A continuum model for airflow, heat and mass transfer in bulk of chicory roots

This article presents a transient 3D CFD model of heat and mass transfer in bulks of chicory roots. The model consists of the system of conservation equations of momentum, energy, and mass for the air phase, and the energy and mass for the product phase without considering the internal gradient in temperature and moisture in the product phase. The interaction between the airflow and the porous media is described by an Ergun-type equation based on experimental data. Heat of respiration is included in the model as an empirically derived function of temperature. A finite volume code is used to solve the model equations. The results show a good agreement between the model and the experiments. Differences between predicted and measured weight loss only amount to a maximum 10% after the initial cooling period. The non-ideal experimental conditions (high velocity low relative humidity of the air), the various sizes of the products, the small scale of the porous region compared to the size of the product, and the estimation of transfer correlations contribute to the observed differences between experiment and simulation. The model can be applied to study the cooling process in an industrial cold store to find the optimal process settings to improve product quality and reduce product weight loss.