One-dimensional simulation of co-current, dairy spray drying systems – pros and cons

Abstract

-One-dimensional (1-D) simulation is a useful technique for the evaluation of dryer operating parameters and product properties before conducting real spray drying trials. The main advantage of a 1-D simulation tool is its ability to perform fast calculations with significant simplicity. Mathematical models can be formulated using heat, mass and momentum balances at the droplet level to estimate time-dependent gas and droplet parameters. One of the purposes of this paper is to summarize key mathematical models that may be used to perform 1-D simulation for spray drying processes, predict essential product-drying gas parameters, assess the accuracy of prediction using pilot-scale spray drying data and perhaps most importantly address the main benefits and limitations of the 1-D simulation technique in relation to industrial spray drying operations. The results of a recent international collaborative study on the development of spray drying process optimization software for skim milk manufacture are presented as an example of the application of 1-D simulation in milk processing.spray drying / one-dimensional simulation / modeling / drying kinetics / dairy product / droplet drying Article published by EDP Sciences à l'échelle de la gouttelette pour estimer les paramètres de vapeur et de gouttelette qui varient au cours du temps. Un des objectifs de cet article est de présenter de façon synthétique les modèles mathé-matiques clés qui peuvent être utilisés pour réaliser une simulation 1-D, prédire les paramètres de vapeur essentiels pour le séchage du produit, évaluer la précision de la prédiction en utilisant les données du séchage par atomisation obtenues à l'échelle pilote, et enfin d'aborder les principaux bénéfices et limites de la technique de simulation 1-D en relation avec les opérations de séchage par atomisation industrielles. Les résultats d'une récente étude réalisée en collaboration internationale sur le développement d'un logiciel d'optimisation du procédé de séchage par atomisation pour la production de poudre de lait écrémé sont présentés pour illustrer l'application de la simulation 1-D.séchage par atomisation / simulation mono-dimensionnelle / modélisation / cinétique de séchage / produit laitier / séchage d'une gouttelette

Drying colloidal systems: Laboratory models for a wide range of applications

“…In other words, this equation is the "fingerprint" of a material's drying behavior. These kinetics data can be implemented into simulation programs home-made [41,42] or commercially available computational fluid dynamics modeling software with specific user established operating files for scale up studies and industrial spray dryer design [43][44][45][46].…”

An effective rate approach to modeling single‐stage spray drying

“…7,18 In model development, the spray dryer was treated as a 1-D plug-flow reactor having a cocurrent flow and all the spherical-shaped droplets in the dryer at the same altitude were assumed to have identical properties. Here, we briefly summarize the 1-D model (i.e., a set of ordinary differential equations).…”

“…Readers can refer to our previous papers for detailed derivations. 8,10,12,18 All variables together with their units are listed in the Notation section. The critical part of this model is the Reaction Engineering Approach (REA) that describes the drying kinetics…”

“…In the most simplistic manner, the modeling typically follows a "black-box" approach in which the powder coming out from the system is assumed to be completely dried. 9,18 These methods are based on simple mass and energy balances, which can hardly offer comprehensive and reliable predictions. The other extreme is to use advanced fluid flow modeling which captures very detailed phenomena in the process at the expense of time and resources required for computer simulation.…”

“…For a onedimensional (1-D) drying process, these PDEs can be simplified as a set of ordinary differential equations (ODEs). 7,18 Mathematically, this 1-D model can be written as a set of coupled ODEs in a general formatwhere x 1 , x 2 ,. .…”