Catalogue en ligne Bibliothèque Ecole Nationale Polytechnique d'Alger

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3752–3766

Titre :	Residence Time Theory
Type de document :	texte imprimé
Auteurs :	E. Bruce Nauman, Auteur
Année de publication :	2008
Article en page(s) :	p. 3752–3766
Langues :	Anglais (eng)
Résumé :	The intellectual roots of residence time theory date back to 1908 and, thus, span the 100-year history of Industrial & Engineering Chemistry. The theory was created, developed, and extended by chemical engineers. It permeates chemical engineering in general and chemical reaction engineering in particular. It also has found widespread utility in the geosciences, environmental engineering, medicine, and biology. This paper provides an overview of the theory and gives some new results here and there.
En ligne :	https://pubs.acs.org/doi/abs/10.1021/ie071635a

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3783–3794

Titre :	Flue-Gas Carbon Capture on Carbonaceous Sorbents: Toward a Low-Cost Multifunctional Carbon Filter for “Green” Energy Producers
Type de document :	texte imprimé
Auteurs :	Maciej Radosz, Auteur ; Xudong Hu, Auteur ; Kaspars Krutkramelis, Auteur
Année de publication :	2008
Article en page(s) :	p. 3783–3794
Langues :	Anglais (eng)
Résumé :	A low-pressure Carbon Filter Process (patent pending) is proposed to capture carbon dioxide (CO2) from flue gas. This filter is filled with a low-cost carbonaceous sorbent, such as activated carbon or charcoal, which has a high affinity (and, hence, high capacity) to CO2 but not to nitrogen (N2). This, in turn, leads to a high CO2/N2 selectivity, especially at low pressures. The Carbon Filter Process proposed in this work can recover at least 90% of flue-gas CO2 of 90%+ purity at a fraction of the cost normally associated with the conventional amine absorption process. The Carbon Filter Process requires neither expensive materials nor flue-gas compression or refrigeration, and it is easy to heat integrate with an existing or grassroots power plant without affecting the cost of the produced electricity too much. An abundant supply of low-cost CO2 from electricity producers is good news for enhanced oil recovery (EOR) and enhanced coal-bed methane recovery (ECBMR) operators, because it will lead to higher oil and gas recovery rates in an environmentally sensitive manner. A CO2-rich mixture that contains some nitrogen is much less expensive to separate from flue-gas than pure CO2; therefore, mixed CO2/N2-EOR and CO2/N2-ECBMR methods are proposed to maximize the overall carbon capture and utilization efficiency.
En ligne :	https://pubs.acs.org/doi/abs/10.1021/ie0707974

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3771–3782

Titre :	Global Capital/Total Annualized Cost Minimization of Homogeneous and Isothermal Reactor Networks
Type de document :	texte imprimé
Auteurs :	Wen Zhou, Auteur ; Vasilios I. Manousiouthakis, Auteur
Année de publication :	2008
Article en page(s) :	p. 3771–3782
Langues :	Anglais (eng)
Résumé :	The minimum capital cost/total annualized cost (MCC/MTAC) problem is investigated, within the infinite-dimensional state-space (IDEAS) framework, for homogeneous and isothermal reactor networks. The resulting mathematical formulation is an infinite-dimensional program with linear constraints and a separable concave objective function to be minimized. The global optimum of this infinite program is approximated through global solution of a series of finite-dimensional programs with concave separable objective functions and linear feasible regions. A branch-and-bound algorithm is used to solve globally each of these finite programs. The proposed methodology is illustrated with a reactor network synthesis case study aiming at capital cost minimization.
En ligne :	https://pubs.acs.org/doi/abs/10.1021/ie060653%2B

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3767-3770

Titre :	Solubility in the NH4NO3 + NaNO3 + H2O System
Type de document :	texte imprimé
Auteurs :	Mieczyslaw Trypuc, Auteur ; Sebastian Druzynski, Auteur
Année de publication :	2008
Article en page(s) :	p. 3767-3770
Langues :	Anglais (eng)
Résumé :	The mutual solubility of salts in the ternary system NH4NO3 + NaNO3 + H2O was investigated in the temperature range 293−323 K by the method of isothermal saturation of solutions. The data obtained were used for plotting the section of the solubility polytherm for the system investigated. Knowledge of the course of the solubility polytherm is necessary for developing a new method of utilization of the post-filtration lye from the soda−chlorine−saltpeter method (SCS) of soda production.
En ligne :	https://pubs.acs.org/doi/abs/10.1021/ie0709741

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3720-3751

Titre :	Structured Packings for Multiphase Catalytic Reactors
Type de document :	texte imprimé
Auteurs :	Kalyani Pangarkar, Auteur ; Tilman J. Schildhauer, Auteur ; J. Ruud van Ommen, Auteur
Année de publication :	2008
Article en page(s) :	p. 3720-3751
Langues :	Anglais (eng)
Mots-clés :	Structured packings
Résumé :	Reactor design for multiphase catalytic fixed bed reactors is always based on conflicting objectives. In the past, catalyst discovery and development preceded and motivated the selection of an appropriate multiphase reactor type. This type of sequential approach is increasingly been replaced by a parallel approach to catalyst and reactor selection. In nearly all respects, structured catalysts and reactors have the ability to outperform randomly packed reactors. Structured packings, apart from their advantages of high voidage and low-pressure drop, have the benefit of ease of scale-up and accurate description of the fluid mechanics. In this review we have evaluated the potential of using structured internals for multiphase catalytic reactions, which are currently carried out in randomly packed fixed bed reactors. Characteristics of various structured internals such as monoliths, corrugated sheet or gauze packings, knitted wire packings and foams are discussed in detail. Since designing a structured device for gas−liquid−solid contacting requires a sound knowledge of hydrodynamics and transport phenomena, a concise review of the above-mentioned structured packings and their characteristics based on hydrodynamics and transport phenomena is presented. Existing models (empirical, phenomenological and mechanistic) are outlined with respect to flow regime transition, pressure drop, liquid hold-up, gas−liquid interfacial area, gas to liquid mass transfer, liquid to solid mass transfer, residence time distribution (RTD), and heat transfer. The models are critically evaluated, and their limitations are discussed. An overview is given about what information is available, what needs to be evaluated and what kind of existing methodology can be applied in order to arrive at quantitative models for the physical parameters. Last, the structured internals are compared with each other and with randomly packed bed reactors, allowing a rational selection of the preferred packing for a given application.
En ligne :	https://pubs.acs.org/doi/abs/10.1021/ie800067r

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3708-3719

Titre :	Electrical Capacitance Tomography - A Perspective
Type de document :	texte imprimé
Auteurs :	Q. Marashdeh, Auteur ; L.-S. Fan, Auteur ; W. Warsito, Auteur
Année de publication :	2008
Article en page(s) :	p. 3708-3719
Langues :	Anglais (eng)
Mots-clés :	Electrical capacitance tomography (ECT)
Résumé :	This article describes the recent progress in research and development on electrical capacitance tomography (ECT). Specifically, the article highlights several aspects of ECT including the electrical capacitance volume tomography (ECVT), 3D sensor design, 3D neural network multicriterion image reconstruction technique (3D-NN-MOIRT), multimodal imaging based on ECT and ECVT sensors, static-charge effects and the scheme of their elimination in the ECT image reconstruction, and multiphase flow imaging applications. The multimodal capability that enables permittivity and conductivity imaging to be simultaneously conducted is illustrated. The simulation and experimental results are presented to provide quantitative and/or qualitative assessment of the significance of various ECT techniques. The employment of ECVT in conjunction with using electrical capacitance based imaging sensors is shown to represent a favorable tool for industrial multiphase flow imaging.
En ligne :	https://pubs.acs.org/doi/abs/10.1021/ie0713590

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3700-3707

Titre :	Micro-Nano Hierarchal Web of Activated Carbon Fibers for Catalytic Gas Adsorption and Reaction
Type de document :	texte imprimé
Auteurs :	Riju Mohan Singhal, Auteur ; Ashutosh Sharma, Auteur ; Nishith Verma, Auteur
Année de publication :	2008
Article en page(s) :	p. 3700-3707
Langues :	Anglais (eng)
Mots-clés :	Carbon nanofibers (CNF) ; the carbon web
Résumé :	A hierarchal web of activated carbon fibers is synthesized in which carbon nanofibers (CNF) are grown on micro activated carbon fibers (ACF) used as a substrate. A bed of ACF was first impregnated with nickel nitrate hexahydrate which was subsequently reduced to metallic nickel. Catalytic chemical vapor deposition (CVD) was then carried out at 1023 K using benzene as carbon source, which resulted in the growth of CNF. Conditions of hierarchal web formation were optimized by employing two different types of reactorsa perforated tube reactor with radially outward flow of gases and a perforated disc reactor providing a parallel flow. Both of these configurations were used for carrying out reduction and CVD. Our results show that relatively larger amount and uniformity of CNF could be obtained using the perforated disc reactor. Various analytical techniques including atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were employed to characterize the carbon web. The resulting ACF web is a hierarchical structure, which was tested for its NO removal capability by reduction. We found these carbon structures to be more efficient compared to the original ACF or ACF impregnated with metal.
En ligne :	https://pubs.acs.org/doi/abs/10.1021/ie071114n

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3687-3699

Titre :	Dynamic Modeling of a Moving-Packed-Bed Reactor for the Solid-State Polymerization of Bisphenol-A Polycarbonate
Type de document :	texte imprimé
Auteurs :	Yuesheng Ye, Auteur ; Kyu Yong Choi, Auteur
Année de publication :	2008
Article en page(s) :	p. 3687-3699
Langues :	Anglais (eng)
Mots-clés :	Dynamic Modeling ; Polymerization ; Polycarbonate
Résumé :	A dynamic process model has been developed for a continuous solid-state step-growth polymerization of bisphenol-A polycarbonate in a moving-packed-bed reactor. In this process, the molecular weight of polycarbonate prepolymer particles is increased as they move downward in a vertical reactor. A heated purge gas is supplied to the bottom of the reactor and flows upward at a high flow rate to remove volatile condensates from the polymer particles and provide thermal energy for the solid-state polymerization. A macroscopic reactor model and a polymer particle model are combined and solved together to calculate the reactor temperature profiles and the polymer-molecular-weight properties. The effects of reactor design and operation parameters on the performance of the solid-state polymerization reactor are analyzed through model simulations. It is shown that a large-scale moving-packed-bed reactor can have a significant temperature nonuniformity in the reactor, particularly during the startup operation, affecting the uniformity of the molecular weight of the polymer in the product.
En ligne :	https://pubs.acs.org/doi/abs/10.1021/ie071078s

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3677-3686

Titre :	Flow Visualization andThree-Dimensional CFD Simulation of the Annular Region of an Annular Centrifugal Extractor
Type de document :	texte imprimé
Auteurs :	Sandesh S. Deshmukh, Auteur ; Jyeshtharaj B. Joshi, Auteur
Année de publication :	2008
Article en page(s) :	p. 3677-3686
Langues :	Anglais (eng)
Mots-clés :	Computational fluid dynamics (CFD) ; Annular centrifugal extractor (ACE)
Résumé :	The single phase flow patterns in the annular region of an annular centrifugal extractor (ACE) have been studied both experimentally and computationally. Experiments were conducted using particle image velocimetry (PIV) and laser Doppler velocimetry (LDV) to understand the flow patterns and velocity profiles in both the presence and the absence of the net flow through the annulus. The data obtained in these experiments have been used for the validation of the computational fluid dynamics (CFD) simulations. Further, complete energy balance has been established. The CFD simulations were performed over a wide range of operating conditions. In contrast with the Taylor annular region (having no end effects), the ACE was found to exhibit markedly different cell patterns. The number of cells was found to be strongly dependent on the Taylor number. The effect of the internals such as radial baffles in the annulus, as well as vanes on the bottom plate, on the flow patterns has been investigated. From the simulations it was revealed that the flow patterns in ACE were also dependent on the start-up procedure of the equipment.
En ligne :	https://pubs.acs.org/doi/abs/10.1021/ie070959w

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3664-3676

Titre :	Decomposition of Flow Structures in Stirred Reactors and Implications for Mixing Enhancement
Type de document :	texte imprimé
Auteurs :	Andrea Ducci, Auteur ; Zacharias Doulgerakis, Auteur ; Michael Yianneskis, Auteur
Année de publication :	2008
Article en page(s) :	p. 3664-3676
Langues :	Anglais (eng)
Mots-clés :	Macro-instability (MI) ;Physical
Résumé :	Earlier studies have shown that macro-instability (MI) vortices in vessels stirred by radial flow impellers can be employed to improve mixing performance through guided feed insertion at selected radial positions along the path of a MI vortex, with an associated mixing time reduction of 20−30%. The present investigation provides for the first time an understanding of the physical mechanisms underlying the MI vortex phenomena, employing a proper orthogonal decomposition analysis to identify and characterize the different flow structures. It is shown that the MI structure is affected by an off-centering perturbation of the core and a stretching mechanism that interact in different ways for low, transitional, and high Reynolds numbers (Re). The different MI vortex frequencies phenomenologically identified in previous works and especially the two simultaneous frequencies encountered for transitional Re are shown to result from a competition between the two mechanisms. The implications of the fadings for mixing enhancement at different Re ranges are discussed.
En ligne :	https://pubs.acs.org/doi/abs/10.1021/ie070905m

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3652-3663

Titre :	Dispersion of Nanoparticle Clusters in a Rotor-Stator Mixer
Type de document :	texte imprimé
Auteurs :	Jerzy Baldyga, Auteur ; Wojciech Orciuch, Auteur ; lukasz Makowski, Auteur
Année de publication :	2008
Article en page(s) :	p. 3652-3663
Langues :	Anglais (eng)
Mots-clés :	Nanoparticles -- Properties ; Nanosuspensions
Résumé :	The unique properties of nanoparticles and nanoparticle clusters show high potential for nanomaterials to be formulated into numerous products. In this paper, nanosuspensions are formulated by breaking up nanoparticle clusters (called agglomerates) in high-shear flows. A new breakage model is introduced to interpret erosive dispersion of agglomerates, and the population balance modeling is applied to account for effects of breakage on agglomerate size distribution. Effects of suspension structure on its rheology and flow are included in modeling. The population balance equations are solved using the quadrature method of moments (QMOM) that is linked directly to the k−ε model of the computational fluid dynamics (CFD) code FLUENT. In dispersion experiments, the aqueous suspensions of fumed silica particles, Aerosil 200V, are used. The test rig consists of an in-line Silverson rotor−stator mixer and a stirred tank. The head is a two-stage rotor−stator design with the inner stator consisting of round holes and the outer stator consisting of smaller square holes. Experimental results are compared with model predictions.
En ligne :	https://pubs.acs.org/doi/abs/10.1021/ie070899u

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3645-3651

Titre :	Production of Hydrogen from Glucose as a Biomass Simulant: Integrated Biological and Thermochemical Approach
Type de document :	texte imprimé
Auteurs :	Sadashiv M. Swam, Auteur ; Vaibhav Chaudhari, Auteur ; Dong-Shik Kim, Auteur
Année de publication :	2008
Article en page(s) :	p. 3645-3651
Langues :	Anglais (eng)
Mots-clés :	Hydrogen ; Biomass simulant: Glucose
Résumé :	Hydrogen production from biomass was investigated using an integrated biological and thermochemical process. Glucose was used as a biomass surrogate and was first converted to ethanol in a fermentation process. The fermentation experiments were carried out using Saccharomyces cerevisiae. The fermentation broth was then used in aqueous phase reforming (APR) over a platinum-based catalyst. An economic analysis of the proposed process demonstrates the economic viability of producing hydrogen from biomass using fermentation combined with APR. The average production yield of hydrogen was ∼25%. The hydrogen obtained from APR of the fermentation broth was compared against the yield from a feed containing 5% ethanol in water. While the catalyst was stable for an extended time on stream during APR of ethanol, very rapid deactivation was observed during APR of fermentation broth. Different catalyst characterization techniques, including XRD, BET surface area, and ICP-AES, were employed to investigate the causes of catalyst deactivation. Although the analysis suggested similar catalyst changes in both cases, and the exact deactivation mechanism could not be concluded, these techniques helped to eliminate some mechanisms while suggesting other possible deactivation routes. Nanofiltration of the fermentation broth was shown to remove the impurities leading to deactivation.
En ligne :	https://pubs.acs.org/doi/abs/10.1021/ie070895p

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3639–3644

Titre :	Vertical Spreading of Aqueous Trisiloxane Solution Driven by a Spontaneously Developing Surface Tension Gradient
Type de document :	texte imprimé
Auteurs :	Anoop Chengara, Auteur ; Alex D. Nikolov, Auteur ; Darsh T. Wasan, Auteur
Année de publication :	2008
Article en page(s) :	p. 3639–3644
Langues :	Anglais (eng)
Mots-clés :	Spontaneous ; Trisiloxane surfactants ; Aqueous film
Résumé :	This article reports the results of experiments conducted on the spontaneous climbing of an aqueous film of trisiloxane surfactants (“superspreaders”) on a vertical strongly hydrophobic solid surface. The final height achieved is much in excess of that expected purely on the basis of the capillary wetting action and suggests that a spontaneously developing surface tension gradient aids in film climbing. Maxima are observed in both the spreading rate and the height achieved as a function of the surfactant concentration, similar to the spreading of a superspreader drop on a horizontal hydrophobic surface.
En ligne :	https://pubs.acs.org/doi/abs/10.1021/ie070862%2B

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3630–3638

Titre :	Liquid-Phase Residence Time Distribution for Two-Phase Flow in Coiled Flow Inverter
Type de document :	texte imprimé
Auteurs :	Subhashini Vashisth, Auteur ; K. D. P. Nigam, Auteur
Année de publication :	2008
Article en page(s) :	p. 3630–3638
Langues :	Anglais (eng)
Mots-clés :	The coiled flow inverter -- Liquid-phase residence time distribution(RTD) ; Gas -liquid ; newtonian fluids
Résumé :	The coiled flow inverter (CFI) is an innovative device, which has potential for the intensification of processes currently carried out in conventional mixers. Step response experiments were carried out in a CFI to study liquid-phase residence time distribution (RTD) for gas−liquid flow under the conditions of both negligible and significant molecular diffusion using Newtonian fluids. A total of 16 CFIs of different curvature ratios ranging from 6.7 to 20, dimensionless pitch from 1 to 2.5, and number of bends from 1 to 15 were investigated. The range of Dean numbers for the gas and the liquid phase was varied from 235 to 1180 and 3.16 to 1075, respectively. The reduction in dispersion number is nearly 2.6 times for two-phase flow in CFI with 15 number of bends as compared to a straight helix under identical process conditions. A modified axial dispersion model is proposed to describe the RTD. The efficiency of the device is characterized by a mixing criterion.
En ligne :	https://pubs.acs.org/doi/abs/10.1021/ie070447h

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3601–3618

Titre :	Influence of Distributed Secondary Gas Injection on the Performance of a Bubbling Fluidized-Bed Reactor
Type de document :	texte imprimé
Auteurs :	D. Christensen, Auteur ; J. Nijenhuis, Auteur ; J. Ruud van Ommen, Auteur ; M.-O. Coppen, Auteur
Année de publication :	2008
Article en page(s) :	p. 3601–3618
Langues :	Anglais (eng)
Mots-clés :	Bubbling Fluidized-bed reactor ; Gas injection
Résumé :	Distributed secondary gas injection via a fractal injector was studied in a lab-scale 3-D fluidized bed to determine its effect on bubble size, bubble fraction, residence time, mixing, and conversion. The experimental results indicate improved reactor performance and are consistent with earlier work in 2-D beds. A model was developed based on simple two-phase theory that describes the effect of distributed secondary injection on the performance of ozone decomposition in a bubbling fluidized bed. The model was used to predict the performance of a reactor for the production of maleic anhydride from n-butane, which includes consecutive and side reactions. The results showed that the production and selectivity of maleic anhydride were significantly improved. It can be concluded that distributed secondary gas injection improves the mass transfer and gas−solid contact, which results in increased reactor performance. It likely achieves these improvements by enhanced gas flow through the dense phase and more micromixing around the injection points, which causes greater interaction between the phases. Some aspects of applying this technology in industry are discussed.
En ligne :	https://pubs.acs.org/doi/abs/10.1021/ie071376p

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3619-3629

Titre :	Determination of Oxygen Permeability in Soft Contact Lenses Using a Polarographic Method: Estimation of Relevant Physiological Parameters
Type de document :	texte imprimé
Auteurs :	J.M. Gonzalez-meijome, Auteur ; V. Compañ-Moreno, Auteur ; E. Riande, Auteur
Année de publication :	2008
Article en page(s) :	p. 3619-3629
Langues :	Anglais (eng)
Mots-clés :	Oxygen ; Polarographic method
Résumé :	This work reports the apparent oxygen transmissibility Dk/t)app of four silicone hydrogel (Si−Hy) contact lenses (CLs). A method is described that allows the estimation of the oxygen tension at the lens−cornea interface for closed- and open-eyelids situations combining the instrument oxygen transmissibility (IOT) and corneal parameters such as corneal thickness, corneal permeability, and oxygen flux across the cornea. From these results, the biological oxygen apparent transmissibility (BOAT), equivalent oxygen percentage (EOP), partial pressure, (ptc), of oxygen at the cornea−CL interface and oxygen flux, (jc), were also obtained. This method allows the evaluation of the physiological environment under the lens using the formulations described in previous studies. The oxygen performance of four Si−Hy materials was evaluated using a polarographic cell coupled to a permeometer. Measurements of the apparent transmissibility, (Dk/t)app, and permeability, Dk, were performed in stacks containing from 1 to n repeated lenses and, from the values obtained, the error involved in the measurements in single samples was estimated. It was found that the values of (Dk/t)app and Dk obtained following the two different procedures (stack method and measurement of single sample) were significantly different from the nominal values given by the manufacturer, particularly for some samples. However, the impact of these differences on the values of the other physiologically relevant parameters (BOAT, EOP, ptc, and jc) was not significant. Furthermore, these parameters were similar for the four lenses in spite of the different (Dk/t)app measured. The relationships of (Dk/t)app with the remaining physiological parameters were calculated and graphically represented for open and closed-eyelid conditions.
En ligne :	https://pubs.acs.org/doi/10.1021/ie071403b

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3591–3600

Titre :	Globally Optimal Design and Operation of a Continuous Photocatalytic Advanced Oxidation Process Featuring Moving Bed Adsorption and Draft-Tube Transport
Type de document :	texte imprimé
Auteurs :	David M. Follansbee, Auteur ; John D. Paccione, Auteur ; Lealon L. Martin, Auteur
Année de publication :	2008
Article en page(s) :	p. 3591–3600
Langues :	Anglais (eng)
Mots-clés :	Oxidation -- Mathematical model ; UV photocatalytic mineralization ; draft tube trnsport
Résumé :	In this paper, we present a mathematical model for a continuous, integrated advanced oxidation process consisting of single-component adsorption, UV photocatalytic mineralization, and draft tube transport. The model is developed and employed as part of a strategy to determine optimal values of selected process design parameters and to identify suitable process operating conditions that may lead to an overall robust performance. An optimization-based algorithm is presented and applied to the design of a water purification system utilizing a composite titanium dioxide/activated carbon photocatalyst adsorbent immobilized on a silica substrate for the degradation of reactive red (RR) dye. A sensitivity analysis is performed to identify qualitative trends implicit in the proposed mathematical model and to measure the robustness of the resulting design over a range of process operating conditions.
En ligne :	https://pubs.acs.org/doi/abs/10.1021/ie071275r

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3582–3590

Titre :	Structure, stability, and upture of free and supported liquid films and assemblies in molecular simulations
Type de document :	texte imprimé
Auteurs :	Rahul Godawat, Auteur ; Sumanth N. Jamadagni, Auteur ; Jeffrey R. Errington, Auteur
Année de publication :	2008
Article en page(s) :	p. 3582–3590
Note générale :	Bibliogr. 3589-3590
Langues :	Anglais (eng)
Mots-clés :	Films -- Structure -- Stability
Résumé :	Attractive interactions between molecules lead to formation of the liquid phase at sufficiently low temperatures. In the absence of external fields or containers, liquids assume the shape of spherical drops, which minimize their surface area. In systems with 3-D periodic boundary conditions (PBCs), which are routinely employed in molecular simulations, alternate configurations can be stable depending on the extent of the system. The stability of a variety of structures under 3-D PBCs originates from the underlying variation of free energy with density as shown elegantly by MacDowell and co-workers (MacDowell, L. G.; Shen, V. K.; Errington, J. R. J. Chem. Phys. 2006, 125, 3.). Here we present analysis of extensive Monte Carlo and molecular dynamics simulations of Lennard-Jones and water fluids to calculate free energy and explore the phase diagram that governs formation of different liquid assemblies. We also study metastability of different shapes and their interconversions by systematically initializing simulations in various configurations. Further, We present results on the rupture of thin liquid films on solid substrates, with focus on the evolution of liquid structure and the rupture mechanism. Our estimates of important capillary wavelengths from simulations are in good agreement with theoretical predictions of Vrij and Overbeek (Vrij, A.; Overbeek, J. T. J. Am. Chem. Soc. 1968, 90, 3074−3078.). Collectively, our work significantly extends the previous simulation studies of interfacial systems, and especially of thin-film structure, stability, and rupture processes in molecular simulations.

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3568–3581

Titre :	Modeling copolymerization of styrene and acrylic acid via the free-radical retrograde-precipitation polymerization (FRRPP) process
Type de document :	texte imprimé
Auteurs :	Yadunandan L Dar, Auteur ; Yi Zhao, Auteur ; Gerard T. Caneba, Auteur
Année de publication :	2008
Article en page(s) :	p. 3568–3581
Note générale :	Bibliogr. p. 3576-3581
Langues :	Anglais (eng)
Mots-clés :	Acrylic acid--Modeling copolymerization ; Styrene acid ; Achilias Kiparissides model
Résumé :	The free-radical retrograde-precipitation polymerization (or FRRPP) process is a free-radical-based chain polymerization process that occurs above a lower critical solution temperature (LCST). The unique features of FRRPP have been exploited for the synthesis of novel amphiphilic materials under industrially practicable conditions. In the work described here, the copolymerization of styrene and acrylic acid via FRRPP is modeled and simulated to derive greater understanding behind the polymerization mechanism. The penultimate model is used to calculate the reactivity ratios. These reactivity ratios are used to calculate conversion, composition, and molecular weight distributions using the mole balance equations for the different species in the system and the Achilias Kiparissides model for the calculation of reaction rate coefficients. The results suggest that precipitation and the resulting phase separation and change in diffusivities have a strong impact on the polymerization kinetics. The penultimate model provides a better representation of the reactivities, in comparison to other approaches

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3562–3567

Titre :	Revisiting the performance of a coaxial mixer
Type de document :	texte imprimé
Auteurs :	Maya Farhat, Auteur ; Louis Fradette, Auteur ; Philippe A. Tanguy, Auteur
Année de publication :	2008
Article en page(s) :	p. 3562–3567
Note générale :	Bibliogr. 3567
Langues :	Anglais (eng)
Mots-clés :	Coaxial mixer ; Co-rotating ; Reynolds number
Résumé :	The performance of a coaxial mixer combining an anchor and a Rushton turbine was investigated for different diameter ratios and rotating modes in the laminar and transition flow regimes. Based on mixing efficiency criteria, this study confirmed that the co-rotating mode is consistently yielding the best results in the laminar and early transition regimes. The best performance was obtained for a turbine to tank diameter ratio of 1/3. In the upper transition and turbulent regimes, the best performance was obtained with the anchor at rest acting like two opposed baffles. With such a configuration, the optimum diameter ratio was found to be 1/2. New definitions of Reynolds number and power number were also introduced based on new characteristic diameter and speed. These correlations shown to be applicable for radial and axial impellers and are significantly better than the ones proposed in the literature.

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3554–3561

Titre :	Surfactants as microbicidal contraceptives : a calorimetric study of partitioning and translocation in model membrane systems
Type de document :	texte imprimé
Auteurs :	Meirav Apel-Paz, Auteur ; Gustavo F. Doncel, Auteur ; T. Kyle Vanderlick, Auteur
Année de publication :	2008
Article en page(s) :	p. 3554–3561
Note générale :	Bibliogr. 3560-3561
Langues :	Anglais (eng)
Mots-clés :	Surfactant partitioning ; microbicidal contraceptives
Résumé :	Surfactant partitioning into lipid vesicles was studied using isothermal titration calorimetry (ITC), comparing the behavior of four surfactants with current or potential application in contraception and the prevention of sexually transmitted diseases: nonoxynol-9 (N-9), the amphoteric mixture known as C31G, benzalkonium chloride (BZK), and sodium dodecyl sulfate (SDS). Membranes varied in composition from a single-component system, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, to a complex lipid mixture that models the sperm plasma membrane. The partitioning of N-9 into the membranes was found to be endothermic in contrast to the other surfactants studied. For all four surfactants, the partition coefficient decreased as the membrane cholesterol content increased. Surfactant translocation across the membrane leaflets was also determined, with SDS being the only surfactant of the four not to exhibit “flip-flop” on experimental time scales. The results of these studies shed light on the process of surfactant-induced membrane permeabilization

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3551–3553

Titre :	Measurements of the Flory-Huggins interaction parameter using a series of critical binary blends
Type de document :	texte imprimé
Auteurs :	Alisyn J. Nedoma, Auteur ; Megan L. Robertson, Auteur ; Nisita S. Wanakule, Auteur
Année de publication :	2008
Article en page(s) :	p. 3551–3553
Note générale :	bibliogr. p. 3553
Langues :	Anglais (eng)
Mots-clés :	Flory-Huggins ; Polyisobutylene ; Neutron scattering
Résumé :	The Flory-Huggins interaction parameter, X, for a series of critical binary blends of polyisobutylene and deuterated polybutadiene was measured by small-angle neutron scattering. X was determined by fitting the scattering intensity profiles single-phase blends to the well-established random-phase approximation. Our experiments, which covered a wide range of chain lengths, suggest that X depends on both blend composition and the ratio of the homopolymer chain lengths.

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3540–3550

Titre :	Polarographic method for measuring oxygen diffusivity and solubility in water-saturated polymer films : application to hypertransmissible soft contact lenses
Type de document :	texte imprimé
Auteurs :	Mahendra Chhabra, Auteur ; John M. Prausnitz, Auteur ; C. J. Radke, Auteur
Année de publication :	2008
Article en page(s) :	p. 3540–3550
Note générale :	Bibliogr. p.3549-3550
Langues :	Anglais (eng)
Mots-clés :	Oxygen -- Electrochemical-polarographic method ; Polarographic method
Résumé :	An electrochemical-polarographic method is described for measuring the diffusivity, D, and solubility, k, of oxygen in aqueous-saturated polymer films. While the apparatus and procedure are general for such films, it is here applied to determine D and k for oxygen in hypertransmissible soft contact lenses. Usually, only oxygen permeability, P, the product of D and k, is measured because P gauges the steady flux of oxygen through hydrogel membranes. However, we utilize the polarographic technique in the unsteady state and, hence, obtain D and k separately. Determination of each of these properties is critical for designing better lens materials that ensure sufficient oxygen supply to the cornea. We have measured oxygen diffusivities and solubilities for nine commercial soft contact lenses. Our data indicate that oxygen diffusivity is primarily responsible for the range of oxygen permeability observed for hypertransmissible soft contact lenses. For 2-hydroxyethyl methacrylate (HEMA)-based lenses, measured solubilities suggest that over 90% of the dissolved oxygen partitions to the polymer phase

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3532–3539

Titre :	Comparison of continuous blend time and residence time distribution models for a stirred tank
Type de document :	texte imprimé
Auteurs :	Vesselina Roussinova, Auteur ; Suzanne M. Kresta, Auteur
Année de publication :	2008
Article en page(s) :	p. 3532–3539
Note générale :	Bibliogr. p. 3538-3539
Langues :	Anglais (eng)
Mots-clés :	Stirred tank; Residence time distribution
Résumé :	In continuous operation, mixing in a stirred tank is often characterized by the residence time distribution (RTD) curves and the mean residence time (V/Q). The RTD is a measure of the history of the fluid element flowing through the reactor rather than a measure of the local mixing conditions inside the vessel. In this study, additional information about local mixing is obtained by taking measurements inside the vessel. The variance of concentration fluctuations from three probes (two located inside the tank and one at the outlet) is used to determine the continuous blend time (θcnts). At the limiting condition of a slow feed rate relative to the batch blend time, the CSTR is ideal, but at high flow rates the mixing inside the vessel deviates by up to 50% from the ideal case. Three design guidelines are recommended for designs where ideal mixing conditions are required. First, a line from the inlet to the outlet should pass through the impeller. Second, the feed velocity should decay to the mean impeller suction velocity by the time the feed reaches the impeller for the case of surface feed above a downpumping impeller. Third, the ratio of the mean residence time (V/Q) to the batch blend time (θb) should be at least 10. Additional guidelines will be needed for tank configurations where the feed(s) and/or outlet(s) are located on the side of the vessel.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie070955r

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3525–3531

Titre :	Comparison between effective electrode/electrolyte interface potential and applied potential for gold electrodes
Type de document :	texte imprimé
Auteurs :	Patricia Taboada-Serrano, Auteur ; Viriya Vithayaveroj, Auteur ; Chia-Hung Hou, Auteur ; Sotira Yiacoumi, Auteur
Année de publication :	2008
Article en page(s) :	p. 3525–3531
Note générale :	Bibliogr. p. 3530-3531
Langues :	Anglais (eng)
Mots-clés :	Gold electrode; AFM measurements
Résumé :	A nonlinear solution of the Poisson−Boltzmann equation between two interacting surfaces was used to model the interaction force between a gold electrode and a standard silicon−nitride cantilever tip employed in atomic force microscopy (AFM). AFM measurements were used to calculate the effective gold electrode/electrolyte solution interface potential via minimization of the error between predicted interaction force values and those measured via AFM. Analysis of the data reveals that an effective electrode/electrolyte potential, rather than the applied potential to the electrode, is responsible for the interaction forces observed in this work. Further examination of the gold electrode/electrolyte interface via cyclic voltammetry reveals that, despite the fact that the gold electrode is considered inert, some degree of association of ions present in the solution with the gold electrode occurs. Accumulation of different ions in the solution at the electrode/electrolyte interface determines the magnitude of the effective potentials at different conditions of pH and ionic strength. At extreme conditions of pH, electrosorption of ionic species could be detected.
En ligne :	http://pubs.acs.org/doi/10.1021/ie070900p

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3515–3524

Titre :	Multifunctional reactor for the synthesis of dimethylacetal
Type de document :	texte imprimé
Auteurs :	Carla S. M. Pereira, Auteur ; Pedro Sa Gomes, Auteur ; Ganesh K. Gandi, Auteur ; Viviana M. T. M. Silva, Auteur
Année de publication :	2008
Article en page(s) :	p. 3515–3524
Note générale :	Bibliogr. p. 3523-3524
Langues :	Anglais (eng)
Mots-clés :	Dimethylacetal; Simulated moving bed reactor
Résumé :	The synthesis of dimethylacetal (1,1-dimethoxyethane) was performed in a Simulated Moving Bed Reactor (SMBR) pilot unit LICOSEP 12-26 (Novasep, France) with 12 columns packed with the acid resin Amberlyst-15 wet (Rohm & Haas, France). For the operating conditions used, the performance parameters obtained were as follows: acetal purity, 91.41%; productivity rate, 5.17 kgacetal/(Ladsorbent day); and desorbent consumption, 7.11 Lmethanol/kgacetal. The effect of the switching time, feed composition, and desorbent flow rate in the performance of the SMBR was studied by means of two mathematical models approaches: the SMBR model (for the concentration profiles and performance parameters) and the True Moving Bed Reactor (TMBR) model (for the reaction separation regions).
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie070889t

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3502–3514

Titre :	Control of complex dynamics with time-delayed feedback in populations of chemical oscillators : desynchronization and clustering
Type de document :	texte imprimé
Auteurs :	Yumei Zhai, Auteur ; István Z. Kiss, Auteur ; John L. Hudson, Auteur
Année de publication :	2008
Article en page(s) :	p. 3502–3514
Note générale :	Bibliogr. p. 3513-3514
Langues :	Anglais (eng)
Mots-clés :	Complex dynamics; Chemical oscillators; Desynchronization; Clustering
Résumé :	Control of collective dynamics with global time-delayed feedback was experimentally studied with (phase) synchronized populations of smooth, relaxational, and chaotic electrochemical oscillators. The experimental results provide laboratory evidence for the findings in the studies of delayed feedback on phase oscillators; multiple, isolated regions of desynchronization in the parameter plane, hysteresis phenomenon around the boundaries of control regions, synchronization of irregular behavior with very strong feedback strength, and a shift of the synchronization transition curves were reproduced in experiments. In addition, it is observed that clustering accompanies the occurrence of desynchronization in delayed feedback of relaxational oscillators. For populations of elements that are close to Hopf bifurcation, desynchronization, amplitude death, and enhanced synchronization occurs with a low, intermediate, and high delay time, respectively.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie0708632

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3489–3501

Titre :	Multiobjective optimal design of heat exchanger networks using new adaptations of the elitist nondominated sorting genetic algorithm, NSGA-II
Type de document :	texte imprimé
Auteurs :	Aaditya Agarwal, Auteur ; Santosh K. Gupta, Auteur
Année de publication :	2008
Article en page(s) :	p. 3489–3501
Note générale :	Bibliogr. p. 3500-3501
Langues :	Anglais (eng)
Mots-clés :	Heat exchanger networks; NSGA-II-sJG
Résumé :	A new approach for generating optimal heat exchanger networks (HENs) is described that does not use any heuristics. This approach involves generating the number of intermediate temperatures in each of the hot and cold streams and their values, randomly, using the binary coded NSGA-II-sJG. The substreams so generated are then matched randomly. This procedure results in a variable number of decision variables in each solution (chromosome). Dummy decision variables are introduced so as to make the length of each chromosome the same. A new crossover strategy, crossA, as well as a few other adaptations, are described that enable faster convergence to the optimal solution(s). Three single-objective problems involving the minimization of the annualized cost are solved and the results compared with those reported in the literature. Thereafter, a few problems with two- and three-objective functions are solved. In these, the objective functions are selected from among the annualized cost, the amount of (hot + cold) utilities required (these are important due the environmental issues associated with them), the energy recovery, and the total number of units. To the best of our knowledge, such multiobjective optimization of HENs has not been reported in the open literature yet. A decision maker can choose any of the solutions from among the set of several nondominated (equally good) Pareto-optimal solutions generated. These are more meaningful than those obtained using single objective functions. Though the algorithm developed is specific to HENs, it can easily be applied to other similar optimization problems.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie070805g

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3470–3488

Titre :	Rheology of non-newtonian fluids containing glass fibers : a review of experimental literature
Type de document :	texte imprimé
Auteurs :	Aaron P. R. Eberle, Auteur ; Donald G. Baird, Auteur ; Peter Wapperom, Auteur
Année de publication :	2008
Article en page(s) :	p. 3470–3488
Note générale :	Bibliogr. p. 3486-3488
Langues :	Anglais (eng)
Mots-clés :	Glass fiber; Non-Newtonian fluids
Résumé :	The objective of this review is to elucidate the rheological behavior of glass fiber suspensions whose suspending mediums are non-Newtonian fluids. In particular, this review focuses on determining the impact of fiber concentration, aspect ratio, orientation distribution, interaction with the suspending medium, and suspending medium viscoelasticity on the rheology of glass fiber composite fluids. The presence of glass fiber can induce a yieldlike behavior, causing shear thinning to occur at reduced shear rates. Glass fiber can impede the elastic properties of the suspending medium but enhance the first normal stress function. Large stress overshoots in both the shear and normal stress growth functions are observed that are associated with changes in fiber orientation. Upon cessation of flow, stress relaxation follows that of the suspending medium but fibers retain their orientation. The presence of glass fiber can induce extension rate thinning and suppress the strain thickening behavior of the suspending medium.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie070800j

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3460–3469

Titre :	An extension to the incorporation model of micromixing and its use in estimating local specific energy dissipation rates
Type de document :	texte imprimé
Auteurs :	M. Assirelli, Auteur ; E. J. W. Wynn, Auteur ; W. Bujalski, Auteur ; A. Eaglesham, Auteur
Année de publication :	2008
Article en page(s) :	p. 3460–3469
Note générale :	Bibliogr. p. 3469
Langues :	Anglais (eng)
Mots-clés :	Micromixing; Extension; Polynomial equations
Résumé :	The incorporation model of micromixing first developed conceptually and quantified by Villermaux and co-workers has been extended to cover both higher rates of micromixing (higher mean and local specific energy dissipation rates) and higher reaction rates (by using higher acid concentrations in the iodide−iodate model reaction scheme). The extended model has involved the use of Bader and Deuflhard's semi-implicit discretization in the Bulirsch−Stoer method, which is especially suitable for stiff ordinary differential equations. Both exponential and linear rates of incorporation were considered, and polynomial equations for three acid concentrations for micromixedness ratios, α, from ∼1 to ∼100, were determined. It was shown that, though different acid concentrations gave different α values at the same feed position and agitation conditions, the micromixing time estimated from the model was constant (as it should be) with exponential incorporation. With linear incorporation, the micromixing time was much less and not constant and was therefore rejected for further analysis. Subsequently, it was shown that φ, the ratio of the local specific energy dissipation rate, εT, to the average, εT, i.e., φ = εT/εT, was constant at the same reactant feed position except when fed into the region of (εT)max close to the impeller. In this case, φ fell with increasing speed as the reactants were swept more rapidly from this region to regions of lower φ. By comparing estimates of φ from feeding a reactant at equivalent positions with a static pipe and one rotating with the impeller, it was found that Φ = φpoint,max/φensemble,max was ∼2.7, in reasonable agreement with the value of ∼3 very recently obtained by Ducci and Yianneskis (AIChE J. 2005, 51, 2133) based on two-point laser Doppler anemometry (LDA) measurements. The absolute value of φensemble,max was rather high compared to the most recent estimates from LDA or particle image velocimetry (PIV), which may reflect some weakness in the model or in the quality of the chemical kinetics data.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie070754n

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3453–3459

Titre :	Room-temperature ionic liquids : temperature dependence of gas solubility selectivity
Type de document :	texte imprimé
Auteurs :	Alexia Finotello, Auteur ; Jason E. Bara, Auteur ; Dean Camper, Auteur ; Richard D. Noble, Auteur
Année de publication :	2008
Article en page(s) :	p. 3453–3459
Note générale :	Bibliogr. p. 3459
Langues :	Anglais (eng)
Mots-clés :	CO2; CH4; H2; N2; Bulk fluid solubility
Résumé :	This study focuses on bulk fluid solubility of carbon dioxide (CO2), methane (CH4), hydrogen (H2), and nitrogen (N2) gases in the imidazolium-based RTILs: 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]), 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF4]), 1-n-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([hmim][Tf2N]), and 1,3-dimethylimidazolium methyl sulfate ([mmim][MeSO4]) as a function of temperature (25, 40, 55, and 70 °C) at near-atmospheric pressures. The experimental behaviors are explained in terms of thermodynamic relationships that account for the negligible vapor pressure of the RTIL as well as the low solubilities of the gases. Results show that, as temperature increases, the solubility of CO2 decreases in all RTILs, the solubility of CH4 remains constant in [emim][Tf2N] and [hmim][Tf2N] but increases in [mmim][MeSO4] and [emim][BF4], and the solubility of N2 and H2 increases. Also, the ideal solubility selectivity (ratio of pure-component solubilities) increases as temperature decreases for CO2/N2, CO2/CH4, and CO2/H2 systems. Experimental values for the enthalpy and entropy of solvation are reported.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie0704142

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3444–3452

Titre :	Optimum UV disinfection between concentric cylinders
Type de document :	texte imprimé
Auteurs :	Z. Ye, Auteur ; L. J. Forney, Auteur ; T. Koutchma, Auteur ; A. T. Giorges, Auteur
Année de publication :	2008
Article en page(s) :	p. 3444–3452
Note générale :	Bibliogr. p. 3452
Langues :	Anglais (eng)
Mots-clés :	UV disinfection; Concentric cylinders; Laminar Poiseuille flow; Turbulent flow; Laminar Taylor−Couette flow
Résumé :	To optimize UV disinfection of microbes between concentric cylinders, inactivation in the plug flow reactor geometries of laminar Poiseuille flow, turbulent flow, and laminar Taylor−Couette flow is investigated experimentally and numerically. It is found that there is an optimum ratio of radiation penetration depth to gap width λ/d for each of the three flow patterns. The optimum λ/d for laminar Poiseuille flow, turbulent flow, and laminar Taylor−Couette flow are 1.5, 1, and 0.5, respectively. It is also concluded that laminar Poiseuille flow provides inferior (small) inactivation levels while laminar Taylor−Couette flow provides superior (large) inactivation levels. The relative inactivation levels are as follows: laminar Poiseuille flow < turbulent flow < laminar Taylor−Couette flow.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie0703641

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3438–3443

Titre :	Scale-up of solids distribution in slurry, stirred vessels based on turbulence intermittency
Type de document :	texte imprimé
Auteurs :	G. Montante, Auteur ; J. R. Bourne, Auteur ; F. Magelli, Auteur
Année de publication :	2008
Article en page(s) :	p. 3438–3443
Note générale :	Bibliogr. p. 3442-3443
Langues :	Anglais (eng)
Mots-clés :	Scale-up criteria; Stirred vessels; Turbulent fluctuations
Résumé :	Scale-up criteria for obtaining the same vertical concentration profile of particles in agitated, dilute suspensions are considered. Previous experiments in two sizes of high aspect ratio vessels stirred by multiple impellers (either pitched blade or Rushton turbines) gave n = 0.93 in the scale-up relationship32 NDn = constant. This result is intermediate between constant power per unit volume (n = 2/3) and constant tip speed (n = 1), although closer to the latter. It is now suggested that intermittent turbulent fluctuations greater than their average values play a part in maintaining vertical concentration gradients. An analysis of solids suspension by intermittent turbulence gives n ≈ 0.93. This value is also supported by additional experimental data as well as by new CFD results.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie070339v

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3430–3437

Titre :	Stochastic analysis of multistate systems
Type de document :	texte imprimé
Auteurs :	Eric Sherer, Auteur ; Doraiswami Ramkrishna, Auteur
Année de publication :	2008
Article en page(s) :	p. 3430–3437
Note générale :	Bibliogr. p. 3436-3437
Langues :	Anglais (eng)
Mots-clés :	Multistate systems; Stochastic framework; Monte Carlo simulations
Résumé :	The treatment necessary to remove all cells for a periodic cell cycle specific regimen is analyzed using stochastic equations of a multistate model with state transition governed by residence time distributions. While the objective is to remove all cells, exactly when this occurs is uncertain due to the random timing of state transitions. Previous work has shown that removal of all cells requires great certainty that the number of cells is small; an expected population that is six standard deviations less than one cell is an indicator when cure is nearly likely. In developing the necessary stochastic framework, the expression for the standard deviation for multistate processes is derived and a simple two-state example is presented that illustrates the potential coupling between subpopulations. Finally, the methodology is applied to cell cycle specific chemotherapy and the number of cycles required to nearly be assured that zero cells remain is calculated. This method has computational advantages over Monte Carlo simulations when the initial number of cells is not small and only the variation in the total number of cells is of interest.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie701723u

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3410–3429

Titre :	Guidelines for modeling based on experiences with radiantly stabilized combustion
Type de document :	texte imprimé
Auteurs :	Stuart W. Churchill, Auteur
Année de publication :	2008
Article en page(s) :	p. 3410–3429
Note générale :	Bibliogr. p. 3428-3429
Langues :	Anglais (eng)
Mots-clés :	Combustion; Radiantly stabilization
Résumé :	Many processes of interest in chemical engineering are yet beyond the reach of a numerical solution in a practical sense. For such processes, creative modeling by means of idealizations and approximations and innovative methods of solution may be needed. Homogeneous combustion, because of extreme temperature gradients, developing flow, turbulent convection of momentum, energy, and species, thermal radiation, and a seemingly unlimited array of free-radical reactions, each with a complex and uncertain dependence on temperature, exemplifies such a process. Guidelines for such modeling have been identified from the accumulative experiences of a long sequence of research on one form of combustion, namely that stabilized primarily by thermal radiation.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie070945q

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3401–3409

Titre :	Adsorption of chromium(VI) from aqueous solutions using an imidazole functionalized adsorbent
Type de document :	texte imprimé
Auteurs :	Hyung-Jun Park, Auteur ; Lawrence L. Tavlarides, Auteur
Année de publication :	2008
Article en page(s) :	p. 3401–3409
Note générale :	Bibliogr. p. 3408-3409
Langues :	Anglais (eng)
Mots-clés :	Chromium(VI) -- separation; Imidazole functionalized adsorbent; Sol-gel synthesis method
Résumé :	Separation of chromium(VI) from aqueous solutions is investigated using an imidazole functionalized sol−gel adsorbent. This adsorbent has been formed by the sol−gel synthesis method. The speciation diagram of Cr(VI) in an aqueous system with varying pH is studied by analyses of the equilibria equations. Batch adsorption equilibrium studies show a decrease in chromium uptake capacity with increase in pH in the range from 2 to 9, and the uptake capacity at pH 2.5 is found to be 2.93 mmol/g (152 mg/g). The Langmuir adsorption isotherm gives a satisfactory fit of the adsorption data. A kinetics study conducted with different concentrations of chromium(VI) in a batch reactor shows a rapid rate of adsorption. The adsorbent shows a high selectivity toward Cr(VI) and negligible adsorption of Cu(II), Ni(II), and Zn(II). Adsorption tests in a fixed bed column show a sharp breakthrough curve. Stripping of the chromium-loaded column bed is achieved using 4 M HNO3. Twenty cycles of adsorption and desorption process are performed for SOL-IPS adsorbent. The adsorbent maintains 90% of original capacity during 15 cycles, and loss of 25% of capacity until 20 cycles of operation. The imidazole functional adsorbent is demonstrated to be an effective sorbent material for the separation of chromium(VI) from aqueous solutions.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie7017096

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3388–3400

Titre :	Identification of the attainable region for batch reactor networks
Type de document :	texte imprimé
Auteurs :	Benjamin J. Davis, Auteur ; Larry A. Taylor, Auteur ; Vasilios I. Manousiouthakis, Auteur
Année de publication :	2008
Article en page(s) :	p. 3388–3400
Note générale :	Bibliogr. p. 3399-3400
Langues :	Anglais (eng)
Mots-clés :	Batch reactors; Infinite DimEnsionAl State-space framework; Linear program
Résumé :	In this work, we describe a method for automatically identifying the set of all points in concentration space that represent outlet compositions of some network of discretely fed batch reactors for a given reaction set with known kinetics. This so-called batch attainable region (BAR) is dependent on the batch network's feed and total operating time, and it is shown to be quantifiable using the Infinite DimEnsionAl State-space (IDEAS) framework. We first establish that a simple batch reactor model possesses the properties that allow application of the IDEAS framework. We then formulate the resulting IDEAS Infinite Linear Program (ILP) whose solution is guaranteed to identify the globally optimal network of batch reactors. We subsequently use a simple transformation of this IDEAS ILP that leads us to propose two algorithms that are related to the construction of the true BAR. The first is a “Shrink-Wrap”-like algorithm that is similar to that previously reported [Manousiouthakis et al. The Shrink-Wrap Algorithm for the Construction of the Attainable Region: Application of the IDEAS Framework. Comput. Chem. Eng. 2004, 28, 1563] and creates increasingly accurate approximations of a set guaranteed to contain the true BAR for all network operating times. The second is a breadth-first algorithm that creates increasingly accurate inner approximations to the BAR for a given network operating time. These two algorithms are applied to an example from the literature and are shown analytically to converge in the limit to the true BAR.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie071664l

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3380–3387

Titre :	Two approximate methods to estimate conversion and yield in mixed chemical reactors
Type de document :	texte imprimé
Auteurs :	Gary K. Patterson, Auteur
Année de publication :	2008
Article en page(s) :	p. 3380–3387
Note générale :	Bibliogr. p. 3386-3387
Langues :	Anglais (eng)
Mots-clés :	Reactors -- chemical reaction; Computational fluid dynamics
Résumé :	In many cases, quick methods are needed to evaluate the conversion and yield that may occur in a given reactor with a desired chemical reaction and necessary product. Full experimentation and/or full numerical simulation to evaluate the situation is neither warranted nor needed. In many cases, methods even quicker than computational fluid dynamics (CFD) with closure are needed to approximate yield results for various versions of a reactor. This paper reviews two methods that might be used beyond assuming perfect mixing or perfect plug flow to determine the likely conversion and yield for reactions in tubular reactors with mixing effects and in stirred vessel reactors. These methods can typically be implemented using a simple numerical integration program (such as POLYMATH) and/or a math program (such as MATLAB). In most cases, the results will not perfectly duplicate actual laboratory or pilot results, but simulated comparisons of various reactor setups can be made which are likely to be valid, because they can give the trends that occur for given changes. Such simplified calculations should always be made before more costly laboratory and simulation efforts are made. The approximate methods reviewed and compared are plug-flow mixing in a pipe with or without static mixing elements and several segment mixing in a stirred vessel. Closures for the extent of mixing in the pipes or segments are paired-interaction (P-I) and random coalescence and dispersion (C−D) mixing, both of which have shown good correspondence with the experimental results when used in CFD simulations.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800042t

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3372–3379

Titre :	Supercritical reaction calorimetry : versatile tool for measuring heat transfer properties and monitoring chemical reactions in supercritical fluids
Type de document :	texte imprimé
Auteurs :	Charalampos A. Mantelis, Auteur ; Thierry Meyer, Auteur
Année de publication :	2008
Article en page(s) :	p. 3372–3379
Note générale :	Bibliogr. p. 3378-3379
Langues :	Anglais (eng)
Mots-clés :	Calorimetry technique; Supercritical fluids; Polymerization
Résumé :	The heat flow reaction calorimetry technique was developed for reactions with supercritical fluids and was applied to monitor the free-radical dispersion polymerization of methyl methacrylate in supercritical carbon dioxide (scCO2). The main mathematical equation for the calorimetric calculations was modified to take into account the particularities linked to the supercritical nature of the solvent. As a result, important heat transfer variables, such as the overall heat transfer coefficient, can be measured at the actual reaction conditions. This information is later used to calculate the heat released by the reaction and thus monitor its evolution. The robustness and accuracy of the technique allowed also investigating the effects of several reaction parameters. Finally, the obtained data were used to illustrate the importance of pressure as far as the safety of the reaction is concerned.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie0712030

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3364–3371

Titre :	Experimental and correlational studies of a vickers-zimmer style polyester finisher
Type de document :	texte imprimé
Auteurs :	W. Roy Penney, Auteur ; Anurag Singh, Auteur
Année de publication :	2008
Article en page(s) :	p. 3364–3371
Note générale :	Bibliogr. p. 3371
Langues :	Anglais (eng)
Mots-clés :	Vickers-Zimmer disk polyester finisher; Spoked-disk style; Mass-transfer coefficients
Résumé :	An 8-in. (0.203 m)-diameter Vickers-Zimmer disk style polyester finisher was tested using carboxymethylcellulose and corn syrup solutions. The processor consisted of a spoked-disk style agitator, with 20, 5-spoke disks, in a horizontal cylindrical vessel. To prevent the liquid batch from rotating with the disks, stationary breaker bars, between each of five adjacent disks, and 210° baffle plates, between every fifth disk, were installed. Fractional liquid holdup, agitator power, angles of batch rise and depression at the vessel walls, fractional liquid film coverage of the spoked disk cutouts, and mass-transfer coefficients were all determined experimentally. Dimensionless correlations were developed for (1) fractional liquid disk holdup, (2) agitator power requirements, (3) angles of rise and depression at the vessel wall, (4) factional film coverage of the spoked wheel cutouts, and (5) mass-transfer coefficient.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie061656p

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3358–3363

Titre :	Kinetic modeling of immobilized lipase catalysis in synthesis of n-butyl levulinate
Type de document :	texte imprimé
Auteurs :	Ganapati D. Yadav, Auteur
Année de publication :	2008
Article en page(s) :	p. 3358–3363
Note générale :	Bibliogr. p. 3363
Langues :	Anglais (eng)
Mots-clés :	n-Butyl levulinate -- esterification; Immobilized lipases
Résumé :	n-Butyl levulinate is used as an important intermediate having diverse applications. The present work focuses on the synthesis of n-butyl levulinate by esterification of levulinic acid with n-butanol by using immobilized lipases. Novozym 435 (Candida antarctica lipase) was found to be the most efficient catalyst, and tetra-butyl methyl ether was the best solvent. Effects of various parameters were studied to analyze the kinetics and mechanism of the lipase action. Ping-pong bi−bi mechanism with n-butanol substrate inhibition was found to describe the kinetics of the reaction. The kinetic parameters evaluated from initial rate data were used to simulate the experimental results. There was a very good agreement between theory and experiment.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800193f

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3346–3357

Titre :	Visible light photocatalytic oxidation of toluene using a cerium-doped titania catalyst
Type de document :	texte imprimé
Auteurs :	Meera Sidheswaran, Auteur ; Lawrence L. Tavlarides, Auteur
Année de publication :	2008
Article en page(s) :	p. 3346–3357
Note générale :	Bibliogr. p. 3356-3357
Langues :	Anglais (eng)
Mots-clés :	Cerium-doped titania photocatalyst; Toluene; Mass transfer
Résumé :	This paper focuses on the evaluation of the potential to use a cerium-doped titania photocatalyst activated by visible light to destroy volatile organics. Toluene is the model compound employed to test the photocatalyst, which is coated on the inner surface of an annular plug flow reactor. Mass transfer resistances are present and considered. Experiments were conducted over a range of residence times between 1 and 20 s and toluene concentrations between 150 and 600 ppb using constant visible-light intensity at room temperature. It is shown that the reaction kinetics can be approximated by a first-order expression with a reaction rate coefficient of 1.72 ± 0.015 s-1. The water adsorption coefficient was found to be 2.64 m3/mol. The catalyst also demonstrates mechanical and chemical stability during the course of the experiments conducted. These results indicate that the cerium based titania catalytic surfaces can be considered for application to destruction of volatile organic hydrocarbons in air using a visible light source.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie071276j

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3338–3345

Titre :	On brownian dynamics simulation of nanoparticle aggregation
Type de document :	texte imprimé
Auteurs :	Sergiy Markutsya, Auteur ; Shankar Subramaniam, Auteur ; R. Dennis Vigil, Auteur ; Rodney O. Fox, Auteur
Année de publication :	2008
Article en page(s) :	p. 3338–3345
Note générale :	Bibliogr. p.
Langues :	Anglais (eng)
Mots-clés :	Nanoparticle aggregation; Brownian dynamics simulations; Dimensionless variable
Résumé :	Accurate simulation and control of nanoparticle aggregation in chemical reactors requires that population balance equations be solved by using realistic expressions for aggregation and breakage rate kernels. Obtaining such expressions requires that atomistic simulation approaches that can account for microscopic details of particle collisions be used. In principle, molecular dynamics simulations can provide the needed microscopic information, but because of the separation in length scales between the aggregates and solvent molecules, such simulations are too costly. Brownian dynamics simulations provide an alternative to the molecular dynamics approach for simulation of particle aggregation, but there has been no systematic attempt to validate the Brownian dynamics method for this class of problems. In this work we attempt to develop a better understanding of Brownian dynamics simulations of aggregation by (1) developing convergence criteria, (2) determining criteria for aggregation to occur in BD simulations using dimensionless variables, and (3) directly comparing BD and MD simulation predictions for a model aggregation problem.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie0711168

[article]
in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3291–3337

Titre :	A review on the potential applications of curved geometries in process industry
Type de document :	texte imprimé
Auteurs :	Subhashini Vashisth, Auteur ; Vimal Kumar, Auteur ; Krishna D. P. Nigam, Auteur
Année de publication :	2008
Article en page(s) :	p. 3291–3337
Note générale :	Bibliogr. p. 3327-3337
Langues :	Anglais (eng)
Mots-clés :	Curved tubes; Friction factor; Heat transfer; Mass transfer
Résumé :	The potential industrial applications of curved tubes for single- and two-phase flow are reviewed within the context of physics of flow, trends in the development of technology, and its laboratory to industrial-scale commercialization. Comparison of the performance of curved tube configurations demonstrates its edge over the conventional motionless mixers, heat exchangers, and reactors. Alongside, their respective advantages and limitations are also highlighted. Further, a compendium of the available correlations for single- and two-phase friction factor and heat- and mass-transfer coefficient in curved tubes has also been presented. Key issues regarding the design parameters governing the performance of the curved tubes for mixing and heat- and mass-transfer that impact the research, development, and scale-up or scale-down of such devices are also analyzed. Emerging trends for the development of a new class of curved tubes, namely, inverters and serpentine and chaotic devices are also presented.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie701760h

Industrial & engineering chemistry research / Paul, Donald R. . Vol. 47 N°10

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