Analysis of morphology, nanostructure, and oxidation reaction of soot particulates from CI engines with dimethoxymethane–diesel blends under different loads and speeds

Abstract

Dimethoxymethane (DMM)-diesel blended fuels can simultaneously reduce exhaust emissions of soot and nitrogen oxide (NO X ); several studies have been conducted in this regard. However, the influence of additive DMM on the production of inception and precursors of particulates, especially the relation between oxidation, morphology, and the nanostructure of soot particles has not been extensively investigated. In this study, a transmission electron microscope (TEM) and a thermogravimetric analyzer are introduced to acquire TEM images and conduct temperature-programmed-oxidation experiments. Aiming to study the influence of DMM addition on soot oxidation, morphology, and nanostructure, tests are conducted at different rotational speeds (1400 rpm and 2200 rpm), two engine loads (0.6 MPa and 1.2 MPa), and three fuels (D100, DMM6.4, and DMM13). The results show that the diameter distributions of all samples display a similar distribution, with the range of sample diameters being from 10 to 45 nm, and the addition of DMM reduces the dp (primary particle diameters) and the Df (fractal dimension), indicating a decreased structural compactness of aggregates, compared with diesel. Moreover, with increasing load and speed, La (the length of the fringe) increases and d (the distance between adjacent layer planes) decreases. Furthermore, with the addition of DMM, a more regular and higher degree of graphitization within soot particles can be observed in comparison to D100. The nanostructure influences the oxidation reaction of graphene segments with a line relation, leading to a difference in soot oxidation property.

Morphological characterization of soot from a compression ignition engine fueled with diesel and an oxygenated fuel

“…However, there are not many studies on the morphology of fuel alternatives. Qian et al 50 compared Dimethoxymethane (DMM) – diesel blends to diesel at medium and high load conditions in a four cylinder CI engine. Both fuels had similar CN, density and heating value.…”

Analytical Methods for Physicochemical Characterization and Toxicity Assessment of Atmospheric Particulate Matter: A Review

“…The internal structure of primary particles can be classified into: (a) purely turbostratic structures; (b) fullerenoid (onion-shaped) structures; (c) turbostratic structures with non-aligned basal planes; and (d) shell-core structures with multiple spherical nuclei oriented concentrically, making up the "outer core" with randomly oriented layers (Figures 3 and 4) [36,47]. Several studies have also reported the ability of particulates to exhibit certain shapes and form chain-like or grain-like structures (e.g., soot from diesel exhaust) [36,48,49]. [51] with the permission of The Journal of Geophysical Research; ref.…”

Carbon Nanomaterials Derived from Black Carbon Soot: A Review of Materials and Applications

“…The DMM addition leads to a higher degree of graphitization in comparison to D100. Increments of the loading and speed result in an increment of the fringe length with a decrement of the adjacent layer plane distance . Yang et al studied the structure of particulate matter liberated from the different mixtures of diesel and oxygenated fuel poly­(oxymethylene dimethyl ethers) (PODEn) .…”