Study of Transport Phenomena in Flowfield and Diffusion Media of a Proton Exchange Membrane Fuel Cell
Proton exchange membrane fuel cells (PEMFC) are a green electrochemical technology that is rapidly gaining traction in the automotive industry and the like. Major components to the fuel cell are the flow field plates and the porous gas diffusion media (GDM) that transport reactants to, and products away from the catalyst layer where the reactions occur to produce heat water and electricity. These components can enhance or hinder fuel cell performance, efficiency, and the rate of degradation via mass transport mechanisms, especially at high power output. Our work begins with a top-level examination of the three most common flow field channel distribution patterns used in research, the parallel channel, single channel serpentine and multiple channel serpentine designs, using both computational methods and lab-built fuel cells. Using multiple channels significantly improved gas distribution across the electrode area but faced water flooding issues due to the low pressure drop. To improve transport focus was then given to the flow channel design. We designed the wavy, 2D-nozzle, and 3D-nozzle channel designs which feature alternating width, height, and direction from inlet to outlet to alter the flow path. Using the limiting current method to quantify the oxygen transport resistance (OTR) we discovered that with our 3D-nozzle design OTR reduced approximately 12% versus the straight channel design at the same current draw. Additionally, the maximum power at high humidity conditions was increased from 1.6 to 2.0 Amp per centimeter square with Toray-060 GDM and 2.6 to 3.1 Amp per centimeter square with Freudenberg H23C8 GDM at 0.3 volts. The 3D-Nozzle design has shown improved OTR and value for further investigation and optimization with the potential of use in commercial PEMFC.