Effects of high sulphur content in marine fuels on particulate matter emission characteristics

摘要

The effect of high sulphur level in marine fuels on diesel exhaust particulate number distributions and mass concentrations was investigated. A strong correlation between increase of emitted particle mass and number and increase in fuel sulphur content was found, with the most affected particles found in the nanoparticle size range. These par-ticulates consist of nucleated/condensed hydrocarbon and sulphur compounds, which are potentially the most hazardous to human health. Nucleation mode particles were found to be greatly affected by primary dilution temperature (PDT), an increase in which cause the vapour pressures of volatile species to rise, considerably slowing down the nucleation process. However, even at PDT=400℃ this mode was not entirely eliminated, since with high-sulphur fuels the concentrations of nucleation-prone vapour-phase volatile components are very high, and higher primary (and overall) dilution ratios are therefore required. The soot fraction, which made up most of the particle mass, was only slightly affected by sulphur content and is unaffected by PDT, although it was influenced by engine operating parameters such as load and speed.