Study on the Structure Characteristics of Diesel Engine Particulates Based on Small‐Angle X‐Ray Scattering

Abstract

In this article, the particulates formed by the combustion of diesel, 20% and 50% biodiesel blended in diesel (denoted as B20 and B50, respectively), and biodiesel were collected. The micromorphologies of the particulates were observed by scanning electron microscopy. Furthermore, the small‐angle X‐ray scattering technique was used to analyze the gyration radius, size distribution, interfacial characteristics, and fractal characteristics of the particulates. The results show that the size of the particulates formed by combustion of the fuels was concentrated between 10 and 35 nm and obeyed a Gaussian distribution. Moreover, the addition of biodiesel to diesel led to smaller particulate sizes for the biodiesel/diesel blend: the mean radii of the particulates for diesel, B20, B50, and biodiesel were 11.5 nm, 10.8 nm, 10.2 nm, and 9.7 nm, respectively. In addition, an interfacial layer was observed between the particulates, and the average interfacial thickness of the particulates was between 1.54 and 1.89 nm. The mass fractal dimension of the particulates was between 0.2 and 2.5, and the surface fractal dimension of the particulates was between 2.1 and 2.9. The addition of biodiesel to diesel resulted in a more compact particulate structure and the rougher surface. © 2019 American Institute of Chemical Engineers Environ Prog, 38:e13146, 2019

Correlation analysis of mechanical and state characteristics of diesel engine exhaust particles

“…The a, b, and c clusters are gradually stacked into from chain‐like floc with clear edges, and the average particle has increased, in the order of 30, 37, and 46 nm. This coincides with the concentration of particles reported in the literature to be between 10 and 50 nm in size 17 . Related studies show that particle collision and coalescence efficiency is mainly affected by the particle size and number of particles in the initial state 40 .…”

“…Guinier is suitable for particles of any shape in the small‐angle part of the scattering curve. According to the relationship between the average radius of spherical or approximately spherical particles and the radius of gyration, combined with the linear fitting slope of the curve in Figure 6c, the radius of gyration and the average pore diameter of the particles can be calculated 17 . According to Equations () ~ (), the sample particles' axial length and distribution dimension can be obtained.…”

“…Combining the particles' morphological characteristics, the analysis in Figure 5 shows that the difference in particle size leads to changes in the attractive force and adhesion between particles, changing the degree of particle agglomeration and arrangement density. With the increase of particles' average size, the attraction between particles is strengthened, the particles gradually agglomerate, change from dendritic to cluster‐like, and gradually pile up in a mountain‐like shape—both the particle density and the cluster size increase 17,44 . When the particle size increases, considering that the compression distance between particles is constant, the contact area between particles, the adhesion between particles, the energy barrier, and the minimum energy barrier to overcome when particles are broken are increased.…”

“…The results show that the atomic force microscope (AFM) has high accuracy in measuring the morphological characteristics of microscopic particles. Li et al 17,18 investigated the effect of diesel/ biodiesel and methanol/biodiesel blending ratios on the microscopic morphology of diesel exhaust particles using scanning electron microscopy. The results showed that the particle size increased as the blending ratio increased.…”

Study on Particulate Structure Characteristics of Diesel Engines Fueled with a Methanol/Biodiesel Blend

“…Oxygen-containing fuels, as the clean renewable energy fuels for diesel engines, can improve the combustion process of diesel engines. Alcohols and biodiesel are oxygen-containing fuels and are suitable for use in diesel engines and have been extensively accepted as partial diesel fuel substitutes. − Methanol and biodiesel have a wide range of sources and contain 50 and 11% oxygen, respectively. Methanol and biodiesel have good mutual solubility and are easy to prepare blends.…”