A proposed numerical-experimental method for drying kinetics in a spray dryer

The drying of lime juice in a spray dryer was simulated using computational fluid dynamics (CFD) method. The lime juice powder was produced using 10% silicon dioxide and 20% maltodextrin (DE5) as additives. The air velocity distribution as the continuous phase was presented. A one way coupling was considered in the simulation of interaction between continuous phase and discrete phase (lime juice droplets). The air flow simulation presented two distinct high and low velocity zones. The trajectory of particles showed that a higher fraction of droplets deposited on the conical wall whereas a smaller fraction deposited on the cylindrical wall. The increment of the inlet air temperature caused an increase in the drying rate. Based on experimental results of moisture content variation along the length of chamber and numerically estimated residence time of droplets, drying kinetic of lime juice in spray dryer was determined. A parametric study carried out to investigate the effects of some important parameters such as droplet diameter and inlet air temperature. (c) 2008 Elsevier Ltd. All rights reserved.