Steffen Tischer

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The ultimate goal in the numerical simulation of automotive catalytic converters is the prediction of exhaust gas emissions as function of time for varying inlet conditions, i.e. the simulation of a driving cycle. Such a simulation must include the calculation of the transient three-dimensional temperature-field of the monolithic solid structure of the(More)
An experimental and kinetic modeling study on the Ni-catalyzed conversion of methane under oxidative and reforming conditions is presented. The numerical model is based on a surface reaction mechanism consisting of 52 elementary-step like reactions with 14 surface and six gas-phase species. Reactions for the conversion of methane with oxygen, steam, and CO2(More)
Light-off of the partial oxidation of methane to synthesis gas on a rhodiumcoated cordierite honeycomb monolith at short contact times is studied experimentally and numerically. The objective of this investigation is a better understanding of transient processes in catalytic oxidation reactors. The numerical simulation predicts the time-dependent(More)
Numerical simulations are increasingly assisting research and development in the field of emission control of automotive vehicles. Our work focuses on the prediction of the tail-pipe emissions, based on a numerical simulation of the automotive catalytic converter. Besides the prediction of the tail-pipe emissions, an understanding of the processes occurring(More)
Water-gas-shift (WGS) and reverse water-gas-shift (RWGS) reactions are numerically investigated in a stagnation-flow on aporous Rh/Al 2 O 3 catalyst. External and internal mass transfer effects are studied using three different models for the mass transport and chemical conversion inside the porous catalyst: the dusty-gas model, a set of reaction-diffusion(More)
2-D convection-diffusion, reacting flows in a single channel of catalytic monoliths are investigated. The fluid dynamics are modelled by a steady state, boundary-layer equations, which is a large system of parabolic partial differential equations (PDEs) with nonlinear boundary conditions arising from the coupling between the gas-phase and surface processes.(More)
This paper presents a hierarchical modeling approach for Solid-Oxide Fuel Cells from elementary kinetics to stacks. On a fundamental level, we have developed an analytical model for the evaluation of volume specific three-phase boundary length (vLtpb) in composite electrodes and electrochemical kinetics expressions to account for coverage dependent(More)
for his very helpful guidance and scientific mentor. I also thank Dr. Huayang Zhu (Colorado School of Mines,Golden, USA) for his help regarding the dusty-gas model implementation. I gratefully acknowledge Dr. Canan Karakaya for her explanations on stagnation-flow reactor experiments and reaction mechanisms. I thank Julian Bär for discussions on(More)
The application of a newly developed computational tool, DETCHEM, for the transient twoand threedimensional simulations of catalytic combustion monoliths is presented. The simulation is based on the coupling of a transient 2D / 3D heat balance of the solid monolith structure with steady-state calculations of the reactive flow in a representative number of(More)