Thin-layer drying model of Cosmos caudatus

Abstract

Drying kinetic models and energy characteristics are well known tools to evaluate and predict the most suitable drying physiochemical conditions for a particular product. In this study, a thin-layer drying model was developed to best describe the drying kinetic behaviour of Cosmos caudatus. The drying experiments were conducted using a thermal convection oven and C. caudatus leaves were dried at five different temperatures (40, 50, 60, 70, 80?C). Six different thin-layer drying models were proposed and applied to select the best drying model by fitting to the experimental moisture ratio data. The proposed drying models included Page, Modified Page, Lewis, Henderson-Pabis, Two Term and Weibull, and the results were statically compared and evaluated based on their goodness of fit. Among these, the Page model was found to best represent the thin-layer drying behaviour of C. caudatus with 99.76%, 5.93?10-5, 9.68?10-5 for the coefficients determination (R2), reduced chi-square (?2), and root mean square error (RMSE), respectively. The average effective moisture diffusion coefficient (Deff) for the temperature 40 to 80?C ranged from 4.12?10-12 to 24.71?10-12 m2/s, while the activation energy (Ea) was calculated at 39.35 kJ/mol based on the Arrhenius?s equation.