The design, modeling, and performance verification of an integrated PEMFC-powered engine for UAVs

In recent years, fuel cell-powered engines have an increasing number of applications in the field of UAVs (unmanned aerial vehicles). The aviation airflow exhibits the advantages of a large airflow rate and excellent cooling effect, and is a good choice for fuel cell units of fuel cell-powered engines for cooling and reaction. In this work, the OER (oxygen excess ratio) characteristics of the air-cooled PEMFCs (proton exchange membrane fuel cells) are investigated to characterize the PEMFC power under different OERs, and the design, modeling, and performance verification of an integrated PEMFC-powered engine for UAVs are conducted based on the obtained OER characteristics. The PEMFC-powered engine introduces a “direct airflow intake” structure, which can utilize aviation airflow to ensure the PEMFC cooling and reaction requirements. The results show that the air-cooled PEMFCs have an optimal operating zone, which is directly determined by the OER. By configuration optimization, the power-to-weight ratio of the PEMFC system and whole engine are increased by 56.7% and 26.9%, respectively. With OER as the key parameter, the performance characteristics ranging from 0 to 2000 m of the PEMFC-powered engine are obtained through performance modeling. Besides, the results of the ground test and the flight test show that the proposed “direct airflow intake” structure can improve the output performance of the engine under various operating conditions. For the 1600 W PEMFC-powered engine, the “direct airflow intake” structure can realize “zero parasitic power loss” during the power transmission process, and the net power of the engine is 183 W higher than traditional PEMFC propulsion systems. This work provides a new design concept for the hydrogen power and propulsion systems for UAVs, which is of great significance for the low-altitude applications of hydrogen-powered UAVs.