Modeling heat and mass transfer during drying of green coffee beans using prolate spheroidal geometry

A heat and mass transfer model in prolate spheroidal coordinates system was proposed to describe the drying of green coffee beans. The model describes the 3D moisture and temperature profiles inside the bean. The results were integrated over volume in order to obtain a drying kinetic equation for prolate spheroidal geometry. The average effective diffusivity of water as function of temperature and moisture was estimated at 45 and 60 °C by slope method from experimental drying kinetic of green coffee beans. The expression obtained applied to drying kinetic equation reproduced approximately the experimental behavior.