Effects of Diesel–Biodiesel–Ethanol–TiO₂ Nanoparticle Blended Fuels on the Performance and Emissions of a Direct Injection Diesel Engine

This study aimed to assess the emissions and performance of direct injection diesel engines operating with fuel blends consisting of diesel-biodiesel-ethanol-TiO₂ (D<i>x</i>B<i>y</i>E<i>z</i>Ti). The blend proportions were determined by analyzing the phase behaviors and fuel stability of D<i>x</i>B<i>y</i>E<i>z</i>Ti blends by using a phase behavior diagram. The emission characteristics and performance of the diesel engines were examined at varying speeds ranging from 1100 to 2300 rpm and different engine loads of 25, 50, and 75% using the following four remaining fuel blends: D40B50E10Ti, D30B60E10Ti, D20B70E10Ti, and D10B80E10Ti. In terms of engine performance at 50% engine load and 2300 engine speed, the results indicated that the brake specific fuel consumption of all fuel blends was higher than that of diesel but lower than that of biodiesel. This was attributed to the oxygenated additives TiO₂ and ethanol, which assisted in improving the atomization of the fuel blends. The brake thermal efficiency of D20B70E10Ti was 1.23% higher than that of diesel. The addition of oxygenated metal-based TiO₂ nanoparticles with a high surface area to volume ratio resulted in better fuel oxidation. In terms of engine emissions under the same engine conditions, D20B70E10Ti exhibited reduced CO, CO₂, NO _<i>x</i> , and smoke opacity levels by 7.44, 37.12, 66.29, and 69.43%, respectively, compared to diesel. Consequently, the results of this study suggest that the D20B70E10Ti blend is viable for use in unmodified diesel engines, enhancing their BTE and reducing emissions.