Development of SCR System with Optimized DEF Dosing Strategy to Meet BS-VI Emission Norms

摘要

The reduction of oxides of nitrogen (NO_x) without altering particulate maters (PM) and fuel consumption is challenging with in-cylinder emission control strategies in the diesel engines. Hence, selective catalyst reduction (SCR) aftertreatment technique is widely preferred for the reduction of diesel NO_x emissions. In this work, SCR system was developed for the 4-stroke, 6 cylinder, diesel engine and diesel exhaust fluid (DEF) dosing strategy was proposed to meet Bharat stage VI (BS-VI) emission requirements. A selection of SCR catalyst material and design of SCR and ammonia oxidation (AMO_x) catalyst were done using appropriate analysis tools. The hot world harmonized steady cycle (WHSC) and hot world harmonized transient cycle (WHTC) tests were carried out with the optimized DEF dozing strategy. About 98% NO_x reduction (DeNO_x) efficiency was achieved with an average NH_3 slip of 8.5 ppm for hot WHSC with an average ammonia to NO_x ratio (ANR) of 1.3. While for hot WHTC with an average ANR of 1.2, DeNO_x efficiency up to 96% with an average NH_3 slip of 4.5 ppm were achieved. Hence, SCR aftertreatment system with the optimized DEF dosing strategy and AMO_x catalyst helped to meet BS-VI emission norms for NO_x and average NH_3 slip.