Fuel Conditioning System Modeling for Liquid Hydrogen-Powered Aircraft

Abstract The increasing demand for sustainable aviation fuels has prompted the exploration of hydrogen as a viable alternative for reducing carbon emissions in the aviation sector. The high gravimetric energy density of hydrogen makes it a promising candidate for future aviation fuel, offering significant potential to reduce the carbon footprint of air travel. While many articles on hydrogen aircraft design focus on the conceptual layout of fuel systems, they often lack critical details on the mass and size of key components and hydrogen boil-off during ground operation, which are vital for practical implementation. Through modeling and dynamic simulation analyses, this paper investigates the process of hydrogen fuel conditioning for gas turbines in aviation, focusing on the mass, sizing and performance of different components. The aircraft considered for this model consists of a 19-passenger with a 700 NM range that burns hydrogen in the GT directly. The sizing/design approaches of the most critical components, namely, the storage tank, heat exchanger, and pump are presented. The system-level analysis is presented for the flight mission profile. The parametric analysis is performed for a foam-insulated, storage tank with semi-hemispherical domes for the effects of ullage volume fraction, dormancy duration, and maximum storage pressure on gravimetric efficiency. Maximum efficiency occurs at low ullage fractions (0.05–0.1) and moderate tank pressures (4.0–5.0 bar). However, efficiency decreases with longer dormancy times. Liquid hydrogen is stored at 21 K and 1.5 bar, pressurized to 28 bar using a centrifugal pump consuming 1.47 kW at take-off. The hydrogen is then heated to the required combustor inlet temperature using a compact heat exchanger with an effectiveness of 0.5. The corrected gravimetric efficiency, considering the fuel conditioning system components, is 57% for a 2-hour dormancy and 53% for a 4-hour dormancy. A tank with gravimetric efficiency above 33% means that the combined mass of fuel and its storage will be lower than that of jet fuel. At 33%, the combined masses will be equal. Gravimetric efficiency of 57% is promising for a short and a medium hydrogen aircraft.