Pollutant emissions from engine starting with ethanol and butanol diesel blends

The starting is a special transient process of engine operation, which is included in the New European Driving Cycle of light duty vehicles (NEDC). This is a critical operation mode of diesel engines with respect to pollutant emissions and to stability of the combustion process. In this work, a turbocharged, direct injection (DI), diesel engine equipped with common rail injection system and EGR strategy was tested during the starting. The engine was tested at relatively cold and warm start. Pollutant emissions (HC, NOx, smoke opacity and particle size distributions), in-cylinder pressure and operating parameters such as rotation speed, relative fuel–air ratio and EGR valve position were registered during the tests. The engine was fueled with a pure low sulfur diesel fuel, and blended with ethanol and butanol. Fuel blends were prepared with the same oxygen content (~ 3.3% in mass). The results show that alcohol diesel blends lead to a positive effect on the reduction in the smoke opacity and particle concentration during warm engine start with similar nitrogen oxide (NOx) emissions. At cold start, blends tested produced combustion instabilities. This fact, jointly with inefficient operation of the diesel oxidation catalyst, produced an increase of all regulated pollutant emissions.