(498e) Design and Strategies for Operating Pem Fuel Cells with Dry Feeds

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 so axial dispersion enhances ?back-mixing? of the product water with the dry feed. We demonstrate autohumidified operation of the channel-less, self-draining fuel cell, based on a stirred tank reactor; data is presented showing auto-humidified operation from 25 to 115ºC at 1 and 3 atm. Design and operating requirements are derived for the auto-humidified operation of the channel-less, self-draining fuel cell. The auto-humidified self-draining fuel cell outperforms a fully humidified serpentine flow channel fuel cell at high current densities. Fuel cells designed with serpentine flow channels were not able to operate with dry feeds at temperatures above 50-60ºC. The new design offers 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. Additionally, the design lends itself well to a modular design concept.