Investigation of drying kinetics of finger millet in fluidized bed dryer

S. Uma Maheswari, R. Kumaresan

Abstract

Finger millet (Ragi) is a highly nutritious cereal, rich in calcium, proteins, iron and other minerals. Drying technique is usually employed to preserve Ragi for a longer time. In this work, the drying process was carried out in laboratory scale fluidised bed dryer and the drying kinetics was studied. The experimental data were made to fit with fifteen thin layer models and the model with best fit was chosen based on the statistical analysis values of R2, RMSE and SSE. The best fit models were Modified Henderson and pabis model, Midilli model and Modified Page model II with maximum R2 values and minimum RMSE, SSE values. The experiments were also carried out to study the effect of temperature and velocity of air, initial moisture content and loading of ragi on drying time. By using fick’s diffusion equation the effective diffusivity values were determined and they varied between 3.26 x 10-10 and 1.29 x 10-9 m2/minute. The activation energy value varied between 19.318 and 59.78 kJ/mol. The heat and mass transfer co-efficient for a single particle of Ragi was also calculated.