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

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 v apor nucleation rates were measured with high precision and phase transitio ns in critical embryos containing two and more dozen molecules were detecte d. Phase transitions in critical embryos were used as markers to detect tha t the new phase critical embryos contain two components. Phase transitions of the first order related with critical point second-order phase transitio ns in the pure CO? carrier-gas were used as markers to demonstrate the pres ence of CO2 in critical embryos of condensate. Results of this research, in our opinion, very clearly demonstrate that vapor nucleation in a gaseous a tmosphere is a binary process and must be interpreted from the point of vie w of nucleation theory within a binary system. "Supercritical" nucleation i s a virtual term born by interpretation of binary vapor-gas nucleation by u sing the nucleation model of a single component. A critical condition for t he binary system could be a higher level for the single component critical pressure and/or temperature, which can produce the illusion of supercritica l nucleation. One component interpretation can be used far from the critica l condition. On the other hand, the Laplace pressure practically always is able to approach the nucleation condition to the critical pressure. This le vel 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 s pace. (C) 1998 American Institute of Physics. [S0021-9606(98)52146-0].