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了重要工业影响的纳米技术，由于其尺寸接近分子尺寸，其性质与块状材料不同。通常，这些材料具有全新的特性。与相同化学成分的微米粉末相比，纳米金属粉末、纳米陶瓷或纳米复合材料具有更高的机械、化学、光学、磁性和电学性能。例如，几十年来一直被用作铁磁记录材料的微米级氧化铁在室温下获得了纳米级的超顺磁性能力。含能材料是纳米粉末性质变化的例子，与微米当量相比，纳米铝粉具有强烈的自燃特性，尺寸依赖性强。在工业规模生产纳米粉末的现有技术中，感应耦合等离子体(ICP)具有许多优点：蒸发任何类型的前体的高温、相对较大的尺寸和较低的速度以及受控的化学环境。由于这种反应器中的流动、温度和浓度场可能非常复杂，而且在这种反应器中产生的纳米粉末严重依赖于这些场，所以在设计ICP纳米粉末生产反应堆时，一个完整的表征是最重要的。本项目的目标是建立一个在等离子体反应器中生产纳米粉末的数学模型，使科学家和工程师能够设计和优化反应堆。该项目将首先涉及一个基本的物理化学现象的数学模型研究，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。它将进一步涉及一个应用的数学模型，数值和工程研究将涉及：1)热等离子体中纳米粒子生产的最新数学模型的现状2)粒子数平衡方程求解方法(矩量法和节点法)的实施和验证3)工业热等离子体反应堆中使用的淬火方法的综合三维建模研究4)开源平台OpenFOAM中的数值模型的优化。

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 theory2) nanoparticle surface reaction rates3) 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 plasmas2) 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 reactors4) the optimization of the numerical model in the open-source platform OpenFOAM.