Performance evaluation of two proton exchange membrane and alkaline fuel cells for use inUAVsby investigating the effect of operating altitude

Fuel cells today have a variety of applications, such as fueling vehicles, which lead to a reduction in conventional fuel consumption and environmental pollution. On the other hand, in the present era, unmanned aerial vehicle (UAV) is known as one of the most important unmanned systems for delivering postal packages, environmental monitoring, disaster relief, and military target. However, the performance of fuel cells is affected by their operating pressure and temperature. In addition, due to some political and technical considerations, the performance of these systems (especially UAV based on fuel cells) is very rare in the literature. The present work provides a conceptual design of UAV propulsion system based on a fuel cell system and a battery. The performance of two different fuel cells, namely the alkaline fuel cell (AFC) and proton exchange membrane fuel cell (PEMFC), is examined separately and compared. Mission and constraint analyses of the system, as well as weight distribution of UAV, are provided. Furthermore, the performance of the UAV propulsion system in different flight modes and the performance of fuel cells under atmospheric conditions are discussed. It should be noted that reference UAV data are used for input parameters. It was found that the total power required by the UAV to carry out the mission is equal to 1253.7 W, which the share of takeoff, climb, cruise, and maximum speed flight modes were 321.3, 608.5, 118.3, and 205.6 W, respectively. Furthermore, the UAV under study, in this paper, has flight endurance of about 7.4 hours. Also, the required area of the PEMFC and AFC to supply the UAV power under the study conditions is about 0.03 and 0.6 m2, respectively. Finally, it observed that with increasing altitude (in the absence of a heating system) the performance of both fuel cells is greatly reduced.