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Evaluating the probabilities of fluidization regimes / Milad Aghabararnejad in Industrial & engineering chemistry research, Vol. 50 N° 8 (Avril 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 8 (Avril 2011) . - pp. 4245–4251 Titre : Evaluating the probabilities of fluidization regimes Type de document : texte imprimé Auteurs : Milad Aghabararnejad, Auteur ; Navid Mostoufi, Auteur ; Rahmat Sotudeh-Gharebagh, Auteur Année de publication : 2011 Article en page(s) : pp. 4245–4251 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Probabilities  fluidization  regimes Résumé : Probabilities of fluidization regimes were determined experimentally using frequency domain analysis of pressure fluctuation data. It was assumed that regime transition does not occur at a distinct gas velocity and fluidization regimes coexist at each gas velocity. Three different flow structures (macro-, meso-, and microstructures) were recognized in a fluidized bed. Macrostructure is represented by bubbles, mesostructures are represented by clusters, and microstructure is represented by particles. These structures are the characteristics of bubbling, turbulent, and fast fluidization regimes. Regime probabilities were determined using power spectrum energies of these structures. Experiments were carried out in a 1 m high and 5 cm inner diameter glass column. Pressure fluctuations were measured using a piezoresistive pressure sensor. Sand particles with various diameters (150, 280, and 490 μm) and fluid catalytic cracking (FCC) particles (73 μm) were used as solids. Probabilities of fluidization regimes were calculated at various gas velocities. A new procedure was proposed for evaluating the regime probabilities versus gas velocity. It was shown that the proposed correlation is in good agreement with the experimental data and is noticeably better than the method proposed in the literature. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100642b [article] Evaluating the probabilities of fluidization regimes [texte imprimé] / Milad Aghabararnejad, Auteur ; Navid Mostoufi, Auteur ; Rahmat Sotudeh-Gharebagh, Auteur . - 2011 . - pp. 4245–4251. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 8 (Avril 2011) . - pp. 4245–4251 Mots-clés : Probabilities  fluidization  regimes Résumé : Probabilities of fluidization regimes were determined experimentally using frequency domain analysis of pressure fluctuation data. It was assumed that regime transition does not occur at a distinct gas velocity and fluidization regimes coexist at each gas velocity. Three different flow structures (macro-, meso-, and microstructures) were recognized in a fluidized bed. Macrostructure is represented by bubbles, mesostructures are represented by clusters, and microstructure is represented by particles. These structures are the characteristics of bubbling, turbulent, and fast fluidization regimes. Regime probabilities were determined using power spectrum energies of these structures. Experiments were carried out in a 1 m high and 5 cm inner diameter glass column. Pressure fluctuations were measured using a piezoresistive pressure sensor. Sand particles with various diameters (150, 280, and 490 μm) and fluid catalytic cracking (FCC) particles (73 μm) were used as solids. Probabilities of fluidization regimes were calculated at various gas velocities. A new procedure was proposed for evaluating the regime probabilities versus gas velocity. It was shown that the proposed correlation is in good agreement with the experimental data and is noticeably better than the method proposed in the literature. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100642b

Nonlinear characterization of pressure fluctuations in fluidized beds / Reza Zarghami in Industrial & engineering chemistry research, Vol. 47 N° 23 (Décembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N° 23 (Décembre 2008) . - p. 9497–9507 Titre : Nonlinear characterization of pressure fluctuations in fluidized beds Type de document : texte imprimé Auteurs : Reza Zarghami, Auteur ; Navid Mostoufi, Auteur ; Rahmat Sotudeh-Gharebagh, Auteur Année de publication : 2009 Article en page(s) : p. 9497–9507 Note générale : Chemistry engineering Langues : Anglais (eng) Mots-clés : Pressure  fluctuations  Fluidized  beds Résumé : Nonlinear time series analysis techniques were applied to predict pressure fluctuation data in fluidized beds in two different hydrodynamic states. The method of delays was used to reconstruct the state space attractor to carry out analysis in the reconstructed state space. The state space reconstruction parameters, i.e., time delay and embedding dimension, were determined and the results shown that their values were different for various types of methods introduced in the literature. Chaotic behavior and predictability of fluidized system were determined by introducing two nonlinear dynamic invariants, correlation dimension and entropy, in different ways. The traditional linear autoregression method and state space based prediction methods (SSBPMs), i.e., nearest neighbors and locally linear, and global linear methods, were applied to predict the pressure fluctuation signals. The quality of prediction was assessed by comparison of the predicted data with its original benchmark. In addition, the dynamic invariants of measured and predicted attractor of the pressure signals were compared. The results showed that SSBPMs are preferred to the traditional linear methods. Finally, a continuous uncertainty band of pressure signals of single and multiple bubble regimes for the prediction methods was presented. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800460f [article] Nonlinear characterization of pressure fluctuations in fluidized beds [texte imprimé] / Reza Zarghami, Auteur ; Navid Mostoufi, Auteur ; Rahmat Sotudeh-Gharebagh, Auteur . - 2009 . - p. 9497–9507. Chemistry engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N° 23 (Décembre 2008) . - p. 9497–9507 Mots-clés : Pressure  fluctuations  Fluidized  beds Résumé : Nonlinear time series analysis techniques were applied to predict pressure fluctuation data in fluidized beds in two different hydrodynamic states. The method of delays was used to reconstruct the state space attractor to carry out analysis in the reconstructed state space. The state space reconstruction parameters, i.e., time delay and embedding dimension, were determined and the results shown that their values were different for various types of methods introduced in the literature. Chaotic behavior and predictability of fluidized system were determined by introducing two nonlinear dynamic invariants, correlation dimension and entropy, in different ways. The traditional linear autoregression method and state space based prediction methods (SSBPMs), i.e., nearest neighbors and locally linear, and global linear methods, were applied to predict the pressure fluctuation signals. The quality of prediction was assessed by comparison of the predicted data with its original benchmark. In addition, the dynamic invariants of measured and predicted attractor of the pressure signals were compared. The results showed that SSBPMs are preferred to the traditional linear methods. Finally, a continuous uncertainty band of pressure signals of single and multiple bubble regimes for the prediction methods was presented. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800460f