CFD Analysis of a Catalytic Converter Using Supported Copper Catalyst to Reduce Particulate Matter and Achieve Limited Back Pressure in Diesel Engine Exhaust 2011-01-1245

The superior performance, higher torque and better efficiency make the diesel engines more popular in both heavy and light duty automobile applications. Comparatively, diesel engine emission contains more oxides of nitrogen (NOx) and particulate matter (PM) than gasoline engine emission. Due to lean operation, control of these emissions in diesel engine is more difficult. These diesel engine emissions affect seriously the environment and human health. The rare earth metals now used as catalyst to reduce NO _X are expensive. The scarcity and high demand of present precious catalyst materials necessitate the need for finding out the alternatives. Cu-ZSM-5 Zeolite has been proved to be one of the catalysts to detoxify gas emissions. Such catalysts however have not been commercialized due to hectic ion exchange of ZSM-5 with Cu, which involves huge volume of water. Another constraint is the transport of toxic gas emissions into the Zeolite micro pores, where the active copper sites are located. Taking into account the above said problems, in the present study, alumino-phosphate supported copper phosphate was examined for the treatment of exhaust emissions.

At present, the wall flow ceramic substrate is used as filters which are expensive and also offer more back pressure resulting in more fuel consumption. In the present study, catalytic-coated steel wire mesh materials with coarse, fine, and very fine grid sizes are used for PM filtration. The soluble organic fractions of diesel PM is oxidized by DOC system. There is always a trade-off between the filtration efficiency and the back pressure developed in the exhaust canister. Through CFD analysis, a compromise between these two parameters namely, more filtration efficiency with limited back pressure is aimed at. In CFD analysis, various models with different wire mesh grid size combinations are simulated using the appropriate boundary conditions. The main objective of this study of CFD analysis is to identify the right size of steel wire mesh grid size combinations which can offer limited back pressure and more percentage of PM reduction. Followed by CFD analysis, an experimental test on a 10 hp, twin-cylinder, four-stroke, direct-injection, vertical diesel engine was also conducted to study the DOC action of the newly-developed catalyst in reducing PM through oxidation process and the results obtained are encouraging.