A fuel cell, a fuel cell bipolar plate and its flow channel structure

Abstract

This invention relates to a fuel cell, a fuel cell bipolar plate, and a flow channel structure thereof. The bottom surface of the flow channel structure includes multiple repeating unit surfaces arranged sequentially along the length of the flow channel structure. The repeating unit surfaces are smoothly connected and transitioned together. The repeating unit surfaces are concave curved surfaces to apply momentum perpendicular to the surface of the fuel cell bipolar plate to the flowing fluid. The shape of the projection of the repeating unit surface onto a plane perpendicular to the width of the flow channel structure is at least partially a brachistochrone curve, or the repeating unit surface is a partial curved surface intercepted from the brachistochrone curve. It can be seen that the above-mentioned flow channel structure can provide momentum perpendicular to the surface of the bipolar plate to the fluid when it passes through, rapidly increase the fluid velocity, thereby improving its mass transfer capacity, improving the drainage capacity of the fuel cell bipolar plate, and improving the performance of the fuel cell.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a fuel cell, a fuel cell bipolar plate, and a flow channel structure thereof. Background Technology

[0002] The function of the flow field in a fuel cell is to provide a medium for the electrochemical reaction, including hydrogen and air, and to remove water produced during the reaction from the flow field. Common bipolar plate flow channel designs include straight, meandering, or serpentine structures, but the bottom of the flow channel generally adopts a planar trench structure parallel to the plate surface. This planar trench structure can only provide basic functions for air intake and drainage, and its drainage capacity is generally limited. Summary of the Invention

[0003] The first objective of this invention is to provide a bipolar plate flow channel structure for a fuel cell that can increase fluid flow rate, improve drainage capacity, and thereby improve fuel cell performance.

[0004] The second objective of this invention is to provide a fuel cell bipolar plate and a fuel cell based on the above-described fuel cell bipolar plate flow channel structure.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A bipolar plate flow channel structure for a fuel cell, wherein the bottom surface of the fuel cell bipolar plate flow channel structure includes a plurality of repeating unit surfaces arranged sequentially along the length direction of the fuel cell bipolar plate flow channel structure, and the repeating unit surfaces are smoothly connected to each other. The repeating unit surfaces are concave curved surfaces to apply momentum perpendicular to the tangent direction of the curved surface where the fluid flows through to the fluid.

[0007] The shape of the projection of the repeating unit surface onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure is at least partially a brachistochrone curve, and the equation of the brachistochrone curve is: Where θ is the angle of rotation of the rolling circle with radius r, and the range of θ in the formula is (0, 2π). Alternatively, the repeating unit surface is a portion of the surface intercepted from the brachistochronous surface, and the equation of the brachistochronous surface is... Where θ is the angle of rotation of the rolling circle with radius r, and the range of θ in the formula is (0, 2π). Φ is the angle between the projection of the measured point of the steepest descent surface onto the xz plane, the line connecting the origin and the x-axis.

[0008] Preferably, the bipolar plate flow channel structure of the fuel cell is a straight flow channel extending in a straight line, or the bipolar plate flow channel structure of the fuel cell is a meandering flow channel extending in a curve, wherein each meandering cycle of the meandering flow channel includes at least one repeating unit surface.

[0009] Preferably, r is 0.5 to 5 times the depth of the bipolar plate flow channel structure of the fuel cell.

[0010] Preferably, the value of θ is in the range of (60°, 120°).

[0011] Preferably, when the shape of the projection of the repeating unit surface onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure is at least partially a brachistochrone line, the repeating unit surface includes an interconnected upper slope surface and a lower slope surface, and the shape of the projection of at least one of the upper slope surface and the lower slope surface onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure is a brachistochrone line.

[0012] Preferably, the shapes of the projections of the upper and lower slopes onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure are both brachistochrone lines.

[0013] Preferably, the values ​​of θ and r of the shape of the projection of the upper slope surface onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure are exactly the same as the values ​​of θ and r of the shape of the projection of the lower slope surface onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure.

[0014] Preferably, at least one of the values ​​of θ and r of the shape of the projection of the upper slope surface onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure is different from the values ​​of θ and r of the shape of the projection of the lower slope surface onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure.

[0015] Preferably, the values ​​of θ and r are exactly the same for the portion of the portion of the repeating unit surface of the fuel cell bipolar plate flow channel structure projected onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure as the briskest descent line.

[0016] Preferably, the values ​​of θ and r for the portion of at least one repeating unit surface of the fuel cell bipolar plate flow channel structure whose projection onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure is a brachistochrone line are different from the values ​​of θ and r for the portions of the repeating unit surface whose projection onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure is a brachistochrone line.

[0017] Preferably, the vertical depth of the repeating unit surface is 0.1 to 0.8 times the vertical depth of the fuel cell bipolar plate flow channel structure.

[0018] A fuel cell bipolar plate includes a plate body and a plurality of side-by-side flow channels disposed on the plate body, wherein the flow channels adopt the fuel cell bipolar plate flow channel structure described in any of the above claims.

[0019] Preferably, the plate is a metal plate, a graphite plate, or a composite material plate.

[0020] A fuel cell includes a fuel cell bipolar plate as described above.

[0021] As can be seen from the above technical solution, this invention discloses a bipolar plate flow channel structure for a fuel cell. The bottom surface of this structure includes multiple repeating unit surfaces arranged sequentially along the length of the flow channel. These repeating unit surfaces are smoothly connected and transitioned together. Each repeating unit surface is a concave curved surface to apply momentum perpendicular to the tangent direction of the curved surface through which the fluid flows. The shape of the projection of the repeating unit surface onto a plane perpendicular to the width direction of the flow channel is at least partially a brachistochrone (maximum rate of descent), and the equation of the brachistochrone is... Where θ is the angle of rotation of the rolling circle with radius r, and the range of θ in the formula is (0, 2π). Alternatively, the repeating element surface is a portion of the surface intercepted from the brachistochronous surface, and the equation of the brachistochronous surface is... Where θ is the angle of rotation of the rolling circle with radius r, the range of θ in the formula is (0, 2π), and Φ is the angle between the projection of the measured point of the steepest descent surface onto the xz plane and the line connecting the origin and the x-axis.

[0022] As can be seen, the above-mentioned fuel cell bipolar plate flow channel structure, by designing the bottom as multiple continuous concave curved surfaces, and the shape of the projection of each concave curved surface onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure, is at least partially a brachistochrone curve or a repeating unit surface is a portion of the curved surface intercepted on the brachistochrone curve, thereby providing momentum perpendicular to the tangential direction of the fluid flow path when the fluid passes through, rapidly increasing the fluid velocity, and thus achieving the purpose of improving its mass transfer capacity, improving the drainage capacity of the fuel cell bipolar plate, and improving the performance of the fuel cell.

[0023] The present invention also discloses a fuel cell bipolar plate including the above-mentioned fuel cell bipolar plate flow channel structure and a fuel cell. Since the fuel cell bipolar plate and the fuel cell both adopt the above-mentioned fuel cell bipolar plate flow channel structure, the fuel cell bipolar plate and the fuel cell should have the same beneficial effects as the fuel cell bipolar plate flow channel structure, which will not be described in detail here. Attached Figure Description

[0024] 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.

[0025] Figure 1 This is a schematic diagram of the bipolar plate flow channel structure of a fuel cell provided in one embodiment of the present invention;

[0026] Figure 2 for Figure 1 AA view in the middle;

[0027] Figure 3 A schematic diagram of a meandering flow channel structure for a fuel cell bipolar plate provided in another embodiment of the present invention;

[0028] Figure 4 for Figure 1 and Figure 3 The shape of the fuel cell bipolar plate flow channel structure in the provided embodiment is the projection of a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure.

[0029] Figure 5 A schematic diagram of the bipolar plate flow channel structure of a fuel cell provided in another embodiment of the present invention;

[0030] Figure 6 This is a schematic diagram of the brachistochrone surface.

[0031] Figure 7 A schematic diagram of the shape formed by the projection of the repeating unit surface of the meandering flow channel onto the surface of the fastest descent.

[0032] Figure 8 For Figure 7 The resulting shape is a side view of the bottom surface of the fuel cell bipolar plate flow channel structure formed by repeating unit surfaces;

[0033] Figure 9 For Figure 7 The resulting shape serves as a front view of the bottom surface of the fuel cell bipolar plate flow channel structure formed by repeating unit surfaces.

[0034] in:

[0035] 1 represents the plate; 2, 2a, and 2b represent repeating unit surfaces; 3 represents the brachistochrone line; and 4 represents the brachistochrone surface. Detailed Implementation

[0036] One of the core aspects of this invention is to provide a bipolar plate flow channel structure for a fuel cell. The structural design of this bipolar plate flow channel structure enables it to increase fluid flow rate, improve drainage capacity, and thus enhance fuel cell performance.

[0037] Another core aspect of this invention is to provide a fuel cell bipolar plate including the above-described fuel cell bipolar plate flow channel structure and a fuel cell.

[0038] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Please see Figures 1-6 , Figure 1 This is a schematic diagram of the bipolar plate flow channel structure of a fuel cell provided in one embodiment of the present invention. Figure 2 for Figure 1 AA view in Figure 3 This is a schematic diagram of a meandering flow channel structure for a fuel cell bipolar plate according to another embodiment of the present invention. Figure 4 for Figure 1 and Figure 3 The provided embodiment shows the shape of the fuel cell bipolar plate flow channel structure projected onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure. Figure 5 This is a schematic diagram of the bipolar plate flow channel structure of a fuel cell provided in another embodiment of the present invention. Figure 6 This is a schematic diagram of the brachistochrone surface.

[0040] This invention discloses a bipolar plate flow channel structure for a fuel cell. The bottom surface of this structure includes multiple repeating unit surfaces 2 arranged sequentially along the length of the flow channel. These repeating unit surfaces 2 are smoothly connected. Each repeating unit surface 2 is a concave curved surface to apply momentum perpendicular to the tangent direction of the curved surface where the fluid flows. The concave curved surface may have a non-zero curvature only in the length direction of the flow channel and a zero curvature in the width direction. Alternatively, the curvature may be non-zero in both the length and width directions. It should be noted that the aforementioned bipolar plate flow channel structure can be a straight flow channel extending along a straight line, such as… Figure 1 and Figure 2 As shown, alternatively, the bipolar plate flow channel structure of the fuel cell is a curved, meandering flow channel, with each meandering cycle of the flow channel including at least one repeating unit surface 2a, as shown. Figure 3 As shown, the meandering flow channel can be viewed as a series of continuous meandering cycles formed by alternating left and right offsets in the length direction based on the straight flow channel.

[0041] Specifically, the shape of the projection of the aforementioned repeating unit surface 2 / 2a onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure is at least partially a brachistochrone 3. The brachistochrone 3, also known as a cycloid or rolling curve, can be equivalently represented as the trajectory formed by a point on the boundary of a circle rolling purely along a straight line. Figure 4 As shown, the equation of the brachistochrone is Where the x-axis is the extension direction of the bipolar plate flow channel structure of the fuel cell, the y-axis is the depth direction of the bipolar plate flow channel structure of the fuel cell, and θ is the angle of rotation of the rolling circle with radius r. The range of θ in the formula is (0, 2π).

[0042] Alternatively, please see Figure 5 and Figure 6 The repeating element surface is a portion of the surface intercepted on the brachistochronous surface 4. The equation of the brachistochronous surface 4 is: Where θ is the angle of rotation of the rolling circle with radius r, and the range of θ in the formula is (0, 2π). Φ is the angle between the projection of the measured point of the steepest descent surface 4 onto the xz plane, the line connecting the origin and the x-axis.

[0043] As can be seen, compared with the prior art, the fuel cell bipolar plate flow channel structure provided in this embodiment of the invention designs the bottom as multiple continuous concave curved surfaces, and the shape of the projection of each concave curved surface onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure is at least partially a brachistochrone curve or a repeating unit surface is a portion of the curved surface intercepted on the brachistochrone curve. This provides momentum to the fluid in the direction perpendicular to the tangent of the curved surface through which the fluid flows, thereby rapidly increasing the fluid velocity, and thus achieving the purpose of improving its mass transfer capacity, improving the drainage capacity of the fuel cell bipolar plate, and improving the performance of the fuel cell.

[0044] The above-mentioned r value can vary with the length and depth of the fuel cell bipolar plate flow channel structure. In the embodiment of the present invention, r is 0.5 times to 5 times the depth of the fuel cell bipolar plate flow channel structure. Since the bottom surface of the fuel cell bipolar plate flow channel structure is undulating, the depth of the fuel cell bipolar plate flow channel structure here refers to its deepest depth.

[0045] Preferably, the range of θ in the above formula is (60°, 120°).

[0046] Further optimizing the above technical solution, when the shape of the projection of the repeating unit surface onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure is at least partially a brachistochrone line, such as... Figures 1 to 3As shown, the aforementioned repeating unit surface 2 / 2a includes an interconnected upper slope surface and a lower slope surface. The shape of the projection of at least one of the upper slope surface and the lower slope surface onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure is a brachistochrone.

[0047] In the above embodiments, only one side of the upslope and downslope is designed with the brachistochrone 3 (asymmetric design). Fluid can flow in from either the side with the brachistochrone 3 design or the side without the brachistochrone design.

[0048] Furthermore, in the above embodiments, the shapes of the projections of the upper and lower slopes onto the plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure are both the brachistochrone line 3.

[0049] Preferably, the values ​​of θ and r of the shape of the projection of the upper slope surface onto the plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure are exactly the same as the values ​​of θ and r of the shape of the projection of the lower slope surface onto the plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure. Thus, due to their symmetry, the fluid inflow direction is exactly the same along the upper and lower slope surfaces.

[0050] Alternatively, an asymmetric design can be adopted, where at least one of the values ​​of θ and r of the shape of the projection of the upper slope surface onto the plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure is different from the values ​​of θ and r of the projection of the lower slope surface onto the plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure. That is, the values ​​of θ and r of the projection of the upper slope surface onto the plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure can be different from the values ​​of θ and / or the values ​​of r and r of the projection of the upper slope surface onto the plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure can be different from the values ​​of θ and r of the projection of the lower slope surface onto the plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure. In other words, the values ​​of θ and r of the upper and lower slope surfaces are taken to different values ​​according to the design requirements, and the design is optimized separately from the fluid inflow direction and the outflow direction to meet the requirements.

[0051] To further optimize the above technical solution, in the above embodiment, the values ​​of θ and r of the projection of each repeating unit surface 2 / 2a of the above fuel cell bipolar plate flow channel structure onto the plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure are exactly the same as the part of the brachistochrone line, that is, each repeating unit surface adopts the same shape (straight flow channel) or two adjacent repeating unit surfaces are mirror images of each other (winding flow channel).

[0052] Of course, in other embodiments, the repeated unit surfaces can also adopt different designs. That is, the values ​​of θ and r of the portion of the projection of at least one repeated unit surface of the fuel cell bipolar plate flow channel structure onto the plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure that is the briskest descent line are different from the values ​​of θ and r of the portion of the projection of the repeated unit surface onto the plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure that is the briskest descent line. Here, different values ​​of θ and r means different values ​​of θ, different values ​​of r, or different values ​​of both θ and r.

[0053] like Figure 6 As shown, the brachistochrone surface 4 is the aforementioned brachistochrone line. θ(0, 2π) is obtained by rotating it 360 degrees around its own line of symmetry.

[0054] like Figure 7 As shown, a portion of the surface is cut off from the brachistochronous surface 4, resulting in the following: Figure 5 , Figure 7 , Figure 8 and Figure 9 The repeated element facet 2b shown is formed by alternating symmetrical repeated element faces 2b. Figure 8 and Figure 9 The flow channel of the fuel cell bipolar plate is shown.

[0055] In the above embodiments, such as Figure 8 and Figure 9 As shown, the peak or trough of each meandering cycle of the meandering flow channel is a portion of the surface intercepted from the brachistochronous surface 4, or a peak plus a trough of each meandering cycle of the meandering flow channel is a portion of the surface intercepted from the brachistochronous surface. The peak or trough of each meandering cycle can be a portion of the brachistochronous surface with the same θ value and / or r value, or it can be a portion of the brachistochronous surface with different θ values ​​and / or r values.

[0056] To further optimize the above technical solution, the vertical depth of the repeating unit surface is 0.1 to 0.8 times the vertical depth of the bipolar plate flow channel structure of the fuel cell.

[0057] This invention also provides a fuel cell bipolar plate, which includes a plate body 1 and a plurality of parallel flow channels disposed on the plate body 1. The flow channels adopt the fuel cell bipolar plate flow channel structure as described in the above embodiments. Since the fuel cell bipolar plate flow channel structure has the above-mentioned technical effects, please refer to the above embodiments for the technical effects of the fuel cell bipolar plate.

[0058] Preferably, the plate 1 is a metal plate, a graphite plate, or a composite material plate, and the forming method of the fuel cell bipolar plate flow channel structure can be stamping, molding, injection molding, or machining.

[0059] Furthermore, embodiments of the present invention also provide a fuel cell, which includes the fuel cell bipolar plate of the above embodiments.

[0060] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0061] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A bipolar plate flow channel structure for a fuel cell, characterized in that, The bottom surface of the fuel cell bipolar plate flow channel structure includes multiple repeating unit surfaces arranged sequentially along the length of the fuel cell bipolar plate flow channel structure. Each repeating unit surface is smoothly connected to the other. The repeating unit surface is a concave curved surface to apply momentum perpendicular to the tangent direction of the curved surface where the fluid flows through. The shape of the projection of the repeating unit surface onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure is at least partially a brachistochrone curve, and the equation of the brachistochrone curve is: Where θ is the angle of rotation of the circle with radius r, and the range of θ in the formula is (0, 2π). The repeating unit surface includes interconnected upper and lower slope surfaces. The shape of the projection of at least one of the upper and lower slope surfaces onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure is a brachistochrone curve. Alternatively, the repeating unit surface is a partial surface intercepted from the brachistochrone surface, and the equation of the brachistochrone surface is... Where θ is the angle of rotation of the rolling circle with radius r, and the range of θ in the formula is (0, 2π). Φ is the angle between the projection of the measured point of the steepest descent surface onto the xz plane, the line connecting the origin and the x-axis.

2. The fuel cell bipolar plate flow channel structure according to claim 1, characterized in that, The bipolar plate flow channel structure of the fuel cell is a straight flow channel extending in a straight line, or the bipolar plate flow channel structure of the fuel cell is a meandering flow channel extending in a curve, wherein each meandering cycle of the meandering flow channel includes at least one repeating unit surface.

3. The fuel cell bipolar plate flow channel structure according to claim 1 or 2, characterized in that, r is 0.5 to 5 times the depth of the bipolar plate flow channel structure of the fuel cell.

4. The fuel cell bipolar plate flow channel structure according to claim 1 or 2, characterized in that, The range of θ is (60°, 120°).

5. The fuel cell bipolar plate flow channel structure according to claim 1 or 2, characterized in that, The shapes of the projections of the upper and lower slopes onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure are both brachistochrone lines.

6. The fuel cell bipolar plate flow channel structure according to claim 5, characterized in that, The values ​​of θ and r of the shape of the projection of the upper slope surface onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure are exactly the same as the values ​​of θ and r of the shape of the projection of the lower slope surface onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure.

7. The fuel cell bipolar plate flow channel structure according to claim 5, characterized in that, The value of at least one of θ and r of the shape of the projection of the upper slope surface onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure is different from the value of θ and r of the shape of the projection of the lower slope surface onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure.

8. The fuel cell bipolar plate flow channel structure according to any one of claims 5-7, characterized in that, The values ​​of θ and r are exactly the same for the portion of the portion of the curve that is the most rapid descent line in the projection of each repeating unit surface of the fuel cell bipolar plate flow channel structure onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure.

9. The fuel cell bipolar plate flow channel structure according to any one of claims 5-7, characterized in that, The values ​​of θ and r for the portion of at least one repeating unit surface of the fuel cell bipolar plate flow channel structure whose projection onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure is a brachistochronous line are different from the values ​​of θ and r for the portions of the repeating unit surface whose projection onto a plane perpendicular to the width direction of the fuel cell bipolar plate flow channel structure is a brachistochronous line.

10. The fuel cell bipolar plate flow channel structure according to any one of claims 1, 2, and 5-7, characterized in that, The vertical depth of the repeating unit surface is 0.1 to 0.8 times the vertical depth of the bipolar plate flow channel structure of the fuel cell.

11. A fuel cell bipolar plate, comprising a plate body and a plurality of side-by-side flow channels disposed on the plate body, characterized in that, The flow channel adopts the fuel cell bipolar plate flow channel structure as described in any one of claims 1-10.

12. The fuel cell bipolar plate according to claim 11, characterized in that, The plate can be a metal plate, a graphite plate, or a composite material plate.

13. A fuel cell, characterized in that, Includes the fuel cell bipolar plate as described in claim 11 or 12.

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