Computer Application in Converter Development from Concept to Manufacturing 2001-28-0046

Conventional catalytic converter developments driven by trial and error attempts by experts who successfully employ heuristics (a set of empirical rules gained through time and experience) will not be able to meet the current demanding needs. The cost and time involved in testing every catalytic converter mandates new approaches aimed at improving efficiency and reducing development lead time.

Computational tools such as HeatCad, P-Cat, CatHeat, WAVE, Computational Fluid Dynamics (CFD), Finite Element Analysis (FEA) and Monte-Carlo simulation are sequentially applied to design, optimize and manufacture catalytic converter. Heatcad analysis provides the way to identify thermal management issues and to optimize runner lengths and material thickness of the manifold, and downpipes. P-Cat is used to estimate back pressure due to substrates, washcoat, end cones, and inlet/outlet pipes. CatHeat analysis is used to predict the temperature profile across the converter. CatHeat offers input for the selection of the right insulation material and mounting gap to comply with durability and external skin temperature requirements. Computational Fluid Dynamics (CFD) analysis is used to design the converter cone geometry and downpipe orientation to obtain uniform exhaust gas flow to achieve maximum converter performance and reduce mat erosion. The uniformity index, velocity index (eccentricity) and pressure drop index predicted are used to optimize the geometry and orientation of the converter components. WAVE simulation is used to predict the exhaust system back pressure from the engine headface to tail pipe and to estimate engine performance. Finite Element Analysis (FEA) is used to predict structural mechanics and structural dynamics of the full exhaust system to give insight about the thermal fatigueness of the converter assembly. Heat transfer analysis performed with thermal, mechanical and road load conditions is used to predict the static and vibrational stresses of the converter components. Monte-Carlo simulation is used to study the effect of substrate, mounting mat and converter shell dimensional tolerances on the converter manufacturing process. Improvements ranging from 28% and 64% in GBD control was achieved.