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5 Commonest Flow-Field Channel Designs for Fuel Cells

The main objective when design flow fields is balancing the pressure drop and the amount of gas that is distributed to the GDL and catalyst layers. Parallel, serpentine and interdigitated designs are the most popular for fuel cell channels. In relatively small fuel cells, the serpentine design is usually used because the hydrogen reaction is not rate limiting and water blockage in the humidified anode can happen.

In the image below, you can see a serpentine flow field design. The flow path is continuous and relatively efficient in distributing gas across the fuel cell. However, since the path is longer than in other designs, pressure loss might be a problem. One advantage of the design if that a block in the path does not compromise activity downstream. A disadvantage is that more gas needs to be input into the fuel cell because the design favors the depletion of the components. Another disadvantage is the build up of water in the cathode during extended periods of operation of the fuel cell. 

 

The image below shows an attempt at fixing some of the problems of the above design. In this geometry, the multiple serpentine channels limit the pressure drop and reduce the amount of power required to pressurize the gases. This geometry also helps prevent the build of liquid water in the cathode side. 

The image below shows the parallel flow field geometry for gas channels. The advantages over the previous designs are that the channels demand less mass flow per channel, the more evenly distribution of gas and a lower pressure drop. One disadvantage is that blockage of the channels is even more undesirable than in the other designs because of the creation of dead zones and excess of mass flow in other channels. 

The last design is the interdigitated one. Since the channels are dead-ended, the reactant flow is forced to go through the porous reactant layer to reach the flow channels connected to the stack manifold. One advantage of this geometry is the easier removal of liquid water in the cathode side. 


Source: https://www.researchgate.net/publication/311886534_Effect_Of_Geometric_Design_Of_The_Flow_Fields_Plat_On_The_Performance_Of_A_PEM_Fuel_Cell_A_Review



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