A fuel cell anode flow channel with a continuous transition inlet structure and a fuel cell stack

Abstract

This invention discloses a fuel cell anode flow channel and stack with a continuous transition inlet structure, belonging to the field of fuel cell technology. The fuel cell stack includes at least one bipolar plate, with an anode flow channel formed on one side of the bipolar plate. The anode flow channel includes a hydrogen inlet, a distribution region, multiple parallel sub-flow channels, and a hydrogen outlet. The distribution region is located between the hydrogen inlet and the multiple sub-flow channels, and the distribution region is configured as a continuous transition structure to gradually change the flow direction and flow cross-section of the hydrogen flowing in from the hydrogen inlet, thereby guiding the hydrogen smoothly into the multiple sub-flow channels. By setting the distribution region as a continuous transition structure, this invention avoids flow separation and local eddies in the inlet region of hydrogen, effectively reduces the local flow resistance at the anode flow channel inlet, improves the uniformity of hydrogen distribution among the sub-flow channels, and enhances the mass transfer capacity on the anode side, making it particularly suitable for high power density cathode open air-cooled fuel cells.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and more specifically, to a fuel cell anode flow channel having a continuous transition inlet structure and a fuel cell stack including the anode flow channel. Background Technology

[0002] Fuel cells, as efficient and clean energy conversion devices, are widely used in portable power supplies, distributed power generation, and transportation due to their high energy conversion efficiency and low emissions. Among them, proton exchange membrane fuel cells (PEMFCs) are particularly suitable for applications with strict requirements on size and weight due to their fast start-up and high power density. As fuel cells develop towards higher power density, miniaturization, and lower cost, the gas flow and mass transfer performance within the fuel cell stack have an increasingly significant impact on overall performance and operational stability.

[0003] In high-power-density fuel cells, the supply and distribution of hydrogen on the anode side directly affects the adequacy of the electrochemical reaction. Especially in fuel cell systems with an open, air-cooled cathode, the uneven temperature distribution and frequent fluctuations in operating conditions during stack operation place higher demands on the continuous and uniform supply of hydrogen on the anode side. Uneven hydrogen distribution at the anode can easily lead to insufficient hydrogen supply or decreased hydrogen utilization in localized areas, resulting in battery performance degradation, reduced efficiency, and even affecting the long-term operational reliability of the stack.

[0004] Existing fuel cell anode flow channel structures typically include a hydrogen inlet, a distribution zone, several parallel sub-flow channels, and a hydrogen outlet. Hydrogen enters the flow field plate through the inlet, first entering the distribution zone, then being distributed to the various sub-flow channels, and finally flowing out of the cell along the flow channels. In the prior art closest to this invention, the anode hydrogen inlet often adopts a straight-through structure, meaning that hydrogen enters the distribution zone or main flow channel directly from the inlet pipe, and the connection between its inlet cross-section and the downstream flow channel structure is usually abrupt.

[0005] In this type of existing scheme, the anode flow field plate is generally a flat plate structure, and the hydrogen inlet is arranged vertically or approximately perpendicular to the flow field plate. When the hydrogen enters the distribution zone, its flow direction and flow cross-section change abruptly. The distribution zone often adopts a straight cavity or a semi-circular transition structure to distribute the hydrogen to multiple parallel sub-channels. Each sub-channel extends along the length of the flow field plate and is connected to the outlet collection area.

[0006] While the manufacturing process of the aforementioned structural form is relatively simple and can meet basic hydrogen supply requirements, its shortcomings gradually become apparent under high power density operating conditions: Due to the significant geometric abrupt change in the inlet region, hydrogen is prone to local eddies and flow separation when entering the distribution zone, resulting in high local flow resistance and increased pressure drop at the inlet. Simultaneously, the instability of the inlet flow state further affects the flow distribution within the distribution zone, causing differences in hydrogen flow rates between different sub-channels and resulting in uneven hydrogen concentration distribution on the anode side. Especially in cathode-open air-cooled fuel cells, the flow of cooling air and changes in environmental conditions significantly affect the stack temperature field and reaction rate. If there is significant inlet flow resistance or uneven distribution on the anode side, its adverse effects are easily amplified under high current density conditions, thus restricting the improvement of the overall fuel cell performance.

[0007] Therefore, how to optimize the connection structure between the anode hydrogen inlet and the distribution zone without significantly increasing structural complexity and manufacturing costs, so as to improve the inlet flow state, reduce local flow resistance and improve hydrogen distribution and transfer capacity, remains an urgent problem to be solved in the existing technology. Summary of the Invention

[0008] To address the aforementioned problems in the prior art, this invention provides a fuel cell anode flow channel with a continuous transition inlet structure and a fuel cell stack including the anode flow channel.

[0009] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0010] This invention provides a fuel cell anode flow channel with a continuous transition inlet structure, applicable to the bipolar plates of a fuel cell stack. The anode flow channel includes a hydrogen inlet, a distribution region, and multiple sub-flow channels. The distribution region is provided with a continuous transition structure, which guides the hydrogen as it enters the multiple sub-flow channels, gradually changing its flow direction and / or flow cross-section to suppress flow separation and the generation of localized eddies.

[0011] In addition, the present invention also provides a fuel cell stack comprising a plurality of single cells, wherein a bipolar plate is disposed between adjacent single cells, and the bipolar plate includes the aforementioned anode flow channel having a continuous transition inlet structure.

[0012] To address the technical problems of abrupt geometric changes in the anode flow channel distribution region and high flow resistance of hydrogen when entering the sub-flow channels in existing technologies, this invention incorporates a continuous transition structure in the distribution region of the anode flow channel. Specifically, this anode flow channel is applied to the bipolar plate of a fuel cell stack and includes a hydrogen inlet, a distribution region, and multiple sub-flow channels connected to the distribution region. The distribution region features a continuous transition structure that guides the hydrogen flow by gradually changing its flow direction and / or flow cross-section as it enters the multiple sub-flow channels from the distribution region.

[0013] During fuel cell operation, hydrogen enters the anode channel from an external hydrogen supply system, first entering the distribution region through the hydrogen inlet. Due to the continuous transition structure in the distribution region, the flow direction and cross-section of hydrogen no longer undergo abrupt changes as it enters each sub-channel; instead, they change smoothly and continuously. This smooth transition flow state avoids the flow separation and local eddy current phenomena commonly found in traditional abrupt structures from a fluid dynamics perspective, thus significantly reducing local flow resistance and pressure drop in the distribution region. Simultaneously, due to the improved flow state, the pressure and velocity fields of hydrogen before entering each sub-channel are more uniformly distributed, laying a solid foundation for subsequent uniform distribution.

[0014] With the above-mentioned configuration, the present invention can effectively reduce the local flow resistance in the anode flow channel distribution area, improve the flow state of hydrogen before it enters the sub-flow channel, and create favorable conditions for achieving uniform distribution of hydrogen among the sub-flow channels, thereby improving the hydrogen supply stability and electrochemical reaction uniformity of the fuel cell.

[0015] To achieve the smooth guiding function of the continuous transition structure, this invention sets the continuous transition structure as a smooth, continuously changing curved surface. This smooth curved surface gradually changes the geometry of the flow channel along the hydrogen flow direction, minimizing the flow resistance experienced by the hydrogen and making the change in flow direction more gradual. This structural form has high manufacturing precision and low flow loss, and can suppress the generation of eddies and flow separation to the greatest extent, making it suitable for high-power-density fuel cell applications with high requirements for flow conditions.

[0016] As another specific implementation of the continuous transition structure, this invention sets the continuous transition structure as a gradual structure composed of multiple progressively changing cross-sections. This gradual structure achieves step-by-step adjustment of the flow cross-section through multiple discrete cross-sectional changes. Although the change is segmented, it still exhibits the characteristics of a continuous transition overall. This structural form reduces manufacturing difficulty while ensuring smooth flow transition, making it suitable for applications sensitive to manufacturing costs. Simultaneously, it effectively suppresses flow separation and the generation of local eddies, reducing local flow resistance in the distribution area.

[0017] To further enrich the implementation methods of continuous transition structures, this invention sets the continuous transition structure as including either a guide surface or a gradually changing cavity. The guide surface, by setting a guide surface of a specific shape, actively guides the change in the hydrogen flow direction; the gradually changing cavity, by expanding or shrinking the cavity cross-section, allows the hydrogen to redistribute its velocity and pressure fields within the cavity. Both structures can achieve a smooth transition in flow direction and flow cross-section, avoiding the flow energy loss caused by traditional abrupt structures, and providing flexible alternatives according to different bipolar plate processing technologies and spatial layout requirements.

[0018] To ensure a uniform hydrogen supply when covering the anode reaction region, this invention arranges multiple sub-channels parallel to each other along the length of the bipolar plate, with consistent spacing between them, to cover their respective anode reaction regions. This parallel, equally spaced arrangement works synergistically with the continuous transition structure of the distribution area: the continuous transition structure ensures uniform hydrogen flow before it enters each sub-channel, while the parallel, equally spaced channel layout ensures that each reaction region receives the same hydrogen supply conditions. The combination of these two factors significantly reduces the differences in hydrogen flow distribution between the sub-channels, providing a more consistent reactant supply environment for the anode reaction region, thereby improving the overall output consistency of the fuel cell.

[0019] To ensure the airtightness and operational safety of the anode flow channel, this invention places the anode flow channel on the anode-side surface of the bipolar plate and provides a sealing structure in the peripheral area of ​​the bipolar plate. This sealing structure, in conjunction with the sealing gasket, prevents hydrogen leakage on the anode side and ensures that the hydrogen flows orderly along the designed flow path. Furthermore, directly machining the anode flow channel onto the bipolar plate surface simplifies the fuel cell stack assembly process and improves structural compactness.

[0020] To apply the aforementioned anode flow channel structure to practical fuel cell products, this invention provides a fuel cell stack comprising multiple individual cells, with bipolar plates disposed between adjacent individual cells. The bipolar plates include the anode flow channel described in any of the preceding technical solutions. By integrating the anode flow channel with a continuous transition structure into the bipolar plates of the stack, the entire stack achieves improved uniformity of hydrogen supply on the anode side, thereby enhancing the performance stability and output consistency of the stack under high power density operating conditions.

[0021] To address the hydrogen supply stability issue caused by fluctuations in cathode-side cooling conditions in open-cathode air-cooled fuel cells, this invention further defines the aforementioned fuel cell stack as an open-cathode fuel cell stack, where the cathode side is connected to ambient air and cooled using forced airflow. In this type of stack, the cathode-side cooling and oxygen supply conditions are significantly affected by the environment, resulting in substantial fluctuations in the internal temperature field and reaction rate distribution, placing higher demands on the uniformity and stability of hydrogen supply to the anode side. This invention, through the design of a continuous transition structure, enhances the stability of hydrogen supply to the anode side, effectively mitigating the adverse effects of cathode-side operating condition fluctuations, thereby improving the overall performance and reliability of the open-cathode air-cooled fuel cell under high power density operating conditions.

[0022] To create a complete hydrogen flow path, this invention incorporates a hydrogen outlet in the anode channel and connects one end of multiple sub-channels to the distribution area and the other end to the hydrogen outlet. During fuel cell operation, hydrogen smoothly enters each sub-channel from the distribution area via a continuous transition structure. After flowing along the length of the sub-channel and participating in the electrochemical reaction, unreacted hydrogen and any inert gases present collect at the end of the sub-channels and are discharged through the hydrogen outlet. This design ensures a continuous and unobstructed hydrogen flow path on the anode side, which is beneficial for maintaining stable pressure within the channel and a continuous supply of reactants.

[0023] To balance the conductivity, mechanical strength, and fabrication feasibility of the bipolar plate, this invention uses a bipolar plate made of metallic or conductive composite materials, with the anode flow channel formed on the surface of the bipolar plate through machining. Metallic materials possess excellent electrical and thermal conductivity, making them suitable for high-power-density fuel cell stacks; conductive composite materials offer advantages such as light weight and corrosion resistance. The anode flow channel is formed directly on the bipolar plate surface through methods such as stamping, etching, or molding, facilitating integrated manufacturing of the flow channel structure, reducing contact resistance, and improving the assembly accuracy and long-term operational reliability of the fuel cell stack.

[0024] This invention, by incorporating a continuous transition structure in the anode flow channel distribution region, allows hydrogen to undergo a smooth transition in flow direction and cross-section before entering the sub-channels. This effectively reduces local flow resistance in the distribution region, improves the uniformity of hydrogen distribution among the sub-channels, and enhances the mass transfer capability on the anode side. Furthermore, this invention further improves the output stability, consistency, and long-term operational reliability of fuel cells, particularly open-cathode air-cooled fuel cells, under high power density operating conditions.

[0025] This invention provides a fuel cell anode flow channel and fuel cell stack with a continuous transition inlet structure, which have the following advantages:

[0026] 1. Effectively reduces local flow resistance in the anode flow channel distribution area.

[0027] In existing technologies, the anode channel inlet and distribution area employ a straight-through or abrupt transition structure. When hydrogen enters the sub-channels, the flow direction and cross-section change abruptly, easily leading to flow separation and localized eddies, resulting in high local flow resistance and pressure drop. This invention incorporates a continuous transition structure in the distribution area, allowing hydrogen to gradually change its flow direction and cross-section as it enters multiple sub-channels, achieving a smooth transition in flow state. Based on fluid mechanics principles, a smooth transition in flow state significantly reduces energy loss. Therefore, this invention effectively reduces local flow resistance and pressure drop in the anode channel distribution area, fundamentally solving the basic defect of "excessive local flow resistance at the anode inlet" in existing technologies.

[0028] 2. Significantly improves the uniformity of hydrogen distribution among the sub-channels.

[0029] In existing technologies, excessive local flow resistance in the inlet region disrupts the pressure and velocity field distributions entering the distribution zone, leading to significant differences in hydrogen flow distribution among the sub-channels. Some sub-channels experience insufficient hydrogen supply, while others have excess hydrogen. This invention reduces local flow resistance in the distribution region through a continuous transition structure, making the hydrogen pressure and velocity fields entering the distribution region more uniform and stable. Based on this, the differences in hydrogen flow distribution among the parallel sub-channels are significantly reduced, allowing each sub-channel to obtain more balanced hydrogen supply conditions. This provides a more consistent reactant supply environment for the anode reaction region, effectively improving the problem of uneven hydrogen supply in sub-channels caused by uneven inlet flow in existing technologies.

[0030] 3. Enhance hydrogen mass transfer capability on the anode side and reduce concentration polarization.

[0031] In existing technologies, uneven hydrogen supply leads to an unreasonable hydrogen concentration distribution on the anode side, which can easily cause localized reaction limitation and intensified concentration polarization under high current density operating conditions. This invention improves the uniformity of hydrogen supply to each sub-channel, resulting in a more reasonable hydrogen concentration distribution on the anode side and improved diffusion mass transfer conditions towards the catalyst layer. Under high current density operating conditions, this invention reduces the probability of localized reaction limitation and concentration polarization, mechanistically enhancing the reaction stability and effective mass transfer capacity on the anode side, thus clearly addressing the problem of "limited mass transfer and intensified polarization under high load conditions" in existing technologies.

[0032] 4. Improve the operational stability and output consistency of fuel cell stacks.

[0033] Based on a series of improvements, including reduced inlet flow resistance, enhanced hydrogen supply uniformity, and improved mass transfer capacity, this invention significantly improves the operational stability and output consistency of fuel cells at the system level. Particularly in fuel cell stacks with an open-type air-cooled cathode, the cooling and oxygen supply conditions on the cathode side are easily affected by the environment, resulting in significant fluctuations in the internal temperature field and reaction rate distribution. This places higher demands on the uniformity and stability of hydrogen supply on the anode side. This invention effectively mitigates these adverse effects by enhancing the stability of hydrogen supply on the anode side, thereby improving the overall performance and reliability of open-type air-cooled fuel cells under high power density operating conditions. For specific effects, please refer to the appendix. Figure 2 The optimization significantly improved the uniformity of hydrogen flow distribution among the sub-channels.

[0034] 5. It has a simple structure, controllable manufacturing costs, and good prospects for engineering applications.

[0035] While achieving the aforementioned technical effects, this invention does not significantly increase structural complexity or manufacturing costs. The continuous transition structure can be directly formed on the surface of the bipolar plate using conventional processing techniques such as stamping, etching, or molding, without requiring additional components or complex assembly processes. The continuous transition structure can be selected from various forms, including smooth, continuously changing curved surfaces, gradually changing structures composed of multiple cross-sections, flow-guiding surfaces, or gently changing cavities. It allows for flexible selection based on different processing conditions and cost requirements, demonstrating promising engineering application prospects and industrialization potential.

[0036] In summary, this invention, through structural optimization of the anode flow channel distribution region, systematically solves the technical problems of high local flow resistance at the anode inlet, uneven hydrogen supply, and limited mass transfer capacity in the prior art in a simple and low-cost manner. It significantly improves the performance stability, output consistency, and long-term operational reliability of fuel cells, especially open-cathode air-cooled fuel cells, under high power density operating conditions, and has outstanding substantive features and significant progress. Attached Figure Description

[0037] 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. 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.

[0038] Figure 1 This is a schematic diagram of a fuel cell stack in an embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram of a bipolar plate in an embodiment of the present invention;

[0040] Figure 3 This is a schematic diagram of the anode flow field in an embodiment of the present invention;

[0041] Figure 4 This is a schematic diagram of the anode flow field from another perspective in an embodiment of the present invention;

[0042] Figure 5 This is a schematic diagram comparing traffic flow before and after optimization in an embodiment of the present invention.

[0043] Explanation of the reference numerals in the figure:

[0044] 1—Cathode open fuel cell stack; 2—Bipolar plate; 3—Anode flow channel; 4—Hydrogen inlet; 5—Distribution area; 6—Sub-flow channel; 7—Hydrogen outlet. Detailed Implementation

[0045] The technical solution of the present invention will be clearly and completely described below with reference to embodiments thereof. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0046] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this 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. Therefore, they should not be construed as limitations on this invention. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the embodiments of this invention, all technical features can be flexibly combined according to actual engineering needs, as long as the combined technical solution can achieve the inventive purpose of this invention.

[0047] Example:

[0048] like Figure 1-5 As shown, this embodiment provides a fuel cell stack, specifically an open-cathode fuel cell stack 1. This stack uses forced airflow for cooling, and its cathode side is directly connected to the ambient air, eliminating the need for a closed cathode flow channel. In an open-cathode fuel cell stack, the cooling and oxygen supply conditions on the cathode side are significantly affected by the environment, resulting in uneven temperature field and reaction rate distribution within the stack. This places higher demands on the uniformity and stability of hydrogen supply on the anode side. Therefore, the rational design of the anode flow channel structure has a significant impact on the overall performance of the stack.

[0049] The cathode open-type fuel cell stack 1 is formed by stacking multiple individual cells sequentially along the stacking direction. The individual cells are electrically connected, gas-separated, and structurally supported by bipolar plates 2. In the stacking direction, the bipolar plates 2 are closely attached to other bipolar plates or membrane electrode assemblies to form a complete stack structure.

[0050] Bipolar plates 2 are disposed between adjacent single cells, with one side forming an anode flow channel 3 and the other side forming a cathode reaction or cooling region. Bipolar plates 2 are typically made of metallic materials (such as stainless steel or titanium alloys) or conductive composite materials, and their main functions include current collection, gas distribution, sealing support, and heat conduction.

[0051] The outer periphery of bipolar plate 2 is equipped with a sealing structure (not shown in the figure). This sealing structure is used to cooperate with a sealing gasket (such as a rubber sealing ring) to form a reliable sealing interface during fuel cell stack assembly. Because hydrogen is flammable and explosive, preventing hydrogen leakage is a fundamental requirement for the safe operation of fuel cells. By setting up the sealing structure, hydrogen can be effectively prevented from leaking from the anode side to the external environment or entering the cathode side, ensuring the safety and reliability of the fuel cell stack.

[0052] An anode flow channel 3 is formed on the anode side surface of the bipolar plate 2. The anode flow channel 3 is used to guide the flow of hydrogen on the anode side and supply reactants to the reaction zone. Specifically, the anode flow channel 3 includes a hydrogen inlet 4, a distribution zone 5, multiple sub-flow channels 6 arranged parallel to each other along the length direction, and a hydrogen outlet 7.

[0053] Hydrogen inlet 4 is located at the beginning of the anode flow channel 3 and is used to receive hydrogen supplied by an external hydrogen supply system. Hydrogen inlet 4 is connected to the distribution area 5, allowing hydrogen to enter the anode flow channel 3 from the external hydrogen supply system.

[0054] The distribution region 5 is located between the hydrogen inlet 4 and multiple sub-channels 6, and is a key transition area connecting the hydrogen inlet and the sub-channels. The key to this invention lies in the optimized design of the structure of the distribution region 5.

[0055] Specifically, the distribution region 5 is configured as a continuous transition structure, which is used to gradually change the flow direction and cross-section of the hydrogen flowing in from the hydrogen inlet 4, so as to guide the hydrogen smoothly into multiple sub-channels 6. This continuous transition structure can be a smooth and continuous curved surface structure, or a gradually changing structure composed of multiple cross-sections.

[0056] The so-called smooth and continuous curved surface structure refers to the transition surface from hydrogen inlet 4 to distribution area 5 using a smooth curve or curved surface connection, without any sharp corners or abrupt changes, allowing hydrogen to achieve continuous changes in flow direction and flow cross-section as it flows through this area. The so-called gradual change structure composed of multiple progressively changing cross-sections refers to the smooth adjustment of the flow state achieved through a series of transition sections with gradually changing cross-sectional dimensions. The cross-sectional change amplitude of each transition section is small, and multiple transition sections are connected in series to form an overall gradual effect.

[0057] In this embodiment, the distribution area 5 may further be provided with a flow-guiding surface or a gradually changing cavity to guide hydrogen gas smoothly from the hydrogen inlet 4 to multiple sub-channels 6. The flow-guiding surface refers to a guiding surface with a specific geometric shape that can actively guide the flow direction of hydrogen gas, allowing it to flow smoothly to each sub-channel along a preset path; the gradually changing cavity refers to a cavity structure with gradually changing cross-sectional dimensions, which allows the speed and pressure distribution of hydrogen gas to be gradually adjusted when it flows within the cavity.

[0058] By configuring the distribution region 5 as a continuous transition structure, the flow direction and cross-section of hydrogen gas can change gradually and continuously as it enters the distribution region 5 from the hydrogen inlet 4 and then enters the sub-channel 6, rather than abruptly as in existing technologies. This structural design, based on fluid dynamics principles, can effectively suppress flow separation and the generation of local eddies, thereby significantly reducing the local flow resistance in the inlet region.

[0059] Multiple sub-channels 6 are arranged parallel to each other along the length of the bipolar plate 2, with consistent spacing between them, to cover the corresponding anode reaction regions. Each sub-channel 6 is connected at both ends to the distribution area 5 on the inlet side and the confluence area on the outlet side, respectively, allowing hydrogen to form a continuous flow path on the anode side. The parallel arrangement of the sub-channels 6, under the premise of uniform inlet pressure, and consistent spacing, ensures that the flow resistance of each sub-channel is essentially the same, which is beneficial for achieving uniform flow distribution in each sub-channel.

[0060] Hydrogen outlet 7 is located at the end of anode channel 3 to collect residual hydrogen after the reaction and discharge it from anode channel 3. Hydrogen outlet 7 is connected to the outlet ends of multiple sub-channels 6 to form a confluence area.

[0061] In the anode channel 3, the hydrogen inlet 4, distribution area 5, multiple sub-channels 6, and hydrogen outlet 7 are sequentially connected to form a continuous hydrogen flow path. Specifically, the hydrogen inlet 4 is connected to one end of the distribution area 5, the other end of the distribution area 5 is connected to the inlet ends of the multiple sub-channels 6, and the outlet ends of each sub-channel 6 are connected to the hydrogen outlet 7. This continuous flow path design ensures that hydrogen can form an orderly flow on the anode side, avoiding the generation of dead zones or backflow phenomena.

[0062] The hydrogen inlet 4, distribution area 5, multiple sub-channels 6, and hydrogen outlet 7 of the anode flow channel 3 are integrally formed on the surface of the bipolar plate 2. They are typically formed directly using methods such as stamping, etching, molding, or machining. This integrally formed structure offers the following advantages: it eliminates the need for additional connectors or seals, reducing the number of parts; it provides high relative positioning accuracy between the flow channels, ensuring uniform flow; it has low manufacturing costs, making it suitable for mass production; and it eliminates the risk of leakage due to poor connections.

[0063] The following combination Figures 1-4 The working process and working principle of the fuel cell stack in this embodiment are described in detail.

[0064] 1. Hydrogen entry and flow transition process

[0065] During fuel cell operation, hydrogen enters the cathode open fuel cell stack 1 from an external hydrogen supply system and enters the anode side through the anode flow channel 3 on the bipolar plate 2. Specifically, hydrogen first enters from the hydrogen inlet 4 and then flows into the distribution area 5.

[0066] Because the distribution region 5 is configured as a continuous transition structure (e.g., a smooth, continuous curved surface or a gradually changing structure composed of multiple cross-sections), the flow direction and cross-section of hydrogen gas change gradually and continuously as it flows through this region, rather than abruptly. This smooth transition process avoids the flow separation and local eddy current phenomena commonly found in traditional straight-through or abrupt inlet structures. Based on fluid mechanics principles, a smooth transition of the flow state can significantly reduce energy loss; therefore, this embodiment can effectively reduce the local flow resistance and pressure drop in the anode channel distribution region 5.

[0067] Within distribution area 5, if a flow-guiding surface or a gradually changing cavity is further provided, hydrogen will flow more smoothly under the guidance of these structures, and the pressure and velocity fields will be more uniformly distributed.

[0068] 2. Hydrogen distribution and uniform hydrogen supply process

[0069] With the reduced local flow resistance and improved inlet flow conditions in distribution region 5, the pressure and velocity fields of the hydrogen entering distribution region 5 tend to become uniform and stable. Subsequently, the hydrogen is distributed into multiple parallel sub-channels 6.

[0070] Because the flow state in distribution area 5 is improved, the difference in hydrogen flow rate entering each sub-channel 6 is significantly reduced, and each sub-channel 6 can obtain more balanced hydrogen supply conditions. Therefore, this embodiment can effectively improve the problem of uneven hydrogen supply in sub-channels caused by uneven inlet flow in the prior art, reduce the situation of insufficient or excessive hydrogen in local areas, and provide a more consistent reactant supply environment for the anode reaction area.

[0071] 3. Electrochemical reactions and mass transfer processes

[0072] Hydrogen gas in each sub-channel 6 flows along the length of the channel. During the flow, the hydrogen gas diffuses from the anode diffusion layer toward the catalyst layer and participates in the electrochemical reaction.

[0073] Because the hydrogen supply uniformity among the sub-channels 6 is improved, the hydrogen concentration distribution on the anode side is more reasonable, and the diffusion mass transfer conditions of hydrogen towards the catalyst layer are improved accordingly. Under high current density operating conditions, this embodiment can reduce the probability of local reaction restriction and concentration polarization, thereby enhancing the reaction stability and effective mass transfer capability on the anode side from a mechanistic perspective.

[0074] 4. Hydrogen emission process

[0075] The residual hydrogen gas after the reaction continues to flow along the sub-channel 6, eventually converging at the hydrogen outlet 7 and being discharged from the anode channel 3.

[0076] like Figure 5 As shown, compared with the anode flow channel using a straight-through or abrupt inlet structure, the anode flow channel 3 in this embodiment has significantly reduced local flow resistance and pressure drop in the distribution region 5, and the hydrogen supply uniformity among multiple sub-flow channels 6 is significantly improved.

[0077] Specifically, by setting a continuous transition structure in the allocation region 5, the present invention achieves the following technical effects:

[0078] First, it effectively reduces local flow resistance and pressure drop in the anode channel distribution area. Because hydrogen gas completes a smooth transition in flow direction and cross-section before entering the sub-channel, it avoids flow separation and local eddy current phenomena in traditional abrupt structures, and significantly reduces energy loss based on fluid dynamics principles.

[0079] Second, it significantly improves the uniformity of hydrogen distribution among the sub-channels. With the reduction of local flow resistance at the inlet and the improvement of the inlet flow state, the hydrogen pressure field and velocity field entering the distribution region 5 tend to be uniform and stable, and each sub-channel 6 can obtain more balanced hydrogen supply conditions, providing a more consistent reactant supply environment for the anode reaction region.

[0080] Third, it enhances the hydrogen mass transfer capability on the anode side. Due to the improved uniformity of hydrogen supply in each sub-channel 6, the hydrogen concentration distribution on the anode side is more reasonable, and the diffusion mass transfer conditions of hydrogen towards the catalyst layer are improved accordingly, reducing the probability of local reaction restriction and concentration polarization.

[0081] Fourth, it improves the operational stability and output consistency of fuel cells. Especially in fuel cell stacks with an open air-cooled cathode structure, the cooling and oxygen supply conditions on the cathode side are easily affected by the environment, resulting in large fluctuations in the internal temperature field and reaction rate distribution. This invention effectively mitigates the above-mentioned adverse effects by enhancing the hydrogen supply stability on the anode side, thereby improving the overall performance and reliability of fuel cells under high power density operating conditions.

[0082] Those skilled in the art should understand that, without departing from the overall technical concept and purpose of this invention, other structural forms can be used to achieve the same or similar technical effects. For example:

[0083] Alternative Option 1: The continuous transition structure adopts a gradual structure composed of multiple progressively changing cross-sections. This gradual structure achieves step-by-step adjustment of the flow cross-section through multiple discrete cross-sectional changes. Although its change method is segmented, it still exhibits the characteristics of a continuous transition overall, reducing the processing difficulty while ensuring a smooth flow transition.

[0084] Alternative Option 2: A continuous transition structure including a guide surface. This guide surface is located at the connection between the distribution area 5 and each sub-channel 6. Through a guide surface of a specific shape, it actively guides the change in the hydrogen flow direction, achieving a smooth transition in flow direction and flow cross-section.

[0085] Alternative Option 3: A continuous transition structure including a gradually changing cavity. This gradually changing cavity is located between the distribution region 5 and each sub-channel 6. By expanding or shrinking the cavity cross-section, the velocity and pressure fields of hydrogen are redistributed within the cavity, avoiding the flow energy loss caused by traditional abrupt structures.

[0086] Alternative Option 4: The anode flow channel 3 can be integrally formed within the bipolar plate 2, or it can be achieved through different processing techniques or structural integration methods. The bipolar plate 2 can be made of metal material by stamping or of conductive composite material by molding. As long as its distribution area 5 has the functional characteristics of smoothly transitioning the hydrogen flow state, it can achieve the invention's objective of reducing flow resistance, increasing flow rate, and enhancing the stability of hydrogen supply on the anode side.

[0087] Although the above-mentioned structural schemes differ in specific geometry or implementation, their technical principles are the same. They all solve the problems of high inlet flow resistance, limited flow rate, and uneven hydrogen supply in the prior art by improving the flow conditions in the anode flow channel distribution area, and should all be considered to fall within the protection scope of this invention.

[0088] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A fuel cell anode flow channel with a continuous transition inlet structure, applied to the bipolar plate (2) of a fuel cell stack, characterized in that, The anode flow channel (3) includes: Hydrogen inlet (4); Allocation area (5); Multiple sub-channels (6) are connected to the distribution area (5); The distribution area (5) is provided with a continuous transition structure, which is used to guide hydrogen gas to gradually change its flow direction and / or flow cross section as it enters the multiple sub-channels (6) from the distribution area (5) in order to suppress flow separation and the generation of local eddies.

2. The fuel cell anode flow channel according to claim 1, characterized in that, The continuous transition structure is a smooth, continuously changing curved surface structure.

3. The fuel cell anode flow channel according to claim 1, characterized in that, The continuous transition structure is a gradual structure composed of multiple cross-sections that change step by step.

4. The fuel cell anode flow channel according to claim 1, characterized in that, The continuous transition structure includes a flow-guiding surface or a gradually changing cavity.

5. The fuel cell anode flow channel according to claim 1, characterized in that, The multiple sub-channels (6) are arranged parallel to each other along the length of the bipolar plate (2), and the spacing between each sub-channel (6) is consistent, which is used to cover the corresponding anode reaction area.

6. The fuel cell anode flow channel according to claim 1, characterized in that, The anode flow channel (3) is disposed on the anode side surface of the bipolar plate (2), and the outer periphery of the bipolar plate (2) is provided with a sealing structure.

7. A fuel cell stack, characterized in that, It includes multiple single cells, with a bipolar plate (2) disposed between adjacent single cells, the bipolar plate (2) including an anode flow channel (3) according to any one of claims 1 to 6.

8. The fuel cell stack according to claim 7, characterized in that, The fuel cell stack is an open-cathode fuel cell stack (1), with its cathode side connected to the ambient air and cooled by forced airflow.

9. The fuel cell stack according to claim 7, characterized in that, The anode channel (3) also includes a hydrogen outlet (7), one end of the plurality of sub-channels (6) is connected to the distribution area (5), and the other end is connected to the hydrogen outlet (7).

10. The fuel cell stack according to claim 7, characterized in that, The bipolar plate (2) is made of metal or conductive composite material, and the anode channel (3) is formed on the surface of the bipolar plate (2) by processing.

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