Experimental Studies On Emission And The Physicochemical Characteristics Of Particulates For Diesel Engine With Low Proportion Biodiesel

Faced with the menace of energy shortage and environmental pollution, the relevant experts and scholars nowadays urgently need to find alternative energy for traditional fossil fuel. Bio-diesel, a kind of renewable and green energy, is drawing more and more attention to research on the regulated emissions and physicochemical characteristics of particulates produced by diesel engine blended with bio-diesel,which is of great theoretical value and application significance.The instrument and equipment concerned with bench test were utilized to study the regulated emission characteristics of 186 FA diesel with different proportions of bio-diesel under the premise of ensuring the output power and fuel spray performance,and the MOUDI was utilized to study the relationship between mass concentration,particle size distribution characteristics and the different proportions of bio-diesel.The results indicate that bio-diesel causes the less emissions of CO, HC and soot, the more emissions of NOX at medium or high load while having no obvious effect on regulated emissions at low load. The mass emission of particulate matter increases with the raise of load. At the same time, the higher the particle size is, the lower the particle mass concentration will be. Bio-diesel can significantly improve the particle emissions of accumulation mode, the particle mass concentration is reduced more as the bio-diesel blending ratio increases.SEM and TEM were utilized to study the effect of bio-diesel on the spatial distribution and overall morphology of particulates. Two main program design, image preprocessing and iterative statistical, were completed based on MATLAB, which is aimed to quantitatively characterize the density and irregular shape of the particulates by introducing the box-counting dimension. The influence of the content of bio-diesel on the oxidation characteristics of particulates and the effect of the microstructure on the oxidation activity were studied through the analysis techniques combined with TGA and HRTEM. The results show that bio-diesel has obvious effect on the accumulation of coarse particles, mixing a certain proportion of bio-diesel has very small effect on original particle size, beyond the scope the particle size significantlyincreases. At low load, the number of primary particles is small, and the morphology is single, mainly in the globular and linear. With the increase of engine load, gradually increases the number of primary particles, the agglomeration phenomenon aggravates,particle morphology complicates. At high load bio-diesel improves particles morphology significantly, with increase of adding ratio of bio-diesel, the overall size of the particles decreases, the dimension of particle decreases gradually. The higher the bio-diesel content is in the fuel, the more is SOF components in the particulate matter and the less is soot component. Blending bio-diesel is easy to produce multiple core structure particles, in which the core’s oxidation activity is higher than the outer shell, and the hollow capsule structure will appear in the oxidation process. The oxidation resistance of the single core particles is better than that of the multiple core ones, for the oxidation process is from shell to core.