A corrugated flow field plate

Abstract

The present invention discloses a corrugated flow field plate, which is used for an anode flow field plate of an active direct methanol fuel cell. The corrugated flow field plate is provided with a flow channel, and a regularly distributed flow disturbance structure is provided in the flow channel. The flow disturbance structure is a regularly distributed corrugated structure, forming a corrugated flow channel. The characteristics of the corrugated structure are sinusoidal functions. A sin( Wx ),in A is the amplitude, W is the angular frequency, and the crests and troughs of the corrugated structure form a disturbance structure. The disturbance structure in the corrugated flow field plate of the present invention increases the wall velocity gradient of the flow channel, so the shear rate of the wall increases, which accelerates the emission of the product on the anode side, carbon dioxide gas, and alleviates the situation of insufficient fuel supply and reduced battery performance caused by carbon dioxide gas blockage on the anode side. At the same time, the disturbance structure in the corrugated flow field plate is more conducive to the mass transfer process, thereby improving the output performance of the battery.

Description

Technical Field

[0001] The invention relates to the technical field of direct methanol fuel cells, and in particular to a corrugated flow field plate for an active direct methanol fuel cell. Background Art

[0002] The electric energy generated by fuel cells is directly converted from the chemical energy of the raw materials themselves, and has high energy density, low environmental pollution, and advantages such as the abundance of raw materials, which have attracted more and more attention. Among them, compared with the high cost of hydrogen raw materials, dangerous storage and transportation, and harsh conditions for use of hydrogen fuel cells, which belong to the proton exchange membrane fuel cell, direct methanol fuel cells, which use methanol as the anode raw material, have good application prospects due to their low operating temperature (generally working at room temperature), high theoretical specific energy, easy to carry and safe to use. They are considered by the industry to be the most promising type of fuel cell to be commercialized first.

[0003] The blockage of carbon dioxide at the anode and water at the cathode are both product management issues. After the product is generated, it enters the flow field through the porous gas diffusion layer. The appropriate porous gas diffusion layer and flow field structure will help the product to be separated and discharged in a timely and effective manner. Otherwise, it will affect the distribution of the reactants or even completely block them, making it impossible to provide basic fuel supply for the electrochemical reaction, resulting in reduced battery performance or even cessation of operation. Therefore, from this perspective, the product management problem at both poles is an urgent part of direct methanol fuel cells that cannot be ignored.

[0004] At present, most researchers focus on the structure of the collector plate when solving product management problems, but most of the research is concentrated on passive direct methanol fuel cells, while there is less research on active direct methanol fuel cells. However, the latter has a higher power density and greater application value, so its product management should be given more attention.

[0005] At the same time, the traditional flow field plate is more about changing the overall distribution of the flow channel, and less attention is paid to the structure of a single flow channel in the flow field plate. Therefore, in the present invention, a spoiler structure is added to the single flow channel, and thus developed into a corrugated flow channel with a structural feature that is a sinusoidal function. The spoiler structure in the corrugated flow field plate increases the wall velocity gradient of the flow channel, so the shear rate of the wall increases, which accelerates the emission of the product on the anode side - carbon dioxide gas, and alleviates the situation of insufficient fuel supply and decreased battery performance caused by the blockage of carbon dioxide gas on the anode side. At the same time, the spoiler structure in the corrugated flow field plate is more conducive to the mass transfer process, thereby improving the output performance of the battery. Summary of the invention

[0006] In order to effectively alleviate the gas blockage phenomenon on the anode side of an active direct methanol fuel cell, enhance the mass transfer process, and thus improve the output performance of the battery. The present invention discloses a corrugated flow field plate. The corrugated flow field plate is used for an active direct methanol fuel cell, and the active direct methanol fuel cell comprises a left end plate, a PVC silicone pad, a cathode flow field plate, a PTFE pad, a membrane electrode assembly, a PTFE pad, an anode flow field plate, a PVC silicone pad, a right end plate, and a bolt group. The corrugated flow field plate is used for the anode side of the active direct methanol fuel cell.

[0007] The present invention is implemented by the following technical solutions:

[0008] A corrugated flow field plate is used for an anode flow field plate of an active direct methanol fuel cell. The corrugated flow field plate is provided with a flow channel, and regularly distributed turbulent structures are arranged in the flow channel.

[0009] Furthermore, the flow-disturbing structure is a regularly distributed corrugated structure, forming a corrugated flow channel.

[0010] Furthermore, the characteristic of the corrugated structure is a sinusoidal function. A sin( Wx ),in A is the amplitude, W is the angular frequency, and the crests and troughs of the corrugated structure form a turbulent structure.

[0011] Furthermore, the amplitude A The value range is 0.05~0.2, the angular frequency W The value range is 1~5.

[0012] Furthermore, the material of the corrugated flow field plate is conductive metal.

[0013] Furthermore, the conductive metal includes alloy steel, aluminum alloy, and copper alloy.

[0014] Furthermore, the alloy steel includes stainless steel.

[0015] Furthermore, the minimum smoothness of the surface of the corrugated flow field plate is 0.3, and the minimum smoothness of the inner surface of the flow channel of the corrugated flow field plate is 0.8.

[0016] Furthermore, the flow channel structure in the corrugated flow field plate is distributed in a serpentine shape.

[0017] Furthermore, the corners of each flow channel of the corrugated flow field plate are rounded transitions.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. In conventional direct methanol fuel cells, the flow field plate and the collector plate are separated, which increases the overall mass of the battery and the internal resistance of the battery. The corrugated flow field plate designed in the present invention is an integration of the conventional flow field plate and the collector plate, which not only plays a role in uniformly distributing reactants and products, but also plays a role in collecting electrons.

[0020] 2. The traditional flow field plate is more about changing the overall distribution of the flow channel, and pays less attention to the structure of a single flow channel in the flow field plate. In the present invention, a spoiler structure is added to a single flow channel, and thus developed into a structural feature showing a sinusoidal function. A sin( Wx ) of the corrugated flow channel.

[0021] 3. The traditional flow field plate does not significantly improve the battery performance. In the present invention, due to the turbulent structure in the corrugated flow field plate, the velocity gradient of the flow channel wall increases, thereby increasing the shear rate of the wall, accelerating the emission of the product on the anode side, carbon dioxide gas, and alleviating the situation of insufficient fuel supply and reduced battery performance caused by carbon dioxide gas blockage on the anode side. At the same time, the turbulent structure in the corrugated flow field plate is more conducive to the mass transfer process, thereby improving the output performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a front view of an active direct methanol fuel cell;

[0023] Figure 2 A front view of a corrugated flow field plate according to an embodiment of the present invention;

[0024] Figure 3 It is a front view of an existing common rounded flow channel flow field plate;

[0025] Figure 4 It is a front view of an existing common right-angle flow channel flow field plate;

[0026] Figure 5 The output curve of the battery performance corresponding to the use of a common rounded channel flow field plate for an active direct methanol fuel cell at different methanol supply flow rates;

[0027] Figure 6 The output curve of the battery performance corresponding to the use of corrugated flow field plates in an active direct methanol fuel cell at different methanol supply flow rates;

[0028] Figure 7 The output curve of the battery performance corresponding to the use of a common rounded flow field plate for an active direct methanol fuel cell at different methanol supply concentrations;

[0029] Figure 8 The output curve of the battery performance corresponding to the use of corrugated flow field plates in an active direct methanol fuel cell at different methanol supply concentrations;

[0030] The figure shows: 1-left end plate; 2-first PVC silicone pad; 3-cathode flow field plate; 4-membrane electrode assembly; 5-anode flow field plate; 6-second PVC silicone pad; 7-right end plate; 8-bolt group; 9-first PTFE pad; 10-second PTFE pad. DETAILED DESCRIPTION

[0031] To further understand the present invention, the present invention is further described below in conjunction with the accompanying drawings. However, it should be noted that the scope of protection claimed by the present invention is not limited to the scope described in the following embodiments.

[0032] like Figure 1 As shown, the active direct methanol fuel cell has the following components from left to right: left end plate 1, first PVC silicone pad 2, cathode flow field plate 3, first PTFE pad 9, membrane electrode assembly 4, second PTFE pad 10, anode flow field plate 5, second PVC silicone pad 6, right end plate 7, bolt group 8. The end plate material is a transparent acrylic plate with high light transmittance, with a size of 60mm×60mm and a thickness of 15mm. There are 8 bolt holes with a diameter of 5mm processed around it. Each layer of components is locked by a bolt group consisting of 8 M4 bolts, and each bolt is tightened by a torque wrench with a torque of 1.6N·m.

[0033] Wherein, the membrane electrode assembly 4 is composed of a membrane electrode and a PTFE sealing gasket (thickness of 0.2 mm). In this example, all homemade membrane electrodes are gas diffusion electrodes, mainly including an anode gas diffusion electrode, a cathode gas diffusion electrode and a proton exchange membrane. Wherein, the gas diffusion electrode is composed of a substrate and a catalyst layer, and the substrate is composed of a support layer and a microporous layer. The support layer adopts TGP-H-060 model fuel cell special carbon paper from Toray Company of Japan. The main component of the microporous layer is conductive carbon black (Vulcan XC72, E-TEK of the United States), which is formed on the surface of one side of the support layer. The catalyst powder (Johnson Matthey, USA) and an appropriate amount of isopropanol analytical pure reagent are mixed and suspended evenly to form a catalyst slurry, which is evenly sprayed on the surface of the microporous layer to form a catalyst layer. The anode is a Pt-Ru catalyst with a loading of 4 mg cm -2 The cathode is a Pt catalyst with a loading of 2 mg cm -2 The proton exchange membrane uses the commercial Nafion 117 electrolyte membrane from DuPont, USA. The proton exchange membrane needs to be pretreated before use, and is soaked in 5% volume fraction hydrogen peroxide, deionized water, 0.5 mol·L -1The pretreated proton exchange membrane is soaked in deionized water and dilute sulfuric acid solution for 1 hour each. During the soaking period, each solution is at 80°C to remove organic impurities, residual hydrogen peroxide reagent, metal impurities and residual sulfuric acid on the surface of the proton exchange membrane. The pretreated proton exchange membrane is soaked in deionized water for storage. When used, it is taken out and placed in the air to dry naturally. The prepared anode gas diffusion electrode and cathode gas diffusion electrode are placed in the middle area with their respective catalytic layer sides facing the proton exchange membrane, and are placed in a hot press. After hot pressing, a membrane electrode is formed. The hot pressing pressure is 10MPa, the temperature is 120°C, and the time is 2min. The prepared membrane electrode is placed in a sealed sample bag for storage.

[0034] Embodiment 1:

[0035] The battery output performance of the novel corrugated flow field plate of the present invention and the traditional rounded flow field plate were studied under different methanol supply flow rates. Figure 2 As shown, in the experimental group, the anode flow field plate 5 of the active direct methanol fuel cell adopts the corrugated flow field plate of the present invention, and its corrugation characteristics are sinusoidal functions 0.1sin(5 x ), the material is stainless steel, the surface finish of the corrugated flow field plate is 0.3, and the inner surface finish of the corrugated flow field plate channel is 0.8. The processing flow of the corrugated flow field plate is mainly divided into blanking, heat treatment, medium wire cutting low current slow forming, and electrolytic polishing processing steps; the cathode flow field plate 3 of the active direct methanol fuel cell adopts a traditional right-angle flow field plate, such as Figure 4 An experimental control group was set up, in which the anode flow field plate 5 of the active direct methanol fuel cell in the control group adopted a conventional rounded flow field plate, such as Figure 3 As shown, the flow field plate on the cathode side still uses a traditional right-angle flow field plate, such as Figure 4 As shown. The flow channel width in the anode flow field plate 5 is 1.2 mm. The anode flow field plate 5 has fuel inlet and outlet circular holes at the lower left and upper right, with a radius of 1 mm. The thickness of the anode flow field plate 5 is 1.5 mm. The methanol supply concentration is set to 2 mol·L -1 , the methanol supply flow rate value is set to 5 groups, respectively: 0.2 mL·min -1 , 0.5mL·min -1 、1mL·min -1 、2mL·min -1 、4mL·min -1 The cathode oxygen supply flow rate is 100 sccm. The battery output performance of the two is as follows Figure 5 and Figure 6 As shown in the corresponding performance output curve, the battery corresponding to the traditional flow field plate is 1mL·min -1 The maximum value was obtained, while the battery corresponding to the corrugated flow field plate was 2 mL min -1The maximum value is obtained when the methanol flow rate is 2 mL min -1 When the battery uses a corrugated flow field plate, the performance is improved by 13.4% compared with the right-angle flow field plate. It is obvious that the corrugated flow field plate can alleviate the gas blockage of the battery anode and enhance the mass transfer process, thereby improving the battery performance.

[0036] Embodiment 2:

[0037] The battery output performance of the novel corrugated flow field plate of the present invention and the conventional rounded flow field plate was studied under different methanol supply concentrations. Figure 2 As shown, in the experimental group, the anode flow field plate 5 of the active direct methanol fuel cell adopts the corrugated flow field plate of the present invention, and its corrugation characteristics are sinusoidal functions 0.1sin(5 x ), the material is stainless steel, the minimum surface finish of the corrugated flow field plate is 0.3, and the minimum surface finish of the inner surface of the corrugated flow field plate flow channel is 0.8. The processing flow of the corrugated flow field plate is mainly divided into blanking, heat treatment, medium wire cutting low current slow forming, and electrolytic polishing processing steps; the cathode flow field plate 3 of the active direct methanol fuel cell adopts a traditional right-angle flow field plate, such as Figure 4 An experimental control group was set up, in which the anode flow field plate 5 of the active direct methanol fuel cell in the control group adopted a conventional rounded flow field plate, such as Figure 3 As shown, the cathode flow field plate 3 still adopts the traditional right-angle flow field plate, such as Figure 4 As shown. The flow channel width in the flow field plate is 1.2 mm. The flow field plate has fuel inlet and outlet circular holes at the lower left and upper right. The radius is 1 mm. The overall flow field plate thickness is 1.5 mm. The methanol supply flow rate is set to the methanol supply flow rate corresponding to the optimal performance output in Example 1, which is 2 mL min -1 , methanol supply concentration was set to 6 groups, respectively: 0.5 mol·L -1 , 2mol·L -1 , 4mol·L -1 , 6mol·L -1 , 8mol·L -1 、10mol·L -1 The cathode oxygen supply flow rate is 100 sccm. The battery output performance of the two is as follows Figure 7 and Figure 8 As shown in the corresponding performance output curve, the battery performance corresponding to the traditional flow field plate and the corrugated flow field plate is both within 8 mol·L -1 The maximum value is obtained when the methanol supply concentration is 8 mol·L -1 When the battery uses a corrugated flow field plate, the performance is improved by 7.96% compared with the right-angle flow field plate. It is obvious that the corrugated flow field plate can alleviate the gas blockage of the battery anode and enhance the mass transfer process, thereby improving the battery performance.

[0038] The above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A corrugated flow field plate, used for an anode flow field plate of an active direct methanol fuel cell, characterized in that: The corrugated flow field plate is provided with a single flow channel, and the single flow channel in the corrugated flow field plate is distributed in a serpentine shape; A regularly distributed flow-disturbing structure is arranged in the single flow channel; The flow-disturbing structure is a regularly distributed corrugated structure, forming a corrugated flow channel; The characteristic of the corrugated flow channel is a sinusoidal function A sin( Wx ),in A is the amplitude, W is the angular frequency, and the crests and troughs of the corrugated flow channel form a turbulent structure; The amplitude A The value range is 0.05~0.2, the angular frequency W The value range is 1~5; The material of the corrugated flow field plate is conductive metal; The minimum smoothness of the surface of the corrugated flow field plate is 0.3, and the minimum smoothness of the inner surface of a single flow channel of the corrugated flow field plate is 0.8; Each corner of the single flow channel is a rounded transition.

2. The corrugated flow field plate according to claim 1, characterized in that: The conductive metal includes any one of alloy steel, aluminum alloy and copper alloy.

3. The corrugated flow field plate according to claim 2, characterized in that: The alloy steel includes stainless steel.

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