HEAT-AND-POWER ENGINEERING FUNDAMENTALS
E.K. Vachagina, A.I. Kadyirov, J.V. Karaeva, R.M. Garipov2, A.A. Akhmadiyarov3
DETERMINATION OF RHEOLOGICAL PARAMETERS OF GIEZEKUS AND Vinogradov-MALKIN modelS FOR DESCRIPTION OF THE RHEOLOGICAL BEHAVIOR OF POLYETHYLENE MELTS (Transactions of Academenergo. 2020. N 1. pp. 7-17).
doi:10.34129/2070-4755-2020-58-1-7-17.
e-mail: vachaginae@mail.ru, aidarik@rambler.ru, julieenergy@list.ru, rugaripov@mail.ru, aydaru@ya.ru
1Institute of Power Engineering and Advanced Technologies of FRC Kazan Scientific Center of RAS
2Kazan National Research Technological University
3Kazan Federal University
Keywords: experiment, rheology, Giezekus model, Vinogradov-Malkin model, polymer melt
Abstract
The paper presents the results of experimental studies of the rheological properties of polymer melts grades PE2NT11-9 and PE2NT11-285. The flow curves are approximated by the Giezekus and Vinogradov-Malkin equations of state. The relaxation time spectrum is determined from the results of oscillation tests. The parameter responsible for the nonlinearity of the Giezekus model is determined from the condition of minimizing the deviation of the stress difference between the calculated and experimental values at a shear flow organized in the gap between two disks (plate-plate measuring system).
A.G. Laptev, T.M. Farakhov, E.A. Lapteva
DETERMINATION OF THE MIXING EFFICIENCY OF HETEROGENEOUS MEDIA IN FLOW CHANNELS WITH CHAOTIC PACKAGING (Transactions of Academenergo. 2020. N 1. pp. 18-29).
doi:10.34129/2070-4755-2020-58-1-18-29.
e-mail: grivka100@mail.ru
Kazan State Energy University
Keywords: turbulent mixing, chaotic nozzles, flow structure
Abstract
The problem of mathematical modeling of turbulent transport and mixing of a fine phase with a liquid in large-scale static flow mixers with a small chaotic packing is considered and solved. A mathematical model of the transfer rate of fine particles, which are almost completely carried away by turbulent pulsations of the liquid phase in the core of the mixer flow, has been developed. An expression is obtained for calculating the particle transfer rate coefficient using the turbulent boundary layer model. With the help of a cell model of the flow structure and the number of units of particle transfer, a formula is obtained to determine the required length of the mixing zone with the packing for a given mixing efficiency. Expressions for calculation of parameters of mathematical model are given and results of calculations of length of packing from Reynolds number at mixing of a liquid phase with particles of different diameter are presented. It is noted that static mixers are successfully implemented at the enterprises of the petrochemical complex.
INDUSTRIAL HEAT-AND-POWER ENGINEERING
N.D. Yakimov*, A.I. Khafizova**, N.D. Chichirova*, O.S. Dmitrieva**, E.V. Artemeva*
INVESTIGATION OF THE TIME OF GAS FLOW THROUGH A HOLE IN LONG PIPELINES UNDER HIGH PRESSURE (Transactions of Academenergo. 2020. N 1. pp. 30-43).
doi:10.34129/2070-4755-2020-58-1-30-43.
e-mail: ieremiada@gmail.com
*Kazan state power engineering university, **Kazan national research technological university
Keywords: gas pipeline, high pressure, mathematical and numerical modeling, isothermal expansion, adiabatic expansion
Abstract
During the operation of pipelines, over time, defects appear in the places of flange connections, through which gas leaks occur. This leads to loss of fuel, as well as the risk of fire and explosion. It is often difficult to detect the leak location. In addition, there are usually several similar sites. The problem is compounded by the fact that such pipelines for transporting gas have a significant length. The easiest and most reliable way to solve this problem is to completely re-seal the suspicious section of the pipeline. This is possible only when the gas pressure drops to values close to atmospheric pressure. At the same time, it is important to know the time of gas flow from the gas pipeline through the fitting, the size of which is known. The difficulty in determining this time is that due to high gas pressure, there will first be a supersonic outflow, and then a subsonic outflow. The ratio of the length of the pipeline section under consideration to its diameter is several tens of thousands, therefore, it is necessary to take into account changes in pressure and density along the length. It is also important to know the effect of the heat exchange process between the gas cooling from the pressure drop and the environment. To solve this problem, a mathematical model of gas flow through a hole in a long pipe is developed, and numerical studies are presented for isothermal and adiabatic expansion. A specific example is used to calculate the time of gas outflow from the pipe when the pressure is equalized with the atmospheric pressure. The distribution of density along the length of the pipe for different modes of processes is also presented.
POWER AND MECHANICAL ENGINEERING
A.V. Tumanov, D.A. Kosov, D.I. Fedorenkov
IMPLEMENTATION OF THE RAMBERG-OSGOOD STATE LAW IN THE ANSYS FINITE ELEMENT COMPLEX (Transactions of Academenergo. 2020. N 1. pp. 44-61).
doi:10.34129/2070-4755-2020-58-1-44-61.
e-mail: tymanoff@rambler.ru
Institute of Power Engineering and Advanced Technologies, FRC Kazan Scientific Center, Russian Academy of Sciences
Keywords: deformation diagram, the Ramberg-Osgood law, finite element method, plastic stress intensity factor
Abstract
In the present work the introduction of dynamically connected library of a user’s material in finite element complex ANSYS has been realized, which allows us to describe the mechanical properties of a material on model Ramberg-Osgood. With the help of this model the stress-strain state of a cylindrical sample and a plate of infinite sizes with a central through crack has been calculated. The verification of the program consisted in determining equivalent deformations and stresses and comparing them with an analytical strain diagram. The found fields of radial and circumferential stresses at various relative distances from the crack apex were compared by HRR solution. The influence of the plastic parameter on the description of the deformation diagram was also shown, which takes into account the nonlinear nature of the deformation in the transition area from the elastic section of the diagram to the plastic one.
POWER GENERATION STATIONS
A.G. Filimonov, A.A. Filimonova, N.D. Chichirova
MODERNIZATION OF HEAT GENERATION IN RUSSIA (Transactions of Academenergo. 2020. N 1. pp. 62-72).
doi: 10.34129/2070-4755-2020-58-1-62-72.
e-mail: agfilimonov@mail.ru, aachichirova@mail.ru, ndchichirova@mail.ru
Kazan State Power Engineering University
Keywords: power engineering, modernization, thermal power plants, combined cycle plants.
Abstract
In the modern energy sector of Russia new basic approaches to the systematic organization of updating and modernization of production assets are taking place. The first power generation modernization program in Russia’s new history from 2010 to 2020 provided a significant breakthrough in the energy asset renovation, creating a tangible groundwork for the electricity industry updates in the medium term until 2025-2030. At the same time came out in the “manual” mode it did not become self-sufficient and self-regulating system mechanism and the necessity of deeper development and creation of systematic approach new models to modernization was revealed. The Russian Energy Ministry with the participation of entire energy community has developed and since 2019 implemented a new integrated mechanism that provides an opportunity for all energy market participants, both producer and consumer, to find mutually beneficial solutions for the implementation of investment projects in power generation.
V.E. Yurin, M.A. Murtazov
PLANTWIDE RESERVATION OF OWN NEEDS OF A NPP BASED ON THE HEAT ACCUMULATION SYSTEM, INCLUDING A LOW-POWER STEAM TURBINE (Transactions of Academenergo. 2020. N 1. pp. 73-83).
doi: 10.34129/2070-4755-2020-58-1-73-83.
e-mail: sncransar@san.ru, urin1990777@bk.ru
Saratov Scientific Center of the Russian Academy of Sciences
Keywords: nuclear power plant, multifunctional additional steam turbine, heat accumulation system, blackout, backup of auxiliary needs of nuclear power plants, core damage.
Abstract
Modern safety systems have a number of disadvantages, such as high cost and single-purpose use, leading to the cost of maintenance. Previously, an alternative option for cooling down VVER-type reactors with complete de-energization by power supplying of own needs consumers through the beneficial use of residual heat energy from the core to generate steam, which serves as working heat for an additional low-power multi-functional steam turbine, was developed and justified. As calculations based on the experimental data of the Balakovo NPP showed, the energy of residual heat generation of one VVER-1000 reactor is enough to cool two VVER-1000 reactors in an emergency situation, accompanied by a complete blackout when the primary circuit is depressurized on one of them for 72 hours. In the normal mode, the effective operation of an additional steam turbine can be ensured by combining the nuclear power plant with a heat accumulation system. An energy complex based on combining nuclear power plants with a phase transition accumulator and an additional multifunctional steam turbine installation has been developed. The investigation of the developed energy complex for the possibility of accumulating excess energy of the reactors residual heat and, as it decreases, effectively using the accumulated excess purposely to increase the time of autonomous power supply of the station’s own needs in emergency situations accompanied by complete blackout, was carried out. The effect can be achieved due to the possibility of increasing the temperature of the feed water at the entrance to the steam generators of nuclear power plants, that in conditions of decreasing residual heat energy, will be possible to maintain at the required level the flow rate of generated fresh steam into a multifunctional steam turbine. The worst case, when the accumulator is in a discharged state, was investigated for two emergency situations with a complete blackout of four power units: without depressurization and with depressurization of the first reactor circuit of one of them.
ECONOMICS, ECOLOGY, INNOVATIVE TECHNOLOGIES
AND PROCESSES IN POWER ENGINEERING
Sh. Shagapov*, E. V. Galiakbarova**
THE INFLUENCE OF THE SIZE AND INITIAL VELOCITY OF THE DROPLETS OF WASHING WATER DURING JET INJECTION ON THE EFFICIENCY OF OIL PURIFICATION FROM MINERALIZED PARTICLES (Transactions of Academenergo. 2020. N 1. pp. 84-94).
doi: 10.34129/2070-4755-2020-58-1-84-94.
e-mail: Shagapov@rambler.ru, emi.galiakbar@yandex.ru
*Mavlyutov Institute of Mechanics, Ufa Investigation Center RAS.
**Ufa State Petroleum Technological University
Keywords: jet mixer, mixing zone, droplet movement, coagulation, washing water, oil.
Abstract
The theory of the process of refining oil from fine particles of mineralized water by the jet introduction of washing water against the flow of the mineralized water in oil emulsion is developed. It is assumed that the dispersion of wash water into droplets is a controlled process. Due to changes in the liquid flow rate and the outlet cross section of the jet device, in addition, the introduction of various additives in the composition of the injected water, which leads to a change in its viscosity and surface tension coefficient, it is possible to affect the droplet size formed during the decay of the jet over a wide range. On the basis of numerical experiments on previously proposed theoretical models, the influence of the degree of dispersion of the jet and the initial droplet velocity on the efficiency of “washing out” mineralized particles from oil is analyzed. In particular, it was found that achieving an increase in the size of a drop of washing water by an order of magnitude can reduce the consumption of washing water by about the same amount.
M.Yu Chernetskiy, E.B. Butakov, V.A. Kuznetsov
Calculation on ash deposit formation during pulverized coal combustion in a large-scale laboratory furnace (Transactions of Academenergo. 2020. N 1. pp. 95-106).
doi: 10.34129/2070-4755-2020-58-1-95-106.
e-mail: Micch@yandex.ru, e_butakov@mail.ru, victor_partner@mail.ru
Kutateladze Institute of Thermophysics, Russian Academy of Sciences
Keywords: mathematical model, furnace, pulverized coal combustion, slag deposits.
Abstract
In this paper are presented a mathematical model and calculation method of slagging factor using CFD methods. The mathematical model of slagging contains a set of models: those of fly ash formation, transport of particles towards the surface and their properties, fixation of particles, and the growth of deposits, properties of deposits. In this work, consideration is given to secondary fast growing slag deposits that settle on the primary layer which has already been formed; these deposits occur as a result of sticking of particles to the surface at the temperature called the initial slagging temperature. The results obtained calculation process of formation of slag deposits on the probe in the uncooled combustion chamber firing stand 5 MW. The results of calculations slagging factor for brown coal and comparison with experimental data have shown that the developed method allows calculation of coefficient predicting slagging coal slag properties. The method is a “virtual stand” and can be successfully used for a preliminary assessment of the slagging process in boilers.