Effect of EGR and Cycle to Cycle Variation on Methanol/Diesel Dual Fuel RCCI Combustion at Mid Load Operation 2019-26-0090
Fuel reactivity controlled compression ignition (RCCI) has been a proven combustion strategy for simultaneous reduction in NOx and PM emissions with lower fuel consumption. This strategy, still need more investigation to overcome its operational stability. In the present study, the effect of hot/cooled exhaust gas recirculation (EGR) and cycle to cycle variation on Methanol/Diesel dual fuel reactivity controlled compression ignition combustion was investigated on a modified 3 cylinder light duty, turbocharged, CRDI diesel engine. Dual fuel RCCI combustion of methanol/diesel was achieved by premixing methanol with intake air in the intake manifold through port fuel injection and injecting diesel directly into the cylinder by flexible common rail direct injection. Intake manifold was modified to adopt port fuel injection of methanol and Hot/Cooled EGR. Experiment was conducted at two medium loads IMEP 5.8 bar and 7.5 bar at 1500 rpm by varying EGR fraction (0-40%) and premixed mass fraction. Overall, results show that 26% cooled EGR resulted in less cycle to cycle variation, better reduction in NO, and smoke emissions with improved thermal efficiency at both loads with 76% and 81% methanol mass fraction respectively. It is also noted that, hot EGR operation resulted in more cycle to cycle variation, rate of pressure rise and higher emissions compared to cold EGR at all operating conditions. It is also observed that IMEP of 7.5 bar exhibited a lesser cycle to cycle variation and emissions compared to 5.8 bar IMEP operation.
RCCI, Hot/Cooled EGR, Cycle to Cycle Variation, Dual Fuel, Rate of Pressure Rise, COV.