SIMULATION OF VACUUM DRYING PROCESS OF WET PARTICLE PACKED BED IN A CONTAINER

Abstract

The purpose of this study is to predict the drying rate and the temperature and water distributions in the packed bed of porous particles in a water-containing state. We made a physical model of the drying process in a cylindrical bed and examined the heat and mass transfer resistances required for it. In this paper, the incorporation of these resistances into the CFD parameters and the comparison results between the predicted and experimental values of the evaporation amount were presented. The calculation result of the amount of evaporation reproduced well the experimental value. The wall heat transfer coefficient and the evaporation rate coefficient were found to improve the reproducibility of the calculations. Although the calculated temperatures underestimated the experiments, the tendency shown by the experiments was reproduced. The validity of the physical model was confirmed. Next, it was confirmed that the liquid saturation in the bed decreased from the periphery to the center of the bed. In addition, the liquid saturation on the vapor permeability had a large effect on the vapor flow distribution in the bed. Furthermore, it was found that the effect of liquid saturation on the effective thermal conductivity in the bed cannot be ignored.