EastWest 2012
concentration of CO and HC emissions is typically increased. On the other hand, the NOx concentration is generally decreased. In addition, differences exist regarding the concentration and maybe the morphology and the chemical composition of the emitted particulate matter. The soot particles concentration is decreased but still this decrease is not sufficient enough to make the Diesel Particulate Filters (DPFs) unnecessary for the future applications. In contrast, the low NOx to soot ratio inhibits the NO2-assisted (indirect) soot oxidation bringing significant difficulties to the regeneration of the filter. Advanced direct soot oxidation catalysts have to be engaged. The increased HC and CO concentration necessitates the incorporation of noble-metal-based catalysts in the filter catalytic coating. In this work the development and performance assessment of a novel MultiFunctional Reactor (MFR) for the diesel engine exhaust is presented. The novelty of this system relies on two aspects: 1. A system design which exploits internal heat recovery. 2. A multifunctional catalyst able to enhance the direct soot oxidation rate (i.e. through oxygen transfer), promote CO and HC oxidation and also promote the indirect (NO2-assisted) soot oxidation. The work is presented in three parts. The first part describes the work towards the attainment of heat recovery and the advantages of the novel design with respect to the filter thermal response and thermal behavior. The second one describes the synthesis and application of the different catalytic functionalities on the filter substrate. The third one presents the results obtained form the performance assessment of a full-scale MFR prototype. This assessment was performed with respect to the filter pressure drop, filtration efficiency and regeneration efficiency under steady state and transient conventional diesel engine conditions as well as under HCCI engine operation conditions. The performance of an aged MFR was also assessed. During the MFR development, the MFR performance was benchmarked against the performance of a State-of-the-Art catalyzed wall-flow DPF (SiC, 5.66 in x 6 in, 300 cpsi, wall thickness 0.25 mm), that represents a current technology under evaluation for a light duty OEM application, hereafter referred to as SA DPF.
ADVANCED FILTER DESIGN WITH INTEGRATED HEAT RECOVERY FUNCTION The target was to recover part of the energy released during the exothermic soot oxidation reaction. Due to the exothermic soot oxidation the downstream of the
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