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A compact, knitted, crimped wiremesh mixer disposed in the exhaust system of an internal combustion engine, between the reductant injection and the urea SCR unit, increases the uniformity of the reductant in the exhaust stream by the time the stream reaches the SCR catalysis unit. Wiremesh mixer enhances thermolysis of urea into ammonia and iso-cyanic acid (HNCO). Computational Fluid Dynamics (CFD) modeling shows improved uniformity index from 0.94 to 0.99 within 35 mm travel length due to longitudinal and radial flow of the exhaust gas through the body of the wiremesh mixer. The higher thermolysis and rapid warm-up nature of the wiremesh provides enhanced ammonia production from urea thermolysis. Wiremesh physical attributes such as material composition, geometry and structure, wire diameter, mesh crimp pitch, crimp depth, crimp angle and the contour are optimized for minimum back pressure and maximum mixing efficiency.

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.

Computer aided engineering is used to design, develop, optimize and manufacture catalytic converter. Heatcad, a transient heat transfer analysis is used to simulate the temperature response in the exhaust system to locate the catalytic converter to achieve maximum performance. Heatcad analysis provides the easy way to identify thermal management issues and to design and optimize the runner lengths and material thicknesses of the manifold, and downpipes. P-Cat is used to estimate back pressure due to substrates, end cones, and inlet/outlet pipes. Catheat, a one dimentional heat transfer tool is used to identify the converter insulation to maintain the required external skin temperature. Computational Fluid Dynamics (CFD) analysis, a powerful means of simulating complex fluid flow situations in the exhaust system, is used to optimize the converter inlet and outlet cones and the downpipes to obtain uniform exhaust gas flow to achieve maximum converter performance and reduce mat erosion.

Fluid flow, temperature prediction, thermal response and light-off behavior of the catalytic converter were investigated using Computational Fluid Dynamics (CFD), combined with a conjugate heat transfer and a chemical reaction model. There are two objectives in this study: one to predict the maximum operation temperature for appropriate materials selection; and the other, to develop a numerical model which can be adjusted to reflect changes in the catalyst/washcoat formulation to accurately predict effects on the flow, temperature and light-off behavior. Temperature distributions were calculated for exhaust gas, catalyzed substrate, mounting mat and converter skin. Converter shell skin temperature was obtained for different mat materials. By changing reactant mass concentrations and noble metal loading, the converter light-off behavior, thermal response and temperature distributions were changed.

While advanced automotive system assemblies contribute greater value to automobile safety, reliability, emission/noise performance and comfort, they are also generating higher temperatures that can reduce the functionality and reliability of the system over time. Thermal management and proper insulation are extremely important and highly demanding for the functioning of BSVI and RDE vehicles. Frugal engineering is mandatory to develop heat shield in the exhaust system with minimum heat loss. Heat shield design parameters such as insulation material type, insulation material composition, insulation thickness, insulation density, air gap thickness and outer layer material are studied for their influences on skin temperature using mathematical calculation, CFD simulation and measurement. Simulation results are comparable to that of the test results within 10% deviation.

The numerical methodology is developed to estimate the backpressure value acquired from the cold flow bench into the hot flow conditions by equalizing various gas flow properties such as gas density and gas constant. The exhaust muffler geometry is adopted for virtual analysis. Computational Fluid Dynamics (CFD) modeling of the exhaust muffler in hot and cold flow conditions shows 60% of difference in back pressure values. The same muffler sample is tested in hot and cold flow test bench for back pressure on same measurement location used in CFD tool, the test result difference between these two conditions is obtained as 61%. By using derived 1D calculation, the cold flow back pressure results are extrapolated to generate hot flow back pressure values for the exhaust muffler system. These extrapolated values are then validated with the back pressure analysis results performed in both CFD and flow test bench using cold and hot flow conditions.