A Study of LNT Urea SCR on DPF System to Meet the Stringent Exhaust Emission Regulation

摘要

In diesel engine development, the new technology is coming out to meet the stringent exhaust emission regulation. The regulation demands more eco-friendly vehicles. Euro6c demands to meet not only WLTP mode, but also RDE(Real Driving Emission). In order to satisfy RDE mode, the new technology to reduce emissions should cover all operating areas including High Load & High Speed. It is a big challenge to reduce NO_x on the RDE mode and a lot of DeNO_x technologies are being developed. So the new DeNO_x technology is needed to cover widened operating area and strict acceleration/deacceleration. The existing LNT(Lean NO_x Trap) and Urea SCR(Selective Catalytic Reduction) is necessary to meet the typical NEDC or WLTP, but the RDE mode demands the powerful DeNO_x technology. Therefore, the LNT & Urea SCR on DPF was developed through this study. This complex new technology consists of new catalysts (to reduce emissions), insulation(to improve fuel economy, and catalytic performance), and logical controller(to control DeNO_x and DePM strategy). This new technology is to improve the weak DeNO_x performance and fuel penalty of LNT, and the fast heat-up issue of Urea SCR system. As this technology gathers the strong points of LNT and the Urea SCR system, it is able to meet the strengthened exhaust emission regulation. This study is the result to meet RDE mode and to make sure of fuel economy.