Modeling of multi-phase moisture transfer and induced stress in drying clay bricks

In this study, transfer of heat and mass of all phases and the induced stresses in structural ceramics during the falling rate period of the drying process are considered. Based on the principles of non-equilibrium irreversible thermodynamics and assuming an isotropic porous system, the macroscopic laws of conservation and the liquid-vapor equilibrium relation of the green clay brick, a set of nonlinear equations for the prediction of simultaneous mass and heat transfer (luring the drying process is developed. Based on the obtained results of the histories of pore pressure and temperature from the nonlinear equations, the induced stresses can be calculated from the combination of the Biot theory and the Boley theory. The final result reveals that pore pressure instead of temperature in the porous system plays the dominant role in the determination of stress distribution during the falling rate period of a drying process, which is consistent with previous observations.