An Open Cathode Fuel Cell for Atmospheric Flight

An open cathode proton exchange membrane fuel cell (PEMFC) could be an ideal power source for unmanned air vehicles because the motion of the aircraft through the atmosphere can be leveraged to provide oxygen to the PEMFC and extract waste heat, eliminating many traditional balance of plant components such as air and coolant pumps, bipolar plates, gaskets, humidifier, and radiator. One challenge presented by this fuel cell arrangement is that the ambient air cannot be conditioned before entering the PEMFC, potentially limiting its operating envelope.  This research examines the performance of an open cathode fuel cell in an environmentally controlled wind tunnel that reproduces the atmospheric flight environment. The cell was constructed by laminating a flexible circuit current collector with a membrane electrode assembly (MEA).  The effects of ambient temperature, ambient relative humidity, air speed and altitude on polarization behavior are discussed in detail.  A simple 1-D fuel cell model shows that the dominant factor influencing the polarization behavior is the temperature of the cell, which is determined by the ability of the cell to reject heat.