Development of an Improved Gravimetric Method for the Mass Measurement of Diesel Exhaust Gas Particles

The Particulate Measurement Programme (PMP) works on the identification of a method to replace or complete the existing particle mass (PM) measurement method. The French PMP subgroup, composed by IFP, PSA Peugeot-Citroën, Renault and UTAC, proposes an improved gravimetric method for the measurement of emitted particles, and conducted an inter-laboratory test to evaluate its performances. The technical programme is based on tests carried out on a Euro3 Diesel passenger car (PC), tested on the New European Driving Cycle (NEDC). To achieve low particulate matter (PM) emissions, the EGR is disconnected and a paraffinic fuel is used. The regulated pollutants are also measured. It is shown that the multiple filter weighing and a 0.1 μg balance instead of a 1 μg one are not necessary, as the first weighing and the 1 μg balance performances are satisfactory for type-approval purposes. The use of one filter for the entire NEDC and the decrease of flow through the tunnel from 12 to 9 m³/min increases the collected PM mass, without influencing the measurement of regulated pollutants. The collected PM mass is around 0.34-0.5 mg with satisfactory levels of repeatability and reproducibility. These results show that the proposed gravimetric method can measure with good precision low PM emissions, at least as low as 8 mg/km, with no change on the existing facilities and without supplementary cost, investment or staff training on new instruments.