AFTERTREATMENT SOLUTIONS TO ADRESS RDE CHALLENGES FUTURE REGULATIONS

摘要

Future emission standards for passenger cars, light and medium duty vehicles, require the combination of a more efficient NO_x reduction performance along with the opportunity to reduce the complexity and the package requirements. Application of Real Driving Emissions (RDE) testing, starting in Europe in 2017, will require uniform system efficiency on all operating points. Recent activities on catalytic product allows for the SCR active compounds to move from the ceramic substrate located in the underbody to the DPF substrate already located in close coupled position to achieve the benefit of the highest temperature. This newly developed SCR coated DPF has massively improved the potential of NOX reduction. As already published in several technical papers it is crucial to inject Adblue/DEF with very high mixing performance level. The benefit of using the SCR coated DPF in combination with a high performance compact mixer has been demonstrated, however new vehicle platform development increase the challenge for exhaust system packaging constraints. The purpose of this paper is to show different exhaust design architecture incorporating a dedicated compact mixer matching compactness, weight and mixing performance. Each system require a specific flow management in order to get high mixing performance and related high NO_x reduction potential. High mixing performance is managed using dedicated mixer design where the cavity behavior is improved using enhanced CFD simulation. At the same time, this performance has to be maintained for all operating points of the engine, even at high speed/high load, in order to address Real Driving Emissions constraints. The paper shows the different products, the system integration and the criteria used to select the design depending on the vehicle application & packaging constraints, under the light of the latest emissions regulations and targets.