Chemical kinetic mechanisms for HCCI combustion of wet ethanol with exhaust gas recirculation

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. The quality of data obtained with the Skeletal mechanism and its lower computational cost makes it a good solution for a quick analysis. However, when greater reliability is required, it is recommended to use the detailed NUI Galway kinetic mechanism, since it provides a better fit to the experimental data, with a more complete analysis of the chemical species involved in ethanol oxidation.