An Open Cathode Fuel Cell for Atmospheric Flight

Abstract

Our previous work has shown that fuel cells are ideal power sources for long endurance unmanned air vehicles (UAVs) (1). An open-cathode fuel cell system has the cathode exposed to the open air to harness the motion of a UAV through the atmosphere to provide O2 to the cathode. By removing the balance of plant (BOP) associated with pumping and preconditioning the incoming air, an open cathode fuel cell may be an ideal power source for atmospheric flight because of its simplicity and reduced weight. A custom open cathode fuel cell based on flexible circuits is fabricated and characterized in a custom wind tunnel/environmental chamber setup to ascertain whether open cathode fuel cells can operate in atmospheric flight conditions. A numerical model is also developed to quantify the associated loss mechanisms in the cell. Wind tunnel experiments show that open cathode operation is possible without catastrophic failure over a wide range of ambient temperatures (5-55 °C), ambient relative humidities (22-90% RH), air speeds (2.6-15.4 m s-1) and altitudes (< 10-914 m); with the largest losses associated with mass transport and catalyst activation.