Abstract:

The volume shrinkage characteristics of porous materials in the drying process are investigated based on the definitions of Volume Shrinkage Coefficient and Shrinkage Isotropicity,with fresh ginger,carrot,potato and ba-nana as the drying materials.The relationship between the volume reduction of the material and the removed mois-ture is then analyzed,and the efects of the drying stream temperature and the relative humidity on the shrinkage characteristics are also discussed.Th e results show that a fast drying rate will result in great volume shrinkage,and that the microstructure of the porous materials significan tly afects the shrinkage characteristics.A dimensionless moisture difusion model is also presented in this paper for the drying of potato ,the obtained results of which accord well with the experimental ones.

Key words: porous material, drying, volume, shrinkage characteristic