Investigation on the usage of effervescent atomization for spraying and spray drying of complex rheological food liquids and on the resulting particle and product properties

喷雾干燥是粉状食品生产中的关键工序。为了降低成本和提高产率，在进料中使用较少的水和较高的固体含量是有利的。这可以是单相或多相进料，其通常表现出复杂的流变行为。如果进料的粘度由于较高的固体含量而增加，则使用常规压力雾化器更难以实现雾化。在较高的粘度下，使用气动雾化器将是有益的，然而它们通常由于高气体消耗而下降。因此，本研究项目着重于使用一种特殊的内部混合气动雾化器，称为喷雾雾化器，用于喷雾和喷雾干燥，它具有特别低的气体消耗。这项建议的主要目标是研究原子化的科学基础。这将使其能够用于复杂的复合食品，并在喷雾干燥过程后控制所得粉末的特性。将建立基本的工艺和性能功能，以允许特定的产品开发和颗粒特性控制（递归工艺设计）。这需要液滴的雾化和干燥的定义和示例性描述。颗粒结构及其对产品性能的影响也需要建立所需的工艺和性能函数。从以前的结果开始，一个焦点将是窄液滴尺寸分布和稳定喷雾所需的工艺参数。除了ALR（工艺参数）对喷雾性能的影响，雾化器内的流动模式的调查将具有优先权。因此，这将是不同的实验工作和2D/3D模拟（由合作伙伴进行）的主题。关于这一点，将采用一个由分项目B10（Weigand）发明和使用的数学模型。这将有助于确定雾化器的相关几何参数，以调整其设计，以达到预期的喷雾效果。第二个重点将是与传统雾化过程相比，反式雾化的分类和评级。为此目的，将检查喷雾性能、雾化效率以及其对多相进料（乳液）的内部结构的影响。此外，还将研究生产者和消费者感兴趣的选定产品特性。

Spray drying is the key process step in the production of powdery food. For cost reduction and improved yield, it is favorable to use less water and a higher solid content in the feed. This may be single-phase or multiphase feeds, which often show a complex rheological behavior. If the viscosity of the feed increases due to a higher solid content, atomization is more difficult to achieve with conventional pressure atomizers. At higher viscosities, the use of pneumatic atomizers would be beneficial, however they are often declined due to a high gas consumption. Therefore, this research project focuses on the use of a special internal mixing pneumatic atomizer called effervescent atomizer for spraying and spray drying, which has a particularly low gas consumption. The main goal of this proposal is to investigate the scientific fundamentals of the effervescent atomization. This will enable its usage for complex compounded foods and control of the resulting powder characteristics after the spray drying process. Essential process and property functions will be established in order to allow specific product development and control of the particle characteristics (recursive process design). This requires the definition and exemplary description of the atomization and the drying of the drops. The particle structure and its influence on product properties is also needed to establish the desired process and property functions. Starting from previous results, one focus will be on the process parameters required for narrow drop size distributions and stable sprays. Investigations on the influence of the flow pattern inside the atomizer in addition to ALR (process parameter) on the spray performance will have priority. Therefore, this will be the subject of different experimental work and 2D/3D-simulations (to be conducted by cooperation partners). Concerning this, a mathematical model invented and used by subproject B10 (Weigand) will be applied. It will help to identify relevant geometrical parameters of the atomizer for aligning its design to achieve the desired spraying results.Second focus will be the categorization and rating of the effervescent atomization compared to conventional atomization process. For this purpose, the spray performance, the efficiency of atomization as well as its influence on the inner structure of multiphase feeds (emulsion) will be examined. Furthermore, selected product properties which are of interest for producer and consumer will be studied.