Documents disponibles écrits par cet auteur

Effect of operating pressure on the extent of hysteresis in a trickle bed reactor / Zeljko Kuzeljevic in Industrial & engineering chemistry research, Vol. 47 N°20 (Octobre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N°20 (Octobre 2008) . - P. 7593-7599 Titre : Effect of operating pressure on the extent of hysteresis in a trickle bed reactor Type de document : texte imprimé Auteurs : Zeljko Kuzeljevic, Editeur scientifique ; Werner van der Merwe, Editeur scientifique ; Muthanna H. Al-Dahhan, Editeur scientifique Année de publication : 2008 Article en page(s) : P. 7593-7599 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Operating  pressure  Hydrodynamic  parameters Résumé : The dependence of hydrodynamic parameters, such as pressure drop, on the flow history of the bed is called hysteresis. This phenomenon is most commonly associated with changes of flow distribution and flow patterns with the flow history. Many studies have shown that increased operating pressure will affect flow distribution and wetting efficiency; however, there seems to be no study of the effect of the elevated operating pressure on the extent of hysteresis. In this study, an experimental investigation of the hysteresis in a high-pressure trickle bed has been performed. A hysteresis factor has been introduced to quantify the extent of hysteresis and was found to be a strong function of gas and liquid operating flow rates as well as the operating pressure. In the region of lower liquid velocities, hysteresis is present regardless of the operating pressure or gas velocity. In the region of higher liquid velocities, increases in both pressure and gas velocity will lower the extent of hysteresis. For the range of conditions considered in this study, the extent of hysteresis was uniquely determined by the pressure drop in the Levec mode, regardless of the operating pressure or velocities. The results are interpreted in terms of the phenomenological analysis of Al-Dahhan and Dudukovic (Al-Dahhan, M. H.; Dudukovic, M. P. Chem. Eng. Sci. 1994, 49, 5681−98), which relates operating pressure and gas velocity to the flow distribution and wetting efficiency in a trickle bed reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800255p [article] Effect of operating pressure on the extent of hysteresis in a trickle bed reactor [texte imprimé] / Zeljko Kuzeljevic, Editeur scientifique ; Werner van der Merwe, Editeur scientifique ; Muthanna H. Al-Dahhan, Editeur scientifique . - 2008 . - P. 7593-7599. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°20 (Octobre 2008) . - P. 7593-7599 Mots-clés : Operating  pressure  Hydrodynamic  parameters Résumé : The dependence of hydrodynamic parameters, such as pressure drop, on the flow history of the bed is called hysteresis. This phenomenon is most commonly associated with changes of flow distribution and flow patterns with the flow history. Many studies have shown that increased operating pressure will affect flow distribution and wetting efficiency; however, there seems to be no study of the effect of the elevated operating pressure on the extent of hysteresis. In this study, an experimental investigation of the hysteresis in a high-pressure trickle bed has been performed. A hysteresis factor has been introduced to quantify the extent of hysteresis and was found to be a strong function of gas and liquid operating flow rates as well as the operating pressure. In the region of lower liquid velocities, hysteresis is present regardless of the operating pressure or gas velocity. In the region of higher liquid velocities, increases in both pressure and gas velocity will lower the extent of hysteresis. For the range of conditions considered in this study, the extent of hysteresis was uniquely determined by the pressure drop in the Levec mode, regardless of the operating pressure or velocities. The results are interpreted in terms of the phenomenological analysis of Al-Dahhan and Dudukovic (Al-Dahhan, M. H.; Dudukovic, M. P. Chem. Eng. Sci. 1994, 49, 5681−98), which relates operating pressure and gas velocity to the flow distribution and wetting efficiency in a trickle bed reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800255p

From laboratory to field tomography / Zeljko Kuzeljevic in Industrial & engineering chemistry research, Vol. 50 N° 17 (Septembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 17 (Septembre 2011) . - pp. 9890-9900 Titre : From laboratory to field tomography : data collection and performance assessment Type de document : texte imprimé Auteurs : Zeljko Kuzeljevic, Auteur ; Milorad Dudukovic, Auteur ; Hugh Stitt, Auteur Année de publication : 2011 Article en page(s) : pp. 9890-9900 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Tomography Résumé : In field tomography, the total number of scan lines collected during imaging is usually limited. At the same time, the demands on the technique regarding resolution are low, corresponding to diagnostic purposes (e.g., presence or absence of maldistribution). In this study, we investigate the level of information needed for purpose of field diagnostics when using a fan beam tomography scanner. We utilize the theoretical framework of Fisher information content to examine dependence between projection data collection methodology and image quality. The findings are substantiated by experimental results obtained on suitable phantom designed to mimic maldistribution in packed bed. The performance of expectation-maximization and alternating-minimization image reconstruction algorithms for varying number of scan lines used is compared. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24483632 [article] From laboratory to field tomography : data collection and performance assessment [texte imprimé] / Zeljko Kuzeljevic, Auteur ; Milorad Dudukovic, Auteur ; Hugh Stitt, Auteur . - 2011 . - pp. 9890-9900. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 17 (Septembre 2011) . - pp. 9890-9900 Mots-clés : Tomography Résumé : In field tomography, the total number of scan lines collected during imaging is usually limited. At the same time, the demands on the technique regarding resolution are low, corresponding to diagnostic purposes (e.g., presence or absence of maldistribution). In this study, we investigate the level of information needed for purpose of field diagnostics when using a fan beam tomography scanner. We utilize the theoretical framework of Fisher information content to examine dependence between projection data collection methodology and image quality. The findings are substantiated by experimental results obtained on suitable phantom designed to mimic maldistribution in packed bed. The performance of expectation-maximization and alternating-minimization image reconstruction algorithms for varying number of scan lines used is compared. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24483632