A fuel cell bipolar plate surface hydrophilic and hydrophobic performance detection tool and detection method

Abstract

The application discloses a kind of fuel cell bipolar plate surface hydrophilic and hydrophobic performance detection tool and detection method, including the anode clamp and cathode clamp of opposite arrangement, in use, anode clamp and cathode clamp will be measured bipolar plate and be fixed between the compression of two;Multiple convex structures, set in the opposite surface of anode clamp and cathode clamp, convex structure corresponds the flow channel groove position of measured bipolar plate;At least one opening is set to one end of convex structure, and convex structure is inserted into flow channel groove.The water contact angle of unknown electrode plate can be determined by the application, so that the hydrophilic and hydrophobic performance of bipolar plate can be quantitatively judged, to reflect the real surface state and performance change of bipolar plate.

Description

Technical Field

[0001] This invention relates to the technical field of fuel cells, and in particular to a tooling and method for testing the hydrophilicity and hydrophobicity properties of fuel cell bipolar plate surfaces. Background Technology

[0002] Water management is crucial for fuel cells. Fuel cells require a sufficiently humid environment for chemical reactions; conversely, they produce water during operation. Excessive water buildup can negatively impact normal operation and even lifespan if not promptly removed. The hydrophilicity / hydrophobicity of the bipolar plate surface significantly influences water management. The water contact angle is commonly used to assess this property. Current testing methods, such as the national standard "Proton Exchange Membrane Fuel Cells Part 6: Bipolar Plate Characteristic Test Methods," which proposes a method for testing the water contact angle on a flat plate (10cm×10cm), only allow testing on a flat plate. However, the flow channels of a real bipolar plate are quite fine, lacking sufficient planar area for testing. Therefore, this method and its associated testing fixtures cannot effectively reflect the hydrophilicity / hydrophobicity of a real bipolar plate. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies by proposing a tooling and method for testing the hydrophilicity and hydrophobicity properties of fuel cell bipolar plate surfaces.

[0004] To achieve the above objectives, the present invention employs the following technical solution: a tooling for testing the hydrophilicity and hydrophobicity properties of a fuel cell bipolar plate surface, comprising:

[0005] The anode clamp and cathode clamp are arranged opposite each other. In use, the anode clamp and the cathode clamp press the bipolar plate to be tested between them and fix it.

[0006] Multiple protruding structures are disposed on the opposite surfaces of the anode clamp and the cathode clamp, and the protruding structures correspond to the flow channel groove positions of the bipolar plate to be tested;

[0007] At least one opening is provided at one end of the protruding structure. When the protruding structure is inserted into the flow channel groove, the opening can be controlled to inject water into the flow channel groove.

[0008] During testing, multiple bipolar plates with different water contact angles are fixed between the anode and cathode clamps, and the protruding structure is inserted into the flow channel groove. The time required for water to completely drain from the flow channel is determined by injecting water through the opening. The water contact angle of the unknown electrode plate is determined by a fitting formula based on multiple experiments.

[0009] As a further description of the above technical solution, the cross-section of the protrusion structure is an isosceles trapezoid, and the side of the protrusion structure closest to the surface of the fixture is the long base of the trapezoid.

[0010] As a further description of the above technical solution, the anode clamp, the cathode clamp, and the protruding structure are all made of transparent material to facilitate observation of the water flow.

[0011] As a further description of the above technical solution, the number of the protruding structures is not greater than the number of the flow channel grooves.

[0012] As a further description of the above technical solution, a valve is provided inside the opening, and the valve is used to control the entry of water.

[0013] As a further description of the above technical solution, bolt holes are correspondingly provided at the four corners of the anode clamp and the cathode clamp, and bolts are inserted into the bolt holes to fasten the two clamps.

[0014] A method for testing the hydrophilicity / hydrophobicity properties of a fuel cell bipolar plate surface, comprising the following steps:

[0015] S1. Select multiple bipolar plates with different water contact angles and number them sequentially.

[0016] S2, Place the bipolar plate to be tested into any of the testing fixtures in claims 1-6, open the opening to allow water to enter the flow channel, and record the time t when the flow channel is filled with water;

[0017] S3, ventilate the flow channel groove, and simultaneously capture and record the time T when the water is completely discharged from the flow channel groove using a high-magnification camera;

[0018] S4. Based on the water contact angle and the corresponding drainage time, a table is drawn to form a fitting curve, and the fitting curve is converted into a fitting formula.

[0019] S5, place the unknown bipolar plate into the detection fixture, execute steps S2-S3, record the drainage time T, and calculate the corresponding water contact angle according to the fitting formula.

[0020] As a further description of the above technical solution, in step S1, the water contact angle is selected in the range of 20°-150°.

[0021] As a further description of the above technical solution, in step S4, the fitted curve is converted into a fitting formula as an exponential function formula.

[0022] As a further description of the above technical solution, in step S2, the test water sample is deionized water.

[0023] The present invention has the following beneficial effects:

[0024] 1. This invention employs multiple bipolar plates with different water contact angles, fixed between the anode and cathode clamps of a testing fixture. Simultaneously, a protruding structure is inserted into the corresponding flow channel groove. Water is injected through openings, and the time for deionized water to completely drain from the flow channel is recorded. A data table is formed by the coordinates of the water contact angles and drainage times obtained from different water contact angles, and then converted into a fitting formula. By determining the water contact angle of the unknown electrode plate, the hydrophilic and hydrophobic properties of the bipolar plate can be quantitatively judged, reflecting the true surface state and performance changes of the bipolar plate. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the testing fixture;

[0026] Figure 2 This is a flowchart of a method for testing the hydrophilicity and hydrophobicity properties of bipolar plate surfaces.

[0027] Legend:

[0028] 1. Anode clamp; 2. Cathode clamp; 3. Bolt hole; 4. Raised structure; 5. Opening. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Reference Figure 1 This invention provides an embodiment of a planar hydrophilicity / hydrophobicity performance testing fixture for fuel cell bipolar plates. Specifically, it includes an anode clamp 1 and a cathode clamp 2 arranged opposite to each other. Multiple protrusions 4 are provided on the opposite surfaces of both clamps, with the protrusions 4 arranged along the length of the clamp surface. During testing, the bipolar plate to be tested is fixed between the anode clamp 1 and the cathode clamp 2. The protrusions 4 on the clamp surface are inserted into the flow channel grooves of the bipolar plate. At one end of the protrusion 4, specifically near the inlet of the fuel cell stack gas chamber, an opening 5 is provided. The opening 5 serves as a water inlet. After the protrusion 4 is inserted into the corresponding flow channel groove, deionized water can be injected into the flow channel groove through the water inlet to test the flow channel drainage time.

[0031] The cross-sectional shape of the protrusion 4 is an isosceles trapezoid, where the side of the protrusion 4 closest to the fixture is the longer base of the trapezoid, and the side inserted into the flow channel groove is the shorter base of the trapezoid. The reason for setting the protrusion 4 as an isosceles trapezoid is that during the testing and assembly process, the protrusion 4 will come into contact with the flow channel groove of the bipolar plate. In order to allow the protrusion 4 to enter the flow channel groove without completely blocking it, the protrusion 4 is machined into an isosceles trapezoid shape with the side closest to the flow channel groove being narrower and the side closest to the fixture being longer. At the same time, the side length of the protrusion 4 is used to control the depth of the protrusion 4 entering the flow channel groove. When using this testing fixture for testing, the depth of the protrusion 4 entering the flow channel groove is required to be equal to the penetration depth of the membrane electrode carbon paper during the actual fuel cell stack assembly process, thereby simulating the actual operating environment of the fuel cell stack; or the depth of the protrusion 4 entering the flow channel is required to be no more than 10% of the depth of the flow channel groove.

[0032] Meanwhile, the number of protrusions 4 is no greater than the number of flow channels. This is because during assembly, the protrusions 4 correspond to the flow channels. To ensure that deionized water can directly enter the flow channels through the inlets on the protrusions 4, the optimal implementation would be that the number of protrusions 4 equals the number of flow channels. However, since the flow channels require precise machining dimensions, using the same number of protrusions 4 would increase the machining cost of the tooling. Therefore, to reduce cost while ensuring testing accuracy, the number of protrusions 4 is less than the number of flow channels. However, the protrusions 4 are positioned in the upper, middle, and lower regions of the bipolar plate flow channels, with at least two protrusions 4 in each region. This configuration reduces the difficulty and cost of tooling machining while still allowing for the determination of the bipolar plate's hydrophilicity / hydrophobicity properties using the same regional distribution.

[0033] In this testing fixture, the anode clamp 1, cathode clamp 2, and protruding structure 4 are all transparent and visible. By making them transparent, the water injection and drainage in the flow channel can be observed more directly. At the same time, it is possible to observe whether there is dirt or damage inside the testing fixture, so that it can be cleaned or replaced in a timely manner to ensure the accuracy of the test. The protruding structure 4 is made of a highly resilient material.

[0034] A valve is provided on the surface of the opening 5 at one end of the protruding structure 4. The valve is connected to the deionized water chamber and the entry of deionized water can be controlled by switching it on and off.

[0035] refer to Figure 1 Bolt holes 3 are provided at all four corners of the clamp. The two clamps can be fastened by inserting bolts into the bolt holes 3 to clamp the bipolar plate between the two clamps. In other feasible embodiments, the two clamps can also be fastened by pressing a weight on the clamp.

[0036] During testing, multiple bipolar plates with different water contact angles are fixed between the anode clamp 1 and the cathode clamp 2 of the testing fixture. At the same time, the protruding structure 4 is inserted into the corresponding flow channel groove, and water is injected through the opening 5. The time for deionized water to be completely discharged from the flow channel is recorded. The coordinates of the water contact angle and discharge time obtained from different water contact angles are used to form a data table, which is then converted into a fitting formula to determine the water contact angle of the unknown electrode plate. This allows for a quantifiable assessment of the hydrophilic and hydrophobic properties of the bipolar plate, reflecting the true surface state and performance changes of the bipolar plate.

[0037] Furthermore, compared to existing testing methods on flat plates, this testing fixture can simulate a real environment and obtain accurate hydrophilic and hydrophobic performance indicators of bipolar plates.

[0038] refer to Figure 2 This application provides a method for testing the hydrophilicity and hydrophobicity performance of a fuel cell bipolar plate planar surface, the specific steps of which include:

[0039] S1. Select multiple bipolar plates with different water contact angles and number them sequentially. The range of water contact angles selected is 20°-150°. At least ten bipolar plates with different water contact angles should be selected, such as 20°, 30°, 40°, etc.

[0040] S2, place the bipolar plate to be tested into any of the testing fixtures in claims 1-6, open the opening 5 to allow water to enter the flow channel, and record the time t when the flow channel is filled with water. When performing this step, after the bipolar plate of the previous water contact angle is tested, the bipolar plate of the next water contact angle is tested.

[0041] S3, ventilate the flow channel groove, and simultaneously capture and record the time T when the water is completely discharged from the flow channel groove using a high-magnification camera;

[0042] S4. Based on the water contact angle and the corresponding drainage time, a table is plotted to form a fitting curve. This fitting curve is then converted into a fitting formula. After testing bipolar plates with different water contact angles, the water contact angle and the corresponding drainage time are plotted as coordinate points (α, T). Multiple coordinate points are used to form a fitting curve in a coordinate system. The fitting curve can then be converted into a fitting formula using Excel. One possible fitting formula is: T = aα m +bα n +…+c;

[0043] S5, place the unknown bipolar plate into the detection fixture, execute steps S2-S3, record the drainage time T, and calculate the corresponding water contact angle according to the fitting formula.

[0044] Based on the above testing scheme, the drainage performance is quantified by calibrating the hydrophobic angle and drainage time, which can provide guidance for application in actual products and subsequent product development.

[0045] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A tooling for testing the hydrophilicity and hydrophobicity properties of a fuel cell bipolar plate surface, characterized in that, include: The anode clamp and cathode clamp are arranged opposite each other. In use, the anode clamp and the cathode clamp press the bipolar plate to be tested between them and fix it. Multiple protrusions are provided on the opposite surfaces of the anode clamp and the cathode clamp, and the protrusions correspond to the flow channel groove positions of the bipolar plate to be tested. At least one opening is provided at one end of the protruding structure. When the protruding structure is inserted into the flow channel groove, the opening can be controlled to inject water into the flow channel groove. During testing, multiple bipolar plates with different water contact angles are fixed between the anode and cathode clamps, and the protruding structure is inserted into the flow channel groove. The time required for water to completely drain from the flow channel is determined by injecting water through the opening. The water contact angle of the unknown electrode plate is determined by a fitting formula based on multiple experiments.

2. The fixture for testing the hydrophilicity / hydrophobicity properties of a fuel cell bipolar plate surface according to claim 1, characterized in that, The cross-section of the protruding structure is an isosceles trapezoid, and the side of the protruding structure closest to the surface of the fixture is the long base of the trapezoid.

3. The tooling for testing the hydrophilicity and hydrophobicity properties of a fuel cell bipolar plate surface according to claim 1, characterized in that, The anode clamp, the cathode clamp, and the protruding structure are all made of transparent material to facilitate observation of the water flow.

4. The fixture for testing the hydrophilicity / hydrophobicity properties of a fuel cell bipolar plate surface according to claim 1, characterized in that, The number of protruding structures is no greater than the number of flow channel grooves.

5. The fixture for testing the hydrophilicity / hydrophobicity properties of a fuel cell bipolar plate surface according to claim 1, characterized in that, A valve is provided on the surface of the opening, and the valve is used to control the entry of water.

6. The tooling for testing the hydrophilicity and hydrophobicity properties of a fuel cell bipolar plate surface according to claim 1, characterized in that, The anode clamp and the cathode clamp have bolt holes at their four corners, and bolts are inserted into the bolt holes to fasten the two clamps.

7. A method for testing the hydrophilicity / hydrophobicity properties of a fuel cell bipolar plate surface, characterized in that, The specific steps include: S1. Select multiple bipolar plates with different water contact angles and number them sequentially. S2, Place the bipolar plate to be tested into any of the testing fixtures in claims 1-6, open the opening to allow water to enter the flow channel, and record the time t when the flow channel is filled with water; S3, ventilate the flow channel groove, and simultaneously capture and record the time T when the water is completely discharged from the flow channel groove using a high-magnification camera; S4. Plot a table based on the water contact angle and the corresponding drainage time to form a fitting curve, and then convert the fitting curve into a fitting formula. S5, place the unknown bipolar plate into the detection fixture, execute steps S2-S3, record the drainage time T, and calculate the corresponding water contact angle according to the fitting formula.

8. The method for detecting the hydrophilicity / hydrophobicity properties of fuel cell bipolar plate surfaces according to claim 7, characterized in that, In step S1, the water contact angle is selected in the range of 20°-150°.

9. The method for detecting the hydrophilicity / hydrophobicity properties of fuel cell bipolar plate surfaces according to claim 7, characterized in that, In step S4, the fitted curve is converted into a fitting formula that is an exponential function formula.

10. The method for detecting the hydrophilicity / hydrophobicity properties of fuel cell bipolar plate surfaces according to claim 7, characterized in that, In step S2, deionized water is used as the test water sample.

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