In this work the estimation of moisture diffusivity in carrot is attempted. In the theoretical part, moisture diffusivity is defined and the available methods of evaluating moisture diffusivity are briefly described .
20 drying experiments at different conditions are realised. The simplified method of slopes is used in order to estimate moisture diffusivity in carrot. During the experiments, constant-rate period was supressed and the succession of two falling-rate periods was observed. A Fickian diffusion coefficient for each falling-rate period is estimated. Moisture diffusivity calculated for carrots in this work, is in the range 1.7836 10-9 - 3.7408 10-8m2/sec for the first falling-rate period and in the range 6.6637 10-10 -1.572610·8 2/sec for the second falling-rate period. The experimental result are represented by an Arrhenius type of relationship. The energy of activation for water diffusion is calculated equal to 921.7 KJ/Kg.
The effect of external factors [Tφ (°C), % R.H., u(m/sec)] on moisture diffusivity as well as the succession of drying periods are examined. The assumptions of the model used and the limitations of the simplified method are also discussed.