A gradient dot matrix distribution area of a fuel cell flow field

Abstract

This invention provides a gradient lattice distribution region for a fuel cell flow field, belonging to the field of fuel cell technology. The distribution region is located in the inlet and outlet distribution region of the bipolar plate flow field and includes several through holes with the same depth as the main flow channel, arranged alternately with a blind lattice in the direction perpendicular to the fluid inlet. The blind lattice is composed of blind holes with a depth less than that of the main flow channel. The blind lattice includes at least forward blind holes and reverse blind holes with open ends communicating with the positive and negative sides of the flow field, respectively, with adjacent columns alternating. This invention allows for localized bypass or overflow of fluid. The alternating arrangement of these two types in the vertical direction forms periodic strong and weak blocking regions before the fluid enters the main flow channel, causing the gas to undergo multiple bypass, overflow, and pressure redistribution in the distribution direction, preventing gas from concentrating in local low-resistance paths, thereby improving the uniformity of flow distribution in the main flow channel.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and more specifically to a gradient lattice distribution region for a fuel cell flow field. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) are power generation devices that directly convert the chemical energy of hydrogen and air into electrical energy. Their reaction products are only water and heat, offering significant advantages such as being pollution-free, highly efficient, and low-noise. Against the backdrop of the booming development of the artificial intelligence industry and the rapid increase in computing power demand, fuel cells have received widespread attention as a stable and continuous power supply solution.

[0003] Bipolar plates are one of the core components of fuel cells, accounting for the majority of the stack's volume and weight. Beyond their function of conducting electrons and heat, the flow field created by their surface processing determines the transport paths and distribution of reactant gases and product water (or coolant). A well-designed flow field ensures that reactants are uniformly delivered to the catalyst surface and that generated liquid water is promptly discharged, directly impacting the cell's output performance and lifespan.

[0004] Flow fields are typically divided into two main functional regions: the main flow zone and the distribution zone. The main flow zone consists of a series of parallel or intersecting channels and serves as the main channel for the transport of the reaction medium. The distribution zone, located at the inlet and outlet of the flow field, acts as a distribution center, its core task being to efficiently and uniformly introduce gas or liquid from external pipelines into the various channels of the main flow zone. Therefore, the design quality of the distribution zone plays a decisive role in the performance of the entire flow field.

[0005] Lattice structures are widely used as flow guiding elements in distribution zones due to their simplicity, ease of fabrication, and ability to generate some flow disturbance. In conventional lattice distribution zone designs, all lattice elements typically employ uniform geometric dimensions, especially ensuring their depth matches the depth of the main flow channel. This design reveals significant drawbacks in practical applications. First, because the lattice depth is uniform, the fluid transport path in the distribution zone exhibits a clear preference: paths closer to the inlet have lower flow resistance and thus receive the majority of the fluid distribution, while areas farther from the inlet experience insufficient flow, resulting in extremely uneven fluid distribution across the entire flow field. This unevenness directly leads to insufficient reactant gas in some areas and flooding in others, severely limiting the battery's performance output.

[0006] Secondly, the uniform-sized lattice design lacks the ability to actively regulate fluid flow in localized areas. When fluid enters the wide distribution zone from a narrow inlet pipe, it experiences a violent high-speed impact, followed by rapid deceleration and diffusion. During this process, the fluid's kinetic energy is dissipated disorderly rather than being effectively utilized for lateral diffusion and pressure equalization. Furthermore, due to the lack of structural guidance, the fluid transport velocity within the distribution zone is generally low, prolonging the time it takes for reactants to reach the mainstream region and reducing the efficiency of the electrochemical reaction.

[0007] To alleviate the problem of uneven fluid distribution, some existing technologies attempt to optimize the flow field by changing the density or arrangement of the lattice. For example, a denser lattice is placed near the inlet to increase local drag, or a sparser lattice is placed far from the inlet to reduce drag. However, these approaches often only focus on flow resistance adjustment in the planar direction, neglecting the three-dimensional flow potential in the depth direction of the flow field. The fluid still mainly flows around in a two-dimensional plane, unable to form effective crossflow and reattachment processes, so its improvement on distribution uniformity is limited, and usually comes at the cost of sacrificing inlet and outlet pressure drops (i.e., energy efficiency).

[0008] Even more challenging is that in the outlet distribution region of the flow field, the water generated by the reaction tends to accumulate on the side walls and at corners. Traditional lattice structures lack targeted drainage designs, leading to liquid water retention, which can cause flooding in severe cases, blocking the reactive gas channels and causing a sharp decline in battery performance.

[0009] In summary, designing a novel distribution zone structure that can improve fluid distribution uniformity, maintain high transmission efficiency, and also take into account drainage capacity is a technical challenge that urgently needs to be solved in the field of bipolar plate flow field design for fuel cells. Summary of the Invention

[0010] To address the shortcomings of existing technologies, this invention provides a gradient lattice distribution region for the flow field of a fuel cell. This region consists of an alternating arrangement of blind lattices and through lattices perpendicular to the inlet direction. The through lattice forms a strong physical barrier to the gas, providing strong kinetic energy, while the blind lattice's barrier effect is relatively weak, allowing for localized bypass or overflow. This alternating arrangement of the two in the vertical direction creates periodic strong and weak barrier zones before the fluid enters the main flow path. This causes the gas to undergo multiple bypasses, overflows, and pressure redistributions in the distribution direction, preventing gas from concentrating in local low-resistance paths and thus improving the uniformity of flow distribution in the main flow path.

[0011] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0012] A gradient lattice distribution region for a fuel cell flow field is provided, wherein a through lattice for guiding flow is provided in the inlet distribution region and / or outlet distribution region of the fuel cell bipolar plate flow field, the through lattice comprising a plurality of through holes with the same depth as the mainstream flow channel, characterized in that, in the direction perpendicular to the fluid inlet, the through lattice and the blind lattice are distributed in an alternating manner; the blind lattice is composed of a plurality of blind holes disposed at the intervals between adjacent through holes, the depth of the blind holes being less than the depth of the mainstream flow channel.

[0013] Furthermore, the blind spot array includes forward blind holes and reverse blind holes with opposite closing directions; wherein, a forward blind spot array is composed of a number of forward blind holes, and the open end of the forward blind hole is connected to the front of the flow field; a reverse blind spot array is composed of a number of reverse blind holes, and the open end of the reverse blind hole is connected to the back of the flow field.

[0014] Furthermore, the cross-sectional shape of the through hole and the blind hole can be any one of the following: circular, triangular, square, or elliptical.

[0015] Furthermore, the depth of the blind hole does not exceed 1 / 2 of the depth of the through hole, and the cross-sectional area of ​​the blind hole is 0.6 to 0.85 times the cross-sectional area of ​​the through hole.

[0016] Furthermore, in the direction perpendicular to the fluid inlet, the distance S1 between adjacent through holes and blind holes is 1–2 mm; in the direction parallel to the fluid inlet, the distance S2 between adjacent through holes is smaller than the distance S between adjacent blind holes. 22 .

[0017] Furthermore, in the direction perpendicular to the fluid inlet, if the nth column of the blind spot lattice is a positive blind spot lattice, then the (n+1)th column of the blind spot lattice is a negative blind spot lattice, such that the open ends of the blind spot lattices of adjacent columns are in opposite directions.

[0018] Furthermore, along the fluid flow direction, the depth and / or cross-sectional area of ​​the forward blind holes in the forward blind lattice gradually change; the depth and / or cross-sectional area of ​​the reverse blind holes in the reverse blind lattice gradually change.

[0019] Furthermore, a row of lattice micro-body is provided on the side wall of the distribution area near the flow field inlet and / or flow field outlet (10), the lattice micro-body being arranged in sequence by side wall through-holes, side wall forward blind hole holes and side wall reverse blind hole holes.

[0020] Furthermore, the cross-sectional area of ​​the through-hole in the sidewall is 15% to 25% of the cross-sectional area of ​​the through-hole; the cross-sectional area of ​​the forward blind hole and the reverse blind hole in the sidewall is 15% to 20% of the cross-sectional area of ​​the blind hole in the blind dot matrix; the depth of the forward blind hole and the reverse blind hole in the sidewall is the same as the depth of the blind hole.

[0021] Furthermore, the distance between the lattice microparticles and the sidewall is 0.1–0.2 mm, the parallel distance between the lattice microparticles and the first column of the main lattice is 1–1.5 mm, and the distance between the lattice microparticles and the inlet and outlet regions of the flow field is 1–3 mm.

[0022] The beneficial effects of this invention are as follows:

[0023] 1. The gradient lattice distribution region of the fuel cell flow field described in this invention forms a flow resistance compensation mechanism by alternating the through lattice and blind lattice in the direction perpendicular to the fluid inlet. This results in higher flow resistance in areas with larger gas flow (such as the area directly opposite the inlet) and relatively lower resistance in areas with smaller flow (such as the edge area). This guides the fluid to spontaneously diffuse from the high-pressure area to the low-pressure area, significantly improving the uniformity of fluid distribution in the distribution region and overcoming the drawback of the traditional uniform depth lattice structure where the fluid preferentially flows along the low-resistance path.

[0024] 2. The gradient lattice distribution zone of the fuel cell flow field described in this invention, by setting blind lattices with a depth less than that of the main flow channel and alternating them with the through lattice, allows the fluid to flow beyond the plane around the lattice, instead of being confined to flow around the lattice on both sides. This creates a three-dimensional composite flow that combines flow around, flow beyond, and reattachment processes. This three-dimensional flow effectively enhances the lateral diffusion and pressure equalization capabilities of the gas within the distribution zone. Simultaneously, through multiple local accelerations and decelerations, it increases the transport speed of the medium entering the main flow channel, shortens the time it takes for reactants to reach the battery reaction area, and thus improves the electrochemical reaction efficiency.

[0025] 3. The gradient lattice distribution region of the fuel cell flow field described in this invention, by setting the blind lattice as a positive blind lattice and a reverse blind lattice with opposite open end directions, and making the open end directions of adjacent columns of blind lattice opposite, forces the fluid to generate alternating crossflow and three-dimensional disturbance in the direction perpendicular to the overall flow field. This design avoids the fluid being concentrated and transported to one side or in one direction of the flow field, further enhancing the material exchange in the thickness direction of the flow field, so that the gas undergoes a more thorough and uniform redistribution process before reaching the mainstream region.

[0026] 4. The gradient lattice distribution zone of the fuel cell flow field described in this invention, by employing a gradient design with both depth and cross-sectional area smaller than the main lattice, allows the fluid medium to undergo continuous local expansion and contraction within the distribution zone, gradually consuming the high-speed impact kinetic energy carried upon entry from the flow field inlet. This, on the one hand, allows the gas to enter the mainstream region in a smoother and more uniform initial state, which is beneficial for extending the service life of battery components such as the membrane electrode assembly; on the other hand, it avoids energy loss caused by severe impact and expansion, achieving a good balance between distribution uniformity and energy efficiency.

[0027] 5. The gradient lattice distribution region of the fuel cell flow field described in this invention generates a higher local velocity gradient and shear force near the wall surface by setting a row of lattice micro-body structures composed of through-holes and blind micro-holes on the sidewall of the distribution region near the flow field inlet and outlet, combined with the same lattice design in the outlet distribution region. This high shear force helps reduce the adhesion time of the product liquid water on the wall surface, accelerates the discharge rate of liquid water from the outlet distribution region, effectively prevents flooding inside the battery, and improves the operational stability of the fuel cell at higher current densities.

[0028] 6. The gradient lattice distribution region of the fuel cell flow field described in this invention, through the gradual structure of blind holes set along the fluid flow direction, makes the flow resistance in the distribution region no longer constant along the flow direction, but forms a designable gradual flow resistance distribution. When only one side of the blind hole (forward or reverse) exhibits a gradual change, this single-sided gradual design can compensate for the pressure loss along the fluid path, using a larger obstruction in the inlet region to facilitate rapid lateral diffusion of the fluid, and a smaller obstruction in the outlet region to promote smoother entry of the fluid into each main channel, thereby improving the distribution uniformity along the flow direction. When both the forward and reverse blind holes adopt a gradual design and the changing trends are opposite, a flow-over effect along the flow direction is further introduced, forcing the fluid to generate continuous exchange and mixing in the thickness direction of the flow field. Experiments show that the fluid distribution uniformity coefficient of the double-sided reverse gradual scheme is better than that of the single-sided gradual scheme, providing a better technical means for achieving higher precision flow field distribution control. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are some embodiments of the present invention. For those skilled in the art, it is obvious that other drawings can be obtained from these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the gradient lattice distribution region of the fuel cell flow field described in this invention.

[0031] Figure 2 This is a partially enlarged view of the gradient lattice distribution region of the fuel cell flow field described in this invention.

[0032] Figure 3 for Figure 2 A sectional view.

[0033] Figure 4 This is a magnified view of a portion of the lattice micro-body on the sidewall described in this invention.

[0034] Figure 5This is a schematic diagram showing the depth variation of the lattice micro-volumes on the sidewall.

[0035] Figure 6 This is a schematic diagram of the dot matrix distribution area for comparison.

[0036] Figure 7 This is a comparison diagram of the uniformity coefficient of fluid distribution in the flow field in Embodiment 1 and the comparative example of the present invention.

[0037] Figure 8 This is a comparison diagram of the flow field pressure drop in Embodiment 1 and the comparative example of the present invention.

[0038] Figure 9 This is a comparison diagram of the uniformity coefficient of fluid distribution in the flow field in Embodiment 4 of the present invention and the comparative example.

[0039] Figure 10 This is a comparison diagram of the flow field pressure drop in Embodiment 4 and the comparative example of the present invention.

[0040] In the picture:

[0041] 1-Through-through lattice; 1-1-Through-through hole; 2-Forward blind lattice; 2-1-Forward blind hole; 3-Reverse blind lattice; 3-1-Reverse blind hole; 4-Inlet distribution area; 5-Flow field inlet; 6-Sidewall through-through micropore; 7-Sidewall forward blind hole; 8-Sidewall reverse blind hole; 9-Outlet distribution area; 10-Flow field outlet. Detailed Implementation

[0042] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0043] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "axial," "radial," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0044] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0045] The gradient lattice distribution region of the fuel cell flow field described in this invention is used for the bipolar plate of a proton exchange membrane fuel cell, as described in the prior art. Figure 6 As shown, a through-matrix 1 is provided in the inlet distribution area 4 and the outlet distribution area 9 respectively. This design leads to uneven fluid distribution and low transmission efficiency. Therefore, as Figure 1 As shown, the present invention includes a blind spot array 2 perpendicular to the fluid inlet direction; the blind spot array 2 and the through-hole array 1 are arranged alternately; the blind spot array 2 is composed of several blind holes disposed at intervals between adjacent through-holes 1-1, and the depth of the blind holes is less than the depth of the main flow channel. By alternately arranging the blind spot array 2 and the through-hole array 1 perpendicular to the inlet direction, the through-hole array 1 forms a strong physical barrier to the gas, possessing strong kinetic energy, while the blocking effect of the blind spot array 1 is relatively weak, allowing for local bypass or bypassing of the fluid. After the two are alternately arranged in the vertical direction, periodic strong and weak blocking zones are formed before the fluid enters the main flow channel, causing the gas to undergo multiple bypassing, bypassing, and pressure redistribution in the distribution direction, preventing the gas from concentrating in local low-resistance paths, thereby improving the uniformity of flow distribution in the main flow channel. The cross-sectional shape of the through-hole 1-1 and the blind holes can be any one of circular, triangular, square, or elliptical.

[0046] It should be noted that the following embodiments are illustrated using the cathode flow field of a fuel cell (the transmission medium is air and liquid water) as an example. However, those skilled in the art will understand that the gradient lattice distribution region design described in this invention is also applicable to the anode flow field (transmitting hydrogen) and the cooling flow field (transmitting coolant).

[0047] Example 1

[0048] like Figure 1 , Figure 2 and Figure 3 As shown, in the gradient lattice distribution zone of Example 1, the gas (or coolant) enters through the flow field inlet 5, first flows through the inlet distribution zone 4, and after being uniformly distributed, it enters the mainstream zone composed of parallel straight channels. After the reaction is completed, the fluid is collected through the outlet distribution zone 9 and discharged to the flow field outlet 10.

[0049] like Figure 1As shown, a through-hole array 1 is provided in the inlet distribution area 4 and the outlet distribution area 9, respectively. The through-hole array 1 is composed of an array of through holes 1-1 with a depth equal to the depth of the main flow channel. In Embodiment 1, an interlaced rectangular array is used as an example. Here, "interlaced" means that the through holes 1-1 in one column are not in the same horizontal direction (flow direction) as the through holes 1-1 in another adjacent column. In this embodiment, the depth H1 of the through holes 1-1 is 0.35 mm, and the cross-section of the through holes 1-1 is circular. The diameter of the cross-section (i.e., Figure 2 The length (L1) and width (W1) are 1.4 mm. The function of the through hole 1-1 is to form a strong local solid barrier within the distribution zone, forcing the fluid to mainly circumvent it from both sides. Both the inlet distribution zone 4 and the outlet distribution zone 9 have blind spot lattices 2. Since the inlet distribution zone 4 and the outlet distribution zone 9 are symmetrically distributed, the following explanation uses the inlet distribution zone 4 as an example.

[0050] A blind spot array 2 is provided in a direction perpendicular to the horizontal direction; the blind spot array 2 and the through-hole array 1 are arranged alternately, and the blind spot array 2 is composed of a number of blind holes set at the intervals between adjacent through-holes 1-1, as follows: Figure 1 As shown, in one column of the through-hole lattice 1, a blind hole is provided between two adjacent through holes 1-1, and several blind holes in one column constitute one column of the blind hole lattice 2; the depth of the blind hole is less than the depth of the main flow channel. Figure 3 As shown, the blind spot array 2 includes forward blind holes 2-1 and reverse blind holes 3-1 with opposite closing directions; wherein, the forward blind spot array 2 is composed of a plurality of forward blind holes 2-1, and the open end of the forward blind hole 2-1 is connected to the front of the flow field; the reverse blind spot array 3 is composed of a plurality of reverse blind holes 3-1, and the open end of the reverse blind hole 3-1 is connected to the opposite side of the flow field.

[0051] The depths of the forward blind hole 2-1 and the reverse blind hole 3-1 are less than the depth of the main channel. In this embodiment, the depth H2 of both the forward blind hole 2-1 and the reverse blind hole 3-1 is 0.15 mm, approximately half the depth of the through hole. The cross-sections of both the forward blind hole 2-1 and the reverse blind hole 3-1 are circular, with the same diameter of 1.2 mm. Their calculated cross-sectional area is approximately 0.73 times that of the through hole 1-1. Since one end of the blind hole is open and the other is closed, fluid can flow around it from both sides, enter from the open end, and flow over it. Therefore, the local flow resistance is weaker than that of the through lattice.

[0052] like Figure 2As shown, in terms of arrangement, in the direction perpendicular to the fluid inlet (i.e., the vertical direction, or column direction), the column-direction spacing S1 between through-hole 1-1 and either the forward blind hole 2-1 or the reverse blind hole 3-1 is 1.1 mm. In the direction parallel to the fluid inlet (i.e., the horizontal direction, or row direction), the row-direction spacing S2 between adjacent through-holes 1-1 is 2.3 mm, and the row-direction spacing S3 between adjacent forward blind holes 2-1 is 2.3 mm. 22 The spacing S in the row direction between adjacent reverse blind holes 3-1 is 2.5mm. 22 It is 2.5mm.

[0053] The open ends of the blind spot array are oriented in opposite directions between adjacent columns. Specifically, the first column of the blind spot array is a forward blind spot array 2, with the open end of its forward blind hole 2-1 communicating with the front of the flow field; the adjacent second column of the blind spot array is a reverse blind spot array 3, with the open end of its reverse blind hole 3-1 communicating with the back of the flow field. Thus, the forward blind spot array 2 and the reverse blind spot array 3 are arranged alternately in a direction perpendicular to the inlet until the entire distribution area is filled. In this embodiment, the depth and cross-sectional area of ​​the blind holes (whether forward or reverse) remain constant along the fluid flow direction.

[0054] Example 1 uses the alternating arrangement of through-hole lattice and blind lattice, as well as the alternating change of the direction of the open end of the blind lattice, to form periodic high and low flow resistance regions and three-dimensional flow paths in the distribution area, which can effectively improve the uniformity of fluid distribution.

[0055] Working principle of Example 1:

[0056] In Example 1, the inherent pattern of uniform lattice depth in the distribution zone, which is the same as the main channel depth, is changed by reducing the local lattice depth. A flow resistance gradient is constructed within the distribution zone using a shallow-depth structure. If the entire distribution zone uses a through-lattice, the fluid is completely blocked in the depth direction and can only flow around the sides of the lattice in the planar direction, resulting in significant local flow resistance and pressure loss. In contrast, the blind lattice depth in Example 1 is smaller than the main channel depth and does not completely penetrate the depth direction of the flow field. The fluid can flow around the sides of the lattice and also flow parallel over the lattice, with a significantly weaker local blocking effect than a through-lattice. This transforms the flow within the distribution zone from a simple planar flow to a complex flow with certain three-dimensional characteristics. Gas can undergo bypassing, flow around, and reattachment processes in local areas, which is beneficial for enhancing lateral diffusion and pressure equalization within the distribution zone.

[0057] Because the blind lattice effectively weakens the excessive obstruction that might occur when the through-lattice is continuously arranged, the local flow resistance in the distribution zone changes from a single high-resistance form to an alternating form of high and low flow resistance, thus enabling the distribution zone to regulate flow. The orderly combination of the blind lattice and the through-lattice allows the gas to undergo multiple local accelerations and decelerations within the distribution zone, ultimately achieving the goal of balancing the overall flow pressure within the distribution zone. In the outlet distribution zone, the depth variation of the blind lattice allows the gas to pass directly horizontally near the guide fluid, generating a local velocity gradient. This enhances the shear force exerted by gas transport on the formation of product water, thereby reducing the adhesion time of liquid water on the surface of the distribution zone and accelerating drainage.

[0058] Furthermore, in Example 1, the blind spot lattice and through-hole lattice are alternately arranged perpendicular to the inlet direction, which can effectively divert the fluid that directly enters the main flow channel. The through-hole lattice forms a strong physical barrier to the gas and has strong kinetic energy, while the barrier effect of the blind spot lattice is relatively weak, allowing the fluid to bypass or flow around locally. After the two are alternately arranged in the vertical direction, periodic strong barrier zones and weak barrier zones are formed before the fluid enters the main flow channel, causing the gas to undergo multiple bypassing, bypassing, and pressure redistribution in the distribution direction, avoiding the gas from concentrating in local low-resistance paths, thereby significantly improving the uniformity of flow distribution in the main flow channel. At the same time, the open ends of adjacent columns of blind spot lattices in the horizontal direction are opposite, which can generate alternating bypassing and three-dimensional disturbance of the gas in the overall direction of the vertical flow field, preventing the fluid from being transported to one side or in a single direction of the flow field. It should be noted that this embodiment does not use the alternating arrangement of blind spot lattices and through-hole lattices in the horizontal direction, because the fluid has already been effectively diverted in the vertical direction, and there is no need to use depth changes to block the only path for the fluid to finally enter the main flow channel.

[0059] Example 2

[0060] like Figure 4 and Figure 5 As shown, in Embodiment 2, based on Embodiment 1, a row of lattice micro-particles is provided on the sidewall of the distribution area near the flow field inlet 5 and / or flow field outlet 10. The lattice micro-particles are arranged in sequence by sidewall through-holes 6, sidewall forward blind spot holes 7, and sidewall reverse blind spot holes 8.

[0061] In terms of dimensions, the diameter of the cross-section of the sidewall through-hole 6 is 0.6 mm, and its cross-sectional area is approximately 18.4% of the cross-sectional area of ​​the through-hole 1-1. The diameter of the cross-section of the sidewall forward blind hole 7 and the sidewall reverse blind hole 8 is 0.5 mm, and their cross-sectional area is approximately 17.4% of the cross-sectional area of ​​the main blind hole. In terms of depth, the depth of the sidewall through-hole 6 is the same as the depth of the through-hole 1-1, both being 0.35 mm; the depth of the sidewall forward blind hole 7 and the sidewall reverse blind hole 8 is the same as the depth of the blind holes in the blind dot lattice, both being 0.15 mm. In terms of position and arrangement, the distance S5 between the sidewall through-hole 6 and the sidewall is 0.2 mm, the parallel distance between the sidewall through-hole 6 and the through-hole 1-1 in the first row of the through-dot lattice 1 is 1.0 mm, and the distance S4 between the sidewall through-hole 6 and the inlet and outlet regions of the flow field is 1.5 mm. The distance S3 between the through-hole 6 on the sidewall and the adjacent blind hole on the sidewall is 0.7 mm, and the distance S6 between the adjacent blind holes on the sidewall is 0.6 mm.

[0062] Because a row of lattice micro-body particles is provided on the sidewall of the distribution zone near the flow field inlet 5 and / or the flow field outlet 10, the fluid also experiences flow around and flow across the lattice micro-body particles. Due to the smaller size of the micro-body particles and their close contact with the sidewall, a higher local velocity gradient and shear force can be generated near the wall surface. Especially in the outlet distribution zone, this high shear force helps to quickly strip the liquid water attached to the sidewall and prevent flooding.

[0063] Example 3

[0064] In Example 3, based on Example 1 or Example 2, the geometric parameters of the forward blind hole 2-1 in the forward blind hole array 2 show a gradual changing trend along the fluid flow direction, or the geometric parameters of the reverse blind hole 3-1 in the reverse blind hole array 3 also show a gradual changing trend.

[0065] Specifically, along the fluid flow direction (i.e., from the flow field inlet 5 to the main flow zone inlet side or from the flow field inlet 5 to the flow field outlet 10), either of the following two situations falls within the protection scope of this embodiment:

[0066] The depth and / or cross-sectional area of ​​the positive blind hole 2-1 in the positive blind lattice 2 gradually change (e.g., gradually decrease or gradually increase), while the depth and cross-sectional area of ​​the reverse blind hole 3-1 in the reverse blind lattice 3 remain constant.

[0067] The depth and / or cross-sectional area of ​​the reverse blind hole 3-1 in the reverse blind lattice 3 gradually change, while the depth and cross-sectional area of ​​the forward blind hole 2-1 in the forward blind lattice 2 remain constant.

[0068] Taking the gradual decrease in the size of the forward blind orifice in scenario a as an example: near the flow field inlet 5, the forward blind orifice 2-1 is deeper and has a larger area, resulting in a stronger blocking effect, which helps to force the fluid to spread rapidly laterally on the front side. As the fluid advances towards the mainstream region, the forward blind orifice 2-1 gradually becomes shallower and smaller, the blocking effect on the front side weakens, and the fluid can enter the mainstream region more smoothly. Meanwhile, the reverse blind orifice 3-1, due to its constant size, maintains its blocking effect along the flow path. This causes the flow resistance difference between the front and reverse sides to gradually change along the flow direction, thereby creating a certain degree of flow redistribution in the flow field thickness direction. This embodiment, by introducing a unilateral gradient, further optimizes the pressure distribution along the flow direction based on embodiment 1, while avoiding the structural complexity caused by a double-sided gradient. It is suitable for application scenarios that require a certain improvement in distribution uniformity but wish to simplify the manufacturing process.

[0069] In this embodiment, the gradient can be a linear gradient, a step gradient, or other forms of continuous or discrete change, as long as it generally exhibits a recognizable decreasing trend along the flow direction. Features not mentioned in this embodiment (such as the arrangement of the dot matrix, sidewall micro-volumes, etc.) are the same as in Embodiment 1 or Embodiment 2.

[0070] Example 4

[0071] In Example 4, based on Example 3, the geometric parameters of the forward blind hole 2-1 in the forward blind hole array 2 gradually change along the fluid flow direction, while the geometric parameters of the reverse blind hole 3-1 in the reverse blind hole array 3 also gradually change, and the forward blind hole and the reverse blind hole adopt opposite gradual change trends.

[0072] Specifically, along the fluid flow direction, the depth and / or cross-sectional area of ​​the forward blind holes 2-1 in the forward blind hole lattice 2 gradually decreases; while the depth and / or cross-sectional area of ​​the reverse blind holes 3-1 in the reverse blind hole lattice 3 gradually increases. This design results in deeper and larger forward blind holes (stronger obstruction) and smaller reverse blind holes (weaker obstruction) in the flow field inlet region, causing the fluid to tend to overflow from the side with weaker obstruction. As the fluid advances towards the main flow region, the forward blind holes gradually become shallower and smaller (weaker obstruction), while the reverse blind holes gradually become deeper and larger (stronger obstruction), causing the fluid to shift to flowing from the front side with weaker obstruction. This reversal of the overflow preference along the flow direction forces continuous exchange and mixing of the fluid in the flow field thickness direction, creating a more complex and intense three-dimensional disturbance than in Example 3. Compared to Example 3, Example 4, through bilateral reverse gradient, not only achieves pressure compensation along the flow direction, but more importantly, introduces an active switching of the dominant flow side along the flow path, thereby significantly enhancing the mixing degree of the upper and lower fluid layers. Experimental verification shows that the fluid distribution uniformity coefficient of this example is better than that of Example 3, proving that the bilateral reverse gradient design has unique advantages in promoting three-dimensional mixing and achieving finer flow distribution, and is suitable for operating conditions with high requirements for distribution uniformity. The gradient method in this example can be linear gradient, step gradient, or other forms of continuous or discrete change.

[0073] This embodiment can also be implemented based on Embodiment 1 or Embodiment 2. The gradient method can also be linear, stepped, or other forms.

[0074] Performance verification

[0075] To verify the technical effect of the present invention, the applicant set up a comparative test. The comparative example adopted a conventional design: the entire distribution area consisted of a lattice with the same dimensions as the through hole in Example 1 (diameter 1.4 mm, depth 0.35 mm), arranged in a simple array with uniform spacing (horizontal spacing 1.3 mm, vertical spacing 0.85 mm). The total flow area was close to that of Example 1. Figure 6 As shown.

[0076] Taking Example 1 as an example, the test was conducted, and the results are as follows: Figure 7 and Figure 8 As shown. Figure 7 The comparison of fluid distribution uniformity coefficients is shown. The fluid distribution uniformity coefficient of Example 1 is 0.71, while that of the comparative example is 0.56, demonstrating that the fluid distribution effect has been significantly improved. Figure 7 The results show that the velocity of the fluid entering the mainstream region in Example 1 is 12.5 m / s, while the velocity of the fluid entering the mainstream region in the comparative example is 8.7 m / s, indicating that Example 1 can significantly improve the medium transmission efficiency.

[0077] For Example 3 (taking the forward blind hole decreasing and the reverse blind hole constant as an example) and Example 4 (taking the forward decreasing and the reverse increasing as an example), simulation calculations and experimental verifications were performed respectively, and the results are as follows. Figure 9 and Figure 10 As shown. Figure 9 The comparison of fluid distribution uniformity coefficients is shown. The uniformity coefficient of Example 4 is 0.77, which is significantly better than 0.65 of Example 3. This indicates that the design of the forward and reverse blind holes in Example 4, which adopt opposite trends along the fluid flow direction, can significantly improve the fluid distribution uniformity. Figure 10 The comparison of average flow velocity in the mainstream flow channel is shown. In Example 3, because the blind holes decrease overall along the fluid flow direction, the speed at which the fluid directly enters the mainstream zone is accelerated, and the overall average flow velocity in the channel reaches 13.1 m / s; while the average flow velocity in Example 4 is 12.2 m / s.

[0078] Comparing the two embodiments, Embodiment 4 shows an improvement in uniformity coefficient of approximately 18.5% compared to Embodiment 3, while the flow velocity only decreases by approximately 6.9%. The improvement in uniformity coefficient far outweighs the loss in flow velocity. Therefore, Embodiment 4 can further improve the uniformity of fluid distribution in the flow field without significantly sacrificing fluid transport velocity; while Embodiment 3, although having a higher medium flow velocity, exhibits relatively poor uniformity. In practical applications, the choice can be made based on specific requirements: Embodiment 3 can be used for scenarios with high flow velocity requirements, while Embodiment 4 can be used for scenarios with high uniformity requirements.

[0079] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0080] The detailed descriptions listed above are merely specific illustrations of feasible embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A gradient lattice distribution region for a fuel cell flow field, wherein a through lattice (1) for guiding flow is provided in the inlet distribution region (4) and / or outlet distribution region (9) of the fuel cell bipolar plate flow field, the through lattice (1) comprising a plurality of through holes (1-1) with a depth equal to the depth of the main flow channel, characterized in that, A blind spot array (2) is provided in the direction perpendicular to the fluid inlet; the blind spot array (2) and the through-hole array (1) are distributed in an alternating manner; the blind spot array (2) is composed of a number of blind holes provided at the interval between adjacent through-holes (1-1), and the depth of the blind holes is less than the depth of the main flow channel.

2. The gradient lattice distribution region of the fuel cell flow field according to claim 1, characterized in that, The blind spot array (2) includes positive blind holes (2-1) and reverse blind holes (3-1) with opposite closing directions; wherein, the positive blind spot array (2) is composed of a number of positive blind holes (2-1), and the open end of the positive blind hole (2-1) is connected to the front of the flow field; the reverse blind spot array (3) is composed of a number of reverse blind holes (3-1), and the open end of the reverse blind hole (3-1) is connected to the back of the flow field.

3. The gradient lattice distribution region of the fuel cell flow field according to claim 1, characterized in that, The cross-sectional shape of the through hole (1-1) and the blind hole can be any one of the following: circular, triangular, square, or elliptical.

4. The gradient lattice distribution region of the fuel cell flow field according to claim 1, characterized in that, The depth of the blind hole does not exceed 1 / 2 of the depth of the through hole (1-1), and the cross-sectional area of ​​the blind hole is 0.6 to 0.85 times the cross-sectional area of ​​the through hole (1-1).

5. The gradient lattice distribution region of the fuel cell flow field according to claim 1, characterized in that, In the direction perpendicular to the fluid inlet, the distance S1 between adjacent through holes (1-1) and blind holes is 1-2 mm; in the direction parallel to the fluid inlet, the distance S2 between adjacent through holes (1-1) is smaller than the distance S between adjacent blind holes. 22 .

6. The gradient lattice distribution region of the fuel cell flow field according to claim 2, characterized in that, In the direction perpendicular to the fluid inlet, if the nth column blind spot array is a positive blind spot array (2), then the (n+1)th column blind spot array is a reverse blind spot array (3), so that the open ends of the blind spot arrays of adjacent columns are opposite.

7. The gradient lattice distribution region of the fuel cell flow field according to claim 2, characterized in that, Along the direction of fluid flow, the depth and / or cross-sectional area of ​​the positive blind hole (2-1) in the positive blind hole array (2) gradually changes, and the depth and / or cross-sectional area of ​​the reverse blind hole (3-1) in the reverse blind hole array (3) gradually changes.

8. The gradient lattice distribution region of the fuel cell flow field according to any one of claims 1-7, characterized in that, A row of lattice micro-body is provided on the side wall of the distribution area near the flow field inlet (5) and / or flow field outlet (10). The lattice micro-body is arranged in sequence by side wall through-holes (6), side wall forward blind hole (7) and side wall reverse blind hole (8).

9. The gradient lattice distribution region of the fuel cell flow field according to claim 8, characterized in that, The cross-sectional area of ​​the through-hole (6) on the sidewall is 15% to 25% of the cross-sectional area of ​​the through-hole (1-1); the cross-sectional areas of the positive blind hole (7) and the negative blind hole (8) on the sidewall are both 15% to 20% of the cross-sectional area of ​​the blind hole in the blind dot matrix; the depth of the positive blind hole (7) and the negative blind hole (8) on the sidewall is the same as the depth of the blind hole.

10. The gradient lattice distribution region of the fuel cell flow field according to claim 8, characterized in that, The distance between the lattice microparticles and the sidewall is 0.1 to 0.2 mm, the parallel distance between the lattice microparticles and the first column of the main lattice is 1 to 1.5 mm, and the distance between the lattice microparticles and the inlet and outlet regions of the flow field is 1 to 3 mm.

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