Due to the limited energy resources as well as due to increasing CO2-emissions the importance of alternative- and biogene fuels increases continuously.
Investigations of the engine operation were performed on a latest technology Liebherr engine for construction machines, which was operated using crude rapseed oil (ROR), rapseed methyl ester (RME) and synthetic Gas-To-Liquid fuel (GTL) without any change of ECU setting. On this occasion the combustion diagnostics, behaviour of the injection system and the pollutant emissions, including the unlimited nano-particles were especially assessed.
For injection (with this unit pumps system) it can be stated, that ROR and a little bit less RME shorten the injection lag and increase the maximum injection pressure. At higher engine load this causes the 50% heat release a little earlier (1-2°CA) and as consequence higher NOx and lower specific energy consumption.
Nevertheless the limited emissions CO, HC, NOx, PM as well as the integrated nanoparticles counts and energy consumption show different results and different relationships between the fuels depending on the engine operating conditions.
Due to that a simple classification of the investigated fuels, like “best-worst” is not possible.