Method for simulating and researching uniformity of flow field in electrolytic cell

Abstract

The invention belongs to the technical field of hydrogen production through water electrolysis, and particularly relates to a method for simulating and researching uniformity of a flow field in an electrolytic bath, which comprises the following steps: introducing water with rated flow into an inlet and outlet end plate; after the bubbles are completely discharged and the water flow is stable, adding a coloring agent into a water source, and recording the diffusion process of colored water flowing from an inlet to an outlet in each flow channel; introducing a hydrogen peroxide solution with a certain concentration into the inlet and outlet end plate; when the hydrogen peroxide solution flows in the runner, the hydrogen peroxide solution is in contact with manganese dioxide dispersed in the catalyst carbon paper to be decomposed, oxygen is separated out on the surface of the carbon paper, and the condition that oxygen is separated out from GDL during electrolysis operation is simulated; after flowing is stable, a coloring agent is added through an inlet connector, and the process that the colored water-gas two-phase flow in each flow channel flows from an inlet to an outlet is recorded. According to the invention, the process of separating oxygen from GDL can be simulated without using a proton exchange membrane and electrifying, and the real condition in the electrolytic cell is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of PEM water electrolysis hydrogen production, and particularly relates to a method for simulating and studying flow field uniformity in an electrolytic cell. Background Art

[0002] Currently, the primary method for studying water-gas two-phase flow within the electrolysis chamber of a PEM electrolyzer is through CFD simulation. However, simulations cannot accurately model the multi-layered mesh structure of the anode, leading to discrepancies between the results obtained when analyzing flow field uniformity and the actual situation. Conventional transparent visualization tools cannot simulate the process of oxygen precipitation from the GDL surface and can only study the uniformity of a single liquid phase flow. Summary of the Invention

[0003] The present invention aims to overcome the shortcomings of the prior art by providing a method for simulating and studying the uniformity of the flow field within an electrolytic cell. The method is performed in a visualization tool. It can simulate the process of oxygen evolution from the GDL without using a proton exchange membrane or applying electricity, recreating the actual conditions within the electrolytic cell and visually demonstrating the uniformity of the two-phase flow field. Furthermore, it can be used to observe whether oxygen evolved from the reaction when using a multilayer titanium mesh as the anode diffusion layer becomes trapped within the mesh, forming a gas block.

[0004] To achieve the above technical objectives, the technical solution adopted in the embodiment of the present invention is: A method for simulating the uniformity of the flow field in an electrolyzer is provided. The method uses hydrogen peroxide decomposition in a two-phase flow field visualization research tool in the electrolysis chamber of a PEM electrolyzer to simulate the process of oxygen evolution from the GDL, including the following steps: Step S1: introducing water of rated flow into the inlet and outlet end plates through the inlet joints; Step S2: After all bubbles have been eliminated and the water flow has stabilized, a dye is added to the water source. A high-speed camera is used to record the diffusion process of the colored water from the inlet to the outlet in each flow channel, and to observe whether there is any difference in the flow rate of each flow channel; Step S3: introducing a hydrogen peroxide solution of a certain concentration into the inlet and outlet end plates through the inlet joints; Step S4: When the hydrogen peroxide solution flows in the flow channel, it contacts the manganese dioxide dispersed in the catalyst carbon paper and decomposes, releasing oxygen on the surface of the carbon paper, simulating the release of oxygen from the GDL during electrolysis operation; Step S5: After the flow stabilizes, dye is added through the inlet joint, and a high-speed camera is used to record the process of the colored water-gas two-phase flow in each flow channel from the inlet to the outlet to observe whether there is a difference in the flow rate of each flow channel.

[0005] Furthermore, in step S3, hydrogen peroxide solutions of different concentrations are used to simulate gas production rates under different electrical densities. The concentration of the hydrogen peroxide solution is c(H2O2) = n(H2O2) ÷ Q = (A×S) / (2×F×Q), mol / mL; where n(H2O2) is the molar amount of hydrogen peroxide H2O2 reacted per second, mol / s, and n(H2O2) = n(O2) × 2. n(O2) is the molar amount of oxygen produced per second by the decomposition of hydrogen peroxide H2O2 in a single electrolytic cell, n(O2) = (A×S) / (4×F), where S is the simulated active area, cm 2 ; A is the current density, A / cm 2 ; Q is the flow rate, mL / s; F is the Faraday constant.

[0006] Furthermore, the two-phase flow field visualization tooling in the electrolysis chamber of the PEM electrolyzer includes an inlet and outlet end plate, a blind end plate, and a flow field plate and catalyst carbon paper located therebetween, wherein the inlet and outlet end plates are provided with an inlet connector and an outlet connector; The flow field plate is provided with a distribution area, a flow channel groove and a common flow channel, the flow channel groove is provided near the blind end plate, the distribution area is provided between the flow channel groove and the common flow channel, a drainage groove is provided between the common flow channel and the distribution area, the drainage groove is covered with a flow channel cover plate, and the flow channel cover plate and the drainage groove together constitute an inner flow channel leading from the common flow channel to the distribution area; Manganese dioxide is uniformly dispersed in the catalyst carbon paper; and the inlet and outlet end plates and the flow field plates are made of transparent materials.

[0007] Furthermore, sealing strips are provided between the flow field plate and the inlet and outlet end plates, and between the flow field plate and the blind end plate. The outline of the sealing strips envelops the common flow channel and the periphery of the entire flow field plate.

[0008] Furthermore, bolts and nuts are provided on the inlet and outlet end plates for clamping and fixing the inlet and outlet end plates, blind end plates, flow field plates, flow channel cover plates, catalyst carbon paper and sealing strips, and the catalyst carbon paper is provided between the blind end plates and the flow field plates.

[0009] Furthermore, the two-phase flow field visualization tooling in the electrolysis chamber of the PEM electrolyzer includes an inlet and outlet end plate, a blind end plate, and an electrode frame, a flow channel cover plate and catalyst carbon paper located therebetween. The inlet and outlet end plates are provided with an inlet connector and an outlet connector. The pole frame is provided with a flow channel groove, and the flow channel groove is covered with a flow channel cover plate. The flow channel cover plate and the flow channel groove together constitute an inner flow channel leading from the common flow channel to the multi-layer titanium mesh. The multi-layer titanium mesh is embedded in the reaction area in the center of the pole frame; Manganese dioxide is evenly dispersed in the catalyst carbon paper; and the inlet and outlet end plates are made of transparent material.

[0010] Furthermore, the inlet joint and the outlet joint are arranged on the inlet and outlet end plates at positions corresponding to the flow channels.

[0011] Furthermore, sealing strips are provided between the pole frame and the inlet and outlet end plates, and between the pole frame and the blind end plate. The outline of the sealing strips envelops the common flow channel and the periphery of the entire pole frame.

[0012] Furthermore, bolts and nuts are provided on the inlet and outlet end plates for clamping and fixing the inlet and outlet end plates, blind end plates, pole frames, flow channel cover plates, catalyst carbon paper, multilayer titanium mesh and sealing strips, and the catalyst carbon paper is provided between the blind end plates and the multilayer titanium mesh.

[0013] The technical solution provided by the embodiment of the present invention has the following beneficial effects: 1. The present invention utilizes a chemical reaction to produce a two-phase flow by contacting hydrogen peroxide with manganese dioxide to decompose the manganese dioxide, and can simulate the process of oxygen precipitation from the GDL in the electrolytic cell without using a proton exchange membrane or applying electricity.

[0014] 2. The present invention uses transparent tooling, flow field plates, and water with dye in conjunction with a high-speed camera to record the flow velocity of each flow channel, intuitively displaying the uniformity of the flow field. It can also be observed whether the oxygen released by the reaction when using a multi-layer titanium mesh as the anode diffusion layer will be trapped in the mesh to form an air blockage. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is an appearance diagram of the tooling for visualizing the two-phase flow field in the electrolysis chamber of the PEM electrolyzer in Example 1 of the present invention.

[0016] Figure 2 yes Figure 1 Exploded view of the tooling for visualizing the two-phase flow field in the electrolysis chamber of a PEM electrolyzer.

[0017] Figure 3 yes Figure 1 Schematic diagram of the structure of the mid-flow field plate.

[0018] Figure 4 yes Figure 1 Schematic diagram of the internal structure of the tooling for visualizing the two-phase flow field in the electrolysis chamber of a PEM electrolyzer.

[0019] Figure 5 yes Figure 1 Layout diagram of the sealing strip.

[0020] Figure 6 yes Figure 1Schematic diagram of the setting position structure of the first catalyst carbon paper.

[0021] Figure 7 This is an appearance diagram of the two-phase flow field visualization research tooling in the electrolysis chamber of the PEM electrolyzer in Example 2.

[0022] Figure 8 yes Figure 7 Exploded view of the tooling for visualizing the two-phase flow field in the electrolysis chamber of a PEM electrolyzer.

[0023] Figure 9 yes Figure 7 Schematic diagram of the structure of the middle pole frame.

[0024] Figure 10 yes Figure 7 Cross-sectional view of the tooling for visualizing the two-phase flow field in the electrolysis chamber of a PEM electrolyzer.

[0025] Explanation of reference numerals: 1a - first inlet and outlet end plates; 2a - first blind end plate; 3a - flow field plate; 4a - first flow channel cover plate; 5a - first catalyst carbon paper; 6a - sealing strip; 7a - first inlet joint; 8a - first outlet joint; 9 - bolt; 10 - nut assembly; 3.1a - distribution area; 3.2a - first flow channel groove; 3.3a - first common flow channel; 3.4a - drainage groove; 3.5a - first inner flow channel; 1b - second inlet and outlet end plates; 2b - second blind end plate; 3b - pole frame; 4b - second flow channel cover plate; 5b - second catalyst carbon paper; 6b - sealing ring; 7b - multi-layer titanium mesh; 8b - second inlet connector; 9b - second outlet connector; 3.1b-second flow channel groove; 3.2b-second common flow channel; 3.3b-reaction zone; 3.4b-second inner flow channel. DETAILED DESCRIPTION

[0026] In the description of the present invention, it should be understood that the directions or positional relationships indicated by directional words such as "inside, outside", "up, down", "left, right", etc. are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention.

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0028] Example 1 like Figure 1-6 As shown, a tool for visualizing the two-phase flow field in the electrolysis chamber of a PEM electrolyzer comprises a first inlet and outlet end plate 1a, a first blind end plate 2a, a flow field plate 3a and a first catalyst carbon paper 5a located therebetween, and a first inlet connector 7a and a first outlet connector 8a are provided on the first inlet and outlet end plate 1a. The flow field plate 3a is provided with a distribution area 3.1a, a first flow channel groove 3.2a, and a first common flow channel 3.3a. The first flow channel groove 3.2a is located near the first blind end plate 2a. The distribution area 3.1a is located between the first flow channel groove 3.2a and the first common flow channel 3.3a. A drainage groove 3.4a is provided between the first common flow channel 3.3a and the distribution area 3.1a. The drainage groove 3.4a is covered with a first flow channel cover plate 4. The first flow channel cover plate 4 and the drainage groove 3.4a together form a first inner flow channel 3.5a leading from the first common flow channel 3.3a to the distribution area 3.1a. Manganese dioxide is uniformly dispersed in the first catalyst carbon paper 5a; the first inlet and outlet end plates 1a and the flow field plate 3a are made of transparent materials.

[0029] Sealing strips 6a are provided between the flow field plate 3a and the first inlet and outlet end plate 1a, and between the flow field plate 3a and the first blind end plate 2a. The outline of the sealing strips 6a envelops the first common flow channel 3.3a and the periphery of the entire flow field plate 3a.

[0030] Bolts 9 and nuts 10 are provided on the first inlet and outlet end plates 1a, which are used to clamp and fix the first inlet and outlet end plates 1a, the first blind end plate 2a, the flow field plate 3a, the first flow channel cover plate 4, the first catalyst carbon paper 5a and the sealing strip 6a. The first catalyst carbon paper 5a is arranged between the first blind end plate 2a and the flow field plate 3a.

[0031] A method for simulating and studying the uniformity of the flow field in an electrolytic cell, wherein the process of oxygen evolution from the GDL is simulated by decomposing hydrogen peroxide in the two-phase flow field visualization research tool in the electrolytic cell of the PEM electrolytic cell, comprising the following steps: Step S1: Introduce water of rated flow into the first inlet and outlet end plate 1a through the first inlet joint 7a; Step S2: After all bubbles have been eliminated and the water flow has stabilized, a dye is added to the water source. A high-speed camera is used to record the diffusion process of the colored water from the inlet to the outlet in each flow channel, and to observe whether there is any difference in the flow rate of each flow channel; Step S3: introducing a hydrogen peroxide solution of a certain concentration into the first inlet and outlet end plate 1a through the first inlet joint 7a; Step S4: When the hydrogen peroxide solution flows in the flow channel, it contacts the manganese dioxide dispersed in the first catalyst carbon paper 5a and decomposes it, releasing oxygen on the surface of the carbon paper, simulating the release of oxygen from the GDL during electrolysis operation. Step S5: After the flow stabilizes, dye is added through the first inlet connector 7a, and a high-speed camera is used to record the process of the colored water-gas two-phase flow in each flow channel from the inlet to the outlet to observe whether there is any difference in the flow rate of each flow channel.

[0032] In step S3, hydrogen peroxide solutions of different concentrations are used to simulate gas production rates under different electrical densities. The concentration of hydrogen peroxide solution is c(H2O2) = n(H2O2) ÷ Q = (A×S) / (2×F×Q), mol / mL; where n(H2O2) is the molar amount of hydrogen peroxide H2O2 reacted per second, mol / s, and n(H2O2) = n(O2) × 2. n(O2) is the molar amount of oxygen produced per second by the decomposition of hydrogen peroxide H2O2 in a single electrolytic cell, n(O2) = (A×S) / (4×F), where S is the simulated active area, cm 2 ; A is the current density, A / cm 2 ; Q is the flow rate, mL / s; F is the Faraday constant.

[0033] Example 2 like Figure 7-10 As shown, a two-phase flow field visualization tooling in an electrolysis chamber of a PEM electrolyzer includes a second inlet and outlet end plate 1b, a second blind end plate 2b, and a pole frame 3b located therebetween, a second flow channel cover plate 4b, and a second catalyst carbon paper 5b. The second inlet and outlet end plate 1b is provided with a second inlet connector 8b and a second outlet connector 9b. A second flow channel groove 3.1b is provided on the pole frame 3b, and a second flow channel cover plate 4b covers the second flow channel groove 3.1b. The second flow channel cover plate 4b and the second flow channel groove 3.1b together form a second inner flow channel 3.4b extending from the second common flow channel 3.2b to the multilayer titanium mesh 7b. The multilayer titanium mesh 7b is embedded in the reaction area 3.3b at the center of the pole frame 3b. Manganese dioxide is evenly dispersed in the second catalyst carbon paper 5b; the second inlet and outlet end plates 1b are made of transparent material.

[0034] The second inlet joint 8b and the second outlet joint 9b are arranged at positions corresponding to the flow channels on the second inlet and outlet end plate 1b.

[0035] Sealing rings 6b are provided between the pole frame 3b and the second inlet and outlet end plate 1b, and between the pole frame 3b and the second blind end plate 2b. The outline of the sealing ring 6b envelops the second common flow channel 3.2b and the periphery of the entire pole frame 3b.

[0036] Bolts 9 and nuts 10 are provided on the second inlet and outlet end plate 1b, which are used to clamp and fix the second inlet and outlet end plate 1b, the second blind end plate 2b, the pole frame 3b, the second flow channel cover plate 4b, the second catalyst carbon paper 5b, the multilayer titanium mesh 7b and the sealing ring 6b. The second catalyst carbon paper 5b is arranged between the second blind end plate 2b and the multilayer titanium mesh 7b.

[0037] A method for simulating and studying the uniformity of the flow field in an electrolytic cell, wherein the process of oxygen evolution from the GDL is simulated by decomposing hydrogen peroxide in the two-phase flow field visualization research tool in the electrolytic cell of the PEM electrolytic cell, comprising the following steps: Step S1: Introduce water of rated flow into the second inlet and outlet end plate 1a through the second inlet joint 8b; Step S2: After all bubbles have been eliminated and the water flow has stabilized, a dye is added to the water source. A high-speed camera is used to record the diffusion process of the colored water from the inlet to the outlet in each flow channel, and to observe whether there is any difference in the flow rate of each flow channel; Step S3: introducing a hydrogen peroxide solution of a certain concentration into the second inlet and outlet end plate 1a through the second inlet joint 8b; Step S4: When the hydrogen peroxide solution flows in the flow channel, it contacts the manganese dioxide dispersed in the second catalyst carbon paper 5b and decomposes, releasing oxygen on the surface of the carbon paper, simulating the release of oxygen from the GDL during electrolysis operation; Step S5: After the flow stabilizes, dye is added through the second inlet connector 8b, and a high-speed camera is used to record the process of the colored water-gas two-phase flow in each flow channel flowing from the inlet to the outlet to observe whether there is any difference in the flow rate of each flow channel.

[0038] In step S3, hydrogen peroxide solutions of different concentrations are used to simulate gas production rates under different electrical densities. The concentration of hydrogen peroxide solution is c(H2O2) = n(H2O2) ÷ Q = (A×S) / (2×F×Q), mol / mL; where n(H2O2) is the molar amount of hydrogen peroxide H2O2 reacted per second, mol / s, and n(H2O2) = n(O2) × 2. n(O2) is the molar amount of oxygen produced per second by the decomposition of hydrogen peroxide H2O2 in a single electrolytic cell, n(O2) = (A×S) / (4×F), where S is the simulated active area, cm 2 ; A is the current density, A / cm 2 ; Q is the flow rate, mL / s; F is the Faraday constant.

[0039] The first catalyst carbon paper 5a in Example 1 and the second catalyst carbon paper 5b in Example 2 were prepared by the following method, including the following steps: (1) Soak the carbon paper in KMnO4 solution for a period of time and then take it out to dry; (2) heating the dried carbon paper to decompose potassium permanganate into MnO2, and MnO2 is evenly dispersed on the carbon paper; (3) Use clean water to wash away K2MnO4, another decomposition product of potassium permanganate, so that only MnO2 remains in the carbon paper.

[0040] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for simulating and studying the uniformity of the flow field in an electrolytic cell, characterized in that: The process of oxygen evolution from the GDL is simulated by decomposing hydrogen peroxide in the two-phase flow field visualization research tool in the electrolysis chamber of the PEM electrolyzer, including the following steps: Step S1: introducing water of rated flow into the inlet and outlet end plates through the inlet joints; Step S2: After all bubbles have been eliminated and the water flow has stabilized, a dye is added to the water source. A high-speed camera is used to record the diffusion process of the colored water from the inlet to the outlet in each flow channel, and to observe whether there is any difference in the flow rate of each flow channel; Step S3: introducing a hydrogen peroxide solution of a certain concentration into the inlet and outlet end plates through the inlet joints; Step S4: When the hydrogen peroxide solution flows in the flow channel, it contacts the manganese dioxide dispersed in the catalyst carbon paper and decomposes, releasing oxygen on the surface of the carbon paper, simulating the release of oxygen from the GDL during electrolysis operation; Step S5: After the flow stabilizes, dye is added through the inlet joint, and a high-speed camera is used to record the process of the colored water-gas two-phase flow in each flow channel from the inlet to the outlet to observe whether there is a difference in the flow rate of each flow channel.

2. The method for simulating and studying the uniformity of the flow field in the electrolytic cell according to claim 1, characterized in that: In step S3, hydrogen peroxide solutions of different concentrations are used to simulate gas production rates under different electrical densities. The concentration of the hydrogen peroxide solution is c(H2O2) = n(H2O2) ÷ Q = (A×S) / (2×F×Q), mol / mL; where n(H2O2) is the molar amount of hydrogen peroxide H2O2 reacted per second, mol / s, and n(H2O2) = n(O2) × 2. n(O2) is the molar amount of oxygen produced per second by the decomposition of hydrogen peroxide H2O2 in a single electrolytic cell, n(O2) = (A×S) / (4×F), where S is the simulated active area, cm 2 ; A is the current density, A / cm 2 ; Q is the flow rate, mL / s; F is the Faraday constant.

3. The method for simulating and studying the uniformity of the flow field in the electrolytic cell according to claim 1, characterized in that: The two-phase flow field visualization tooling in the electrolysis chamber of the PEM electrolyzer includes an inlet and outlet end plate, a blind end plate, and a flow field plate and catalyst carbon paper located therebetween. The inlet and outlet end plates are provided with an inlet connector and an outlet connector. The flow field plate is provided with a distribution area, a flow channel groove and a common flow channel, the flow channel groove is provided near the blind end plate, the distribution area is provided between the flow channel groove and the common flow channel, a drainage groove is provided between the common flow channel and the distribution area, the drainage groove is covered with a flow channel cover plate, and the flow channel cover plate and the drainage groove together constitute an inner flow channel leading from the common flow channel to the distribution area; Manganese dioxide is uniformly dispersed in the catalyst carbon paper; and the inlet and outlet end plates and the flow field plates are made of transparent materials.

4. The method for simulating and studying the uniformity of the flow field in the electrolytic cell according to claim 3, characterized in that: Sealing strips are provided between the flow field plate and the inlet and outlet end plates, and between the flow field plate and the blind end plate. The outline of the sealing strips envelops the common flow channel and the periphery of the entire flow field plate.

5. The method for simulating and studying the uniformity of the flow field in the electrolytic cell according to claim 3, characterized in that: Bolts and nuts are provided on the inlet and outlet end plates for clamping and fixing the inlet and outlet end plates, blind end plates, flow field plates, flow channel cover plates, catalyst carbon paper and sealing strips. The catalyst carbon paper is provided between the blind end plates and the flow field plates.

6. The method for simulating and studying the uniformity of the flow field in the electrolytic cell according to claim 1, characterized in that: The two-phase flow field visualization tooling in the electrolysis chamber of the PEM electrolyzer comprises an inlet and outlet end plate, a blind end plate, and a pole frame, a flow channel cover plate and catalyst carbon paper located therebetween. The inlet and outlet end plates are provided with an inlet joint and an outlet joint. The pole frame is provided with a flow channel groove, and the flow channel groove is covered with a flow channel cover plate. The flow channel cover plate and the flow channel groove together constitute an inner flow channel leading from the common flow channel to the multi-layer titanium mesh. The multi-layer titanium mesh is embedded in the reaction area in the center of the pole frame; Manganese dioxide is evenly dispersed in the catalyst carbon paper; and the inlet and outlet end plates are made of transparent material.

7. The method for simulating and studying the uniformity of the flow field in an electrolytic cell according to claim 3 or 6, characterized in that: The inlet joint and the outlet joint are arranged on the inlet and outlet end plates at positions corresponding to the flow channels.

8. The method for simulating and studying the uniformity of the flow field in the electrolytic cell according to claim 6, characterized in that: Sealing strips are provided between the pole frame and the inlet and outlet end plates, and between the pole frame and the blind end plate. The outline of the sealing strips envelops the common flow channel and the periphery of the entire pole frame.

9. The method for simulating and studying the uniformity of the flow field in the electrolytic cell according to claim 6, characterized in that: Bolts and nuts are provided on the inlet and outlet end plates for clamping and fixing the inlet and outlet end plates, blind end plates, pole frames, flow channel cover plates, catalyst carbon paper, multi-layer titanium mesh and sealing strips. The catalyst carbon paper is provided between the blind end plates and the multi-layer titanium mesh.

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