This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Model Based Assessment of Real-Driving Emissions - A Variation Study on Design and Operation Parameter
ISSN: 0148-7191, e-ISSN: 2688-3627
Published January 09, 2019 by SAE International in United States
Annotation ability available
In 2017 the European authorities put into effect the first part of a new certification test procedure for Real Driving Emissions (RDE). Similar tests are planned in other regions of the world, such as the upcoming China 6a/6b standards, further tightening emission limits, and also the introduction of RDE tests. Both restrictions pose challenging engineering tasks for upcoming vehicles. RDE certification tests feature significantly more demanding engine operating conditions and thus, emit more pollutants by orders of magnitude compared to known cycles like NEDC. Here, especially the reduction of NOx is a specific technical challenge, as it needs to compromise also with reduction targets on carbon dioxide. The fulfilment of both emission limits requires a widening of the focus from an isolated engine or exhaust aftertreatment view to a system engineering view involving all hardware and software domains of the vehicle.
The investigation of RDE by means of simulation enormously increases the complexity of standard vehicle performance and fuel consumption models. The transient nature of real driving specifically requires transient models of the entire powertrain, including engine, cooling and driveline. Additionally, a comprehensive exhaust gas aftertreatment model is key. It needs to comply with the requirements of various types of catalysts and particulate filters (DOC, SCR; DPF, SDPF, LNT, …) in a highly flexible manner. Transient driving also requires appropriate controls (i.e. air path control, fuel path control, exhaust gas control) that either can be tackled by software models of the xCU or by linking the model to a hardware xCU on a Hardware in the Loop (HiL) bench. The latter approach additionally challenges the numerical solution procedure of the virtual vehicle model as hard real-time constrains need to be fulfilled.
This work presents a real-time capable vehicle modelling framework for office and HiL based simulation in the concept phase. Based on a use-case of a diesel engine powered passenger car, all essential modelling areas (engine, combustion, pollutant formation, exhaust gas aftertreatment, …) are discussed in detail and verification simulations of selected component models are presented. The base parameterization of the model including a simplifying control strategy makes it suitable for the simulation of engine outlet and tailpipe emissions in the concept phase. A variation matrix of key design and operation parameters (catalyst sizing and arrangement, i.e. injection timings, …) is defined and drive-cycle simulations are performed for a list of randomly assembled, though RDE compliant, driving maneuvers. Key performance indicators such as emissions and fuel consumption are compared in their overall number and also in their distribution over the engine operating map. The HiL compliance of the model is presented by time measurements of an open loop model on an RT node.
CitationKrammer, J. and Nahtigal, A., "Model Based Assessment of Real-Driving Emissions - A Variation Study on Design and Operation Parameter," SAE Technical Paper 2019-26-0241, 2019, https://doi.org/10.4271/2019-26-0241.
- AVL, “Users Guide AVL CRUISE M v2018,” 2018.
- Pfau, R.U. and Schaden, T., “Real-Time Simulation of Extended Vehicle Drivetrain Dynamics, Multibody Dynamics,” Computational Methods in Applied Sciences 23:195-214, 2011.
- Manheller, P., Rauner, T., Spiegel, L., Combé, T. et al., “Durchgängige Nutzung von Simulationsmodellen im Entwicklungsprozess von Hybridfahrzeugen - Von der Simulation über Optimierung an den Prüfstand,” 5. International Symposium für Entwicklungsmethodik, Wiesbaden, 2013
- Zahn, S.Isermann, R. and, “Development of a Crank Angle Based Engine Model for Realtime Simulation,” Kahrstedt, J. (Herausgeber), Engine Process Simulation and Supercharging II (Aachen, Haus der Technik, 2007), S255-S279.
- Wurzenberger, J.C., Heinzle, R., Schuemie, A., and Katrasnik, T., “Crank-Angle Resolved Real-Time Engine Simulation -Integrated Simulation Tool Chain from Office to Testbed,” SAE Technical Paper 2009-01-0589, 2009, doi:10.4271/2009-01-0589.
- D’Errico, G., Ferrari, G., Onorati, A., and Cerri, T., “Modeling the Pollutant Emissions from a S.I. Engine,” SAE Technical Paper 2002-01-0006, 2002, doi:10.4271/2002-01-0006.
- Siano, D. and Bozza, F., “Combustion Noise Prediction in a Small Diesel Engine Finalized to the Optimization of the Fuel Injection Strategy,” SAE Technical Paper 2009-01-2077, 2009, doi:10.4271/2009-01-2077.
- Sjeric, M., Kozarac, D., and Taritas, I., “Experimentally Supported Modeling of Cycle-to-Cycle Variations of SI Engine Using Cycle-Simulation Model,” SAE Technical Paper 2014-01-1069, 2014, doi:10.4271/2014-01-1069.
- Chmela, F. and Orthaber, G., “Rate of Heat Release Prediction for Direct Injection Diesel Engines Based on Purely Mixing Controlled Combustion,” SAE Technical Paper 1999-01-0186, 1999, doi:10.4271/1999-01-0186.
- Pötsch, C., “Crank-Angle Resolved Modeling of Fuel Injection and Mixing Controlled Combustion for RT Application in Steady and Transient Operation,” SAE Technical Paper 2014-01-1095, 2014, doi:10.4271/2014-01-1095.
- Merker, G P., Schwarz, C, and Teichmann, R. (Herausgeber), Grundlagen Verbrennungsmotoren, Funktionsweise, Simulation, Messtechnik (Springer, 2012).
- Katrašnik, T. and Wurzenberger, J.C., “Development of Advanced Conventional and Hybrid Powertrains by Mechanistic System Level Simulations,” Transport Research Arena - Europe 2012, TRA Conference, Athens, Greece, Apr. 23-26, 2012; Procedia: Social & Behavioral Sciences 48:3371-3388, 2012 (Athens: TRA, 2012).
- Wurzenberger, J.C., Wanker, R., and Schüssler, M., “Simulation of Exhaust Gas Aftertreatment Systems - Thermal Behavior During Different Operating Conditions,” SAE Technical Paper 2008-01-0865, 2008, doi:10.4271/2008-01-0865.