Begell House Inc.
Heat Transfer Research
HTR
1064-2285
34
5&6
2003
Heat and Mass Transfer in Formation of Diverse-Function Coats by a Supersonic Heterogeneous Flow
7
P. V.
Nikitin
Moscow State Aviation Institute (Technical University), Moscow, Russia
A. G.
Smolin
Moscow State Aviation Institute (Technical University), Moscow, Russia
The paper presents the laws governing the mechanism of the formation of surface coatings by the low-temperature gas-dynamical method. It is shown that the level of the kinetic energy of the particle plays a deterministic role in the process of coating formation by a supersonic two-phase flow. The required magnitude of the kinetic energy depends uniquely on the kind of a coating, its predictable properties, and the properties of the substrate. The analysis of the dynamics of collision between a hard particle and an obstacle is carried out for a velocity of particles of about 1000 m/sec. An equation of energy balance (in the zone of impact) is derived and solved.
Heat Transfer to Liquid Metal Flow in a Porous Saturated Circular Tube with Uniform Wall Temperature: An Exact Solution
6
Kamel
Hooman
Mechanical Engineering Department, Persian Gulf University, Bushehr 75168, Iran
A. A.
Ranjbar-Kani
Mechanical Engineering Department, Faculty of Engineering, Mazandaran University, PO Box 484, Babol, Iran
Arash
Ejlali
Reservoir Research Center, Azarab Co.; and Reactor-Saz Co., Engineering Deptartment, Tehran, Iran
A theoretical analysis is presented to investigate the thermal development of liquid metal forced-convection flow in a circular tube filled by a saturated porous medium, with uniform wall temperature and with the effects of axial conduction included. The Darcy model is employed. The analysis leads to expressions for the local Nusselt number as a function of the dimensionless axial coordinate and the Peclet number.
Using a Porous Segment to Increase Thermal Efficiency by Converting Gas Enthalpy to Thermal Radiation in High-Temperature Industrial Furnaces
8
Kamel
Hooman
Mechanical Engineering Department, Persian Gulf University, Bushehr 75168, Iran
Mofid
Gorji-Bandpy
University of Mazandaran
M.
Mahdavi-Hezaveh
Renewable Energy Ward, Atomic Research Center, Tehran, Iran
In this paper, effect of a porous segment in the outlet of a hightemperature one-dimensional duct such as an industrial furnace is investigated numerically. The target was to increase the efficiency of these furnaces containing high-temperature gases by undertaking energy conversion and to recover the energy of the gas flows inside the duct. Enthalpy of high-temperature gas was converted to thermal radiation by means of this porous segment. The two-flux method was taken into account for this problem and to perform the numerical procedure the forth order Runge–Kutta scheme was utilized. The porous layer was supposed to have a high-porosity causing a high area/volume ratio and also it was considered highly emissive to radiate absorbed convective energy. Solving the energy equation numerically along and outside the porous segment simultaneously, it was shown that a huge part of convective energy could be converted to recovered energy in the form of thermal radiation. It was shown that due to massive difference between the inlet and outlet temperature of the porous segment, heat could be transferred to upstream. Also it was seen that, the more optic length is the higher efficiency is gained.
Enhancement of Heat Transfer in the Freeboard Volume of a Fluidized and Circulating Fluidized Beds: Influence of Turbulence
14
G. I.
Pal'chonok
Academic Scientific Complex "A. V. Luikov Heat and Mass Transfer Institute," National Academy of Sciences of Belarus, Minsk, Belarus
A.
Borodulya
A. V. Luikov Heat and Mass Transfer Institute, National Academy of Sciences of Belarus, Minsk, Belarus
C.
Breitholtz
Department of Energy Conversion, Chalmers University of Technology, S-412 96 Goteborg, Sweden
B.
Leckner
Department of Energy Conversion, Chalmers University of Technology, S-412 96 Goteborg, Sweden
We consider the problems of modeling, calculation, and design of fluidized-bed and circulating fluidized-bed combustors. We carried out some runs of measurements and presented experimental and calculated results. We recommend a relation for estimating the coefficients of mass transfer in the freeboard region of a fluidized bed and a circulating fluidized bed.
Heat and Mass Transfer in Gas-Disperse Systems Exposed to Intense Radiation
12
Konstantin
Volkov
Kingston University London
Vladislav
Emelyanov
Physical and Mechanical Department, Baltic State Technical University, Saint Petersburg, 190005, Russia
Li
Solong
"VOENMEKH" Baltic State Technical University, St. Petersburg, Russia
Models of shock-wave processes induced by intense radiation fluxes in gas-disperse systems have been developed. The continuum coupling penetration model is used to simulate mixture motion. The problem of interaction of radiation with an individual particle is formulated to calculate source terms connected with the interphase mass, momentum, and energy transfer. Solution of a microproblem and of the problem of calculation of gasdynamic variables are found in parallel. Agreement of micro- and macrolevel problems ensured with the aid of iteration interrelationship in a computational procedure. Lengthwise distributions of mixture parameters and influence of different factors on the energy influx efficiency have been investigated.
Formation of Vapor Nuclei in a Superheated Liquid on Gas Inclusions
7
G. V.
Ermakov
Institute of Thermophysics, Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia
S. A.
Perminov
Institute of Thermophysics, Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia
E. V.
Lipnyagov
Institute of Thermophysics, Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia
The possibility of existence of a steadily equilibrious vapor-gas nucleus in a highly superheated liquid is shown. Phenomenological and kinetic models of its fluctuation-diffusion growth are proposed. Results of the calculation are in good agreement with the data of experiment.
The Model of Polydisperse Nonisothermal Flow with Coalescence and Breakup of Drops
7
V. A.
Naumov
Kaliningrad State Technical University, Kaliningrad, Russia
A one-dimensional model of polydisperse flow with coalescence and breakup of drops in a vertical column is suggested. The concept of N fractions of drops is used. A calculation method for the liquid clean rate of gas pollution in scrubbers has been developed. The results of calculation of the volumetric mass transfer factor are compared with experimental data.
Wide-Range Equation of State of Matter with Account for Evaporation, Dissociation, and Ionization
8
F. N.
Borovik
A. V. Luikov Heat and Mass Transfer Institute, National Academy of Sciences of Belarus, Minsk, Belarus
G. S.
Romanov
A. V. Luikov Heat and Mass Transfer Institute, National Academy of Sciences of Belarus, Minsk, Belarus
A semiempirical wide-range equation of state of granite and water based on decomposition of pressure and energy into a cold component and thermal nuclear and electronic components is presented. The thermal electronic components of energy and pressure are calculated with the Thomas–Fermi model which allows one to take into account both thermal and pressure ionization. The description of the cold isotherm is based on experimental data. Evaporation and dissociation are taken into account with corresponding addends in the free energy. Condensed state is described within the framework of the Debye approximation. The curves of coexistence of condensed and gas phases are calculated. Isoenergy curves in the density–temperature and density–pressure phases are considered.
Calculation of Vapor Content of a Two-Phase Flow in Water Boiling on Horizontal Tubes (Single Tubes and Tube Bundles)
10
V. D.
Chaika
Far Eastern Technical Institute of Fish Industry, Vladivostok, Russia
Calculation of vapor content of a two-phase flow is made for water boiling on single horizontal copper tubes 10, 16, 24, 34, and 70 mm in diameter and also on a five-row-bundle of copper tubes 34 mm in diameter at a pressure of 26 p q — onset of nucleation and up to 200 kW/m2. The characteristics of the process of boiling simultaneously in two directions are obtained by high-speed filming; the formulas are obtained. Empirical nondimensional correlations are based on various experimental results. The formulas take into account the effect of side tubes and a tube pitch.
Film-Boiling Heat Transfer of Liquid Nitrogen and Hydrogen in Tubes at Large Liquid Subcoolings
12
Guenrikh A.
Dreitser
Department of Aviation-Space Thermal Techniques,
Moscow Aviation Institute, Volokolamskoe shosse, 4, Moscow, 125993, Russia
V. P.
Firsov
Moscow Aviation Institute (Technical University), Moscow, Russia
I. V.
Antyukhov
Moscow Aviation Institute (Technical University), Moscow, Russia
A. A.
Kurilenko
Moscow Aviation Institute (Technical University), Moscow, Russia
The results of experimental investigation of film boiling of liquid nitrogen in vertical tubes of a diameter of 9.7 mm and 20 mm and liquid hydrogen in tubes of a diameter of 70 mm are presented. The experiments were carried out under the conditions of unsteady cooling of the test section in the range of variation of mass flow velocity from 500 to 15,000 kg/(m2·sec), pressure form 5 to 20 bars, dimensionless liquid subcooling from 0.05 to 0.6, and wall temperature from 200 to 900 K. It is shown that under the conditions of large subcoolings of liquids the slug annular vapor–liquid regime is realized and the existence of two basic regimes of heat transfer is possible: self-similar and non-self-similar with respect to the temperature of a heat-transfer surface. The generalizing dependences on heat transfer in slug self-similar annular film boiling regime of liquid nitrogen and hydrogen are obtained.
Modeling of the Effect of the Temporal Shape of a Laser Pulse on the Processes of Metal Treatment
9
U. S.
Semmler
Society of Scientific-Technical Development, Kemnitz, Germany
V. I.
Mazhukin
Institute of Mathematical Simulation, Russian Academy of Sciences, Moscow, Russia
V. V.
Nosov
Institute of Mathematical Simulation, Russian Academy of Sciences, Moscow, Russia
The paper presents the results of mathematical simulation dealing with unsteady effects induced by variation of temporal energy distribution in a laser pulse for the so-called engineering range of intensity 104–107 W/cm and duration 10–6–10–2 sec. It is established that passing from a rectangle to Gaussian shape of laser pulse, the dynamics of a number of the process parameters, particularly, the melting front velocity and the melt layer thickness change significantly. The maximum melt thickness for Gaussian pulses is reached after the laser pulse termination and exceeds the value of steady-state estimation by 1–2 orders of magnitude. However, this approximation appears to be quite accurate to predict thickness of the layer evaporated.
Conductive-Convective Heat Exchange in Disperse Systems with Suspended Particles
8
Yu. S.
Teplitskii
Academic Scientific Complex "A. V. Luikov Heat and Mass Transfer Institute," National Academy of Sciences of Belarus, Minsk, Belarus
A film model of heat exchange of a disperse medium with a macrosurface under the conditions of ascending motion of a gas is suggested. A model equation is obtained which yields the dependence of the heat-transfer coefficient on determining factors. It is used to correlate experimental data in different systems: fluidized bed, circulating fluidized bed, and vertical pneumatic transport.
Growth of a Vapor Film on the Heater Immersed into a Highly Conducting Liquid
11
A. A.
Gorbunov
Institute of the Problems of Mechanics, Russian Academy of Sciences, Moscow
I. M.
Dergunov
Moscow Power Engineering Institute, Russian Academy of Sciences, Moscow, Russia
Alexei P.
Kryukov
Moscow Power Engineering Institute, Moscow, Krasnokazarmennaya 14, 111250, Russia
Results of the numerical investigation of vapor film evolution in sodium film boiling under microgravity conditions are presented. The gas molecular-kinetic theory in combination with continuum mechanics are used for system description. Two different heat transfer models are considered. The peculiarities of vapor cavity evolution connected with interphase resistance and liquid thermal resistance are obtained. The influence of temperature and pressure in the vessel on the vapor film growth–collapse is investigated.
Characteristic Features of Heat Transfer of Tube Bundles in a Cross Water–Air Flow and a Three-Phase Fluidized Bed
7
L. K.
Vasanova
Ural State Technical University, Ekaterinburg
V. V.
Korotke
Ural State Technical University, Ekaterinburg
A. V.
Sokolov
Ural State Technical University, Ekaterinburg
G. P.
Yasnikov
Ural State Technical University, Ekaterinburg
V. S.
Belousov
Ural State Technical University, Ekaterinburg
As a result of studies of heat transfer between horizontal in-line and staggered tubes and a gas–liquid flow, heat transfer of higher intensity was obtained as compared with a single-phase liquid flow. The presence of solid particles in a gas-liquid flow, i.e., formation of a three-phase fluidized bed, results in a greater intensity of pulses (liquid-phase velocity and pressure fluctuations) near the heat-transfer surface. These fluctuations cause an increase in the heat-transfer coefficient for smaller Reynolds numbers.
Heat Transfer in Condensation of Vapor in the Presence of a Large Amount of a Noncondensing Gas in the Contact Apparatus with a Net Packing
7
N. A.
Dikii
Kiev Polytechnic Institute, National Technical University of Ukraine, Kiev, Ukraine
V. I.
Shklyar
Kiev Polytechnic Institute, National Technical University of Ukraine, Kiev, Ukraine
V. V.
Dubrovskaya
Kiev Polytechnic Institute, National Technical University of Ukraine, Kiev
Results of experimental investigation of heat and mass transfer in a contact apparatus with a net packing in condensation of a gas–steam mixture are presented. The dependences of the heat-transfer coefficient on gas–steam mixture velocity, spray density, packing length, and amount of noncondensing gases have been studied. Generalizing relations are proposed to determine heat-transfer coefficients and apparatus flooding rates.
Influence of the Size and Shape of the Bodies Moving in a Fluidized Bed on Heat Transfer Intensity
5
S. A.
Nagornov
All-Russia Scientific-Research and Design-Technological Institute for the Use of Technology and Oil Products in Agriculture; Ural State Technical University, Ekaterinburg, Russia
I. A.
Osintsev
All-Russia Scientific-Research and Design-Technological Institute for the Use of Technology and Oil Products in Agriculture; Ural State Technical University, Ekaterinburg, Russia
A. V.
Ostrovskaya
All-Russia Scientific-Research and Design-Technological Institute for the Use of Technology and Oil Products in Agriculture; Ural State Technical University, Ekaterinburg, Russia
V. N.
Korolev
All-Russia Scientific-Research and Design-Technological Institute for the Use of Technology and Oil Products in Agriculture; Ural State Technical University, Ekaterinburg, Russia
The influence of transformation of the gyration of a cylinder in a horizontal plane into an extended body driven in a vertical direction in a fluidized bed on the intensity of external heat transfer is investigated for the case of co- and countercurrent motion of a surface and a gas medium. It is shown that differences in the character of fluidized-bed flow around differently shaped bodies account for the intensity of heat transfer between these bodies and a fluidized medium. It is established that replacement of a cylinder by an extended body distorts not only the uniformity of heat exchange around the perimeter of the body, but also causes a drop in the intensity of external heat transfer.
Conjugate Heat and Mass Transfer in Crystallization from Food Solutions
14
O. G.
Burdo
Odessa State Academy of Foodstuff Technologies, Odessa, Ukraine
S. I.
Milinchuk
Odessa State Academy of Foodstuff Technologies, Odessa, Ukraine
E. A.
Kovalenko
Odessa State Academy of Foodstuff Technologies, Odessa, Ukraine
The paper considers the prospects of the development of modern methods used in dehydration of foodstuff. The main tendencies of the development of the low-temperature techniques of separation of solutions are formulated. The advantages of the technique of block freezing and ways of its further perfection are shown. Simulation of the processes of low-temperature crystallization from solutions is carried out and the necessity of creation of the model of conjugate heat and mass transfer is justified. The outcomes of experimental researches of processes of freezing of fruit juices and lactic whey are presented. It is shown that the model developed adequately features the process of crystallization from food solutions with an error not exceeding 10%.