Exergetic and exergoeconomic analyses of a CI engine fueled with diesel-biodiesel blends containing various metal-oxide nanoparticles

Highlights: • Comprehensive exergetic, exergoeconomic and sustainability analyses of nanoparticle-doped diesel-biodiesel blends. • Detailed comparison of Al₂O₃, SiO₂, and TiO₂ nanoparticles at the same fraction. • Better results with the doping of nanoparticles into neat diesel fuel or diesel-biodiesel blend in all cases. • Observed the worst results with TiO₂-doped test fuel among nanofuels. • Al₂O₃-doped test fuel is the best exergetically-sustainable fuel among all test fuels. Comprehensive exergetic and exergoeconomic analyses of a single-cylinder, four-stroke, naturally aspirated compression ignition (CI) diesel engine were conducted in the present paper. Exergy-based sustainability indicators were also determined in the study. The test engine was fueled with diesel fuel (D100), %90 diesel+10% waste cooking oil methyl ester blend (D90B10), D90B10 with Al₂O₃ nanoparticle of 100 ppm (D90B10Al₂O₃), D90B10 with TiO₂ nanoparticle of 100 ppm (D90B10TiO₂), and D90B10 with SiO₂ nanoparticle of 100 ppm (D90B10SiO₂) nanofuels, separately. The tests were performed at a constant engine speed of 2000 rpm and at varying engine loads from 2.5 to 10 Nm with an increment of 2.5 Nm. As a result, the exergy efficiencies of the test engine for D90B10 and D90B10Al₂O₃ were determined to be 25.57% and 28.12%, respectively. The lowest cost flow rate of crankshaft work was found to be 0.4247 US$/h at 2.5 Nm, 0.5154 US$/h at 5 Nm for D90B10Al₂O_3, and 0.6029 US$/h at 7.5 Nm, 0.7253 US$/h at 10 Nm for D90B10SiO₂. At 10 Nm, the highest and lowest sustainability index values were determined to be 1.391 for D90B10Al₂O₃ and 1.344 for D90B10, respectively. From the perspective of exergy and sustainability, D90B10Al₂O₃ had the best results. Besides, from the perspective of exergoeconomics, D90B10Al₂O₃ had the best results at lower engine loads. As a conclusion, it can be said that nanofuels showed better performances compared to neat diesel fuel and diesel-biodiesel blend in the terms of in terms of exergy, exergoeconomics, and sustainability analyzes. Considering all analyses together, it is noticed that Al₂O₃-doped nanofuel is the best test fuel for this study, and then it is followed by SiO₂ and TiO₂-doped nanofuels, respectively.