Exploring the relationship between fuel injection pressure and nanoparticle additives on the combustion, performance and emission characteristics of diesel engine fueled with animal waste-based blends

•Injection pressure varied from 180 bar to 240 bar.•Two types of nanoparticles, Ce2O3 and TiO2, were dispersed in 20 % biodiesel blends at a concentration of 50 ppm.•Increasing engine load and injection pressure improved BTE levels, with Ce2O3 blend reporting the highest BTE.•Ce2O3 nanoparticles were found to be more effective than TiO2 in reducing emissions. The current study investigated the effect of varying injection pressure on a diesel engine fueled with waste animal fats oil. The injection pressure varied from 180 bar to 240 bar, and parameters such as engine performance, combustion, and emission characteristics were determined. In addition to the biodiesel blends, two types of nanoparticles, Ce2O3 and TiO2, were studied. A series of tests were conducted on a single-cylinder diesel engine. Both nanoparticles were dispersed in the biodiesel blends at a concentration of 50 ppm. The results indicated that increasing the engine load and injection pressure improved the brake thermal efficiency levels. The use of Ce2O3 along with the blend reported the highest BTE due to its oxygen content during combustion. Higher injection pressure improved spray characteristics and combustion stability, resulting in better combustion efficiency. However, excessive pressure rise can lead to combustion instability and higher emissions. Ce2O3 nanoparticles were found to be more effective than TiO2 in reducing the emission of hydrocarbons, nitrogen oxides, carbon monoxide, and soot. Meanwhile, increasing injection pressure can help mitigate hydrocarbon formation and reduce nitrogen oxide emissions, while Ce2O3 nanoparticles promote a more efficient combustion process. The blend with 20 % biodiesel and 50 ppm of Ce2O3 at 240 bar reported the lowest emissions. On the other hand, 20 % biodiesel with 50 ppm of TiO2 at 240 bar showed the lowest smoke opacity emissions. The study concludes that Ce2O3 nanoparticles and increased injection pressure hold promise in reducing emissions and improving combustion efficiency.