Cathode flow channel structure for proton exchange membrane fuel cell based on corner flow guide structure

Abstract

This invention discloses a cathode flow channel structure for a proton exchange membrane fuel cell based on an angular flow guide structure, belonging to the field of proton exchange membrane fuel cell technology. The structure includes a flow field plate with a cathode flow channel on it. The cathode flow channel has a flow channel inlet, a flow channel outlet, and a flow channel bottom surface. Multiple angular flow guide structures are arranged at intervals along the gas flow direction on the bottom surface of the flow channel within the cathode flow channel. Each angular flow guide structure includes a peak, a windward ridge, a flow guide side, a windward surface, a leeward surface, a leeward ridge, and a bottom surface of the flow guide structure, with the peak facing the flow channel inlet. This structure allows the gas to form a wheat-ear-shaped flow field at the top surface of the flow channel and a globally symmetrical double-vortex flow field within the flow channel. This promotes oxygen transport to the gas diffusion layer and facilitates the migration and discharge of water seeping from the gas diffusion layer to both sides of the flow channel, improving the oxygen supply and drainage performance on the cathode side, and enhancing the fuel cell output performance and operational stability.

Description

Technical Field

[0001] This invention relates to the field of proton exchange membrane fuel cell technology, and specifically to a proton exchange membrane fuel cell cathode flow channel structure based on an angular flow guide structure. Background Technology

[0002] Proton exchange membrane fuel cells are a type of high-efficiency, clean energy device that directly converts the chemical energy of hydrogen and oxygen into electrical energy. They have advantages such as high energy conversion efficiency, low operating temperature, fast start-up speed, and environmental friendliness, and have broad application prospects in transportation, distributed power generation, and portable power supplies.

[0003] As a crucial component of proton exchange membrane fuel cells (PEMFCs), the flow field plate's flow channel structure not only affects the distribution and transport of reactant gases within the cell but also directly impacts the removal of product water and the overall performance of the cell. The oxygen transport process on the cathode side is particularly complex, and the water generated by the electrochemical reaction is primarily concentrated there. An improperly designed cathode flow channel can easily lead to insufficient oxygen supply, limited mass transfer in the diffusion layer, and accumulation of liquid water. This can result in intensified concentration polarization, decreased output performance, and even localized blockage, affecting the stable operation of the cell.

[0004] In existing proton exchange membrane fuel cells, the cathode flow channel mostly adopts a traditional direct-flow structure. Although this type of structure is relatively simple to manufacture and has a small pressure drop, the fluid flow along the mainstream direction is relatively uniform, and there is insufficient lateral disturbance within the flow channel, making it difficult to effectively enhance the convective mass transfer effect at the interface between the flow channel and the gas diffusion layer. Under high current density operating conditions, the traditional direct-flow structure is prone to problems such as reduced oxygen concentration and poor moisture removal in the downstream region, thus limiting further improvements in battery performance.

[0005] Therefore, there is an urgent need to propose a novel flow channel structure that can effectively improve the flow state, enhance oxygen transport, and promote water discharge within the cathode flow channel, so as to improve the mass transfer performance and output performance of the cathode side of the proton exchange membrane fuel cell. Summary of the Invention

[0006] The purpose of this invention is to address the problems in existing proton exchange membrane fuel cell cathode direct current channel structures, such as the single gas flow pattern, insufficient lateral disturbance, weak mass transfer capacity at the interface between the channel and the gas diffusion layer, and difficulty in timely discharge of product water. This invention provides a proton exchange membrane fuel cell cathode channel structure based on an angled flow guide structure to improve the flow state within the cathode channel, enhance oxygen transport to the gas diffusion layer, and promote the migration and discharge of reaction-generated water. This alleviates the problem of limited mass transfer on the cathode side and improves the output performance and operational stability of the fuel cell.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A proton exchange membrane fuel cell cathode flow channel structure based on an angular flow guide structure includes a flow field plate, on which a cathode flow channel is disposed. The cathode flow channel has a flow channel inlet, a flow channel outlet, and a flow channel bottom surface. Multiple angular flow guide structures are disposed inside the cathode flow channel, and the multiple angular flow guide structures are arranged at intervals on the bottom surface of the flow channel along the gas flow direction.

[0008] The angular guide structure includes a peak, a windward ridge, a guide side, a windward surface, a leeward surface, a leeward ridge, and a bottom surface. After the gas enters the cathode channel through the inlet, it comes into contact with the windward surface of the angular guide structure and undergoes local acceleration and diversion under the influence of the windward ridge and the peak. Subsequently, the airflow deflects to both sides along the windward surface and the guide side, and further flow around and wake disturbances are formed near the leeward surface and the leeward ridge, thereby creating a continuous three-dimensional guiding effect inside the channel.

[0009] Furthermore, the angular flow guiding structure is symmetrically arranged along the windward ridge line and the leeward ridge line.

[0010] Furthermore, the ends of the windward ridge line, the leeward ridge line, the boundary line between the guide side and the windward surface, and the boundary line between the guide side and the leeward surface are respectively connected to the peak.

[0011] Furthermore, the peak of the angular flow guide structure is positioned towards the flow channel outlet.

[0012] Furthermore, by arranging multiple angular guide structures sequentially along the length of the channel, the airflow can form a periodically expanding diversion trajectory on the top surface, exhibiting an overall "wheat ear" flow characteristic. This flow characteristic indicates that while the gas is transported along the mainstream direction, it continuously diffuses to both sides of the channel and re-converges, thereby enhancing lateral disturbance and fluid mixing within the channel and improving the uniformity of the flow field distribution.

[0013] Furthermore, the angular guide structure can induce the airflow to form a symmetrically distributed double vortex flow field within the cross-sectional area of ​​the flow channel. This double vortex flow field covers the main area of ​​the flow channel, which can enhance the momentum exchange between the mainstream area and the area near the bottom of the flow channel, allowing the gas to be transported more effectively to the bottom of the flow channel and the gas diffusion layer interface, thereby strengthening the convective mass transfer process on the cathode side.

[0014] Furthermore, since the angular guide structure guides and pressurizes the fluid, the gas can migrate more effectively from the main flow channel area to a position closer to the gas diffusion layer after flowing through the angular guide structure. This allows oxygen to be renewed more quickly near the interface between the flow channel and the gas diffusion layer, and further transferred into the interior of the gas diffusion layer, thereby improving the oxygen supply conditions on the cathode side.

[0015] Furthermore, at the interface between the flow channel and the gas diffusion layer, influenced by the lateral flow induced by the angular guiding structure, the gas near the interface can flow from the center towards the two side walls. This flow pattern facilitates the timely sweeping of liquid water seeping from the gas diffusion layer to the areas on both sides of the flow channel, and its discharge from the flow channel under the carrying action of the mainstream, thereby reducing the retention and accumulation of liquid water near the interface.

[0016] As a preferred option, multiple angular guide structures are continuously arranged along the length of the flow channel to ensure that the flow channel maintains a strong guiding and disturbance effect throughout its length. By adjusting the height, spacing, and arrangement density of the angular guide structures, the intensity of flow field disturbance, the distribution range of the double vortex, and the mass transfer effect at the interface between the flow channel and the gas diffusion layer can be further controlled to meet the design requirements of the cathode flow channel under different operating conditions.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) Significantly improves the flow state and enhances the flow field organization within the cathode channel. By incorporating an angular guiding structure within the cathode channel, continuous lateral disturbance, local acceleration, and flow diversion are generated as the fluid moves along the mainstream direction, altering the single-axial flow state of a traditional direct-flow channel. Specifically, a periodic "wheat ear" shaped flow trajectory is formed at the top surface, and a symmetrical double-vortex flow field covering the main area of ​​the channel is formed at the outlet. These flow characteristics enhance fluid mixing and momentum exchange within the channel, improve the uniformity of the flow field distribution, and strengthen the three-dimensional mass transfer capability within the cathode channel. 2) Enhanced oxygen transport into the gas diffusion layer. The directional flow and double-vortex flow field induced by the angular guide structure enable gas to migrate more effectively from the main flow channel region to the bottom of the flow channel and the gas diffusion layer interface, and further into the gas diffusion layer. This facilitates the compression of oxygen into the gas diffusion layer, improving oxygen supply conditions on the cathode side. This structure helps reduce the oxygen concentration gradient, shrink the downstream low-oxygen region, improve the uniformity of oxygen supply in the reaction region, and has a positive effect on mitigating concentration polarization.

[0018] 3) Promotes the migration and discharge of product water to both sides of the flow channel. At the interface between the flow channel and the gas diffusion layer, the present invention induces a transverse flow that develops from the center to both side walls, which can promptly sweep the liquid water seeping from the gas diffusion layer to the areas on both sides of the flow channel and discharge it with the airflow. This structure helps to reduce the accumulation of liquid water at the interface, reduce the risk of flooding, keep the gas transmission channel unobstructed, and at the same time help to further ensure oxygen transmission capacity; 4) Improve fuel cell output performance and operational stability. By simultaneously improving the gas transport conditions on the cathode side and the product water discharge conditions, it is helpful to increase the effective reaction area of ​​the membrane electrode reaction region, enhance the uniformity of membrane current density distribution, improve the output capacity of the fuel cell at higher current densities, and improve its operational stability. Attached Figure Description

[0019] Figure 1 The present invention provides a schematic diagram of a proton exchange membrane fuel cell cathode flow channel structure based on an angular flow guide structure. (a) is a three-dimensional perspective view, and (b) is a top view. Figure 2 The schematic diagram of the angular flow guiding structure provided by the present invention is shown in (a) as a three-dimensional oblique view, (b) as a top view, and (c) as a side view. Figure 3 Side-direction trace diagram comparing the improved cathode flow channel provided by the present invention with a conventional DC flow channel; Figure 4 Top surface directional trace diagram comparing the improved cathode flow channel provided by the present invention with a conventional DC flow channel; Figure 5 An exit direction trace diagram comparing the improved cathode flow channel provided by the present invention with that of a conventional DC flow channel; Figure 6 A comparison diagram of polarization curves between the improved cathode flow channel and the conventional DC flow channel provided by this invention; Figure 7 A comparison diagram of the transverse mid-section membrane current density of the improved cathode flow channel provided by this invention and the conventional DC flow channel proton exchange membrane (PEM) under 0.4 V operating conditions; Figure 8 A comparison diagram of the water mole fraction distribution at the interface between the improved cathode flow channel provided by this invention and the conventional direct current flow channel under a 0.4 V operating condition. Figure 9 A comparison diagram of the oxygen mole fraction distribution at the contact surface between the improved cathode flow channel provided by this invention and the traditional DC flow channel under a 0.4 V operating condition. Figure 10 A schematic diagram of a proton exchange membrane fuel cell structure based on an angular flow guide structure is provided for this invention. In the figure: 1. Flow field plate; 2. Angular guide structure; 3. Flow channel inlet; 4. Flow channel outlet; 5. Flow channel bottom surface; 6. Peak; 7. Windward ridge line; 8. Guide side; 9. Windward surface; 10. Leeward surface; 11. Leeward ridge line; 12. Bottom surface of guide structure. Detailed Implementation

[0020] To make the technical problems solved, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. This invention is provided with accompanying drawings, which are part of the disclosure of this invention and are mainly used to illustrate the embodiments. These drawings, in conjunction with the relevant descriptions in the specification, explain the operating principles of the embodiments. It should be understood that the specific embodiments described herein are only for explaining this invention and are not intended to limit this invention.

[0021] like Figure 10 As shown, a proton exchange membrane fuel cell structure based on an angular flow guide structure comprises, from top to bottom, an anode flow field plate, an anode gas diffusion layer, an anode catalyst layer, a proton exchange membrane, a cathode catalyst layer, a cathode gas diffusion layer, and a cathode flow field plate; this invention provides a cathode flow channel structure for a proton exchange membrane fuel cell based on an angular flow guide structure.

[0022] like Figures 1-2 As shown, the feature is that it includes a flow field plate 1, a flow channel inlet 3, a flow channel outlet 4, and a flow channel bottom surface 5; multiple angular flow guiding structures 2 are provided in the cathode flow channel, and the multiple angular flow guiding structures 2 are arranged at intervals on the flow channel bottom surface 5 along the gas flow direction.

[0023] An angular flow guide structure 2 is disposed inside the cathode flow channel to guide, split, and turbulent the gas entering the flow channel. The angular flow guide structure 2 includes a peak 6, a windward ridge 7, a flow guide side 8, a windward surface 9, a leeward surface 10, a leeward ridge 11, and a bottom surface 12. The bottom surface 12 of the flow guide structure is connected to the bottom surface 5 of the flow channel, so that the angular flow guide structure 2 is fixedly disposed inside the cathode flow channel.

[0024] The angular guide structure 2 is an overall angular guide, with its front end converging to form a peak 6. The peak 6 is connected to the windward ridge 7 and the leeward ridge 11. The windward ridge 7 and the leeward ridge 11 divide the outer surface of the angular guide structure 2 into a windward surface 9, a leeward surface 10, and guide side surfaces 8 located on both sides. The windward surface 9 faces the flow channel inlet 3 and is used for initial guidance and diversion of the incoming gas. The leeward surface 10 faces away from the flow channel inlet 3 and is used to form a wake disturbance after the gas flows through the angular guide structure 2. The guide side surfaces 8 are used to guide the gas to deflect to both sides of the flow channel.

[0025] In this embodiment, multiple angular guide structures 2 are continuously arranged along the length of the cathode flow channel, with intervals maintained between adjacent angular guide structures 2, so that the gas is continuously guided and disturbed during the flow process. Preferably, the multiple angular guide structures 2 are arranged sequentially along the bottom surface 5 of the flow channel, so that the fluid can periodically generate diversion, deflection and re-convergence effects when flowing through each angular guide structure 2, thereby forming a continuous flow field enhancement effect throughout the entire cathode flow channel.

[0026] The angular flow guiding structure 2 described in this invention can be adjusted in height, spacing and arrangement density according to actual application needs to change the disturbance intensity of fluid in the cathode channel, lateral transport capacity and mass transfer effect at the interface between the channel and the gas diffusion layer. However, the basic concept is to set the angular flow guiding structure 2 in the cathode channel to achieve simultaneous enhancement of oxygen transport and product water discharge.

[0027] The angular flow guide structure described in this invention has a height of 0.5-0.95mm and a spacing of 2-4mm, and the height and spacing can be combined in certain ways. Taking a height of 0.5mm combined with a spacing of 4mm and a height of 0.95mm combined with a spacing of 2mm as examples, compared to traditional DC channels, it has optimized effects on overall convection and battery performance. Figures 3-5 As shown, the angular guide structures with a height of 0.5 mm and a spacing of 4 mm create a relatively significant convection effect in the longitudinal direction, but the lateral convection effect is weak. In contrast, the angular guide structures with a height of 0.95 mm and a spacing of 2 mm exhibit strong convection effects in both the longitudinal and lateral directions, forming a "wheat ear" shaped flow field laterally and a symmetrical double-vortex flow field throughout the entire domain. Figure 6 As shown, compared to traditional DC channels, the current density of the angled current-conducting structure with a height of 0.5mm and a spacing of 4mm, and a height of 0.95mm and a spacing of 2mm, respectively, is increased by 2.01% and 6.84% under 0.2V conditions. Figure 7 As shown, compared to traditional DC channels, the average membrane current density of the PEM transverse mid-section increased by 0.80% and 2.66%, respectively, with the angular current-conducting structure having a height of 0.5mm and a spacing of 4mm, and the angular current-conducting structure having a height of 0.95mm and a spacing of 2mm, respectively, under 0.4 V operating conditions. Figure 8 As shown, compared to traditional direct current channels, the average water mole fraction at the interface between the flow channel and the GDL (Gas-Diverter) is reduced by 7.38% and 27.25%, respectively, under a 0.95mm height and 2mm spacing combination, compared to 0.5mm height and 4mm spacing combination. Figure 9 As shown, compared with the traditional DC channel, the average oxygen mole fraction at the interface between the flow channel and the GDL is increased by 2.61% and 9.71% respectively when the angled flow guide structure with a height of 0.5 mm and a spacing of 4 mm and a height of 0.95 mm and a spacing of 2 mm is used at a height of 0.95 mm and a height of 2 mm, respectively, under the condition of 0.4 V.

[0028] Working principle: The peak 6 of the angular guide structure 2 faces the outlet 4 of the flow channel. When the gas flows past the peak 6, it is split and locally accelerated under the action of the peak 6 and the windward ridge 7, and deflected along the windward surface 9 and the guide side 8 towards both sides of the flow channel and near the bottom surface 5 of the flow channel. Since a low-pressure area is formed behind the leeward surface 10 and the leeward ridge 11, the airflow leaves the surface of the angular guide structure 2 after bypassing the peak 6 and the windward ridge 7, and re-converges and is entrained inside the flow channel, thus forming a periodic turbulent flow around the angular guide structure 2.

[0029] After multiple angular guide structures 2 are arranged sequentially along the flow channel direction, the gas no longer maintains the single axial flow state of a traditional direct-flow channel. Instead, under the action of each angular guide structure 2, it continuously undergoes diversion, deflection, re-convergence, and entrainment, forming periodic forced convection perpendicular to the mainstream direction of the flow channel. This flow pattern makes the flow field distribution more uniform and enhances the gas transport capacity towards the gas diffusion layer (GDL) without significantly affecting the gas permeability within the flow channel.

[0030] Furthermore, the gas flow trajectory in the top direction exhibits a periodic expansion and contraction pattern, forming a flow characteristic similar to a "wheat ear." In the outlet direction, the gas forms a symmetrically distributed double-vortex flow field within the channel cross-section. This double-vortex flow field covers the main area of ​​the channel, which on the one hand promotes the migration of oxygen in the mainstream area towards the bottom of the channel and the GDL interface, and further pressurizes it into the GDL, thereby enhancing the oxygen supply on the cathode side; on the other hand, it allows the gas near the interface between the channel and the GDL to flow from the middle towards the two side walls, which is beneficial for blowing the liquid water seeping from the GDL to the two side walls of the channel and discharging it, thus improving the drainage capacity and water management capacity on the cathode side.

[0031] To verify the effectiveness of the proton exchange membrane fuel cell cathode flow channel structure based on the angular flow guide structure described in this invention, a three-dimensional model of the cathode flow channel was performed, and the flow state and mass transfer characteristics within the flow channel were analyzed using numerical simulation.

[0032] like Figure 3 As shown, when the fluid flows through the angular guide structure 2, it exhibits obvious velocity stratification and vertical disturbance characteristics in the lateral direction. Compared with the traditional direct flow channel, after setting the angular guide structure 2, the fluid no longer flows smoothly in a single direction, but forms a more significant deflection and entrainment effect before and after the guide structure, indicating that the angular guide structure 2 can effectively enhance the three-dimensional flow within the channel.

[0033] like Figure 4As shown, in the top direction, the fluid exhibits a periodic splitting and re-convergence process under the action of multiple angular guide structures 2, forming a "wheat ear" shaped flow trajectory. This result indicates that while the gas flows along the flow channel, it continuously diffuses to both sides and re-converges, thereby enhancing lateral disturbance and fluid mixing within the flow channel and making the flow field distribution more uniform.

[0034] like Figure 5 As shown, in the outlet direction, the fluid forms a symmetrical double-vortex flow field within the channel cross-section. Specifically, a portion of the fluid is deflected towards the bottom and sides of the channel under the action of the angular guide structure 2, while another portion flows back towards the central region under the low-pressure entrainment effect in the leeward region. The two portions of fluid form vortices moving in the same direction along the circumference within the cross-section, thereby enhancing the convection effect and momentum exchange within the cross-section. This double-vortex flow field is beneficial for pressurizing oxygen into the GDL and promotes the flow of gas near the interface from the center to both sides, thereby driving the liquid water to migrate towards the channel sidewalls.

[0035] like Figure 6 The figure shown is a comparison of the polarization curves of the improved cathode flow channel of this invention and the traditional DC flow channel. Figure 6 It can be seen that after adopting the angular flow guiding structure 2 described in this invention, the fuel cell exhibits better output characteristics in the higher current density region, indicating that this invention can improve the output performance of the fuel cell by improving the flow state and mass transfer conditions in the cathode flow channel.

[0036] like Figures 7 to 9 As shown, Figure 7 , Figure 8 and Figure 9 The results are a comparison between the improved cathode flow channel of this invention and the traditional DC flow channel under a 0.4 V operating condition. Figure 7 This is a comparison of membrane current densities at the mid-section of the PEM. Figure 7 It can be seen that after adopting the angular current-conducting structure 2 described in this invention, the membrane current density distribution is improved and the local low-reaction area is reduced, indicating that the oxygen supply and mass transfer conditions on the cathode side are enhanced. Figure 8 This is a comparison diagram of the water mole fraction distribution at the interface between the flow channel and the GDL. Figure 8 It can be seen that after adopting the cathode flow channel structure described in this invention, the water accumulation phenomenon at the interface between the flow channel and the GDL is reduced, indicating that the lateral flow from the middle to both sides at the interface is conducive to promoting the migration and discharge of product water. Figure 9 This is a comparison diagram of the oxygen mole fraction distribution at the interface between the flow channel and the GDL. Figure 9 It can be seen that after adopting the cathode flow channel structure described in this invention, the oxygen distribution at the contact surface between the flow channel and the GDL is improved, and the downstream low-oxygen region is reduced, indicating that the guiding and double vortex effect induced by the angled flow guiding structure 2 can enhance the transport of oxygen to the GDL direction.

[0037] The above embodiments are merely one specific implementation of the technical solution of the present invention, and the scope of protection of the present invention is not limited to this embodiment. All modifications, substitutions, and other implementations that can be conceived by those skilled in the art based on conventional technical means within the scope of the technology disclosed in the present invention are within the scope of protection of the present invention.

Claims

1. A proton exchange membrane fuel cell cathode flow channel structure based on an angled flow guide structure, characterized in that, The cathode channel is provided with multiple angular flow guiding structures (2). The multiple angular flow guiding structures (2) are arranged at intervals on the bottom surface (5) of the channel along the gas flow direction. Each angular flow guiding structure (2) includes a peak (6), a windward ridge line (7), a flow guiding side (8), a windward surface (9), a leeward surface (10), a leeward ridge line (11), and a bottom surface (12) of the flow guiding structure. The bottom surface (12) of the flow guiding structure is connected to the bottom surface (5) of the channel, and the angular flow guiding structures (2) are symmetrically arranged along the windward ridge line (7) and the leeward ridge line (11).

2. The proton exchange membrane fuel cell cathode flow channel structure based on the angular flow guide structure according to claim 1, characterized in that, After the gas enters the cathode channel through the channel inlet, it comes into contact with the windward side (9) of the angular guide structure (2). When the gas flows through the windward ridge (7) and the peak (6), it is accelerated and split, and deflects to both sides along the windward side (9) and the guide side (8). It forms a flow around and a wake disturbance near the leeward side (10) and the leeward ridge (11), thereby forming a continuous three-dimensional guiding effect inside the cathode channel.

3. The proton exchange membrane fuel cell cathode flow channel structure based on the angular flow guide structure according to claim 1, characterized in that, The windward side (9) is located on the inflow side, the leeward side (10) is located on the backflow side, and the flow guiding side (8) is located on both sides of the angular flow guiding structure (2) and connects the windward side (9) and the leeward side (10) respectively.

4. The proton exchange membrane fuel cell cathode flow channel structure based on the angular flow guide structure according to claim 1, characterized in that, The ends of the dividing lines between the windward ridge (7), the leeward ridge (11), the guide side (8) and the windward surface (9), and the dividing line between the guide side (8) and the leeward surface (10) are respectively connected to the peak (6).

5. The proton exchange membrane fuel cell cathode flow channel structure based on the angular flow guide structure according to claim 1, characterized in that, The peak (6) of the angular flow guide structure (2) is set toward the flow channel outlet direction.

6. The proton exchange membrane fuel cell cathode flow channel structure based on the angular flow guide structure according to claim 1, characterized in that, Multiple angular flow guiding structures (2) are arranged sequentially along the length of the cathode flow channel, so that the gas continuously splits, deflects and re-converges during the flow process. A wheat-ear-shaped flow field with periodic splitting, diffusion and re-convergence is formed on the top surface of the flow channel, and a symmetrical double vortex flow field is formed in the entire flow channel. This promotes the transport of oxygen to the bottom of the flow channel and the direction of the gas diffusion layer, and causes the gas near the interface between the flow channel and the gas diffusion layer to flow from the middle to both sides, so as to promote the migration and discharge of water seeping from the gas diffusion layer to both sides of the flow channel, thereby improving the oxygen supply performance and drainage performance on the cathode side and improving the output performance of the fuel cell.

Images