Numerical simulation of centrifugal spray drying based on single-droplet evaporation

In order to analyze the physical field distribution and droplet movement pattern inside centrifugal spray dryer, a three-dimensional steady-state mathematical model of the spray drying process was established by using the Euler-Lagrange method coupling the single-droplet drying model. Experiments were conducted on a pilot-scale centrifugal spray drying system using 70% (wet basis) maltodextrin solution as the feedstock, and the temperature distribution inside the dryer was measured. The results showed that the simulated temperatures at characteristic points agreed well with the experimental values with 1.84% of average relative error, demonstrating the accuracy and reliability of the simulation results. Examination of continuous phase transfer process revealed that the three-dimensional physical field showed a cylindrically asymmetric distribution, having higher temperatures, lower water vapor contents, and greater airflow velocities at the center area of the tower. Analysis of droplet movement trajectory and drying process found that larger droplets had longer drying times, while smaller droplets had shorter drying times but longer residual time due to the occurrence of swirling and backflow. The effects of inlet air temperature, atomization disc rotation speed, and inlet air angle on the physical field distribution and droplet drying behavior inside the tower were studied by simulation, and the mass and heat transfer mechanism of spray drying process were analyzed. © 2024 Chemical Industry Press Co., Ltd.. All rights reserved.