Documents disponibles écrits par cet auteur

Assessment of CFD−VOF method for trickle-bed reactor modeling in the catalytic wet oxidation of phenolic wastewaters / Rodrigo J. G. Lopes in Industrial & engineering chemistry research, Vol. 49 N° 6 (Mars 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 6 (Mars 2010) . - pp. 2638–2648 Titre : Assessment of CFD−VOF method for trickle-bed reactor modeling in the catalytic wet oxidation of phenolic wastewaters Type de document : texte imprimé Auteurs : Rodrigo J. G. Lopes, Auteur ; Rosa M. Quinta-Ferreira, Auteur Année de publication : 2010 Article en page(s) : pp. 2638–2648 Note générale : Industrial Chemistry Langues : Anglais (eng) Mots-clés : Assessment  CFD−VOF  Trickle  Bed  Reactor  Modeling  Catalytic  Wet  Oxidation  Phenolic  Wastewaters Résumé : A multiphase volume of fluid (VOF) model was developed to provide a more detailed understanding of the transient behavior of a laboratory-scale trickle-bed reactor. The gas−liquid flow through a catalytic bed of spherical particles was used to compute velocity field and liquid volume fraction distributions considering interfacial phenomena as well as surface tension effects. The computational model was used to simulate the catalytic wet air oxidation of a phenolic model solution in the multiphase reactor. Several runs were carried out under unsteady-state operation to evaluate the dynamic performance addressing the total organic carbon concentration and temperature profiles. In all runs, some level of backmixing was predicted, being lower at high operating temperatures. These axial concentration profiles were then correlated with the radial ones revealing a poor radial mixing for the simulated flow regime, namely, at the hot spots. The influence of the operating temperature on the thermal profiles illustrated the existence of such hot spots located in the first quarter of the axial coordinate with an intensity about 6% higher than the inlet and wall temperatures. The transient radial temperature profiles corresponding to the hot spot showed the same intensity as was found for the axial thermal profiles, indicating the existence of considerable radial gradients that sustained the poor radial mixing in downflow operating mode. Despite the qualitative differences attained for the shapes of the thermal profiles, one should bear in mind that the maximum difference between the computed results and experimental data was lower than 1.5%, which reinforces the validation of the computational fluid dynamics (CFD) approach at reacting flow conditions. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901412x [article] Assessment of CFD−VOF method for trickle-bed reactor modeling in the catalytic wet oxidation of phenolic wastewaters [texte imprimé] / Rodrigo J. G. Lopes, Auteur ; Rosa M. Quinta-Ferreira, Auteur . - 2010 . - pp. 2638–2648. Industrial Chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 6 (Mars 2010) . - pp. 2638–2648 Mots-clés : Assessment  CFD−VOF  Trickle  Bed  Reactor  Modeling  Catalytic  Wet  Oxidation  Phenolic  Wastewaters Résumé : A multiphase volume of fluid (VOF) model was developed to provide a more detailed understanding of the transient behavior of a laboratory-scale trickle-bed reactor. The gas−liquid flow through a catalytic bed of spherical particles was used to compute velocity field and liquid volume fraction distributions considering interfacial phenomena as well as surface tension effects. The computational model was used to simulate the catalytic wet air oxidation of a phenolic model solution in the multiphase reactor. Several runs were carried out under unsteady-state operation to evaluate the dynamic performance addressing the total organic carbon concentration and temperature profiles. In all runs, some level of backmixing was predicted, being lower at high operating temperatures. These axial concentration profiles were then correlated with the radial ones revealing a poor radial mixing for the simulated flow regime, namely, at the hot spots. The influence of the operating temperature on the thermal profiles illustrated the existence of such hot spots located in the first quarter of the axial coordinate with an intensity about 6% higher than the inlet and wall temperatures. The transient radial temperature profiles corresponding to the hot spot showed the same intensity as was found for the axial thermal profiles, indicating the existence of considerable radial gradients that sustained the poor radial mixing in downflow operating mode. Despite the qualitative differences attained for the shapes of the thermal profiles, one should bear in mind that the maximum difference between the computed results and experimental data was lower than 1.5%, which reinforces the validation of the computational fluid dynamics (CFD) approach at reacting flow conditions. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901412x

Euler – lagrange CFD simulation of a gas – liquid fluidized bed reactor for the mineralization of high - strength phenolic wastewaters / Rodrigo J. G. Lopes in Industrial & engineering chemistry research, Vol. 51 N° 26 (Juillet 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 8891-8902 Titre : Euler – lagrange CFD simulation of a gas – liquid fluidized bed reactor for the mineralization of high - strength phenolic wastewaters Type de document : texte imprimé Auteurs : Rodrigo J. G. Lopes, Auteur ; M.L.N. Perdigoto, Auteur ; Rosa M. Quinta-Ferreira, Auteur Année de publication : 2012 Article en page(s) : pp. 8891-8902 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Waste  water  Strength  Mineralization  Fluidized  bed  reactor  Computational  fluid  dynamics Résumé : A state-of-the-art Euler―Lagrange model was developed to simulate the ozonation of phenol-like pollutants in a bubble column reactor. First, several numerical simulations were performed to evaluate on how the bubble velocity and oxidant concentration can improve the detoxification of liquid effluents by noncatalytic ozonation. Second, the effect of inlet ozone velocity as well as the influence of inlet ozone concentration has been investigated comparatively under different process conditions. We found that the Eulerian―Lagrangian computations have correctly handled the experimental observations in the quasi-homogeneous flow regime both in terms of the gas―liquid velocity distributions and normalized pollutant concentration. The numerical confidence exhibited by the CFD simulations underlined the ozonation-based technology as one promising application to improve the environmental performance of bubble columns, which is typically operated under the low-interaction regimes, especially when the mass transfer of ozone is rate controlling and affects the mineralization rate. The interstitial flow maps have been successfully correlated with total organic carbon concentration profles as function of inlet ozone velocities and concentrations. Moreover, the multiphase CFD framework gathered positively the mixing degree induced by different inlet bubble velocities as demonstrated by the total organic carbon concentration mappings and experimental conversion data. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26107444 [article] Euler – lagrange CFD simulation of a gas – liquid fluidized bed reactor for the mineralization of high - strength phenolic wastewaters [texte imprimé] / Rodrigo J. G. Lopes, Auteur ; M.L.N. Perdigoto, Auteur ; Rosa M. Quinta-Ferreira, Auteur . - 2012 . - pp. 8891-8902. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 8891-8902 Mots-clés : Waste  water  Strength  Mineralization  Fluidized  bed  reactor  Computational  fluid  dynamics Résumé : A state-of-the-art Euler―Lagrange model was developed to simulate the ozonation of phenol-like pollutants in a bubble column reactor. First, several numerical simulations were performed to evaluate on how the bubble velocity and oxidant concentration can improve the detoxification of liquid effluents by noncatalytic ozonation. Second, the effect of inlet ozone velocity as well as the influence of inlet ozone concentration has been investigated comparatively under different process conditions. We found that the Eulerian―Lagrangian computations have correctly handled the experimental observations in the quasi-homogeneous flow regime both in terms of the gas―liquid velocity distributions and normalized pollutant concentration. The numerical confidence exhibited by the CFD simulations underlined the ozonation-based technology as one promising application to improve the environmental performance of bubble columns, which is typically operated under the low-interaction regimes, especially when the mass transfer of ozone is rate controlling and affects the mineralization rate. The interstitial flow maps have been successfully correlated with total organic carbon concentration profles as function of inlet ozone velocities and concentrations. Moreover, the multiphase CFD framework gathered positively the mixing degree induced by different inlet bubble velocities as demonstrated by the total organic carbon concentration mappings and experimental conversion data. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26107444

Hydrodynamic simulation of pulsing-flow regime in high-pressure trickle-bed reactors / Rodrigo J. G. Lopes in Industrial & engineering chemistry research, Vol. 49 N° 3 (Fevrier 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 3 (Fevrier 2010) . - pp. 1105–1112 Titre : Hydrodynamic simulation of pulsing-flow regime in high-pressure trickle-bed reactors Type de document : texte imprimé Auteurs : Rodrigo J. G. Lopes, Auteur ; Rosa M. Quinta-Ferreira, Auteur Année de publication : 2010 Article en page(s) : pp. 1105–1112 Note générale : Industrial Chemistry Langues : Anglais (eng) Mots-clés : Hydrodynamic--Simulation--Pulsing--Flow--Reactors--Trickle Résumé : In the present study, attention is focused on the CFD simulation of trickle-bed reactors when the trickling-flow regime changes into the pulsing-flow regime, along with the parameters that characterize this latter regime. These parameters include the velocity at which the pulse front travels along the bed, the frequency of pulsations, and the structure of pulses being formed (i.e., the sizes of the liquid-rich and gas-rich zones). Results are presented for a three-phase reactor operating at an elevated pressure in the pulsing-flow regime. Several parameters that characterize the pulsing flow, namely, the velocity of pulses traveling along the bed, the frequency of pulsations and their structure, the length of the pulses, and the length of the liquid-rich zone, were examined at high pressure by means of an Eulerian CFD model. Note de contenu : Bibiogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900767q [article] Hydrodynamic simulation of pulsing-flow regime in high-pressure trickle-bed reactors [texte imprimé] / Rodrigo J. G. Lopes, Auteur ; Rosa M. Quinta-Ferreira, Auteur . - 2010 . - pp. 1105–1112. Industrial Chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 3 (Fevrier 2010) . - pp. 1105–1112 Mots-clés : Hydrodynamic--Simulation--Pulsing--Flow--Reactors--Trickle Résumé : In the present study, attention is focused on the CFD simulation of trickle-bed reactors when the trickling-flow regime changes into the pulsing-flow regime, along with the parameters that characterize this latter regime. These parameters include the velocity at which the pulse front travels along the bed, the frequency of pulsations, and the structure of pulses being formed (i.e., the sizes of the liquid-rich and gas-rich zones). Results are presented for a three-phase reactor operating at an elevated pressure in the pulsing-flow regime. Several parameters that characterize the pulsing flow, namely, the velocity of pulses traveling along the bed, the frequency of pulsations and their structure, the length of the pulses, and the length of the liquid-rich zone, were examined at high pressure by means of an Eulerian CFD model. Note de contenu : Bibiogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900767q

Numerical simulation of trickle-bed reactor hydrodynamics with RANS-based models using a volume of fluid technique / Rodrigo J. G. Lopes in Industrial & engineering chemistry research, Vol. 48 N°4 (Février 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - pp. 1740–1748 Titre : Numerical simulation of trickle-bed reactor hydrodynamics with RANS-based models using a volume of fluid technique Type de document : texte imprimé Auteurs : Rodrigo J. G. Lopes, Auteur ; Rosa M. Quinta-Ferreira, Auteur Année de publication : 2009 Article en page(s) : pp. 1740–1748 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Trickle-bed  reactor  Volume  of  fluid  model  Fluid  dynamics  Hydrodynamic  behavior Résumé : A trickle-bed reactor (TBR) was modeled by means of the volume of fluid (VOF) model to provide a hydrodynamic behavior analysis in trickling flow conditions. Fluid dynamics of the TBR is characterized by poor liquid distribution and inefficient catalyst utilization and conventional modeling techniques are unable to address these key design issues. Therefore, the VOF code was used to investigate the major hydrodynamic parameters in a three-dimensional packed bed providing a more rigorous physical description of the underlying flow process. Several numerical solution parameters including different mesh densities, time steps, and convergence criteria were optimized in order to provide computational independent results. During the parametric optimization it was found that the VOF model is more sensible to mesh density and time step than with respect to convergence criteria. The computational fluid dynamic model was thoroughly validated by comparing the model predictions with the published experimental data for liquid holdup and two-phase pressure drop. After the VOF optimization, selected values for the numerical solutions parameters were used to perform the assessment of different turbulent flow models at two nominal gas flow rates. Afterward, several computational runs were performed in the evaluation of the influence of either gas or liquid flow rate on TBR hydrodynamics. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8014186 [article] Numerical simulation of trickle-bed reactor hydrodynamics with RANS-based models using a volume of fluid technique [texte imprimé] / Rodrigo J. G. Lopes, Auteur ; Rosa M. Quinta-Ferreira, Auteur . - 2009 . - pp. 1740–1748. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - pp. 1740–1748 Mots-clés : Trickle-bed  reactor  Volume  of  fluid  model  Fluid  dynamics  Hydrodynamic  behavior Résumé : A trickle-bed reactor (TBR) was modeled by means of the volume of fluid (VOF) model to provide a hydrodynamic behavior analysis in trickling flow conditions. Fluid dynamics of the TBR is characterized by poor liquid distribution and inefficient catalyst utilization and conventional modeling techniques are unable to address these key design issues. Therefore, the VOF code was used to investigate the major hydrodynamic parameters in a three-dimensional packed bed providing a more rigorous physical description of the underlying flow process. Several numerical solution parameters including different mesh densities, time steps, and convergence criteria were optimized in order to provide computational independent results. During the parametric optimization it was found that the VOF model is more sensible to mesh density and time step than with respect to convergence criteria. The computational fluid dynamic model was thoroughly validated by comparing the model predictions with the published experimental data for liquid holdup and two-phase pressure drop. After the VOF optimization, selected values for the numerical solutions parameters were used to perform the assessment of different turbulent flow models at two nominal gas flow rates. Afterward, several computational runs were performed in the evaluation of the influence of either gas or liquid flow rate on TBR hydrodynamics. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8014186

Numerical studies of catalyst wetting and total organic carbon reaction on environmentally based trickle - bed reactors / Rodrigo J. G. Lopes in Industrial & engineering chemistry research, Vol. 49 N° 21 (Novembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10730-10743 Titre : Numerical studies of catalyst wetting and total organic carbon reaction on environmentally based trickle - bed reactors Type de document : texte imprimé Auteurs : Rodrigo J. G. Lopes, Auteur ; Rosa M. Quinta-Ferreira, Auteur Année de publication : 2011 Article en page(s) : pp. 10730-10743 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Trickle  bed  reactor  Total  organic  carbon  Wetting  Catalyst Résumé : This work is devoted to the computational fluid dynamics (CFD) simulation of trickle-bed reactors (TBRs) with environmentally based applications on advanced wastewater remediation technologies. Recently, TBRs have assumed a major role in industrial wastewater treatment plants being envisaged as a breakthrough paraphernalia to move forward superseded decontamination processes. According to the literature, the generous research in environmental reaction engineering has indicated that scale-up of TBRs is erroneous if one considers isothermal operation and uses either a pseudohomogeneous or a heterogeneous model with plug flow for gas and liquid phases. Even though an axial dispersion model may account for liquid distribution nonuniformity, the reaction parameters are strongly dependent on the reactor fluid dynamics. In our case-study, first we developed a volume-of-fluid CFD framework which accounts for the surface tension and wall adhesion effects. A three-dimensional computational domain was employed to investigate and validate the multiphase flow model at diverse operating conditions. The catalytic wet oxidation of high-strength phenolic wastewaters was taken as our case study to evaluate axial profiles of temperature and total organic carbon depletion rates. Second, the theoretical calculations were compared against experimental data taken from a TBR pilot plant. The CFD simulations have shown promising results on how fluid dynamics can be correlated with chemical reaction, namely on the prediction of total organic carbon conversions functionalized by nominal liquid flow rates and attained at different temperatures. Finally, the effect of temperature on the spatial distribution studies of liquid phase gave rise to the requirement of higher liquid throughput to achieve sufficient liquid holdup for the same total organic carbon conversions at elevated temperatures. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23447966 [article] Numerical studies of catalyst wetting and total organic carbon reaction on environmentally based trickle - bed reactors [texte imprimé] / Rodrigo J. G. Lopes, Auteur ; Rosa M. Quinta-Ferreira, Auteur . - 2011 . - pp. 10730-10743. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10730-10743 Mots-clés : Trickle  bed  reactor  Total  organic  carbon  Wetting  Catalyst Résumé : This work is devoted to the computational fluid dynamics (CFD) simulation of trickle-bed reactors (TBRs) with environmentally based applications on advanced wastewater remediation technologies. Recently, TBRs have assumed a major role in industrial wastewater treatment plants being envisaged as a breakthrough paraphernalia to move forward superseded decontamination processes. According to the literature, the generous research in environmental reaction engineering has indicated that scale-up of TBRs is erroneous if one considers isothermal operation and uses either a pseudohomogeneous or a heterogeneous model with plug flow for gas and liquid phases. Even though an axial dispersion model may account for liquid distribution nonuniformity, the reaction parameters are strongly dependent on the reactor fluid dynamics. In our case-study, first we developed a volume-of-fluid CFD framework which accounts for the surface tension and wall adhesion effects. A three-dimensional computational domain was employed to investigate and validate the multiphase flow model at diverse operating conditions. The catalytic wet oxidation of high-strength phenolic wastewaters was taken as our case study to evaluate axial profiles of temperature and total organic carbon depletion rates. Second, the theoretical calculations were compared against experimental data taken from a TBR pilot plant. The CFD simulations have shown promising results on how fluid dynamics can be correlated with chemical reaction, namely on the prediction of total organic carbon conversions functionalized by nominal liquid flow rates and attained at different temperatures. Finally, the effect of temperature on the spatial distribution studies of liquid phase gave rise to the requirement of higher liquid throughput to achieve sufficient liquid holdup for the same total organic carbon conversions at elevated temperatures. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23447966