Effect of operating parameters on a hybrid propulsion system with high efficiency fueled by kerosene for high altitude long endurance unmanned aerial vehicles

The traditional engine propulsion systems have poor performance on the high altitude long endurance unmanned aerial vehicles (HALE UAVs) due to the low thermal efficiency. Thanks to the high thermal efficiency and fine off-design performance, SOFC (solid oxide fuel cell) gas turbine hybrid systems can provide a remarkable solution for the propulsion systems of HALE UAVs. The scheme of a SOFC gas turbine hybrid propulsion system fueled by kerosene for HALE UAVs is proposed. The goal of this paper is to demonstrate the effect of operation parameters on the hybrid propulsion systems, which mainly include anode separation ratio, excess air factor, SOFC current density, cathode separation ratio and fuel reforming temperature. We build the lumped mathematical models of the hybrid propulsion system and performance evaluation is done. Several conclusions can be drawn as follows: The efficiency of the hybrid propulsion systems can be significantly increased up to 64%. The efficiency can be optimized as anode separation ratio increases. Cathode separation ratio has little influence on the efficiency. The efficiency increases as the excess air factor increases. The increase of the current density or fuel reforming temperature can lead to the decrease of efficiency.