WO2024130948A1

WO2024130948A1 - Bipolar plate flow field structure and fluid flow direction control method thereof and fuel cell

Info

Publication number: WO2024130948A1
Application number: PCT/CN2023/094992
Authority: WO
Inventors: 麦建明; 白云飞
Original assignee: 上海氢晨新能源科技有限公司
Priority date: 2022-12-20
Filing date: 2023-05-18
Publication date: 2024-06-27
Also published as: CN115621485A; CN115621485B

Abstract

The present invention relates to the field of fuel cells, and provides a bipolar plate flow field structure and a fluid flow direction control method thereof and a fuel cell. The bipolar plate flow field structure specifically comprises a first flow field gas inlet, at least one second flow field gas inlet, a first flow field gas outlet, and at least one second flow field gas outlet, wherein the first flow field gas inlet and the first flow field gas outlet are oppositely arranged along a main flow channel of a bipolar plate, the second flow field gas inlet and the second flow field gas outlet are oppositely arranged along the main flow channel of the bipolar plate, and the second flow field gas inlet and the second flow field gas outlet are opened and closed by means of a valve outside a reactor core, so as to change the fluid direction in the flow field. According to the processing scheme, the fluid flow direction in the flow field can be changed.

Description

Bipolar plate flow field structure and fluid flow direction control method thereof, fuel cell

Technical Field

The present invention relates to the field of fuel cells, and in particular to a bipolar plate flow field structure and a fluid flow direction control method thereof, and a fuel cell.

Background technique

The core of the fuel cell is the membrane electrode and bipolar plate. The membrane electrode is the site of the electrochemical reaction; the bipolar plate provides gas distribution and collects current. In current production, the power generation efficiency of the fuel cell is largely limited by the structure of the bipolar plate flow field. A high-quality flow field structure can improve the flow state of reactants and products, so that reactants can be obtained in time at all parts of the electrode, and cooling water can be removed in time to improve the power generation efficiency of the fuel cell. The design of the flow field on the bipolar plate is a single form. The bipolar plate needs to provide gas distribution for different working conditions of the fuel cell. For example, under light load conditions, the flow rate is low, resulting in insufficient gas exchange and mass transfer performance, and under heavy load conditions, the air compressor power consumption is too high due to the large flow resistance. This limits the performance of the fuel cell.

Summary of the invention

Therefore, in order to overcome the above-mentioned shortcomings of the prior art, the present invention provides a bipolar plate flow field structure with variable fluid flow direction in the flow field, a fluid flow direction control method of the bipolar plate flow field structure, and a fuel cell.

In order to achieve the above-mentioned objectives, the present invention provides a bipolar plate flow field structure, comprising a first flow field air inlet, at least one second flow field air inlet, a first flow field exhaust port and at least one second flow field exhaust port, wherein the first flow field air inlet and the first flow field exhaust port are arranged opposite to each other along the main flow channel of the bipolar plate, the second flow field air inlet and the second flow field exhaust port are arranged opposite to each other along the main flow channel of the bipolar plate, and the second flow field air inlet and the second flow field exhaust port are opened and closed by valves outside the core, thereby realizing the change of fluid direction in the flow field.

In one embodiment, a width ratio of the first flow field air inlet to the second flow field air inlet is 1:0.5-5.

In one embodiment, the width ratio of the first flow field exhaust port to the second flow field exhaust port is 1:0.5-5.

In one embodiment, the bipolar plate is provided with a secondary flow channel near the second flow field air inlet and/or the second flow field exhaust port, and the secondary flow channel and the main flow channel have different feature settings.

In one embodiment, the main flow channel is at least one of a straight flow channel, a winding flow channel, an undulating flow channel and a staggered flow channel.

A method for controlling fluid flow direction in a bipolar plate flow field structure comprises: obtaining the current operating condition of a fuel cell; determining the flow direction of the fluid according to the current operating condition; and opening a valve according to the flow direction of the fluid, wherein the control method is used to control the fluid in the above-mentioned bipolar plate flow field structure.

A fuel cell comprises: a core composed of a plurality of bipolar plates arranged side by side; a valve arranged outside the core and used to adjust the change of fluid direction in the flow field, wherein the control method of the fluid direction adopts the above method.

Compared with the prior art, the advantages of the present invention are: by setting multiple air inlets and exhaust ports, and using valves outside the core to control the activation or not of the multiple air inlets and exhaust ports, the fluid flow direction in the flow field can be changed, thereby changing the overall flow direction of the flow field, and improving the gas flow rate distribution and pressure drop under different working conditions, thereby enhancing the gas exchange performance under light load conditions, or reducing the air compressor power consumption under heavy load conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

FIG1 is a schematic structural diagram of a fuel cell in an embodiment of the present invention;

FIG2 is a schematic structural diagram of a fuel cell core in an embodiment of the present invention;

FIG3 is a schematic structural diagram of a fuel cell core in an embodiment of the present invention;

4 is a schematic diagram of a first fluid flow direction of a bipolar plate flow field structure according to an embodiment of the present invention;

5 is a schematic diagram of a second fluid flow direction of a bipolar plate flow field structure according to an embodiment of the present invention;

6 is a schematic diagram of a first fluid flow direction of a bipolar plate flow field structure according to an embodiment of the present invention;

7 is a schematic diagram of a second fluid flow direction of a bipolar plate flow field structure according to an embodiment of the present invention;

8 is a schematic diagram of a first fluid flow direction of a bipolar plate flow field structure according to an embodiment of the present invention;

FIG. 9 is a schematic diagram of a first fluid flow direction of a bipolar plate flow field structure in an embodiment of the present invention.

Detailed ways

The embodiments of the present application are described in detail below with reference to the accompanying drawings.

The following describes the implementation methods of the present application through specific specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein may be embodied in a wide variety of forms, and any specific structure and/or The functions are illustrative only. Based on the present application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspect described herein can be used to implement the device and/or practice the method. In addition, other structures and/or functionalities other than one or more of the aspects described herein can be used to implement this device and/or practice this method.

It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, one skilled in the art will appreciate that the aspects described may be practiced without these specific details.

As shown in FIG. 1 , an embodiment of the present application provides a fuel cell, including a core 10 and a valve 20 .

As shown in Figures 2 and 3, the core 10 is composed of a plurality of bipolar plates arranged side by side, and the bipolar plates are encapsulated by a shell. The shell of the core 10 is provided with a plurality of through holes 11. The through holes 11 can be used as exhaust ports, drain ports, air inlets or water inlets. In one embodiment, as shown in Figure 4, the flow field structure of the bipolar plate includes a first flow field air inlet 1a, a second flow field air inlet 2a, a first flow field exhaust port 1b and a second flow field exhaust port 2b.

Since the core 10 is composed of a plurality of bipolar plates arranged side by side, and the bipolar plates are consistent, the air inlets 1a, 2a and the exhaust ports 1b, 2b of all unit flow fields form a common gas pipeline in the core of the stacked structure, corresponding to the total air inlets 1A, 2A and the total exhaust ports 1B, 2B. The air inlets 2a of all unit flow fields are controlled for gas supply by valves arranged on the total air inlet 2A, and the exhaust ports 2b of all unit flow fields are controlled for exhaust by valves arranged on the total exhaust port 2B. Therefore, after the bipolar plates are stacked, all the first flow field air inlets 1a will form the first air inlet 1A at the corresponding position of the shell of the core; after the bipolar plates are stacked, all the first flow field exhaust ports 1b will form the first exhaust port 1B at the corresponding position of the shell of the core; after the bipolar plates are stacked, all the second flow field air inlets 2a will form the second air inlet 2A at the corresponding position of the shell of the core; after the bipolar plates are stacked, all the second flow field exhaust ports 2b will form the second exhaust port 2B at the corresponding position of the shell of the core.

As shown in FIGS. 1 to 3 , the valve 20 is disposed outside the core 10 to close the through hole 11, thereby adjusting the change in the direction of the fluid in the flow field. The valve 20 may be disposed near the second air inlet 2A and/or the second exhaust port 2B to close the second air inlet 2A and/or the second exhaust port 2B. The flow field may be the cathode flow field of the fuel cell, or may be the anode flow field, the cooling flow field, etc.

As shown in Figures 4 and 6, in one embodiment, the present application also provides a bipolar plate flow field structure, including a first flow field air inlet 1a, at least one second flow field air inlet 2a, a first flow field exhaust port 1b and at least one second flow field Exhaust port 2b.

The total width of the first flow field air inlet 1a and all the second flow field air inlets 2a is adapted to the total width of the main flow channel of the bipolar plate. In one embodiment, the main flow channel is at least one of a straight flow channel, a winding flow channel, an undulating flow channel and a staggered flow channel.

The total width of the first flow field exhaust port 1b and all the second flow field exhaust ports 2b is adapted to the total width of the main flow channel. The second flow field air inlet 2a and the second flow field exhaust port 2b are opened and closed by valves outside the core, thereby changing the direction of the fluid in the flow field. The valves for opening and closing the second flow field air inlet 2a and the second flow field exhaust port 2b are different valves. The valve material is metal. In one embodiment, the valve material can be an inert metal material.

As shown in Figure 4, 3 is the flow field in the electric field core, and arrow 4 is the flow direction of the fluid in the flow field. When the first flow field air inlet 1a and the first flow field exhaust port 1b are opened, and the second flow field air inlet 2a and the second flow field exhaust port 2b are closed by the valve cutoff outside the core, the fluid in the flow field only enters the flow field from 1a and leaves the flow field only from 1b. The fluid in the flow field flows along the flow direction 4 shown in Figure 4 to form a return flow field. At this time, the cross-sectional area through which the fluid flows is small, the flow path is long, and the flow rate is fast, which is conducive to enhancing gas exchange and material transfer. At this time, the prohibition symbol 21 in Figure 2 indicates that the second air inlet 2A and the second exhaust port 2B are in a closed state, so the flow direction of the fluid in the electric core is as shown in Figure 2.

As shown in FIG5 , when the first flow field air inlet 1a and the first flow field exhaust port 1b are opened, and the second flow field air inlet 2a and the second flow field exhaust port 2b are opened by opening the valve outside the core, the fluid in the flow field enters the flow field from 1a and 2a, and leaves the flow field from 1b and 2b. The fluid in the flow field flows along the flow direction 4 shown in FIG5 , forming a parallel flow field. At this time, the cross-sectional area through which the fluid flows is larger, the flow path is shorter, and the pressure drop is lower, which is conducive to reducing the power consumption of the air compressor. At this time, there is no prohibition symbol 21 at the second air inlet 2A and the second exhaust port 2B in FIG3 , and the flow direction of the fluid in the electric core is as shown in FIG3 .

The above structure realizes the change of fluid flow direction in the flow field by setting multiple air inlets and exhaust ports and using valves outside the core to control the activation or non-activation of multiple air inlets and exhaust ports, thereby changing the overall flow direction of the flow field and improving the gas flow velocity distribution and pressure drop under different working conditions, thereby enhancing the gas exchange performance under light load conditions or reducing the power consumption of the air compressor under heavy load conditions.

As shown in Figures 6 and 7, multiple second flow field air inlets 2a and second flow field exhaust ports 2b are provided, so the flow field has multiple corresponding return areas. The bipolar plate with the above structure is applicable to a wider range of fuel cell operating conditions and a finer adjustment range.

In one embodiment, the core 10 is composed of multiple bipolar plate layers arranged side by side, and each bipolar plate layer has multiple bipolar plates arranged in parallel. Therefore, a first air inlet 1A, a first exhaust port 1B, a second air inlet 2A, and a second exhaust port 2B may exist simultaneously on one side of the core 10.

In one embodiment, the width ratio of the first flow field air inlet to the second flow field air inlet is 1:0.5-5.

As shown in Figures 6 and 7, in one embodiment, the bipolar plate is provided with a secondary flow channel (the cross grid area in the figure) near the second flow field air inlet and/or the second flow field exhaust port, and the feature settings of the secondary flow channel and the main flow channel (the horizontal line area in the figure) are inconsistent. The secondary flow channel can adopt the same flow channel form as the main flow channel, or a different flow channel form. When the secondary flow channel and the main flow channel adopt the same flow channel form, the characteristic dimensions of the main flow channel and the secondary flow channel, such as width, depth, etc., are inconsistent. When the secondary flow channel and the main flow channel adopt different flow channel forms, the characteristic dimensions of the main flow channel and the secondary flow channel, such as width, depth, etc., may be inconsistent or inconsistent.

As shown in Figures 8 and 9, the first flow field air inlet 1a and the first flow field exhaust port 1b are arranged opposite to each other along the main flow channel of the bipolar plate, and the second flow field air inlet 2a and the second flow field exhaust port 2b are arranged opposite to each other along the main flow channel of the bipolar plate. The staggered arrangement of the first flow field air inlet 1a and the second flow field air inlet 2a in Figures 8 and 9 can better adapt to irregular flow fields and irregular main flow channels.

In an embodiment of the present application, a method for controlling fluid flow direction of a bipolar plate flow field structure is also provided, comprising the following steps:

Step 1, obtaining the current working condition of the fuel cell, which can be determined by detecting the gas or liquid discharged from the fuel cell, or by the battery efficiency, or by other feasible methods. In one embodiment, the current working condition can be represented by the power consumption of the air compressor.

Step 2: Determine the flow direction of the fluid according to the current working condition. When the current working condition is represented by the power consumption of the air compressor, when the power consumption of the air compressor is too high, it can be determined that the fluid flow path is too long and needs to be shortened, and the fluid flow direction is re-determined; when the power consumption of the air compressor is too low, it can be determined that the fluid flow path is too short and needs to be extended, and the fluid flow direction is re-determined.

Step 3: Open the valve according to the flow direction of the fluid. Opening the valve shortens the flow path of the fluid, while closing the valve lengthens the flow path of the fluid.

The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

A bipolar plate flow field structure, characterized in that it comprises a first flow field air inlet, at least one second flow field air inlet, a first flow field exhaust port and at least one second flow field exhaust port,

The first flow field air inlet and the first flow field air outlet are arranged opposite to each other along the main flow channel of the bipolar plate, and the second flow field air inlet and the second flow field air outlet are arranged opposite to each other along the main flow channel of the bipolar plate.

The second flow field air inlet and the second flow field exhaust are opened and closed by valves outside the core, thereby changing the direction of the fluid in the flow field.
The bipolar plate flow field structure according to claim 1 is characterized in that a width ratio of the first flow field air inlet to the second flow field air inlet is 1:0.5-5.
The bipolar plate flow field structure according to claim 1 is characterized in that the width ratio of the first flow field exhaust port to the second flow field exhaust port is 1:0.5-5.
The bipolar plate flow field structure according to claim 1 is characterized in that the bipolar plate is provided with a secondary flow channel near the second flow field air inlet and/or the second flow field exhaust port, and the characteristic settings of the secondary flow channel and the main flow channel are inconsistent.
The bipolar plate flow field structure according to claim 1 is characterized in that the main flow channel is at least one of a straight flow channel, a winding flow channel, an undulating flow channel and a staggered flow channel.
A method for controlling fluid flow direction in a bipolar plate flow field structure, characterized by comprising:

Obtain the current operating condition of the fuel cell;

determining a flow direction of the fluid according to the current working condition;

Open the valve according to the flow direction of the fluid,

Wherein, the control method is used to control the fluid in the bipolar plate flow field structure according to any one of claims 1 to 5.
A fuel cell, characterized by comprising:

The core is composed of a plurality of bipolar plates arranged side by side;

A valve, arranged outside the core, is used to adjust the change of the fluid direction in the flow field,

Wherein, the method for controlling the fluid direction adopts the method described in claim 6.