Experimental investigation to reduce exhaust emissions in a single cylinder CI engine fuelled with methyl ester of neem oil using antioxidant (L-ascorbic acid)

Biodiesel offers cleaner combustion over conventional diesel fuel, including reduced particulate matter, carbon monoxide and unburned hydrocarbon emissions. However, several studies point to a slight increase in NOx emissions (about 13%) for biodiesel fuel compared with conventional diesel fuel. The use of antioxidant additives is one of the most cost-effective ways to reduce the formation of NOx. In this study, the effect of antioxidant additive (L-ascorbic acid) on NOx emissions in a neem methyl ester fuelled direct injection diesel engine has been investigated experimentally. The antioxidant additive is mixed in various proportions with neem methyl ester and was tested in computerized four-stroke, water-cooled single cylinder diesel engine of 3.5 kW rated power. Results show that the antioxidant additive is effective in controlling the emissions like NOx, HC and CO2 of neem biodiesel fuelled diesel engines. Particularly for LA300 mixture, NOx emissions reduce by 16.95% at full load conditions due to the delay or inhibitions of the oxidative process by donating an electron or hydrogen atom to a radical derivative. However, there is a slight increase in carbon monoxide emissions to a slight decrease in brake thermal efficiency.