Efficient turbulent flow defoaming flow field structure for electrolyzed water

Abstract

The utility model discloses an efficient turbulent flow defoaming flow field structure for electrolyzed water. The efficient turbulent flow defoaming flow field structure comprises a rectangular wave flow field and periodically repeated trapezoidal flow channel grooves formed in a rectangular convex ridge. The width of the trapezoidal runner groove is similar to that of the rectangular convex ridge, the trapezoidal runner groove is adjacent to the two trapezoidal convex ridges left and right, and the trapezoidal runner groove is communicated with the two parallel transverse straight runners up and down. And the trapezoidal grooves on the rectangular convex ridge on the same step surface and the trapezoidal grooves on the adjacent step surface are distributed in parallel at equal intervals or non-equal intervals. The flow field increases the contact area of the electrolyte and the polar plate in the electrolytic bath, reduces the resistance and improves the flow guide effect of the flow field. Meanwhile, the ordered trapezoidal flow field structure has a strong turbulent flow effect on gas-liquid two-phase flow in the polar plate of the electrolytic cell, so that a rapid bubble removal effect is generated in the electrolysis process, accumulation of bubbles in liquid in a flow channel is reduced, the situation that the bubbles are accumulated in the flow channel to form large bubbles is avoided, and the electrolysis efficiency of an active reaction area and water is improved.

Description

Technical Field

[0001] The present application belongs to the field of hydrogen production by water electrolysis, and specifically relates to a highly efficient turbulent and degassing flow field structure for water electrolysis. Background Art

[0002] Hydrogen production by water electrolysis is easy to apply on a large scale, and the hydrogen production process is pollution-free. Combined with renewable energy, it can achieve zero emissions. Water electrolysis hydrogen production technology is mainly divided into alkaline electrolysis cells, solid oxide electrolysis cells, proton exchange membrane water electrolysis, etc. At present, large-scale water electrolysis hydrogen production technology mainly adopts alkaline water electrolysis hydrogen production technology and proton exchange membrane electrolysis hydrogen production technology.

[0003] The water electrolysis process is the process of decomposing water into hydrogen and oxygen under the action of electrode potential difference. In this process, external input electrical energy is converted into chemical energy and stored in hydrogen and oxygen. In the electrochemical reaction process with gas phase formation, the appearance of bubbles has an important influence on the entire electrochemical reaction process. On the one hand, the bubbles undergo nucleation growth and detachment processes on the electrode surface. The buoyancy has a significant effect on the detachment of large bubbles. When the buoyancy is greater than the adhesion force, the bubbles detach from the electrode surface. On the other hand, in a high concentration electrolyte, due to the small conductivity ratio between the gas and liquid phases, the gas phase causes the overall conductivity of the electrolyte to decrease.

[0004] The flow field structure is an important part of the electrolyzer, because the arrangement of the flow channel directly affects the uniform distribution of the reactants and the effective transportation of the gas. The ideal flow field structure has the following characteristics: effective mass transfer from the reactants to the catalyst layer, discharge of the reaction products from the flow channel to the outside of the flow channel, low pressure drop and effective thermal management. At present, the more commonly used flow field structures are parallel flow field, serpentine flow field, point flow field and cross-finger flow field. The parallel flow field will cause uneven distribution of the fluid in the entire flow field due to its small pressure drop and more branch flow channels, causing bubble accumulation in some areas, affecting the efficiency of the electrolyzer; the advantage of the serpentine flow field is that the fluid is evenly distributed, but for the plates with larger areas, the flow field pressure drop is larger; the point flow field has a simple structure, uniform fluid distribution and good degassing effect. The "nipple" structure of the current electrolyzer plate is a point flow field; the cross-finger flow field is also called a discontinuous flow field. It is a more complex flow guide structure, which can generally force the reactants to transfer to the diffusion layer, and improve the performance of the electrolyzer to a certain extent. In addition to the above four conventional flow fields, electrolytic cells that use three-dimensional metal mesh structures (such as diamond mesh, stretched mesh, woven mesh, etc.) to replace conventional flow field plates are currently widely used, which effectively reduces the cost of the electrolytic cell and improves the performance of the electrolytic cell to a certain extent.

[0005] Chinese patent CN 114703494 discloses an electrolytic cell anode plate, which is composed of a plurality of protrusions on one side of the plate, an anode flow channel is formed between the protrusions, and the plate is provided with an outlet flow channel and an inlet flow channel, and the outlet flow channel and the inlet flow channel are connected to the anode flow channel. This flow field improves the transmission efficiency of the reaction water to a certain extent, so that the reaction water is evenly distributed in the flow field. However, the water flow resistance of the flow field plate is large, which is not conducive to the use of large-surface positive plates. Chinese patent CN112626542 discloses a metal plate mesh flow field structure, the metal plate has a first surface and a second surface in the thickness direction thereof, and a through water inlet and a water outlet are provided along the thickness direction of the metal plate. The flow field structure is simple and low in cost, but the flow field has limited water distribution and degassing effects.

[0006] In view of the problems existing in the flow field plates of the current electrolytic cells, the utility model discloses a structure with a highly efficient turbulent flow field, and its beneficial effects include: 1) improving the contact area and structural mode between the electrolyte and the electrode plates in the electrolytic cell, which has the characteristics of shortening the electrolyte path, reducing resistance, and improving the flow field; 2) having a strong turbulent effect in the electrode plates of the electrolytic cell, so that a rapid degassing effect is produced during the electrolysis process, reducing the accumulation of bubbles in the liquid in the flow channel, avoiding the accumulation of bubbles in the flow channel to form large bubbles, and improving the active reaction area and water electrolysis efficiency. Utility Model Content

[0007] The utility model discloses a water electrolysis flow field structure capable of rapidly removing bubbles, comprising a rectangular wave flow field and a periodically repeated trapezoidal flow channel groove on a rectangular convex ridge. The width of the trapezoidal flow channel groove is similar to the width of the rectangular convex ridge. The trapezoidal flow channel groove is adjacent to two trapezoidal convex ridges on the left and right, and the trapezoidal groove is connected to two parallel transverse direct current channels up and down. The trapezoidal grooves on the rectangular convex ridge on the same step are equidistantly or non-equidistantly distributed in parallel with the trapezoidal grooves on the adjacent steps. The flow field plate, the electrolysis chamber partition, the electrode and the diffusion layer together constitute the electrolysis chamber unit.

[0008] The flow field structure can realize electrolyte flow guidance along the XY axis in the direction parallel to the electrode surface.

[0009] The flow field plate has a rectangular tooth structure, the upper step surface of the rectangular convex ridge is in contact with the diffusion layer of the electrolytic chamber, and the lower step surface is in contact with the partition, forming a closed cavity for the flow of electrolyte.

[0010] Preferably, the flow field plate can be made of stainless steel, titanium alloy, aluminum alloy, carbon steel, etc., and is prepared by punching a metal sheet and then bending the sheet metal.

[0011] The flow field structure is a parallel straight flow channel in the electrolyte flow direction along the X-axis. The electrolyte flows through the parallel cavity formed between the flow field plate and the diffusion layer, and the gas generated by electrolysis flows more easily along the X-axis through the parallel cavity formed between the partition plate and the flow field plate. The layered flow of electrolyte and gas can achieve gas-liquid separation and more effectively increase the contact reaction area between the electrolyte and the plate.

[0012] The flow field structure is a flow field structure with a "trapezoidal" open hole slot structure arranged periodically in the electrolyte flow direction along the Y axis. The structure has the characteristics of a variable diameter flow channel along the electrolyte direction, so that the liquid flow turbulence is generated during the flow of the electrolyte along the Y direction, which can more effectively and quickly remove small-sized bubbles generated during the electrolysis process, greatly reduce the accumulation of bubbles in the liquid in the flow channel, thereby forming large bubbles, and can greatly improve the active reaction area and water electrolysis efficiency.

[0013] Preferably, the size of the flow field trapezoidal opening groove is set according to the different area sizes of the flow field plate. The lower base of the trapezoidal groove is about twice the size of the upper base.

[0014] Preferably, the spacing of the trapezoidal grooves is consistent with or similar to the size of the trapezoidal grooves, and is generally set to the width of the ridges;

[0015] Preferably, the ridges and grooves where the flow field plate contacts the diffusion layer have relatively small size differences, both set to be in the range of 1-30 mm.

[0016] Preferably, the axes of the trapezoidal grooves along the Y-axis are on parallel lines with the same spacing, and the axes of the adjacent trapezoidal grooves along the X-axis can be set to correspond to the adjacent trapezoidal ridges.

[0017] Preferably, the flow field plate is connected to the partition plate by a welding process, so as to play the role of supporting, collecting and draining the flow.

[0018] The utility model discloses an electrolytic cell high-efficiency turbulent degassing flow field structure, and its beneficial effects include:

[0019] (1) Increase the contact area between the electrolyte and the electrode plate in the electrolytic cell, shorten the electrolyte path, reduce resistance, and improve the flow field guidance effect;

[0020] (2) The ordered trapezoidal flow field structure in the flow field structure has a strong disturbing effect on the plates of the electrolytic cell, which produces a rapid degassing effect during the electrolysis process, reduces the accumulation of bubbles in the liquid in the flow channel, avoids the accumulation of bubbles in the flow channel to form large bubbles, and improves the active reaction area and water electrolysis efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0022] Figure 1 A flow field structure diagram provided for an embodiment of the present invention;

[0023] Figure 2 A structural diagram of an electrolytic cell provided in an embodiment of the present invention;

[0024] Figure 3 A diagram of the structure of a plate provided in an embodiment of the present invention;

[0025] Figure 4 A flow field structure diagram provided for an embodiment of the present invention.

[0026] List of parts and reference numerals:

[0027] 1-flow field plate, 101-upper step surface of trapezoidal convex ridge, 102-trapezoidal groove, 103-parallel flow channel in X direction, 2-partition plate, 3-cathode diffusion layer, 4-electrolyzer electrode, 5-anode diffusion layer, 6-anode flow field plate, 7-partition plate, 201-anode inlet, 202-cathode outlet, 203-anode outlet, 204-cathode inlet, 104-flow field plate, 105-trapezoidal groove, 106-upper bottom of trapezoidal groove, 107-lower bottom of trapezoidal groove. DETAILED DESCRIPTION

[0028] In order to more clearly illustrate the overall concept of the present application, a detailed description is given below in an illustrative manner in conjunction with the accompanying drawings.

[0029] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0030] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific embodiments disclosed below.

[0031] In addition, in the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0032] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0033] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0034] In the present application, unless otherwise clearly specified and limited, a first feature "above" or "below" a second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0035] A highly efficient turbulent degassing flow field structure for a water electrolyzer. The implementation principle of the utility model is that the reaction electrolyte is introduced into the electrode plate flow channel through the anode inlet 201 at the top of the flow channel, and the fluid first distributes the electrolyte horizontally in the lateral direction along the parallel flow channel -103 in the X direction. Then it flows step by step to the second, third, fourth...flow channels in the X direction through the trapezoidal groove flow channel in the Y direction. When the electrolyte passes through the trapezoidal groove flow channel, it first alternately passes through the upper bottom 106 of the trapezoidal groove and the lower bottom 107 of the trapezoidal groove flow channel. Since the upper and lower bottom widths of the trapezoidal groove are significantly different, when the fluid flows through the trapezoidal groove, the actual flow direction of the liquid phase is constantly changed through the diameter change of the trapezoidal groove, which promotes the generation of turbulence in the fluid, prevents the formation and aggregation of bubbles, and allows the bubbles to leave the electrode surface in time with the liquid and enter the parallel flow channel 103, ensuring the efficient transmission of the gas-liquid two-phase in the flow channel, thereby improving the electrolysis efficiency. The flowing gas-liquid two-phase flow disperses in the parallel flow channel 103, and easily flows in the fluid groove formed by the flow field plate and the partition along the X direction, so that the main gas channel and the main liquid channel flow separately, which increases the contact area between the reaction electrolyte and the electrode, and further improves the electrolysis efficiency. The flow field structure is first punched into a trapezoidal hole, and then bent at a right angle to form a flow field plate, and then the flow field plate is fixed to the partition by welding to form an electrolytic cell plate structure.

[0036] like Figure 3 As shown, the Y-direction trapezoidal groove of the flow field structure has a trapezoidal upper bottom width of 2.0-3.0mm, a trapezoidal lower bottom width of 5.0-6.0mm, a ridge width that can be set to 3.0mm, and a trapezoidal groove depth of 1.5-2.5mm. Along the Y direction, the center of the trapezoidal groove is located on parallel lines with the same spacing. In adjacent trapezoidal grooves, the upper bottom of the first-step trapezoidal groove corresponds to the lower bottom of the second-step trapezoidal groove. The reaction electrolyte flows along the same straight line along the Y flow direction, and the overall flow effect is that it flows along the same straight line through the variable diameter flow channel. During the flow of the reaction electrolyte, the liquid and the edge of the trapezoidal groove are blocked, causing a change in the flow direction, thereby producing a turbulent effect on the flow. The turbulent flow quickly removes the bubbles generated on the electrode surface during the electrolysis process. After the bubbles are carried away by the liquid phase flow, they are quickly filled with the electrolyte, which can achieve full contact between the electrolyte and the electrode and improve the electrolysis efficiency. Generally, for PEM electrolyzers, the electrolyte is ultrapure water, and the flow field plate can be obtained by plating corrosion-resistant precious metals on the surface of the conductive metal sheet. Similarly, the metal separator can be provided with a flow field plate cavity, or the metal separator and the outer frame can be combined to form a flow field plate cavity, which provides a physical space for the flow of electrolyte and a flow and reaction place for the gas-liquid two-phase flow. Furthermore, the components such as the plates and electrodes are stacked and fastened in sequence to form a high-efficiency electrolytic cell.

[0037] like Figure 4As shown, along the Y direction, the center of the trapezoidal groove is located on parallel lines with different spacings. On the adjacent ridge structure, the upper bottom of the first-step trapezoidal groove corresponds to the lower bottom of the second-step trapezoidal ridge. The reaction electrolyte flows along the Y flow direction and along the periodic wavy line. The width of the upper bottom of the trapezoid is 2.0-3.0mm, the width of the lower bottom of the trapezoid is 5.0-6.0mm, the width of the ridge can be set to 3.0mm, and the depth of the trapezoidal groove is 1.5-3.0mm. Its beneficial effect is that it further enhances the periodic change of the flow direction of the electrolyte, enhances the turbulence effect, and more effectively removes the bubbles generated by the reaction.

[0038] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0039] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A highly efficient turbulent and degassing flow field structure for electrolyzed water, characterized in that: The flow field structure comprises a rectangular wave step surface and periodically repeated trapezoidal flow channel grooves formed on the rectangular convex ridge.

2. The electrolytic water efficient turbulence and degassing flow field structure according to claim 1, characterized in that: The width of the trapezoidal flow channel groove is similar to that of the rectangular ridge. The trapezoidal flow channel groove is adjacent to two trapezoidal ridges on the left and right. At the same time, the trapezoidal groove is connected to two parallel transverse direct current channels from top to bottom. The ridge is divided into an upper step surface and a lower step surface.

3. The electrolytic water efficient turbulence and degassing flow field structure according to claim 1, characterized in that: The trapezoidal upper base width of the trapezoidal flow channel groove is 2.0-3.0 mm, the trapezoidal lower base width is 5.0-6.0 mm, and there are two adjacent trapezoidal ridges on the left and right of the trapezoidal flow channel groove. The trapezoidal groove and the trapezoidal ridges are distributed at periodic intervals on the same step surface.

4. The electrolyzed water efficient turbulence and degassing flow field structure according to claim 1, characterized in that: The electrolyte flows in a direction perpendicular to the rectangular step surface and flows over the rectangular ridge surface through the trapezoidal grooves.

5. The electrolytic water efficient turbulence and degassing flow field structure according to claim 2, characterized in that: The trapezoidal grooves on the rectangular ridges on the same step surface are distributed in parallel with the trapezoidal grooves on the adjacent step surfaces in an equidistant or non-equidistant manner.

6. The electrolyzed water efficient turbulence and degassing flow field structure according to claim 2, characterized in that: The upper step surface is in contact with the electrolytic cell electrode, and the lower step surface is in contact with the electrolytic cell separator.

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