Ice Formation and Film Flow of Water on Vertical and Inclined Packings
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Journal of Engineering Physics and Thermophysics, Vol. 93, No. 4, July, 2020
HEAT TRANSFER IN PHASE TRANSFORMATIONS ICE FORMATION AND FILM FLOW OF WATER ON VERTICAL AND INCLINED PACKINGS I. I. Pukhovoi
UDC 69.621.58
This paper presents the results of studies on the formation of ice on vertical and inclined packings manufactured from a cord of diameters 2 and 5 mm or a wire. Water was sprayed by a rotating disk onto the walls of a pipe of diameter 200 mm where it was cooled and fell on the cord packings without the action of special distributing devices. Periodic protrusions and troughs appeared on the packings just as in the case of formation of icicles. The presence of the cord made it possible to obtain long stalactites as opposed to icicles that grow due to the freezing of their tips and cease to grow at large wetting densities. At the lower parts of the packings tilted at angles of 20–25o, a toothed ice was formed without separation of drops and icicles. The thicknesses of water films and heat transfer coefficients were calculated for air flow across the packings. Good agreement of the results of calculations with corresponding experimental data has been obtained. Keywords: cord packings, water films, heat transfer, ice formation, ice accumulation, ventilation, heat pumps. Introduction. Atmospheric air is used in thermal power engineering and cooling installations for removing heat in carrying out thermodynamic cycles. In these processes, water cooled in evaporative chimney-type cooling towers is an intermediate heat transfer agent, with wind and gas dynamics of air flow playing a large role in this case [1]. The same processes also take place in the case of ice formation in the form of icicles in so-called ice cooling towers [2]. Under the conditions of negative temperatures lower than 10–15oC, realized over the larger parts of Europe, Asia, and America, the best effect in obtaining ice is attained with the use of icicles grown on horizontal and inclined packings. The formation of ice in icicles has advantages over other means of producing ice in natural conditions due to the absence of thermal resistance of ice on direct contact of cold air with water flowing over a large number of icicles. In work [3], it was suggested to use icicles for heating frozen air by the water crystallization heat — a suggestion checked in practice in [4]. The cold penetrating from the outer space in winter is a renewable energy source that allows generation of ice in winter with simultaneous heating air ahead of the heaters of fans and heat pump evaporators. This renewable resource reduces the consumption of fuel and, correspondingly, the ejections of greenhouse gases that contribute to the overheating of the planet. In the generation of ice with the use of natural freezing air, it is important that the surface of air contact with water be as large as possible. Only at temperatures below –20oC can the sprayed drops freeze during their motion in air [5]. At higher temperatures, the drops freeze only after they arrive at a solid s
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