The effects of different biodiesel blends on engine-out emissions under various transient conditions were investigated in this study using fast response diagnostic equipment. The experimental work was conducted on a modern 3.0 L, V6 high pressure common rail diesel engine fuelled with mineral diesel (B0) and three different blends of rapeseed methyl esters (RME) (B30, B60, B100 by volume) without any modifications of engine parameters. DMS500, Fast FID and Fast CLD were used to measure particulate matter (PM), total hydrocarbon (THC) and nitrogen monoxide (NO) respectively. The tests were conducted during a 12 seconds period with two tests in which load and speed were changed simultaneously and one test with only load changing. The results show that as biodiesel blend ratio increased, total particle number (PN) and THC were decreased whereas NO was increased for all the three transient conditions. In addition, the largest PN transient spikes were observed for all the fuels in the test within the low-medium load speed change. Furthermore, the size of the spikes in PN decreased with the biodiesel blend ratio increasing. The duration of particulates transient recovery period was increased with the decease of biodiesel blend ratio for all the engine transient tests due to the oxygen content in biodiesel. Moreover, compared to the diesel fuel, almost doubled NO and half reduced PN and THC cumulative emissions were observed during a 15 seconds time interval with neat biodiesel.
