Developing and utilizing a mini food powder production facility to produce industrially relevant particles for functionality testing

In this thesis is presented research relating to a monodisperse droplet dryer for production of milk powder. The development and testing of several monodisperse droplet generators and lab-scale spray dryers was carried out. Furthermore, a number of down-scaled techniques for quality measurement were devised for analysis of the powder. Sufficient amounts of highly uniform powder could be dried to low moisture contents, using a range of feed solids concentrations and drying air temperatures. A single droplet drying model was created to simulate the situation, based on established mass and heat transfer equations and material specific kinetics using the Reaction Engineering Approach. Through a series of experiments varying drying temperature and feed solids content for a number of feed materials, the model was validated and its limits of accuracy were established. It successfully predicted the true final moisture contents and insolubilities in a range of conditions. The known and uniform temperature history and the regular particle sizes were then used to conduct original research on the formation of insoluble material during powder heat damage and the formation of particle morphology and shrinkage. Work was also done on spray freeze drying, thin layer drying, powder wetting, dissolution and the addition of surfactants.本论文围绕用于奶粉生产的单分散液滴干燥机开展相关研究。完成了多款单分散液滴发生器与实验室级喷雾干燥机的开发与测试工作。此外，针对粉体分析研发了多套小型化质量检测技术。通过调控进料固含量与干燥空气温度，可制备得到足量且高度均匀的低含水率粉体。本研究基于成熟的传质、传热方程与反应工程法（Reaction Engineering Approach）的材料专属动力学特性，构建了单液滴干燥模型以模拟该干燥过程。通过针对多种进料物料开展干燥温度与进料固含量双变量调控的系列实验，完成了该模型的验证，并确定了其精度适用范围。该模型可在多种工况下准确预测粉体的最终真实含水率与不溶物含量。借助已知且均匀的温度历程与规整的颗粒粒径参数，本研究开展了原创性探索：针对粉体热损伤过程中不溶物的生成机制，以及颗粒形貌与收缩行为的形成规律展开研究。此外，本研究还涉及喷雾冷冻干燥、薄层干燥、粉体润湿性、溶解特性以及表面活性剂添加等相关研究内容。