CN110165242B - A PEM battery flow field plate structure with multi-level flow channel width - Google Patents

Abstract

The invention discloses a PEM battery flow field plate structure with multi-level flow channel width, which comprises a plate body, wherein a reaction gas inlet and a reaction gas outlet are formed in the plate body; a plurality of flow channel shoulders are arranged in each stage of flow channel field, a single flow channel is formed by two adjacent flow channel shoulders, and the width of the single flow channel of each stage of flow channel field is gradually reduced. The invention has the effective effects that: the invention designs the flow channel field structure with the width changing of the multilevel flow channel by conforming to the generalized Ruili law, is similar to a multilevel pore structure, has more uniform distribution of materials, reduces the water transmission resistance, and improves the comprehensive performance of the flow field plate of the proton exchange membrane fuel cell.

Description

A PEM battery flow field plate structure with multi-level flow channel width

technical field

The invention relates to the technical field of fuel cells, in particular to a PEM cell flow field plate structure with multi-level flow channel widths.

Background technique

The proton exchange membrane fuel cell (PEM cell) uses hydrogen and oxygen as fuel, diffuses into the gas diffusion layer through the gas flow channel of the fuel cell bipolar plate, and reaches the catalytic layer to generate electricity through an electrochemical reaction, which directly converts chemical energy into electrical energy. , is an environmentally friendly power generation device. Since it is not limited by the Carnot cycle, the energy conversion rate of proton exchange membrane fuel cells is extremely high, up to 60%.

The flow field plate of the proton exchange membrane fuel cell is a kind of electrode plate with flow channels. The flow field plate plays the role of isolating the reactant gas in the battery, realizing the assembly connection of the battery and acting as an electron channel. The gas flows on the flow field plate engraved with the flow channel. The gas flow channel is the main channel for the reaction gas to be transported from the outside to the inside of the cell and the product to be discharged. The structure and shape of the flow field will affect the transmission state and utilization of the reaction gas. The availability of gas in the cell and whether water can be drained will affect overall cell performance. Therefore, designing a reasonable flow field is the key to the design of proton exchange membrane fuel cells. A reasonable flow field can not only ensure that the gas is evenly distributed in the entire reaction active area of the battery, so that the chemical energy can be fully converted into electrical energy; it also allows the water generated by the reaction to be smoothly discharged from the flow channel to avoid flooding, so as to achieve the best conversion efficiency of the battery and output performance.

At present, the commonly used proton exchange membrane fuel cell flow fields include parallel flow field and serpentine flow field. As shown in Figure 1, the parallel flow field is a typical fuel cell flow field, including an inlet flow channel 3, an outlet flow channel 4, and a branch flow channel 5. The inlet of each branch flow channel 5 is connected to the inlet flow channel 3, The outlet of each branch flow channel 5 is connected to the outlet flow channel 4 , and the gas enters from the inlet flow channel 3 and is discharged from the outlet flow channel 4 . Due to the short path of the gas in the parallel flow channel, the inlet pressure loss is small, and the reaction gas is evenly distributed. However, the flow rate in the flow channel is small, and the generated liquid water cannot be discharged in time, resulting in flooding. The serpentine flow field has a large reaction gas flow rate and a large pressure drop, which can timely discharge the water produced by the reaction out of the flow channel to avoid flooding. However, for a large area of serpentine flow field, the pressure drop is too large and the gas distribution is uneven.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a PEM battery flow field plate structure with a multi-layered flow channel width that improves the pressure drop of the flow field and the gas uniformity in view of the deficiencies of the prior art.

The technical scheme adopted in the present invention is: a PEM battery flow field plate structure with a multi-level flow channel width, comprising a plate body, and a reaction gas inlet and a reaction gas outlet are opened on the plate body, and the reaction gas inlet and the reaction gas outlet are provided with a reaction gas inlet and a reaction gas outlet. There are multi-stage flow channel fields connected in sequence between them. The first-stage flow channel field is connected with the reaction gas inlet, and the last-stage flow channel field is connected with the reaction gas outlet. There are multiple flow channel shoulders in each stage flow channel field, and two adjacent flow channel fields are arranged. The shoulder forms a single flow channel, and the width of the single flow channel of the flow channel field at all levels decreases in turn.

According to the above scheme, the single runners in the runner fields at all levels are evenly spaced and distributed in parallel, and the width of the single runners in the runner fields at all levels satisfies the following relationship:

A ₁ ² =A ₂ ² +A ₃ ² +A ₄ ² +...+A _n-3 ² +A _n-2 ² +A _n-1 ² +A _n ² ;

A ₂ ² =A ₃ ² +A ₄ ² +A ₅ ² +...+A _n-3 ² +A _n-2 ² +A _n-1 ² +A _n ² ;

...

A _n-3 ² =A _n-2 ² +A _n-1 ² +A _n ² ;

A _n-2 ² =A _n-1 ² +A _n ² .

In the above formula, A ₁ is half the width of the single runner in the first-stage runner field, A ₂ is half the width of the single runner in the second-stage runner field, ..., An is the single-flow channel in the _n -th stage runner field. half the width of the track.

According to the above scheme, each single flow channel in the same stage is connected with the flow channel field of the previous stage.

According to the above solution, the plate body is provided with an intake main flow channel communicating with the reaction gas inlet, and the intake main flow channel is communicated with a single flow channel in the first-stage flow channel field.

According to the above solution, the plate body is provided with a main gas outlet flow channel communicating with the outlet of the reaction gas, and the main gas outlet flow channel is communicated with a single flow channel in the final flow channel field.

According to the above solution, several bolt holes are provided at intervals along the four periphery of the plate body, and are connected to other structures of the PEM battery through connecting bolts.

The effective effects of the present invention are as follows: the present invention utilizes the generalized Murray's law to design a flow channel field structure with variable multi-stage flow channel width, which is similar to a multi-stage pore structure, the distribution of materials is more uniform, the water transmission resistance is reduced, and the protons are improved. The comprehensive performance of the flow field plate of the exchange membrane fuel cell, thereby improving the efficiency of the entire fuel cell; in addition, compared with the existing ordinary parallel flow field, the flow field plate of the present invention has a larger pressure drop, which is more conducive to drainage and avoids water flooded.

Description of drawings

Figure 1 shows a traditional equal channel width parallel flow field plate.

FIG. 2 is a schematic structural diagram of a specific embodiment of the present invention.

FIG. 3 is a comparison diagram of the performance curves of the proton exchange membrane fuel cell when the flow field plate and the parallel flow field of the present invention are used respectively.

Figure 4 is a cloud diagram of the mass fraction distribution of cathode water at 0.7v under the calculation conditions of the embodiment.

Among them: 1. Reactive gas inlet; 2. Reactive gas outlet; 3. Inlet main flow channel; 4. Outlet main flow channel; 5. First-stage flow channel field; 6. Last-stage flow channel field; 8. Single channel; 9. Plate body.

Detailed ways

For a better understanding of the present invention, the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

As shown in FIG. 2, a PEM battery flow field plate structure with a multi-level flow channel width includes a plate body 9, and the plate body 9 is provided with a reaction gas inlet 1 and a reaction gas outlet 2. Between the reactive gas outlets 2, there are multi-stage flow channel fields connected in sequence, the first-stage flow channel field 5 is communicated with the reaction gas inlet 1, and the last-stage flow channel field 6 is communicated with the reaction gas outlet 2; The channel shoulder 7, two adjacent channel shoulders 7 form a single channel 8, and the width of the single channel 8 of the channel fields at all levels decreases sequentially.

Preferably, the single flow channels 8 in the flow channel fields of all levels are evenly spaced and distributed in parallel, and each single flow channel 8 in the same stage is connected with the flow channel field of the previous stage; the width of the single flow channel 8 of the flow channel field of each level satisfies The following relationship:

A ₁ ² =A ₂ ² +A ₃ ² +A ₄ ² +...+A _n-3 ² +A _n-2 ² +A _n-1 ² +A _n ² ;

A ₂ ² =A ₃ ² +A ₄ ² +A ₅ ² +...+A _n-3 ² +A _n-2 ² +A _n-1 ² +A _n ² ;

...

A _n-3 ² =A _n-2 ² +A _n-1 ² +A _n ² ;

A _n-2 ² =A _n-1 ² +A _n ² .

In the above formula, A ₁ is half the width of the single flow channel 8 in the first-stage flow channel field 5, A ₂ is half the width of the single flow channel 8 in the second-stage flow channel field, ..., An is the _n -th stage flow channel field. Half of the width of the inner single channel 8.

Preferably, the plate body 9 is provided with an intake main flow channel 3 that communicates with the reaction gas inlet 1 , and the intake main flow channel 3 communicates with the single flow channel 8 in the first-stage flow channel field 5 .

Preferably, the plate body 9 is provided with a main gas outlet flow channel 4 communicating with the reaction gas outlet 2 , and the main gas outlet flow channel 4 communicates with the single flow channel 8 in the final flow channel field 6 .

Preferably, a plurality of bolt holes are formed along the four edges of the plate body 9 at uniform intervals, and are connected to other structures of the PEM battery through connecting bolts.

In this embodiment, the main intake flow channel 3 has a depth of 1 mm and a width of 3 mm; the air outlet main flow channel 4 has a depth of 1 mm and a width of 3 mm. There are six flow channel shoulders 7 in the first-stage flow channel field 5, forming a total of seven single flow channels 8. The single flow channel 8 has a depth of 1mm and a width of 2.8mm; the second-stage flow channel field has ten The six runner shoulders 7 form a total of seventeen single runners 8. The single runner 8 has a depth of 1mm and a width of 2mm; the single runner 8 in the third-stage runner field has a depth of 1mm and a width of 1.6mm; The depth of the single flow channel 8 in the stage flow channel field 6 is 1 mm and the width is 1 mm.

其中α与传输类型有关，一般为2或3；X是孔隙传输过程中质量变化率。本发明基于默里定律设计多级流道宽度变化的流场板结构，气体的分布更均匀，水传输阻力更小，提高了PEM电池性能。Both plants and animals have similar tissue transport structures. These tissues contain a well-defined network of voids. The size ratio of the pores has evolved to maximize mass transport and reaction rates, with the least resistance during mass transport. Transport efficiency At the highest, this optimized hierarchical design conforms to Murray's law. The generalized Murray's law expresses the pore size relationship for hierarchical pores as

where α is related to the transport type, generally 2 or 3; X is the mass change rate during pore transport. Based on Murray's law, the invention designs a flow field plate structure with a multi-stage flow channel width variation, the gas distribution is more uniform, the water transmission resistance is smaller, and the performance of the PEM battery is improved.

The performance curves of the proton exchange membrane fuel cell using the flow field plate structure of the present invention and the traditional parallel flow field structure are shown in Fig. structure). Under the operating conditions of the fuel cell temperature of 80° C. and the pressure of 0.15 MPa, the mass flow rate of hydrogen gas of 1.5e-06kg/s and air of 2.6e-05kg/s were introduced. Under the condition that the open circuit voltage is 1V, change the voltage and record the corresponding current density. It can be seen from FIG. 3 that the performance of the PEM battery using the flow field plate structure of the present invention is higher than that of the traditional parallel flow channel, and the current density is higher. Positions with small track widths have relatively large velocities and are more uniformly distributed. It can be concluded that the flow field plate structure of the present invention not only maintains the advantages of uniform distribution of parallel flow field cells, but also enhances the uniformity of gas distribution and improves the overall performance of the proton exchange membrane fuel cell. The mass fraction distribution cloud diagram of cathode water at 0.7v under the calculation conditions of the embodiment is shown in Fig. 4 . From left to right is the direction from the inlet to the outlet, the mass fraction of water at the inlet is lower than other positions, and the mass fraction of water in the flow channel area is evenly distributed.

Finally, it should be noted that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art can still understand the above The technical solutions recorded in each embodiment are modified, or some technical features thereof are equivalently replaced, but any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the present invention. within the scope of protection.

Claims (5)

1. a PEM battery flow field plate structure of a multi-level flow channel width, is characterized in that, comprises plate body, and is provided with reaction gas inlet and reaction gas outlet on described plate body, between reaction gas inlet and reaction gas outlet There are multiple flow channel fields connected in sequence, the first stage flow channel field is connected with the reaction gas inlet, and the last stage flow channel field is connected with the reaction gas outlet; each stage flow channel field is provided with multiple flow channel shoulders, two adjacent flow channel shoulders A single flow channel is formed, and the width of the single flow channel of the flow channel field at each level decreases in turn; the single flow channel in the flow channel field at each level is evenly spaced and distributed in parallel, and the single flow channel width of the flow channel field at each level satisfies the following relationship: A ₁ ² =A ₂ ² +A ₃ ² +A ₄ ² +...+A _n-3 ² +A _n-2 ² +A _n-1 ² +A _n ² ; A ₂ ² =A ₃ ² +A ₄ ² +A ₅ ² +...+A _n-3 ² +A _n-2 ² +A _n-1 ² +A _n ² ; ... A _n-3 ² =A _n-2 ² +A _n-1 ² +A _n ² ; A _n-2 ² =A _n-1 ² +A _n ² , In the above formula, A ₁ is half the width of the single runner in the first-stage runner field, A ₂ is half the width of the single runner in the second-stage runner field, ..., An is the single-flow channel in the _n -th stage runner field. half the width of the track. 2 . The PEM battery flow field plate structure with multi-level flow channel widths according to claim 1 , wherein each single flow channel in the same stage is communicated with the flow channel field of the previous stage. 3 . 3. the PEM battery flow field plate structure of the multi-level flow channel width as claimed in claim 1, is characterized in that, on the described plate body, is provided with the main flow channel of air intake that is communicated with the reaction gas inlet, and the main flow channel of air intake is provided. It communicates with the single runner in the first-stage runner field. 4. The PEM battery flow field plate structure of the multi-layered flow channel width as claimed in claim 1, wherein the plate body is provided with a main gas outlet flow channel that communicates with the reaction gas outlet, and the main gas outlet flow channel is connected to the end of the gas outlet. Single runner connection in the stage runner field. 5. The PEM battery flow field plate structure with multi-level flow channel width as claimed in claim 1, characterized in that, several bolt holes are provided along the four periphery of the plate body at intervals, and are connected with other structures of the PEM battery through connecting bolts.

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