Heterogeneous Nucleation of Vapor on Insoluble Particles Predicted by an Improved Classical Nucleation Theory

Abstract

The classical nucleation theory (CNT) plays an important role in the investigation of vapor heterogeneous nucleation on solid surfaces. However, the CNT relies on the macroscopic surface tension to describe the formation of a nano-sized embryo, which inevitably causes the model inaccuracy. In this study, an improved CNT is developed by integrating the microscopic surface tension as a function of the embryo size obtained using the molecular dynamics (MD) simulation to enhance the model accuracy. The important heterogeneous nucleation behaviors, including the Gibbs free energy of embryo formation, critical saturation ratio, and nucleation probability, are numerically investigated by the improved CNT. Compared with the CNT with the macroscopic surface tension, the improved CNT using the microscopic surface tension predicts lower Gibbs free energy of embryo formation, lower critical saturation ratio, and higher nucleation probability, particularly when the contact angle of the particle is large. The improved CNT proposed in this study is validated by comparing the numerically predicted critical saturation ratios for the heterogeneous nucleation of water vapor on planar surfaces and on nano- and micron-sized insoluble particles with the experimentally measured data published in literature.