Abstract:

The biggest technical difficulty in developing small drones is to solve the problems of their power systems. In order to maintain the flight of aircraft, the power system of small drone also provides energy for the airborne equipment. Therefore, the unmanned aerial vehicle (UAV) power unit requires a small volume with high energy density, and can be easily and efficiently converted into thrust force. In this paper, proton exchange membrane fuel cell (PEMFC) is used as the power source candidate of the UAV. Based on the PEMFC stack model and the environmental model, numerical simulations were conducted by Matlab to investigate the effect of altitude on operation status and thermodynamic performance of PEMFC system. The results indicated that as the height increases, the variations of system output voltage, output electric power and system electrical efficiency exhibit a downward trend. When the height is constant, the output power of the system has the highest value with the rise of current density, but the output voltage of the stack and the output efficiency of the system decrease. Moreover, it has been found that the increase of the hydrogen inlet pressure intensifies the output voltage, electric power and electrical efficiency of the system. For the purpose of performance improvement of PEMFC system at a certain height, it is necessary to select a suitable current density and a high hydrogen inlet pressure.

Key words: fuel cells, unmanned aerial vehicle, altitude, dynamic simulation, thermodynamic properties

摘要：

建立了无人机用质子交换膜燃料电池（PEMFC）动力系统性能随大气环境变化的数学模型，通过Matlab进行仿真，分析海拔高度对PEMFC系统运行状况和热力学性能的影响。结果显示: 随着高度的增加，系统输出电压、输出电功率及系统电效率呈下降趋势；当高度一定时，随着电流密度的增加，系统输出电功率有最大值，但电堆输出电压和系统输出电效率下降；氢气进气压力的增大使系统的输出电压、电功率和电效率逐渐增大；为了提高燃料电池系统在一定高度下的性能，需要选择合适的电流密度和较高的氢气进气压力。

关键词: 燃料电池, 无人机, 海拔高度, 动态仿真, 热力学性质