F2008-06-059
Development of LNT (Lean Nox Trap) Using 2nd Injection System
To meet strict NOx emission regulations, many researchers in institutes and car makers are interested in NOx aftertreatment system and have carried out in various development programs. The development of NOx aftertreatment system is divided into two methods. First, it is selective catalytic reduction system using urea. It will be applied to heavy-duty vehicle where high efficiency of NOx reduction is required. Another method is NOx adsorber catalyst system which purifies NOx adsorbed in normal driving condition into nitrogen during rich condition. In this study, LNT system has been tested with 2nd injection system in diesel passenger car, which has Euro IV 2.0 liter engine. This LNT system consists of CPF close to engine, 2nd Injection system, and LNT catalyst in UCC position. Also it has a DFC (Diesel Fuel Cracking) catalyst between 2nd injector and LNT for increasing NOx conversion by cracking diesel fuel to H2, CO, short chain HC. With this 2nd injection system, it doesn't need any Lean/Rich operation in engine, and it has an advantage in making rich condition with well controlled injection patterns. It was confirmed that this system with LNT catalyst has good NOx conversion in NEDC mode, with fast warm-up strategy and improving 2nd injection patterns. Finally it will be possible to meet Euro VI NOx regulation with Euro IV engine and LNT system.
Session: Exhaust Gas Aftertreatment