Computational fluid-particle dynamics for the flame synthesis of alumina particles

Johannessen, Tue; Pratsinis, Sotiris E.; Livbjerg, Hans

doi:10.1016/s0009-2509(99)00183-9

Cited by 132 publications

(87 citation statements)

References 21 publications

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“…flow rates and temperature gradients). The cr ystalline structure of the particles can be also adjusted by adding dopants to the feed stream (Vemury and Pratsinis 1995) and by controlling the temperature history of the particles, as has been demonstrated by Jiang et al (2007) and shown computationally by Johannessen et al (2000;2001) and Tsantilis et al (2002). The application of external electric fields has also been shown to provide good control of the physical and chemical characteristics of the produced particles (Vemury and Pratsinis 1995;Kammler and Pratsinis 2000;Kammler et al 2003).…”

Section: Flame Synthesismentioning

confidence: 97%

Generation and Sizing of Particles for Aerosol-Based Nanotechnology

Biskos

Vons

Yurteri

et al. 2008

KONA

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Section: Flame Synthesismentioning

confidence: 97%

Generation and Sizing of Particles for Aerosol-Based Nanotechnology

Biskos

Vons

Yurteri

et al. 2008

KONA

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“…Assuming strong adhesive forces, characteristic for small particles, or chemical bonds, these collisions result in coagulation [7], [8]. Coalescence and fusion are sufficiently fast in the high-temperature zones of the reactor to effect a reduction in the level of aggregation or even the formation of spherical particles due to sintering processes [9], [10]. Figure 3 shows the mechanisms' influence on particle formation, growth, and final morphology.…”

Section: Gas-phase Synthesis Of Nanoparticlesmentioning

confidence: 99%

Gas-Phase Production of Nanoparticles

Gutsch¹,

Kramer²,

Günther³

et al. 2002

KONA

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Gas-phase synthesis is a well-known chemical manufacturing technique for an extensive variety of nano-sized particles. Since the potential of ultra-fine and especially nano-sized particles in high-performance applications has been identified, the scientific and commercial interest has increased immensely, disclosing this field as a most important technology of the future.The paper will present the basics of the gas-phase synthesis and particle formation process including the relation between the principal process conditions and the product characteristics.Moreover, several reactor technologies such as f lame, hot-wall, plasma and laser reactors will be introduced and their specific advantages will be pointed out. Precise process control is crucial in order to meet stringent specifications regarding the particles ' chemical composition and morphology. In addition, the paper will deal with some special nanoscaled gas-phase products of high innovative potential and their functional contribution in various applications.Rodenbacher Chaussee 4, 63457 Hanau, Germany † Accepted: June 28, 2002The smaller the particles, the ...• higher the catalytic activity (Pt@Al 2 O 3 )• higher the mechanical reinforcement (carbon black in rubber)• higher the electrical conductivity of ceramics (CeO 2 )• lower the electrical conductivity of metals (Cu, Ni, Fe, Co, Cu alloys)• initially increasing and later decreasing magnetic coercivity, finally superparamagnetic behaviour (Fe 2 O 3 )• higher the hardness and strength of metals and alloys• higher the ductility, hardness and formability of ceramics; the lower the sintering and superplastic forming temperature of ceramics (TiO 2 )• higher the blue-shift of optical spectra of quantum dots (quantum confinement of Si)• higher the luminescence of semiconductors (Si, GaAs, ZnS:Mn 2ѿ ) silica, for which Degussa is the world market leader, is used in particular as a reinforcing filler in silicone rubber and to control the rheology of coatings and colorants. Industrial carbon black, in which Degussa ranks second in the world, is used particularly in the tyre industry and as a pigment in printing inks, coatings and plastics. In industrial products, primary nanoscale particles are normally not isolated but build up aggregates and agglomerates. In aggregates, the primary particles contact each other at surfaces or edges and Ҁ as a rule Ҁ they cannot be broken down further by shear forces applied in the application. Agglomerates are formed when aggregates and/or primary particles contact each other at points. If nanoparticles are dispersed in a liquid, the agglomerates are destroyed and the surface chemical groups of the aggregates interact with each other (see Fig. 1). In the case of fumed silica, this affinity is attributed to the hydrogen bridge linkages and results in a temporary, three-dimensional lattice structure becoming macroscopically "visible" in the form of thickening and thixotropy. To control the application behaviour often means to generate tailor-made aggregates with a ta...

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“…As in the case of soot, early works on modelling nanoparticle synthesis with CFD relied on a moment approach to predict integral properties such as volume fraction and surface area. Pratsinis et al [188] simulated ideal reactors with moment methods and Johannessen et al [105] modelled the combustion synthesis of alumina particles by coupling a moment method with FLUENT. Muhlenweg et al [158] compared the moment approach with a discretised PBE and a two-dimensional PBE that predicted a distribution in both particle size and surface area, and implemented them into a FLUENT with the objective of comparing the CPU time requirements in a simple plug flow.…”

Section: Soot Formation and Nanoparticle Synthesismentioning

confidence: 99%

Population balance modelling of polydispersed particles in reactive flows

Rigopoulos

2010

Progress in Energy and Combustion Science

133

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Polydispersed particles in reactive flows is a wide subject area encompassing a range of dispersed flows with particles, droplets or bubbles that are created, transported and possibly interact within a reactive flow environment -typical examples include soot formation, aerosols, precipitation and spray combustion. One way to treat such problems is to employ as a starting point the Newtonian equations of motion written in a Lagrangian framework for each individual particle and either solve them directly or derive probabilistic equations for the particle positions (in the case of turbulent flow). Another way is inherently statistical and begins by postulating a distribution of particles over the distributed properties, as well as space and time, the transport equation for this distribution being the core of this approach. This transport equation, usually referred to as population balance equation (PBE) or general dynamic equation (GDE), was initially developed and investigated mainly in the context of spatially homogeneous systems. In the recent years, a growth of research activity has seen this approach being applied to a variety of flow problems such as sooting flames and turbulent precipitation, but significant issues regarding its appropriate coupling with CFD pertain, especially in the case of turbulent flow. The objective of this review is to examine this body of research from a unified perspective, the potential and limits of the PBE approach to flow problems, its links with Lagrangian and multifluid approaches and the numerical methods employed for its solution. Particular emphasis is given to turbulent flows, where the extension of the PBE approach is met with challenging issues. Finally, applications including reactive precipitation, soot formation, nanoparticle synthesis, sprays, bubbles and coal burning are being reviewed from the PBE perspective. It is shown that popualtion balance methods have been applied to these fields in varying degrees of detail, and future prospects are discussed.

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Computational fluid-particle dynamics for the flame synthesis of alumina particles

Cited by 132 publications

References 21 publications

Generation and Sizing of Particles for Aerosol-Based Nanotechnology

Generation and Sizing of Particles for Aerosol-Based Nanotechnology

Gas-Phase Production of Nanoparticles

Population balance modelling of polydispersed particles in reactive flows

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