Method of Calculating Emission Factors from Volume Concentration Data Acquired by Portable Emission Tests

Portable emission measurement tests get reliable data in comparison with chassis dynamometer tests. In portable emission tests, volume concentration and mass flow of exhaust gas measured second by second. This two series of data may be measured in one point of exhaust path from engine to tailpipe so mass flow correspond to volume concentration in each moment. If they measure in different points, data should be synchronize. Same trend of NOx and Manifold absolute pressure(MAP) is used to syncing data. Unsynchronized data cause up to 30% error of final emission factors. Each vehicle is tested in different driving conditions, different road and manner, like uphill road or highly congested trafficto determine the real emission produced.