scholarly journals Effect of ions on sulfuric acid-water binary particle formation: 2. Experimental data and comparison with QC-normalized classical nucleation theory

2016 ◽  
Vol 121 (4) ◽  
pp. 1752-1775 ◽  
Author(s):  
J. Duplissy ◽  
J. Merikanto ◽  
A. Franchin ◽  
G. Tsagkogeorgas ◽  
J. Kangasluoma ◽  
...  
Keyword(s):  
Experimental Data ◽  
Sulfuric Acid ◽  
Particle Formation ◽  
Nucleation Theory ◽  
Acid Water ◽  
Classical Nucleation Theory

scholarly journals CFD modeling of a vehicle exhaust laboratory sampling system: sulfur driven nucleation and growth in diluting diesel exhaust

2015 ◽  
Vol 15 (2) ◽  
pp. 2905-2956 ◽  
Author(s):  
M. Olin ◽  
T. Rönkkö ◽  
M. Dal Maso
Keyword(s):  
Sulfuric Acid ◽  
Diesel Exhaust ◽  
Measurement Data ◽  
Particle Formation ◽  
Nucleation Theory ◽  
Acid Water ◽  
High Temporal Resolution ◽  
Computational Domain ◽  
Sampling System ◽  
Aerosol Model

Abstract. A new exhaust aerosol model CFD-TUTEAM (Tampere University of Technology Exhaust Aerosol Model for Computational Fluid Dynamics) was developed. The model can be used to simulate particle formation and evolution in diesel exhaust. The model has an Eulerian sub-model that provides spatial information within the computational domain, and a computationally less expensive Lagrangian sub-model that can be used to examine particle formation in a high temporal resolution. Particle formation in a laboratory sampling system that includes a porous tube type diluter and an aging chamber was modeled with CFD-TUTEAM. The simulation results imply that over 99% of new particles are formed in the aging chamber region, because nucleation rate remains at high level in the aging chamber due to low dilution ratio and low nucleation exponents. The nucleation exponents for sulfuric acid in sulfuric acid-water nucleation ranging from 0.25 to 1 appeared to fit best with measurement data, which are the same values as the slopes of volatile nucleation mode number concentration vs. raw exhaust sulfuric acid concentration obtained from the measurement data. These nucleation exponents are very low compared to the nucleation exponents obtained from the classical nucleation theory of binary sulfuric acid-water nucleation. The values of nucleation exponent lower than unity suggest that other compounds, such as hydrocarbons, might have a significant role in the nucleation process.

scholarly journals Effect of ions on sulfuric acid-water binary particle formation: 1. Theory for kinetic- and nucleation-type particle formation and atmospheric implications

2016 ◽  
Vol 121 (4) ◽  
pp. 1736-1751 ◽  
Author(s):  
Joonas Merikanto ◽  
Jonathan Duplissy ◽  
Anni Määttänen ◽  
Henning Henschel ◽  
Neil M. Donahue ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Particle Formation ◽  
Acid Water ◽  
Type Particle

The Effect of Turbulence and Real Gas Models on the Two Phase Spontaneously Condensing Flows in Nozzle

2013 ◽  
Author(s):  
Yogini Patel ◽  
Giteshkumar Patel ◽  
Teemu Turunen-Saaresti
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Navier Stokes ◽  
Two Phase ◽  
Real Gas ◽  
Spontaneous Condensation ◽  
Condensing Flows ◽  
Computational Fluid Dynamics Cfd

The aim of the paper is to analyse the effect of turbulence and real gas models on the process of spontaneous condensation in converging diverging (CD) nozzle by using commercial Computational Fluid Dynamics (CFD) code. The calculations were based on the 2-D compressible Navier-Stokes (NS) equations coupled with two-equation turbulence model, and the non-equilibrium spontaneous condensing steam flow was solved on the basis of the classical nucleation theory. The results were validated to the available experimental data.

scholarly journals New Parameterizations for Neutral and Ion-Induced Sulfuric Acid-Water Particle Formation in Nucleation and Kinetic Regimes

2018 ◽  
Vol 123 (2) ◽  
pp. 1269-1296 ◽  
Author(s):  
Anni Määttänen ◽  
Joonas Merikanto ◽  
Henning Henschel ◽  
Jonathan Duplissy ◽  
Risto Makkonen ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Particle Formation ◽  
Acid Water ◽  
Water Particle

scholarly journals Bacteria as Cloud Condensation Nuclei (CCN) in the Atmosphere

Atmosphere ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 786
Author(s):  
Mihalis Lazaridis
Keyword(s):  
Contact Angle ◽  
Sulfuric Acid ◽  
Cloud Condensation Nuclei ◽  
Sulfuric Acid Concentration ◽  
Contact Angles ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Condensation Nuclei ◽  
Critical Cluster ◽  
Model Simulations

Bacteria activation and cloud condensation nuclei (CCN) formation have been studied in the atmosphere using the classical theory of heterogeneous nucleation. Simulations were performed for the binary system of sulfuric acid/water using laboratory-determined contact angles. Realistic model simulations were performed at different atmospheric heights for a set of 140 different bacteria. Model simulations showed that bacteria activation is a potentially favorable process in the atmosphere which may be enhanced at lower temperatures. CCN formation from bacteria nuclei is dependent on ambient atmospheric conditions (temperature, relative humidity), bacteria size, and sulfuric acid concentration. Furthermore, a critical parameter for the determination of bacteria activation is the value of the intermolecular potential between the bacteria’s surface and the critical cluster formed at their surface. In the classical nucleation theory, this is parameterized with the contact angle between substrate and critical cluster. Therefore, the dataset of laboratory values for the contact angle of water on different bacteria substrates needs to be enriched for realistic simulations of bacteria activation in the atmosphere.

scholarly journals Nucleation and supersaturation in porous media (revisited)

2014 ◽  
Vol 78 (6) ◽  
pp. 1437-1447 ◽  
Author(s):  
M. Prieto
Keyword(s):  
Experimental Data ◽  
Porous Media ◽  
Interfacial Tension ◽  
Induction Time ◽  
Reactive Transport ◽  
Theoretical Calculations ◽  
Transport Processes ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Nucleation Time

Supersaturation-Nucleation-Time (S-N-T) diagrams are shown to be a useful tool to predict nucleation during reactive-transport processes in porous media. Such diagrams can be determined experimentally or estimated from theoretical calculations based on classical nucleation theory. With this aim, a ‘pragmatic’ understanding of the nucleation rate equation is adopted here and the meaning and magnitude of the interfacial tension and induction time discussed. Theoretical diagrams and experimental data are shown to match fairly well as long as there is an appropriate choice of the ‘relevant’ volume for induction-time calculations.

scholarly journals LaMer's 1950 model of particle formation: a review and critical analysis of its classical nucleation and fluctuation theory basis, of competing models and mechanisms for phase-changes and particle formation, and then of its application to silver halide, semiconductor, metal, and metal-oxide nanoparticles

2021 ◽  
Author(s):  
Christopher B. Whitehead ◽  
Saim Özkar ◽  
Richard G. Finke
Keyword(s):  
Reaction Mechanisms ◽  
Silver Halide ◽  
Metal Oxide Nanoparticles ◽  
Particle Formation ◽  
Phase Changes ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Wide Range ◽  
Competing Models ◽  
Chemical Reaction Mechanisms

Are classical nucleation theory and the 1950 LaMer model of particle formation supported for a wide range of particle formations, or do competing models in the form of chemical reaction mechanisms have better experimental support? Read on to find out.

scholarly journals Classical nucleation theory of immersion freezing: sensitivity of contact angle schemes to thermodynamic and kinetic parameters

2017 ◽  
Vol 17 (3) ◽  
pp. 1713-1739 ◽  
Author(s):  
Luisa Ickes ◽  
André Welti ◽  
Ulrike Lohmann
Keyword(s):  
Experimental Data ◽  
Contact Angle ◽  
Kinetic Parameters ◽  
Aerosol Particles ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Kinetic And Thermodynamic Parameters ◽  
Immersion Freezing ◽  
Thermodynamic And Kinetic Parameters ◽  
Homogeneous Freezing

Abstract. Heterogeneous ice formation by immersion freezing in mixed-phase clouds can be parameterized in general circulation models (GCMs) by classical nucleation theory (CNT). CNT parameterization schemes describe immersion freezing as a stochastic process, including the properties of insoluble aerosol particles in the droplets. There are different ways to parameterize the properties of aerosol particles (i.e., contact angle schemes), which are compiled and tested in this paper. The goal of this study is to find a parameterization scheme for GCMs to describe immersion freezing with the ability to shift and adjust the slope of the freezing curve compared to homogeneous freezing to match experimental data. We showed in a previous publication that the resulting freezing curves from CNT are very sensitive to unconstrained kinetic and thermodynamic parameters in the case of homogeneous freezing. Here we investigate how sensitive the outcome of a parameter estimation for contact angle schemes from experimental data is to unconstrained kinetic and thermodynamic parameters. We demonstrate that the parameters describing the contact angle schemes can mask the uncertainty in thermodynamic and kinetic parameters. Different CNT formulations are fitted to an extensive immersion freezing dataset consisting of size-selected measurements as a function of temperature and time for different mineral dust types, namely kaolinite, illite, montmorillonite, microcline (K-feldspar), and Arizona test dust. We investigated how accurate different CNT formulations (with estimated fit parameters for different contact angle schemes) reproduce the measured freezing data, especially the time and particle size dependence of the freezing process. The results are compared to a simplified deterministic freezing scheme. In this context, we evaluated which CNT-based parameterization scheme able to represent particle properties is the best choice to describe immersion freezing in a GCM.

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