Numerical simulation and experimental characterization of nanoparticle synthesis in flame spray processes

火焰喷涂过程中纳米粒子合成的数值模拟和实验表征

• 批准号: 375857992
• 负责人: Professor Dr.-Ing. Frank Beyrau
• 金额: --
• 依托单位: Institut für Technische Verbrennung (ITV)
• 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/375857992?language=en
• 关键词: Numerical; simulation; experimental; characterization; nanoparticle

Flame spray synthesis offers numerous possibilities for the production of custom-made nanoparticles. However, the interactions of spray, turbulence, phase transition, precursor decomposition, chemistry and particle formation are so complex that our understanding of the process is rather incomplete. During the first funding period, a reference burner and reference conditions and material systems were agreed upon. Experiments and models for the description of the complex processes were developed. In the second funding period, experiments and models shall be extended, and adapted for the optimised reference burner and new material systems. The new design of the reference burner now needs to be characterised using a variety of experimental techniques (Particle Image Velocimetry, Phase-Doppler Anemometry, Laser-induced Fluorescence, Elastic Light Scattering and Multiple-Angle-Light –Scattering). These methods alone are only partially useful in multi-phase systems. Hence, the advantages of combining imaging diagnostics and numerical simulations developed in funding period 1, will be applied for particle diagnostics. In order to achieve meaningful validation of models, despite the inherent ambiguities, we will compare synthetic signals, generated by the numerical simulations directly with experimental signals. The modelling is based on a stochastic method called Multiple Mapping Conditioning (MMC). This method allows for a detailed and efficient description of all processes involved including their interactions. Following the results of FP1 and the expected changes of the reference system, new challenges arise. New boundary conditions need to be defined and the new nozzle design including partial premixing of the dispersion gases may require an extension of the modelling that allows for the description of stratified flames. Furthermore, the description of the transport of nanoparticles shall be decoupled from transport for the gaseous phase to account for the different diffusive fluxes of the two phases.Finally, the – so far mostly ignored – microexplosions of the precursor-solvent mixtures will be investigated. Microexplosions were reported for the most standard material systems of the SPP in single droplet experiments and it can be assumed, that conventional evaporation models, based on phase equilibria – cannot describe the evaporative fluxes with sufficient accuracy. Hence, the occurrence of microexplosions in the SpraySyn configuration shall be verified experimentally for the first time and semi-empirical models for the description of this process shall be developed and implemented in the simulations.

火焰喷涂合成为定制纳米颗粒的生产提供了多种可能性。然而，喷雾，湍流，相变，前驱体分解，化学和颗粒形成的相互作用是如此复杂，以至于我们对该过程的理解是相当不完整的。在第一个供资期间，商定了一个参考燃烧器和参考条件以及材料系统。开发了用于描述复杂过程的实验和模型。在第二个资助期内，实验和模型将得到扩展，并适用于优化的参考燃烧器和新材料系统。现在需要使用各种实验技术（粒子图像测速、相位多普勒测速、激光诱导荧光、弹性光散射和多角度光散射）来表征参考燃烧器的新设计。这些方法单独在多相系统中仅部分有用。因此，在第1个供资期开发的成像诊断和数值模拟相结合的优势将应用于粒子诊断。为了实现有意义的模型验证，尽管固有的模糊性，我们将比较合成信号，直接与实验信号的数值模拟产生的。建模是基于一种称为多重映射条件（MMC）的随机方法。这种方法允许详细和有效地描述所有涉及的过程，包括它们的相互作用。在FP 1的结果和参考系统的预期变化之后，出现了新的挑战。需要定义新的边界条件，新的喷嘴设计包括弥散气体的部分预混，可能需要扩展模型，以便描述分层火焰。此外，纳米粒子的运输的描述应解耦运输的气相占不同的扩散通量的两个phase.Finally，到目前为止，大多被忽视的微爆炸的的吸附剂-溶剂混合物将进行调查。据报道，最标准的材料系统的SPP在单液滴实验中的微爆炸，它可以假设，传统的蒸发模型，相平衡的基础上，不能描述的蒸发通量具有足够的精度。因此，应首次通过实验验证SpraySyn配置中微爆炸的发生，并应在模拟中开发和实施用于描述该过程的半经验模型。