This article develops a numerical simulation framework for ammonia/diesel
dual-fuel combustion using CONVERGE software. The modeling approach is explained
in detail, including theories of numerical computation, mathematical submodels,
modeling methodologies, and boundary condition specifications. Based on the
developed model, this work investigates the impact of the ammonia fuel ratio on
some key combustion and emission characteristics: heat release dynamics,
distribution of the in-cylinder temperature field, formation of intermediate
combustion species, and pollutant emissions. It provides comprehensive analysis
in terms of in-cylinder pressure, mean temperature, heat release rate profile,
cumulative heat release, fluctuations in the compositions of n-heptane and
ammonia, distribution of the equivalence ratio, turbulent kinetic energy,
concentration of OH radicals, formation of formaldehyde, and emissions of
pollutants including CO, NOx, N2O, soot, and unburned hydrocarbons
(HC) with respect to crank angle. The results showed that the fraction of
ammonia fuel is the key to affecting in-cylinder combustion, the development of
intermediate and final products, and different pollutant emissions. This work
can provide important theoretical guidance and practical suggestions for the
development of ammonia/diesel dual-fuel combustion technology, as well as
promote effective and green utilization of ammonia in internal combustion
engines.