Modeling of convective drying kinetics of pistachio kernels in a fixed bed drying system

Drying kinetics of pistachio kernels with initial moisture content of 32.4% wet basis was investigated as a function of drying conditions in a fixed bed drying system. The drying experiments were carried out at different temperatures of drying air (40, 60 and 80 °C) and air velocities (0.05, 0.075, and 0.1 m/s). Several experiments were performed in terms of mass of pistachio kernels (15 g and 30 g) using a constant air velocity of 0.075 m/s. The fit quality of models was evaluated using the determination coefficient, sum square error, and root mean square error. Among the selected models, the Midilli et al model was found to be the best models for describing the drying behavior of pistachio kernels. The activation energies were calculated as 29.2 kJ/mol and effective diffusivity values were calculated between 1.38 and 4.9410^-10 m²/s depending on air temperatures.