Measurement and numerical simulation of moisture transport within potash beds as a prelude to moisture migration caking

As one kind of hygroscopic salts, potash readily absorbs large quantities of water vapor from air during storage and transportation processes. Accumulated moisture will further penetrate into a potash bed to cause serious caking. To study moisture migration within a potash bed, an experimental test apparatus was constructed to investigate the moisture redistribution of a potash bed. A one-dimensional mathematical model with physically realistic representation of moisture transport processes was developed to simulate moisture migration. Based on Whitaker's theory, a model accounting for vapor diffusion, and liquid film movement by capillarity and gravity effects was fully implemented. An adsorption/desorption model was used to determine the phase change rate. The numerical model is validated using experimental data with a small range of uncertainty for particle sizes that have a small size range. Numerical simulation results show that predictions agree with the experimental results within the 95% uncertainty bounds.