HEAT AND MASS-TRANSFER MODELING IN AIR-DRYING OF FOODS

Heat and mass transfer modeling in the air drying of solids is conside red as a two stage procedure. The former aims to discover the dominant heat and mass transfer phenomena (heat versus mass, internal versus e xternal), the latter aims to formulate empirical equations for the cal culation of the corresponding heat and mass transport properties (mass diffusivity, thermal conductivity, boundary heat and mass transfer co efficients). A model discrimination procedure was proposed in the firs t stage, and a model building procedure was examined in the second sta ge. The proposed procedures were applied to a wide set of experimental data in potato drying. The resulting model takes into account moistur e diffusion and convective heat and mass transfer in the air boundary layer. Moisture diffusivity is dependent an material moisture content and temperature, while heat and mass transfer coefficients can be cons idered as constants.