Study of the effect of the engine parameters calibration to optimize the use of bio-ethanol/RME/diesel blend in a Euro5 light duty diesel engine

In the global scenario of encouraging the use of renewable sources, the bioethanol as fuel supply in the automotive sector is receiving increasing interest. In the present paper the results of a research activity aimed to study the impact of a bioethanol/biodiesel/mineral diesel blend on performance and emissions of an automotive diesel engine are reassumed. An experimental campaign has been devoted to characterize the engine fuelled by the ethanol based blend highlighting the advantages and issues related to the bioethanol use. Moreover, the effects of the most important injection settings on the engine performance have been detailed, applying a Design of Experiment (DoE) method, to identify the potentiality offered by a proper engine calibration to optimize the ethanol blend use. The tests were performed on a 2.0 L Euro5 diesel
engine, in steady-state at partial and full-load conditions, burning two fuel blends: the Rapeseed Methyl Ester (RME)/ Diesel with 10% of biodiesel by volume, and the bioethanol/RME/Diesel with 20% of bioethanol and 10% of biodiesel by volume. The results showed a strong smoke emissions reduction for bioethanol blend in all tested conditions, together with a decrease of NOx, confirming a well known trend. Nevertheless, an increment of CO and HCs emissions for bioethanol blends were found, mainly at low load conditions. This issue has been investigated performing a specific test campaign inspired to the DoE method. Such activity identified in the calibration of the pilot injection quantity and rail pressure values the most influential factors in the gaseous unburned reduction.