Documents disponibles écrits par cet auteur

Formation of thermal wave trains in loop reactors / Pietro Altimari in Industrial & engineering chemistry research, Vol. 51 N° 28 (Juillet 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 28 (Juillet 2012) . - pp. 9609-9619 Titre : Formation of thermal wave trains in loop reactors : Stability limits and spatiotemporal structure for reversible reactions Type de document : texte imprimé Auteurs : Pietro Altimari, Auteur ; Erasmo Mancusi, Auteur ; Silvestro Crescitelli, Auteur Année de publication : 2012 Article en page(s) : pp. 9609-9619 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Reversible  reaction  Stability  Reactor  Thermal  wave Résumé : Networks of fixed bed reactors with periodically switched inlet and outlet sections are studied with reference to equilibrium limited reactions. The methanol synthesis is selected as representative reaction example and the mechanisms governing the emergence of periodic regimes corresponding to trains of traveling thermal waves are analyzed. Analytical approximations, accounting for the influence of the implemented switching strategy and in satisfactory agreement with numerical simulation, are derived for the switch time stability limits in terms of temperature fronts velocities. Large and sudden variations in the switch time stability range of any wave train solution are demonstrated to occur when the sum of the velocities of declining temperature fronts exceeds the sum of the velocities of rising temperature fronts. The illustrated results provide indications on how to design and operate the network so as to generate thermal wave trains with desired number of waves and stability limits. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26163298 [article] Formation of thermal wave trains in loop reactors : Stability limits and spatiotemporal structure for reversible reactions [texte imprimé] / Pietro Altimari, Auteur ; Erasmo Mancusi, Auteur ; Silvestro Crescitelli, Auteur . - 2012 . - pp. 9609-9619. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 28 (Juillet 2012) . - pp. 9609-9619 Mots-clés : Reversible  reaction  Stability  Reactor  Thermal  wave Résumé : Networks of fixed bed reactors with periodically switched inlet and outlet sections are studied with reference to equilibrium limited reactions. The methanol synthesis is selected as representative reaction example and the mechanisms governing the emergence of periodic regimes corresponding to trains of traveling thermal waves are analyzed. Analytical approximations, accounting for the influence of the implemented switching strategy and in satisfactory agreement with numerical simulation, are derived for the switch time stability limits in terms of temperature fronts velocities. Large and sudden variations in the switch time stability range of any wave train solution are demonstrated to occur when the sum of the velocities of declining temperature fronts exceeds the sum of the velocities of rising temperature fronts. The illustrated results provide indications on how to design and operate the network so as to generate thermal wave trains with desired number of waves and stability limits. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26163298

Numerical analysis of a periodically forced dyeing process / Erasmo Mancusi in Industrial & engineering chemistry research, Vol. 49 N° 18 (Septembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 18 (Septembre 2010) . - pp. 8568–8574 Titre : Numerical analysis of a periodically forced dyeing process Type de document : texte imprimé Auteurs : Erasmo Mancusi, Auteur ; Selene Guelli Ulson de Souza, Auteur ; Antônio Augusto Ulson de Souza, Auteur Année de publication : 2010 Article en page(s) : pp. 8568–8574 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Dyeing  Process Résumé : In this work, a forcing strategy based on a cyclic flow reversal of a dyeing process of bobbin threads is investigated through numerical simulation. Convection, dispersion, and adsorption of dye on the threads are modeled considering that the system is operated by a cyclic reversal of the flow direction through the bobbins. The periodic forcing is modeled by an ad hoc discontinuous periodic function, and a mathematical model that takes it into account is developed. The mathematical model is a set of partial differential equations that is reduced to a system of ordinary differential equations by an orthogonal collocation on finite elements technique. The comparison between forced and unforced processes has been carried out analyzing the dye distribution factor and the total amount of adsorbed dye during the transient regime for both of the processes. The main effect of periodic forcing is to enhance a more even dye distribution. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9017012 [article] Numerical analysis of a periodically forced dyeing process [texte imprimé] / Erasmo Mancusi, Auteur ; Selene Guelli Ulson de Souza, Auteur ; Antônio Augusto Ulson de Souza, Auteur . - 2010 . - pp. 8568–8574. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 18 (Septembre 2010) . - pp. 8568–8574 Mots-clés : Dyeing  Process Résumé : In this work, a forcing strategy based on a cyclic flow reversal of a dyeing process of bobbin threads is investigated through numerical simulation. Convection, dispersion, and adsorption of dye on the threads are modeled considering that the system is operated by a cyclic reversal of the flow direction through the bobbins. The periodic forcing is modeled by an ad hoc discontinuous periodic function, and a mathematical model that takes it into account is developed. The mathematical model is a set of partial differential equations that is reduced to a system of ordinary differential equations by an orthogonal collocation on finite elements technique. The comparison between forced and unforced processes has been carried out analyzing the dye distribution factor and the total amount of adsorbed dye during the transient regime for both of the processes. The main effect of periodic forcing is to enhance a more even dye distribution. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9017012

Optimal Reference Trajectory Shaping and Robust Gain-Scheduling for Transition Control of Nonlinear Processes / Pietro Altimari in Industrial & engineering chemistry research, Vol. 48 N° 20 (Octobre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 20 (Octobre 2009) . - pp. 9128–9140 Titre : Optimal Reference Trajectory Shaping and Robust Gain-Scheduling for Transition Control of Nonlinear Processes Type de document : texte imprimé Auteurs : Pietro Altimari, Auteur ; Lucia Russo, Auteur ; Erasmo Mancusi, Auteur Année de publication : 2010 Article en page(s) : pp. 9128–9140 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Nonlinear  processes  Transition  control  Gain  scheduling Résumé : A novel method for transition control of nonlinear processes is presented. Gain scheduling is implemented to ensure stability and desired output behavior over the operating region of interest while transition between the initial and the final steady state is achieved by predictive reference control (or reference governor). In this framework, the search of a feasible reference input sequence is performed so that the closed-loop system moves along an optimal curve of steady states. This curve is constructed off-line so that its points lie far from the border of the process constraint set and correspond to satisfactory controllability properties of the uncontrolled plant. Moreover, bifurcation analysis of the closed-loop system is performed by varying the reference signal according to the selected curve. In this way, regions of state multiplicity and/or instability are identified enabling the choice of the controller parameters values preventing transitions to undesired solution regimes. The method is validated on a simulated problem of start-up control of a jacketed continuous stirred tank reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9001553 [article] Optimal Reference Trajectory Shaping and Robust Gain-Scheduling for Transition Control of Nonlinear Processes [texte imprimé] / Pietro Altimari, Auteur ; Lucia Russo, Auteur ; Erasmo Mancusi, Auteur . - 2010 . - pp. 9128–9140. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 20 (Octobre 2009) . - pp. 9128–9140 Mots-clés : Nonlinear  processes  Transition  control  Gain  scheduling Résumé : A novel method for transition control of nonlinear processes is presented. Gain scheduling is implemented to ensure stability and desired output behavior over the operating region of interest while transition between the initial and the final steady state is achieved by predictive reference control (or reference governor). In this framework, the search of a feasible reference input sequence is performed so that the closed-loop system moves along an optimal curve of steady states. This curve is constructed off-line so that its points lie far from the border of the process constraint set and correspond to satisfactory controllability properties of the uncontrolled plant. Moreover, bifurcation analysis of the closed-loop system is performed by varying the reference signal according to the selected curve. In this way, regions of state multiplicity and/or instability are identified enabling the choice of the controller parameters values preventing transitions to undesired solution regimes. The method is validated on a simulated problem of start-up control of a jacketed continuous stirred tank reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9001553