Evaluation of a fuel cell system designed for unmanned aerial vehicles
Diogo F.M. Santos, Rui B. Ferreira, D.S. Falcão, A.M.F.R. Pinto
Abstract
A commercial fuel cell system designed for unmanned aerial vehicles (UAVs) is studied. The system presents a rated power of about 258 W and a maximum efficiency of 47%. Energy lost due to the unreacted hydrogen (lost during purging and short-circuit) is a major contributor to the lower efficiency obtained at low power outputs (<80 W). For higher power outputs, heat generation represents the major loss. Purge duration increases with power to regulate water content in the cell. Temperature control, performed by the air supplying fans, is only active above 200 W. Below this value the temperature reached poses less risk of drying the fuel cell stack membranes. The system includes a battery that supplies additional power. It provides power when the fuel cell stack matches its voltage and it is recharged at 1 A. The performance of the system is also evaluated using real flight data.