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Modelling the Influence of Different Soot Types on the Radio-Frequency-Based Load Detection of Gasoline Particulate Filters
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on April 14, 2020 by SAE International in United States
Due to the harmful health effects of ultrafine particles, emission standards for gasoline engines have been tightened in recent years with regard to particle number. In order to meet the limits, gasoline particulate filter (GPF) have become necessary, especially for engines with direct injection. As for diesel applications, GPFs can be monitored via differential pressure measurement or a radio-frequency approach (RF sensor). The latter is based on the influence of the soot conductivity on the electromagnetic field. Due to large differences in soot properties and engine operating modes (e.g., the possibility of incomplete regenerations), the behavior of both sensor systems has to be investigated in detail. For this purpose, usually complex measurements on engine test benches are required. To simplify sensor development, a simulation model was created using COMSOL Multiphysics that not only allows to calculate the loading and regeneration process of GPFs under different engine operating conditions, but also to determine the impact on both sensor systems. In order to simulate the regeneration behavior of gasoline soot accurately, an oxidation model was developed using reaction parameters determined by thermogravimetric analysis. To replicate the response of the RF sensor, the soot conductivity was determined using the cavity perturbation method at temperatures typical for automotive applications. To validate the transferability of the properties from pure soot to complete filter systems, regeneration measurements were performed on GPFs loaded with synthetic soot and compared with the simulated data. Using the kinetic and electrical properties of soot samples generated by an engine test bench at various operating points, the influence of different soot types on the sensor behavior could be investigated at typical driving conditions (e.g. driving cycles or continuous loading with partial regeneration).