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This work compares the accuracy of in-cylinder pressure and apparent heat release rate (AHRR) diagrams to the experimental data and the use of different chemical kinetics models applied to the GT-Power® software. The engine computational model is based on a naturally aspirated diesel engine with three cylinders, one of them modified to operate with hydrous ethanol with port fuel injection and HCCI combustion achieved with hot exhaust gas recirculation (EGR) of the Diesel cylinders. Operating points chosen to perform the comparison to experimental tests were 1800 rpm, 300 kPa of indicated mean effective pressure and fuels with 10% and 20% of water-in-ethanol by volume. The kinetic mechanisms for ethanol oxidation evaluated were the detailed NUI Galway and a Skeletal model based on it. With either model, cylinder pressure diagrams were not very different from the experimental values. The detailed mechanism was, on average, 9 times slower to process each case than the Skeletal mechanism.

Concerns about global warming, pollutant emissions and energy security have driven research towards cleaner and more environmentally friendly fuels. In the same way as ethanol, butanol is a promising biofuel but with different characteristics such as higher calorific value and lower latent heat of vaporization. It has similar properties to those of gasoline, which makes it a potential surrogate for this fossil fuel. Therefore, the present study proposes a comparison among four different fuels i.e. n-butanol, n-butanol and ethanol blend (B73E27), gasoline and ethanol blend (G73E27), and hydrous ethanol. A single cylinder naturally aspirated research engine with port fuel injection was employed. Engine performance was experimentally evaluated and combustion parameters were determined through reverse calculation based on acquired intake, exhaust and in-cylinder pressure on GT-Power.

Among the gases usually emitted by internal combustion engines, NOx chemical species appear as some of the causes of great environmental impact and damage to human health, which shows the relevance of its study and quantification, as well as the constant search for the reduction of these emissions. The use of biofuels such as hydrous ethanol and n-butanol has the goal of reducing CO2 emissions in comparison to fossil fuels. However, it has to be accomplished without increasing NOx emissions. Analyzing combustion of these two fuels through a two-zone model for an Otto cycle engine, this work compared quantitatively the NOx emissions with the Zeldovich reaction mechanism, which can predict the formation and consumption of these chemical species during the engine's combustion cycle, being thus known as thermal NO.

The ethanol fuel sold in Brazil, which is seen as an option that represents less polluting gases emitted into the atmosphere, goes through a period where its economic viability does not compensate its use against the alternative coming from nonrenewable sources. It is known that part of the cost associated with commercial ethanol is due to its purification through distillation, which decreases the water percentage in the final composition. Aiming to evaluate alternatives to reduce the final cost of the fuel, a comparison was made between the burning results of hydrous ethanol, with up to 5% of water by volume, and the wet ethanol, with 30% water by volume, in an Otto cycle engine, operating with a fixed speed of 1800 RPM and seeking the maximum brake torque in each test.