Experimental study on convective drying of quince slices and evaluation of thin-layer drying models

Abstract

The objective of the present work is to study the drying kinetics of quince slices during convective drying. The details of the laboratory-scaled convective dryer are presented. Experiments were carried out at air temperatures 40 °C, 50 °C and 60 °C and 2 m s−1 bulk velocity. The whole process occurred within the falling rate period. Results showed that the temperature of the air stream has a significant effect on the drying curves. In particular, a temperature increase from 40 to 60 °C produced a decrease of the total time of drying of about 54%. Eight thin-layer drying models were used to fit the temporal distributions of the moisture data using non-linear regression analysis. Among the various models, the Weibull formula was best fitted to measurements. For the range of the drying temperatures examined, Fick's law of diffusion was used to determine the effective moisture diffusivity, which varied between 3.23 × 10−10 m2 s−1 and 7.82 × 10−10 m2 s−1. Assuming an Arrhenius type model for the drying process, a value of 38.291 kJ mol−1 was estimated for the activation energy.