TESTING OF AN ALTERNATIVE METHOD OF POLLU TANT EMISSION MEASUREMENT FOR PASSENGER CARS

An on-board sampling system (mini-CVS), an alternative method for meas uring passenger car pollutant emissions to the CVS, has been tested. F irstly, the emissions of a specific vehicle were compared according to the representative driving cycles on a chassis dynamometer using a mi ni-CVS and then a CVS. Secondly, the reliability of the mini-CVS syste m has been tested through measuring pollutant emissions of three vehic les over about 20 trips, according to three different methods: on-road mini-CVS sampling, then CVS and mini-CVS sampling on a chassis dynamo meter using the same speeds. In addition, the relation between the num ber of on-road tests and the accuracy of the measurement average has b een determined. It can be noted that the measurements using a mini-CVS are reliable and close to the measurements carried out with a CVS, pr ovided that the number of rules are met. On road, only five to six tri ps are required to assess with a 10% margin, the emissions of a vehicl e for specific traffic conditions. Finally, the method has been tested during a measurement campaign (about 150 trips) in Mexico City to obt ain emission factors representing the actual use conditions of Mexican vehicles.