Modelling the pneumatic drying of food particles

A one-dimensional model for pneumatic drying of food particles is presented. The model includes mass, momentum and energy transfer between the gas and the solid phases, taking into account variations of properties with humidity and temperature as well as solid shrinkage during drying. A plug-flow assumption is made for the dryer model and the non-spherical shape of particles is considered in drag and heat transfer coefficients. The set of coupled non-linear ordinary differential equations is solved numerically for the velocity, moisture and temperature of particles and air along the dryer. The model is applied to simulate the drying of potato particles under different conditions. Model predictions are used to illustrate the complex transport phenomena that occur during the process and the profiles of temperature, moisture content and pressure developed through the dryer. Effects of mass flowrates ratio, velocity and temperature of air, shape and size of particle on drying time and final moisture content of the material are studied.