An investigation of the influence of two-stage drying conditions on convective drying of porous materials

A numerical study is carried out to investigate the influence of multistage drying regimes on the drying kinematics of a porous material. In particular the effects of varying the conditions of the drying medium are studied. The drying model for the solid is developed based on the continuum approach. A series of simulations of the drying behaviour of a rectangular brick with varying temperature, heat transfer coefficient and relative humidity of the drying medium are undertaken. It is found that the total drying time is mainly dependent on the relative humidity of the drying medium. Also condensation is predicted on the surface of the brick, with the quantity of condensation being directly linked to the relative humidity and temperature of the drying medium. Overall it is concluded that multistage drying regimes are useful in reducing the overall drying time whilst avoiding detrimental shrinkage during the constant drying period