A method for an efficiency and weight-optimised preliminary design of a hydrogen-powered fuel cell-based hybrid-electric propulsion system for aviation purposes

Abstract

There is a worldwide effort to advance the usage of zero-emission propulsion systems for aircraft. Due to their high thermodynamic efficiency and the fact that they produce no CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ extrm{CO}_{2}$$\\end{document} and NOx\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ extrm{NO}_{x}$$\\end{document} emissions, hydrogen-powered fuel cells are becoming increasingly popular for aviation purposes. However, fuel cell systems suffer from lower power density and higher cooling requirements when compared to conventional propulsion systems. Harnessing the high potential requires an optimised design of the whole propulsion system and its heat management system. This paper aims to present a method for the preliminary design and dimensioning of a fuel cell-based hybrid-electric propulsion system, which respects the limits of the heat management system and is weight and efficiency optimised. Thermodynamic models of the whole propulsion system are a crucial element to enable further investigations. Such a model has been developed, which is suitable for unsteady simulations of the propulsion and the heat management system performance of a short-range four-seater aircraft. A parameter study of the design parameters has been performed to display their impact on the system mass, the overall efficiency and the total hydrogen consumption. These results enable the identification of an overall optimised configuration. The study indicates that fuel cell-only configurations with an oversized fuel cell stack are beneficial for the analysed aircraft and flight mission.