A new atmospheric aerosol phase equilibrium model (UHAERO): organic systems N. R. Amundson1, A. Caboussat1, J. W. He1, A. V. Martynenko1, C. Landry2, C. Tong3, and J. H. Seinfeld3 1Department of Mathematics, University of Houston, Houston, USA 2Chaire d'Analyse et Simulation Numériques, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland 3Departments of Chemical Engineering and Environmental Science and Engineering, California Institute of Technology, Pasadena, USA
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.
Citation: Amundson, N. R., Caboussat, A., He, J. W., Martynenko, A. V., Landry, C., Tong, C., and Seinfeld, J. H.: A new atmospheric aerosol phase equilibrium model (UHAERO): organic systems, Atmos. Chem. Phys., 7, 4675-4698, doi:10.5194/acp-7-4675-2007, 2007.