NO{sub}x Performance of an LNT+SCR System Designed to Meet EPA 2010 Emissions: Results of Engine Dynamometer Emission Tests

摘要

The paper covers the NO{sub}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{sub}x trap (LNT), diesel particulate filter (DPF), and selective catalytic reduction (SCR) in series, to reduce engine-out NO{sub}x and PM. System NO{sub}x reduction performance was verified in an engine dynamometer test cell, using a 2007 7.6L medium-duty engine. System NO{sub}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{sub}x conversion ranged from 84 to 99%, SCR contributing between 8 - 25% of total system NO{sub}x conversion. System fuel consumption ranged from 2.3 to 4.7%.