Numerical simulation of heat and moisture transfer in fibrous porous media dehydration process with ultrasound assisted

摘要

In recent decades, the enhancement of ultrasound on heat and mass transfer in the processes of food processing, waste sludge dehydration and silica gel regeneration has been confirmed by experiments and simulations. The effect of ultrasound in the dehydration process of fibrous porous media has been experimentally studied, however, the theoretical simulation is still lacking, which will be presented in this paper. In the first place, the effects of ultrasound frequency and intensity on ultrasound propagation in fibrous porous media are investigated. For the pressure and deformation produced by ultrasound propagation in porous media, ultrasound intensity has an important influence on their magnitude, and their distribution trend is also affected by ultrasound frequency. Then, the fundamental heat and mass transfer process in fibrous porous media with ultrasound assisted dehydration is studied and the mathematical model is validated by experiments in terms of the drying curves under different ultrasound intensity. By numerical simulation, the distribution of liquid transmission velocity, temperature and dry basis moisture content are obtained which is useful to further analyse the mechanism of ultrasound enhancement in fibrous porous media dehydration. (C) 2019 Published by Elsevier Ltd.