Abstract

The thin layer drying kinetics of pellets millet flour was studied at drying air temperatures of 40, 50 and 60°C using a constant air velocity of 1.0 m/s for pellets size 2.5 mm < d₁ < 3.15 mm and 5 mm < d₂ < 6.30 mm. Ten thin layer drying models were evaluated by fitting the experimental moisture data. The goodness of fit of each model was evaluated using the coefficient of determination (R²) the reduced chi-square () and root means square error (RMSE). Among these models, the modified Henderson and Pabis model is the best one to describe the behaviour in the drying of pellets millet. The effective diffusivity has been found to be varying between 4.4676 × 10^-9 and 31.94 x 10^-9 m²/s and activation energy was 33.048 and 42.658 kJ/mol for pellets size of d₁ and d₂ respectively.

Key words: Thin layer drying, mathematical modelling, effective diffusivity, activation energy.