U.S. 2007 - Which Way to Go? Possible Technical Solutions

The exhaust emissions standards for heavy-duty (HD) truck engines in the U.S. are facing a severe reduction of both PM and NO_x emission in the year 2007, making extensive exhaust aftertreatment inevitable. Although the final emission limit values for NO_x (0.20 g/bhp-hr) and NMHC (0.14 g/bhp-hr) will see a phase-in between 2007 and 2010, the PM emission limits of 0.01 g/bhp-hr will already take full effect in 2007.

Engine-out emissions in the range of EURO 5 / U.S. 2002/04 will be achievable through internal measures as described in this paper. To fulfill U.S. 2007 limits, a diesel particulate filter will be necessary. The final limits taking effect in 2010 will only be fulfilled through application of NO_x and particulate aftertreatment.

To achieve the low engine-out emission levels, this paper will focus on both internal measures (high-EGR combustion systems and partial homogenization) and external aftertreatment systems. These approaches will be assessed to determine combined solutions that reach the desired emission targets.