Mixing, Combustion and Soot Characteristics of Diesel/Waste Cooking Oil Biodiesel Blend with Al2O3 Nanoparticles Additive

Waste Cooking Oil (WCO) biodiesel can be used as fuel by blending with diesel in suitable fractions to cope with the global energy transition. In that context, the present study aims to understand the chemical nature as well as the mixing behavior of waste cooking oil with diesel through FTIR. The soot particles from the engine exhaust have been characterized through analysis, such as SEM/EDAX and XRD. The study is also extended to identify traces of nanoparticles used in the blend to obtain better spray characteristics. The physical nature of soot of B20 is different from that of diesel fuel, as waste cooking oil contains excess oxygen in it compared to diesel. The oxygen bonds of waste cooking oil biodiesel are exhibited through FTIR spectra. Furthermore, FTIR for diesel, diesel+20%WCO (B20) fuel, and pure WCO fuel are compared in the preliminary study and thereby the effect of adding WCO to diesel for its basic chemical nature is verified. The main characteristics of WCO fuel in FTIR are C = O and C–O in 1734 cm⁻¹ and 1214–1362 cm⁻¹, respectively. The FTIR spectra of B20 and diesel are compared, and there are no significant changes in their patterns, indicating that up to 20% of the blending does not affect the chemical nature of the blend. Elemental analysis is carried out for the soot particles using SEM/EDX for B20 fuel with the addition of Al2O3 nanoparticles. The beneficial effect of adding Al2O3 exhibited a substantial reduction in oxygen content in soot particle emissions for the B20 fuel. It is also observed emission of Al2O3 along with soot for B20+ Al2O3.