A New Concept for Real-Time Measurement of Particulate Matter (Soot and SOF)

Measurements of soot and SOF emitting from automobile engines by conventional gravimetric method and soxhlet extraction method are difficult and time-consuming processes. The composition in the filter substrate may change during time-consuming analysis. Therefore an accurate and real time measurement method for particulate matter is the key demand for automobile industry. This paper describes a new concept for analyzing PM, which includes measurement of soot and SOF separately, as well as the total PM emission from automobile engine continuously. The concept comprises of the real-time measurement of soot emission with a diffusion charger (DC) combined with a specific dilution system. A differential flame ionization detector with separate sample line temperatures (47°C and 191°C), have been applied for the SOF measurement. The total PM is then expressed as the sum of soot and SOF mass.

It is confirmed that there are good correlations between the newly developed system and the conventional gravimetric method and soxhlet extraction method. Good correlations were also confirmed for different engines, vehicles and for different operating conditions. For different operating conditions in a same engine it was observed that the emission patterns of the soot and SOF vary with the status of engine loads and speeds during real-time emission test using the analyzer.