Preliminary study of the impact of using hydrogen with a fuel cell for Aircraft propulsion in an existing platform
Creators: name:  V.M. DE FRUTOS CASADO 
name:   C. BORDONS ALBA 
name:   S. ESTEBAN RONCERO 
name:   J.R. PARRA 
Publisher: name: Proceedings of  the 9th European Conference for Aerospace Sciences. Lille, France, 27 June - 1 July, 2022
Year: 2022
Subjects: HYBRID ELECTRIC PROPULSION
AVIATION
EMISSIONS

description: In the pursue of truly achieving the decarbonisation of air transport, several initiatives have been launched within the aeronautical industry with very different approaches. Despite that many studies have been conducted over the last years, including trials with demonstration flights for fuel cell-based aircraft platforms or for burning hydrogen propulsion, these studies have never gone beyond prototype status. With the establishment of the Clean Skies for Tomorrow initiative (CST) in 2019, 60 companies in the World Economic Forums Clean Skies for Tomorrow Coalition partnered with the objective to accelerate the deployment of sustainable aviation fuels (SAF) on the path to net-zero emissions by 2050 and working together to power global aviation with 10% SAF by 2030, many efforts and resources have been dedicated to go beyond the prototype phase. Among those, it can be pointed out that in September 2020,Airbus presented three ZEROe hydrogen-fuelled concepts aiming for commercial service by 2035. One of the most promising presented alternatives is the incorporation of hydrogen technology in the power plant of flying platforms in order to reduce the carbon footprint. Two ways are contemplated for the introduction of hydrogen technology in the engine plant of an aircraft: the burning of hydrogen in a combustion engine and the use of a fuel cell to generate energy to fly. Prior to consider the hydrogen utilization as an alternative, it is necessary to evaluate theimpact that such technology might have in aircrafts. The main objectives sought in this paper are: 1. Providing a methodology that allows to evaluate the impact of the introduction of hydrogen fuel cell technologies by means the comparison between the performances of the existing platform and the derivative. 2. Evaluating what type of platforms might be suitable for adapting hydrogen-based power sources having in perspective the scalability of the platforms (from UAVs to large commercial transports), and how the adaptation might affect in the performance when compared with conventional jet fuel propulsion. 3. Using a design-based methodology, identify how the required power-to-weight ratios might affect the design point of new aircraft platforms when the hydrogen fuel technologies are considered from the beginning of the design process. 4. Identify different levels of power source hybridization that might be required in order to minimize performance degradation, and how the different hybridization strategies might help to improve the two previous objectives. In order to obtain these objectives the paper presents a mathematical methodology that provides a preliminary sensitivity analysis that will allow to conduct assessment of the suitability and impact that an alternative hydrogen based fuel cell propulsion system might have in existing aircrafts when the carbon-based fuels propulsion system is replaced by hydrogen fuel-based propulsion systems. The study uses an existing tactical transport platform as a benchmark following several assumptions: 1. Both platforms, traditional and modified, have the same physical envelope. This means that the aerodynamic characteristics are the same on the traditional and modified platform. 2. The size and integration of the new power plant system could be done on the current platform envelope and only the mass changes. 3. For the modified platform, the removal of the current power plant and the installation of the new hydrogen-based power plant is considered, so the operational empty weight is affected. The sensitivity studies evaluate how the performance is affected by the different considered hybridization power plants, while uses different metrics to evaluate the viability of the proposed power alternatives, and propose the best configuration. The Maximum Take off Weight (MTOW) is taken as pass/fail criteria for the modified platform: if the modification for introducing the new power plant based on hydrogen results in an aircraft weight higher than the MTOW of the traditional platform, as long as the aerodynamic behavior is the same, the modified platform will not take off. Then the MTOW will limit the hydrogen system and the starting point for the impact evaluation. This preliminary study helps to pave the way for the use of hydrogen and hybrid electrical/hydrogen systems for propulsion in future aircraft designs.