Influence of fuel injection pressure and RME on combustion, NO⨯ emissions and soot nanoparticles characteristics in common-rail HSDI diesel engine

‏ Manipulating in fuel injection strategies and introduce renewable fuel in diesel engine can provide clean combustion and lower pollutant emissions. The effect of fuel injection pressures (FIPs) and RME on combustion characteristics, NOx emissions and soot nanoparticle emissions when rapeseed methyl esters was used have been investigated at 1500 rpm and two brake mean effective pressure of 2.5 and 5 bar. A calibrated electrostatic mobility spectrometer (EMS) was used to measure the soot nanoparticle number size distributions. The peak cylinder pressure and heat release rates were evaluated when the FIP increased for all fuels studied. The results showed that further advanced in combustion with RME, meanwhile a shorter ignition delay from the fuel was exhibited in comparison with diesel fuel combustion under various FIP. Furthermore, the values of BSFC decreased by 3.7% and 17.8% from the RME combustion at high and low engine load, respectively. The reduction in NOx emissions was obtained when FIP increased during RME combustion in comparison with ULSD under low engine load. In contrast, RME generated higher NOx by 7% and lower soot nanoparticles by 27% compared to the ULSD under high engine load. RME combustion produced lower nucleation particle numbers in comparison with those emitted from ULSD under all engine operating conditions as well as the accumulation mode particles was higher for ULSD.