Proceedings of Real Driving Emission (RDE) Measurement in China

Light-duty China-6, which is among the most stringent vehicle exhaust emission standards globally, mandates the monitoring and reporting of real driving emissions (RDE) from July, 2023. In the process of regulation promulgation and verification, more than 300 RDE tests have been performed on over 50 China-5 and China-6 certified models. This technical paper endeavors to summarize the experience of RDE practice in China, and discuss the impacts of some boundary conditions (including vehicle dynamic parameters, data processing methods, hybrid propulsion and testing altitude) on the result of RDE measurement. In general, gasoline passenger cars confront few challenges to meet the upcoming RDE NO_x requirement, but some China-5 certified samples, even powered by naturally-aspirated engines may have PN issues. PN emissions from some GDI-hybrid powertrain systems also need further reduction to meet China-6 RDE requirements. Vehicle dynamic parameters, both v.a_pos-[95] and RPA, have been confirmed to have strong impacts on RDE NO_x and PN emissions. Data processing methods, namely moving average windows (MAW) and power-binning (BIN), output quite similar emission factors if engine-stop, warm-up and idle are excluded from the calculation. Testing altitude up to 2400 m shows evident influence on RDE measurement, however, no clear correlation between altitude and RDE emissions can be concluded so far.