Influence of cetane number improver on performance and emissions of a common-rail diesel engine fueled with biodiesel-methanol blend

In this paper, the effect of cetane number (CN) improver on performance and emissions, including particulate number concentration and size distribution, of a turbocharged, common-rail diesel engine fueled with biodiesel-methanol were studied. Two volume fractions (0.3% and 0.6%) of CN improver were added to BM30 (30% of methanol in the biodiesel-methanol blend) in the experiment. The results show that, compared with those of biodiesel-methanol blend, the peak value of cylinder pressure increases, the second peak of heat release rate decreases, the start of second heat release are advanced, and the fuel economy and thermal efficiency are improved when CN improver is added to biodiesel-methanol blend. Besides, CO and HC emissions decrease, NOx emission varies little and smoke emissions increase slightly. Moreover, exhaust particles of BM30 mainly distribute in nanosize range. Furthermore, particle number concentration decreases and peak of size distribution profile shifts toward large size direction. © 2011 Higher Education Press and Springer-Verlag Berlin Heidelberg.