Morphological characteristics of particles emitted from combustion of different fuels in improved and traditional cookstoves

Abstract

The study was conducted to analyze the morphological aspects of particle emitted from improved and traditional cookstoves when used with different fuel combinations. The particles were sampled using hood method under actual cooking process performed in controlled laboratory conditions. The sample preparation was done using wet technique which was also compared to dry technique for transferring particles on to the transmission electron microscopy (TEM) grid. The density and parameter fractal dimension 2D-DDf and PDf was calculated using box count algorithm developed using Python language. The 3D-DDf was calculated using ensemble approach and other shape descriptors were also measured using image processing software. The distribution of primary particle, particle agglomerates and tar balls were also studied. The 3D-DDf for particles emitted from traditional cookstove with wood as fuel was 2.42 compared to a lower 3D-DDf of 1.82 in PF cookstove. The 3D-DDf along with fractal prefactor (kg) of 0.7 and 1.4 indicated circular and dense particles emitted from TR cookstove with wood as fuel. On the contrary, with Mix-2 and Mix-3, the particles emitted from improved cookstoves had 3D-DDf>2 indicating presence of super soot aggregates. The distribution of primary particle and tar balls indicated count median diameter (CMD) in the range of 15–25nm and 64–104nm respectively for all cookstove–fuel combinations. The distribution of equivalent area diameter of aggregates showed maximum particles of 300–400nm range as evident in other physical characterization studies conducted using instruments that work light scattering principle and electrical mobility of particles.