CN215418242U

CN215418242U - Flow field structure of bipolar plate of proton exchange membrane fuel cell

Info

Publication number: CN215418242U
Application number: CN202121738409.5U
Authority: CN
Inventors: 张锐明; 唐浩林; 隋邦杰; 黄亮; 龚聪文
Original assignee: Guangdong Institute Of Hydrogen Energy Industry Technology
Current assignee: Guangdong Institute Of Hydrogen Energy Industry Technology
Priority date: 2021-07-28
Filing date: 2021-07-28
Publication date: 2022-01-04
Anticipated expiration: 2031-07-28

Abstract

The utility model discloses a flow field structure of a bipolar plate of a proton exchange membrane fuel cell, which has the main innovative design points that: the electrochemical reaction active area of the bipolar plate adopts the smoothness of a staggered lattice structure, so that the uniform distribution of the flow speed of hydrogen, air and cooling liquid is realized, the discharge performance and reliability of the galvanic pile can be improved, meanwhile, the efficient heat dissipation is realized, and the stable operation of the proton exchange membrane fuel cell is ensured. The shape of the staggered dot matrix comprises a circular dot matrix, a rectangular dot matrix and a special-shaped dot matrix. The anisotropic lattice adopts a streamline design, and the flow resistance is reduced to the maximum extent. The design of the staggered lattice structure is subjected to computational fluid mechanics and statics simulation calculation and experimental verification, and the optimal longitudinal spacing, transverse spacing and lattice shape are determined through optimization design.

Description

Flow field structure of bipolar plate of proton exchange membrane fuel cell

Technical Field

The utility model belongs to the technical field of fuel cells, and particularly relates to a novel bipolar plate flow field structure of a proton exchange membrane fuel cell.

Background

The fuel cell is a device for directly converting chemical energy of fuel into electric energy, and compared with the traditional heat engine, the fuel cell has the advantages of high operating efficiency, cleanness, no pollution, low noise and the like, and is expected to solve the problem of environmental pollution of an energy system. At present, fuel cells are popularized and applied in the fields of automobiles, unmanned planes, fixed power generation and the like, and have wide application prospects in the future.

The electric pile is a core component of a fuel cell and is formed by laminating membrane electrodes, bipolar plates, current collecting plates, end plates and other components. Wherein the bipolar plate is in direct contact with the membrane electrode, the main function of the bipolar plate is to conduct current and provide a stable and uniform fluid supply. Fluids in the pem fuel cell include hydrogen, air and coolant, and the flow velocity distribution is required to be uniform by the optimized design of the bipolar plate flow field structure. If the hydrogen and air flow velocity distribution is not uniform, the local electrochemical reaction activity is affected, resulting in non-uniform current and voltage of the battery cell, non-uniform heating value and additional energy loss. If the flow velocity distribution of the cooling liquid is not uniform, the temperature distribution inside the single cell is not uniform, so that larger local thermal stress is caused, and the output performance and the service life of the cell stack are influenced.

In the prior art, the bipolar plate of the proton exchange membrane fuel cell usually adopts a parallel direct current structure. For example, a chinese utility model patent with publication number CN213278134U discloses a high-power proton exchange membrane fuel cell bipolar plate, which comprises: be located cooling flow field on the bipolar plate, the one end in cooling flow field is provided with air inlet, hydrogen export and cooling water entry, and the other end is provided with hydrogen entry, air export and cooling water export, the cooling flow field is located in the middle of the bipolar plate, and the both ends in cooling flow field are provided with the distribution dot matrix, be provided with the distribution region between distribution dot matrix and cooling water entry, the cooling water export, the distribution dot matrix includes marginal dot matrix and direction dot matrix, the direction dot matrix sets up with the parallel sprue slope in cooling flow field, and the both sides of direction dot matrix are provided with marginal dot matrix.

The bipolar plate provided by the prior patent has a simple structure and is easy to process, and although the distribution dot matrixes are arranged, the distribution dot matrixes are only arranged at two ends of the cooling flow field, and the main cooling area in the middle part is still in a parallel direct current structure; therefore, the problems of poor fluid distribution effect and low uniformity still exist.

SUMMERY OF THE UTILITY MODEL

Aiming at the problems in the prior art, the utility model aims to provide a novel bipolar plate flow field structure of a proton exchange membrane fuel cell, which has more uniform flow velocity distribution of hydrogen, air and cooling liquid, so that the discharge performance and reliability of a galvanic pile are improved, high-efficiency heat dissipation is realized, and the stable operation of the proton exchange membrane fuel cell is ensured.

In order to achieve the purpose, the utility model adopts the following technical scheme.

A bipolar plate flow field structure of a proton exchange membrane fuel cell, comprising: the plate body is provided with an air inlet, an air outlet, a hydrogen inlet, a hydrogen outlet, a cooling liquid inlet, a cooling liquid outlet and an electrochemical reaction active area; the electrochemically active area is located at the middle of the plate body, the air inlet, the hydrogen inlet and the coolant inlet are located at one end of the electrochemically active area, and the air outlet, the hydrogen outlet and the coolant outlet are located at the other end of the electrochemically active area; a flow field structure is arranged corresponding to the electrochemical reaction active area; the flow field structure is a staggered lattice structure formed by a plurality of lattice units, and the staggered lattice structure is used for hydrogen, air and cooling liquid flow channels.

More preferably, the lattice units close to the end where the cooling liquid inlet is located and the end where the cooling liquid outlet is located adopt gradually changed lattice intervals; the closer to the end of the plate body, the larger the lattice spacing, and the closer to the center of the plate body, the smaller the lattice spacing.

More preferably, the gradual change of the dot matrix pitch comprises gradual change of the pitch in the direction of each row of the dot matrix and/or gradual change of the pitch in the direction of each column of the dot matrix.

More preferably, the lattice unit located in the middle of the electrochemical reaction active region is a uniform lattice structure, and a lattice interval of the uniform lattice structure is smaller than a minimum value of the gradual change lattice interval.

More preferably, the lattice unit near the end of the cooling liquid inlet and the end near the cooling liquid outlet have gradually changed geometric sizes; the geometrical shape of the dot matrix unit is smaller closer to the end of the plate body, and the geometrical shape of the dot matrix unit is larger closer to the center of the plate body.

More preferably, the staggered lattice structure is a circular lattice, a rectangular lattice or a streamline-designed irregular lattice.

More preferably, the staggered lattice structure has a staggered form of: and the lattice units are kept at a certain interval along the direction from the cooling liquid inlet to the cooling liquid outlet and staggered along the direction perpendicular to the direction from the cooling liquid inlet to the cooling liquid outlet.

More preferably, the plate body is a rectangular plate body, the air inlet and the air outlet are arranged along one diagonal of the plate body, the hydrogen inlet and the hydrogen outlet are arranged along the other diagonal of the plate body, the coolant inlet is located between the air inlet and the hydrogen inlet, and the coolant outlet is located between the air outlet and the hydrogen outlet.

More preferably, the plate body is a metal plate, a graphite plate or a composite material plate, and the plate body is prepared by numerical control machine machining, die pressing or stamping casting.

More preferably, in the staggered lattice structure, the shapes of the lattice units and the intervals among the lattice units are obtained through computational fluid dynamics and statics simulation calculation and experimental verification.

Compared with the prior art, the utility model has the beneficial effects.

The utility model provides a flow field structure of a bipolar plate of a proton exchange membrane fuel cell, wherein a staggered dot matrix is adopted in an electrochemical reaction active area of the bipolar plate. The staggered dot matrix is easy to process, the distribution uniformity of the flow velocity is good, and an ideal fluid distribution effect is realized. The hydrogen and the air are uniformly distributed, so that the electrochemical reaction rate in the single fuel cell is consistent. For cooling liquid, the staggered dot matrix can break a fluid boundary layer, reduce the temperature difference between a solid phase and a liquid phase and obviously improve the heat dissipation efficiency. Meanwhile, the cooling liquid is uniformly distributed, so that the heat dissipation efficiency is uniformly distributed, and the internal temperature distribution of the single fuel cell is more uniform. Through test verification, the distribution uniformity of fluid inside the bipolar plate is greater than 97%, and the difference between the highest temperature and the lowest temperature inside a single cell of the fuel cell is less than 5 ℃; the distribution uniformity of the fluid in the straight flow channel is far better than 76 percent of the distribution uniformity of the fluid in the existing straight flow channel.

Secondly, the flow field dot matrix of the bipolar plate adopts uneven distribution, the dot matrix distribution is sparse at the fluid inlet and the fluid outlet, and the flow resistance is reduced to the maximum extent. Through test verification, under the rated working condition of the fuel cell, the pressure difference of an inlet and an outlet of a hydrogen and air flow passage is less than 30kPa, and the pressure difference of an inlet and an outlet of a cooling liquid flow passage is less than 50 kPa.

The shape of the bipolar plate flow field lattice can adopt a circular, rectangular or streamline special-shaped lattice through simulation design, and through computational fluid mechanics, statics simulation and optimization design, the bipolar plate flow field lattice not only ensures the uniform dispersion of fluid, but also can play a role in supporting the strength of the bipolar plate, and protects the bipolar plate from deformation and fracture under assembly pressure.

And fourthly, key parameters of the bipolar plate flow field lattice comprise the geometrical shape of lattice units, the longitudinal spacing, the transverse spacing and the gradual change trend of the spacing, a design scheme can be defined by using the minimum parameters, and the optimized design scheme can be obtained by using the minimum test and calculation cost during the optimized design.

And fifthly, the bipolar plate flow field adopts a staggered lattice structure, so that the processing is simpler and the use cost is low.

Drawings

Fig. 1 is a schematic diagram of a plate flow field partition of a bipolar plate flow field structure provided by the present invention.

Fig. 2 is a circular lattice structure diagram of a bipolar plate flow field structure provided by the present invention.

Fig. 3 is a rectangular lattice structure diagram of a bipolar plate flow field structure provided by the present invention.

Fig. 4 is a water drop type lattice structure diagram of the bipolar plate flow field structure provided by the utility model.

Fig. 5 is a cross-sectional flow velocity profile of a conventional bipolar plate having a straight flow channel in the active region.

Fig. 6 is a flow velocity distribution diagram of a middle section of a bipolar plate using a drop staggered lattice according to the present invention.

Reference numerals indicate the same.

1: plate body, 2: air inlet, 3: air outlet, 4: hydrogen inlet, 5: hydrogen outlet, 6: cooling liquid inlet, 7: coolant outlet, 8: electrochemical reaction active region, 9-1/9-2/9-3: and (4) flow field structure.

Detailed Description

In the description of the present invention, it should be noted that, for the terms of orientation, such as "central", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., it indicates that the orientation and positional relationship shown in the drawings are based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, but does not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and be operated without limiting the specific scope of protection of the present invention.

Furthermore, if the terms "first" and "second" are used for descriptive purposes only, they are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features. Thus, a definition of "a first" or "a second" feature may explicitly or implicitly include one or more of the feature, and in the description of the utility model, "at least" means one or more unless specifically defined otherwise.

In the present invention, unless otherwise expressly specified or limited, the terms "assembled", "connected", and "connected" are to be construed broadly, e.g., as meaning fixedly connected, detachably connected, or integrally connected; or may be a mechanical connection; the two elements can be directly connected or connected through an intermediate medium, and the two elements can be communicated with each other. The specific meanings of the above terms in the present invention can be understood by those of ordinary skill in the art according to specific situations.

In the present application, unless otherwise specified or limited, "above" or "below" a first feature may include the first and second features being in direct contact, and may also include the first and second features not being in direct contact but being in contact with each other through another feature therebetween. Also, the first feature being "above," "below," and "above" the second feature includes the first feature being directly above and obliquely above the second feature, or simply an elevation which indicates a level of the first feature being higher than an elevation of the second feature. The first feature being "above", "below" and "beneath" the second feature includes the first feature being directly below or obliquely below the second feature, or merely means that the first feature is at a lower level than the second feature.

The following describes the embodiments of the present invention with reference to the drawings of the specification, so that the technical solutions and the advantages thereof are more clear and clear. The embodiments described below are exemplary and are intended to be illustrative of the utility model, but are not to be construed as limiting the utility model.

Additional aspects and advantages of the utility model will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the utility model.

As shown in fig. 1, the present invention provides a bipolar plate flow field structure of a proton exchange membrane fuel cell, including: the plate comprises a plate body 1, an air inlet 2, an air outlet 3, a hydrogen inlet 4, a hydrogen outlet 5, a cooling liquid inlet 6, a cooling liquid outlet 7 and an electrochemical reaction active area 8, wherein the air inlet, the air outlet, the hydrogen inlet 4, the hydrogen outlet 5, the cooling liquid inlet 6, the cooling liquid outlet 7 and the electrochemical reaction active area 8 are arranged on the plate body 1, the electrochemical reaction active area 8 is positioned in the middle of the plate body 1, and a flow field is arranged corresponding to the electrochemical reaction active area 8; the air inlet 2, the hydrogen inlet 4, and the coolant inlet 6 are located at one end of the electrochemically active region 8, and the air outlet 3, the hydrogen outlet 5, and the coolant outlet 7 are located at the other end of the electrochemically active region 8.

The plate body 1 is a rectangular plate body, the air inlet 2 and the air outlet 3 are arranged along one diagonal of the plate body 1, the hydrogen inlet 4 and the hydrogen outlet 5 are arranged along the other diagonal of the plate body 1, the cooling liquid inlet 6 is arranged between the air inlet 2 and the hydrogen inlet 4, and the cooling liquid outlet 7 is arranged between the air outlet 3 and the hydrogen outlet 5. The arrangement can achieve better heat dissipation effect.

An important innovative design of the utility model is that the flow field on the electrochemical reaction active region 8 adopts a staggered lattice structure to replace the traditional parallel direct current structure, and the shape of the lattice can adopt a circular lattice, a rectangular lattice or a streamline special-shaped lattice.

The specific design form of the staggered lattice structure is as follows: the lattice units are kept at a certain distance along the direction from the cooling liquid inlet 6 to the cooling liquid outlet 7, and are staggered along the direction perpendicular to the direction from the cooling liquid inlet 6 to the cooling liquid outlet 7.

When the fuel cell works, the fluid distribution on the whole electrochemical reaction active area 8 is realized by utilizing the staggered dot matrix, and the uniform distribution of reaction gas is realized for hydrogen and air, so that the electrochemical reaction rate in the single cell of the fuel cell is consistent. For cooling liquid, the staggered dot matrix can break a fluid boundary layer, reduce the temperature difference between a solid phase and a liquid phase and obviously improve the heat dissipation efficiency. Meanwhile, the cooling liquid is uniformly distributed, so that the heat dissipation efficiency is uniformly distributed, and the internal temperature distribution of the single fuel cell is more uniform. Tests prove that the staggered dot matrix provided by the utility model is used for realizing the fluid distribution on the electrochemical reaction active area 8, the distribution uniformity of the fluid in the plate body 1 is more than 97%, the difference between the highest temperature and the lowest temperature in a single fuel cell is less than 5 ℃, under the rated working condition of the fuel cell, the pressure difference between an inlet and an outlet of a hydrogen and air flow passage is less than 30kPa, and the pressure difference between an inlet and an outlet of a cooling liquid flow passage is less than 50 kPa.

The method of use of the present invention is illustrated below with reference to three examples.

Example 1.

As shown in fig. 2, a bipolar plate flow field structure of a proton exchange membrane fuel cell includes: the plate comprises a plate body 1, an air inlet 2, an air outlet, a hydrogen inlet 4, a hydrogen outlet, a cooling liquid inlet 6, a cooling liquid outlet and an electrochemical reaction active area 8 which are arranged on the plate body 1, wherein a flow field structure 9-1 is arranged corresponding to the electrochemical reaction active area 8; the flow field structure 9-1 adopts a circular staggered lattice structure.

The circular staggered lattice structures at the two ends of the electrochemical reaction active region 8 adopt gradually changed lattice intervals, the closer to one side of an inlet or an outlet, the larger the lattice intervals are, and the closer to one side of the center of the plate body 1, the smaller the lattice intervals are.

In this embodiment, the gradual change of the dot pitch includes gradual change of the transverse pitch H0 and gradual change of the longitudinal pitch V0. Obviously, one of the vertical spacing H0 and the vertical spacing V0 can be set to be a gradual structure according to different actual needs by those skilled in the art; the present embodiment is not limited.

As an alternative embodiment of the gradual change structure, the radius of the circular lattice unit may be set to be in a gradual change form, which can achieve similar technical effects.

In this embodiment, the circular staggered lattice structure in the middle of the electrochemical reaction active region 8 is a uniform lattice structure. That is, the lateral pitch H1 and the longitudinal pitch V1 remain unchanged. Also, the lateral spacing H1 is less than the minimum lateral spacing H0 and the longitudinal spacing V1 is less than the minimum longitudinal spacing V0.

It should be noted that various parameter designs of the circular staggered lattice structure, such as values of H0, V0, H1, and V1, and values of the radius of the circular lattice unit, are obtained by optimization design by those skilled in the art with the minimum flow resistance and the most uniform temperature distribution as the optimization design goal. The optimization design method comprises simulation calculation optimization or experiment optimization, and the cost of the simulation calculation optimization is lower. As for the specific simulation calculation optimization or experimental optimization method, it is common technical knowledge known to those skilled in the art, and detailed description thereof is omitted here.

Example 2.

As shown in fig. 3, a bipolar plate flow field structure of a proton exchange membrane fuel cell comprises: the plate comprises a plate body 1, an air inlet 2, an air outlet, a hydrogen inlet 4, a hydrogen outlet, a cooling liquid inlet 6, a cooling liquid outlet and an electrochemical reaction active area 8 which are arranged on the plate body 1, wherein a flow field structure 9-2 is arranged corresponding to the electrochemical reaction active area 8; the flow field structure 9-2 adopts a rectangular staggered lattice structure.

The rectangular staggered lattice structures at the two ends of the electrochemical reaction active region 8 adopt gradually changed lattice intervals, the closer to one side of an inlet or an outlet, the larger the lattice intervals are, and the closer to one side of the center of the plate body 1, the smaller the lattice intervals are.

As a transformation implementation mode of the gradual change structure, the length and width values of the rectangular lattice unit can be set into a gradual change form, and similar technical effects can be achieved.

In this embodiment, the rectangular staggered lattice structure located in the middle of the electrochemical reaction active region 8 is a uniform lattice structure. That is, the lateral pitch H1 and the longitudinal pitch V1 remain unchanged. Also, the lateral spacing H1 is less than the minimum lateral spacing H0 and the longitudinal spacing V1 is less than the minimum longitudinal spacing V0.

It should be noted that various parameter designs of the rectangular staggered lattice structure, such as values of H0, V0, H1, and V1, and values of the length and width of the rectangular lattice unit, are obtained by optimization design with minimum flow resistance and most uniform temperature distribution as optimization design targets by those skilled in the art. The optimization design method comprises simulation calculation optimization or experiment optimization, and the cost of the simulation calculation optimization is lower. As for the specific simulation calculation optimization or experimental optimization method, it is common technical knowledge known to those skilled in the art, and detailed description thereof is omitted here.

Example 3.

As shown in fig. 4, a bipolar plate flow field structure of a proton exchange membrane fuel cell comprises: the plate comprises a plate body 1, an air inlet 2, an air outlet, a hydrogen inlet 4, a hydrogen outlet, a cooling liquid inlet 6, a cooling liquid outlet and an electrochemical reaction active area 8 which are arranged on the plate body 1, wherein a flow field structure 9-3 is arranged corresponding to the electrochemical reaction active area 8; the flow field structure 9-3 adopts a drop-shaped staggered lattice structure.

The drop-shaped staggered dot matrix structures at the two ends of the electrochemical reaction active region 8 adopt gradually changed dot matrix intervals, the closer to one side of an inlet or an outlet, the larger the dot matrix interval is, and the closer to one side of the center of the plate body 1, the smaller the dot matrix interval is.

As a transformation implementation mode of the gradual change structure, the geometric shape of the drop-shaped lattice unit can be set into a gradual change form, and a similar technical effect can be achieved.

In this embodiment, the droplet-shaped staggered lattice structure located in the middle of the electrochemical reaction active region 8 is a uniform lattice structure. That is, the lateral pitch H1 and the longitudinal pitch V1 remain unchanged. Also, the lateral spacing H1 is less than the minimum lateral spacing H0 and the longitudinal spacing V1 is less than the minimum longitudinal spacing V0.

It should be noted that various parameter designs of the droplet-shaped staggered lattice structure, such as values of H0, V0, H1, and V1, and geometric design of the droplet-shaped lattice units (spline curve fitting is performed on the outer contours of the droplet-shaped lattice units), are obtained by optimization design by those skilled in the art with minimum flow resistance and most uniform temperature distribution as optimization design targets. The optimization design method comprises simulation calculation optimization or experiment optimization, and the cost of the simulation calculation optimization is lower. As for the specific simulation calculation optimization or experimental optimization method, it is common technical knowledge known to those skilled in the art, and detailed description thereof is omitted here.

It should be noted that, those skilled in the art may also adopt other irregularly-shaped staggered dot matrix structures with streamline design to replace the drop-shaped staggered dot matrix structure, as long as the flow resistance can be reduced to the greatest extent, and the present invention is not limited to this embodiment.

And (4) carrying out comparative experiments.

In order to better embody the progress of the present invention, the flow velocity distribution experiment of the middle section is respectively performed on the staggered dot matrix flow field structure provided by the present invention and the flow field structure of the direct flow channel in the prior art.

Fig. 5 is a flow velocity distribution diagram of a middle section of a bipolar plate with straight flow channels in an active area, wherein the flow velocity distribution is W-shaped and the flow distribution uniformity reaches 76%. Fig. 6 shows that the flow distribution uniformity of the flow distribution of the bipolar plate with the drop-shaped staggered dot matrix according to the present invention is significantly improved to 97%.

It will be appreciated by those skilled in the art from the foregoing description of construction and principles that the utility model is not limited to the specific embodiments described above, and that modifications and substitutions based on the teachings of the art may be made without departing from the scope of the utility model as defined by the appended claims and their equivalents. The details not described in the detailed description are prior art or common general knowledge.

Claims

1. A bipolar plate flow field structure of a proton exchange membrane fuel cell, comprising: the plate body is provided with an air inlet, an air outlet, a hydrogen inlet, a hydrogen outlet, a cooling liquid inlet, a cooling liquid outlet and an electrochemical reaction active area; the electrochemically active area is located at the middle of the plate body, the air inlet, the hydrogen inlet and the coolant inlet are located at one end of the electrochemically active area, and the air outlet, the hydrogen outlet and the coolant outlet are located at the other end of the electrochemically active area; a flow field structure is arranged corresponding to the electrochemical reaction active area; the flow field structure is a staggered lattice structure formed by a plurality of lattice units, and the staggered lattice structure is used for hydrogen, air and cooling liquid flow channels.

2. The bipolar plate flow field structure of proton exchange membrane fuel cell according to claim 1, wherein the lattice unit near the end of the cooling liquid inlet and the end of the cooling liquid outlet adopts gradually changed lattice spacing; the closer to the end of the plate body, the larger the lattice spacing, and the closer to the center of the plate body, the smaller the lattice spacing.

3. A pem fuel cell bipolar plate flow field structure as claimed in claim 2, wherein said gradual pitch change of said lattice comprises gradual pitch change in the direction of each row of said lattice and/or gradual pitch change in the direction of each column of said lattice.

4. The pem fuel cell bipolar plate flow field structure of claim 2, wherein said lattice unit located in the middle of said electrochemically active area is a uniform lattice structure having a lattice spacing smaller than the minimum of the gradual lattice spacing.

5. The bipolar plate flow field structure of a proton exchange membrane fuel cell according to claim 1, wherein the lattice unit near the end where the cooling liquid inlet is located and the lattice unit near the end where the cooling liquid outlet is located have gradually changed geometric sizes; the geometrical shape of the dot matrix unit is smaller closer to the end of the plate body, and the geometrical shape of the dot matrix unit is larger closer to the center of the plate body.

6. The PEMFC bipolar plate flow field structure of claim 1, wherein said staggered lattice structure is a circular lattice, a rectangular lattice or a streamlined shaped lattice.

7. A pem fuel cell bipolar plate flow-field structure as claimed in claim 1, wherein said staggered lattice structure is in the form of: and the lattice units are kept at a certain interval along the direction from the cooling liquid inlet to the cooling liquid outlet and staggered along the direction perpendicular to the direction from the cooling liquid inlet to the cooling liquid outlet.

8. A proton exchange membrane fuel cell bipolar plate flow field structure as claimed in claim 1, wherein the plate body is a rectangular plate body, the air inlet and the air outlet are disposed along one diagonal of the plate body, the hydrogen inlet and the hydrogen outlet are disposed along the other diagonal of the plate body, the coolant inlet is located between the air inlet and the hydrogen inlet, and the coolant outlet is located between the air outlet and the hydrogen outlet.

9. A pem fuel cell bipolar plate flow field structure of claim 1 wherein said plate body is a metal plate, a graphite plate or a composite plate.