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Great efforts have been paid to improve engine efficiency as well as to reduce the pollutant emissions. The direct injection allows to improve the engine efficiency; on the other hand, the GDI combustion produces larger particle emissions. The properties of fuels play an important role both on engine performance and pollutant emissions. In particular, great attention was paid to the octane number. Oxygenated compounds allow increasing gasoline's octane number and play an important role in PM emission reduction. In this study was analyzed the effect of fuels with different RON and with ethanol and ethers content. The analysis was performed on a small GDI engine. Two operating conditions, representative of the typical EUDC cycle, were investigated. Both the engine performance and the exhaust emissions were evaluated. The gaseous emissions and particle concentration were measured at the exhaust by means of conventional instruments.

Low and ultra low viscosity oils are one of the main solutions considered in view of the improvement of energy efficiency for better fuel economy. The recent modification of SAE J300 engine oil viscosity classification, to include engine oils with high temperature & high shear rate (HTHS) viscosity of 2.3 mPa·s for the SAE 16 grade, has opened debate on the possible real benefits that could derive, in terms of fuel economy and CO2 emission reduction, from the use of ultra low viscosity oils on engines of current technology. Two European compact cars (C-segment) of recent technology and similar characteristics were employed in our laboratories, on chassis-dyno test bed, to evaluate fuel economy with the use of oils having an HTHS viscosity decreasing from 2.9 to 2.0 mPa·s, with a −0.3 mPa·s step.

The aim of this study is to investigate how the fouling that injectors undergo after several operating hours on a vehicle can affect the injection and combustion phases. The impact of the injector fouling on the pollutant formation has been also investigated. Moreover, the effects of the injector cleaning by deposits through the top quality diesel fuel commercialized by eni that is FAME free and contains multi performance additives have been investigated. The experimentation has been carried out on transparent compression ignition engine. It is a single cylinder equipped with a Euro 5 multi-cylinder head and a second-generation common rail injection system. Three indirect-acting piezoelectric injectors have been tested. The first one has been fouled with European commercial diesel fuel through the CEC DW10 injector-coking test. The second one has been fouled in the same way and, then, it has been cleaned with eni top quality diesel fuel. This fuel has fed the third injector too.

Polyoxymethylene dimethyl ether (POMDME) is a new alternative fuel that can be produced from waste biomasses and tailored through the distribution of oligomers to fit into the distillation range of diesel fuel. Since one potential advantage of alternative fuels is that they could reduce emissions also from old in-use vehicles without waiting for their replacement, we have measured and evaluated the emission performance of neat POMDME and a blend of 10% POMDME and 90% commercial diesel fuel in an old Euro-2 diesel car over the NEDC driving cycle. As compared to the reference diesel fuel, the experimental results show a significant reduction in PM emissions already with the 10% blend, i.e., −18%, and even more pronounced with the neat POMDME, i.e., −77%. With this latter the PM emission reached below the Euro 4 limit. The composition of PM was quite different for the two extreme fuels; being mostly VOF from lube oil for the neat POMDME, while mostly soot in the case of diesel fuel.

This work regards the study of the effect of the fuel properties on the diesel engine emissions of particulate separated in soluble organic fraction (SOF) and soot. A Euro-4 engine was used operating at two engine conditions: 1500 rpm speed − 8% of maximum load and 2300 rpm − 13%. Model hydrocarbon fuels containing 100% of n-alkanes and iso-alkanes were used for studying the effect of cetane number. The effect of fuel composition on soot and SOF emissions was studied at a fixed cetane number (52) by using six fuels formulated with 90 vol% of model alkanes and iso-alkanes and 10 vol% of different components as alkylbenzenes, naphthenes (decaline), diaromatics (methylnaphthalene), fatty acid methyl esters (FAME) and highly paraffinic refinery streams (Fischer-Tropsch GtL and high-pressure Hydro cracking).