SAE International NOx Performance of an LNT+SCR System Designed to Meet EPA 2010 Emissions: Results of Engine Dynamometer Emission Tests 2008-01-2642

The paper covers the NO x performance evaluation of an LNT + SCR system designed to meet the 2010 on-highway heavy-duty (HD) US EPA emission standards. The system combines a fuel reformer catalyst (REF), lean NO x trap (LNT), diesel particulate filter (DPF), and selective catalytic reduction (SCR) in series, to reduce engine-out NO x and PM. System NO x reduction performance was verified in an engine dynamometer test cell, using a 2007 7.6L medium-duty engine. System NO x performance was characterized using fresh LNT and SCR along with hydrothermal aged LNT and fresh SCR. Test results show levels consistent with EPA 2010 limits under various test conditions. Catalysts performance was characterized at eight steady engine-operating conditions (A100, B50, B75, A75, B100, C100, C75, C50, across a 13-mode Supplemental Emission Test (SET), and an on-highway Heavy Duty Federal Test Procedure (HD-FTP). System level NO x conversion ranged from 84 to 99%, SCR contributing between 8 - 25% of total system NO x conversion. System fuel consumption ranged from 2.3 to 4.7%.