The heat-and-power engineering hardware of black metallurgy most power-consuming not only, but also are the most powerful sources of contamination of environment (including and thermal). Obviously, that more perfect aggregates have high coefficient of efficiency relatively, consume less energies and less select contaminations. One of factors influencing on efficiency of thermal device, there is intensity heat-exchange processes, including on the surfaces of the processed material, for example, coefficient of heat exchange between a working environment and surfaces.
Simple by a structural element, to inherent many heat-and-power engineering hardware, there is a pipe which a viscid environment moves into, and its surface is exposed to thermal influence. On such element it is relatively easily to experiment and expose dependence of coefficient of heat exchange on different factors. This system of heating (coolings), filled by heat-transfer , is liable by forced or gravitation convection. Warmly from the hot area of contour is carried in those areas, where taking of heat is carried out. The capacity of such aggregate will depend on inertia of the system and time of output on the stationary mode at the change of the mode of heat exchange.
Target setting: from the wide class of tasks of heat-transfer it was decided to stop on consideration tasks of decision of equalization of energy most often meeting in practice in mobile environments at the set field of speed. The study of such process into the simplest structural element by a numeral method allows to expose not only features of flowline of this process with the thermal loading variable on length in the dynamic and stationary modes, but also to work the method of decision of the system of equalizations for the aggregates of more complicated configuration, in which the field of speed also is required. This moment is very important, because the analysis of the got decision allows to foresee and to remove emergency situations during exploitation of equipment.
Therefore a task in the following raising is formulated in the real work: lets on a pipe by the R radius heat-transfer the temperature of which in the initial moment of time makes tн moves, and his expense - G [kg/s]. It is adopted the flow hydrodynamically is stabilized. In this case the transversal speed Vr = 0, and longitudinal constituent to the Vx speed does not change on length of pipe, and will change on a radius, for example, from law: Vx=V0•(1-r2/R2)=2•Vcp•(1-r2/R2) where V0 is speed on the axis of pipe; Vср it is middle speed on the section.
we will open out the comforts of further exposition the reserved contour. There is the external heating of pipe by the permanent thermal stream of q on a vertical area, on all the other areas pipe there is tвх with a temperature with an environment in a state of natural convection. In the initial moment of time heat-transfer has a stationary temperature, I.e. at tau= 0; t = tн. In quality a characteristic size for a horizontal pipe its diameter is accepted, for vertical is distance from the beginning of area before the examined section. It is assumed that on the external surface of pipe the thermal loading is distributed evenly, therefore the sought after field of temperatures does not depend on a co-ordinate, and on the axis of pipe of r = 0 the condition of symmetry will be executed. At the beginning of pipe (х = 0) and in its end (x = Lx) temperatures must coincide, because a pipe represents the reserved contour. After the decision of task, when the field of temperatures into a pipe will be found, it will be possible to find the value of local coefficients of heat emission from the internal surface of pipe to teplonosytelyu.
The set problem often meets in practice and is most simple in the class of tasks about a konvektyvnom heat exchange, because equalization of conservation of energy in a mobile environment with the set field of speed is analysed. The detailed study of process of heat exchange is planned to execute by the numeral experiment.
1. Patankar S., Numerical heat transfer and fluid. - М.:Energoatomizdat, 1984.-150p.
2. Aderson, Deyl. Computational fluid mechanics and heat transfer.-М.:Мir, 1990.