Multi-scale and multi-layer structural modeling and simulation of heat and mass transfer processes for drying of grain packing porous media

Aiming at the problem of multi-layer physical structure for the skeleton of porous media, a multi-scale and multi-layer structural model of heat and mass transfer processes for drying of grain packing porous media was established by applying the pore network method and multi-scale theory. An experimental study on rice drying was conducted in order to validate this model. The simulation and experimental results indicated that the established model could explain the mechanical properties of rice drying well. There was a higher moisture gradient inside the rice grain. The diffusion coefficient of rice embryo played an important role in the drying process, and whose effect on drying was larger than the diffusion coefficient of rice hull and chaff. The moisture was imprisoned effectively inside the rice when the diffusion coefficient of rice embryo was very small.