Numerical Analysis of Heat and Mass Transfer During Convective Drying of Cassava Chips in Nigeria

This study develops and validates a numerical model of simultaneous heat and mass transfer during convective drying of cassava chips, calibrated to the typical chip geometry and moisture content range encountered in Nigerian industrial cassava chip production. Accurate prediction of drying kinetics is essential for optimising industrial dryer design, reducing energy consumption, and maintaining product quality. Existing thin-layer drying models applied to cassava in Nigeria literature are empirical and do not capture the physical mechanisms of heat and moisture transport within the drying chip. This study develops a coupled partial differential equation model of internal moisture diffusion and external convective heat and mass transfer using the finite element method implemented in COMSOL Multiphysics. Model parameters including effective moisture diffusivity as a function of moisture content and temperature are determined from experimental drying data collected using cassava chips of TMS 30572 variety at controlled drying conditions in the University of Nigeria Nsukka food engineering laboratory. Model validation compares numerical predictions against independent experimental datasets at different drying conditions. Findings reveal that moisture diffusivity in cassava chips exhibits strong temperature dependence, with activation energy of 28 kilojoules per mole determined from Arrhenius fitting. The numerical model predicts moisture profiles and drying curves within 5 percent of measured values across a range of temperatures. The study contributes a physically based numerical drying model for Nigerian cassava and recommends its use for industrial dryer optimisation and scale-up.

Keywords: convective drying, numerical modelling, cassava chips, heat and mass transfer, Nigeria.