(146b) Operation of Polymer Electrolyte Membrane Fuel Cells with Dry Feeds. Design and Operating Strategies

The operation of polymer electrolyte membrane fuel cells (PEMFCs) with dry feeds has been examined with different fuel cell flow channel designs as functions of pressure, temperature and flow rate. Auto-humidified (or self humidifying) PEMFC operation is improved at higher pressures and low gas velocities where axial dispersion enhances ?back-mixing? of the product water with the dry feed. We demonstrate auto-humidified operation of the channel-less, self-draining fuel cell operation from 25 to 115°C with dry feeds. Design and operating requirements are derived for the auto-humidified operation. We show why the traditional serpentine flow design is incompatible with autohumidified operation. New engineering designs which improve mixing and exploit gravity offer substantial benefits for simplicity of operation and control including: the ability to self drain reducing flooding, the ability to uniformly disperse water removing current gradients and the ability to operate on dry feeds eliminating the need for humidifiers.