Ice Formation Investigation on a Horizontal Cooled Plate

In the horizontal layer of water with two rigid boundaries, the formation of ice on a monotonically cooled plate has been studied. The temperature distribution along the height of the layer was measured experimentally. The measurements are made by resistance thermometers, which give averaged values of the temperature in the horizontal plane at given levels. Subcooling of water was found almost to -4 ° C. It is established that the formation of a smooth transparent layer of ice is preceded by the formation of dendrites in a layer about 4-5 mm thick near the upper cold boundary. In a layer 33.7 mm thick, the intensity of the convective flow was attenuated when the water was cooled to a temperature below 4 °C. The rate of the ice layer thickness growth is measured. The water layer of a given thickness was located in a cavity with horizontal dimensions of 240 x 240 mm2. The horizontal boundaries of the layer consist of massive copper plates. The initial temperature of the system was 25.4 °C. At the initial time, cooling of the lower boundary to 6 °C was included. The upper limit was cooled by pumping the coolant from the cryotermostat with a lower limit of -15 °C. The cooling rate of the entire system at the initial stage was 0.2 °C / min. Due to weak heating from below, a convective flow was observed in the water layer during the first 150 min. In the Rayleigh-Benar cell-convection mode, a temperature profile is formed with a reverse gradient in the central part along the height of the layer. When the temperature reached the upper limit of +4 °C, the convective flow practically disappeared. Under the cold upper boundary, upon further cooling, an increasingly thick layer of a stably stratified liquid forms. The crystallization process at a given layer height begins with a practically absent convective flow.

термогравитационная конвекция, нестационарное поле температуры, переохлаждение воды, образование льда

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