Mathematical modelling of the nanopowders production in Inductively Coupled Plasma reactors

纳米粉末的生产是一项已经产生重要工业影响的纳米技术，由于其尺寸接近分子尺寸，其性质与散装材料不同。这些材料通常具有全新的特性。与具有相同化学组成的微米粉末相比，纳米氧化铝粉末、纳米铈或纳米复合材料具有增强的机械、化学、光学、磁性和电子性质。例如，几十年来一直用作铁磁记录材料的微米尺寸的氧化铁在室温下获得纳米尺寸的超顺磁性能力。含能材料是纳米粉体性质变化的例子，与微米级等效物相比，纳米铝粉具有强烈的尺寸依赖性的自燃性。在工业规模生产纳米粉末的技术中，电感耦合等离子体（ICP）具有许多优点：高温蒸发任何类型的前体，相对较大的尺寸和受控化学环境的低速度。由于这种反应器中的流动、温度和浓度场可能非常复杂，并且由于在这种反应器中产生的纳米粉末在很大程度上取决于这些场，因此完整的表征在ICP纳米粉末生产反应器的设计中是最重要的。该计划的目标是开发ICP反应器中纳米粉末生产的数学模型，使科学家和工程师能够设计和优化反应器。该项目将首先涉及物理化学现象的基本数学建模研究，涉及：1）均匀成核理论2）纳米颗粒表面反应速率3）纳米颗粒聚集。它还将涉及应用数学、数值和工程研究，将涉及：1）热等离子体中纳米颗粒产生的数学建模的最新技术2）粒子数平衡方程求解方法的实施和验证（矩量法和节点法）3）工业热等离子体反应器中使用的淬火方法的全面三维建模研究4）在开源平台OpenFOAM中对数值模型进行优化。

The production of nanopowders, whose properties differ from the bulk material due to their size close to molecular dimensions, is a nanotechnology that has already had an important industrial impact. Often these materials have completely new properties. Nanometallic powders, nanoceramics or nanocomposites have mechanical, chemical, optical, magnetic and electronic properties that are enhanced compared to micrometric powders with the same chemical composition. For example, micron- sized iron oxide which is has been used as a ferromagnetic recording material for decades acquires at nanometric sizes super-paramagnetic capabilities at room temperature. Energetic materials are examples of nanopowders properties change compared to the micrometric equivalent, nano-aluminum powders have a spontaneous ignition strongly size-dependent. Among the technologies available to produce nanopowders at industrial scale, the Inductively Coupled Plasma (ICP) presents numerous advantages: high temperatures to vaporize precursors of any type, relatively large size and low velocities with a controlled chemical environment. As the flow, temperature and concentration fields in such reactors can be very complex, and since the nanopowders produced in such reactors depend heavily on these fields, a complete characterization is of outmost importance in the design of ICP nanopowders production reactors. It is the objective of this program to develop a mathematical model of the nanopowders production in an ICP reactor that will enable scientists and engineers to design and optimize the reactors. The project will involve first a fundamental mathematical modelling study of the physico-chemical phenomena dealing with: 1) homogeneous nucleation theory 2) nanoparticle surface reaction rates 3) nanoparticle aggregation. It will further involve an applied mathematical, numerical and engineering study that will deal with: 1) the state of the art of the mathematical modelling of nanoparticle production in thermal plasmas 2) the implementation and validation of the Population Balance Equations solution methods (Method Of Moments and Nodal methods) 3) a comprehensive 3-D modelling study of the quenching methods used in industrial thermal plasma reactors 4) the optimization of the numerical model in the open-source platform OpenFOAM.