Numerical simulation of pharmaceutical particle drying in a gas-solid fluidized bed using the CPFD method

Fluidized bed drying is a crucial step in the processing of pharmaceutical particles. This process involves complex gas–solid flow, encompassing interphase momentum, heat, and mass transfer. In this study, a numerical model for fluidized bed drying was established based on the computational particle fluid dynamics (CPFD) method to describe the flow, heat transfer, and mass transfer behaviors during drying. The accuracy of the model was validated by comparing predicted data with the experimental data. Building upon this validated model, the gas–solid flow characteristics and heat/mass transfer mechanisms within the dryer were systematically investigated, with a specific focus on the impact of inlet gas parameters (velocity, temperature) on drying kinetics. The results demonstrate that both the increasing of inlet gas velocity and temperature significantly enhances the moisture evaporation rate. However, raising the inlet gas temperature exacerbates drying nonuniformity. Conversely, increasing the inlet gas velocity enhances gas–solid mixing, thereby increasing drying uniformity. This model not only contributes to understanding the gas–solid flow and heat/mass transfer within fluidized bed dryers but also aids in the design and scale-up of fluidized bed drying processes.