Quantitative Flow-Reactor Study of Diesel Soot Oxidation Process

Advanced flow-reactor capabilities created at Cummins were applied to the study of the diesel particulate matter (soot) oxidation process. This approach complemented the on-engine studies with a number of important features, including accurate control of gas composition and soot layer temperature.

Using the developed methodology for quantitative soot oxidation studies in a broad range of temperatures (200-700°C), an initial set of experiments was performed to compare the behavior of the real and model soot samples under the identical conditions (10%vol. of O₂, 0-15%vol. of H₂O). It was found that presence of H₂O vapor synergistically enhances the rate of oxidation by O₂ of the diesel soot sample. However, the behavior of the model soot sample (carbon black) was virtually not affected by H₂O.

Kinetic analysis of the obtained results revealed an unusual type of behavior, with the activation energy of soot oxidation increasing in the course of the experiment. The kinetic results were shown to be experimental technique-independent. Interpretation of the observed kinetic effects requires further investigation.