Emission Characteristics from After-Treatment System of Medium and Light Duty Engines

To meet the Japan Post New-Long-Term (Japan 2009) emissions regulation introduced in 2009, The Hydrocarbon Selective Catalytic Reduction (HC-SCR) system for the NOx emission with a diesel fuel was chosen among various deNOx after-treatment systems (the Urea-SCR, the NOx storage-Reduction Catalyst and so on). The HC-SCR was adopted, in addition to combustion modification of diesel engine (mainly cooled EGR) as the New DPR system. The New DPR system for medium and light duty vehicles was developed as a world's first technology by Hino Motors. Advantages of the New DPR are compact to easy-to-install catalyst converter and no urea solution (DEF) injection (regardless urea infrastructure) as compared the Urea-SCR system.

This study is reported to introduce the New DPR system, and to clarify the reduction effect of the Original DPR on the regulated emissions (NOx, PM, HC and CO) and emissions level of the unregulated emissions (N₂O, CH₄, HCHO, CH₃CHO, 1,3-butadiene, benzene, Benzo[a]pyrene and NH₃), based on the measurement results. It was clarified that the regulated emissions level from the New DPR vehicle were held within Japan 2009 emissions regulation. Furthermore, it was confirmed that the New DPR vehicle (Japan 2009) could reduce the NOx by 60% and PM by 20% respectively, as compared the Original DPR vehicle (Japan 2005). On the other hand, the unregulated emissions related to green house gas (GHG) were very low level or below measurable limitation, under the condition of JE05 mode, Tokyo metropolitan government modes and Highway mode. The N₂O and CH₄ emissions, converted to CO₂-equivalent amount by using Global Warming Potential (GWP) factors, are evaluated as the emission ratio to CO₂ at the JE05 mode. As a result, the emission ratios of N₂O and CH₄ at the JE05 mode were 4.1% and 0.03%, respectively. The unregulated emissions related to HC gas components and the NH₃ emission were also very low level.