Homogeneous Nucleation of the Homologous Series of n-Alkanes

Abstract

We measured homogeneous nucleation rates J = N/Δt for the homologous series of n-alkanes from n-heptane to n-decane in the temperature range of 150 K to 220 K using a supersonic Laval nozzle. For each compound we conducted two sets of experiments under identical conditions. First, we obtained the characteristic time 1·10−5 ≤ Δt/s ≤ 4·10−5, the time during which nucleation occurs, by carrying out static pressure trace measurements along the axis of the nozzle. In the second set of experiments, we determined the particle number density 1011 ≤ N/cm−3 ≤ 1012 using Small Angle X-ray Scattering. Consequently, we achieve nucleation rates of 2.5·1015 ≤ J/cm−3s−1 ≤ 1017 in our experiments. Hale’s scaled nucleation model [1,2] shows that our results are consistent with the low pressure measurements carried out by Peters et al. [3], Luitjens et al. [4] and the scaling factors shown by Rusyniak and El-Shall [5]. All condensable species are treated as thermally perfect, calorically imperfect vapors in this work.