Three-Dimensional Numerical Investigation of a Mono-Disperse Droplet Spray Dryer: Validation Aspects and Multi-Physics Exploration

Abstract

Many studies have been carried out on using CFD to explore spray drying phenomena.However, due to the complexity of the drying process in a conventional spray dryer that may include the wide droplet size distribution, complicated particle trajectory and difficulty in taking on-line measurements, validation of the computational codes or the models remains a challenging task. In this study, experimental conditions employed in a more defined spray drying condition, published recently on spray drying of mono-disperse skim milk droplets in a vertical cylindrical chamber, are simulated using ANSYS FLUENT.We have examined the effects of droplet-dispersion patterns on the drying results and found ways to incorporate more practical shrinkage models into the code to make simulations more realistic. Through a comparison with the relevant experimental results on 10~50 wt% skim milks published recently by the same group, we have identified a few areas that urgently need more detailed future research. Using the revised sets of codes established here, we simulated skim milk droplets (with a uniform size between 180 m to Downloaded by [Columbia University] at 00:42 03 February 2015 2 220 m) spray dried by 90°C to 180°C hot air streams. The quantitative drying history data predicted by our new model would help understanding the system better.

An effective rate approach to modeling single‐stage spray drying

“…This facility has demonstrated unique potential in validating a set of predictive models (from 1-D to 3-D), which has led to an improved understanding of the spray drying system. [19][20][21]28,[31][32][33] Process description and system specification Three basic steps are usually involved in a spray drying process: the atomization of the feed into a spray of fine droplets, the evaporation of droplets by a stream of heated gas and finally, the separation of the dried powder from the gas stream at the dryer exit. For the monodisperse droplet spray dryer investigated in this work, a schematic of its main drying chamber is given in Figure 1.…”

“…This phenomenon may affect particle structure, and it is of interest to quality control in spray drying. 31 Effects of Initial Droplet Size. Monodisperse spray dryer provides us with unique opportunities to explore the effects of initial droplet size on product formation during spray drying.…”

“…The predictions shown in Figure 3 should be satisfactory considering the uncertainties in experimental results. Actually, the prediction precision of the current ERA model is not lower than that of a comprehensive CFD model (see CFD results in Yang et al, 2015). 31 …”

Implementation of P-Controller in Computational Fluid Dynamics (CFD) Simulation of a Pilot Scale Outlet Temperature Controlled Spray Dryer

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Mathematical modeling of moisture evaporation in co-current foam spray drying

“…In the falling drying rate period, particle can shrink due to thermal deformations of solidified crust. Particle shrinkage can be determined using modified equation proposed by Chen [6]:…”