Experimental study of multiple injection scheduling for smoke - NOx tradeoff in a twin cylinder turbo charged CRDI engine

Abstract

Advancement in electronic fuel injection system provided the flexibility to optimize the injection parameter to control the smoke – NOx tradeoff in diesel engines. This experimental study evaluated the effect of a multiple injection strategy on emission reduction. The fuel injection pattern involves a pilot – main – post sequence with several combinations having fuel quantity and dwell period as the variables. Experiments were performed in twin cylinder turbo charged, common rail direct injection (CRDi) diesel engine controlled by an open electronic control unit (ECU). During the experiment the main injection was unaltered with an injection pressure of 700 bar and fuel injected at 6 crank angle degree (CAD) before top dead center (bTDC). For the pilot injection, the fuel quantity was varied 5, 10,15 and 20 % percentage and the dwell period between pilot and main were 12, 14 and 16 CAD respectively. The timing of post injection was 16, 18 and 20 CAD respectively after the end of main injection coupled with 0.5 and 1 mg of fuel quantity combination. The optimized injection schedule yielded 17 % reduction in smoke and 33 % reduction in NOx. HC and CO emission were reduced by 22 and 7% respectively. The study confirmed previous research finding regarding the correlation between in cylinder pressure and rate of heat release in lieu of emission formation. For the multiple injection sequence, the peak in cylinder pressure and rate of heat release reduced up to 5 and 17 % in comparison to single injection.Advancement in electronic fuel injection system provided the flexibility to optimize the injection parameter to control the smoke – NOx tradeoff in diesel engines. This experimental study evaluated the effect of a multiple injection strategy on emission reduction. The fuel injection pattern involves a pilot – main – post sequence with several combinations having fuel quantity and dwell period as the variables. Experiments were performed in twin cylinder turbo charged, common rail direct injection (CRDi) diesel engine controlled by an open electronic control unit (ECU). During the experiment the main injection was unaltered with an injection pressure of 700 bar and fuel injected at 6 crank angle degree (CAD) before top dead center (bTDC). For the pilot injection, the fuel quantity was varied 5, 10,15 and 20 % percentage and the dwell period between pilot and main were 12, 14 and 16 CAD respectively. The timing of post injection was 16, 18 and 20 CAD respectively after the end of main injection coupled with...