A modelling tool for engine and exhaust aftertreatment performance analysis in altitude operation

Abstract

Abstract New regulation standards on engine pollutant emissions are widening the engine operating conditions subjected to type approval tests as a way to prevent from the gap between regulated and real-driving emissions. In this regard, ambient temperature and driving altitude are new boundaries to be considered. Although the basis of the impact of these variables has been studied concerning the engine performance, new challenges appear to meet the emission limits and the aftertreatment conversion efficiency. In this work, a gas dynamic modelling tool is approached to explore the maximisation of the engine torque when operating at high altitude in a wide range of ambient temperatures. Particular focus is put on the modelling of the combustion, the turbocharger and the exhaust aftertreatment system. Starting from a sea-level calibration, the proposed methodology accounts for mechanical criteria as well as the impact on the engine raw emissions and exhaust flow properties to define new combustion settings for altitude operation. Next, these boundaries are applied to the exhaust aftertreatment system to analyse the impact on the catalyst conversion efficiency and the particulate filter performance concerning pressure drop and filtration efficiency.