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http://dx.doi.org/10.7467/KSAE.2012.20.1.095

The Development and Implementation of Model-based Control Algorithm of Urea-SCR Dosing System for Improving De-NOx Performance and Reducing NH3-slip  

Jeong, Soo-Jin (Green Powertrain System R&D Center, Korea Automotive Technology Institute)
Kim, Woo-Seung (Department of Mechanical Engineering, Hanyang University)
Park, Jung-Kwon (Green Powertrain System R&D Center, Korea Automotive Technology Institute)
Lee, Ho-Kil (Green Powertrain System R&D Center, Korea Automotive Technology Institute)
Oh, Se-Doo (Green Powertrain System R&D Center, Korea Automotive Technology Institute)
Publication Information
Transactions of the Korean Society of Automotive Engineers / v.20, no.1, 2012 , pp. 95-105 More about this Journal
Abstract
The selective catalytic reduction (SCR) system is a highly-effective aftertreatment device for NOx reduction of diesel engines. Generally, the ammonia ($NH_3$) was generated from reaction mechanism of SCR in the SCR system using the liquid urea as the reluctant. Therefore, the precise urea dosing control is a very important key for NOx and $NH_3$ slip reduction in the SCR system. This paper investigated NOx and $NH_3$ emission characteristics of urea-SCR dosing system based on model-based control algorithm in order to reduce NOx. In the map-based control algorithm, target amount of urea solution was determined by mass flow rate of exhaust gas obtained from engine rpm, torque and $O_2$ for feed-back control NOx concentration should be measured by NOx sensor. Moreover, this algorithm can not estimate $NH_3$ absorbed on the catalyst. Hence, the urea injection can be too rich or too lean. In this study, the model-based control algorithm was developed and evaluated on the numerical model describing physical and chemical phenomena in SCR system. One channel thermo-fluid model coupled with finely tuned chemical reaction model was applied to this control algorithm. The vehicle test was carried out by using map-based and model-based control algorithms in the NEDC mode in order to evaluate the performance of the model based control algorithm.
Keywords
SCR(Selective Catalytic Reduction); Urea; $NH_3$; NOx; NEDC(New European Driving Cycle);
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