Drying paddy by microwave vibro-fluidized bed drying using single mode applicator

This study aimed to develop the system of microwave-assisted vibro-fluidized bed (MVFB) drying for particulate agricultural products by applying the single mode applicator (SMA), where the microwave field can be focused. SMA- and multi-mode applicator (MMA)-MVFB dryers were set up and their microwave efficiency at different levels of microwave power density (0.82, 1.04 and 1.70 kW/kg) was investigated in water system. Types of applicator did not affect microwave generation efficiency but significantly affected microwave absorbance efficiency. Almost 100% efficiency of microwave absorbance was achieved when heating water in SMA. Therefore, SMA-MVFB drying was selected to perform drying characteristics of paddy, the representative of particulate agricultural products. Four drying techniques including MVFB drying at 850 W, low temperature (LT)-MVFB drying at 850 W and 60 degrees C, LT-vibro-fluidized bed (VFB) drying at 60 degrees C and high temperature (HT)-VFB drying at 150 degrees C were used to dry paddy from 27 to 17% w.b. under constant air velocity of 5 m/s and vibration of 1200 rpm. In addition, it consumed the lowest energy and removed the highest amount of water from paddy. The hybrid system of LT-MVFB drying was proven to be superior to the other drying techniques. This study confirmed successfully application of SMA-MVFB drying for paddy.