Abstract

NOx Reduction system was newly developed ; The De-NOx system is composed up of an external fuel injection system, DFC(Diesel Fuel Cracking catalyst) and LNT(Lean NOx Trap). External fuel injector was used for the supply of diesel fuel into DFC and LNT. DFC converts the injected diesel fuel gas into more effective reductants such as $H_2$, CO and low chain hydrocarbon. The concentration and amount of reductant can be controlled with the control of external injection. In this paper, the NOx reduction efficiency with respect to the reductant concentration was investigated with engine bench test and vehicle test. Vehicle test was conducted against EURO 6 regulation with the NEDC mode. The conclusion is that; The De-NOx system with external injection, DFC and LNT can reduce NOx efficiently even in 7% $O_2$ concentration, so the NOx reduction is possible without engine calibration for the lean/rich control. There is an threshold level of reductant concentration for high NOx reduction and low THC slip. This value is proportional to the $O_2$ contration and gas flow rate of exhaust gas.

Keywords

• LNT;
• Diesel Fuel Cracking Catalyst;
• External injection;
• HEDC(New Europian Driving Cycle);
• Vehicle test;
• NOx reduction

• 흡장형 NOx 촉매;
• 디젤 연료 변환 촉매;
• 후분사;
• 차량시험;
• NOx 환원;