SIMULATION OF SPRAY DRYING OF A SOLUTION ATOMIZED IN A PULSATING FLOW

Spray drying of NaCl solution was carried out under an intense oscillating flow field generated by a pulse combustor. A pulse combustion spray drying system was constructed. An optical analyzer was used to measure the particle diameter distribution of droplets atomized by a pulsating flow. The momentum, heat and mass transfer in both gaseous and particulate phases during spray drying inside the drying chamber were simulated using the computational fluid dynamics method. The simulated profiles of flow field, temperature and humidity of the gaseous phase, as well as the particulate phase, in the drying chamber were presented. The simulation showed changes of the flow field and particle trajectories in the drying chamber during one pulsating period. A large-scale vortex was observed in the upper part of the drying chamber because of the unstable state of flow field and particle trajectories. Short drying time and large evaporation rate are characteristics of pulsating spray drying. The influence of gas stream pulsation frequency on the drying process is also analyzed.