Dehydration characteristics and mathematical modelling of lemon slices drying undergoing oven treatment

Abstract

In this study, the effect of drying temperature on drying behaviour and mass transfer parameters of lemon slices was investigated. The drying experiments were conducted in a laboratory air ventilated oven dryer at temperatures of 50, 60 and 75 °C. It was observed that the drying temperature affected the drying time and drying rate significantly. Drying rate curves revealed that the process at the temperature levels taken place in the falling rate period entirely. The usefulness of eight thin layer models to simulate the drying kinetics was evaluated and the Midilli and Kucuk model showed the best fit to experimental drying curves. The effective moisture diffusivity was determined on the basis of Fick’s second law and obtained to be 1.62 × 10⁻¹¹, 3.25 × 10⁻¹¹ and 8.11 × 10⁻¹¹ m² s⁻¹ for the temperatures of 50, 60 and 75 °C, respectively. The activation energy and Arrhenius constant were calculated to be 60.08 kJ mol⁻¹ and 0.08511 m² s⁻¹, respectively. The average value of convective mass transfer coefficient for the drying temperatures of 50, 60 and 75 °C was calculated to be 5.71 × 10⁻⁷, 1.62 × 10⁻⁶ and 2.53 × 10⁻⁶ m s⁻¹, respectively.