Transient emission characteristics of a heavy-duty natural gas engine at stoichiometric operation with EGR and TWC

摘要: Abstract The recent issued emission regulations have more stringent standards for the transient emissions of natural gas engines. When equipped with cooled exhaust recirculation (EGR) and three way catalyst (TWC), engines operating at stoichiometric conditions are capable achieving extremely low emissions. In this paper, characteristics a heavy-duty engine operation EGR TWC experimentally studied based on world harmonized cycle (WHTC). results show that both raw carbon monoxide (CO) total hydrocarbon (THC) higher in hot start test while NOx cold test. measurements conducted after TWC, all these Among sub-cycles WHTC, urban sub-cycle plays most important role except (ATWC) CO test, where motorway takes up highest percentage. summary, CO, nitrogen oxide (NOx) as well non-methane (NMHC) can meet requirements Euro VI standards, whereas CH 4 than corresponding standard, suggesting improvements performance essential.