Bishkek, Kyrgyzstan

Kyrgyz State Technical University
Bishkek, Kyrgyzstan

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Engelsht V.S.,Institute of Physical Technical Problems and Material science NAS KR | Muratalieva V.Z.,Kyrgyz State Technical University
Thermophysics and Aeromechanics | Year: 2013

Wollastonite synthesis and decomposition were analyzed from the viewpoint of thermodynamics (using the TERRA software). It is shown that wollastonite synthesis from limestone and silica takes place at a minimum content of nitrogen (10-5 N2) with a release of carbon dioxide. The synthesis temperature is T ≥ 560 K. Wollastonite is decomposed in the presence of flue gas (4N2) with limestone and silica formation and burial of carbon dioxide in the form of CaCO3(c). Wollastonite decomposition temperature is T ≤ 420 K. The cyclic reciprocating process for complete removal of carbon dioxide by wollastonite is suggested. Four strokes of the reciprocating system with the fixed temperatures of wollastonite decomposition (T=300 K) and wollastonite synthesis (T=560 K) are presented. Total energy consumption (T = 560 K) is ΔI ≈ 130 kJ/mole, 30 % of energy is spent for heating and 70 % of energy is spent for chemical reaction. This is comparable with the heat of CO2 solution in ethanolamin. © 2013 Pleiades Publishing, Ltd.

Ryspaev T.,Kyrgyz State Technical University | Janecek M.,Charles University | Kral R.,Charles University | Wesling V.,Clausthal University of Technology | Wagner L.,Clausthal University of Technology
Materials Science Forum | Year: 2016

The grain refinement after thermo-mechanical treatment (TMT) was investigated in AZ91, AE42, und QE22 magnesium alloys. The optimal over-aging temperature was determined to be 300°C in the case of AZ91 and AE42 alloys and 350°C for QE22 alloy. After optimized TMT, the average grain sizes were 13.5 μm (AE42), 11.1 μm (AZ91) and 1.9 μm (QE22). The QE22 alloy exhibited the superior superplastic properties, with maximum elongation to failure 750 % and strain rate sensitivity parameter m=0.73. The Friction Stir Welding showed that the original base material grain structure of the alloys AZ31 and AZ91 replaced by ultrafine grains in the stir zone. The purpose of the present paper is to present the results of the grain refinement in magnesium alloys by thermo mechanical treatment and stir welding. © 2016 Trans Tech Publications, Switzerland.

Zhainakov A.Z.,Kyrgyz State Technical University | Kurbanaliev A.Y.,Kyzyl Kiysk Humanitarian Pedagogic Institute of the Batken State University
Thermophysics and Aeromechanics | Year: 2013

The work presents the results of mathematical modeling of large-scale flows in areas with a complex topographic relief. The Reynolds-averaged Navier-Stokes equations constitute the basis of the three-dimensional unsteady modelling. The well-known Volume of Fluid method implemented in the solver interFoam of the open package OpenFOAM 1.7.1 is used to track the free-boundary location. The mathematical model adequacy is checked by comparing with experimental data. The efficiency of the applied technology is illustrated by the example of modeling the breakthrough of the dams of the Andijan (Uzbekistan) and Papan (near the Osh town, Kyrgyzstan) reservoirs. © 2013 Pleiades Publishing, Ltd.

Engelsht V.S.,Institute of Physical and Technical Problems and Material Science NAS KR | Muratalieva V.Z.,Kyrgyz State Technical University
Thermophysics and Aeromechanics | Year: 2014

Thermodynamic analysis (TERRA program) of synthesis, heating, and melting of stoichiometric glass CaSiO3·SiO2 has been carried out. Chemically pure substances silica and lime are subjected to exothermic reaction with further external heating and melting. Wollastonite is synthesized, the chemical reaction generates heat Qchr = −505.3 kJ/kg, and temperature increases T = 820 K. When Tmelt = 1812–1814 K, wollastonite melts, and a mixture of liquid wollastonite and condensed silica is formed. At Tmelt = 1995–1997 K, silica melts, and stoichiometric glass (CaSiO3·SiO2) is formed. Evolutions of temperature and melting of wollastonite and silica have been studied by detailed step-by-step thermodynamic calculation (ΔT = 0.1 K). © 2014, Pleiades Publishing, Ltd.

Kalybekovich T.S.,Kyrgyz State Technical University | Djumabekovich O.A.,Kyrgyz State Technical University
Journal of Engineering Science and Technology Review | Year: 2012

This article discusses on use of alternative energy sources in Kyrgyz Republic and the ways of solving problems on its development. © 2012 Kavala Institute of Technology.

Engel'Sht V.S.,National Academy of science | Muratalieva V.Zh.,Kyrgyz State Technical University
High Temperature | Year: 2013

A thermodynamic analysis of the interaction between limestone and silica is carried out under normal pressure with the use of the TERRA program system. An equilibrium system is considered. The thermodynamic parameters are calculated with a step-by-step increase in temperature. The temperature of calcium silicate synthesis with respect to the initial mixture composition is found. At all possible ratios between limestone and silica, the products of the chemical reaction are determined. The reaction heat, synthesis temperature, enthalpy increment, and heat content are determined. It is shown that wollastonite isothermal synthesis proceeds at 550 K at a constant heat content, and rankinite isothermal synthesis proceeds at 750 K at a constant heat content as well. The reaction heat increases with rising limestone content until rankinite starts to form and then decreases to zero. The interaction between limestone and silica produces carbon dioxide gas, whose content grows simultaneously with the rising reaction heat. When the rankinite yield is maximal, the amount of carbon dioxide diminishes to zero, because free limestone forms and CO2 is buried. On the basis of the results, the conclusion is drawn that the reaction proceeds with a latent exotherm due to latent limestone dissociation and formation of lime during the thermal interaction between limestone and silica. © 2013 Pleiades Publishing, Ltd.

Engel'Sht V.S.,Jeenbayev Institute Of Physical Technological Problems And Materials Science Chui Pr 265 | Muratalieva V.Z.,Kyrgyz State Technical University
High Temperature | Year: 2013

Thermodynamic analysis is performed (TERRA software) of the lime-silica interaction for all possible lime-to-silica ratios at normal pressure. The components of the exothermal reactions are calculated. The adiabatic temperature of silica combustion in the lime is found. The heat of the chemical reaction is determined. The enthalpies of the initial rough material and the combustion materials are calculated. The evolution of the silica combusting in the lime, including formation of the stochiometric glass, wollastonite, rankinite, and pseudo-cement, is considered. The thermodynamic analysis is performed under the supposition of use of chemically pure substances with the absence of external heat and specific additions. © 2013 Pleiades Publishing, Ltd.

Duishenaliev T.,Kyrgyz State Technical University | Askarbekov R.,Czech University of Life Sciences
Engineering for Rural Development | Year: 2016

In solid mechanics, there are classical methods for determining and calculating the deformation of the material body, which is used today. Such material, like rubber is anisotropic and at large deformations classical equations and relations are not applicable. For calculation of large deformations notion nonlinearity exists. The given paper contains the use of a non-traditional method for calculating the stress-strain state of rubber metal supports. This method is based on the Cauchy tensor to determine deformation of the body when there is displacement of the body points. With the help of Matlab system we wanted to show the applicability of the new method for calculation of the body with large deformations.

Engelsht V.S.,Institute of Physical and Technical Problems and Material Science NAS KR | Muratalieva V.Z.,Kyrgyz State Technical University
Thermophysics and Aeromechanics | Year: 2015

The authors have studied the change in the component composition of wollastonite marble from Slyudyanka deposits at increasing pressure (p = 0.1–12000 MPa) and temperature (T = 300–6000 K). Metamorphism of marble maturation has been found. The essence of maturation is the calcite melting, carbon dioxide deposition, the monolith compaction, the transformation of mineral composition at pressure increase up to the value of the initial components. When the pressure value reaches 12000 MPa the original components are reproduced, and the maturation of marble completes. Thermodynamic analysis reveals the secrets of the marble origin. © 2015, Pleiades Publishing, Ltd.

Bochkarev I.V.,Kyrgyz State Technical University
Procedia Engineering | Year: 2015

The investigation of a doubly fed induction motor in electric drives of pumping stations is conducted in this paper. The effect of non-sinusoidal rotor supply is considered in the analysis as well. The current total harmonic distortion (THD) is evaluated with respect to the selected voltage modulation in a thyristor frequency converter (TFC) as well as on motor duty cycle. A novel method of reactive power regulation with constant rotor current I2=I2H=constant is proposed. It is shown that the proposed method considerably improves motor performance in the whole operation range. The proposed analytical method is verified with laboratory measurements. © 2015 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.

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