Pre-Turbine-Catalysts for Passenger Car Diesel Engines (Poster Presentation)

Authors

Dipl.-Ing. G. Kellermayr, Dipl.-Ing. R. Ratzberger, Dipl.-Ing. P. Rumplmayr, Univ.-Prof. Dr. H. Eichlseder, Graz University of Technology; Dipl.-Ing. M. Wieser, AVL List GmbH, Graz; Dr. F. Jayat, Continental Emitec, GmbH, Lohmar; Dr. M. Bonifer, Heraeus Precious Metals GmbH & Co KG, Hanau

Year

2017

Print Info

Fortschritt-Berichte VDI, Series 12, No 802

Summary

The quality control of Diesel engines leads to low exhaust temperatures due to the operation at high air/fuel ratio. Furthermore, increasing engine efficiency induces declining exhaust enthalpy. Hence, heating strategies of the exhaust aftertreatment system are essential during the warm-up phase of the engine in order to guarantee a fast light-off of the catalyst and to consequentially reduce cold-start emissions. These strategies, as they are e.g. retarded combustion or throttling of the intake air, usually lead to increased fuel consumption. The positioning of exhaust aftertreatment components upstream of the turbocharger turbine to take advantage of a higher temperature level has already been discussed but is still an unconventional method. This yet competes against the close-coupled arrangement of the turbocharger targeting a fast transient response. A late boost pressure supply limits the engine torque especially at full-load acceleration. Investigations on the engine test bed and 1D gas-exchange simulation have identified the thermal inertia of the Pre-Turbine-Catalyst (PTC) as primary cause of the deterioration of boost pressure build-up. For this purpose, Diesel oxidation catalysts of different substrate sizes were installed upstream the turbine and were investigated in stationary and dynamic engine operation. Additionally, the combination of a PTC with a NO_x storage catalyst (Lean NO_x Trap LNT) and a Diesel Particulate Filter (DPF) downstream of the turbine was examined. In order to evaluate the potential advantages in the light-off behaviour of the catalytic converter without loss of engine dynamics, a combination of pre-turbine catalytic converter and electric compressor (e-booster) was additionally investigated by means of a 0D engine simulation. The validation of the simulation with e-booster will be additionally executed on the engine test bed in the future.