Journal articles: 'Coal liquefaction Mathematical models'

1

Wu, Chunlai, Shidong Shi, Xiaosu Zhu, and Ming Zhou. "A mathematical model for tubular reactors in direct coal liquefaction." Energy 18, no. 8 (August 1993): 815–25. http://dx.doi.org/10.1016/0360-5442(93)90060-q.

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2

Bongers, Geoffrey D., John S. T. Chan, W. Roy Jackson, Antonio F. Patti, Marc Marshall, and Pavla Meakin. "Reactions of montan wax fractions as models of brown coal liquefaction." Fuel 75, no. 10 (August 1996): 1161–66. http://dx.doi.org/10.1016/0016-2361(96)00078-6.

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3

Williams, B. C., and J. T. McMullan. "Development of computer models for the simulation of coal liquefaction processes." International Journal of Energy Research 18, no. 2 (March 1994): 117–22. http://dx.doi.org/10.1002/er.4440180209.

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Ji, Jie, Hui Yao, Di Wang, Zhi Suo, Luhou Liu, and Zhanping You. "Properties of Direct Coal Liquefaction Residue Modified Asphalt Mixture." Advances in Materials Science and Engineering 2017 (2017): 1–11. http://dx.doi.org/10.1155/2017/2473283.

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The objectives of this paper are to use Direct Coal Liquefaction Residue (DLCR) to modify the asphalt binders and mixtures and to evaluate the performance of modified asphalt mixtures. The dynamic modulus and phase angle of DCLR and DCLR-composite modified asphalt mixture were analyzed, and the viscoelastic properties of these modified asphalt mixtures were compared to the base asphalt binder SK-90 and Styrene-Butadiene-Styrene (SBS) modified asphalt mixtures. The master curves of the asphalt mixtures were shown, and dynamic and viscoelastic behaviors of asphalt mixtures were described using the Christensen-Anderson-Marasteanu (CAM) model. The test results show that the dynamic moduli of DCLR and DCLR-composite asphalt mixtures are higher than those of the SK-90 and SBS modified asphalt mixtures. Based on the viscoelastic parameters of CAM models of the asphalt mixtures, the high- and low-temperature performance of DLCR and DCLR-composite modified asphalt mixtures are obviously better than the SK-90 and SBS modified asphalt mixtures. In addition, the DCLR and DCLR-composite modified asphalt mixtures are more insensitive to the frequency compared to SK-90 and SBS modified asphalt mixtures.

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Kirca, V. S. Ozgur, and B. Mutlu Sumer. "Sinking Failure of Drag Embedment Anchors Due to Wave-Induced Seabed Liquefaction." International Journal of Ocean and Coastal Engineering 01, no. 04 (December 2018): 1850006. http://dx.doi.org/10.1142/s2529807018500069.

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This paper presents the results of an integrated mathematical modeling exercise for sinking of Drag Embedment Anchors (DEA) in a seabed liquefied by waves. The mathematical model consists of three elements (sub-models): (1) Mathematical model for residual liquefaction under waves; (2) Mathematical model for sinking of DEAs in the liquefied soil; and (3) Mathematical model for upward progression of compaction front in the post-liquefaction stage. The study demonstrates the implementation of the model with reference to a selected group of real-life DEAs. The results generally show that the ultimate sinking depths of DEAs are rather large (tens of centimeters short of the liquefaction depth), and accordingly, the ultimate sinking times of DEAs are rather small (O(10[Formula: see text]min)) as a result of the massive weights of these anchors. The paper presents a parametric study carried out in a systematic way to understand the influence of parameters such as the relative density of soil, the soil depth, and the grain size on the end results.

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Sato, Shimio. "Remarks on rate analysis of coal liquefaction using kinetic models involving multimolecular reaction paths." JOURNAL OF CHEMICAL ENGINEERING OF JAPAN 23, no. 2 (1990): 249–50. http://dx.doi.org/10.1252/jcej.23.249.

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7

Şimşek, Emir Hüseyin, Fatih Güleç, and Hakan Kavuştu. "Application of Kalman filter to determination of coal liquefaction mechanisms using discrete time models." Fuel 207 (November 2017): 814–20. http://dx.doi.org/10.1016/j.fuel.2017.06.004.

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8

Saxena, S. "Mathematical models for fluidized-bed coal combustion and sulfur retention." Energy 13, no. 7 (July 1988): 557–607. http://dx.doi.org/10.1016/0360-5442(88)90011-4.

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9

Yang, Lanhe. "Nonlinear coupling mathematical models on percolation-patterned underground coal gasification." International Journal of Energy Research 29, no. 15 (2005): 1331–53. http://dx.doi.org/10.1002/er.1067.

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Trokhymets, Mykola, Vira Maltseva, Yehor Vialushkin, Volodymyr Antonchik, Tetiana Moskalova, and Maryna Polushyna. "Method and equipment for the safe development of preparatory workings in the gas-bearing coal seams." E3S Web of Conferences 109 (2019): 00102. http://dx.doi.org/10.1051/e3sconf/201910900102.

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The article describes a method and equipment for the safe development of preparatory working on a gas-bearing, outburst hazardous coal seam by a heading machine. The described method significantly prevents the gas emission during mining operations. Determination of the amount of degassing and relief wells is performed according to the given in article mathematical formulas. This ensures a significant increase in the level of safety processing the preparatory roadway on a gas-bearing, prone to outbursts coal seam by a heading machine. Due to this, the speed of conducting excavation increases and the cost of mining is reduced. The proportionality coefficients of the mathematical models were determined. Mathematical models are used to calculate the number of relief and degassing wells, which are drilled during the impulse hydraulic loosing of the nearby part of the coal seam. Also the duration of liquid injection into a coal seam is also determined. Mathematical models for calculating the number of injection, unloading and degassing boreholes can be used in development of the passports for conducting preparatory workings on a gas-bearing, prone to outburst coal seam by a heading machine with a preliminary impulse hydraulic loosing of the nearby part of a coal seam.

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11

Miranda, Lima Rose. "Emerging iron-making technologies — their coal consumption using simple mathematical models." Fuel 72, no. 5 (May 1993): 716. http://dx.doi.org/10.1016/0016-2361(93)90669-s.

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12

Yang, L. "Non-linear coupling mathematical models of percolation-patterned underground coal gasification." Energy 29, no. 2 (February 2004): 211–34. http://dx.doi.org/10.1016/j.energy.2003.08.012.

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Kachurin, A. N., V. K. Demin, D. N. Shkuratskyi, and P. I. Karnachev. "MATHEMATICAL DEGASATIONMODELS OF COAL BANDS, RELEASED INTO MINING FACES." News of the Tula state university. Sciences of Earth 4, no. 1 (2019): 249–58. http://dx.doi.org/10.46689/2218-5194-2019-4-1-249-258.

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Mathematical models have been developed for the degassing of roofing coal packs discharged into treatment faces when mining powerful flat coal seams with one face. It was shown that when a powerful coal seam is excavated to full capacity with one face with the release of a sub roofing pack, methane release from the sub roofing pack of a disturbed structure will be formed according to the laws of gas motion in fractured-porous sorbing media.

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14

Jing, Xing Peng. "Reservoir Pressure of Coal-Bed Methane Prediction Research Based on Analysis Method by Neural Net-Work." Advanced Materials Research 756-759 (September 2013): 4758–62. http://dx.doi.org/10.4028/www.scientific.net/amr.756-759.4758.

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In Order to Achieve Accurate Quantitative Results of Parameters for Reservoir Pressure of Coal-Bed Methane, Neural Network Prediction Analytic Method is Adopted to Predict the Reservoir Pressure of Coal-Bed Methane. the Main Controlling Factors such as Conformation Stress, Buried Depth, in-Situ Stress and Permeability are Investigated. Mathematical Models of Neural Network of Reservoir Pressure of Coal-Bed Methane of Mathematical Analysis and System Architecture are Established; Taking the Qinshui Basin Coal Seam as Example to Forecast and use Reservoir Pressure of Coal-Bed Methane. Projections Show that: the use of Neural Network Prediction of Reservoir Pressure of Coal-Bed Methane is Feasible; Neural Network Method Makes up a Mathematical Point of Linear and Regularity in Order to Solve the Non-Linear Complex Relationship between the Input and Output Parameter Variables.

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15

Vedernikova, Tatyana, and Artur Vronskiy. "Comparative Analysis of Models of the Combustion Process of Coal Dust in a Turbulent Flow of a Torch of a Charcoal Boiler." System Analysis & Mathematical Modeling 3, no. 3 (December 16, 2021): 213–26. http://dx.doi.org/10.17150/2713-1734.2021.8(3).213-226.

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This article provides an overview of existing turbulence models. The scheme of combustion of pulverized coal fuel, the construction of a pulverized coal boiler unit and the process of burning coal in the furnace of a boiler unit BKZ-420-140 are considered. We analyzed the existing turbulence models and selected the most optimal mathematical model to study the combustion process of pulverized coal fuel in order to increase the efficiency of the CHPP.

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Heng, Li Jun, Kun Jie Duan, and Chang Zheng He. "Study on Mathematical Simulation of Nitrogen Oxides (NO_x) Formation of Coal-Fired Boiler." Advanced Materials Research 354-355 (October 2011): 319–24. http://dx.doi.org/10.4028/www.scientific.net/amr.354-355.319.

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There exist certain limitations to research the law and influence factors of the nitrogen oxides formation only with the help of field tests, because the nitrogen oxides formation of the boiler is influenced by various factors. The flow, combustion mathematical models interrelated and so on are established taking the 410t/h boiler fired tangentially as a prototype by the use of the fluent software. All the mathematical models are verified and modified with the aid of routine field test data, and the accuracy and reliability of the mathematical models are improved. Then NOx formation performance is stimulated in allusion to the influence factors without field test conditions. The mathematical simulation results show that mathematical models can provide a sufficient theoretical basis to analyze accurately combustion and NOx formation law in furnace, and the deficiencies of field tests have been made up.

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17

Wan, Wen Jun, Zhi Yuan Fan, Wei Jian Huang, and Shi He Chen. "Dynamic Characteristics and Mathematical Models of Filled Level for Ball Mills with Double Inlets and Outlets." Advanced Materials Research 1008-1009 (August 2014): 988–94. http://dx.doi.org/10.4028/www.scientific.net/amr.1008-1009.988.

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Ball mills with double inlets and outlets (BMDIO) are widely equipped in milling systems of thermal power plants because of BMDIOs’ vantage on being able to pulverize various raw coal. In this paper, dynamic characteristics of mill’s coal level were studied by pulverizing coal mechanism analysis. Furthermore, models for filled level of mill were obtained with mathematical Equations. The nonlinear, strong coupling and large lag features of BMDIO’s dynamic characteristics were demonstrated by the model for level of materiel constructed in this paper. And, the model would be become the available theory basis for the calculation of pulverized coal into furnace and design of combustion in fossil-fired thermal unit.

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Martínez, Manuel, Grony Garbán, Adriana Gamboa, and Ricardo Rodríguez. "Conversión de Carbón a Productos Líquidos mediante Despolimerización Asistida por Solventes: una Revisión de los Fundamentos y Avances en la Región." Revista Científica y Tecnológica UPSE 4, no. 1 (May 25, 2017): 39–46. http://dx.doi.org/10.26423/rctu.v4i1.240.

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En la búsqueda de transformar el carbón mineral en materiales más sencillos, se han ensayado varios procedimientos químicos de despolimerización (licuefacción, pirólisis, hidrogenación). El tratamiento con solventes luce como una alternativa que tiene la ventaja de requerir bajas temperaturas. Varios modelos macromoleculares han sido propuestos para explicar la interacción solvente-carbón. Se presenta una exposición de las características y antecedentes de la despolimerización, su aplicación en carbones y la potencialidad de la técnica para diversificar la industria carbonífera en los países de la región.Abstract Looking for the coal conversion into simpler materials, several procedures have been assayed (liquefaction, pyrolysis, and hydrogenation). The solvent treatment of coal looks as an alternative with the advantage of requiring low temperatures. Several macromolecular models have been proposed to explain the solvent-coal interaction. In this study, a comprehensive review of coal depolymerization is exposed, its feasibility and the potential of the technology to diversify the coal-bearing industry in the countries of the region.

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Slavinskaya, N. A., U. Riedel, V. E. Messerle, and A. B. Ustimenko. "Chemical Kinetic Modeling in Coal Gasification Processes: an Overview." Eurasian Chemico-Technological Journal 15, no. 1 (December 24, 2012): 1. http://dx.doi.org/10.18321/ectj134.

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<p>Coal is the fuel most able to cover world deficiencies in oil and natural gas. This motivates the development of new and more effective technologies for coal conversion into other fuels. Such technologies are focused on coal gasification with production of syngas or gaseous hydrocarbon fuels, as well as on direct coal liquefaction with production of liquid fuels. The benefits of plasma application in these technologies is based on the high selectivity of the plasma chemical processes, the high efficiency of conversion of different types of coal including those of low quality, relative simplicity of the process control, and significant reduction in the production of ashes, sulphur, and nitrogen oxides. In the coal gasifier, two-phase turbulent flow is coupled with heating and evaporation of coal particles, devolatilization of volatile material, the char combustion (heterogeneous/porous oxidation) or gasification, the gas phase reaction/oxidation (homogeneous oxidation) of gaseous products from coal particles. The present work reviews literature data concerning reaction kinetic modelling in coal gasification. Current state of related kinetic models for heterogeneous/homogeneous oxidation of coal particles, included plasma assisted, is reviewed.</p>

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Vasileva, Yelena, Aleksandr Nevedrov, and Sergey Subbotin. "Development and Performance Evaluation of a Computer Program Based on Neural Network Mathematical Models for Forecasting By- Product Yield." E3S Web of Conferences 174 (2020): 03023. http://dx.doi.org/10.1051/e3sconf/202017403023.

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Process performance of coking plants are based on data on the yield of by-products of coking coal and their quality, therefore, much attention is paid to the issues of their analysis. In view of the complexity and insufficient knowledge of the relationship between these parameters, mathematical modeling of this dependence using neural networks is of great interest. Based on a mathematical analysis of experimental data on the quality indicators of coal, coal concentrates and the by-product yield, neural network mathematical models have been developed to forecast the parameters under study. The neural network is based on the Ward’s network. Based on the results of the research, the application “Intelligent Information System for Forecasting By-product Yield” was created, which implements neural networks [1]. The relative forecasting error for the parameter “coke” is 0.64±0.23%, “coal tar” is 19.53±5.25%, “crude benzene” is 10.02±2.83%, and “coke gas” is 5.11±1.34%. A comparative analysis of the data obtained using the developed design method is carried out, with the simulation results using existing methods, as well as with the production values of by-products yield.

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21

Zhao, Wei, Yuanping Cheng, Zhejun Pan, Kai Wang, and Shimin Liu. "Gas diffusion in coal particles: A review of mathematical models and their applications." Fuel 252 (September 2019): 77–100. http://dx.doi.org/10.1016/j.fuel.2019.04.065.

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22

Belikov, A. S., N. N. Biliaiev, V. V. Biliaieva, and O. V. Berlov. "Assessment of the dust pollution level in the workspaces by the methods of mathematical modeling." Geo-Technical mechanics, no. 152 (2020): 218–25. http://dx.doi.org/10.15407/geotm2020.152.218.

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Coal dust leakage from coal stacks leads to intensive contamination of the working areas. Therefore, determining level of air pollution near the coal piles for various meteorological situations, when new coal piles are arranged, is an important applied problem. For practice, it is necessary to have quick-calculating mathematical models whiсh take into account the most significant physical processes impacting on formation of contamination zones near the coal piles. Today, to predict the level of air pollution at dust leaking from the coal stacks, the normative technique OND-86 or the Gauss model is used. These forecasting methods make it possible to quickly calculate the contamination zones, but they do not take into account geometric shape of the coal stack and unevenness of the velocity field near it. The subject of this research was creation of a mathematical model for predicting the level of air pollution near coal piles with taking into account the aerodynamics of air flows around them. The purpose of the work was to develop a set of numerical models for quick calculation of the level of air pollution at coal dust leaking from the coal piles with taking into account the uneven emission of dust from different areas of the stack surface. The modelling equations are the three-dimensional mass transfer equation (Marchuk's model) and the three-dimensional equation for the velocity potential. The Marchuk's model allows taking into account rate of the coal dust particles settling, parameters of turbulent diffusion and uneven air flow rate near the coal pile. The Dirac delta function is used for modelling coal dust leaking from various sections of the coal pile. For the numerical solution of the mass transfer equation, a difference splitting scheme is used. On the basis of the three-dimensional equation for the velocity potential, an uneven velocity field near the coal pile is determined. The Richardson method is used for numerical solution of the three-dimensional equation for the velocity potential. An algorithm for solving the problem of calculating a level of contamination of working areas near a coal pile is considered. The description of the structure of the created complex of computer programs is given.

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Wen, Guojun, Haojie Liu, Hongbo Huang, Yudan Wang, and Xinyu Shi. "Meshless method simulation and experimental investigation of crack propagation of CBM hydraulic fracturing." Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles 73 (2018): 72. http://dx.doi.org/10.2516/ogst/2018074.

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For simulating CoalBed Methane (CBM) hydraulic fracturing using 3-D meshless method, this paper analyzed the hydraulic fracturing mechanism and cracking form for coal rock and established the geometric and mathematical models of hydraulic fracturing propagation in coal rock in terms of the Hillerborg model on crack opening displacement theory. With the theoretical basis of hydromechanics, the formulas for calculating hydraulic pressure inside the fracture by numerical simulation were deduced from the analysis on this fluid-structure interaction problem. The geometric and mathematical models established above were described by 3-D meshless Galerkin (EFG, Element-Free Galerkin) method and compiled into the numerical simulation program using VB and FORTRAN programming language to simulate the fracture propagation for an actual coal rock sample with a drilling hole as an example. Then the physical simulation experiment of hydraulic fracturing propagation of coal seam was conducted on the same coal rock sample. Through the direct observation with naked eyes and detection by advanced instruments of ESEM and Micro-CT, the shape and parameters of cracks on the surface of and inside the coal rock sample were achieved, which indicated that experimental results are reasonably consistent with numerical simulation results.

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Sun, Yuantian, Guichen Li, and Junfei Zhang. "Developing Hybrid Machine Learning Models for Estimating the Unconfined Compressive Strength of Jet Grouting Composite: A Comparative Study." Applied Sciences 10, no. 5 (February 28, 2020): 1612. http://dx.doi.org/10.3390/app10051612.

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Coal-grout composites were fabricated in this study using the jet grouting (JG) technique to enhance coal mass in underground conditions. To evaluate the mechanical properties of the created coal-grout composite, its unconfined compressive strength (UCS) needed to be tested. A mathematical model is required to elucidate the unknown nonlinear relationship between the UCS and the influencing variables. In this study, six computational intelligence techniques using machine learning (ML) algorithms were used to develop the mathematical models, which includes back-propagation neural network (BPNN), random forest (RF), decision tree (DT), support vector machine (SVM), k-nearest neighbors (KNN), and logistic regression (LR). In addition, the hyper-parameters in these typical algorithms (e.g., the hidden layers in BPNN, the gamma in SVM, and the number of neighbor samples in KNN) were tuned by the recently developed beetle antennae search algorithm (BAS). To prepare the dataset for these ML models, three types of cementitious grout and three types of chemical grout were mixed with coal powders extracted from the Guobei coalmine, Anhui Province, China to create coal-grout composites. In total, 405 coal-grout specimens in total were extracted and tested. Several variables such as grout types, coal-grout ratio, and curing time were chosen as input parameters, while UCS was the output of these models. The results show that coal-chemical grout composites had higher strength in the short-term, while the coal-cementitious grout composites could achieve stable and high strength in the long term. BPNN, DT, and SVM outperform the others in terms of predicting the UCS of the coal-grout composites. The outstanding performance of the optimum ML algorithms for strength prediction facilitates JG parameter design in practice and could be the benchmark for the wider application of ML methods in JG engineering for coal improvement.

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25

Wei, Jianping, Junzhao Zhang, Zhihui Wen, Libo Zhang, Yongjie Ren, and Leilei Si. "Natural Frequency of Coal: Mathematical Model, Test, and Analysis on Influencing Factors." Geofluids 2022 (May 31, 2022): 1–13. http://dx.doi.org/10.1155/2022/7891894.

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The difficulty in enhancing the low permeability of deep coal seams is the key problem restricting gas extraction. The technology of coal rock resonance and permeability enhancement excited by vibration wave is hailed as a new technology to enhance coal seam permeability. In particular, the effect of resonance and permeability enhancement is remarkable when the excitation frequency is exactly the same as the natural frequency of coal. In order to promote the application of the technology, the first step is to explore the variation characteristics of coal natural frequency and its influencing factors. In this study, two mathematical models of coal natural frequency were established, and the variations and influencing factors of coal natural frequency were discussed through an experiment on the natural frequency of coal. The results show that coal vibration has multiorder natural frequency which grows with the increase of the order. In addition, the natural frequency of coal is closely related to its elastic modulus, density, size, mass, stiffness, and other physical and mechanical parameters. The larger the coal size and mass are, the lower the natural frequency would be. The natural frequency parallel to the bedding plane is higher than that perpendicular to the bedding plane. For the saturated coal sample, moisture changes its density and reduces its elastic modulus. Consequently, its natural frequency is lower than that of the dried coal sample. The difference of organic matter and mineral content coal of different rank affects the physical and mechanical properties of coal, which leads to the difference in natural frequency of different-rank coals. The natural frequencies of different-rank coal show bituminous > anthracite > lignite. The natural frequencies of coal samples under different influencing factors are all tens of Hz. Thus, the vibration excitation of coal under the low-frequency condition is the focus of future research. The study can provide a theoretical basis for the technology of coal resonance and permeability enhancement excited by vibration wave.

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Myszograj, Sylwia, and Magdalena Wojciech. "Mathematical modelling of waste activated sludge thermal disintegration." ITM Web of Conferences 23 (2018): 00027. http://dx.doi.org/10.1051/itmconf/20182300027.

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Chemical Oxygen Demand (COD) solubilisation was used to evaluate the impact of thermal pretreatment on the transfer of sewage sludge from particulate to soluble phase. It was gathering the experimental data needed for building of empirical mathematical model describing the relation between applied temperature and time and rate of COD solubilisation and degradation. In view of repeated measurements, in order to describe the relationship between changes in the fraction of dissolved COD and the time and temperature, mixed models have been adopted where by fixed factor measurement conditions have been adopted: time and temperature, while the random factor changes the characteristics of waste activated sludge. Linear and logistic nonlinear mixed models were analyzed. The tests demonstrated that all variables are statistically significant in assessing their impact on the efficiency of liquefaction of sludge. On the basis of the estimated model, the temperature rise of 10°C increases degree of disintegration 1.7% above the average treatment time for 0.5h, by 2.6% for 1 hour, and by 3.9% for 2h. COD values decrease between 3 to 23% at temperatures in the range of 55 to 115°C. At higher temperatures COD was reduced in the range of 32 to 44%. Disintegration time did not have the significant impact on the degradation effect.

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KACHURIN, Nikolai, Galina STAS, and Alexander KACHURIN. "DYNAMICS OF GAS EMISSION FROM EXPOSED SURFACE OF GAS-BEARING COAL SEAMS HAVING MEDIUM THICKNESS." Sustainable Development of Mountain Territories 13, no. 3 (September 30, 2021): 441–48. http://dx.doi.org/10.21177/1998-4502-2021-13-3-441-448.

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The goal of the research was to clarify the regularities of the dynamics of gas release from the surface of the outcrop of the developed coal seam. The main research methods were theoretical methods of mathematical physics and non-equilibrium thermodynamics. Gas-bearing coal seams are usually mined underground. When driving development workings, outcropping surfaces of gas-bearing coal seams appear and gases in the seams under excessive pressure are released into the atmosphere of the mine workings. Gas-bearing coal seams are usually mined underground. When driving preparatory workings, surfaces of outcropping of gas-bearing coal seams arise and gases that are in the seams under excessive pressure are released into the atmosphere of the mine workings. The most important gas-dynamic characteristic of this process is the rate of gas release, which represents the volume of gases released from a unit area of exposure of a coal seam per unit of time. A generalized law of resistance for gas filtration in a rock mass is recommended, and a fairly rigorous thermodynamic substantiation is given. It is shown that the densities of gas mass flows in accordance with the postulate of their linear relationship with the driving forces are determined by the Onsager relation. The results obtained and their discussion is presented. Mathematical models are proposed for engineering calculations of the dynamics of methane release from the outcropping surface of medium-thick coal seams. The error of the adopted approximations does not exceed 3%. The intensity of methane release is directly related to the planogram of work in the working face. Analysis of this dependence indicates that during the extraction cycle, methane release increases due to an increase in the area of the gas-release surface. The main conclusions are as follows: mathematical modeling of the processes of gas movement in a porous sorbing medium using approximate mathematical models representing linearized equations of mathematical physics; the regularities of the dynamics of the rate of gas release from the surface of the outcrop of a gas-bearing coal seam is the theoretical basis for the mathematical description of the process of gas release; the use of a linearized hyperbolic filtration equation most accurately describes the processes of methane release from the outcropping surface of mined coal seams.

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Qin, Tao, Kai Yun Zhang, and Hong Lei Liu. "The Comparative Study on the Gassy Coal Thermal-Fluid-Solid Coupling and no Coupling." Advanced Materials Research 1010-1012 (August 2014): 1494–97. http://dx.doi.org/10.4028/www.scientific.net/amr.1010-1012.1494.

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In order to study the mechanism of dynamic disaster on gassy coal and realize the monitoring and prediction, with the Didao mine as an example, this paper set up the thermal fluid-solid three field couple mathematical models of driving face and comparative analyzed the mathematical models between couple and not couple by using the software comsol. The study result shows that it has a swift response, a close connection and a shorter time in the formation of o-ring, when it is the thermal fluid-solid three field couple.

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Chen, Chao, De Gang Ouyang, Zhong Hua Song, and Ming Hui Li. "Numerical Simulation on Thawing Time of Frozen Coal in Tram." Advanced Materials Research 516-517 (May 2012): 360–63. http://dx.doi.org/10.4028/www.scientific.net/amr.516-517.360.

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In this paper, numerical simulation on thawing of frozen coal in tram of coke-oven plant was carried out. Simplified physical and mathematical models were developed and calculated, based on which the rules of coal thawing were obtained. By analyzing effects of wind temperature and wind speed on thawing, thawing time of frozen coal under different conditions was calculated, which can provide reference for accurate design and actual operating.

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Xu, Gang, Meng Hao, and Hongwei Jin. "Study on Fluid-solid Coupling Mathematical Models and Numerical Simulation of Coal Containing Gas." IOP Conference Series: Earth and Environmental Science 113 (February 2018): 012138. http://dx.doi.org/10.1088/1755-1315/113/1/012138.

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Su, H. K., Z. Y. Li, L. H. Gong, W. P. Zhu, M. M. Zhang, and Q. M. Jia. "Dynamic simulation of the cool down process of double-pressure helium liquefaction cycle." IOP Conference Series: Materials Science and Engineering 1240, no. 1 (May 1, 2022): 012111. http://dx.doi.org/10.1088/1757-899x/1240/1/012111.

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Abstract A double-pressure helium liquefaction cycle, which consists of two compressors, six heat exchangers, two expanders and several valves, was proposed in this paper. The thermodynamic parameters of the process were calculated and analyzed. The mathematical models of the above-mentioned key equipment are established, and the cool down process of the helium refrigerator is dynamically simulated. By adjusting the parameters of each valve in the process, the working process of the compressor was simulated, and the cool-down process of heat exchangers and the expanders was obtained and analyzed. Finally the stable refrigeration capacity was obtained. The simulation of the dynamic process has a great guiding role for the actual experimental process afterwards.

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Duan, Jon, G. Cornelis van van Kooten, and A. T. M. Hasibul Islam. "Calibration of Grid Models for Analyzing Energy Policies." Energies 16, no. 3 (January 23, 2023): 1234. http://dx.doi.org/10.3390/en16031234.

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Intermittent forms of renewable energy destabilize electricity grids unless adequate reliable generating capacity and storage are available, while instability of hybrid electricity grids and cost fluctuations in fossil fuel prices pose further challenges for policymakers. We examine the interaction between renewable and traditional fossil-fuel energy sources in the context of the Alberta electricity grid, where policymakers seek to eliminate coal and reduce reliance on natural gas. We develop a policy model of the Alberta grid and, unlike earlier models, calibrate the cost functions of thermal generation using positive mathematical programming. Rather than employing constant average and marginal costs, calibration determines upward sloping supply (marginal cost) functions. The calibrated model is then used to determine an optimal generation mix under different assumptions regarding carbon prices and policies to eliminate coal-fired capacity. Results indicate that significant wind capacity can enter the Alberta grid if carbon prices are high, but that it remains difficult to eliminate reliable baseload capacity. Adequate baseload coal and/or natural gas capacity is required, which is the case even if battery storage is allowed into the system. Further, significant peak-load gas capacity will also be required to backstop intermittent renewables.

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Makoba, Mmoloki, Daniel Erich Botha, Mpho Thabang Rapoo, László Zsolt Szabó, Thapelo Shomana, Paul Serban Agachi, and Edison Muzenda. "A Review on Botswana Coal Potential from a Pyrolysis and Gasification Perspective." Periodica Polytechnica Chemical Engineering 65, no. 1 (July 6, 2020): 80–96. http://dx.doi.org/10.3311/ppch.12909.

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Coal pyrolysis and gasification are promising options for the future of Botswana as the country has large coal reserves with severe limitations in terms of export options. Coal characterization facilities will be required in order to harness its full potential and methods such as proximate, ultimate and chemical structure analysis (FTIR, Raman spectroscopy and X-ray diffraction techniques) were investigated. The paper presents a brief history of pyrolysis and gasification, typical types of the reactors as well as factors that influence product selection for Botswana coal. Coal pyrolysis and gasification are complex processes and it is difficult to define the mechanisms of product formation. However, there are several kinetic models that are relevant to the sub-bituminous coal of Botswana which were proposed by researchers to describe the formation of the compounds and mathematical models that were validated by other researchers on mass and heat transfer as also presented herein.

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A, Starovoit, Sorokin Ye, and Shumeiko T. "Analytical determination of the rational amount of low-alumina coal of grade DG in the charge for coke production the specified properties." Theory and practice of metallurgy 1, no. 1 (January 21, 2019): 93–96. http://dx.doi.org/10.34185/tpm.1.2019.12.

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In this paper we consider mathematical calculations for the study of optimal content of fractions of weakly-coagulated coal of a certain density, which is part of the coal charge for coking. The methods of mathematical calculations, which were carried out with the help of the method of PFE 22 and TSKOP, are presented. As a result of the analysis, the authors found that the main factors that affect the quality of the final product are the granulometric composition and the degree of its metamorphism. On the basis of the calculations, the authors found that the obtained linear models of PFE 22 are inadequate and are not acceptable for their further use. In this way, the article is devoted to a detailed study of mathematical calculations, namely, the regression equation and response surfaces obtained with the help of the TsKOP method, which showed in which optimum quantity it is possible to use a fraction of poorly sparing coal to produce the required quality coke.

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Do, An Manh, Dung Tien Nguyen, Thao Thanh Thi Nguyen, Huan Hoang Nguyen, Anh Tuan Pham, and Tuan Ba Dinh. "Establishing mining deposit groups and exploration grid patterns in the Binh Minh Coal Mine, Quang Ninh Province by using Geo-mathematical models." Journal of Mining and Earth Sciences 63, no. 2 (April 30, 2022): 15–30. http://dx.doi.org/10.46326/jmes.2022.63(2).02.

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Binh Minh mine is one of the major mines of the Quang Ninh coal basin and contributes significantly to the country's annual coal reserves. Based on collected data, the paper has synthesized and processed geological data especially applied mathematical methods to identify research objects and describe quantitative properties. The results indicate that the coal seams belong to the group of medium and thick seams, the thickness of the entire seam changes complicatedly, with variable thickness are unstable, its coefficient of variation (Vm = 53.5 and 97.7%); the variable slope angle is stable (Vα = 29.4 and 44.1%); coal ash level is relatively stable (VA = 56.1 and 74.6%). Coal seams in the group of seams have a level of complexity from simple to relatively complex with the coefficient of formation (Kcc = 0.84 and 0.96); rate of interbedding rock (Kk = 8 and 24%); thickness of interbedding rock (Mk = 0.16 and 1.34 m). Quantitative calculation results have shown that the Binh Minh coal deposit belongs to the type III of mining exploration groups. For an exploration of this type of mineral, it is recommended to use a linear grid pattern. The appropriate exploration grid pattern for reserve level 122 is (200÷250)×(90÷100) m. Research results are the basis for proposing technical means of coal exploration in mines and areas with similar geological and mineral conditions.

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Kostyuchenko, Mikhail, Volodymyr Gogo, Boris Kobilyansky, Oleg Kruzhilko, Ihor Yefremov, Kyrylo Hriadushchyi, and Oleksandr Tkachuk. "ANALYSIS OF PRODUCTION RISK ON EXAMPLES OF MINERS ‘LABOR." JOURNAL of Donetsk Mining Institute, no. 2 (2021): 159–75. http://dx.doi.org/10.31474/1999-981x-2021-2-159-175.

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Objective: Based on the review of the array of publications to analyze the methods and models of general risk assessment, the nature of industrial risks and management processes on the examples of labor of coal miners. Propose a classification of mathematical models of industrial risk and identify the most appropriate model for the work of miners in the stochastic system “man-machine-environment”. Methodology: Applied to the use of situational analysis, qualimetry, probability theory and risk theory, methods of classification of occupational risks. Results: Based on a systematic analysis of multifactorial risks of emergency situations, the essence of industrial risks and management processes on the examples of coal miners, the dominant causes of industrial risk in the ergatic system (“man – machine – environment”), models and methods of risk research. Scientific novelty: For the first time on the basis of the analysis of the reasons, dynamics and consequences of industrial risks the classification of mathematical models of risks which are adapted to ergatic systems of mine production is offered. Practical value: The need for adequate practical application of risk methods and models for the assessment and measurement of industrial hazards has been proven.

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Khorolskyi, A., and A. Kosenko. "DEVELOPMENT AND IMPLEMENTATION OF A MODEL FOR SUBSTANTIATION OF OPTIMAL TECHNOLOGICAL SCHEMES FOR THE MINING OF OUTBURST-PRONE COAL SEAMS." Naukovyi visnyk Donetskoho natsionalnoho tekhnichnoho universytetu, no. 1-2 (2022): 193–205. http://dx.doi.org/10.31474/2415-7902-2022-1(8)-2(9)-193-205.

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Purpose. The purpose of the work is to develop a new approach to substantiate the optimal technological schemes for the mining of outburst-prone coal seams, which will ensure the minimum likelihood of sudden outbursts of coal and gas in the breakage face. Methodology. The integrated approach has been applied, involving the use of graphs, network models, optimization algorithms to find optimal technological solutions; application of energy-force models to assess the likelihood of sudden outbursts of coal and gas; application of dynamic programming to substantiate technological parameters (seam thickness, cutter-loader web width, length of a breakage face, etc.) for mining of outburst-prone coal seams. Results. In the course of the work, a new mathematical model has been obtained and implemented, which allows assessing the risks of a sudden outburst of coal and gas during the mining of coal seams. Based on the application of the model, an algorithm for substantiating technical and technological solutions has been developed. Technical solutions provide for the choice of means of mechanization of a breakage face, a mining schedule out a breakage face, measures for degassing a coal seam, while technological solutions provide for the justification of the length of a breakage face, the cutter-loader web width, and the speed of movement of the breakage face line. Scientific novelty. The originality lies in the creation of the mathematical model that allows assessing the likelihood of a sudden outburst of coal or gas, which made it possible to create a new approach based on the use of graphs and network models, as well as to determine the optimal technological solutions for mining coal seams. Practical significance. The practical value of the work lies in the creation of an application package for the selection of purification facility in accordance with certain technological solutions. The general algorithm for justifying technological schemes for mining outburst-prone coal seams involves the following sequence of actions: setting the initial parameters of a rock mass and breaking them into discrete values; for possible routes of the graph of technological solutions, the mathematical expectation and dispersion are determined; the probability of sudden outbursts of coal and gas for the studied parameters is determined; on the basis of the calculated probability, dependences of the occurrence of a coal or gas outburst are obtained in accordance with the values of the parameters (face length, the speed of movement of the breakage face line, etc.); on the basis of the data obtained, the optimal technological schemes for mining outburst-prone coal seams are substantiated; based on the application of a package of applied programs, mechanization means are selected. The scope of the above approach is not limited to the existing means of mechanization, mining and geological conditions of coal seams, existing technological schemes, and others.

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Jiang, Kao, Kuidong Gao, and Lirong Wan. "Effect of Gangue Distributions on Cutting Force and Specific Energy in Coal Cutting." Strojniški vestnik – Journal of Mechanical Engineering 66, no. 3 (March 15, 2020): 203–12. http://dx.doi.org/10.5545/sv-jme.2019.6461.

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Coal consists of diverse materials, and gangue is one of the most common ones. At present, most mathematical models about cutting force and specific energy in the cutting process have not taken gangue minerals in coal seams into consideration. The gangue distribution function is proposed to simulate situations in which gangue minerals are in different distributions. Moreover, the cutting force due to gangue mineral at different heights is also obtained with the finite element method. Combined with the gangue distribution function, the increased cutting force due to gangue minerals can be obtained for any gangue distribution. The present paper also proposes a new mathematical model to calculate the increased specific energy under different gangue distributions. The results show that the gangue distribution function is useful for simulating various situations of gangue distributions in coal seams. Under dispersive gangue distribution in coal seams, the increased mean cutting force, as well as the increased specific energy, is less influenced by gangue distribution, and it tends to be a constant. These results can be useful for the related research on coal cutting under complicated conditions.

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Hajra, Sugato, and Abhishek Aditya Patra. "STUDY OF CIRCULATING COAL FLUIDIZED BOILERS." International Journal of Students' Research in Technology & Management 3, no. 6 (September 30, 2015): 396. http://dx.doi.org/10.18510/ijsrtm.2015.363.

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In the days of modernization, industrialization, technological world we find out a new method of steam production with help of coal. This state of act systems are manufactured over a range of 500 TPH.This boilers are highly efficient, multi coal firing capacity, less emission of so2 and nox gases, utilize high ignite cokes, petcoats,washery rejects. This survey paper is intended to comprehensively give an account of domain knowledge related to CFBC boiler. The authors touch upon the design changes which are introduced in the component levels in order to ease the operation, enhance the performance and to meet the regulatory compliance. In addition, salient correlations related to hydrodynamics, heat transfer and combustion are narrated to facilitate the control and system engineers to develop mathematical models using conservation of mass, energy and momentum equations.

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Wen, Xiao Qiang. "Comparison and Application of Two Mathematical Models in Predicting and Determining the State of Deposition and Slagging of Coal Burning Boiler." Advanced Materials Research 818 (September 2013): 240–45. http://dx.doi.org/10.4028/www.scientific.net/amr.818.240.

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Building a model to predict the state of slag on coal-fired boilers is a good way to optimize the coal combustion and reduce the risk of boiler slag. This paper built new models based on vague sets to predict the state of slag on coal-fired boilers, in which there were six input vectors, which were softening temperature, SiO2-Al2O3 ratio, alkali-acid ratio, percentage of silicon content, the dimensionless average temperature furnace and the dimensionless inscribed circle diameter furnace, and one output vectors, which was slagging degree. Two methods, which were based on the sense of distance and symmetric fuzzy cross entropy, were proposed to calculate the similarity between vague sets. 10 coal burning boilers were selected as known samples and the feasibility of the new methods was proved by the result of predicting the state of slag on the four coal burning boilers from Jilin heat and power plant, Xinli power plant, Jinzhou power plant and Qinhuangdao power plant. Through predicting and determining, it proves that the two pattern recognition models are high in prediction accuracy. Compared with the normal method, it is easier for operators to predict, determine the slagging state and reduce disturbance as far as possible. Besides, a prediction system has been developed by object-oriented high-level language accordingly.

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Milicevic, Aleksandar, Srdjan Belosevic, Ivan Tomanovic, Nenad Crnomarkovic, and Dragan Tucakovic. "Development of mathematical model for co-firing pulverized coal and biomass in experimental furnace." Thermal Science 22, no. 1 Part B (2018): 709–19. http://dx.doi.org/10.2298/tsci170525206m.

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A comprehensive mathematical model for prediction of turbulent transport processes and reactions during co-combustion of pulverized fuels in furnace fired by 150 kW swirl stabilized-burner has been developed. Numerical simulations have been carried out by using an in-house developed computer code, with Euler-Lagrangian approach to the two-phase flow modelling and sub-models for individual phases during complex combustion process: evaporation, devolatilization, combustion of volatiles, and char combustion. For sub-model of coal devolatilization the approach of Merrick is adopted, while for biomass devolatilization the combination models of Merrick, and of Xu and Tomita are selected. Products of devolatilization of both the pulverized coal and biomass are considered to contain the primary gaseous volatiles and tar, which further decomposes to secondary gaseous volatiles and residual soot. The residual soot in tar and carbon in coal and biomass char are oxidized directly, with ash remaining. For volatiles combustion the finite rate/eddy break-up model is chosen, while for char oxidation the combined kinetic-diffusion model is used. The comprehensive combustion model is validated against available experimental data from the case-study cylindrical furnace. The agreement of the simulations with the data for the main species in the furnace is quite good, while some discrepancies from experimental values are found in the core zone. The presented model is a good basis for further research of co-combustion processes and is able to provide analysis of wide range of pulverized fuels, i. e. coal and biomass. At the same time, the model is relatively simple numerical tool for effective and practical use.

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Strang, Kenneth David. "Logistic Planning with Nonlinear Goal Programming Models in Spreadsheets." International Journal of Applied Logistics 3, no. 4 (October 2012): 1–14. http://dx.doi.org/10.4018/jal.2012100101.

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This is a case study of a coal mining company to demonstrate how algebra principles and nonlinear goal programming can be applied for logistics planning using spreadsheet software. The paper asserts that mathematical programming techniques are not well-accepted by managers because the models are difficult to understand due to abstract notational conventions yet alternative commercial software is inflexible (and sometimes inaccurate). The relevant operations research literature was reviewed, highlighting techniques applicable for analyzing quantitative and qualitative logistics data. A practical supply-demand transportation logistics model was built which included determinist constraints and stochastic costing theories, while applying both linear and nonlinear calculus slope principles. The formulae were explained in algebraic standard form (citing corresponding spreadsheet functions). The logistics problem was optimized, illustrating how 6 mining sites could supply 4 countries with sufficient coal to meet different electricity demand levels, surpassing the break-even goal and projecting annual revenue of over $34 billion.

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Strand, Julian, Reem Freij-Ayoub, and Shakil Ahmed. "Simulating the impact of coal seam gas water production on aquifers." APPEA Journal 52, no. 1 (2012): 545. http://dx.doi.org/10.1071/aj11042.

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Derived from a larger scale project, which studied geomechanical issues associated with coal seam gas (CSG) production, this paper investigates a hypothetical case study based on the Latrobe Valley, Gippsland Basin, Victoria. The paper focuses on examining aquifer water management associated with CSG production-related water extraction. As such, the paper limits itself to determining the volume of water production from a hypothetical case study area in the Latrobe Valley. A simplistic property model and methane production strategy has been used. The impact of extraction of this water on the hydraulic head in aquifers underlying the produced seams is quantified. The Latrobe Valley Depression contains 129,000 million tonnes of coal resources and is one of the world’s largest, and lowest cost, energy sources. Most of Victoria’s electricity is generated using coal from the Loy Yang, Morwell and Yallourn mines. In addition to these massive operations, significant additional coal resources are available and unallocated at this time. Opportunities exist for the continued usage of these resources for electricity production, gasification, liquefaction and other coal conversion processes, as well as solid fuel for industrial, domestic and other uses. The existence of data from the Victorian Department of Primary Industries 2003 coal resource model was the main reason for the selection of the case study, and their data was used to form a model of the stratigraphy of the Latrobe Valley. Aquifer models were simulated in MODFLOW, based on extraction figures modelled in the CSG simulator COMET3.

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Perkins, Greg. "Mathematical modelling of in situ combustion and gasification." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 232, no. 1 (August 2, 2017): 56–73. http://dx.doi.org/10.1177/0957650917721595.

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The total worldwide resources of oil sands, heavy oil, oil shale and coal far exceed those of conventional light oil. In situ combustion and gasification are techniques that can potentially recover the energy from these unconventional hydrocarbon resources. In situ combustion can be used to produce oil, especially viscous and immobile crudes, by heating the oil and reducing the viscosity of the hydrocarbon liquids allowing them to flow to production wells. In situ gasification can be used to convert deep carbonaceous materials into synthesis gas which can be used at surface for power generation and petrochemical applications. While both in situ combustion for oil recovery and in situ gasification of coal have been developed and demonstrated over many decades, the commercial applications of these techniques have been limited to date. There are many physical processes occurring during in situ combustion, including multi-phase flow, heat and mass transfer, chemical reactions in porous media and geomechanics. A key tool in analysing and optimising the technologies involves using numerical models to simulate the processes. This paper presents a brief review of mathematical modelling of in situ combustion and gasification with an emphasis on developing a generalised framework and describing some of the key challenges and opportunities.

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Tyurina, E. A., P. Yu Elsukov, and A. S. Mednikov. "Synthetic liquid fuels: prospects for innovative technologies based on underground coal gasification." E3S Web of Conferences 209 (2020): 03026. http://dx.doi.org/10.1051/e3sconf/202020903026.

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The growing demand for energy, the depletion of oil and gas reserves, and the threat of global climate change have led to an increase in interest in underground coal gasification technologies (UCG) around the world. The potential for using underground gasification of low-grade coal resources with complex mining and geological conditions is huge. The main challenge is the development of competitive technologies for the production of synthesis gas and production of electricity, heat, and synthetic liquid fuels on its basis. The paper presents a study of one of the promising areas of the use of UCG gas for the combined production of synthetic liquid fuel (methanol) and electricity. A mathematical model of the installation for combined production of methanol and electricity (ICPME) was developed. Based on this mathematical model, a technical and economic optimization of the parameters was carried out to assess the prospects of the scale of application of this coal processing method. The purpose of research conducted using the mathematical models of the ICPME is to determine the optimal parameters of the installation and the sensitivity of its economic performance indicators to changes in external conditions.

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Pavlysh, V. M., I. V. Tarabaieva, O. S. Grebonkina, and S. S. Grebonkin. "The investigation of mathematical models of the processes of drying of enriching coal in “boiling layer”." Mining of Mineral Deposits 9, no. 2 (June 30, 2015): 163–66. http://dx.doi.org/10.15407/mining09.02.163.

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Kiriia, R. V. "Mathematical models of functioning of accumulating bunkers in systems of underground conveyor transport of coal mines." Geo-Technical mechanics, no. 151 (2020): 216–33. http://dx.doi.org/10.15407/geotm2020.151.216.

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Liu, Jingzhang, Sheng Chen, Zhaohui Liu, Ke Peng, Nan Zhou, Xiaohong Huang, Tai Zhang, and Chuguang Zheng. "Mathematical Modeling of Air– and Oxy–Coal Confined Swirling Flames on Two Extended Eddy-Dissipation Models." Industrial & Engineering Chemistry Research 51, no. 2 (December 16, 2011): 691–703. http://dx.doi.org/10.1021/ie201430a.

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Karbownik, Marcin, Jerzy Krawczyk, Katarzyna Godyń, Tomasz Schlieter, and Jiří Ščučka. "Analysis of the Influence of Coal Petrography on the Proper Application of the Unipore and Bidisperse Models of Methane Diffusion." Energies 14, no. 24 (December 16, 2021): 8495. http://dx.doi.org/10.3390/en14248495.

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The analysis of phenomena related to gas transport in hard coal is important with regard to the energetic use of coal bed methane (CBM), the reduction of greenhouse gas emissions to the atmosphere (CO2) and the prevention of natural hazards such as methane hazards and gas and rock outbursts. This article presents issues concerning the feasibility and scope of applying the unipore and bidisperse diffusion models to obtain knowledge concerning the kinetics of methane sorption and its diffusion in the carbon structure, depending on its petrography. Laboratory tests were carried out on coal samples which varied in terms of petrography. Quantitative point analyses were carried out, based on which content of groups of macerals was determined. The degree of coalification of coal samples was also determined based on measurements of vitrinite reflectivity R0 and the volatile matter content Vdaf. Sorption kinetics were also investigated, and attempts were made to adjust the unipore and bidisperse models to the real sorption kinetic courses. This allowed the identification of appropriate coefficients controlling the course of sorption in mathematical models. An attempt was also made to assess the possibility of applying a given model to properly describe the phenomenon of methane sorption on hard coal.

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Wang, Chia-Nan, Hoang-Phu Nguyen, Yen-Hui Wang, and Nhat-Luong Nhieu. "Strategic Alliances for Sustainable Development: An Application of DEA and Grey Theory Models in the Coal Mining Sector." Axioms 11, no. 11 (October 28, 2022): 599. http://dx.doi.org/10.3390/axioms11110599.

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Sustainable development is a global trend and an economic priority for many governments. Although new energies can be considered good investments in green growth, they may lead to financial barriers to developing countries. The purpose of the study concentrates on an alternative solution that increases the efficiency performance of current fossil energy industries. The study has combined two models of Data Envelopment Analysis (DEA) and Grey Theory in determining inefficient units to propose potential strategic alliances for sustainable development in the Vietnam Coal industry. Besides considering inputs and outputs in the models, the location of coal mines is also a key indicator in recommending good alliances. The results show that the collaborations between the Cao Son coal mine and the Coc Sau coal mine, and between the Nui Beo coal mine and the Vang Danh coal mine, bring the best improvement for sustainable development. The study suggests detailed strategies in action that enterprises and policymakers can refer to, to apply in practice.

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Journal articles on the topic 'Coal liquefaction Mathematical models'

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