Spray Conditioning for the Preparation of Spray Dried Submicron Particles

[EN] Particle size reduction down to the submicron range (0.1-1 µm) is an effective option to increase the bioavailability of low water soluble active pharmaceutical ingredients. According to the Nernst-Brunner equation, the preparation of submicron sized particles increases the specific surface area, thus increases the dissolution rate. Conventional spray drying devices for submicron particles show certain limitations. The main challenge is the preparation of small and uniform droplets during the atomisation step. In this work, fine droplets were generated combining a nozzle with a droplet separator. Therefore, the aerosol is generated with a pneumatic nozzle and is sprayed into a cyclone droplet separator. Depending on the characteristics of the cyclone, droplets larger than the cut-off-size were separated and returned into the liquid feed. The conditioned aerosol at the top of the cyclone separator can then be introduced into the drying chamber. With this concept the usable part is separated, thus no classification process after drying is necessary. The investigations show that the dependencies during atomisation of the droplets size on the liquid-to-gas mass flow ratio µm and the liquid properties (e.g. viscosity) do not apply to the separation step. The conditioned aerosol only depends on the separation characteristics of the cyclone droplet separator. However, the amount of droplets separated is determined by the atomisation step. Hence, the amount of droplets smaller than the cut-off-size can be increased by decreasing the droplet size of the primary aerosol. This is realised by secondary droplet fragmentation. An impact surface causes breakup of the droplets of the primary aerosol before separation. The investigations show an increased amount of droplets <2µm.Gorny, R.; Schaldach, G.; Walzel, P.; Thommes, M. (2017). Spray Conditioning for the Preparation of Spray Dried Submicron Particles. En Ilass Europe. 28th european conference on Liquid Atomization and Spray Systems. Editorial Universitat Politècnica de València. 162-166. https://doi.org/10.4995/ILASS2017.2017.4701OCS16216

Discutindo a educação ambiental no cotidiano escolar: desenvolvimento de projetos na escola formação inicial e continuada de professores

A presente pesquisa buscou discutir como a Educação Ambiental (EA) vem sendo trabalhada, no Ensino Fundamental e como os docentes desta escola compreendem e vem inserindo a EA no cotidiano escolar., em uma escola estadual do município de Tangará da Serra/MT, Brasil. Para tanto, realizou-se entrevistas com os professores que fazem parte de um projeto interdisciplinar de EA na escola pesquisada. Verificou-se que o projeto da escola não vem conseguindo alcançar os objetivos propostos por: desconhecimento do mesmo, pelos professores; formação deficiente dos professores, não entendimento da EA como processo de ensino-aprendizagem, falta de recursos didáticos, planejamento inadequado das atividades. A partir dessa constatação, procurou-se debater a impossibilidade de tratar do tema fora do trabalho interdisciplinar, bem como, e principalmente, a importância de um estudo mais aprofundado de EA, vinculando teoria e prática, tanto na formação docente, como em projetos escolares, a fim de fugir do tradicional vínculo “EA e ecologia, lixo e horta”.Facultad de Humanidades y Ciencias de la Educació

Comparison of Experimental and Numerical Transient Drop Deformation during Transition through Orifices in High-Pressure Homogenizers

The droplet deformation in dispersing units of high-pressure homogenizers (HPH) is examined experimentally and numerically. Due to the small size of common homogenizer nozzles, the visual analysis of the transient droplet generation is usually not possible. Therefore, a scaled setup was used. The droplet deformation was determined quantitatively by using a shadow imaging technique. It is shown that the influence of transient stresses on the droplets caused by laminar extensional flow upstream the orifice is highly relevant for the droplet breakup behind the nozzle. Classical approaches based on an equilibrium assumption on the other side are not adequate to explain the observed droplet distributions. Based on the experimental results, a relationship from the literature with numerical simulations adopting different models are used to determine the transient droplet deformation during transition through orifices. It is shown that numerical and experimental results are in fairly good agreement at limited settings. It can be concluded that a scaled apparatus is well suited to estimate the transient droplet formation up to the outlet of the orifice

genehmigt durch die Fakultät für Verfahrens- und Systemtechnik der Otto-von-Guericke-Universität Magdeburg. Gutachter:

The out-flowing behavior of particles at the discharge end of rotary kiln