Comparative study of fuel injection at common rail system using different types of fuel

In recent years the use of alternative fuels based, among other things, on vegetable oil is causing increasing concern, which is also observed in our country. Such fuels have different physical and chemical properties (especially viscosity) with reference to the standard diesel fuel. Therefore it is important to know the effect of the additive of biocomponents on fuel injection process, in particular of its parameters, which play an important role in the combustion process and formation of pollutions in exhaust gases. In the paper is presented the test results of selected parameters of the injection process executing by four different electromagnetically controlled injectors using diesel fuel without the biocomponents and mixtures of such fuel with esters of rapeseed oil (FAME). Investigations were carried out on a specially prepared test stand which enables the measurement of fuel delivery and fuel returning from the injector together with its density and temperature. Additionally, beside mentioned parameters, there were recorded high-speed courses of pressure in the high-pressure pipe behind the rail and before the injector. Next, using a system of AVL Visioscope, the fuel injection into the visualization chamber filled with fuel was recorded. It determined the basic parameters of the fuel spray. The aim of this study was to determine the impact of fuel type on the injection process executed by the injectors with different constructional parameters.