Air-cooled proton exchange membrane fuel cell bipolar plate

Abstract

The application relates to a forced air-cooled proton exchange membrane fuel cell bipolar plate, which comprises an anode plate and a cathode plate stacked in an up-down mode. The cathode plate comprises a cathode flow field, a second rib and a cooling flow field arranged on the cathode flow field; the anode plate comprises an anode flow field, a hydrogen gas inlet, a hydrogen gas outlet and a first rib. The anode flow field is provided with a plurality of hydrogen gas flow channels, and the cathode flow field is provided with a plurality of oxygen gas flow channels; the bipolar plate cooling structure of the application is provided with an open channel (inclined groove) on the rib of the cathode flow field. The microstructure added to the rib of the cathode flow field is designed from the perspective of improving the oxygen concentration and the air cooling area. The microstructure on the rib of the cathode flow field can connect the air from the adjacent channels to increase the contact area between the air and the gas diffusion layer. The application can efficiently dissipate heat, reduce the power consumption required by the external auxiliary components of the electric pile, effectively improve the power generation efficiency of the fuel cell electric pile, and ensure the safe and stable operation of the fuel cell.

Description

Technical Field

[0001] This invention belongs to the field of proton exchange membrane fuel cell technology, and specifically relates to a cooling structure for the bipolar plate of a proton exchange membrane fuel cell. Background Technology

[0002] In proton exchange membrane fuel cells (PEMFCs), energy is released through the electrochemical reaction of hydrogen and oxygen and output as electrical energy. They can operate at low temperatures and are not limited by the Carnot cycle during energy conversion. Only water is produced throughout the entire production process, achieving true zero pollution. PEMFCs can be classified into air-cooled fuel cells and water-cooled fuel cells based on their cooling method. The structure of an air-cooled PEMFC stack is simpler than that of a liquid-cooled PEMFC stack, with its bipolar plates consisting of only two flow fields: the anode and the cathode. Its system configuration uses a fan as the main balancing component, making it much simpler than a water-cooled PEMFC system, which requires components such as an air compressor, hydrogen recirculation pump, humidifier, heat exchanger, and liquid pump.

[0003] For air-cooled fuel cells, two questions remain unclear: how are temperature, humidity, and mass distributed within the cell when oxidant and coolant flows are combined, and how does the geometry of the cathode channel affect cell performance. It is necessary to understand the mechanisms underlying the relationship between these coupled physical quantities and the cathode channel size.

[0004] Traditional PEMFC bipolar plates often employ a parallel DC channel cooling flow field, such as... Figure 8 and Figure 9 As shown, the structure is simple and easy to manufacture, but its cooling distribution effect is poor. The middle part of the bipolar plate of the fuel cell often has a much better cooling effect than the two sides, resulting in uneven cooling effect of the entire fuel cell. Summary of the Invention

[0005] Therefore, it is necessary to address the aforementioned problems by providing an air-cooled proton exchange membrane fuel cell bipolar plate, aiming to solve the uneven cooling effect of traditional parallel bipolar plates. This bipolar plate cooling structure can efficiently dissipate heat, while reducing the power consumption required by external auxiliary components of the fuel cell stack, effectively improving the power generation efficiency of the fuel cell stack, and ensuring the safe and stable operation of the fuel cell.

[0006] To achieve the above objectives, this invention proposes an air-cooled proton exchange membrane fuel cell bipolar plate. The air-cooled proton exchange membrane fuel cell bipolar plate includes an anode plate and a cathode plate stacked vertically. The cathode plate includes a cathode flow field, a second rib, and a cooling flow field disposed on the cathode flow field. The anode plate includes an anode flow field, a hydrogen inlet, a hydrogen outlet, and a first rib. The anode plate has multiple hydrogen flow channels, and the cathode plate has multiple oxygen flow channels.

[0007] Furthermore, the hydrogen flow channel extends along the length of the bipolar plate, and the oxygen flow channel extends along the width of the bipolar plate.

[0008] Furthermore, the anode flow field on the anode plate is provided with a plurality of first ribs spaced apart along its length, and the hydrogen flow channel is defined between two adjacent first ribs;

[0009] Furthermore, the cathode flow field on the cathode plate is provided with a plurality of second ribs spaced apart along its width direction, and the oxygen flow channel is defined between two adjacent second ribs.

[0010] Furthermore, the cooling flow field includes the cooling structure disposed on the second rib of the cathode flow field.

[0011] Furthermore, the cooling structure located on the cathode flow field of the bipolar plate of the air-cooled proton exchange membrane fuel cell is an inclined groove on the second rib.

[0012] Furthermore, the inclined groove is continuously disposed on multiple second ribs.

[0013] Furthermore, the inclined groove is disposed on the second rib in the same direction as the width direction of the bipolar plate; or the inclined groove is disposed intersectingly on the second rib in the width direction of the bipolar plate.

[0014] Furthermore, the inclined groove is aligned and disposed on the second rib along the length direction of the bipolar plate.

[0015] Furthermore, the inclined groove has a width (W) of 0.3mm to 3mm, a length (L) of 1.5mm to 3mm, an angle (θ) of 30° to 75°, and a groove depth (D) of 0.3mm to 1mm. The spacing (S) between adjacent inclined grooves is 3mm to 10mm.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] The cooling flow field structure provided by this invention can be used for bipolar plates made of metal substrates, as well as bipolar plates made of graphite and composite materials. It can be manufactured through CNC machining, molding, or stamping / casting. Simulation calculations and experimental tests show that this flow field design can effectively reduce the temperature generated in the fuel cell stack, accelerate the heat dissipation efficiency of the bipolar plate, and effectively solve the problem of uneven heat dissipation in bipolar plates.

[0018] The bipolar plate cooling structure of this invention features open channels (cooling structures) on the ribs of the cathode flow field. These microstructures added to the cathode flow field ribs are designed to increase oxygen concentration and air cooling area. The microstructures on the cathode flow field ribs allow the cathode flow field to connect with air from adjacent channels, increasing the contact area between air and the gas diffusion layer. This structure enables the PEMFC to generate velocity in a direction perpendicular to the entire battery plane, forcing more reactant gases into the gas diffusion layer and ultimately reaching the catalyst layer. It also carries liquid water accumulated in the porous layer into the branch channels and discharges it through the outlet channel. Therefore, it effectively avoids cathode flow field flooding, effectively increases oxygen concentration within the porous electrode, improves fuel cell output performance, and prevents localized oxygen deficiency.

[0019] The thermal convection of the cooling structure of the air-cooled bipolar plate of the present invention can improve the performance of the stacked membrane, reduce the membrane dehydration rate and temperature distribution uniformity, because its internal water balance is better.

[0020] The air-cooled bipolar plate of this invention solves the problem of uneven heat dissipation in traditional air-cooled bipolar plates. Therefore, it greatly simplifies the structure of the air-cooled fuel cell stack, and also simplifies the peripheral auxiliary equipment for stack operation, such as heat dissipation equipment, thereby significantly reducing the weight of the entire power generation unit.

[0021] The air-cooled bipolar plate of the present invention has the advantages of high output performance, low operating temperature and high energy density, and can be widely used in drones, electronic devices and backup power supplies. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of Example 1;

[0023] Figure 2 This is a schematic diagram of the overall structure from another angle of Embodiment 1;

[0024] Figure 3 for Figure 1 Schematic diagram of the anode plate structure;

[0025] Figure 4 for Figure 2 Schematic diagram of the cathode plate structure;

[0026] Figure 5 for Figure 1 Enlarged structural diagram at point A;

[0027] Figure 6 for Figure 2 Enlarged structural diagram at point B;

[0028] Figure 7 for Figure 6 Enlarged structural diagram at point C;

[0029] Figure 8 This is a schematic diagram of the overall structure in comparison.

[0030] Figure 9 This is a schematic diagram of the whole from another angle of the comparison.

[0031] Figure 10 This is a schematic diagram of the overall structure of Example 2;

[0032] Figure 11 This is a schematic diagram of the entire embodiment from another angle;

[0033] Figure 12 Polarization curves of fuel cells with different cathode air-cooled flow fields;

[0034] Figure 13 The average temperature of the fuel cell stack under different cathode air-cooled flow fields;

[0035] Figure 14 This represents the maximum temperature difference between fuel cells with different cathode air-cooled flow fields.

[0036] Explanation of icon numbers:

[0037] 100 air-cooled proton exchange membrane fuel cell bipolar plate with 7 tilted slots (cooling structure)

[0038] 111 Anode plate 131 Cooling flow field

[0039] 121 Cathode plate 141 Anode flow field

[0040] 1 Hydrogen inlet 151 Cathode flow field

[0041] 2. Hydrogen outlet groove width W

[0042] 3 Hydrogen flow channel L-groove length

[0043] 4. First rib S-groove spacing

[0044] 5. Oxygen flow channel D groove depth

[0045] 6. The groove angle of the second rib θ; Detailed Implementation

[0046] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0047] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0048] Example 1

[0049] like Figures 1 to 4 As shown, the air-cooled proton exchange membrane fuel cell bipolar plate 100 of Embodiment 1 of the present invention includes an anode plate 111 and a cathode plate 121 stacked on top of each other.

[0050] The cathode plate 121 includes a cathode flow field 151, a second rib 6, and a cooling flow field 131 disposed on the cathode flow field 151; the anode plate 111 includes an anode flow field 141, a hydrogen inlet 1, a hydrogen outlet 2, and a first rib 4.

[0051] The anode plate 111 is provided with multiple hydrogen flow channels 3, and the cathode plate 121 is provided with multiple oxygen flow channels 5; wherein, the hydrogen flow channels 3 extend along the length direction of the bipolar plate 100, and the oxygen flow channels 5 extend along the width direction of the bipolar plate 100.

[0052] Among them, the anode flow field 141 on the anode plate 111 is provided with a plurality of first ribs 4 at intervals along its length direction, and hydrogen flow channels 3 are defined between two adjacent first ribs 4.

[0053] The cathode flow field 151 on the cathode plate 121 is provided with a plurality of second ribs 6 at intervals along its width direction, and an oxygen flow channel 5 is defined between two adjacent second ribs 6.

[0054] The cooling flow field 131 includes a cooling structure 7 disposed on the second rib 6 of the cathode flow field.

[0055] Cooling structure 7 is located on the cathode flow field 151 of the bipolar plate 100 of the air-cooled proton exchange membrane fuel cell; the cooling structure 7 is the inclined groove 7 on the second rib 6.

[0056] The inclined groove is disposed on the second rib in the same direction as the width of the bipolar plate, and the inclined groove is disposed on the second rib in alignment with the length of the bipolar plate.

[0057] The width W of the inclined groove 7 is 0.3 mm, the length L of the inclined groove 7 is 1.5 mm, the angle θ of the inclined groove 7 is 30°, the groove depth D of the inclined groove 7 is 0.7 mm, and the spacing S between adjacent inclined grooves 7 is 3 mm.

[0058] The hydrogen flow channel 3 in the anode flow field has a width of 1.5 mm and a length of 300 mm; the first rib 4 has a width of 1.5 mm and a length of 300 mm. The entire anode flow field 141 region forms a rectangle of 49.5 mm * 300 mm.

[0059] The oxygen flow channel 5 in the cathode flow field has a width of 1.5 mm and a length of 70 mm; the second rib 6 has a width of 1.5 mm and a length of 70 mm. The entire cathode flow field 151 region forms a rectangle of 70 mm * 280.5 mm.

[0060] The bipolar plate 100 is a graphite bipolar plate 100, which is manufactured by CNC machining.

[0061] like Figure 8 and Figure 9 The comparative example is the cooling flow field of a traditional PEMFC bipolar plate, which often uses a parallel DC channel structure, and the parameters are the same as those of the flow channel in this embodiment.

[0062] Example 2

[0063] The overall structure of this embodiment is similar to that of Embodiment 1, and will not be repeated. The difference lies in that the grooves are intersecting along the width of the bipolar plate on the second rib to improve the gas mixing degree, such as... Figure 10 and Figure 11 As shown, the intersecting inclined slots allow air to exchange across the oxygen channels on both sides of the cathode plate in an open airflow field, disrupting the airflow and thus improving gas mixing. This promotes gas diffusion in the cathode-side gas diffusion layer, increases the effective area of ​​the electrode during actual stack operation, and significantly improves the overall performance and specific power density of the fuel cell.

[0064] The performance of Examples 1, 2, and the comparative example was compared under the same operating conditions. The ambient temperature was approximately 24℃ ± 2℃, and the relative humidity was approximately 45% ± 5%. The performance comparison results are as follows: Figure 12 As shown, the air-cooled fuel cell stack with open channels on the ribs of the cathode flow field exhibits better performance than the conventional air-cooled fuel cell stack. The maximum output power of Example 1 is increased by 9.7% compared to Example 1. The maximum output power of Example 2 is increased by 17.2% compared to Example 1.

[0065] Figure 13 and 14The figure shows the average temperature of the PEMFC stack under different cathode air-cooled flow fields and the maximum temperature difference between cells under different currents. As can be seen from the figure, the average temperature of the stack gradually increases with increasing current, and the temperature difference between cells also increases. However, the highest temperature in Example 1 is 45°C, and the maximum temperature difference is approximately 5.6°C. The highest temperature in Example 2 is 47°C, and the maximum temperature difference is approximately 8°C. The highest temperature in the comparative example is 51°C, and the maximum temperature difference is approximately 11°C. Clearly, setting open channels on the ribs of the cathode flow field can significantly reduce the maximum temperature difference in the PEMFC stack, resulting in a more uniform temperature distribution.

[0066] Research has shown that the thermal convection effect of the cooling structure of the air-cooled bipolar plate of this invention can improve the output performance of the fuel cell stack and enhance the uniformity of temperature distribution due to its better internal water balance. Therefore, the air-cooled bipolar plate of this invention solves the problem of uneven heat dissipation inherent in traditional air-cooled bipolar plates. This greatly simplifies the structure of the air-cooled fuel cell stack and also simplifies peripheral auxiliary equipment such as heat dissipation devices, thereby significantly reducing the weight of the entire power generation unit. It can be widely used in fields such as drones, electronic devices, and backup power supplies.

[0067] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0068] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A wind-cooled proton exchange membrane fuel cell bipolar plate, characterized in that, The device includes an anode plate and a cathode plate stacked on top of each other. The cathode plate includes a cathode flow field, second ribs, and a cooling flow field disposed on the cathode flow field. The anode plate includes an anode flow field, first ribs, a hydrogen inlet, and a hydrogen outlet. The anode plate has multiple hydrogen flow channels, and the cathode plate has multiple oxygen flow channels. The hydrogen flow channels extend along the length direction of the bipolar plate, and the oxygen flow channels extend along the width direction of the bipolar plate. The anode flow field on the anode plate has multiple first ribs spaced along its length direction, and the hydrogen flow channels are defined between two adjacent first ribs. The cathode flow field on the cathode plate has multiple second ribs spaced along its width direction, and the oxygen flow channels are defined between two adjacent second ribs. The cooling flow field includes a cooling structure disposed on the second ribs of the cathode flow field. The cooling structure is an inclined groove provided on the ribs of the cathode flow field; the inclined groove is an open channel provided on the ribs of the cathode flow field; the inclined groove is a microstructure on the ribs of the cathode flow field. The inclined grooves are continuously provided on multiple second ribs; The inclined grooves are arranged in the same direction along the width direction of the bipolar plate on the second rib; or the inclined grooves are arranged intersectingly along the width direction of the bipolar plate on the second rib.

2. The bipolar plate according to claim 1, characterized in that, The inclined groove is aligned and disposed on the second rib along the length direction of the bipolar plate.

3. The bipolar plate according to claim 1, characterized in that, The width (W) of the inclined groove is 0.3mm to 3mm, the length (L) of the inclined groove is 1.5mm to 3mm, the angle (θ) of the inclined groove is 30° to 75°, and the groove depth (D) of the inclined groove is 0.3mm to 1mm; the spacing (S) between adjacent inclined grooves (7) is 3mm to 10mm.

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