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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.

Exhaust gases of diesel vehicles are considered as a major reason of city air pollutions. The DOC(Diesel Oxidation Catalyst) and DPF(Diesel Particulate Filter) have been used to reduce the emissions of diesel vehicles. The DOC can oxides HC, CO and SOF(Soluble Organic Fraction) in the PM emissions, and the DPFs can filter the most of solid PM, such as carbon particles. As the DPFs, wall flow type ceramic honeycomb filters have been commonly used and now being still advanced. However, the cost and durability of the currently used DPFs are not perfect yet. Metal foam is the one of promising materials for the DPFs due to its cost effectiveness, good thermal conductivity and high mechanical strength. The metal foam can be produced with various pore sizes and strut thickness and finally can be coated with catalytic wash-coats with low cost.