Trade-Space Analysis of Liquid Hydrogen Propulsion Systems for Electrified Aircraft

Abstract

This thesis assesses the feasibility of turbo-, hybrid-, and fully-electric aircraft propulsion systems to enable more efficient air transport. A modular optimization framework was developed to quantify system performance for single-aisle transport aircraft with a mission similar to a Boeing 737 MAX 8. Various propulsion systems leveraging superconducting motors, boundary layer ingestion, high-temperature PEM fuel cells, and liquid hydrogen fuel were examined. Aviation turbine fuel (ATF) and liquid hydrogen were compared using the payload-fuel energy intensity (PFEI), defined as the fuel energy required per product of range and payload.

For a given mission, it was found that a hydrogen-fueled fully-electric configuration required similar fuel energy compared to an ATF-burning turbo-fan propulsion system (PFEI = 5.0). Relative to these systems, a hydrogen-fueled turbo-fan had 14% lower PFEI, an ATF-burning turbo-electric propulsion system had 23% higher PFEI, a hydrogen-fueled turbo-electric propulsion system had 8% lower PFEI, and a hydrogen-fueled hybrid-electric had 3% lower PFEI for the same mission.