Emissions and Fuel Consumption Trade-Offs of a Turbocharged Diesel Engine Equipped with Electrically Heated Catalyst

In order to meet the very stringent emissions standards, particular attention has to be provided to ensure quick catalyst light-off. One of the strategies being considered to reduce light-off time is to place an electrically heated catalyst upstream of the main catalyst. In this regard, a model for an electrically heated catalyst has been developed. The model uses a highly efficient advanced adaptive (time and space) numerical scheme including a quasi-steady assumption which states that spatial changes are much greater than the temporal ones. The model has been validated using literature data for vehicle emissions tests and catalyst bed temperatures during cold start. This methodology is then applied to an aftertreatment system model comprised of an electrically heated catalyst upstream of a DOC, DPF, and SCR in series to investigate the effect of overall aftertreatment system efficiency during a New European Drive Cycle (NEDC). Finally, the aftertreatment system model is integrated with engine and vehicle models in order to study the trade-offs of tailpipe emissions vs. fuel penalty during an NEDC.