Drying kinetics of high moisture paddy undergoing vibration-assisted infrared (IR) drying

Abstract

Both heating and drying of high moisture paddy using vibrating platform coupled with infrared heating source dryer give uniform but quick drying by exposing each and every grain uniformly to the IR source. A laboratory apparatus capable of modulating both frequency and amplitude of vibration had been developed to study vibration aided drying characteristics of high moisture paddy. The effective moisture diffusivity of the grain during drying under this mode has been evaluated. The drying characteristics of high moisture paddy was studied under different vibrating conditions for five levels of radiation intensity (1509, 2520, 3510, 4520 and 5514 W/m 2) and four levels of grain bed depths (single kernel thickness of 3, 6, 12 and 25 mm). The optimum frequency and amplitude of the vibrations were found to be in the range of 20–22 Hz and 8–9 mm for all the three grain bed depths of paddy (25, 12 and 6 mm) for obtaining nearly complete and uniform mixing (mixing index ≅ 1.0) [Das, I., Das, S.K., Bal, S., 2003a. Determination of mixing index of paddy grains under vibrating conditions. Journal of Food Process Engineering 26 (2), 121–133]. Drying occurred almost under falling rate period. The value of the average effective moisture diffusivity ( D eff) avg ranged between the 0.778 × 10 −10 and 3.884 × 10 −10 m 2/s for different drying treatments. Both the radiation intensity and grain bed depth found to have significant effect on the ( D eff) avg value at 1% level of significance.