Simulation of a Spray Dryer Fitted with a Rotary Disk Atomizer Using a Three-Dimensional Computional Fluid Dynamic Model

Abstract

Spray dryers fitted with a rotary disk atomizer are widely used in many industries requiring high throughputs to produce powders from liquid streams. The interaction between droplets or particles and the drying medium within the drying chamber is still not well understood and hence difficult to model reliably. In this article CFD results are presented to describe the behavior of the performance of a spray dryer fitted with a rotary disk atomizer in a cylinder-on-cone chamber geometry. Four different turbulence models, i.e., standard k − ε, RNG k − ε, Realizable k − ε, and Reynolds stress models were tested and compared to simulate the swirling two-phase flow with heat and mass transfer in the chamber. The results of this investigation can provide further insight into turbulent swirling flow modeling. The predicted results, such as, air flow patterns, air velocity and temperature, distributions, particle/droplet trajectories, drying performance etc., are obtained using the CFD code FLUENT6.1. Comparison with available limited experimental data shows that CFD results display reasonable agreement. Predicted results also show that the RNG k − ε model performs better in this specific case.

Keywords:

• CFD
• Air flow pattern
• Drying model
• Suspension
• Swirling flow
• Turbulent model
• Two-phase flow

Acknowledgments

The authors are grateful to Dr. Bhesh. Bhandari and Dr. Vinh Truong of University of Queensland, school of land and food sciences, for providing us with some of the data which are referenced in this article for a comparative analysis with our simulation model.