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Thermal state of stored products in storage bins with aeration system: experimental-theoretical study

The cooling of grains by ventilation with ambient air applies widely in the final stages of drying and for the subsequent temperature control of stored grains. The objective of this work is to carry out an experimental-theoretical study on the thermal state of a soybean mass, subject to the aeration. The experimental data on cooling dynamics of preheated soybean mass were obtained for different heights of the grain column and air velocities. The analysis of the results showed that the cooling rate varies significantly during all process in all domains and the thermal diffusivity of the layers cannot be considered as a constant. To simulate the cooling dynamics two mathematical models were introduced. In the first model the cooling domain was divided by means of the movable frontier in two zones represented by different coefficients of thermal diffusivity (analogous of Stefan's problem). In another model all the domain was divided hypothetically in small layers and was considered that the thermal balance between the air and the mass of grains for these layers is reached instantly ("homogeneous reactors"). The results of simulations showed a satisfactory agreement with the experimental data.

storage; aeration; cooling


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