An Investigation on the Particulate Size Emissions of Partially Premixed Combustion for n-butanol

An experimental investigation on effect of EGR, injection timing, intake pressure and injection strategy on combustion and particulate size distributions of n-butanol partially premixed combustion(PPC)under low loads was conducted in a single cylinder diesel engine. The results indicate that the properly small EGR rate can promote ignition which leads to a forward CA 50. The particulate diameter is less than 40 nm for most of particle emissions, and the most of particle emissions are nucleate mode. The scope of particle diameter broadens as the EGR rate increases, but the concentration and diameter of particulate matter decrease sharply when the EGR rate is too high since the longer ignition delay and retarded CA 50. The curves of particulate size distribution shift toward bigger diameter and higher concentration firstly, and then move toward smaller diameter and lower concentration as the injection timing advances. The particle concentration and diameter at the injection timing closed to top dead center(TDC) are smaller than that at the injection timing far from TDC under the same CA 50. The particle concentration is very low and the scope of particulate size distribution is small for lower intake pressure because of longer ignition delay. And the scope of particle diameter broadens as the intake pressure increases. The particle concentration and size are smaller for the two-state injection strategies compared to single injection strategy, and main-post injection strategy gives the lowest particle concentration among three injection strategy. © 2020, Editorial Office of the Transaction of CSICE. All right reserved.