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spouting behavior of binary particle mixtures of different densities: Fluid dynamics and particle segregation

Particuology 2019年第1期17卷 58-66页

作者： K.G. santos R.C. santana D.L. souza V.V. murata m.a.s. barrozo Federal University ofTriangulo mineiro Chemical Engineering DepartmentUniverdecidade CampusUberabaMGBrazil Federal University of Uberlandia Chemical Engineering SchoolUberlandiaMG. Brazil

Numerous industrial applications of spouted beds involve a mixture of granular particles, where differences in particle size, density, and shape can cause particle segregation, affecting the quality of flow and decreasing product homogeneity. The aim of this study was to investigate the particle segregation and fluid dynamics of a conical spouted bed operating with a binary mixture of particles of different densities. Using glass beads and polyethylene particles with a diameter of 4 mm, we determined the effects of the mass fraction of denser particles and static bed height on the minimum spouting condition and mixture index. The pressure drop and airflow in the minimum spouting condition increased with an increase in bed height or jetsam concentration. Regarding particle segregation, the jetsam particles tended to concentrate near the bottom, at the spout–annulus interface because they have a shorter trajectory than the lighter particles in the fountain region. Jetsam-rich mixtures with high initial static bed heights exhibited more efficient particle mixing, excluding those at the bottom of the bed.

关键词： Density segregation spouted bed Binary mixtures

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Cataracting-centrifuging transition investigation using nonspherical and spherical particles in a rotary drum through CFD simulations

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Particuology 2022年第1期20卷 48-60页

作者： Wanessa m.Benedito Claudio R.Duarte marcos A.s.barrozo Dyrney A.santos Institute of Chemistry Federal University of Goias-UFGCampus SamambaiaGoianiaGO74690-900Brazil school of Chemical Engineering Federal University of Uberlandia-UFUCampus Santa MonicaUberlandiaMG38408-144Brazil

This paper aims to systematically investigate the cataracting-centrifuging transition in a rotary drum involving spherical and nonspherical particles by using the multiphase Granular Eulerian model(mGEm).The effects of drum length and particle shape on the cataracting-centrifuging transition behavior were *** results showed that drum length plays an important role in the cataracting-centrifuging transition,although most related works in the literature do not consider *** particle shape also significantly affects the cataracting-centrifuging transition *** particles required lower rotation speeds than spherical particles to reach the centrifuging *** particle shape was shown to be related to the critical solid fraction(asc)from schaeffer’s model,although further investigations are required to completely correlate particle spherecity with critical solid volume fractions.

关键词： Frictional viscosity mGEm model Particle shape Drum length Drum flow regimes

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Fluid dynamics analysis and pyrolysis of brewer’s spent grain in a spouted bed reactor

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Particuology 2019年第1期17卷 199-207页

作者： marcos A.s. barrozo Lidja D.m.s. Borel Taísa s. Lira Carlos H. Ataíde school of Chemical Engineering Federal University of UberlandiaBrazil Department of Engineering and Technologies Federal University of Espirito SantoBrazil

Brewer’s spent grain (BsG) is a large-scale agroindustrial waste that could be more efficiently utilized. This waste is composed of lignocellulosic material and so may serve as a good source of biomass for thermochemical conversion. The present study investigated the fluid dynamics behavior of mixtures of sand and BsG in a spouted bed to assess the viability of the thermochemical conversion of this biomass via fast pyrolysis. Fluid dynamics analyses were performed while varying the mass fraction of BsG (6–80%) and the static bed height (6.6–13.4 cm). Empirical equations for predicting the minimum spouting conditions and the mixing index were obtained using a regression technique, and the selected fluid dynamics parameters were employed in the spouted bed pyrolysis. The bio-oil resulting from this process was rich in phenolic compounds, various nitrogenated compounds (representing precursors for pharmaceuticals) and long-chain hydrocarbons. The products obtained from the analytical and spouted bed pyrolysis processes were also compared.

关键词： Brewer’s spent grain Agroindustrial residue spouted bed Fast pyrolysis Particle mixing

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Effects of N-acetylcysteine on growth,viability and reactive oxygen species levels in small antral follicles cultured in vitro

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Asian pacific Journal of Reproduction 2023年第1期12卷 42-48页

作者： Efigênia B.Cordeiro Bianca R.silva Laís R.F.m.Paulino Pedro A.A.Barroso Laryssa G.barrozo miguel F.de Lima Neto JoséR.V.silva Laboratory of Biotechnology and Physiology of Reproduction Federal University of CearaAv.Comandante Maurocélio Rocha Ponte 10062041-040SobralCEBrazil

Objective:To investigate the effects of different concentrations of N-acetylcysteine on follicular growth and morphology,as well as on viability,levels of reactive oxygen species(ROs)and meiotic progression of oocytes from in vitro cultured bovine early antral ***:Isolated early antral follicles(about 500μm)were cultured in TCm-199+alone or supplemented with 1.0,5.0 or 25.0 mm N-acetylcysteine at 38.5℃with 5%CO_(2) for 8 *** diameters were evaluated at day 0,4 and 8 of *** the end of culture,the levels of ROs,chromatin configuration and viability(calcein-Am and ethidium homodimer-1 staining)were investigated in the cumulus-oocyte *** of follicle diameters between treatments were *** on percentages of morphologically normal follicles,growth rates and chromatin configuration in different treatments were ***:An increase in follicular diameters after culture in all treatments was observed,except for follicles cultured with 25.0 mm *** microscopy showed that oocytes cultured in all treatments were stained positively with calcein Am,and that 5.0 mm N-acetylcysteine reduced fluorescence for ethidium *** levels of ROs in oocytes from follicles cultured with 1.0 mm N-acetylcysteine showed a significant reduction compared to other *** presence of N-acetylcysteine in culture medium did not influence the rates of oocyte at the germinal vesicle ***:N-acetylcysteine at concentrations of 1.0 and 5.0 mm reduces ROs levels and staining for ethidium homodimer-1 in in vitro cultured follicles,respectively,while 25.0 mm N-acetylcysteine decreases follicular growth and the percentages of continuously growing follicles.

关键词： Antioxidant N-acetylcysteine Antral follicles Bovine Reactive oxygen species

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