Energetic Analysis of the Performances of Innovative Aftertreatment Systems

The development and the optimization of aftertreatment systems are fundamental keys to meet the more and more severe regulations concerning automotive exhaust emissions. This paper aims to analyse and compare the energetic performances of passive and active aftertreatment systems. The passive flow control represents the technical solution largely adopted in practice with unidirectional flow within the aftertreatment system. Conversely, the active flow control is based on reversed flow systems and, additionally, on the control of the exhaust gas flow path through the monolith. A single channel one-dimensional model was proposed in order to assess the heat exchange between the aftertreatment system and the exhaust gas and to compare the energetic characteristics of the two control modes. The analysis showed that the active flow control appears more suitable to maintain the initial temperature level of the monolith for a longer time after sudden variations in engine load. Furthermore, the effects of the exhaust gas temperature and unburned hydrocarbons concentration on the system performance were presented.