A Mathematical Model for Ultrafine Iron Powder Growth in a Thermal Plasma

Bilodeau, Jean‐François; Proulx, Pierre

doi:10.1080/02786829608965362

Cited by 46 publications

(31 citation statements)

References 25 publications

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“…For this, the following assumptions are further introduced in this work [29]: (1) spherical droplets; (2) negligible droplet inertia; (3) identical velocity and temperature of a droplet to those of the gas flow; (4) negligible heat generation caused by condensation; (5) negligible electric charge of a droplet; (6) lognormal size distribution; (7) the composition of a droplet at a local position is independent on the droplet size; (8) the effect of SWCNTs grown from a droplet is totally ignored, even though SWCNTs have a significant impact on the droplet generation and its transport. The GDE can be written as Nano Res (2009) 2: 800 817 then the co-condensation term can be written as, l Lastly, in a free molecular regime, the collision kernel between droplets with volume v d and v d s is written as [36], E It is very difficult to solve the above GDE directly because of its non-linearity. Up to now, s several methods have been proposed to solve this equation, for instance, the discrete sectional method, t the moment method, and the quadrature moment d method.…”

Section: Carbon-metal Liquid Droplet Formation Modelmentioning

confidence: 99%

“…7. The boundary conditions employed in previous thermal plasma modeling were used here for the calculations of thermofluid, electromagnetic fields, species, and the three moments [26,29,36]. As a typical example, the boundary conditions used in the plasma equations for the thermofluid fields, whereas the vector potential equation for the electromagnetic field and the moment transport equations were solved using the user defined functions (UDFs) approach.…”

Section: Swnt Nucleation and Growth Modelmentioning

confidence: 99%

“…In this method, the droplet a size distribution function is assumed to follow a lognormal distribution, and then the À g rst three moments are calculated using À the following equations, r The zeroth moment is the mean droplet number e density, whereas the first moment represents the e mean volume of the droplets produced. By using the o moment method, the GDE can be transformed into s these three steady-state moment transport equations [36]. 0 th moment:…”

Section: Carbon-metal Liquid Droplet Formation Modelmentioning

confidence: 99%

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Synthesis of single-walled carbon nanotubes by induction thermal plasma

Moradian

Mostaghimi

et al. 2009

Nano Res.

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The production of high quality single-walled carbon nanotubes (SWCNTs) on a bulk scale has been an issue of considerable interest. Recently, it has been demonstrated that high quality SWCNTs can be continuously synthesized on large scale by using induction thermal plasma technology. In this process, the high energy density of the thermal plasma is employed to generate dense vapor-phase precursors for the synthesis of SWCNTs. With the current reactor system, a carbon soot product which contains approximately 40 wt% of SWCNTs can be continuously synthesized at the high production rate of ~100 g/h. In this article, our recent research efforts to achieve major advances in this technology are presented. Firstly, the processing parameters involved are examined systematically in order to evaluate their individual inÁuences on the SWCNT synthesis. Á Based on these results, the appropriate operating conditions of the induction thermal plasma process for an effective synthesis of SWCNTs are discussed. A characterization study has also been performed on the SWCNTs produced under the optimum processing conditions. Finally, a mathematical model of the process currently under development is described. The model will help us to better understand the synthesis of SWCNTs in the induction plasma process. KEYWORDSSingle-walled carbon nanotubes (SWCNTs), large-scale continuous synthesis, radio frequency (RF) induction thermal plasma, optimization, numerical modeling Nano ResearchOver the past decade, the superlative properties of single-walled carbon nanotubes (SWCNTs) [1] have attracted much attention for their use in a wide range of applications, including microelectronic [2], biomedical [3], polymer [4], energy [5], and environmental [6] devices. Consequently, the economical production of high quality SWCNTs on a large scale has become an issue of considerable interest. To date, there have been tremendous efforts to develop new synthesis methods leading to the economical production of SWCNTs and it has been shown that SWCNTs can be produced by many 801 Nano Res (2009) 2: 800 817 different ways, such as arc discharge, laser ablation, arc-jet plasmas, chemical vapor deposition (CVD), non-equilibrium plasmas, and combustion methods.Recently, it was demonstrated that high quality SWCNTs can be continuously synthesized, on a large scale, by the method of simultaneous direct evaporation of carbon black and metal/metaloxide catalyst mixtures, using induction thermal plasma technology [7]. In this process, the high energy density of the thermal plasma is employed to generate dense vapor-phase precursors for the synthesis of SWCNTs. The main advantages of this process are that the rate of input carbon is not limited by the rate of electrode erosion and that SWCNTs are synthesized in the free space without any substrates. Before undertaking optimization efforts, it was shown that a carbon soot product which contains approximately 40 wt% of SWCNTs can be continuously synthesized at production rates of over 100 g/h.The primary goal ...

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Section: Carbon-metal Liquid Droplet Formation Modelmentioning

confidence: 99%

Section: Swnt Nucleation and Growth Modelmentioning

confidence: 99%

Section: Carbon-metal Liquid Droplet Formation Modelmentioning

confidence: 99%

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Synthesis of single-walled carbon nanotubes by induction thermal plasma

Moradian

Mostaghimi

et al. 2009

Nano Res.

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“…of nanoparticles in spite of its much simpler mathematical form than the often-used model which is known as the method of moment [8] [9] [10] [11] [12], [16]. By virtue of its simplicity, the computation can be performed with a lower computational cost than other models [8]- [13], [16].…”

Section: Nanopowder Growth and Transportmentioning

confidence: 99%

Numerical Study of Axial Magnetic Effects on a Turbulent Thermal Plasma Jet for Nanopowder Production Using 3D Time-Dependent Simulation

Shigeta¹

2018

JFCMV

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Abstract3D time-dependent simulations are performed using a computational method suitable for thermal plasma flows to capture a turbulent field induced by a thermal plasma jet and steep gradients in nanopowder distributions. A mathematical model with a simple form is developed to describe effectively simultaneous processes of growth and transport of nanopowder in/around a thermal plasma flow. This growth-transport model obtains the spatial distributions of the number density and mean diameter of nanopowder with a lower computational cost. The results show that an argon thermal plasma jet induces multi-scale vortices even far from itself. A double-layer structure of high-temperature thicker vortex rings surrounded by low-temperature thinner vortex rings is generated in the upstream region. As the vortex rings flow downstream, the high-temperature thicker vortex rings deform largely whereas the low-temperature thinner vortex rings break up into smaller vortices. Nanopowder is generated at the fringe of plasma and transported widely outside the plasma region. The nanopowder grows up collectively by coagulation decreasing particle number as well as homogeneous nucleation and heterogeneous condensation. When a uniform magnetic field is applied in the axial direction, a longer and straighter thermal plasma jet is obtained because of Lorentz force and Joule heating. Larger nanopowder is produced around the plasma because turbulent diffusions of silicon vapor and nanoparticles by vortices are suppressed as well.

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“…Plasma thermo-fluid dynamics calculations rely on the following assumptions, which have been widely adopted in literature [5,16]:…”

Section: Plasma Modellingmentioning

confidence: 99%

Design-Oriented Modelling of Different Quenching Solutions in Induction Plasma Synthesis of Copper Nanoparticles

Bianconi

Boselli

Gherardi

et al. 2017

Plasma Chem Plasma Process

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The aim of this paper is to compare the effects of different mechanisms underlying the synthesis of copper nanoparticles using an atmospheric pressure radiofrequency induction thermal plasma. A design oriented modelling approach was used to parametrically investigate trends and impact of different parameters on the synthesis process through a thermo-fluid dynamic model coupled with electromagnetic field equations for describing the plasma behaviour and a moment method for describing nanoparticles nucleation, growth and transport. The effect of radiative losses from Cu vapour on the precursor evaporation efficiency is highlighted, with occurrence of loading effect even with low precursor feed rate due to the decrease in plasma temperature. A method to model nanoparticle deposition on a porous wall is proposed, in which a sticking coefficient is employed to model particle sticking on the porous wall used to carry a quench gas flow into the chamber. Two different reaction chamber designs combined with different quench gas injection strategies (injection through a porous wall for "active" quenching; injection of a shroud gas for "passive" quenching) are analysed in terms of process yield and size distribution of the synthetized nanoparticles. Conclusion can be drawn on the characteristics of each quenching strategy in terms of throughput and mean diameter of the synthesized nanoparticles.

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A Mathematical Model for Ultrafine Iron Powder Growth in a Thermal Plasma

Cited by 46 publications

References 25 publications

Synthesis of single-walled carbon nanotubes by induction thermal plasma

Synthesis of single-walled carbon nanotubes by induction thermal plasma

Numerical Study of Axial Magnetic Effects on a Turbulent Thermal Plasma Jet for Nanopowder Production Using 3D Time-Dependent Simulation

Design-Oriented Modelling of Different Quenching Solutions in Induction Plasma Synthesis of Copper Nanoparticles

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