Connected flow channels of a fuel cell and manufacturing method thereof

Abstract

The present invention provides a connected flow channel for a fuel cell and a manufacturing method thereof. The connected flow channel is used to transport a reaction medium to a reaction zone. The connected flow channel is wavy, and convex body textures with the same distribution are respectively provided on the inner and outer surfaces of the side wall of the wavy connected flow channel, and the distribution density gradient of the convex body textures decreases along the flow direction. The present invention can slow down the impact force of liquid water on the side wall, maintain its inherent shape to reduce the time for liquid water to pass through the flow channel, and accelerate the removal of liquid water. At the same time, the outer convex structure can increase the effective surface area of the flow field and promote the electrochemical reaction efficiency.

Description

Technical Field

[0001] The present invention relates to the field of fuel cells or the field of fuel cell bipolar plate flow fields, and specifically relates to a connected flow channel of a fuel cell and a manufacturing method thereof. Background Art

[0002] As a new energy technology, fuel cell technology has been vigorously developed. Proton exchange membrane fuel cells have become a big hit in fuel cell technology because of their advantages of renewable power energy, high energy density, high reliability, and no polluting exhaust gas emissions. However, since liquid water is generated during the operation of proton exchange membrane fuel cells, a large amount of liquid water will block the flow channels if not removed in time, hinder the gas from participating in the reaction, and affect the working performance of the fuel cell. Therefore, the problem of draining and transporting water in the battery has become a major difficulty.

[0003] The flow channel is one of the key components on the fuel cell, and its surface structure directly affects the drainage performance of the fuel cell. The structure of the flow channel determines the shape of the flow field. Currently, common flow fields include straight channel flow fields, parallel channel flow fields, serpentine single-channel flow fields, serpentine multi-channel flow fields, variable cross-section flow fields, interdigitated flow fields, etc. As a new type of flow field structure, the wavy channel has a good effect on promoting the gas to participate in the reaction. However, due to the sinusoidal wave shape of the wavy channel, its influence on liquid water is great, which is not conducive to the timely removal of the product water, and its water management has become the current research focus.

[0004] The prior art discloses a flow field structure for increasing the effective area of the wavy flow channel of a fuel cell bipolar plate. The semi-circular convex platforms are arranged in the electrochemistry weakening areas on both sides of the wavy flow channel of the fuel cell, which increases the effective area of the electrochemistry reaction of the fuel cell, but it has no improvement effect on the discharge of liquid water. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the present invention provides a connected flow channel of a fuel cell and a manufacturing method thereof. The connected flow channel is wavy, and convex body textures with the same distribution are respectively arranged on the inner and outer surfaces of the side walls of the wavy connected flow channel, and the distribution density gradient of the convex body textures decreases along the flow direction. When the inner side of the wavy connected flow channel is covered with this kind of microstructure, the impact force of the liquid water on the side wall can be reduced, its inherent shape can be maintained to reduce the time for the liquid water to pass through the flow channel, and the discharge of the liquid water can be accelerated. At the same time, the outer convex structure can increase the effective surface area of the flow field and promote the electrochemistry reaction efficiency.

[0006] The present invention realizes the above technical purpose through the following technical means.

[0007] A connected flow channel of a fuel cell, which is used to transport a reaction medium to a reaction zone. The connected flow channel is wavy, and convex body textures with the same distribution are respectively provided on the inner and outer surfaces of the side walls of the wavy connected flow channel, and the distribution density gradient of the convex body textures decreases along the flow direction.

[0008] Furthermore, the wavy connected flow channel includes a wave crest section and a wave trough section. The alternately distributed wave crest section and wave trough section constitute the wavy connected flow channel. The convex body texture includes a first convex texture and a second convex texture. The second convex texture is located at the wave crest of the wave crest section, the wave trough of the wave trough section, and the junction of the wave crest section and the wave trough section; the first convex texture is located at other positions on the side wall of the connected flow channel except at the wave crest of the wave crest section, the wave trough of the wave trough section, and the junction of the wave crest section and the wave trough section. The convex height of the second convex texture is greater than the convex height of the first convex texture.

[0009] Furthermore, the shape of the convex body texture is a sphere or a cube or a cylinder or a regular tetrahedron or an ellipsoid.

[0010] Furthermore, the surface area of the convex body texture on the side wall of the connected flow channel accounts for 70% - 80% of the surface area of the side wall of the connected flow channel.

[0011] Furthermore, the convex height of the second convex texture is 10% - 20% of the height of the side wall of the connected flow channel.

[0012] Furthermore, the convex height of the first convex texture is 0.8 - 0.9 times the convex height of the second convex texture.

[0013] Furthermore, one wave crest section and an adjacent wave trough section constitute a periodic wavy connected flow channel. A number of convex body textures are arranged in an N×M rectangular array on the first-period wavy connected flow channel; a number of convex body textures are arranged in an (N-(i - 1))×(M-(i - 1)) rectangular array on the i-period wavy connected flow channel.

[0014] Furthermore, the horizontal interval between adjacent first convex textures is 0.3 - 0.8 mm, and the vertical interval between adjacent first convex textures is 0.1 - 0.3 mm.

[0015] Furthermore, the horizontal interval between adjacent second convex textures is 0.3 - 0.6 mm, and the vertical interval between adjacent second convex textures is 0.05 - 0.2 mm; the convex height of the convex body texture is 0.01 - 0.1 mm.

[0016] A manufacturing method for the connected flow channels of a fuel cell, which uses long-pulse-width laser to perform laser remelting and texturing on the inner and outer sides of the side walls of the connected flow channels respectively to form convex body textures; the processing parameters of the long-pulse-width laser are: power is 450W, pulse width is 2ms, scanning speed is 2000mm / s, and the number of repetitions is 10 times.

[0017] The beneficial effects of the present invention are as follows:

[0018] 1. For the connected flow channels of the fuel cell described in the present invention, the inner and outer surfaces of the wavy side walls of the connected flow channels are respectively provided with convex body textures with the same distribution, and the distribution density gradient of the convex body textures decreases along the flow direction, which can reduce the impact force of the liquid water seeping up from the gas diffusion layer on the side walls of the wavy flow channels, reduce its adhesion time, maintain its inherent shape, and can drain the liquid water from the flow channels faster, effectively preventing the occurrence of the "waterlogging" phenomenon.

[0019] 2. For the connected flow channels of the fuel cell described in the present invention, the connected flow channels are located in the flow field of the bipolar plate of the fuel cell, and there are raised textures outside the connected flow channels. The micro-convex body textures distributed on the outer sides of the side walls of the connected flow channels can increase the surface area outside the flow channels, further increase the surface area of the current flowing through the surface of the connected flow channels, increase the effective surface area of the electrochemical reaction in the flow field, and improve the reaction rate.

[0020] 3. For the connected flow channels of the fuel cell described in the present invention, the micro-convex body textures are distributed in a decreasing manner, which can reduce the processing cost. And the laser remelting technology adopted has a simple and convenient processing process. Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. The following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained obviously without creative efforts based on these drawings.

[0022] Figure 1 It is a schematic structural diagram of the connected flow channels of the fuel cell described in the present invention.

[0023] Figure 2 It is a schematic diagram of the wavy shape of the connected flow channels described in the present invention.

[0024] Figure 3 It is a side view of the wavy connected flow channels in Embodiment 1 of the present invention.

[0025] Figure 4 It is an enlarged view of the convex body texture in Embodiment 1 of the present invention.

[0026] Figure 5Side view of the wavy connected flow channel of Embodiment 1 of the present invention.

[0027] Figure 6 Enlarged view of the convex body texture of Embodiment 1 of the present invention.

[0028] Figure 7 Comparison diagram of drainage effects of Embodiment 1 and Embodiment 2 of the present invention and Comparative Example 1.

[0029] Figure 8 Comparison diagram of pressure drops of Embodiment 1 and Embodiment 2 of the present invention and Comparative Example 1.

[0030] Figure 9 Comparison diagram of drag reduction rates of Embodiment 1 and Embodiment 2 of the present invention and Comparative Example 1.

[0031] Figure 10 Comparison diagram of water phase volume fractions at the bottom of the flow channel of Embodiment 1 and Embodiment 2 of the present invention and Comparative Example 1.

[0032] Figure 11 Comparison diagram of current densities of Embodiment 1 and Embodiment 2 of the present invention and Comparative Example 1.

[0033] In the figure:

[0034] 1 - connected flow channel; 21 - first convex texture; 22 - second convex texture; T n - bend period; - vertical distance between adjacent first convex textures; - vertical distance between adjacent second convex textures; - horizontal distance between adjacent first convex textures; - horizontal distance between the second convex texture and the first convex texture; - horizontal distance between adjacent second convex textures; - convex height of the first convex texture; - bottom diameter of the first convex texture; - convex height of the second convex texture; - bottom diameter of the second convex texture. Detailed implementation manners

[0035] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0036] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0037] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "axial", "radial", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more, unless otherwise specifically defined.

[0038] In the present invention, unless otherwise clearly specified and defined, the terms "installed", "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] As Figure 1 and Figure 2 shown, for the communication flow channel of the fuel cell described in the present invention, the communication flow channel 1 is located in the flow field of the fuel cell bipolar plate. The communication flow channel 1 is used to transport the reaction medium to the reaction area. The reaction medium can be water, oxygen, or hydrogen. A plurality of communication flow channels 1 are arranged side by side. The communication flow channel 1 is in a wavy shape. On the inner and outer surfaces of the side wall of the wavy communication flow channel 1, convex body textures 2 with the same distribution are respectively provided, and the distribution density gradient of the convex body textures 2 decreases along the flow direction. The convex body texture 2 inside the communication flow channel 1 can reduce the impact force of the liquid water permeating from the gas diffusion layer on the side wall of the wavy flow channel, reduce its adhesion time, maintain its inherent shape, and can discharge the liquid water from the flow channel faster, effectively preventing the occurrence of the "waterlogging" phenomenon. The convex body texture 2 outside the communication flow channel 1 can increase the surface area outside the flow channel, further increase the surface area of the current flowing through the surface of the communication flow channel, increase the effective surface area of the electrochemical reaction in the flow field, and improve the reaction rate.

[0040] The shape of the convex body texture 2 is a sphere, a cube, a cylinder, a regular tetrahedron, or an ellipsoid. The surface area of the convex body texture 2 on the side wall of the connected flow channel 1 accounts for 70% - 80% of the surface area of the side wall of the connected flow channel 1. For example, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, or 80%, etc., but not limited to the listed values. Other unlisted values within the above value range are equally applicable. The present invention balances the exclusion of liquid water and the cost performance of manufacturing cost by controlling the proportion of the surface area of the convex body texture 2 in the total surface area inside and outside the side wall. If the number of the convex body textures 2 is too large, the manufacturing cost will increase, and if the number is too small, it has little impact on the exclusion of liquid water. For the size of the surface area of the convex body texture 2, the parameters of changing the diameter size and the number of the convex body textures 2 can be selected to achieve. Those skilled in the art can comprehensively consider the size of the wavy flow channel, the required drainage performance, the manufacturing cost, etc., and select appropriate parameters for manufacturing.

[0041] As Figure 2 As shown in the figure, the wavy connected flow channel 1 includes a wave crest section and a wave trough section. The alternately distributed wave crest section and wave trough section constitute the wavy connected flow channel 1. The convex body texture 2 includes a first convex texture 21 and a second convex texture 22. The second convex texture 22 is located at the wave crest of the wave crest section, the wave trough of the wave trough section, and the junction of the wave crest section and the wave trough section. The first convex texture 21 is located at other side wall positions of the connected flow channel 1 except at the wave crest of the wave crest section, the wave trough of the wave trough section, and the junction of the wave crest section and the wave trough section. The protruding height of the second convex texture 22 is greater than the protruding height of the first convex texture 21.

[0042] The protruding height of the second convex texture 22 is 10% - 20% of the side wall height of the connected flow channel 1. For example, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%, etc., but not limited to the listed values. Other unlisted values within the above value range are equally applicable as long as they are greater than the protruding height of the first convex texture 21 at other positions. The protruding height of the first convex texture 21 is 0.8 - 0.9 times the protruding height of the second convex texture 22. For example, 0.8 times, 0.81 times, 0.82 times, 0.83 times, 0.84 times, 0.85 times, 0.86 times, 0.87 times, 0.88 times, 0.89 times, or 0.9 times, etc., but not limited to the listed values. Other unlisted values within the above value range are equally applicable.

[0043] As Figure 3As shown in the figure, a wave crest section and an adjacent wave trough section constitute a wave-connected flow channel 1 of one period. A number of convex body textures 2 are arranged in an N×M rectangular array on the wave-connected flow channel 1 of the first period; a number of convex body textures 2 are arranged in an (N - i - 1)×(M - i - 1) rectangular array on the wave-connected flow channel 1 of the i-th period.

[0044] The horizontal interval between adjacent first convex textures 21 is 0.3 - 0.8 mm, such as 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm or 0.8 mm, etc., but not limited to the listed values. Other unlisted values within the above value range are equally applicable. The vertical interval between adjacent first convex textures 21 is 0.1 - 0.3 mm, such as 0.1 mm, 0.12 mm, 0.14 mm, 0.16 mm, 0.18 mm, 0.2 mm, 0.22 mm, 0.24 mm, 0.26 mm, 0.28 mm or 0.3 mm, etc., but not limited to the listed values. Other unlisted values within the above value range are equally applicable.

[0045] The horizontal interval between adjacent second convex textures 22 is 0.3 - 0.6 mm, such as 0.3 mm, 0.33 mm, 0.36 mm, 0.39 mm, 0.42 mm, 0.45 mm, 0.48 mm, 0.51 mm, 0.54 mm, 0.57 mm or 0.6 mm, etc., but not limited to the listed values. Other unlisted values within the above value range are equally applicable. The vertical interval between adjacent second convex textures 22 is 0.05 - 0.2 mm, such as 0.05 mm, 0.065 mm, 0.08 mm, 0.095 mm, 0.11 mm, 0.125 mm, 0.14 mm, 0.155 mm, 0.17 mm, 0.185 mm or 0.2 mm, etc., but not limited to the listed values. Other unlisted values within the above value range are equally applicable; the convex height of the convex body texture 2 is 0.01 - 0.1 mm, such as 0.01 mm, 0.02 mm, 0.03 mm, 0.04 mm, 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm or 0.1 mm, etc., but not limited to the listed values. Other unlisted values within the above value range are equally applicable. As a preferred technical solution of the present invention, the central positions of the micro-convex structures are on the same horizontal or vertical direction.

[0046] The manufacturing method of the connected flow channel of the fuel cell described in the present invention uses a long-pulse-width laser to perform laser remelting and texturing on the inner and outer sides of the side wall of the connected flow channel 1 respectively to form a convex texture 2; the processing parameters of the long-pulse-width laser are: power is 450W, pulse width is 2ms, scanning speed is 2000mm / s, and the number of repetitions is 10 times.

[0047] Example 1

[0048] As Figure 2 、 Figure 3 and Figure 4 shown, Example 1 provides a connected flow channel of a fuel cell. The wavy connected flow channel 1 is made of 304 stainless steel. The length of the wavy connected flow channel 1 is 0.12m, and the cross-sectional area is 1mm×1mm. On the inner and outer sides of the two side walls of the wavy connected flow channel 1, there are orderly distributed spherical micro-convex textures 2 with decreasing numbers, and the positions of the spherical micro-convex textures 2 inside and outside the side walls correspond to each other. The second convex texture 22 is located at the peak of the peak section, the trough of the trough section, and the junction of the peak section and the trough section; the first convex texture 21 is located at other side wall positions of the connected flow channel 1 except for the peak of the peak section, the trough of the trough section, and the junction of the peak section and the trough section. The surface area of the micro-convex structure accounts for 70% of the wavy flow channel.

[0049] In the first cycle T1, the rectangular arrangement of the convex texture 2 is 13×7, in the second cycle T2, the rectangular arrangement of the convex texture 2 is 12×6, in the third cycle T3, the rectangular arrangement of the convex texture 2 is 11×5, and in the fourth cycle T4, the rectangular arrangement of the convex texture 2 is 10×4.

[0050] For those with an odd number of columns of the convex texture 2 in one cycle, the second convex texture 22 has 3 columns at the center of the peak / trough, and for those with an even number of columns of the convex texture 2 in one cycle, the second convex texture 22 has 2 columns at the center of the peak / trough. The second convex texture 22 is a sphere, the diameter d2 of the second convex texture 22 is 0.12mm, and the convex height h2 of the second convex texture 22 is 0.06mm. Here, the convex height h2 is the height protruding from the wall surface. The first convex texture 21 is also a sphere, the diameter d1 of the first convex texture 21 is 0.1mm, and the convex height h1 of the first convex texture 21 is 0.05mm. The central positions of each column of the convex texture 2 are on the same horizontal line and perpendicular to the side wall of the wavy flow channel.

[0051] The vertical distance between adjacent first convex textures 21 in T1 is 0.03mm, the horizontal distance between adjacent first convex textures 21 is 0.25mm, the vertical distance between adjacent second convex textures 22 is 0.01 mm, and the horizontal distance between adjacent second raised textures 22 is 0.23 mm, and the horizontal distance between the first raised texture 21 and the second raised texture 22 is 0.24 mm.

[0052] The vertical distance between adjacent first raised textures 21 in T2 is 0.035 mm, and the horizontal distance between adjacent first raised textures 21 is 0.26 mm, and the vertical distance between adjacent second raised textures 22 is 0.033 mm, and the horizontal distance between adjacent second raised textures 22 is 0.24 mm, and the horizontal distance between the first raised texture 21 and the second raised texture 22 is 0.25 mm.

[0053] The vertical distance between adjacent first raised textures 21 in T3 is 0.05 mm, and the horizontal distance between adjacent first raised textures 21 is 0.27 mm, and the vertical distance between adjacent second raised textures 22 is 0.03 mm, and the horizontal distance between adjacent second raised textures 22 is 0.25 mm, and the horizontal distance between the first raised texture 21 and the second raised texture 22 is 0.26 mm.

[0054] The vertical distance between adjacent first raised textures 21 in T4 is 0.14 mm, and the horizontal distance between adjacent first raised textures 21 is 0.3 mm, and the vertical distance between adjacent second raised textures 22 is 0.12 mm, and the horizontal distance between adjacent second raised textures 22 is 0.28 mm, and the horizontal distance between the first raised texture 21 and the second raised texture 22 is 0.29 mm.

[0055] Example 2

[0056] Such as Figure 2 、 Figure 5 and Figure 6As shown in the figure, Embodiment 1 provides a connected flow channel for a fuel cell. The wavy connected flow channel 1 is made of 304 stainless steel. The length of the wavy connected flow channel 1 is 0.1 m, and the cross-sectional area is 1.2 mm × 1.2 mm. On the inner and outer sides of the two side walls of the wavy connected flow channel 1, cylinder micro-protrusion textures 2 are distributed in an orderly manner with a decreasing number, and the positions of the sphere micro-protrusion textures 2 on the inner and outer sides of the side walls correspond to each other. The second protrusion texture 22 is located at the peak of the peak section, the trough of the trough section, and the junction between the peak section and the trough section; the first protrusion texture 21 is located at other side wall positions of the connected flow channel 1 except for the peak of the peak section, the trough of the trough section, and the junction between the peak section and the trough section. The surface area of the micro-protrusion structure accounts for 80% of the wavy flow channel.

[0057] In the first cycle T1, the rectangular arrangement of the protrusion texture 2 is 13×7. In the second cycle T2, the rectangular arrangement of the protrusion texture 2 is 12×6. In the third cycle T3, the rectangular arrangement of the protrusion texture 2 is 11×5. In the fourth cycle T4, the rectangular arrangement of the protrusion texture 2 is 10×4. The second protrusion texture 22 is a cylinder. The diameter d2 of the second protrusion texture 22 is 0.12 mm, and the protrusion height h2 of the second protrusion texture 22 is 0.8 mm. Here, the protrusion height h2 is the height protruding from the wall surface. The first protrusion texture 21 is also a cylinder. The diameter d1 of the first protrusion texture 21 is 0.1 mm, and the protrusion height h1 of the first protrusion texture 21 is 0.6 mm.

[0058] The vertical distance between adjacent first protrusion textures 21 in T1 is 0.04 mm, and the horizontal distance between adjacent first protrusion textures 21 is 0.26 mm. The vertical distance between adjacent second protrusion textures 22 is 0.02 mm, and the horizontal distance between adjacent second protrusion textures 22 is 0.24 mm. The horizontal distance between the first protrusion texture 21 and the second protrusion texture 22 is 0.25 mm.

[0059] The vertical distance between adjacent first protrusion textures 21 in T2 is 0.036 mm, and the horizontal distance between adjacent first protrusion textures 21 is 0.28 mm. The vertical distance between adjacent second protrusion textures 22 is 0.034 mm, and the horizontal distance between adjacent second protrusion textures 22 is 0.26 mm. The horizontal distance between the first protrusion texture 21 and the second protrusion texture 22 is 0.27 mm.

[0060] The vertical distance between adjacent first raised textures 21 in T3 is 0.06 mm, and the horizontal distance between adjacent first raised textures 21 is 0.28 mm. The vertical distance between adjacent second raised textures 22 is 0.04 mm, and the horizontal distance between adjacent second raised textures 22 is 0.26 mm. The horizontal distance between the first raised texture 21 and the second raised texture 22 is 0.27 mm.

[0061] The vertical distance between adjacent first raised textures 21 in T4 is 0.15 mm, and the horizontal distance between adjacent first raised textures 21 is 0.32 mm. The vertical distance between adjacent second raised textures 22 is 0.13 mm, and the horizontal distance between adjacent second raised textures 22 is 0.3 mm. The horizontal distance between the first raised texture 21 and the second raised texture 22 is 0.31 mm.

[0062] Taking the wavy flow channel of the prior art as Comparative Example 1, its wavy flow channel length is 0.12 m, and the cross-sectional area is 1 mm × 1 mm.

[0063] Compared with the prior art, the present invention has a positive improvement effect on the drainage effect. For example Figure 7 as shown, the droplet removal speed of the connected flow channel of the fuel cell of the present invention is significantly greater than that of the flow channel of the prior art. At the same moment, the position of the droplets in the wavy flow channels of Example 1 and Example 2 is significantly ahead of that of the wavy flow channel of Comparative Example 1. And in Figure 8 the pressure drop in the flow channels of Example 1 and Example 2 is significantly greater than that in the flow channel of Comparative Example 1 in the initial and middle stages, which is beneficial to the drainage speed.

[0064] According to the drag reduction rate calculation formula:

[0065]

[0066] where S is the drag reduction rate, is the pressure drop in the wavy flow channel with micro-protrusions, is the pressure drop in the wavy flow channel without micro-protrusions.

[0067] As Figure 9 shown, the wavy flow channels of Example 1 and Example 2 have the effect of reducing the movement resistance of droplets to the wavy flow channel of Comparative Example 1, and can accelerate the removal of droplets in the flow channel.

[0068] As Figure 10 shown, during the movement of the droplets, the water volume fraction at the bottom of the wavy flow channels in Example 1 and Example 2 is smaller than that in Comparative Example 1 in the middle stage, which is beneficial for the gas transport of the fuel cell. Since the bottom of the flow channel is the surface of the gas diffusion layer, the less liquid water adheres to its surface, the more conducive it is for the reaction gas to pass through the diffusion layer and reach the reaction area faster. Although the water volume fractions of the three examples in the figure are almost the same in the initial and later stages, and even the water volume fraction of Example 2 is the largest in the later stage, this is caused by the droplets falling off the bottom of the flow channel to the bottom at the end, and the reference effect is not significant.

[0069] As Figure 11 shown, compared with Comparative Example 1, Example 1 and Example 2 have a larger current density, which has a positive promoting effect on the electrochemical reaction of the fuel cell and can accelerate the reaction speed and reaction efficiency.

[0070] It should be understood that although this specification is described according to each embodiment, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0071] The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of the present invention, and they are not intended to limit the protection scope of the present invention. Any equivalent embodiments or modifications made without departing from the technical spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A connected flow channel of a fuel cell, the connected flow channel being used for transporting a reaction medium to a reaction zone, and a plurality of connected flow channels being arranged side by side, characterized in that, The connected flow channel (1) is wavy, and convex body textures (2) with the same distribution are respectively arranged on the inner and outer surfaces of the side wall of the wavy connected flow channel (1), and the distribution density gradient of the convex body textures (2) decreases along the flow direction; The wavy connected flow channel (1) includes a wave crest section and a wave trough section, and the alternately distributed wave crest section and wave trough section constitute the wavy connected flow channel (1). The convex body texture (2) includes a first convex texture (21) and a second convex texture (22). The second convex texture (22) is located at the wave crest of the wave crest section, the wave trough of the wave trough section, and the junction of the wave crest section and the wave trough section; the first convex texture (21) is located at other side wall positions of the connected flow channel (1) except for the wave crest of the wave crest section, the wave trough of the wave trough section, and the junction of the wave crest section and the wave trough section. The convex height of the second convex texture (22) is greater than the convex height of the first convex texture (21).

2. The connected flow channel of the fuel cell according to claim 1, characterized in that, The shape of the convex body texture (2) is a sphere or a cube or a cylinder or a regular tetrahedron or an ellipsoid.

3. The connected flow channel of the fuel cell according to claim 1, characterized in that, The surface area of the convex body texture (2) on the side wall of the connected flow channel (1) accounts for 70% - 80% of the surface area of the side wall of the connected flow channel (1).

4. The connected flow channel of the fuel cell according to claim 1, characterized in that, The convex height of the second convex texture (22) is 10% - 20% of the height of the side wall of the connected flow channel (1).

5. The connected flow channel of the fuel cell according to claim 1, characterized in that, The convex height of the first convex texture (21) is 0.8 - 0.9 times the convex height of the second convex texture (22).

6. The connected flow channel of the fuel cell according to claim 1, characterized in that, One wave crest section and an adjacent wave trough section constitute a periodic wavy connected flow channel (1), and a number of convex body textures (2) are arranged in an N×M rectangular array on the first-period wavy connected flow channel (1); on the i-period wavy connected flow channel (1), a number of convex body textures (2) are arranged in an (N - (i - 1))×(M - (i - 1)) rectangular array.

7. The communicating flow channel of the fuel cell according to claim 6, characterized in that, The horizontal interval between adjacent first convex textures (21) is 0.3 - 0.8 mm, and the vertical interval between adjacent first convex textures (21) is 0.1 - 0.3 mm.

8. The communicating flow channel of the fuel cell according to claim 6, characterized in that, The horizontal interval between adjacent second convex textures (22) is 0.3 - 0.6 mm, and the vertical interval between adjacent second convex textures (22) is 0.05 - 0.2 mm; the convex height of the convex body texture (2) is 0.01 - 0.1 mm.

9. A manufacturing method of a connected flow channel of a fuel cell according to any one of claims 1 - 8, characterized in that Long-pulse-width laser is used to perform laser remelting and texturing processing on the inner and outer sides of the side wall of the connected flow channel (1) respectively to form convex body textures (2); The processing parameters of the long-pulse-width laser are: power is 450 W, pulse width is 2 ms, scanning speed is 2000 mm / s, and the number of repetitions is 10 times.

Images