Currently, lighting systems with hollow tubular light guides that can transport light to any part of the building have been widely used for natural illumination of buildings. The article presents a comparative analysis of the operation of hollow light guides and traditional side and upper light openings. Examples of large realized projects of buildings with hollow tubular light guides in Russia show the rationale for choosing such lighting systems and their advantages. The unique experience of using light guides for natural lighting of a church in Siberia is considered in the paper. During the design of this illumination system some innovative technical solutions were developed and implemented for the first time. The access of daylight in dark rooms, the provision of thermal and light comfort in the building, energy saving, protection from adverse weather conditions, the emergence of new opportunities for architectural solutions are factors determining the prospects for application of a natural lighting system with hollow tubular light guides in Russia.

Keywords: natural lighting systems, hollow tubular light guides, side and upper light openings, energy saving, innovative technologies

An approximate method for calculating the temperature field in solids heated by convection and radiation at the same time, when the thermophysical properties of the substance depend on temperature, is described. The method is based on the complex use of linearization functions and methods of numerical analysis. In the paper an example of calculation of radiation-convective heating of an unlimited plate, during which the heat capacity and thermal conductivity of the material change with temperature, is presented. The results obtained are in good agreement with the data of the finite difference method. The proposed method makes it possible to solve nonlinear problems of thermal conductivity with other boundary conditions, since the technique of solving such problems is not fundamentally different from one another. The article was published in the framework of the program of the International Forum "Victorious may 1945".

Keywords: temperature field,radiation-convective heating, thermal conductivity and heat capacity coefficients, linearizing transformation

The scheme of calculation of nonstationary temperatures in the bodies heated by the radiation which based on the established dependencies between them is presented in the article. To study the process of radiation heating of bodies, the method of linearization functions proposed by one of the authors is used. The idea of the method is as follows. The linearizing transformation leads nonlinear boundary conditions to linear boundary conditions of the third kind. The solution of the linear problem in the stage of regular temperature regime is found by multiplying the corresponding solutions of one-dimensional transfer problems. After the transformations, equations are obtained that allow calculating the temperature fields in multidimensional bodies, if the temperature distribution along the coordinate axes or on the surface is known. There is no need to know the physical parameters of the material and the degree of blackness of the body surface.

Keywords: temperature field, radiation heating, multidimensional bodies, linearizing transformation, linear boundary conditions of the third kind

Numerical solution to the problem of heat transfer in boundary layers transparent Strip on the walls, exposed on the opposite side of the radiant-convective heating. Study of influence of mode parameters on heat transfer process of tasks carried out in the case of the gradient flow and included the most typical variants of transportation processes. The purpose of the real work is studying of processes of transfer at non-linear boundary conditions, obtaining approximate and analytical decisions non-linear warm and a mass transfer, establishment of communication between regime parameters and physical interpretation of results of a research. Also some conjugate problems of heat exchange in the presence of radiation are studied. The analysis received decisions is carried out. The executed research allowed to establish that existence of a transversal overflow of heat in a wall and also the radiation of a surface have significant effect on the nature of distribution of the surface temperatures.

Keywords: boundary layer, convection, radiation, gradient flow, conjugate heat transfer

Numerical solution of the problem of heat transfer in the boundary layers of transparent gas wall, exposed on the opposite side of radiant-convective heating. The energy dissipation due to viscosity is negligible, the wall is thermally thin, and the physical properties of the medium do not depend on temperature. The aim of this work - finding the local heat transfer coefficients (Nusselt number) needed for the analysis of heat exchangers. When solving the problem of nonlinear transfer functions linearizing method is used, based on which numerical scheme for computer calculations was constructed. The intensity of the local heat transfer in the boundary layer is determined by the number Kx = Nux / Nux0, where the value Nusselt numbers refer to the conditions under consideration of the problem of heat exchange (Nux) and constant surface temperature (Nux0). From a physical point of view, non-dimensional parameter Kx is a measure of the intensity of heat transfer in the boundary layer on a nonisothermal surface compared to heat transfer when the wall temperature everywhere the same. The analysis of this research showed that in radiative-convective heating number Kx on the front edge of the plate takes the largest value of Kx ≈ 1,37 corresponding to a constant heat flux on the wall. It is also shown that the relative temperature of the incoming flow has a significant impact on the value of Kx. The effect of this setting is especially evident in the processes when dominated by the effect of radiation and related to the nonlinearity of the transfer processes. The analysis revealed the influence of basic parameters of heat transfer on the development of transport processes in the boundary layer by heating radiation and convection simultaneously.

Keywords: Boundary layer, convection, radiation, radiation-convection heating, high temperature gas invironment, linearizing function