The effects of fuel composition, properties, and additives on soot production in an optically accessible D.I. diesel engine

This study utilizes laser diagnostics in an optically-accessible diesel engine to evaluate the impact of diesel fuel components, physical properties of a fuel, and additives on soot production. The laser diagnostics employed include laser light extinction, light scattering, and laser-induced incandescence (LII). Light extinction or LII data alone allows quantitative determination of particle volume fraction. Rayleigh as well as Mie theory analysis of simultaneously recorded extinction and light scattering, or LII and light scattering signals, provides quantitative measurement of particle diameter and number density.; The influences on soot production of two major fuel components, aromatic compounds and sulfur, were investigated. The effect of differing 90% boiling point temperatures (T90s) in fuels on particle production was investigated using two low-sulfur British Petroleum fuels with mostly similar physical properties. The effects of several additives on particle production were investigated by combining them with two-component representative non-aromatic and three-component representative aromatic fuels.; The simultaneous light scattering/LII technique showed it is possible to use this laser diagnostic to detect the general influence of additives and fuel components on particle volume fraction, diameter, and number density trends. Unfortunately, the time-consuming nature of this optical technique made acquisition of enough “repeated-condition” data to establish a representative result difficult. The light extinction optical diagnostic offered a less labor-intensive, repeatable method of obtaining time-resolved soot mass concentrations which readily showed the impact of additives and fuel modifications. The simultaneous light scattering/extinction offered both the advantages and capabilities of the light extinction and the simultaneous light scattering/LII techniques.