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Title: Binary nucleation kinetics. I. Self-consistent size distribution

Abstract

Using the principle of detailed balance, we derive a new self-consistency requirement, termed the kinetic product rule, relating the evaporation coefficients and equilibrium cluster distribution for a binary system. We use this result to demonstrate and resolve an inconsistency for an idealized Kelvin model of nucleation in a simple binary mixture. We next examine several common forms for the equilibrium distribution of binary clusters based on the capillarity approximation and ideal vapor behavior. We point out fundamental deficiencies for each expression. We also show that each distribution yields evaporation coefficients that formally satisfy the new kinetic product rule but are physically unsatisfactory because they depend on the monomer vapor concentrations. We then propose a new form of the binary distribution function that is free of the deficiencies of the previous functions except for its reliance on the capillarity approximation. This new self-consistent classical (SCC) size distribution for binary clusters has the following properties: It satisfies the law of mass action; it reduces to an SCC unary distribution for clusters of a single component; and it produces physically acceptable evaporation rate coefficients that also satisfy the new kinetic product rule. Since it is possible to construct other examples of similarly well-behavedmore » distributions, our result is not unique in this respect, but it does give reasonable predictions. As an illustration, we calculate binary nucleation rates and vapor activities for the ethanol--hexanol system at 260 K using the new SCC distribution and compare them to experimental results. The theoretical rates are uniformly higher than the experimental values over the entire vapor composition range. Although the predicted activities are lower, we find good agreement between the measured and theoretical slope of the critical vapor activity curve at a constant nucleation rate of 10{sup 7} cm{sup {minus}3} s{sup {minus}2}.« less

Authors:
;  [1]
  1. Lawrence Livermore National Laboratory, Livermore, California 94551-9900 (United States)
Publication Date:
OSTI Identifier:
72779
DOE Contract Number:  
FG02-92ER14257; W-7405-ENG-48
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 103; Journal Issue: 3; Other Information: PBD: 15 Jul 1995
Country of Publication:
United States
Language:
English
Subject:
66 PHYSICS; NUCLEATION; MOLECULAR CLUSTERS; SIZE; EVAPORATION; DISTRIBUTION FUNCTIONS; BINARY MIXTURES; CHEMICAL COMPOSITION; KINETICS; STATISTICAL MECHANICS; ETHANOL; HEXANOLS

Citation Formats

Wilemski, G, Wyslouzil, B E, Department of Chemical Engineering, Worcester Polytechnic Institute, Worcester, Massachusetts 01609-2280, and Physical Sciences Inc., Andover, Massachusetts 01810-1077. Binary nucleation kinetics. I. Self-consistent size distribution. United States: N. p., 1995. Web. doi:10.1063/1.469823.
Wilemski, G, Wyslouzil, B E, Department of Chemical Engineering, Worcester Polytechnic Institute, Worcester, Massachusetts 01609-2280, & Physical Sciences Inc., Andover, Massachusetts 01810-1077. Binary nucleation kinetics. I. Self-consistent size distribution. United States. https://doi.org/10.1063/1.469823
Wilemski, G, Wyslouzil, B E, Department of Chemical Engineering, Worcester Polytechnic Institute, Worcester, Massachusetts 01609-2280, and Physical Sciences Inc., Andover, Massachusetts 01810-1077. 1995. "Binary nucleation kinetics. I. Self-consistent size distribution". United States. https://doi.org/10.1063/1.469823.
@article{osti_72779,
title = {Binary nucleation kinetics. I. Self-consistent size distribution},
author = {Wilemski, G and Wyslouzil, B E and Department of Chemical Engineering, Worcester Polytechnic Institute, Worcester, Massachusetts 01609-2280 and Physical Sciences Inc., Andover, Massachusetts 01810-1077},
abstractNote = {Using the principle of detailed balance, we derive a new self-consistency requirement, termed the kinetic product rule, relating the evaporation coefficients and equilibrium cluster distribution for a binary system. We use this result to demonstrate and resolve an inconsistency for an idealized Kelvin model of nucleation in a simple binary mixture. We next examine several common forms for the equilibrium distribution of binary clusters based on the capillarity approximation and ideal vapor behavior. We point out fundamental deficiencies for each expression. We also show that each distribution yields evaporation coefficients that formally satisfy the new kinetic product rule but are physically unsatisfactory because they depend on the monomer vapor concentrations. We then propose a new form of the binary distribution function that is free of the deficiencies of the previous functions except for its reliance on the capillarity approximation. This new self-consistent classical (SCC) size distribution for binary clusters has the following properties: It satisfies the law of mass action; it reduces to an SCC unary distribution for clusters of a single component; and it produces physically acceptable evaporation rate coefficients that also satisfy the new kinetic product rule. Since it is possible to construct other examples of similarly well-behaved distributions, our result is not unique in this respect, but it does give reasonable predictions. As an illustration, we calculate binary nucleation rates and vapor activities for the ethanol--hexanol system at 260 K using the new SCC distribution and compare them to experimental results. The theoretical rates are uniformly higher than the experimental values over the entire vapor composition range. Although the predicted activities are lower, we find good agreement between the measured and theoretical slope of the critical vapor activity curve at a constant nucleation rate of 10{sup 7} cm{sup {minus}3} s{sup {minus}2}.},
doi = {10.1063/1.469823},
url = {https://www.osti.gov/biblio/72779}, journal = {Journal of Chemical Physics},
number = 3,
volume = 103,
place = {United States},
year = {Sat Jul 15 00:00:00 EDT 1995},
month = {Sat Jul 15 00:00:00 EDT 1995}
}