Batch-wise process of cherry juice freeze concentration

Abstract
Basic laws of the cherry juice freeze concentration process are investigated. Is established that the basic factors influencing the process of freezing are: the boiling point of refrigerant in the freezing unit (–17 оС), surface area of heat exchange elements to the unit of the working volume of the unit, the juice flow rate and initial content of dry matter in the original juice. It is shown that with the decrease of the refrigerant boiling point in the vaporizer of the freezing unit specific quantity of the ice frozen out increases monotonically due to the transition of a significant quantity of free water into the solid phase because of the high temperature difference between the circulating juice and the heat exchange surface of the unit. A specific quantity of the ice frozen out with an increase in the specific surface area of heat exchange elements to 72,0…75,0 m2/m3 increases to a certain value also, then it decreases to the maximum values of the compressor refrigerating power. A change in the value of a specific quantity of the ice frozen out depending on the cherry juice flow rate (2·10–5 м3/с) and the initial content of dry matter in it (12,4%) is of nonlinear nature also. The influence of the investigated factors on the energy consumption at moisture freezing out is analyzed. It is found out that with an increase in the specific surface area of heat exchange elements the specific energy consumption to freeze out 1 kg ice increases directly proportionally, reaching maximum value at the maximum specific surface area of heat exchange elements (f = 127 м2/м3). The greatest energy consumption is found to be when a juice with the minimum initial content of dry matter is frozen out. The obtained information is of great importance for estimation and prediction of both the regimes of freezing cherry juice with different content of dry matter and the energy consumption for the heating of the concentration process.