Effect of sintering on the fractal prefactor of agglomerates

Abstract

In a previous study different agglomerates composed by a variable number of primary particles corresponding to extreme and intermediate values of fractal dimension (Df=1, 2 and 3) were characterized to be used as reference shapes in a method for the determination of the fractal dimension of actual agglomerates. In that work, primary particles were assumed to be spherical and with no sintering or necking effects. In this work, the geometrical effect of processes such as coalescence, sintering, flattening, or surface growth is considered to evaluate the impact of these phenomena in the morphological parameters of fractal-like agglomerates. A sintering coefficient is firstly defined. Afterwards, the moment of inertia and radius of gyration of the agglomerate are determined and finally the prefactor of the power–law relationship is obtained as a function of the number of primary particles and the sintering coefficient. The equations proposed are used in a geometrical method to determine the fractal dimension of soot agglomerates, showing that sintering increases the prefactor significantly, which leads to a slight decrease in the fractal dimension of the agglomerates.