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  Subjects -> ENGINEERING (Total: 1955 journals)
    - CHEMICAL ENGINEERING (153 journals)
    - CIVIL ENGINEERING (148 journals)
    - ELECTRICAL ENGINEERING (82 journals)
    - ENGINEERING (1111 journals)
    - ENGINEERING MECHANICS AND MATERIALS (290 journals)
    - HYDRAULIC ENGINEERING (45 journals)
    - INDUSTRIAL ENGINEERING (52 journals)
    - MECHANICAL ENGINEERING (74 journals)

ENGINEERING (1111 journals)            First | 1 2 3 4 5 6 7 8 | Last

Biomaterials Science     Full-text available via subscription   (Followers: 4)
Biomedical Engineering     Hybrid Journal   (Followers: 9)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 12)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 4)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 14)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 12)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 4)
Biomedical Microdevices     Hybrid Journal   (Followers: 7)
Biomedizinische Technik - Biomedical Engineering     Full-text available via subscription  
Biomicrofluidics     Open Access   (Followers: 2)
BioNanoMaterials     Full-text available via subscription   (Followers: 1)
Biotechnology Progress     Hybrid Journal   (Followers: 20)
Boletin Cientifico Tecnico INIMET     Open Access  
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access  
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 5)
Bubble Science, Engineering & Technology     Hybrid Journal  
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 1)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 3)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Full-text available via subscription   (Followers: 11)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 13)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 3)
Case Studies in Thermal Engineering     Open Access   (Followers: 1)
Catalysis Communications     Hybrid Journal   (Followers: 4)
Catalysis Letters     Hybrid Journal   (Followers: 1)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 4)
Catalysis Science and Technology     Free   (Followers: 4)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 4)
Catalysis Today     Hybrid Journal   (Followers: 6)
CEAS Space Journal     Hybrid Journal   (Followers: 1)
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 2)
Central European Journal of Engineering     Hybrid Journal   (Followers: 1)
CFD Letters     Open Access   (Followers: 1)
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 1)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 1)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 1)
Chinese Journal of Engineering     Open Access  
Chinese Science Bulletin     Open Access  
Ciencia e Ingenieria Neogranadina     Open Access  
Ciencia en su PC     Open Access  
Ciencias Holguin     Open Access  
Cientifica     Open Access  
CIRP Annals - Manufacturing Technology     Full-text available via subscription   (Followers: 10)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 8)
City, Culture and Society     Hybrid Journal   (Followers: 18)
Clay Minerals     Full-text available via subscription   (Followers: 3)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Clinical Science     Full-text available via subscription   (Followers: 3)
Coal Science and Technology     Full-text available via subscription   (Followers: 2)
Coastal Engineering     Hybrid Journal   (Followers: 7)
Coastal Engineering Journal     Hybrid Journal   (Followers: 1)
Coatings     Open Access   (Followers: 1)
Cogent Engineering     Open Access  
Cognitive Computation     Hybrid Journal   (Followers: 3)
Color Research & Application     Hybrid Journal   (Followers: 1)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 5)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 10)
Communications Engineer     Hybrid Journal  
Communications in Information Science and Management Engineering     Open Access   (Followers: 7)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 3)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 8)
Composite Interfaces     Hybrid Journal   (Followers: 3)
Composite Structures     Hybrid Journal   (Followers: 36)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 28)
Composites Part B : Engineering     Hybrid Journal   (Followers: 26)
Composites Science and Technology     Hybrid Journal   (Followers: 34)
Comptes Rendus Mécanique     Full-text available via subscription  
Computation     Open Access   (Followers: 1)
Computational Geosciences     Hybrid Journal   (Followers: 10)
Computational Optimization and Applications     Hybrid Journal   (Followers: 5)
Computational Science and Discovery     Full-text available via subscription  
Computational Water, Energy, and Environmental Engineering     Open Access   (Followers: 2)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 6)
Computer Science and Engineering     Open Access   (Followers: 7)
Computers & Geosciences     Hybrid Journal   (Followers: 6)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 4)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 3)
Computers and Geotechnics     Hybrid Journal   (Followers: 5)
Computing and Visualization in Science     Hybrid Journal   (Followers: 3)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 10)
Conciencia Tecnologica     Open Access   (Followers: 1)
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 3)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 4)
Control Engineering Practice     Hybrid Journal   (Followers: 12)
Control Theory and Informatics     Open Access   (Followers: 4)
Corrosion Science     Hybrid Journal   (Followers: 19)
Corrosion Series     Full-text available via subscription   (Followers: 5)
CT&F Ciencia, Tecnologia y Futuro     Open Access  
Current Applied Physics     Full-text available via subscription   (Followers: 4)
Dams and Reservoirs     Hybrid Journal   (Followers: 3)
Data Handling in Science and Technology     Full-text available via subscription   (Followers: 2)
Design Journal     Full-text available via subscription   (Followers: 14)
Designed Monomers and Polymers     Hybrid Journal   (Followers: 2)
Designs, Codes and Cryptography     Hybrid Journal   (Followers: 4)
Developments in Clay Science     Full-text available via subscription  
Developments in Geotechnical Engineering     Full-text available via subscription   (Followers: 1)

  First | 1 2 3 4 5 6 7 8 | Last

Journal Cover AIChE Journal
   Journal TOC RSS feeds Export to Zotero [20 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0001-1541 - ISSN (Online) 1547-5905
     Published by John Wiley and Sons Homepage  [1604 journals]   [SJR: 0.889]   [H-I: 94]
  • Effect of Particle Size on Flow and Mixing in a Bladed Granular Mixer
    • Authors: Avik Sarkar; Carl R. Wassgren
      Pages: n/a - n/a
      Abstract: A number of studies have modeled flow and mixing of granular materials using the discrete element method (DEM). In an attempt to reduce computational costs, many of these DEM studies model particles larger than the actual particle size without investigating the implications of this assumption. Using DEM, the influence of the modeled particle size on flow and mixing in a bladed granular mixer is studied. The predicted flow microdynamics, including mixing rates, are strongly dependent on the particle diameter. The effect of particle size on macroscopic advective flow also is significant, particularly for dilute flow regions. These results suggest that the influence of particle size needs to be taken into consideration when using larger particles in DEM mixing simulations. To guide scale‐up efforts, particle‐size‐based scaling relationships for several key flow measurements are presented. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-19T03:07:17.654639-05:
      DOI: 10.1002/aic.14629
       
  • Engineering Acidithiobacillus ferrooxidans growth media for enhanced
           electrochemical processing
    • Authors: Xiaozheng Li; Roel Mercado, Sarah Berlinger, Scott Banta, Alan C. West
      Pages: n/a - n/a
      Abstract: The chemolithoautotroph A. ferrooxidans has been proposed as a potential electrofuel synthetic platform, and its growth medium is engineered to increase its conductivity and energy density, thereby improving viability of the process. The ion V3+ is used as an indirect electron supplier together with Fe2+ to grow A. ferrooxidans to increase the energy density of the medium, overcoming the Fe3+ solubility limit. A medium containing 10 mM Fe2+ with 60 mM V3+ was able to support cell growth to a final cell concentration very similar to medium of 70 mM Fe2+. Integration of the biological process with an electrochemical reactor requires, for economical operation, a medium with high ionic conductivity. This is achieved by the addition of salt, and Mg2+ was found to be least toxic to the bacterium. A concentration of 500 mM Mg2+ is optimal considering constraints on bacterial growth and electrochemistry. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-17T03:48:54.727058-05:
      DOI: 10.1002/aic.14628
       
  • A General and Robust Approach for Defining and Solving Microkinetic
           Catalytic Systems
    • Authors: Gabriel S. Gusmão; Phillip Christopher
      Pages: n/a - n/a
      Abstract: Recent approaches for the rational design of heterogeneous catalysts have relied on first‐principles based microkinetic modeling to efficiently screen large phase spaces of catalytic materials for optimal activity and selectivity. Microkinetic modeling allows the calculation of catalytic rate and selectivity under a given set of conditions without a priori assumptions of rate or selectivity controlling steps by simultaneously solving non‐linear algebraic equations comprising species mass balances bound by the pseudo steady state approximation. We introduce a general approach to define and solve microkinetic systems that relies solely on its stoichiometric matrix and kinetic parameters of considered reaction steps. Our approach relies on linearization of the microkinetic system, enabling analytical calculation of system derivatives for use in quasi‐Newton solution schemes that exhibit excellent robustness and efficiency with minimal dependence on initial conditions. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-17T02:00:55.601826-05:
      DOI: 10.1002/aic.14627
       
  • Introducing vapor recompression mechanism in heat integrated distillation
           column (HIDiC): Impact of internal energy driven intermediate and bottom
           reboiler
    • Authors: Bandaru Kiran; Amiya K. Jana
      Pages: n/a - n/a
      Abstract: This work proposes a novel combination of internally heat integrated distillation column (HIDiC) and vapor recompression column (VRC) with intermediate reboiler (IR). Supplying heat at the highest temperature point (i.e., column bottom) of the VRC scheme is not thermodynamically favorable and therefore, we aim to install the IR for better distribution of heat along the column length, thereby reducing the compressor work. Introducing IR in the combined HIDiC‐VRC system, the present work formulates an open‐loop variable manipulation policy to evaluate the comparative impact of internal and external heat sources on bottom liquid reboiling. With internal energy driven bottom reboiler, we further investigate the hybrid HIDiC‐VRCIR column with proposing the two modes of compressor arrangement, namely parallel and series. Finally, a multicomponent distillation system is exampled to show the promising potential of the proposed HIDiC‐VRCIR configurations in improving the energetic and economic performance over the HIDiC‐alone and HIDiC‐VRC schemes with reference to a conventional standalone column. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-16T11:20:40.502851-05:
      DOI: 10.1002/aic.14620
       
  • 1H‐ and 13C‐NMR Spectroscopic Study of Chemical Equilibria in
           the System Acetaldehyde + Water
    • Authors: Andreas Scheithauer; Thomas Grützner, Christiaan Rijksen, Daniel Zollinger, Erik von Harbou, Werner R. Thiel, Hans Hasse
      Pages: n/a - n/a
      Abstract: Acetaldehyde is an important intermediate in the chemical industry and often used in mixtures with water. These mixtures are reactive multicomponent systems, as acetaldehyde forms oligomers with water. Quantitative studies of the resulting speciation are scarce in the literature and limited to the formation of the smallest oligomer, ethane‐1,1‐diol. Therefore, in the present work, a comprehensive study of chemical equilibria in mixtures of acetaldehyde and water was carried out by quantitative 1H‐ and 13C‐NMR spectroscopy. The study covers temperatures between 275 and 338 K and overall acetaldehyde mole fractions between about 0.05 and 0.95 mol/mol. The peak assignment is given for both the 1H‐ and 13C‐NMR spectra. From the speciation data, obtained from the peak area fractions, numbers for the chemical equilibrium constants of the oligomer formation are obtained and a correlation is presented. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-16T04:06:19.379465-05:
      DOI: 10.1002/aic.14623
       
  • Kinetics of formation of oil‐in‐water emulsions using in situ
           rheo‐optical measurements
    • Authors: Rudy Covis; Christophe Baravian, Emmanuelle Marie, Alain Durand
      Pages: n/a - n/a
      Abstract: The kinetics of mechanical emulsification in vane geometry was investigated using an original rheo‐optic device. Hexadecane‐in‐water micronic emulsions were prepared using a nonionic polymeric surfactant (Brij700®) as stabilizer. The viscosity of aqueous phase was adjusted using a commercial viscosifier (Emkarox®) which ensured Newtonian behavior to the continuous phase. The influences of two variables (rotational speed and oil volume fraction) on the kinetics of droplet fragmentation were examined in detail. Rotational speed was varied between 50 and 100 rad.s‐1 and had a strong effect on the kinetics of emulsion formation which was discussed on the basis of droplet fragmentation by shear forces. On the contrary, oil volume fraction (between 20 and 60 % v/v) showed no marked effect, which appeared as an important result for scale up considerations. A theoretical description of fragmentation mechanism was proposed and experimental results were compared to calculated values. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-16T03:58:15.289281-05:
      DOI: 10.1002/aic.14626
       
  • The generation of hydroxyl radicals by hydrogen peroxide decomposition on
           FeOCl/SBA‐15 catalysts for phenol degradation
    • Authors: Xue‐jing Yang; Peng‐fei Tian, Xiao‐man Zhang, Xin Yu, Ting Wu, Jing Xu, Yi‐fan Han
      Pages: n/a - n/a
      Abstract: Iron oxychloride (FeOCl) supported on mesoporous silica (SBA‐15), as a Fenton‐like solid catalyst for phenol degradation, showed supreme activity for production of hydroxyl radical (HO·) by H2O2 decomposition, and the generation capacity was comparable to the conventional Fenton reagent (Fe2++H2O2). The structure of FeOCl was characterized with multi spectroscopies. The generation of HO· species during the reaction was detected using 5,5‐ dimethyl‐1‐pyrroline N‐ oxide (DMPO) trapped electron paramagnetic resonance (EPR). Furthermore, the kinetics in detail was driven for the creation and diffusion of HO· by H2O2 decomposition over FeOCl, which follows a first‐order rate through a two‐step reaction. With the combination of the catalyst structure and kinetic parameters, the plausible mechanism for H2O2 decomposition during the oxidative degradation of phenol was rationalized. As a Fenton‐like solid catalyst, FeOCl/SBA‐15 is a promising alternative for the removal of low‐level organic contaminates from water. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-12T12:13:28.25-05:00
      DOI: 10.1002/aic.14625
       
  • Continuum approximation of large reaction mixtures in reactors with
           backmixing
    • Authors: Teh C. Ho; Benjamin S. White
      Pages: n/a - n/a
      Abstract: The growing need to produce ultra‐clean fuels from hydrocarbon mixtures such as petroleum fractions and residues has put increasing pressure on refiners to achieve deep conversions. It is imperative to be able to predict the behavior of such mixtures at high conversions as functions of their properties and reactor type. To this end, treating the reaction mixture as a continuum greatly simplifies the analysis and modeling of the conversion process. However, the continuum approximation can become invalid at very high conversions. Previously, we examined the validity of the approximation for various reactions in plug flow reactors. The present work develops validity conditions for first‐order reaction mixtures in reactors with different mixing intensities. In general, backmixing widens the range of validity. In certain cases the continuum approximation is valid at arbitrarily high conversions. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-11T09:47:24.673548-05:
      DOI: 10.1002/aic.14624
       
  • Quality assurance of Chinese herbal medicines: Procedure for
           multiple‐herb extraction
    • Authors: Yeuk T. Lau; Na Chen, David T. W. Lau, Kam M. Ko, Ka M. Ng, Ping C. Leung, Christianto Wibowo
      Pages: n/a - n/a
      Abstract: A quality assurance (QA) procedure for multiple‐herb extraction, which takes into account the existence of common chemical markers and multiple‐herb‐extraction effects, has been developed for producing Chinese herbal medicines (CHMs) of consistent quality. The experimental method for determining related correlation function of the multiple‐herb‐extraction effect was designed. A systematic solution strategy was also developed to appropriately decompose the multiple‐herb extraction system into several subsystems for obtaining solution(s) and determining the overall behavior of the system. An example of quality assurance of Danshen‐Gegen (DG) decoction was used to demonstrate the QA procedure. An H9c2 cell assay was used to test the efficacy of consistent quality DG decoctions prepared by different herb combinations with different material costs of herbs. It was observed that a multiple‐herb‐extraction effect was present in the aqueous extraction of Danshensu and this effect was depended on the extraction solvent. The possible mechanism of this multiple‐herb‐extraction effect in the aqueous DG extraction was speculated to be the change of initial pH value of the aqueous extraction solvent by an unknown component from Gegen. The experimental chemical marker concentrations fell within ±10% of the specified chemical marker compositions by using the amount of herb from each herb class as predicted by the QA model. Furthermore, an H9c2 cell assay was used to test the efficacy of three consistent quality DG extracts, which were produced by different herb combinations with different material costs of herbs. The results showed that the three DG extracts provided consistent biological efficacy against menadione‐induced toxicity. This study extended a recently developed QA procedure of single‐herb extraction to multiple‐herb extraction. It provides a solution of quality assurance in extraction, which is one of the most important unresolved problems in the modernization of traditional Chinese medicines. With this modified model and the companion experiments, the amount of herbs needed from different quality classes to produce a multiple‐herb formula CHM product decoction with consistent quality can be exactly determined. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-11T08:34:42.636755-05:
      DOI: 10.1002/aic.14619
       
  • Multi‐scale modeling of protein adsorption and transport in
           macroporous and polymer‐grafted ion exchangers
    • Authors: Joseph E. Basconi; Giorgio Carta, Michael R. Shirts
      Pages: n/a - n/a
      Abstract: A multi‐scale model is presented to elucidate protein adsorption and transport behaviors in ion‐exchange chromatography (IEC) adsorbent particles that have either an open pore structure or charged dextran polymers grafted into the pores. Molecular dynamics (MD) simulation is used to determine protein diffusion and partitioning in different regions of the adsorbent pore, and these outputs are used in numerical simulations of mass transfer to determine the intraparticle protein concentration profile and the mass transfer rate. Modeling results indicate that, consistent with experimental observations, protein transport can be faster in the polymer‐grafted material compared to the open pore case. This occurs when favorable partitioning of protein into the polymer‐filled pore space is combined with relatively high protein mobility within this region. The modeling approach presented here should be applicable to proteins and adsorbents with different properties, and could help elucidate the factors that control adsorption and transport in various IEC systems. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-11T08:30:19.56178-05:0
      DOI: 10.1002/aic.14621
       
  • Number density of turbulent vortices in the entire energy spectrum
    • Authors: Farideh Ghasempour; Ronnie Andersson, Donald J. Bergstrom, Bengt Andersson
      Pages: n/a - n/a
      Abstract: In coalescence and break‐up modeling, vortex number density and size distributions of turbulent vortices are required in order to calculate the rate of interaction between continuous and dispersed phases. Existing number density models are only valid for the inertial subrange of the energy spectrum and no model of the vortex number density, valid for the entire energy spectrum, is available. In the present study, the number density of the turbulent vortices were studied and modeled for the entire energy spectrum including the dissipative, inertial and energy containing subranges. It was observed that the new number density model depends on vortex size, local turbulent kinetic energy and dissipation rate. Moreover, the new number density model was validated by the number density distributions quantified in a turbulent pipe flow. The turbulent vortices of the pipe were identified and labeled using a vortex‐tracking algorithm that was developed recently by the authors. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-11T08:26:23.384187-05:
      DOI: 10.1002/aic.14622
       
  • Phenomenological model‐based analysis of lithium batteries.
           Discharge, charge, relaxation times studies and cycles analysis
    • Authors: E.R. Henquín; P.A. Aguirre
      Pages: n/a - n/a
      Abstract: This work addresses the operation of lithium ion batteries in discharge and charge processes. A simple phenomenological model is developed in order to predict all variables values. A set of algebraic and differential equations is derived taking into account salt and Lithium balances in electrodes, in the separator, and in particles. Balances are developed for finite volumes and appropriate average values of several variables such as concentrations, current densities, and electrochemical reaction rates are introduced. Definitions of current densities as volume fraction functions are critical issues in the computations. Experimental values taken from the literature for discharge processes are predicted very accurately. Constant salt concentration in the separator can be assumed and consequently the model can be analytically solved. Charge and discharge times, initial cell capacity, lost capacity and relaxation times are easily estimated from simple equations and cell parameters. The limiting processes taking place during cell discharge can be determined. Energy efficiency and capacity usage are quantified for cycles. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-08T07:20:21.635278-05:
      DOI: 10.1002/aic.14618
       
  • Experimental study of oscillation behaviors in confined impinging jets
           reactor under excitation
    • Authors: Wei‐Feng Li; Wen‐Wei Qian, Guang‐Suo Yu, Hai‐Feng Liu, Fu‐Chen Wang
      Pages: n/a - n/a
      Abstract: Dynamic behaviors in a three‐dimensional confined impinging jets reactor (CIJR) under excitation were experimentally studied by a flow visualization technique at 75≤Re≤150. The effects of inlet Reynolds numbers (Re), excitation frequencies and excitation amplitudes on the oscillation behaviors in CIJR have been investigated by a Particle Image Velocimetry (PIV) and a high‐speed camera. Results indicate that the excitation in the inflow of the opposed jets can induce periodic oscillation of the impingement plane along the axis, whose oscillation frequency is equal to the excitation frequency. At Re≤100, the induced axial oscillation can further cause a deflective oscillation with a frequency nearly equal to the excitation, and the scale of the vortex in the impingement plane is well regulated by the excitation frequency. At Re=150, the excitation of amplitude less than 20% has insignificant effect on the deflective oscillation existing in CIJR. A semiempirical formula has been proposed to predict the oscillation amplitude of the impingement plane in CIJR under excitation. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-05T04:38:52.435156-05:
      DOI: 10.1002/aic.14617
       
  • Synthesis of sustainable integrated biorefinery via reaction pathway
           synthesis: Economic, incremental enviromental burden and energy assessment
           with multi‐objective optimization
    • Authors: Viknesh Andiappan; Andy S. Y. Ko, Veronica W. S. Lau, Lik Yin Ng, Rex T. L. Ng, Nishanth G. Chemmangattuvalappil, Denny K. S. Ng
      Pages: n/a - n/a
      Abstract: With the increasing attention toward sustainable development, biomass has been identified as one of the most promising sources of renewable energy. In order to convert biomass into value‐added products and energy, an integrated processing facility, known as an integrated biorefinery is needed. To date, various biomass conversion systems such as gasification, pyrolysis, anaerobic digestion, fermentation, etc. are well established. Due to a large number of technologies available, systematic synthesis of a sustainable integrated biorefinery which simultaneously considers economic performance, environmental impact and energy requirement is a challenging task. In order to address this issue, multi‐objective optimization approaches are used in this work to synthesize a sustainable integrated biorefinery. In addition, a novel approach (incremental environmental burden) to assess the environmental impact for an integrated biorefinery is presented. To illustrate the proposed approach, a palm‐based biomass case study is solved. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-05T04:31:36.584805-05:
      DOI: 10.1002/aic.14616
       
  • Evolving trends in chemical engineering education
    • Authors: Arvind Varma; Ignacio Grossmann
      Pages: n/a - n/a
      PubDate: 2014-09-04T07:36:27.981856-05:
      DOI: 10.1002/aic.14613
       
  • Dynamic CO2 adsorption performance of internally cooled silica supported
           poly(ethylenimine) hollow fiber sorbents
    • Authors: Yanfang Fan; Ying Labreche, Ryan P. Lively, Christopher W. Jones, William J. Koros
      Pages: n/a - n/a
      Abstract: The dynamic adsorption behavior of CO2 under both non‐isothermal and nearly isothermal conditions in silica supported poly(ethylenimine) (PEI) hollow fiber sorbents (Torlon®‐S‐PEI) is investigated in a rapid temperature swing adsorption (RTSA) process. A maximum CO2 breakthrough capacity of 1.33 mmol/g‐fiber (2.66 mmol/g‐silica) is observed when the fibers are actively cooled by flowing cooling water in the fiber bores. Under dry CO2 adsorption conditions, heat released from the CO2‐amine interaction increases the CO2 breakthrough capacity by reducing the severity of the diffusion resistance in the supported PEI. This internal resistance can also be alleviated by prehydrating the fiber sorbent with a humid N2 feed. The CO2 breakthrough capacity of prehydrated fibers is adversely affected by the release of the adsorption enthalpy (unlike the dry fibers); however, active cooling of the fiber results in a constant CO2 breakthrough capacity even at high CO2 delivery rates (i.e., high adsorption enthalpy delivery rates). In full RTSA cycles, a purity of 50% CO2 is achieved and the adsorption enthalpy recovery rate can reach ˜ 72%. Studies on the cyclic stability of uncooled fiber sorbents in the presence of SO2 and NO contaminants indicate that exposure to NO at 200 ppm over 120 cycles does not lead to a significant degradation of the sorbents, but SO2 exposure at a similar high concentration of 200 ppm causes 60% loss in CO2 breakthrough capacity after 120 cycles. A simple amine re‐infusion technique is successfully demonstrated to recover the adsorption capacity in poisoned fiber sorbents after deactivation by exposure to impurities such SO2. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-04T03:36:31.449898-05:
      DOI: 10.1002/aic.14615
       
  • Experimental study on the reaction rate of a second‐order chemical
           reaction in a planar liquid jet
    • Authors: T. Watanabe; Y. Sakai, K. Nagata, O. Terashima
      Pages: n/a - n/a
      Abstract: Instantaneous concentrations of reactive species are simultaneously measured in a planar liquid jet with a second‐order chemical reaction A + B → R in order to investigate the statistical properties of the chemical reaction rate and the validity of models which have been proposed for concentration correlation. The jet flow contains the reactant A and the ambient flow contains the reactant B. The results show that the concentration correlation of the reactants makes a negative contribution to the mean reaction rate, and this contribution is important in the downstream direction. The concentration correlation changes owing to the chemical reaction. The effects of the chemical reaction on the concentration correlation change with the flow location and the Damköhler number. The concentration correlation predicted by the Toor’s model and the three‐environment (3E) model are compared with the experimental results. The results show that these models fail to accurately estimate the concentration correlation. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-04T03:25:43.51534-05:0
      DOI: 10.1002/aic.14610
       
  • Facile fabrication of spherical architecture of Ni/Al layered double
           hydroxide based on in situ transformation mechanism
    • Authors: Fazhi Zhang; Yue Zhang, Caili Yue, Rong Zhang, Yanmin Yang
      Pages: n/a - n/a
      Abstract: Spherical architectures of nickel‐aluminum layered double hydroxide (NiAl‐LDH) with hydrotalcite‐like nanoflakes as building blocks were facilely fabricated by precipitation reaction in aqueous solution without any surfactants and organic solvents. Growth of such unique structure undergoes preorganization of primary nanospheres of colloidal amorphous aluminum hydroxide (AAH) in solution, followed by nucleation and crystallizaion of LDH from exterior to interior of AAH spheres by an in situ transformation mechanism. The structure and morphology of LDH spheres depend on both starting raw materials and synthetic parameters including reaction time, reaction temperature and aqueous ammonia dosage. NiAl‐LDH sphere as positive electrode material delivers improved rechargeable and discharge‐capacity, with the highest discharge capacity of 173 mAh g‐1 at a current density of 30 mA g‐1 within a potential range from ‐0.1 to 0.45 V in 10 mol L‐1 KOH solution, due to the faster diffusion processes in the spherical architecture than the powder sample. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-04T03:24:45.291152-05:
      DOI: 10.1002/aic.14609
       
  • Wet dispersion mechanism of fine aggregates in multiphase flow with solid
           beads under simple shear
    • Authors: Daisuke Nishiura; Atsuko Shimosaka, Hide Sakaguchi
      Pages: n/a - n/a
      Abstract: Clarifying the disintegration mechanism of aggregates in multiphase fluid flow coupled with beads and particulates is important for the optimum design of a wet dispersion process using a stirred media mill. Thus, we develop a numerical method for simulating multiphase flow with beads and particulates using a discrete element method and computational fluid dynamics, and we employ the four‐way coupling simulation to study the fluid‐bead‐particulate‐coupled phenomenon that occurs in a simple shear box. The results show that the dominant force causing aggregate disintegration is the fluid force, rather than the bead contact force, because aggregates rarely collide with beads, contact force of which is too small to disintegrate aggregates. Furthermore, aggregates with strong aggregation force are effectively disintegrated by the fluid flow with a dominant high pure‐shear rate induced near the bead surfaces by the expansive force, rather than the compressive force. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-04T03:24:31.247714-05:
      DOI: 10.1002/aic.14614
       
  • Natural Giesekus fluids: Shear and extensional behavior of food gum
           solutions in the semi‐dilute regime
    • Authors: M.D. Torres; B. Hallmark, L. Hilliou, D.I. Wilson
      Pages: n/a - n/a
      Abstract: The shear and extensional behavior of two aqueous gum solutions, namely (i) 1‐20 g/L guar gum 1and (ii) κ/ι‐hybrid carrageenan solutions (5‐20 g/L), are shown to exhibit Giesekus‐fluid behaviour when in the semi‐dilute regime. In this regime a common set of Giesekus fluid parameters described both shear and extensional behavior. A new analytical result describing the extension of a Giesekus fluid in the filament stretching geometry is presented. This also gave reasonable predictions of the Trouton ratio. Higher concentration guar solutions, in the entangled regime, yielded different Giesekus fluid parameters for extension to those for simple shear. The extensional data for all concentrations of both gums collapsed to a common functional form, similar to that reported for cake batters2; the limits of the new filament thinning expression provide insight into this behaviour. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-04T03:05:38.926095-05:
      DOI: 10.1002/aic.14611
       
  • Influence of unsteady mass transfer on dynamics of rising and sinking
           droplet in water: Experimental and CFD study
    • Authors: Abhijit Rao; Rupesh K Reddy, Kalliat T Valsaraj, Krishnaswamy Nandakumar, Shashank Pandey, C. L. Wu
      Pages: n/a - n/a
      Abstract: Experimental and numerical investigations were conducted to study the effect of unsteady mass transfer on the dynamics of an organic droplet released in quiescent water. The situation is important and relevant to deep sea oil spill scenario. The droplet contains two components, one is heavier (immiscible) than water and other is lighter (miscible). When released, with an initial mixture density (890‐975 kg/m3) lower than that of surrounding water, droplet rises in the column. The mass transfer of lighter solute component into water causes the droplet density to increase and droplet sinks when the density exceeds that of water. A mass transfer correlation accounting for the loss of the solute, based on Reynolds, Grashoff and Schmidt numbers was developed. A 2D axisymmetric CFD model accounting for species transport was developed to emulate the experimental observations. The study also helped in identifying dominant mass transfer mechanisms during different stages of droplet motion. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-04T02:56:12.35339-05:0
      DOI: 10.1002/aic.14612
       
  • Orbitally Shaken Bioreactors ‐ Viscosity effects on flow
           characteristics
    • Authors: Andrea Ducci; Weheliye Hashi Weheliye
      Pages: n/a - n/a
      Abstract: Phase resolved PIV measurements were carried out to assess the flow dynamics occurring in orbitally shaken bioreactors of cylindrical geometry when working fluids of increasing viscosity are considered. Study of the phase‐resolved flow characteristics allowed to built a Re‐Fr map, where four quadrants associated to different flow regimes are identified: in‐phase toroidal vortex (low Fr, high Re), out‐of‐phase precessional vortex (high Fr, high Re), in‐phase single vortex (low Fr, low Re), out‐of‐phase counter‐rotating toroidal vortex (high Fr, low Re). Turbulence levels are found to be significant only in the top right quadrant (high Fr, low Re) and scaling of the turbulent kinetic energy obtained with fluid of varying viscosity is obtained by employing the ratio of the operating Froude number to the critical Froude number associated to the mean flow transition, Fr/Frc. Estimates of the mean flow strain deformation as well as of the flow dissipative scale are provided, while a comparison is made between the flow circulation times obtained for different regimes. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-01T07:25:40.810259-05:
      DOI: 10.1002/aic.14608
       
  • Enhanced performance of supercritical fluid foaming of natural‐based
           polymers by deep eutectic solvents
    • Authors: Marta Martins; Ivo Aroso, Rita Craveiro, Rui L. Reis, Alexandre Paiva, Ana Rita C. Duarte
      Pages: n/a - n/a
      Abstract: Natural deep eutectic solvents are defined as a mixture of two or more solid or liquid components, which at a particular composition present a high melting point depression becoming liquids at room temperature. NADES are constituted by natural molecules and fully represent the green chemistry principles. For these reasons the authors believe that the submitted manuscript is a highly valuable contribution to the field of green chemistry and chemical engineering. In this work we reveal for the first time the possibility to use NADES as enhancers of supercritical fluid technology. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-30T03:34:16.650527-05:
      DOI: 10.1002/aic.14607
       
  • UNIFAC model for ionic liquid‐CO (H2) systems: An experimental and
           modeling study on gas solubility
    • Authors: Zhigang Lei; Chengna Dai, Qian Yang, Jiqin Zhu, Biaohua Chen
      Pages: n/a - n/a
      Abstract: The UNIFAC model for ionic liquids (ILs) has become notably popular because of its simplicity and availability via modern process simulation softwares. In this work, new group binary interaction parameters (αmn and αnm) between CO (H2) and IL groups were obtained by correlating the solubility data in pure ILs at high temperatures (above 273.2 K) collected from the literature. We also measured the solubility of CO in [BMIM]+[BF4]‐, [OMIM]+[BF4]‐, [OMIM]+[Tf2N]‐ and their mixtures, as well as that of H2 in [EMIM]+[BF4]‐, [BMIM]+[BF4]‐, [OMIM]+[Tf2N]‐ and their mixtures, at temperatures from 243.2 to 333.2 K and pressures up to 6.0 MPa. The UNIFAC model was observed to well predict the solubility in pure and mixed ILs at both high (above 273.2 K) and low (below 273.2 K) temperatures. Moreover, the selectivity of CO (or H2) to CO2 in ILs increases with decreasing temperature, indicating that low temperatures favor for gas separation. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-28T02:12:45.692518-05:
      DOI: 10.1002/aic.14606
       
  • Magnetic nanowire synthesis: A Chemical Engineering approach
    • Authors: Ouar Nassima; Farhat Samir, Hinkov Ivaylo, Wang Guillaume, Ricolleau Christian, Mercone Silvana, Zighem Fatih, Schoenstein Frédéric, Jouini Noureddine
      Pages: n/a - n/a
      Abstract: Bimetallic one‐dimensional (1‐D) cobalt‐nickel magnetic nanowires capped on both sides with conical heads were synthesized using the polyol process. Then, the process was scaled up to produce magnetic nanowires in sample aliquots of ˜20 grams. The scale‐up strategy involved improving the mixing reagents using either axial or radial mixing configurations and was experimentally validated by comparing the structural and magnetic properties of the resulting nanowires. The results indicated a connection between the flow patterns and the size and shape of the nanowires. When a Rushton turbine was used, shorter nanowires with unconventional small heads were obtained. Because the demagnetizing field is strongly localized near or inside these heads, the coercive field was enhanced nearly twofold. These results were confirmed by micromagnetic simulations using isolated nanowires. In addition, the development of flow patterns at the small and pilot scales was predicted and compared using three‐dimensional (3‐D) turbulent computational fluid dynamics simulations. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-28T02:06:40.893947-05:
      DOI: 10.1002/aic.14605
       
  • Modeling of turbulent cross flow microfiltration of pomegranate juice
           using hollow fiber membranes
    • Authors: Sourav Mondal; Sirshendu De, Alfredo Cassano, Franco Tasselli
      Pages: n/a - n/a
      Abstract: A mathematical analysis of the permeate flux decline during microfiltration of fruit juice with hollow fibers under turbulent flow is presented. Impact of complex fluid flow phenomena on mass transfer is analyzed. A comprehensive analytical model for developing concentration boundary layer was formulated from first principles using integral method. Attempts to model the system considering constant boundary layer thickness (film theory) is inaccurate for developing boundary layer. Gel resistance parameter depending on juice characteristics has significant impact on permeate flux. Specific gel layer concentration has insignificant effect on system performance under total recycle mode but important for batch mode. Theoretical results were compared with experiments in clarification of pomegranate juice with poly(ether ether ketone) and polysulfone hollow fiber membranes. The physical parameters of complex mixture were evaluated by optimizing of the flux profiles in total recycle mode of operation and were successfully applied for prediction of batch mode performance. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-27T14:31:54.531115-05:
      DOI: 10.1002/aic.14594
       
  • An integrated qualitative and quantitative modeling framework for
           computer‐assisted HAZOP studies
    • Authors: Jing Wu; Laibin Zhang, Jinqiu Hu, Morten Lind, Xinxin Zhang, Sten Bay Jørgensen, Gürkan Sin, Niels Jensen
      Pages: n/a - n/a
      Abstract: The article proposes a novel practical framework for computer‐assisted hazard and operability (HAZOP) that integrates qualitative reasoning about system function with quantitative dynamic simulation in order to facilitate detailed specific HAZOP analysis. The practical framework is demonstrated and validated on a case study concerning a three‐phase separation process. The multilevel flow modeling (MFM) methodology is used to represent the plant goals and functions. First, means‐end analysis is used to identify and formulate the intention of the process design in terms of components, functions, objectives, and goals on different abstraction levels. Based on this abstraction, qualitative functional models are constructed for the process. Next MFM‐specified causal rules are extended with systems specific features to enable proper reasoning. Finally, systematic HAZOP analysis is performed to identify safety critical operations, its causes and consequences. The outcome is a qualitative hazard analysis of selected process deviations from normal operations and their consequences as input to a traditional HAZOP table. The list of unacceptable high risk deviations identified by the qualitative HAZOP analysis is used as input for rigorous analysis and evaluation by the quantitative analysis part of the framework. To this end, dynamic first‐principles modeling is used to simulate the system behavior and thereby complement the results of the qualitative analysis part. The practical framework for computer‐assisted HAZOP studies introduced in this article allows the HAZOP team to devote more attention to high consequence hazards. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-27T14:17:12.861552-05:
      DOI: 10.1002/aic.14593
       
  • Numerical simulation of rapid expansion of supercritical carbon dioxide
    • Authors: Jiewei Liu; Minh Do‐Quang, Gustav Amberg
      Pages: n/a - n/a
      Abstract: This paper investigates axisymmetric rapid expansion of supercritical carbon dioxide. The extended generalized Bender equation of state is used to give a good description of the fluids over a wide range of pressure and temperature conditions. The location of Mach disks are analyzed and compared with an experimental correlation for the case where there is no plate positioned in front of the nozzle exit. It is found that the disagreement between our numerical results and the experimental formula is very small when the pressure ratio is small, and increases as the pressure ratio increases. It is also found that with different equations of state, the predicted positions of Mach disks do not differ a lot, but the temperature profiles in the chamber differ a lot. This paper has also studied the case where there is a plate positioned in front of the nozzle exit. A universal similarity solution is obtained. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-27T10:58:59.874008-05:
      DOI: 10.1002/aic.14603
       
  • A novel fluorinated polymeric product for photo‐reversibly
           switchable hydrophobic surface
    • Authors: Yin‐Ning Zhou; Jin‐Jin Li, Qing Zhang, Zheng‐Hong Luo
      Pages: n/a - n/a
      Abstract: In this work, a new chemical product, i.e. photo‐reversibly switchable hydrophobic surface coating, was synthesized by atom transfer radical polymerization (ATRP) and graft‐from method based on molecular design. Focusing on the strategy of new product development from the chemical product engineering perspective, the product characterization, switching mechanism analysis, performance evaluation and model interpretation were carried out to confirm the new product manufacture and to ensure the product application with a following aging test. The results show that the product enables surfaces to have reversibly switchable wettability and excellent stability after a month‐long test with eight irradiation cycles. Additionally, the wetting behavior of silicon surface can be tuned between hydrophilicity and hydrophobicity based on blank sample using the surface engineering technique (decorated with functional film and surface roughening). The product presented here can be utilized for constructing a hydrophobic surface with photo‐induced controllable wettability in moisture‐resistance, and it also offers a new technique for the manipulation of liquids in microfluidic devices. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-27T09:37:47.887919-05:
      DOI: 10.1002/aic.14602
       
  • Cake properties of nano‐colloid evaluated by variable pressure
           filtration associated with reduction in cake surface area
    • Authors: Eiji Iritani; Nobuyuki Katagiri, Ryota Nakajima, Kuo‐Jen Hwang, Tung‐Wen Cheng
      Pages: n/a - n/a
      Abstract: A potential method has been developed for evaluating simultaneously both the average specific resistance and average porosity of the filter cake formed in unstirred dead‐end ultrafiltration of nano‐colloids such as BSA solution and silica sol. The method consists of variable pressure filtration followed by constant pressure filtration. The relation between the average specific cake resistance and the pressure drop across the cake was determined from the evolution of the filtration rate with time in the course of the variable pressure filtration period, based on the compressible cake filtration model. The average porosity was evaluated from the significant flux decline caused by a sudden reduction in the cake surface area in the middle of the constant pressure filtration period. The pressure dependences of both the average specific cake resistance and average cake porosity were obtained from only two runs which differed from each other in the pressure profiles. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-27T09:36:26.606692-05:
      DOI: 10.1002/aic.14601
       
  • Hybrid FSC Membrane for CO2 Removal from Natural Gas: Experimental,
           Process Simulation and Economic Feasibility Analysis
    • Authors: Xuezhong He; Taek‐Joong Kim, May‐Britt Hägg
      Pages: n/a - n/a
      Abstract: The novel fixed‐site‐carrier (FSC) membranes were prepared by coating carbon nanotubes (CNTs) reinforced polyvinylamine (PVAm)/polyvinylalcohol (PVA) selective layer on top of ultrafiltration polysulfone support. Small pilot‐scale modules with membrane area of 110‐330cm2 were tested with high pressure permeation rig. The prepared hybrid FSC membranes show high CO2 permeance of 0.084~0.218 m3 (STP) / (m2.h.bar) with CO2/ CH4 selectivity of 17.9‐34.7 at different feed pressures up to 40 bar for a 10% CO2 feed gas. Operating parameters of feed pressure, flow rate and CO2 concentration were found to significantly influence membrane performance. HYSYS simulation integrated with ChemBrane and cost estimation was conducted to evaluate techno‐economic feasibility of a membrane process for natural gas sweetening. Simulation results indicated that the developed FSC membranes could be a promising candidate for CO2 removal from low CO2 concentration (10%) natural gases with a low natural gas sweetening cost of 5.73E‐3 $ / Nm3 sweet NG produced. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-27T02:01:53.588201-05:
      DOI: 10.1002/aic.14600
       
  • CFD Modeling of LPG Vessels under Fire Exposure Conditions
    • Authors: Arianna D’aulisa; Gabriele Landucci, Alessandro Tugnoli, Valerio Cozzani, Albrecht Michael Birk
      Pages: n/a - n/a
      Abstract: Fire exposure of tanks used for the storage and transportation of liquefied gases under pressure may cause complex heat and mass transfer phenomena that may contribute to compromise the integrity of the vessels in accident scenarios. Heat transfer through vessel lading results in the heat‐up of the internal fluid and the increase of vessel internal pressure. However, local temperature gradients in the liquid phase cause liquid stratification phenomena that result in a more rapid vaporization and pressure build‐up in the liquid phase. These fundamental phenomena were analyzed by a Computational Fluid Dynamic (CFD) model. The model was specifically focused on the early steps of vessel heat‐up, when liquid stratification plays a relevant role in determining the vessel internal pressure. A two‐dimensional transient simulation was set up using ANSYS FLUENT in order to predict the evolution of the liquid and vapor phases during the tank heat up. The model was validated against available large scale experimental data available for liquefied petroleum gas (LPG) vessels exposed to hydrocarbon fires, and was applied to case studies derived from recent accidental events in order to assess the expected time of pressure build‐up in different fire scenarios. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-27T01:54:41.674435-05:
      DOI: 10.1002/aic.14599
       
  • Boundary conditions for collisional granular flows of frictional and
           rotational particles at flat walls
    • Authors: Yunhua Zhao; Yingjie Zhong, Yurong He, H. Inaki Schlaberg
      Pages: n/a - n/a
      Abstract: Collisions between frictional particles and flat walls are determined using Coulomb friction and both tangential and normal restitution, and pseudothermal states of particles are described by both the translational and rotational granular temperatures. Then, new models for the stresses and the fluxes of fluctuation energy for the collisional granular flows at the walls are derived. These new models are tested and compared with the literature data and models. The ratio of rotational to translational granular temperatures is shown to be crucial on accurately predicting the shear stress and energy flux and is dependent on the normalized slip velocity as well as the collisional parameters. Using a theoretical but constant value for this ratio, predictions by the new models could still agree better with the literature data than those by the previous models. Finally, boundary conditions are developed to be used within the framework of kinetic theory of granular flow. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-25T21:08:42.042732-05:
      DOI: 10.1002/aic.14596
       
  • Measurement of particle concentration in a Wurster fluidized bed by
           electrical capacitance tomography sensors
    • Authors: Ruihuan Ge; Jiamin Ye, Haigang Wang, Wuqiang Yang
      Pages: n/a - n/a
      Abstract: It is essential to measure and monitor the particle flow characteristics in a Wurster fluidized bed to understand and optimize the coating processes. In this article, two electrical capacitance tomography (ECT) sensors are used to measure the particle concentration in different regions in a Wurster fluidized bed for the “cold” particle flows. One ECT sensor has a 12‐4 internal‐external electrodes and another has eight electrodes. The 12‐4‐electrode ECT sensor is used to measure the particle concentration in the annular fluidization region (outside of the Wurster tube) and the eight‐electrode ECT sensor is used to measure the particle flow in the central region (inside the Wurster tube). The effect of particle type, particle moisture, fluidization velocity, and geometrical parameters on the Wurster fluidization process is studied based on the two ECT measurements. The radial particle concentration profiles in the annular fluidization and central flow regions with different operation parameters are given. Fast Fourier Transform analysis of the particle concentration in the Wurster tube is performed with different superficial air velocities. The optimum operating ranges of the Wurster fluidization process for different particles are given. In the end of the article, computational fluids dynamics simulation results are given and used to compare with the measurement results by ECT for a typical Wurster fluidized bed. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-25T20:59:06.104639-05:
      DOI: 10.1002/aic.14595
       
  • Minimum entropy generation for isothermal endothermic/exothermic reactor
           networks
    • Authors: Paul G. Ghougassian; Vasilios Manousiouthakis
      Pages: n/a - n/a
      Abstract: In our earlier work, it was shown that entropy generation and energy (hot utility or cold utility) consumption of isothermal, isobaric reactor networks depend only on the network’s inlet and outlet stream compositions and flow rates and are not dependent on the reactor network structure, as long as the universe of realizable reactor units and network outlet mixing units are either all endothermic interacting with a single hot reservoir, or all exothermic interacting with a single cold reservoir respectively. In this work, it is shown that when the universe of realizable reactor/mixer units, of isothermal, isobaric, continuous stirred tank reactor networks, consists of both endothermic units interacting with a single hot reservoir and exothermic units interacting with a single cold reservoir, the network’s net (hot minus cold) utility consumption depends only on the network’s inlet and outlet stream compositions and flow rates (and does not depend on the network’s structure). In contrast, the network’s entropy generation depends on the network’s inlet and outlet stream compositions and flow rates, and the network’s hot utility (or cold utility) consumption. The latter, in general, depends on the network structure, thus making entropy generation also, in general, depend on network structure. Thus the synthesis of isothermal, isobaric reactor networks, with fixed inlet and outlet stream specifications, is equivalent to the synthesis of minimum hot (or cold) utility consuming such networks. The Infinite DimEnsionAl State‐space (IDEAS) conceptual framework is employed for the problem’s mathematical formulation, which is then used to rigorously establish the above equivalence. A case study involving Trambouze kinetics demonstrates the findings. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-21T10:56:53.104694-05:
      DOI: 10.1002/aic.14598
       
  • A mechanistic growth model for inorganic crystals: Solid‐state
           interactions
    • Authors: Preshit Dandekar; Michael F. Doherty
      Pages: n/a - n/a
      Abstract: Growth shapes of inorganic crystalline solids govern material properties such as catalytic activity and selectivity, solar cell efficiency, etc. A systematic understanding of the crystal growth process and the solid‐state interactions within inorganic crystals should help to engineer crystal shapes. We present a general model that identifies periodic bond chains in inorganic crystals while accounting for the long‐range electrostatic interactions. The variation in the electronic structure and the partial charges of growth units on the inorganic crystal surfaces has been captured using the bond valence model. The electrostatic interaction energies in the kink sites of inorganic crystals were calculated using a space partitioning method that is computationally efficient. This model provides a quantitative explanation for the asymmetric growth spirals formed on the surface of calcite. This methodology studying solid‐state interactions can be used with a mechanistic growth model to predict the morphology of a wide variety of inorganic crystals. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-21T02:29:25.776293-05:
      DOI: 10.1002/aic.14597
       
  • Practical challenges in the energy‐based control of molecular
           transformations in chemical reactors
    • Authors: Izabela Szydłowska Franssen; Daniel Irimia, Georgios D. Stefanidis, Andrzej I. Stankiewicz
      Pages: n/a - n/a
      PubDate: 2014-08-12T13:42:45.863869-05:
      DOI: 10.1002/aic.14575
       
  • Global optimality properties of total annualized and operating cost
           problems for compressor sequences
    • Authors: Jeremy A. Conner; Vasilios I. Manousiouthakis
      Pages: n/a - n/a
      Abstract: In this work, the minimum total annualized cost problem is studied for a series of non‐isentropic compressors and coolers that brings a gas with constant compressibility factor from a specified initial pressure and temperature to a specified final pressure and the same temperature. It is established analytically that at the global optimum, the cooler outlet temperatures are equal to the minimum allowable temperature. For constant heat capacity, constant compressibility factor gases, additional properties of the globally optimal compressor sequence are analytically established for the minimum operating cost case. The aforementioned properties permit development of a solution strategy that identifies the globally‐minimum operating cost. Several case studies are presented to illustrate the developed theorems and solution strategies. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-11T09:40:36.178594-05:
      DOI: 10.1002/aic.14580
       
  • Distributed Lyapunov‐based model predictive control with
           neighbor‐to‐neighbor communication
    • Authors: Su Liu; Jinfeng Liu
      Pages: n/a - n/a
      Abstract: We consider distributed predictive control of large‐scale nonlinear systems with neighbor‐to‐neighbor communication. This work fulfills the gap between the existing centralized Lyapunov‐based MPC (LMPC) and the cooperative distributed LMPC and provides a balanced solution in terms of implementation complexity and achievable performance. We focus on a class of nonlinear systems with subsystems interacting with each other via their states. For each subsystem, an LMPC is designed based on the subsystem model and the LMPC only communicates with its neighbors. At a sampling time, a subsystem LMPC optimizes its future control input trajectory assuming that the states of its upstream neighbors remain the same as (or close to) their predicted state trajectories obtained at the previous sampling time. Both non‐iterative and iterative implementation algorithms are considered. The performance of the proposed designs are illustrated via a chemical process example. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-11T06:12:03.418863-05:
      DOI: 10.1002/aic.14579
       
  • Modified gas‐translation model for prediction of gas permeation
           through microporous organosilica membranes
    • Authors: Hiroki Nagasawa; Takuya Niimi, Masakoto Kanezashi, Tomohisa Yoshioka, Toshinori Tsuru
      Pages: n/a - n/a
      Abstract: A modified gas‐translation (GT) model was applied for the theoretical analysis of gas permeation through microporous organosilica membranes derived from bis(triethoxysilyl)ethane (BTESE) via a sol‐gel method using different water/alkoxide molar ratios. The pore sizes of BTESE‐derived membranes were quantitatively determined by Normalized Knudsen‐based Permeance (NKP) analysis, which was based on a modified‐GT model, using experimentally obtained permeances of He, H2, N2, C3H8, and SF6. The pore sizes of BTESE‐derived membranes were successfully controlled from 0.65 to 0.46 nm by increasing the H2O/BTESE ratio from 6 to 240. Furthermore, theoretical correlations of all possible pairs of permeance ratios were calculated based on the modified‐GT model. The experimental data were in good agreement with the theoretical correlation curves, indicating that the modified‐GT model can clearly explain gas permeation mechanisms through microporous membranes, and, thus, can be used to predict the gas permeation properties for these membranes. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-11T06:06:22.375282-05:
      DOI: 10.1002/aic.14578
       
  • Mechanism and kinetic modeling for steam reforming of toluene on
           La0.8Sr0.2Ni0.8Fe0.2O3 catalyst
    • Authors: Usman Oemar; Ang Ming Li, Kus Hidajat, Sibudjing Kawi
      Pages: n/a - n/a
      Abstract: Reaction mechanism for steam reforming of toluene is proposed for La0.8Sr0.2Ni0.8Fe0.2O3 (LSNFO) perovskite catalyst. The proposed mechanism was derived from various characterization results such as TPD and TPSR water, TPSR toluene, TPD O2 and in‐situ DRIFT of toluene decomposition and steam reforming of toluene. Five kinetic models were developed based on the proposed dual‐site reaction mechanism using Langmuir‐Hinshelwood (LH) approach. Subsequently, the parameters of the kinetic models were estimated by non‐linear least square regression. A good agreement was obtained between experimental and model predicted results for the rate determining step (RDS) based on reaction between adsorbed aldehyde and adsorbed oxygen. The adsorbed aldehyde species is produced from the reaction between adsorbed C2H2 or CH2 and adsorbed oxygen while the adsorbed oxygen species can come from the oxygen from water activation, lattice oxygen species, and/or the redox property of some metals such as Fe. This shows that the adsorbed oxygen species plays important role in this reaction. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-11T05:36:59.473292-05:
      DOI: 10.1002/aic.14573
       
  • A numerical study of dynamic capillary pressure effect for supercritical
           carbon dioxide‐water flow in porous domain
    • Authors: Diganta B. Das; Bhupinder S. Gill, Luqman K. Abidoye, Kamal Khudaida
      Pages: n/a - n/a
      Abstract: Numerical simulations for core‐scale capillary pressure (Pc)–saturation (S) relationships have been conducted for a supercritical carbon dioxide‐water system at temperatures between 35°C and 65°C at a domain pressure of 15 MPa as typically expected during geological sequestration of CO2. As the Pc‐S relationships depend on both S and time derivative of saturation (∂S / ∂t) yielding what is known as the ‘dynamic capillary pressure effect’ or simply ‘dynamic effect’, this work specifically attempts to determine the significance of these effects for supercritical carbon dioxide‐water flow in terms of a coefficient, namely dynamic coefficient (τ). The coefficient establishes the speed at which capillary equilibrium for supercritical CO2‐water flow is reached. The simulations in this work involved the solution of the extended version of Darcy’s law which represents the momentum balance for individual fluid phases in the system, the continuity equation for fluid mass balance, as well as additional correlations for determining the capillary pressure as a function of saturation, and the physical properties of the fluids as a function of temperature. The simulations were carried for 3D cylindrical porous domains measuring 10 cm in diameter and 12 cm in height. τ was determined by measuring the slope of a best‐fit straight line plotted between (i) the differences in dynamic and equilibrium capillary pressures (Pc,dyn – Pc,equ) against (ii) the time derivative of saturation (dS/dt), both at the same saturation value. The results show rising trends for τ as the saturation values reduce, with noticeable impacts of temperature at 50% saturation of aqueous phase. This means that the time to attain capillary equilibrium for the CO2‐water system increases as the saturation decreases. From a practical point view, it implies that the time to capillary equilibrium during geological sequestration of CO2 is an important factor and should be accounted for while simulating the flow processes, e.g., to determine the CO2 storage capacity of a geological aquifer. In this task, one would require both the fundamental understanding of the dynamic capillary pressure effects for supercritical CO2‐water flow as well as τ values. These issues are addressed in this article. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-08T11:58:12.148498-05:
      DOI: 10.1002/aic.14577
       
  • Near‐wall convection in a sedimenting suspension of fibres
    • Authors: Feng Zhang; Katarina Gustavsson, Fredrik Lundell, Anders A. Dahlkild
      Pages: n/a - n/a
      Abstract: The sedimentation of a fibre suspension near a vertical wall is investigated numerically. Initially, the near‐wall convection is an upward backflow, which originates from the combined effects of the steric‐depleted layer and a hydrodynamically‐depleted region near the wall. The formation of the hydrodynamically‐depleted region is elucidated by a convection‐diffusion investigation, in which fibres are classified according to the different directions in which they drift. For fibres with sufficiently large aspect ratio, the initial near‐wall backflow keeps growing. However, the backflow reverses to downward flow at later times if the aspect ratio is small. This is due to the fibre‐wall interactions which rotate fibres to such angles that make fibres drift away from the wall, inducing a dense region and a correspondingly downward flow outside the initial backflow. Moreover, the steric‐depleted boundary condition is of secondary importance in the generation and evolution of the near‐wall convection. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-08T11:35:18.80853-05:0
      DOI: 10.1002/aic.14576
       
  • Analysis of plug flow reactors with variable mass density
    • Authors: J. S. Vrentas; C. M. Vrentas
      Pages: n/a - n/a
      Abstract: The design of plug flow reactors with variable mass density is examined. Equations which include a two‐term constitutive equation for the reaction rate are derived for the flow of liquids and for the flow of ideal gases in steady plug flow reactors. It is shown that the addition of the second term in the constitutive equation can have a significant effect on the calculation of the reactor volume needed to carry out a specific conversion of the reactant. Published experimental plug flow reactor data support the observation that a reaction rate constitutive equation with two terms can provide a good representation of the experimental data for variable mass density reactors. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-06T07:35:05.487258-05:
      DOI: 10.1002/aic.14574
       
  • Influence of loading rate and pre‐loading on the mechanical
           properties of dry elasto‐plastic granules under compression
    • Authors: Alexander Russell; Peter Müller, Hao Shi, Jürgen Tomas
      Pages: n/a - n/a
      Abstract: In order to ensure high quality of granular products post‐industrial operations, it is necessary to precisely define their micro‐macro mechanical properties. However, such an endeavor is arduous, owing to their highly inhomogeneous, anisotropic and history‐dependent nature. In this article, we present the distributed granular micro‐ and macro‐mechanical, energetic and breakage characteristics using statistical distributions. We describe the material behavior of elasto‐plastic zeolite 4AK granules under uniaxial compressive loading until primary breakage, and localized cyclic loading up to different maximum force levels, at different displacement‐controlled loading rates. The observed force‐displacement behavior had been approximated and further evaluated using well‐known contact models. The results provide the basis for a detailed analysis of the viscous behavior of zeolite 4AK granules in the moist and wet states, indicating that higher compressive loads are required at higher displacement‐controlled loading rates to realize equivalent deformation and breakage probability achieved by loads at lower displacement‐controlled loading rates. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-04T06:00:36.692376-05:
      DOI: 10.1002/aic.14572
       
  • Continuous flow characterization of solid biomass in a
           reciprocating/rotating scraper tube: An experimental study
    • Authors: Kamelia V.K. Boodhoo; Lily Smith, Juan Pedro Solano, Mark Gronnow, James Clark
      Pages: n/a - n/a
      Abstract: The performance of reciprocating/rotating scrapers has been assessed in a visualization study of the continuous flow hydrodynamics of air‐fluidized solid biomass under varying conditions of air flow rate and scraping velocities. A combination of low air flow rates and high scraping velocities result in more uniform flow of both types of biomass investigated. Power consumed by the reciprocating action of the scrapers increases with the scraping velocity but typically represents no more than 20% of the overall power consumption at the highest air flow rate applied. We also demonstrate that rotation of the scrapers superimposed on their reciprocating action gives higher flow rate of biomass and better mixing within the bulk solid compared to reciprocating action alone. The application of the reciprocating/rotating scraper technology described in this study represents a viable step forward in developing a continuous, large‐scale process for the microwave‐assisted decomposition of solid biomass to produce bio‐oils. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-04T05:20:37.661511-05:
      DOI: 10.1002/aic.14571
       
  • Analytical models of penetration depth during slot die coating onto porous
           media
    • Authors: Xiaoyu Ding; Zhuo Li, Joshua Prince Ebin, Thomas F. Fuller, Tequila A.L. Harris
      Pages: n/a - n/a
      Abstract: A series of analytical models have been developed to predict the penetration depth during slot die coating on porous media. Analytical models for both Newtonian and non‐Newtonian fluids were derived based on Lubrication Theory, Darcy’s law, and a modified Blake‐Kozeny equation. Using these models, the penetration depth can be quickly solved and the effects of material properties and processing conditions on penetration depth can be easily investigated. Experiments of coating Newtonian glycerin and non‐Newtonian blackstrap molasses onto Toray series carbon paper were conducted to validate developed models. The overall relative error between the predicted and measured penetration depth was found to be typically lower than 20%, which demonstrates the relative accuracy of developed models. Furthermore, based on a parametric study, it was found that the effect of capillary pressure on penetration depth is less than 10% when the ratio of coating bead pressure and capillary pressure is larger than 10. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-01T10:49:24.54136-05:0
      DOI: 10.1002/aic.14570
       
  • Experimental investigation of continuous single‐phase rimming flow
           in a horizontal rotating cylinder
    • Authors: Saravanan Suppiah Singaram; Roshan J Jachuck, Himanshu Lodha
      Pages: n/a - n/a
      Abstract: Rimming flow of water that leads to a thin film onto the inner surface of a horizontally rotating cylinder is studied in this work. At higher rotational speeds, axial flow of uniform thin film is established inside the rotating cylinder. Film thickness measurements under different flow conditions were performed in the annular flow regime using an optical interferometric technique. Dimensional analysis was also performed to understand the parametric dependence of key parameters involved in the rimming flow of water inside a horizontal rotating cylinder and expressions to determine average film thickness and average residence time are also presented. This current study will provide a basis to estimate the transport characteristics in the thin film inside the horizontal rotating cylinder. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-01T05:36:07.46609-05:0
      DOI: 10.1002/aic.14569
       
  • Formation of defect-free polyetherimide/PIM-1 hollow fiber membranes for
           gas separation
    • Authors: Lin Hao; Jian Zuo, Tai-Shung Chung
      Pages: n/a - n/a
      Abstract: Dual-layer hollow fiber membranes were produced from blends of Ultem and polymer of intrinsic microporosity (PIM-1) with enhanced gas permeance. The effects of spinning parameters (take-up speed and air gap distance) on gas separation performance were investigated based on the pristine Ultem. Selected spinning conditions were further adopted for the blend system, achieving defect-free and almost defect-free hollow fibers. Adding PIM results in a higher fractional free volume, 50% increments in gas permeance were observed for Ultem/PIM-1 (95/5) and more than 100% increments for Ultem/PIM-1 (85/15). Both O2/N2 and CO2/CH4 selectivities remained the same for Ultem/PIM-1 (95/5) and above 80% of their respective intrinsic values for Ultem/PIM-1 (85/15). The selective layer thickness ranges from 70 to 120 nm, indicating the successful formation of ultrathin dense layers. Moreover, minimum amounts of the expensive material were consumed, that is, 0.88, 1.7, and 2.3 wt % PIM-1 for Ultem/PIM-1 (95/5), (90/10), and (85/15), respectively. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-28T14:09:07.6357-05:00
      DOI: 10.1002/aic.14565
       
  • Model reduction for linear simulated moving bed chromatography systems
           using Krylov-subspace methods
    • Authors: Suzhou Li; Yao Yue, Lihong Feng, Peter Benner, Andreas Seidel-Morgenstern
      Pages: n/a - n/a
      Abstract: Simulated moving bed (SMB) chromatography is a well-established technology for separating chemical compounds. To describe an SMB process, a finite-dimensional multistage model arising from the discretization of partial differential equations is typically employed. However, its relatively high dimension poses severe computational challenges to various model-based analysis. To overcome this challenge, two Krylov-type model order reduction (MOR) methods are proposed to accelerate the computation of the cyclic steady states (CSSs) of SMB processes with linear isotherms. A “straightforward method” that carefully deals with the switching behavior in MOR is first proposed. Its improvement, a “subspace-exploiting method,” thoroughly exploits each reduced model to achieve further acceleration. Simulation studies show that both methods achieve high accuracy and significant speedups. The subspace-exploiting method turns out to be computationally much more efficient. Two challenging analyses of SMB processes, namely uncertainty quantification and CSS optimization, further demonstrate the accuracy, efficiency, and applicability of the proposed methods. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-28T14:03:09.521068-05:
      DOI: 10.1002/aic.14561
       
  • Experimental validation of a flexible modeling approach for distillation
           columns with packings
    • Authors: Christoph Ehlers; Georg Fieg
      Pages: n/a - n/a
      Abstract: The two main concepts for the modeling of distillation columns are the equilibrium-stage (EQ) and the nonequilibrium-stage (NEQ). A model is presented which combines decisive features of both conventional concepts. Based on the idea of a reduced nonequilibrium-stage (RNEQ), this model can be used for the simulation of distillation columns with packings. In contrast to the conventional NEQ approach, this model neglects the influence of liquid side mass-transfer coefficients, which ultimately allows to come up with only one empirical equation describing the overall mass transfer. Thus, a considerable reduction in model complexity is reached, which allows for an efficient consideration of new experimental distillation results. Fitted to experimental data, the model is able to predict, how different pressures and chemical systems might affect the separation efficiency. By comparing calculation results with experimentally determined separation efficiencies for three different packing types, these valuable RNEQ qualities are illustrated. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-24T13:22:23.478698-05:
      DOI: 10.1002/aic.14560
       
  • Mixing potential: A new concept for optimal design of hydrogen and water
           networks with higher disturbance resistance
    • Authors: Zuwei liao; Junyi Lou, Jingdai Wang, Binbo Jiang, Yongrong Yang
      Pages: n/a - n/a
      Abstract: During the last decade, the design methods of hydrogen and water networks have been improved greatly. Since the resulting network structure featuring minimum utility consumption is not unique, other properties such as disturbance resistance have drawn more and more attention. In this article, a novel concept, Mixing Potential, is proposed to improve the disturbance resistance ability of the networks in the design stage. This concept originates from measuring the concentration fluctuation of a single sink, and could be calculated by its graphical and algorithmic definition, respectively. In addition, a sufficient condition for minimizing the Mixing Potential of a single sink has been proved. Based on this sufficient condition, a graphical and its corresponding algorithmic method are proposed to design the hydrogen and water networks with minimum utility consumption. Literature examples illustrate that the disturbance resistance ability of the network can be improved by adjusting the satisfying order of sinks. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-24T13:22:01.598619-05:
      DOI: 10.1002/aic.14556
       
  • Framework for correlating the effect of temperature on nonelectrolyte and
           ionic liquid activity coefficients
    • Authors: Timothy C. Frank; Steven G. Arturo, Bruce S. Holden
      Pages: n/a - n/a
      Abstract: A power-law expression is proposed for correlating the temperature dependence of infinite-dilution activity coefficients ( γij∞) for nonelectrolyte solute–solvent binary pairs and for pairs including an ionic liquid: ln⁡γij∞(at T)/ln⁡γij∞(at Tref)=(Tref/T)θij, where θij = 0 for Lewis–Randall ideal solutions, θij = 1 for classic enthalpy-based Scatchard–Hildebrand regular solution and van Laar models, and −5 
      PubDate: 2014-07-24T13:16:26.501557-05:
      DOI: 10.1002/aic.14557
       
  • Impact of separator’s solid phase ion conductivity parameter on
           convection battery performance and modeling
    • Authors: R. Hilton; M. Gordon, D. Dornbusch, G. J. Suppes
      Pages: n/a - n/a
      Abstract: A solid phase ion conductivity parameter has been added to the separator of a porous electrode theory description of a convection battery performance to increase the accuracy of this model. With the addition of the ion conductivity parameter, the variances between the model and experimental data have been reduced by 80-85% in both the convection cell and the diffusion cell. The parameter is fundamentally consistent with solid phase mechanisms by which ions can transport through separators in parallel with liquid phase transport, and the improved modeling results substantiate the importance of solid or surface ion transport mechanisms at high current fluxes. Modeling was supplemented with dimensionless analysis to lump fundamental parameters that are inherently coupled in the underlying equations. From this analysis, a global parameter has been developed describing the ratio of convective charge transfer to diffusive charge transfer that characterizes the transition from diffusive to convective cell behavior. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-24T01:02:05.521355-05:
      DOI: 10.1002/aic.14568
       
  • Equation-oriented flowsheet simulation and optimization using
           pseudo-transient models
    • Authors: Richard C. Pattison; Michael Baldea
      Pages: n/a - n/a
      Abstract: Tight integration through material and energy recycling is essential to the energy efficiency and economic viability of process and energy systems. Equation-oriented steady state process simulation and optimization are key enablers in the optimal design of integrated processes. In this paper a new process modeling and simulation concept based on pseudo-transient continuation is introduced. We present an algorithm for reformulating the steady-state models of process unit operations as differential-algebraic equation (DAE) systems that are statically equivalent with the original model. We show that these pseudo-transient models improve the convergence of equation-oriented process flowsheet simulations by expanding the convergence basin. We use this concept to build a library of pseudo-transient models for common process unit operations, and show that this modeling concept seamlessly integrates with a previously developed time-relaxation optimization algorithm. Two design case studies are presented to validate the proposed framework. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-24T00:28:29.260326-05:
      DOI: 10.1002/aic.14567
       
  • Structure-property Relationship of pH-sensitive (PCL)2(PDEA-b-PPEGMA)2
           micelles: Experiment and DPD simulation
    • Authors: Wen JingLin; Shu YuNie, Quan Chen, Yu Qian, Xiu FangWen, Li Juan Zhang
      Pages: n/a - n/a
      Abstract: The experiment and dissipative particle dynamics (DPD) simulation were carried out on four polymers with different block ratios for the investigation of the structure-property relationship of (poly(ε-caprolactone)2-[poly(2-(diethylamino)ethyl methacrylate)-b-poly(poly(ethylene glycol) methyl ether methacrylate)]2 [(PCL)2(PDEA-b-PPEGMA)2] micelles. The miktoarm star polymers assembled into spherical micelles composed of PCL core, pH-sensitive PDEA mesosphere and PPEGMA shell. When decreasing pH from 7.4 to 5.0, the hydrodynamic diameter and transmittance of (PCL)2(PDEA-b-PPEGMA)2 micelles increased along with globule-uneven-extended conformational transitions, owing to the protonation of tertiary amine groups of DEA at lower pH conditions. Doxorubicin (DOX) was mainly loaded in the pH-sensitive layer, and more DOX were loaded in the core when increasing drug concentrations. The in vitro DOX release from the micelles was significantly accelerated by decreasing pH from 7.4 to 5.0. The results demonstrated that the pH-sensitive micelles could be used as an efficient carrier for hydrophobic anticancer drugs, achieving controlled and sustained drug release. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-22T03:30:49.283386-05:
      DOI: 10.1002/aic.14562
       
  • Polypropylene in the melt state as a medium for in situ synthesis of
           copper nanoparticles
    • Authors: Humberto Palza; Katherine Delgado, Natalia Moraga, Sing-Hi Wang Molina
      Pages: n/a - n/a
      Abstract: Copper nanoparticles were in situ synthesized into a polypropylene matrix in the melt state. Three different routes were studied depending on the method used for the addition of a copper salt: (1) directly as powder; (2) dissolved in water; and (3) dissolved in water with a reducing agent. The first route produced microcrystal, whereas the second route allowed the synthesis of nanoparticles (∼20 nm) homogeneously dispersed in the polymer matrix. By changing the concentration of the reducing agent in the copper solution (third route), a control of the copper structure in the polymer was possible and salt-based or metal/oxide nanoparticles could be obtained. All these composites were able to release copper ions depending on the characteristic of the nanoparticles present in the polymer. Noteworthy, the resulting polymer/copper composites displayed strong antimicrobial behavior against Escherichia coli. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-21T11:03:38.13524-05:0
      DOI: 10.1002/aic.14549
       
  • Phase Equilibria and Structural Properties of Thiophene/[Bmim][BF4]: A
           Molecular Insight from Monte Carlo Simulations
    • Authors: Yongping Zeng; Chunfeng Wang, Yueyang Xu, Junmei Hu, WenLin Xu, Shengui Ju
      Pages: n/a - n/a
      Abstract: The phase equilibria of thiophene in 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) is calculated by Monte Carlo simulation in Gibbs ensemble using a united atom force field. The liquid density of studied ionic liquid and the vapor pressure of thiophene in [Bmim][BF4] were compared with corresponding experimental data reported in the literature, and a good agreement was obtained. In order to describe the solubility of thiophene in this ionic liquid, we have calculated the radial distribution functions and spatial distribution functions of thiophene/IL mixtures to study the interaction of thiophene with cations and anions of [Bmim][BF4] in the liquid phase. The local composition concept in fluid was also examined to give further insight into the liquid structure. The results show that thiophene is well organized around the terminal carbon atom of the butyl or methyl chain attached to the imidazolium ring of cations and tends to adopt a symmetrically distribution on the anions. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-21T05:24:07.325795-05:
      DOI: 10.1002/aic.14566
       
  • A lattice Boltzmann simulation of mass transport through composite
           membranes
    • Authors: Li-Zhi Zhang
      Pages: n/a - n/a
      Abstract: Composite membranes with a porous support layer and a dense skin layer have been extensively used in gas separation processes. In this study, a new approach, a meso-scale Lattice Boltzmann Simulation approach (LBM), is proposed and used to model the pore-scale gas flow and mass transfer in the inhomogeneous membrane matrixes. Only physical forces are considered. Chemical forces are equivalently converted to physical forces through the relaxation time. Selective permeation of moisture through a composite membrane is modeled. The overall permeability is evaluated. It is found that mass transfer inhomogeneity exists not only in the porous media, but also in the seemingly uniform dense skin layer. Increasing the diffusivity in the skin layer is more effective than decreasing the skin layer thickness in optimizing the overall membrane performance. The new approach gives more detailed insights into the directions for future design of composite membranes for gas separations like air dehumidification. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-19T06:59:00.05676-05:0
      DOI: 10.1002/aic.14564
       
  • The adjustable synergistic effects between acid-base coupling bifunctional
           ionic liquid extractants for rare earth separation
    • Authors: Xiaoqi Sun; Kristian E Waters
      Pages: n/a - n/a
      Abstract: Two of the most widely used industrial extractants for rare earth elements (REEs), i.e., di(2-ethylhexyl)phosphoric acid (HDEHP) and 2-ethyl(hexyl) phosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) were developed into [DEHP]- type acid-base coupling bifunctionalized ionic liquids (ABC-BILs) and [EHEHP]- type ABC-BILs, respectively. The combinations of ABC-BIL extractants revealed obviously synergistic effects for REEs. Seven different combinations of ABC-BILs and five kinds of REEs confirmed the novel synergistic extraction. Some synergy coefficients of the combined ABC-BILs were bigger than those of mixed HDEHP and HEH[EHP] by two orders of magnitude. This paper reports the first synergistic extraction produced by ionic liquid extractants in the field of solvent extraction. The novel synergistic extraction from combined ABC-BILs extractants revealed highly efficient and environmentally friendly potential in both of academic research and industrial application for REEs separation. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-19T03:06:18.682879-05:
      DOI: 10.1002/aic.14563
       
  • Microwave assisted flow synthesis: Coupling of electromagnetic and
           hydrodynamic phenomena
    • Authors: Narendra G. Patil; Faysal Benaskar, Jan Meuldijk, Lumbertus A. Hulshof, Volker Hessel, Jaap C. Schouten, Erik D. C. Esveld, Evgeny V. Rebrov
      Pages: n/a - n/a
      Abstract: This article describes the results of a modeling study performed to understand the microwave heating process in continuous-flow reactors. It demonstrates the influence of liquid velocity profiles on temperature and microwave energy dissipation in a microwave integrated milli reactor-heat exchanger. Horizontal cocurrent flow of a strong microwave absorbing reaction mixture (ethanol + acetic acid, molar ratio 5:1) and a microwave transparent coolant (toluene) was established in a Teflon supported quartz tube (i.d.: 3 × 10−3 m and o.d.: 4 × 10−3 m) and shell (i.d.: 7 × 10−3 m and o.d.: 9 × 10−3 m), respectively. Modeling showed that the temperature rise of the highly microwave absorbing reaction mixture was up to four times higher in the almost stagnant liquid at the reactor walls than in the bulk liquid. The coolant flow was ineffective in controlling the outlet reaction mixture temperature. However, at high flow rates it limits the overheating of the stagnant liquid film of the reaction mixture at the reactor walls. It was also found that the stagnant layer around a fiber optic temperature probe, when inserted from the direction of the flow, resulted in much higher temperatures than the bulk liquid. This was not the case when the probe was inserted from the opposite direction. The experimental validations of these modeling results proved that the temperature profiles depend more on the reaction mixture velocity profiles than on the microwave energy dissipation/electric field intensity. Thus, in flow synthesis, particularly where a focused microwave field is applied over a small tubular flow reactor, it is very important to understand the large (direct/indirect) influence of reactor internals on the microwave heating process. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-18T13:35:33.306397-05:
      DOI: 10.1002/aic.14552
       
  • A novel hybrid feedstock to liquids and electricity process: Process
           modeling and exergoeconomic life cycle optimization
    • Authors: Chang He; Fengqi You, Xiao Feng
      Pages: n/a - n/a
      Abstract: This article proposes a novel hybrid low-rank coal (LRC)/biomass/natural gas process for producing liquid fuels and electricity. The hybrid process highlights coexistence of indirect and direct liquefaction technologies, cogasification of char and biomass, and corefinery of LRC syncrude and Fischer–Tropsch syncrude. A process simulation based on detailed chemical kinetics is present to illustrate its feasibility. In addition, we propose an exergoeconomic life cycle optimization framework that seeks to maximize the primary exergy saving ratio, primary total overnight cost saving ratio, life cycle waste emissions avoidance ratio, and primary levelized cost saving ratio by comparing the proposed hybrid process to its reference stand-alone subsystems. From the results, we can determine four optimal designs which yield competitive breakeven oil prices ranging from $1.87/GGE to $2.13/GGE. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-18T13:32:34.589941-05:
      DOI: 10.1002/aic.14551
       
  • Enhancement of flux and solvent stability of Matrimid® thin-film
           composite membranes for organic solvent nanofiltration
    • Authors: Shi-Peng Sun; Tai-Shung Chung, Kang-Jia Lu, Sui-Yung Chan
      Pages: n/a - n/a
      Abstract: The development of high flux and solvent-stable thin-film composite (TFC) organic solvent nanofiltration (OSN) membranes was reported. A novel cross-linked polyimide substrate, consisting of a thin skin layer with minimum solvent transport resistance and a sponge-like sublayer structure that could withstand membrane compaction under high-pressure was first fabricated. Then the solvent flux was significantly enhanced without compromising the solute rejection by the coupling effects of (1) the addition of triethylamine/camphorsulfonic acid into the monomer solution, and (2) the combined post-treatments of glycerol/sodium dodecyl sulphate immersion and dimethyl sulfoxide (DMSO) filtration. Finally, the long-term stability of the TFC membrane in aprotic solvents such as DMSO was improved by post-crosslink thermal annealing. The novel TFC OSN membrane developed was found to have superior rejection to tetracycline (MW: 444 g/mol) but was very permeable to alcohols such as methanol (5.12 lm−2h−1bar−1) and aprotic solvents such as dimethylformamide (3.92 lm−2h−1bar−1) and DMSO (3.34 lm−2h−1bar−1). © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-18T11:07:45.512646-05:
      DOI: 10.1002/aic.14558
       
  • Reconstruction of transcription factor profiles from fluorescent protein
           reporter systems via dynamic optimization and Tikhonov regularization
    • Authors: Wei Dai; Juergen Hahn, Jia Kang
      Pages: n/a - n/a
      Abstract: This work presents a generally applicable technique for reconstructing transcription factor (TF) profiles from fluorescence microscopy images of green fluorescent protein reporter systems. The approach integrates dynamic optimization and a Tikhonov regularization to avoid over-fitting caused by the highly ill-conditioned structure of this inverse problem. The advantage that the presented approach has over existing methods is that no assumptions are made about the TF profile, the linearity, or lack thereof, of the dynamic model used, and the sampling time of the measurements. Moreover, the method allows to use discretization times for the model different from the measurement sampling times and can also deal with state constraints. The technique has been applied to both simulated and experimental data where the profile of the TFs NF-κB and STAT3 are reconstructed. In both of the case studies, the presented approach exhibits excellent performance while fewer assumptions are needed than for existing techniques. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-18T11:04:28.555781-05:
      DOI: 10.1002/aic.14559
       
  • Effect of impeller design and power consumption on crystal size
           distribution
    • Authors: Chinmay V. Rane; Kalekudithi Ekambara, Jyeshtharaj B. Joshi, Doraiswami Ramkrishna
      Pages: n/a - n/a
      Abstract: Crystallization processes in a 500 mL stirred tank crystallizer with computational fluid dynamics (CFD) and population balances toward estimating how crystal size distributions (CSDs) are influenced by flow inhomogeneities was explored. The flow pattern and CSD are presented here though extensive phase Doppler particle analyzer measurements and CFD predictions for three different impeller designs (disc turbine, pitched blade turbine, and Propeller) and each rotated at three different speeds (2.5, 5, and10 r/s). As crystallization processes in practice could involve break-up and aggregation of crystals, some selected break-up and aggregation kernels are incorporated. Extensive comparison of simulations with experimental data showed consistent trends in the proper quantitative range. An attempt has also been made to develop scaling laws: (a) mean particle size with average power consumption per unit mass and (b) particle-size distribution with the turbulent energy dissipation distribution. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-16T14:14:53.653545-05:
      DOI: 10.1002/aic.14541
       
  • Comparison of wash‐coated monoliths vs. microfibrous entrapped
           catalyst structures for catalytic VOC removal
    • Authors: Sabrina Wahid; Donald R. Cahela, Bruce J. Tatarchuk
      Pages: n/a - n/a
      Abstract: Head‐to‐head experimental performance comparisons for flow through pleated microfibrous structures (flat‐, V‐, and W‐shaped) were made with wash‐coated monolith of different cells per square inch (230 and 400). Microfibrous entrapped catalyst (MFEC) was prepared by entrapping support particles (γ‐Al2O3, 150–250 μm diameter) into nickel microfibers. Pleated structures of MFECs and wash‐coated monoliths containing Pd‐Mn/γ‐Al2O3 were investigated systematically for volatile organic compound (e.g., ethanol) removal at various face velocities (ca. 3–30 m/s) and at low temperatures (≤473 K). The experimental studies showed that pleated MFEC (W‐shaped) had shown significantly improved performance in VOC removal in terms of conversion and pressure drop than tested monolith for high face velocity system. The flexibility of pleating lowered the effective velocity inside the media that resulted lower pressure drop and higher conversion. Furthermore, a reaction kinetic model was developed for pleated MFEC considering the Peffer's model to substantiate the experimental results. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-15T16:16:32.634213-05:
      DOI: 10.1002/aic.14555
       
  • Kinetic study of retro‐aldol condensation of glucose to
           glycolaldehyde with ammonium metatungstate as the catalyst
    • Authors: Junying Zhang; Baolin Hou, Aiqin Wang, ZhenLei Li, Hua Wang, Tao Zhang
      Pages: n/a - n/a
      Abstract: The kinetics of the retro‐aldol condensation of glucose to glycolaldehyde was studied in a batch reactor at 423–453 K using ammonium metatungstate (AMT) as the catalyst. Three consecutive reactions were considered: retro‐aldol condensation of glucose to erythrose and glycolaldehyde (R1), retro‐aldol condensation of erythrose to two moles of glycolaldehyde (R2), and further conversion of glycolaldehyde to side products (R3). Fitting of the experimental data showed that R1 was first‐order reaction while R2 and R3 were 1.7th‐ and 2.5th‐order reaction, respectively. Conversely, the reaction rate of R1 was 0.257th‐order dependence on the concentration of AMT catalyst. The apparent activation energies for R1, R2, and R3 were 141.3, 79.9, and 52.7 kJ/mol, respectively. The high activation energy of R1 suggests that a high temperature is favorable to the formation of glycolaldehyde. The experimental C–t curves at different temperatures and initial glucose concentrations were well predicted by the kinetic model. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-15T14:08:43.897286-05:
      DOI: 10.1002/aic.14554
       
  • Flow and temperature patterns in an inductively coupled plasma reactor:
           Experimental measurements and CFD simulations
    • Authors: Sangeeta B. Punjabi; Sunil N. Sahasrabudhe, S. Ghorui, A. K. Das, Narendra K. Joshi, Dushyant C. Kothari, Arijit A. Ganguli, Jyeshtharaj B. Joshi
      Pages: n/a - n/a
      Abstract: Measurements of temperature patterns in an inductively coupled plasma (ICP) have been carried out experimentally. Plasma torch was operated at different RF powers in the range of 3–14 kW at near atmospheric pressure and over a wide range of sheath gas flow rate (3–25 lpm). Measurements were made at five different axial positions in ICP torch. The chordal intensities were converted into a radial intensity profile by Abel Inversion technique. Typical radial temperature profile shows an off‐axis temperature peak, which shifts toward the wall as the power increases. Temperatures in the range of 6000–14,000 K were recorded by this method. The temperature profiles in the plasma reactor were simulated using computational fluid dynamics (CFD). A good agreement was found between the CFD predictions of the flow and temperature pattern with those published in the literature as well as the temperature profiles measured in the present work. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-15T14:07:42.877996-05:
      DOI: 10.1002/aic.14547
       
  • High‐throughput packed‐bed microreactors with in‐line
           analytics for the discovery of asphaltene deposition mechanisms
    • Authors: Chuntian Hu; Ryan L. Hartman
      Pages: n/a - n/a
      Abstract: Understanding asphaltene nanoaggregation kinetics is a key to predicting the deposition in pure quartz‐grain porous media. High‐throughput quartz packed‐bed microreactors (μPBRs) were, therefore, designed to provide mechanistic insights by merging oilfield chemistry and microchemical systems. In‐line UV‐Vis spectroscopy and pressure transducer were used to characterize the stable packing of quartz particles with porosity of ∼40% and permeability of ∼5.5 × 10−13 m2. Temperature (25.0–90.0°C), n‐heptane composition (50.0–80.0 vol %), and n‐alkane (n‐C5 to n‐C9) were all observed to influence asphaltenes deposition in the porous media, and reduced dispersion was obtained in the damaged packed‐bed by estimating dispersion coefficients and the Bodenstein number. Deposition by mechanical entrapment dominated the mechanism in all scenarios, as discovered by the simplified Kozeny–Carman and Civan's permeability‐porosity relationships. The results could aid in the design of remediations that minimize production losses of considerable economic magnitude. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-10T12:57:05.481004-05:
      DOI: 10.1002/aic.14542
       
  • Atomic layer deposition of polyimide on microporous polyethersulfone
           membranes for enhanced and tunable performances
    • Authors: Ting Sheng; He Chen, Sen Xiong, Xiaoqiang Chen, Yong Wang
      Pages: n/a - n/a
      Abstract: Atomic layer deposition (ALD) of polyimide (PI) is explored to tune the separation properties of microporous polyethersulfone (PES) membranes and also to improve their mechanic and thermal stability. Conformal and uniform thin layers of PI are deposited along the pore wall throughout the entire PES membrane instead of forming a top layer merely on the membrane surface. With increasing ALD cycles, the pore size of the PES membrane is progressively reduced, leading to increased retention. The permeation is correspondingly decreased but its drop is less pronounced than the increase of retention. For example, the retention to 23‐nm silica nanospheres is significantly increased from nearly zero to 60% after 3000 ALD cycles, whereas the water flux is moderately decreased by 54%. Moreover, ALD of PI evidently enhances the mechanical strength and thermal resistance of the PES membrane as PI tightly wraps the skeleton of the membrane. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-10T12:37:53.431256-05:
      DOI: 10.1002/aic.14553
       
  • Gas–liquid flow modeling in columns equipped with structured packing
    • Authors: Cyprien Soulaine; Pierre Horgue, Jacques Franc, Michel Quintard
      Pages: n/a - n/a
      Abstract: The modeling of gas–liquid flow in distillation columns equipped with structured packing has been dealt. The devices are seen as bistructured porous media, and a macroscale model is proposed taking into account this specific geometry. In this model, the two liquid films, one‐per‐sheet, are treated separately and are allowed to exchange matter at the vicinity of the contact points between corrugated sheets. The model emphasizes mechanisms that lead to the liquid radial dispersion effects: a main part comes from the geometry itself, another part is due to the capillary effects. A particular attention is paid to model these phenomena from a macroscale point of view. Finally, the simulation results are confronted to tomography imaging within a lab‐scale column and show a qualitative good agreement of the liquid distribution. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-10T12:36:00.74958-05:0
      DOI: 10.1002/aic.14550
       
  • Optimization models for shale gas water management
    • Authors: Linlin Yang; Ignacio E. Grossmann, Jeremy Manno
      Pages: n/a - n/a
      Abstract: There are four key aspects for water use in hydraulic fracturing, including source water acquisition, wastewater production, reuse and recycle, and subsequent transportation, storage, and disposal. Water use life cycle is optimized for wellpads through a discrete‐time two‐stage stochastic mixed‐integer linear programming model under uncertain availability of water. The objective is to minimize expected transportation, treatment, storage, and disposal cost while accounting for the revenue from gas production. Assuming freshwater sources, river withdrawal data, location of wellpads, and treatment facilities are given, the goal is to determine an optimal fracturing schedule in coordination with water transportation, and its treatment and reuse. The proposed models consider a long‐time horizon and multiple scenarios from historical data. Two examples representative of the Marcellus Shale play are presented to illustrate the effectiveness of the formulation, and to identify optimization opportunities that can improve both the environmental impact and economical use of water. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-09T17:50:52.759637-05:
      DOI: 10.1002/aic.14526
       
  • Kinetics of CO2 absorption by aqueous 3‐(methylamino)propylamine
           solutions: Experimental results and modeling
    • Authors: Juliana G. M.‐S. Monteiro; Saddam Hussain, Hammad Majeed, Emmanuel O. Mba, Ardi Hartono, Hanna Knuutila, Hallvard F. Svendsen
      Pages: n/a - n/a
      Abstract: Experimental data and a model for the initial kinetics of CO2 into 3‐(methylamino)propylamine (MAPA) solutions are presented in work. MAPA has been tested as an activator for tertiary amines with encouraging results. The measurements were performed in a string of discs contactor and, as no initial kinetics data are available in literature, additional measurements were carried out and in a wetted wall column. The obtained overall mass‐transfer coefficients from both apparatuses are in reasonable agreement. To obtain values for the observed kinetic constant, kobs, the experimental results were interpreted using a two‐film mass‐transfer model and invoking the pseudo‐first order assumption. Needed experimental values for density, viscosity, and Henry's law coefficient for CO2 were measured and are given. The results indicate that MAPA is almost twice as fast as piperazine, eight times faster than 2‐(2‐aminoethyl‐amino)ethanol (AEEA), and 15 times faster than monoethanolamine, when comparing unloaded 1 M solutions at 25°C. The observed kinetic constant was modeled using the direct mechanism. The final expression for kobs can be applied for any concentration and temperature within the experimental data range, and, together with the presented physical data, comprises a complete model for calculating absorption fluxes. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-09T17:38:37.973748-05:
      DOI: 10.1002/aic.14546
       
  • Continuous electroreduction of CO2 to formate using Sn gas diffusion
           electrodes
    • Authors: Andrés Del Castillo; Manuel Alvarez‐Guerra, Angel Irabien
      Pages: n/a - n/a
      Abstract: Electrochemical valorization may be a strategy for mitigating climate change, as the process allows for CO2 to be converted into industrially useful chemicals. The aim of this work is to study the influence of key variables on the performance of an experimental system for continuous electroreduction of CO2 to formate with a gas diffusion electrode (GDE) loaded with Sn. A 23 factorial design of experiments at different levels of current density (j), electrolyte flow rate/electrode area ratio (Q/A ratio) and GDE Sn load was followed. Higher rates and concentrations (i.e., 1.4·10−3 mol m−2 s−1 and 1348 mg L−1 with efficiencies of approximately 70%) were obtained with GDEs than with plate electrodes. The statistical design of experiments demonstrated that the Sn load had the most significant effect on rate and efficiency. However, despite these promising results, further research is required to optimize the process. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-05T19:11:25.124982-05:
      DOI: 10.1002/aic.14544
       
  • Partial oxidation of methane in hollow‐fiber membrane reactors based
           on alkaline‐earth metal‐free CO2‐tolerant oxide
    • Authors: Yanying Wei; Qing Liao, Zhong Li, Haihui Wang, Armin Feldhoff, Juergen Caro
      Pages: n/a - n/a
      Abstract: The U‐shaped alkaline‐earth metal‐free CO2‐stable oxide hollow‐fiber membranes based on (Pr0.9La0.1)2(Ni0.74Cu0.21Ga0.05)O4+δ (PLNCG) are prepared by a phase‐inversion spinning process and applied successfully in the partial oxidation of methane (POM) to syngas. The effects of temperature, CH4 concentration and flow rate of the feed air on CH4 conversion, CO selectivity, H2/CO ratio, and oxygen permeation flux through the PLNCG hollow‐fiber membrane are investigated in detail. The oxygen permeation flux arrives at approximately 10.5 mL/min cm2 and the CO selectivity is higher than 99.5% with a CH4 conversion of 97.0% and a H2/CO ratio of 1.8 during 140 h steady operation. The spent hollow‐fiber membrane still maintains a dense microstructure and the Ruddlesden‐Popper K2NiF4‐type structure, which indicates that the U‐shaped alkaline‐earth metal‐free CO2‐tolerant PLNCG hollow‐fiber membrane reactor can be steadily operated for POM to syngas with good performance. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-05T19:00:05.327276-05:
      DOI: 10.1002/aic.14540
       
  • A 2‐D observer to estimate the reaction rate in a stopped flow fixed
           bed reactor for gas phase olefin polymerization
    • Authors: Barbara Browning; Nida Sheibat‐Othman, Isabelle Pitault, Timothy F. L. McKenna
      Pages: n/a - n/a
      Abstract: A two‐dimensional high gain observer has been constructed to estimate the reaction rate parameters in a laboratory scale stopped flow fixed bed reactor for gas phase ethylene polymerization. The observer is based on the heat balances of a validated model of the reactor and the measured variable is the outlet temperature of the fixed bed. To create an observable system of equations, the polymerization rate is considered in two parts, an activation energy term and a lumped parameter. The effective radial conductivity in the fixed bed and the heat‐transfer coefficient at the wall are considered separately. The polymerization rate is calculated from the observer results and is in good agreement with the measured data and calculated values. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-05T18:58:57.64543-05:0
      DOI: 10.1002/aic.14538
       
  • Selective hydrogenation of nitriles to imines over a multifunctional
           heterogeneous Pt catalyst
    • Authors: Jilan Long; Biaolin Yin, Yingwei Li, Lianjie Zhang
      Pages: n/a - n/a
      Abstract: Imines and their derivatives are versatile synthetic intermediates for the industrial preparation of both bulk and fine chemicals and for pharmaceuticals, but preparing these compounds efficiently through direct hydrogenation of nitriles are hindered by overhydrogenation to secondary amines. Here we report a highly efficient multifunctional catalyst system for selective hydrogenation coupling of nitriles to secondary imines using a heterogeneous Pt catalyst that was deposited on a nickel‐based metal‐organic framework (MOF) containing DABCO. The catalyst showed excellent synergy in promoting the hydrogenation of a variety of nitriles, giving significantly improved activity and selectivity (up to >99% yield) even under atmospheric pressure of H2. It is suggested that the Lewis base (DABCO) sites on the Ni‐MOF inhibit further hydrogenation of the imines. The influence of H2 pressure, reactant concentration, stirring speed, and reaction temperature was investigated. The kinetics and mechanism of hydrogenation of benzonitrile (BN) by the Pt/Ni‐MOF catalyst has been studied. The reaction showed a first‐order dependence on both BN concentration and H2 pressure. A kinetic model was proposed based on the mechanism of nitriles hydrogenation and compared with experimental observations. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-05T18:34:37.838763-05:
      DOI: 10.1002/aic.14545
       
  • Ni/CaO‐Al2O3 bifunctional catalysts for sorption‐enhanced
           steam methane reforming
    • Authors: Pan Xu; Zhiming Zhou, Changjun Zhao, Zhenmin Cheng
      Pages: n/a - n/a
      Abstract: Ni/CaO‐Al2O3 bifunctional catalysts with different CaO/Al2O3 mass ratios were prepared by a sol–gel method and applied to the sorption‐enhanced steam methane reforming (SESMR) process. The catalysts consisted mainly of Ni, CaO and Ca5Al6O14. The catalyst structure depended strongly on the CaO/Al2O3 mass ratio, which in turn affected the CO2 capture capacity and the catalytic performance. The catalyst with a CaO/Al2O3 mass ratio of 6 or 8 possessed the highest surface area, the smallest Ni particle size, and the most uniform distribution of Ni, CaO, and Ca5Al6O14. During 50 consecutive SESMR cycles at a steam/methane molar ratio of 2, the thermodynamic equilibrium was achieved using the catalyst with a CaO/Al2O3 mass ratio of 6, and H2 concentration profiles for all the 50 cycles almost overlapped, indicating excellent activity and stability of the catalyst. Moreover, a high CO2 capture capacity of 0.44 gCO2/gcat was maintained after 50 carbonation–calcination cycles, being almost equal to its initial capacity (0.45 gCO2/gcat). © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-05T18:21:41.748017-05:
      DOI: 10.1002/aic.14543
       
  • On the tuning of predictive controllers: Impact of disturbances,
           constraints, and feedback structure
    • Authors: Benjamin P. Omell; Donald J. Chmielewski
      Pages: n/a - n/a
      Abstract: The impact of problem formulation modifications on predictive controller tuning is investigated. First, the proposed tuning method is shown to adapt to disturbance characteristic changes and thus, takes full economic advantage of the scenario. The second topic concerns point‐wise‐in‐time constraints and the impact of constraint infeasibility. Specifically, we shift the tuning question from selection of nonintuitive weighting matrix parameters to that of a few key parameters and results in a rather intuitive trade‐off between expected profit and expected constraint violations. Finally, we show that simple modifications will allow for the consideration of various feedback structures, including computational delay and partial state information. The overall conclusions of the work are that the results of the automated algorithm will help build an intuitive understating of the dynamics of the process and ultimately result in a higher level trade‐off between profit and constraint observance. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-03T10:48:31.101905-05:
      DOI: 10.1002/aic.14529
       
  • An approach to mechanistic event recognition applied on monitoring organic
           matter depletion in SBRs
    • Authors: Mariano N. Cruz Bournazou; Stefan Junne, Peter Neubauer, Tilman Barz, Harvey Arellano‐Garcia, Costas Kravaris
      Pages: n/a - n/a
      Abstract: A fundamental practice in process engineering is monitoring the state dynamics of a system. Unfortunately, observability of some states is related to high costs, time, and efforts. The mechanistic event recognition (MER) aims to detect an event (defined as a change of the system with specific significance to the operation of the process) that cannot be directly observed but has some predictable effect on the dynamics of the systems. MER attempts to apply fault diagnosis techniques using mechanistic “recognition” models to describe the process. A systematic method for building recognition models using optimal experimental design tools is presented. As proof of concept, the MER approach to detect organic matter depletion in sequencing batch reactors, measuring only ammonia, dissolved oxygen, and nitroxides is applied. The event, that is, consumption of organic matter to a level below 50 gCOD/m3, was successfully detected even though microbial activity is known to continue after organic matter depletion. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-02T21:52:27.396596-05:
      DOI: 10.1002/aic.14536
       
  • Mathematical modeling of the partial hydrogenation of vegetable oil in a
           monolithic stirrer reactor
    • Authors: Diego E. Boldrini; Daniel E. Damiani, Gabriela M. Tonetto
      Pages: n/a - n/a
      Abstract: Experimental and theoretical studies on the partial hydrogenation of vegetable oil in a monolithic stirrer reactor are reported. A complete mathematical model of the reactor was developed, including hydrogenation and isomerization kinetics, catalyst deactivation, external gas–liquid and liquid–solid as well as internal mass transfer. The experimental studies were carried out in a Pd/Al2O3/Al monolithic stirrer reactor, at a wide range of temperatures (353–373 K), pressures (414–552 kPa), and catalyst loadings (0.00084–0.00527 kgPd,exp m−3). Based on this model, simulated data can be used to evaluate the catalyst (Pd/Al2O3/Al) and the hydrogenation process in consecutive catalytic tests under different operating conditions. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-02T21:17:53.267086-05:
      DOI: 10.1002/aic.14539
       
  • Numerical investigation of monodisperse granular flow through an inclined
           rotating chute
    • Authors: Sushil S. Shirsath; Johan T. Padding, J. A. M. (Hans) Kuipers, Tim W. J. Peeters, Herman J. H. Clercx
      Pages: n/a - n/a
      Abstract: A discrete element model of spherical glass particles flowing down a rotating chute is validated against high quality experimental data. The simulations are performed in a corotating frame of reference, taking into account Coriolis and centrifugal forces. In view of future extensions aimed at segregation studies of polydisperse granular flows, several validation steps are required. In particular, the influence of the interstitial gas, a sensitivity study of the collision parameters, and the effect of system rotation on particle flow is investigated. Shirsath et al. have provided the benchmark laboratory measurements of bed height and surface velocities of monodisperse granular flow down an inclined rotating chute. With a proper choice of the friction coefficients, the simulations show very good agreement with our experimental results. The effect of interstitial gas on the flow behavior is found to be relatively small for 3‐mm granular particles. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-06-30T14:45:22.167474-05:
      DOI: 10.1002/aic.14535
       
  • Hydrodynamics and reactor performance evaluation of a high flux
           gas‐solids circulating fluidized bed downer: Experimental study
    • Authors: Chengxiu Wang; Shahzad Barghi, Jesse Zhu
      Pages: n/a - n/a
      Abstract: Reactor performance of a high flux circulating fluidized bed (CFB) downer is studied under superficial gas velocities of 3–7 m/s with solids circulation rate up to 300 kg/m2s using ozone decomposition reaction. Results show that the reactant conversion in the downer is closely related to the hydrodynamics, with solids holdup being the most influential parameter on ozone decomposition. High degree of conversion is achieved at the downer entrance region due to strong gas‐solids interaction as well as higher solids holdup and reactant concentration. Ozone conversion increases with the increase of solids circulation rate and/or the decrease of superficial gas velocity. Overall conversion in the CFB downer is less than but very close to that in an ideal plug flow reactor indicating a good reactor performance in the downer because of the nearly “ideal” hydrodynamics in downer reactors. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-06-30T09:27:39.882057-05:
      DOI: 10.1002/aic.14534
       
  • Kinetics of CO2 absorption into a novel
           1‐diethylamino‐2‐propanol solvent using
           stopped‐flow technique
    • Authors: Helei Liu; Zhiwu Liang, Teerawat Sema, Wichitpan Rongwong, Chen Li, Yanqing Na, Raphael Idem, Paitoon Tontiwachwuthikul, Raphael Idem, Paitoon Tontiwachwuthikul
      Pages: n/a - n/a
      Abstract: A stopped‐flow apparatus was used to measure the kinetics of carbon dioxide (CO2) absorption into aqueous solution of 1‐diethylamino‐2‐propanol (1DEA2P) in terms of observed pseudo‐first‐order rate constant (ko) and second‐order reaction rate constant (k2), in this work. The experiments were conducted over a 1DEA2P concentration range of 120–751 mol/m3, and a temperature range of 298–313 K. As 1DEA2P is a tertiary amine, the base‐catalyzed hydration mechanism was, then, applied to correlate the experimental CO2 absorption rate constants obtained from stopped‐flow apparatus. In addition, the pKa of 1DEA2P was experimentally measured over a temperature range of 278–333 K. The Brønsted relationship between reaction rate constant (obtained from stopped‐flow apparatus) and pKa was, then, studied. The results showed that the correlation based on the Brønsted relationship performed very well for predicting the absorption rate constant with an absolute average deviation of 5.2%, which is in an acceptable range of less than 10%. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-06-25T14:31:44.095041-05:
      DOI: 10.1002/aic.14532
       
  • Ionic liquid recovery alternatives in ionic liquid‐based
           three‐phase partitioning (ILTPP)
    • Authors: Enrique Alvarez‐Guerra; Angel Irabien, Sónia P. M. Ventura, João A. P. Coutinho
      Pages: n/a - n/a
      Abstract: Ionic liquid‐based three‐phase partitioning (ILTPP) is a promising technique to recover high‐added value proteins at the liquid–liquid interface. Its economic and environmental performance highly depends on the net ionic liquid consumption. Alternatives to maximize the fraction of ionic liquid that can be recycled are studied. It is demonstrated that the addition of extra salt, previously proposed in literature, has a very limited effect on ionic liquid recovery for relatively high protein concentrations in the feed stream, and that it may even lead to an increase of the ionic liquid losses under certain conditions. However, small additions of salt are shown to be effective and profitable from an economic point of view. Vacuum evaporation is shown to allow for the complete ionic liquid and salt recovery, reinforcing the sustainability and viability of ILTPP processes. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-06-24T15:49:16.942556-05:
      DOI: 10.1002/aic.14530
       
  • Kinetic parameter estimation of HDPE slurry process from molecular weight
           distribution: Estimability analysis and multistep methodology
    • Authors: Chen Zhang; Zhijiang Shao, Xi Chen, Zhen Yao, Xueping Gu, Lorenz T. Biegler
      Pages: n/a - n/a
      Abstract: This study addresses kinetic parameter estimation for a high‐density polyethylene (HDPE) slurry process based on fitting molecular weight distributions (MWDs). From the process model, we conduct an estimability analysis by assessing the relative sensitivity between output variables and kinetic parameters as well as confidence intervals. This determines which parameters can be estimated. Conversely, a major challenge remains with the solution of an ill‐conditioned parameter estimation problem with MWD as the output variable. To overcome the convergence difficulties with the associated problem, we develop a novel multistep methodology where we first obtain MWD parameters by matching to data and then estimate kinetic parameters by matching to the regressed MWD parameters. Computational results and eigenvalue analysis show this multistep methodology separates an ill‐conditioned problem into two well‐conditioned subproblems. Moreover, we consider simulation‐based and industrial HDPE case studies. These results demonstrate the applicability, potential, and efficiency of this solution procedure. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-06-24T15:39:37.892284-05:
      DOI: 10.1002/aic.14527
       
  • A mechanistic growth model for inorganic crystals: Growth mechanism
    • Authors: Preshit Dandekar; Michael F. Doherty
      Abstract: Inorganic crystals grown from solution find wide application. We present a mechanistic growth model based on the spiral growth mechanism that operates at low supersaturation on inorganic crystal surfaces. The long-range electrostatic interactions on inorganic crystal surfaces are captured by methods developed in our previous paper1. The interactions of kink site growth units with the solvent molecules partially determine the growth kinetics. Relevant experimental parameters are systematically accounted for in the expression for the kink incorporation rate along step edges on the crystal surfaces. The growth model accurately predicts the asymmetric growth spirals on the (101¯4) surface of calcite crystals. The effect of supersaturation and ionic activity ratio on the step velocities of the acute and obtuse spiral edges is correctly captured. This model can be used to predict the shapes of solution grown inorganic crystals and to engineer the growth process to design inorganic solids with functionally desirable shapes. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-05-28T08:30:09.968276-05:
      DOI: 10.1002/aic.14513
       
 
 
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