Precursor release in nanoparticle producing spray flames: Single droplet investigation of multicomponent mass transfer (within SPP 1980)

产生喷雾火焰的纳米粒子中的前体释放：多组分传质的单液滴研究（SPP 1980 内）

• 批准号: 373275335
• 负责人: Professor Dr.-Ing. Lutz Mädler
• 金额: --
• 依托单位: Fachgebiet Mechanische Verfahrenstechnik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/373275335?language=en
• 关键词: Precursor; release; nanoparticle; producing; spray; Precursor; release; nanoparticle; producing; spray

The aim of the SPP is a fundamental understanding and theoretically modelling of the entire flame spray pyrolysis process. To develop such a predictive process model for the spray flame synthesis of nanoparticles requires the understanding of many aspects and mechanisms. These include the multicomponent mass transfer from the liquid droplet phase to the gas phase and particle growth that includes oxide formation, nucleation, condensation, coagulation, coalescence and sintering.In the first project phase we could demonstrate the importance of the droplet micro-explosion effect on the homogeneity of nanoparticle production using flame spray pyrolysis precursors. Micro-explosions were especially found to be a vital mechanism for utilizing cheap nitride precursors in industry. In the last project phase strong progress was achieved in single droplet experiments that show the great importance of micro-explosions for effective production of homogeneous nanoparticles. The combustion and particle synthesis of different precursor-solvent systems were experimentally investigated and conceptual mechanism of droplet micro-explosion were deduced. A new double droplet generator and a 3D measurement technique using two time-synchronized high-speed cameras were developed to study double droplet combustion and micro-explosions. Rainbow refractometry was used to measure droplet temperature and composition changes during single droplet combustion of precursor/solvent droplets. A multicomponent diffusion limited model was developed to infer the internal temperature and concentration profiles. The experimental setup of digital in-line holography was constructed. The hologram formation and numerical reconstruction of non-burning droplets were developed. Preliminary holography experiments on single droplet combustion of precursor solutions were conducted. For the first time the luminous flame position above the droplet surface (flame standoff ratio) of single isolated burning droplets with micro-explosions was measured. The primary goal of our project proposal is to study the mechanism and role of micro-explosions in effective synthesis of nanoparticles in the flame spray pyrolysis process using single droplet experiments. To achieve this goal, we will broaden our analysis tools and develop and integrate chemiluminescence, pyrometry, laser-induced fluorescence techniques for single droplet experiments. In close collaboration with other research groups of the SPP we will develop and provide validation data for multicomponent mass transfer models for the precursor release from droplets into the gas phase that includes precursor decomposition, bubble nucleation, shell formation, droplet micro-explosions and mass transfer into the gas phase.

SPP的目的是对整个火焰喷雾过程的基本理解和理论上的建模。为了开发用于纳米颗粒的喷雾剂合成的这种预测过程模型，需要了解许多方面和机制。其中包括从液滴相位到气相和颗粒生长的多组分质量转移，包括氧化物形成，成核，凝结，凝结，凝结，结合和烧结。在第一个项目阶段，我们可以证明液滴微型揭示对使用火焰喷雾喷雾pyropersssors的同质性生产的重要性。特别发现微型探索是利用行业中廉价氮化物前体的重要机制。在最后一个项目阶段，在单滴实验中取得了强大的进步，这些实验表明，微观探索对于有效生产均匀纳米颗粒的重要性。实验研究了不同前体 - 溶剂系统的燃烧和颗粒合成，并推导了液滴微探索的概念机制。开发了一种新的双液滴发生器和3D测量技术，使用两个时间同步的高速相机开发了研究双液滴燃烧和微探索。在前体/溶剂液滴的单滴燃烧过程中，彩虹折射率用于测量液滴温度和组成变化。开发了多组分扩散限制模型，以推断内部温度和浓度曲线。构建了数字全息图的实验设置。开发了非燃烧液滴的全息图形成和数值重建。对前体溶液的单滴燃​​烧进行了初步全息实验。首次测量了带有微探索的单个隔离燃烧液滴的液滴表面（火焰对峙比）的发光火焰位置。我们项目建议的主要目的是使用单滴实验研究微探索在纳米颗粒有效合成纳米颗粒中的机制和作用。为了实现这一目标，我们将扩大分析工具，并为单滴实验开发和整合化学发光，热量计，激光诱导的荧光技术。在与SPP的其他研究小组的密切合作中，我们将开发并为从液滴释放到气相的多组分传质模型并提供验证数据，该模型包括前体分解，气泡成核，壳形成，螺栓形成，液滴微型探索和向气相中的质量转移。