Key Engineering Materials Vol. 743

Abstract: The paper investigates the peculiarities of the chemical and mineralogical compositions of semi-flint kaolins and their behavior under heating up to 1500 °C. It was found that the sintering process of kaolin clay raw materials depends on the temperature of their preliminary calcining, method of milling after the thermal treatment and application of mineralizing additives. In the case of Borovichy kaolin, preliminary calcining at 850 °C and 980 °C and its subsequent milling increase the material strength after sintering calcining at the temperature of 1400–1450 °C at the expense of uniform sintering and the formation of a homogeneous microstructure of sintered material.

Abstract: Gravity separation is considered as the most used processing technique for thermal coal cleaning. A broad variety of methods and machines was developed for that purpose. However, the performance of those apparatus under different conditions is not the same. In this article, the results of coarse thermal coal cleaning in various equipment were simulated by means of mathematical modelling. The comparison of obtained quantitative and qualitative indicators of gravity separation showed that for processing of difficult-to-wash thermal coal the heavy medium-based processes are more favorable, whereas for more easily washable coal jigging can be efficiently used as well.

Abstract: Changes in the properties of brown Kansk-Achinsk coal after exposure to microwaves have been studied using scanning electron microscopy (SEM) and electron magnetic resonance (EMR). The size composition of the samples has been investigated. The structure of coal has been found to be similar to the structure of multicomponent organic glass. The analysis of the changes in the EMR spectra of the coal samples (300 K, 83 K) exposed to microwaves has been found to gather information about the structural transformation taking place in the coal matter.

Abstract: Nowadays, X-ray tomography is one of the most pertinent directions of the development of non-destructive testing methods. Besides the experimental setup to conduct the X-ray tomographic measurements, it is necessary to have stable and flexible software. In most cases, existing software packages for the reconstruction of tomographic data are not freeware. This makes tomographic experiments not flexible because of the restriction of the source code correction. This papers explains how to implement one of important parts of tomographic research, namely, experimental data simulation, which allows to test reconstruction algorithms further.

Abstract: This paper presents the results of mathematical modelling of three–dimensional heat transfer in a closed two-phase thermosyphon taking into account phase transitions. Three-dimensional conduction equation was solved by means of the finite difference method (FDM). Locally one-dimensional scheme of Samarskiy was used to approximate the differential equations. The effect of the thermosyphon height and temperature of its bottom lid on the temperature difference in the vapor section was shown.

Abstract: Standardization is the activity of normalizing norms and rules which are in general obligatory for products, services and methods of measurement, control and testing. One of the main demands to the methods of analysis is to ensure a certain level of accuracy. Requirements for the analysis sequence and the accuracy of the measurement data are the result of a compromise between the consumer and the supplier of the analysis. It is suggested to use functional-target analysis in order to determine the relations between the properties and functions of the object. On the example of X-ray fluorescence analysis it is shown that it is possible to formulate the functions of the researched object and analyze the properties which are necessary to put these functions into practice. It allows for determining such indicators of the analytical method that can be assessed quantitatively. Such approach can be used to construct mathematical models to estimate the degree of accuracy required for solving specific problems of consumers of precise measurement information.

Abstract: The manufacturing of polymer optical parts is a technologically complicated process because of a high precision of optical surfaces. Every responsible part has to be checked for homogeneity due to its high effect on optical properties. Thus, the creation of an area for automatized part control after injection molding is a pertinent goal. The study has applied the concept “Industry 4.0” to create a model of automatized area for polymer lens control. A photoelasticity control method for photosensitive materials was chosen.

Abstract: As the title implies the article deals with the problem of stress-strain assessment of metallic elements in power-generating equipment. An electromagnetic-acoustical method is proposed to test and diagnose the technical condition of power apparatuses. It is stressed that the transfer function is an integral parameter that makes it possible to assess the condition of metal in a unit under test. The studies established the relationship between the quantitative values of polynomial roots of the transfer function in the system “a unit under test - electromagnetic acoustic transducer” and the level of the stress-strain state of metal.

Abstract: Fuel-power supply systems are priority areas of engineering services. They account for large capital investments and costs of energy resources. An energy supply system based on LPG provides a high level of diversification and autonomy. This article presents recommendations for determining the basic technological parameters of liquefied petroleum gas tanks. The recommendation are intended to improve the efficiency of the tanks. The economic-mathematical model of optimizing underground tanks considers own evaporative capacity of tanks, their mutual thermal effect, as well as the temporal dynamics and unstable cost factors. The model allows for revealing the optimum technological parameters of installations: a single tank volume, the number of tanks in a group installation, the calculated level of gas tanks fill up before next refueling, depending on the volume of gas consumption.

Abstract: In this paper, the steady-state flow of non-Newtonian fluid in a planar channel with sudden expansion is investigated. The rheological behavior of this media is described by the Herschel-Bulkley model. To determine both steady-state velocity and pressure fields, a numerical algorithm based on the relaxation method and SIMPLE procedure is used.The mathematical problem statement includes three non-dimensional parameters: the Reynolds number, the Bingham number (non-dimensional viscoplasticity parameter), and the power-law index. The results of numerical simulation are obtained in a range of the Reynolds number 1 ≤ Re ≤ 40, Bingham number 0 ≤ Se ≤ 2, and power-law index 0.4 ≤ k ≤ 2 (for shear thinning, Newtonian, and shear thickening fluids).The distribution of the main fluid flow characteristics and localization of the two-dimensional region in an expansion zone is presented. The impact of main parameters of the problem on a dead zone distribution in the fluid flow is shown.