High-Altitude Operation of a Commercial 100 kW PEM Fuel Cell System

A commercially available 100 kW PEM fuel cell system designed for efficient operation on ground-level was tested at low ambient pressures between 750 mbar and 940 mbar in a low-pressure chamber. The current–voltage characteristics at 940 mbar and 900 mbar showed only small differences, while the system performed worse at lower ambient pressures. To enable operation at these low pressures, an additional current-limiting strategy had to be implemented, as it was found that the compressor could not deliver sufficient mass flow at ambient pressures below 867 mbar to reach the maximum current allowed by the system (420 A). The results show that the fuel cell system, which was designed for ground-level applications, can be operated at lower pressures if the proposed current-limiting strategy is implemented, although at the cost of a lower maximum current output at low ambient pressures. Based on the results, suggestions for further hardware measures to optimise the system for flight conditions are made.