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Optimization of Urea SCR deNOx Systems for HD Diesel Engines
ISSN: 0148-7191, e-ISSN: 2688-3627
Published March 08, 2004 by SAE International in United States
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In the past decade, SCR deNOx technology with urea injection has grown to maturity. European OEMs will apply SCR deNOx to meet future heavy-duty emissions legislation starting with EURO-4 (2005/2006). Numerous research programs in Europe and the US have shown a variety of system layouts and control strategies. The main differences are formed by:
- the engine-out NOx calibration
- the application of an NO to NO2 catalyst
- open-loop or closed-loop urea dosage control.
This paper gives an overview of possible SCR system configurations that are required for different stages of future emission legislation.
Engine-out NOx emission is strongly influenced by ambient conditions. Projections in this study show that a combination of cold climate and a wintergrade fuel is the most severe: it may lead to 30% lower engine-out NOx emission with respect to laboratory conditions. The varying engine-out NOx emission requires a safety margin in the case of an open-loop controlled system in order to avoid excessive NH3 slip.
Calculations in this paper show that Euro 4 limits can be met with open-loop controlled urea dosage; an NO to NO2 catalyst is even not required. For other future emission legislation (Euro 5, US 2007 and US 2010), it becomes difficult to safely achieve the limits with open-loop control. US 2007 and 2010 legislation require an NO to NO2 catalyst because of the low average load and consequently low exhaust gas temperatures. Engines that are developed to meet US 2010 legislation need special measures to increase the exhaust gas temperature and to reduce engine-out NOx below 2 g/kWh.
In all cases, optimal hydrolysis and mixing conditions are of major importance. High speed photography and droplet size measurements are presented as methods for characterizing and modeling aqueous urea spray patterns. The information from these measurements is used as input parameters for simulation tools. These consist of a 2D/3D CFD program for urea mixing analysis and a 1D SCR system model for development of dosage control and optimization of catalyst dimension.
Finally, simulations with the SCR system model are compared with measurements on the engine test bench.
Citationvan Helden, R., Verbeek, R., Willems, F., and van der Welle, R., "Optimization of Urea SCR deNOx Systems for HD Diesel Engines," SAE Technical Paper 2004-01-0154, 2004, https://doi.org/10.4271/2004-01-0154.
Diesel Emissions on CD-ROM from the SAE 2004 World Congress
Number: SP-1835CD; Published: 2004-03-08
Number: SP-1835CD; Published: 2004-03-08
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- Lietti, L. Nova, I. Camurri, S. Tronconi, E. Forzatti, P. Dynamics of the SCR-deNOx Reaction by the Transient-Response Method AlChE Journal 43 2559 2570 1997
- Miller, W.R. Klein, J.T. Mueller, R. Doelling, W. Zuerbig, J. The Development of Urea-SCR Technology for US Heavy Duty Trucks SAE 2000-01-0190
- Amon, B. Keefe, G. On-Road Demonstration of NO x Emission Control for Heavy-Duty Diesel Trucks using SINOx™ Urea SCR technology - Long Term Experience and Measurement Results SAE 2001-01-1931
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- Kao Minghui Moskwa, J. Turbocharged diesel engine modeling for nonlinear control and state estimation ASME J. of Dynamic Systems, Measurement and Control 117 20 30 1995
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- Bardasz, E. Mackney, D. Britton, N. Kleinscheck, G. Olofsson, K. Murray, I. Walker, A. Investigations of interactions between Lubricant-derived Species and Aftertreatment Systems on a State-of-the-Art Heavy Duty Diesel Engine JSAE 20030077, SAE 2003-01-1963
- Signer, M. Heinze, P. Mercogliano, R. Stein, H. European Programme on Emissions, Fuels and Engine Technology (EPEFE) - Heavy Duty Diesel Study SAE 961074
- Stradling, R. Gadd, P. Signer, M. Operti, C. The Influence of Fuel Properties and Injection Timing on the Exhasut Emissions and Fuel Consumption of an Iveco Heavy-Duty Diesel Engine SAE 971635
- Walker, A. The Development and On-Road Demonstration of Four-Way Emission Control Systems for HDD Applications Heavy Duty Diesel Emissions Control TopTec Symposium Sweden 2003
- Spurk, P. Pfeifer, M. Gieshoff, J. Lox, E. A Breakthrough in SCR Technology AutoTechnology 3 2002
- Song, Q. Zhu, G. Model-based Closed-loop Control of Urea SCR Exhaust Aftertreatment System for Diesel Engine SAE 2002-01-0287