Radiative Heat Transfer Processes in Heating Open Platforms
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Journal of Engineering Physics and Thermophysics, Vol. 93, No. 6, November, 2020
RADIATIVE HEAT TRANSFER PROCESSES IN HEATING OPEN PLATFORMS A. A. Red'ko,a I. A. Red'ko,b Yu. A. Burda,a A. F. Red'ko,a and S. V. Pavlovskiia
UDC 621.184.004
The results of a numerical analysis of the parameters of the system of radiative heating of an open platform, a flat car of size 10 × 75 m, are presented. The temperature of the radiator of size 0.3 × 9 m was 600–900 K. The temperature of the atmospheric air varied in the range from –10 to +10oC at a wind velocity of up to 5 m/s. As the criterion of heating comfortably a human being, the temperature at the level of his head (175 cm) was taken. As a result of the computational experiment, the dependences of the temperature of the heated platform on the temperature and the height of the radiator mounting, as well as on the direction and velocity of wind, were obtained. It has been established that the temperature at the level of the top of the human being's head is equal from 2–3 to 16–18oC when the radiators are disposed at a height of 4–8 m from the platform surface at the surrounding air temperature of 0oC and wind velocity of 0.5–5 m/s. It is shown that on decrease of the air temperature to –10oC the installation of wind protection is required. Keywords: numerical analysis, radiative heating, open platform, comfort, short-wave emitters. Introduction. At the present time, infrared heating systems with gaseous burners are finding wide application due to their high economical efficiency in heating various large industrial buildings (flat cars and car shops, garages, hungars, and storehouses), as well as for local heating of open sites of cafes, restaurants, stadiums, factories, and other objects. A special region of application of infrared heating is the local heating of people in a room where the mounting of convective heating is impossible. Continuous heating of people directly where they work by infrared radiant burners confers favorable thermal feelings, since relative stability of a thermal regime is provided. At the present time there are no verified data on doses of radiative heating of people on platforms where they are subjected to the action of wind at a low temperature. The temperature of the surfaces of gaseous flameless radiators amounts to 600–1700 K. The wavelength of their radiation changes in the range from 1.5 to 5 μm. High-temperature emitters have a limited application, since they do not provide uniform heating of the entire room because of the high intensity of their radiation and the acute angle of its directionality. However, due to their small size and mass, large service life (up to 20 years), high reliability and economical efficiency, they are used effectively for local heating of some sections of the room, as well as at a large height (up to 20 m) [1–6]. According to the data of [6, 7], at a lowered air temperature the intensity of infrared irradiation of a human being must increase by 25 W/m2 for each degree of temperature decrease beginning from the
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