Effect of nano-fuel additive on emission reduction in a biodiesel fuelled CI engine

The present investigation is to study the effect of Nano-fuel additives [Magnalium (Al-Mg) and cobalt oxide (Co₃O₄)] on the performance and emission characteristics of Jatropha biodiesel (B100) in a single cylinder, air cooled, direct injection diesel engine. Ball mill (Magnalium) and Sol-Gel (Cobalt oxide) processes were adopted for Nano-particle preparation. The obtained particle size range is from 38-70 nm. The particle size is characterised using scanning electron microscope (SEM). The Nano particles (100 mg/l) were dispersed in the fuel by an ultrasonicator with the assistance of optimised surfactant concentration. It was noticed that the addition of Nano cobalt oxide additive reduced specific energy consumption at part load and full load conditions. Cobalt oxide acts as an oxygen buffer which improves the combustion and reduces the emissions. The introduction of Nano-fuel additive resulted in maximum reduction of about 60% in unburnt hydrocarbon (UBHC) and 50% reduction in carbon monoxide at full load and 75% load respectively for neat biodiesel operation. It was observed that NO_x emission were higher at neat biodiesel operation compared with neat diesel operation and it was countered by introduction of Nano-fuel additive which resulted in 45% reduction in NO_x emission at the same biodiesel operation. Magnalium particles are highly energetic materials and it reduces the energy consumption and improves the thermal efficiency, the reason is that, the additive releases energy during combustion, in addition to the liquid fuel. Magnalium improves the atomisation by means of micro explosion phenomena and hence it reduces the pollution formation. Due to micro explosion, the air/fuel mixing will be proper and hence it results in 70% reduction in HC emission and 41% reduction in CO emission for B100 with additive at part load and full load conditions respectively. It was also noticed that, additive act as a heat sink and reduces the in-cylinder temperature which results in 30% reduction in NO_x emission at 75% load for B100 with additive.