Model Based Methodologies Supporting Real Driving Emissions Challenges

To comply with real-driving emissions, the well-known high efficiency of the 3-way catalyst has to be guaranteed under all driving modes. At the same time, hybridization and CO2 minimization requirements increase the importance for the engine and exhaust system thermal management. In this new technological and legislative environment, the application of model-based methodologies could support the complex optimization problem of exhaust system design and control. The purpose of the present study is to present a practical simulation approach for the engine and after-treatment system, focusing on gasoline engines for start-stop and hybrid-electric vehicle applications. The methodology is supported by a complete vehicle simulation platform with main emphasis in the prediction of engine-out and tailpipe emissions via respective engine and after-treatment modeling. The TWC simulation is based on previously established and validated mathematical models of the physicochemical phenomena. On the other hand, the engineout emissions prediction is based on a semi-empirical approach with sufficient degrees of freedom to describe the effects of stoichiometry and engine thermal state on engine-out emissions. The developed model is applied for different driving cycles and the challenges of hybridization are discussed and analyzed supported by advanced thermal loss calculations in the exhaust system.