Numerical model of heat and mass transfer during roasting coffee using 3D digitiszed geometry

Nowadays roasters are equipped with electric control board, thermo-regulator device, display for temperatures and on-line sensors to detect defects and/or the roasting end, depending on coffee types and blends and the desired roasting degree. It is important to have a good control of the roasting process in order to obtain a high quality final beverage. For the process optimisation the relationship between process and product parameter have to be studied. Most of literature studies [1,2,3] refer to models based on simplified geometry, particularly spherical or semi-ellipsoid geometries. As a consequence it should be useful to assess the solution obtained by simplified geometry models. The aim of this work was to develop a numerical model based on a 3D digitized geometry. The model is able to describe and predict the heat and moisture transfer, inside the coffee bean, during the roasting process in a rotating cylinder roaster, in natural convection conditions. The model was then validated with experimental data observed in a pilot plant.