An optimization problem related to the modeling of atmospheric organic aerosols

Amundson, Neal R.; Caboussat, Alexandre; He, Jiwen; Seinfeld, John H.; Yoo, Kee-Youn

doi:10.1016/j.crma.2005.04.018

Cited by 11 publications

(18 citation statements)

References 3 publications

(5 reference statements)

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“…Other numerically efficient approaches to find phase equilibrium, including those of n component mixtures, are available in the literature (e.g., Amundson et al, 2005Amundson et al, , 2007Zuend et al, 2010). Comparison for phase boundaries (x a , x b ) calculated using standard UNI-FAC parameters and the Eubank method used in this model, and standard UNIFAC parameter and the algorithm in the UHAERO model (Amundson et al, 2007) are in good agreement and summarized in the Supplement.…”

Section: Phase Equilibriummentioning

confidence: 57%

“…The relationship between critical supersaturation and dry diameter is then predicted using Köhler theory (Seinfeld and Pandis, 2006). The basic model mechanics are similar to those employed in multicomponent phase equilibrium models (Ming and Russell, 2002;Raatikainen and Laaksonen, 2005;Topping et al, 2005;Amundson et al, 2007;Zuend et al, 2008) but limited in scope to binary compositions and with focus on accurately representing phase and water activity at conditions relevant at the point of CCN activation only. These predictions are validated by manually mapping chemical composition to UNI-FAC groupings and comparing modeled CCN activity against observations from a compiled library of recently published CCN data of mostly weakly oxidized hydrocarbons containing a mixture of alcohol, carbonyl, aldehyde, ether, carboxyl, nitrate, and hydroperoxide moieties.…”

Section: D Petters Et Al: Prediction Of Cloud Condensation Nuclementioning

confidence: 99%

“…Some of these comparisons prompted proposed revisions of specific group interaction parameters, e.g., [OH] and [H 2 O]. Several thermodynamic models that treat complex phase equilibria of multifunctional, multicomponent organic mixtures are based on UNIFAC activity coefficients (Ming and Russell, 2002;Raatikainen and Laaksonen, 2005;Topping et al, 2005;Amundson et al, 2007;Zuend et al, 2008;Compernolle et al, 2009). The development of these models has been driven by the need to enable predictions over a wide range of conditions and compositions, including the effect of liquid-liquid phase separation on gas-to-particle partitioning (Zuend and Seinfeld, 2012;.…”

Section: D Petters Et Al: Prediction Of Cloud Condensation Nuclementioning

confidence: 99%

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Prediction of cloud condensation nuclei activity for organic compounds using functional group contribution methods

2016

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Abstract.A wealth of recent laboratory and field experiments demonstrate that organic aerosol composition evolves with time in the atmosphere, leading to changes in the influence of the organic fraction to cloud condensation nuclei (CCN) spectra. There is a need for tools that can realistically represent the evolution of CCN activity to better predict indirect effects of organic aerosol on clouds and climate. This work describes a model to predict the CCN activity of organic compounds from functional group composition. Following previous methods in the literature, we test the ability of semi-empirical group contribution methods in Köh-ler theory to predict the effective hygroscopicity parameter, kappa. However, in our approach we also account for liquidliquid phase boundaries to simulate phase-limited activation behavior. Model evaluation against a selected database of published laboratory measurements demonstrates that kappa can be predicted within a factor of 2. Simulation of homologous series is used to identify the relative effectiveness of different functional groups in increasing the CCN activity of weakly functionalized organic compounds. Hydroxyl, carboxyl, aldehyde, hydroperoxide, carbonyl, and ether moieties promote CCN activity while methylene and nitrate moieties inhibit CCN activity. The model can be incorporated into scale-bridging test beds such as the Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) to evaluate the evolution of kappa for a complex mix of organic compounds and to develop suitable parameterizations of CCN evolution for larger-scale models.

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Section: Phase Equilibriummentioning

confidence: 57%

Section: D Petters Et Al: Prediction Of Cloud Condensation Nuclementioning

confidence: 99%

Section: D Petters Et Al: Prediction Of Cloud Condensation Nuclementioning

confidence: 99%

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Prediction of cloud condensation nuclei activity for organic compounds using functional group contribution methods

2016

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“…the number of phases π and their compositions {y α , x α } α=1,π . The detailed description of the numerical solution of the PEP by a primal-dual interior-point algorithm is given by Amundson et al (2005bAmundson et al ( , 2006b. Essentially, the numerical minimization technique relies on a geometrical concept of phase simplex of the convex hull of the normalized GFE g n to characterize an equilibrium solution that corresponds to a global minimum of the total GFE G n .…”

Section: Modeling Approachmentioning

confidence: 99%

“…In the present work UHAERO is extended for determining the phase equilibrium of organicwater systems. The next section is devoted to a brief summary of the mathematical approach to solving the equilibrium problem, the details of which are given elsewhere (Amundson et al, 2005b(Amundson et al, , 2006b. Section 3 discusses general characteristics of organic phase equilibria, and presents a number of examples of organic phase equilibria calculated Published by Copernicus Publications on behalf of the European Geosciences Union.…”

Section: Introductionmentioning

confidence: 99%

A new atmospheric aerosol phase equilibrium model (UHAERO): organic systems

Amundson

Caboussat

et al. 2007

Atmos. Chem. Phys.

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Abstract. In atmospheric aerosols, water and volatile inorganic and organic species are distributed between the gas and aerosol phases in accordance with thermodynamic equilibrium. Within an atmospheric particle, liquid and solid phases can exist at equilibrium. Models exist for computation of phase equilibria for inorganic/water mixtures typical of atmospheric aerosols; when organic species are present, the phase equilibrium problem is complicated by organic/water interactions as well as the potentially large number of organic species. We present here an extension of the UHAERO inorganic thermodynamic model (Amundson et al., 2006c) to organic/water systems. Phase diagrams for a number of model organic/water systems characteristic of both primary and secondary organic aerosols are computed. Also calculated are inorganic/organic/water phase diagrams that show the effect of organics on inorganic deliquescence behavior. The effect of the choice of activity coefficient model for organics on the computed phase equilibria is explored.

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