Research on Engine Lube Oil Deterioration and Emissions of Diesel Engines with BioFuels (RME)

In the Diesel sector the fatty acid methyl esters (FAME’s) – in Europe mostly RME *) (rapeseed methyl ester) and in US mostly SME (soja oil methyl ester) – are used as a various share, % volume blends with the Diesel fuel (B5, B7, B10, B20, Bxx). The present joint project focuses on RME being the most important representative of the biofuels of 1st generation in Europe. The influences of RME blend fuels on emissions and on lube oil deterioration are emphasised.Emissions were investigated on a modern engine with exhaust gas aftertreatment devices like SCR and (DPF+ SCR) with blend fuels containing different share of RME (B7, B20, B30 & B100).The most important findings are:•the increased share of RME w/o aftertreatment causes an increase of NOx by higher engine load and reduction of CO & HC; at transient operation (ETC) these tendencies are less pronounced and only B100 shows an increase of NOx,•with SCR alone there are no differences of NOx and of NOx reduction rate (KNOX) with increasing RME portion; there is lowering of CO & HC,•with DPF+SCR KNOX-values are slightly higher, than with SCR alone, due to the production of NO2 in the catalytic DPF (upstream of SCR),•there is excellent count filtration efficiency of DPF, up to 99.9%; with SCR alone there is usually a small reduction of nanoparticles concentrations (in the range of 10-20%, similar like an usual oxidation catalyst).The paper describes as well significant problems related to the influences of biofuels on engine lube oils deterioration demonstrated by monitoring the engine lube oil aging during its operation in heavy duty (HD) and modern high speed direct injection (HSDI) light duty (LD) engine through the bench tests. Increasing usage of Diesel biofuels has an impact on accelerated degradation of engine oil performance. On the basis of the obtained results it can be stated that:•the presence of bio-components in the fuel has significant impact on multidirectional hastening of engine lube oil destruction processes,•kind of base lube oil, lube oil additives components and RME-portion, as well as engine design and its operating conditions are very essential factors influencing the engine lube oil performance degradation,•the processes taking place in an engine lubricant, adversely influence the limited possibilities of bio-componentsevaporation from engine lube oil and contribute to initiation of accelerated, deeper engine lube oil oxidation and degradation. Oxidation causes the oil to thicken, to form acids and generally to lose the lubrication qualities which are important for engine performance. The aged lube oil shortens the engine life by creation deposits on engine pistons, in combustion chambers and on valves, stucking rings and provoking the bore polishing.