Non-uniform double-channel snake-shaped flow channel structure in water electrolysis tank

Abstract

The invention discloses a flow channel structure in a water electrolysis tank, and particularly relates to a non-uniform double-channel snake-shaped flow channel structure in the water electrolysis tank, which comprises a snake-shaped flow channel I and a snake-shaped flow channel II formed on a bipolar plate of the water electrolysis tank, the snake-shaped flow channel I and the snake-shaped flow channel II are arranged in parallel in the same direction and the same phase, and the snake-shaped flow channel I and the snake-shaped flow channel II are arranged in parallel in the same direction. The cross section areas of the two are different; the first snake-shaped flow channel and the second snake-shaped flow channel are of a nested structure. According to the invention, the technical problem of realizing gas-liquid split-path transportation in the water electrolysis tank is solved. According to the water electrolysis cell with the non-uniform double-channel snake-shaped flow channel structure, gas and liquid in the water electrolysis cell are guided to be transported in different diameters through the differential pressure flow channel in the operation process, so that gas and liquid transportation is not hindered, the transportation efficiency is improved, and the electrochemical performance of the water electrolysis cell is further improved. The method has very important scientific significance and application value for step-type development of AWE and PEM water electrolysis hydrogen production technologies.

Description

Technical Field

[0001] The present invention relates to a flow channel structure in a water electrolysis cell, in particular to a non-uniform double-channel serpentine flow channel structure in a water electrolysis cell. Background Art

[0002] Currently, the commercially advanced AWE and PEM water electrolysis hydrogen production technologies both use a water electrolysis cell as the core component of the system. The water electrolysis cell, which includes a proton exchange membrane and cathode and anode catalyst layers, is the place where the water electrolysis reaction occurs; adjacent to it is the liquid / gas diffusion layer, also known as the porous transport layer, mostly a porous medium, whose function is to transport reactants and products; and, the bipolar plate, which can fix the electrolytic cell components and guide the current transfer. Flow channels are usually processed on the bipolar plate, and their function is to uniformly transport water into the cathode and anode catalyst layers and discharge the gas. The above water electrolysis cells (water electrolysis units) are stacked and assembled into a stack system, which can integrate high-power water electrolyzers, and then form a large-scale hydrogen production device.

[0003] Parallel, cross-type, and serpentine flow channels are common flow channel structures in water electrolyzers. These flow channels can uniformly infiltrate the water flowing in from the electrolyzer inlet into the porous medium, and finally transport it to the catalyst layer for the electrolysis reaction to occur. In addition, the gas generated after water electrolysis will also detach from the catalyst layer and the diffusion layer, enter the flow channel, and flow out of the water electrolyzer together with the liquid water.

[0004] The existing flow channel structures applied in water electrolyzers, although they can achieve the transport of water and gas, still have technical defects. Since the transport path of water is to infiltrate from the flow channel into the porous diffusion layer and finally reach the catalyst layer, while the transport path of gas is to transfer from the catalyst layer to the diffusion layer and finally reach the flow channel. Therefore, during the transport of water and gas, there must be a situation where they hinder each other's transport, and the occurrence of this situation is neither conducive to the supply of water nor the discharge of gas. And the existing flow channels cannot solve the above technical pain points.

[0005] Therefore, the applicant proposes the present invention. Summary of the Invention

[0006] The purpose of the present invention is to provide a non-uniform double-channel serpentine flow channel structure that realizes gas-liquid separate-path transport in a water electrolysis cell to solve the above-mentioned deficiencies of the prior art.

[0007] To achieve the above purpose, a non-uniform double-channel serpentine flow channel structure in a water electrolysis cell designed by the present invention includes: A serpentine flow channel one and a serpentine flow channel two formed on the bipolar plate of the water electrolysis cell. The serpentine flow channel one and the serpentine flow channel two are arranged in parallel with the same direction and the same phase, and the cross-sectional areas of the two are different.

[0008] The present invention proposes a differential pressure flow channel structure design, specifically: Since the cross-sections of adjacent flow channels are different, when the same flow rate of water is introduced, a flow velocity difference is generated between adjacent flow channels, which in turn causes a pressure difference. The different densities and viscosities of gas and liquid fluids cause the gas to preferentially flow to the low-pressure area and the liquid to remain in the high-pressure area, realizing the separate-path transportation of gas and liquid. The density difference between gas and liquid further strengthens the pressure difference between the flow channels, promoting further separation of gas and liquid.

[0009] Furthermore, in the above non-uniform double-channel serpentine flow channel structure in a water electrolysis cell, in its preferred structure, serpentine flow channel 1 and serpentine flow channel 2 are in a nested structure with each other.

[0010] The layout of the above non-uniform double-channel serpentine flow channel structure design is more reasonable and compact.

[0011] Compared with the prior art, the non-uniform double-channel serpentine flow channel structure in a water electrolysis cell obtained by the present invention has the following technical effects: In combination with the water electrolysis cell with the non-uniform double-channel serpentine flow channel structure of the present invention, during operation, the differential pressure flow channel guides the separate-path transportation of gas and liquid in the water electrolysis cell, so that the gas and liquid transportation do not hinder each other, improving the transportation efficiency, and further enhancing the electrochemical performance of the water electrolysis cell. The present invention has very important scientific significance and application value for the step-by-step development of AWE and PEM water electrolysis hydrogen production technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a schematic diagram of a non-uniform double-channel serpentine flow channel structure in a water electrolysis cell; Figure 2 is a cloud map of the gas volume fraction distribution in the flow channel; Figure 3 is the polarization curve of the water electrolysis cell.

[0013] In the figure: bipolar plate 1, serpentine flow channel 1 2-1, serpentine flow channel 2 2-2. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present invention.

[0015] As Figure 1 shown, as an implementation manner of the present invention, the non-uniform double-channel serpentine flow channel structure provided in this embodiment includes: The serpentine flow channel one 2-1 and the serpentine flow channel two 2-2 formed on the bipolar plate 1 of the water electrolysis cell. The serpentine flow channel one 2-1 and the serpentine flow channel two 2-2 are arranged in parallel with the same direction and the same phase, that is, arranged in parallel, and the cross-sectional areas of the two are different. During the operation of the water electrolysis cell, the same flow rate of water is introduced into the two serpentine flow channels respectively. However, due to the different cross-sectional areas, there is a velocity difference, which further brings a pressure difference. Eventually, water mainly accumulates in the serpentine channel two 2-2 with a larger cross-section, and gas accumulates in the serpentine channel one 2-1 with a smaller cross-section, forming a separate-path transportation of water and gas.

[0016] At the same time, in order to make the layout of the non-uniform double-channel serpentine flow channel structure provided in this embodiment more reasonable and compact, the serpentine flow channel one 2-1 and the serpentine flow channel two 2-2 in its structure are in a nested structure with each other.

[0017] The following verifies the gas volume fraction distribution index in the gas-liquid transportation of the flow channel design of the present invention through a simulation experiment. The specific simulation experiment process is as follows: Carry out a simulation study in the Comsol Multiphysics software. First, establish a geometric model including a catalytic layer, a diffusion layer, a flow channel, and a bipolar plate. Subsequently, use the free and porous media flow module and the level set module in the software, and couple the two to establish a gas-liquid two-phase flow model in the PEM water electrolysis cell. Then, set the relevant gas and liquid properties, relevant boundary conditions, and initial values (as shown in Table 1), and conduct a gas-liquid two-phase flow simulation under a certain gas flow rate and water flow rate. Finally, on the basis of the above two-phase flow model, add a water electrolysis cell module, and set the corresponding boundary conditions and initial values (as shown in Table 1) to conduct an electrochemical simulation.

[0018] Table 1 Setting of relevant parameters during the simulation Parameter Expression Unit Water, dynamic viscosity 0.000357 [Pa*s] Hydrogen, dynamic viscosity 8.92E-06 [Pa*s] Oxygen, dynamic viscosity 2.27E-05 [Pa*s] Water, density 1000 [kg / m^3] Hydrogen, density 0.08375 [kg / m^3] Oxygen, density 1 [kg / m^3] Diffusion layer, porosity 0.75 Diffusion layer, permeability 1E-10 [m^2] Reaction layer, porosity 0.3 Reaction layer, permeability 1E-10 [m^2] Water flow rate 60 [ml / min] Operating pressure, atmospheric pressure 101325 [Pa] Flow channel, initialization parameter, multiphase flow parameter 0.1 Diffusion layer, initialization parameter, multiphase flow parameter 0.1 Reaction layer, initialization parameter, multiphase flow parameter 0.1 Flow channel, interface thickness, multiphase flow parameter 0.00015 [m] Diffusion layer, interface thickness, multiphase flow parameter 0.00015 [m] Catalytic layer, interface thickness, multiphase flow parameter 0.00015 [m] Membrane porosity 0.3 Current collector plate conductivity 1000 [S / m] Diffusion layer conductivity 50 [S / m] Electrolyte conductivity 10 [S / m] Catalytic layer conductivity 1000 [S / m] Applied current density 0.5 [A / cm^2] Exchange current density, hydrogen oxidation 50 [A / m^2] Exchange current density, oxygen reduction 0.5 [A / m^2] Molar volume, hydrogen 22.414 [L / mol] Molar volume, water 18.07 [L / mol] Molar volume, oxygen 22.414 [L / mol] Catalytic layer, specific surface area 1E+09 [1 / m] Diffusion layer, fiber diameter 50 [um] The results of the simulation experiment are as follows: Instruction manual appendix Figure 2 Shows the gas volume fraction distribution cloud map obtained by simulation in the flow channel. As shown in the figure, in the flow channel, the gas volume fraction of the serpentine flow channel one 2-1 part is relatively high, while the gas volume fraction of the serpentine flow channel two 2-2 part is basically 0 (which means that the fluid in it is mainly liquid water), realizing the separate-path transportation of gas and water in the flow channel.

[0019] Instruction manual appendix Figure 3 Shows the polarization curves of the water electrolysis cells obtained by using the traditional serpentine flow channel structure and the flow channel structure designed in this patent respectively. As shown in the figure, when the same voltage is applied, the water electrolysis cell with the flow channel structure designed in this patent has a higher current density.

[0020] The above simulation results have shown that the flow channel design of the present invention can indeed promote the separate transportation of gas and liquid and improve the electrochemical performance of the water electrolyzer.

[0021] The present invention is not limited to the above best implementation manner. Anyone can obtain other various forms of products under the inspiration of the present invention. However, no matter what changes are made in its shape or structure, as long as it has the same or similar technical solutions as the present application, it falls within the protection scope of the present invention.

Claims

1. A non-uniform dual-channel serpentine flow channel structure in a water electrolysis cell, characterized in that Comprising: A serpentine flow channel one and a serpentine flow channel two formed on the bipolar plate of the water electrolysis cell, the serpentine flow channel one and the serpentine flow channel two are arranged in parallel with the same direction and the same phase, and the cross-sectional areas of the two are different.

2. The non-uniform double-channel serpentine flow channel structure in a water electrolysis cell according to claim 1, characterized in that: The serpentine flow channel one and the serpentine flow channel two are in a nested structure with each other.

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