An Investigation of Diesel Fuel Composition-Exhaust Emission Relationships.

The present investigation has been conducted to study the effects of hydrocarbon composition and additive content of diesel fuels on exhaust pollutant emissions. The reported results were obtained using a two-cylinder, four-stroke cycle Onan diesel engine-generator unit instrumented for exhaust emissions measurements. Seven different fuels and fuel blends having aromatic contents varying from 0 to 74 percent and cetane numbers from 37 to 71 were investigated. The results of this study demonstrate that increasing concentrations of aromatic hydrocarbons in the fuel significantly increase emission of oxides of nitrogen while slightly decreasing the emission of unburned hydrocarbons, while other fuel characteristics, including cetane number, remain essentially constant. A full-scale, six-cylinder military engine LDT-465 was used to verify the aromatics vs NOx relationship obtained with the Onan motor-generator unit.