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Selective Catalytic Reduction (SCR) is effective over a wide temperature window to reduce NOx emissions from engine exhaust during lean operations. In this study, different supplier SCR catalysts are investigated and modeled. A global Ammonia SCR reaction mechanism has been used, and kinetic parameters for selective catalytic reduction of NOx by Ammonia were developed for both Copper (Cu)-zeolite and Iron (Fe)-zeolite SCR catalysts. The kinetic analysis was performed using a commercial one dimensional (1-D) aftertreatment code, coupled with an optimizer. The optimized kinetics have been validated extensively with laboratory reactor data for various operating conditions on three supplier catalysts - two Copper and one Iron based formulations. Both steady state and transient tests are performed and the developed SCR models are shown to agree with the experimental measurements reasonably well.

Diesel engines offer better fuel economy compared to their gasoline counterpart, but simultaneous control of NOx and particulates is very challenging. The blended 2-way SCR/DPF is recently emerging as a compact and cost-effective technology to reduce NOx and particulates from diesel exhaust using a single aftertreatment device. By coating SCR catalysts on and inside the walls of the conventional wall-flow filter, the 2-way SCR/DPF eliminates the volume and mass of the conventional SCR device. Compared with the conventional diesel aftertreatment system with a SCR and a DPF, the 2-way SCR/DPF technology offers the potential of significant cost saving and packaging flexibility. In this study, an engine dynamometer test cell was set up to repeatedly load and regenerate the SCR/DPF devices to mimic catalyst aging experienced during periodic high-temperature soot regenerations in the real world.

An integrated system model containing sub-models for a diesel engine, NOx and soot emissions, and a diesel particulate filter (DPF) has been used to simulate stead-state engine operating conditions. The simulation results have been used to investigate the effect of DPF loading and passive regeneration on engine performance and emissions. This work is the continuation of previous work done to create an overall diesel engine/exhaust system integrated model. As in the previous work, a diesel engine, exhaust system, engine soot emissions, and diesel particulate filter (DPF) sub-models have been integrated into an overall model using Matlab Simulink. For the current work new sub-models have been added for engine-out NOx emissions and an engine feedback controller. The integrated model is intended for use in simulating the interaction of the engine and exhaust aftertreatment components.

A model was developed for a lean NOx trap (LNT) used in a diesel application. The accuracy of the LNT model was validated using data from flow reactor experiments and vehicle testing. It is demonstrated that the model agrees with the experiments reasonably well on both reactor and vehicle test data. The LNT model was then applied to simulate the NOx emissions at the trap outlet over the FTP cycle, and quantitatively evaluate the effect of inlet CO concentration, inlet H2 concentration, inlet gas temperature, and trap size on NOx conversion performance of the LNT. The LNT model was also integrated with an exhaust pipe model to investigate the impact of engine exhaust configuration on NOx conversion. The integration of the LNT model with the engine exhaust model is valuable in the assessment of engine exhaust configuration and NOx trap performance.