Phenomenological Modeling of Soot Process in Diesel Engine Combustion

Abstract

During the last two decades, several emission standards have been implemented all over the world defining the permissible values of the pollutants. As a result, pollution reduction has become a major problem for the researchers in the field of internal combustion engines. Although diesel engines are considered more efficient than gasoline engines for their power, better fuel economy and less CO2 emissions, but the major concern is the high emitted level of Nitrogen oxides (NOx) and particulate matter (PM). In Europe, the Euro standards are being used which set different levels of nitrous oxides (NOx) and particulate matter (PM) for the diesel engines. The Euro 6 standard allows PM levels upto 0.005g/km. For achieving this small value a lot of effort has been put up nowadays for reducing the emissions. For diesel engines, the after treatment reduction of emissions using NOx traps and selective catalytic reduction (SCR) are expensive and difficult to implement. Therefore, at source reduction techniques have been developed, the most common of which is exhaust gas recirculation (EGR). Water injection (WI), by different means i.e. either by a separate injector in the chamber, by mixing with the fuel or injecting in the manifold is also used for decreasing NOx by dropping the combustion chamber temperature. This research has been performed to model the soot process in a diesel engine. Soot is the carbon based solid element and is a major component of PM. For this purpose, a simulation model of a diesel engine is developed which leads to soot production. By changing the parameters such as speed, air to fuel ratio, injection timing etc, soot production can be predicted using this model. Moreover, a modification in the model has been made to incorporate EGR and WI in the model to see the behavior of the soot process. The simulated results are then compared with the experimental results, with and without the emission reduction techniques. The soot formation model show satisfactory agreement with the experimentally measured values which results in the validation of this model as a soot prediction tool. The modification in the model also shows good results with the measured results with EGR and WI at different loading conditions.