Recently, a potentiality of Dedicated EGR (D-EGR) concept SI engine has been studied. This concept engine had four cylinders and operated with exhaust gas supplied from the single cylinder to the intake manifold. Compared with conventional SI engines, it was able to increase thermal efficiency and decrease CO, HC, and NO x emission by the high D-EGR ratio 0.25. In this study, numerical analysis of a SI engine with D-EGR system with various D-EGR ratios was conducted for detailed understanding the potentiality of this concept in terms of thermal efficiency and NO x emission. #1 cylinder of assumed engine was used as D-EGR cylinder that equivalence ratio varied from 0.6 to 3.4. Entire exhaust gas from #1 cylinder was recirculated to the other cylinders. The other cylinders run with this exhaust gas and new premixed air and fuel with various equivalence ratios from 0.6-1.0. To study the effect of D-EGR ratio, the number of engine cylinders was considered from 3 to 6, same meaning with D-EGR ratio 0.5-0.2. A Laminar burning velocity and a flame temperature were considered to analyze thermal efficiency and NO x emission. The results show that D-EGR system is able to make a similar level of thermal efficiency to that of conventional SI engines. NO x emission were reduced by decreasing flame temperature while the laminar burning velocity was increased without flame temperature rising due to the influence of H 2 and CO that were included in EGR gas as intermediates.
| SAE International | |
|---|---|
| Product Category | Standards and Technical Documents |
| Product Number | 2014-32-0108 |
| Product Name | A Potentiality of Dedicated EGR in SI Engines Fueled by Natural Gas for Improving Thermal Efficiency and Reducing NO x Emission |
