Study On Formation Mechanism Of Particles Of Diesel Engine Fueled With Pistacia Chinensis Bunge Seed Biodiesel

The economic performance of diesel engine is very good, but higher particulateemissions which generated by combustion limits diesel engine development andbecomes key and difficult problems. The study of clean alternative fuels of dieselengine (such as biomass fuels) and particle formation mechanism will help tofundamentally purifying diesel engine exhaust pollution, reduce particulate emissionsand realize low pollution of diesel engine combustion.This paper mainly studies the volatile organic fraction, morphology andmicrostructure of soot emitted from YTR3105agricultural diesel engine and GW4D20car with diesel engine which fuelled with different proportions of Pistacia chinensisseed biodiesel in different injection timings, the EGR rates and operating conditionswith thermal-gravimetric analysis and high-resolution transmission electronmicroscopy methods. The main conclusions are as follows:1. For YTR3105diesel engine, the volatile organic fractions in particles generatedby B0, B10and B20peaked at the evaporation temperature of150~180℃. Thevolatile organic fraction in the particulate emissions increases and the proportions ofelemental carbon decreases with the increase of the proportions of biodiesel in theblends.2. The particles emitted from YTR3105and GW4D20diesel engine have asimilar microscopic structure. From the morphology, the soot particles are piled up bythe dozens, hundreds of spherical primary particles and exhibit different shapes andcharacteristics of fractal structure. From the microstructure of primary particles whichform particles, the primary particles have two parts of the shell and the core. The shellshows a multilayer graphite-like microcrystalline structure. The core is disorderedamorphous structure with a weak thermal stability.3. For YTR3105diesel engine, injection timing and operating conditions havelittle effect on the size of primary particles; Mean diameter of primary particles for B20was larger than that for B0. For GW4D20diesel engine, the blend ratio of pistaciachinensis seed biodiesel within a certain range has little effect on the size of primaryparticles. Overall, compared to the two engines, the mean diameter of primaryparticles produced by YTR3105diesel engine is larger than that produced by GW4D20diesel engine.4. For GW4D20diesel engine, as the percentage of Pistacia chinensis Bunge seedbiodiesel increased, fractal dimension increased and primary particles become moreclose together; and mean fringe separation distances decrease and the oxidativeactivities become lower. Mean fringe separation distance increases with the increase ofthe load. In the test conditions, with the decrease of the EGR valve, the mean diameterof primary particle for B50increases3.35nm, a slight increase in the fringe separationdistance; the mean diameter of primary particle for B50slightly decrease and fringeseparation distance decreases0.029nm.