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New electrical exhaust aftertreatment heating systems are in development to address the expected Euro7 regulation in Europe. These systems considerably shorten the light =-off time of the catalyst, even under extreme boundary conditions, for example start and drive away at -7°C. The pollutant limits foreseen for Europe are less severe than for example a US Tier3/Bin30 level, but the boundary conditions considered (temperature, altitude, driving patterns) are much broader than on the chassis dyno cycle. CARB has proposed within the ACCII draft further development of the LEVIII regulation to eliminate loopholes and ensure that internal combustion engines emissions remain low while transitioning the fleet to Zero emission vehicles. A proposal with similar scope from the EPA on federal level is expected. This paper shows how the Electrical Heated Catalyst (EHC) technology is developed and optimized and points out the differences between US and European requirements.

Future Diesel emission standards for passenger cars, light and medium duty vehicles, require the combination of a more efficient NOx reduction performance along with the opportunity to reduce the complexity and the package requirements to facilitate it. With the increasing availability of aqueous urea, DEF or AdBlue® at service stations, and improved package opportunities, the urea SCR technical solution has been demonstrated to be very efficient for NOx reduction; however the complexity in injecting and distributing the reductant remains a challenge to the industry. The traditional exhaust system contains Diesel Oxidation Catalysts (DOC), Diesel Particulate Filters (DPF) and Selective Catalytic Reduction (SCR), all require additional heat to facilitate each of their specific functions.

Stringent emissions standards (Euro 6 and Tier2Bin5) lead to the use of nitrogen oxides (NOx) aftertreatment. One of the most widespread technical solutions able to meet these legislations is Urea Selective Catalytic Reduction (Urea SCR). A urea aqueous solution is introduced into the exhaust system in order to reduce NOx over SCR catalyst. Before reaching the catalyst, the aqueous solution has to be transformed into ammonia. Current serial applications need long distances (≻ 400 mm) from injection point to SCR catalyst and a mixer apparatus to ensure sufficient mixing between exhaust gas and ammonia. Because of this distance, SCR catalyst is located far from the engine. The light-off of the catalyst is penalized and therefore the efficiency of the SCR system is low. The purpose of this paper is to show a compact mixing device able to ensure mixing in a short distance (~ 75 mm).

Current emission standards for diesel passenger cars in Europe and the US require the use of diesel particulate filters (DPF). For optimal engine performance the accumulated soot on the filter has to be removed periodically at elevated exhaust gas temperature of 600-650\,DC. Since many driving conditions do not allow such exhaust gas temperature additional measures have to be applied to increase the temperature in the exhaust. Post-injection of diesel fuel in the combustion chamber is the more common solution used to increase the exhaust temperature for particulate filter regeneration. Oil dilution is one of the drawbacks of regeneration by post-injection. The use of a fuel vaporizer is another option to increase the exhaust temperature by introducing fuel in vapor form into the exhaust system. The vaporizer can be located in front of the DOC/DPF either in a close coupled position to the engine or in an underfloor position.

The SCR after treatment system is already in production for passenger car engines with a single exhaust system. In this case, the exhaust system has to be designed very carefully to optimize the Ammonia distribution on the catalyst and therefore the DeNOx potential. The application to V8 engines with two turbochargers delivering the gas into two separated DOC & DPF units is an additional challenge. This paper describes the different optimization steps of such an exhaust system and the tools used during this work. After a design phase to integrate the SCR system in the exhaust geometry, a first CFD study was conducted to evaluate the performance of the basic system using one or two urea injectors. An optimization of the connection of the two tubes, directly in front of the SCR catalyst, has been designed using further CFD calculations as well as a marker gas SF6 on a cold flow bench.

In order to fulfill the more and more stringent emission levels (Euro V, SULEV…), catalytic converter light-off time has to be reduced as much as possible. Consequently, all the parts upstream of the catalytic converter have to be designed in order to minimize the gas heat loss. As a matter of fact, considering the emission performance, all components of the hot end contribute to a better after-treatment. In this study, we focus on the exhaust manifold, that has a major contribution to the thermal mass upstream of the catalyst. The study carried out aims at highlighting the impact of fabricated manifold length and thickness on emissions and engine performance. Several manifold designs, dedicated to different naturally aspirated gasoline engine applications, have been tested on a dynamic engine bench or chassis dyno. Emission results were also supported by temperature measurements.

The development of diesel powered passenger cars is driven by the enhanced emission legislation. To fulfill the future emission limits there is a need for advanced aftertreatment devices. A comprehensive study was carried out focusing on the improvement of the DOC as one part of these systems, concerning high HC/CO conversion rates, low temperature light-off behaviour and high temperature aging stability, respectively. The first part of this study was published in [1]. Further evaluations using a high temperature DPF aging were carried out for the introduced systems. Again the substrate geometry and the catalytic coating were varied. The results from engine as well as vehicle tests show advantages in a highly systematic context by changing either geometrical or chemical factors. These results enable further improvement for the design of the exhaust system to pass the demanding emission legislation for high performance diesel powered passenger cars.