Fuel cell snakelike flow field with gradually reduced number of channels beneficial to drainage

Abstract

The invention discloses a fuel cell channel number decreasing type snakelike flow field beneficial to water drainage, which comprises a snakelike channel number decreasing type reaction area, the reaction area comprises a plurality of groups of sub snakelike flow channels, the plurality of groups of sub snakelike flow channels are sequentially connected at corners to form a multi-stage reaction area from top to bottom, the channel number in each stage of sub snakelike flow channel is gradually decreased step by step, and the channel number in each stage of sub snakelike flow channel is gradually decreased. An open connection mode is adopted at the connection corner of each stage of sub-snake-shaped flow channel; the multi-channel gas inlet is formed in the initial end of the snake-shaped channel number gradually-decreasing type reaction area; and the few-channel gas outlet is arranged at the tail end of the snake-shaped channel number gradually-decreasing type reaction area. The drainage capacity can be enhanced, the gas inlet and outlet pressure drop can be reduced, and the overall efficiency and stability of the fuel cell are further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of fuel cells, and in particular relates to a fuel cell channel number decreasing type serpentine flow field which is beneficial to drainage. Background Art

[0002] Fuel cells, as a clean and efficient energy technology, have attracted widespread attention and in-depth research in recent years. The flow field is one of the key components of fuel cells, and its functions include distributing reaction gases, removing moisture, and conducting electrons. The serpentine flow field has become the most commonly used design due to its advantages such as simple processing and strong gas mass transfer capacity. However, the serpentine flow field still has the problem of liquid water easily gathering at the corners of the flow channel, resulting in poor gas mass transfer, which seriously affects the efficiency and stability of the fuel cell.

[0003] Patent CN103746129A proposes an improved fuel cell serpentine flow field, which partially improves the drainage effect by adopting nine parallel flow channels at the gas inlet and merging every three flow channels into one at the turn of the flow channel. However, the design still adopts a closed structure at the turn, resulting in the accumulation of liquid water hindering the mass transfer of the gas. In addition, in the area where the flow channel exceeds two-thirds, the design adopts parallel three serpentine flow channels, resulting in excessive pressure drop at the gas inlet and outlet, reducing the system efficiency of the fuel cell, especially in commercial fuel cells with a large activation area. This problem is more obvious. Patent CN 101047252A proposes a hybrid fuel cell variable flow field, which reduces the multiple channels at the inlet step by step through a multi-channel circular flow field, partially improving the fuel utilization rate and drainage capacity, but because the gas outlet of the flow field of the invention is located in the circular center area, the design will face the problem of outlet layout when assembling the stack, and its unconventional shape of the activation area will significantly increase the loss of expensive membrane electrode materials in practical applications. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes a serpentine flow field with a decreasing number of fuel cell channels that is conducive to drainage, which can enhance drainage capacity and reduce gas inlet and outlet pressure drops, thereby improving the overall efficiency and stability of the fuel cell.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a fuel cell channel number decreasing serpentine flow field which is conducive to drainage, comprising:

[0006] A reaction area with a decreasing number of serpentine channels, comprising multiple groups of sub-serpentine flow channels, which are sequentially connected at the corners to form a multi-stage reaction area from top to bottom, wherein the number of channels in each sub-serpentine flow channel decreases step by step, and an open connection method is adopted at the connecting corners of each sub-serpentine flow channel;

[0007] A multi-channel gas inlet is arranged at the beginning of the reaction area with a decreasing number of serpentine channels;

[0008] and a few-channel gas outlet, which is arranged at the end of the serpentine channel number decreasing type reaction area.

[0009] Furthermore, the open connection mode is that the channels of the upper sub-serpentine flow channel and the lower sub-serpentine flow channel are interconnected.

[0010] Furthermore, at the corner connection of the sub-serpentine flow channel, the ends of each channel in the sub-serpentine flow channel are staggered in sequence to form a step shape; the step structures at the corner connection of the upper-level sub-serpentine flow channel and the lower-level sub-serpentine flow channel are intertwined and connected to each other.

[0011] Furthermore, the channel width and depth of the sub-serpentine flow channel are both 1 mm.

[0012] Furthermore, the serpentine channel number decreasing type reaction area includes a first-level sub-serpentine flow channel, a second-level sub-serpentine flow channel, a third-level sub-serpentine flow channel, a fourth-level sub-serpentine flow channel and a fifth-level sub-serpentine flow channel, and the sub-serpentine flow channels of each level are sequentially connected at the corners;

[0013] The first-stage serpentine flow channel includes a parallel seven-channel structure;

[0014] The secondary sub-serpentine flow channel includes a parallel six-channel structure;

[0015] The third-stage serpentine flow channel includes a parallel five-channel structure;

[0016] The fourth-stage serpentine flow channel includes a parallel four-channel structure;

[0017] The five-stage serpentine flow channel includes a parallel three-channel structure.

[0018] Furthermore, the multi-channel gas inlet is a parallel seven-channel gas inlet, and the few-channel gas outlet is a parallel three-channel gas outlet.

[0019] The beneficial effects of adopting this technical solution are:

[0020] The present invention realizes a layout with a decreasing number of channels by optimizing the design of the serpentine flow channel, thereby enhancing the drainage capacity of the flow field while properly controlling the gas inlet and outlet pressure drop, thereby improving the overall efficiency and stability of the fuel cell.

[0021] The present invention adopts a planar structure that is easy to CNC process, and sequentially sets areas with decreasing channel numbers at the corners of the four serpentine flow channels in the gas flow direction, thereby accelerating the gas flow rate by gradually reducing the number of parallel channels, thereby significantly enhancing the drainage capacity of the flow field. In addition, the present invention adopts an open design at the corners of the area with decreasing channel numbers, which effectively alleviates the problem of poor gas mass transfer caused by the accumulation of liquid water in conventional serpentine flow fields. Compared with traditional serpentine flow fields, the present invention achieves a good balance between battery system efficiency and drainage capacity while improving drainage capacity, and is particularly suitable for commercial fuel cells with a large activation area.

[0022] Compared with the traditional serpentine flow field design that maintains a consistent number of channels, the serpentine flow field with a decreasing number of channels proposed in the present invention not only maintains smooth gas flow, but also gradually reduces the number of channels, so that the gas is continuously accelerated during the flow process, thereby significantly enhancing the drainage capacity.

[0023] Compared with the improved serpentine flow field proposed in the prior art, the present invention achieves a better balance between system efficiency and drainage capacity through a channel number reduction scheme, and is particularly suitable for commercial fuel cells with a large activation area. In addition, the present invention adopts an open structure design in the area where the number of channels decreases, which effectively solves the problem of gas mass transfer obstruction caused by local liquid water accumulation, thereby further improving the operating stability of the fuel cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic structural diagram of a serpentine flow field with a decreasing number of fuel cell channels that is beneficial to drainage according to the present invention;

[0025] Figure 2 This is a schematic diagram of the structure of Comparative Example 1 in an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the structure of Comparative Example 2 in an embodiment of the present invention;

[0027] Figure 4 It is a performance comparison diagram of three flow fields of the embodiment of the present invention and comparative examples 1 and 2;

[0028] Figure 5 It is a comparison diagram of the cathode gas inlet and outlet pressure drops of three flow fields of the embodiment of the present invention and comparative examples 1 and 2. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described below with reference to the accompanying drawings.

[0030] In this embodiment, see Figure 1 As shown, the present invention proposes a fuel cell channel number decreasing serpentine flow field which is beneficial to drainage, comprising:

[0031] A reaction area with a decreasing number of serpentine channels, comprising multiple groups of sub-serpentine flow channels, which are sequentially connected at the corners to form a multi-stage reaction area from top to bottom, wherein the number of channels in each sub-serpentine flow channel decreases step by step, and an open connection method is adopted at the connecting corners of each sub-serpentine flow channel;

[0032] A multi-channel gas inlet is arranged at the beginning of the reaction area with a decreasing number of serpentine channels;

[0033] and a few-channel gas outlet, which is arranged at the end of the serpentine channel number decreasing type reaction area.

[0034] The reaction gas enters from the inlet of the fuel cell and is evenly distributed through the multi-channel gas inlet to ensure sufficient contact and reaction of the gas in the initial stage. This design ensures that the gas can be fully distributed in the early stage of the reaction and improves fuel utilization.

[0035] Serpentine channel number decreasing type reaction area: Set the channel number decreasing area at the four corners in the middle and lower part of the activation area, such as Figure 1 As shown in the figure, the number of channels is gradually reduced from seven to six, five, four, and finally three. This design keeps the gas flowing smoothly while gradually reducing the number of channels, which accelerates the gas during the flow process and enhances the drainage capacity. This innovative design effectively avoids the occurrence of flooding in traditional flow fields.

[0036] After passing through the reaction area, the gas is gathered at the few-channel gas outlet and finally discharged from the outlet.

[0037] As an optimization solution of the above embodiment, the open connection mode is that the channels of the upper sub-serpentine flow channel and the lower sub-serpentine flow channel are interconnected.

[0038] Preferably, at the corner connection of the sub-serpentine flow channel, the ends of each channel in the sub-serpentine flow channel are staggered in sequence to form a step shape; the step structures at the corner connection of the upper-level sub-serpentine flow channel and the lower-level sub-serpentine flow channel are intertwined and connected to each other.

[0039] As an optimization scheme of the above embodiment, the serpentine channel number decreasing type reaction area includes a first-level sub-serpentine flow channel, a second-level sub-serpentine flow channel, a third-level sub-serpentine flow channel, a fourth-level sub-serpentine flow channel and a fifth-level sub-serpentine flow channel, and the sub-serpentine flow channels of each level are sequentially connected at the corners;

[0040] The first-stage serpentine flow channel includes a parallel seven-channel structure;

[0041] The secondary sub-serpentine flow channel includes a parallel six-channel structure;

[0042] The third-stage serpentine flow channel includes a parallel five-channel structure;

[0043] The fourth-stage serpentine flow channel includes a parallel four-channel structure;

[0044] The five-stage serpentine flow channel includes a parallel three-channel structure.

[0045] The multi-channel gas inlet is a parallel seven-channel gas inlet, and the few-channel gas outlet is a parallel three-channel gas outlet.

[0046] A specific embodiment is as follows:

[0047] The channel width and depth in the sub-serpentine flow channel are both 1 mm, and the width of the ridge is also 1 mm.

[0048] The active area of ​​the flow field is 9700mm 2 (Horizontal 100mm*vertical 97mm).

[0049] At the second turn of the flow channel, the parallel seven channels are reduced to a parallel six-channel design, and an open corner structure is adopted.

[0050] At the fifth turn of the flow channel, the parallel six-channel design is reduced to a parallel five-channel design, and an open corner structure is adopted.

[0051] The design reduces the parallel five-channel design to a parallel four-channel design at the seventh turn of the flow channel and adopts a corner open structure.

[0052] The design reduces the parallel four-channel design to a parallel three-channel design at the eighth turn of the flow channel and adopts a corner open structure.

[0053] The gas is then guided to the outlet through the three parallel channels.

[0054] The design adopts an open structure design at the corners of the area where the number of channels decreases, such as Figure 1 As shown, it can effectively reduce the accumulation of liquid water at the corners, improve gas mass transfer, and ensure smooth reaction. This design overcomes the problem of gas flow obstruction caused by water accumulation at the corners in traditional flow field design.

[0055] The advantages of the present invention are illustrated below by comparing the present invention with Comparative Examples 1 and 2:

[0056] Comparative Example 1: An improved serpentine flow channel design similar to that of patent CN 103746129 A is adopted, and the seven parallel channels are merged into a three-parallel channel design at the first turn of the flow channel; the gas is guided to the outlet through the three parallel flow channels formed after the merger. A closed design is used at the turn after the merger. The flow channel width and depth of Comparative Example 1 are both 1mm, and the ridge width is also 1mm. Figure 2 shown.

[0057] Comparative Example 2: The traditional serpentine flow channel design with the number of channels remaining unchanged is adopted, and a seven-channel parallel design with a closed flow channel bend is adopted. The flow channel width and depth of Comparative Example 2 are both 1 mm, and the ridge width is also 1 mm. Figure 3 shown.

[0058] The performance of this embodiment and comparative examples 1 and 2 were compared under the same operating conditions. The test conditions were: the relative humidity of the gas at the inlet end was 100%, there was no back pressure, and the operating temperature of the fuel cell was 60 degrees Celsius.

[0059] Output performance such as Figure 4 As shown, the peak power density of the fuel cell using the flow field of this embodiment is 501mW cm -2 , which are increased by 4.3% and 17.9% compared with Comparative Example 1 and Comparative Example 2, respectively.

[0060] The comparison results of cathode gas inlet and outlet pressure drops are as follows: Figure 5 As shown, at a current density of 1300 mA cm -2 Under the working condition, the cathode gas inlet and outlet pressure drops of the embodiment and comparative example 1 increased by 9.0% and 57.3% respectively compared with comparative example 2. Therefore, the gas inlet and outlet pressure drop of the embodiment is significantly reduced compared with comparative example 2, thereby improving the system efficiency of the fuel cell.

[0061] comprehensive Figure 4 and Figure 5 It can be seen from the data that the embodiment significantly improves the performance of the fuel cell at the cost of appropriately increasing the cathode inlet and outlet pressure drop, and can achieve a better balance between the battery system efficiency and drainage capacity.

[0062] The superiority of the embodiment in performance can be attributed to the following points:

[0063] First, the embodiment effectively avoids the drainage difficulty problem caused by the low gas flow rate and the use of a closed structure at the bend of the flow channel in Comparative Example 2. By gradually reducing the number of channels, the embodiment can maintain smooth gas flow while continuously accelerating the gas during the flow process, thereby improving the drainage capacity of the fuel cell; secondly, compared with the improved fuel cell serpentine flow field proposed in patent CN 103746129 A, the embodiment adopts a scheme of gradually decreasing the number of channels, which still improves the battery performance while greatly reducing the cathode inlet and outlet pressure drop, and achieves a better balance between the battery system efficiency and the drainage capacity; in addition, the embodiment adopts an open structure in the reaction area with a gradually decreasing number of channels, which can further reduce the probability of flooding failure of the fuel cell under high current density.

[0064] In summary, the present invention, through innovative flow field design, substantially improves the drainage capacity and gas mass transfer efficiency of the fuel cell without substantially increasing the system complexity and manufacturing cost, and solves the flooding problem existing in the traditional serpentine flow field. The invention has broad application prospects and provides a strong guarantee for the efficient operation of proton exchange membrane fuel cells.

[0065] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A fuel cell channel number decreasing serpentine flow field that is beneficial to drainage, characterized in that: include: A reaction area with a decreasing number of serpentine channels, comprising multiple groups of sub-serpentine flow channels, which are sequentially connected at the corners to form a multi-stage reaction area from top to bottom, wherein the number of channels in each sub-serpentine flow channel decreases step by step, and an open connection method is adopted at the connecting corners of each sub-serpentine flow channel; A multi-channel gas inlet is arranged at the beginning of the reaction area with a decreasing number of serpentine channels; and a few-channel gas outlet, which is arranged at the end of the serpentine channel number decreasing type reaction area.

2. The fuel cell channel number decreasing serpentine flow field that is beneficial to drainage according to claim 1, characterized in that: The open connection mode is that the channels of the upper sub-serpentine flow channel and the lower sub-serpentine flow channel are interconnected.

3. The fuel cell channel number decreasing serpentine flow field that is beneficial to drainage according to claim 2, characterized in that: At the corner connection of the sub-serpentine flow channel, the ends of each channel in the sub-serpentine flow channel are staggered in sequence to form a step shape; the step structures at the corner connection of the upper-level sub-serpentine flow channel and the lower-level sub-serpentine flow channel are intertwined and connected with each other.

4. A fuel cell channel number decreasing serpentine flow field that is beneficial to drainage according to any one of claims 1 to 3, characterized in that: The width and depth of the sub-serpentine flow channel are both 1 mm.

5. A fuel cell channel number decreasing serpentine flow field that is beneficial to drainage according to any one of claims 1 to 3, characterized in that: The serpentine channel number decreasing type reaction area comprises a first-level sub-serpentine flow channel, a second-level sub-serpentine flow channel, a third-level sub-serpentine flow channel, a fourth-level sub-serpentine flow channel and a fifth-level sub-serpentine flow channel, and the sub-serpentine flow channels of each level are sequentially connected at the corners; The first-stage serpentine flow channel includes a parallel seven-channel structure; The secondary sub-serpentine flow channel includes a parallel six-channel structure; The third-stage serpentine flow channel includes a parallel five-channel structure; The fourth-stage serpentine flow channel includes a parallel four-channel structure; The five-stage serpentine flow channel includes a parallel three-channel structure.

6. The fuel cell channel number decreasing serpentine flow field that is beneficial to drainage according to claim 5, characterized in that: The multi-channel gas inlet is a parallel seven-channel gas inlet, and the few-channel gas outlet is a parallel three-channel gas outlet.

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