Continuum-scale modeling of superheated steam drying of cellular plant porous media

Abstract

In this work, a continuous model is developed to describe the dynamics of heat and mass transfer in cellular plant porous media during the superheated steam drying process at atmospheric pressure. This model accounts for the advective liquid and vapor flows in the intercellular void space as well as for the diffusive liquid flow across the solid cell membranes of the porous medium. The numerical results are verified against drying experiments for potato samples, which were carried out by a magnetic suspension balance at three different superheated steam temperatures (160 °C, 180 °C, 200 °C). A comparison between the simulation results and the measured data shows that the drying characteristics of a plant porous medium can fairly be predicted by using the continuous model developed herein. The influence of the cell membrane water conductivity on the spatio-temporal distribution of the moisture content and of the temperature within the porous medium is studied by numerical simulations. It is observed that the water diffusion across the cell membranes controls the dynamics of the heat and mass transfer in the porous medium, and thus the drying kinetics.