Dual fuel diesel combustion with an E85 ethanol/gasoline blend

In this experimental study, the ethanol/gasoline blend E85 was used as the primary fuel in a dual-fuel combustion concept. The E85 blend was injected at low pressure into the intake manifold and the mixture was ignited via a diesel fuel injection near top dead centre. The research engine was based on a heavy-duty diesel engine equipped with a common-rail injection system. Only the duration of the diesel injection was modified in the diesel injection system during the tests - the other diesel injection parameters were not changed. The goal was to study the possibilities of using the waste material-based E85 ethanol blend on dual-fuel concept as a promising future bio-fuel option. The results were promising, though the engine was not optimised for the combustion concept being studied and minimum modifications were done to the engine. High E85 rates (up to 89%) by energy content were achieved, especially under medium load conditions. On the high and low load portions were lower, but the E85 rates were higher than 30% even in these cases. For most of the cases, the limiting issue was the pressure rise rate, but in cases with the highest portions of E85 the limiting factor was the minimum quantity of the diesel fuel enabling two phase diesel fuel injection. In all cases the E85 increased carbon-monoxide and un-burned hydrocarbon emission, but the nitrogen oxide emission decreased simultaneously in most of the cases. Smoke emissions were low in all cases, but at highest E85 rate smoke emissions further decreased to near zero value.