Critical embryo phase transitions in the nucleated binary glycerin–carbon dioxide system

Abstract

In order to develop a consistent nucleation theory, the main assumptions of the theory should be revised. One of the questionable problems is the role of the carrier gas in nucleation and the surface tension for the critical embryo as a function of cluster size. Using a flow diffusion chamber, the vapor nucleation rates were measured with high precision and phase transitions in critical embryos containing two and more dozen molecules were detected. Phase transitions in critical embryos were used as markers to detect that the new phase critical embryos contain two components. Phase transitions of the first order related with critical point second-order phase transitions in the pure CO2 carrier-gas were used as markers to demonstrate the presence of CO2 in critical embryos of condensate. Results of this research, in our opinion, very clearly demonstrate that vapor nucleation in a gaseous atmosphere is a binary process and must be interpreted from the point of view of nucleation theory within a binary system. “Supercritical” nucleation is a virtual term born by interpretation of binary vapor–gas nucleation by using the nucleation model of a single component. A critical condition for the binary system could be a higher level for the single component critical pressure and/or temperature, which can produce the illusion of supercritical nucleation. One component interpretation can be used far from the critical condition. On the other hand, the Laplace pressure practically always is able to approach the nucleation condition to the critical pressure. This level of detail is a problem for future studies. The traditional application of classical nucleation theory for vapor–gas nucleation should be modified to consider the nucleation conditions in pressure-temperature-composition space.

High-pressure phase equilibria with compressed gases

“…In addition, phase equilibria data allow theoretical development of high-pressure and near-critical phenomena. [9][10][11] Several experimental methods can be used to measure high-pressure phase equilibria. These methods are generally divided into two categories: analytical and synthetic approaches.…”

Aerosol Science and Technology: History and Reviews

“…The FDC can be developed easily for measurements at pressures up to 20 MPa. Several results illustrated that a high-pressure flow diffusion chamber should be designed for the careful research of multichannel nucleation (e.g., Anisimova et al, 2001;Anisimov et al, 1998aAnisimov et al, , 1998b. While a new experimental system is being developed, research teams have used existing FDCs to study nucleation systems, showing that there are effects of the carrier gas and multiphase phenomena that need to be explored further.…”

“…Figure 7 provides an example of experimental data that shows the gap in nucleation rate. The gap is initiated by the phase change in critical embryos generated by a supersaturated vapor-gas system (Anisimov et al, 1998b). A conceptual problem in vapor-liquid nucleation is that it is treated as a singlecomponent problem.…”

“…In that case, the Gibbs free energy surface has several saddle points for the formation of binary system embryos (each saddle point is associated with a nucleation channel; for details, see Anisimov & Hopke, 2001). Several studies (e.g., Anisimova et al, 2001;Anisimov et al, 1998b) have shown that a high-pressure flow diffusion chamber needs to be designed for the profound research of multichannel nucleation. While a new experimental system is in development, researchers have used an existing FDC to study nucleation systems.…”

General Requirements and Recommendations for Vapor Nucleation Rate Experiments

“…• cm −3 s −1 can be measured using the flow diffusion chamber (Anisimov et al 1998a). For the lowest rate of 10 −3 to 10 2 cm −3 s −1 , the static diffusion chamber (Rudek et al 1999) can be used.…”