The potential of dimethyl carbonate (DMC) as an alternative fuel for compression ignition engines with different EGR rates

Dimethyl carbonate (DMC) has high oxygen content (53.3%) and a non-toxic preparation, which is a promising additive for diesel fuel. Exhaust gas recirculation (EGR) technology inhibits the formation of NOX. The combination of DMC with EGR is considered to be a practical means of meeting emissions regulations. In this study, a four-cylinder diesel engine was used to study the effects of DMC and EGR on engine emissions and performance. The three test fuels included a pure diesel (D100), 10% DMC and 90% diesel (DMC10), and 20% DMC and 80% diesel (DMC20). The results show that the DMC20 mixtures created a longer ignition delay, and resulted in the highest pressure and heat release rate. However, the use of DMC shortened the duration of the combustion. The brake specific fuel consumption of the DMC blends was higher than that of diesel, and the brake thermal efficiency of the DMC10 was higher than diesel at the same EGR. Through an energy balance analysis, DMC20 has a significant potential for exhaust gas energy recovery. Overall, DMC20 had the best combustion performance when it was used in combination with EGR rates of 20%-30%. When EGR = 40%, the NOX emission of DMC20 was reduced by 64.9%, and the soot emission was reduced by 80%. The nucleation mode and aggregation mode particulate matter (PM) emissions were less affected by EGR, the total PM concentration of DMC20 reduced to less than 20% of D100, and the mass concentration was reduced by approximately 70%.