A multi-zone variable cross-section flow field plate, bipolar plate assembly, and fuel cell stack

Abstract

The application discloses a multi-region variable cross-section parallel flow channel flow field plate, a bipolar plate assembly and a fuel cell stack. The flow channel region is a parallel flow field formed by parallel flow channels and flow channel ridges. The partitioned ridges are arranged in the parallel flow field region, and the parallel flow field region is divided into at least two partitions. A plurality of common channels are arranged at both ends of the parallel flow field region and are asymmetrically distributed. The common channels are connected in series with the partitions to form a complete flow field loop. The flow resistance of the common channels is 1-2 orders of magnitude smaller than the flow resistance of the flow channels. Through the above manner, the fluid cross-sectional area of each region divided by the common channels is gradually reduced or kept equal through the region design. The common channels connecting different partitions balance the gas concentration of the bipolar plates at different positions in the stack again, so that the performance of the stack is more balanced. The flow field plate has extremely low flow resistance, and liquid water generated in the flow field is easily discharged.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a multi-region variable cross-section parallel flow channel plate, a bipolar plate assembly, and a fuel cell stack. Background Technology

[0002] Fuel cells convert the chemical energy of hydrogen and oxygen into electrical and thermal energy through an electrochemical reaction. There is no traditional combustion process in the energy conversion process, resulting in high energy conversion efficiency. Moreover, the reactant is water, making it a highly efficient conversion of clean energy.

[0003] The bipolar plate is a core component of a fuel cell, primarily used to support the membrane electrode assembly (MEA), distribute gas, conduct electricity and heat, and remove reactants. In traditional flow field plate designs, the flow interface is constant. As the reactant is consumed, the gas concentration and pressure along the flow path gradually decrease, leading to a decline in the fuel cell's electrochemical performance. Furthermore, traditional flow field plates typically have long flow channels and high flow resistance, with most exceeding 20 kPa, making them prone to localized flooding and affecting the fuel cell's polarization performance and lifespan.

[0004] To address the aforementioned issues, various improvement schemes have been proposed in existing technologies, such as variable cross-section flow channel design and multi-channel serpentine flow field. However, these schemes either increase flow resistance, hindering drainage, or require complex manifold structures connected in series, increasing the design difficulty and cost of the fuel cell stack. Therefore, there is an urgent need for a flow field plate structure that can reduce flow resistance while maintaining uniform concentration and pressure of the reaction medium. Summary of the Invention

[0005] The main technical problem solved by this invention is to provide a parallel flow field plate with multi-region variable cross-section, a bipolar plate assembly, and a fuel cell stack. By dividing the parallel flow field into sections and connecting them in series using low-resistance common flow channels, the flow area is gradually reduced, so that the concentration and pressure of the reaction medium in the entire flow field region do not decrease with the consumption of the medium; at the same time, the flow resistance in the entire flow field is significantly reduced, the drainage capacity of the fuel cell is improved, and the performance and reliability are enhanced.

[0006] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is: to provide a multi-region variable cross-section flow field plate, comprising:

[0007] The flow channel region is a parallel flow field composed of mutually parallel flow channels and flow channel ridges;

[0008] The ridge of the partition is set in the parallel flow field region, dividing the parallel flow field region into at least two partitions;

[0009] Multiple common channels are located at both ends of the parallel flow field region and are asymmetrically distributed. The common channels are connected in series with the partitions to form a complete flow field loop.

[0010] Among them, the cross-sectional area of ​​fluid flow in each zone decreases sequentially or remains equal along the flow direction;

[0011] The flow resistance of the common channel is 1 to 2 orders of magnitude smaller than that of the flow channel.

[0012] In a preferred embodiment of the present invention, the flow channel is a straight flow channel, an S-shaped curved flow channel, or a flow channel of other shapes; the common channel is staggered at both ends of the parallel flow field, so that the fluid alternates direction between adjacent partitions, forming a reciprocating flow path.

[0013] In a preferred embodiment of the present invention, the common channel includes a starting channel and an intermediate common channel; the starting channel is a separate fluid inlet or outlet channel; the intermediate common channel connects two adjacent zones simultaneously, allowing the fluid in the two zones to flow in series; the common channels located at both ends of the parallel flow field are connected to the same zone, allowing the fluid in the three zones to flow in series.

[0014] In a preferred embodiment of the present invention, a bridging zone structure is further included. The bridging zone structure is located on the opposite side of the flow channel region and includes a bridging zone flow channel groove and fluid inlet and outlet communicating with the common channel and the parallel flow field region, for guiding fluid from the common channel to the parallel flow field region to realize the series connection between the zones.

[0015] In a preferred embodiment of the present invention, the ridge of the partition is provided with a ridge cut-off opening for connecting adjacent partitions, so that fluid can flow from one partition into the adjacent partition.

[0016] In a preferred embodiment of the present invention, all common channels and flow channels are disposed on the same side of the flow field plate, and the fluid directly turns between the partitions through the common channels.

[0017] In a preferred embodiment of the present invention, the ratio of the fluid flow cross-sectional area of ​​adjacent partitions is 0.85 to 0.98; the overall flow resistance of the flow field plate is less than 10 kPa.

[0018] In a preferred embodiment of the present invention, the edges of the common channel and the partition are provided with sealing ridges, and the flow field plate is provided with flow field sealing grooves for sealing when assembling a fuel cell stack.

[0019] Another technical solution adopted by the present invention is to provide a flow field plate comprising at least one of the above-mentioned flow field plates as an anode plate and / or a cathode plate.

[0020] Another technical solution adopted by the present invention is to provide a bipolar plate assembly comprising multiple of the above-mentioned bipolar plate assemblies and a membrane electrode assembly.

[0021] The beneficial effects of this invention are as follows: Through a regional design, the fluid cross-sectional area of ​​each region divided by the common flow channel decreases sequentially or remains equal, avoiding concentration and pressure drops caused by the consumption of the reaction medium. The common flow channel connecting different zones will again balance the gas concentration at different positions of the electrode plates in the fuel cell stack, making the performance of the fuel cell stack more balanced.

[0022] The flow field plate of this invention has extremely low flow resistance, making it easy to discharge the liquid water generated within the flow field. The multi-zone design is connected in series through a common flow channel, where most of the liquid water collects and can humidify the reaction medium before entering the next zone; excess liquid water can be controlled and discharged by adding a water guide pipe at the port of the common flow channel of the fuel cell stack.

[0023] The multi-region variable cross-section parallel flow field plate of the present invention can reduce the stoichiometric ratio requirement, thereby reducing the power consumption of the circulating pump or compressor and improving the utilization rate of the fuel cell system.

[0024] This invention divides the flow field into multiple regions and connects them in series through a common flow channel, without the need for additional pipes and accessories, forming a single and complete flow field. The structure is simple, and the design of the fuel cell stack and system is straightforward. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0026] Figure 1 This is a schematic diagram of a preferred embodiment of the parallel flow channel flow field plate with multi-region variable cross-section of the present invention;

[0027] Figure 2 This is a schematic diagram of a preferred embodiment of the parallel flow channel flow field plate with multi-region variable cross-section of the present invention;

[0028] Figure 3 yes Figure 1 and Figure 2 Schematic diagram of the bridge section at point A;

[0029] Figure 4 This is a schematic diagram of a preferred embodiment of the parallel flow channel flow field plate with multi-region variable cross-section of the present invention;

[0030] The components in the attached diagram are labeled as follows: 100, Flow field plate; 201, Inlet common channel for medium A; 202, Intermediate common channel; 203, Intermediate common channel; 204, Intermediate common channel; 205, Intermediate common channel; 206, Outlet common channel for medium A; 301, Inlet common channel for medium B; 302, Outlet common channel for medium B; 401, Inlet common channel for medium C; 402, Outlet common channel for medium C; 501, Fluid inlet and outlet of the parallel flow channel region and the common flow channel of medium A; 601, Ridge of the parallel flow channel section; 602, Ridge of the parallel flow channel; 603, Ridge connecting the common flow channel and the parallel flow channel (bridge area). ); 604, Ridge cut-off; 701, Flow channel groove of parallel flow channel; 702, Flow channel groove of bridge area; 801, Sealing groove of flow field; 802, Sealing groove of common flow channel at outlet of medium B; 803, Sealing groove of common flow channel at inlet of medium C; 804, Sealing groove of common flow channel connecting medium A; 805, Sealing groove of common flow channel connecting medium A; 806, Sealing groove of common flow channel at inlet of medium A; 807, Sealing groove of common flow channel at inlet of medium B; 808, Sealing groove of common flow channel at outlet of medium C; 809, Sealing groove of common flow channel connecting medium A; 810, Sealing groove of common flow channel connecting medium A; 811, Sealing groove of common flow channel at outlet of medium A. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0033] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0034] In the description of this invention, it should be noted that the terms "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is conventionally placed during use. These terms are used only for the convenience of describing the invention and for 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. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0035] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "connection" 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 based on the specific circumstances.

[0036] In this invention, unless otherwise expressly specified and limited, "above or below" a first feature may include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on" the first feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the first feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0037] Example 1:

[0038] Reference Figure 1 and Figure 3 This embodiment provides a flow field plate 100 with multi-region variable cross-section. The flow channel region of the flow field plate 100 is a parallel flow field composed of mutually parallel flow channel ridges 602 and flow channel grooves 701. In this embodiment, the flow channel grooves 701 are straight channels (or S-shaped curved channels) and are arranged parallel to the flow channel ridges 602. The parallel flow field region is provided with ridges 601 that divide the parallel flow field into five zones (first to fifth zones). Multiple common channels are provided at both ends of the parallel flow field, including an inlet common channel 201 for medium A, an outlet common channel 206, and intermediate common channels 202, 203, 204, and 205. These common channels are staggered (asymmetrically distributed), connecting the five zones in series to form a complete flow field loop.

[0039] The flow path of medium A (an oxidant in this embodiment) is as follows:

[0040] Fluid enters from the inlet public channel 201, passing through the bridge area structure ( Figure 3 The flow path reaches the first zone. The bridge zone structure is located on the opposite side of the flow channel region, including the bridge zone flow channel groove 702, the ridge 603 located at the connection between the common flow channel and the parallel flow channel, and the fluid inlet and outlet 501 connecting the common channel and the parallel flow field region. The fluid enters the bridge zone from the inlet common channel 201, is guided by the bridge zone flow channel groove 702, and flows into the flow channel groove 701 of the parallel flow channel through the fluid inlet and outlet 501, thereby entering the first zone.

[0041] The fluid flows to the right along the flow channel 701 in the first zone and reaches the common channel 204.

[0042] The fluid flows through the common channel 204, passes through the bridge area structure to reach the second zone, flows to the left in the second zone, and reaches the common channel 202.

[0043] Similarly, the fluid flows sequentially through common channel 202, third zone (to the right), common channel 205, fourth zone (to the left), common channel 203, fifth zone (to the right), and outlet common channel 206, completing the entire flow field loop.

[0044] The fluid inlet / outlet 501 is used to introduce fluid from the common channel into the parallel flow channel 701, and can also lead the fluid from the parallel flow channel 701 to the next common channel 204.

[0045] The entrance public passage 201 connects the outside to the first zone; public passage 204 connects the first zone and the second zone; public passage 202 connects the second zone and the third zone; public passage 205 connects the third zone and the fourth zone; public passage 203 connects the fourth zone and the fifth zone; and exit public passage 206 connects the fifth zone and the outside.

[0046] The common channels 204 and 202 located at both ends of the parallel flow field jointly connect the second zone, enabling the first, second, and third zones to flow in series; the common channels 205 and 203 jointly connect the fourth zone, enabling the third, fourth, and fifth zones to flow in series.

[0047] The cross-sectional area of ​​fluid flow in each zone decreases sequentially along the flow direction (the first zone has the largest cross-sectional area, and the fifth zone has the smallest). The ratio of the cross-sectional area of ​​fluid flow between adjacent zones is 0.85 to 0.98 to compensate for the consumption of the reaction medium, so that the flow velocity and pressure of the medium in each zone remain basically constant. The flow resistance of the common channel is 1 to 2 orders of magnitude smaller than that of the flow channel, so that the overall flow resistance of the flow field plate is less than 10 kPa.

[0048] The edge of the flow field plate 100 is also provided with an inlet common channel 301 and an outlet common channel 302 for medium B (fuel), and an inlet common channel 401 and an outlet common channel 402 for medium C (coolant). The edges of the common channels and partitions are provided with sealing ridges, and the flow field plate is provided with flow field sealing grooves 801 to 811 for forming a seal with the membrane electrode when the fuel cell stack is assembled.

[0049] Example 2:

[0050] like Figure 2 and Figure 3 As shown, the difference between this embodiment and Embodiment 1 is that: the ridge 601 of the parallel flow channel partition is provided with a ridge cut-off port 604, the opening width of which matches the width of the flow channel groove 701 of each partition, so that the fluid in adjacent partitions can flow directly. The intermediate common channels 202, 203, 204, 205 and the ridge cut-off port 604 together form a series path between partitions, wherein the common channel mainly plays a role in pressure balance and fluid compensation, ensuring that the fluid flows stably in series between each partition.

[0051] The flow path of medium A is as follows:

[0052] The fluid enters the first section from the inlet common channel 201 and flows to the right. It passes through the bridge area structure, such as... Figure 3 As shown, the first zone is reached. The bridge zone structure is located on the opposite side of the flow channel region, including a bridge zone flow channel trough 702, a ridge 603 located at the connection between the common flow channel and the parallel flow channel, and a fluid inlet and outlet 501 communicating with the common channel and the parallel flow field region.

[0053] The fluid flows to the right along the flow channel 701 within the first section.

[0054] After the fluid reaches the end of the first section, it mainly enters the second section of the low-resistance main passage directly through the ridge cut-off port 604 on the ridge 601. At the same time, a small portion of the fluid enters the second section through the bridge area of ​​the common channel 204.

[0055] Within the second zone, the fluid flows to the left, primarily entering the third zone through the ridge cut-off port 604, with a small portion passing through the bridge area and entering the third zone via the common passage 202.

[0056] Similarly, the fluid flows sequentially through the ridge cut-off port 604 (main), the public channel (auxiliary), through the third zone (right), the fourth zone (left), and the fifth zone (right), and finally through the bridge area and out through the outlet public channel 206.

[0057] The entrance public passage 201 connects the outside to the first zone; public passage 204 connects the first zone and the second zone; public passage 202 connects the second zone and the third zone; public passage 205 connects the third zone and the fourth zone; public passage 203 connects the fourth zone and the fifth zone; and exit public passage 206 connects the fifth zone and the outside.

[0058] Common channels 204 and 202, located at both ends of the parallel flow field, jointly connect the second zone, enabling the first, second, and third zones to flow in series. Common channels 205 and 203 jointly connect the fourth zone, enabling the third, fourth, and fifth zones to flow in series.

[0059] Because the ridge 601 has a ridge cut-off port 604, the flow channels 701 of adjacent zones are directly connected through the ridge cut-off port 604. This allows the intermediate common channels 202, 203, 204, and 205 to primarily serve as pressure balancing and fluid compensation channels, rather than being the only necessary channels for fluid series connection. The common channels and the ridge cut-off port 604 together constitute the series connection path between zones: the ridge cut-off port 604 provides a low-resistance main path, while the common channels provide an auxiliary path and ensure pressure balance. When the ridge cut-off port 604 experiences insufficient flow due to manufacturing errors or partial blockage, the common channels can provide compensating flow, ensuring stable series flow of fluid between zones.

[0060] The fluid flow cross-sectional area of ​​each zone is kept equal (or can be set to decrease sequentially), and the ratio of the fluid flow cross-sectional area of ​​adjacent zones is 0.85 to 0.98 to compensate for the consumption of the reaction medium. The flow resistance of the common channel is 1 to 2 orders of magnitude smaller than that of the flow channel, and the overall flow resistance is less than 10 kPa.

[0061] The edges of the common passage and partitions are provided with sealing ridges, and the flow field plate is provided with flow field sealing grooves to form a seal with the membrane electrode when the fuel cell stack is assembled. Other media channels are the same as in Example 1.

[0062] Example 3:

[0063] Reference Figure 4 The difference between this embodiment and Embodiment 1 is that the flow field plate does not include a bridge area structure, and all common channels and flow channel grooves are located on the same side of the flow field plate. The fluid directly changes direction between the different zones through the common channels without the need for a bridge structure.

[0064] The flow path of medium A is as follows:

[0065] The fluid enters the first section from the inlet common channel 201, flows to the right, and reaches the common channel 204.

[0066] Since the flow field plate does not include a bridge area structure, the fluid flows to the right along the flow channel 701 in the first zone and then directly merges into the common channel 204. In the common channel 204, the fluid turns along the surface of the flow field plate and flows directly into the flow channel 701 of the second zone from the outlet end of the common channel 204, flows to the left, and reaches the common channel 202.

[0067] Similarly, proceed sequentially through public passage 202, the third section (to the right), public passage 205, the fourth section (to the left), public passage 203, the fifth section (to the right), and exit public passage 206.

[0068] The connection relationships between each common channel and the partition are the same as in Example 1: common channel 204 connects the first and second partitions, common channel 202 connects the second and third partitions, common channel 205 connects the third and fourth partitions, and common channel 203 connects the fourth and fifth partitions. Common channels 204 and 202, located at both ends of the parallel flow field, jointly connect to the second partition, enabling the first, second, and third partitions to flow in series.

[0069] The cross-sectional area of ​​fluid flow in each zone decreases sequentially along the flow direction, and the ratio of the cross-sectional area of ​​fluid flow in adjacent zones is 0.85 to 0.98 to compensate for the consumption of the reaction medium. The flow resistance of the common channel is 1 to 2 orders of magnitude smaller than that of the flow channel, and the overall flow resistance is less than 10 kPa.

[0070] The edges of the common passage and partitions are provided with sealing ridges, and the flow field plate is provided with flow field sealing grooves to form a seal with the membrane electrode when the fuel cell stack is assembled. Other structures are similar to those in Example 1.

[0071] Example 4:

[0072] This embodiment provides a bipolar plate assembly, including at least one flow field plate as described in any one of the preceding embodiments 1 to 3, serving as an anode plate and / or a cathode plate.

[0073] Specifically, the bipolar plate assembly is composed of two stacked flow field plates, namely an anode plate and a cathode plate. Both the anode plate and the cathode plate adopt the flow field plate structure described in any one of Embodiments 1 to 3 above. The back sides (i.e., the sides without flow channels) of the two flow field plates are arranged opposite each other and sealed together by a frame, forming a closed coolant flow field between them; the flow channel surface of the anode plate faces the anode side of the membrane electrode, and the flow channel surface of the cathode plate faces the cathode side of the membrane electrode. The common channels 401 / 402 of the medium C (coolant) on the two flow field plates are automatically aligned after stacking, forming a coolant passage through the bipolar plate assembly; the common channels of medium A and medium B are respectively located on the outside of the two flow field plates and are connected to the external manifold.

[0074] In this embodiment, medium B (fuel, such as hydrogen) flows through the flow channel region of the anode plate, and medium A (oxidant, such as air) flows through the flow channel region of the cathode plate. The flow channel regions of the two plates are separated by the catalytic layer of the membrane electrode. Coolant medium C flows in the cooling flow field formed on the back of the two plates.

[0075] In another preferred embodiment, the anode plate adopts the flow field plate with the bridge area structure described in Example 1, and the cathode plate also adopts the flow field plate described in Example 1. The two flow field plates are sealed by a sealing ring in the sealing groove or by laser welding process to ensure that there is no leakage between the three media (fuel, oxidant, and coolant).

[0076] In another embodiment, the anode plate adopts the ridge-cut flow field plate described in Example 2, and the cathode plate adopts the bridge-free flow field plate described in Example 3. The common channel of the two flow field plates automatically aligns after stacking, forming a dielectric passage through the bipolar plate assembly.

[0077] The edge of the bipolar plate assembly has common inlet and outlet channels for media A, B, and C, for connection to an external manifold. Sealing ridges on the flow field plate form a contact seal with the membrane electrode frame, ensuring the gas-tightness of the fuel cell stack.

[0078] Example 5:

[0079] This embodiment provides a fuel cell stack, including multiple bipolar plate assemblies as described in Embodiment 4, and a membrane electrode assembly. The bipolar plate assemblies and the membrane electrode assembly are alternately stacked to form the main structure of the fuel cell stack.

[0080] Specifically, the fuel cell stack consists of dozens to hundreds of individual cells connected in series. Each individual cell includes: a membrane electrode assembly (containing a proton exchange membrane, an anode catalyst layer, a cathode catalyst layer, an anode gas diffusion layer, and a cathode gas diffusion layer), and bipolar plate assemblies (anode plate + cathode plate) located on both sides of the membrane electrode. The flow channel surface of the anode plate forms a contact seal and fluid communication with the anode gas diffusion layer of the membrane electrode through the seals in the sealing grooves 801-811; the flow channel surface of the cathode plate forms a contact seal and fluid communication with the cathode gas diffusion layer of the membrane electrode. Adjacent individual cells share a single bipolar plate assembly (i.e., the cathode plate of the previous individual cell and the anode plate of the next individual cell are the same flow field plate), and cooling isolation is achieved through the coolant flow field on the back of this flow field plate.

[0081] The fuel cell stack has end plates and current collectors at both ends for applying clamping force and collecting current. Inside the fuel cell stack, there are medium inlet manifolds and outlet manifolds that run through all bipolar plate assemblies and membrane electrode assemblies, which are connected to the common inlet and outlet channels of mediums A, B, and C on the flow field plate, respectively.

[0082] In a preferred embodiment, the fuel cell stack employs the bipolar plate assembly described in Example 4, wherein both the anode and cathode plates utilize the flow field plate with a bridging region structure described in Example 1. During stack operation, oxidant (air) enters the cathode plate flow field (i.e., cathode-side flow field) of each bipolar plate assembly from the dielectric A inlet manifold, fuel (hydrogen) enters the anode plate flow field (i.e., anode-side flow field) of each bipolar plate assembly from the dielectric B inlet manifold, and coolant (deionized water) enters the coolant flow field of the bipolar plate assemblies arranged back-to-back from the dielectric C inlet manifold. The three media flow in parallel within the stack, completing the electrochemical reaction through the membrane electrode assembly. After the reaction, exhaust gas is discharged from the dielectric A outlet manifold and the dielectric B outlet manifold, and the heated coolant is discharged from the dielectric C outlet manifold.

[0083] Thanks to the adoption of a multi-region variable cross-section flow field plate structure, the overall flow resistance of the fuel cell stack is less than 10 kPa, significantly lower than that of traditional fuel cell stacks (typically greater than 20 kPa). At the same time, the fluid flow cross-sectional area of ​​each zone decreases sequentially, ensuring that the concentration and pressure of the reaction medium remain uniform within the flow field region, thereby improving the performance stability and service life of the fuel cell stack.

[0084] The rated power of the fuel cell stack can be adjusted according to the number of bipolar plate assemblies and the active area, typically ranging from 1kW to 500kW, and is suitable for a variety of applications such as portable power supplies, stationary power stations and vehicle power systems.

[0085] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A flow field plate with multi-region variable cross-section, characterized in that, include: The flow channel region is a parallel flow field composed of mutually parallel flow channels and flow channel ridges; The ridge of the partition is set in the parallel flow field region, dividing the parallel flow field region into at least two partitions; Multiple common channels are located at both ends of the parallel flow field region and are asymmetrically distributed. The common channels are connected in series with the partitions to form a complete flow field loop. Among them, the cross-sectional area of ​​fluid flow in each zone decreases sequentially or remains equal along the flow direction; The flow resistance of the common channel is 1 to 2 orders of magnitude smaller than that of the flow channel.

2. The multi-region variable cross-section flow field plate according to claim 1, characterized in that, The flow channel is either a straight flow channel or a curved flow channel; the common channel is staggered at both ends of the parallel flow field, so that the fluid alternates direction between adjacent zones, forming a reciprocating flow path.

3. The multi-region variable cross-section flow field plate according to claim 1, characterized in that, The common channel includes a starting channel and an intermediate common channel; the starting channel is a separate fluid inlet or outlet channel; the intermediate common channel connects two adjacent zones, allowing the fluid in the two zones to flow in series. The common channels located at both ends of the parallel flow field are connected to the same partition, allowing the fluid in the three partitions to flow in series.

4. The multi-region variable cross-section flow field plate according to claim 1, characterized in that, It also includes a bridging zone structure, which is located on the opposite side of the flow channel region. The bridging zone structure includes a flow channel groove and fluid inlets and outlets that communicate with the common channel and the parallel flow field region, for guiding fluid from the common channel to the parallel flow field region to achieve series connection between the zones.

5. The multi-region variable cross-section flow field plate according to claim 1, characterized in that, The ridge of the partition has a ridge cut-off point to connect adjacent partitions, allowing fluid to flow from one partition into the next.

6. The multi-region variable cross-section flow field plate according to claim 1, characterized in that, All common channels and flow channels are located on the same side of the flow field plate, and the fluid directly turns between the zones through the common channels.

7. The multi-region variable cross-section flow field plate according to claim 1, characterized in that, The ratio of the fluid flow cross-sectional area of ​​adjacent zones is 0.85 to 0.98; the overall flow resistance of the flow field plate is less than 10 kPa.

8. The multi-region variable cross-section flow field plate according to claim 1, characterized in that, The edges of the common channel and the partition are provided with sealing ridges, and the flow field plate is provided with flow field sealing grooves for sealing when assembling a fuel cell stack.

9. A bipolar plate assembly, characterized in that, It includes at least one flow field plate as any one of claims 1 to 8, serving as an anode plate and / or a cathode plate.

10. A fuel cell stack, characterized in that, It includes the bipolar plate assembly as described in multiple claims 9, and the membrane electrode assembly.

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