Multi-objective Investigation and Optimization of Paddy Processing in a Hot Air Dryer

Abstract

In order to investigate the convective drying of paddy kernels, process time, required energy and head rice yield (HRY) were experimentally measured for different combination of air temperature (40, 55 and 70 °C), velocity (0.6, 1 and 1.4 m/s), drying bed height (18, 25 and 32 cm), and final moisture content of paddy (8, 10 and 12% wet basis). According to the results, at higher temperatures, and for the end-products with higher moisture contents, lower energy was required for drying process, but by increasing the air velocity and sample's bed height the amount of consumed energy increased. The conducted experiments also showed that by changing the drying parameters, HRY varied from 36.32 to 80.56 %. The response surface methodology (RSM) and desirability factor were also used to find optimized conditions and showed that for samples with bed height 18 cm, the convective drying with 59 °C, 0.6 m/s, until the final moisture content of 0.09% wet basis, provides a maximum desirability of 0.791.