Modeling of multiphase heat and mass transport and drying behavior of potash particles in a packed bed: Experiments and simulation

Abstract

The drying behavior of potash particles was experimentally investigated in a convective packed bed dryer under different operating conditions, including inlet gas temperature of 40 °C, 50 °C, and 60 °C, moisture content of 2.8 wt%, and superficial gas velocity of 0.3 m/s. When the temperature increased from 40 °C to 50 °C and then to 60 °C, the drying time decreased from 930 s to 870 s and then to 720 s, respectively. The thermal conductivity and specific heat capacity of potash particles as a function of moisture content and porosity of the packed bed was determined at a 95 % confidence interval to have R2 values of 0.94 and 0.91, respectively. During drying of potash particles, solid bridges form, and the whole bed behaves like a porous medium with void spaces that expand. In this work, a conjugate heat and mass transfer model was developed for batch packed bed drying of wet potash particles. Computational fluid dynamics was used to simulate the momentum, mass, and energy transport in a porous medium based on the physical properties of potash particles. The model successfully correlated the experimental particle moisture content versus time with average absolute deviation percentage values of 14.8, 3.2, and 14.7 for the inlet gas temperatures of 40 °C, 50 °C, and 60 °C, respectively.