Validation of experimental and gradient boosting regressor model for predicting performance, combustion, emission, and biomedical implications of cerium oxide (CeO₂)-augmented B20 biodiesel blends derived from used temple oil

The global decline in fossil fuel availability and rising environmental concerns have intensified the search for sustainable alternative fuels, with biodiesel emerging as a promising option. This study investigates the performance, combustion, and emission characteristics of a B20 biodiesel blend derived from Used Temple Oil Methyl Ester (UTOME) enhanced with cerium oxide (CeO₂) nano additives. Conducted at constant speed and varying engine loads, the experiments show that CeO₂ additives significantly enhance brake thermal efficiency (BTE), with the B20UTOME100CeO₂ blend achieving efficiency levels comparable to pure diesel. Specific fuel consumption (SFC) decreases as CeO₂ concentration increases, reflecting enhanced fuel efficiency, while higher cylinder pressure (CP) and net heat release (NER) signify improved combustion processes. Emission analysis reveals substantial reductions in hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx), with the B20UTOME100CeO₂ blend demonstrating the lowest HC and NOx emissions due to better fuel atomization, improved combustion efficiency, and lower peak combustion temperatures enabled by the CeO₂ nanoparticles. The B20UTOME100CeO₂ blend demonstrated enhanced performance at maximum load, exhibiting a 1.57% increase in Brake Thermal Efficiency, a 6.67% reduction in Specific Fuel Consumption, a 2.83% elevation in cylinder pressure, and a 5.95% greater heat release when compared to conventional diesel. Emissions analysis revealed a significant reduction in carbon monoxide by 66.67%, hydrocarbons by 13.51%, and nitrogen oxides by 0.20% relative to diesel. A gradient boosting regressor model was trained on experimental data comprising fish oil biodiesel blends with nanoparticle additives, utilizing Python libraries. The accuracy of the model is supported by a mean squared error of 0.7647 for HC emissions and R² scores of 0.9247 and 0.9882 for HC and NOx emissions, respectively. Overall, the results indicate that B20UTOME with 100 ppm CeO₂ additives offers a viable alternative to diesel, providing improved thermal efficiency, enhanced combustion, and reduced harmful emissions. The marked reduction in toxic emissions, including CO, HC, and NOx, carries significant biomedical relevance. These pollutants are known to induce respiratory, cardiovascular, and neurological disorders upon prolonged exposure. Therefore, implementing CeO₂-enhanced biodiesel blends offers a potential strategy for protecting public health by diminishing harmful exhaust emissions.