Mathematical modelling, moisture diffusion and specific energy consumption of thin layer microwave drying of olive pomace

In this study, the effects of microwave drying power on drying kinetics, effective moisture diffusivity, and specific energy consumption of olive pomace were studied at three different microwave power levels of 170, 360 and 510 W. Increasing microwave power resulted in a considerable decrease in drying time. The experimental data for moisture loss was converted to moisture ratios and fitted to eleven thin layer drying mathematical models to describe the drying process. Among the models tested, the Midilli et al. and Diffusion Approch models were found to be the most appropriate in describing microwave drying kinetics of olive pomace. The effective moisture diffusivity values varied from 3.55 x 10-9 to 20.47 x 10-9 m2/s and increased with increase in microwave power. The activation energy was calculated using an exponential expression based on Arrhenius equation and was found to be 20.98 W/g. The specific energy consumption values were in the range of 52.56 to 25.32 MJ/kg [H2O], under applied drying conditions.