Efeitos da adição de ozônio em parâmetros de desempenho, combustão e emissões de um motor de ignição por centelha operando com gasolina brasileira

Abstract

The increasingly strict environmental legislation requires the use of strategies and technologies to achieve higher efficiencies in internal combustion engines (ICE). Governmental programs as Rota 2030 stimulate the use of renewable fuels, reducing greenhouse gas emissions. Nowadays, direct injection (DI) and variable valve train (VVT) technologies are used in modern downsized engines to reach higher thermal efficiencies. Lean operation strategy has the potential to increase engine efficiency due to less pumping work requirement on detriment of combustion stability. Large flame development angle caused by slow flame kernel growth results in high cyclic combustion variability. The addition of ozone increases the reactivity of the mixture due to the pre-oxidation of the fuel molecules lead to a low temperature heat release, providing better ignition conditions and flame propagation to extend the lean limit operation. Thus, the focus of the present work was to explore air dilution limits of the mixture using ozone as a combustion improver at several engine relevant operating points of a turbocharged three-cylinder 1.0 L DI SI engine. The engine was fueled with Brazilian gasoline. Spark timing was adjusted to achieve MBT or limited by knock. Lambda was swept from stoichiometric to a maximum lean value considering 3.0% COV of IMEP limitation. With the addition of ozone it was possible to extend the lean limit operation up to lambda 1.7. However, it was not possible to achieve a large increase in energy efficiency due to higher pumping losses under conditions with O2 and O3 addition. Additionally, the oxygen added to the mixture caused a significant growth in NOx emissions.