Abstract Measurements of the heat capacity of pure magnesium and ultralight magnesium–lithium alloy with a Li content of 30 at. % were performed by means of differential scanning calorimetry in the temperature range of 300 K to 825 K. The estimated error of the data obtained was 2–3%. The corresponding temperature dependences of the heat capacity were constructed. Peculiarities were revealed in the

Abstract The paper substantiates selection of boundary conditions for correct modeling of gas motion in a turning-and-expanding flow. The choice is based on comparison of calculation results and experimental data. Measurements of average and pulsation values of flow velocity were carried out by the method of laser Doppler anemometry. The numerical modelling was performed on the basis of known modern

Abstract This paper presents a theoretical analysis of methods for modeling of industrial processes and a new approach to modeling and simulation of industrial processes at lack of information on the process mechanism.

Abstract Characteristic features of mixing of and heat transfer between a 2D counter-flowing wall jet and a main-stream flow were studied numerically. In the initial section of the flow above the working wall, an extended zone of recirculation flow appears after the reversal of the jet. A local increase in the velocity is observed between the upper wall of the channel and the separation zone. The size

Abstract Combustion of pyridine in rich, stoichiometric, and lean mixtures of C5H5N/O2(\(\rho_\mathrm{ Py}=0.11\) and 0.15 mol/dm3; \(\rho_\mathrm{ O_2}=0.71\)–1.18 mol/dm3) diluted with argon or water vapor was investigated at uniform heating of the reactor to 823 K. Analysis of the time dependences of the temperature and pressure of the reaction mixtures revealed differences in the mechanisms of

Abstract Absorption refrigeration technology, which enables utilization of low-grade thermal energy such as solar energy and waste heat, has attracted much attention in the past few decades. It is presently accepted that carbon dioxide (CO2)–ionic liquids (ILs) as new absorption working pairs have great application prospects. The capacity of absorption of CO2 into ILs depends mainly on the species

Abstract This paper discusses the use of volumetric enhancers in ducts of heat exchangers for high-viscosity liquid media, which ensure the transition from a laminar flow to a turbulent one. Small random metal packings with a large free volume and an equivalent diameter of 5 to 25 mm were used as volumetric enhancers. It has been found that volumetric enhancers provide an increase in the heat transfer

Abstract The backward-facing step flow is seen in applications in our daily life: the high attack angle at airfoil, the separation flow behind a vehicle, the flow in a gas turbine, and the flow around a boat or building. In view of increasing the heat and mass transfer, control of the backward step region is important. In this study, the heat transfer and flow structures with turbulence of step corner

Abstract A spectral-based computational algorithm is presented, showing the effects of rotation and curvature on a fluid flow with natural and forced convective heat transfer (CHT) in a rotating curved rectangular channel with an aspect ratio of 3 and curvature ratio ranging from 0.001 to 0.5. The bottom wall of the channel is heated, with cooling from the ceiling; the vertical walls are thermally

Abstract With the ever-increasing societal demands to control the climate change, various policy and regulatory actions are coming out to reduce or restrict refrigerants with non-zero ozone depletion potential (ODP) and high global warming potential (GWP). For low pressure centrifugal chiller applications, R123 with non-zero ODP and R245fa with high GWP, will be phased out. For the current study, the

Abstract Experimental data on the diffusion combustion of a round hydrogen microjet in a concurrent coaxial flow are presented. The effects on the combustion of a concurrent air flow and an air flow premixed with nanopowder of TiO2 are of interest. The hydrogen microjet emanates from a round micronozzle, which is surrounded by a coaxial slit to produce the concurrent flow. Combustion events found in

Abstract This paper presents the results of an experimental study of the formation of large-scale non-uniformity of liquid flow on a RSR metal random packing of 0.47 m in diameter and a Sulzer 500X structured packing of 0.6 m in diameter. The experiments on the RSR packing were carried out with water without vapor flow for the superficial velocity of the liquid varying as \(3\cdot 10^{-3}< L_{0}<12\cdot

Abstract The paper presents results of experimental research on the influence of the mass flux on the heat transfer during flow boiling of subcooled de-ionized water in conditions of three-side heating in a system of two microchannels with an aspect ratio of 13.3. The horizontal experimental section was a copper block with two microchannels 2 mm wide, 0.15 mm deep, and 16 mm long; the inner surface

Abstract This article presents an experimental study of colloidal solutions with a focus on the surface properties of colloidal solutions in view of their further application in pulsating heat pipes. Using a tensiometer and the Welhelmi plate method, we carried out a series of measurements of surface tension for various concentrations and temperatures of colloidal solutions with three promising surfactants:

Abstract The paper presents results of an experimental study of the structure of gas-liquid flow in a slit microchannel with a cross section of \(200\times 1205\) \(\mu\)m and an aspect ratio of 1:6. The liquids used were ethanol and distilled water, and the gas was nitrogen; a cross-junction mixer performed the mixing. In the wide ranges of gas and liquid flow rates J\(_\mathrm{liq}=0.02\)–0.1 m/s

Abstract It is shown that theoretical models elaborated for polymer microcomposites are not capable to describe variation of the melt viscosity of polypropylene/globular carbon nanocomposites at change in the nanofiller contents. Then a fractal model of viscosity is proposed, which takes into account the sizes of nanofiller aggregates and their surface structure. This model shows a good agreement with

Abstract Climate change concerns have made the engineering community care more about environmentally friendly working fluids. Currently, the fluid R134a, which has a high global warming potential, is widely used in chiller applications. In this study, several low GWP working fluids, R450A, R513A, R1224yd(Z), and R1234ze(E), are investigated numerically as alternatives to R134a for comparison of their

Abstract Miniature fiber optic sensors were used for detection of initial boiling-up of uniformly superheated liquid in the capillary of a bubble chamber. The possibility of local boiling-up activation by a laser pulse at a single-mode fiber end with a diameter of 9 \(\mu\)m was shown. The object of the study was \(n\)-pentane superheated at 82 K with respect to the liquid-vapor equilibrium temperature

Abstract We scrutinize a steady incompressible natural-convection flow between vertical walls. The modelling equations are solved analytically. Basing on plotted graphs, we discuss the impacts of the chemical reaction, Hall current, and radiation on the fluid velocity, induced magnetic field, current density, temperature field, and concentration. Both the radiation parameter and heat source parameter

Abstract The article presents measurements and calculations of selected gas phase parameters in a liquid metal-gas flow in a magnetic field. The gas phase were argon bubbles, while the liquid metal was the GaInSn eutectic. The flow velocities of the gas bubbles, their equivalent diameter, and drag coefficient values were calculated for different argon inlet nozzles. The boundaries between the rise

Abstract This paper reviews counterflows, double counterflows, and circulation cells in vortex motion and argues that all these seemingly paradoxical phenomena can be caused by a common swirl-decay mechanism (SDM). It is shown that the SDM explains (a) the counterflow of water and oil in hydrocyclones, (b) the elongated counterflow of hot and cold air in vortex tubes, (c) the double counterflow occurring

Abstract This paper presents experimental results on heat transfer efficiency on a flat circular heat-release surface modified using additive technology. A porous plate 500 \(\mu\)m thick, 3D-printed from copper spherical granules with an average diameter of 50 \(\mu\)m, was fixed by means of resistance soldering on a heat-release brass surface of 20 mm in diameter. The heat transfer was investigated

Abstract The article outlines the relevance of production of dried products using a mobile solar dryer plant with mobile shelving. For intensification of the drying process, the convection of the drying agent flow in the proposed design of drying chamber was studied via numerical solution of the Navier–Stokes equations. As a result, a graphical interpretation of isolines of moving stream of drying

Abstract Accurate prediction of the temperature and various species concentrations at combustor exhaust is very important. This work presents numerical investigations of a can-type combustor used in industrial gas turbines for power generation. The methane-air combustion process is investigated using models based on Reynolds-averaged Navier–Stokes (RANS) equations. Enhancement of the mixing of air

Abstract This article is devoted to adhesion forces of polymers modified with silica nanoparticles, as well as studying changes in the surface relief of polymers modified with nanopowders of silicon dioxide, using the atomic force microscope. Enhancement of adhesion forces of nanocomposite samples of polymers containing 1 and 3% of silica nanoparticles was observed despite the non-modified nature of

Erratum

Abstract An experimental investigation of flow pattern regimes and mixing inside a T-type microchannel for different inlet flowrate ratios was carried out. Seven flow pattern regimes were obtained experimentally. Partial penetration of the flow into the opposite input channel with occurrence of one vortex was shown by Rahimi et al. [8]. We experimentally demonstrate arising of two vortex structures

Abstract Characteristics of gas-droplet flow created by spraying a liquid using an advanced pneumatic nozzle for suspension fuel were studied experimentally. The measurements were made using the shadow photography method. On the example of water, the disperse composition of the gas-droplet flow, jet expansion angle, and flow structure stability were determined for different regimes. It was shown that

Abstract The high heat flux from electronic devices such as projectors, LEDs, or high power chips requires effective cooling methods at heat dissipation in a limited space. In the present study, the heat and fluid flow characteristics of isothermally heated objects located in a duct were numerically analyzed in order to investigate cooling of electronic devices. The channel had three objects attached

Abstract We study a two-dimensional flow over a cylinder and three ellipses with the aspect ratio \(a / b = 2.04\), \(3.65\), and \(5\) at a Reynolds number \(Re = 100\) based on the inflow velocity and hydraulic diameter using a direct numerical simulation (DNS) and linear stability analysis. The DNS shows that increase in \(a / b\) leads to stabilization of the flow due to decrease in the recirculation

Abstract The paper presents results of an experimental study of the effect of pin microstructures on the wetting front propagation and its structure under adiabatic conditions and on strongly pre-heated surfaces, as well as the heat transfer and critical heat fluxes under steady-state heat release with liquid nitrogen film flowing. The surface structuring was created by the deformational cutting method

Abstract The effect of surface wettability and pressure on multiscale heat transfer characteristics at liquid boiling was studied. The experiments were carried out at saturated water boiling on surfaces with different wettability in the pressure range of 8.8–103 kPa. The usage of transparent ITO film heater deposited on a sapphire substrate and high-speed visualization showed the nucleation site density

Abstract The task of intensifying film evaporation and boiling is extremely relevant. It is of great interest for technologies of chemical, oil refining, food, cryogenic, and refrigeration industries. To date, a lot of experimental material has been accumulated in this area. However, correct physical models are still missing because of the complexity of describing the hydrodynamics and heat and mass

Abstract When submersible temperature sensors (TSs) are used to measure non-stationary temperatures or applied in systems for automatic control of non-stationary temperatures, it is necessary to know dynamic characteristics of the TSs. In Russian standards, dynamic characteristics of industrial TSs are specified only by the index of thermal inertia. Dynamic characteristics of some types of industrial

Abstract Two-phase and two-component flows in microchannels being very promising for applications in areas such as microfluidics, microelectronic cooling, and heat exchange systems, there is a need to study characteristics of these flows and new effects associated with microchannel flows. This work presents an experimental and theoretical study of waves in stratified and annular flow regimes for a

Abstract This article presents the results of study of dibenzothiophene (DBT, the fuel equivalence ratio \(\varphi = 0.94\)–1.01) oxidation in a medium of dense water vapor or argon at uniform heating (1 K/min) to 853 K of a tubular reactor made of stainless steel. The oxidation of DBT was found to proceed by the mechanisms of heterogeneous and homogeneous reactions. From the dynamics of the temperature

Abstract This study investigates the mixed convection heat transfer characteristics of micropolar nanofluid containing motile microorganisms as it is passing over a stretching sheet. The governing equations of the fluid flow and boundary conditions are solved via similarity analysis using the fourth-order Runge–Kutta method. To verify the accuracy and validity of the method, the results are compared

Abstract Based on an algebraic model of Reynolds stresses and fluxes, a numerical model of the dynamics of a flat localized region of turbulent perturbations of non-zero buoyancy in a linearly stratified medium was constructed. The evolution of a weakly heated turbulent spot was considered. Presence of non-zero buoyancy leads to increase in the geometrical dimensions of the turbulent spot and generation

Abstract The paper presents a joint experimental study of synergic effects on C/SiC composites. Outgassing characteristics are investigated in experimental tests. Correlation between these phenomena and variation in thermal properties of C/SiC composites is studied by means of the inverse method and scanning electron microscope (SEM) analysis.

Abstract Experimental studies on control of turning-and-diverging flow have been carried out; detailed diagnostics of averaged and turbulent characteristics have been made. Numerical modeling and comparison with experimental data based on known up-to-date turbulence models have been performed; comparative analysis of models has been done. The findings may be useful for determination of applicability

Abstract The thermal conductivity and thermal diffusivity of europium (Eu) in the solid and liquid states, including the melting-crystallization region, have been measured for the first time by the laser flash method in the temperature range from 298 to 1625 K. The error of measurement of the heat transfer coefficients was 4–6%. The data for the temperature regions of 298–550 K and 965–1625 K were

Abstract The paper presents results of experimental study of an upward flow in a vertical rod bundle consisting of nine rods arranged in a square. Spacing grids were used to keep the bundle geometry. The experiments were performed in single-phase and bubbly flows using an electrochemical technique. A local wall shear stress probe was mounted in the central rod. The dependence of the local wall shear

Abstract The paper addresses a mixed convection boundary layer flowing on a horizontal surface embedded in porous medium with exponentially decaying internal heat generation (IHG) and internal mass generation (IMG) from a specific component with chemical reaction in order to investigate the heat and mass transfer characteristics. Corresponding similarity solutions are used to reduce the governing partial

Abstract In this study, the motion of three phases (gas, liquid, and solid) and characteristics of particle removal inside the liquid chamber of industrial scrubbing tower were studied through unsteady simulations using the VOF-DPM coupled model. The study focused on the motion of dust particles in a three-dimensional computational domain of \(4200\times 8400\) mm. After the system achieved stability

Abstract Methods for determination of thermal properties of various materials, including iron ore, are adequately covered in the relevant literature. They rely, as a rule, on certain solutions to the problem of heat conductivity without consideration of internal heat sources that occur in the body of sample under study if the heating (cooling) process is accompanied by various thermochemical and phase

Abstract The article presents the results of an experimental study of the turbulent structure of flow over a two-dimensional hydrofoil, which is a scaled-down model of guide vane of high-pressure hydraulic turbine. The study was carried out for four regimes of cavitating flow, covering the cases of cavitation-free flow, quasi-steady sheet-vortex cavity with detachments of small-scale cavitation clouds

Abstract An experimental investigation has been carried out regarding the effect of microstructural parameters of capillary porous coatings produced by directed plasma spraying on the heat transfer and critical heat fluxes during boiling of nitrogen at steady-state heat generation on horizontally-oriented tubular heaters of 3 and 16 mm in diameter. For both the tube diameters, the highest increase

Abstract The possibility of increasing the reactivity of low grade Kansk-Achinsk brown coal 2 BR from the Irsha-Borodino deposit due to mechanically activated micronizing by means of special mill disintegrators has been shown on the 5-MW experimental firing stand at the Institute of Thermophysics SB RAS (IT). This coal is used in the coal-fired PK-38 boiler of station 2B of the Krasnoyarsk State District

Abstract A hydrodynamic model of motion of compressible liquid in a complex profile pipeline has been built and the resulting coupled equations have been solved. The dynamics of the liquid flow rate was determined in dependence on parameters of the system and inlet and outlet pressure variation.

Abstract This paper presents the experimental and numerical results of modeling the local structure of gas-liquid downflow in a vertical pipe. The measurements were carried out using the PIV/PLIF system “Polis-PIV,” developed at the Institute of Thermophysics SB RAS. The numerical model is based on the use of a two-fluid Eulerian approach. The effect of changes in the diameter of air bubbles on the

Abstract Convection in a sessile droplet of water in a laminar air flow was studied. The experiments were conducted in the air velocity range \(U_{1}=2\)–5 m/s. The experimental data are compared with approximate numerical solutions and an approximate analytic solution made for small numbers Re for both the liquid and gas phase. It has been shown experimentally and theoretically that the maximum velocity

Abstract One of the key challenges to model condition monitoring is; how to suitable match the level of detail of the model description of the diagnostic requirements. To do so, a counter-current heat exchanger of the tire factory was investigated. Moreover, a two-stage grey-box modelling was deployed. The modelling is deployed in a discrete state space, relying on a combination of prior knowledge

Abstract Operating characteristics of aeronautic and marine vehicles, as well as hydraulic machines designed for various purposes are largely affected by flow separation. Therefore, control of separated flows is an extremely important problem for modern aviation and marine engineering. Based on dynamometric measurements of forces and torque acting on model hydrofoils and the ship rudder, jet control

AbstractThe coaxial cylinders method was used to measure the thermal conductivity of the R-125/R-134A (39/61) gas mixture. The experiments were carried out in the temperature range of 320–415 K and in the pressure range of 0.1–1.8 MPa. Coefficients were determined for an equation describing the thermal conductivity as a function of pressure and temperature. Thermal conductivity on the dew line and

AbstractGas hydrates are a special state of matter because of their properties to concentrate significant volumes of gas in themselves. Different hydrate forming gases have different thermobaric regions of existence. These properties of gas hydrates create a prospect for developing promising industrial technologies for their synthesis and dissociation. This paper reflects the effects of surface-active

AbstractThe article presents the results of comparative investigations of operation modes of the DKVR 10-13 steam boiler system. The investigations were performed in two different modes. In the first mode, the boiler worked only on the gas fuel, whereas in the second mode, the boiler worked on the gas fuel and mazout simultaneously. Each mode requires considering the economic and ecological conditions

AbstractWe present a numerical model suitable for simulation of shock or blast waves passing through a cloud of water droplets. The model takes into account the droplet breakup, radiation, and evaporation effects. The gas phase (a mixture of air and water vapor) is solved within an Eulerian framework with a set of compressible transport equations. The disperse phase (water droplets) is represented

AbstractThis work investigates the motion of the liquid metal on the surface of a heated cylindrical rod. Experiment data are presented, and computational models modified in accordance with the experimental results are described. Exploration of the motion of molten metal over the surface of fuel column simulator both in gravitational runoff and at gas blowoff involved high-speed recording. Formation

AbstractSeveral challenges coexist in the field of flow boiling in microchannels, ranging from high superheat required for boiling incipience to boiling instabilities and early dryouts. The aim of this study is to mitigate or solve some of the challenges and develop an image-processing algorithm for analysis of boiling oscillations in multiple parallel channels. The experimental results were acquired

AbstractThe paper analyzes steady laminar boundary layer flow of low-conductivity Casson fluid over a stretching/shrinking sheet subjected to a transverse magnetic field in the presence of suction/injection when the fluid far away from the surface is at rest. This flow problem is mathematically modelled and the non-Newtonian fluid under consideration obeys the rheological equation of state by the Casson