Technological approaches to improve the engine efficiency and to reduce pollutant emissions of automotive diesel engines.

The research work was mainly focused on the technological approach to improve engine efficiency and reduce pollutant emissions applicable to diesel engines which are very often incompatible were assessed through a set of full- scale tests on a real diesel engine in order to satisfy the new emissions limits. (1) The first strategy evaluated in this work to improve the engine efficiency was the reduction of the mechanical losses: through the incorporation of nanomaterials in the lubricant formulation. The effect of the lubricant oil additivated with MoS2 nanopowders was assessed through a set of full - scale tests on a real diesel engine – several engine points and cooling water temperatures were investigated for both a reference oil and a MoS2-additivated one. (2) Other strategy to reduce pollutant emissions included in this PhD thesis was the effects of using a 30% by volume blend of a renewable fuel, called Farnesane, and fossil diesel in a small Euro 5 displacement passenger car diesel engine. (3) And finally, the CeO2/BaO/Pt system was selected in order to perform an NO2-assisted soot oxidation, as a aftertreatment strategy to reduce pollutant emissions. The aim of such catalytic system is to couple the catalytic functionality for soot abatement during DPF regeneration, namely CeO2, and an embedded lean NOx trap (LNT) functionality given by BaO, for NOx storage, whose oxidation over Pt to form adsorbed nitrates is facilitated by the presence of CeO2 itself.