Particulate Emissions from a Common Rail Fuel Injection Diesel Engine with RME-based Biodiesel Blended Fuelling Using Thermo-gravimetric Analysis

Increasing biodiesel content in mineral diesel is being promoted considerably for road transportation in Europe. With positive benefits in terms of net CO₂ emissions, biofuels with compatible properties to those of conventional diesel are increasingly being used in combustion engines. In comparison to standard diesel fuel, the near zero sulphur content and low levels of aromatic compounds in biodiesel fuel can have a profound effect not only on combustion characteristics but on engine-out emissions as well. This paper presents analysis of particulate matter (PM) emissions from a turbo-charged, common rail direct injection (DI) V6 Jaguar engine operating with an RME (rapeseed methyl ester) biodiesel blended with ultra low sulphur diesel (ULSD) fuel (B30 - 30% of RME by volume). Three different engine load and speed conditions were selected for the test and no modifications were made to the engine hardware or engine management system (EMS) calibration. In this work specific total particulate mass was measured at each operating point and, in addition, thermo-gravimetric analysis (TGA) was used to determine mass fractions of the volatile PM. Although the relative effect on particulate emissions was dependent on engine operating speed and load, the effects of engine operation modes such as degree of exhaust gas recirculation EGR also have to be accounted for. In general, total PM mass from B30 combustion was lower than that for ULSD in all engine operating conditions. Moreover, elemental carbon PM mass fractions were slightly lower for the B30. For both fuels used in the test, volatile organic fraction (VOF) was observed to be higher at idle speed and light load when exhaust gases were at low temperature.