Behavior of Particulate Matter Emissions in a Dual-Fuel Engine

Particulate matter (PM) emission from an internal combustion engine has an adverse impact on human health and the environment. Dual-fuel combustion with a homogeneous mixture like in a gasoline engine and compression ignition like in a diesel engine has the potential to reduce PM, nitrogen oxides (NO _x ), and other emissions from engines. The study presents an experimental investigation into a four-cylinder compression ignition engine with high and low reactivity fuel to understand soot formation in terms of PM, particle number (PN), and composition. The effect of dual fuel, injection pressure, exhaust gas recirculation (EGR), and sulfur content on soot emission is presented. The soot and NO _x emissions decrease with the increase in the gasoline percentage in the dual fuel. A reduction in soot of up to 30% is observed for a 75% gasoline content. NO _x emission is reduced by 15% for a 50% gasoline content and reduced further by 10% by increasing the gasoline content to 75%. The dual fuel with 85% gasoline has a 0.08 filter smoke number (FSN) for smoke and NO _x of 4.74 g/kWhr, significantly lower compared to conventional diesel engine operation. An increase in gasoline reduces both particle diameter and particle concentration. The PN and size move from the accumulation mode to the nuclei mode with the increase in gasoline content. The filter paper analysis shows that the hydrocarbon (HC) fraction in soot increases for higher gasoline percentages. The use of dual fuel has the potential for simultaneous reduction in soot and NO _x emissions and reduces the aftertreatment cost for a diesel engine.