Technical Report 124, c4e-Preprint Series, Cambridge
Sooting tendency of surrogates for the paraffinic fractions of diesel and gasoline in diffusion flames
ref: Technical Report 124, c4e-Preprint Series, Cambridge
The influence of the chemical structure in the sooting characteristics of surrogates for the paraffinic fraction of gasoline and diesel fuel is studied experimentally. The experiment involves the combustion of the paraffin in a smoke point lamp (ASTM D1322). Differential mobility spectrometry is used to measure the particle size distribution (PSD) at different flame heights. The wick-fed laminar diffusion flame is sampled at the tip; the flame height is modified systematically from small heights to large heights (in some cases beyond the smoke point). Normal, iso and cyclo paraffins PSDs evolve in a similar way with flame height. At very low flame heights the PSD is unimodal, but rapidly evolves to a multi-modal one. The total number of particles decreases with flame height and approaches constant values for all considered fuels. As flame height increases so does the mean soot particle diameter until a height where a maximum is achieved and sustained. As the number of carbon atoms increases in the molecule the final mean soot particle diameter decreases. Cyclic and iso-paraffins produce soot particles with larger mean sizes compared to normal paraffins of the same carbon number.
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