The effect of biodiesel and CeO2 nanoparticle blends on the CRDI diesel engine: a special focus on combustion, particle number, PM2.5 species, organic compound, and gaseous emissions

This study aimed to investigate the effect of biodiesel and CeO2 nanoparticles (NPs) blends on organic car- bon (OC) and elemental carbon (EC), organic compounds, size distribution, gaseous emissions, and com- bustion reactivity from a CRDI diesel engine at the steady-state mode. To ensure that gaseous pollutants do not depend on a filter device, the research engine was allowed to operate without a diesel particulate filter. The nano-additive of 20 ppm was included in various biodiesel blends through the ultrasonication process. Experimental results revealed that the addition of biodiesel in CeO2 NP blends significantly improved the in-cylinder pressure and heat released rate (HRR) of the engine. As for the B15C20 fuel, sig- nificant reductions in CO and HC emissions were observed by 32.16% and 45.59%, respectively, with a rise in NOx of 5.97% compared to B0. It was also found that the B0 and B0C20 fuels generate more particles within a diameter size range over 50 nm compared to B10C20 and B15C20 that generate particles of diameter ranging from ∼10 nm to 37 nm. EC-soot was slightly higher compared to OC for all test fuels, which could be explained by the catalytic effect of metals on soot oxidation as a result of the low amount of total PM2.5 mass present. The toxic pollutants such as polycyclic aromatic hydrocarbons (PAHs) and n- alkanes decreases when the ratio of biodiesel increases in CeO2 NPs. This might reduce the effect of can- cer and direct eye irritants that cause an allergic response in humans and animals.