Effects of fuel properties on exhaust emission from DI diesel engine

Exhaust emissions (HC, CO, NOx, PM, and PAH (polycyclic aromatic hydrocarbons in PM)) from a commercial DI diesel engine were measured for petroleum-derived fuels with a wide range of fuel properties. Fuel properties such as cetane number, aromatic content and type, and distillation temperature were adjusted to be independent from each other. The test results showed that total aromatic content was the controlling factor for NOx emission, and PM emission mainly depended on polycyclic aromatic content in the fuel. The increases in PM emission with increase in aromatics was mainly caused by the increase in SOF emission. Both of NOx and PM emissions were seldom affected by cetane number and 90% distillation temperature. Therefore, chemical characteristics of fuel are the controlling factor for NOx and PM emission, not the physical properties. The amount of sulfate in PM proportionally increased with increase in sulfur content of fuel. PAK emission was evaluated by analyzing SOF using a high performance liquid chromatography with a chemiluminesence detector. Also, the PAH highly depended on aromatic content, and the emission characteristics caused by aromatics was quite similar to PM emission.