ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-4-439-2004 Volatile particles formation during PartEmis: a modelling study Vancassel X. 1 5 Sorokin A. 2 Mirabel P. 1 Petzold A. 3 Wilson C. 4 Centre de Géochimie de la Surface, Université Louis Pasteur, Strasbourg, France Central Institute for Aviation Motors, Moskow, Russia Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen, Germany QinetiQ, Farnborough, UK now at: Atmospheric, Oceanic and Planetary Physics, University of Oxford, UK 17 03 2004 4 2 439 447 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/4/439/2004/acp-4-439-2004.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/4/439/2004/acp-4-439-2004.pdf

A modelling study of the formation of volatile particles in a combustor exhaust has been carried out in the frame of the PartEmis European project. A kinetic model has been used in order to investigate nucleation efficiency of the H<sub>2</sub>O-H<sub>2</sub>SO<sub>4</sub> binary mixture in the sampling system. A value for the fraction <IMG WIDTH="10" HEIGHT="13" ALIGN="BOTTOM" BORDER="0" src="acp-4-439-img1.gif" ALT="$varepsilon$"> of the fuel sulphur S(IV) converted into S(VI) has been indirectly deduced from comparisons between model results and measurements. In the present study, <IMG WIDTH="10" HEIGHT="13" ALIGN="BOTTOM" BORDER="0" src="acp-4-439-img1.gif" ALT="$varepsilon$"> ranges between roughly 2.5% and 6%, depending on the combustor settings and on the value assumed for the parameter describing sulphuric acid wall losses. Soot particles hygroscopicity has also been investigated as their activation is a key parameter for contrail formation. Growth factors of monodisperse particles exposed to high relative humidity (95%) have been calculated and compared with experimental results. The modelling study confirms that the growth factor increases as the soot particle size decreases.