Novel bipolar plate flow field structure and bipolar plate for PEM water electrolysis

Abstract

The utility model provides a novel bipolar plate flow field structure and PEM electrolyzed water bipolar plate, the novel bipolar plate flow field structure comprises a ridge beam, flow channels and a flow guide structure, the flow channels are uniformly arranged in parallel, each flow channel is of a trapezoidal groove structure, the ridge beam is of a trapezoidal structure, each flow channel is provided with a flow channel inlet and a flow channel outlet, and the flow guide structure is arranged on the ridge beam. The flow guide structure is arranged in the flow channel, and the flow area of the flow channel inlet is smaller than that of the flow channel outlet; the utility model has the beneficial effects that the through-flow area is gradually increased along with gradual approaching to the outlet, so that the water flow speed is more uniform, the temperature uniformity of the electrolytic bath is ensured, in addition, the flow resistance of water vapor can be reduced, and the blockage caused by gradual increase of gas is prevented.

Description

Technical Field

[0001] The utility model relates to the technical field of bipolar plates, in particular to a novel bipolar plate flow field structure and a bipolar plate for PEM electrolyzed water. Background Technique

[0002] Hydrogen energy is a clean and efficient secondary energy source, a green and low-carbon industrial raw material, and a flexibly utilized energy carrier. Hydrogen energy will play an important role in a new power system dominated by new energy.

[0003] The PEM electrolyzed water hydrogen production technology has the advantages of high efficiency, small floor area, fast load dynamic response, good matching with renewable energy, no corrosion caused by lye, and high hydrogen purity. It is more suitable for the application scenarios of hydrogen production coupled with renewable energy systems and distributed on-site hydrogen production. With the rapid development of new energy sources such as photovoltaic and wind power, the PEM electrolyzed water hydrogen production technology has great development potential. It can be predicted that in the near future, with the gradual maturity and industrialization of PEM electrolyzer technology, the cost of PEM electrolyzers and peripheral systems will be further reduced, and the market share will also be further expanded.

[0004] As an important component of the PEM electrolyzer, the bipolar plate is a component as important as the membrane electrode. It mainly plays the role of supporting the electrolyzer, collecting and conducting electrons, separating hydrogen and oxygen, and guiding the flow of substances on the electrode surface. The flow field structure of the bipolar plate has an important impact on the uniform distribution of substances, the discharge of water and heat, and the uniform distribution of current. The bipolar plate generally uses a titanium material plate with high strength, strong corrosion resistance, and excellent electrical conductivity. The high strength of the titanium material mainly plays the role of supporting the electrolyzer, collecting and conducting electrons, separating hydrogen and oxygen, and guiding the flow of substances on the electrode surface. The flow channels engraved on the bipolar plate play the role of distributing gas and water. It is based on the principle of physical diversion. The conventional design has uniform dimensions, that is, the flow areas at the outlet and inlet are the same; there are various styles of flow channel structure designs reported in public, but the flow areas of these flow channels are fixed values. As hydrogen and oxygen gases are generated, they will exist in the form of bubbles in the water, increasing the flow resistance. In addition, due to the fixed flow area, as the amount of gas increases, the water flow rate will accelerate, affecting the heat exchange effect. The heat exchange effect is worse in the area closer to the outlet, thus affecting the overall performance of the electrolyzer. Summary of the Utility Model

[0005] To overcome the above problems existing in the prior art, the utility model provides a novel bipolar plate flow field structure and a bipolar plate for PEM electrolyzed water.

[0006] The present utility model discloses a novel bipolar plate flow field structure, including a backbone, flow channels, and a diversion structure. The flow channels are arranged uniformly and parallelly. The flow channels are trapezoidal groove structures, the backbone is a trapezoidal structure. The flow channels are provided with a flow channel inlet and a flow channel outlet. The diversion structure is arranged in the flow channels. The flow area of the flow channel inlet is smaller than that of the flow channel outlet.

[0007] On this basis, the width value of the flow channel inlet is set as a, and the width value of the flow channel outlet is set as b. The width ratio of a and b is 1:1.2 - 2. The width ratio of the backbone at the flow channel inlet position to the backbone width at the flow channel outlet position is 1.2 - 2:1.

[0008] On this basis, the cross-sectional shape of the flow channel is a gradually expanding shape, gradually increasing from the inlet to the outlet.

[0009] On this basis, the depth of the flow channel is 1 - 3 mm.

[0010] On this basis, the cross-sectional area shape of the backbone is a converging shape, gradually shrinking from the inlet to the outlet.

[0011] On this basis, the diversion structure is a protrusion arranged in the flow channel, and the height of the protrusion is 0.2 - 0.8 mm.

[0012] A bipolar plate for PEM electrolyzed water has the novel bipolar plate flow field structure described above.

[0013] Compared with the prior art, the beneficial effects of the present utility model are as follows: The flow channels are trapezoidal flow channels, arranged uniformly and parallelly. The flow area of each flow channel inlet is smaller than that of the flow channel outlet, which increases the fluid velocity, promotes the exclusion of gas, and avoids the risk of large fluid flow resistance. By changing the width values of the flow channel inlet and outlet, the flow area gradually increases, making the water flow velocity more uniform, which is more conducive to taking out the heat generated by the electrolytic cell and contributing to the heat balance and heat management of the electrolytic cell. In addition, by increasing the depth of the flow channel, the flow area of the fluid is also larger, preventing the influence of gas accumulation on the performance of the electrolytic cell. Description of the Drawings

[0014] Figure 1 It is a schematic diagram of the bipolar plate flow field structure of the present utility model;

[0015] In the figure: 1. Backbone; 2. Flow channel; 3. Flow channel inlet; 4. Flow channel outlet; 5. Diversion structure. Detailed Embodiments

[0016] The following further details the present utility model in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present utility model.

[0017] The utility model discloses a novel bipolar plate flow field structure, including a backbone 1, flow channels 2 and a diversion structure 5. The flow channels 2 are arranged uniformly and parallelly. The flow channels 2 are trapezoidal groove structures, and the depth of the flow channels 2 is 1 - 3 mm. The backbone 1 is a trapezoidal structure, and the cross-sectional shape of the flow channels 2 is a gradually expanding shape, gradually increasing from the inlet to the outlet. The flow channels 2 are provided with a flow channel inlet 3 and a flow channel outlet 4. The diversion structure 5 is arranged in the flow channels 2. The flow area of the flow channel inlet 3 is smaller than that of the flow channel outlet 4, so that the fluid velocity increases, promoting the exclusion of gas and avoiding the risk of large fluid flow resistance. The width value of the flow channel inlet 3 is set as a, and the width value of the flow channel outlet 4 is set as b. The width ratio of a and b is 1:1.2 - 2. By changing the width values of the flow channel inlet and outlet, the flow area gradually increases, making the water flow velocity more uniform, more conducive to taking out the heat generated by the electrolytic cell, and contributing to the heat balance and heat management of the electrolytic cell. In addition, by increasing the depth of the flow channel, the flow area of the fluid is also larger, preventing the influence of gas accumulation on the performance of the electrolytic cell.

[0018] The cross-sectional area shape of the backbone 1 is a converging shape, gradually shrinking from the inlet to the outlet. The width ratio of the backbone 1 at the position of the flow channel inlet 3 to the width of the backbone 1 at the position of the flow channel outlet 4 is 1.2 - 2:1.

[0019] The diversion structure 5 is a protrusion arranged in the flow channel, and the height of the protrusion is 0.2 - 0.8 mm.

[0020] Example 1

[0021] Select a:b as 1:1.2. The size of the bipolar plate flow field area is 340 mm * 260 mm. The width of the flow channel inlet is 1 mm, the width of the ridge is 1.2 mm, the depth is 1 mm. The width of the flow channel outlet is 1.2 mm, the width of the ridge is 1.0 mm, the depth is 1 mm. The height of the diversion structure is 0.6 mm. Select 20 bipolar plates, and assemble them with upper and lower end plates, upper and lower current collector plates, upper and lower insulating plates, upper and lower end polar plates and fasteners into a short stack of 21 electrolytic cells. Each electrolytic cell is installed with a cell voltage inspection, marked as electrolytic short stack one. The electrolytic short stack one is placed on the test verification platform for performance testing. The test current is 2000 A, that is, the current density is 1.5 A / cm 2 The average cell voltage of the electrolytic short stack one in the test result is 1.76 V, and the direct current power consumption is 4.21 kWh / Nm 3 H 2 .

[0022] Example 2

[0023] Select a:b as 1:2, the size of the bipolar plate flow field area is 340mm * 260mm, the width of the flow channel inlet is 1mm, the ridge width is 1.2mm, the depth is 1mm, the width of the flow channel outlet is 2mm, the ridge width is 1.0mm, the depth is 1mm, the height of the flow guiding structure is 0.6mm. Select 20 bipolar plates, and assemble them with upper and lower end plates, upper and lower current collector plates, upper and lower insulating plates, upper and lower end polar plates and fasteners into a short stack of 21 electrolytic cells. Install a cell voltage inspection for each electrolytic cell, and label it as electrolytic short stack two; place the electrolytic short stack two on the test and verification platform for performance testing, the test current is 2000A, that is, the current density is 1.5A / cm 2 The test result shows that the average cell voltage of the electrolytic short stack two is 1.758V, and the DC power consumption is 4.20kWh / Nm 3 H 2 。

[0024] Comparative Example 1

[0025] Select a:b as 1:1, the size of the bipolar plate flow field area is 340mm * 260mm, the width of the flow channel inlet is 2mm, the ridge width is 2mm, the depth is 1mm, the width of the flow channel outlet is 2mm, the ridge width is 2mm, the depth is 1mm, the height of the flow guiding structure is 0.6mm. Select 20 bipolar plates, and assemble them with upper and lower end plates, upper and lower current collector plates, upper and lower insulating plates, upper and lower end polar plates and fasteners into a short stack of 21 electrolytic cells. Install a cell voltage inspection for each electrolytic cell, and label it as electrolytic short stack three. The average cell voltage of the electrolytic short stack three is 1.81V, and the DC power consumption is 4.33kWh / Nm 3 H 2 。

[0026] It can be seen from the comparison results of Example 1, Example 2 and Comparative Example 1 that the performance of the electrolytic short stack one is more excellent, and the energy consumption is reduced by 3%.

[0027] Example 3

[0028] This embodiment provides a bipolar plate for PEM electrolyzed water, having this novel bipolar plate flow field.

[0029] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inner", "front", "center", "both ends", etc. is the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0030] In the present utility model, unless otherwise clearly defined and limited, terms such as "installation", "setting", "connection", "fixation", "swivel connection", "padding", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components. Unless otherwise clearly defined, for those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0031] The above description shows and describes the preferred embodiments of the present utility model. As mentioned above, it should be understood that the present utility model is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments. Instead, it can be used in various other combinations, modifications, and environments, and can be changed within the scope of the inventive concept described herein through the above teachings or the techniques or knowledge in related fields. And any changes and alterations made by those skilled in the art that do not depart from the spirit and scope of the present utility model shall fall within the protection scope of the appended claims of the present utility model.

Claims

1. A new type of bipolar plate flow field structure, characterized in that: The invention comprises a ridge (1), a flow channel (2) and a flow guide structure (5), wherein the flow channels (2) are evenly arranged in parallel, the flow channels (2) are trapezoidal groove structures, the ridge (1) is a trapezoidal structure, the flow channel (2) is provided with a flow channel inlet (3) and a flow channel outlet (4), the flow guide structure (5) is arranged in the flow channel (2), and the flow area of ​​the flow channel inlet (3) is smaller than the flow area of ​​the flow channel outlet (4).

2. The novel bipolar plate flow field structure according to claim 1 is characterized in that: The width of the flow channel inlet (3) is set to a, and the width of the flow channel outlet (4) is set to b, wherein the width ratio of a to b is 1:1.2-2.

3. The novel bipolar plate flow field structure according to claim 1 is characterized in that: The cross-sectional shape of the flow channel (2) is gradually expanding, gradually increasing from the inlet to the outlet.

4. The novel bipolar plate flow field structure according to claim 1 is characterized in that: The flow channel (2) has a depth of 1 to 3 mm.

5. The novel bipolar plate flow field structure according to claim 1 is characterized in that: The ratio of the width of the ridge beam (1) at the flow channel inlet (3) to the width of the ridge beam (1) at the flow channel outlet (4) is 1.2 to 2:1, and the cross-sectional shape of the ridge beam (1) is inward-retracted, gradually decreasing from the inlet to the outlet.

6. The novel bipolar plate flow field structure according to claim 1 is characterized in that: The flow-guiding structure (5) is a protrusion arranged in the flow channel, and the height of the protrusion is 0.2 to 0.8 mm.

7. A bipolar plate for PEM water electrolysis, characterized in that: The invention has a novel bipolar plate flow field structure as claimed in any one of claims 1 to 6.

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