Research on RDE performance for in-use vehicles especially at high altitude conditions in China

Abstract

The real driving emissions (RDE) of an in-use gasoline an in use diesel light-duty (LD) vehicle , both are SUV type, are studied based on portable emission measurement system (PEMS). The gasoline vehicle complying with emission standard of China 6 with a mileage of about 50000 km, and the diesel vehicle in this study is complying with emission standard of China 5 with a mileage of about 130000 km for there are hardly any China 6 diesel vehicles in-use in major city. Special attentions are paid on their emission behaviors at high altitude conditions (1300 to 3000 m above sea level). It is observed that the RDE test approach is still feasible for revealing in-use real driving emissions at extremely high altitudes (>1300 m, which is beyond the upper limit of extended altitude conditions according to the Euro 6 regulation). The results reveals that for in-use China 6 gasoline vehicle, the efficient three way catalyst (TWC) is capable of handling NOx, CO emission sufficiently, accompany with port fuel injection that guarantees the RDE test results (NOx, PN, CO) fulfill the China 6 emissions standards (which are 35 mg/km, 6E11 #/km and 500 mg/km respectively). And for China 5 in-use diesel vehicle, EGR as the only NOx control means is not sufficient which brings extremely high real driving NOx emission, with the maximum value exceeds about 3.7 and 23.2 times of the China 5 and China 6 NOx emission limits, but on the other hand, the PN emission is only about 1% of the China 6 PN standard value for the usage of DPF.