Renewable fuel single cell

Abstract

This invention discloses a renewable fuel cell, comprising an oxygen electrode flow field plate, an oxygen electrode diffusion layer, a membrane electrode, a hydrogen electrode diffusion layer, and a hydrogen electrode flow field plate stacked sequentially. The oxygen electrode flow field plate includes a base plate with a central mounting cavity, a front inlet cavity, and a rear outlet cavity. The central mounting cavity of the base plate has several rows of corrugated plates arranged evenly from top to bottom to form a flow field reaction zone. The front inlet cavity has several rows of inlet fluid distribution units arranged evenly from top to bottom to form a fluid distribution inlet zone. The rear outlet cavity has several rows of outlet fluid distribution units arranged evenly from top to bottom to form a fluid distribution outlet zone. In FC (Fuel Cell) operating mode, this invention ensures the diffusion capacity of the reactant gas while improving mass transfer capacity throughout the gas transport process. This reduces gas starvation caused by reactant gas blockage and flooding caused by the accumulation of generated water, thereby increasing the performance of the renewable fuel cell.

Description

Technical Field

[0001] This invention belongs to the field of new energy technology, specifically relating to a renewable fuel cell. Background Technology

[0002] The integrated regenerative fuel cell (URFC) based on a proton exchange membrane is a dual-function renewable energy conversion device that can simultaneously generate electricity and produce hydrogen through both fuel cell (FC) and electrolytic cell (EC) modes. It boasts advantages such as high specific energy density and no self-discharge, showing great promise in aerospace, renewable energy, and other fields, and can also achieve self-sufficiency by combining with solar or wind power.

[0003] URFC (Ultra-Renewable Fuel Cell) is a stacked fuel cell based on two end plates. Each end plate has a main pipe leading to an internal flow channel on the end plate. In EC (Electro-Chemical) mode, one end plate acts as the cathode and the other as the anode, electrolyzing water into hydrogen and oxygen. In FC (Fuel-Fuel Cell) mode, one end plate acts as the anode and the other as the cathode, consuming hydrogen and oxygen and generating electricity. In practical applications, URFC faces challenges such as insufficient cycle efficiency and stability. The flow field design of the URFC significantly impacts internal heat distribution, reactant transport, and overall efficiency. For example, in FC mode, liquid water generated at the cathode outlet is difficult to remove, and reactant transport efficiency is low.

[0004] Integrated regenerative fuel cells (URFCs) face challenges related to efficiency, stability, and lifespan. A well-designed flow field can mitigate corrosion caused by oxides generated in the electrolysis mode of URFCs, further extending the overall cell lifespan and efficiency, and reducing maintenance costs. When an URFC is in fuel cell mode, improper stoichiometry and relative humidity can lead to flooding in the cathode gas diffusion layer and cathode flow channels, potentially even submerging parts of the reaction zone surface. Simultaneously, reactants may not diffuse quickly enough to the catalytic reaction layer, resulting in significant concentration polarization and drastically reducing cell performance, thus hindering the URFC's ability to switch between fuel cell mode and water electrolysis mode. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the above-mentioned technologies by providing a renewable fuel cell with low flow resistance and high transmission efficiency.

[0006] To achieve the above objectives, the present invention provides a renewable fuel cell, comprising an oxygen electrode flow field plate, an oxygen electrode diffusion layer, a membrane electrode, a hydrogen electrode diffusion layer, and a hydrogen electrode flow field plate stacked sequentially, wherein the oxygen electrode flow field plate and the hydrogen electrode flow field plate are arranged symmetrically along the membrane electrode.

[0007] The oxygen electrode flow field plate includes a base plate, and a central mounting cavity, a front inlet cavity, and a rear outlet cavity are formed on the base plate. The central mounting cavity is connected to the front inlet cavity and the rear outlet cavity, respectively. The central mounting cavity of the base plate has several rows of corrugated plates arranged evenly from top to bottom to form a flow field reaction zone. The front inlet cavity, located in front of the flow field reaction zone, has several rows of inlet fluid distribution units arranged evenly from top to bottom to form a fluid distribution inlet zone. The rear outlet cavity, located behind the flow field reaction zone, has several rows of outlet fluid distribution units arranged evenly from top to bottom to form a fluid distribution outlet zone.

[0008] Several air inlets connected to the fluid distribution inlet area are opened on the inner wall of the pipe hole at the bottom front end of the base plate, and several air outlets connected to the fluid distribution outlet area are opened on the inner wall of the pipe hole at the top rear end of the base plate.

[0009] Furthermore, the top and bottom surfaces of the central mounting cavity are both formed with wavy curved surfaces that are the same shape as the corrugated plate. Fluid reaction channels are formed between the wavy curved surface at the upper edge and the corrugated plate, between each pair of adjacent corrugated plates, and between the wavy curved surface at the lower edge and the corrugated plate.

[0010] Furthermore, each of the wave-shaped plates includes n curved plates, and the curved surfaces of each two adjacent curved plates are arranged in opposite directions; each curved plate includes a first arc plate and a second arc plate, the center of the first arc plate is concentric with the center of the second arc plate, and the ratio of the arc of the first arc plate to the arc of the second arc plate is 1:2 to 4.

[0011] Furthermore, in the cross-section of each of the curved plates: the horizontal line connecting the end of the first curved plate and the end of the second curved plate is flush with the horizontal line; the angle between the line connecting the end of the first curved plate and the intersection of the first and second curved plates and the horizontal line is α; the angle between the line connecting the end of the second curved plate and the intersection of the first and second curved plates and the horizontal line is β; and the angle α is consistent with the outlet direction of the air inlet.

[0012] Furthermore, α is 0° to 15°, and β is 0° to 0.08°.

[0013] Furthermore, each row of the inlet fluid distribution unit includes at least one inclined boss, and the gap between every two adjacent inclined bosses in each row of the inlet fluid distribution unit is the same as the gap between every two adjacent rows of inlet fluid distribution units, forming an inclined fluid inlet main distribution channel and a horizontal fluid inlet secondary distribution channel; the structure of each row of the outlet fluid distribution unit is the same as that of the inlet fluid distribution unit.

[0014] Furthermore, the outlet direction of each air inlet is the same as the direction of the main distribution channel of the fluid inlet; the inlet direction of each air outlet is the same as the direction of the main distribution channel of the fluid outlet.

[0015] Furthermore, the length of each curved plate is 6 to 10 mm, and the rib width and fluid reaction channel width of each curved plate are equal, both being 1 to 3 mm.

[0016] Furthermore, the inlet fluid distribution unit of the fluid distribution inlet area rotates 180 degrees around the vertical symmetry center line of the flow field reaction zone and coincides with the outlet fluid distribution unit of the fluid distribution outlet area.

[0017] Furthermore, the base plate is provided with sealing grooves around its perimeter and is sealed with silicone rubber sealing rings.

[0018] Compared with existing technologies, the beneficial effects of this invention are as follows: The renewable fuel cell of this invention, when the URFC is in FC operating mode, can ensure the diffusion capacity of the reactant gas, while simultaneously improving mass transfer capacity throughout the gas transport process. This reduces gas starvation caused by reactant gas blockage and flooding caused by the accumulation of generated water, thereby increasing the performance of the renewable fuel cell. In the flow field reaction zone, the flow channels are compactly arranged, resulting in a more compact structure and reduced costs. When the URFC is in EC mode, liquid water generates hydrogen at the lower cathode plate and oxygen at the anode plate. When switching to FC mode, the protrusion distribution structure and fluid reaction channel structure can rapidly transport oxygen to the diffusion layer and catalyst layer, reducing corrosion caused by oxide formation in EC mode. Attached Figure Description

[0019] Figure 1 This is an exploded view of the structure of the renewable fuel cell of the present invention;

[0020] Figure 2 for Figure 1 Schematic diagram of the flow field plate structure of the oxygen electrode;

[0021] Figure 3 for Figure 2 Schematic diagram of the corrugated plate structure;

[0022] Figure 4 for Figure 3 Schematic diagram of structural parameters;

[0023] Figure 5 for Figure 1 A partially enlarged schematic diagram. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments to facilitate a clearer understanding of the invention, but these descriptions do not constitute a limitation on the invention.

[0025] like Figure 1 The renewable fuel cell shown includes an oxygen electrode flow field plate 1, an oxygen electrode diffusion layer 2, a membrane electrode 3, a hydrogen electrode diffusion layer 4, and a hydrogen electrode flow field plate 5, which are stacked sequentially. The oxygen electrode flow field plate 1 and the hydrogen electrode flow field plate 5 have the same structure and are arranged symmetrically along the membrane electrode 3. Only the oxygen electrode flow field plate 1 will be described in detail below. Since the hydrogen electrode flow field plate 5 has the same structure as the oxygen electrode flow field plate 1, it will not be described again.

[0026] like Figure 2 The oxygen electrode flow field plate 1 shown includes a base plate 6, with sealing grooves around its perimeter, and is sealed with silicone rubber sealing rings. According to... Figure 2 The direction is such that a central mounting cavity, a front inlet cavity, and a rear outlet cavity are formed on the base plate 6, and the central mounting cavity is connected to the front inlet cavity and the rear outlet cavity respectively. For example... Figure 3 The mounting cavity in the middle of the base plate 6 shown is arranged from top to bottom (according to...). Figure 2 A flow field reaction zone 10 is formed by several rows of corrugated plates 7 arranged evenly and side by side. The top and bottom surfaces of the central mounting cavity are both formed with wavy curved surfaces 8, identical in shape to the corrugated plates 7. Fluid reaction channels 9 are formed between the upper edge wavy curved surface 8 and the corrugated plates 7, between each pair of adjacent corrugated plates 7, and between the lower edge wavy curved surface 8 and the corrugated plates 7. A fluid distribution inlet zone 11 is formed by several rows of inlet fluid distribution units arranged evenly from top to bottom in front of the flow field reaction zone 10. A fluid distribution outlet zone 12 is formed by several rows of outlet fluid distribution units arranged evenly from top to bottom in the rear outlet zone 10. Simultaneously, the inlet fluid distribution units of the fluid distribution inlet zone are arranged along the vertical symmetrical centerline of the flow field reaction zone (according to...). Figure 2 After rotating 180 degrees around the direction, it coincides with the outlet fluid distribution unit of the fluid distribution outlet area.

[0027] The key point of this invention is: Figure 4Each corrugated plate shown includes n curved plates 13, with the curved surfaces of every two adjacent curved plates 13 arranged in opposite directions. Each curved plate 13 includes a first arc plate 14 and a second arc plate 15, the center of the first arc plate 14 and the center of the second arc plate 15 are concentric, and the ratio of the arc of the first arc plate 14 to the arc of the second arc plate 15 is 1:2 to 4; the length of each curved plate 13 is 6 to 10 mm, and the rib width of each curved plate 13 and the width of the fluid reaction channel 9 are equal, both being 1 to 3 mm.

[0028] like Figure 4 As shown, in the cross-section of each curved plate 13: the horizontal line connecting the end of the first curved plate 14 and the end of the second curved plate 15 is flush with the horizontal line; the angle between the line connecting the end of the first curved plate 14 and the intersection of the first curved plate 14 and the second curved plate 15 and the horizontal line is α; and the angle between the line connecting the end of the second curved plate 15 and the intersection of the first curved plate 14 and the second curved plate 15 and the horizontal line is β.

[0029] like Figure 5 Each row of inlet fluid distribution units includes at least one inclined boss 16. The gap between any two adjacent inclined bosses 16 in each row of inlet fluid distribution units is the same as the gap between any two adjacent rows of inlet fluid distribution units, forming an inclined main fluid inlet distribution channel and a horizontal secondary fluid inlet distribution channel. The structure of each row of outlet fluid distribution units is the same as that of the inlet fluid distribution units.

[0030] Several air inlets (not shown in the figure) are formed on the inner wall of the pipe hole at the bottom front end of the base plate, which are connected to the fluid distribution inlet area 11. The outlet direction of each air inlet is the same as the direction of the main distribution flow channel of the fluid inlet. Similarly, several air outlets 17 (e.g., ...) are formed on the inner wall of the pipe hole at the top rear end of the base plate, which are connected to the fluid distribution outlet area 12. Figure 2 As shown in the diagram, the inlet direction of each air outlet 17 is the same as the direction of the main distribution channel of the fluid outlet. The included angle α is consistent with the outlet direction of the air inlet, ranging from 0° to 15°, and β is calculated to be from 0° to 0.08°.

[0031] The fluid reaction channel exhibits a steep-then-gentle structure from left to right, resulting in less entropy increase and better mass transfer performance compared to traditional direct-flow channels. This not only effectively enhances convective mass transfer but also promotes reaction uniformity and reduces the presence of low-oxygen regions. Furthermore, the periodicity of this structural feature causes periodic changes in gas flow direction, velocity, and pressure, enhancing convection and increasing oxygen transport rates and gas utilization in the diffusion and catalyst layers, while also increasing current density. When the reactant gases enter the fluid reaction channel at different velocities, a velocity difference is generated between adjacent channels, easily leading to secondary flows of reactant gases. This improves the uniformity of gas distribution within the active region and prevents excessively high temperatures caused by localized heating. Due to the presence of these secondary flows, the reactant gases and generated water in adjacent channels collide under the influence of pressure differences within the reaction zone. At relatively low Reynolds numbers, this can be ideally considered a turbulent state, thereby accelerating the reaction rate of the fuel cell. When the reactant gas enters the fluid reaction channel at an angle of attack α, the resistance encountered by the reactant gas during its transport in the channel is minimized according to the definition coefficient of the angle of attack, thus accelerating the transport of the reactant gas in the channel and increasing the reaction rate and current density. When the reactant gas enters or exits the reaction zone of the flow field, it must pass through the fluid distribution inlet and outlet areas, which allows the reactant gas and generated water to be dispersed to reduce blockage. At the same time, the reactant gas can enter the reaction zone of the flow field at a given angle α.

[0032] When the renewable fuel cell is in FC mode, the reactant gas enters the fluid distribution inlet area 6 through the common pipe area 5. The reactant gas is further dispersed by the boss distribution structure in this area, and then enters the flow field reaction zone 7 along the gaps in the distribution structure. It enters the flow channel at an angle of attack α at the fluid reaction channel inlet, where it is accelerated, improving the transport of the reactant gas throughout the process. Furthermore, due to the multiple inlets and outlets in the flow field, the pressure drop in the semi-windmill-like flow channel of the flow field reaction zone 7 is relatively small. In EC mode, this reduces corrosion caused by oxide formation and improves the cycle life of the integrated renewable fuel cell.

[0033] In summary, the renewable fuel cell of this invention, when the URFC is in FC operating mode, can ensure the diffusion capacity of the reactant gas, while improving mass transfer capacity throughout the gas transport process, reducing gas starvation caused by reactant gas blockage and flooding caused by the accumulation of generated water, thus increasing the performance of the renewable fuel cell. In the flow field reaction zone 7, the flow channels are arranged compactly, making the structure more compact and reducing costs. When the URFC is in EC mode, liquid water generates hydrogen at the lower cathode plate and oxygen at the anode plate. When switching to FC mode, the boss distribution structure and fluid reaction channel structure can quickly transport oxygen to the diffusion layer and catalyst layer, reducing corrosion caused by oxide formation in EC mode.

[0034] The Effective Mass Transfer Coefficient (EMTC) is an index characterizing the vertical transport capacity of reactants. Simulation calculations show that the Sherwood number for a 1:2–4 ratio of the curvature of the first to the second arc plate is at least 48.94% higher than that of a conventional direct-flow channel under the same boundary conditions. Therefore, the vertical transport capacity of reactants in a 1:2–4 channel is stronger than that of a conventional channel. Secondly, the Euler number is the relative magnitude of the momentum loss rate during the reaction flow. Simulation analysis shows that the Euler number of a 1:2–4 wave channel is smaller than that of a direct-flow channel and a conventional wave channel. Therefore, the momentum loss caused by a larger pressure difference is smaller. The Mass Transfer Evaluation Criterion (MTEC) characterizes the relationship between the mass transfer coefficient and the pressure difference. The friction coefficient of the 1:2 to 4 scale skin is much smaller than that of the traditional wave channel. Due to its gentle structure, the 1:2 to 4 scale wave channel has lower flow resistance and pressure loss, resulting in the best drainage performance and mass transfer efficiency. According to simulation results, the pressure difference of the 1:2 to 4 scale wave channel is smaller than that of the traditional wave channel, improving oxygen distribution and transport by 9.57%, and the impact of gas disturbance is smaller. Finally, the dynamic transport capacity of liquid water was further studied using the VOF model, especially the 1:2 to 4 scale wave channel. Due to its structural advantages, it is more conducive to the discharge of liquid water at the gentle wave interface after local acceleration.

Claims

1. A regenerative fuel cell, characterized by: It includes an oxygen electrode flow field plate (1), an oxygen electrode diffusion layer (2), a membrane electrode (3), a hydrogen electrode diffusion layer (4), and a hydrogen electrode flow field plate (5) that are stacked in sequence. The oxygen electrode flow field plate (1) and the hydrogen electrode flow field plate (5) are arranged symmetrically along the membrane electrode (3). The oxygen electrode flow field plate (1) includes a base plate (6), and a middle mounting cavity, a front inlet cavity and a rear outlet cavity are provided on the base plate (6). The middle mounting cavity is connected to the front inlet cavity and the rear outlet cavity respectively. The middle mounting cavity of the base plate (6) is arranged with several rows of corrugated plates (7) evenly spaced from top to bottom to form a flow field reaction zone (10). The front inlet cavity, located in front of the flow field reaction zone (10), is arranged with several rows of inlet fluid distribution units evenly spaced from top to bottom to form a fluid distribution inlet zone (11). The rear outlet cavity, located behind the flow field reaction zone (10), is arranged with several rows of outlet fluid distribution units evenly spaced from top to bottom to form a fluid distribution outlet zone (12). The bottom front end of the base plate (6) has several air inlets connected to the fluid distribution inlet area (11) on the inner wall of the pipe hole, and the bottom rear end of the base plate (6) has several air outlets (17) connected to the fluid distribution outlet area (12) on the inner wall of the pipe hole. Each of the wave-shaped plates includes n curved plates (13), and the curved surfaces of each two adjacent curved plates (13) are arranged in opposite directions; each curved plate (13) includes a first arc plate (14) and a second arc plate (15), the center of the first arc plate (14) is concentric with the center of the second arc plate (15), and the ratio of the arc of the first arc plate (14) to the arc of the second arc plate (15) is 1:2~4.

2. The regenerative fuel cell of claim 1, wherein: The top and bottom surfaces of the central mounting cavity are both formed with wavy curved surfaces (8) that are the same shape as the corrugated plate (7). Fluid reaction channels (9) are formed between the wavy curved surface (8) on the upper edge and the corrugated plate (7), between each two adjacent corrugated plates (7), and between the wavy curved surface (8) on the lower edge and the corrugated plate (7).

3. The regenerative fuel cell of claim 1, wherein: In the cross section of each of the curved plates (13): the horizontal line connecting the end of the first curved plate (14) and the end of the second curved plate (15) is flush with the horizontal line; the angle between the line connecting the end of the first curved plate (14) and the intersection of the first curved plate (14) and the second curved plate (15) and the horizontal line is α; the angle between the line connecting the end of the second curved plate (15) and the intersection of the first curved plate (14) and the second curved plate (15) and the horizontal line is β; and the angle α is consistent with the outlet direction of the air inlet.

4. The renewable fuel cell according to claim 3, characterized in that: The α value is 0°~15°, and the β value is 0°~0.08°.

5. The renewable fuel cell according to claim 1, characterized in that: Each row of the inlet fluid distribution unit includes at least one inclined boss (16). The gap between each two adjacent inclined bosses (16) in each row of the inlet fluid distribution unit is the same as the gap between each two adjacent rows of the inlet fluid distribution unit, forming an inclined fluid inlet main distribution channel and a horizontal fluid inlet secondary distribution channel. The structure of each row of the outlet fluid distribution unit is the same as that of the inlet fluid distribution unit.

6. The renewable fuel cell according to claim 5, characterized in that: The outlet direction of each air inlet is the same as the direction of the main distribution channel of the fluid inlet; the inlet direction of each air outlet (17) is the same as the direction of the main distribution channel of the fluid outlet.

7. The renewable fuel cell according to claim 1, characterized in that: The length of each curved plate (13) is 6~10mm, and the rib width of each curved plate (13) and the width of the fluid reaction channel (9) are equal to 1~3mm.

8. The renewable fuel cell according to claim 1, characterized in that: The inlet fluid distribution unit of the fluid distribution inlet area rotates 180 degrees around the vertical symmetry center line of the flow field reaction zone and then coincides with the outlet fluid distribution unit of the fluid distribution outlet area.

9. The renewable fuel cell according to claim 5, characterized in that: The base plate (6) is provided with sealing grooves around its perimeter and is sealed with silicone rubber sealing rings.

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