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The new trends of the automotive market require the development of a new concept of engines using different types of fuel, mainly those resulting from alternative sources of energy. For this purpose those multi-fuel engines must function with higher energy efficiency therefore allowing for lower fuel consumption and a drastic reduction of exhaust emission. The multi-fuel engines available in the market display only one volumetric compression ratio, which leaves ample room for the development of a better level of fuel energy use. To achieve so, such an engine must count on a variable volumetric compression ratio, which, despite being technically possible, is not economically viable for a low cost product. The present project intends to create a system capable of achieving the best performance for all types of fuel through the variation of the boost pressure, viable for a low cost product, without changing its volumetric compression ratio.

Gasoline is a complex mixture, composed of hundreds of different hydrocarbons. Surrogate fuels decrease the complexity of gasoline and are being used to improve the understanding of internal combustion engines (ICEs) fundamental processes. Computational tools are largely used in ICE development and performance optimization using simple fuels, because it is still not possible to completely model a commercial gasoline. The kinetics and interactions among all the chemical constituents are not yet fully understood, and the computational cost is also prohibitive. There is a need to find suitable surrogate fuels, which can reproduce commercial fuels performance and emissions behavior, in order to develop improved models for fuel combustion in practical devices, such as homogeneous charge compression ignition (HCCI) and spark ignition (SI) engines. Representative surrogate fuels can also be used in fuel development processes.

This work shows procedures for analyzing sprays produced by a direct injection injector. The parameters studied were tip penetration, spray pattern, cone angles and velocity profiles. Two different experimental procedures were applied. The first one to get knowledge of the initial stage of injection consisted in recording images in 4000 Hz. With the data obtained, the penetrations and penetration rates were evaluated. The second experimental procedure consisted of using the Particle Image Velocimetry technique to get images and velocity data for getting knowledge of spray pattern, external and internal cone angle and velocity profiles of the spray fully developed. Gasoline and ethanol were the two fluids tested on the experiments. The results showed larger cone angles for gasoline, linear decreasing behavior for velocities on the linear velocity profiles and a transient stage for the magnitude of the velocities in the initial stage of injection.

Nowadays computer simulation is an important tool to support new internal combustion engine projects, but still further studies are necessary for its use in fuel development. In order to study the influence of fuel properties on engine combustion and emission performance, a computer model was designed based on a Flex-Fuel engine geometric data. Model was validated with experimental tests done on an engine dynamometer. A simulation software was used to simulate the experimental conditions, by using Wiebe two zone combustion and Woschni heat transfer models. In-cylinder maximum pressure, IMEP and emission data were calculated for different gasoline-hydrous ethanol blends at 3875 rpm, 60 Nm and 105 Nm. Total hydrocarbons concentration was simulated comparing the experimental data of hydrocarbons added with unburned ethanol emission measured with a FTIR analyzer.

This work presents an experimental procedure to find the best operating point for a spark ignition engine controlled by a general Engine Management System. The ECU control allows changing the ignition and fuel injection timing as a function of load and rotational speed, beyond configuring the whole system according to the sensors and actuators types. The ignition dwell time and the best moment to start the injection fuel can be controlled accurately by this system. In addition, this electronic system allows adjustments in real time with engine installed onto a dynamometric test stand. This work describes the experimental apparatus, sensors characteristics used and also the methodology to accomplish the adjustments in the ECU maps, seeking to obtain the best performance. Comparison performance data for the standard engine and the proposed configuration are presented here, showing a 50% gain for a spark ignition engine of 1300 cm3, four cylinders in line, and 16 valves.

The pollutants emitted by fuel burn in an internal combustion engine are harmful to humankind health. One of undesirable pollutants are the nitrogen oxides (NOx), witch in the presence of sunlight is responsible by photochemical mist, forming products that irritates eyes, respiratory system and may damage plants. The present article aims to present the theoretical potential reduction in volumetric emissions of nitrogen oxides (NOx) in an internal combustion engine operating with the torch ignition system and homogeneous charge. Therefore, a calculation methodology based in measured pressures and determined temperatures were implemented to check the potential reduction in these pollutant emissions. The presented methodology used to estimate the NOx formation is based in NO formation model presented by [1].