Nitrogen oxides (NOx) are one of the main harmful emissions from diesel engines. Regulations on emissions are becoming more stringent; consequently, research should aim at reducing both engine-out NOx and tail-pipe NOx emissions. Exhaust gas recirculation is mainly used to reduce engine-out NOx emissions. After-treatment methods such as lean NOx trap systems and selective catalyst reduction are used to minimize tail-pipe NOx emissions. Real-time feedback control during transient conditions can further reduce these emissions and be utilized when information about real-time engine-out NOx emissions is available. It would be helpful to evaluate the proportion of NO2 in NOx emissions because the conversion efficiency of an after-treatment system is affected by temperature and the NO-to-NO2 ratio. Therefore, a semi-empirical NOx model considering NO and NO2 separately was developed for a diesel engine in this study. The NO estimation model was established based on the extended Zeldovich mechanism. The NO2 estimation model focused on chemical reactions between NO and other species and was based on formation and decomposition mechanisms. This NOx model can contribute to the cost reduction of engine systems by replacing existing NOx sensors and can also be applied to real-time feedback control strategies to minimize NOx emissions.
Prediction of NOx considering NO and NO2 for a CI engine
2022-04-01
11 pages
Article (Journal)
Electronic Resource
English
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