Development of an ammonia-fueled cracker-engine-unit as propulsion system for inland waterway vessel

The urgent need to reduce CO2 emissions in all areas demands the swift development and implementation of appropriate solutions for the worldwide shipping branch both for sea-going and inland waterway vessels. Therefore, several options are viable, most of them based on green e-fuels. Ammonia, produced on basis of renewable energies e.g., by solar and wind power, looks as a promising candidate for shipping as worldwide trading and handling are already in place which eases the establishment of a fuel supply chain.Within the CAMPFIRE alliance, new energy conversion and storage technologies based on green ammonia are investigated as part of the future energy systems. One of the projects focuses on the development of an ammonia-fueled cracker-engine-unit as propulsion system for inland waterway vessels. The spark-ignited heavy-duty engine will be fed by liquid ammonia as main fuel. A part stream of ammonia will be decomposed into hydrogen and nitrogen so that a small amount of hydrogen is brought to the engine as ignition amplifier for the ammonia. The project goal is the achievement of diesel-like engine output values with a maximum share of ammonia.The paper describes the specific boundaries of inland waterway shipping, the ideas behind the monofuel propulsion concept and presents results from the pressurized ammonia cracker development as well as from the single-cylinder engine (SCE) testing. ... mehrA further chapter will handle related safety experiences.The ammonia cracker as automated stand-alone plant was developed according to the requirements set by the engine and on the basis of extensive catalyst testing as well as process and multi-physics simulations. Here, special emphasis is placed on challenges in the development process, e.g., the influence of the harsh conditions characterized by a combination of high temperature and ammonia-rich atmosphere on process and reactor design including the selection of a suitable material. The final cracker design is presented and first experimental results are discussed.The SCE testing allowed a systematic investigation of various mixture formation concepts (PFI and DI) – supported by optical spray investigations -, different compression ratios and ignition systems. All that comes along with 3D-CFD simulations, especially for the mixture formation optimization. One important task was the development of fuel injectors suitable for liquid ammonia. During the whole SCE operation, a detailed emission measurement was carried out, enabling an extensive knowledge about the impact of various parameters.The results will be transferred to the multi-cylinder engine, which is going to be married and tested with the ammonia cracker in 2025. Then specific focus will be set on the complete cracker-engine-unit optimization under maritime operational boundaries and the setup of an exhaust aftertreatment system.