the data model after the optimized resistance along the way is imported into the CFD fluid simulation calculation software to calculate the flow field characteristics of the bipolar plate cooling flow field after the local resistance optimization. The results are imported into the data processing software to obtain the mass flow and uniformity parameters of each flow channel in the flow field after processing, and finally determine whether the target requirements are met. Figure 7 The flow characteristics of the cooling flow field after local resistance optimization show that after one round of optimization, the mass flow rate of channels 10 and 1 in the cooling flow field has improved significantly. The new highest mass flow rate is located in channels 10 and 11, and the lowest mass flow rate is located in channel 3. Uniformity analysis shows that the uniformity deviation of channels 10 and 11 is 3.39%; the uniformity deviation of channel 3 is -3.78%. Compared with the initial flow field, the cooling flow field after the second round of optimization meets the cooling flow field uniformity target of ≤5%, and the cooling flow field optimization is complete.

[0062] In actual operation, multiple rounds of optimization may be required. These optimizations may also require alternating the order of along-the-line resistance and local resistance, but they basically follow the above optimization process.

[0063] After adopting the above scheme, the coolant is controlled to flow uniformly in the cooling flow field through the refined flow cross-sectional dimensions of the flow channel, thereby achieving efficient heat exchange and providing suitable temperature conditions for the reaction to occur, thereby improving the efficiency of the fuel cell stack when generating electricity. At the same time, the cooling flow field adopts a technical solution that is conducive to engineering implementation, and can complete the processing and production of the bipolar plate cooling flow field at low cost and high controllability. The bipolar plate cooling flow field adopts a closed-loop design method of flow channel topology design, empirical structure optimization, numerical calculation optimization, and final data freezing to complete the complete design of the refined flow channel, quickly perform design optimization, improve the cooling performance of the cooling flow field, and shorten the development cycle. Through the above methods, a low-resistance, uniform-flow bipolar plate cooling flow field structure can be developed at low cost and high efficiency to provide cooling for the fuel cell stack and improve the performance and reliability of the stack.

[0064] In the description of the present invention, it should be understood that the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inside", "front", "center", "both ends", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0065] In the present invention, unless otherwise clearly stipulated and limited, the terms "install", "set", "connect", "fix", "screw" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, ordinary technicians in this field can understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0066] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A bipolar plate cooling plate, characterized in that: have: A bipolar plate, comprising a cathode plate and an anode plate, wherein the cathode plate and the anode plate form a bipolar plate; A cooling flow field is formed between the cathode plate and the anode plate; The cooling flow field includes primary flow areas located on both sides and a secondary flow area located near the middle; The primary flow region is a branched structure; the secondary flow region is a parallel structure.

2. The bipolar plate cooling plate according to claim 1, wherein: The primary flow region includes an inlet primary flow region located at the inlet and an outlet primary flow region located at the outlet. The inlet primary flow region is a centrally symmetrical structure with the outlet primary flow region.

3. The bipolar plate cooling plate according to claim 2, wherein: The secondary flow area includes a plurality of block areas, and each block area includes a plurality of flow channels parallel to each other.

4. The bipolar plate cooling plate according to claim 3, wherein: The plurality of divided areas are evenly distributed in the direction perpendicular to the coolant flow.

5. The bipolar plate cooling plate according to claim 4, characterized in that: The bipolar plates are further provided with an inlet manifold and an outlet manifold on both sides; the inlet primary flow region diverts the coolant introduced from the plate inlet manifold to the secondary flow region, and then converges the coolant to the outlet manifold through the outlet primary flow region.

6. The method for designing a bipolar plate cooling plate according to claim 5, wherein: The steps include: 1) Determine the initial flow field structure; 2) Calculation of initial flow field flow characteristics; 3) Optimization of resistance along the way; 4) Calculation of flow characteristics after optimization of flow resistance; 5) Local resistance optimization; 6) Calculation of flow characteristics after local resistance optimization; 7) The target flow field structure is frozen.

7. The method for designing a bipolar plate cooling plate according to claim 6, wherein: In the above step 1), a data model of the initial bipolar plate cooling flow field is established using CAD three-dimensional modeling software. This model includes the basic characteristics of the cooling flow field. In the above step 2), the data model is imported into CFD fluid simulation calculation software to calculate the flow field characteristics of the initial bipolar plate cooling flow field. The results are imported into data processing software, and after processing, the mass flow rate and uniformity parameters of each flow channel in the flow field are obtained.

8. The method for designing a bipolar plate cooling plate according to claim 7, wherein: In the above step 3), based on the flow field characteristic diagram of the initial bipolar plate cooling flow field, the cross-section of the flow channel with poor uniformity is adjusted in the CAD three-dimensional modeling software, and the effect of one round of optimization is achieved by optimizing the along-line resistance loss; the optimization direction includes the plane direction - that is, the flow channel width direction; in the above step 4), after the round of optimization is completed, the data model after the along-line resistance optimization is imported into the CFD fluid simulation calculation software, and the flow field characteristics of the bipolar plate cooling flow field after the along-line resistance optimization are calculated, and the results are imported into the data processing software. After processing, the mass flow rate and uniformity parameters of each flow channel in the flow field are obtained.

9. The method for designing a bipolar plate cooling plate according to claim 8, wherein: In step 5) above, based on the flow characteristic diagram of the cooling flow field after the along-line resistance is optimized, the turning angle or radius of the flow channel with poor uniformity is adjusted in the CAD three-dimensional modeling software, and a second round of optimization is achieved by optimizing the local resistance loss.

10. The method for designing a bipolar plate cooling plate according to claim 9, wherein: In step 6) above, after the two rounds of optimization are completed, the data model after the optimized along-line resistance is imported into the CFD fluid simulation calculation software, and the flow field characteristics of the bipolar plate cooling flow field after the local resistance optimization are calculated. The results are imported into the data processing software, and after processing, the mass flow rate and uniformity parameters of each flow channel in the flow field are obtained to finally determine whether the target requirements are met.

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