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1
Content available remote Thermal conductivity of the gas in small space
100%
Pavlenko A.
Journal of New Technologies in Environmental Science
|
2018
|
tom Vol. 2, nr 4
197--200
EN
The article is devoted to research of peculiarities of porous materials with micropores thermal conductivity. The temperature influence pattern of heating surface on the process of heat transfer by convection in the pores is given. Mathematical model of gravitational convection, which allows to predict the intensity of the convection current is proposed.
2
Content available Energy and resource saving technologies of formation of massive amorphous structure
100%
Pavlenko A.
Structure and Environment
|
2016
|
tom Vol. 8, no. 1
47--51
EN
The article presents the results of an experimental study of energy-resource saving technologies of formation of massive amorphous structure. Considered are the methods of mathematical modeling and optimization of process production of massive amorphous structures, which can reduce experimental studies and material resources to create a highly efficient production of amorphous alloys. The results of physical experiments are compared with the results of the calculation. Received results can be used to analyze the physical regularities and justified choice of technological modes of formation of amorphous structures.
3
Content available The temperature distribution of the materials in the convective heat transfer
100%
Pavlenko A.
Structure and Environment
|
2015
|
tom Vol. 7, no. 4
185--188
EN
A new method for solving the equations of thermal conductivity materials with specific properties. This method is useful for an approximate estimate of the temperature field of materials.
4
Thermal stability and development of film boiling sites. Experiment and modeling
63%
Pavlenko A. , Starodubtseva I.
Zeszyty Naukowe Politechniki Świętokrzyskiej. Mechanika
|
1999
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tom Z. 67
313--322
EN
The development of one-dimensional (1D) and two-dimensional (2D) sites of film boiling has been studied numerically. To present the valid boundary conditions at the front of the boiling regimes transition, we introduced the dimensionless parameter ε which characterized the ratio between the width of the temperature front along a heat-releasing surface and the linear scale of the capillary forces' action. Here, we present the calculations of stability zones from the film boiling sites depending on their initial sizes, and the dynamic characteristics of development for the different heat flux densities. Simulations were carried out with various boundary conditions within two- and three-zone shape of the boiling curve. Different values of parameter ε were used in these simulations. While describing the dynamics of the front of boiling regime change in the calculation model, the authors take into account the non-stationary character of heat transfer in the zone of bubble boiling caused by temperature pulsations during the growth and detachment of vapor bubbles. We obtained experimental values for the equilibrium density of heat flux in nitrogen. These data were compared with our calculations.
5
Content available remote Mathematical solution to the problem of obtaining massive amorphous structures
63%
Pavlenko A. , Pavlenko A. M.
Journal of New Technologies in Environmental Science
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2018
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tom Vol. 2, nr 3
134--139
EN
This article proposes a mathematical formulation of the problem of casting a metal in a water-cooled mold. The model includes a heat conduction equation that describes thermal phenomena under appropriate boundary conditions.
6
Content available Dispersed phase breakup at emulsion boiling
63%
Klimov R. , Pavlenko A.
Structure and Environment
|
2017
|
tom Vol. 9, no. 1
63--69
EN
In this paper we consider the breakup processes of the emulsion dispersed phase. The possibility of large droplets splitting by small ones under boiling water phase due to a sharp release of pressure is shown, we also take into account the force impact of one drop on the another, based on the instability criteria of Bond and Weber. It is indicated the applicability of the model to determine the processes of displacement, deformation or breakup of inclusions of dispersed phase.
7
Content available Calculation of heat transfer in fluid around gas-vapour bubbles
63%
Pavlenko A. , Koshlak H.
Structure and Environment
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2017
|
tom Vol. 9, no. 1
59--62
EN
In this paper the mathematical model for calculating heat transfer in the fluid that surrounds the oscillating gas – steam bubble. The mathematical model takes into account the changing thermal and physical characteristics the liquid, changing the size of bubbles, heat exchange processes at its border.
8
Content available Peculiarities of phase processes in the volume of liquid
63%
Pavlenko A. , Koshlak H. V.
Structure and Environment
|
2018
|
tom Vol. 10, no. 1
66--74
EN
The work is devoted to the study of the transient processes of heat and mass transfer in the volume of a liquid. The method of calculating the temperature field in a liquid takes into account phase transitions, motion of the bubble wall and heat exchange processes near its surface. The method takes into account the change in the thermophysical characteristics of a liquid when its temperature changes. The results of the research can be used to optimize the various technological processes associated with cavitation, boiling and the formation of gas hydrates.
PL
Artykuł dotyczy analizy nieustalonych zjawisk wymiany ciepła i masy w dużej objętości cieczy. Metoda określenia pola temperatur w cieczy uwzględnia przemiany fazowe, ruch pęcherzy i procesy wymiany ciepła przy ścianie. Metoda ta bierze pod uwagę zmianę właściwości termofizycznych cieczy, gdy zmienia się jej temperatura. Wyniki badań mogą być wykorzystane do optymalizacji różnych procesów technologicznych związanych z kawitacją, wrzeniem i tworzeniem hydratów gazowych.
9
Content available Thermal Insulation Materials with High-porous Structure Based on the Soluble Glass and Technogenic Mineral Fillers
63%
Pavlenko A. , Szkarowski A.
Rocznik Ochrona Środowiska
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2018
|
tom Tom 20, cz. 1
725--740
EN
We report results of research into processes of formation of porous structure by the method of thermal bloating of the gel­like mixture of raw materials. Regularities of the course of physical­chemical transformations are considered in the material when it is heated; as a result, we established the initial water content in the raw mixture, optimal for the formation of xerogel, and the residual water content in gel, sufficient for effective bloating. The raw mix of silica-containing technogenic component – fly ash of thermal power plants – and the methods of preparing waterproof porous thermal insulating materials of extended application on its base according to the powder low-temperature technology has been developed using multifunctional properties of soluble glass as: a) a binding component; b) blowing agent; c) the raw mix hardening rate regulator. The physical and chemical, technological aspects of obtaining and using the suggested alkaline-silicate compositions have been considered. We proposed the optimized composition of the raw mixture that employs maximally permissible amount of ash as a mineral filler; the thermal modes of bloating are studied. Based on the data obtained, a new technology for the production of porous thermal insulation materials is created.
PL
Przekazujemy wyniki badań procesów powstawania porowatej struktury metodą termicznego wzdęcia żelowej mieszaniny surowców. Badaliśmy przemiany fizyko-chemiczne surowej mieszaniny po jej ogrzaniu, co umożliwiło określenie początkowej zawartości wody w surowej mieszaninie, optymalnej dla tworzenia się kserożelu i resztkowej zawartości żelu, wystarczającej do skutecznego pęcznienia. Surowa mieszanina zawiera lotny popiół z elektrowni cieplnej, jak również sposoby wytwarzania porowatych materiałów wodoodpornych, wytrzymałych materiałów izolacyjnych na bazie technologii proszek o niskiej temperaturze zostały opracowane przy użyciu właściwości wielofunkcyjnych szkła wodnego jako: a) element łączący; b) środek porotwórczy; c) regulator szybkości utwardzania dla surowej mieszaniny. Uwzględniono fizyko-chemiczne, technologiczne aspekty wytwarzania i stosowania proponowanych kompozycji alkaliczno-krzemianowych. Zaproponowaliśmy zoptymalizowany skład surowej mieszaniny, która wykorzystuje maksymalną dopuszczalną ilość popiołu jako wypełniacza mineralnego; rozważane są tryby obrzęku termicznego. Na podstawie uzyskanych danych opracowano nową technologię produkcji porowatych materiałów termoizolacyjnych.
10
Content available remote New materials for thermal protection of buildings
63%
Pavlenko A. , Piotrowski J. Z.
Journal of New Technologies in Environmental Science
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2017
|
tom Vol. 1, nr 1
9--18
EN
Significant part of the modern technological processes of structure formation of materials are based on the thermal impact on various raw mixtures, which implement in them physical and chemical processes that create conditions for structure formation. Such processes can be controlled, but it is necessary to find qualitative and quantitative dependencies of the changing thermal properties of materials in the process of their formation. Investigation and control of the processes of structure formation of materials are difficult tasks, which are still unsolved. Clear understanding of the mechanism of structure formation makes it possible to develop a methodological basis of new technologies, including the technology of production of thermal insulating materials with predictable thermal properties. of the porous structure are still little investigated, and a clear relationship between the porosity and the material.
11
Content available remote Dimensions of the nucleus agent pore former closed spherical pores
51%
Pavlenko A. , Cheylitko A. , Koshlak H. , Piotrowski J. Z.
Journal of New Technologies in Environmental Science
|
2017
|
tom Vol. 1, nr 3
101--107
EN
Many experimental data indicate a relationship between the porosity of the material and its thermophysical properties [1-3]. Influence of porosity on the thermal conductivity of the material can be considered following the example of experimental data [2]. The values of thermal conductivity coefficient of iron (58.19 W/(m∙K)) and a rock formation (3.26 W/(m∙K)) differ by almost 18 times, but the filling of iron balls and balls rock formation of the same a porosity of 62.5% has nearly the same coefficient of thermal conductivity (0.0403 W/(m∙K) and 0.0402 W/(m∙K) respectively). However, the way of forming the porous structure has not yet been investigated, and a clear relationship between the porosity and the physical properties of the material not found.
12
Content available Prospects for the development of hydrate storage and transportation technology of methane gas
51%
Pavlenko A. , Koshlak H. , Vytyaz O. , Rybicki C.
AGH Drilling, Oil, Gas
|
2015
|
tom Vol. 32, no. 1
13--21
EN
The gas hydrate tecłmologies can be alternative to the traditional methods of the rational use of hydrocarbon gases. However the known constructions of apparatuses for the production of gas hydrates cannot satisfy the condition of their industrial use fully. Authors offer to carry out the high-quality contact of gas and water at formation of gas hydrate by jet apparatuses with a free falling jet. On their basis a technological chart is offered for realization of continuous cycle of production of gas hydrate. The aim is to develop technical solutions and process parameters of continuous production of gas hydrates, which would satisfy the requirements of industrial application
13
Content available remote Research of influence of the perforation form in metal products on their thermal conductivity
51%
Pavlenko A. , Koshlak H. , Cheylitko A.
Journal of New Technologies in Environmental Science
|
2017
|
tom Vol. 1, nr 3
108--112
EN
The porosity in metals has been perceived only as a negative factor for a long time, which reduces the mechanical properties and tightness of the material. For preventing and blocking the negative effects of porosity in metals were dedicated a lot of scientific works, some of them are used in present time [1-3]. However, due to numerous experiments the positive factors of porosity in metals were opened. These factors are the combination of physical and mechanical properties such as high stiffness in combination with a very low density (low specific gravity) and/or high gas permeability combined with a high/low thermal conductivity [4]. Thanks to this, porous metals have received a new stage of evolution. Now porosity is being regarded not only as a negative effect of imperfection technology of making metal products, but also as a way to produce a material with unique properties. Globally porous metal materials can be divided into three categories: cellular metals [5]; metallic foams [6] and porous metals [7]. Products from such materials are used in the automotive industry as structural elements; in the aerospace industry as titanium and aluminum sandwich panels; in shipbuilding as a body for passenger vessels; in medicine as implants in humans [8-11]. From the field of use such products must conform to the following parameters: porosity, gas permeability, thermal conductivity, electrical conductivity, density, sound absorption, etc. There are a lot of methods of creation of porous metallic materials today. But complete method of controlling thermal properties of materials by changing parameters of porosity is still no. For creating such method we need to know what factors, under what conditions and with what degree are influence on the required material's parameters. The aim of this work is to investigate the influence of a combination of factors (form, size and position of pores) in the porous metal material on the thermal conductivity.
14
Content available Study of the stability of methane hydrates in normal conditions
51%
Pavlenko A. , Koshlak V. , Vytyaz O.
AGH Drilling, Oil, Gas
|
2014
|
tom Vol. 31, no. 4
495--505
EN
The problems of accumulation, transport and storage of gases and gas mixtures exist in many cases. Often the existent technologies appear ineffective for transporting his with pipelines, as condensate or compressed gas. Therefore, the transportation and storage of gas in hydrate form can be an alternative to traditional technologies. Preservation of gas hydrate blocks can store them for some time at the no equilibrium conditions. The thermodynamic parameters of forcibly conservation of gas hydrate blocks theoretically are determined and experimentally verified.
15
Content available remote The phenomenon of resonance in gas-steam bubbles
51%
Pavlenko A. , Kutnyi B. , Abdullah N.
Journal of New Technologies in Environmental Science
|
2017
|
tom Vol. 1, nr 2
52--60
EN
In the basis of many advanced industrial technologies there are such thermodynamic processes occurring on the surface of gas-particle bubbles as absorption [16], aeration [13], bubbling [9], vacuum distillation [5], degassing [3], boiling [18], cavitation [12], the production of heat-insulating materials by the method of blowing [19], gas hydrating [11], and many others. Active studies of the bubbles effect on sound vibrations were carried out to optimize the sonar operation. Existing literature [1, 4] highlights the issue of the damped oscillations at frequencies from 4 kHz to 150 kHz in seawater at different depths. Another direction of research was caused by the need for the use of cavitation [14]. The study of fluid degasification by cavitation method was carried out at frequency from 10 kHz to 1 MHz. In most cases, bubbles oscillation is damping. However, definitely during these oscillations, the most intense heat and mass exchange processes on the bubbles surface are observed. In the course of oscillation, there is a very rapid change in the thermodynamic parameters of the system "gas bubble-liquid". The urgency of the study of heat and mass transfer processes dynamics on the oscillating gas bubble surface is due to the need to optimize various technological processes.
16
Content available Badania spalania emulsji paliwowych
51%
Pavlenko A. , Szkarowski A. , Janta-Lipińska S.
Rocznik Ochrona Środowiska
|
2014
|
tom Tom 16, cz. 1
376--385
EN
Now the majority of oil refineries seek to improve technologies of oil refining. Deeper processing of raw materials leads to change of physical and chemical indicators of the black oil being the final product. As a result when burning black oil indicators of work of a boiler are broken, incompleteness of combustion, adjournment of particles of coke on heating surfaces, and also decrease in stability of burning increases up to torch failure. The complex solution of this problem is fuel burning in the form of a water black oil emulsion (DOE fuel). In a zone of high temperature of a fire chamber the drop of an emulsion blows up that leads to secondary dispersion of fuel. Than more small drops of water contain in an emulsion, especially this effect is noticeable. Therefore is necessary preliminary preparation of fuel oil by preparation of uniformly distributed and small dispersed fraction of water which contains in fuel and by destruction of the quasicrystal structures which were in it. Researches of formation of NOx when burning DOE fuel showed that the black oil and water ratio in an emulsion has the greatest impact on concentration of oxides of nitrogen. Influence of the same factors on combustion value of an emulsion was researched also. The analysis of data showed that the same factor the content of water in an emulsion has the greatest impact on the combustion value of fuel. Though the increase of the dispersed water content reduces combustion value of fuel, temperature growth in a fire chamber was observed. It is explained by positive influence of small dispersed water on process of further dispersion of fuel oil in a flame. The received results of researches were used in practice for increase in efficiency of the reconstructed boiler KSV-2,9G. The gained ecological effect accompanied the general improvement of work of a boiler and increase of efficiency of use of fuel.
17
Content available The energy parameters of formation of the porous structure
51%
Koshlak H. V. , Pavlenko A. , Piotrowski J. Z.
Structure and Environment
|
2016
|
tom Vol. 8, no. 3
206--210
EN
Research porosity thermal insulation of refractory materials is the important task of power engineering, because the thermal conductivity of porous materials depends on the shape and especially location of pore. Analytical review of existing technologies shows that research in this area is focused on the study of a process separately and generalized theories are not sufficient to clear analysis and model building process heat mass transfer of alumina porous material.
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