| 초록 |
The drawback of Gasoline and Diesel Direct Injection (GDI, DI Diesel) engines are increased particle number (PN) emissions compared to conventional Port Fuel Injection (PFI) engines. Therefore, Gasoline and Diesel Particulate Filter (GPF, DPF) systems are required as an established emission control technology to reduce particulate maters for several years. But the pressure drop caused by GPF and DPF is a big problem to be overcome because it results in higher CO2 emissions by back pressure. In addition, sufficient filtration efficiency for particles is needed to meet the PM and PN emission regulation. In order to decrease pressure drop, regeneration of the filter is necessary to increase the fuel efficiency. Regeneration occurs at temperatures above 500℃ by soot oxidation by O2. If the soot oxidation is an exothermic process and occurs relatively fast at high temperatures around 600℃, it is crucial to control the exhaust gas temperature and space velocity to avoid thermal runaway which degrades the filter material and cracks. Thereby 1-D and 3-D CFD simulation for predicting pressure drop and temperature distributions in the GPF and DPF is a subject of special interest for the design of particulate filters In order for the pressure drop modeling, special emphasis is given on the wall, soot permeability, filter inlet and outlet flow properties and its dependence on temperature and pressure. For regeneration modeling, the soot oxidation by O2 is modeled with kinetic parameters. Finally, optimized parameters are transferred to 3-D CFD for pressure drop and regeneration modeling. Furthermore, local hot zone formation can be monitored according to soot loading conditions. This study establishes the pressure drop and active regeneration modeling procedures and examines various parameters. Finally, a new analytical expression is determined based on experimental data of diesel.
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