A gas-water separation flow field structure and a hydrogen production device comprising the same

Abstract

The application discloses a gas-water separation flow field structure and a hydrogen production equipment comprising the same. The gas-water separation flow field structure comprises a bipolar plate. The bipolar plate is provided with a fence at the edge to enclose an enclosed area. The enclosed area is provided with an inlet, an outlet and a flow splitting structure. The flow splitting structure is symmetrical and has two. A main flow channel is reserved between the two flow splitting structures. A branch flow channel is reserved between the flow splitting structure and the fence. The flow splitting structure comprises an inflow flow splitting plate and a plurality of baffle plates. Two adjacent baffle plates form a reaction zone. The two ends of the reaction zone are connected to the main flow channel and the branch flow channel respectively. The electrolyte with a faster moving speed flows in the main flow channel and the branch flow channel. The electrolyte with a slower moving speed is subjected to electrolysis reaction in the reaction zone. The pressure difference is caused by the flow rate difference between the main flow channel, the branch flow channel and the reaction zone. The hydrogen concentration difference exists between the reaction zone and the main flow channel and the branch flow channel. The double power drives the hydrogen in the reaction zone to be discharged quickly.

Description

Technical Field

[0001] This invention relates to the field of water electrolysis for hydrogen production technology, and particularly to a gas-water separation flow field structure and a hydrogen production device including the same. Background Technology

[0002] Anion exchange membrane electrolyzers (AEMWEs) are the core equipment for the large-scale application of water electrolysis for hydrogen production technology. They have advantages such as low operating temperature, controllable cost, and environmental friendliness. However, their development has long been constrained by the following key challenges: Mass transfer performance bottleneck: When traditional flow fields (serpentine flow fields, parallel flow fields, etc.) are running at medium to high current densities, the reactants and products are not separated, and the product hydrogen is prone to stagnation in the flow channel, forming "gas blockage". This causes the reactants to be unable to reach the catalyst layer efficiently and the products to be difficult to discharge quickly, resulting in severe concentration polarization. This causes the polarization curve to enter the limiting current density plateau region or even the decline region too early, which significantly limits the stable operating range and energy conversion efficiency of the electrolyzer.

[0003] High proportion of dead zones in the flow channel: Existing flow fields mostly adopt straight channel or fixed-spaced wall designs, which easily form dead zones on both sides and corners of the flow channel. Product gases cannot be discharged in time, which leads to local concentration polarization. Boundary layer separation is prone to form at the inlet section, and wake vortices are easily generated in the flow channel, which can carry away and hinder water and gas transport, further increasing mass transfer resistance and energy consumption.

[0004] High operating costs: Most existing AEMWEs use catalyst-coated membrane (CCM) type MEAs. When this structure is replaced, the entire membrane and catalyst need to be replaced, resulting in serious catalyst waste and high replacement costs, which restricts the large-scale promotion of the technology.

[0005] Based on this, developing a flow field structure that can alleviate gas blockage and enhance concentration mass transfer at medium and high current densities, and is compatible with low-cost catalyst-coated substrate (CCS) type MEAs, has become a key technological direction for breaking through the bottleneck of large-scale application of AEMWE. Summary of the Invention

[0006] This invention aims to at least solve one of the aforementioned technical problems existing in the prior art. To this end, this application proposes a gas-liquid separation flow field structure that can alleviate gas blockage, enhance concentration mass transfer, and is compatible with the flow field structure of a low-cost CCS-type MEA.

[0007] This application also proposes a hydrogen production device having the above-mentioned gas-water separation flow field structure.

[0008] The gas-water separation flow field structure according to the first aspect embodiment of this application includes: A bipolar plate has a perimeter enclosed area, within which an inlet, an outlet, and a diversion structure are provided. Two diversion structures are symmetrically arranged, with a main flow channel connecting the inlet and outlet between the two diversion structures. A branch flow channel is reserved between the diversion structure and the perimeter. Each diversion structure includes an inlet diversion plate and multiple baffles. The inlet diversion plate diverts the fluid entering from the inlet to the main flow channel and the branch flow channel. A reaction zone is formed between two adjacent baffles, with both ends of the reaction zone connected to the main flow channel and the branch flow channel, respectively. A membrane electrode assembly that transitions from the cathode side to the anode side along the thickness direction; The bipolar plate includes a cathode-side bipolar plate and an anode-side bipolar plate. The cathode-side bipolar plate is attached to the cathode side of the membrane electrode assembly, and the anode-side bipolar plate is attached to the anode side of the membrane electrode assembly.

[0009] The gas-liquid separation flow field structure according to the embodiments of this application has at least the following beneficial effects: by setting a main channel and a branch channel on the bipolar plate, the electrolyte can flow rapidly through the main channel and the branch channel, while the electrolyte flows slowly in the reaction zone and promotes the electrolyte to permeate the membrane electrode assembly to undergo electrolysis reaction; the reaction zone produces a large amount of gas, and the two ends are connected to the main channel and the branch channel respectively. Due to the flow velocity difference, a pressure difference is formed, and the hydrogen concentration difference is formed, which drives the product in the reaction zone to be quickly discharged to the main channel and the branch channel, avoiding gas blockage and dead zones.

[0010] According to some embodiments of this application, the width of the main channel gradually increases along the direction from the inlet to the outlet.

[0011] According to some embodiments of this application, a diversion bend is provided at one end of the inflow diversion plate near the main flow channel, and the diversion bend bends toward the inlet.

[0012] According to some embodiments of this application, the inflow splitter plate is provided with a plurality of grooves at one end near the branch channel, the grooves being used to induce turbulence.

[0013] According to some embodiments of this application, the diversion structure further includes an outflow manifold, which is disposed at the confluence of the main flow channel and the branch flow channel.

[0014] According to some embodiments of this application, the outflow manifold is provided with a plurality of grooves at one end near the branch channel, the grooves being used to induce turbulence.

[0015] According to some embodiments of this application, the end of the baffle is bent toward the outlet.

[0016] According to some embodiments of this application, the bipolar plate further includes a baffle plate disposed in the branch channel and extending along the branch channel.

[0017] According to some embodiments of this application, the bipolar plate is disc-shaped, the main flow channel passes through the center of the bipolar plate, and the branch flow channel extends circumferentially along the bipolar plate.

[0018] The hydrogen production apparatus according to the second aspect of this application includes the gas-water separation flow field structure described above.

[0019] The hydrogen production equipment according to the embodiments of this application has at least the following beneficial effects: by using the above-mentioned gas-water separation flow field structure, the hydrogen production equipment can reduce the occurrence of gas blockage, which is conducive to the efficient discharge of hydrogen products, thereby improving the hydrogen production efficiency.

[0020] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0021] The accompanying drawings are used to provide a further understanding of the technical solutions disclosed in this application and form part of the specification. They are used together with the embodiments disclosed in this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions disclosed in this application.

[0022] Figure 1 This is a disassembled schematic diagram of the gas-water separation flow field structure according to the first aspect embodiment of this application; Figure 2 This is a schematic diagram of the bipolar plate structure in the gas-water separation flow field structure of the first aspect embodiment of this application; Figure 3 This is a schematic diagram of fluid flow in the gas-water separation flow field structure according to the first aspect embodiment of this application.

[0023] Reference numerals: 100-Bipolar plate, 110-Cathode-side bipolar plate, 120-Anode-side bipolar plate, 130-Baffle, 140-Inlet, 150-Outlet, 161-Inflow diverter plate, 1611-Diverter bend plate, 162-Baffle, 163-Outflow manifold plate, 164-Groove, 170-Main flow channel, 180-Branch channel, 190-Break plate, 200-Membrane electrode assembly, 210-Anion exchange membrane, 220-Cathode-side gas diffusion layer, 230-Anode-side gas diffusion layer, 300-Cathode-side end plate, 400-Anode-side end plate. Detailed Implementation

[0024] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0025] In the description of this application, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0026] In the description of this application, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0027] In the description of this application, unless otherwise expressly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0028] In the description of this application, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0029] Anion exchange membrane electrolyzers (AEMWEs) are the core equipment for the large-scale application of water electrolysis for hydrogen production technology. They have advantages such as low operating temperature, controllable cost, and environmental friendliness. However, their development has long been constrained by the following key challenges: Mass transfer performance bottleneck: When traditional flow fields (serpentine flow fields, parallel flow fields, etc.) are running at medium to high current densities, the reactants and products are not separated, and the product hydrogen is prone to stagnation in the flow channel, forming "gas blockage". This causes the reactants to be unable to reach the catalyst layer efficiently and the products to be difficult to discharge quickly, resulting in severe concentration polarization. This causes the polarization curve to enter the limiting current density plateau region or even the decline region too early, which significantly limits the stable operating range and energy conversion efficiency of the electrolyzer.

[0030] High proportion of dead zones in the flow channel: Existing flow fields mostly adopt straight channel or fixed-spaced wall designs, which easily form dead zones on both sides and corners of the flow channel. Product gases cannot be discharged in time, which leads to local concentration polarization. Boundary layer separation is prone to form at the inlet section, and wake vortices are easily generated in the flow channel, which can carry away and hinder water and gas transport, further increasing mass transfer resistance and energy consumption.

[0031] High operating costs: Most existing AEMWEs use catalyst-coated membrane (CCM) type MEAs. When this structure is replaced, the entire membrane and catalyst need to be replaced, resulting in serious catalyst waste and high replacement costs, which restricts the large-scale promotion of the technology.

[0032] Based on this, developing a flow field structure that can alleviate gas blockage and enhance concentration mass transfer at medium and high current densities, and is compatible with low-cost catalyst-coated substrate (CCS) type MEAs, has become a key technological direction for breaking through the bottleneck of large-scale application of AEMWE.

[0033] To address this, this application proposes a gas-liquid separation flow field structure. By setting a main channel and a branch channel on the bipolar plate, the electrolyte can flow rapidly through the main channel and the branch channel, while the electrolyte flows slowly in the reaction zone, promoting the electrolysis reaction of the electrolyte permeating the membrane electrode assembly. The reaction zone produces a large amount of gas, and its two ends are connected to the main channel and the branch channel respectively. Due to the difference in flow velocity, a pressure difference is formed, and the difference in hydrogen concentration forms a concentration difference. The dual driving forces drive the products in the reaction zone to be quickly discharged to the main channel and the branch channel, avoiding gas blockage and dead zones.

[0034] In addition, this application also proposes a hydrogen production device that includes the above-mentioned gas-water separation flow field structure. By using the above-mentioned gas-water separation flow field structure, this hydrogen production device can reduce the occurrence of gas blockage, which is conducive to the efficient discharge of hydrogen products, thereby improving the hydrogen production efficiency.

[0035] Reference Figure 1The gas-water separation flow field structure in the first aspect embodiment of this application includes a bipolar plate 100 and a membrane electrode assembly 200. The bipolar plate 100 includes a cathode-side bipolar plate 110 and an anode-side bipolar plate 120. The membrane electrode assembly 200 transitions from the cathode side to the anode side along its thickness direction. The cathode-side bipolar plate 110 is attached to the cathode side of the membrane electrode assembly 200, and the anode-side bipolar plate 120 is attached to the anode side of the membrane electrode assembly 200. Anions in the cathode-side bipolar plate 110 can pass through the membrane electrode assembly 200 into the anode-side bipolar plate 120, thereby completing the hydrogen production process.

[0036] Specifically, regarding the specific structure of the bipolar plate 100, refer to... Figure 2 The enclosure 130 is set around its edge to create a closed area, within which an inlet 140, an outlet 150, and a diversion structure are provided. The electrolyte flows in through the inlet 140 and out through the outlet 150. The diversion structure guides the electrolyte and induces turbulence, achieving gas-liquid separation and promoting mass transfer. There are two diversion structures arranged symmetrically, with a main channel 170 connecting the inlet 140 and outlet 150 between the two diversion structures, and a branch channel 180 between the diversion structure and the enclosure 130. In this application, the main channel 170 is a straight channel, which allows hydrogen bubbles with a faster flow rate to flow quickly from the inlet 140 to the outlet 150; the branch channel 180 extends along the inner wall of the enclosure 130, which on the one hand extends the flow path of the electrolyte, thereby allowing the electrolyte to be fully electrolyzed, and on the other hand, the electrolyte in the branch channel 180 can continuously flow to the diversion structure to replenish the electrolysis raw materials, and the hydrogen bubbles produced in the diversion structure can also flow to the outlet 150 through the main channel 170 or the branch channel 180.

[0037] The electrolytic reaction mainly occurs within the diversion structure, which includes an inlet diversion plate 161 and multiple baffles 162. The inlet diversion plate 161 diverts the fluid entering at the inlet to the main flow channel 170 and the branch flow channel 180. A reaction zone is formed between two adjacent baffles 162. The two ends of the reaction zone are connected to the main flow channel 170 and the branch flow channel 180, respectively, thereby ensuring fluid communication between the reaction zone and the main flow channel 170 and the branch flow channel 180.

[0038] Reference Figure 3The working principle of the bipolar plate 100 is as follows: After the fluid enters from the inlet 140, it is divided by the inlet diversion plate 161, with part flowing into the main channel 170 and the other part flowing into the branch channel 180. The fluid velocity in the main channel 170 and the branch channel 180 is relatively faster, which can quickly carry away the hydrogen bubbles generated during electrolysis. Due to the obstruction of the baffle 162, the fluid velocity in each reaction zone within the diversion structure is slower. The fluid continuously flows into each reaction zone during the flow process to replenish the raw materials, which is more suitable for electrolysis reaction and forms the main gas production zone. At the same time, there is both a pressure difference caused by the velocity difference between the main channel 170 and the branch channel 180 and the reaction zone, and a concentration difference caused by the hydrogen concentration difference. The dual forces drive the hydrogen bubbles generated in the reaction zone to move towards the main channel 170 or the branch channel 180, thereby completing the separation of hydrogen bubbles and reducing the occurrence of gas blockage and dead zones.

[0039] Furthermore, the membrane electrode assembly 200 specifically includes anion exchange membrane 210, a cathode-side gas diffusion layer 220, and an anode-side gas diffusion layer 230. The anion exchange membrane 210 allows anions to pass through to achieve ion exchange on both sides. The cathode-side gas diffusion layer 220 is attached to the cathode-side bipolar plate 110 for transferring anions, and the anode-side gas diffusion layer 230 is attached to the anode-side bipolar plate 120 for transferring cations.

[0040] Furthermore, the gas-water separation flow field structure also includes a cathode-side end plate 300 and an anode-side end plate 400. The cathode-side end plate 300 is installed on the outside of the cathode-side bipolar plate 110 and protects the cathode-side bipolar plate 110. The anode-side end plate 400 is installed on the outside of the anode-side bipolar plate 120 and protects the anode-side bipolar plate 120.

[0041] Furthermore, along the direction from inlet 140 to outlet 150, the width of the main channel 170 gradually increases to accommodate the amount of hydrogen bubbles that accumulate during the fluid flow, providing sufficient space for gas production; at the same time, it makes it easier for hydrogen bubbles in the hydrogen production zone of the diversion structure to flow into the main channel 170 and flow with the fluid to outlet 150.

[0042] Furthermore, a diversion bend 1611 is provided at one end of the inlet diversion plate 161 near the main flow channel 170. The diversion bend 1611 is bent toward the inlet 140 to facilitate the diversion of the fluid entering from the inlet 140.

[0043] Furthermore, the inflow diversion plate 161 is provided with a plurality of grooves 164 at one end near the branch channel 180. The grooves 164 are used to induce turbulence. On the one hand, they can reduce the flow velocity of the fluid flowing into the branch channel 180. On the other hand, the generation of turbulence can delay the boundary layer separation when the fluid flows around it, reduce the formation of wake and vortex region, promote full flow and mass transfer of fluid, thereby improving the electrolysis sufficiency of electrolyte and improving hydrogen production efficiency.

[0044] Furthermore, the diversion structure also includes an outflow manifold 163, which is located at the confluence of the main flow channel 170 and the branch flow channel 180. It is used to guide the fluid in the branch flow channel 180 to merge with the fluid in the main flow channel 170 and flow together into the outlet 150.

[0045] Furthermore, the outflow manifold 163 is provided with a plurality of grooves 164 at one end near the branch channel 180. The grooves 164 are used to induce turbulence. On the one hand, they can reduce the flow velocity of the fluid discharged from the branch channel 180. On the other hand, the generation of turbulence can delay the boundary layer separation when the fluid flows around it, reduce the formation of wake and vortex region, promote full flow and mass transfer of fluid, thereby improving the electrolysis sufficiency of electrolyte and improving hydrogen production efficiency.

[0046] Furthermore, the end of the baffle 162 is bent toward the outlet 150, thereby reducing the impact of the end of the baffle 162 on the fluid flow in the main channel 170 and the branch channel 180.

[0047] Furthermore, the bipolar plate 100 also includes a baffle plate 190, which is disposed in the branch channel 180 and extends along the branch channel 180. The purpose of the baffle plate 190 is to guide and direct the fluid within the branch channel 180. On the one hand, it can guide the fluid to flow orderly to each reaction zone within the flow distribution structure, allowing the electrolyte to fully penetrate the membrane electrode assembly 200 to participate in the electrolysis reaction; on the other hand, it can optimize the flow field distribution, suppress the formation of wake and vortex regions, ensure the stability of fluid transmission, and thus improve hydrogen production efficiency. The number of baffle plates 190 can be set to multiple to enhance the turbulence effect.

[0048] Furthermore, in this application, the bipolar plate 100 is disc-shaped, with the main flow channel 170 passing through the center of the bipolar plate 100, and the branch flow channel 180 extending circumferentially along the bipolar plate 100. Thus, the enclosure 130 is an arc-shaped curved plate, resulting in less velocity loss when the fluid flows along it.

[0049] A hydrogen production device according to a second aspect embodiment of this application includes the gas-water separation flow field structure described above.

[0050] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application. Furthermore, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other.

Claims

1. A gas-water separation flow field structure, characterized in that, include: A bipolar plate has a perimeter enclosed area, within which an inlet, an outlet, and a diversion structure are provided. Two diversion structures are symmetrically arranged, with a main flow channel connecting the inlet and outlet between the two diversion structures. A branch flow channel is reserved between the diversion structure and the perimeter. Each diversion structure includes an inlet diversion plate and multiple baffles. The inlet diversion plate diverts the fluid entering from the inlet to the main flow channel and the branch flow channel. A reaction zone is formed between two adjacent baffles, with both ends of the reaction zone connected to the main flow channel and the branch flow channel, respectively. A membrane electrode assembly that transitions from the cathode side to the anode side along the thickness direction; The bipolar plate includes a cathode-side bipolar plate and an anode-side bipolar plate. The cathode-side bipolar plate is attached to the cathode side of the membrane electrode assembly, and the anode-side bipolar plate is attached to the anode side of the membrane electrode assembly.

2. The gas-water separation flow field structure according to claim 1, characterized in that: The width of the main channel gradually increases along the direction from the inlet to the outlet.

3. The gas-water separation flow field structure according to claim 1, characterized in that: The inflow diversion plate has a diversion bend at one end near the main flow channel, and the diversion bend bends toward the inlet.

4. The gas-water separation flow field structure according to claim 3, characterized in that: The inflow splitter plate has multiple grooves at one end near the branch channel, and these grooves are used to induce turbulence.

5. The gas-water separation flow field structure according to claim 1, characterized in that: The diversion structure also includes an outflow manifold, which is located at the confluence of the main flow channel and the tributary channel.

6. The gas-water separation flow field structure according to claim 5, characterized in that: The outflow manifold plate has multiple grooves at one end near the branch channel, and these grooves are used to induce turbulence.

7. The gas-water separation flow field structure according to claim 1, characterized in that: The end of the baffle is bent toward the outlet.

8. The gas-water separation flow field structure according to claim 1, characterized in that: The bipolar plate also includes a baffle plate disposed in the branch channel and extending along the branch channel.

9. The gas-water separation flow field structure according to any one of claims 1 to 8, characterized in that: The bipolar plate is disc-shaped, the main flow channel passes through the center of the bipolar plate, and the branch flow channels extend circumferentially along the bipolar plate.

10. A hydrogen production device, characterized in that, Includes the gas-water separation flow field structure described in any one of claims 1 to 9.

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