Study on the effect of diesel blended with n-butanol on particulate matter state characteristics of a small agricultural diesel engine

This work studied the effect of diesel blended with n-butanol on particulate matter (PM) state characteristics of a small agricultural diesel engine which revealed the mechanism of n-butanol reducing PM emissions in diesel engine. The microstructure, oxidation characteristics, components and surface functional groups of PM with N5 (5% n-butanol and 95% diesel fuel in quality basis), N10 and diesel fuel were measured. The results indicated that n-butanol/diesel PM displayed cluster structure. With the increase in n-butanol content, the average diameter of PM gradually decreased while aggregation degree increased. Pyrolysis of PM in the air was divided into two stages - soluble organic matter evolution stage and soot combustion stage. With the increase in n-butanol content, the initial combustion temperature of soot decreased, the temperature corresponding to the mass change rate peak of weightlessness with PM dropped, soluble organic matter and soot content in particulate fractions increased, while metal and inorganic salt content decreased. The equivalent peak height ratio (IC-H-IC=C)/IC=C of aliphatic functional C-H on particulate surface increased and its relative content gradually increased.