Investigating Drying of Rice Paddy Using a Continuous Band Microwave Dryer

In recent years, application of microwave dryer is expanding to speed up drying the agricultural products. Therefore, in this research a continuous band microwave dryer was fabricated and evaluated for drying paddy grains. In this experiments, drying process of two paddy varieties (Tarom Hashemi and Nemat) were studied in three levels of microwave power 90, 270 and 450 Watts, three different thicknesses of grain layer 6, 12 and 18 mm and five feeding speed 0.24, 0.3, 0.4, 0.6 and 1.2 mmin-1. The average slope of moisture ratio at the beginning of drying was -1.6×10-3, -1.47×10-3 and -3.16×10-3 for Tarom Hashemi and -2×10-3, -2.1×10-3 and -2.4×10-3 for Nemat at 6, 12 and 18 mm layer thickness, respectively. The finding reflected faster decreasing in the moisture content in the18 mm layer thickness compared to the two other examined layers. By evaluating all of the effective parameters of the fabricated microwave dryer on the moisture reduction and seed breakage percent, the power of 90 W, conveyor speed of 0.24 m/min-1, and layer thickness of 18 mm can be suggested for drying Tarom Hashemi paddy variety. The seed breakage percent in the proposed conditions for Tarom Hashemi was less than 10% for all of the conducted measurements.