Optimization Strategies to Enhance System Performance with Aged LNT on SUV

Diesel oxidation catalysts (DOC) combined with NOx adsorbers and passive selective catalytic reduction (SCR) systems have demonstrated effectiveness in achieving high conversion efficiencies for CO, HC, and NOx emissions. This integrated exhaust after-treatment system has shown its efficiency in meeting the demanding BS6 Real Driving Emissions (RDE) standards. However, the assessment of emissions at the end of the system's life reveals a decrease in the conversion efficiency of aged exhaust systems, particularly affecting NOx, HC and CO emissions. Factors such as thermal aging and catalyst poisoning are identified as key contributors to the degradation of the after-treatment performance. This paper elucidates correlation methodologies applied to aged Lean NOx Trap (LNT) exhaust after-treatment systems. These methodologies aid in understanding the aging behavior of LNT samples and devising strategies to enhance the emissions performance aged samples during the end-of-life tests. A dual approach involving hardware and software optimization was implemented to achieve the targeted emissions for light-duty applications. The process involved selecting vehicle load points and conducting calibration optimization with optimized engine hardware on an engine test bench. Analysis of aged samples using Scanning Electron Microscopy (SEM) revealed shifts in light-off temperature and reduced storage efficiency due to aging. The combination of aging and diminished storage efficiency led to higher emissions from aged samples compared to well-preserved samples. Through a structured approach, optimization of combustion parameters was performed, along with necessary attribute balancing, to enhance light-off temperature and storage capacity. This optimization effort resulted in achieving emissions within the targets.