Mathematical Modeling of Kinetics of Thin-layer Drying of Apple (var. Golab)
Mathematical models of thin-layer drying of apple were studied and verified with experimental data. Fourteen different mathematical drying models were compared according to three statistical parameters, i.e. root mean square error (RMSE), chi-square (X2) and modeling efficiency (EF). The thin-layer drying kinetics of apple slices was experimentally investigated in a laboratory convective dryer and the mathematical modeling, using thin-layer drying models present in the literature, was performed. The main objective of the study was the verification of models already developed. Experiments were performed at air temperature between 40 and 80 °C, velocity of 0.5, 1 and 2 m/s, and thickness of thin layer of 2, 4, 6 mm. Besides the effects of drying air temperature and velocity, effects of slice thickness on the drying characteristics and drying time were also determined. Drying curves obtained from the experimental data were fitted to the-thin layer drying models. The results have shown that, model introduced by Midilli et al. (2002) obtained the highest value of EF = 0.99972, the lowest value of RMSE = 0.00292 and X2 = 10-5. Therefore this model was the best for describing the drying curves of apples. The effects of drying air temperature, velocity and thickness on the drying constant and coefficient were shown to compare the circumstances of drying.