bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of multistage air-steam-blown entrained-flow coal gasification
Authors: Nikitin A D , Abaimov N A , Butakov E B , Burdukov A P , Ryzhkov A F 
Published: December 2020

Abstract
The aim of the work is using an experimental-computational method to study the process of air-steam-blown entrained-flow gasification of coal with multistage air supply. To achieve this aim, the experiment was conducted on a plant consisting of a swirler into which coal and air are supplied, and a reaction chamber into which steam and multistage air are supplied; the experiment was numerically simulated using a validated CFD model; and the process under study was analysed using the obtained experimental and calculated data. The conducted experimental and computational studies of air-steam-blown gasification allowed determining the effect of steam supply and multistage air supply on the features of the gasification process. Steam injection lowers the temperature of the gas mixture and increases the concentration of hydrogen due to the hydrogasification reaction. The air supply to the reaction chamber increases the temperature of the mixture due to the burning of part of the syngas, while the syngas heating value is reduced by an appropriate amount. The maximum concentration of the syngas combustible components (and hence syngas heating value) is observed before the second point of air supply to the reaction chamber.
Nonlinear steady-state traveling waves in a rivulet flowing down an inclined tube
Authors: Aktershev S P , Alekseenko S V , Bobylev A V 
Published: December 2020

Abstract
The theoretical model based on long-wave approach is developed for the description of waves in rivulet flowing on the bottom surface of an inclined cylinder. The model equations are derived on the weighed residual method by projecting Navier-Stokes equations on the system of basic orthogonal polynomials. The simplest case of quasi-two-dimensional waves is studied in detail. The characteristics of nonlinear steady-state traveling waves in the rivulet are obtained for the first time. The results of calculations are in good agreement with experimental data for various liquids in a wide range of parameters.
The study of gas injection modes from a long tube to a channel filled with liquid
Authors: Alekseev M V , Lobanov P D , Svetonosov A I , Lezhnin S I , Pribaturin N A 
Published: December 2020

Abstract
The results of experimental and numerical studies of the gas phase injection into the liquid column and sudden gas-liquid interaction are presented. Experimental study was performed by means of high-speed shadowgraph and analysis of signals of pressure transducers. The numerical part of the work was carried out using the OpenFOAM software. The data about void fraction distribution and pressure evolution are presented. In general, a good agreement between the experimental and calculated data was found. The data obtained can be used for verification and validation of different numerical codes, as example ones for the prediction of the process of the steam generation leakage on nuclear power plant.
Experimental study of gas-liquid flow in a rectangular microchannel using LIF method
Authors: Bartkus G V , Kuznetsov V V 
Published: December 2020

Abstract
This paper aims at experimental study of gas-liquid flow in a horizontal rectangular hydrophilic microchannel with a cross-section of 200×400 μm. The ethanol and nitrogen are used as working liquids and gas accordingly in the microchannel with crossflow T-mixer at the channel inlet. Experimental data are obtained using high-speed visualization, laser flow scanning, and LIF method. The elongated bubble flow and transition flow are observed in the hydrophilic rectangular microchannel depending on gas and liquid flow rates. Using the LIF method, the non-uniform liquid film distribution is observed in the channel cross-section. The liquid film thickness is measured for elongated bubble flow and transition flow and compared with the Taylor law.
Simulation of conjugate heat and moisture transfer in multilayer porous materials with ventilated channels
Authors: Borodulin V Yu , Nizovtsev M I 
Published: December 2020

Abstract
A physical and mathematical model for calculating the thermal and moisture state of the facade of a building with ventilated channels has been developed. The model is based on the joint solution of a system of non-stationary differential equations of heat and moisture transfer in multilayer porous materials. In addition, equations describing heat and mass transfer in ventilated air channels are included in the model. The calculations of the thermal and moisture state of the brick wall of the building, insulated from the outside with heat-insulating panels with ventilated channels, have shown that the selected geometry of the ventilated channels provides a low level of moisture content in the facade materials.
The study of the hydrodynamics of bubble downflow at small gas-content by means of PIV / PFBI
Authors: Evdokimenko I A , Lobanov P D 
Published: December 2020

Abstract
Experiments on evaluation of the effect of bubbles on the hydrodynamic structure of two-phase bubbly downflow were carried out by means of PIV / PLIF method. Experiments were performed at Re = 5000 and gas flow rate ratio β = 1%. Data were obtained on the distribution of liquid velocity and its fluctuations, as well as on the mean bubble diameter. The results were processed using a computer bubble detection algorithm. To validate the received data, they were compared with the results obtained in [1] for the same pipe using electrochemical method. A good agreement was found for R. M. S. of liquid velocity distribution for different methods.
Influence of a soluble surfactant on the wave characteristics of a liquid film flow
Authors: Guzanov V V , Bobylev A V , Kvon A Z , Kharlamov S M 
Published: December 2020

Abstract
In this paper we present results of experimental investigation of the influence of soluble surfactant (Triton X-100) on wave characteristics of vertically falling liquid film in the range of film flow Reynolds number 25 < Re < 95. Shadowgraph technique is used to analyze wave patterns on the whole length of the test section (140 cm). Film thickness fields obtained with the help of high-speed Laser Induced Fluorescence (LIF) technique in two areas in the bottom part of test section allow analyzing statistical characteristics of the film flow. Expectedly, adding surfactant suppresses wave motion. For some surfactant concentrations the absence of waves is observed in the whole test section. For other concentrations the wave repetition rate decreases with distance from the liquid inlet. Analysis of spectral characteristics reveals that for water with some concentrations of surfactant, as for pure liquids, the steady-state three-dimensional wave regimes are observed. The characteristics in such flow regimes differ from the characteristics of pure water flow.
Experimental study of dynamic contact angles in liquid-liquid microfluidic plug flow with partial wetting
Authors: Kovalev A V , Yagodnitsyna A A , Bilsky A V 
Published: December 2020

Abstract
Partial wetting of walls by immiscible liquids in microfluidic flows is a crucial parameter for heat and mass transfer applications. Dynamic contact angles, which characterize wettability, are studied experimentally for different liquid-liquid sets in microchannels with 200×400 μm and 120×240 μm cross-sections. An appropriate algorithm is chosen for meniscus shape approximation. Cox-Voinov law is found to predict correctly advancing contact angles in liquid-liquid flow. The generalized version of Cox-Voinov law is proposed for the liquid sets with different physical properties. Based on experimental data, new dependences of receding contact angle on contact line velocity are provided for the systems with concave and convex rear meniscus of a plug.
Explosive vaporization of two- and three component liquid mixtures on microheater
Authors: Kozulin I A , Bartkus G V , Kuznetsov V V 
Published: December 2020

Abstract
The explosive vaporization of two-component mixtures of ethanol-water and three-component mixtures of acetone-ethanol-water during pulse thermal loads on the microheater during isobaric heating has been investigated. Microheater fabricated using MEMS technology presents the multilayer thin-film structure with the central Ta-Al layer heated by pulse electric current. The optical method based on measuring the laser intensity reflected from resistor surface recorded the characteristics of explosive vaporization. The dependence of the temperature of nucleation and the time of explosive vaporization on the rate of temperature growth and heat flux density are obtained.
Three-dimensional modeling of dynamics of liquid dielectric droplets on a wettable surface in the electric field
Authors: Kupershtokh A L 
Published: December 2020

Abstract
Three-dimensional non-stationary modeling of liquid dielectric droplets on a wettable surface in an electric field is performed. The distribution of the electric field is calculated by solving the equation for the electric field potential. The lattice Boltzmann method is employed to describe the hydrodynamic processes with gravitational, electrostatic, and capillary forces. A hemispherical droplet is placed on the surface of the lower electrode. Two variants of the droplet behaviour are observed. The droplet can acquire its equilibrium shape after several oscillations or elongate unlimitedly up to its destruction.
The numerical study of the flow regimes of two-phase oil and displacing agent mixtures in straight microchannels simulating a pore or crack in the rock formation
Authors: Lobasov A S , Minakov A V 
Published: December 2020

Abstract
The calculated study of the flow regimes of two-phase oil and water mixture in straight microchannels simulating a pore or crack in the rock formation was carried out. It was shown as a result of the literature survey that all modern, industrially developed methods of the oil recovery from the oil reservoirs is considered as unsatisfactory in all oil-producing countries. The average value of the final oil recovery is varied from 25% to 45%, so, it is easy to count, that residual or unrecoverable oil reserves in the subsoil reach an average of 55-75% of their initial values. Also, it was found, that the use of micro and nanotechnologies in a broad sense is one of the possible and promising ways to solve these problems. A numerical method called «Volume of Fluid» (VOF) was used to simulate the two-phase flows of oil and displacing agents in the considered microchannels. It was proposed to use the dimensionless number, called Regime number, to describe the different flow regimes of oil/water mixture and transitions between these regimes. The plug flow, the slug flow, the parallel flow and the emulsion flow regimes were observed.
Influence of stirring working area on the synthesis of freon 134a hydrate by the method of explosive boiling of liquid hydrate-forming gas in volume of water during decompression
Authors: Meleshkin A V 
Published: December 2020

Abstract
The presented work is part of a comprehensive experimental study aimed at finding the optimal operating parameters by the method of explosive boiling of liquefied hydrate-forming gas in a volume of water. The results obtained and published earlier showed the high efficiency and productivity of this method. This paper presents a study of the effect of the stirrer speed during the decompression of the working section on the gas hydrate synthesis.
Simulating waves on a horizontal liquid film entrained by a gas flow
Authors: Tsvelodub O. Yu. , Arkhipov D. G. 
Published: December 2020

Abstract
Nonlinear waves on a horizontal liquid film surface are considered. The effect of adjacent gas flow is taken into account through the data on shear stress at the film-gas interface obtained by the Boussinesq model of turbulence. A model nonlinear equation for the film thickness deviation from the undisturbed level is used to simulate nonlinear wave modes. Weakly nonlinear steady-state travelling solutions of this equation with wave numbers located in the vicinity of neutral wave numbers are constructed analytically. The evolution of periodic perturbations with wave numbers lying in the depth of the linear instability region is also considered numerically. Several typical scenarios of their evolution have been identified.
Bubble dynamics during flow boiling in a flat 0.6 mm high channel
Authors: Belosludtsev V V 
Published: December 2020

Abstract
The vapour bubble dynamics during subcooled flow boiling in a flat microchannel with the height of 0.6 mm was investigated using high-speed visualization. Nucleate flow boiling was maintained by localized heat source. The data on the bubble dynamics was compared with well-known classic growth correlation formulas. The obtained data have shown that the bubble size can reach the channel height in about 0.1 ms, which can lead to heat transfer crisis in channels with local heating.
Heat transfer in the falling liquid film on an array of horizontal tubes with MAO coating
Authors: Pavlenko A N , Pecherkin N I , Volodin O A , Kataev A I , Mironova I B 
Published: December 2020

Abstract
The paper presents investigation results on heat transfer of falling liquid films of Freon R21 on an array of horizontal tubes with porous Al2O3 coating obtained by the method of microarc oxidation (MAO coating). The microcharacteristics of samples (porosity, thickness, surface roughness) were measured. The results of measuring heat transfer coefficients on the surface of an aluminum tube with a MAO coating and a reference smooth tube were compared. Heat transfer on the surface of the tube with a porous coating was lower than on a smooth reference tube. It was shown that to intensify heat transfer on a surface with a MAO coating, it is necessary to increase the porosity of the coating and decrease its the thermal resistance.
Heat transfer at boiling on a vertical modified surface
Authors: Pavlenko A N , Zhukov V E , Slesareva E Yu 
Published: December 2020

Abstract
Modification of heat transfer surface through additive technologies (3D printing) is a very promising direction, since it allows organizing surface structures of any complexity with high reproducibility of parameters. This paper presents investigation results on heat transfer at boiling of freon R21 on a flat, vertically oriented brass surface modified with a copper coating using 3D printing. The heat-transfer surface is modified using 0.5 mm thick and 4 mm wide 3D-printed plates. The plates are made of copper spherical granules with an average diameter of 50 μm by laser welding of granules. The plates are fixed on the heat transfer surface by spot soldering. The experiments are carried out under conditions of large volume at a pressure of 0.18 - 0.21 MPa, which correspond to equilibrium temperatures of 25 - 30°C. The heat flux density varies in the range of 700 - 410000 W/m2. Experiments are carried out on the heat transfer surface before modification under the same conditions, but the surface is oriented horizontally. The experimental data show that for a modified heat transfer surface in the range of heat flux density from 1.8·104 to 3·105 W/m2, the heat transfer coefficient changes little and is approximately equal to 1·104 W/m2K. In the range of heat flux density less than 2·105 W/m2, the value of heat transfer coefficient on a modified heat transfer surface is up to 4 times greater than on a smooth horizontally oriented heat transfer surface without coating.
Effect of ionic liquid additives on temperature and pressure fluctuations during water flow boiling in microchannels
Authors: Sachi S , Zaitsev D V , Raj R 
Published: December 2020

Abstract
Overheating of high-performance electronic devices is undesired for long-term reliability. In this regard, two-phase microchannel heat sinks promise high heat dissipation within small temperature budgets using the latent heat of vaporization of the boiling fluid. However, geometrical confinement induces thermofluidic fluctuations and prohibits the use of two-phase microchannel heat sinks in practical applications. Here we for the first-time report flow boiling experiments with surface-active ionic liquid (SAIL) as an additive in water. This concept is inspired by our results of pool boiling wherein bubble coalescence was avoided with SAIL. In comparison to the water where fluctuations were apparent in the slug flow regime, temperature and pressure fluctuations were nearly mitigated up to the heat flux of 700 kW/m2 with an ionic liquid solution. The suppression of instabilities is attributed to the delay in the formation of a big vapor bubble at the inlet of microchannels due to the non-coalescing nature of bubbles formed with the SAIL solution.
The effect of air relative humidity on the intensity of evaporating of water–ethanol droplets
Authors: Sterlyagov A N , Nizovtsev M I , Borodulin V Yu , Letushko V N 
Published: December 2020

Abstract
The results of experimental studies of the evaporation of the water-ethanol droplets with various concentrations of ethanol suspended on a thread are presented. Using high-speed microphotography, we studied the dynamics of changes in the size of evaporating droplets at various relative humidity of the surrounding air. As a result of experiments, it was found that the relative humidity of the surrounding air had a significant effect on the process of droplet evaporation. For all the considered concentrations of ethanol, it was found that the higher the concentration, the shorter the evaporation time of the droplets. Generalization of the experimental data on the evaporation time of the water-ethanol droplets of the corresponding concentration of ethanol at a relative humidity of 95% was carried out.
Possibilities of heat pulse probing method for determining the phase diagram of partially-miscible liquid mixtures
Authors: Volosnikov D V , Povolotskiy I I 
Published: December 2020

Abstract
In the course of this research, the liquid-liquid equilibrium line for binary solutions characterized by the upper critical solution temperature was developed by the traditional method of visual observation and the method of heat pulse probing. The objects of study were solutions of perfluoromethylcyclohexan/hexene-1 and perfluorodimethylcyclohexan/hexene-1. Heat pulse probing mode was found, which allows us to recognize the approaching to the temperature of liquid-liquid phase separation. The possibility of pulse technique with a characteristic time of several milliseconds to determine the phase state and estimate the actual concentration of solutions in opaque vessels was revealed.
Investigation of characteristics of a pneumatic nozzle as applied to coal-water fuel spraying
Authors: Shadrin E Yu , Anufriev I S , Kopyev E P , Maltsev L I , Sharypov O V 
Published: December 2020

Abstract
A gas-droplet flow, formed by spraying liquid with a pneumatic nozzle was studied in a wide range of parameters. Information on the distribution of particle sizes was obtained using the method of shadow photography. High-speed visualization of the flow was performed. The nozzle operating regimes of a steady gas-droplet flow generation were identified.
Analysis of the effectiveness of the systems for providing thermal conditions of the local working areas based on the gas infrared emitters
Authors: Voloshko I V , Kuznetsov G V , Maksimov V I , Nagornova T A 
Published: December 2020

Abstract
One of the urgent tasks in recent years is to reduce the cost of thermal energy to ensure the thermal regime of the local working areas in the production facilities. For these purposes, the gas infrared emitters (GIE) are increasingly used, but due to the lack of an informative base that provides the regulated thermal regime of the big-sized workrooms, their implementation is constrained. The article presents the results of the experimental and theoretical studies carried out to assess the efficiency of using such systems. The measurements of the temperatures of the floor surface at the characteristic points were carried out during the operation of the emitter of average power. The article presents the results of mathematical modeling of heat transfer in the surface layer of the floor which receives the heat flux from the GIE.
Gasification and oxidation of thiophene in supercritical water fluids
Authors: Vostrikov A A , Psarov S A , Dubov D Yu , Sokol M Ya , Shishkin A V , Fedyaeva O N 
Published: December 2020

Abstract
The paper deals with the gasification of thiophene in supercritical water (SCW) at a molar ratio of H2O:C4H4S = 1:0.107, a temperature of 873–1023 K, a pressure of 30 MPa, and a holding time of 150–600 s in a batch reactor. The gases of CO2, CO, H2, CH4, and H2S were detected in the composition of SCW gasification products. The maximum degree of thiophene gasification (>99.9%) was achieved at 1023 K and 600 s. The conversion of thiophene in SCW is described by a pseudo-first-order macro kinetic equation. It was revealed that the oxidation of thiophene in H2O/O2 mixture at uniform heating of the reactor (1 K·min−1) begins at T ≈ 400 K. The lack of O2 results in the formation of soot. It is shown that the formation of sulfuric acid during the oxidation of thiophene in the H2O/O2 mixture causes corrosion of stainless steel.
Simulating glow discharge positive column parameters in neon
Authors: Demin N A , Fedoseev A V 
Published: December 2020

Abstract
The nonlocal self-consistent model for the low temperature plasma parameters in a glow discharge positive column is presented. The model implies relaxation method for the solving of the nonlocal Boltzmann equation for electron energy distribution function, continuity equation for ions distribution and Poisson equation for radial electric field. Calculations are provided for a cylindrical discharge tube used in the Plasma Kristall-4 experiments for neon as a plasma forming gas for the gas pressures of 30-70 Pa and discharge currents of 0.5-2.5 mA. Axial electric field strength, electron temperature and electron density are calculated as functions of the discharge current and the gas pressure. The results are in good agreement with the data provided by other authors.
Partial oxidation of light alkanes in microchannel
Authors: Dimov S V , Gasenko O A 
Published: December 2020

Abstract
In this work, we conducted an experimental study of partial oxidation of fuel gas, consisting of a mixture of light C1-C4 alkanes, in an annular microreactor with a catalyst deposited on the inner wall of the channel with a carbon/oxygen ratio equal to one. The experiments were carried out at different contact times in the temperature range of the reactor of 450-750°C.
Numerical optimization of plasma generation in a microwave resonant cavity
Authors: Hrebtov M Yu , Bobrov M S 
Published: December 2020

Abstract
The paper presents a numerical simulation of the hydrogen plasma generation process in a cylindrical microwave resonant cavity at moderate pressures (10 Torr). We introduce a modification to the chamber by placing several spherical dielectrics with a high permittivity at the central axis. The radii of the spheres are chosen for the Mie resonance for microwave radiation (at 2.45GHz frequency) to occur. For a dimer configuration where two spheres are placed closely together, a maximum of the electrical field magnitude is located in the gap between the spheres where the intense discharge occurs. Positioning the spheres in different spots of the chamber allows controlling the process of the microwave plasma generation. Such modification is promising for a stable discharge initiation and for preventing the discharge breaking in the microwave cavity.