Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 3 6 2003 10.5194/acpd-3-5803-2003 http://www.atmos-chem-phys-discuss.net/3/5803/2003/ http://www.atmos-chem-phys-discuss.net/3/5803/2003/acpd-3-5803-2003.html http://www.atmos-chem-phys-discuss.net/3/5803/2003/acpd-3-5803-2003.pdf 5803 5829 2003-11-18 Volatile particles formation during PartEmis: a modelling study X. Vancassel A. Sorokin P. Mirabel A. Petzold C. Wilson 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 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 H₂O-H₂SO₄ binary mixture in the sampling system. A value for the fraction <font face="Symbol">e</font> 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, <font face="Symbol">e</font> ranges between roughly 2.5% and 6%, depending on the combustor settings and on the microphysical approach used. 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.