Methodology to analyse the dynamic conditions of real driving emission test and CO2 emission factors: speed binning averaged emission method

Abstract

Regulations limiting the exhaust gas emissions since the EURO I emission standards, which was put into effect in 1992, have entered a new period since 2017 and require Real Driving Emission (RDE) tests as well as laboratory tests. Laboratory tests are carried out to determine basically fuel consumption and CO2 emissions, and are aimed to determine other driving emission factors by RDE test. However, the route created to perform RDE test must meet certain boundary conditions and remain within certain limits in terms of its dynamic behaviour. According to Moving Average Window (MAW) method, these limits are determined with ±25% tolerances of CO2 emission factors obtained from the WLTC test. However, since the MAW method ignores idling conditions (vehicle speed lower than 1 km/h) and uses linear equations for the CO2 characteristic curve, it can lead to misinterpretation of RDE dynamic conditions. Therefore, in this study, a new methodology has been introduced in order to overcome these deficiencies. Two different RDE test samples were collected using Portable Emission Measurement System (PEMS) and trip dynamic conditions were examined using both MAW method suggested by the regulations and Speed Binning Averaged Emission (SBAE) method, the methodology introduced in this study. Completeness and normality values of each method are calculated to determine the conformity of the test route. As a result, while the tests are assumed complete and normal according to SBAE method, only the first test is normal, although both tests are considered complete, by means of MAW method.