Vapor phase nucleation of the short-chain n-alkanes (n-pentane, n-hexane and n-heptane): Experiments and Monte Carlo simulations

Kehinde E Ogunronbi; Aliasghar Sepehri; Bin Chen; Barbara E Wyslouzil

doi:10.1063/1.5023567

Vapor phase nucleation of the short-chain n-alkanes (n-pentane, n-hexane and n-heptane): Experiments and Monte Carlo simulations

J Chem Phys. 2018 Apr 14;148(14):144312. doi: 10.1063/1.5023567.

Authors

Kehinde E Ogunronbi¹, Aliasghar Sepehri², Bin Chen², Barbara E Wyslouzil¹

Affiliations

¹ William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio 43210, USA.
² Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803-1804, USA.

PMID: 29655353
DOI: 10.1063/1.5023567

Abstract

We measured the nucleation rates of n-pentane through n-heptane in a supersonic nozzle at temperatures ranging from ca. 109 K to 168 K. For n-pentane and n-hexane, these are the first nucleation rate measurements that have been made, and the trends in the current data agree well with those in the earlier work of Ghosh et al. [J. Chem. Phys. 132, 024307 (2010)] for longer chain alkanes. Complementary Monte Carlo simulations, using the transferable potentials for phase equilibria-united atom potentials, suggest that despite the high degree of supercooling, the critical clusters remain liquid like under experimental conditions for n-pentane through n-heptane, but adopt more ordered structures for n-octane and n-nonane. For all three alkanes, the experimental and simulated nucleation rates are offset by ∼3 orders of magnitude when plotted as a function of ln S/(T_c/T - 1)^1.5. Explicitly accounting for the surface tension difference between the real and model substances, or alternatively using the Hale [Phys. Rev. A 33, 4156 (1986); Metall. Mater. Trans. A 23, 1863 (1992)] scaling parameter, Ω, consistent with the model potential, increases the offset to ∼6 orders of magnitude.