Simulation Study on the Working Process of Diesel Engine with Injection Strategy Coupled EGR

Abstract

in this paper, electronically controlled high pressure common rail diesel engine is taken as the research model, and the effect of post-injection parameters (main to post-injection angle and proportion of fuel injection), post-injection timing and exhaust-gas recirculation (EGR) on engine energy distribution and emission characteristics is mainly studied. The research shows that the adoption of smaller main to post-injection angle and larger post-injection amount is beneficial to reduce NOx emission and exhaust loss, improve efficiency; but it is not benefit to the improvement of heat transfer loss. With the delay of main injection timing, torque first rises and then falls; Exhaust loss increases obviously near top dead center (TDC), heat transfer loss decrease gradually. When the main injection timing is in a certain angle before TDC, with the increasing of the EGR rate, the torque is not significantly reduced, and the BSFC is good, while the NOx emission is greatly reduced. Therefore, reasonable timing of main injection and proper increasing of EGR rate are benefit to improving the trade-off relationship between NOx and fuel consumption. Compared with single injection, multiple injection coupled injection timing can reduce NOx emission to a certain extent.