Monopole plate of fuel cell

Abstract

The utility model relates to the technical field of hydrogen fuel cells, in particular to a fuel cell monopolar plate. Comprising a plate body, the plate body is provided with a gas inlet and a gas outlet, the gas inlet and the gas outlet are communicated through a flow field area, the flow field area is located in the center area of the plate body and comprises a plurality of flow field channels, one end of each flow field channel is communicated with the gas inlet through an inlet distribution area, and the other end of each flow field channel is communicated with the gas outlet through an outlet distribution area. The flow field area further comprises a plurality of sets of boss structures, each boss structure comprises a plurality of bosses, the bosses correspond to the flow field channels in a one-to-one mode, and the height of the bosses is smaller than the width of the flow field channels. The monopolar plate has a unique distribution area structure, a flow field structure and an inlet and outlet gap bridge structure, so that the gas distribution uniformity is improved while the better drainage capacity of the monopolar plate is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of hydrogen fuel cells, in particular to a single-pole plate for a fuel cell. Background Art

[0002] As one of the core components of fuel cells, the drainage performance of the unipolar plate largely determines whether the performance of the membrane electrode can be better exerted. If the water generated by the electrochemical reaction cannot be discharged in time, it is easy to cause flooding, which in turn leads to reduced membrane electrode performance. Therefore, good drainage capacity has a great impact on the temperature distribution and water performance output of the entire fuel cell stack. Utility Model Content

[0003] Problem to be solved: Provide a monopolar plate structure with better drainage capacity.

[0004] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a fuel cell monopolar plate, comprising a plate body, a gas inlet and a gas outlet being provided on the plate body, the gas inlet and the gas outlet being connected through a flow field area, the flow field area being located in the central area of the plate body, and characterized in that: the flow field area comprises a plurality of flow field channels, one end of the flow field channel is connected to the gas inlet through an inlet distribution area, and the other end is connected to the gas outlet through an outlet distribution area, the flow field area also comprises multiple groups of boss structures, the boss structures comprise a plurality of bosses, the plurality of bosses correspond one-to-one to the plurality of flow field channels, and the height of the bosses is less than the width of the flow field channels.

[0005] Preferably, the distances between the multiple groups of boss structures decrease step by step along the direction from the gas inlet to the gas outlet.

[0006] Preferably, the specific number of the multiple groups of boss structures is six.

[0007] Preferably, an inlet bridge structure is provided at one end where the gas inlet is connected to the inlet distribution area, and an outlet bridge structure is provided at one end where the gas outlet is connected to the outlet distribution area. The cross-sectional area of the inlet bridge structure that can provide gas circulation is larger than the cross-sectional area of the outlet bridge structure that can provide gas circulation.

[0008] Preferably, the inlet bridge structure has a grooves, the outlet bridge structure has b grooves, and a is greater than b.

[0009] Preferably, the inlet distribution area is provided with a protrusion, which is close to the gas inlet and located on the extension line of the length direction of the flow field area.

[0010] Preferably, the outlet end of the outlet distribution area is in a downwardly inclined shape with a slope of 5° to 10°.

[0011] Compared with the existing technology, the utility model provides a fuel cell monopolar plate with the following beneficial effects: the step-by-step boss structure in the flow field area can effectively increase the gas flow rate and quickly carry away moisture. The boss structure is also conducive to uniform gas distribution and increased current density. The increase in current density will increase the gas flow rate, thereby promoting water discharge in multiple directions; the cross-sectional area of the inlet bridge structure is larger than the cross-sectional area of the outlet bridge structure, which increases the airflow rate under the same current density working conditions; the outlet end of the outlet distribution area is in a downward and inclined shape, which can also accelerate the discharge of water. The utility model solves the drainage problem of the monopolar plate from multiple angles. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a structural diagram of the utility model and an enlarged view of some areas.

[0013] Figure 2 It is a structural diagram of the utility model and an enlarged diagram of the flow field area.

[0014] Figure 3 It is an enlarged view of the inlet bridge structure and the outlet bridge structure of the utility model.

[0015] Figure 4 This is a graph showing the current density and gas flow rate involved in the present invention.

[0016] Explanation of the accompanying drawings: 1. Plate; 11. Flow field area; 111. Flow field channel; 12. Boss structure; 121. Boss; 2. Gas inlet; 21. Inlet bridge structure; 3. Gas outlet; 31. Outlet bridge structure; 4. Inlet distribution area; 41. Protrusion; 5. Outlet distribution area. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention will be described below with reference to the accompanying drawings in the embodiments of the present invention:

[0018] As shown in the figure, a fuel cell monopolar plate includes a plate body 1, which is provided with a gas inlet 2 and a gas outlet 3. The gas inlet 2 and the gas outlet 3 are connected through a flow field area 11. The flow field area 11 is located in the central area of the plate body 1. The flow field area 11 includes a plurality of flow field channels 111. One end of the flow field channel 111 is connected to the gas inlet 2 through the inlet distribution area 4, and the other end is connected to the gas outlet 3 through the outlet distribution area 5. The flow field area 11 also includes multiple groups of boss structures 12. The boss structure 12 includes a plurality of bosses 121. The plurality of bosses 121 correspond one-to-one with the plurality of flow field channels 111. Figure 2As shown in the figure, the length direction of the plate body 1 is defined as the X-axis, the width direction of the plate body 1 is defined as the Y-axis, and the height of the convex platform 121 protruding in the negative Y-axis direction is less than the width of the flow field channel 111. The position of point O perpendicular to the X-axis is the right end of the flow field area 11. There are six points A, B, C, D, E, and F to the left of point O in sequence. A set of convex platform structures 12 are provided on the perpendicular lines of points A, B, C, D, E, and F perpendicular to the X-axis. The number of convex platforms 121 included in each set of convex platform structures 12 is the same as the number of flow field channels 111; the distance between O and A is d1, the distance between A and B is d2, the distance between B and C is d3, the distance between C and D is d4, the distance between D and E is d5, and the distance between E and F is d6. Along the positive X-axis direction, the distance between the multiple sets of convex platform structures 12 gradually decreases. One of the change methods is d6 = d5 < d4 = d3 < d2 = d1. The purpose of such a distribution is to gradually increase the pressure drop inside the flow field channel 111, so as to ensure that while increasing the medium flow rate, the gas longitudinal transfer effect is improved. When the medium flow rate increases, the water generated by the reaction will be carried away by the fast-flowing medium, and the good gas longitudinal transfer effect promotes the more uniform distribution of the gas in the flow field area.

[0019] The function of the convex platform 121 is to reduce the local cross-sectional area of the flow field channel 111, increase the local flow rate, improve the medium transmission speed, quickly carry away the water generated by the reaction, and at the same time help to increase the reactant concentration in the flow channel. Increasing the concentration of the medium can increase the limiting current density j

[0025] , , , conc , ,

[0024] , reduce the concentration loss η conc , increase the output voltage V, and the principle is as follows:

[0020] Limiting current density j L As the reactant concentration in the flow channel changes as follows,

[0021]

[0022] Among them, j L is the limiting current density A / cm 2 ; n is the number of transferred electrons; F is the Faraday constant C / mol; D eff is the effective diffusivity; is the reactant concentration in the flow channel; σ is the diffusion layer thickness mm;

[0023] Concentration loss η conc and the limiting current density j L are related as follows:

[0024]

[0025] Among them, η concis the concentration loss; R is the ideal gas constant J / (mol·K); T is the temperature K; n is the number of transferred electrons; F is the Faraday constant C / mol; α is the transmission coefficient; j is the current density A / cm 2 ;j L is the limiting current density A / cm 2

[0026] Output working voltage V and concentration loss η conc The relationship is as follows:

[0027] V=E-η act -η ohm -η conc ;

[0028] Where V is the output voltage; E is the Nernst voltage; η act is the activation loss; η ohm is the ohmic loss; η conc is the concentration loss:

[0029] The above design is also based on the following principle: assuming the total flow rate is Q, the outlet area is A, and the flow velocity is v, Q = v·A shows that when the total flow rate Q remains unchanged, the outlet area A becomes smaller, resulting in an increase in the flow velocity v.

[0030] Therefore, in order to increase the gas flow rate due to the small outlet area, improvements are made to the gas inlet 2 and the gas outlet 3. An inlet bridge structure 21 is provided at the end of the gas inlet 2 connected to the inlet distribution area 4, and an outlet bridge structure 31 is provided at the end of the gas outlet 3 connected to the outlet distribution area 5. According to the above principle, the cross-sectional area of the inlet bridge structure 21 for gas flow is larger than the cross-sectional area of the outlet bridge structure 31 for gas flow, which can increase the gas flow rate. The inlet bridge structure 21 has a groove, and the outlet bridge structure 31 has b grooves. If a is greater than b, the gas flow rate can be increased. The following is obtained in the simulation software: Figure 4 The results shown are as follows: Curve Y1 is the simulation result obtained when a is 30 and b is 20, and Curve Y2 is the simulation result obtained when a is 30 and b is 30. The independent variable on the horizontal axis is the current density, and the dependent variable is the gas flow rate. The number of grooves in the outlet bridge structure 31 is less than the number of grooves in the inlet bridge structure 21:

[0031] Y1=-14.323X 5 +115.77X 4 -360.96X 3 +541.03X 2 -381.27X+109.96;

[0032] The number of grooves in the outlet bridge structure (31) is equal to the number of grooves in the inlet bridge structure (21):

[0033] Y2=0.4735X4 +4.6086X 3 -29.962X 2 +56.642X-22.763;

[0034] Depend on Figure 4 It can be seen that under the same current density conditions, the gas flow rate when a is greater than b is greater than the gas flow rate when a is equal to b.

[0035] The uniform distribution of gas in the flow field area 11 is also conducive to the discharge of water. The flow field channel 111 on the edge of the flow field area 11 is close to the gas inlet 2, which can easily lead to excessive gas distribution. Therefore, a protrusion 41 is provided in the inlet distribution area 4. The protrusion 41 is close to the gas inlet 2 and is located on the extension line of the length direction of the flow field area 11. The protrusion 41 plays a role in blocking excessive gas from entering the edge flow field channel 111, thereby promoting the uniform distribution of gas. Then, the smooth discharge of water and gas at the gas outlet 3 is also very critical. The outlet end of the outlet distribution area 5 is connected to the gas outlet 3 in a downward and inclined shape with an inclination of 5° to 10°. This inclined setting is conducive to the timely discharge of liquid water generated by the reaction. Taking into account the size and space of the entire plate, the inclination is set to 5° to 10°.

[0036] In summary, the step-by-step boss structures 12 in the flow field area 11 and the cross-sectional area of the inlet bridge structure 21 being larger than the cross-sectional area of the outlet bridge structure 31 can effectively increase the gas flow rate and quickly carry away moisture. The outlet end of the outlet distribution area 5 is in a downward and inclined shape, which can also accelerate the discharge of water. The boss structure 12 is also conducive to uniform gas distribution and increased current density. The utility model can better solve the drainage problem of the monopolar plate.

[0037] The above embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A fuel cell monopolar plate, comprising a plate body (1), wherein the plate body (1) is provided with a gas inlet (2) and a gas outlet (3), wherein the gas inlet (2) and the gas outlet (3) are connected via a flow field region (11), and the flow field region (11) is located in a central region of the plate body (1), and wherein: The flow field region (11) includes a plurality of flow field channels (111), one end of the flow field channel (111) is connected to the gas inlet (2) through the inlet distribution area (4), and the other end is connected to the gas outlet (3) through the outlet distribution area (5). The flow field region (11) also includes multiple groups of boss structures (12), and the boss structures (12) include a plurality of bosses (121). The plurality of bosses (121) correspond one-to-one to the plurality of flow field channels (111), and the height of the bosses (121) is less than the width of the flow field channels (111).

2. The fuel cell monopolar plate according to claim 1, wherein: The distances between the multiple groups of boss structures (12) decrease gradually along the direction from the gas inlet (2) to the gas outlet (3).

3. The fuel cell monopolar plate according to claim 2, wherein: The specific number of the multiple groups of boss structures (12) is six groups.

4. The fuel cell monopolar plate according to claim 1, wherein: An inlet bridge structure (21) is provided at one end of the gas inlet (2) connected to the inlet distribution area (4), and an outlet bridge structure (31) is provided at one end of the gas outlet (3) connected to the outlet distribution area (5). The cross-sectional area of the inlet bridge structure (21) available for gas circulation is larger than the cross-sectional area of the outlet bridge structure (31) available for gas circulation.

5. The fuel cell monopolar plate according to claim 4, wherein: The inlet bridge structure (21) has a number of grooves, the outlet bridge structure (31) has b number of grooves, and a is greater than b.

6. The fuel cell monopolar plate according to claim 5, wherein: The inlet distribution area (4) is provided with a protrusion (41), which is close to the gas inlet (2) and located on the lengthwise extension line of the flow field area (11).

7. The fuel cell monopolar plate according to claim 6, wherein: The outlet end of the outlet distribution area (5) is in a downwardly inclined shape with a slope of 5° to 10°.

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