ECO-DIESEL ENGINE FUELED WITH RAPESEED OIL METHYL ESTER AND ETHANOL

Abstract

A novel concept of fueling of the diesel engine with biofuels: rapeseed oil methyl ester (RME) and ethanol was proposed, developed, and investigated. The idea of the concept depends on standard fueling with RME and additional injection of ethanol into the inlet port at the inlet valve, which had yet not opened. This enabled ethanol to evaporate and, in the result, filling the cylinder with gaseous mixture of ethanol and air. After ignition from burning RME droplets, the ethanol-air mixture burns very quickly and promotes combustion of main fuel droplets. This results in a shorter combustion period. Experiments were carried out with the use of a one-cylinder direct-injection diesel engine adapted to ethanol injection at three speeds and two loads: low and high and for three injection timings. At each experimental point (i.e., for constant load and speed), and changing quantity of ethanol (proportion of ethanol to RME was changed from zero to the value at which diesel knock occurred). This procedure enabled to find influence of ethanol energy to total fuel energy ratio (ΩE) on efficiency and emissions (ΩE was a main independent variable parameter). Considerable decrease of CO2 and smoke level was obtained and-for high load-also CO and HC emission. At low loads, NOx emission was reduced. The optimum ratio of ethanol energy to total fuel energy, in terms of brake fuel conversion efficiency and benefit of emission decrease, was found to be about 25%.