The design of modern aftertreatment systems to meet Real Driving Emissions (RDE)
regulations is a significant challenge faced by manufacturers today. This is
because testing vehicles under RDE conditions is both time consuming and
expensive. In this study, we quantify the effect of real driving conditions on
vehicle performance (efficiency and emissions) using a system model comprised of
vehicle and aftertreatment subsystems, built using the commercial simulation
software GT-SUITE. The developed system model will allow manufacturers to
predict vehicle performance and prospective emissions under real driving
conditions early in the development cycle and to ensure compliance with current
and future regulations. The engine used in this study is a 2.0 L turbocharged
diesel engine, while the aftertreatment system consists of a diesel oxidation
catalyst (DOC), a diesel particulate filter (DPF), and a selective catalytic
reduction (SCR).
The simulated real driving route was generated by using a new feature that uses
real-time global positioning system (GPS) data to calculate a driving route from
a defined starting point to a destination. The feature considers current traffic
conditions (traffic lights, traffic density, speed limits, etc.) and allows
different driver profiles to be simulated. In this study, a city driving route
in Los Angeles (LA) County and a highway driving route from New York City (NYC)
to LA were simulated with average traffic light durations of 15 s and 90 s. In
addition, two driver profiles were simulated for each route and traffic light
duration. The effect of all these factors on the observed engine efficiency and
emissions is quantified and discussed.
The aftertreatment system features a high-fidelity DOC model that was developed
based on synthetic gas bench (SGB) data from the literature with additional
mechanisms for sulfur poisoning and platinum oxidation. The effects of sulfur
poisoning, as well as platinum oxidation on DOC-out emissions, were also
investigated under the real driving scenarios.
