Testing microtubular SOFCs in unmanned air vehicles (UAVs)

Unmanned Air Vehicles (UAVs) powered by microtubular SOFCs (mSOFCs) are described for comparison with polymer fuel cells (PEFCs). Using propane as fuel, 7mm diameter mSOFCs have been tested in a 2m wingspan aircraft with a total weight of 6kg. The start-up time was 12 minutes to deliver 250W in a fuel cell/battery hybrid drive system. Tubes were YSZ cermet anode supported, with 10 µm YSZ electrolyte, 6µm SDC interlayer coated with 50µm LSCF cathode. Silver wires were used as interconnects. Pure propane fuel gas was mixed with air in a CPOX reactor using catalytic fuel processing mesh. A polymeric fuel inlet manifold gave cold sealing at the tube inlet ends which projected out of the hot box. Cathode air was provided in counterflow, preheated over an anode off-gas catalyst. The fuel utilization was 55%, output power of 250W. The fuel cell was incorporated in a hybrid electrical system with lithium polymer battery and inserted in a Skywalker X8 UAV with 500g of propane in an aluminum tank.