Modeling of Humidity Evolution During Solar Drying of Cassava in a Ventilated Attic

In Africa, it is possible to take advantage of the heat provided by metal roofs (constantly exposed to the sun) for the drying of agricultural products to reduce post-harvest losses. For this purpose, a prototype ventilated attic equipped with shelves is built and tested on the drying of cassava. For 6 kg of manioc, it takes three days to dry in the prototype. The modeling of moisture growth in the drying air is carried out by the fourth-order Runge-Kutta method. The theoretical results allow predicting the variation of moisture in the air of the attic with accuracy. Modeling of the manioc drying curve is made using five semi-empirical models. The Midili-Kucuk model is the one that best predicts moisture content evolution in cassava, as it gives the highest value of the determination coefficient. As drying is a simultaneous heat and mass transfer phenomenon, the coefficients of heat and mass transfer evolutions were observed too. We noticed their increase with drying time. The presence of fresh products in the attic keeps its internal temperature lower than outside. When the products are no longer fresh, the temperature of the attic (on the products) increases. Polystyrene insulation on the ceiling, product bed and air circulation generated by chimneys help prevent heat from migrating through the ceiling. So, this attic has two advantages: the drying of products to extend its shelf life and reduction of heat in houses.