Investigation on the Evolution of the Coal Macromolecule in the Process of Combustion With the Molecular Dynamics Method

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Bonan Xu ◽  
Hanhui Jin ◽  
Hanqing Li ◽  
Yu Guo ◽  
Jianren Fan
Keyword(s):  
Molecular Dynamics ◽  
Chemical Reactions ◽  
Coal Combustion ◽  
Ring Opening ◽  
Combustion Process ◽  
Three Dimensional ◽  
Structural Evolution ◽  
Coal Particles ◽  
Dynamics Method ◽  
Detailed Chemical

Abstract It is reported that a three-dimensional cross-linked macromolecular structure with heterogeneous inorganic and organic compositions widely exists in coal particles. The macromolecules usually represent the rank transition of more than 75% of the carbon (C) content of coal particles. In order to know the coal combustion process better, it is important to specifically study the evolution of the coal macromolecule during combustion. In this paper, the structural evolution and the detailed oxidization reactions of a coal macromolecule during the process of combustion are numerically studied with the reactive force field (ReaxFF) molecular dynamics (MD) method, in which the carbon (C) and hydrogen (H) atoms are fully oxidized to CO2 and H2O, respectively. It is found that the coal macromolecule experiences three main stages sequentially: the cleavage, the ring opening, and the oxidation. The heteroatoms (O, N, and S) inside the coal macromolecule are found to play important roles throughout the whole combustion process. The detailed chemical reactions with their occurrence frequencies show that the chemical reactions with O2 mainly occur in C1–4 fragments, and the C1–2–H–O fragments widely exist in the system before they are finally oxidized to CO or CO2.

scholarly journals Verification of three-dimensional mathematical modeling when calculating the combustion of hydrocarbon fuel in an experimental cylindrical furnace enriched with a plasma fuel system

2020 ◽  
Vol 4 (315) ◽  
pp. 96-105
Author(s):  
V. E. Messerle ◽  
◽  
S. A. Bolegenova ◽  
M. K. Bodykbayeva ◽  
A. A. Kuykabayeva ◽  
...  
Keyword(s):  
Coal Combustion ◽  
Thermal Power ◽  
Combustion Process ◽  
Three Dimensional ◽  
Thermal Characteristics ◽  
Hydrocarbon Fuel ◽  
Fuel System ◽  
Two Phase ◽  
Coal Particles ◽  
Kinetics Of

In this work, the operation of the boiler in traditional and plasma-activated conditions is investigated. To test the possibility of modeling the Cinar ICE program with an understanding of the physical mechanism of the processes of electrothermochemical fuel preparation (ETCF) and combustion, a study of coal combustion in an experimental furnace with a thermal power of 3 MW equipped with a plasma fuel system was carried out. To study the combustion process of an air mixture that had undergone preliminary plasma preparation for combustion, one-dimensional plasma-coal and three-dimensional computer programs Cinar ICE were used, which study in detail the mechanism of the kinetics of thermochemical exchange in a two-phase flow, where the plasma fuel source is located, and the exact geometry of the furnace, and the kinetics of the process сombustion of coal particles. As a result of calculations, the distribution of temperature, velocity of gas and particles in the process of ETCPT, the concentration of gas-phase mixtures, the concentration of carbon and the degree of gas contamination in the remainder of alloyed coal were determined. It was found that the plasma activation of combustion affects the thermal characteristics of the Torch, the mechanical non-combustible fuel residue and the concentration of nitrogen oxide at the outlet from the furnace. It has been proven that when simulating coal combustion, it is possible to achieve an effective description of the process using the Cinar ICE program.

Viscosity Prediction of Water-Based Silver Nanofluid Using Equilibrium Molecular Dynamics

2016 ◽  
Author(s):  
Qianli Ma ◽  
Haisheng Fang
Keyword(s):  
Molecular Dynamics ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Weight Fraction ◽  
Nanoparticle Concentration ◽  
Nanoparticle Aggregation ◽  
Ink Jet ◽  
Jet Printing ◽  
Viscosity Prediction ◽  
Dynamics Method

Nanofluids containing silver (Ag) nanoparticles have been used in three dimensional ink-jet printing (3DP) in recent years. Rheological properties of the nanofluids, for example, viscosity, play significant roles during the application. In this paper, viscosity of Ag-water nanofluid has been predicted using the equilibrium molecular dynamics method. The influencing factors of the viscosity, including temperature, nanoparticle size, nanoparticle concentration and nanoparticle aggregation, have been investigated. By screening the existing water models, TIP4P/2005 model is found the most suitable for viscosity calculation under the temperature range. The weight fraction of the nanoparticles, which proves more appropriate, is used during the study of the concentration effect instead of volume fraction. The results show that the viscosity of the nanofluid goes up by decreasing temperature or increasing nanoparticle concentration. Furthermore, as the nanoparticles get smaller, or aggregate, the viscosity increases slightly.

scholarly journals The anomalous behavior of liquids in three-dimensional and two-dimensional spaces

2021 ◽  
Vol 13 (2) ◽  
pp. 111-118
Author(s):  
Yury D. Fomin ◽  
◽  
Elena N. Tsiok ◽  
Anton B. Teslyuk ◽  
Valentin N. Ryzhov ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Space Dimension ◽  
Three Dimensional ◽  
Anomalous Behavior ◽  
Two Dimensional ◽  
Step Width ◽  
Density Anomaly ◽  
2D System ◽  
Potential Parameters ◽  
Dynamics Method

Using a molecular dynamics method water-like anomalies in a core-softened system depending on the potential parameters and space dimension were investigated. We have examined the anomalies of density, diffusion and structure and have shown that the sequence of anomalous regions cardinally depends on the repulsive step width and space dimension. Thus, in a three-dimensional (3D) system with small values of the step width the sequence of anomalous regions is the same as in water, whereas in a two-dimensional (2D) system – as in liquid silica. With an increase in the step width, an inversion of the regions of the diffusion anomaly and of the density anomaly is observed. Such an unusual sequence of anomalous regions different from water and liquid silica is exclusively caused by the step width and does not depend on the space dimension.

scholarly journals Coal combustion modelling in a frontal pulverized coal-fired boiler

2018 ◽  
Vol 46 ◽  
pp. 00010
Author(s):  
Paweł Madejski
Keyword(s):  
Coal Combustion ◽  
Gas Flow ◽  
Combustion Process ◽  
Three Dimensional ◽  
Pulverized Coal ◽  
Operational Conditions ◽  
Power Plant Boiler ◽  
Combustion Modelling ◽  
Flow Through ◽  
Plant Boiler

The paper presents results of numerical modelling of pulverized coal combustion process in the coal-fired boiler. In the numerical model, coal combustion process includes particle heating, devolatilization, char combustion, as well as turbulent flow and radiative heat transfer was modelled. Presented modelling results were carried out using the Open Source CFD code - Code_Saturne created and developed by EDF R&D and were used to study the combustion of coal in power plant boiler with the objective of simulating the operational conditions and identifying factors of inefficiency. The behaviour of the flow of air and pulverized coal through the burners was modelled, and the three-dimensional flue gas flow through the combustion chamber and heat exchangers was reproduced in the simulation.

CHAOTIC MOTION OF TWO MOLECULES IN A BOX

1993 ◽  
Vol 03 (05) ◽  
pp. 693-710 ◽  
Author(s):  
M. HASEGAWA ◽  
K. NANBU ◽  
K. IWATA
Keyword(s):  
Molecular Dynamics ◽  
Chaotic Motion ◽  
Three Dimensional ◽  
Physical Space ◽  
Temporal Behavior ◽  
Initial Condition ◽  
Remarkable Feature ◽  
Higher Dimensional ◽  
Physical Spaces ◽  
Dynamics Method

Motion of two molecules in a specularly reflecting box is analyzed for two-, three- and higher-dimensional cases. The temporal behavior of this nonlinear system is pursued by the molecular-dynamics method. The distributions of molecular velocities and collisional points are examined for two- and three-dimensional cases. Strange patterns, which depend on the initial condition of the system, have been found in velocity and physical spaces. The reason of this remarkable feature is discussed. The energy distribution function is also examined for a molecule in chaotic motion. The distribution depends on the dimension of the physical space. It can be described by the beta distribution, which holds in general for any dimension.

The Investigation of Nanowires Properties in the Process of Deformation

2018 ◽  
Vol 30 ◽  
pp. 34-38
Author(s):  
Mikhail D. Starostenkov ◽  
Oleg V. Yashin ◽  
Alexander V. Yashin
Keyword(s):  
Molecular Dynamics ◽  
Crystal Lattice ◽  
Three Dimensional ◽  
Cubic Symmetry ◽  
Pair Potentials ◽  
Deformation Processes ◽  
Three Dimensional Models ◽  
Axial Stretching ◽  
Fcc Metal ◽  
Dynamics Method

In this work, the authors attempted to consider the influence of the geometry of the crystal lattice on the properties of nanowires, which manifest themselves in the process of uni-axial stretching. This work summarizes and systematizes the results of previous studies of the authors. The first group of samples – are typical FCC metal – Ni3Al. For these nanowires, deformation processes in directions with different packing densities of atoms <100>, <110> and <111> were investigated. The second material group studied was an alloy with the non-cubic symmetry of the element cell CuAu I. Correspondingly, this sample was examined under deformation in directions corresponding to different lengths of the sides of the unit cell, <001> and <010>. All the investigations described in this paper were carried out by molecular dynamics method on three-dimensional models using the Morse's pair potentials.

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