CN114267848B - Fuel cell bipolar plate of bionic multistage bifurcation flow field and implementation method thereof - Google Patents
Fuel cell bipolar plate of bionic multistage bifurcation flow field and implementation method thereof Download PDFInfo
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
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Abstract
The invention discloses a fuel cell bipolar plate of a bionic multistage bifurcation flow field and an implementation method thereof. The distribution flow channels and the collection flow channels are adopted to respectively reduce the width and the length of the flow channels in the gas transmission direction in a gradient manner and increase the width and the length of the flow channels in a gradient manner, so that the reaction gas is directionally transmitted, the mass transfer efficiency of the bionic multi-stage bifurcation flow field is improved, the reaction gas is promoted to be uniformly distributed, meanwhile, the phenomenon of blockage of the collection flow channels which are close to the oversized mass transfer task of the outlet is avoided, and the product water is discharged in a gradient manner in time; two-stage flow channel units with two symmetrical sides are distributed between the distribution flow channel and the collection flow channel, so that the pressure drop and pumping power of the fuel cell are obviously reduced, and water generated by the reaction is rapidly discharged; meanwhile, the unreacted gas is circularly transmitted and utilized for a plurality of times, so that the utilization rate of the reaction gas is improved; the invention reduces pressure drop and pumping power, improves mass transfer efficiency, improves water management of the fuel cell, and finally improves performance and stability of the fuel cell.
Description
Technical Field
The invention relates to a fuel cell technology, in particular to a fuel cell bipolar plate of a bionic multistage bifurcation flow field and an implementation method thereof.
Background
The proton exchange membrane fuel cell is an energy conversion device which directly converts chemical energy into electric energy, and the working principle is as follows: the bipolar plates transport the reactant gases hydrogen and oxygen into the cell so that the gases are distributed on the gas diffusion layer and transported to the reaction sites of the catalytic layer by diffusion or convection. The hydrogen at the anode side generates electrons and hydrogen protons under the action of the catalyst, the electron load of the external circuit conveys the electrons to the cathode, and the hydrogen protons are conveyed to the cathode through the proton exchange membrane. Oxygen molecules, hydrogen protons and electrons on the cathode side produce water and heat under the action of the catalyst, while generating electrical energy. The method has the advantages of low-temperature operation, zero emission, low noise, high reliability, quick start and the like, and has wide application prospect in the fields of new energy automobiles, unmanned aerial vehicles, ships, military and the like.
The bipolar plate is used as a key component of the fuel cell, has the functions of supporting the cell, blocking the reaction gas of the anode and the cathode, collecting current and the like, and the flow field structure on the bipolar plate directly determines the distribution condition of reactants and products so as to influence the electrochemical reaction rate. The traditional parallel flow field has the advantages of simple processing, low manufacturing cost, low working pressure and wide application, but has the performance problems of uneven reactant distribution, flooding and the like. The traditional serpentine flow field has good drainage performance and relatively simple manufacture, but has the performance problems of uneven current density distribution, overlarge pressure drop and the like along the flowing direction. The traditional interdigital flow field can greatly improve the concentration of reactants of a diffusion layer and rapidly discharge water generated by reaction, but the closed flow channel leads the pressure drop of the flow field to be overlarge, and directly influences the output power and the service life of the battery. Therefore, bipolar plate flow field configurations are required to ensure uniform distribution and distribution of reactants, rapid drainage of reaction product water, and reduced pressure drop.
Disclosure of Invention
Aiming at the problems existing in the prior art, the invention provides a fuel cell bipolar plate of a bionic multi-stage bifurcation flow field and a realization method thereof, wherein the bionic multi-stage bifurcation flow field is designed by utilizing a multi-stage proportion structure of a natural circulation and conveying system (such as animal blood vessels, plant veins and the like), reactants are distributed more uniformly by changing a gas flow path and a conveying mode, pressure drop is reduced, reaction product water is discharged rapidly, mass transfer and water management efficiency in a cell is improved, uniform distribution of current density is ensured, and thus the overall performance of the cell is improved.
The fuel cell includes: bipolar plate, gas diffusion layer, catalytic layer and proton exchange membrane; the proton exchange membrane is positioned in the center, and two sides of the proton exchange membrane are respectively provided with a cathode catalytic layer, an anode catalytic layer, a cathode gas diffusion layer, an anode gas diffusion layer and a cathode bipolar plate and an anode bipolar plate which are symmetrically distributed from inside to outside.
An object of the present invention is to provide a fuel cell bipolar plate of a bionic multi-stage bifurcated flow field.
The fuel cell bipolar plate of the bionic multi-stage bifurcation flow field comprises: the bipolar plate comprises a bipolar plate main body, an inlet, a middle distribution runner, an upper left distribution runner, an upper right distribution runner, a left collecting runner, a right collecting runner, a lower left collecting runner, a lower right collecting runner, a runner unit network, a left outlet and a right outlet; the bipolar plate main body is a plane plate, an inlet is engraved at the center of the top of the front surface of the bipolar plate main body, a middle distribution runner communicated with the inlet is engraved at the center of the front surface of the bipolar plate main body along the vertical direction, the middle distribution runner is divided into N grades along the air flow transmission direction, the length and the width of each grade are reduced in a gradient manner along the air flow transmission direction, and N is a natural number more than or equal to 4; the top of the front surface of the bipolar plate main body is carved with an upper left distribution runner and an upper right distribution runner which are communicated with the inlet and are respectively positioned at two sides of the inlet along the horizontal direction, the upper left distribution runner and the upper right distribution runner are symmetrically distributed about a vertical central line, the upper left distribution runner and the upper right distribution runner are divided into M grades along the air flow transmission direction, the length and the width of each grade are reduced in a gradient way along the air flow transmission direction, and M is a natural number which is more than or equal to 2; the two sides of the front surface of the bipolar plate main body are respectively carved with a left collecting runner and a right collecting runner along the vertical direction, the left collecting runner and the right collecting runner are symmetrically distributed about a vertical central line, the left collecting runner and the right collecting runner are uniformly divided into N grades along the airflow transmission direction and the middle distribution runner, and the length and the width of each grade are increased in a gradient manner along the airflow transmission direction; the bottom of the front surface of the bipolar plate is carved with a left lower collecting runner and a right lower collecting runner which are communicated with the middle distributing runner and are respectively positioned at two sides of the middle distributing runner along the horizontal direction, the left lower collecting runner and the right lower collecting runner are symmetrically distributed about a vertical central line and are respectively communicated with a left collecting runner and a right collecting runner, the left lower collecting runner and the right lower collecting runner are divided into K grades along the airflow transmission direction, the length and the width of each grade are increased in a gradient way along the airflow transmission direction, and K is a natural number which is more than or equal to 3; the collecting part of the left collecting flow channel and the left lower collecting flow channel and the collecting part of the right collecting flow channel and the right lower collecting flow channel are respectively carved with a left outlet and a right outlet, and the left outlet and the right outlet are symmetrically distributed about a vertical central line;
The middle distribution runner, the upper left distribution runner and the upper right distribution runner are collectively called a distribution runner, and the left collecting runner, the right collecting runner, the lower left collecting runner and the lower right collecting runner are collectively called a collecting runner; a communicating runner unit net is carved in the area enclosed between the distribution runner and the collection runner; the flow channel unit networks are distributed according to self-similarity and affine rules, so that the flow channel unit networks, the distribution flow channels and the collection flow channels form a bionic multi-stage bifurcation flow field; the gateway of the flow channel unit is symmetrically distributed on the vertical central line, and the network of the flow channel unit comprises a primary flow channel unit and a secondary flow channel unit; wherein, the liquid crystal display device comprises a liquid crystal display device,
the primary runner unit comprises a primary parent runner, a primary horizontal sub runner and a primary vertical sub runner; a plurality of parallel primary father runners are carved between the distribution runner and the collection runner, namely, between the upper left distribution runner and the collection runner, between the middle distribution runner and the collection runner, between the upper right distribution runner and the collection runner, between the middle distribution runner and the collection runner, and between the middle distribution runner and the collection runner, the primary father runners and the collection runner have acute angles with the vertical center line, and the distances between the adjacent primary father runners are equal; a plurality of first-level horizontal sub-channels which are communicated with the first-level father channel and along the horizontal direction are carved on the upper edge of each first-level father channel, and the distances between the adjacent first-level horizontal sub-channels are equal; a plurality of first-stage vertical sub-channels which are communicated with the first-stage father channel along the vertical direction are carved on the lower edge of each first-stage father channel, and the distances between the adjacent first-stage vertical sub-channels are equal;
The secondary runner unit comprises a secondary father runner, a secondary horizontal sub runner and a secondary vertical sub runner; the tail end of the first-level horizontal sub-runner of the first-level vertical sub-runner is communicated with a second-level father runner, and the tail end of the first-level horizontal sub-runner of the first-level father runner positioned between the left upper distribution runner and the left collecting runner and between the right upper distribution runner and the right collecting runner is communicated with the second-level father runner, and the second-level father runner is parallel to the first-level father runner; the tail ends of the secondary father runners are respectively communicated with a secondary horizontal sub runner and a secondary vertical sub runner; the secondary horizontal sub-flow passage is along the horizontal direction, and the secondary vertical sub-flow passage is along the vertical direction; the tail end of the secondary horizontal sub-runner is communicated with the next primary vertical sub-runner along the air flow transmission direction, and the tail end of the secondary vertical sub-runner is communicated with the next primary father runner along the air flow transmission direction; the tail end of the first-stage horizontal sub-runner is communicated with the next second-stage vertical sub-runner along the air flow transmission direction;
the tail ends of the first-level horizontal sub-runner, the first-level vertical sub-runner, the second-level father runner, the second-level horizontal sub-runner and the second-level vertical sub-runner along the air flow transmission direction are communicated with the corresponding left collecting runner, right collecting runner, left lower collecting runner or right lower collecting runner; the son runner and father runner of each level runner unit are of a bifurcation structure, and a runner unit network formed by two levels of runner units is of a multi-level bifurcation structure;
When the fuel cell works, reaction gas enters from an inlet, and is transmitted to a flow channel unit network through an upper left distribution flow channel, an upper right distribution flow channel and a middle distribution flow channel, and the lengths and widths of the upper left distribution flow channel, the upper right distribution flow channel and the middle distribution flow channel in the gas transmission direction are reduced in a gradient manner, so that the widths of the flow channels are changed through the gradient, the sectional areas of the flow channels are changed, the reaction gas with the same flow rate is transmitted, the distribution flow channels far away from the inlet position can be ensured to obtain a larger reaction gas flow rate, the mass transfer efficiency of the bionic multi-stage bifurcation flow field is improved while the reaction gas is directionally transmitted, and the reaction gas of each different-stage flow channel unit connected with each different stage of the distribution flow channel can enter the whole bionic multi-stage bifurcation flow field at the same flow rate, so that the reaction gas is promoted to be uniformly distributed, the reaction gas is enabled to uniformly and rapidly enter a catalytic layer to perform electrochemical reaction, and the electrochemical reaction generates product water; the reaction gas transmitted from the distribution runner to the runner unit network firstly enters a primary parent runner, the primary parent runner is communicated with the distribution runner and the collection runner, the reaction gas and the generated water are directly transmitted to the collection runner by utilizing the through direct structural characteristic of the primary parent runner, and the first gradient directional transmission is carried out, so that the transmission path of the bionic multi-stage bifurcation flow field from an inlet to an outlet is shortened, the pressure drop and the pumping power of the fuel cell are obviously reduced, and the generated water is rapidly discharged; the first-stage horizontal and vertical sub-flow channels are equidistantly distributed on the first-stage parent flow channel, and the component force of the reaction gas in the horizontal and vertical directions is utilized to transmit the reaction gas and the product water to the collecting flow channel for carrying out second gradient directional transmission; the tail end of each first-stage vertical sub-runner is an inlet of a second-stage runner unit, unreacted gas of the first-stage horizontal sub-runner and the first-stage vertical sub-runner enters a second-stage father runner again, and third gradient directional transmission is carried out on the reactant gas and the product water transmitted by the first-stage vertical sub-runner in the vertical direction; the second-stage vertical sub-flow passage and the second-stage horizontal sub-flow passage are respectively positioned in the vertical direction and the horizontal direction, and the component force of the reaction gas in the horizontal direction and the vertical direction is utilized again to transmit the reaction gas and the product water so as to perform fourth gradient directional transmission; the secondary horizontal sub-runner and the secondary vertical sub-runner of the secondary runner unit are connected back to the primary runner unit, and finally, the reaction gas and the product water are transmitted to the collecting runner in a multi-directional guiding and circulating mode; meanwhile, unreacted gas is circularly transmitted and utilized for multiple times, so that no place where the reactant gas does not reach exists in the bionic multi-stage bifurcation flow field, and the utilization rate of the reactant gas of the fuel cell is improved; the multi-stage bifurcation structure of the flow passage unit net can be used for draining product water to the collecting flow passage in a gradient and directional way, the drainage mechanism of the structure obviously improves the drainage efficiency of the fuel cell, and finally improves the performance and the stability of the fuel cell; the length and the width of the collecting flow channels in the gas transmission direction are increased in a gradient manner, and the width of the collecting flow channels is increased along with the decrease of the distance close to the outlet, so that the blocking phenomenon of flow channels close to the oversized mass transfer task of the outlet is avoided, and the reaction gas and the resultant water which are transmitted and collected from different stage flow channel units and distribution flow channels are discharged from the left outlet and the right outlet in a gradient manner in time.
The width of each grade of the middle distribution runner meets Wz (n-1) ＝k Z ·W Zn ，n＝2，…N，Wz (n-1) To distribute the width of the flow channel in the n-1 level, W Zn To allocate the width of the flow channel n level, k Z Gradient width ratio of middle distribution runner is 1.2.ltoreq.k Z Less than or equal to 1.5; the lengths of the various grades of the distribution flow channels satisfy L Z(n-1) ＝t Z ·L Zn ，Lz (n-1) Length of the medium distribution runner n-1 level, L Zn Length of the nth level of the flow channel is distributed among the flow channels, t Z The gradient length ratio of the middle distribution runner is not less than 1.2 and not more than t Z ≤1.5。
The width of each level of the left and right upper distribution flow channels satisfies W S(m-1) ＝k S ·W Sm ，m＝2，…M，W S(m-1) Dividing the width of the flow channel in the m-1 level to the left and the right upper part, W Sm Distributing width k of the mth level of the runner for the upper left and right S The gradient width ratio of the distribution flow channels on the left and the right is 1.1.ltoreq.k S Less than or equal to 1.6; the lengths of the levels of the left and right upper distribution flow channels satisfy L S(m-1) ＝t S ·L Sm ，L S(m-1) Distributing the length of the m-1 level of the flow channel for the left and the right upper part, L Sm Distributing the length of the mth level of the runner for the upper left and right, t S The gradient length ratio of the distribution flow channels on the left and the right is not less than 1.1 and not more than t S ≤1.6。
The width of each grade of the left and right collecting channels satisfies W B(n-1) ＝k B ·W Bn ，n＝2，…N，W B(n-1) For the width of the n-1 level of the left and right collecting channels, W Bn The width k of the nth class of the collecting channels for the left and right sides B The gradient width ratio of the left collecting flow channel and the right collecting flow channel is 0.5.ltoreq.k B Less than or equal to 0.9; the lengths of the left and right collecting channels satisfy L B(n-1) ＝t B ·L Bn ，L B(n-1) For the length of the n-1 th level of the left and right collecting channels, L Bn Collect for left and right sideLength of the nth stage of the flow channel, t B Gradient length ratio of left and right collecting channels, 0.5 < t B ≤0.9。
The width of each grade of the left and right lower collecting channels satisfies W X(k-1) ＝k X ·W Xk ，W X(k-1) For the width of the k-1 level of the left and right lower collecting channels, W Xk For the width of the k-th class of the left and right lower collecting channels, k X The gradient length ratio of the collecting flow channels is 0.5-k X Less than or equal to 0.9; length is L X(k-1) ＝t X ·L Xk ，L X(k-1) For the length of the k-1 level of the left and right lower collecting channels, L X(k-1) For the length of the k-th class of the left and right lower collecting channels, t X Gradient width ratio of collecting flow channel for left and right lower collecting flow channel, 0.5 < t X ≤0.9。
The included angle alpha between the primary father runner and the vertical central line is more than or equal to 45 degrees and less than or equal to 65 degrees. The widths of the primary father runner and the secondary father runner meet W F1 ＝k F ·W F2 ，W F1 Is the width of the primary father runner, W F2 Is the width, k of the secondary father runner F The width ratio of the primary father runner to the secondary father runner is 1.0 < k F Less than or equal to 1.2; the width relation between the father runner and the son runner of the same-level runner unit meets W F ＝k E ·W E ，W F Width of father flow channel, W E For the width of the sub-flow channel, k E The width ratio of the father runner to the son runner of the same-level runner unit is less than or equal to 1.0 and less than or equal to k E ≤2.0。
The bipolar plate body is made of one of graphite, titanium, niobium, aluminum, copper and stainless steel.
The depth D of each flow channel is equal and is 1.0 mm-2.0 mm.
Another object of the present invention is to provide a method for implementing a fuel cell bipolar plate of a bionic multi-stage bifurcated flow field.
The invention discloses a realization method of a fuel cell bipolar plate of a bionic multistage bifurcation flow field, which comprises the following steps:
1) When the fuel cell works, reaction gas enters from an inlet, and is transmitted to a flow channel unit network through an upper left distribution flow channel, an upper right distribution flow channel and a middle distribution flow channel, and as the lengths and widths of the upper left distribution flow channel, the upper right distribution flow channel and the middle distribution flow channel in the gas transmission direction are reduced in a gradient manner, the widths of the flow channels are changed through the gradient, the sectional areas of the flow channels are changed, the reaction gas with the same flow rate is transmitted, the distribution flow channels far away from the inlet position can be ensured to obtain a larger flow rate of the reaction gas, so that the reaction gas is directionally transmitted, the mass transfer efficiency of the bionic multi-stage bifurcation flow field is improved, and the reaction gas of each different stage flow channel unit connected with each different stage of the distribution flow channel can enter the whole bionic multi-stage bifurcation flow field at the same flow rate to carry out the reaction gas transmission, so that the reaction gas is promoted to be uniformly and rapidly enter a catalytic layer to carry out electrochemical reaction, and the electrochemical reaction generates product water;
2) The reaction gas transmitted from the distribution runner to the runner unit network firstly enters a primary parent runner, the primary runner is communicated with the distribution runner and the collection runner, the reaction gas and the generated water are directly transmitted to the collection runner by utilizing the through direct structural characteristic of the primary parent runner, and the first gradient directional transmission is carried out, so that the transmission path of the bionic multi-stage bifurcation flow field from an inlet to an outlet is shortened, the pressure drop and the pumping power of the fuel cell are obviously reduced, and the water generated by the reaction is rapidly discharged; the first-stage horizontal and vertical sub-flow passages are equidistantly distributed on the first-stage parent flow passage, and the component force of the reaction gas in the horizontal and vertical directions is utilized to transmit the reaction gas and the product water to the collecting flow passage for carrying out second gradient directional transmission; the tail end of each first-stage vertical sub-runner is an inlet of a second-stage runner unit, unreacted gas of the first-stage horizontal sub-runner and the first-stage vertical sub-runner enters a second-stage father runner again, and third gradient directional transmission is carried out on the reactant gas and the product water transmitted by the first-stage vertical sub-runner in the vertical direction; the second-stage vertical sub-flow passage and the second-stage horizontal sub-flow passage are respectively positioned in the vertical direction and the horizontal direction, and the component force of the reaction gas in the horizontal direction and the vertical direction is utilized again to transmit the reaction gas and the product water so as to perform fourth gradient directional transmission; the secondary horizontal sub-runner and the secondary vertical sub-runner of the secondary runner unit are connected back to the primary runner unit, and finally, the reaction gas and the product water are transmitted to the collecting runner in a multi-directional guiding and circulating mode; meanwhile, unreacted gas is circularly transmitted and utilized for multiple times, so that no place where the reactant gas does not reach exists in the bionic multi-stage bifurcation flow field, and the utilization rate of the reactant gas of the fuel cell is improved; the multi-stage bifurcation structure of the flow passage unit net can be used for draining product water to the collecting flow passage in a gradient and directional way, the drainage mechanism of the structure obviously improves the drainage efficiency of the fuel cell, and finally improves the performance and the stability of the fuel cell;
3) The length and the width of the collecting flow channels in the gas transmission direction are increased in a gradient manner, and the width of the collecting flow channels is increased along with the decrease of the distance close to the outlet, so that the blocking phenomenon of flow channels close to the oversized mass transfer task of the outlet is avoided, and the reaction gas and the resultant water which are transmitted and collected from different stage flow channel units and distribution flow channels are discharged from the left outlet and the right outlet in a gradient manner in time.
The invention has the advantages that:
the bipolar plate bionic multi-stage bifurcation flow field comprises a middle distribution flow channel, an upper distribution flow channel, a lower collection flow channel and collection flow channels symmetrically arranged on the left side and the right side; the width and the length of the distribution flow channels and the collection flow channels respectively decrease or increase in a gradient manner along the gas transmission direction, the number of grades of the distribution flow channels is equal to that of the collection flow channels on the left side and the right side, the width of the flow channels is changed through the gradient, the sectional area of the flow channels is changed, the flow channels are controlled to transmit the reaction gas with the same flow rate at any position, the distribution flow channels far from the inlet position are ensured to obtain the larger flow rate of the reaction gas, the directional transmission of the reaction gas is realized, the mass transfer efficiency of the bionic multistage bifurcation flow field is improved, and the uniform distribution of the reaction gas is promoted; the collecting flow passage is used for bearing the dual task of collecting unreacted gas and product water, the width of the collecting flow passage is increased along with the decrease of the distance close to the outlet, the larger flow speed near the outlet can be ensured while the pressure drop is low, the phenomenon of blockage of the collecting flow passage of the mass transfer task close to the outlet is avoided, and the product water is discharged in a gradient manner in time; two-stage flow channel units with left and right sides being symmetrical are distributed between the distribution flow channel and the collection flow channel, and a primary parent flow channel is communicated with the distribution flow channel and the collection flow channel, so that a transmission path of the bionic multi-stage bifurcation flow field from an inlet to an outlet is shortened, pressure drop and pumping power of the fuel cell are obviously reduced, and water generated by reaction is discharged rapidly; the secondary runner units are connected between the primary parent runners in a staggered manner through the secondary runners of the primary parent runner units, the secondary runners of the secondary runner units are communicated back to the primary parent runner, and unreacted gas of the primary runner units enters the secondary parent runner again, so that unreacted gas is recycled for multiple times, no place where the reactive gas does not reach exists in the bionic multi-stage bifurcation flow field, the utilization rate of the reactive gas is improved, and the discharge of water generated by the reaction can be accelerated through the structural arrangement of the gradient directional multi-stage staggered runner units; the mechanism changes the internal gas and water transmission mechanism of the bionic multi-stage forked flow field, the reactive gas is distributed uniformly in a directional way, the two-stage flow channel unit structure circulates the mass transfer and the water discharge in a staggered way, the pressure drop and the pumping power are reduced, the mass transfer efficiency is improved, the water management of the fuel cell is improved, and the performance and the stability of the fuel cell are finally improved.
Drawings
FIG. 1 is an elevation view of one embodiment of a fuel cell bipolar plate of a biomimetic multi-stage bifurcated flow field of the present invention;
FIG. 2 is a schematic diagram of a secondary flow channel unit of one embodiment of a fuel cell bipolar plate of the bionic multi-stage bifurcated flow field of the present invention;
fig. 3 is a schematic illustration of the width and length of the flow channels of one embodiment of a fuel cell bipolar plate of the biomimetic multi-stage bifurcated flow field of the present invention.
Detailed Description
The invention will be further elucidated by means of specific embodiments in conjunction with the accompanying drawings.
As shown in fig. 1, the fuel cell bipolar plate of the bionic multi-stage bifurcated flow field of the present embodiment includes: a bipolar plate main body, an inlet 1, a middle distribution runner 2, an upper left distribution runner 31, an upper right distribution runner 32, a left collecting runner 41, a right collecting runner 42, a lower left collecting runner 51, a lower right collecting runner 52, a runner unit, a left outlet 61, and a right outlet 62; the bipolar plate main body is a plane plate, an inlet 1 is carved in the center of the top of the front surface of the bipolar plate main body, a middle distribution runner 2 communicated with the inlet 1 is carved in the center of the front surface of the bipolar plate main body along the vertical direction, the middle distribution runner 2 is divided into four grades from top to bottom along the airflow transmission direction, and the length and the width of each grade are reduced in a gradient manner from top to bottom along the airflow transmission direction; the top of the front surface of the bipolar plate main body is carved with an upper left distribution runner 31 and an upper right distribution runner 32 which are communicated with the inlet 1 and are respectively positioned at two sides of the inlet 1 along the horizontal direction, the upper left distribution runner 31 and the upper right distribution runner 32 are symmetrically distributed about a vertical central line a-a', the upper left distribution runner 31 and the upper right distribution runner 32 are divided into two grades along the air flow transmission direction, and the length and the width of each grade are reduced in a gradient manner along the air flow transmission direction, namely from the middle to the two sides; left collecting flow channels 41 and right collecting flow channels 42 are respectively carved on two sides of the front surface of the bipolar plate main body along the vertical direction, the left collecting flow channels 41 and the right collecting flow channels 42 are symmetrically distributed about a vertical central line, the left collecting flow channels 41 and the right collecting flow channels 42 are uniformly divided into four grades along the air flow transmission direction, namely from top to bottom and the middle distributing flow channels 2, and the length and the width of each grade are increased in a gradient manner along the air flow transmission direction, namely from top to bottom; a left lower collecting flow passage 51 and a right lower collecting flow passage 51 which are communicated with the middle distributing flow passage 2 and are respectively positioned at two sides of the middle distributing flow passage 2 are carved on the bottom of the front surface of the bipolar plate along the horizontal direction, the left lower collecting flow passage 51 and the right lower collecting flow passage 52 are symmetrically distributed about a vertical center line and are respectively communicated with the left collecting flow passage 41 and the right collecting flow passage 42, the left lower collecting flow passage 51 and the right lower collecting flow passage 52 are divided into three grades along the air flow transmission direction, namely from the middle to the two sides, and the length and the width of each grade are increased in a gradient manner along the air flow transmission direction, namely from the middle to the two sides; the collecting part of the left collecting flow channel 41 and the left lower collecting flow channel 51 and the collecting part of the right collecting flow channel 42 and the right lower collecting flow channel 52 are respectively carved with a left outlet 61 and a right outlet 62, and the left outlet 61 and the right outlet 62 are symmetrically distributed about a vertical central line;
The middle distribution runner 2, the upper left distribution runner 31, and the upper right distribution runner 32 are collectively referred to as distribution runners, and the left collection runner 41, the right collection runner 42, the lower left collection runner 51, and the lower right collection runner 52 are collectively referred to as collection runners; a communicating runner unit is carved in a region enclosed between the distribution runner and the collection runner; the flow channel units are distributed according to self-similarity and affine rules, so that the flow channel units, the distribution flow channels and the collection flow channels form a bionic multi-stage bifurcation flow field; the flow channel units are symmetrically distributed about a vertical central line and comprise a primary flow channel unit and a secondary flow channel unit; wherein, the liquid crystal display device comprises a liquid crystal display device,
the primary runner unit comprises a primary parent runner 71, a primary horizontal sub runner 72 and a primary vertical sub runner 73; a plurality of parallel primary parent runners 71 are carved between the distribution runner and the collection runner, namely, between the upper left distribution runner 31 and the left collection runner 41, between the middle distribution runner 2 and the lower left collection runner 51, between the upper right distribution runner 32 and the right collection runner 42, between the middle distribution runner 2 and the right collection runner 42 and between the middle distribution runner 2 and the lower right collection runner 52, the primary parent runners 71 and the vertical center line have an acute included angle, and the distances between the adjacent primary parent runners 71 are equal; a plurality of first-stage horizontal sub-runners 72 along the horizontal direction are carved on the upper edge of the first-stage parent runner 71, and the distances between the adjacent first-stage horizontal sub-runners 72 are equal; a first-stage vertical sub-runner 73 along the vertical direction is carved on the lower edge of the first-stage parent runner 71, and the distances between the adjacent first-stage vertical sub-runners 73 are equal;
The secondary runner unit includes a secondary parent runner 81, a secondary horizontal sub runner 82, and a secondary vertical sub runner 83; the end of the primary horizontal sub-runner 72 of the primary parent runner 71 between the upper left distribution runner 31 and the left collection runner 41 and between the upper right distribution runner 32 and the right collection runner 42 is communicated with the secondary parent runner 81, and the secondary parent runner 81 is parallel to the primary parent runner 71; the tail ends of the secondary parent runners 81 are respectively communicated with a secondary horizontal sub runner 82 and a secondary vertical sub runner 83; the secondary horizontal sub-flow channel 82 is along the horizontal direction and the secondary vertical sub-flow channelThe flow passage 83 is in the vertical direction; the end of the secondary horizontal sub-flow passage 82 is communicated to the next primary vertical sub-flow passage 73 in the air flow transmission direction, and the end of the secondary vertical sub-flow passage 83 is communicated to the next primary parent flow passage 71 in the air flow transmission direction; the end of the primary horizontal sub-flow passage 72 communicates to the next secondary vertical sub-flow passage 83 in the air flow transfer direction; the included angle between the secondary horizontal sub-runner 82 and the secondary parent runner 81 is beta 2 The included angle between the secondary vertical sub-runner 83 and the secondary parent runner 81 is beta 1 ，β 1 +β 2 =90°, as shown in fig. 2.
The ends of the primary horizontal sub-flow path 72, the primary vertical sub-flow path 73, the secondary parent flow path 81, the secondary horizontal sub-flow path 82, and the secondary vertical sub-flow path 83 in the air flow transfer direction are communicated to the left side collecting flow path 41, the right side collecting flow path 42, the left lower collecting flow path 51, or the right lower collecting flow path 52.
As shown in FIG. 3, the four levels of width in the middle distribution runner 2 are Wz respectively 1 、Wz 2 、Wz 3 And Wz 4 The method comprises the following steps: wz 1 ＝1.2 3 Wz 4 ，Wz 2 ＝1.2 2 Wz 4 ，Wz 3 ＝1.2Wz 4 The method comprises the steps of carrying out a first treatment on the surface of the The lengths of the respective stages of the middle distribution runner 2 satisfy L Z1 、Lz 2 、Lz 3 And Lz 4 The method comprises the following steps: lz 1 ＝1.2 3 Lz 4 ，Lz 2 ＝1.2 2 Lz 4 ，Lz 3 ＝1.2Lz 4 。
The width of the two levels of the upper left and right distribution flow channels 31 and 32 is W, respectively S1 And W is S2 Satisfy W S1 ＝1.2W S2 The lengths of the two stages in the upper left and right distribution flow paths 31 and 32 satisfy L S1 And L S2 The method comprises the following steps: l (L) S1 ＝1.2L S2 。
The four level flow paths of the left and right collecting flow paths 41 and 42 are respectively W B1 、W B2 、W B3 And W is B4 The method comprises the following steps: wz 1 ＝0.8 3 W B4 ，W B2 ＝0.8 2 W B4 ，W B3 ＝0.8W B4 The method comprises the steps of carrying out a first treatment on the surface of the Left and right collecting channels 41 and 42Length of (2) is L B1 、L B2 、L B3 And L B4 The method comprises the following steps: l (L) B1 ＝0.8 3 L B4 ，L B2 ＝0.8 2 L B4 ，Lz 3 ＝0.8L B4 。
The width of each level of the left and right lower collecting channels 51 and 52 satisfies W X1 、W X2 And W is X3 The method comprises the following steps: w (W) X1 ＝0.8 2 W X3 ，W B2 ＝0.8W X3 The method comprises the steps of carrying out a first treatment on the surface of the The lengths of the left and right lower collecting channels 51 and 52 satisfy L X1 、L X2 And L X3 The method comprises the following steps: l (L) X1 ＝0.8 2 L X3 ，L B2 ＝0.8L X3 。
The primary parent channel 71 is at an angle α=60° to the vertical centerline; the widths of the primary parent flow passage 71 and the secondary parent flow passage 81 satisfy W F1 ＝1.2W F2 ，W F1 Width W of primary parent channel 71 F2 The width of the secondary parent channel 81; the width relation between the primary father runner and the primary vertical and horizontal son runners satisfies W F1 ＝1.63W E1 ，W E1 For the widths of the primary vertical and horizontal sub-channels, the relation of the widths of the secondary father channel and the secondary vertical and horizontal sub-channels satisfies W F2 ＝1.63W E2 ，W E2 Is the width of the secondary vertical and horizontal sub-channels.
Graphite is adopted as the material of the bipolar plate main body, and the depth D of each runner is 1.5mm.
The implementation method of the fuel cell bipolar plate of the bionic multi-stage bifurcation flow field of the embodiment comprises the following steps:
1) When the fuel cell works, reaction gas enters from the inlet 1, and is transmitted to the flow channel unit network through the upper left distribution flow channel 31, the upper right distribution flow channel 32 and the middle distribution flow channel 2, and the lengths and the widths of the upper left distribution flow channel 31, the upper right distribution flow channel 32 and the middle distribution flow channel 2 in the gas transmission direction are reduced in a gradient manner, so that the widths of the flow channels are changed by the gradient, the sectional area of the flow channels is changed, the reaction gas with the same flow rate is transmitted, the distribution flow channels far from the inlet 1 can be ensured to obtain the same larger flow rate of the reaction gas, the mass transfer efficiency of the bionic multi-stage bifurcation flow field is improved while the reaction gas is directionally transmitted, and the reaction gas of different stage flow channel units connected with different stages of the distribution flow channels can enter the whole bionic multi-stage bifurcation at the same flow rate to be transmitted, so that the reaction gas is promoted to be uniformly and rapidly enter the catalytic layer to perform electrochemical reaction, and the electrochemical reaction can generate product water;
2) The reaction gas transmitted from the distribution runner to the runner unit network firstly enters the primary parent runner 71, the primary runner is communicated with the distribution runner and the collection runner, the reaction gas and the generated water are directly transmitted to the collection runner by utilizing the through direct structural characteristic of the primary parent runner 71, and the first gradient directional transmission is carried out, so that the transmission path from the inlet 1 to the outlet of the bionic multi-stage bifurcation flow field is shortened, the pressure drop and the pumping power of the fuel cell are obviously reduced, and the water generated by the reaction is rapidly discharged; the primary horizontal and vertical sub-channels are equidistantly distributed on the primary parent channel 71, and the component force of the reaction gas in the horizontal and vertical directions is utilized to transmit the reaction gas and the product water to the collecting channel for carrying out second gradient directional transmission; the tail end of each first-stage vertical sub-runner 73 is an inlet of a second-stage runner unit, unreacted gas of the first-stage horizontal sub-runner 72 and the first-stage vertical sub-runner 73 enters a second-stage parent runner 81 again, and third gradient directional transmission is carried out on the reactant gas and the product water transmitted by the first-stage vertical sub-runner 73 in the vertical direction; the secondary vertical sub-flow channel 83 and the secondary horizontal sub-flow channel 82 which are respectively positioned in the vertical direction and the horizontal direction, and the component force of the reaction gas in the horizontal direction and the vertical direction is utilized again to transmit the reaction gas and the product water, so as to perform fourth gradient directional transmission; the secondary horizontal sub-runner 82 and the secondary vertical sub-runner 83 of the secondary runner unit are connected back to the primary runner unit, and finally, the reaction gas and the product water are transmitted to the collecting runner in a multi-directional guiding and circulating mode; meanwhile, unreacted gas is circularly transmitted and utilized for multiple times, so that no place where the reactant gas does not reach exists in the bionic multi-stage bifurcation flow field, and the utilization rate of the reactant gas of the fuel cell is improved; the multi-stage bifurcation structure of the flow passage unit net can be used for draining product water to the collecting flow passage in a gradient and directional way, the drainage mechanism of the structure obviously improves the drainage efficiency of the fuel cell, and finally improves the performance and the stability of the fuel cell;
3) The length and width of the collecting flow channels in the gas transmission direction are increased in a gradient manner, and the width of the collecting flow channels is increased along with the decrease of the distance close to the outlet, so that the blocking phenomenon of flow channels close to the oversized mass transfer task of the outlet is avoided, and the reaction gas and the resultant water which are transmitted and collected from different stage flow channel units and distribution flow channels are discharged from the left outlet 61 and the right outlet 62 in a gradient manner in time.
Finally, it should be noted that the examples are disclosed for the purpose of aiding in the further understanding of the present invention, but those skilled in the art will appreciate that: various alternatives and modifications are possible without departing from the spirit and scope of the invention and the appended claims. Therefore, the invention should not be limited to the disclosed embodiments, but rather the scope of the invention is defined by the appended claims.
Claims (10)
1. A fuel cell bipolar plate of a bionic multi-stage bifurcated flow field, the fuel cell bipolar plate comprising: the bipolar plate comprises a bipolar plate main body, an inlet, a middle distribution runner, an upper left distribution runner, an upper right distribution runner, a left collecting runner, a right collecting runner, a lower left collecting runner, a lower right collecting runner, a runner unit network, a left outlet and a right outlet; the bipolar plate main body is a plane plate, an inlet is engraved at the center of the top of the front surface of the bipolar plate main body, a middle distribution runner communicated with the inlet is engraved at the center of the front surface of the bipolar plate main body along the vertical direction, the middle distribution runner is divided into N grades along the air flow transmission direction, the length and the width of each grade are reduced in a gradient manner along the air flow transmission direction, and N is a natural number more than or equal to 4; the top of the front surface of the bipolar plate main body is carved with an upper left distribution runner and an upper right distribution runner which are communicated with the inlet and are respectively positioned at two sides of the inlet along the horizontal direction, the upper left distribution runner and the upper right distribution runner are symmetrically distributed about a vertical central line, the upper left distribution runner and the upper right distribution runner are divided into M grades along the air flow transmission direction, the length and the width of each grade are reduced in a gradient way along the air flow transmission direction, and M is a natural number which is more than or equal to 2; the two sides of the front surface of the bipolar plate main body are respectively carved with a left collecting runner and a right collecting runner along the vertical direction, the left collecting runner and the right collecting runner are symmetrically distributed about a vertical central line, the left collecting runner and the right collecting runner are uniformly divided into N grades along the airflow transmission direction and the middle distribution runner, and the length and the width of each grade are increased in a gradient manner along the airflow transmission direction; the bottom of the front surface of the bipolar plate is carved with a left lower collecting runner and a right lower collecting runner which are communicated with the middle distributing runner and are respectively positioned at two sides of the middle distributing runner along the horizontal direction, the left lower collecting runner and the right lower collecting runner are symmetrically distributed about a vertical central line and are respectively communicated with a left collecting runner and a right collecting runner, the left lower collecting runner and the right lower collecting runner are divided into K grades along the airflow transmission direction, the length and the width of each grade are increased in a gradient way along the airflow transmission direction, and K is a natural number which is more than or equal to 3; the collecting part of the left collecting flow channel and the left lower collecting flow channel and the collecting part of the right collecting flow channel and the right lower collecting flow channel are respectively carved with a left outlet and a right outlet, and the left outlet and the right outlet are symmetrically distributed about a vertical central line;
The middle distribution runner, the upper left distribution runner and the upper right distribution runner are collectively called a distribution runner, and the left collecting runner, the right collecting runner, the lower left collecting runner and the lower right collecting runner are collectively called a collecting runner; a communicating runner unit net is carved in the area enclosed between the distribution runner and the collection runner; the flow channel unit networks are distributed according to self-similarity and affine rules, so that the flow channel unit networks, the distribution flow channels and the collection flow channels form a bionic multi-stage bifurcation flow field; the gateway of the flow channel unit is symmetrically distributed on the vertical central line, and the network of the flow channel unit comprises a primary flow channel unit and a secondary flow channel unit; wherein, the liquid crystal display device comprises a liquid crystal display device,
the primary runner unit comprises a primary parent runner, a primary horizontal sub runner and a primary vertical sub runner; a plurality of parallel primary father runners are carved between the distribution runner and the collection runner, namely, between the upper left distribution runner and the collection runner, between the middle distribution runner and the collection runner, between the upper right distribution runner and the collection runner, between the middle distribution runner and the collection runner, and between the middle distribution runner and the collection runner, the primary father runners and the collection runner have acute angles with the vertical center line, and the distances between the adjacent primary father runners are equal; a plurality of first-level horizontal sub-channels which are communicated with the first-level father channel and along the horizontal direction are carved on the upper edge of each first-level father channel, and the distances between the adjacent first-level horizontal sub-channels are equal; a plurality of first-stage vertical sub-channels which are communicated with the first-stage father channel along the vertical direction are carved on the lower edge of each first-stage father channel, and the distances between the adjacent first-stage vertical sub-channels are equal;
The secondary runner unit comprises a secondary father runner, a secondary horizontal sub runner and a secondary vertical sub runner; the tail end of the first-level horizontal sub-runner of the first-level vertical sub-runner is communicated with a second-level father runner, and the tail end of the first-level horizontal sub-runner of the first-level father runner positioned between the left upper distribution runner and the left collecting runner and between the right upper distribution runner and the right collecting runner is communicated with the second-level father runner, and the second-level father runner is parallel to the first-level father runner; the tail ends of the secondary father runners are respectively communicated with a secondary horizontal sub runner and a secondary vertical sub runner; the secondary horizontal sub-flow passage is along the horizontal direction, and the secondary vertical sub-flow passage is along the vertical direction; the tail end of the secondary horizontal sub-runner is communicated with the next primary vertical sub-runner along the air flow transmission direction, and the tail end of the secondary vertical sub-runner is communicated with the next primary father runner along the air flow transmission direction; the tail end of the first-stage horizontal sub-runner is communicated with the next second-stage vertical sub-runner along the air flow transmission direction;
the tail ends of the first-level horizontal sub-runner, the first-level vertical sub-runner, the second-level father runner, the second-level horizontal sub-runner and the second-level vertical sub-runner along the air flow transmission direction are communicated with the corresponding left collecting runner, right collecting runner, left lower collecting runner or right lower collecting runner; the son runner and father runner of each level runner unit are of a bifurcation structure, and a runner unit network formed by two levels of runner units is of a multi-level bifurcation structure;
When the fuel cell works, reaction gas enters from an inlet, and is transmitted to a flow channel unit network through an upper left distribution flow channel, an upper right distribution flow channel and a middle distribution flow channel, and the lengths and widths of the upper left distribution flow channel, the upper right distribution flow channel and the middle distribution flow channel in the gas transmission direction are reduced in a gradient manner, so that the widths of the flow channels are changed through the gradient, the sectional areas of the flow channels are changed, the reaction gas with the same flow rate is transmitted, the distribution flow channels far away from the inlet position can be ensured to obtain a larger reaction gas flow rate, the mass transfer efficiency of the bionic multi-stage bifurcation flow field is improved while the reaction gas is directionally transmitted, and the reaction gas of each different-stage flow channel unit connected with each different stage of the distribution flow channel can enter the whole bionic multi-stage bifurcation flow field at the same flow rate, so that the reaction gas is promoted to be uniformly distributed, the reaction gas is enabled to uniformly and rapidly enter a catalytic layer to perform electrochemical reaction, and the electrochemical reaction generates product water; the reaction gas transmitted from the distribution runner to the runner unit network firstly enters a primary parent runner, the primary parent runner is communicated with the distribution runner and the collection runner, the reaction gas and the generated water are directly transmitted to the collection runner by utilizing the through direct structural characteristic of the primary parent runner, and the first gradient directional transmission is carried out, so that the transmission path of the bionic multi-stage bifurcation flow field from an inlet to an outlet is shortened, the pressure drop and the pumping power of the fuel cell are obviously reduced, and the generated water is rapidly discharged; the first-stage horizontal and vertical sub-flow channels are equidistantly distributed on the first-stage parent flow channel, and the component force of the reaction gas in the horizontal and vertical directions is utilized to transmit the reaction gas and the product water to the collecting flow channel for carrying out second gradient directional transmission; the tail end of each first-stage vertical sub-runner is an inlet of a second-stage runner unit, unreacted gas of the first-stage horizontal sub-runner and the first-stage vertical sub-runner enters a second-stage father runner again, and third gradient directional transmission is carried out on the reactant gas and the product water transmitted by the first-stage vertical sub-runner in the vertical direction; the second-stage vertical sub-flow passage and the second-stage horizontal sub-flow passage are respectively positioned in the vertical direction and the horizontal direction, and the component force of the reaction gas in the horizontal direction and the vertical direction is utilized again to transmit the reaction gas and the product water so as to perform fourth gradient directional transmission; the secondary horizontal sub-runner and the secondary vertical sub-runner of the secondary runner unit are connected back to the primary runner unit, and finally, the reaction gas and the product water are transmitted to the collecting runner in a multi-directional guiding and circulating mode; meanwhile, unreacted gas is circularly transmitted and utilized for multiple times, so that no place where the reactant gas does not reach exists in the bionic multi-stage bifurcation flow field, and the utilization rate of the reactant gas of the fuel cell is improved; the multi-stage bifurcation structure of the flow passage unit net can be used for draining product water to the collecting flow passage in a gradient and directional way, the drainage mechanism of the structure obviously improves the drainage efficiency of the fuel cell, and finally improves the performance and the stability of the fuel cell; the length and the width of the collecting flow channels in the gas transmission direction are increased in a gradient manner, and the width of the collecting flow channels is increased along with the decrease of the distance close to the outlet, so that the blocking phenomenon of flow channels close to the oversized mass transfer task of the outlet is avoided, and the reaction gas and the resultant water which are transmitted and collected from different stage flow channel units and distribution flow channels are discharged from the left outlet and the right outlet in a gradient manner in time.
2. The fuel cell bipolar plate of claim 1 wherein the width of each stage of the middle distribution runner satisfies Wz (n-1) ＝k Z ·W Zn ，n＝2，…N，Wz (n-1) To distribute the width of the flow channel in the n-1 level, W Zn To allocate the width of the flow channel n level, k Z Gradient width ratio of middle distribution runner is 1.2.ltoreq.k Z Less than or equal to 1.5; the lengths of the various grades of the distribution flow channels satisfy L Z(n-1) ＝t Z ·L Zn ，Lz (n-1) Length of the medium distribution runner n-1 level, L Zn Length of the nth level of the flow channel is distributed among the flow channels, t Z The gradient length ratio of the middle distribution runner is not less than 1.2 and not more than t Z ≤1.5。
3. The fuel cell bipolar plate of claim 1 wherein the width of each level of the left and right upper distribution channels satisfies W S(m-1) ＝k S ·W Sm ，m＝2，…M，W S(m-1) Dividing the width of the flow channel in the m-1 level to the left and the right upper part, W Sm Distributing width k of the mth level of the runner for the upper left and right S Distributing flow channels for upper left and rightGradient width ratio, k is 1.1.ltoreq.k S Less than or equal to 1.6; the lengths of the levels of the left and right upper distribution flow channels satisfy L S(m-1) ＝t S ·L Sm ，L S(m-1) Distributing the length of the m-1 level of the flow channel for the left and the right upper part, L Sm Distributing the length of the mth level of the runner for the upper left and right, t S The gradient length ratio of the distribution flow channels on the left and the right is not less than 1.1 and not more than t S ≤1.6。
4. The fuel cell bipolar plate of claim 1 wherein the width of each of the left and right side collecting channels at each level satisfies W B(n-1) ＝k B ·W Bn ，n＝2，…N，W B(n-1) For the width of the n-1 level of the left and right collecting channels, W Bn The width k of the nth class of the collecting channels for the left and right sides B The gradient width ratio of the left collecting flow channel and the right collecting flow channel is 0.5.ltoreq.k B Less than or equal to 0.9; the lengths of the left and right collecting channels satisfy L B(n-1) ＝t B ·L Bn ，L B(n-1) For the length of the n-1 th level of the left and right collecting channels, L Bn The length of the nth class of the collecting flow channel for the left side and the right side, t B Gradient length ratio of left and right collecting channels, 0.5 < t B ≤0.9。
5. The fuel cell bipolar plate of claim 1 wherein the width of each level of the left and right lower collecting channels satisfies W X(k-1) ＝k X ·W Xk ，W X(k-1) For the width of the k-1 level of the left and right lower collecting channels, W Xk For the width of the k-th class of the left and right lower collecting channels, k X The gradient length ratio of the collecting flow channels is 0.5-k X Less than or equal to 0.9; length is L X(k-1) ＝t X ·L Xk ，L X(k-1) For the length of the k-1 level of the left and right lower collecting channels, L X(k-1) For the length of the k-th class of the left and right lower collecting channels, t X Gradient width ratio of collecting flow channel for left and right lower collecting flow channel, 0.5 < t X ≤0.9。
6. The fuel cell bipolar plate of claim 1 wherein the primary parent flow channel has an angle α of 45 ° or less and 65 ° or less from the vertical centerline.
7. The fuel cell bipolar plate of claim 1 wherein the primary parent flow channel and the secondary parent flow channel have widths that satisfy W F1 ＝k F ·W F2 ，W F1 Is the width of the primary father runner, W F2 Is the width, k of the secondary father runner F The width ratio of the primary father runner to the secondary father runner is 1.0 < k F Less than or equal to 1.2; the width relation between the father runner and the son runner of the same-level runner unit meets W F ＝k E ·W E ，W F Width of father flow channel, W E For the width of the sub-flow channel, k E The width ratio of the father runner to the son runner of the same-level runner unit is less than or equal to 1.0 and less than or equal to k E ≤2.0。
8. The fuel cell bipolar plate of claim 1 wherein the bipolar plate body is made of one of graphite, titanium, niobium, aluminum, copper and stainless steel.
9. The bipolar plate of claim 1 wherein each of said flow channels has an equal depth of 1.0mm to 2.0mm.
10. A method of implementing a fuel cell bipolar plate of a biomimetic multi-stage bifurcated flow field as in claim 1, the method comprising the steps of:
1) When the fuel cell works, reaction gas enters from an inlet, and is transmitted to a flow channel unit network through an upper left distribution flow channel, an upper right distribution flow channel and a middle distribution flow channel, and as the lengths and widths of the upper left distribution flow channel, the upper right distribution flow channel and the middle distribution flow channel in the gas transmission direction are reduced in a gradient manner, the widths of the flow channels are changed through the gradient, the sectional areas of the flow channels are changed, the reaction gas with the same flow rate is transmitted, the distribution flow channels far away from the inlet position can be ensured to obtain a larger flow rate of the reaction gas, so that the reaction gas is directionally transmitted, the mass transfer efficiency of the bionic multi-stage bifurcation flow field is improved, and the reaction gas of each different stage flow channel unit connected with each different stage of the distribution flow channel can enter the whole bionic multi-stage bifurcation flow field at the same flow rate to carry out the reaction gas transmission, so that the reaction gas is promoted to be uniformly and rapidly enter a catalytic layer to carry out electrochemical reaction, and the electrochemical reaction generates product water;
2) The reaction gas transmitted from the distribution runner to the runner unit network firstly enters a primary parent runner, the primary runner is communicated with the distribution runner and the collection runner, the reaction gas and the generated water are directly transmitted to the collection runner by utilizing the through direct structural characteristic of the primary parent runner, and the first gradient directional transmission is carried out, so that the transmission path of the bionic multi-stage bifurcation flow field from an inlet to an outlet is shortened, the pressure drop and the pumping power of the fuel cell are obviously reduced, and the water generated by the reaction is rapidly discharged; the first-stage horizontal and vertical sub-flow passages are equidistantly distributed on the first-stage parent flow passage, and the component force of the reaction gas in the horizontal and vertical directions is utilized to transmit the reaction gas and the product water to the collecting flow passage for carrying out second gradient directional transmission; the tail end of each first-stage vertical sub-runner is an inlet of a second-stage runner unit, unreacted gas of the first-stage horizontal sub-runner and the first-stage vertical sub-runner enters a second-stage father runner again, and third gradient directional transmission is carried out on the reactant gas and the product water transmitted by the first-stage vertical sub-runner in the vertical direction; the second-stage vertical sub-flow passage and the second-stage horizontal sub-flow passage are respectively positioned in the vertical direction and the horizontal direction, and the component force of the reaction gas in the horizontal direction and the vertical direction is utilized again to transmit the reaction gas and the product water so as to perform fourth gradient directional transmission; the secondary horizontal sub-runner and the secondary vertical sub-runner of the secondary runner unit are connected back to the primary runner unit, and finally, the reaction gas and the product water are transmitted to the collecting runner in a multi-directional guiding and circulating mode; meanwhile, unreacted gas is circularly transmitted and utilized for multiple times, so that no place where the reactant gas does not reach exists in the bionic multi-stage bifurcation flow field, and the utilization rate of the reactant gas of the fuel cell is improved; the multi-stage bifurcation structure of the flow passage unit net can be used for draining product water to the collecting flow passage in a gradient and directional way, the drainage mechanism of the structure obviously improves the drainage efficiency of the fuel cell, and finally improves the performance and the stability of the fuel cell;
3) The length and the width of the collecting flow channels in the gas transmission direction are increased in a gradient manner, and the width of the collecting flow channels is increased along with the decrease of the distance close to the outlet, so that the blocking phenomenon of flow channels close to the oversized mass transfer task of the outlet is avoided, and the reaction gas and the resultant water which are transmitted and collected from different stage flow channel units and distribution flow channels are discharged from the left outlet and the right outlet in a gradient manner in time.
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