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In order to satisfy China IV emissions regulations, a unique design concept was proposed with injector closely coupled with Selective Catalytic Reduction (SCR) system outer body. The benefit of this design is significant in cost reduction and installation convenience. One paper was published to describe the vertical inlet layout [1]; this work is the second part describing applications of this concept to horizontal inlet configurations. For horizontal inlet pipe, two mixing pipe designs were proposed to avoid urea deposit and meet EU IV emission regulations. Computational Fluid Dynamics (CFD) technique was used to evaluate two design concepts; experiments were performed to validate both designs. CFD computations and experiments give the same direction on ranking of the two decomposition tubes. With the straight decomposition pipe design and unique perforated baffle design, no urea deposits were found; in addition, the emission level satisfied EU IV regulations.

In order to satisfy China IV (equivalent to EU IV) emission regulations, an unconventional design concept was proposed with injector closely coupled with SCR can body. The benefit of this design is that the urea decomposition pipe was removed or drastically shortened, resulting in much smaller packaging space and lower cost of the whole system. However, the resulting short urea mixing distance generates concerns on low urea mixing efficiency and risks of urea deposits. In particular, airless urea injectors tend to generate incomplete evaporation of urea water solution, resulting in high risks of urea deposits. New aftertreatment mixing structures need to be developed to resolve these technical challenges.

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.