Gas flow channel opening and bipolar plate

Abstract

The invention relates to a gas flow channel opening and bipolar plate structure for a proton exchange membrane (PEM) electrolytic cell, and aims to solve the challenge of an ultra-large electrolytic cell in the aspect of gas emission. By innovatively designing the divergent streamline flow channel opening, the sectional area of the flow channel opening is greatly expanded, and the directional groove array is constructed on the inner surface of the flow channel opening, the gas flow resistance is effectively reduced, the gas discharge efficiency is improved, and the gas-liquid distribution is balanced. In addition, the bipolar plate adopts a multi-layer composite structure, so that the stability and the production efficiency of the electrolytic cell are ensured. According to the implementation of the invention, the overall performance of the PEM electrolytic cell is remarkably improved, and powerful support is provided for realizing an efficient and stable hydrogen production process.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production by electrolysis of water, and in particular to a gas flow channel opening and a bipolar plate structure for a proton exchange membrane (PEM) electrolyzer. Background Art

[0002] As the global demand for clean energy rises sharply, proton exchange membrane water electrolysis has attracted much attention as an efficient and clean hydrogen production technology. PEM electrolyzers use proton exchange membranes as electrolytes to decompose water into hydrogen and oxygen under the action of direct current. In this process, the rapid and smooth discharge of gas plays a decisive role in the stable operation and production efficiency of the electrolyzer.

[0003] The design of the flow channel openings of the traditional PEM electrolyzer bipolar plates focuses more on compactness and easy processing. The size of the flow channel openings is relatively small, which makes it difficult to meet the needs of rapid discharge after large-scale gas production in super-large electrolyzers. When the scale of the electrolyzer is expanded and the current density is increased, the gas generation rate increases exponentially. The narrow flow channel openings are prone to gas blockage and pressure accumulation, resulting in uneven gas-liquid distribution on both sides of the electrolyte membrane, exacerbating the concentration polarization phenomenon; not only does it reduce the electrolysis efficiency, it may also damage the proton exchange membrane, greatly reduce its service life, and increase equipment maintenance costs and operating risks. In addition, the shape design of the ordinary flow channel openings lacks precise consideration of the flow field fluid dynamics, the gas flow resistance is large, and the energy loss increases accordingly, which is not conducive to the realization of an efficient and economical hydrogen production process. Summary of the invention

[0004] The present invention aims to overcome the defects of the prior art and provide a new gas flow channel and bipolar plate structure, which is specially designed for ultra-large PEM electrolyzers to achieve the purpose of reducing gas flow resistance, efficiently removing gas, and balancing gas-liquid distribution, thereby significantly improving the production efficiency and stability of the electrolyzer.

[0005] The key design points of the gas flow channel and bipolar plate of the present invention include unique flow channel shape, size optimization and surface microstructure processing, as follows: Flow channel shape design: abandoning the traditional rectangular and circular flow channel, innovatively adopting a gradually expanding streamlined structure. The inlet end is narrow, which fits the initial low-speed generation state of the gas and accurately guides the airflow; as the flow channel extends, the width and height gradually expand according to a specific curve law, which fits the trend of gas acceleration and flow increase, making the gas flow smooth and without mutation, effectively reducing turbulence and energy loss. After computational fluid dynamics (CFD) simulation optimization, the curve fits the gas flow velocity-pressure distribution characteristics, can maintain a stable flow state under different working conditions, and promote the gas to flow quickly to the outlet.

[0006] Super-large size planning: Based on the estimated gas production scale and flow rate of super-large electrolyzers, the cross-sectional area of ​​the flow channel is greatly widened. The width can reach 2-3 times that of conventional designs, and the height can be flexibly adapted according to the number of electrolyzer stacking layers and the electrode spacing to ensure that the gas can escape unhindered when running at high current density to avoid excessive local pressure; at the same time, in order to adapt to the mechanical requirements of large structures, reinforcing ribs are added around the flow channel to ensure stability with lightweight alloy materials to resist internal air pressure shocks and external assembly stresses.

[0007] Surface microstructure treatment: Using micro-nano processing technology, a directional groove array is constructed on the inner surface of the flow channel. The groove depth is 1-5 microns and the width is 5-20 microns, arranged according to the gas flow direction. This microstructure uses surface tension and gas viscosity to cleverly guide the boundary layer gas flow and weaken the near-wall airflow resistance, as if opening up a "high-speed channel" for the gas. In conjunction with the streamlined design, the total flow resistance is further reduced by more than 30%.

[0008] As a key component of integrated flow channel, the bipolar plate adopts a multi-layer composite structure: the base layer is made of highly conductive and corrosion-resistant graphite / metal composite materials to ensure electronic conduction; the middle layer is a polymer film with gas barrier and hydrophilicity regulation functions to optimize gas-liquid separation efficiency; the outer layer is covered with a corrosion-resistant coating, which is tightly attached through a special sintering process to resist electrolyte corrosion and gas erosion. The flow channel layout on the bipolar plate is symmetrically distributed in an array, accurately matching the electrode reaction area, ensuring uniform gas extraction, and maintaining pressure balance inside the electrolyzer. . BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 : Schematic diagram of the structure of one side of the bipolar plate; Figure 2 : Schematic diagram of the structure on the other side of the bipolar plate; Figure 3 : Microstructure of inner surface of flow channel; Wherein: the above drawings include the following reference numerals: 10. electrode plate; 11. first flow slot; 12. first gradually expanding flow hole; 21. second flow slot; 22. second rectangular flow hole; 31. groove array DETAILED DESCRIPTION

[0010] In order to achieve the purpose of the present invention, the specific implementation methods of the gas flow channel opening and the bipolar plate structure will be described in detail below.

[0011] 1. Production and design of gas flow channel First, we use advanced manufacturing technology to make the gas flow channel according to the specific needs of ultra-large PEM electrolyzers. We abandon the traditional rectangular and circular designs and innovatively adopt a gradually expanding streamlined structure.

[0012] Through precise computational fluid dynamics (CFD) simulation, the initial narrow inlet end of the flow channel is determined to adapt to the initial low-speed generation state of the gas. As the flow channel extends, its width and height gradually expand according to a carefully designed specific curve. This curve is determined based on in-depth research and optimization of the gas flow rate and pressure distribution characteristics. It can maintain a stable flow state under different working conditions, making the gas flow smooth and without mutation, effectively reducing turbulence and energy loss.

[0013] 2. Structural design and production of bipolar plates As a key component, the structural design of the bipolar plate is of vital importance. We use a multi-layer composite structure, and the base layer is made of graphite / metal composite materials with high conductivity and excellent corrosion resistance to ensure good electronic conduction performance.

[0014] The middle layer is a polymer film with excellent gas barrier and hydrophilicity regulation functions, which optimizes the gas-liquid separation efficiency. The outer layer is covered with a corrosion-resistant coating, which is tightly attached through a special sintering process to resist electrolyte corrosion and gas erosion.

[0015] On the bipolar plate, the flow openings are arranged in a symmetrical array to precisely match the electrode reaction zone, ensuring that the gas can be evenly extracted and maintaining the pressure balance inside the electrolyzer.

[0016] 3. Surface microstructure treatment Using micro-nano processing technology, a directional groove array is constructed on the inner surface of the flow channel. The depth of the groove is between 1 and 5 microns, the width is 5 to 20 microns, and it is arranged strictly according to the gas flow direction. This microstructure uses surface tension and gas viscosity to cleverly guide the boundary layer gas flow and weaken the near-wall airflow resistance, as if opening up a "high-speed channel" for the gas, and cooperates with the streamlined design to further significantly reduce the total flow resistance.

[0017] Through the above specific implementation methods, the gas flow channel opening and bipolar plate structure proposed in the present invention can be realized, thereby effectively improving the production efficiency and stability of ultra-large PEM electrolyzers in practical applications.

Claims

1. A gas flow channel for a proton exchange membrane electrolyzer, characterized in that: The flow channel opening adopts a gradually expanding streamlined structure, with a narrow inlet end and then gradually expanding in width and height along the extension direction of the flow channel according to a specific curve rule.

2. The gas flow channel according to claim 1, wherein the specific curve law is determined by computational fluid dynamics simulation optimization to maintain a stable flow state under different working conditions and reduce energy loss.

3. According to claim 1 or 2, the cross-sectional area of ​​the gas flow channel opening is greatly widened, the width can reach 2-3 times of the conventional design, and the height can be flexibly adapted according to the number of stacked layers of the electrolytic cell and the electrode spacing.

4. The gas flow port according to any of the above claims, wherein an array of directional grooves is constructed on the inner surface of the flow port, the grooves have a depth of 1-5 microns and a width of 5-20 microns, and are arranged according to the gas flow direction to further reduce flow resistance.

5. A bipolar plate, characterized in that: The bipolar plate is integrated with the gas flow channel opening according to any one of claims 1 to 4, and adopts a multi-layer composite structure, including a base layer, an intermediate layer and an outer layer.

6. The bipolar plate according to claim 5, wherein the base layer is a highly conductive, corrosion-resistant graphite / metal composite material; the middle layer is a polymer film with gas barrier and hydrophilicity regulation functions; and the outer layer is covered with a corrosion-resistant coating.

7. The bipolar plate according to claim 5 or 6, wherein the flow channel openings are symmetrically distributed in an array on the bipolar plate, accurately matching the electrode reaction area to ensure uniform gas extraction and pressure balance inside the electrolytic cell.

8. A proton exchange membrane electrolyzer, characterized in that: The electrolytic cell is equipped with a bipolar plate according to any one of claims 5 to 7.

9. The protection scope of the present invention includes but is not limited to the contents described in the above claims. Any technical solution that is equivalent to or simply modified to the present invention should fall within the protection scope of the present invention.

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