Development and validation of phenomenological models for combustion and emissions of a dual-fuel marine engine supplied with ammonia

This study investigates ammonia-fueled RCCI combustion in a medium-bore research engine. Ammonia is introduced via port injection, while light fuel oil is directly injected inside the cylinder. The experimental campaign explores variations in engine load, air-to-fuel ratio, injection timing and duration, and valve timing. A phenomenological model is developed and validated, incorporating chemical kinetics and flame propagation. The framework employs a multi-zone approach to calculate fuel distribution, integrating a spray model, a tabulated method for ignition prediction, and an emissions model to estimate CO, NO, uHC, uNH3, and N2O concentrations. The model accurately simulates experimental results, achieving an average error below 10 % in global performance predictions and of about 20 % in pollutant emission evaluations. By capturing the key physics of RCCI combustion, this study provides valuable insights into ammonia potential as a marine zero-carbon fuel and supports the development of predictive tools for engine design and optimization.