Effect of ambient high-temperature on real driving emission tests of a light-duty gasoline vehicle

Abstract

In real driving emission (RDE) test procedures, the extended high-temperature conditions of 30–35 °C are set to correct for the effect of ambient high-temperature on RDE tests. However, direct test data supporting or explaining the rationality of this provision remains lacking. To understand the impact of high-temperature environmental conditions on the RDE tests, ten RDE tests of a light-duty gasoline vehicle were conducted in an ambient temperature range of approximately 10–40 °C with the same driver and driving route. From the sample data of the ten RDE tests, the RDE tests were more affected by the non-temperature test conditions of trip dynamic, route topography, etc., than by the ambient temperature test conditions. The CO2, CO, NOx, and PN emissions were not sensitive to the variations in ambient temperature except for very few cases in urban CO2 and CO emissions. The ambient high-temperature conditions did not necessarily lead to severe pollutant emissions in the ten RDE tests. Extending the upper limit of the moderate temperature conditions upwards to a higher ambient temperature in the RDE test procedures should be considered.