Modelling of coupled heat and mass transfer for combined infrared and hot-air drying of sweet potato

This study aims to develop a numerical model to accurately predict moisture content and temperature distribution for sweet potato during combined infrared and hot-air drying (IR-HAD). The coupled heat and mass transfer during drying was simulated considering both temperature and shrinkage dependent diffusivity. The simultaneous heat and mass transfer model were solved using COMSOL Multiphysics, considering 2-D axisymmetric geometry. The IR energy input was determined by the Lambert's law. The simulation results were further evaluated based on data obtained from experiments conducted, showing that the model could adequately describe the coupled heat and mass transfer process of sweet potato during combined IR-HAD (R-2 = 0.986-0.996). The IR was also shown to be the most influential factor with regards to the heat transfer rate during the combined IR-HAD. The developed model can serve as a good basis for applications in other agricultural crops under different drying conditions. (C) 2018 Elsevier Ltd. All rights reserved.