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The mathematical modeling and simulation of an SI engine combustion cycle has contributed for its development, leading to the improvement of the engine purpose to convert the chemical energy of a fuel into mechanical energy through the movement of a piston. The simulation of this models allows the efficiency evaluation of the fuel combustion by generating performance parameters. The Matlab® software, a high-level language and interactive environment, were used for the creation of an add-on based on graphical user interface (GUI), capable of simulating the combustion cycle of a SI engine fuelled by wet ethanol with user-supplied initial parameters.

Various studies previously conducted have estimated the net energy value for ethanol, but the variations of data and assumptions used caused the results to lack in precision. However, studies are unanimous in pointing out that the greatest fraction of the energy necessary for making ethanol is spent in water removal (distillation and dehydration), growing exponentially the smaller the amount of water in the final product. By using wet ethanol to avoid the energy cost of dehydration, the purposes of this work were to numerically evaluate the energy spent in the distillation process and compare the results with the efficiency in using wet ethanol as fuel. The simulation was modelled through Matlab® software environment, using as base a distillation column for batch process with a variable number of plates to obtain as a final product ethanol with different degrees of hydration.

Zero-dimensional zonal models are seen as interesting tools for engine simulation due to their simplicity and yet accuracy in fitting or predicting experimental data. For combustion, a common model is a dual zone model, in which two-zones, spatially homogeneous, are set during the combustion process. Such model take into account an interface of infinitesimal thickness for the separation between zones. The success of this simulation approach depends on the accuracy of the heat transfer model. These models aim to obtain the heat transfer coefficient from the combustion gases in contact with the cylinder walls. Several heat transfer correlations from the literature can be used to obtain the heat transfer coefficient.

Butanol is an important industrial chemical and a promising biofuel. However, for the butanol applications in engines, studies are not as extensive as the case of ethanol or biodiesel. Therefore, there is a lack of information regarding the thermodynamic and combustion parameters of internal combustion engines operation using butanol fuel. To evaluate the combustion calculations and the thermodynamic simulation of internal combustion engines, several references from the literature can be used to obtain the thermodynamic and combustion routines. The most complete models are based on polynomials curve fits to the thermodynamic data (specific heat, enthalpy and entropy) of the fuels. The goal of this study is to evaluate the coefficients of the thermodynamic property curves of butanol fuel, so that the fuel can be included in the routines for internal combustion engines calculations.