Improvement of NOx Reduction Rate of Urea-SCR System by NH3 Adsorption Quantity Control

A urea SCR system was combined with a DPF system to reduce NOx and PM in a four liters turbocharged with intercooler diesel engine. Significant reduction in NOx was observed at low exhaust gas temperatures by increasing NH₃ adsorption quantity in the SCR catalyst. Control logic of the NH₃ adsorption quantity for transient operation was developed based on the NH₃ adsorption characteristics on the SCR catalyst. It has been shown that NOx can be reduced by 75% at the average SCR inlet gas temperature of 158 deg.C by adopting the NH₃ adsorption quantity control in the JE05 Mode.