Abstract: In order to reduce the atmospheric pollution emitted by automobiles, control devices are being incorporated in the vehicles in many countries. This has resulted in a reduced vehicle mileage to the extent of about fifteen percent. With-out the introduction of new technology, any further reduction in emission levels would be expected to extract payment in the form of further fuel economy losses. It is, therefore, worthwhile to look into the suitability of “clean ” burning fuels for use in internal combustion engines and assess their potential for reducing engine exhaust emissions. So the investigation of alternative fuels becomes very necessary. In this work three types of fuels are investigated: Alcoholic fuels, gaseous fuels and liquid fuels. Their properties were inserted in a computer program which was specially designed to calculate the performance of a spark ignition engine over wide range of operating conditions (design and off-design). The design operating variable namely compression ratio, advance angle, engine speed and spark advance were chosen for each fuel based on the physi-cal and chemical properties and the resulting fuel-engine interactions such as mixing, flammability and knock. The result-ing performance includes power, specific fuel consumption and thermal efficiency. Their variation with equivalence ratio, engine speed and spark advance was calculated and plotted in the figures and briefly mentioned in the conclusions. The engine variables including temperature, pressure and volume were calculated at different points of the cycle. Hence the P-V and the P-rc diagrams were drawn for the different alternative fuels. These diagrams are considered unique con-tribution to the characterization of alternative fuels.

Bioethanol is very similar to gasoline in many aspects and can be used in internal combustion engines without any changes in their structure. It has advantage that is produced from biomass and can be delivered to users by the same infrastructures. The paper present results of the experimental investigations of an A15MF supercharged engine fuelled with E20 gasoline-ethanol blend. Using this fuel an increase of the engine power was obtained comparative with gasoline at the same air fuel ratio. Also, it was obtained a decrease of the brake specific fuel consumption and a decrease of CO and HC emissions level. Keywords: gasoline, ethanol, supercharged, emissions, performances Currently, there is a worldwide growing interest, regarding the use of alternative fuels in spark ignition engines in order to reduce pollutant emissions, consumption of petroleum fuels and to increase the energy performance of engines Biofuels such as ethanol, biodiesel and biohydrogen are the main alternative fuels of the future Bioresources raw materials used to ethanol manufacture were diverse: biomass energy production plants, agroindustrial residues, wood residues from forest materials The researches carried out on alternative fuels have led to the use of ethanol as automotive fuel, especially when mixed with gasoline, due to its attractive properties. Therefore, appeared increasingly more studies based on experimental investigations or numerical modeling For example, M. Gogos et al. In another study, it was investigated the effect of using gasoline-ethanol blends on spark ignition engine performance and exhaust emission on a four cylinder SI engine (type Toyota, Tercel-3A) in four strokes The researchers studied the experimental investigation of the engine performance and pollutant emission of a commercial S.I. engine using ethanol-gasoline blended fuels with various blended rates (0, 5, 10, 20, 30%) [15]. Results showed that with increasing the ethanol content, the torque output and fuel consumption of the engine slightly increase while CO and HC emissions decrease dramatically as a result of the leaning effect caused by the ethanol addition. CO 2 emission increases because of the improved combustion and NO X emission depends on the engine operating condition rather than the ethanol content. It was also compared the performance and emissions from an engine 1.0 liter, eight-valve, in four-stroke fuelled by E22 (78% gasoline-22% ethanol) blend Paper objectives To obtain better performance in terms of energetic and economic, the A15MF engine has been supercharged by using a variable geometry turbine, aiming at obtaining a similar power of the engine with normal intake but at lower engine speeds and partial loads, based on downspeeding concept. Furthermore, supplying gasoline-ethanol blend of supercharged engine expects to achieve the desired goals. Properties Comparative to gasoline, ethanol contains more oxygen in its chemical composition Ethanol flammability range is much wider for air-ethanol mixtures comparative to gasoline (0, 3...1, 56 versus 0, 4...1, 4) providing engine run stability in the area of lean mixtures Ethanol has a higher octane rating (RON=106) than gasoline and because of its antiknock properties, engines with a higher compression ratio, and subsequently more power, can be designed The heat of vaporization of ethanol is 854 kJ/kg, higher than the value of 290-335 kJ/kg of the gasoline. This property can

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