Heat And Mass Transfer And Hygrothermal Stress Analysis In Porous Media

The thesis is mainly on the research of the process of heat and mass transfer in porous media and the analysis of hygrothermal stress induced by temperature and moisture effect by taking building materials as an engineering background.Based on Luikov's equations as coupling model , porous media is treated as virtual continuous body in macro-scale. The process of transient coupled heat and moisture transfer in one-dimensional and two-dimensional porous structures are simulated with the finite difference method. The transient distribution of temperature and moisture content of hollow cylinder and plate are obtained. Transient boundary conditions are assumed for heat and moisture transfer at external surface, which is more reasonable. Besides,the influence of dimensionless numbers to the process of heat and mass transfer is discussed, which is useful to understand the process more deeply.The constitutive equations under hygrothermal effect are discussed by applying the thermal elastic mechanic theory to the condition of coupled temperature and moisture. Hygrothermal stress of hollow cylinder and plate are analyzed and the transient distribution of displacement and hygrothermal stress are simulated. Thermal stress and hydro stress are studied respectively, which finding the impact of temperature and moisture to the hygrothermal stress. The research of hygrothermal stress provides some reference for crack analysis of porous media.