The Way to Achieve "CARB post 2023" Emission Legislation for Commercial Vehicles

Authors

Dipl.-Ing. R. Brück, Dipl.-Ing. O. Holz, Continental Emitec GmbH, Lohmar; Dr. A. Geisselmann, Dr.-Ing. A. Scheuer, Umicore AG & Co KG, Hanau-Wolfgang

Year

2017

Print Info

Fortschritt-Berichte VDI, Series 12, No 802

Summary

The current discussion on tightening of NO_x limits in the commercial vehicle sector in Europe as well as especially in the Unites States presents a new challenge for the engineand catalyst-manufacturer. Lowering of 90 % (down to 0,02 g/bhp-hr) requires NO_x – reduction at all engine operating conditions. Especially cold start and load points with low exhaust temperatures demand high activity of the exhaust aftertreatment system, particularly the amount and preparation of the reductant. In passenger car application well proven close coupled catalyst configuration is deemed to be a major step to reach the future limits. The use of additional heating measures seems unavoidable to ensure the perfect preparation of the reductant on the one hand side and to reach the needed conversion efficiency of the SCR catalysts on the other hand. Particularly an electrical heated catalyst with hydrolyses coating was installed just downstream of the reductant injection. An improvement of almost 60 % could be demonstrated for the NO_x values in the FTP cycle coming along with reduction of muffler size of 50 %. For this reason the considerable smaller exhaust system can be positioned closer to the engine and make use of the thermodynamical advantages of the hotter exhaust. This paper describes the development of a close coupled exhaust aftertreatment system utilizing CAD and by testing on a dynamical HD engine dyno.