1,722,047 research outputs found
Editorials for visual special issue on pyrolysis for green energy and sustainable products
No full textKinetics and thermodynamics of microalgae residue oxidative pyrolysis based on double distributed activation energy model with simulated annealing method
No full textNon-isothermal thermogravimetric analysis (TGA) at four heating rates of 10, 20, 30 and 40 K min−1 under oxidative atmosphere was employed to investigate the characteristics of microalgae residue oxidative pyrolysis. The double distributed activation energy model (DAEM) was used to analyze the oxidative pyrolysis kinetics of microalgae residue and the simulated annealing method was employed for the estimation of the model parameters. The results showed that the double DAEM could describe the kinetic experimental data of microalgae residue oxidative pyrolysis very well whilst the simulated annealing method was effective for determining the kinetic parameters of the double DAEM. The kinetic process of microalgae residue oxidative pyrolysis could be considered as two partially overlapped pseudo-sub-processes. The mean values of activation energy distributions were 179 and 259 kJ mol−1 for the first and second pseudo-sub-processes. The thermodynamic parameters of microalgae residue oxidative pyrolysis processes at the different heating rate were studied based on the obtained kinetic parameters.</p
Parametric analysis of biomass fast pyrolysis in a downer fluidized bed reactor
Full text linkThis study presents a theoretical parametric analysis of biomass fast pyrolysis in a downer reactor, as part of a dual fluidized bed system. The model framework uses a Eulerian-Eulerian CFD approach and incorporates a user-defined function (UDF) for the thermochemical conversion of biomass. The downer reactor consists of a novel gas-solid separator, which is employed to control the gas residence time within the reactor. The parameters investigated included the reactor temperature, the particle (heat carrier and biomass) size and the gas residence time. The product yield was found to be strongly dependent on the reactor temperature (varied through changing the heat carrier flow rate), intermediately dependent on the sweeping gas (N2) flow rate and the sand particle size, and much less dependent on the biomass particle size (within the range of 1 mm diameter). The developed model and the results demonstrate the advantage and robustness of employing the model for parameters optimization and sensitivity investigation when dealing with complex multiphase flow reactive system. This conclusion will benefit future development and scale-up studies of downer reactors for biomass fast pyrolysis
Influence of Reaction Atmosphere (H2O, N2, H2, CO2, CO) on Fluidized-Bed Fast Pyrolysis of Biomass Using Detailed Tar Vapor Chemistry in Computational Fluid Dynamics
Full text linkSecondary pyrolysis in fluidized bed fast pyrolysis of biomass is the focus of this work. A novel computational fluid dynamics (CFD) model coupled with a comprehensive chemistry scheme (134 species and 4169 reactions, in CHEMKIN format) has been developed to investigate this complex phenomenon. Previous results from a transient three-dimensional model of primary pyrolysis were used for the source terms of primary products in this model. A parametric study of reaction atmospheres (H2O, N2, H2, CO2, CO) has been performed. For the N2 and H2O atmosphere, results of the model compared favorably to experimentally obtained yields after the temperature was adjusted to a value higher than that used in experiments. One notable deviation versus experiments is pyrolytic water yield and yield of higher hydrocarbons. The model suggests a not overly strong impact of the reaction atmosphere. However, both chemical and physical effects were observed. Most notably, effects could be seen on the yield of various compounds, temperature profile throughout the reactor system, residence time, radical concentration, and turbulent intensity. At the investigated temperature (873 K), turbulent intensity appeared to have the strongest influence on liquid yield. With the aid of acceleration techniques, most importantly dimension reduction, chemistry agglomeration, and in-situ tabulation, a converged solution could be obtained within a reasonable time (∼30 h). As such, a new potentially useful method has been suggested for numerical analysis of fast pyrolysis.QC 20150918</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Yu Xi 虞喜 (fl. 307-346) (Zhongning 仲寧) - Astronome et ermite lettré des Jin de l’Est
No full textInternational audienceDaniel P. Morgan, « Yu Xi 虞喜 (fl. 307-346) (Zhongning 仲寧) - Astronome et ermite lettré des Jin de l’Est », dans Dictionnaire biographique du haut Moyen Âge chinois, François Martin et Damien Chaussende (éd.), Paris, Les Belles Lettres, 2020, p. 601-602
Yu Xi 虞喜 (fl. 307-346) (Zhongning 仲寧) - Astronome et ermite lettré des Jin de l’Est
No full textInternational audienceDaniel P. Morgan, « Yu Xi 虞喜 (fl. 307-346) (Zhongning 仲寧) - Astronome et ermite lettré des Jin de l’Est », dans Dictionnaire biographique du haut Moyen Âge chinois, François Martin et Damien Chaussende (éd.), Paris, Les Belles Lettres, 2020, p. 601-602
Yu Xi 虞喜 (fl. 307-346) (Zhongning 仲寧) - Astronome et ermite lettré des Jin de l’Est
No full textInternational audienceDaniel P. Morgan, « Yu Xi 虞喜 (fl. 307-346) (Zhongning 仲寧) - Astronome et ermite lettré des Jin de l’Est », dans Dictionnaire biographique du haut Moyen Âge chinois, François Martin et Damien Chaussende (éd.), Paris, Les Belles Lettres, 2020, p. 601-602
Yu Xi 虞喜 (fl. 307-346) (Zhongning 仲寧) - Astronome et ermite lettré des Jin de l’Est
No full textInternational audienceDaniel P. Morgan, « Yu Xi 虞喜 (fl. 307-346) (Zhongning 仲寧) - Astronome et ermite lettré des Jin de l’Est », dans Dictionnaire biographique du haut Moyen Âge chinois, François Martin et Damien Chaussende (éd.), Paris, Les Belles Lettres, 2020, p. 601-602
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