Numerical Optimization of Methanol–Ammonia Blends for Sustainable Marine Propulsion Using Three-Dimensional CFD Simulation

The maritime industry's transition toward low-carbon propulsion has intensified interest in carbon-neutral fuels, particularly ammonia, because of its zero-carbon molecular structure and potential for renewable production. However, its application in marine compression-ignition engines is limited by high auto-ignition temperature, low flame speed, narrow flammability limits, and poor combustion reactivity, leading to prolonged ignition delay, combustion instability, and ammonia slip. This study presents a three-dimensional Computational Fluid Dynamics (CFD) investigation of the combustion, performance, and emission characteristics of methanol–ammonia dual-fuel blends in a medium-speed marine diesel engine using diesel pilot ignition.