| Popis: |
Spray drying is a commonly used method in various industries to rapidly produce a dry powder from a liquid or slurry by removing the solvent from suspension within a high temperature gas. This method is preferred for producing milk powder in the dairy industry to extend the shelf-life of milk as well as making it easier for transportation. During this process, some of the partially wet milk droplets deposit on the chamber’s wall surface which is linked to the onset of biofouling. The main problem with biofouling is the reduced efficiency of the drying process, and can also be a serious health and safety hazard. Therefore, it is essential to improve the process of milk powder production in order to reduce the cost of production. A comprehensive CFD simulation of a spray dryer should couple droplet drying, non-isothermal airflow, droplet tracking and moisture transport submodels. This paper is focused on the key submodel, droplet drying, to find out how droplet mass and surface temperature are sensitive to the surrounding air temperature (Tg) and velocity (Vg). An implicit finite volume approach has been implemented to solve the governing equations to track the droplet’s morphological evolution, moisture content and temperature distribution. |
