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A series of theoretical analyses of pollutant formation has been undertaken on a computer program based on temperature and volume data from a two-zone internal combustion engine model. The objective was to predict the formation of nitric oxide and carbon monoxide during combustion process in an ethanol-fueled engine before the three-way catalyst operation. The predictions were based on a chemical kinetics model, which considered 12 chemical species and 22 chemical reactions. The model calculated the reaction rates from the beginning of the combustion process until chemical kinetics calculations showed no effect on the gases composition during expansion. The developed analysis tested some temperatures in order to discover until when chemical kinetics effectiveness was considerable. This analysis involved the study of NO and CO formation rates. The considered range of temperatures was between 2500 and 1500K, typical engine temperatures during combustion and expansion processes. Results showed that NO and CO formation were qualitatively coherent when compared to known formation measures by ICEs presented on literature. The studied temperatures allow the possibility of maintaining constant the concentration of some species from specific moments during expansion process, without changing significantly formation results.

Vehicle hybridization is considered a promising alternative for pollutant emission mitigation. This type of vehicle combines the use of an internal combustion engine and electrical power. One of the most common layouts is the series-parallel hybrid vehicle, which consists of using a combustion engine as the main source of power in parallel to electrical sources. Besides propelling the vehicle, the combustion engine has the task of supplying energy to the electrical system. In parallel to hybridization, other technologies such as engine downsizing via turbocharging have been adopted to increase thermal efficiency of internal combustion engines. The purpose of this work is to analyze the viability of combining aforementioned technologies. To improve energy utilization, part of the exhaust system energy is recovered from a free turbine connected to the vehicle's battery. To evaluate the proposal viability, experimental data was obtained from a turbocharged spark-ignition engine. Efficiency indexes were calculated based on exergetic analyses for the turbocompressor set and the entire engine system. Thereafter, a virtual free turbine was added, assuming that it operates exactly as the main turbine and the efficiency indexes were recalculated as absolute values of recovered energy. The free turbine recovers up to 1.2% of fuel exergy and increases power by almost 5.2% at full load conditions.

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