Considerations for Ammonia-fuelled Aircraft and Propulsion Systems: A Component-level and System Analysis
Marcel Otto, Ramees K. Rahman, Jonathan Gladin, William Andress, Guillermo Barrios Cadenas, Chintan Rank, Saqib Shahzad, Kangana Patel, Benjamin Turner, Andrew Menendez, Connor Wall, Richard Blair, David Zamora, Yu Cai, Venkat Athmanathan, Keith McManus, Guillermo Paniagua, Terrence Meyer, Subith Vasu, Jayanta KapatAbstract
Alternative fuels for aviation as substitutes for Jet-A are currently being investigated globally. Ammonia has emerged as a potential candidate given its robust supply chain, technological maturity, and global infrastructure. Ammonia combustion at scale has been successfully demonstrated in gas turbines for power generation. This paper studies the potential of ammonia as aircraft fuel. A modern single-aisle airliner with two state-of-the-art high-bypass turbofans is assumed to be powered by ammonia. System trade-off analysis is performed considering the impact of weight and fuel volume on the payload range performance of the aircraft. Concepts for on-board fuel storage are presented and evaluated. The proposed concept utilizes a supercritical carbon dioxide (sCO2) cycle for waste heat energy harvesting and thermal management of the ammonia. The system integration, including a transient analysis and heat exchanger design, is presented. Alternative thermal management concepts through direct heat transfer are explored on a cycle performance basis and thrust-specific fuel consumption. The combustion system is designed to burn ammonia-hydrogen mixtures. Kinetic models and combustor designs are presented for use in commercial turbofan engines. An integrated ammonia cracking system and novel catalysts are experimentally explored and presented. Ultimately, a technology maturation plan through real engine ground testing is described.