Development of an Integrated Box SCR System for China IV On-Highway Applications 2014-01-1539

To satisfy China IV emissions regulations, diesel truck manufacturers are striving to meet increasingly stringent Oxides of Nitrogen (NOx) reduction standards. Heavy duty truck manufacturers demand compact urea SCR NOx abatement designs, which integrate injectors, NOx sensors and necessary components on SCR can in order to save packaging space and system cost. To achieve this goal, aftertreatment systems need to be engineered to achieve high conversion efficiencies, low back pressure, no urea deposit risks and good mechanical durability. Initially, a baseline Euro IV Urea SCR system is evaluated because of concerns on severe deposit formation. Systematic enhancements of the design have been performed to enable it to meet multiple performance targets, including emission reduction efficiency and low urea deposit risks via improved reagent mixing, evaporation, and distribution. Acoustic performance has been improved from the baseline system as well.

The optimized system improved ammonia uniformity, eliminated urea deposits, improved NOx conversion efficiency while satisfying existing EU III installation packing space. This development demonstrates that good system performance can be achieved despite the challenges of meeting multifaceted and often-conflicting performance targets. System perspectives combined with assessment and understanding of unique components is critical to achieving aggressive performance targets while reducing development time for urea SCR systems.