Drying Characteristics of Porous Materials in a Fluidized Bed of Hygroscopic Porous Particles

摘要

The drying characteristics of a porous material immersed in a fluidized bed were examined.Some kinds of porous silica gel beads were used as the fluidizing particles.In a part of experiment,the glass bead(inert particle)was used as the fluidizing particle and the results were compared with the cases of silica gel beads.The numerical calculation of heat and mass transfers in the porous material was also performed.In this calculation,the liquid water transfer from the drying material to the fluidizing particle bed was considered in the cases of silica gel beads.The temperature and mass velocity of the drying gas were changed in experiment.In the cases of silica gel beads,the temperature decrement in drying which is observed in the case of glass bead does not appear.The phenomenon can be expressed by the numerical calculation including the liquid water transfer from the sample to the fluidizing particle bed.The drying time is shorter in the cases of silica gel beads than in the case of glass beads at the same mass velocity of the drying gas.The effects of the mass velocity of the drying gas and the heat transfer coefficient on the drying time are smaller than that of the kinds of fluidizing particles.The effects of the physical properties of the fluidizing particle on the drying time increase as the drying gas temperature becomes lower.