Effect of the high oxygen excess ratio design on the performance of air-cooling polymer electrolyte membrane fuel cells for unmanned aerial vehicles

Oxygen excess ratio (OER) is a key parameter that affects output power and operating current density of air-cooling polymer electrolyte membrane fuel cells (PEMFCs). In this work, the design method and performance model of air-cooling PEMFCs for UAVs with high OER are proposed. The high OER is realized by using high-speed airflow behind propeller to feed PEMFC cathode. The effect of high OER on the PEMFC performance is investigated by measuring OER and the output power of PEMFC. The test results indicate that the high OER design can further release the performance potential of the PEMFC constrained by heat dissipation while discarding the parasitic power caused by cooling fans. Compared with current PEMFC with low OER by using cooling fans, the temperature distribution variation of PEMFC stack is reduced by 29.8% and the voltage consistency of the single cell at high current density is doubled. The PEMFC with the high OER design exhibits the “current jump” effect, the continuous operating current of PEMFC is increased by 25.0%. The PEMFC net power is increased from 1070 W to 1320 W, and the power density is also increased by 67.8%. Such results provide good reference values for the current PEMFC-powered propulsion system.