Evaluation of RME (rapeseed methyl ester) and mineral diesel fuels behaviour in quiescent vessel and EURO 5 engine

Alternative diesel fuels for internal combustion engines have grown significantly in interest in the last decade. This is due to the potential benefits in pollutant emissions and particulate matter reduction. Nevertheless at possible increase in nitrogen oxide (NOx), and almost certainly increase of fuel consumption have been observed. In this paper, mineral diesel and RME (rapeseed methyl ester) fuels have been characterized in a non-evaporative spray chamber and in an optically-accessible single-cylinder engine using a Common Rail injector (8 holes, 148° cone opening angle and 480cc/30s@10MPa flow number) to measure the spatial fuel distribution, the temporal evolution and the vaporization-combustion processes. The injection process and mixture formation have been investigated at the Urban Driving Cycle ECE R15: 1500rpm at 0.2MPa of break mean effective pressure. Characteristic parameters of the spray like penetration length and liquid fuel distribution have been analysed and they have been correlated with the exhaust gaseous and particulate matter emissions. In the spray-analysis in non-evaporative conditions, short events (pilot) are mostly affected by asymmetries in the fuel distributions with noticeable standard deviations at low injected quantities. In the engine tests, the jets reached immediately the stabilization. A comparative analysis on the liquid phase of the spray, in non-evaporative and evaporative conditions, has permitted to investigate better the mixture formation. Its effect on pollutant emissions has been analysed for both fuels.