Experimental Assessment of Waste Cooking Oil Biodiesel (UCME) Blends in a Diesel Engine

This study experimentally investigates the performance, combustion behavior, and emission characteristics of a single-cylinder, direct-injection compression ignition engine fueled with biodiesel derived from waste cooking oil (WCO). Used cooking oil methyl ester (UCME) was produced via alkaline transesterification using methanol and potassium hydroxide (KOH) and blended with commercial diesel at volumetric ratios of B2, B5, B7, and B10. Engine tests were conducted at a constant speed of 3000 rpm under varying load conditions. The physicochemical properties of UCME blends were found to be comparable to those of conventional diesel, enabling stable engine operation without modification. Performance analysis revealed that B7 and B10 blends improved brake thermal efficiency at higher loads, with B7 achieving up to 11.84% enhancement compared to diesel. However, biodiesel blends resulted in increased NOx emissions, reaching a maximum rise of 58.8% at full load, attributed to higher combustion temperatures and oxygen availability. CO emissions increased by up to 35% under certain conditions, while CO2 levels showed a moderate rise, indicating more complete carbon oxidation. Remarkably, the smoke level was greatly lessened, and B10 reached a maximum of 50% less than diesel, and it can be seen that the soot was successfully suppressed because biodiesel is oxygenated. All in all, the findings support the hypothesis about the viability and sustainability of the low-percentage UCME blends to be an alternative fuel to diesel engines to provide better thermal and high levels of smoke suppression, which is accompanied by the necessity of NOx reduction measures.