Aftertreatment Strategy for Reducing Emissions from an Ethanol Fueled CI Engine

A nine liters ethanol-fueled CI engine was equipped with aftertreatment devices while different ratios of exhaust gas recirculation (EGR) were tested. The NO_X emissions were negatively correlated to the EGR-ratio and NO_X reductions of between 33% and 73% were obtained. Unfortunately, the decrease in NO_X was followed by increased emissions of carbon monoxide, hydrocarbons, particulate matter and higher fuel consumption. The particle number emission increased approximately 4 times and particle sizes above 200 nm became more frequent when using EGR. The remedy for these emissions was to combine an oxidation catalyst and a diesel particle filter (DPF), while keeping the EGR-ratio low to minimize fuel consumption. Equipped like this, the engine passed the Euro 5 regulation as well as the Enhanced Environmentally Friendly Vehicles standard (EEV).