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One of the alternative fuels considered for powering piston internal combustion engines is ethanol. In some countries, ethanol has been successfully used for many years as a self-contained fuel in positive-ignition engines after relatively minor technical modifications. Due, among other things, to a very low cetane number, this fuel cannot be used in pure form in diesel engines. Consideration is being given to fuels that are blends of diesel fuel with some ethanol fraction. Diesel fuel containing up to 15% (v/v) of ethanol is sometimes referred to as e-diesel or oxygenated diesel. However, it is necessary to improve the autoignition properties of such a blend. Improvement of the autoignition properties of an ethanol–diesel fuel blend (EDB) can be accomplished by introducing an additive that improves the propensity for autoignition. One such additive may be 2-ethylhexyl nitrate (2-EHN), which is commonly used to improve the autoignition properties of diesel fuels. This study determined the effect of the addition of 2-EHN (up to 10,000 ppm [m/m]) on the autoignition properties of an EDB with an ethanol fraction of 15% (v/v). The study was carried out by using a device with a constant volume combustion chamber, which additionally enabled determination of the effect of the ambient gas temperature (in the range 550–650 °C) on the period of ignition delay and the period of combustion delay, as well as the derived cetane number. The average and maximum pressure rise rates in the combustion chamber were also analysed. Studies have shown that, with an increase of the 2-EHN fraction in an EDB, the periods of ignition and combustion delay decrease, and the increase in the temperature of ambient gas into which the fuel is injected shortens these periods to a varying extent. [ABSTRACT FROM AUTHOR]

Due to increasing fuel consumption in various industries, especially in road transport, interest in increasing the market proportion of renewable fuels is growing. The raw materials for production of ethanol may include sugar beets, sugar cane, potatoes and many other plants containing starch. In some countries, ethanol has been successfully used for many years as a self-contained fuel in positive-ignition engines after subjection to relatively minor technical modifications. Due, among other things, to a very low cetane number, this fuel cannot be used in diesel engines. For this reason, increasing attention is being paid to fuels that are blends of diesel with some ethanol fraction. Diesel fuel containing up to 15% (v/v) of ethanol is sometimes referred to as e-diesel or oxygenated diesel. In this study, the autoignition properties of blends of typical diesel fuel with ethanol have been tested with ethanol contents up to 14% (v/v) and where a constant volume combustion chamber was used. The study determined the effect of gaseous medium temperature in the range 550–650 °C on the period of ignition delay and the period of combustion delay. The average and maximum rates of pressure rise in the combustion chamber were also analysed. Studies have shown that, with an increase of ethanol fraction in diesel fuel, the periods of ignition and combustion delay increase, and the increase in the temperature of the gaseous medium into which the fuel is injected shortens these periods to a varying extent. [ABSTRACT FROM AUTHOR]

• A range of 2nd generation-derived furans were tested in diesel blends in an engine. • Ignition delay decreased with greater molecular saturation and branching. • Fully aromatic furans unsuitable for combustion at this blend ratio. • Oxygenated functional groups appeared to destabilise the aromatic ring. • Addition of an oxygenated functional group enhanced soot oxidation. Screening of a variety of bioderived furanic molecules was performed in order to improve our understanding of how this class of molecules respond during compression-ignition combustion, after blending with diesel fuel. Reducing carbon emissions is possible through the use of "2nd generation" carbon neutral biofuels, the sources of which are from non-edible feedstocks, meaning that competition with food resources is negated. The tested molecules were selected for their potentially more economic and less energy intensive production routes, compared to more conventional alternative diesel fuels. These furan-based molecules were varied in their degree of molecular saturation, their branching and in the addition of an oxygenated functional group. It was found that the molecules liberated from lignocellulosic biomass need to be saturated to achieve stable combustion when blended at a volumetric ratio of 50:50 with fossil diesel. The aromatic ring of a furan molecule was postulated to be difficult to break down and increased the ignition delay substantially. This resulted in a significant increase in carbon monoxide (CO) emissions. Blending with butanol and increasing the proportion of diesel in the blend mitigated this effect, and enabled the effect on emissions of adding furan molecules into a blend to be evaluated with a wider range of candidate molecules. Biofuel combustion produced higher NO x emissions and particle number, while particle mass decreased compared to the fossil diesel. Between the molecules, an increase in the degree of saturation decreased the ignition delay, which tended to decrease the NO x emissions and increase the particle mass. Furthermore, the effect of adding alkyl chains to the ring structure tended to increase the molecules' propensity to ignite by providing more radicals during the ignition delay period; longer single chains were more effective compared to numerous shorter chains. It was also noted that the addition of an oxygenated functional group to the molecule decreased the particle mass in all cases. Carbonyl groups decreased the ignition delay period relative to the base molecule while alcohol groups increased this period; in both cases, however, NO x emissions increased. [ABSTRACT FROM AUTHOR]

Abstract: Lubrication systems of combustion engines offer a large potential for energy conservation and reduction of emissions. Different approaches include variable oil pumps to adjust oil pressure and flow rates to the engines requirements or thermal management to reduce the viscosity of the engine oil. For both of these systems the fuel conservation during physical tests is typically much smaller than the predictions through computations. The root cause of these differences between simulations and test results are analysed in this paper with specific focus on the heat transfer from the engine to the lubrication oil and the effects of water condensation in the exhaust. The analysis resulted in different waste heat recovery system configurations that are presented. Vehicle test results for one system with a gasoline engine demonstrate a fuel conservation potential of over 7% together with two digit reductions of several emission components. For another more effective but also more simple system configuration a similar improvement potential is shown. Risks and benefits of such novel waste heat recovery systems are discussed. Further benefits are the positive effects on performance, reduction of wear and the potential of extended oil change intervals. [Copyright &y& Elsevier]