Unsteady wave flows of a gas suspension with account for phase changes

A system of equations of unsteady motion of a gas suspension with account for heat and mass transfer is presented. As a result of the computational experiment, the effect of the gas vibrations at the channel inlet on the motion of the gas suspension and the rate of heat and mass transfer is studied. Specifically, it is shown that, in the considered parametric region, the gas vibrations enhance the interphase heat and mass transfer. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 3, pp. 487–492, May–June, 2000.     

Wave Motion of Solid Particles in a Pulsed Gas Flow

The effect of lowfrequency pulsations of gas on the motion of solid particles has been studied on the basis of numerical solution of equations of the dynamics of a monodisperse gas suspension with account for interphase forces of hydrodynamic drag, virtual masses, and forces due to nonstationary effects around particles. It is found that at certain parameters gas pulsations lead to enhancement of interphase heat transfer. The dependences of the time of particle residence in a pneumochannel on the frequency of gas pulsations have been obtained.     

Numerical Investigation on Turbulence and Bubbles Distribution in Bubbly Flow Under Normal Gravity and Microgravity Conditions

Two-phase flows of gas and liquid are increasingly paid much attention to space application due to excellent properties of heat and mass transfer, so it is very meaningful to develop studies on them in microgravity. In this paper, gas-phase distribution and turbulence characteristics of bubbly flow in normal gravity and microgravity were investigated in detail by using Euler–Lagrange two-way model. The liquid-phase velocity field was solved by using direct numerical simulations (DNS) in Euler frame of reference, and the bubble motion was tracked by using Newtonian motion equations that took into account interphase interaction forces including drag force, shear lift force, wall lift force, virtual mass force and inertia force, etc. in Lagrange frame of reference. The coupling between gas–liquid phases was made with regarding interphase forces as a momentum source term in the momentum equation of the liquid phase. Under the normal gravity condition, a great number of bubbles accumulate near the walls under the influence of the shear lift force, and addition of bubbles reduces turbulence of the liquid phase. Different from the normal gravity condition, in microgravity, an overwhelming majority of bubbles migrate towards the centre of the channel driven by the pressure gradient force, and bubbles have little effect on the turbulence of the liquid phase.     

Possible intensification of interphase heat and mass transfer in a gas suspension with pulsating resonance flow

Calculated motions and heat transfer of particles suspended in a gas stream pulsating at large amplitude (resonance) show that the heat transfer and the amount of heat transferred to a particle increases, while the mean flow velocity required to transport particles decreases in comparision with the corresponding values in flow without pulsation. The use of resonance oscillations is claimed to intensify interphase heat and mass transfer in a gas suspension.     

Statement of boundary and conjugation conditions for problems of heat transfer in granular beds on the basis of a two-temperature model

Physically justified boundary and conjugation conditions for problems of heat transfer in infiltrated granular beds have been formulated within the framework of the two-temperature model that takes into account the absence of interphase interaction at the boundaries. It is shown that the classical Danckwerts conditions are applicable to a gas. The problem of filtration cooling of a heat-generating granular bed over which there is an inert bed (pile-up) has been solved in a new statement. The dependence of the pressure drop in a granular bed on the mass flow rate of the gas is established. A formula to calculate the maximum temperature of particles is obtained. The region of applicability of the one-temperature model is determined. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 6, pp. 98–106, November–December, 2006.     

Characteristic features of the process of mixture formation upon fuel injection into a high-temperature air flow

Physical models of the processes of interphase heat and mass transfer and computational techniques based on them are suggested. The problem of the interaction of fuel droplets with a high-temperature air flow is solved numerically. It is shown that injection of a fuel by a spray atomizer may cause a substantial change in the gas temperature. With pneumatic spraying of a fuel by a cold air jet the influence of interphase exchange on the characteristics of the main flow is insignificant. Upon injection of a hot spraying air the influence of fuel injection on the formation of temperature fields is more appreciable. However, here the gas is cooled less than in the case of spraying by a jet. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 2, pp. 250–258, March–April, 2008.     

The propagation of linear waves in humid,gas-saturated media

The process of propagation of acoustic waves in humid, gas-saturated porous media is investigated in a two-velocity approximation. A dispersion relation is derived, which includes interphase interaction forces and heat transfer between the skeleton of porous medium, liquid, and gas. The effect of heat transfer between the phases on the propagation of the “fast” and “slow” waves is included by means of heat equation     

Specific features of the processes of drying and evaporation in the absence of an analogy between external heat and mass exchange

The impossibility of constancy of evaporation and wet-bulb temperatures in the absence of analogy between the processes of interphase heat and mass transfer has been shown. It has been noted that, in the general case, the wet-bulb and adiabatic saturation temperatures depend on the process hydrodynamics and their values do not always coincide. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 2, pp. 62–68, March–April, 2006.     

Interphase heat transfer between low-temperature plasma and disperse materials in a plasma reactor

Data on heat transfer of plasma flows in a cylindrical channel of a reactor with a three-jet mixing chamber are analyzed. Experimental results are also presented on interphase heat transfer between plasma flows and disperse particles, and two possible methods of generalization of the results are shown. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 70, No. 3, pp. 462–468, May–June, 1997.     

Problems of the radiation theory of heat and mass transfer in solid and liquid media

A mechanism and foundations of the radiation theory of heat and mass transfer that are based on the transfer of energy by photons emitted and absorbed by particles of the substance are presented. Equations of heat and mass transfer that transform, in the limit, to known phenomenological equations, energy distribution functions of atoms and their degrees of freedom in diffusion processes, and expressions for the specific heat and the diffusion coefficient that yield, as particular cases, the known Debye, Arrhenius, and Einstein formulas have been found.z Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 4, pp. 851–859, July–August, 2000.     

Determination of the local parameters of heat- and mass transfer in deep cooling in a tube bundle of fuel combustion products of thermal power plants

The specific features of heat and mass transfer of flue gases deeply cooled below the dew point of the steam contained in them have been analyzed. A method of determining the local parameters of heat and mass transfer in surface condensation heat utilization units is suggested. An analysis of the local characteristics of cooled and condensing combustion products allows one to study the relationship between the heat and mass transfer parameters and justify the optimum geometric characteristics of condensation heat utilization units. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 82, No. 2, pp. 289–295, March–April, 2009.     

Effect of the phase transformations on acoustics of a mixture of gas with vapor,droplets, and solid particles

The propagation of acoustic waves in the two-fraction mixtures of gas with vapor, droplets, and solid particles of different materials and sizes with phase transformations has been studied. Nonstationary and nonequilibrium effects of the interphase exchange of the impulse, mass, and heat have been taken into account. A system of the differential equations of the motion of the mixture has been presented, and the dispersion relation has been deduced. The high- and low-frequency asymptotics of the attenuation coefficient have been obtained and analyzed. The effect of the heat and mass exchange on dispersion and dissipation of acoustic waves in the two-fraction mixtures of gas with vapor, droplet, and solid particles has been studied.     

Heat and mass transfer in the heterogeneous system matrix-inclusions under pulse electron-beam processing

A mathematical model of pulse electron-beam processing of a heterogeneous material with allowance for the fact that each phase (particles and the matrix) possess its own properties and thus is characterized by its own concentration and temperature has been proposed. The processes of transfer of heat and mass in particles and the matrix and exchange processes between the phases have been taken into account. An example of a partial problem enabling one to calculate the coefficients of heat and mass exchange between the phases as functions of the temperature and the particle size has been given. The influence of the character of the external heat flux on the temperature and concentration fields in particles and the matrix has been illustrated. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 1, pp. 147–156, January–February, 2008.     

Calculation of turbulent momentum transfer in a solid phase based on equations for the second and third moments of particle-velocity pulsations

A chain of transfer equations for the second and third moments of dispersed-phase-velocity pulsations in the anisotropic field of energy of random particle motion is obtained based on the computational procedure developed. The interphase and interparticle interactions are allowed for. The turbulent characteristics of the gas are calculated on the basis of a one-parameter turbulence model generalized to the case of two-phase turbulent flows. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 2, pp. 60–70, March–April, 2007.     

Use of integral boundary-layer theory for solving conjugate problems of heat transfer in channels of high-power plants

The solution of the conjugate problem of convective-conductive heat transfer in the channels of power plants is presented. The problem of convective heat transfer in the gas phase is solved by the integral theory of heat transfer. A one-dimensional problem of conductive heat transfer in the material of the wall is solved by the finite-difference method. Relative laws of heat and mass transfer and friction are obtained by numerical integration with respect to the boundary-layer thickness. The effect of the material and geometry of the wall on the level of problem “conjugation” is studied. Translated from Inzhenemo-Fizicheskii Zhurnal, Vol. 73, No. 1, pp. 131–137, January–February, 2000.     

Features and efficiency of interphase heat and mass transfer with a pulsation organization of the process

It is shown that, with a low-frequency organization of transient interphase heat and mass transfer, its intensity is higher than in the case of a stationary organization. Algorithms for computation of the interface and the time of phase contact in jet mixing of mutually insoluble media are given. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 71, No. 2, pp. 317–322, March–April, 1998.     

Solutions of the type of traveling waves including hyperbolic heat transfer

Solutions of the type of traveling waves defining heat transfer and gas motion with account for the relaxation of the heat flow have been obtained and investigated. A comparative analysis of solutions of both types has been carried out. It is shown that, in the case where the relaxation of the heat flow is taken into account, solutions of the type of traveling waves can exist for any relation between the velocity of the traveling wave and the velocity of sound. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 2, pp. 290–302, March–April, 2008.     

Structure of pulse dispersed jet upon change in its frequency characteristics

Intensities of heat and mass transfer for continuous and pulse spray in interaction with the vertical surface of a heat exchanger differ considerably from one another when the time-averaged spraying rate [1–6] is kept constant. This difference is determined by characteristic properties of gas-drop flows of continuous and pulse sprays and their interaction with the heat-exchanging surface. Results of experimental studies of basic hydrodynamic parameters of pulse drop flow are presented: velocity and drop size dispersions, spectral characteristics of the kinetic energy of the spray at various distances from the source, and influence of the gas concurrent flow on these parameters. A difference in the heat transfer is shown upon variation of the pulse drop flow parameters from the heat transfer at the stationary supply of spray.     

Numerical modeling of the aerodynamics, heat exchange, and combustion of a polydisperse ensemble of coke-ash particles in ascending axisymmetric two-phase flow

A two-dimensional stationary model of motion, heat and mass exchange, and chemical reaction of polydisperse coke and ash particles in ascending gas-suspension flow has been constructed with allowance for the turbulent and pseudoturbulent mechanisms of transfer in the dispersed phase. The system of equations that describes motion and heat transfer in the solid phase has been closed at the level of the equations for the second moments of velocity and temperature pulsations, whereas the momentum equations of the carrying medium have been closed using the equation for turbulent gas energy, which allows for the influence of the particles and heterogeneous reactions.     

Heat transfer in a horizontal coiled pipe in a transient regime and at a near-critical pressure of a fluid

It has been established that in the region of pressures close to a critical one, heat transfer in a transient regime of motion of a single-phase flow in a horizontal coil pipe changes nonuniformly over the cross section of the perimeter. The main factors here are the influence of inertia forces and of free convection. Equations to calculate the heat-transfer coefficient are suggested. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 5, pp. 892–896, September–October, 2008.