Accuracy of exhaust emission factor measurements on chassis dynamometer
The influence of 20 parameters on the measurement of light-vehicle emission factors on chassis dynamometer based on driving patterns, vehicle-related parameters, vehicle sampling, and laboratory-related parameters, was studied. The results were based on literature synthesis, ≈ 2700 specific tests with 183 vehicles, and the reprocessing of > 900 tests. Parameters that had a qualitative or quantitative influence on the emission measurements had a statistically significant influence. No statistically significant influence on emission measurement was found for some vehicle- and laboratory-related parameters. The influence of four parameters could be quantified, and quantitative correction factors were derived from the test data and were available to standardize emission measurements for the gearshift strategy, vehicle mileage, ambient air temperature, and ambient air humidity parameters. The mileage had no influence on the CO2 emission nor on the emissions of diesel vehicles, but increased CO, hydrocarbon, and NOx emissions of petrol cars. The hot emissions decreased with increasing temperature for petrol cars, but mainly for diesel ones. The influence of the ambient humidity existed only for NOx and for some vehicle classes. The best accuracy was encountered for CO2, for which the average coefficient of variation was around 5%. Diesel and petrol fuels strongly influenced the emissions, except for CO2.
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Journal of the Air and Waste Management Association, 59 (6), 695-703