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The transportation sector is responsible for 24% of CO2 global emissions and great effort has been made by the scientific community to replace the use of fossil fuels with renewables. Brazil has committed to implement all obligations provided in COP26 seeking carbon neutrality in the set of economic activities. In this regard, Brazil has agreed in reducing GHG by 50% until 2030. Flexfuel technology was introduced in the Brazilian market decreasing fuel conversion efficiency due to the use of an intermediary compression ratio value, lower in comparison with the best value for engines exclusively fueled with ethanol and higher for gasoline. According to data published by INMETRO, flexfuel engine consumption has increased around 6%. Many European countries have been pointing to the electrification of the light vehicle as a solution to mitigate GHG, which is neither best nor a feasible solution for the future of Brazilian mobility.

In 2020, 3.6 million of heavy-duty vehicles operate in Brazil transporting 1,548 billion TKU goods and 2,372 million passengers every year. 45.1 billion of liters of Diesel are consumed per year emitting 185.3 million tons of CO2 to atmosphere. Transportation is one of largest sectors of society in CO2 emissions, being responsible of 8.6% of GHG. In Brazil, heavy vehicles predominantly are powered by fossil fuels. Huge efforts have been displayed by the scientific community to mitigate GHG emissions. Brazil has signed the term of COP 26 establishing a goal to reduce GHG emissions in 50% until 2030. Heavy duty vehicles are responsible of emitting 49.9% of CO2 of the transportation sector. The emissions standards of Brazilian legislations have decreased the limits of NOx, PM, CO in 75, 94 and 63% since 2000 were PROCONVE P2 have stabilized the first emissions limits for heavy-duty vehicles.

This paper applies numerical models to simulate the Onset of Knock (OK) in a commercial automotive spark ignition engine. Results from different models were compared with different knock detection methods to verify the best agreement. Despite being widely studied and reported in the literature, avoiding knock still poses a challenge to engine efficiency improvement and it is the focus of many new technologies. Knock detection methods rely on measurements of incylinder pressure or engine vibrations to determine the onset of knock, while some 0D predictive models are deduced from experimental data and correlations involving the critical parameters related to the knock phenomenon. Although 0D predictive models are easy to apply and calculate, the initial formulation and the different experimental conditions used to create each model often result in different numerical formulations.

The Stratified Torch Ignition (STI) engine is capable of operating with lean mixture and low cyclic variability. These characteristic significantly decreases fuel consumption and emission levels. In the STI engine the combustion starts at a pre-combustion chamber where a stoichiometric mixture is ignited by an electrical spark. Pressure increase in the pre-combustion chamber push the combustion jet flames through a calibrated nozzle to be precisely targeted into the main chamber. These combustion jet flames endowed with high thermal and kinetic energy assures a fast and stable combustion of a lean mixture formed at the main chamber. A STI prototype were built and tested. The main combustion parameters were obtained from the in-cylinder pressure measured during the experiments. A combustion analysis is carried out to explain the significant improvement of the STI engine in regard to the baseline engine which was used as workhorse for the prototype engine construction.

The emission of nitric oxide (NOx) is the most difficult to limit among numerous harmful exhaust gas components. The NOX emission of internal combustion engines is mainly NO, but it will be oxidized into NO2 quickly after entering the air. NO is formed inside the combustion chamber in post-flame combustion by the oxidation of nitrogen from the air in conditions that are dependent on the chemical composition of the mixture, temperature and pressure. The correlation between NO emissions and temperature in the combustion chamber is a result of the endothermic nature of these reactions and can be described by extended Zeldovich Mechanism. The stratified torch ignition engine is able to run with lean mixture and low cyclic variability. Due to lean operation, the in-cylinder temperature of the STI engine is significantly lower than the conventional spark ignited one. This fact lead to a substantial reduction in NOx specific emission.

A global effort has been made by the scientific community to promote significant reduction in vehicle engine out-emission. To comply with this goal a stratified torch ignition (STI) engine is built from a commercial existing baseline engine. In this system, combustion starts in a pre-combustion chamber, where the pressure increase pushes the combustion jet flames through calibrated nozzles to be precisely targeted into the main chamber. These combustion jet flames are endowed with high thermal and kinetic energy, being able to generate a stable lean combustion process. The high kinetic and thermal energy of the combustion jet flame results from the load stratification. The engine out-emissions of CO, HC and CO2 of the STI engine are presented, analyzed and compared with the baseline engine. The STI engine showed a significant decrease in the specific emissions of CO and CO2.