The effect of temperature on nanoparticle clustering

A multiscale computational approach was applied to study the evolution of soot formation in an ethylene flame environment, from small polycyclic aromatic hydrocarbons of less than 10 atoms, to nano-sized organic carbon (NOC) clusters of diameters up to 15 nm. As this evolution covers sizable breadth in time and length scales, the application of a sequence of complementary computational approaches was employed. To model NOC particle aggregation, the coarse grain method allowed for molecular dynamics simulation of over 13,000 nanoparticles (106 atoms), for hundreds of nanoseconds. Notable growth in both the number and size of particles was observed when temperature was dropped from 1800 to 300 K. A test of input sensitivity determined little noticeable effect upon inclusion of electrostatic interactions of atomic-centered partial charges. These results provide insights on the influence of temperature on nanoparticle aggregation in flames. This could also assist in the analysis of experimental measurements of methods which allow for sample cooling in the period from extraction to detection.