CN201466110U

CN201466110U - Snakelike micro-point mixed type flow field for proton exchange membrane fuel cell

Info

Publication number: CN201466110U
Application number: CN2009201062279U
Authority: CN
Inventors: 王新东; 李山梅; 马利军; 魏浩杰; 侯淼淼; 王同涛; 叶锋
Original assignee: University of Science and Technology Beijing USTB
Current assignee: University of Science and Technology Beijing USTB
Priority date: 2009-03-17
Filing date: 2009-03-17
Publication date: 2010-05-12
Anticipated expiration: 2019-03-17

Abstract

The utility model discloses a snakelike micro-point mixed type flow field for a proton exchange membrane fuel cell, belonging to the technical field of fuel cell flow field. In the structure of the flow field, a snakelike flow field and a micro-point prominence layer of a flow field ridge part are organically combined to form a fuel reaction area; the main structure of the flow field comprises a feed inlet A, a feed inlet D, a feed outlet B, a feed outlet C, flow guiding grooves 1 and 5 respectively located in an inlet and an outlet, a communicated sealing groove 6, a snakelike flow channel2, ridge 3 of the flow field and ridge prominence structural micro-point 4. The size of the micro-point is smaller than the width of the ridge, and the height of the micro-point is controlled to be one fifth to one third of the depth of a snakelike flow path. The main body design of the snakelike flow channel guarantees favorable velocity distribution of reactant and excellent draining performance, and the micro-point embedded structure enables electrode surface contact points to connect the current of the fuel cell more safely. The utility model fully maintains the advantage of the snakelike flow field and enhances local current collection effect of the flow field; the cell performance of the snakelike micro-point mixed flow field is obviously higher than that of a point type flow field and has better overall performance than that of a snakelike flow field; and the utility model is suitable for direct menthol fuel cells and hydrogen-oxygen fuel cells.

Description

The snakelike little some mixed flow field of used in proton exchange membrane fuel cell

Technical field

The utility model belongs to fuel battery flow field, particularly the flow field structure of a proton exchanging film fuel battery.

Background technology

Fuel cell is the new forms of energy of a kind of high efficiency, high-energy-density and environment-friendly type, fuel cell technology has improved the utilance of fuel greatly as a kind of novel energy utilization patterns, helps reducing acid rain, greenhouse effect and the problem of environmental pollution that traditional energy brings.Today, be developed country or developing country all in the development and utilization of acceleration fuel cell technology, make great efforts to promote its business-like process.Proton Exchange Membrane Fuel Cells (PEMFC) is to be electrolyte with perfluorinated sulfonic acid type amberplex, and methyl alcohol or hydrogen are fuel, and air or oxygen is the fuel cell of oxidant.The core of PEMFC is membrane electrode and bipolar plates.Membrane electrode is the place of electrochemical reaction, bipolar plates is called flow-field plate (Flow field plates) or current-collector (Current collectors) again, its major function is charging water conservancy diversion and collected current, fuel distributes and these two tasks of collected current in order to finish, and bipolar plates need have the penetrability of excellent conducting performance, good current collection performance, good heat-conducting, anti-fuel and oxidant and the corrosion resistance in electrochemical environment etc. usually.

The design of bipolar plate flow field at first should be satisfied and flows smooth and easyly, reduces air resistance, pressure falls less (to reduce the auxiliary power consumption of gas compression) and assurance gas by diffusion layer to all even good current collection effect of the transmission of catalyst surface.Secondly, it is very important in time cell electrochemical reaction being generated the water discharge.If can not in time discharge generating water, along with building up of water generation reaction, will cause: the water around (1) catalyst makes reactant can not fully contact with catalyst, so-called " electrode water logging " phenomenon promptly occurs; (2) accumulation of water also can make sometimes and film be produced the local swelling phenomenon that produces of film shrink or flexural deformation, influences the output performance of battery; (3) increased the resistance to mass tranfer of reactant, reduced the power output of battery by diffusion layer arrival Catalytic Layer.

The point-like flow field is a kind of flow field of being used widely in early days, and its rate of flow of fluid is lower, so drainability is poor, but moisture-retaining capacity is stronger relatively.The fluid flow uniformity is generally not ideal enough, fluid is being imported and exported flowing soon of line zone, and on the corner, have viscous flow, problems such as concentration polarization or water logging occur, but good local current collection distribution makes it still obtain being suitable for widely under some specific condition.

The flow field of crawling is a kind of flow field of at present extensive use, and the advantage of serpentine flow path is that the entrance and exit of passage is corresponding one by one, because repeatedly bending, passage is longer relatively, and concentration gradient is bigger, and mass transfer is more even.When current density was big, fuel-feed increased, and the flow velocity in the runner than the runner of other types has more strengthened the transmission capacity of fuel from runner course diffusion layer, and fuel infiltration is less, the performance of battery when helping to improve high current density; When the methyl alcohol input hour because resistance is bigger, be unfavorable for mass transfer, influence normally carrying out of electrochemical reaction, battery performance is not high.

The utility model content

In order to solve the deficiency in above-mentioned various flow fields, effectively control on the advantage basis of flow field pressure drop in reservation snakelike (single snake or many snakes) flow field, proposition on multichannel serpentine flow basis in conjunction with the point-like flow field, promptly carve many little spot-like projections structures in the spine in the flow field of crawling more, with the drawback of avoiding normal stream field type runner spine and diffusion layer contact position fuel to be difficult to arrive, it is more even to reach the horizontal fuel mass transfer of diffusion layer, avoids the purpose of water logging.Because the damascene structures of little layer in the miniature environment of part, has better current collection and distributes, make this kind flow field have better current collection function on the other hand.

For achieving the above object, this flow field structure organically combines the formation fuel reaction zone by little some protuberance layer of snakelike (single snake or many snakes) flow field and flow field spine.Its agent structure comprises charging aperture A and D, discharging opening B and C (C and D are the bipolar plates discharging opening and the charging aperture in one side flow field in addition), the water conservancy diversion groove 1 and 5 in porch and exit; The sealed groove 6 that is communicated with; The serpentine flow path 2 of flow field conversion zone; The little point 4 of the spine 3 in flow field and spine's raised structures.

The width of this flow field serpentine flow path is 0.8-1.2mm, and the degree of depth is 1-1.5mm, and ridge is wide to be 0.6-1.2mm.On this basis, in the many equally distributed little points 4 of being carved with of flow field spine, the size of little point is less than the width of ridge.The height of little point be controlled at flow channel depth 1/5th to 1/3rd between.

Described snakelike little some flow field serpentine flow path 2 can be snakelike for single channel, binary channels parallel snakelike, multi-channel parallel is snakelike, any form in the snakelike grade of gradual change.

The cross sectional shape of described little point 4 structures can for round point shape, rectangular-shaped, hexagon is cellular, oblique strip and irregularly shaped in one or more combination, its stereochemical structure can be cuboid, trapezoid body, cylinder and cone etc.

The degree of depth of described sealed groove 6 is 0.5-0.8mm, and wide is 3-4mm, annular be communicated be distributed in flow field regions around.

Fuel and oxidant flow into inside, battery flow field by inlet A and D respectively, enter serpentine flow path through separately guiding gutter, flow being parallel to the MEA direction along serpentine flow path, and because diffusion, the effect of infiltration and convection current is flowed to the MEA direction; In addition, because the existence of little layer, make loose a little with contacting of flow field spine with the direct contacted diffusion layer in flow field, fluid also will be to the direction diffusion around little point, form the flow-disturbing of the little point of ring, thereby form fluid is parallel to the MEA direction in diffusion layer diffusion, also spread and infiltration when fuel and oxidant are covered with diffusion layer through modes such as diffusion, infiltration, convection current to Catalytic Layer, contact with catalyst in Catalytic Layer, the electro-catalysis chemical reaction takes place.Along with the carrying out of electrochemical reaction, fuel and oxide consume gradually, the water of generation and C0 ₂Gas, through Catalytic Layer, diffusion layer, runner are finally got rid of from outlet B and C through the guiding gutter in exit.

This flow field structure has following advantage:

1. the gas that has kept serpentine flow distributes, the VELOCITY DISTRIBUTION advantage of reasonable, has improved the deficiency of the easy water logging of serpentine flow flow field end.

2. the existence of little layer not only can produce in the part and strengthen pressure, also might produce local turbulence, has reduced the resistance of horizontal mass transfer in the diffusion layer, makes fuel and the oxidant mass transfer in diffusion layer more even.

3. little layer is a damascene structures with contacting of diffusion layer, has increased local current collecting efficiency, has reduced the transmission loss of electric current, makes the flow field possess better current collection ability.

4. improved flow field type has kept the superiority that use in the point-like flow field under high current density, the drawback that the agent structure of serpentine flow has avoided the point-like flow field to use under high current density again, the utilance of the fuel that improves is applicable to direct methanol fuel cell and hydrogen oxygen fuel cell.

Description of drawings

Fig. 1 is snakelike (single snake) little some mixing flow field perspective view

Fig. 2 is the planar structure schematic diagram of how snakelike little some mixing flow field

Fig. 3 is the planar structure schematic diagram of the snakelike little point of multichannel gradual change

Cross-sectional view when Fig. 4 is square, hexahedron and cylinder for the little point in flow field

Cross-sectional view when Fig. 5 is centrum for the little point in flow field

Fig. 6 is the little dot structure schematic diagram in flow field

Embodiment

Embodiment 1

This flow field is little some mixed structure of single snake-like, as shown in Figure 1, bipolar plates be shaped as rectangle, its size is 1.5cm * 1.5cm, its effective working region be 1.3cm * 1.3cm, the bipolar plates simulation material is a graphite.The thickness of bipolar plates is 2mm, and the cross sectional dimensions of main serpentine flow path 2 grooves is 1mm * 1mm, and the width of spine 3 is 1mm, and little point 4 is of a size of 0.4mm * 0.3mm * 0.25mm, and serpentine flow path 2 is 1mm deeply.

Snakelike little some mixing flow field has the damascene structures that is similar to miniature point-like flow field, in the miniature environment of part, has better current collection and distributes.During oversaturated fuel gas, the battery performance of snakelike little some mixing flow field is apparently higher than serpentine flow.The damascene structures in layer CURRENT DISTRIBUTION point-like flow field not only can produce in the part and strengthen pressure, also might produce local turbulence.Increase local current collection effect, reduced the transmission loss of electric current.In middle low current density areas, snakelike little some mixing flow field be complicated to contain a plurality of little dot structures provides more electrode surface contact point to collect the electric current of fuel cell, increase along with current density, the serpentine flow path structure of snakelike little some mixing flow field has guaranteed the unobstructed of drainage performance, have the drainage performance suitable with serpentine flow, because the superiority on the current collection, thereby overall performance is better than serpentine flow.

Embodiment 2

The size in the snakelike little some flow field of multichannel is identical with embodiment 1, and different is that the flow field is the multichannel serpentine flow, and the little point 4 of spine is the tetragonal body shape, and little spot size is 0.4mm * 0.4mm * 0.35mm, and serpentine flow path 2 is 1.2mm deeply, as shown in Figure 2.This flow field had both kept the characteristics of multichannel serpentine flow mass transfer more even (comparing with single channel is snakelike), had possessed the little some advantage that the type current collection is good again.

Embodiment 3

The degree of depth of flow field serpentine flow path 2 among the size in the snakelike little some flow field of multichannel gradual change (three become two) and the embodiment 1, the width of width and ridge is all identical, and little point 4 of spine is the little point of cylinder type, is of a size of r=0.25mm, height is 0.32mm, and serpentine flow path 2 is 1.5mm deeply.As shown in Figure 3.Because passage is by changeable few, the pressure in the passage increases gradually, and the fluid velocity of Jiang Diing increases once more gradually, makes that the fluid mass-transfer of flow field latter half is more even, fast.Avoided owing to fuel flows to the rear portion, flow field because the fuel supply that the reduction of concentration and flow velocity causes is not enough and the generation of non-uniform phenomenon; Little some type makes that the horizontal mass transfer in flow field is more even, and the current collection effect is also better.

Claims

1. snakelike little some mixed flow field of used in proton exchange membrane fuel cell, its agent structure comprises the water conservancy diversion groove in charging aperture and discharging opening, porch and exit, the sealed groove that is communicated with, it is characterized in that, the width of the serpentine flow path of flow field conversion zone (2) is 0.8-1.2mm, the degree of depth is 1-1.5mm, ridge is wide to be 0.6-1.2mm, in the many equally distributed little points of being carved with of flow field spine (4), the size of little point is less than the width of ridge, the height of little point flow channel depth 1/5th to 1/3rd between.

2. the snakelike little some mixed flow field of stating as claim 1 is characterized in that more, described serpentine flow path (2) is that single channel is snakelike, binary channels parallel snakelike, multi-channel parallel is snakelike, gradual change any in snakelike.

3. the snakelike little some mixed flow field of stating as claim 1 more, it is characterized in that, the cross sectional shape of described little point (4) structure be round point shape, rectangular-shaped, hexagon is cellular, oblique strip and irregularly shaped in any, its stereochemical structure is a cuboid, trapezoid body, cylinder and cone.

4. the snakelike little some mixed flow field of stating as claim 1 is characterized in that more, and the degree of depth of described sealed groove (6) is 0.5-0.8mm, and wide is 3-4mm, annular be communicated be distributed in flow field regions around.