Drying characteristics of green pellets based on the Weibull and Dincer models

The drying of green pellets is a critical step in the pellet production process. To optimize and control the drying process of green pellets, it is essential to understand the green pellets moisture variation over time under different drying conditions. This study investigates the impact of various drying conditions on the drying characteristic of green pellets and evaluates the applicability of the Weibull and Dincer models in describing the drying process of green pellets. The results show that the drying process of green pellets can be divided into acceleration and deceleration periods, with no constant-rate period. Increasing the drying air temperature and air velocity, decreasing the drying layer weight, and reducing the green pellets diameter help shorten the drying completion time of green pellets. The Weibull and Dincer models can accurately describe the drying behavior of green pellets, providing a simple yet reliable method for determining the moisture diffusivity and mass transfer coefficient values during the drying process of green pellets. The calculations of β and Bi values suggest that the drying process of green pellets is limited by both internal and external moisture transfer resistances. The activation energy E_a value for the drying process of green pellets is calculated to be 13.56 ​kJ ​mol⁻¹.