Review of Moisture Movement Mechanisms in Plant Tissues Using Transfer Models in Porous Media – Part I: Moisture Transfer Models

Water transfer in plant tissues is a complex phenomenon. The cell wall and plasma membrane are permeable to water and the amount of water exchange among cells and the intercellular space mainly depends on the amount of intracellular water pressure and the viability of the cell membrane. The movement of water within the plant tissues includes simultaneous heat and mass transfer and therefore the thermophysical properties of the plant tissue plays an important role in this transition. Capillary pressure, intrinsic permeability, relative permeability, effective moisture diffusivity, and thermal conductivity are the key thermal and transport properties needed for comprehensive investigation of moisture transfer mechanism in plant tissue. The plant material can be considered as a porous medium in a non-steady state, which contains about 10 - 80% water. Molecular diffusion for gases (water vapor and air), capillary influence for the liquid (water) and advection mechanisms (Darcy flow) are used in the drying model in porous media. Thus, multiphase models can be used to study the water movement in plant tissues. In multiphase models of transmission mechanism, transfer of water into two types of liquid and gas is investigated simultaneously under the influence of temperature and other properties of plant tissue. In this article, the plant tissue is considered as a porous medium and the factors affecting the moisture transfer in these tissues are discussed.