Autoren

Sandro SILVESTRINI^1,2, Bouzid SEBA^1,2, Brijesh Rakeshbhai KINKHABWALA², Heiko KUBACH², Thomas KOCH^2 
1Liebherr Machines Bulle SA, CH; ²Karlsruhe Institute of Technology, DE

Zusammenfassung

As efforts to reduce carbon emissions grow, ammonia is gaining attention as a carbon-free fuel. This work investigates the use of direct liquid ammonia injection combined with port fuel hydrogen injection in a spark-ignition engine, using CFD simulations supported by experimental data. A literature-based evaporation model was validated to simulate liquid ammonia evaporation. The simulation approach includes: (i) a VoF simulation to analyse ammonia behaviour at the nozzle outlet, (ii) an engine simulation using a Lagrangian spray model and (iii) a combustion investigation. Combustion simulations for the selected case at CR = 18.5 assess the impact of spark timing on pressure rise, combustion duration, and emissions. Advancing ignition improves combustion efficiency, increases NOx, and reduces NH3 and N2O. The results highlight how in-nozzle phase change affects fuel preparation, how turbulence–chemistry interaction governs flame development, and how ignition phasing influences the overall combustion process in ammonia–hydrogen dual-fuel operation.

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