Proton exchange membrane fuel cell runner with variable throttling characteristic and bipolar plate

Abstract

The invention provides a proton exchange membrane fuel cell flow channel with a variable throttling characteristic and a bipolar plate, and relates to the technical field of proton exchange membrane hydrogen fuel cell systems, the proton exchange membrane fuel cell flow channel comprises flow channels, channel grooves and throttling characteristics, the flow channels are periodic flow channels, a plurality of flow channels are arranged in an array, the channel grooves are arranged in the flow channels, and the throttling characteristics are arranged in the channel grooves. A throttling feature is arranged in the channel groove; a plurality of groups of circulations are arranged on the flow channel, a first circulation is arranged on the inlet side of the flow channel, the lengths of the plurality of groups of circulations are gradually reduced from the first circulation in the fluid flowing direction, the period of the first circulation is a first period, and the period lengths of the plurality of groups of circulations are gradually reduced from the first period in the fluid flowing direction. Due to the transverse component of the fluid flow vector, the transverse mass transfer efficiency between the adjacent flow channels is improved. Due to the existence of the throttling characteristic, the flow velocity and the fluid pressure in the flow channel can be correspondingly adjusted, the variable throttling characteristic generates vortex locally, and the mass transfer from the ridge to the GDL is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of proton exchange membrane hydrogen fuel cell systems, and in particular to a proton exchange membrane fuel cell flow channel and a bipolar plate with variable throttling characteristics. Background Art

[0002] A proton exchange membrane hydrogen fuel cell is a power generation device that uses hydrogen as fuel. Hydrogen generates water and electricity through electrochemical reactions. The smallest component unit that completes the electrochemical reaction in a fuel cell is called a single cell, which is composed of an anode plate, a membrane electrode, and a cathode plate. The bipolar plate composed of the anode plate and the cathode plate is one of the core components of the fuel cell, which plays the role of supporting the membrane electrode, providing reaction gas and coolant flow channels, and conducting charge and heat. Common bipolar plates are spliced ​​by one anode plate and one cathode plate. The outside of the anode plate has a hydrogen flow field, the outside of the cathode plate has an air flow field, and the two plates form a coolant flow field. The outer flow field area of ​​the anode and cathode corresponds to the active area on the membrane electrode, which is an important area for generating electrochemical reactions. The design of the flow channel determines the flow state of the reaction gas in the flow field. Reasonable flow channel design can ensure that the electrochemical reaction can proceed normally and improve the mass transfer efficiency of the reactants. At the same time, the water of the reaction product is discharged from the flow field in time, thereby improving the performance of the fuel cell. At present, the most common flow channels are parallel flow channels, including straight flow channels, serpentine flow channels, S-shaped flow channels, etc.

[0003] The straight flow channel has the advantages of simple structure and easy manufacturing. Its total length is shorter than other types of flow channels, so the flow resistance and pressure drop are smaller. However, due to the smaller flow resistance, the reactants stay in the flow field where most electrochemical reactions occur for a shorter time, thereby reducing the utilization rate of the reactants. Although the existing flow channel bottom structure can improve the gas mass transfer efficiency, it will form a large flow resistance and pressure drop, resulting in low lateral mass transfer efficiency and low ridge mass transfer efficiency between the flow channels, which is not conducive to the water management of the stack with self-humidification function. Summary of the invention

[0004] In view of the defects in the prior art, an object of the present invention is to provide a proton exchange membrane fuel cell flow channel and a bipolar plate with variable throttling characteristics.

[0005] According to the present invention, a proton exchange membrane fuel cell flow channel with a variable throttling feature includes a flow channel, a channel groove and a throttling feature. The flow channel is a periodic flow channel, a plurality of flow channels are arranged in an array, a channel groove is provided in the flow channel, and a throttling feature is provided in the channel groove;

[0006] There are multiple sets of circulations on the flow channel, the inlet side of the flow channel is the first circulation, the lengths of the multiple sets of circulations gradually decrease from the first circulation along the direction of fluid flow, the period of the first circulation is the first period, and the period lengths of the multiple sets of circulations gradually decrease from the first period along the direction of fluid flow.

[0007] Preferably, in each flow channel, the throttling features are located at the crests and troughs of the flow channel;

[0008] Alternatively, in two adjacent flow channels, a throttling feature is provided on a transition section on the downstream side of a wave crest of one flow channel, and a throttling feature is provided on a transition section on the downstream side of a wave trough of an adjacent flow channel;

[0009] Alternatively, in two adjacent flow channels, throttling features are provided at the crests and troughs of one flow channel, and throttling features are provided at the transition between the crests and troughs of the other adjacent flow channel, and the spacing distance of the throttling features is equal to the flow channel cycle period.

[0010] Preferably, the height of the throttling feature increases with the increase of the liquid water content in the flow channel, and the height of the throttling feature is 0-40% of the depth of the channel groove.

[0011] Preferably, the throttling characteristics in each flow channel are highly the same;

[0012] Alternatively, the throttling characteristics in two adjacent flow channels are highly switched alternately;

[0013] Alternatively, two adjacent throttling feature heights in the flow channel are switched alternately.

[0014] Preferably, a plurality of groups of cycles are provided with oblique line segments, the oblique line segments are projected along the extension direction of the flow channel, and the length of the oblique line segments is shortened along the extension direction of the flow channel from the first cycle.

[0015] Preferably, the initial length W of the oblique line segment is repeated N times continuously, and the length of the oblique line segment is shortened by % to enter the next cycle, and the number of subsequent cycles is the same as the initial number, and this is repeated until the end of the flow channel;

[0016] Alternatively, the number of subsequent cycles N is increased or decreased based on the initial number;

[0017] Alternatively, the number of subsequent cycles is taken in an alternating manner of odd and even numbers according to the initial number of repetitions.

[0018] Preferably, each bend of the channel is provided with a throttling feature, and the height of the throttling feature is 0.03-0.132 mm and the length is 0.8 mm.

[0019] Preferably, the height of the throttling feature is controlled by the following sigmoid function:

[0020]

[0021] Among them, the first bending point is taken as the origin of the function, the X coordinate is expanded along the extension direction of the flow channel, the variable X represents the displacement of each throttling feature relative to the origin, e is a natural constant, and k, m, n, and q are all constants.

[0022] Preferably, each flow channel forms a trigonometric function (sine or cosine function) with a constant period / frequency, and its function expression is:

[0023] f(x)=A·sin(Bx+C)+D

[0024] Where x and f(x) represent the displacement from the origin along the direction of the flow channel extension and the displacement of the center line of the flow channel in the orthogonal direction at x, respectively, and A, B, C, and D are all constants.

[0025] The present invention also provides a bipolar plate including a proton exchange membrane fuel cell flow channel with a variable throttling feature.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) Due to the lateral component of the fluid flow vector, the lateral mass transfer efficiency between adjacent flow channels is improved. In addition, due to the existence of the throttling feature, the flow velocity and fluid pressure in the flow channel can be adjusted accordingly. The throttling feature can also generate vortices locally to improve the mass transfer from the ridge to the GDL;

[0028] (2) The height and distribution density of the throttling feature in the present invention can be adjusted according to the liquid water content in the flow channel, which is beneficial to the water management of the stack with self-humidification function.

[0029] (3) In the present invention, the throttling features are arranged alternately in every two adjacent flow channels, thereby generating a flow velocity difference and a pressure difference of the gas between different flow channels, thereby improving the mass transfer capacity under the ridge. Similarly, alternating different throttling heights in the same flow channel will also generate a flow velocity difference and a pressure difference of the gas, thereby improving the mass transfer efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0031] Figure 1 It is a schematic diagram of the structure in Embodiment 1 of the present invention;

[0032] Figure 2 It is a schematic diagram of the local structure of the present invention;

[0033] Figure 3 A top view of the present invention;

[0034] Figure 4This is a schematic diagram of the structure of Embodiment 2 of the present invention;

[0035] Figure 5 This is a schematic diagram of the structure in Example 3 of the present invention.

[0036] The figure shows: flow channel 1, channel groove 2, and throttling feature 3. DETAILED DESCRIPTION

[0037] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0038] Example 1

[0039] According to the present invention, a proton exchange membrane fuel cell flow channel with variable throttling characteristics is provided, such as Figure 1-4 As shown, it includes a flow channel 1, a channel groove 2 and a throttling feature 3. The flow channel 1 is a periodic flow channel 1, which is wavy or zigzag. There are multiple sets of cycles on the flow channel 1. The inlet side of the flow channel 1 is the first cycle. The length of the multiple sets of cycles gradually decreases from the first cycle along the direction of fluid flow. The period of the first cycle is the first period. The period length of the multiple sets of cycles gradually decreases from the first period along the direction of fluid flow. The length Wi of the oblique line segment gradually shortens. The length of the oblique line segment is defined as the projected length of the oblique line segment along the extension direction of the flow channel 1, that is, the length of the bends of every two adjacent flow channels 1. Multiple flow channels 1 are arranged in an array, and a channel groove 2 is provided in the flow channel 1, and a throttling feature 3 is provided in the channel groove 2.

[0040] In each flow channel 1, the throttling feature 3 is located at the crest and trough of the flow channel 1; or, in two adjacent flow channels 1, a throttling feature 3 is provided on the transition section on the downstream side of the crest of one flow channel 1, and a throttling feature 3 is provided on the transition section on the downstream side of the trough of an adjacent flow channel 1; or, in two adjacent flow channels 1, a throttling feature 3 is provided at the crest and trough of one flow channel 1, and a throttling feature 3 is provided on the transition between the crest and trough of another adjacent flow channel 1, and the spacing distance of the throttling features 3 is equal to the cycle period of the flow channel 1.

[0041] The height of the throttling feature 3 increases with the increase of the liquid water content in the flow channel 1, and the height of the throttling feature 3 is 0-40% of the depth of the channel groove 2. The height of the throttling feature 3 includes but is not limited to the following: the height of the throttling feature 3 is the same in each flow channel 1; or, the height of the throttling feature 3 in two adjacent flow channels 1 alternately uses two different height values ​​within the aforementioned height range; or, in the same flow channel 1, the height of two adjacent throttling features 3 alternately uses two different height values ​​within the aforementioned height range.

[0042] Each flow channel 1 forms a trigonometric function (sine or cosine function) with a constant period / frequency, and its function expression is:

[0043] f(x)=A·sin(Bx+C)+D

[0044] Where x and f(x) represent the displacement from the origin along the extension direction of flow channel 1 and the displacement of the center line of flow channel 1 in the orthogonal direction at x, respectively, and A, B, C, and D are all constants.

[0045] The height of throttling feature 3 is controlled by the following sigmoid function:

[0046]

[0047] The first bending point is taken as the origin of the function, the X coordinate is expanded along the extension direction of the flow channel 1, the variable X represents the displacement of each throttling feature 3 relative to the origin, e is a natural constant, and k, m, n, and q are all constants.

[0048] Example 2

[0049] This embodiment 2 is completed on the basis of embodiment 1. Figure 4 As shown, a throttling feature 3 with a height of 40% of the depth of the channel 1 and a length of 0.8 mm is placed at each bend of the zigzag line. The length of the oblique line segment can be arranged in a variety of ways, including but not limited to the following:

[0050] The initial oblique line segment length W1 will be repeated N times, in this embodiment, 4 times (N=4), and then the oblique line segment length will be shortened by 20% to enter the next stage. The cycle rule is the same as the previous cycle and is repeated until the end of the flow channel 1. The number of cycles N and the shortening percentage can be freely adjusted to adapt to different flow channel 1 lengths.

[0051] Alternatively, the number of subsequent repetitions can be gradually increased or decreased based on the initial number.

[0052] Alternatively, the subsequent repetition times are taken in an alternating manner of odd and even numbers according to the initial repetition times.

[0053] Example 3

[0054] This embodiment 3 is completed on the basis of embodiment 1, using a zigzag line, and the spacing between adjacent bends is unchanged. A 0.8 mm long throttling feature 3 is placed at each bend of the zigzag line. The height of the throttling feature 3 is set between 0.03 mm and the maximum (40% of the groove depth of the flow channel 1 in this embodiment) 0.132 mm, and its height variation process is controlled by the following sigmoid function:

[0055]

[0056] The first bending point is taken as the origin of the function, the X coordinate is expanded along the extension direction of the flow channel 1, and the variable X represents the displacement of each throttling feature 3 relative to the origin.

[0057] More specifically, Figure 5 As shown, each flow channel 1 has a total of 16 throttling features 3, which are placed in the flow channel 1 at a fixed interval of 12.8 mm. The converted height of each throttling feature 3 is shown in the following table:

[0058]

[0059]

[0060] Example 4

[0061] The present invention also provides a bipolar plate, including the proton exchange membrane fuel cell flow channel with variable throttling characteristics in Example 1. The bipolar plate can be made of metal, graphite or composite material.

[0062] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0063] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A proton exchange membrane fuel cell flow channel with variable throttling characteristics, characterized in that: It comprises a flow channel (1), a channel groove (2) and a throttling feature (3), wherein the flow channel (1) is a periodic flow channel, a plurality of the flow channels (1) are arranged in an array, the flow channel (1) is provided with the channel groove (2), and the throttling feature (3) is provided in the channel groove (2); The flow channel (1) is provided with a plurality of cycles, the inlet side of the flow channel (1) is a first cycle, the lengths of the plurality of cycles gradually decrease from the first cycle along the direction of fluid flow, the period of the first cycle is a first period, and the period lengths of the plurality of cycles gradually decrease from the first period along the direction of fluid flow.

2. The proton exchange membrane fuel cell flow channel 1 with variable throttling characteristics according to claim 1 is characterized in that: In each of the flow channels (1), the throttling features (3) are located at the crests and troughs of the flow channel (1); Alternatively, in two adjacent flow channels (1), the throttling feature (3) is provided on the transition section on the downstream side of the wave crest of one flow channel (1), and the throttling feature (3) is provided on the transition section on the downstream side of the wave trough of the adjacent flow channel (1); Alternatively, in two adjacent flow channels (1), the throttling feature (3) is provided at the wave crest and wave trough positions of one of the flow channels (1), and the throttling feature (3) is provided at the transition between the wave crest and the wave trough of the other adjacent flow channel (1), and the spacing distance of the throttling features (3) is equal to the cycle period of the flow channel (1).

3. The proton exchange membrane fuel cell flow channel with variable throttling characteristics according to claim 1, characterized in that: The height of the throttling feature (3) increases with the increase of the liquid water content in the flow channel (1), and the height of the throttling feature (3) is 0-40% of the depth of the channel groove (2).

4. The proton exchange membrane fuel cell flow channel with variable throttling characteristics according to claim 3, characterized in that: The throttling feature (3) in each of the flow channels (1) has the same height; Alternatively, the throttling characteristics (3) in two adjacent flow channels (1) are highly switched alternately; Alternatively, the heights of two adjacent throttling features (3) in the flow channel (1) are switched alternately.

5. The proton exchange membrane fuel cell flow channel with variable throttling characteristics according to claim 1, characterized in that: A plurality of groups of the loops are provided with oblique line segments, the oblique line segments are projected along the extension direction of the flow channel (1), and the length of the oblique line segments is shortened along the extension direction of the flow channel (1) from the first loop.

6. The proton exchange membrane fuel cell flow channel with variable throttling characteristics according to claim 5, characterized in that: The initial length W1 of the oblique line segment is repeated N times continuously, and the length of the oblique line segment is shortened by 20% to enter the next cycle, and the number of subsequent cycles is the same as the initial number, and this is repeated until the end of the flow channel (1); Alternatively, the number of subsequent cycles N is increased or decreased based on the initial number; Alternatively, the number of subsequent cycles is taken in an alternating manner of odd and even numbers according to the initial number of repetitions.

7. The proton exchange membrane fuel cell flow channel with variable throttling characteristics according to claim 3, characterized in that: The throttling feature (3) is provided at each bend of the channel, and the height of the throttling feature (3) is 0.03-0.132 mm and the length is 0.8 mm.

8. The proton exchange membrane fuel cell flow channel with variable throttling characteristics according to claim 1, characterized in that: The height of the throttling feature (3) is controlled by the following sigmoid function: The first bending point is taken as the origin of the function, the X coordinate is expanded along the extension direction of the flow channel 1, the variable X represents the displacement of each throttling feature (3) relative to the origin, e is a natural constant, and k, m, n, q are all constants.

9. The proton exchange membrane fuel cell flow channel with variable throttling characteristics according to claim 1, characterized in that: Each of the flow channels (1) forms a trigonometric function with a constant period / frequency, and the function expression is: f(x)=A·sin(Bx+C)+D Wherein, x and f(x) represent the displacement from the origin along the extension direction of the flow channel (1) and the displacement of the center line of the flow channel (1) in the orthogonal direction at x, respectively, and A, B, C, and D are all constants.

10. A bipolar plate, characterized in that: A proton exchange membrane fuel cell flow channel with variable throttling characteristics comprising any one of claims 1-9.

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