Numerical Study of the Drying of Cassava Roots Chips Using an Indirect Solar Dryer in Natural Convection

Abstract

In this work, an indirect solar dryer for drying cassava root chips was modelled and experimentally validated using the environmental conditions of Yaoundé in Cameroon and Yamoussoukro in Ivory Coast. The dryers were operational in natural convection mode. Resolution of the equations was achieved by finite differences and the 4th order of Runge–Kutta methods. A model was proposed for performing heat and mass transfer using thermophysical properties of cassava roots, and the obtained results were satisfactory for all conditions, with moisture content difference of less than 0.2 kg/kg between the experimental and theoretical results. The model showed that the core of the product takes more time to dry, which always prolongs the drying duration. The heat and mass transfer coefficients vary during the entire process of solar drying. The drying kinetics vary during the drying with values lower than 1.2 × 10−4 kg/(kg.s). The great gradients of humidity were observed in the thickness of the sample with a regular distribution of the temperature each drying time in the thickness of the sample.

Keywords

• cassava roots
• desorption isotherms
• drying kinetics
• heat and mass transfer
• natural convection
• solar dryer