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Particle growth by coalescence and agglomeration

Partikelwachstum durch Koaleszenz und Agglomeration
: Friedlander, S.K.; Koch, W.

Particle and particle systems characterization 8 (1991), Nr.1, S.86-89
ISSN: 0934-0866
Fraunhofer ITA ( ITEM) ()
agglomerate; coalescence; condensation; Koaleszenz; Kondensation; particles; Partikel; Primärpartikelgröße; size of primary particle

A dispersed system is considered which will form its condensed phase at high temperatures and is characterized by a high density of very small supercritical nuclei. It is assumed that particle growth is determined by coagulation and (viscous flow) coalescence. The morphology of the final particle depends on the temperature history of the formation process. Compact spherical particle and agglomerates may be formed. Agglomerates result when the process temperature decreases to an extent that coalescence is quenched in the course of the growth process. The average size of the primary particle in the agglomerates is calculated by using the analysis and the approximations described in a previous paper. The growth kinetics of the primary particle are presented in a dimensionless form. The results show that the dimensionless size of the primary particle depends only on the ratio of two characteristic lengths of the system. For small values of this ratio, the size of the primary particle compo sing the agglomerates, although much greater than the initially formed nuclei, is independent of the volume fraction of the condensed aerosol. For large values of this parameter, the theory merges into the classical theory of perfectly coalescing spheres.