Advanced Mass Emission Measurement Systems for Low Emission Vehicles 2001-26-0008
Developments of the low emission vehicles (LEV) require the mass emission measurement technologies to be highly accurate. The present paper first reviews optimization of constant volume sampling (CVS) system that has been commonly used for emission measurements. The evaluation method to minimize CVS dilution rate while preventing water condensation and typical ideas for reducing HC contamination due to absorption and out-gassing have been described. Dilution factor that is needed for mass calculation in CVS system could also cause measurement error, and dilution air refinement is discussed as possible solution of this issue. Bag mini-diluter technique is also described as a promising alternative to the LEVs measurement.