tailieunhanh - Multiscale simulations of spray drying process

In this paper, a multiscale study of spray drying process with skim milk served as drying product is presented. Firstly, a characteristic drying curve model is developed to describe the heat and mass transfer of single droplet drying process. | . Journal of Science & Technology 130 (2018) 070-075 Multiscale Simulations of Spray Drying Process Thi Thu Hang Tran* Hanoi University of Science and Technology – No. 1, Dai Co Viet Str., Hai Ba Trung, Ha Noi, Viet Nam Received: December 09, 2017; Accepted: November 26, 2018 Abstract Spray drying process for powder production is widely commercialized in diary industrial sector. In this paper, a multiscale study of spray drying process with skim milk served as drying product is presented. Firstly, a characteristic drying curve model is developed to describe the heat and mass transfer of single droplet drying process. The parameters of the characteristic drying curve model are established based on the experimental observation. Then, the single droplet drying characters are incorporated into a computational fluid dynamic (CFD) solver to customize the heat, mass and momentum transfer between the droplet/particle and the drying agent flow inside a spray dryer. The CFD simulation results are validated by comparing against the experimental data observed on a pilot-scale spray dryer. A good agreement between numerical and experimental result on both of fluid phase and particle properties indicates the predictability of the CFD simulation. The influence of the drying conditions on the drying efficiency of the tower is also explored in detail. Keywords: spray drying, CFD simulation, single droplet drying model, characteristic drying curve model, skim milk 1. Introduction1 challenging [12,13]. Spray drying modelling is a useful solution for this issue. However, the modelling approach also faces various obstacles such as lacking similarity in the dynamics of small and large spray dryers, the complicated air flow and the different trajectories of particles, the dependence of product quality on particle heating history in the tower, and the difficulty in determining the drying kinetics of droplets/particles during spray drying [14]. Spray drying is one of the most commonly