Modelling and simulation of drying phenomena with rheological behaviour

Foods have high moisture contents which are lost during the drying process. This water loss can produce important changes in size that hinder the analysis of heat and mass transport. A model of simultaneous heat and moisture transfer in parallelepiped-shaped potato samples was coupled with a model of its elastic behaviour. Governing equations and boundary conditions were solved numerically using the finite difference method. To check the validity of the mathematical model, drying experiments were carried out. Experimental conditions were as follows: drying temperatures of 38, 42 and 47 degrees C; relative humidities of 14, 20 and 23% and air velocities of 1.5, 3 and 4.5 m/s. The different air velocities and temperatures were used in the drying process to determine their effects on drying time. It was obtained the range of moisture content in the sample and the range of temperature and stress during drying time. Comparison between predicted and experimental results provides satisfactory agreement.