Effects of Different Biodiesels and their Blends with Oxygenated Additives on Emissions from a Diesel Engine 2008-01-1812
Biodiesel is an alternative, renewable, clean fuel, which can effectively reduce emissions from diesel engines. However, the effects of biodiesel on engine emissions vary due to the difference in source. In this paper, performance of five different biodiesels was studied: CME, SME, RME, PME and WME. Engine power, fuel consumption, gaseous emissions and PM, DS and none soot fraction (NSF) were investigated in a Cummins ISBe6 Euro III diesel engine fueled with five biodiesels respectively and compared with the diesel fuel. Results revealed that using different biodiesels resulted in PM reductions ranging from 53% to 69%, which included DS reduction ranging from 79% to 83%. Observations showed that fuel oxygen content and viscosity had obvious effects on DS. Higher oxygen content biodiesels produced less DS at high load while lower viscosity biodiesels produced less DS at low load. Cetane number may be responsible to the NSF difference between biodiesels, for NSF decreased consistently with increasing cetane number exception for only one fuel.
Blended fuels with different physicochemical properties were obtained by blending biodiesels with certain proportions of ethanol, DMC and DMM and were tested on the same engine. The test results show that, as oxygen content increases, PM and DS emissions continue to decrease, but the decrease rate slows down. When oxygen content was up to 15% to 20%, nearly no DS was found. Biodiesel-Ethanol blends and Biodiesel-DMC blends are more effective in reducing PM and DS than Biodiesel-DMM blends. The NSF increase was observed with increasing oxygen content for all the three blended fuels. And increase of additives' cetane number from 8 to 36 did not show a reduction of NSF emission.