Modelling & Simulation


Large eddy simulation of spray flame synthesis of silica nanoparticles

Andreas Rittler, University of Duisburg-Essen, Duisburg, Germany
Irenäus Wlokas, University of Duisburg-Essen, Duisburg, Germany
Andreas Kempf, University of Duisburg-Essen, Duisburg, Germany

The synthesis of nanoparticles from the gas phase enables scalable and continuous processes. Oxidic particles are preferably made from flames, doped with a gaseous metal containing a precursor [1]. The choice of the precursor is mostly limited by its vapor pressure. This limit is expanded in the flame spray pyrolysis (FSP) where the metal containing compound is solved in a combustible liquid and injected into the flame [2].

The synthesis of silica nanoparticles from spray flames was investigated in several experimental and computational studies [2-5]. We present the first large eddy simulation of the FSP process. For consistency with available literature, we investigated a standard reactor with an ethanol/oxygen flame and hexamethyldisiloxane (HMDSO) as silica precursor dissolved in ethanol. The spray flame is stabilized by a premixed methane/oxygen pilot flame. The gas and the dispersed particle phase are modelled in the Eulerian frame, while the spray droplets are described in the Lagrangian frame. The gas phase chemistry of combustion and particle species formation is described by a tabulated chemistry model, adapted from the premixed flamelet generated manifold approach (PFGM) with artificial flame thickening, including the particle nucleation source term. The particle dynamics (formation, coagulation and coalescence) are described in terms of number, volume and surface area concentration. The simulation results for the particles are presented and discussed, in particular particle size distributions resulting from turbulence.

The work was supported by AiF (grant No. 18298N/3), the state North Rhine-Westphalia, Germany, and the Center for Computational Sciences and Simulations of the University Duisburg-Essen.

[1] P. Roth, Particle synthesis in flames, Proceedings of the combustion institute, 31 (2007) 1773-1788.
[2] L. Mädler, H. Kammler, S. E. Pratsinis, R. Mueller, Journal of Aerosol Science, 33 (2002) 369–389.
[3] K. Wegner, W. J. Stark, S. E. Pratsinis, Materials Letters 55 (2002) 318–321.
[4] S. R. Engel, A. F. Koegler, Y. Gao, D. Kilian, M. Voigt, T. Seeger, W. Peukert, A. Leipertz, Applied Optics 51 (2012) 6063–6075.
[5] D. Kilian, S. Engel, B. Borsdorf, Y. Gao, A. F. Koegler, S. Kobler, T. Seeger, S. Will, A. Leipertz, W. Peukert, Journal of Aerosol Science 69 (2014) 82 – 97.

« back