It is well known the dual-fuel operation at lower loads suffers from lower thermal efficiency and higher unburned percentages of fuel. The present work includes a computational investigation to predict the effects of Exhaust Gas Recirculation (EGR) on the operation of an indirect-injection, dual-fuel (Ricardo-E6) engine by using a detailed chemical kinetic scheme and a quasi-two- zone analytical model. The comprehensive chemical kinetic scheme for methane oxidation consisting of 178 elementary reaction steps with 41 species. A quasi- two-zone analytical model is based on the effective energy releases of the pilot diesel fuel while using the detailed chemical reaction kinetic scheme for the oxidation of methane. Through the results, it was shown that, the active species such as H, O and OH produced in the high-temperature combustion process and found in the exhaust gases are play a significant role in the preignition reactions. The using of EGR shorten the ignition delay which leads to improve the combustion process and thus, the low efficiency and poor emissions at light loads can be improved significantly by using the exhaust gas recirculation (EGR). On the other hand, the exhaust emissions, particularly NOdx are improved by using exhaust gas recirculation (EGR). The use of EGR is considered to be a suitable means to improve the operation of dual-fuel engine fueled with methane. |
