Kinetics of the process of concentration by freezing the cherry juice
Автор: Antipov S.T., Ovsiannikov V.Iu., Kondrateva Ia.I.
Статья в выпуске: 4 (62), 2014 года.
The urgency of theme is substantiated and the basic directions of studies are determined. Is substantiated the mechanism of the process of the concentration of liquid media by freezing moisture, that is determined in essence by the conditions for the migration of the molecules of water to the frontal surface of crystallization and their incorporation into the crystal structure of ice. It is shown that the regime of freezing moisture is characterized by the temperature of the heat exchange surface, which receives heat of crystallization of moisture, by the speeds of displacement and with the surface area of the contact of the being transferred heat media, by form and by the concentration of the dissolved substances of product. The process of heat exchange between the surface of crystallization and the workable technological medium is described. The schematic of the work of the experimental freezing out installation and the procedure of experiences is represented. Are investigated a change in the average value of a quantity of frozen out ice from the unit of heat exchange surface, which freezes out installations in the time, reflected in the form of the curves of increase and rate of growth in the icy phase on the surface of the heat exchange elements of area of 0.08 m 2, in 3600 seconds depending on the temperature of the heat exchange surface and initial content of dry matter in the cherry juice. An increase in the initial content of dry matter in the cherry juice at constant temperature of boiling refrigerant in the vaporizer of the freezing out installation nonlinearly reduces the specific quantity of ice, which was being formed on the heat exchange surface. A change in the boiling point of refrigerant also causes a nonlinear increase in the specific quantity of ice, frozen out on the heat exchange surface. The obtained curves of the rate of growth in the icy phase make it possible to isolate the sections of the crystallization of the moisture, which has different nature of connection with the solute. Is investigated a change in the degree of concentration of cherry juice with the freezing from the boiling point of refrigerant and initial content of dry matter. It is shown that the degree of the concentration of cherry juice is reduced with an increase in the initial content of dry matter in it and an increase in the boiling point of refrigerant in the vaporizer of the freezing out installation.
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