Comprehensive technical analyses of a solid oxide fuel cell turbine-less hybrid aircraft propulsion system using ammonia and methane as alternative fuels

Abstract

This paper presents a novel hybrid aircraft propulsion system that combines a turbojet engine with an ammonia decomposition reactor and a solid oxide fuel cell system, where the compressor is driven by a solid oxide fuel cell instead of a turbine. Ammonia and methane are selected as alternative fuels to replace kerosene. Technical analyses, including energy and exergy analyses, and comprehensive parametric studies, including engine, flight, fuel cell, and decomposition parameters, are performed, together with quantification of global warming potential (GWP). The results show that the solid oxide fuel cell has a power of 316.68 kW and an electrical efficiency of 42.09%. The hybrid aircraft propulsion system has a thrust of 851.82 N, a specific fuel consumption of 49.93 g/(kN·s) and an exergy efficiency of 22.27%. Compared to a kerosene-fueled turbojet, the hybrid aircraft propulsion system can decease 80.37% of GWP. The optimum choice of engine parameters is a low fuel ratio, a medium pressure ratio and a high air ratio. The best choice of flight parameters is a high Mach number and a medium altitude. Fuel cell parameters cannot achieve high thrusts and low fuel consumptions at the same time. The decomposition temperature should be as high as possible.