Effect of the corrugated bipolar plate design on the self-humidification of a high power density PEMFC stack for UAVs

Open-cathode PEMFCs for unmanned aerial vehicles operate at a near-ambient temperature, which requires high super-stoichiometric air flow rates to remove heat. This, in turn, makes the stack vulnerable to drying out. Using a combination of experimental measurements with a 1.2 kW stack and 3D multiphysics modelling, we show that the design of the corrugated metal bipolar plate with a height above the commonly used 1.05 mm and with cathode cooling channels wider than air-suppling channels allows for a more efficient heat removal at lower air flow rates, thus assuring a wider range of operating parameters, while maintaining adequate hydration. The self-humidifying stack attains 1000 W kg(-1) power, and the full system with a nominal runtime of 4 h attains specific energy of 700 Wh kg(-1).