CN114243050B - Deeply shallow flow field plate with liquid water adaptive diversion structure - Google Patents

Abstract

The invention discloses a depth gradually shallower flow field plate with a liquid water self-adaptive flow guiding structure, which comprises the following structures: and reactant inlets and outlets, a plurality of ridges and flow channels distributed on the flow field plate, and self-adaptive structures arranged on the grooves of the gradually shallower flow channels. When liquid water stored in the flow channel exists, the self-adaptive structures can absorb water and expand, the distance between every two adjacent self-adaptive structures is shortened, even the adjacent self-adaptive structures are attached together, and the cross-sectional area of the flow channel is reduced; when no liquid water is stored in the flow channel, the self-adaptive structure can evaporate the liquid water in the flow channel under the conditions of battery operation temperature and reactant purging, so that the flow channel has a larger cross-sectional area. The self-adaptive structure added by the invention can be changed in a self-adaptive way according to the change of the liquid water content in the flow channel, when the liquid water content is more, the flow speed of the reactant is accelerated, and the liquid water discharge can be accelerated; when the liquid water content is low, the two-phase flow resistance is low, and the pumping power consumption can be reduced.

Description

Deeply shallow flow field plate with liquid water adaptive diversion structure

Technical field

The invention belongs to the field of fuel cells, and specifically relates to a shallow-depth flow field plate structure with a liquid water adaptive flow guide structure.

Background technique

Hydrogen is a bridge connecting renewable energy and traditional fossil energy. Through the development and utilization of hydrogen fuel cells, the vision of future changes in clean energy utilization can be realized.

Fuel cells have developed rapidly due to their advantages of reliable operation, clean and efficient operation, less harmful electrochemical reaction products, and simple operation. They have broad prospects for commercial application and continuous breakthroughs in core technology. Therefore, they are regarded as the most promising energy and power devices. one.

The flow field plate is one of the important components of the fuel cell. The design, production and materials of the flow field plate will directly affect the life, volume, cost, quality and other aspects of the battery. Its main function is to distribute reaction gases, conduct electrons and discharge The liquid water produced by the reaction, therefore, the flow field plate of the fuel cell must have good conductivity and drainage capabilities.

In order to improve battery performance, research has designed gradually shallower flow channels. Compared with straight flow channels, this gradually shallower flow channel can increase oxygen concentration, promote mass transfer, and accelerate the discharge of liquid water. However, the shape and size of traditional gradually shallower flow channels They are all fixed and cannot adapt to variable operating conditions. When there is no accumulation of liquid water in the flow channel, the resistance to the two-phase flow is greater and the pump power is consumed, thereby reducing the net power of the battery.

Contents of the invention

In response to the above shortcomings, the present invention adds an adaptive structure that can adaptively change the liquid water content on the gradually shallower flow channel plane, so that the flow field can adapt to different working conditions and achieve the effect of increasing the net power of the battery.

In order to achieve the above objects, the present invention adopts the following technical solutions:

The invention provides a shallow-depth flow field plate with an adaptive structure for liquid water, which is characterized by: reactant inlets and outlets, a number of ridges and flow channels distributed on the flow field plate, and automatic flow fields fixed in grooves with glue. Adapt to the structure.

Furthermore, an adaptive structure is added to the gradually shallower flow channel. When there is accumulated liquid water in the flow channel, the adaptive structure absorbs water and expands, and the depth of the flow channel further gradually becomes shallower along the direction of reactant flow; when there is no more accumulated liquid in the flow channel, When using water, the adaptive structure can dehydrate and shrink when heated at the battery operating temperature or purged by reaction gas. The cross-sectional area of the flow channel becomes larger, and the flow channel remains a gradually shallower flow channel, thereby achieving a gradually shallower flow channel depth to the liquid state. Adaptive changes in water content.

Furthermore, the adaptive structure is arranged in multiple sections on the same flow channel and distributed evenly. The length before water absorption is 1mm to 6mm, and the width is 1/3 to 2/3 of the width of the flow channel.

Further, the projection of the adaptive structure on the flow channel plane is rectangular, triangular, trapezoidal or circular.

Further, the adaptive structure does not dissolve at battery operating temperatures.

Furthermore, the moisture-sensitive materials used in the adaptive structure are harmless to membrane electrodes and reach water saturation within 5 to 7 minutes in a flooded environment. Under 80°C conditions, the saturated linear expansion of water absorption is 50% to 300%.

Furthermore, there is a groove structure on the flow channel plane, and part of the adaptive structure is a convex structure that matches the groove.

Furthermore, the optimal dimensions of the groove structure in the flow channel are: the length is 1mm~2mm, the width is 0.2mm~0.3mm, and the depth is 0.02mm~0.2mm.

Further, the adaptive structure is adhered to the groove structure of the flow channel plane using glue that is harmless to the membrane electrodes.

Furthermore, the adaptive structure is suitable for serpentine flow fields, bionic flow fields, parallel flow fields, combined flow fields, and interdigitated flow fields.

To sum up, the present invention has the following beneficial effects:

The adaptive structure added in the present invention can adaptively change according to changes in the liquid water content in the flow channel. When there is accumulated liquid water in the flow channel, the adaptive structure absorbs water and expands, further reducing the cross-sectional area of the shallower flow channel along the reactant flow direction, thereby increasing the reactant flow rate and accelerating the discharge of liquid water; when the flow channel When there is no more accumulated liquid water, the two-phase flow resistance is smaller, which can reduce pump power consumption. In addition, the adaptive structure can guide the transfer of reactants to the diffusion layer.

Picture description:

Figure 1 is a structural plan view of the fuel cell flow field plate before the adaptive structure absorbs water and expands;

Figure 2 is an axial view of the fuel cell flow field plate structure before the adaptive structure absorbs water and expands;

Figure 3 is a structural plan view of the fuel cell flow field plate after the adaptive structure is saturated with water and expands;

Figure 4 is an axial view of the fuel cell flow field plate structure after the adaptive structure is saturated and expanded by water absorption;

Figure 5 is a partial comparison of the adaptive structure in area A before and after saturated water absorption and expansion (left picture: before water absorption; right picture: after saturated water absorption);

Figure 6 is a schematic diagram of the fixation method before the adaptive structure absorbs water and expands;

In the picture: 1 reactant inlet, 2 reactant outlet, 3 flow channels, 4 ridges, 5 adaptive structure, 6 glue.

Detailed ways:

The specific implementation modes of the present invention are further described below in conjunction with the accompanying drawings and examples:

As shown in Figures 1 and 2, several adaptive structures 5 are arranged on the gradually shallower flow channel 3, so that the flow field has a certain ability to adapt to liquid water. The reactants flow from the inlet 1 into the flow channel 3 formed between adjacent ridges 4. When flowing through the adaptive structure 5, the disturbance of the air flow will be increased, guiding the reactants to be transported to the gas diffusion layer, and the reactants will reach the catalytic layer to undergo electrochemistry. reaction, the liquid water generated will flow into the flow channel 3 through the diffusion layer, and flow out from the outlet 2 together with the reaction gas.

As shown in Figures 3 and 4, when there is accumulated liquid water in the flow channel 3, the adaptive structure 5 absorbs water and gradually expands, and the volume becomes larger. After the water absorption reaches saturation, the adjacent adaptive structures 5 in each flow channel 3 will fit together, and the cross-sectional area of the gradually shallower flow channel 3 will be further reduced, which can increase the concentration of reactants, reduce the influence of concentration polarization, and Increasing the reactant flow rate is beneficial to the discharge of liquid water.

As shown in Figure 5, when there is no more accumulated liquid water in the flow channel 3, the internal water in the adaptive structure 5 will evaporate under the conditions of the battery's own operating temperature and reaction gas purge, causing it to dehydrate and shrink, gradually becoming shallower. The flow channel cross-sectional area becomes larger. Compared with the adaptive structure 5 after absorbing water and expanding, the two-phase flow resistance in the flow channel 3 is reduced. The adaptive change of the flow field to the liquid water content in the flow channel is realized through the water absorption expansion and syneresis shrinkage of the adaptive structure 5, which can further increase the output power and net power of the fuel cell based on the original gradually shallower flow channel.

As shown in Figure 6, there is a groove structure on the plane of the gradually shallow flow channel 3. A part of the adaptive structure 5 is a convex structure corresponding to the groove. Glue 6 that is harmless to the membrane electrode is used to connect the adaptive structure 5 and The grooves are pasted together, and the mortise and tenon structure and glue 6 are used to fix the adaptive structure 5. In addition, all the contact surfaces between the adaptive structure 5 and the groove are adhered with glue 6, which can limit the expansion of the adaptive structure 5 in the groove and ensure that the adaptive structure exposed in the flow channel 3 Achieve ideal expanded size.

Claims (5)

1. A depth progressively shallower fuel cell flow field plate with liquid water adaptive structure, characterized in that: comprises a reactant inlet (1), a reactant outlet (2), a plurality of ridges (4) and flow channels (3) which are distributed on a flow field plate, and a self-adaptive structure (5) which is fixed in grooves of the flow channels (3) by glue (6); the flow channel (3) is a gradually shallower flow channel, and the depth of the flow channel (3) gradually becomes shallower along the flowing direction of the reactant; the self-adaptive structures (5) are arranged on the same flow channel (3) in a multi-section mode and are uniformly distributed, the length of each section before water absorption is 1 mm-6 mm, and the width of each section is 1/3-2/3 of the width of the flow channel; the adaptive structure (5) does not dissolve at the battery operating temperature; the humidity-sensitive material used by the self-adaptive structure (5) is harmless to the membrane electrode, and is saturated by water absorption within 5-7 min in a water flooding environment, and the saturated linear expansion degree of water absorption is 50% -300% under the condition of 80 ℃; the plane of the flow channel (3) is provided with a groove structure, and one part of the self-adaptive structure (5) is a convex structure which is matched with the groove; adding an adaptive structure (5) into the gradually shallower flow passage, and when liquid water stored in the flow passage (3) exists, the adaptive structure (5) absorbs water and expands, and after the water absorption reaches saturation, adjacent adaptive structures in each flow passage are attached together; the depth of the flow channel (3) is further gradually shallower along the flow direction of the reactant; when the accumulated liquid water is not present in the runner (3), the self-adaptive structure (5) can be dehydrated and contracted under the condition of heating or blowing of the reaction gas at the battery operating temperature, the cross section area of the runner (3) is increased, and the runner (3) is still a gradually shallower runner, so that the self-adaptive change of the depth of the gradually shallower runner to the liquid water content is realized.

2. A fuel cell flow field plate as claimed in claim 1, wherein: the projection of the self-adaptive structure (5) on the plane of the flow channel (3) is rectangular, triangular, trapezoidal or circular.

3. A fuel cell flow field plate as claimed in claim 1, wherein: groove structure size in runner (3): the length is 1 mm-2 mm, the width is 0.2 mm-0.3 mm, and the depth is 0.02 mm-0.2 mm.

4. A fuel cell flow field plate as claimed in claim 1, wherein: the self-adaptive structure (5) is adhered to the groove structure of the plane of the flow channel (3) by using glue (6) harmless to the membrane electrode.

5. A fuel cell flow field plate as claimed in claim 1, wherein: the self-adaptive structure (5) is suitable for a serpentine flow field, a bionic flow field, a parallel flow field, a combined flow field or an interdigital flow field.