Drying kinetics and moisture diffusivity analysis of paddy in fluidised bed drying process

The drying kinetics and moisture diffusivity of paddy are studied in a fluidised bed dryer in this article. Different values of temperatures of drying air (T) at 45°C, 50°C and 55°C, velocities of drying air (V) at 2m/s, 2.5m/s and 3 m/s and paddy inventory (I) of 2 kg and 3 kg are used for drying paddy. The moisture content of paddy is reduced to a final value of around 12% (wb) from an initial value of around 28% (wb). Results showed that as the temperature and velocity of drying air increased, the drying rate also increased whereas, the drying rate decreased with an increase in paddy inventory. The moisture diffusivity is found to be increased as temperature and velocity of drying air increases, but it decreases with the inventory. A regression equation is obtained from linear regression analysis relating effective moisture diffusivity with all the drying process variables. With increase in drying air velocity and paddy inventory, the average activation energy decreases.