Exhaust Fuel Injection

Authors

Dipl.-Wirt.-Ing. Verena Huth, Avnish Dhongde, MSc., Dipl.-Ing. Daniel Klein, Dr.-Ing. Marco Günther, Prof. Dr.-Ing. Stefan Pischinger,
Institute for Combustion Engines, RWTH Aachen University, Aachen;
Dr. Takao Fukuma,
Toyota Motor Corporation, Shizuoka, Japan

Summary

In order to meet current and future legislation limits increasing effort is necessary for high efficient exhaust aftertreatment. In addition to commonly used exhaust aftertreatment systems, new technologies are entering the market. Exhaust fuel injection is a possible solution to reduce nitrogen oxides (NO_x) also at high exhaust temperatures [1], [2], [3].

For any application where fluid is injected into the exhaust, one of the big challenges is designing the mixing section upstream catalyst to ensure good evaporation and high uniformity. To support this design process 3D-CFD (Computational Fluid Dynamics) simulations are often the method of choice. A detailed comparison between simulation and measurement with exhaust fuel injection was performed in the FVV project "Exhaust Fuel Injection". Different parameters were varied and the comparison of measurement and simulation showed good correlations regarding uniformity index and peak shape for most variations. Especially simulations in operating points with comparably low exhaust temperature (340 °C - 395 °C) matched well. Also the influence of different injection pressures (5-50 bar) was modeled well. Highest deviations between simulation and measurement were found with high exhaust temperatures and low exhaust mass flow rates and in the variations with additional mixers.

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