Kinetics and Modeling of the Heat and Mass Transfer During the Solar Drying of Cassava Slices Under Natural Convection Mode

The kinetics and modeling of heat and mass transfer during the solar drying of cassava slices integrated with the pebble's sensible thermal storage material (PSTSM) were investigated. Fifteen thin layer drying models were adopted to model the drying curves following standard criteria for fitness. The maximum temperatures were 52.5 °C and 55 °C for plywood drying chamber (PLC) and Perspex glass chamber (PGC), respectively. It took both drying systems with Perspex and plywood chambers 38 h to reduce the moisture content of cassava slices from 56% w.b. to 10.62 and 15.20% w.b., respectively. The effective moisture diffusivity (D_e) for the system with Perspex glass and plywood chambers were 6.28 × 10⁻¹⁰ m²/s and 4.53 × 10⁻¹⁰ m²/s, respectively. The activation energy values were 20.56 kJ/mol and 20.82 kJ/mol for the system with Perspex and plywood, respectively. The mass transfer coefficient values for the cassava slices dried in Perspex and plywood were 1.70 × 10⁻⁶ and 1.67 × 10⁻⁶ m/s, respectively. At the same time, the heat transfer coefficients were 2.63 and 2.08 W/m².K. The Midilli et al. and modified Henderson and Pabis models were adjudged the best to describe the solar drying of cassava slices using the Perspex and plywood drying chamber, respectively. Therefore, the obtained results would be useful in the design of solar drying equipment for agricultural products under natural convection mode.