Ignition and Combustion of Hydrocarbon Fuels Enhanced by Aluminum Nanoparticle Additives: Insights from Reactive Molecular Dynamics Simulations

Owing to the unique properties of aluminum nanoparticles, these nanoadditives show promise in improving the combustion performance of traditional hydrocarbon fuels. Here, the ignition and combustion processes of the simplest hydrocarbon, methane, with the addition of aluminum nanoparticles, were investigated using ReaxFF molecular dynamics simulations. The oxidation of the initially unoxidized aluminum nanoparticles is a microexplosive violent combustion process. The simulation results revealed that the presence of such aluminum nanoparticles reduces the ignition delay of methane and improves its combustion efficiency. The activation energy of methane dissociation is significantly reduced by similar to 47% in the presence of aluminum nanoparticles compared to the pure methane system. It is found that the mechanism of this combustion enhancement is from the significant increase in the number of atomic oxygen with the addition of aluminum nanoparticles, which accounts for the decomposition of methane by more than 60%. Moreover, the formation of atomic oxygen is mainly caused by the instability of low-coordination atoms on the surface of the AlxOy cluster. Further simulations of aluminum particles with oxide shells show that such particles can also promote the production of atomic oxygen to a small extent. It is believed that the findings presented here provide an important perspective on understanding the influence of aluminum nanoparticles on the combustion of hydrocarbon fuels at an atomic scale, and have an instructive significance in improving combustion efficiency.