EXPERIMENTAL-STUDY OF THE HEAT AND MASS-TRANSFER DURING DRYING IN A FLUIDIZED-BED DRYER

Drying curves obtained in a pilot-scale fluidized bed dryer using biol ogical source solids (sawdust, soya and fish meal) were used to estima te the parameters involved in heat and mass transfer phenomenas: heat transfer coefficient and moisture diffusivity coefficient. Parameters involved in mass transfer were estimated from drying models based on d iffusional mechanisms and others that in addition consider internal an d external resistance to the mass transfer. The estimated effective di ffusivity coefficient was between 2x10(-11) to 1x10(-9) (m(2)/s) for t he considered products. Heat transfer coefficient was estimated from d rying data points in the constant drying rate period when the external resistance to the mass transfer controls the process.