Improvement in Diesel Combustion with Emulsified Blends of Aqueous Ethanol and Diesel Fuel

Abstract

This paper discusses the operational characteristics of two emulsified blends of aqueous ethanol and diesel fuel in a DI diesel engine with supercharging and cooled EGR. Two emulsified blends: one with 25 vol% aqueous ethanol (E20W5, Ethanol: 20 vol%, Water: 5 vol%) and the other with 50 vol% aqueous ethanol (E40W10, Ethanol: 40 vol%, Water: 10 vol%) were examined. Silent, low NOx, and smokeless combustion was realized over a wide load range with the emulsified fuel, E40W10 when the quantity of pilot injection and the intake oxygen content were optimized. The results show that smokeless operation can be established with low pressure injection and low intake oxygen content. The degree of constant volume heat release and the indicated thermal efficiency with the emulsified fuels improved over a wide load range as the pilot injection quantity was increased and the heat release with the pilot injection was retarded to near TDC. The degree of constant volume heat release with the emulsified fuel also improved, mainly due to the reduction in afterburning with smaller quantities of the main injection.