DYNAMIC FIELD MEASUREMENTS OF SUBMICRON PARTICLES FROM DIESEL ENGINES

The authors present new tools and a complete setup with which the submicron particles, emitted from combustion processes, can be measured and classified according to their chemical nature even in the field. Diesel engines are the predominant source of these particles in the industrialized countries. The setup comprises an exhaust conditioning part including means for precipitation of the coarse particle fraction, dilution, and removal of volatile material. The submicron particles are detected with three different sensors: one for particle number concentration (condensation particle counter, CPC), one for the particle Fuchs-surface, and one that responds specifically to the carbonaceous particles. These sensors possess a short response time so that transients such as those occurring in the free acceleration mode may be observed as well. Experiments on a conventional engine test bench demonstrate the tools. The test results are highly reassuring. Correct handling of the volatile fraction is essential to avoid severe artifacts from gas to particle reactions particularly in exhaust from engines equipped with particle traps.