Fractal Characteristics of Soot Particles in Ethylene/Air inverse diffusion Flame

2014 ◽  
Vol 953-954 ◽  
pp. 1196-1200 ◽  
Author(s):  
Jian Yi Lv ◽  
Xin Cao ◽  
Cheng Long Meng
Keyword(s):  
Fractal Dimension ◽  
Primary Particle ◽  
Fractal Dimensions ◽  
Flame Height ◽  
Soot Particles ◽  
Transmission Electron ◽  
Primary Particles ◽  
Fractal Characteristics ◽  
Inverse Diffusion ◽  
Inverse Diffusion Flame

Soot is produced in incomplete combustion of fuels, it is harmful to human health and the environment. Sampling points were set along the flame height of different air-fuel ratios in ethylene/air IDF and samples were tested by transmission electron microscopy (TEM). MATLAB software was used to process TEM images, calculated the fractal dimensions of soot samples and analyzed the fractal features. With the increasing of air-fuel ratio, the soot fractal dimension decreases, the size and the number of primary particles included in aggregates increase. With the increasing of flame height, the fractal dimension value decreases, and the size of primary particle increases, the aggregating soot particles are united loose.

scholarly journals Technical Note: The single particle soot photometer fails to detect PALAS soot nanoparticles

2012 ◽  
Vol 5 (4) ◽  
pp. 4905-4925 ◽  
Author(s):  
M. Gysel ◽  
M. Laborde ◽  
J. C. Corbin ◽  
A. A. Mensah ◽  
A. Keller ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Single Particle ◽  
Primary Particle ◽  
Particle Morphology ◽  
Counting Efficiency ◽  
Particle Mass ◽  
Effective Density ◽  
Soot Particles ◽  
Primary Particles ◽  
Small Primary

Abstract. The single particle soot photometer (SP2) uses laser-induced incandescence (LII) for the measurement of atmospheric black carbon (BC) particles. The BC mass concentration is obtained by combining quantitative detection of BC mass in single particles with a counting efficiency of 100% above its lower detection limit (LDL). It is commonly accepted that a particle must contain at least several tenths of femtograms BC in order to be detected by the SP2. Here we show the unexpected result that BC particles from a PALAS spark discharge soot generator remain undetected by the SP2, even if their BC mass, as independently determined with an aerosol particle mass analyser (APM), is clearly above the typical LDL of the SP2. Comparison of counting efficiency and effective density data of PALAS soot with flame generated soot (combustion aerosol standard burner, CAST), fullerene soot and carbon black particles (Cabot Regal 400R) reveals that particle morphology can affect the SP2's LDL. PALAS soot particles are fractal-like agglomerates of very small primary particles with a low fractal dimension, resulting in a very low effective density. Such loosely-packed particles behave like "the sum of individual primary particles" in the SP2's laser. Accordingly, the PALAS soot particles remain undetected as the SP2's laser intensity is insufficient to heat the primary particles to vaporisation because of their small size (primary particle diameter ~5–10 nm). It is not surprising that particle morphology can have an effect on the SP2's LDL, however, such a dramatic effect as reported here for PALAS soot was not expected. In conclusion, the SP2's LDL at a certain laser power depends on total BC mass per particle for compact particles with sufficiently high effective density. However, for fractal-like agglomerates of very small primary particles and low fractal dimension, the BC mass per primary particle determines the limit of detection, independent of the total particle mass. Consequently, care has to be taken when using the SP2 in applications dealing with loosely-packed particles that have very small primary particles as building blocks.

scholarly journals Development of Back-calculation Model for Aggregate Gradation Determination Using Fractal Theory

2018 ◽  
Vol 159 ◽  
pp. 01006
Author(s):  
Bagus Hario Setiadji ◽  
Supriyono ◽  
Djoko Purwanto
Keyword(s):  
Fractal Dimension ◽  
Fractal Theory ◽  
Asphalt Mixture ◽  
Fractal Dimensions ◽  
Calculation Model ◽  
Careful Consideration ◽  
Upper And Lower Bounds ◽  
Aggregate Gradation ◽  
Fractal Characteristic ◽  
Fractal Characteristics

Several studies have shown that fractal theory can be used to analyze the morphology of aggregate materials in designing the gradation. However, the question arises whether a fractal dimension can actually represent a single aggregate gradation. This study, which is a part of a grand research to determine aggregate gradation based on known asphalt mixture specifications, is performed to clarify the aforementioned question. To do so, two steps of methodology were proposed in this study, that is, step 1 is to determine the fractal characteristics using 3 aggregate gradations (i.e. gradations near upper and lower bounds, and middle gradation); and step 2 is to back-calculate aggregate gradation based on fractal characteristics obtained using 2 scenarios, one-and multi-fractal dimension scenarios. The results of this study indicate that the multi-fractal dimension scenario provides a better prediction of aggregate gradation due to the ability of this scenario to better represent the shape of the original aggregate gradation. However, careful consideration must be observed when using more than two fractal dimensions in predicting aggregate gradation as it will increase the difficulty in developing the fractal characteristic equations.

Application of Fractal Theory in Aggregate Gradation Research

2012 ◽  
Vol 204-208 ◽  
pp. 1923-1928
Author(s):  
Bo Tan ◽  
Rui Hua Yang ◽  
Yan Ting Lai
Keyword(s):  
Fractal Dimension ◽  
Fractal Theory ◽  
Asphalt Mixture ◽  
Fractal Dimensions ◽  
Aggregate Gradation ◽  
Structure Characteristics ◽  
Aggregate Distribution ◽  
Dimension Formula ◽  
Mass Fractal ◽  
Fractal Characteristics

The paper presents the fractal dimension formula of distribution of asphalt mixture aggregate diameter by the deducing mass fractal characteristics function. Taking AC-20 and SMA-20 as examples, selected 6 groups of representative grading curves within the grading envelope proposed by the present specification, and calculated their fractal dimensions. The asphalt mixture gradation has fractal dimension D (D∈(1,3)), and the fractal of continuous gradation is single while the fractal of gap-gradation shows multi-fractal with 4.75 as the dividing point. Fractal dimension of aggregate gradation of asphalt mixture reflect the structure characteristics of aggregate distribution, that is, finer is aggregate, bigger is the fractal dimension.

scholarly journals The Impacts of Matrix Compositions on Nanopore Structure and Fractal Characteristics of Lacustrine Shales from the Changling Fault Depression, Songliao Basin, China

Minerals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 127 ◽  
Author(s):  
Zhuo Li ◽  
Zhikai Liang ◽  
Zhenxue Jiang ◽  
Fenglin Gao ◽  
Yinghan Zhang ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Pore Structure ◽  
Fractal Dimensions ◽  
Organic Medium ◽  
Songliao Basin ◽  
Sem Images ◽  
Fractal Characteristics ◽  
Inorganic Mineral ◽  
Nanopore Structure ◽  
High Fractal Dimension

The Lower Cretaceous Shahezi shales are the targets for lacustrine shale gas exploration in Changling Fault Depression (CFD), Southern Songliao Basin. In this study, the Shahezi shales were investigated to further understand the impacts of rock compositions, including organic matters and minerals on pore structure and fractal characteristics. An integrated experiment procedure, including total organic carbon (TOC) content, X-ray diffraction (XRD), field emission-scanning electron microscope (FE-SEM), low pressure nitrogen physisorption (LPNP), and mercury intrusion capillary pressure (MICP), was conducted. Seven lithofacies can be identified according to on a mineralogy-based classification scheme for shales. Inorganic mineral hosted pores are the most abundant pore type, while relatively few organic matter (OM) pores are observed in FE-SEM images of the Shahezi shales. Multimodal pore size distribution characteristics were shown in pore width ranges of 0.5–0.9 nm, 3–6 nm, and 10–40 nm. The primary controlling factors for pore structure in Shahezi shales are clay minerals rather than OM. Organic-medium mixed shale (OMMS) has the highest total pore volumes (0.0353 mL/g), followed by organic-rich mixed shale (ORMS) (0.02369 mL/g), while the organic-poor shale (OPS) has the lowest pore volumes of 0.0122 mL/g. Fractal dimensions D1 and D2 (at relative pressures of 0–0.5 and 0.5–1 of LPNP isotherms) were obtained using the Frenkel–Halsey–Hill (FHH) method, with D1 ranging from 2.0336 to 2.5957, and D2 between 2.5779 and 2.8821. Fractal dimensions are associated with specific lithofacies, because each lithofacies has a distinctive composition. Organic-medium argillaceous shale (OMAS), rich in clay, have comparatively high fractal dimension D1. In addition, organic-medium argillaceous shale (ORAS), rich in TOC, have comparatively high fractal dimension D2. OPS shale contains more siliceous and less TOC, with the lowest D1 and D2. Factor analysis indicates that clay contents is the most significant factor controlling the fractal dimensions of the lacustrine Shahezi shale.

scholarly journals Fractal Characteristics of Chip Morphology and Tool Wear in High-Speed Turning of Iron-Based Super Alloy

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 1020
Author(s):  
Xu Zhang ◽  
Guangming Zheng ◽  
Xiang Cheng ◽  
Rufeng Xu ◽  
Guoyong Zhao ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Tool Wear ◽  
High Speed ◽  
Cutting Speed ◽  
Fractal Dimensions ◽  
Chip Morphology ◽  
Color Changes ◽  
Fractal Characteristics ◽  
Iron Based ◽  
Super Alloy

Considering that iron-based super alloy is a kind of difficult-to-cut material, it is easy to produce work hardening and serious tool wear during machining. Therefore, this work aims to explore the chip change characteristics and tool wear mechanism during the processing of iron-based super alloy, calculate the fractal dimensions of chip morphology and tool wear morphology, and use fractals to analyze their change trend. Meanwhile, a new cutting tool with a super ZX coating is used for a high-speed dry turning experiment. The results indicate that the morphology of the chip is saw-tooth, and its color changes gradually, due to the oxidation reaction. The main wear mechanisms of the tool involve abrasive wear, adhesive wear, oxidation wear, coating spalling, microcracking and chipping. The fractal dimension of the tool wear surface and chip is increased with the improvement of cutting speed. This work investigates the fractal characteristics of chip morphology and tool wear morphology. The fractal dimension changes regularly with the change of tool wear, which plays an important role in predicting this tool wear. It is also provides some guidance for the efficient processing of an iron-based super alloy.

Nano-Pore Structure and Fractal Characteristics of Shale Gas Reservoirs: A Case Study of Longmaxi Formation in Southeastern Chongqing, China

2021 ◽  
Vol 21 (1) ◽  
pp. 343-353
Author(s):  
Wei-Dong Xie ◽  
Meng Wang ◽  
Xiao-Qi Wang ◽  
Yan-Di Wang ◽  
Chang-Qing Hu
Keyword(s):  
Fractal Dimension ◽  
Pore Structure ◽  
Shale Gas ◽  
Fractal Dimensions ◽  
Gas Reservoirs ◽  
Longmaxi Formation ◽  
Shale Gas Reservoirs ◽  
Fractal Characteristics ◽  
Temperature Liquid ◽  
Menger Sponge

Pore structure and fractal dimensions can characterize the adsorption, desorption and seepage characteristics of shale gas reservoirs. In this study, pore structure, fractal characteristics and influencing factors were studied of the Longmaxi formation shale gas reservoir in southeastern Chongqing, China. Scanning electron microscopy was used to describe the characteristics of various reservoirs. High pressure mercury intrusion and low temperature liquid N2 and CO2 adsorption experiments were used to obtain pore structure parameters. V–S model, FHH model and Menger sponge model were selected to calculate the micropore, mesopore and macropore fractal dimensions, respectively. The results show that organic matter pores, inter-granular pores, intra-granular pores and micro-fractures are developed within the shale, and the pore morphology is mostly ink pores and parallel plate pores with aperture essentially in the 1–2 nm and 2–50 nm ranges. Moreover, macropores are the most complex in these samples, with mesopores being less complex than macropores, and the micropores being the simplest. D1 (micropore fractal dimension) ranges from 2.31 to 2.50, D2 (mesopore fractal dimension) ranges from 2.74 to 2.83, D3 (macropore fractal dimension) ranges from 2.87 to 2.95, and Dt (comprehensive fractal dimension) ranges from 2.69 to 2.83 of fractal characteristics. D1 and D2 are mainly controlled by TOC content, while D3 and Dt are mainly controlled by brittle and clay mineral content. These results may be helpful for exploration and the development of shale gas in southeastern Chongqing, China.

Fractal Characteristics and Its Controlling Factors of Nanopore of Coal from Shanxi Province, North China

2021 ◽  
Vol 21 (1) ◽  
pp. 727-740
Author(s):  
Zhi Xu ◽  
Ming Li ◽  
Yu Xu ◽  
Luwei Sun
Keyword(s):  
Fractal Dimension ◽  
Coalbed Methane ◽  
Correlation Coefficients ◽  
Fractal Dimensions ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
Fractal Model ◽  
Shanxi Province ◽  
Fractal Characteristics ◽  
Permian Coal

Much attention has been recently paid to the Carboniferous-Permian coal-bearing strata in Shanxi Province, now the largest producing coalbed methane field in China. In this study, a comprehensive approach of mercury injection, low-temperature liquid nitrogen adsorption, and permeability experiments was adopted to investigate the structure and fractal characteristics of nanopores in the Carboniferous-Permian coal (with 0.77%˜3.04% Ro,ran). Based on the fractal model, two fractal dimensions D1 and D2 corresponding to diffusion pore (<65 nm) and seepage pore (pore size ≥65 nm), respectively, were calculated, and the relationships between the fractal dimensions with the pore structure parameters and permeability are discussed here. The results indicate that the studied coal samples have good fractal characteristics and that the calculated linear correlation coefficients are higher than 0.80. The fractal dimension D1 of the diffusion pores ranges from 2.3777 to 2.4624, with an average of 2.4173, while the fractal dimension D2 of the seepage pores is between 2.5844 and 2.6256, with an average of 2.5990. The fractal dimensions D1 of the diffusion pores increases with an increase in the BET specific surface area, vitrinite content, and Ro,ran while it decreases with an increase in the permeability, and has a weak correlation with the total pore volume. The correlation coefficients R2 for the fractal dimension D2 of the seepage pores, pore parameters, permeability, and maceral composition ranges from 0.0357 to 0.2551. These results indicate that uncertain relationships exist among these parameters.

Fractal Characteristics of Primary Phase Morphology in Semisolid A356 Alloy

2012 ◽  
Vol 535-537 ◽  
pp. 936-940
Author(s):  
Zheng Liu ◽  
Xiao Mei Liu
Keyword(s):  
Fractal Dimension ◽  
A356 Alloy ◽  
Fractal Dimensions ◽  
Processing Parameters ◽  
Primary Phase ◽  
Phase Morphology ◽  
Box Counting ◽  
Magnetic Stirring ◽  
Fractal Characteristics ◽  
Electro Magnetic

Semisolid A356 alloy was prepared by low superheat pouring and slightly electro- magnetic stirring(LSPSES). The fractal dimensions of primary phase morphology in semisolid A356 alloy were researched by the calculating program written to calculate the fractal dimensions of box-counting in the image of primary phase morphology in semisolid A356 alloy. The results indicated that the primary phase morphology in the alloy was characterized by fractal dimension, and the morphology obtained by the different processing parameters had the different fractal dimension. The morphology at the different position of ingot had the different fractal dimensions, which reflected the effect of solidified conditions at different position in the same ingot on the morphology in the alloy. Solidification of the alloy was a course of change in fractal dimension.

scholarly journals An Investigation of Fractal Characteristics of Marine Shales in the Southern China from Nitrogen Adsorption Data

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Jian Xiong ◽  
Xiangjun Liu ◽  
Lixi Liang
Keyword(s):  
Fractal Dimension ◽  
Pore Structure ◽  
Southern China ◽  
Fractal Dimensions ◽  
Nitrogen Adsorption ◽  
Mean Value ◽  
Relative Pressure ◽  
Pore Surface ◽  
Adsorption Sites ◽  
Fractal Characteristics

We mainly focus on the Permian, Lower Cambrian, Lower Silurian, and Upper Ordovician Formation; the fractal dimensions of marine shales in southern China were calculated using the FHH fractal model based on the low-pressure nitrogen adsorption analysis. The results show that the marine shales in southern China have the dual fractal characteristics. The fractal dimensionD1at low relative pressure represents the pore surface fractal characteristics, whereas the fractal dimensionD2at higher relative pressure describes the pore structure fractal characteristics. The fractal dimensionsD1range from 2.0918 to 2.718 with a mean value of 2.4762, and the fractal dimensionsD2range from 2.5842 to 2.9399 with a mean value of 2.8015. There are positive relationships between fractal dimensionD1and specific surface area and total pore volume, whereas the fractal dimensionsD2have negative correlation with average pore size. The larger the value of the fractal dimensionD1is, the rougher the pore surface is, which could provide more adsorption sites, leading to higher adsorption capacity for gas. The larger the value of the fractal dimensionD2is, the more complicated the pore structure is, resulting in the lower flow capacity for gas.

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