Abstract: The reduction of greenhouse gas emissions is a demand for the solid contribution replacement of oil-derived transportation fuels with alternatives as ethanol and methanol. Exhaust gas recirculation (EGR) is from the most effective techniques for reducing NOx emissions in compression ignition engines. A 4-cylinder four stroke water cooled direct injection (DI) Fiat diesel engine used for conducting tests with (10% ethanol or 10% methanol) oxygenates blends with diesel fuel combined with EGR technique. The study focused on the trade-off between NOx and PM. The results show that the PM concentration decreases regardless of the types of oxygenating additives, and it decreases with the increase of the oxygen mass fraction in the blends without increasing the NOx. The emitted PM concentrations from diesel engine increased when fuelled with pure diesel fuel and equipped with EGR. Engine operation on the diesel- oxygenate blends presents a remarkable reduction in NOx/ PM concentrations.
Keywords: NOx-PM trade-off, methanol, ethanol, EGR.