Influence of Flow interrupters in Infrared Drying Column on Temperature of the paddy grains

Abstract

This research aimed to investigate the influence of flow obstructions on the movement of paddy grains within a drying chamber utilizing infrared heaters as the heat source. The objective was to raise the grain temperature from an initial 30 – 31°C to a target of 42 – 43°C. A prototype paddy dryer was employed in the experiments, using Khao Dawk Mali 105 rice variety. Each sample weighed 1.5 kilograms with an initial moisture content ranging from 22% to 25% wet basis. Experiments were conducted at air temperatures of 60°C and 80°C, with a controlled paddy flow rate of 1.5 kilograms per minute. Three types of flow obstructions were tested: alternating fin barriers, expanded metal mesh, and an unobstructed (empty) drying chamber. The results indicated that these factors significantly affected the time required for the paddy to reach the target temperature. The unobstructed drying chamber at an air temperature of 80°C required the shortest heating time, taking only 3.3 minutes to reach 42 – 43°C. Furthermore, the lowest energy consumption, at 0.10 kilowatt - hours, was observed in both the unobstructed chamber at 60°C and the alternating fin barrier at 60°C. In an additional drying experiment with an initial moisture content of 24% wet basis, the grains were dried to a final moisture content of 14% wet basis. It was found that the unobstructed chamber required the shortest drying time at 95 minutes, whereas the alternating fin barrier configuration required 140 minutes a difference of 32.14%.