Benchmarking a 1 kW hybrid hydrogen fuel cell system

Abstract: Unmanned Aerial Vehicles (UAV's) offer great versatility in the tasks that they may perform and they are today used in many sectors. The H24LEO project, administered by the Lund University School of Aviation, aims to develop and demonstrate a hybrid proton-exchange membrane fuel cell-powered UAV to aid in search and rescue operations performed by the Swedish Maritime Administration, and reduce the greenhouse gas emissions compared to similar work performed by helicopters. This master's thesis aims to test the performance and learn about the operation of a physical hybrid fuel cell system before it is integrated in a UAV airframe. A test bench was designed and built where experiments with the fuel cell could be run in a controlled manner. An analysis was also made of the system's strengths and weaknesses, and these were compared to those of battery-electric and combustion-based power supplies. Due to time constraints of the project and major hardware issues with the fuel cell system, results from the experiments could not be gathered in time for this report. An electrical fault due to bad wiring led to the fuel cell not working properly, and repairs could not be performed within the deadline of the project. This hybrid fuel cell system should be able to provide 6 \% better energy density than a battery-electric system, with the same airframe and propulsion system. The system could however be further optimized by using different hydrogen cylinders. The bulkiness of the system is a limitation, with custom modifications of the fuel cell stack being required to fit in the airframe. The hybrid fuel cell system should be a valid choice for a UAV, and should be able to provide sufficient power during all stages of flight. It does however offer significantly worse range than that of a combustion-based system. Cold Swedish weather could prove to be a challenge as it might compromise the start-up of the system under sub-zero temperatures.