Towards cleaner combustion of hydrocarbons by blending with ammonia and hydrogen using CFD-Based emissions minimization

• Investigated the impact of ammonia and hydrogen enrichment on ethylene, propane, and toluene flames. • Explored combustion reactions and intermediate species formation, highlighting NH3 and H2 influence on reaction rates. • Analyzed COx, PAH, C-H-O species, and NOx emissions, showcasing the influence of NH3 and H2 concentrations on waste reduction. • Employed computational models integrating soot surface equations and the Moss-Brookes model for analysis. • Conclusions highlight NH3 enrichment at 50% for ethylene, significant NOx reduction with H2 in propane, and effective PAH reduction with NH3 at 50% in toluene. The combustion of hydrocarbons significantly impacts the environment. It produces greenhouse gas (GHG) emissions, including unburned organic volatiles, polycyclic aromatic hydrocarbons (PAHs), nitrogen oxides (NO x ), and carbon oxides (CO x ). However, hydrocarbons remain a dominant global energy source. Blending alternative fuels such as ammonia (NH 3 ) and hydrogen (H 2 ) presents a promising strategy to reduce emissions while maintaining energy efficiency. In this study, a validated two-dimensional transient computational fluid dynamics (CFD) model was used, incorporating detailed chemical reaction kinetics (which refers to the study of the rates and mechanism of chemical reactions) and the Moss-Brookes soot formation model (a predictive framework that describes how soot particles form, grow, and oxidize during combustion). Unlike prior research on (NH 3 ) or (H 2 ) separately, this work investigates their combined effects when blended with hydrocarbon fuels. Simulations were conducted on ethylene (C 2 H 4 ), propane (C 3 H 8 ), and toluene (C 6 H 5 CH 3 ) with varying NH 3 /H 2 ratios (0-50%). Our results show that, compared to pure hydrocarbon baselines (0% NH 3 /H 2 ) a 50% NH 3 -H 2 blend reduced PAH emissions by 18% in toluene (T3) and up to 97% ethylene (E3). NO X emissions were also reduced, ranging from 5% in propane (P2, 25% NH 3 ) to 63% in propane (P5, 50% H 2 ) while maintaining an effective combustion temperature of approximately (1500 K) at the specified equivalence ratio.