Combined grid type flow field transition device, fuel cell flow field plate and fuel cell

Abstract

The application discloses a combined grid type flow field transition device, a fuel cell flow field plate and a fuel cell. The combined grid type flow field transition device comprises a central horizontal grid area and two lateral vertical grid areas. The central horizontal grid area is arranged at a gas opening of the flow field plate, and the two lateral vertical grid areas are arranged on the two sides of the central horizontal grid area. The gas enters the central horizontal grid area from the gas opening to form a horizontal flow. The horizontal flow is uniformly distributed and converted into a uniform vertical flow through the two lateral vertical grid areas, and then enters a reaction area to react. The device adopts a combined design of the central horizontal grid area and the lateral vertical grid areas, simultaneously has the functions of horizontal flow generation and distribution, and is a combination of the central area and the two side areas. The device can achieve the effect of flow uniform distribution with small resistance, that is, "drag reduction and efficiency improvement", and can further strengthen the water and heat management capability of the battery and improve the performance and durability of the fuel cell.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fuel cells, in particular to a combined grid type flow field transition device, a fuel cell flow field plate and a fuel cell. BACKGROUND

[0002] A hydrogen fuel cell is a clean and efficient energy conversion device that converts chemical energy stored in fuel and oxidants into electrical energy through electrochemical reactions, and has a huge development prospect in the fields of transportation and energy storage.

[0003] A single cell, as the core unit of a fuel cell stack, is composed of a flow field plate and a membrane electrode. The flow field plate of a fuel cell includes a gas opening, a transition zone and a reaction zone, and the reaction zone is usually composed of multiple parallel flow channels or grooves, which is the place where electrochemical reactions occur. With the continuous increase of the area of practical fuel cells, the number of flow channels can reach dozens or even more, and the problem of uniformity of gas distribution in each flow channel in the reaction zone gradually emerges.

[0004] The transition zone is located between the gas opening and the reaction zone, and is the place where flow distribution is achieved. The current design of the flow field transition zone can be divided into two types: channel type and dot matrix type. In the channel type structure, each transition zone fine channel is responsible for a certain number of parallel flow channels in the downstream reaction zone. Since the flow characteristic sizes of the two are comparable, it is often difficult to complete the flow distribution in each flow unit. The dot matrix transition zone is to arrange rectangular or circular obstacles in the flow field transition zone, and the flow characteristics are changed from "internal flow" of fine channels to "restricted flow around". Fluid spontaneously selects the path with the smallest resistance to enter each flow channel in the downstream reaction zone. The current design of this type of transition zone uniformly arranges dot matrix, which lacks scientificity and rationality. The improper design of the transition zone structure will directly cause the problem of "increased resistance and reduced efficiency", that is, uneven flow distribution and increased flow pressure drop in the polar plate, which further causes the consequences of reduced reaction gas diffusion flux, accumulated product liquid water, etc., ultimately affecting the performance and durability of the fuel cell. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the defects of uneven flow distribution and increased flow pressure drop in the polar plate caused by the unreasonable design of the existing fuel cell flow field transition zone.

[0006] To solve the above technical problems, the present application provides a combined grid type flow field transition device, a fuel cell flow field plate and a fuel cell.

[0007] The technical scheme adopted by the present application to solve the above technical problems is: a combined grid type flow field transition device applied between a gas opening and a reaction area of a fuel cell flow field plate, the combined grid type flow field transition device comprising a central horizontal grid area and two lateral vertical grid areas, the central horizontal grid area being arranged at the gas opening of the flow field plate, and the two lateral vertical grid areas being arranged on the two sides of the central horizontal grid area; gas enters the central horizontal grid area from the gas opening to form a horizontal flow, the horizontal flow is uniformly distributed and converted into a uniform vertical flow through the two lateral vertical grid areas, and then enters the reaction area for reaction.

[0008] In the present scheme, when fluid approaches the central horizontal grid area, the fluid is blocked in the central horizontal grid area to form a stagnation point flow, at the stagnation point, the velocity of the fluid is zero, the pressure is increased, a horizontal pressure gradient is formed, and a horizontal flow is generated, i.e. a part of the fluid changes from vertical flow to horizontal flow; from the nature of flow, it is the horizontal flow that plays a role in uniformizing the velocity, which efficiently transports the high-speed area of large vertical kinetic energy to the low-speed area, thereby strengthening the uniform distribution process of the fluid; according to this uniform distribution mechanism based on horizontal flow regulation, a suitable horizontal flow is formed in the central horizontal grid area, and the horizontal flow is uniformly distributed to the two side areas through the lateral vertical grid areas, and then converted into a uniform vertical flow, thereby effectively improving the uniformity of fluid flow through active flow control.

[0009] Due to the combined design of the central horizontal grid area and the lateral vertical grid area, the gas entering from the gas opening can be distributed, the gas is uniformly distributed to the two sides through the horizontal flow, and then converted into a uniform vertical flow; the present device has both the functions of generating and distributing horizontal flow, and is a combination of the central area and the two side areas, which can achieve the effect of flow uniformity with small resistance, i.e. "drag reduction and efficiency improvement", thereby being capable of strengthening the water and heat management capability of the battery and improving the performance and durability of the fuel cell; the combined grid type flow field transition device provided by the present application has low cost, is economic and practical, is simple to manufacture, and can be applied to large-scale production.

[0010] Preferably, the central horizontal grid area comprises a first substrate and a plurality of grid protrusions, the plurality of grid protrusions being arranged horizontally on the first substrate, and the plurality of grid protrusions being horizontally spaced apart on the first substrate.

[0011] In the present scheme, the plurality of grid protrusions are arranged horizontally to block the gas of the gas opening, so that the gas flows to the two sides in a horizontal direction, thereby realizing the function of gas distribution.

[0012] Preferably, the side vertical grid area comprises a second substrate and a plurality of grid protrusions, the plurality of grid protrusions are longitudinally arranged on the second substrate, and the plurality of grid protrusions are transversely spaced on the second substrate, and a longitudinal air channel is formed between two adjacent grid protrusions.

[0013] In the present scheme, the gas passes through the plurality of longitudinal air channels to change the flow direction, and the plurality of longitudinal air channels uniformly distribute the gas to flow into the reaction area.

[0014] Preferably, the length h of the grid protrusion is 1 / 4-1 / 3 of the short side length H of the transition area of the flow field plate.

[0015] In the present scheme, the length of the longitudinal grid protrusion is limited to be less than the width of the transition area, so that a space for gas flow and distribution is formed between the longitudinal grid protrusion gas openings, and a space for gas flow and distribution is formed between the longitudinal grid protrusion and the reaction area, and the uniformity of gas distribution in the reaction area is improved.

[0016] Preferably, the height of the grid protrusion is consistent with the depth of the flow channel of the reaction area, and both are 0.3-2 mm; and / or, the width of the grid protrusion is consistent with the width of the flow channel of the reaction area, and both are 0.3-2 mm.

[0017] Preferably, the edge of the center transverse grid area close to the gas opening is on the same horizontal line as the edge of the side vertical grid area close to the gas opening; and / or, the horizontal line is on the short side center line of the transition area of the flow field plate.

[0018] In the present scheme, when the horizontal flow flows into the side vertical grid area, the left and right side vertical grid areas maintain the same height, and the left and right gas distribution amounts are uniform; the upper edges of the center transverse grid area and the side vertical grid area are on the short side center line of the transition area, so that a wide gas distribution area is formed between the upper edges of the center transverse grid area and the side vertical grid area and the gas opening, which is beneficial for the gas to flow freely in this area and reduces the flow resistance.

[0019] Preferably, the width of the center transverse grid area is consistent with the width of the gas opening, and the center transverse grid area is directly opposite the gas opening.

[0020] In the present scheme, the center transverse grid area is directly opposite the gas opening, the gas is evenly distributed on the left and right, the width of the center transverse grid area just covers the gas opening, and under the premise of being able to completely change the direction of the gas, the width of the center transverse grid area is reduced to reduce the gas resistance.

[0021] A fuel cell flow field plate comprising a gas opening, a reaction zone and at least one combined grid type flow field transition device.

[0022] Preferably, the number of the combined grid type flow field transition devices is two, and the gas opening comprises a gas inlet and a gas outlet, wherein one of the combined grid type flow field transition devices is arranged between the gas inlet and the reaction zone, and the other of the combined grid type flow field transition devices is arranged between the gas outlet and the reaction zone.

[0023] In the present scheme, the gas enters one of the combined grid type flow field transition devices from the gas inlet, reacts in the reaction zone, and then flows out from the other of the combined grid type flow field transition devices and the gas outlet, thereby completing the process of gas distribution, reaction and discharge.

[0024] A fuel cell comprising the fuel cell flow field plate as described above.

[0025] In the present scheme, the fuel cell using the fuel cell flow field plate of the present application has the effect of "reducing resistance and increasing efficiency", that is, under the same working conditions, the gas flow uniformity inside the fuel cell of the present application is better, and the gas flow resistance is smaller, thereby improving the durability and performance of the fuel cell.

[0026] On the basis of common knowledge in the art, the above-mentioned preferred conditions can be combined arbitrarily, thereby obtaining each preferred example of the present application.

[0027] The positive progress effect of the present application is that: due to the combined design of the central transverse grid zone and the lateral vertical grid zone, the gas entering from the gas opening can be distributed, and the gas is uniformly distributed to both sides by transverse flow, and then converted into uniform longitudinal flow; the present device has both the functions of generating and distributing transverse flow, and is a combination of the central region and the two side regions, which can achieve the effect of uniform flow with smaller resistance, that is, "reducing resistance and increasing efficiency", thereby strengthening the water and heat management capability of the battery and improving the performance and durability of the fuel cell; the combined grid type flow field transition device provided by the present application has low cost, is economical and practical, is simple to manufacture, and can be applied to large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 FIG. 1 is a structural schematic diagram of an embodiment of the combined grid type flow field transition device of the present application.

[0029] Figure 2 FIG. 4 is a schematic diagram of the gas flow in the grid type flow field transition device of the present application.

[0030] Figure 3 FIG. 7 is a distribution schematic diagram of the central transverse grid zone and the lateral vertical grid zone of the present application.

[0031] Figure 4A cross-sectional view at A-A in the present application Figure 1 A cross-sectional view at A-A in the present application

[0032] Figure 5 A comparison chart of the gas flow uniformity of the present application and the existing uniform dot array type distribution device.

[0033] BRIEF DESCRIPTION OF DRAWINGS

[0034] Gas opening 10

[0035] Reaction zone 11

[0036] Transition zone 12

[0037] Central horizontal grid zone 20

[0038] Side vertical grid zone 30

[0039] Grid protrusion 40

[0040] First substrate 21

[0041] Second substrate 31

[0042] Longitudinal airway 41

[0043] Transition zone short edge center line C

[0044] Transition zone short edge length H

[0045] Grid protrusion length h

[0046] Lateral flow V1

[0047] Longitudinal flow V2 DETAILED DESCRIPTION

[0048] The present application will be more fully understood and appreciated by referring to the following detailed description taken in conjunction with the accompanying drawings, in which:

[0049] Figures 1-5 An embodiment of a combined grid type flow field transition device of the present application is shown, which is applied between the gas opening and the reaction zone of a fuel cell flow field plate, and the combined grid type flow field transition device comprises a central horizontal grid zone 20 and two side vertical grid zones 30, the central horizontal grid zone 20 is arranged at the gas opening 10 of the flow field plate, and the two side vertical grid zones 30 are arranged at the two sides of the central horizontal grid zone 20; the gas enters the central horizontal grid zone 20 from the gas opening 10 to form a lateral flow, the lateral flow is uniformly distributed and converted into a uniform longitudinal flow by the two side vertical grid zones 30, and then enters the reaction zone 11 for reaction, as shown in Figure 2 , wherein the direction shown by V1 is the flow direction of the lateral flow, and the direction shown by V2 is the flow direction of the longitudinal flow.

[0050] In this example, when the fluid approaches the central transverse grid area 20, it is obstructed within the central transverse grid area 20, forming stagnation flow. At the stagnation point, the fluid velocity is zero, the pressure increases, forming a transverse pressure gradient and generating transverse flow. That is, a portion of the fluid changes from longitudinal flow to transverse flow. From the perspective of flow essence, it is the transverse flow that plays a role in velocity homogenization, efficiently transporting the larger longitudinal kinetic energy in the high-speed region to the low-speed region, thus enhancing the fluid uniformity process. Based on this uniformity mechanism based on transverse flow control, a suitable transverse flow is formed in the central transverse grid area 20, and it is evenly distributed to the two sides through the lateral vertical grid areas 30, transforming into a uniform longitudinal flow. Through active flow control, the uniformity of fluid flow is effectively improved.

[0051] Due to the combined design of the central horizontal grid area 20 and the side vertical grid areas 30, the gas entering through the gas opening 10 can be distributed. The gas is evenly distributed from the center to both sides through lateral flow, and then transformed into a uniform longitudinal flow. This device has two functions: generating and distributing lateral flow. It is a combination of the central area and the side areas, which can achieve the effect of uniform flow distribution with less resistance, i.e., "drag reduction and efficiency improvement". This can enhance the battery's hydrothermal management capabilities and improve the performance and durability of the fuel cell. The combined grid-type flow field transition device provided by this invention has low cost, is economical and practical, is easy to manufacture, and can be applied to mass production.

[0052] Preferably, the central horizontal grid area 20 includes a first substrate 21 and a plurality of grid protrusions 40, the plurality of grid protrusions 40 being horizontally disposed on the first substrate 21 and the plurality of grid protrusions 40 being horizontally spaced on the first substrate 21.

[0053] In this example, multiple grid protrusions are arranged horizontally to block the gas from the gas opening 10, thereby causing the gas to flow laterally to both sides, thus achieving the function of gas distribution.

[0054] In practice, the adjacent two transverse grid protrusions 40 are spaced apart and form a ventilation gap, which is used to divert the gas flowing in from the gas opening 10 so that it enters the reaction zone 11 evenly.

[0055] like Figure 1 and Figure 4 As shown, preferably, the side vertical grid area 30 includes a second substrate 31 and a plurality of grid protrusions 40. The plurality of grid protrusions 40 are longitudinally disposed on the second substrate 31, and the plurality of grid protrusions 40 are arranged laterally at intervals on the second substrate 31, and a longitudinal air passage 41 is formed between two adjacent grid protrusions 40.

[0056] In the present example, the gas is changed in flow direction by the plurality of longitudinal gas passages 41, and the plurality of longitudinal gas passages 41 uniformly distribute the gas to flow into the reaction zone 11.

[0057] In a specific implementation, the grid protrusions 40 are long strips, and can be specifically cuboids or long arcs; it should be noted that the specific shape of the grid protrusions 40 is not limited, as long as it is a long strip, it can play a flow distribution role.

[0058] As shown in Figure 3 , preferably, the length h of the grid protrusions 40 is 1 / 4-1 / 3 of the short side length H of the transition zone 12 of the flow field plate.

[0059] In the present example, the length h of the grid protrusions 40 is 1 / 4 of the short side length H of the transition zone 12 of the flow field plate.

[0060] In the present example, the length of the longitudinal grid protrusions 40 is limited to be less than the width of the transition zone, so that spaces for gas flow and distribution are formed between the longitudinal gas openings 10 of the longitudinal grid protrusions 40, and spaces for gas flow and distribution are formed between the longitudinal grid protrusions 40 and the reaction zone 11, improving the uniformity of gas distribution in the reaction zone 11.

[0061] Preferably, the height of the grid protrusions 40 is consistent with the flow channel depth of the reaction zone 11, and both are 0.3-2 mm; and / or, the width of the grid protrusions 40 is consistent with the flow channel width of the reaction zone 11, and both are 0.3-2 mm.

[0062] Preferably, the height of the grid protrusions 40 is 0.5-1.5 mm, and more preferably 0.6-1 mm.

[0063] Preferably, the width of the grid protrusions 40 is 0.5-1.5 mm, and more preferably 0.6-1 mm.

[0064] As shown in Figure 2 , preferably, the edge of the central horizontal grid zone 20 close to the gas opening 10 is on the same horizontal line as the edge of the lateral vertical grid zone 30 close to the gas opening 10; and / or, the horizontal line is on the short side midline of the transition zone 12 of the flow field plate, Figure 2 which is referred to as the end short side midline of the transition zone 12.

[0065] In the present example, when the cross flow flows into the side vertical grid area 30, the left and right side vertical grid areas 30 keep the same height level, and the left and right gas distribution amounts keep uniform; the upper edge of the center horizontal grid area 20 and the side vertical grid area 30 is located at the middle line of the short side of the transition area 12, so that a wide gas distribution area is formed between the upper edge of the center horizontal grid area 20 and the side vertical grid area 30 and the gas opening 10, which is beneficial to the free flow of the gas in the area and reduces the flow resistance.

[0066] As shown in Figure 3 Preferably, the width of the center horizontal grid area 20 is consistent with the width of the gas opening 10, and the center horizontal grid area 20 is directly opposite to the gas opening 10.

[0067] In the present example, the center horizontal grid area 20 is directly opposite to the gas opening 10, the gas is uniformly distributed left and right, the width of the center horizontal grid area 20 just covers the gas opening 10, and the width of the center horizontal grid area 20 is reduced to reduce the gas resistance on the premise of ensuring that the gas can be completely changed in direction.

[0068] A fuel cell flow field plate includes a gas opening 10, a reaction area 11, and at least one combined grid type flow field transition device.

[0069] Preferably, the number of the combined grid type flow field transition devices is two, the gas opening 10 includes a gas inlet and a gas outlet, one of the combined grid type flow field transition devices is arranged between the gas inlet and the reaction area 11, and the other combined grid type flow field transition device is arranged between the gas outlet and the reaction area 11.

[0070] In the present example, the gas enters one of the combined grid type flow field transition devices from the gas inlet, reacts in the reaction area 11, and then flows out from the other combined grid type flow field transition device and the gas outlet, completing the process of gas distribution, reaction, and discharge.

[0071] In specific implementation, a plurality of grid protrusions 40 are arranged at the gas opening 10, the extension direction of the grid protrusions 40 is consistent with the gas flow direction, and adjacent two grid protrusions 40 form a gas flow space.

[0072] In other embodiments, the gas inlet and the gas outlet are arranged at the two ends of the flow field plate respectively, and the combined grid type flow field transition devices are also arranged symmetrically about the reaction area 11.

[0073] In other embodiments, the gas inlet is arranged at one end of the flow field plate, and the gas outlet is arranged at the side of the flow field plate.

[0074] The fuel cell flow field plate in the embodiment of the present application is rectangular, with a length of 300 mm, a width of 100 mm, and a thickness of 1.5 mm. The gas opening 10 has a width of 40 mm, the transition zone 12 has a length of 20 mm, the reaction zone 11 has a length of 260 mm, the flow channel of the reaction zone 11 has a length of 260 mm, a width of 1 mm, and a depth of 0.6 mm, the ridge of the flow channel has a width of 1 mm, and the number of the flow channels is 50.

[0075] The central transverse grid zone 20 has a width of 40 mm, contains 3 grid protrusions 40, the grid protrusions 40 have a length of 12.667 mm and a pitch of 1 mm, and are arranged at equal intervals; the width of the grid protrusions 40 is consistent with the width of the flow channel of the reaction zone 11, and is 1 mm; and the height of the grid protrusions 40 is consistent with the depth of the flow channel of the reaction zone 11, and is 0.6 mm.

[0076] The lateral vertical grid zone 30 has a width of 30 mm, contains 7 grid protrusions 40, the width of the grid protrusions 40 is consistent with the width of the flow channel of the reaction zone 11, and is 1 mm; the pitch of the grid protrusions 40 is 2.875 mm, and the grid protrusions 40 are arranged at equal intervals; the length of the grid protrusions 40 is 1 / 4 of the length of the short side of the transition zone 12, and is 5 mm; and the height of the grid protrusions 40 is consistent with the depth of the flow channel of the reaction zone 11, and is 0.6 mm.

[0077] In order to compare the implementation effects, two fuel cell flow field plates are used in the embodiment, the reaction zones 11 of the two flow field plates are completely consistent, and the transition zones 12 adopt the combined grid type flow field transition device of the present application and the uniform dot matrix type structure of the prior art, respectively.

[0078] The dot matrix type structure is a uniform dot matrix distributed cube structure, the side length of the cube structure is 1 mm, and the cube structure is uniformly arranged in the transition zone 12; the flow space volume accounts for 86.8% of the total transition space; and the rest of the technical parameters and materials of the two flow field plates are completely same.

[0079] The two flow field plates are simulated and tested under the same working condition, the gas velocity of the gas inlet is 11.8 m / s, the operating pressure is 1 atm, and the back pressure of the gas outlet is 0.

[0080] Figure 5 The comparison of the flow uniformity in the two flow field plates is given, and it can be seen from the figure that the present application can significantly improve the flow uniformity in the cell.

[0081] A fuel cell comprises the fuel cell flow field plate described above.

[0082] In the present example, the fuel cell with the fuel cell flow field plate of the present application has the effect of "reducing resistance and increasing efficiency", that is, under the same working conditions, the gas flow uniformity inside the fuel cell of the present application is better, the gas flow resistance is smaller, and the durability and performance of the fuel cell are improved.

[0083] Although the specific embodiments of the present application are described above, those skilled in the art should understand that this is only an example, and the protection scope of the present application is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present application, and these changes and modifications all fall within the protection scope of the present application.

Claims

1. A combined mesh flow field transition device for use between a gas opening and a reaction area of a fuel cell flow field plate, characterized by: The combined grid type flow field transition device comprises a center horizontal grid area and two side vertical grid areas, the center horizontal grid area is arranged at the gas opening of the flow field plate, and the two side vertical grid areas are arranged on both sides of the center horizontal grid area; The gas enters the center horizontal grid area through the gas opening to form a horizontal flow, the horizontal flow is uniformly distributed and converted into a uniform vertical flow through the two side vertical grid areas, and then enters the reaction area for reaction; The center horizontal grid area comprises a first substrate and a plurality of grid protrusions, the plurality of grid protrusions are arranged horizontally on the first substrate, and the plurality of grid protrusions are arranged horizontally and spaced apart on the first substrate; The side vertical grid area comprises a second substrate and a plurality of grid protrusions, the plurality of grid protrusions are arranged vertically on the second substrate, and the plurality of grid protrusions are arranged horizontally and spaced apart on the second substrate, and a vertical air channel is formed between adjacent two grid protrusions.

2. The combination grid type flow field transition device of claim 1, wherein: The length h of the grid protrusion in the side vertical grid area is 1 / 4-1 / 3 of the short side length H of the transition area of the flow field plate.

3. The combination grid type flow field transition device of claim 1 wherein: The height of the grid protrusion in the center horizontal grid area and the side vertical grid area is consistent with the flow channel depth of the reaction area, and is 0.3-2mm; And / or, the width of the grid protrusion in the center horizontal grid area and the side vertical grid area is consistent with the flow channel width of the reaction area, and is 0.3-2mm.

4. The combination grid strainer flow field transition device of claim 1, wherein: The edge of the center horizontal grid area close to the gas opening is on the same horizontal line with the edge of the side vertical grid area close to the gas opening.

5. The combination grid strainer flow field transition device of claim 4, wherein: The horizontal line is located on the short side middle line of the transition area of the flow field plate.

6. The combination grid strainer flow field transition device of claim 1, wherein: The width of the center horizontal grid area is consistent with the width of the gas opening, and the center horizontal grid area is opposite to the gas opening.

7. A fuel cell flow field plate characterized by: It comprises a gas opening, a reaction area and at least one combined grid type flow field transition device as claimed in any one of claims 1-6.

8. The fuel cell flow field plate of claim 7, wherein: The number of the combined grid type flow field transition devices is two, the gas opening comprises a gas inlet and a gas outlet, one of the combined grid type flow field transition devices is arranged between the gas inlet and the reaction area, and the other combined grid type flow field transition device is arranged between the gas outlet and the reaction area.

9. A fuel cell characterized by: It comprises the fuel cell flow field plate as claimed in any one of claims 7-8.

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