A Prophase Simulation Study of Fuel Cell-Battery Hybrid System for eVTOL Aircraft in Steady-State Operation 2023-01-7092

Electric vertical take-off and landing (eVTOL) is defined as vertical lift aircraft propelled by electric power and capable of carrying people. Based on the system of battery powered CY300 eVTOL, a fuel cell-battery hybrid system (FBHS) in steady-state operation as a potential propulsion system for CY300 eVTOL is proposed. In order to analyze the feasibility of FBHS-powered eVTOL system, a mathematical model is established to evaluate the proposed system performance considering various irreversible effects. Furthermore, considerable sensitivity analyses indicate that the payload of the proposed system is considerably benefited by a higher specific energy of the battery system, specific power of the fuel cell system and hydrogen storage ratio of the hydrogen tank. Hydrogen tank weight decreases the payload while enhances the hovering time. DoH accounts for power balancing between two power sources, and affects the impacts of different design parameters on the performance of the proposed FBHS. In order to achieve a long endurance eVTOL with a cruise time of more than 30 min and a payload rate of more than 30%, the specific energy of the battery system in this proposed FBHS needs to be greater than 500 Wh/kg, and the specific power of the fuel cell system needs to reach more than 1000 W/kg. For hydrogen storage technology selections, high pressure gaseous hydrogen storage technologies are suitable enough for short-range eVTOLs, but liquid hydrogen powered eVTOLs can be an ideal solution for long-endurance aircraft. The results acquired may be helpful in designing and optimizing such an actual power system.