Propagation of technological filtration combustion waves in porous media of inhomogeneous composition

The article contains results of numerical simulation of propagation of filtration combustion waves with forced supply of gas-phase reagent into a porous medium of inhomogeneous composition. Wave “penetration” and “reflection” effects at the interface of media with different chemical compositions are found and explained. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 71, No. 1, pp. 46–50, 1998.     

Some energy characteristics of the process of heating of a porous layer by an incompressible liquid or gas flow

The process of heating of a porous body that is initially at a low temperature by an incompressible liquid or gas flow is considered. The amount of heat energy that cannot be transferred to the porous layer because of the temperature difference between the liquid (or gas) and solid phases, respectively, is calculated. This energy may be considered “excess” energy. Its quantity is calculated analytically for the case of heating of a semi-infinite porous body. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 70, No. 2, pp. 195–199, March–April, 1997.     

Heat transfer in regional extracorporal perfusion of limbs

Two problems of heat transfer in regional perfusion are analyzed, viz., in heating of limbs by hot blood and in normothermal perfusion in combination with local SHF hyperthermia. The efficiency of the procedure in the latter case and its inefficiency in the former case are shown. The coefficient of heat transfer between a circulatory system and biotissue is estimated. Academic Scientific Complex “A. V. Luikov Heat and Mass Transfer Institute, Academy of Sciences of Belarus,” Minsk; Scientific Research Institute of Oncology and Medical Radiology, Ministry of Public Health of Belarus,” Minsk, Belarus. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 69, No. 3, pp. 434–442, May–June, 1996.     

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.     

The Transfer of Fibres in the Carding Machine

The problem of understanding the transfer of fibres between carding-machine surfaces is addressed by considering the movement of a single fibre in an airflow. The structure of the aerodynamic flow field predicts how and when fibres migrate between the different process surfaces. In the case of a revolving-flats carding machine the theory predicts a “strong” aerodynamic mechanism between taker-in and cylinder and a “weak” mechanism between cylinder and removal cylinder resulting in effective transfer in the first case and a more limited transfer in the second.     

Heat release into the ambient medium from a pulsed heat source of “running heat wave” type

An experimental study is performed of the radial distribution of the maximum ambient (air, water without forced agitation) temperatures at different distances from a pulsed cylindrical heat source with a “charge” of energy-producing mixtures of different composition burning frontally. Mechanisms of heat transfer from the source to the ambient medium are considered. The influence of the phase transition in the combustion products on the thermal pattern of heat transfer from the pulsed heat source to the ambient medium is discovered and explained.     

Dispersion characteristics of water- and gold-infiltrated opal photonic crystals

This paper presents a theoretical analysis of conditions for the propagation of electromagnetic waves in a wide frequency range (from the infrared to ultraviolet spectral region) in synthetic opals infiltrated with water and gold nanoparticles. A dispersion equation is derived which describes the dispersion law of both “right-hand” (right-hand system of the [(E)\vec]\vec E, [(H)\vec]\vec H, and [(k)\vec]\vec k vectors) and “left-hand” (left-hand system of the [(E)\vec]\vec E, [(H)\vec]\vec H, and [(k)\vec]\vec k vectors) electromagnetic waves in the crystals. We have determined the dispersion characteristics of the refractive index and broadband reflectance of the opals, group velocity dispersion, and effective mass dispersion for phonons and polaritons. Theoretical results are compared to measured reflection spectra.     

Calculation of the effect of evaporating drops on the relative law of heat exchange with a disperse mist flow

On the basis of a two-layer scheme of wall turbulence, a relative law of heat exchange with a disperse mist flow is calculated. It is shown that the influence of drops on heat exchange leads to a finite “stepwise” increase in heat transfer compared to the case of a single-phase vapor flow. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 70, No. 3, pp. 510–513, May–June, 1997.     

Realization of the Indium Fixed Point by an Adiabatic Technique

This work investigates the effect of heating techniques on the realization of the ITS-90 fixed points above room temperature. For that purpose, LNE has constructed a new apparatus to realize the indium fixed point under adiabatic conditions using the “calorimetric” method. The adiabatic condition, in general, is established by maintaining a temperature difference between the fixed-point cell and its surroundings that is as small as possible. In this work, the indium fixed-point cell is located within thermally controlled heat shields whose walls also contain indium. Thus, the shields themselves are also indium cells. The experiments realizing the melting and freezing temperatures of indium using the calorimetric method are described. The results revealed the existence of thermal effects in the realization of the indium fixed-point cell by the conventional “continuous heat flux” method. The advantages of the “cell-within-cell” technique are presented.     

Influence of stefan flow on the characteristics of heterogeneous combustion of a carbon particle in air

The influence of Stefan flow and radiation-induced heat losses on the characteristics of stationary high-and low-temperature stable and critical regimes of heat and mass transfer of a carbon particle in air is analyzed. The investigations are sponsored by the International Fund “Vidrodzhennya” within the framework of the program ISSEP (contract No. K6V100). Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 70, No. 1, pp. 146–152, January–February, 1997.     

Porous yttria-stabilized zirconia ceramics with ultra-low thermal conductivity. Part II: temperature dependence of thermophysical properties

This study describes the experimental results of thermal diffusivity, specific heat at constant pressure, and thermal conductivity of porous 8 mol% yttria-stabilized zirconia (YSZ) ceramics in a temperature range from room temperature to 1,400 °C. It is a follow-up study of the earlier report titled by “Porous YSZ ceramics with ultra-low thermal conductivity”, which focused on the room-temperature thermal conductivity. The thermal diffusivity of porous YSZ ceramics decreased with the increase of the measurement temperature up to 600–1,000 °C, followed by an increasing trend with increasing temperature. The specific heat did not exhibit any significant dependence on sintering temperature and agreed with literature data. The thermal conductivity of the porous YSZ ceramics showed an insensitive tendency of change with measurement temperature. The thermal conductivity fell in groups by the sintering temperature level. This investigation also discussed an appropriate sintering temperature of porous YSZ ceramics, which had both low thermal conductivity and high strength required by the practical service.     

New composite sorbents of water and ammonia for chemical and adsorption heat pumps

New sorbents of water and ammonia — “salt in porous matrix” composites and “salt on fiber” composites — have been reviewed. The possibility of “constructing” the sorption properties of the composites at the nanophase level by varying their composition, the size of the host-matrix pores, and synthesis conditions has been shown. The application of the new materials in adsorption refrigerating devices has been considered. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 6, pp. 160–175, November–December, 2006.     

The use of the limiting laws of turbulent friction and heat transfer to construct wall functions on permeable surfaces

The limiting laws of turbulent transfer of momentum and heat at high values of the Reynolds number are used to derive wall functions (“wall laws”) under conditions of a flow of gas with variable physical properties along a permeable surface.     

High-temperature heat and mass transfer in a layer of coke of heat-shielding materials

The model including the structure inhomogeneity of the coke of a typical “charring” heat-shielding material (HSM) is used to investigate the process of high-temperature heat and mass transfer in a layer of HSM coke. The scales are determined of temperature nonequilibrium between condensed and gaseous products of thermal decomposition of HSM under conditions of high (above 1000 K) temperatures of the environment. It is demonstrated that, in solving numerous problems associated with heat shielding, it is appropriate to employ models including the temperature nonequilibrium of the gas and condensed phases of HSM coke.     

A Novel Technique for Experimental Thermophysical Characterization of Phase-Change Materials

The major objective of this project is to use phase-change materials (PCMs) as integrated components in passive solar heat recovery systems. The suggested approach involves experimental investigations and characterization of the global behavior of a parallelepiped “material wrap” filled with the PCM. The experimental apparatus permits simultaneous measurements of heat fluxes and temperatures. It also allows imposing and measuring temperatures variations with respect to selected time scales between the two predominant faces of the sample. The instantaneous heat flux measurements allow the determination of the “apparent” or overall heat storage capacities and thermal conductivities of the PCM—in the solid and liquid states—and that of the latent heat of melting. Results were found to be very satisfactory.     

Multi-scale Modeling of Radiation Heat Transfer through Nanoporous Superinsulating Materials

In this contribution, the extraordinarily high level of thermal insulation produced by nanoporous materials, which can achieve thermal conductivities down to a few mW·m⁻¹·K⁻¹ when they are evacuated to a primary vacuum, is highlighted. The objective here is to quantify the level of radiation heat transfer traveling through a nanoporous material in relation with its composition. The model used here is based on the “non-gray anisotropically scattering Rosseland approximation,” which allows the definition of a “radiation thermal conductivity” expressed as a function of the optical properties (complex optical index spectra), mean sizes and volume fractions of the different populations of particles constituting the material. With the help of this simple model, one can draw interesting conclusions concerning the impacts of different parameters related to the microstructure of the nanoporous material on the amplitude of the radiation heat transfer. In the future, this model should help to orient the formulation of new nanoporous materials with optimized radiative properties. Paper presented at the Seventeenth European Conference on Thermophysical Properties, September 5–8, 2005, Bratislava, Slovak Republic.     

Uncertainty of measurement results in various scales

The relationship between the concepts of “error” and “uncertainty” of measurement results is examined. The concepts of “standard uncertainty,” “combined standard uncertainty,” and “expanded uncertainty” are shown to be inapplicable in nonmetric scales of quantities and properties, in which the general concept of “uncertainty” in the broad sense is recommended. Translated from Izmeritel'naya Tekhnika, No. 5, pp. 29–30, May, 2000.     

Mechanisms of the mass transfer of “Loose” corrosion deposits in primary circuits of a water-cooled reactor and practical recommendations

This paper describes the mechanisms of the mass transfer of “loose” corrosion deposits in the primary circuits of water-cooled reactors. The revealed “peaks” of the amount of suspended corrosion particles in the reactor transients are reported are reported. Two ways of using this effect are suggested: first, for monitoring the amount of suspended corrosion particles in the circuit and the thickness of their deposits formed on the surfaces of the primary circuit equipment; second, for removing “loose” deposits containing radionuclides from primary circuits, i.e., for “non-chemical decontamination technology.”     

“Thermal Prism” Method for Measuring Thermophysical Properties of Thin Films

Theoretical principles underlying the photothermal method for measuring the thickness and thermal properties of a thin film located between two optical elements (“sandwich”) are analyzed. The method is based on the irradiation of the assembly by repetitive pulse laser radiation. Radiation is absorbed in the film and causes heating of the optical elements by heat conduction. The element is monitored by a narrow beam of a second low-power laser propagating through the heated region. The beam is deflected due to the spatial variation of the refractive index, and the magnitude of the deflection angle as a function of time contains the relaxation and “wave” components. It is shown that the phase of the “wave” component depends on the thickness and thermophysical properties of the film. The thermophysical properties of the film can be determined, provided that the analogous properties of the optical element are measured previously or otherwise known, by comparing experimentally measured values of the phase shift with theoretical values obtained from the analytical solution of the non-stationary two-dimensional heat conduction equation.     

A model for the energy bands of an “open”-type periodic structure: a periodic viaduct coupled with the half-space

The periodic viaduct in this study was defined as a new kind of periodic structure—the “open”-type periodic structure—for the first time. Knowledge about the energy bands of this kind of “open” periodic viaduct is important for its aseismic design. Using the transfer matrix method and the compliances for the pile foundations, the impedances for the piers were obtained. Based on the Bloch theorem and the transfer matrix method, the nonlinear polynomial eigenvalue equation for the energy bands of the periodic viaduct undergoing in-plane motion was derived using the impedance of the piers. Based on the obtained nonlinear eigenvalue equation, the approximate linear eigenvalue equation for the periodic viaduct was obtained, and numerical results for the energy bands of the periodic viaduct were presented. The numerical results in this paper demonstrate that when the periodic viaduct is undergoing in-plane motion, there exist three lattice waves: the first kind of wave is a highly decaying wave; the second kind of lattice wave can propagate only at some frequency ranges; and the third kind of lattice wave can propagate at most frequencies.