Selection of optimal method of forming a layer of candied fruits during filtration drying

Abstract

Optimal formation of the layer of candied fruits in a drying zone allows reducing the volume of a dryer, increasing the contact area of the outer surface of a particle thermal agent and, as a consequence, cutting energy costs. To determine optimal method of the formation of layer, we conducted experimental studies of the change in hydraulic resistance from the speed of gas flow motion under conditions of forming a layer of candied fruits by different methods. Based on generalizations of experimental and theoretical studies, we obtained estimated dependencies for the calculation of coefficient of hydraulic resistance and losses of pressure in the layer of candied fruits formed by different methods. They represent equations, which include such hydrodynamic parameters, obtained through experimental research and generalization of research data, as: actual speed of gas flow, equivalent diameter and equivalent height of between the particles, coefficient of hydraulic resistance. Obtained theoretical dependencies agree well experimental data and are important for the prediction of kinetics of the filtration drying regard to energy costs for the process. The dependencies are also important both for numerical simulation of the course of thermal mass exchanging processes during drying and for practical calculations. Based on the generalizing equations and values of specific surface, received by Authors, the expediency of forming a layer by the method of arranging the particles of candied fruits vertically with blocking the channels was substantiated. It is proved that this method allows providing for the maximum speed of thermal agent in the layer and, as a consequence, intensifying the process of filtration drying.