Drying comparison of nonhygroscopic and hygroscopic materials

摘要

This paper investigates and presents the simulation of drying for hygroscopic andnonhygroscopic materials. This present work used a coupled mathematical model of mass, heat andgas transfer that implemented to finite element method in two dimensional and numericallycompute using Skyline solver to capture highly nonlinear transient process. Bound watercontribution was taken into account in the drying of hygroscopic materials by incorporatingconstitutive equation of bound water. The results showed drying process can be divided into threeperiods named constant rate period (CRP), first falling rate period (FRP1) and second falling rateperiod (FRP2). Capillary action is dominated during CRP before vapour diffusion takes place inFRP1. Bound water movement is generated by vapour pressure gradient exists that representhygroscopic material.