Flow channel inlet and outlet edge length ratio controllable bipolar plate

Abstract

The application discloses a bipolar plate with controllable length ratio of inlet and outlet of flow channel, comprising a bipolar plate and a plurality of connecting rod devices, the bipolar plate is provided with a bipolar plate inlet, a bipolar plate outlet and a plurality of flow channels, a rotating rib is arranged at the inlet or outlet of each flow channel, a film capable of shielding the inlet or outlet of the flow channel is connected to the rotating rib, and the connecting rod devices are connected with the rotating rib and capable of driving the rotating rib to rotate. The application satisfies the regulation and control of the length ratio of inlet and outlet of the flow channel of the bipolar plate, improves the drainage, mass transfer and heat dissipation performance of the bipolar plate, so that the fuel cell can work under the optimal performance, and the larger length ratio of inlet and outlet can greatly enhance the water removal capacity of the bipolar plate under the premise of no shutdown, prevent the water flooding phenomenon of the bipolar plate, and thus affect the safety, working efficiency of the fuel cell and increase the energy consumption.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of bipolar plate structure, and particularly relates to a bipolar plate with controllable length ratio of inlet and outlet of flow channel. BACKGROUND

[0002] Energy production and consumption are closely related to global warming and greenhouse effect. The greenhouse gas emissions caused by the current global energy system account for more than 50% of the total emissions. Hydrogen energy is clean and environmentally friendly, which helps to reduce carbon emissions; hydrogen energy has high combustion heat value and can release a large amount of chemical energy; hydrogen energy is a non-natural energy and widely exists in nature, and even can be obtained in many industrial and chemical processes, and the energy reserves are abundant. Hydrogen energy has a wide range of uses, one of which is as a fuel for proton exchange membrane fuel cells. The proton exchange membrane fuel cell has the advantages of high energy conversion efficiency, low pollutant emission, fast start-stop response, low noise, etc., and is one of the most promising environmentally friendly and efficient power generation technologies. Fuel cells can convert the chemical energy in fuel (hydrogen) and oxidant (air or oxygen) into usable electrical energy through internal electrochemical reactions, and the reaction product is only water. The chemical reaction in the fuel cell is not limited by the Carnot cycle, and the energy conversion efficiency can reach more than 60%, which is much higher than that of an internal combustion engine. However, the water removal and mass transfer uniformity of the fuel cell have always been a challenging problem, which affects the overall performance of the cell.

[0003] The bipolar plate is an important component of the proton exchange membrane fuel cell, which not only separates the fuel and the oxidant to prevent gas mixing, but also conducts current and reaction heat. If the reaction heat is not discharged in time, the operating temperature of the stack cannot be maintained within a suitable range, thereby affecting the durability and operating performance of the cell. The reaction gas and the water generated by the reaction flow through the flow channel structure on the bipolar plate, which determines the uniformity of the distribution of the reaction gas and the ability to discharge the water generated by the reaction. If the mass transfer capacity of the flow channel is poor, fuel starvation will occur, which will affect the service life of the fuel cell and increase the amount of heat generated, thereby affecting the stability and safety of the cell. If the water removal capacity of the flow channel is poor, water flooding will occur, which will increase the transmission loss of the reactants, reduce the current density, and affect the operating efficiency of the cell. In addition, when water flooding occurs, the gas tends to flow through the path with the smallest resistance, and a large amount of liquid water exists in the flow channel at the bottom, which increases the flow resistance, so the gas is not easy to flow through, and the water removal effect is worse. At this time, the stack needs to be stopped and purged for a long time to achieve water removal, which not only has low efficiency, but also increases the energy consumption of the cell system and reduces the economy.

[0004] In addition, the existing bipolar plate flow channel shapes, such as parallel flow channels, serpentine flow channels, interdigital flow channels, bionic flow channels, and three-dimensional grid flow channels, have advantages and disadvantages, but the biggest disadvantage is that the flow channel structure is fixed. Since the flow channel structure plays an important role in the mass transfer capacity, water removal capacity, and gas distribution uniformity of the bipolar plate, it is closely related to the performance of the proton exchange membrane fuel cell. If the flow channel structure is fixed and cannot be changed according to the actual use, it will be difficult to run the fuel cell at optimal performance under different working conditions. In addition, the bipolar plates currently used in practical applications and the existing patents have a 1:1 inlet and outlet edge length ratio of the bipolar plate flow channel, and at most there is an example of changing the inlet and outlet manifold area ratio of the bipolar plate. For example, the Chinese utility model patent with the authorization announcement number CN217182209U applies a fuel cell bipolar plate inlet and outlet structure, which designs the cross-sectional area of the gas inlet manifold to be smaller than that of the gas outlet manifold, thereby reducing the pressure drop at the cathode plate manifold, solving the problem of water discharge difficulty during the startup operation of the fuel cell, improving the water flooding phenomenon, and improving the stability of the stack operation. The Chinese invention patent with the publication number CN114784312A applies a flow uniformity bipolar plate for fuel cells, which selects bipolar plates with different flow channel cross-sectional areas at the hydrogen, air, and cooling liquid inlets of the fuel cell, and the flow channel cross-sectional area of the selected bipolar plate at the hydrogen, air, and cooling liquid inlets is smaller than that at the hydrogen, air, and cooling liquid outlets, thereby balancing the flow and pressure of the flow channels of multiple bipolar plates, reducing the pressure requirement at the inlet, and improving the performance and reliability of the fuel cell. Some scholars have conducted simulation research on bipolar plates with different inlet and outlet edge length ratios and found that under the same working conditions, when the inlet and outlet edge length ratio is set to 0.6:1, 0.8:1, 1:1, 1:1.2, and 1:1.4, the increase in the inlet and outlet edge length ratio is beneficial to the output voltage and power density of the fuel cell. The reason is that the contact area between the bipolar plate and the gas diffusion layer decreases, which increases the contact area between the channel and the gas diffusion layer, thereby promoting the effective transport path of the reactants from the channel to the gas diffusion layer, improving the transport of the reactants; it is beneficial to improve the oxygen molar concentration in the downstream gas diffusion layer and catalyst layer of the cathode flow channel, which is due to the increase in the contact area between the flow channel and the gas diffusion layer, thereby promoting the transport of oxygen from the flow channel to the gas diffusion layer; the membrane water content in the cathode catalyst layer is low, which is because a reasonable and high inlet and outlet edge length ratio has good water removal capacity, which can reduce the excess liquid water saturation and maintain sufficient membrane water content in the cathode catalyst layer; the pressure drop of the cathode channel decreases, which is beneficial to reduce the pump work of delivering reactants to the fuel cell, which is beneficial to the energy efficiency of the fuel cell. SUMMARY

[0005] In order to solve the problem that the traditional bipolar plate flow channel structure cannot be adjusted, so as to meet the demand of actual use conditions such as environment, load and the like, the present application provides a bipolar plate with controllable inlet and outlet edge length ratio of flow channel, which can change the flow channel structure according to actual working conditions to achieve the best performance, improve the drainage, mass transfer and heat dissipation performance of the bipolar plate, and meet the demand of variable working condition experiment research of the fuel cell. In addition, considering the water flooding phenomenon of the bipolar plate, it is often necessary to stop the machine and blow the stack for a long time to achieve the purpose of water removal, which not only has low efficiency, but also increases the energy consumption of the fuel cell system and reduces the economy. The present application can achieve the purpose of increasing the edge length ratio by adjusting the edge length ratio, so as to avoid the energy loss caused by stopping the machine and the working medium loss caused by high flow rate blowing.

[0006] The technical scheme adopted by the present application to solve the technical problem is: a bipolar plate with controllable inlet and outlet edge length ratio of flow channel, comprising a bipolar plate and a plurality of connecting rod devices, the bipolar plate is provided with a bipolar plate inlet, a bipolar plate outlet and a plurality of flow channels, the inlet or outlet of each flow channel is provided with a rotating rib, the rotating rib is connected with a film which can shield the inlet or outlet of the flow channel, the film is used to block the space between the adjacent rotating rib and the original rib of the bipolar plate flow channel, so as to destroy the inlet and outlet edge length ratio of the bipolar plate flow channel; the connecting rod device is connected with and can drive the rotating rib to rotate respectively, so as to achieve the purpose of controllable inlet and outlet edge length ratio of flow channel.

[0007] Further, the connecting rod device comprises a connecting rod, a filling bolt, a ball, a double rod group, a spur gear and a rack, the rack is connected with the spur gear in meshing, one end of the filling bolt is connected with the rotating rib, the other end is connected with the spur gear, the ball is arranged at one end of the connecting rod, the ball is connected with the rack through the double rod group to form a crank rocker mechanism which can drive the rack to slide, by rotating the connecting rod, the ball at one end of the connecting rod rolls to exert a downward pulling force on the double rod group, so that the rack slides in the groove, the spur gear is engaged with the rack, since the filling bolt and the spur gear have the same center axis, the filling bolt rotates with the spur gear, so as to drive the rotating rib to swing, so as to achieve the purpose of controllable inlet and outlet edge length ratio of flow channel.

[0008] Further, the filling bolt is connected at the midpoint of the rotating rib.

[0009] Further, the bottom of the bipolar plate is provided with a connecting rod groove for mounting the connecting rod. The connecting rod grooves are staggered arranged at the bottom of the bipolar plate to avoid the problem that the gear shifter is inconvenient to distinguish.

[0010] Further, the bipolar plate is further provided with a sliding groove for allowing the rack to slide.

[0011] Further, the gear shifter is further provided with a plurality of gear slots corresponding to the rotation angle of the connecting rod, and the finger ring buckle is provided with a clamping block capable of being clamped into the gear slot, and each finger ring buckle is connected to the other end of the connecting rod through a spring, so that the gear slots and the finger ring buckle of the gear shifter are used to realize the selection and fixation of the preset length ratio of the inlet and outlet of the flow channel of the bipolar plate.

[0012] Further, the shape of the shell and the finger ring buckle is a hand-shaped imitation type that matches the hand, which enhances the comfort when the spring is adjusted.

[0013] The beneficial effects of the present application are:

[0014] (1) The present application designs a bipolar plate structure with variable length ratio of inlet and outlet of flow channel, which solves the problem that the traditional bipolar plate structure cannot change the flow channel structure after being processed;

[0015] (2) The present application uses the linkage of gear set and double rod set to support the variable structure of the flow channel of the bipolar plate, realizes the transmission of the torsion from the horizontal direction to the vertical direction, and solves the problem that the internal structure of the bipolar plate is fine and difficult to be accurately adjusted by external force;

[0016] (3) The present application uses the combination of the finger ring buckle and the gear slot of the gear shifter, can obtain the gear shifter with the expected length ratio range by setting different rotation angles of the gear slot, and can obtain the expected length ratio by selecting different gear slots of the gear shifter, and at the same time, the double rod set has a limit stretching range, which can prevent the flow channel from being blocked due to too large or too small length ratio, and realizes the controllable length ratio of the inlet and outlet of the flow channel of the bipolar plate.

[0017] (4) The present application uses the gear clamping type gear shifter, which is matched with the spring, uses the elastic deformation force of the spring to keep the original state, so that the device can realize the variable and controllable length ratio of the inlet and outlet of the flow channel without power supply, the design of the pure mechanical structure avoids the influence of the circuit on the working state of the fuel cell itself and the increase of the additional energy consumption, and at the same time, if different interval and range of length ratio is needed, the gear shifter can be replaced to realize the maintenance and improvement;

[0018] (5) The inlet and outlet length ratio controllable flow channel structure designed by the present application not only provides a way for the fuel cell to run at the best performance under different working conditions, but also can be used for water removal in the flow channel, solves the difficulty that the traditional bipolar plate needs to be stopped and blown for a long time to achieve water removal when water flooding occurs, improves the working efficiency, reduces the energy consumption of the fuel cell system, and increases the economy. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a schematic diagram of the overall structure of the present application.

[0020] Figure 2 is the bipolar plate front view of the present application.

[0021] Figure 3a and Figure 3b is the bipolar plate inside view of the present application.

[0022] Figure 4 is the schematic diagram of the connecting rod structure of the present application.

[0023] Figure 5 is the schematic diagram of the connecting rod and filling bolt connection of the present application.

[0024] Figure 6 is the front view of the connecting rod and filling bolt connection of the present application.

[0025] Figure 7 is the detail view of the connecting rod and filling bolt connection of the present application.

[0026] Figure 8 is the internal schematic diagram of the straight rack base of the present application

[0027] Figure 9 is the front view of the shifter of the present application.

[0028] Figure 10 is the sectional view of the shifter of the present application.

[0029] Figure 11 is the schematic diagram of the finger ring buckle of the present application.

[0030] Figure: 1-bipolar plate, 2-connecting rod device, 3-shifter, 11-bipolar plate inlet, 12-bipolar plate outlet, 13-thin film, 14-rotating rib, 15-connecting rod groove, 16-bolt groove, 21-spring, 22-connecting rod, 23-filling bolt, 24-rolling ball, 25-double rod group, 26-spur gear, 27-rack, 28-sliding slot, 29-rack base, 31-gear slot, 32-outer shell, 33-finger ring buckle. DETAILED DESCRIPTION

[0031] The present application will be further described below with reference to the drawings. It is to be noted that these specific embodiments are merely representative of the present application, and the specific methods, devices, conditions, materials, etc. shown are not intended to limit the present application or the corresponding embodiments. Therefore, the devices in the drawings are only used to express their relative positions and are not drawn according to their actual proportions.

[0032] A bipolar plate with controllable flow channel inlet and outlet side length ratio, such as Figures 1-11As shown, including bipolar plate 1, a number of connecting rod device 2 and a number of gear 3, the embodiment of the present application provides 1 connecting rod device 2 and gear 3, in fact, can be set 9, the remaining 9 connecting rod device 2 and gear 3 structure with the same structure of the present embodiment, in actual operation does not necessarily have to use all, can be according to the actual working condition and the user's own needs to operate change bipolar plate flow channel structure, meet the demand of higher accuracy. The bipolar plate 1 is provided with bipolar plate inlet 11, bipolar plate outlet 12 and a plurality of flow channels, the inlet or outlet of each flow channel is provided with rotating rib 14, the rotating rib 14 is connected with the film 13 which can shield the inlet or outlet of the flow channel, rotating rib 14 and film 13 is a combination, such as Figure 3bThe arrow indicates the direction of the flow channel, and the ellipse indicates that the rotating rib 14 and the original rib form a whole through the film 13. The purpose of the film 13 is to prevent the working medium from flowing into the space between the two adjacent rotating ribs 14 and the original rib. If the film 13 is not added, the length ratio between the rotating rib and the original rib will be opposite to the expected ratio, and the internal flow channel will form a ladder-shaped space alternately, which cannot achieve the purpose of controlling the length ratio. The connecting rod device 2 includes a connecting rod 22, a filling bolt 23, a ball 24, a double rod group 25, a spur gear 26, and a rack 27. The rack 27 is connected with the spur gear 26. One end of the filling bolt 23 is connected with the rotating rib 14, and the other end of the filling bolt 23 is connected with the spur gear 26. The ball 24 is arranged at one end of the connecting rod 22. The ball 24 is connected with the rack 27 through the double rod group 25, and forms a crank rocker mechanism that can drive the rack to slide. The gear shifter 3 includes a shell 32 and a ring buckle 33. The shell 32 is provided with a plurality of gear grooves 31 matched with the rotating angle of the connecting rod 22. The ring buckle 33 is provided with a clamping block that can be clamped into the gear groove 31. The ring buckle is connected with the other end of the connecting rod 22 through the spring 21. When there is a specific requirement for the length ratio of the inlet and outlet of the bipolar plate flow channel, the ring buckle 33 overcomes the tension of the spring 21, pulls out the shell 32 from the gear groove 31, and then rotates the connecting rod 22 to the appropriate angle, and then inserts the ring buckle 33 into the appropriate gear groove 31. Due to the tension of the spring 21, the ring buckle 33 is fixed again. The rotation of the ring buckle 33 applies a torsion to the connecting rod 22. The connecting rod 22 transmits the torsion to the ball 24 at the top of the connecting rod 22 through the connecting rod groove 15 at the bottom of the bipolar plate 1. The rotation of the ball 24 causes the double rod group 25 to be stretched. The ball 24 rotates with the connecting rod 22, and the spherical shape is more suitable for uniform force transmission, which can realize the conversion of horizontal and vertical forces, and then moves the rack 27 with the rack base 29 in the sliding groove 28 added to the bipolar plate 1. The sliding groove 28 is arranged in the interlayer of the bipolar plate 1. The interlayer is used for the movement of the rack base 29 in the sliding groove 28. Only an opening with a size matched with the handle of the rack 27 is provided at the bottom of the bipolar plate 1 to achieve the fixation in the up-down direction, so that the rack 27 can only support the left-right direction sliding. The rack 27 is engaged with the spur gear 26 during the dragging process. Since the spur gear 26 and the filling bolt 23 have the same center axis, the filling bolt 23 is driven to rotate. The filling bolt 23 is engaged with the groove at the center of the rotating rib 14, so that the filling bolt 23 acts as the fulcrum of the rotating rib 14. The rotating rib rotates with the filling bolt 23, thereby realizing the function of changing the length ratio of the inlet and outlet of the flow channel. The rotating rib 14 is connected with the nearby bipolar plate flow channel through the film 13 to prevent the working medium in the flow channel from flowing through, thereby destroying the structure of the preset inlet and outlet length ratio and affecting the operation performance of the fuel cell.

[0033] Further, the bipolar plate 1 is provided with a bolt groove 16 for mounting the filling bolt 23.

[0034] Further, the connecting rod grooves 15 are staggered on the bottom of the bipolar plate 1 to avoid the problem that the gear shifter 3 cannot distinguish.

[0035] Further, the shell 32 and the ring buckle 33 are shaped like a hand to enhance the comfort when the spring 21 adjusts the gear.

[0036] The present application is mainly used for improving the mass transfer capacity and water removal capacity of the bipolar plate, which are closely related to the performance of the proton exchange membrane fuel cell. The mass transfer capacity and water removal capacity of the bipolar plate are determined by the flow channel structure, and the traditional bipolar plate flow channel structure cannot be adjusted, so it cannot meet the needs of actual use conditions such as environmental changes, load changes, etc. The present application realizes the fixation and switching of gears through the linkage of springs, ring buckles and gear shifters, realizes the rotation on two different center axes through the meshing of spur gears and racks and the sliding of racks and grooves, and meets the regulation and control of the inlet and outlet side length ratio of the bipolar plate flow channel. The present application improves the drainage, mass transfer and heat dissipation performance of the bipolar plate, so that the fuel cell can work at the best performance. A larger inlet and outlet side length ratio can greatly enhance the water removal capacity of the bipolar plate without stopping the machine, prevent the bipolar plate from being flooded, and thus affect the safety, working efficiency and energy consumption of the fuel cell.

[0037] The present application uses a gear shifting device, and if different intervals and ranges of side length ratios are needed, the gear shifter can be replaced to achieve this, for example: if the gear shifter is replaced by one gear larger, the rack set can be pulled by one gear, the filling bolt drives the rotating rib to rotate, and the inlet and outlet side length ratio changes from 1:1 to 1.2:1. If the gear shifter is replaced by two gears larger, the rack set can be pulled by two gears, the filling bolt drives the rotating rib to rotate, and the inlet and outlet side length ratio changes from 1:1 to 1.4:1, and so on. In summary, the present application can adjust and control the flow channel structure of the bipolar plate, and can be changed according to actual needs to ensure the performance and efficiency of the fuel cell.

[0038] The above is only a preferred embodiment of the present application, and cannot limit the scope of the present application. Any simple equivalent changes and modifications made according to the scope of the present application and the content of the present application are still within the scope of the present application.

Claims

1. A bipolar plate with controllable flow channel inlet and outlet edge length ratio, characterized in that, The application relates to a bipolar plate and a plurality of connecting rod devices, the bipolar plate is provided with a bipolar plate inlet, a bipolar plate outlet and a plurality of flow channels, a rotating rib is arranged at the inlet or outlet of each flow channel, a film capable of shielding the inlet or outlet of the flow channel is connected to each rotating rib, the connecting rod device is connected to and capable of driving the rotating rib to rotate; the rotating rib and the original rib on the bipolar plate flow channel are integrated through the film.

2. The bipolar plate of claim 1, wherein, The connecting rod device comprises a connecting rod, a filling bolt, a ball, a double-rod group, a spur gear and a rack, the rack is in meshing connection with the spur gear, one end of the filling bolt is connected with the rotating rib, the other end of the filling bolt is connected with the spur gear, the ball is arranged at one end of the connecting rod, the ball is connected with the rack through the double-rod group and forms a crank rocker mechanism capable of driving the rack to slide.

3. The bipolar plate of claim 2, wherein the length ratio of the inlet and outlet of the flow channel is controllable. The bottom of the bipolar plate is provided with a connecting rod groove for mounting the connecting rod.

4. The bipolar plate of claim 3, wherein the length ratio of the inlet and outlet of the flow channel is controllable. The connecting rod grooves are staggered arranged at the bottom of the bipolar plate.

5. The bipolar plate of claim 2, wherein the length ratio of the inlet and outlet of the flow channel is controllable. The bipolar plate is provided with a sliding groove for allowing the rack to slide.

6. The bipolar plate of claim 2, wherein the length ratio of the inlet and outlet of the flow channel is controllable. The filling bolt is connected with the midpoint of the rotating rib.

7. The bipolar plate of any one of claims 2-6, wherein the length of the inlet and outlet of the flow channel is controllable. The application further comprises a plurality of shifters, each shifter comprises a shell and a finger ring buckle, the shell is provided with a plurality of gear slot matched with the rotating angle of the connecting rod, the finger ring buckle is provided with a clamping block capable of being clamped into the gear slot, and each finger ring buckle is connected with the other end of the connecting rod through a spring.

8. The bipolar plate of claim 7, wherein the length of the inlet and outlet of the flow channel is controllable. The shell and the finger ring buckle are in the shape of imitation hands matched with hands.

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