Impact of ambient temperatures on regulated emissions from diesel vehicle equipped with LNT over the world-harmonized light duty vehicle test cycle (WLTC)

Euro 6 Diesel vehicle equipped with LNT (Lean NO_x Trap) was evaluated on a chassis dynamometer test bench to verify the impact of various ambient temperatures on regulated emission characteristics under the WLTC. Regulated emissions and particle emissions were measured at various ambient temperatures over the World-harmonized light-duty vehicle test cycle (WLTC). Regulated gaseous emissions from CVS-diluted exhaust gases were measured using exhaust gas analyzer (MEXA-7200H). Especially, NO_x and exhaust gas temperature sensors were installed at the before and after the LNT + DPF position to monitor emission purification characteristics. Particle concentrations and size distributions were measured by the fast particle analyzer (DMS500) that provides the particle number over the size range between 5 – 1000 nm. With the exception of NO_x emissions, regulated gaseous emissions, PM and PN were generally lower than Euro 6 regulation without distinction of ambient temperatures. At sub-zero temperature condition, regulated emissions and particle emissions were higher than normal ambient temperature conditions. Regardless of ambient temperature conditions, LNT regeneration occurred 3 times in the entire cycle. This result and analysis are new on condition that vehicle tests on WLTC were performed with installing NO_x sensor to the after-treatment system. Consequently, this study contributes to development strategy of Euro 6 vehicle and after-treatment system under the WLTC.