The Effects Of Microwave Energy To The Drying Of Apple (Gala) Slices
In this work, the drying behaviors of apple slices with 2, 4, and 6mm thickness were investigated in a microwave conveyor dryer. The effects of different microwave power levels (1050W, 1500W and 2100W) and conveyor belt speeds (0.175, 0.210 ve 0.245m/min) on drying time, color changing and energy consumption have been investigated. The results show that drying time and energy consumption decreases considerably with increasing microwave power and with decreasing conveyor belt speed. Then, the mathematical models were fitted to the experimental data. According to the results, the Page Model was found to best explain thin layer drying behavior of the apple slices as compared to the other models. Fick’s diffusion model was applied to calculate the effective diffusivities. The effective diffusivity values were found between 1.1916×10−8m2/s and 2.7540×10−7m2/s. The activation energies were calculated as 156.65, 40.18 and 17.90W/g for samples thickness of 2, 4 and 6 mm, respectively. At the end of the drying process, minimum energy consumption for 2mm at 0.175m/min conveyor speed and 2100W power is calculated as 1.34kWh. From the results of colour quality, the colour criteria nearest the those of apple slices occurred at 1050W and 0.210m/min.
© 2011 Karaelmas Fen ve Mühendislik Dergisi