Development of models to study the emissions, flow, and kinetic characteristics from diesel oxidation catalysts and particulate filters.

摘要

Models were developed to predict the emissions, flow, and kinetic characteristics from diesel oxidation catalysts and particulate filters used for diesel engine emissions control. Extensive experimental data was collected, and compared against both models with good agreement found in most cases. Parametric studies were performed to determine the effects on thermal and NO2-assisted oxidation due to variations in the engine operating conditions (exhaust gas temperatures, volumetric flow rates. O2 and NO2 concentrations). Heat generation phenomena inside a porous filter wall, was also studied to model the effect of microwave irradiation on the regeneration characteristics in a diesel particulate filter.; A one-dimensional model simulating the oxidation of CO, HC, and NO was developed to predict the gaseous emissions downstream of a diesel oxidation catalyst (DOC). The model is based on the conservation of mass, species, and energy inside the DOC. Steady-state experiments covering a wide range of operating conditions (exhaust temperatures, flow rates and gaseous emissions) were performed, and the data were used to calibrate the model. NO conversion efficiencies of 50% and higher were obtained at temperatures between 280°C and 370°C. CO conversion efficiencies of 85% and higher were found at every steady state condition above 200°C. HC conversion efficiencies of 75% and higher were found at every steady state condition above 200°C. The model agrees well with the experimental results at temperatures from 200°C to 500°C, and volumetric flow rates from 8--42 actual m3/min. The estimated activation energies and pre-exponential factors obtained from the model calibration are in good agreement with values reported in the literature. An analytic pressure drop model was used to estimate the pressure drop across the DOC channels, and agreement within 8% of the experimental data was obtained.; A one-dimensional model simulating the filtration and regeneration behavior in a diesel particulate filter (DPF) was developed. The model predicts the particulate mass evolution (deposition and oxidation) in a diesel particulate filter (DPF) during simultaneous loading, and during thermal and NO2 -assisted regeneration conditions. (Abstract shortened by UMI.)