A large amount synthesis of nanopowder using modulated induction thermal plasmas synchronized with intermittent feeding of raw materials

Tanaka, Yasunori; Tsuke, T.; Guo, Weixuan; Uesugi, Yoshihiko; Ishijima, Tatsuo; Watanabe, Shuichi; Nakamura, Keitaro

doi:10.1088/1742-6596/406/1/012001

Cited by 22 publications

(30 citation statements)

References 26 publications

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“…In the actual experiment, the powder reaches to the PMITP in a finite time after inputting the opening signal to the solenoid valve. This finite time was measured in our previous work as another delay time t adt of 6-8 ms [21]. Therefore, the actual total delay time is (t d + t adt ) ≃ (t d + 7) ms before the powder is actually injected to the PMITP.…”

Section: Methodology Of a Large-scale Nanopowder Synthesis Systemmentioning

confidence: 90%

“…Here, our developed method is described briefly for synthesis of large amounts of nanopowders using a PMITP-TCFF, although it has been described in our previous paper [21].…”

Section: Methodology Of a Large-scale Nanopowder Synthesis Systemmentioning

confidence: 99%

“…In our previous work, the PMITP-TCFF method developed as explained above was adopted to synthesize pure TiO 2 nanopowder for mass production. Results show that this method using a 20-kW PMITP supported a production rate of about 500 g h −1 of pure TiO 2 nanopowder with mean particle diameter of about 43 nm [21].…”

Section: Introductionmentioning

confidence: 91%

“…The authors recently developed a new synthesis method of large amounts of pure oxide nanopowder without contamination using pulse-modulated induction thermal plasma (PMITP) with time-controlled feeding of feedstock (TCFF) [19]- [21]. The PMITP was developed by our group to control the temperature and chemical activity fields in thermal plasmas using coil-current modulation [23,24].…”

Section: Introductionmentioning

confidence: 99%

“…In addition to this, our group recently developed a method for feedstock powder injection, in which the feedstock powder is supplied intermittently to the thermal plasma periodically, in synchronization with the coil-current modulation of the PMITP. This intermittent and synchronized feeding of feedstock is a time-controlled feedstock feeding (TCFF) method [21,22]. The TCFF was combined with the PMITP for nanopowder synthesis.…”

Section: Introductionmentioning

confidence: 99%

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A method for large-scale synthesis of Al-doped TiO₂nanopowder using pulse-modulated induction thermal plasmas with time-controlled feedstock feeding

Kodama¹,

Tanaka²,

Kita³

et al. 2014

J. Phys. D: Appl. Phys.

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Abstract.A unique large-scale synthesis method for Al-doped TiO 2 nanopowder was developed using 20-kW Ar-O 2 pulse-modulated induction thermal plasmas (PMITP) with time-controlled feedstock feeding (TCFF). This PMITP-TCFF method is characterized by intermittent feedstock powder feeding synchronized with modulated power of the PMITP. The method enables heavy-load feeding of raw material powder to the thermal plasmas for complete evaporation. Synthesized nanopowder was analyzed using different methods including FE-SEM, XRD, BF-TEM, TEM/EDX mapping, XPS, and spectrophotometry. Results showed that Al-doped TiO 2 nanopowder can be synthesized with mean diameters of 50-60 nm. The Al doping in TiO 2 was confirmed from the constituent structure in XRD spectra, the uniform presence of Al on the nanopowder in TEM/EDX mapping, the chemical shift in XPS spectra, and the absorption edge shift in the optical property. The production rate of Al-doped TiO 2 nanopowder was estimated as 400 g h −1 .

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Section: Methodology Of a Large-scale Nanopowder Synthesis Systemmentioning

confidence: 90%

“…Here, our developed method is described briefly for synthesis of large amounts of nanopowders using a PMITP-TCFF, although it has been described in our previous paper [21].…”

Section: Methodology Of a Large-scale Nanopowder Synthesis Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

A method for large-scale synthesis of Al-doped TiO₂nanopowder using pulse-modulated induction thermal plasmas with time-controlled feedstock feeding

Kodama¹,

Tanaka²,

Kita³

et al. 2014

J. Phys. D: Appl. Phys.

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Modeling and simulation of a turbulent‐like thermal plasma jet for nanopowder production

Shigeta

2018

IEEJ Transactions Elec Engng

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This paper discusses theoretical models and numerical methods to simulate turbulent thermal plasma flow transporting a nanopowder. In addition to a thermal plasma flow model, a sophisticated model is described mathematically for the nanopowder's collective growth by homogeneous nucleation, heterogeneous condensation, and coagulation among nanoparticles, and also transport by convection, diffusion, and thermophoresis, simultaneously. Demonstrative simulations show clearly that a suitable numerical method with high‐order accuracy should be used for long and robust simulation capturing multiscale eddies and steep gradients of temperature, which are the turbulent features of thermal plasma flows with locally variable density, transport properties and Mach numbers. Eddies are first generated at the interfacial region between the plasma jet and ambient nonionized gas by fluid‐dynamic instability. As a result of the eddies' generation–breakup process, the plasma flow entrains the ambient cold gas and deforms its shape traveling downstream. Numerous sub‐nanometer particles are generated by nucleation and condensation in the thin layers near the plasma jet. Those particles diffuse and increase their size, thus decreasing their number by coagulation. Cross‐correlation analysis suggests that the nanopowder distribution distant from a plasma jet can be controlled by controlling the temperature fluctuation at the upstream plasma fringe. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

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Simulating Turbulent Thermal Plasma Flows for Nanopowder Fabrication

Shigeta

2020

Plasma Chem Plasma Process

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This article presents descriptions of theoretical models and numerical methods for simulating turbulent thermal plasma flow with nanopowder growth. Turbulence models must express turbulent and laminar states because both states co-exist with thermal plasmas showing large density variation and transport properties. Time-dependent 3D simulations are conducted based on Large Eddy Simulation using a dynamic Smagorinsky model. Results show significant difference depending on temporal and spatial discretization schemes and velocity-pressure coupling algorithms. Simulation results demonstrate that advanced numerical methods with high-order accuracy should be used for long and robust computations capturing steep gradients of nanopowder concentration and plasma temperature and 3D dynamic motions of multiscale vortices, which are turbulent features of thermal plasma flows with low Mach numbers. A thermal plasma jet generates a doublelayer structure of inner high-temperature thick vortex rings and outer low-temperature thin vortex rings near the nozzle exit. Flowing downstream, these vortices interact, deform, and break up. Consequently, plasma transits to a complex thermal flow. The widely spreading distribution of multiscale vortices agrees with experimental observations, which are not simulated using conventional methods. Nanopowder is generated from material vapour by nucleation and condensation at interfacial regions between plasma and cold gas. Those regions include numerous vortices. Therefore, the vortices convey the nanopowder, producing a complex distribution of nanopowder. Simultaneously, the nanopowder diffuses and increases in size, decreasing in number by interparticle coagulation. Cross-correlation analysis suggests that a nanopowder distribution distant from a plasma jet can be controlled through temperature fluctuation control at the upstream plasma fringe.

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A large amount synthesis of nanopowder using modulated induction thermal plasmas synchronized with intermittent feeding of raw materials

Cited by 22 publications

References 26 publications

A method for large-scale synthesis of Al-doped TiO₂nanopowder using pulse-modulated induction thermal plasmas with time-controlled feedstock feeding

A method for large-scale synthesis of Al-doped TiO₂nanopowder using pulse-modulated induction thermal plasmas with time-controlled feedstock feeding

Modeling and simulation of a turbulent‐like thermal plasma jet for nanopowder production

Simulating Turbulent Thermal Plasma Flows for Nanopowder Fabrication

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A large amount synthesis of nanopowder using modulated induction thermal plasmas synchronized with intermittent feeding of raw materials

Cited by 22 publications

References 26 publications

A method for large-scale synthesis of Al-doped TiO2nanopowder using pulse-modulated induction thermal plasmas with time-controlled feedstock feeding

A method for large-scale synthesis of Al-doped TiO2nanopowder using pulse-modulated induction thermal plasmas with time-controlled feedstock feeding

Modeling and simulation of a turbulent‐like thermal plasma jet for nanopowder production

Simulating Turbulent Thermal Plasma Flows for Nanopowder Fabrication

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Product

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A method for large-scale synthesis of Al-doped TiO₂nanopowder using pulse-modulated induction thermal plasmas with time-controlled feedstock feeding

A method for large-scale synthesis of Al-doped TiO₂nanopowder using pulse-modulated induction thermal plasmas with time-controlled feedstock feeding