Study On Fractal Diffusion Aggregation Of Fine Particulate Matter In Soot

The soot particles emitted from coal-fired power plants are one of the main pollutants in haze weather.Coal-fired power plants generally use some purification processes and dust removal technologies to remove soot particles,which has achieved remarkable results,but a great deal of fine particulate matter is discharged into the atmosphere.The growth meehanism of the diffusion aggregation of fine particulate matter is still not completely clear.Therefore,the research on the diffusion aggregation mechanism and the control of fine particulate matter in soot have great theoretical significance and application value.Fractal theory is a nonlinear scientific theory with a wide range of applications and strong interdisciplinary intersections.It has been widely used in the fields of dendrite growth,chemical deposition and dust diffusion aggregation.This thesis aims at the fractal behavior of fine particulate matter in the process of diffusion aggregation by using the theory of cellular automata,small world network and fractal growth model to simulate and control the fractal diffusion aggregation of fine particulate matter in soot.The main research contents are as follows:(1)Fractal diffusion aggregation of fine particulate matter in soot based on cellular automataCellular automata can generate complex phenomena with fractal characteristics through simple rules.Based on the fractal growth model and the analysis of cellular automata evolution rules,the simulation and control of fine particulate matter fractal diffusion aggregation in coal-fired power plants are realized by using cellular automata theory.Different cellular automata rules are set to realize the directional diffusion aggregation control of fine particulate matter and the fractal diffusion aggregation control of multiple aggregation centers respectively.The morphology characteristics of soot aggregates are analyzed by fractal dimension and lacunarity.In addition,the fractal characteristics of aggregates generated by cellular automata are discussed.(2)Fractal diffusion aggregation control of differently-sized fine particulate matter in soot based on small world networkIn reality,the fine particulate matter emitted by coal-fired power plants is usually composed of particles with different particle sizes,and its diffusion and movement rules present irregular state.In order to study the diffusion aggregation behavior of fine particulate matter in soot more closely to the real situation,according to the particle size distribution characteristics of fine particulate matter emitted from coal-fired power plants and the long jump characteristics of irregular diffusion movement,a fractal diffusion aggregation control model of fine particulate matter with different particle sizes is established based on small world network for the first time.By changing the two control parameters of small world network and the particle size distribution parameter of fine particulate matter,the fractal diffusion aggregation control of fine particulate matter with different particle sizes is realized.Based on the simulation data,fractal dimension,multifractal spectrum and lacunarity are used to quantitatively describe the fractal characteristics of the soot aggregates formed under the control of small world network.The results show that for fine particulate matter with different particle size distribution,by changing the range parameter and the channel parameter of small world network,the morphology of the central region of soot aggregates become more compact,both of the fractal dimension and the complexity of morphology increase.At the same time,the fractal diffusion aggregation of fine particulate matter with different sizes under external field interference is studied,and the change of the morphology of the aggregates is analyzed.The relevant research in this thesis reveals the fractal diffusion aggregation mechanism of fine particulate matter in soot to some extent,which is of certain reference significance for improving the soot purification processes in coal-fired power plants.(3)Implementation of simulation software for diffusion aggregation of fine particulate matterIn order to better understand the fractal diffusion aggregation process of fine particulate matter in soot,learn the fractal growth theory knowledge intuitively and conveniently,and enhance students’ interest in learning fractal growth theory,the simulation software for diffusion aggregation of fine particulate matter is designed and implemented in this thesis.Based on the mixed programming of Python and MATLAB,the software realizes the fractal diffusion aggregation simulation of fine particulate matter in soot and the fractal diffusion aggregation control of fine particulate matter with different particle sizes based on small world network.By changing the relevant parameter variables,the fractal morphology,fractal dimension and other information of aggregates under different conditions can be obtained directly and conveniently,which effectively improves the visualization,intuition and convenience of learning the fractal growth theory and the diffusion aggregation of fine particulate matter.