Effect of a carrier gas on nucleation in diffusion chambers

Itkin, A. L.

doi:10.1016/s0021-8502(98)00526-6

Cited by 3 publications

(4 citation statements)

References 2 publications

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“…This is true unless transport of this molecule to the surface of the cluster is regulated by diffusion of the molecule through the background gas, and the rate of chemical reaction (attachment of the molecule to the cluster) is much more than the rate of diffusion. As shown in [1] typical conditions in DCC just meet these requirements and hence this is the case when nucleation kinetics is a diffusion-limited one.…”

Section: Main Idea Of the Theorymentioning

confidence: 91%

“…First we have to discuss the main physical idea of our theory that in more detail is given in [1]. We consider nucleation process when a certain molecule attaches a cluster.…”

Section: Main Idea Of the Theorymentioning

confidence: 99%

“…According to our microscopic nucleation theory (MNT) [2] a studying mixture of gases and clusters is treated as a mixture of ideal gases each of that is characterized by the size of the identical clusters composing it. Continuity and diffusion equations for the mixture components obtained in the Navier-Stokes approximation are used, that based on the analysis of the DCC operation specificity and our asymptotic method [1,3] we managed to analytically solve, obtaining the following representation for concentrations HJ of clusters withy molecules…”

Section: Solution Of Kinetic Equationsmentioning

confidence: 99%

“…Here nj e is the equilibrium concentration [2], parameter y is introduced as a cluster size being a boundary between two kinds of solution. In [1] an equation for y is derived which takes a simple form if S exceeds approximately 1.5 (as it usually takes place in a zone of active nucleation in experiments in DCC) 2b 4X0-( 3m l 3/' 3 ŵ here a is surface tension. At 0/=7, y coincides with the critical size.…”

Section: - L -Rmentioning

confidence: 99%

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Kinetic theory of a carrier gas effect on nucleation in diffusion chambers

Itkin¹

2000

AIP Conference Proceedings

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Kinetic theory is presented which proposes an explanation of a carrier gas effect on nucleation in DCC. The main idea of this theory is that for DCC transport of condensing molecules to the cluster surface is determined by their diffusion through a carrier gas that results in new kinetic equations or, in other words, in usual kinetic equations where rate constants of the cluster formation depends upon carrier gas pressure. Analytical dependencies of critical supersaturation S* and derivative dS*/dT on a carrier gas pressure P 0 , temperature T and the nature of the carrier gas are derived that reproduce experimental data of Heist and co-authors.

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Section: Main Idea Of the Theorymentioning

confidence: 91%

“…First we have to discuss the main physical idea of our theory that in more detail is given in [1]. We consider nucleation process when a certain molecule attaches a cluster.…”

Section: Main Idea Of the Theorymentioning

confidence: 99%

Section: Solution Of Kinetic Equationsmentioning

confidence: 99%

Section: - L -Rmentioning

confidence: 99%

See 2 more Smart Citations

Kinetic theory of a carrier gas effect on nucleation in diffusion chambers

Itkin¹

2000

AIP Conference Proceedings

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Theoretical prediction of a carrier gas effect under nucleation in thermal diffusion chambers

Itkin¹

2000

Chemical Physics

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Complete thermodynamically consistent kinetic model of particle nucleation and growth: Numerical study of the applicability of the classical theory of homogeneous nucleation

Чесноков

Krasnoperov

2007

The Journal of Chemical Physics

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A complete thermodynamically consistent elementary reaction kinetic model of particle nucleation and growth from supersaturated vapor was developed and numerically evaluated to determine the conditions for the steady-state regime. The model treats all processes recognized in the aerosol science (such as nucleation, condensation, evaporation, agglomerationcoagulation, etc.) as reversible elementary reactions. It includes all possible forward reactions (i.e., of monomers, dimers, trimers, etc.) together with the thermodynamically consistent reverse processes. The model is built based on the Kelvin approximation, and has two dimensionless parameters: S0-the initial supersaturation and Theta-the dimensionless surface tension. The time evolution of the size distribution function was obtained over the ranges of parameters S0 and Theta. At low initial supersaturations, S0, the steady state is established after a delay, and the steady-state distribution function corresponds to the predictions of the classical nucleation theory. At high initial supersaturations, the depletion of monomers due to condensation on large clusters starts before the establishing of the steady state. The steady state is never reached, and the classical nucleation theory is not applicable. The boundary that separates these two regimes in the two dimensionless parameter space, S0 and Theta, was determined. The model was applied to several experiments on water nucleation in an expansion chamber [J. Wolk and R. Strey, J. Phys. Chem. B 105, 11683 (2001)] and in Laval nozzle [Y. J. Kim et al., J. Phys. Chem. A 108, 4365 (2004)]. The conditions of the experiments performed using Laval nozzle (S0=40-120) were found to be close to the boundary of the non-steady-state regime. Additional calculations have shown that in the non-steady-state regime the nucleation rate is sensitive to the rate constants of the initial steps of the nucleation process, such as the monomer-monomer, monomer-dimer, etc., reactions. This conclusion is particularly important for nucleation from supersaturated water vapor, since these processes for water molecules at and below the atmospheric pressure are in the low pressure limit, and the rate constants can be several orders of magnitude lower than the gas kinetic. In addition, the impact of the thermodynamic inconsistency of the previously developed partially reversible kinetic numerical models was assessed. At typical experimental conditions for water nucleation, S0=10 and Theta=10 (T=250 K), the error in the particle nucleation rate introduced by the thermodynamic inconsistency exceeds one order of magnitude.

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Effect of a carrier gas on nucleation in diffusion chambers

Cited by 3 publications

References 2 publications

Kinetic theory of a carrier gas effect on nucleation in diffusion chambers

Kinetic theory of a carrier gas effect on nucleation in diffusion chambers

Theoretical prediction of a carrier gas effect under nucleation in thermal diffusion chambers

Complete thermodynamically consistent kinetic model of particle nucleation and growth: Numerical study of the applicability of the classical theory of homogeneous nucleation

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