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This study analyzes the mass, number density and size of the soot formed and oxidized inside a direct injection diesel engine. The predictions were made using the modified KIVA-3V code with the Foster soot model for the different engine operating variables. The multi-step reactions in the Foster model were converted into a system of ordinary differential equations, which was solved using the VODE ODE solver. The computed soot emissions were well compared with the engine-out data obtained from experiments. The change of the soot size during the expansion stroke was investigated. The surface growth, coagulation and oxidation of soot particles continuously changed size distribution. The sizes of soot particles at EVO timing were predicted to range from 1 nm to 50 nm. Retarded SOI timing increased the portion of diffusion combustion.

Cooled exhaust gas recirculation (EGR) is widely applied in modern diesels to effectively control nitric oxides (NOx) emission. However, unfiltered high-pressure loop EGR leads to EGR cooler fouling and loss of its effectiveness. Reduced EGR cooler effectiveness often leads to increased NOx emission through increased intake charge temperature and/or reduced EGR flows. Therefore, there is a desire to avoid EGR cooler fouling and its associated problems. Filtering the EGR upstream from the EGR cooler is considered a potential solution to preserve EGR cooler effectiveness over long operating periods and simplify the control of the EGR system. The effect of EGR filter filtration efficiency on the EGR cooler effectiveness was investigated at Southwest Research Institute (SwRI). Alantum, a filter manufacturer from Korea, developed EGR filters having 50 and 70 percent filtration efficiency for this study. A 2008 calibration, V8, A350 International diesel engine was used in this work.