Reducing the Effect of High Sulfur Content in Diesel Fuel on NO(x) Emissions and PM Characteristics Using a PPCI Mode Engine and Gasoline–Diesel Blends

[Image: see text] Recently, high sulfur content in diesel fuel is one of the main problems that have an effect on combustion and emission characteristics. Iraq is one of many countries in the world that use diesel fuel with high sulfur content. Therefore, the partially premixed combustion ignition (PPCI) concept and different blend ratios of gasoline–diesel (GD30, GD40, and GD50) were suggested in this study to reduce the sulfur content in the fuel, improve the engine performance, and reduce the exhaust emissions. The combined effect of adding gasoline to the diesel fuel and manipulating the fuel injection timings can lead to better and clean combustion. For the same engine operating conditions, it is found that the brake thermal efficiency (BTE) decreases during the combustion of GD blends in comparison with diesel fuel. Furthermore, the results of using GD blends showed a small reduction in brake-specific fuel consumption (BSFC) compared to the conventional diesel fuel. The exhaust gas temperature reduces from the combination effect of PPCI mode and GD blends, which in turn decreases the NO(x) emission concentration under variable conditions of engine loads and speeds. It is indicated that the NO(x) emissions significantly decreased during the combustion of GD30, GD40, and GD50 blends by 25.94, 50.9, and 84%, respectively, in comparison with diesel fuel. In addition, higher reduction in CO and HC formation was obtained during the combustion of conventional fuel in comparison with the combustion of GD blends. The results showed that the number and concentration of PM reduced more when using GD blends and PPCI mode. The average particle diameter (d(p)) decreased from the combustion of GD blends in comparison with diesel fuel. The particle diameter of the GD blend was varied from 25 to 26 nm compared to those of diesel fuel of 35 and 36 nm under the same engine operating conditions. Reducing the sulfur content in GD blends contributed to a clear reduction in SO(2) and H(2)S emissions by 57.85 and 50.12%, respectively.