Control of emission characteristics by using Selective Catalytic Reduction (SCR) in D.I. diesel engine

摘要

Emission control is one of the biggest challenge in today's automotive industry. Emission control can be achieved either by controlling combustion or by treating the exhaust gas. The latter is comparatively easier since there is less or no need to modify the engine itself. One such after treatment method is the use of catalytic converter. But, the 3-way converter is expensive due to use of both platinum and palladium/rhodium. One of the alternative is the use of selective catalytic reduction, i.e., reduction of a particular mission based on the type of the engine used. For example, the major emissions in case of CI engines are NOX and PM. This project aims at reduction of NOX using SCR and its optimization. This project presents a modelling approach to the design optimization of Selective Catalytic Reduction (SCR) systems. The present study is concerned with ammonia slip and conversion efficiency of oxides of nitrogen (NOx), which are two major issues of SCR technologies. The physical processes including urea spray atomization, droplet evaporation, urea decomposition and turbulent mixing are accounted for in the modelling method. In addition, the velocity distribution and pressure drop in the SCR converter are analyzed with the consideration of flow resistances of the catalyst substrates and perforated plates.