M. L. German

Mathematical Model for Calculating the Heat-Protection Properties of the Composite Coating “Ceramic Microspheres–Binder”

A mathematical model which makes it possible to calculate the heat-protection properties of the composite coating “ceramic microspheres–binder” is proposed. The model takes account of the optical and thermophysical properties of the components and the optical properties of a substrate. It is shown that the decrease in the heat loss due to suppression of its radiative component by the coating in question can reach more than 50%. Under certain conditions, the heat-insulation effect can be absent or even inverted, i.e., the presence of the coating is capable of resulting in an increase in the heat flux from the surface being protected. Comparison of the data of the performed full-scale experiment and the calculations based on the proposed model showed that the latter adequately reflects the actual process of heat transfer and can be used for calculating the heat-protection properties of coatings representing a compound of a binder and ceramic microspheres.

Thermal Calculation of the Furnace Chamber of a Fire‐Tube Boiler With a Dead‐End Furnace

An engineering procedure for calculating the thermal regime of the furnace chambers of fire‐tube boilers with a dead‐end furnace is given. The procedure proposed is devoid of many drawbacks that are inherent in the standard method for calculating boiler units and permits more accurate allowance for the special features of combined energy exchange in furnace chambers of boilers that differ significantly in type and size from traditional ones.

Procedure of Calculation of the Optical Characteristics of Selectively Radiating Gases

The efficiency and correctness of the procedure of calculation of the optical characteristics of selectively radiating and absorbing media proposed by the authors earlier and making it possible to take into account with a high degree of accuracy the fine structure of the absorption line is illustrated with the example of calculation of a number of standard problems of radiative transfer. The reliability of calculation of the absorption coefficient (averaged over a finite spectral interval) of a selective medium is evaluated based on the comparison of the results obtained to the experimental and theoretical data given in the literature.

Effective absorption coefficient of a selective medium within a finite spectral range with regard for scattering

The effect of scattering on the lineshape of outgoing radiation for the regular absorption band model is investigated for the model of a homogeneous plane-parallel radiating, absorbing, and scattering layer with transparent boundaries. The investigation is based on numerical solution of the integrodifferential equation of radiation transport. Based on an analysis of results obtained, methods more accurate than the known ones are proposed for calculation of the absorption coefficient by a selective component of the medium averaged over a finite spectral range.

Effect of scattering on the contour of the radiation line of a plane layer of a selective medium

An analytical expression for determination of the correction factor which allows for effect of scattering on the contour of the radiation line of a plane layer of a selective medium is presented. Errors of calculation of the intensity of radiation which arise when this effect is neglected are analyzed. The study is based on a numerical solution of the integro-differential transfer equation.

Mathematical simulation of the temperature field in hardening gears by induction heating under a layer of water

We consider a mathematical model of heat exchange in strainless successive high-frequency-current hardening of the working surfaces of gears. The dynamics of the process of heating and cooling is analyzed, its special features are indicated, and the advantages of the technology of hardening gear tooths by this technique are considered.

Dependence of the characteristics of radiative heat exchange on the optical properties of absorbing, emitting, and scattering media and their boundary surfaces

We suggest a new hybrid numerical-analytical method for solving an integrodifferential equation of radiation transfer. We present results of an investigation of the effect of the temperature distribution and scattering properties of a medium and its absorption density as well as the emissivity of the boundary on the intensity and density of the emergent-radiation fluxes.

INFLUENCE OF THE OPTICAL THICKNESS OF AN EMITTING AND SCATTERING FLAT LAYER ON CHARACTERISTICS OF RADIATIVE HEAT TRANSFER

Analysis is given for the dependence of density of the radiant flux incident on a heat-absorbing surface on the optical thickness of a flat emitting layer.