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ENGINEERING (1172 journals)            First | 1 2 3 4 5 6 7 8 | Last

Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access  
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 4)
Biomedical Engineering     Hybrid Journal   (Followers: 10)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 13)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 16)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 15)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 7)
Biomedical Science and Engineering     Open Access   (Followers: 1)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 1)
Biotechnology Progress     Hybrid Journal   (Followers: 20)
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription  
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   (Followers: 1)
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: 15)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 13)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 4)
Case Studies in Thermal Engineering     Open Access   (Followers: 1)
Catalysis Communications     Hybrid Journal   (Followers: 5)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 7)
Catalysis Science and Technology     Free   (Followers: 5)
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: 2)
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 2)
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: 11)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 10)
City, Culture and Society     Hybrid Journal   (Followers: 19)
Clay Minerals     Full-text available via subscription   (Followers: 10)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Clinical Science     Full-text available via subscription   (Followers: 8)
Coal Science and Technology     Full-text available via subscription   (Followers: 4)
Coastal Engineering     Hybrid Journal   (Followers: 9)
Coastal Engineering Journal     Hybrid Journal   (Followers: 2)
Coatings     Open Access   (Followers: 2)
Cogent Engineering     Open Access   (Followers: 1)
Cognitive Computation     Hybrid Journal   (Followers: 3)
Color Research & Application     Hybrid Journal   (Followers: 1)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 6)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 11)
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: 14)
Composite Interfaces     Hybrid Journal   (Followers: 4)
Composite Structures     Hybrid Journal   (Followers: 156)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 120)
Composites Part B : Engineering     Hybrid Journal   (Followers: 139)
Composites Science and Technology     Hybrid Journal   (Followers: 103)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access   (Followers: 1)
Computational Geosciences     Hybrid Journal   (Followers: 13)
Computational Optimization and Applications     Hybrid Journal   (Followers: 6)
Computational Science and Discovery     Full-text available via subscription  
Computational Water, Energy, and Environmental Engineering     Open Access   (Followers: 3)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 7)
Computer Science and Engineering     Open Access   (Followers: 8)
Computers & Geosciences     Hybrid Journal   (Followers: 8)
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: 8)
Computing and Visualization in Science     Hybrid Journal   (Followers: 3)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 13)
Conciencia Tecnologica     Open Access   (Followers: 1)
Concurrent Engineering     Hybrid Journal   (Followers: 4)
Conference Proceedings - Lucian Blaga University Sibiu     Open Access  
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: 32)
Control Theory and Informatics     Open Access   (Followers: 4)
Corrosion Science     Hybrid Journal   (Followers: 22)
CT&F Ciencia, Tecnologia y Futuro     Open Access  
Current Applied Physics     Full-text available via subscription   (Followers: 4)
Dams and Reservoirs     Hybrid Journal   (Followers: 4)
Data Handling in Science and Technology     Full-text available via subscription   (Followers: 3)
Design Journal : An International Journal for All Aspects of Design     Hybrid Journal   (Followers: 23)

  First | 1 2 3 4 5 6 7 8 | Last

Journal Cover   AIChE Journal
  [SJR: 1.098]   [H-I: 104]   [23 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  [1597 journals]
  • Calculation of the phase envelope of multicomponent mixtures with the bead
           spring method
    • Authors: Ilias K. Nikolaidis; Georgios C. Boulougouris, Loukas D. Peristeras, Ioannis G. Economou
      Abstract: In this work, we propose a robust numerical scheme for the calculation of constant composition (isoplethic) phase diagrams of complex multicomponent mixtures. The scheme refers to the sequential calculation of the phase envelope of a mixture by guiding the estimation for the equilibrium curve via the introduction of a “spring” that sets the slope value of the modified tangent plane distance with respect to either temperature or pressure. A simple variation of the proposed method allows direct estimation of the Cricondentherm and/or Cricondenbar points, thus avoiding the calculation of the entire phase diagram. We provide extensive tests of the proposed scheme for different types of phase diagrams, using both cubic and higher order equations of state. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-30T19:44:42.432655-05:
      DOI: 10.1002/aic.15064
  • A systematic comparison of PCA‐based statistical process monitoring
           methods for high‐dimensional, time‐dependent processes
    • Authors: Tiago Rato; Eric Schmitt, Bart De Ketelaere, Mia Hubert, Marco Reis
      Abstract: High‐dimensional and time‐dependent data pose significant challenges to Statistical Process Monitoring (SPM). Most of the high‐dimensional methodologies to cope with these challenges rely on some form of Principal Component Analysis (PCA) model, usually classified as non‐adaptive and adaptive. Non‐adaptive methods include the static PCA approach and Dynamic PCA for data with autocorrelation. Methods, such as Dynamic PCA with Decorrelated Residuals, extend Dynamic PCA to further reduce the effects of autocorrelation and cross‐correlation on the monitoring statistics. Recursive PCA and Moving Window PCA, developed for non‐stationary data, are adaptive. These fundamental methods will be systematically compared on high‐dimensional, time‐dependent processes (including the Tennessee Eastman benchmark process) to provide practitioners with guidelines for appropriate monitoring strategies and a sense of how they can be expected to perform. The selection of parameter values for the different methods is also discussed. Finally, the relevant challenges of modeling time‐dependent data are discussed, and areas of possible further research are highlighted. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-30T18:42:10.034627-05:
      DOI: 10.1002/aic.15062
  • Engineering uniform nanocrystals: Mechanism of formation and
           self‐assembly into bimetallic nanocrystal superlattices
    • Abstract: The preparation of metal nanocrystals with precise and tunable size is of great interest for many applications. Following previous reports on the synthesis of monodisperse Ni, Pd and Pt nanocrystals, we here show that the narrow size distributions are the result of an optimized combination of surfactants that play a dynamic, synergistic role in stabilizing the particles at different stages (nucleation, growth) of their preparation. This dynamical process allows the temporal separation of nucleation and growth responsible for the narrow size distributions achievable with this heat‐up method. Finally, the uniform nanocrystals are exploited in the preparation of binary nanocrystals superlattices (BNSLs) entirely based on metal components, with promising applicability in the fields of catalysis, sensing and optics. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-30T18:41:13.903542-05:
      DOI: 10.1002/aic.15063
  • Microstructured Al‐fiber@meso‐Al2O3@Fe‐Mn‐K
           Fischer‐Tropsch Catalyst for Lower Olefins
    • Authors: Lupeng Han; Chunzheng Wang, Guofeng Zhao, Ye Liu, Yong Lu
      Abstract: A thin‐sheet Al‐fiber@meso‐Al2O3@Fe‐Mn‐K catalyst is developed for the mass/heat‐transfer limited Fischer‐Tropsch synthesis to lower olefins (FTO), delivering a high FTY of 206.9 μmolCO gFe−1 s−1 at 90% CO conversion with 40% selectivity to C2‐C4 olefins under optimal reaction conditions (350°C, 4.0 MPa, 10000 mL/(g·h)). A microfibrous structure consisting of 10 vol% 60‐μm Al‐fiber and 90 vol% voidage undergoes a steam‐only‐oxidation and calcination to create 0.6 μm mesoporous γ‐Al2O3 shell along with the Al‐fiber core. Active components of Fe and Mn as well as additives (K, Mg, or Zr) are then placed into the pore surface of γ‐Al2O3 shell of the Al‐fiber@meso‐Al2O3 composite by incipient wetness impregnation method. Neither Mg‐modified nor Zr‐modified structured catalyst yields better FTO results than K‐modified one, because of their lower reducibility, poorer carbonization property and fewer basicity. The favorable heat/mass transfer characteristics of this new approach are also discussed. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-30T18:39:05.60909-05:0
      DOI: 10.1002/aic.15061
  • Equation‐oriented optimization of process flowsheets with
           dividing‐wall columns
    • Authors: Richard C. Pattison; Akash M. Gupta, Michael Baldea
      Abstract: We present a new modeling approach for dividing‐wall columns (DWCs) that is amenable to equation‐oriented flowsheet simulation and optimization. The material, equilibrium, summation, and heat (MESH) equations describing a DWC are highly coupled and nonlinear, making DWC‐based process flowsheets challenging to simulate. Design optimization poses further challenges, typically requiring integer variables to select the number of column stages. To address these difficulties, we represent DWCs as networks of pseudo‐transient (differential‐algebraic) sub‐unit models. We show that these networks have the same steady state solution as the original (algebraic) MESH equations, but present significant numerical benefits. We then embed these models in a previously developed pseudo‐transient flowsheet modeling and optimization framework. We further reformulate the models to require only continuous decision variables when selecting the optimal number of stages during design optimization. To illustrate these concepts, we discuss the DWC‐based intensification of the dimethyl ether process. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-30T18:38:25.445688-05:
      DOI: 10.1002/aic.15060
  • A System‐Size Independent Validation of CFD‐DEM for
           Non‐Cohesive Particles
    • Authors: Casey Q. LaMarche; Peiyuan Liu, Kevin M. Kellogg, Alan Weimer, Christine M. Hrenya
      Abstract: For the first time, CFD‐DEM simulations of small‐scale fluidized beds are quantitatively validated against large‐scale experiments. Such validation is possible via the identification of a measurement independent of system size, namely defluidization. CFD‐DEM inputs (particle properties and operating conditions) are measured directly. Sphericity is found to be critical, even for highly‐spherical particles. This size‐independent method of validation is valuable since it allows for validation of CFD‐DEM models without restrictions on system sizes or particle sizes. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-29T09:36:23.304287-05:
      DOI: 10.1002/aic.15057
  • Morphology‐Dependent Electrocatalytic Activity of Nanostructured
           Pt/C Particles from Hybrid Aerosol–Colloid Process
    • Authors: Ratna Balgis; Aditya F. Arif, Takahiro Mori, Takashi Ogi, Kikuo Okuyama, Gopinathan M. Anilkumar
      Abstract: An optimum nanostructure and pore size of catalyst supports is very important in achieving high catalytic performances. In this instance, we evaluated the effects of various carbon nanostructures on the catalytic performances of carbon‐supported platinum (Pt/C) electrocatalysts experimentally and numerically. The Pt/C catalysts were prepared using a hybrid method involving the preparation of dense, hollow, and porous nanostructured carbon particle via aerosol spray pyrolysis followed by microwave‐assisted Pt deposition. Electrochemical characterization of the catalysts showed that the porous Pt/C catalyst gave the best performance; its electrochemical surface area was much higher, more than twice than those of hollow or dense Pt/C. The effects of pore size on electrocatalysis were also studied. The results showed the importance of a balance between meso‐ and macro‐pores for effective catalysis with a high charge transfer rate. A fluid flow model showed that good oxygen transport contributed to the catalytic activity. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-24T18:52:46.434568-05:
      DOI: 10.1002/aic.15059
  • Formation and Stability of String Phase in Polyamide 6/Polystyrene Blends
           in Confined Flow: Effects of Nanoparticles and Blend Ratio
    • Authors: Miqiu Kong; Yajiang Huang, Yadong Lv, Qi Yang, Guangxian Li
      Abstract: Influences of silica nanoparticles on the microstructural evolution of polyamide 6 (PA6)/polystyrene (PS) blends with varying blend ratios was investigated in confined shear flow. Hydrophilic silica nanoparticles were found to promote the formation of PA6 strings with excellent shape stability during shearing. It was ascribed to the promoted coalescence of PA6 droplets induced both by the significantly increased droplet viscoelasticity and confinement, and the reduced interfacial tension by adding silica nanoparticles. Additionally, the width and aspect ratio of droplets obtained by experiments were compared to the predictions of MM, M, SH, MMSH and mM models. Good agreements were found in the droplet width in blends with low nanoparticle concentrations, whereas the experimental aspect ratio showed a negative deviation to model predictions, which was attributed to the enhanced droplet viscoelasticity and the omitted droplet orientation angle in these models. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-24T18:51:22.427122-05:
      DOI: 10.1002/aic.15058
  • Thermal Coupling Links to Liquid‐only Transfer Streams: An
           Enumeration Method for New FTC Dividing Wall Columns
    • Authors: Gautham Madenoor Ramapriya; Mohit Tawarmalani, Rakesh Agrawal
      Abstract: Novel dividing wall columns (DWCs) can be obtained by converting thermal couplings to liquid‐only transfer streams. Here, we develop a simple four‐step method to generate a complete set of DWCs containing n‐2 dividing walls, for a given n‐component fully thermally coupled (FTC) distillation. Among the novel DWCs, some easy‐to‐operate DWCs possess the property that the vapor flow in every section of the DWC can be controlled during operation by means that are external to the column. We develop a simple method to enumerate all such easy‐to‐operate DWCs. We expect that the easy‐to‐operate DWCs can be operated close‐to‐optimality; leading to a successful industrial implementation of the n‐component (n≥3) FTC distillation in the form of a DWC. As an illustration, we show figures of all easy‐to‐operate DWCs with two dividing walls for the four‐component FTC distillation. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-24T12:26:21.956674-05:
      DOI: 10.1002/aic.15053
  • The role of microexplosions in flame spray synthesis for homogeneous
           nanopowders from low‐cost metal precursors
    • Abstract: One of the most versatile and rapid manufacturing processes for a variety of nanopowders is flame‐spray‐pyrolysis (FSP). The production costs of this scalable process are largely controlled by the raw materials, pushing for the utilization of low‐cost metal precursors. These, however, typically yield inhomogeneous products containing large particles up to micrometer size along with fine nanoparticles. Here we investigate the release mechanism of nitrate and carboxylate precursors from spray droplets by single droplet combustion experiments and thermogravimetric analysis. The results show that neither precursor evaporation nor choice of solvents are prerequisites for homogeneous nanopowders but droplet microexplosions with continuing combustion. It is shown that even low‐cost metal nitrates yield homogeneous nanopowders if precursors are formulated such that droplet microexplosions occur by internal superheating. The proposed precursor release mechanisms are verified with lab‐ and pilot‐scale FSP, demonstrating that single droplet combustion experiments can be employed to predict the product quality. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-19T10:47:47.176765-05:
      DOI: 10.1002/aic.15056
  • Process Fault Detection Using Time‐Explicit Kiviat Diagrams
    • Authors: Ray Wang; Thomas F. Edgara, Michael Baldeaa, Mark Nixon, Willy Wojsznis, Ricardo Dunia
      Abstract: Significant amounts of data are collected and stored during chemical process operations. The corresponding data sets are typically difficult to represent and analyze using traditional visualization methods. This paper introduces time‐explicit Kiviat diagrams as means to visualize the multi‐dimensional time series data acquired from plant operations. We then use this framework to build multivariate control charts for large scale time series data sets, and to develop a fault detection mechanism that lends itself to real‐time implementation. The proposed methodology is applied to an industrial case study as well as to data obtained from the Tennessee Eastman process simulator, showing very good performance. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-18T18:38:24.679205-05:
      DOI: 10.1002/aic.15054
  • Development of a Hybrid Shrinking‐Core Shrinking‐Particle
           Model for Entrained‐Flow Gasifiers
    • Authors: Pratik Pednekar; Debangsu Bhattacharyya, Job S. Kasule, Richard Turton, Raghunathan Rengaswamy
      Abstract: The slagging entrained‐flow gasifiers operate above the melting temperature of the ash. Since slag is highly non‐wetting on the surface of char (carbon) particles, it is likely that it will agglomerate into one or several slag droplets and some of these droplets can detach from the char particles. If the slag exists in the form of droplets on the char surface rather than as a solid shell around the unreacted char particle, a shrinking particle model (SPM) would be more physically realistic representation in comparison to the widely‐used shrinking core model (SCM). In the early section of the gasifier, the temperature remains below the ash melting temperature and therefore, the SCM is more appropriate in this region. With this motivation, a novel hybrid shrinking‐core shrinking‐particle (HSCSP) model has been developed. The model provides spatial profile of a number of important variables that are not available from the traditional SCM. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-18T18:37:43.015802-05:
      DOI: 10.1002/aic.15055
  • CFD‐DEM Modelling of Gas Fluidization of Fine Ellipsoidal Particles
    • Authors: J.Q. Gan; Z.Y. Zhou, A.B. Yu
      Abstract: Particle characteristics are important factors affecting gas fluidization. In this work, the effects of both particle size and shape on fluidization in different flow regimes are studied using the combined CFD‐DEM approach. The results are first analysed in terms of flow patterns and fluidization parameters such as pressure drop, minimum fluidization and bubbling velocities. The results show that with particle size decreasing, agglomerates can be formed for fine ellipsoidal particles. In particular, “chain phenomenon”, a special agglomerate, exists in expanded and fluidized beds for fine prolate particles, which is caused by the van der Waals force. The minimum fluidization velocity increases exponentially with the increase of particle size, and for a given size, it shows a “W” shape with aspect ratio. A correlation is established to describe the dependence of minimum fluidization velocity on particle size and shape. Ellipsoids have much higher minimum bubbling velocities and fluidization index than spheres. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-17T17:42:53.0607-05:00
      DOI: 10.1002/aic.15050
  • Quantitative Assessment of Fine‐Grid
           Kinetic‐Theory‐Based Predictions of Mean‐Slip in
           Unbounded Fluidization
    • Authors: W.D. Fullmer; C.M. Hrenya
      Abstract: The quantitative ability of a kinetic‐theory‐based, two‐fluid model is demonstrated in a clustering (unstable) gas‐solid system via highly‐resolved simulations. Unlike previous works, this assessment is validated against ideal CFD‐DEM data to minimize sources of discrepancy. Overall, good agreement in mean slip velocities is observed with relative errors less than 20% over a mean solids concentration range of 0.02–0.25. Local concentration gradient distributions are also studied, showing a distinct shift towards higher gradients at higher mean solids concentrations which is proposed as the bottleneck in obtaining grid‐independence rather than the cluster length scale. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-17T17:42:14.058854-05:
      DOI: 10.1002/aic.15052
  • Analysis of particle cloud height dynamics in a stirred tank
    • Authors: Matthias Eng; Rasmus Jonsson, Anders Rasmuson
      Abstract: Local and temporal variations of the particle cloud formed in a cylindrical mixing vessel were investigated experimentally. Different particle sizes (0.5mm, 1mm, 2mm) and volumetric concentration up to 20%vol were evaluated at different impeller speeds. The time‐averaged cloud height was linear with impeller frequency and with volume concentration. Suspensions with larger particles had a lower average cloud height, while the standard deviation for the temporal cloud height variation was larger. Two strong periodic phenomena were identified to be dominating the particle cloud height variations. The frequencies were linear with impeller speed, resulting in dimensionless frequencies of S1=0.02 – 0.03 and S2=0.05 – 0.06. The frequencies were affected by neither the particle size, nor the volumetric concentration. The amplitude showed no dependency on the particle size, but the S2 amplitude significantly decreases and S1 increases with increasing solid concentration. The results were compared to LES/DEM simulations and showed a fair agreement. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-17T17:41:39.352336-05:
      DOI: 10.1002/aic.15051
  • Novel graphical tool for the design of the heat integrated water
           allocation networks
    • Authors: Zuwei liao; Xiaodong Hong, Binbo Jiang, Jingdai Wang, Yongrong Yang
      Abstract: A new graphical tool has been developed for the HEN design of WAHEN. An ΔH‐F diagram is proposed to deal with the heat exchange matches. Non‐isothermal stream mixing and splitting can be achieved by the transformation of stream composite curve in the ΔH‐F diagram. A matching composite curve is proposed for the design of HEN with parallel structure. The structure of HEN can be simplified by adjusting the shape of the matching composite curve. Both small scale and large scale examples are illustrated. Results show that the proposed method is as good as the previous methods for small scale problem, while it gets a better result for large scale problem. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-16T11:21:45.399841-05:
      DOI: 10.1002/aic.15049
  • In Situ Metal Doping during Modified Anodization Synthesis of Nb2O5 with
           Enhanced Photoelectrochemical Water Splitting
    • Authors: Chenyan Hu; Wey Yang Teoh, Shulin Ji, Changhui Ye, Akihide Iwase
      Abstract: A new technique of in situ doping of alkali metal (Li+, Na+, K+, Rb+, and Cs+) in Nb2O5 was showcased by the modified anodization of Nb foils at high frequency, negative‐to‐positive pulsed voltage. At the optimized dopant concentration and synthesis condition, the doped‐Nb2O5 shows 2‐fold enhancement in photoelectrochemical water splitting efficiencies compared to the undoped Nb2O5 electrode, as a result of improved charge carrier density and enhanced surface charge transfer. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-16T11:05:37.49991-05:0
      DOI: 10.1002/aic.15048
  • Integrating compressors into heat exchanger networks above ambient
    • Authors: Chao Fu; Truls Gundersen
      Abstract: Heat from compression processes is normally wasted to cooling water due to its low temperature or concerns about operability. The recoverable amount of heat can be enhanced by increasing the operating temperature of compressors. However, the compression work also increases under this condition. The integration of compressors into heat exchanger networks is complex since both heat and work are involved, and the role of streams (as hot or cold streams), the utility demand, and the location of pinch points may change. This paper presents a systematic graphical design procedure for above ambient heat exchanger network design including compressors. The objective is to minimize exergy consumption in order to balance the complex heat‐work trade‐offs involved. Four theorems are proposed as the basis of the design procedure with certain well‐defined assumptions. It is found that the compression should be performed at pinch or ambient temperatures in order to achieve minimum exergy consumption. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-15T16:30:04.053626-05:
      DOI: 10.1002/aic.15045
  • Long‐term testing of a high temperature polymer electrolyte membrane
           fuel cell: The effect of reactant gases
    • Authors: F. Javier Pinar; Nadine Pilinski, Peter Wagner
      Abstract: The investigations have been conducted with different oxidants and fuels with the aim of determining the state‐of‐the‐art of commercially available HT‐PEMFC based on PBI for its application in CHP systems. The fuel cell test carried out with synthetic reformate (‐63 μV/h) showed an increase of anode charge and mass transfer resistances. This behaviour has suggested that CO may be generated from the CO2 included in the synthetic reformate via reverse water gas shift reaction. The fuel cell test carried out with pure O2 developed the highest degradation rates (‐70 μV/h) due to fast oxidative degradation of MEA materials such as cathode catalyst and membrane. Fuel cell operation with H2/air exhibited the lowest degradation rates (‐57 μV/h) and it requires longer investigating times to identify the different degradation mechanisms. Moreover, fuel cell tests carried out with air suggested longer break‐in procedures to complete catalyst activation and redistribution of electrolyte. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-15T16:25:02.126177-05:
      DOI: 10.1002/aic.15044
  • On the length to diameter ratio of extrudates in catalyst technology I.
           modeling catalyst breakage by impulsive forces
    • Authors: Jean W. L. Beeckman; Natalie A. Fassbender, Theodore E. Datz
      Abstract: Natural or forced catalyst extrudate breakage is an important phenomenon during catalyst manufacture. Here we develop a two parameter model for predicting the reduction in the length to diameter ratio of catalyst extrudates due to breakage by impulsive forces as experienced in a laboratory drop test. In Part II we will show that both parameters can be correlated with the strength of the extrudates and the severity of the drop test. For breakage by impulsive forces, the model reveals that extrudates are reduced in length to diameter ratio according to a pseudo‐second order break law. Also, a tie‐in exists with the well‐known Golden Ratio that is famous for its inherent esthetic value. Applying the model to cases of “severity sequencing” and “severity conditioning” reveals the non‐linear behavior of the length to diameter ratio and yields results that are often non‐intuitive and hard to get without this engineering analysis. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-15T16:23:40.698545-05:
      DOI: 10.1002/aic.15046
  • Dispersion of feed spray in a new type of FCC feed injection scheme
    • Authors: Zihan Yan; Yiping Fan, Zhao Wang, Sheng Chen, Chunxi Lu
      Abstract: A new type of FCC feed injection scheme in which the feed is injected downwards into the riser to realize a countercurrent contact of feed oil with catalyst particles is put forward. The dispersion of feed spray and flow behaviors of particles in the new type of feed injection scheme are investigated via a large scale cold‐riser model. Experimental results show that the proposed scheme provides a better contact of feed oil with catalyst particles. Furthermore, the centerline equations of both the feed main flow and the secondary flow in the riser are given by introducing a density correction coefficient. The momentum‐ratio of the secondary flow to the main flow is then obtained and the trajectory of the feed main jets as well as the secondary flow is estimated by the centerline equation. The computed results give a reasonable agreement with the experimental data. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-15T16:23:07.545803-05:
      DOI: 10.1002/aic.15047
  • Stereo Imaging of Crystal Growth
    • Authors: Cai Y. Ma; Jing J. Liu, Xue Z. Wang
      Abstract: A methodology that directly images the full three‐dimensional shape of crystals within a crystalliser is reported. It is based on the mathematical principle that if the two‐dimensional images of an object are obtained from two or more different angles, the full three‐dimensional crystal shape could be reconstructed. A prototype instrument is built and proof of concept study carried out to demonstrate the potentials in using the system for three‐dimensional measurement of crystal shape and shape distribution. It is our belief that 3D measurement of crystal shape represents a significant step forward from existing work of 2D measurement of crystal morphology and is potentially of great significance to research towards closed‐loop control of crystal morphology. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-11T18:27:32.720601-05:
      DOI: 10.1002/aic.15041
  • A Novel Framework for Integrating Data Mining with Control Loop
           Performance Assessment
    • Authors: Laya Das; Babji Srinivasan, Raghunathan Rengaswamy
      Abstract: Data driven control loop performance assessment techniques assume that the data being analysed correspond to single plant‐controller configuration. However in an industrial setting where processes are affected due to the presence of feedstock variability and drifts, the plant‐controller configuration changes with time. Also, user‐defined benchmarking of control loops (common in industrial plants) requires that the data corresponding to optimal operation of the controller be known. However such information might not be available beforehand in which case it is necessary to extract the same from routine plant operating data. We propose a technique that addresses these fundamental requirements for ensuring reliable performance assessment. The proposed technique performs a recursive binary segmentation of the data and makes use of the fact that changes in controller settings translate to variations in plant output for identifying regions corresponding to single plant‐controller configurations. The statistical properties of the data in each such window are then compared with the theoretically expected behaviour to extract the data corresponding to optimal configuration. This approach has been applied on: (i) raw plant output (ii) Hurst exponent and (iii) minimum variance index of the process data. Simulation examples demonstrate the applicability of proposed approach in industrial settings. A comparison of the three routes is provided with regard to the amount of data needed and the efficacy achieved. Key results are emphasised and a framework for applying this technique is described. This tool is of significance to industries interested in an automated analysis of large scale control loop data for multiple process variables that is otherwise left un‐utilised. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-11T18:26:22.71426-05:0
      DOI: 10.1002/aic.15042
  • Breakup Dynamics for High‐viscosity Droplet Formation in a
           Flow‐Focusing Device: Symmetrical and Asymmetrical Ruptures
    • Authors: Wei Du; Taotao Fu, Chunying Zhu, Youguang Ma, Huai Z. Li
      Abstract: The breakup mechanism of high‐viscosity thread for droplet formation in a flow‐focusing device is investigated using a high‐speed digital camera. Aqueous solution of 89.5%‐glycerol is used as the dispersed phase, while silicone oil as the continuous phase. The breakup process of the dispersed thread presents two categories: symmetrical rupture and asymmetrical rupture. Furthermore, the rupture behavior could be divided into two stages: the squeezing stage controlled by the squeezing pressure and the pinch‐off stage controlled by viscous stresses of both phases and surface tension. Specifically, it suggests that the differences in the shape of the liquid‐liquid interface and the dynamics in the two breakup processes are caused by the disparity of the strain field at the point of detachment. Moreover, the thinning rate and the dynamics of the dispersed thread change with the viscosity of the continuous phase, but are less dependent of the flow rate of the continuous phase. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-11T18:25:20.920618-05:
      DOI: 10.1002/aic.15043
  • Optimal Flowsheet Configuration of a Polymerization Process with Embedded
           Molecular Weight Distributions
    • Authors: Chen Zhang; Zhijiang Shao, Xi Chen, Xueping Gu, Lianfang Feng, Lorenz T. Biegler
      Abstract: We consider the optimal reactor network synthesis of a polymerization process with detailed molecular weight distributions (MWDs). Based on an industrial high‐density polyethylene (HDPE) slurry process model including an embedded MWD, a fully connected process superstructure of continuous stirred tank reactors (CSTRs) is established through the introduction of splitters. Using this generalized superstructure as a basis, two nonlinear programming (NLP) problem formulations, which simultaneously maximize the monomer conversion and minimize the deviation between the calculated and target MWDs, are developed by applying multiobjective optimization (MO) methods. Different optimal flowsheet configurations are generated by systematically manipulating a set of continuous decision variables. Several case studies that consider different specifications on MWD are conducted to illustrate the effectiveness and efficiency of the proposed synthesis approach. Numerical results show that the optimal flowsheet configurations overcome the limitations of conventional reactor network structures and help to increase reactor productivity at the desired product quality. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-11T18:07:20.954002-05:
      DOI: 10.1002/aic.15040
  • Sustainability Decision Support Framework for Industrial System
    • Authors: Jingzheng Ren; Di Xu, Huan Cao, Shun'an Wei, Michael Evan Goodsite, Lichun Dong
      Abstract: This study proposed a multi‐criteria decision making methodology for the sustainability prioritization of industrial systems. The methodology incorporates a fuzzy Analytic Hierarchy Process method that allows the users to assess the soft criteria by using linguistic terms. A fuzzy Analytic Network Process method is used to calculate the weights of each criterion, which can tackle the interdependencies and interactions among the criteria. The Preference Ranking Organization Method for Enrichment Evaluation approach is used to prioritize the sustainability sequence of the alternative systems. Moreover, a sensitivity analysis method was developed to investigate the most critical and sensitive criteria. The developed methodology was illustrated by a case study to rank the sustainability of five alternative hydrogen production technologies. The advantages of the developed methodology over the previous approaches were demonstrated by comparing the results determined by the proposed framework with those determined by using the pervious approaches. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-09T17:49:53.722672-05:
      DOI: 10.1002/aic.15039
  • A new insight to validation of local composition models in binary mixtures
           using molecular dynamic simulation
    • Authors: Ali Haghtalab; Jaber Yousefi Seyf
      Abstract: A computational method based on molecular dynamics (MD) simulation is developed to predict the interaction parameters in local composition (LC) models such as Wilson, NRTL, and UNIQUAC applicable in vapor liquid equilibrium calculations so that LC models are validated. The five binary mixtures of water‐acetonitrile, water‐isopropanol, methanol‐chloroform, acetone‐cyclohexane, and meta xylene‐benzene were simulated. The MD simulations are carried out using the COMPASS force field and all ranges of radial distribution function (RDF) are considered. In addition, the interaction parameters are determined by optimization through experimental data and are compared with the MD results. The interaction parameters are calculated through RDF where the effective radius is investigated by experimental data. The present results demonstrate that interaction parameters are composition dependent which are best fitted by a third‐order polynomial relation. Based on the deviation in the activity coefficients, the results of the UNIQUAC model are more accurate than Wilson and NRTL models. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-09T17:48:59.087977-05:
      DOI: 10.1002/aic.15038
  • A new dynamic model of crude oil fouling deposits and its application to
           the simulation of fouling‐cleaning cycles
    • Abstract: Modelling of crude oil fouling in heat exchangers has been traditionally limited to a description of the deposit as a thermal resistance. However, consideration of the local change in thickness and the evolution of the properties of the deposit due to ageing or changes in foulant composition is important to capture the thermal and hydraulic impact of fouling. A dynamic, distributed, first‐principles model of the deposit is presented that considers it as a multi‐component varying‐thickness solid undergoing multiple reactions. For the first time, full cleaning, partial cleaning and fouling resumption after cleaning can be simulated in any order with a single deposit model. The new model, implemented within a single tube framework, is demonstrated in a case study where various cleaning actions are applied following a period of organic deposition. It is shown that complete mechanical cleaning and chemical cleaning of different extent, according to a condition‐based efficacy, can be seamlessly simulated. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-09T17:47:27.379576-05:
      DOI: 10.1002/aic.15036
  • Kinetic modeling strategy for an exothermic multiphase reactor system:
           application to vegetable oils epoxidation by using Prileschajew method
    • Abstract: Epoxidation of cottonseed oil by peroxyformic acid (PFA) was studied in a semi‐batch calorimeter. This liquid‐liquid reaction system is composed of different exothermic steps. Thus, a kinetic modeling strategy to diminish the number of parameters to estimate was developed by investigating each reaction system: PFA synthesis and decomposition, ring‐opening and epoxidation. A thermal study was conducted by determining heat capacity of the different organic species, and by analyzing the evolution of global heat transfer coefficient with the reaction extent. The epoxidation reaction was performed in a semi‐batch reactor under isoperibolic mode within an initial temperature range of 50‐70°C, an organic phase of 30‐34 wt.%, a formic acid molar flow rate of 0.02‐0.05 mol/min and an addition time of 25‐50 min. The interfacial mass transfer was supposed to be faster than the intrinsic reaction kinetics suppressing the use of mass transfer correlation. Non‐linear regression was used to estimate the kinetic and thermal parameters. The kinetic parameters of epoxidation of the three different fatty acids, namely oleic, linoleic and its intermediate were estimated. The reaction enthalpy of epoxidation was estimated to ‐230 ± 3.8 kJ/mol, and the reaction enthalpy of ring‐opening was measured to be ‐90 kJ/mol by Tian‐Calvet calorimeter. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-09T17:47:24.080801-05:
      DOI: 10.1002/aic.15037
  • Deciphering and handling uncertainty in shale gas supply chain design and
           optimization: Novel modeling framework and computationally efficient
           solution algorithm
    • Authors: Jiyao Gao; Fengqi You
      Abstract: This paper addresses the optimal design and operations of shale gas supply chains under uncertainty of estimated ultimate recovery (EUR). A two‐stage stochastic mixed‐integer linear fractional programming (SMILFP) model is developed in order to optimize the levelized cost of energy generated from shale gas. In this model, both design and planning decisions are considered with respect to shale well drilling, shale gas production, processing, multiple end‐uses, and transportation. In order to reduce the model size and number of scenarios, we apply a sample average approximation method to generate scenarios based on the real‐world EUR data. In addition, a novel solution algorithm integrating the parametric approach and the L‐shaped method is proposed for solving the resulting SMILFP problem within a reasonable computational time. The proposed model and algorithm are illustrated through a case study based on the Marcellus shale play, and a deterministic model is considered for comparison. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-03T18:42:30.737666-05:
      DOI: 10.1002/aic.15032
  • Use of CuO/MgAl2O4 and La0.8Sr0.2FeO3/γ‐Al2O3 in chemical
           looping reforming system for tar removal from gasification gas
    • Authors: Martin Keller; Henrik Leion, Tobias Mattisson
      Abstract: Biomass gasification gas contains condensable hydrocarbons usually referred to as “tars”. The use of chemical‐looping reforming (CLR) has been proposed as a downstream technology for tar removal. In this work, the tar removal capabilities and the regeneration properties of two particularly promising bed materials, CuO/MgAl2O4 and La0.8Sr0.2FeO3/γ‐Al2O3, were investigated by using C2H4, C6H6 and C7H8 as tar surrogates. The material La0.8Sr0.2FeO3/γ‐Al2O3 exhibited high levels of conversion of all tar surrogates investigated, whereas CuO/MgAl2O4 showed less promising behavior. For this material the C2H4 conversion in the absence of aromatic compounds was very high, but in the presence of monoaromatic compounds, the conversion of aromatics and C2H4 was poor. This indicates that monoaromatic compounds hinder the conversion of C2H4 effectively. Therefore, C2H4 may not always be a good choice as a tar surrogate and its suitability may depend on the mechanism of hydrocarbon conversion on the bed material surface in question. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-03T18:42:13.414978-05:
      DOI: 10.1002/aic.15034
  • Energy demand management for process systems through production scheduling
           and control
    • Abstract: Demand response (DR) is an integral part of the Smart Grid paradigm, and has become the focus of growing research, development, and deployment in residential, commercial and industrial systems over the last few years. In process systems, energy demand management through production scheduling is an increasingly important tool that has the potential to provide significant economic and operational benefits by promoting the responsiveness of the process operation and its interactions with the utility providers. However, the dynamic behavior of the underlying process, especially during process transitions, is seldom taken into account as part of the DR problem formulation. Furthermore, the incorporation of energy constraints related to electricity pricing and energy resource availability presents an additional challenge. The goal of this study is to present a novel optimization formulation for energy demand management in process systems that accounts explicitly for transition behaviors and costs, subject to time‐sensitive electricity prices and uncertainties in renewable energy resources. The proposed formulation brings together production scheduling and closed‐loop control, and is realized through a real‐time or receding‐horizon optimization framework depending on the underlying operational scenarios. The dynamic formulation is cast as a mixed‐integer nonlinear programming problem based on a proposed discretization approach, and its merits are demonstrated using a simulated continuous stirred tank reactor where the energy required is assumed to be roughly proportional to the material flow. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-03T18:42:12.141706-05:
      DOI: 10.1002/aic.15033
  • Impact of polyethylene glycol as additive on the formation and extraction
           behaviour of ionic‐liquid based aqueous two phase system
    • Authors: Mohammad Vahidnia; Gholamreza Pazuki, Shiva Abdolrahimi
      Abstract: The present study aims at developing a novel Ionic‐liquid (IL) based aqueous two phase system (ATPS) with polyethylene glycol (PEG) as adjuvant for the separation of biomolecules. This original work involves addition of various concentration of PEG (2000, 4000 and 6000 gr/mol) to 1‐butyl‐3‐methylimidazolium acetate+ potassium hydrogen phosphate ATPS in order to investigate their subsequent effect on phase diagrams and partitioning coefficient of α‐amylase. In another innovative aspect of this work, response surface methodology (RSM) based on three‐variable central composite design (CCD) was employed to understand the effect of phase forming components on extraction studies of α‐amylase. The addition of small amount of PEG improved the partitioning coefficient of biomolecule. The Effective excluded volume theory (EEV) was applied to correlate the salting‐out ability. As a result, it can be stated that the proposed system can effectively be used in separation and purification studies instead of task specific ionic liquids. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-03T18:42:03.63948-05:0
      DOI: 10.1002/aic.15035
  • Simultaneous model selection and parameter estimation for
           lithium‐ion batteries: A sequential MINLP solution approach
    • Abstract: Equivalent circuit model (ECM) is a practical and commonly used tool not only in state of charge (SOC) estimation but also in state of health (SOH) monitoring for lithium‐ion batteries (LIBs). The functional forms of circuit parameters with respect to SOC in ECM are usually empirical determined, which cannot guarantee to obtain a compact and simple model. In this study, a systematical solution framework for simultaneous functional form selection and parameter estimation is proposed. A bi‐objective mixed‐integer nonlinear programming (MINLP) model is first constructed. Two solution approaches, namely the explicit and implicit methods, are then developed to balance model accuracy and model complexity. The former explicitly treats the model complexity as a constraint and the latter implicitly embeds the model complexity into the objective as a penalty. Both approaches require sequential solution of the transformed MINLP model and an ideal and nadir ideal solutions based criterion is utilized to terminate the solution procedure for determining the optimal functional forms, in which ideal solution and nadir ideal solution represent the best and worst of each objective respectively. Both explicit and implicit approaches are thoroughly evaluated and compared through experimental pulse current discharge test and hybrid pulse power characterization test of a commercial LIB. The fitting and prediction results illustrate that the proposed methods can effectively construct an optimal ECM with minimum complexity and prescribed precision requirement. It is thus indicated that the proposed MINLP based solution framework, which could automatically guide the optimal ECM construction procedure, can be greatly helpful to both SOC estimation and SOH monitoring for LIBs. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-03T18:37:13.526272-05:
      DOI: 10.1002/aic.15030
  • Defect engineering in semiconducting oxides: Control of ZnO surface
           potential via temperature and oxygen pressure
    • Authors: Ming Li; Edmund G. Seebauer
      Abstract: The technological usefulness of a semiconductor often depends upon the types, concentrations, charges, spatial distributions, and mobilities of the atomic‐scale defects it contains. For semiconducting metal oxides, defect engineering is relatively new and involves complex transport and reaction networks. Surface‐based methods hold special promise in nanostructures where surface‐to‐volume ratios are high. The present work employs photoreflectance augmented by X‐ray photoelectron spectroscopy to show that the surface potential VS for Zn‐terminated ZnO(0001) can be manipulated over a significant range 54.97‐79.08 kJ/mol (0.57‐0.82eV) via temperature and the partial pressure of O2. A defect transport model implies this variation in VS should affect the injection rate of oxygen interstitials by a factor of three. Such injection plays an important role in controlling the concentrations of oxygen vacancies deep in the bulk, which often prove troublesome as trapping centers in photocatalysis and photovoltaics and as parasitic emitters in light‐emitting devices. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-03T18:36:35.640464-05:
      DOI: 10.1002/aic.15031
  • Continuous synthesis of palladium nanorods in oxidative segmented flow
    • Authors: Victor Sebastian; Soubir Basak, Klavs F. Jensen
      Abstract: Laminar and segmented flow methods are presented for producing Pd rod‐shaped nanostructures from Na2PdCl4 in mixtures of water, ethylene glycol, polyvinyl pyrrolidone, and KBr. Synthesis in laminar flow produced an evolution from Pd nanoparticles to short nanorods with residence time. Use of air as the segmentation gas tuned the oxidative environment promoting anisotropic growth of Pd. Moreover, the elevated temperatures (160 and 190°C) and pressure (0.8 MPa) reduced the synthesis time from hours for most batch systems to 2 minutes. The ratio of polyol and Pd precursor metal flow streams controlled the anisotropic growth, obtaining nanorods with a diameter ∼ 4 nm and an aspect ratio up to 6. Nanorods were single crystal with the {100} lattice spacing of fcc structure, and without any dislocation, stacking fault, or twin defects. The resulting Pd nanorods had high activity at moderate temperature (40ºC) and pressure (0.2MPa) in the catalytic hydrogenation of styrene. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-03T18:31:41.033012-05:
      DOI: 10.1002/aic.15029
  • Issue information
    • Abstract: Cover illustration. Cover composed by Andrew Grossmann from images purchased from: Robert_s/Shutterstock, Pensiri/Shutterstock 10.1002/aic.15013
      PubDate: 2015-09-03T10:04:17.706909-05:
      DOI: 10.1002/aic.14589
  • Study of the effect of porous particles on vapor‐liquid equilibrium
           by using the headspace gas chromatography
    • Abstract: The effect of certain porous particles on vapor‐liquid equilibrium(VLE) of ethanol + water, ethanol + ethyl acetate, acetic acid + ethyl acetate and n‐hexane + n‐heptane systems was investigated by using the headspace gas chromatography (HSGC) at 60°C, 50°C, 50°C and 50°C, respectively. Four kinds of porous particles were studied: molecular sieves (3 Å, 4 Å, 5 Å, and 13 X), activated carbons (columnar activated carbon, powdered activated carbon), activated alumina balls and non‐polar adsorption resins (D4006, D4020). Good agreement was noticed when the experimental results in the absence of porous particles were compared with the NRTL model's predictions. These results added to the validity of using the HSGC in studying the VLE of binary systems. The results obtained showed that the VLE of these four kinds of binary mixtures in the presence of molecular sieves and activated alumina balls was altered considerably. The presence of activated carbons had no effect on the VLE of these binary systems, but the VLE of n‐hexane + n‐heptane system was altered in the presence of D4006 or D4020 non‐polar adsorption resin. Other factors, such as pore size, type, weight, properties of porous particles and solvents were also investigated. The results showed that the alteration in the VLE of a given binary solution was a function of the pore size, type, weight, properties of porous particles and the properties of solvents. In addition, the mechanism of the porous particles altering the VLE was also analyzed accordingly. This article is protected by copyright. All rights reserved.
      PubDate: 2015-09-02T10:39:15.199312-05:
      DOI: 10.1002/aic.15028
  • New MINLP Formulation for the Multiperiod Pooling Problem
    • Authors: Pedro M. Castro
      Abstract: This paper addresses the modeling of blending tank operations in petroleum refineries for the most profitable production of liquid fuels in a context of time‐varying supply and demand. A new mixed‐integer nonlinear programming formulation is proposed that by using individual flows and split fractions as key model variables leads to a different set of non‐convex bilinear terms compared to the original work of Kolodziej et al. (Comput Chem Eng 2013;53:122‐142). Through the solution of a set of test problems from the literature, we show that these are better handled by decomposition algorithms that divide the problem into integer and nonlinear components as well as by commercial solvers. In fact, BARON and GloMIQO can solve to global optimality all problems resulting from the new formulation and literature data. A tailored global optimization algorithm working with a tight mixed‐integer linear relaxation from multiparametric disaggregation achieves a similar performance. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-29T10:41:53.89397-05:0
      DOI: 10.1002/aic.15018
  • Interaction dynamics of a spherical particle with a suspended liquid film
    • Authors: Subhasish Mitra; Elham Doroodchi, Geoffrey M. Evans, Vishnu Pareek, Jyeshtharaj B. Joshi
      Abstract: Hydrodynamics of collision interactions between a particle and gas‐liquid interface such as droplet/film is of keen interest in many engineering applications. This study reports on the collision interaction between a suspended liquid (water) film of thickness 3.41±0.04 mm and an impacting hydrophilic particle (glass ballotini) of different diameters (1.1‐3.0 mm) in low particle impact Weber number (We=ρlvp2dp/σ) range (1.4 – 33). Two distinct outcomes were observed – particle retention in the film at lower Weber number and complete penetration of the film towards higher Weber number cases. A collision parameter was defined based on energy balance approach to demarcate these two interaction regimes which agreed reasonably well with the experimental outcomes. It was shown that the liquid ligament forming in the complete penetration cases breaks up purely by “dripping/end pinch‐off” mechanism and not due to capillary wave instability. An analytical model based on energy balance approach was proposed to determine the liquid mass entrainment associated with the ligament which compared well with the experimental measurements. A good correlation between the % film mass entrained and the particle Bond number (Bo = ρlgdp2/σ) was obtained which indicated a dependency of Bo1.72. Computationally, a three dimensional CFD model was developed to simulate these interactions using different contact angle boundary conditions which in general showed reasonable agreement with experiment but also indicated deficiency of a constant contact angle value to depict the interaction physics in entirety. The computed force profiles from CFD model suggest dominance of the pressure force over the viscous force almost by an order of magnitude in all the Weber number cases studied. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-28T17:41:37.853681-05:
      DOI: 10.1002/aic.15027
  • Effect of channel size on liquid‐liquid plug flow in small channels
    • Authors: Dimitrios Tsaoulidis; Panagiota Angeli
      Abstract: The hydrodynamic properties of plug flow were investigated in small channels with 0.5, 1, and 2 mm ID, for an ionic liquid/aqueous two‐phase system with the aqueous phase forming the dispersed plugs. Bright field PIV combined with high speed imaging were used to obtain plug length, velocity and film thickness, and to acquire velocity profiles within the plugs. Plug length decreased with mixture velocity, while for constant mixture velocity it increased with channel size. Plug velocity increased with increasing mixture velocity and channel size. The film thickness was predicted reasonably well for Ca>0.08 by Taylor's1 model. A fully developed laminar profile was established in the central region of the plugs. Circulation times in the plugs decreased with increasing channel size. Pressure drop was predicted reasonably well by a modified literature model, using a new correlation for the film thickness derived from experimental values. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-28T17:40:54.687092-05:
      DOI: 10.1002/aic.15026
  • Chemical nature of active sites for defect‐mediated nucleation on
           silicon dioxide
    • Authors: Joseph M. McCrate; John G. Ekerdt
      Abstract: Germanium nanoparticle growth on SiO2 proceeds via defect‐mediated nucleation and particle density can be enhanced by chemically treating the SiO2 with SiHx. The influence of SiHx fragments on SiO2 surface sites is studied using a fluorescent probe‐based technique to understand the chemical nature of the inherent defect trapping sites and the chemical nature of the additional trapping sites formed by SiHx. We show oxygen‐vacancy sites on SiO2 are the inherent sites for defect‐mediated nucleation. SiHx fragments, generated by cracking disilane on a hot tungsten filament, are shown to react with strained siloxane sites, leading to a conversion of these strained siloxane sites into a different low density defect site that is shown to display reactive characteristics similar to the oxygen‐vacancy defect sites. Previous work demonstrating an increased density of Ge nuclei on SiO2 surfaces with increasing SiHx exposure is interpreted in the context of the current experimental results. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-28T03:31:02.610608-05:
      DOI: 10.1002/aic.15023
  • Adsorption of nitrogen and sulfur containing compounds on nimos for
           hydrotreating reactions: A DFT and vdW‐corrected study
    • Authors: Srinivas Rangarajan; Manos Mavrikakis
      Abstract: Adsorption of thirty five molecules, comprising of organonitrogen and organosulfur compounds and hydrocarbons relevant to hydrotreating, was studied on the nickel promoted metal edge of molybdenum sulfide catalysts using periodic DFT, accounting for van der Waal's interactions in several cases. Basic molecules tend to adsorb via their nitrogen atoms directly on top of nickel atoms while non‐basic molecules adsorb via carbon atoms relatively weakly. Molecular size, electron density, and alkyl substitution affects binding at the GGA‐PW91 level of theory. van der Waal's corrections influences adsorption geometry and leads to significant additional stabilization of adsorbates. The differential binding energy of nitrogen‐containing compounds decreases by 0.2 – 0.3 eV for each additional molecule added on the edge and their presence destabilizes the binding of organosulfur compounds by more than 0.2 eV. The inhibition of hydrodesulfurization is suggested to arise from site blocking and destabilization of reaction intermediates and transition states by organonitrogen compounds. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-28T03:30:28.032528-05:
      DOI: 10.1002/aic.15025
  • Effect of dead volumes on the performance of an industrial‐scale
           simulated moving‐bed parex unit for p‐xylene purification
    • Abstract: The cyclic steady state (CSS) of the industrial‐scale, seven‐zone, simulated moving‐bed unit for p‐xylene (p‐x) purification (Parex unit) with three types of dead volumes—bed lines, pusharound and pumparound circulation lines, and bed heads—is analysed. In particular, the effects of the size and level of hydrodynamic dispersion of each dead volume on process performance and on its CSS are studied in detail. The circulation lines change the CSS behaviour from t*‐periodic to Nt*‐periodic, where t* is the switching interval and N = 12 is the number of columns in each adsorbent chamber. A high level of axial dispersion in the bed lines, characterized by Péclet numbers smaller than 100, affects the p‐x purity. Moreover, the bed lines lower the average p‐x concentration in the extract, which reduces the p‐x recovery. If the small time lags introduced by the circulation lines are neglected, it is possible to develop a detailed process model that considers the operation of the Parex unit over a single switching interval as opposed to a full cycle, and whose CSS solution can be efficiently computed using a full‐discretization approach. Finally, it is shown that the volume of the bed heads influences significantly the performance of the Parex unit, and that its impact on the location of the operating point with respect to the boundaries of the separation region can be approximately taken into account using the standard TMB‐SMB equivalence rules if they are corrected for the presence of extra interparticle fluid. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-28T03:29:37.185235-05:
      DOI: 10.1002/aic.15022
  • Liquid‐liquid flow patterns in reduced dimension based on energy
           minimization approach
    • Authors: Aadithya Kannan; Subhabrata Ray, Gargi Das
      Abstract: Study of liquid‐liquid flow patterns in reduced dimensions is relevant under the current trends to miniaturize process equipment. The phase distribution results from interplay of surface (dominant in microchannels) and gravity forces (dominant in larger dimensions). The proposed analysis, based on minimization of total system energy comprising of kinetic, surface and potential energy, unravels the influence of wetting properties and predicts the range of existence of annular and plug flow as well as the onset of stratification with increasing conduit dimension. Unlike existing models marking abrupt transitions, the proposed methodology can predict zones of transition where interfacial distributions gradually evolve with change of operating conditions ‐ the predictions agreeing closely to experimental and literature data. The analysis illustrates the coupled effect of diameter, contact angle and inlet composition on flow distribution and defines the transition from macro to micro domain (millichannels) in terms of Bond number as 0.1
      PubDate: 2015-08-28T03:28:54.632234-05:
      DOI: 10.1002/aic.15024
  • CFD simulation of a transpiring‐wall SCWO reactor: Formation and
           optimization of the water film
    • Authors: Fengming Zhang; Chunyuan Ma
      Abstract: A 2‐dimentional axisymmetric computational fluid dynamics model of a transpiring wall reactor for supercritical water oxidation (SCWO) was developed using the commercial software Fluent 6.3. Numerical model was validated by comparisons with experimental temperature profiles and product properties (total organic carbon and CO). Compared with the transpiration intensity, the transpiring water temperature was found to have a more significant influence on the reaction zone. An assumption that an ideal corrosion and salt deposition inhibitive water film can be formed when the temperature of the inner surface of the porous tube is less than 374°C was made. It was observed that lowering transpiring water temperature is conducive to the formation of the water film at the expense of feed degradation. The appropriate mass flux ratio between the total transpiring flow and the core flow was determined at 0.05 based on the formation of the water film and feed degradation. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-27T18:41:28.582313-05:
      DOI: 10.1002/aic.15021
  • Kinetic study of 1‐butanol dehydration to di‐n‐butyl
           ether over Amberlyst 70
    • Abstract: Kinetics of the catalytic dehydration of 1‐butanol to di‐n‐butyl ether (DNBE) over Amberlyst‐70 was investigated. Experiments were performed in liquid phase at 4 MPa and 413‐463 K. Three elementary reaction mechanisms were considered: a Langmuir‐Hinselwood‐ Hougen‐Watson (LHHW) formulation; an Eley‐Rideal (ER) formulation in which DNBE remains adsorbed; an ER formulation in which water remains adsorbed. Two kinetic models explain satisfactorily the dehydration of 1‐butanol to DNBE: a LHHW formalism in which the surface reaction between two adjacent adsorbed molecules of 1‐butanol is the rate limiting step (RLS) and where the adsorption of water is negligible, and a mechanism in which the RLS is the desorption of water being the adsorption of DNBE negligible. In both models the strong inhibiting effect of water was successfully taken into account by means of a correction factor derived from a Freundlich adsorption isotherm. Both models present similar values of apparent activation energies (122±2 kJ/mol). This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-27T18:37:03.299048-05:
      DOI: 10.1002/aic.15020
  • Trends and Challenges in Process Safety
    • PubDate: 2015-08-27T18:27:33.00836-05:0
      DOI: 10.1002/aic.15019
  • New frames of reference for mapping drugs in the four classes of the BCS
           and BDDCS into regions with clear boundaries
    • Authors: Kalliopi Chatzizacharia; Dimitris Hatziavramidis
      Abstract: The Biopharmaceutics Classification System (BCS), adopted by drug regulatory agencies for oral drug products approval, classify drug substances into four classes according to their aqueous solubility and epithelial membrane permeability. In a solubility‐permeability frame of reference, drugs on the boundaries of the four regions depicting the four drug classes are problematic to classify. To remove the fuzziness in the boundaries of the solubility‐permeability frame of reference, a data set of 85 oral drugs from all four classes of BCS are mapped into new frames of references in which the coordinate axes are based on the rates of dissolution, systemic elimination (metabolism) and membrane permeation. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-20T01:54:07.96739-05:0
      DOI: 10.1002/aic.15017
  • A Thermodynamic Approach Towards Defining the Limits of Biogas Production
    • Authors: Ralph Farai Muvhiiwa; Diane Hildebrandt, David Glasser, Tonderayi Matambo, Craig Sheridan
      Abstract: In this paper the authors present theoretical thermodynamic targets for producing biogas. The research shows the relationship between the mass of substrate used versus the methane produced from a feedstock of glucose and an estimate for that of cellulose. Calculations based on material and energy balances are used to determine the performance target (material and energy limits) of an anaerobic digestion system. These limits cannot be exceeded even if one genetically engineer organisms to increase yield. The results show that all processes that produce methane are feasible from a Gibbs Free Energy point of view but do not conserve the chemical potential of the feed material. The thermodynamics show that methane production is material and energy limited. The maximum amount of methane that can be formed sustainably is 3 moles per mole of glucose, producing 142 kJ of heat per mole of glucose which needs to be rejected. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-19T11:11:20.635909-05:
      DOI: 10.1002/aic.15016
  • Experimental Investigation of Solid Particles Flow in a Conical Spouted
           Bed Using Radioactive Particle Tracking
    • Authors: L. Spreutels; B. Haut, R. Legros, F. Bertrand, J. Chaouki
      Abstract: Solid particles flow in a conical spouted bed is characterized by radioactive particle tracking (RPT). The influence of operating conditions on key parameters of this flow is evaluated and discussed: the morphology of the solid bed is not strongly influenced by the forces exerted by the gas on the solid particles, but rather by geometrical considerations; the particles spend approximately eight percent of their time in the spout in all experiments; it is the force exerted on the solid particles by the gas that directly controls the volumetric flow rate between adjacent regions, and not the amount of particles in the bed; as U/Ums increases, the volume of solid particles in the annulus decreases, the volume of solid particles in the fountain increases and the volume of solid particles in the spout remains constant. Correlations to predict key flow parameters as functions of operating conditions are also established and discussed. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-19T01:12:01.503479-05:
      DOI: 10.1002/aic.15014
  • Thermodynamics and Separation Process for Quaternary Acrylic Systems
    • Authors: Cuncun Zuo; Yaping Li, Chunshan Li, Shasha Cao, Haoyu Yao, Suojiang Zhang
      Abstract: Vapor‐liquid equilibrium (VLE) and liquid‐liquid equilibrium (LLE) data of binary and ternary acrylic systems were systematically measured. Subsequently, VLLE phase diagrams of binary systems, tridimensional VLE phase diagrams of methyl acrylate (MA)‐methanol (Me)‐H2O ternary system, and quaternary LLE phase diagrams of MA‐Me‐H2O‐methyl acetate (MeOAc) system were constructed. These diagrams clearly demonstrated the effects of temperature on phase equilibrium. The experimental data was fitted by the NRTL and UNIQUAC models, and the best‐fitted parameters were used to predict interaction properties of ternary and quaternary mixture. Therefore, the phase equilibrium data were provided as reference for the design of acrylic systems rectification or extraction process. Residue curve was mapped out for MA‐Me‐H2O system through Aspen plus software. Finally, using thermodynamics and residue curve as theoretical basis, two novel separation processes were proposed and applied to the quaternary acrylic systems. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-19T01:10:59.36514-05:0
      DOI: 10.1002/aic.15015
  • Advanced technologies for water treatment and reuse
    • Authors: Inmaculada Ortiz Uribe; Anuska Mosquera Corral, Juan Lema Rodicio, Santiago Esplugas
      PubDate: 2015-08-17T18:43:07.814198-05:
      DOI: 10.1002/aic.15013
  • Engineering Design of Outer‐Selective Tri‐bore Hollow Fiber
           Membranes for Forward Osmosis and Oil‐Water Separation
    • Abstract: Outer‐selective thin‐film composite (TFC) hollow fiber membranes offer advantages like less fiber blockage in the feed stream and high packing density for industrial applications. However, outer‐selective TFC hollow fiber membranes are rarely commercially available due to the lack of effective ways to remove residual reactants from fiber's outer surface during interfacial polymerization and form a defect‐free polyamide film. This study reports a new simplified method to fabricate outer‐selective TFC membranes on tri‐bore hollow fiber substrates. Mechanically robust tri‐bore hollow fiber substrates containing 3 circular‐sector channels were first prepared by spinning a P84/ethylene glycol mixed dope solution with delayed demixing at the fiber lumen. The thin wall tri‐bore hollow fibers have a large pure water permeability up to 300 L m−2 h−1 bar−1. Outer‐selective TFC tri‐bore hollow fiber membranes were then fabricated by interfacial polymerization with the aid of vacuum sucking to ensure the TFC layer well‐attached to the substrate. Under forward osmosis studies, the TFC tri‐bore hollow fiber membrane exhibits a good water flux and a small flux difference between active‐to‐draw (i.e., the active layer facing the draw solution) and active‐to‐feed (i.e., the active layer facing the feed solution) modes due to the small internal concentration polarization. A hyper‐branched polyglycerol was further grafted on top of the newly developed TFC tri‐bore hollow fiber membranes for oily wastewater treatment. The membrane displays low fouling propensity and can fully recover its water flux after a simple 20‐min water wash at 0.5 bar from its lumen side, which makes the membrane preferentially suitable for oil‐water separation. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-13T18:21:26.997763-05:
      DOI: 10.1002/aic.15012
  • First‐Principles Based Group Additivity Values for Thermochemical
           Properties of Substituted Aromatic Compounds
    • Abstract: A set of 7 Benson group additive values (GAV) together with 15 correction terms for non‐nearest neighbor interactions (NNI) is developed to calculate the gas phase standard enthalpies of formation, entropies and heat capacities of monocyclic aromatic compounds containing methyl, ethyl, vinyl, formyl, hydroxyl and methoxy substituents. These GAVs are obtained through least squares regression of a database of thermodynamic properties of 143 molecules, calculated at the post‐Hartree–Fock G4 composite method. Out of the 15 NNIs, which account for several well‐known substituent effects in aromatic molecules, 13 have been determined for the first time. All but two group additively calculated standard enthalpies of formation agree within 4 kJ mol‐1. The entropies and the heat capacities generally deviate less than 4 J mol‐1 K‐1 from the ab initio results. Natural bond orbital (NBO) analysis is utilized to identify the underlying causes of the observed NNIs. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-12T18:16:20.308654-05:
      DOI: 10.1002/aic.15008
  • Process Intensification on the Separation of Benzene and Thiophene by
           Extractive Distillation
    • Authors: Jingli Han; Zhigang Lei, Yichun Dong, Chengna Dai, Biaohua Chen
      Abstract: The separation of benzene and trace thiophene by extractive distillation was intensified in two aspects, i.e., selection of a suitable entrainer and improvement of the process. The mixture of dimethylformamide (DMF) and an ionic liquid (IL) was chosen as the entrainer. Vapor‐liquid equilibrium (VLE) experiments using pure DMF and a mixed entrainer were conducted, and UNIFAC model for ILs was extended to the benzene‐thiophene‐DMF‐IL system. The results demonstrated that volatilization loss of DMF in the vapor phase was significantly reduced by adding IL. Moreover, an improved process with only four columns using a mixed entrainer was proposed. The results indicated that the improved process is more promising for decreasing energy consumption and equipment investment compared with the conventional six‐column process. The total heat duties of reboilers and condensers was decreased by 6.47% and 6.41%, respectively. The process intensification strategy may be directly extended to separate trace components of other systems. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-12T18:13:09.013163-05:
      DOI: 10.1002/aic.15009
  • Mixed matrix membranes based on 6FDA polyimide with silica and zeolite
           microsphere dispersed phases
    • Abstract: Mixed matrix membranes (MMMs) prepared with 6FDA‐DAM polymer using ordered mesoporous silica MCM‐41 spheres (MSSs), Grignard surface functionalized MSSs (Mg‐MSSs) and hollow zeolite spheres (HZSs) are studied to evaluate the effects of surface modification on performance. Performance near or above the so‐called permeability‐selectivity trade‐off curve was achieved for the H2/CH4, CO2/N2, CO2/CH4 and O2/N2 systems. Two loadings (8 and 16 wt%) of MSSs were tested using both constant volume and Wicke‐Kallenbach sweep gas permeation systems. Besides single gas H2, CO2, O2, N2 and CH4 tests, mixed gas (50/50 vol%) selectivities were obtained for H2/CH4, CO2/N2, CO2/CH4 and O2/N2 and found to show enhancements vs. single gases for CO2 including cases. Mg‐MSS/6FDA‐DAM was the best performing MMM with H2/CH4, CO2/N2, CO2/CH4 and O2/N2 separation selectivities of 21.8 (794 Barrer of H2), 24.4 (1214 Barrer of CO2), 31.5 (1245 Barrer of CO2) and 4.3 (178 Barrer of O2), respectively. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-12T18:09:52.783452-05:
      DOI: 10.1002/aic.15011
  • PtZn‐ETS‐2: A Novel Catalyst for Ethane Dehydrogenation
    • Authors: Zhengnan Yu; James A. Sawada, Weizhu An, Steven M. Kuznicki
      Abstract: Catalysts having unprecedented selectivity toward ethane dehydrogentation were prepared by combining platinum and zinc on the surface of the titanate ETS‐2. This high surface area, sodium titanate ion exchanger affords high metal dispersion, presents many active sites to the gas stream, and is free of any pore structure that can influence mass transfer to and away from the active sites. It was determined that the addition of zinc to platinum‐loaded ETS‐2 changes the electronic properties of the metals and significantly improves the specificity of the catalyst. By changing the zinc‐to‐platinum ratio, and by manipulating the space velocity of the gas, the production of side products and coke can be suppressed or eliminated. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-12T18:09:22.531979-05:
      DOI: 10.1002/aic.15010
  • Effect of Liquid Addition on the Bulk and Flow Properties of Fine and
           Coarse Glass Beads
    • Authors: James V. Scicolone; Matthew Metzger, Sara Koynov, Kellie Anderson, Paul Takhistov, Benjamin J. Glasser, Fernando J. Muzzio
      Abstract: The effect of water on the packing and flow properties of fine and coarse particles was experimentally investigated. Four different particle sizes of glass beads, from 5 to 275μm, were studied with increasing water weight‐percentages. Using a FT4 Powder Rheometer, changes in bulk properties were collected as a function of water content and particle size. The results show that water content plays a significant role on the packing and flow of the particles. Small amounts of water created porous aggregates due to liquid bridging. Greater amounts of water resulted in the filling of the void‐spaces. This was indicated by an increase in basic flow energy, density, and pressure drop, with a decrease in porosity. A greater understanding of bulk properties of wetted material is useful to develop standard systems that can be used to examine the behavior of more complex situations, and implement changes to improve materials handling and processing. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-11T19:41:41.407228-05:
      DOI: 10.1002/aic.15004
  • A model for supersaturation and aspect ratio for growth dominated
           crystallization from solution
    • Authors: L. Derdour; E.J. Chan
      Abstract: A model for predicting supersaturation, crystal growth rate, crystal size distribution and aspect ratio is presented. The model applies to isothermal anti‐solvent crystallization where crystal growth is the dominant phenomena and for systems where crystal habit can be characterized by two dimensional variables. A parameter estimation algorithm was derived to extract solute integration coefficients in the two growth directions from experimental data about temporal evolution of concentration during crystallization, the final aspect ratio and the aspect ratio at the end of the seed age period. Model's predictions for supersaturation and aspect ratio were in good agreement with experimental data obtained on an investigational drug that crystallizes in the parallelepipedic shape. Finally, model simulations predict that for a given initial seed size, the seed loading is the main factor impacting the final aspect ratio and thus identified the range of seed loading that would result in undesired powder flow. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-11T19:31:21.088942-05:
      DOI: 10.1002/aic.15007
  • Ultra‐thin Carbon Molecular Sieve Membrane for Propylene/Propane
    • Authors: Xiaoli Ma; Y.S. Lin, Xiaotong Wei, Jay Kniep
      Abstract: Ultra‐thin (down to 300 nm), high quality carbon molecular sieve (CMS) membranes were synthesized on mesoporous γ‐alumina support by pyrolysis of defect free polymer films. The effect of membrane thickness on the micropore structure and gas transport properties of CMS membranes was studied with the feed of He/N2 and C3H6/C3H8 mixtures. Gas permeance increases with constant selectivity as the membrane thickness decreases to 520 nm. The 520 nm CMS membrane exhibits C3H6/C3H8 mixture selectivity of ∼31 and C3H6 permeance of ∼1.0 × 10−8 mol m−2 s−1 Pa−1. Both C3H8 permeance and He/N2 selectivity increase, but the permeance of He, N2 and C3H6 and the selectivity of C3H6/C3H8 decrease with further decrease in membrane thickness from 520 nm to 300 nm. These results can be explained by the thickness‐dependent chain mobility of the polymer film which yields thinner final CMS membranes with reduction in pore size and possible closure of C3H6‐accessible micropores. The authors would like to acknowledge the support of the National Science Foundation (IIP‐1127395) for this project, and Belle K. Lin for assistance in some experiments. We also acknowledge the use of facilities with the LeRoy Eyring Center for Solid State Science at Arizona State University. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-11T19:30:44.538053-05:
      DOI: 10.1002/aic.15005
  • Efficient recovery of high‐purity aniline from aqueous solutions
           using pervaporation‐fractional condensation system
    • Authors: Chuncheng Li; Xinru Zhang, Xiaogang Hao, Minmin Wang, Chuan Ding, Zhongde Wang, Yinan Wang, Guoqing Guan, Abuliti Abudula
      Abstract: Selective recovery of valuable minor component with high‐purity form from dilute aqueous solution is an interesting issue in the area of organophilic pervaporation. In this study, high‐purity aniline was recovered with a high production rate from dilute aqueous solution by a pervaporation‐fractional condensation (PVFC) coupling system. The effects of downstream pressure and temperature (the first condenser) on the performance of PVFC system were investigated based on experimental measurements and Aspen simulations. Sorption and desorption experiments demonstrated that the sorption selectivity of PEBA‐2533 membrane to aniline was extremely high, indicating excellent pervaporation performance for aniline/water solutions. The perfect integration of high‐performance PEBA‐2533 membrane with the fractional condensation process yielded high production rate of 1222.5 g/(m2·h) as well as high recovery efficiency (86.5%) for recovering high‐purity aniline in the first condenser when feed concentration and temperature were 1 wt% and 80 ˚C, respectively. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-11T19:30:06.365446-05:
      DOI: 10.1002/aic.15006
  • Drop printing of pharmaceuticals: Effect of molecular weight on PEG
           coated‐naproxen/PEG3350 solid dispersions
    • Abstract: Solid dispersions have been used to enhance the bioavailability of poorly water‐soluble active pharmaceutical ingredients (APIs). However, the solid state phase, compositional uniformity, and scale‐up problems are issues that need to be addressed. To allow for highly controllable products, the Drop Printing (DP) technique can provide precise dosages and predictable compositional uniformity of APIs in two/three dimensional structures. In this study, DP was used to prepare naproxen (NAP)/polyethylene glycol 3350 (PEG3350) solid dispersions with PEG coatings of different molecular weights (MW). A comparison of moisture‐accelerated crystallization inhibition by different PEG coatings was assessed. Scanning electron microscopy (SEM), second harmonic generation (SHG) microscopy, and differential scanning calorimetry (DSC) analysis were performed to characterize the morphology and quantify the apparent crystallinity of NAP within the solid dispersions. Thermogravimetric analysis (TGA) was employed to measure the water content within each sample. The results suggest that the moisture‐accelerated crystallization inhibition capability of the PEG coatings increased with increasing MW of the PEG coating. Besides, to demonstrate the flexibility of DP technology on manufacturing formulation, multilayer tablets with different PEG serving as barrier layers were also constructed, and their dissolution behavior was examined. By applying DP and appropriate materials, it is possible to design various carrier devices used to control the release dynamics of the API. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-06T18:37:55.283444-05:
      DOI: 10.1002/aic.14979
  • Lumped reaction kinetic models for pyrolysis of heavy oil in the presence
           of supercritical water
    • Abstract: The reaction kinetics of the pyrolysis of heavy oil in the presence of supercritical water (SCW) and high pressure N2 were measured. At any reaction temperature applied, the pyrolysis under SCW environments is faster than that under N2 environments. Meanwhile, at lower temperatures the pyrolysis under both environments is accelerated by the introduction of coke into the feedstock. On the basis of a first‐order four‐lump reaction network consisting of the sequential condensation of maltenes and asphaltenes, the pyrolysis in whichever medium can be preferably described either by the lumped reaction kinetic model modified with autocatalysis and pseudo‐equilibrium or by the model modified solely with pseudo‐equilibrium. Benefited from the reduced limitation of diffusion to reaction kinetics, the pyrolysis in the SCW phase is more sensitive to the increase in reaction temperature than that in the oil phase, disengaging readily from the dependence on autocatalysis at a lower temperature. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-06T18:37:27.567937-05:
      DOI: 10.1002/aic.14978
  • The separation of two different sized particles in an evaporating droplet
    • Authors: Nicole Raley Devlin; Katherine Loehr, Michael T. Harris
      Abstract: The separation of two different sized particles during evaporation of a dilute droplet is examined both computationally and experimentally. A transport model of the evaporating droplet system was solved using the finite element method to determine the fluid velocity, pressure, vapor concentration surrounding the droplet, temperature, and both particle concentrations. Experimentally, 1 μm and 3 μm polystyrene particles were used during the evaporation of a sessile water droplet. It was determined that to accurately model particle deposition, thermal effects need to be considered. The Marangoni currents in evaporating droplets keep particles suspended in the droplet until the end of the evaporation. Previous models of particle deposition during droplet evaporation have rapid accumulation of particles at the contact line. Our experiments and the experiments of others demonstrate that this is not accurate physically. In addition, to model the separation of two different sized particles the consideration of thermal effects is essential. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-06T11:03:56.646128-05:
      DOI: 10.1002/aic.14977
  • On the Accuracy of Landweber and Tikhonov Reconstruction Techniques in
           Gas‐Solid Fluidized Bed Applications
    • Authors: M. Banaei; M. van Sint Annaland, J.A.M Kuipers, N.G. Deen
      Abstract: As electrical capacitance tomography (ECT) technique needs a sophisticated reconstruction, the accuracy of two of the most widely used reconstruction techniques (Landweber and Tikhonov) for gas‐fluidized bed applications were assessed. For this purpose, the results of two‐fluid model (TFM) simulations were used as an input of reconstruction. After finding the optimum reconstruction parameters for the studied system, it is found that both techniques were able to obtain the radial profile and overall value of average volume fraction very well. Conversely, both methods were incapable to determine bubble sizes accurately especially small bubble sizes, unless the Landweber technique with inverted Maxwell concentration model is applied. The probability distribution of the reconstructed results were also smoother in transition between the emulsion and bubble phases compared to the reality. Finally, no significant differences in noise immunity of these two techniques was observed. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-03T03:04:48.503616-05:
      DOI: 10.1002/aic.14976
  • Using short‐term resource scheduling for assessing effectiveness of
           CCS within electricity generation sub‐sector
    • Authors: Colin Alie; Ali Elkamel, Eric Croiset, Peter L. Douglas
      Abstract: A new methodology for assessing the effectiveness of CCS (Carbon Capture and Storage) that does explicitly consider the detailed operation of the target electricity system is proposed in this paper. The electricity system simulation consists of three phases, each one using a modified version of an economic dispatch problem that seeks to maximize the producers' and consumers' surplus while satisfying the technical constraints of the system. The economic dispatch is formulated as a dynamic MINLP (Mixed‐Integer Non‐Linear Programming) problem and implemented in GAMS (General Algebraic Modelling System). The generating unit with CCS is designed and simulated using Aspen Plus®. In the first case study, the operation of the IEEE RTS '96 (Institute of Electrical and Electronics Engineers One‐Area Reliability Test System ‐ 1996)) is simulated with GHG regulation implemented in the form of CO2 permits that generators need to acquire for every unit of CO2 that it is emitted. In the second case study, CCS is added at one of the buses and the operation of the modified IEEE RTS '96 is again simulated with and without GHG regulation. The results suggest that the detailed operation of the target electricity system should be considered in future assessments of CCS and a general procedure for undertaking this for any GHG mitigation option is proposed. Future work will use the novel methodology for assessing the effectiveness of generating units with flexible CO2 capture. This article is protected by copyright. All rights reserved.
      PubDate: 2015-08-01T03:51:45.396917-05:
      DOI: 10.1002/aic.14975
  • A novel adaptive surrogate modeling based algorithm for simultaneous
           optimization of sequential batch process scheduling and dynamic operations
    • Authors: Hanyu Shi; Fengqi You
      Abstract: We propose a novel adaptive surrogate modeling based algorithm to solve the integrated scheduling and dynamic optimization problem for sequential batch processes. The integrated optimization problem is formulated as a large scale mixed integer nonlinear programming (MINLP) problem. In order to overcome the computational challenge of solving the integrated MINLP problem, we propose an efficient solution algorithm based on the bilevel structure of the integrated problem. Because processing times and costs of each batch are the only linking variables between the scheduling and dynamic optimization problems, surrogate models based on piece‐wise linear functions are built for the dynamic optimization problems of each batch. These surrogate models are then updated adaptively, either by adding a new sampling point based on the solution of the previous iteration, or by doubling the upper bound of total processing time for the current surrogate model. The performance of our proposed method is demonstrated through the optimization of a multi‐product sequential batch process with seven units and up to five tasks. The results show that the proposed algorithm leads to a 31% higher profit than the sequential method. The proposed method also outperforms the full space simultaneous method by reducing the computational time by more than four orders of magnitude and returning a 9.59% higher profit. This article is protected by copyright. All rights reserved.
      PubDate: 2015-07-30T17:50:08.993106-05:
      DOI: 10.1002/aic.14974
  • Computational study of spout collapse and impact of partition plate in a
           double slot‐rectangular spouted bed
    • Authors: Shiliang Yang; Ke Zhang, Jia Wei Chew
      Abstract: Gas‐solid hydrodynamics in a three‐dimensional slot‐rectangular double‐spouted bed was numerically investigated by a combined approach of discrete element method (DEM) and computational fluid dynamics (CFD), and the knowledge gained was extended to understand the mechanisms leading to operational instability due to the collapse of a spout, along with the beneficial impact of inserting a vertical partition plate. The setup investigated has two diverging bases and contains up to 2,590,000 particles. The computational results show different behaviors of pressure drop, in terms of average value, fluctuations and power spectral trends, in the five distinct flow regimes corresponding to various superficial gas velocities. Two types of spout shapes are observed under stable spouting conditions, and the spout sizes are quantified. When one of the spouts chokes then collapses, complex interactions between the chambers are identified. Furthermore, the insertion of a vertical partition plate between two chambers appears to be an effective way to prevent the interactions between adjacent fountains, which is advantageous for improving the operational stability of such systems upon scale‐up. This article is protected by copyright. All rights reserved.
      PubDate: 2015-07-27T13:55:41.362616-05:
      DOI: 10.1002/aic.14973
  • Determination of kinetics of CO2 absorption in solutions of
           2‐amino‐2‐methyl‐1‐propanol using a
           microfluidic technique
    • Authors: C. Zheng; B.C. Zhao, K. Wang, G.S. Luo
      Abstract: The kinetics for the reactions of carbon dioxide with 2‐amine‐2‐methyl‐1‐propanol (AMP) and carbon dioxide (CO2) in both aqueous and nonaqueous solutions were measured using a microfluidic method at a temperature range of 298‐318 K. The mixtures of AMP‐water and AMP‐ethylene glycol (EG) were applied for the working systems. Gas‐liquid bubbly mciroflows were formed through a micro‐sieve device and used to determine the reaction characteristics by online observation of the volume change of microbubbles at the initial flow stage. In this condition, a mathematical model according to zwitterion mechanism has been developed to predict the reaction kinetics. The predicted kinetics of CO2 absorption in the AMP aqueous solution verified the reliability of the method by comparing with literatures' results. Furthermore, the reaction rate parameters for the reaction of CO2 with AMP in both solutions were determined. This article is protected by copyright. All rights reserved.
      PubDate: 2015-07-27T13:54:30.669493-05:
      DOI: 10.1002/aic.14972
  • Flexibility Assessment and Risk Management in Supply Chains
    • Authors: Nihar Sahay; Marianthi Ierapetritou
      Abstract: Increased uncertainty in recent years has led the supply chains to incorporate measures to be more flexible in order to perform well in the face of the uncertain events. It has been shown that these measures improve the performance of supply chains by mitigating the risks associated with uncertainties. However, it is also important to assess the uncertainty under which a supply chain network can perform well and manage risk. In this work, flexibility is defined in terms of the bounds of uncertain parameters within which supply chain operation is feasible. A hybrid simulation based optimization framework that uses two‐stage stochastic programming in a rolling horizon framework is proposed. The framework enables taking optimum planning decisions considering demand uncertainty while managing risk. The framework is used to study the trade‐offs between flexibility, economic performance and risk associated with supply chain operation. This article is protected by copyright. All rights reserved.
      PubDate: 2015-07-24T10:27:05.028984-05:
      DOI: 10.1002/aic.14971
  • Modeling and Analysis of Conventional and Heat‐Integrated
           Distillation Columns
    • Abstract: A generic model that can cover diabatic and adiabatic distillation column configurations is presented, with the aim of providing a consistent basis for comparison of alternative distillation column technologies. Both a static and a dynamic formulation of the model, together with a model catalogue consisting of the conventional, the heat‐integrated and the mechanical vapor recompression distillation columns are presented. The solution procedure of the model is outlined and illustrated in three case studies. One case study being a benchmark study demonstrating the size of the model and the static properties of two different HIDiC schemes and the MVRC. The second case study exemplifies the difference between a HIDiC and a CDiC in the composition profiles within a multicomponent separation, whereas the last case study demonstrates the difference in available dynamic models for the HIDiC and the proposed model. This article is protected by copyright. All rights reserved.
      PubDate: 2015-07-24T10:02:47.212608-05:
      DOI: 10.1002/aic.14970
  • Kinetic Insight into Electrochemically Mediated ATRP Gained through
    • Abstract: A detailed kinetic model was constructed using the method of moments to elucidate the electrochemically mediated atom transfer radical polymerization (eATRP). Combined with electrochemical theory, the reducing rate coefficient relevant to the overpotential in eATRP was coupled into the kinetic model. The rate coefficients for eATRP equilibrium and the reducing rate coefficient were fitted to match the experimental data. The effects of catalyst loading, overpotential, and application of programmable electrolysis on the eATRP behavior were investigated based on the tested kinetic model. Results showed that the apparent polymerization rate exhibited a square root dependence on catalyst loading. In addition, a more negative potential accelerated the polymerization rate before the mass transport limitation was reached. This phenomenon indicated that the polymerization rate could be artificially controlled by the designed program (i.e., stepwise and intermittent electrolysis programs). What's more, the normal ATRP, photo‐ATRP, and eATRP were compared to obtain a deeper understanding of these ATRP systems. This article is protected by copyright. All rights reserved.
      PubDate: 2015-07-23T18:23:57.072058-05:
      DOI: 10.1002/aic.14969
  • Integrating expanders into heat exchanger networks above ambient
    • Authors: Chao Fu; Truls Gundersen
      Abstract: The integration of expanders into heat exchanger networks (HENs) is a complex task since both heat and work are involved. In addition, the role of streams (as hot or cold), the utility demand, and the location of pinch points may change. With certain well‐defined conditions, four theorems are proposed for the integration of expanders into HENs above ambient temperature with the objective of minimizing exergy consumption. A straightforward graphical methodology for above ambient HENs design including expanders is developed on the basis of Grand Composite Curves (GCCs). It is concluded that in order to achieve a design with minimum exergy consumption, stream splitting may be applied and expansion should be done at pinch temperatures, hot utility temperature or ambient temperature. In the majority of cases, however, and in line with the concept of Appropriate Placement from Pinch Analysis, expansion at pinch temperatures gives the minimum exergy consumption. This article is protected by copyright. All rights reserved.
      PubDate: 2015-07-23T18:19:51.364947-05:
      DOI: 10.1002/aic.14968
  • Multistream heat exchanger modeling and design
    • Authors: Harry A. J. Watson; Kamil A. Khan, Paul I. Barton
      Abstract: A new model formulation and solution strategy for the design and simulation of processes involving multistream heat exchangers (MHEXs) is presented. The approach combines an extension of pinch analysis with an explicit dependence on the heat exchange area in a nonsmooth equation system to create a model which solves for up to three unknown variables in an MHEX. Recent advances in automatic generation of derivative‐like information for nonsmooth equations make the method tractable, and the use of nonsmooth equation solving methods make the method very precise. Several illustrative examples and a case study featuring an offshore liquefied natural gas production concept are presented which highlight the flexibility and strengths of the formulation. This article is protected by copyright. All rights reserved.
      PubDate: 2015-07-21T10:54:11.414921-05:
      DOI: 10.1002/aic.14965
  • Retrofit design of a pharmaceutical batch process considering “green
           chemistry and engineering” principles
    • Abstract: Considering the capital intensive nature of the chemical industry, redesign of existing production plants is a strategic decision. In this study, retrofitting is performed by using a systematic path flow decomposition method, enriching it with hazard assessment and life cycle analysis path flow indicators and proposing a classification scheme for coupling these new path flow indicators with relevant heuristics for process alternative generation. The developed methodology is applied in a batch production plant from the pharmaceutical industry. The method highlights solvent recovery or substitution as importanECt retrofitting actions, generates diverse process layout structures to achieve this task and evaluates them from cost, hazard and life cycle assessment point of view. Extractive distillation using glycol as an entrainer is identified as the multiobjective optimal option for separating the THF/Water azeotrope with improvement up to 40% for the various objectives compared to a base case where the waste solvent is incinerated. This article is protected by copyright. All rights reserved.
      PubDate: 2015-07-21T10:53:40.529575-05:
      DOI: 10.1002/aic.14966
  • Economic model predictive control of nonlinear time‐delay systems:
           Closed‐loop stability and delay compensation
    • Authors: Matthew Ellis; Panagiotis D. Christofides
      Abstract: Closed‐loop stability of nonlinear time‐delay systems under Lyapunov‐based economic model predictive control (LEMPC) is considered. LEMPC is formulated with an ordinary differential equation model and is designed on the basis of an explicit stabilizing control law. To address closed‐loop stability under LEMPC, first, we establish that the steady‐state of the closed‐loop sampled‐data system resulting from the nonlinear continuous‐time delay system with state and input delays under a sample‐and‐hold implementation of the explicit stabilizing control law is practically stable. Second, conditions such that closed‐loop stability, in the sense of boundedness of the closed‐loop state, under LEMPC are derived. A chemical process example is used to demonstrate that indeed closed‐loop stability is maintained under LEMPC for sufficiently small time‐delays. To cope with performance degradation owing to the effect of input delay, a predictor feedback LEMPC methodology is also proposed. The predictor feedback LEMPC design employs a predictor to compute a prediction of the state after the input delay period and an LEMPC scheme that is formulated with a differential difference model (DDE) model, which describes the time‐delay system, initialized with the predicted state. The predictor feedback LEMPC is applied to the chemical process example and yields improved closed‐loop stability and economic performance properties. This article is protected by copyright. All rights reserved.
      PubDate: 2015-07-21T10:48:49.689961-05:
      DOI: 10.1002/aic.14964
  • Real‐time preventive sensor maintenance using robust moving horizon
           estimation and economic model predictive control
    • Authors: Liangfeng Lao; Matthew Ellis, Helen Durand, Panagiotis D. Christofides
      Abstract: Conducting preventive maintenance of measurement sensors in real‐time during process operation under feedback control while ensuring the reliability and improving the economic performance of a process is a central problem of the research area focusing on closed‐loop preventive maintenance of sensors and actuators. To address this problem, a robust moving horizon estimation (RMHE) scheme and an economic model predictive control (EMPC) system are combined to simultaneously achieve preventive sensor maintenance and optimal process economic performance with closed‐loop stability. Specifically, given a preventive sensor maintenance schedule, a robust moving horizon estimation scheme is developed that accommodates varying numbers of sensors to continuously supply accurate state estimates to a Lyapunov‐based economic model predictive control (LEMPC) system. Closed‐loop stability for this control approach can be proven under fairly general observability and stabilizability assumptions to be made precise in the manuscript. Subsequently, a chemical process example incorporating this RMHE‐based LEMPC scheme demonstrates its ability to maintain process stability and achieve optimal process economic performance as scheduled preventive maintenance is performed on the sensors. This article is protected by copyright. All rights reserved.
      PubDate: 2015-07-17T00:01:49.18498-05:0
      DOI: 10.1002/aic.14960
  • Depletion of cross‐stream diffusion in the presence of
    • Authors: Arman Sadeghi
      Abstract: This work presents an effort to analyze the viscoelasticity effects on transverse transport of neutral solutes between two miscible streams in an electrokinetic T‐sensor. The analysis is based on an approximate analytical solution for the depthwise averaged concentration, assuming a channel of large width to depth ratio for which a 1‐D profile is sufficient for describing the velocity field. We show that the solution derived is surprisingly accurate even for very small channel aspect ratios and the maximum error reduces to only about 1% when the aspect ratio is 5. The developed model reveals that the mixing length for a viscoelastic fluid may be by far larger than that for a Newtonian fluid. Moreover, the Taylor dispersion coefficient for electroosmotic flow of viscoelastic fluids, which its determination is a main part of the analysis, is found to be an increasing function of both the elasticity level and the EDL thickness. This article is protected by copyright. All rights reserved.
      PubDate: 2015-07-15T18:21:05.310829-05:
      DOI: 10.1002/aic.14955
  • Dynamic modeling and validation of a biomass hydrothermal pretreatment
           process ‐ A demonstration scale study
    • Abstract: Hydrothermal pretreatment of lignocellulosic biomass is a cost effective technology for second generation biorefineries. The process occurs in large horizontal and pressurized thermal reactors where the biomatrix is opened under the action of steam pressure and temperature to expose cellulose for the enzymatic hydrolysis process. Several by‐products are also formed, which disturb and act as inhibitors downstream. The objective of this study is to formulate and validate a large scale hydrothermal pretreatment dynamic model based on mass and energy balances, together with a complex conversion mechanism and kinetics. The study includes a comprehensive sensitivity and uncertainty analysis, with parameter estimation from real‐data in the 178‐185° range. To highlight the application utility of the model, a state estimator for biomass composition is developed. The predictions capture well the dynamic trends of the process, outlining the value of the model for simulation, control design, and optimization for full‐scale applications. This article is protected by copyright. All rights reserved.
      PubDate: 2015-07-15T18:20:40.575318-05:
      DOI: 10.1002/aic.14954
  • Three‐dimensional hydrogel encapsulated embryonic stem and carcinoma
           cells as culture platforms for cytotoxicity studies
    • Authors: Sneha Oberai; Kalpith Ramamoorthi, Jared Hara, Ailing Teo, Mayasari Lim, Prashanth Asuri
      Abstract: Our study describes the utility of alginate hydrogels for 3D culture of mouse embryonic stem cells (mESCs) and future development of 3D stem cell culture‐based in vitro screens of toxicity. Using alginate hydrogels of various stiffness, we first evaluated the impact of substrate modulus on mESC viability, proliferation, as well as expression of pluripotency and germ‐layer markers and observed that low concentration alginate hydrogels (0.5% and 1% alginate) were most suitable for long‐term culture of mESCs. These results were not unique to mESCs; long‐term viability and proliferation of mouse embryonic carcinoma cells (mECCs) was also best supported by similar conditions. Finally, we determined cytotoxic responses of alginate encapsulated cells to commercially available chemicals and interestingly observed similar responses for mESCs and mECCs, thereby suggesting that mECCs can predict stem cell responses to chemicals. These studies will facilitate future design of optimal stem cell‐based platforms of organ‐specific and developmental toxicity. This article is protected by copyright. All rights reserved.
      PubDate: 2015-07-15T18:20:17.058032-05:
      DOI: 10.1002/aic.14957
  • Refactoring β‐amyrin synthesis in Saccharomyces cerevisiae
    • Authors: Genlin Zhang; Qian Cao, Jingzhu Liu, Baiyang Liu, Jun Li, Chun Li
      Abstract: Triterpenoids are a highly diverse group of natural products and used particularly as medicine. Here, a strategy combining stepwise metabolic engineering and transcriptional control was developed to strengthen triterpenoid biosynthesis in Saccharomyces cerevisiae. Consequently, an efficient biosynthetic pathway for producing β‐amyrin, a commercially valuable compound and precursor of triterpenoids, was constructed through expressing a plant‐derived β‐amyrin synthase. Introducing a heterologous squalene monooxygenase greatly dragged intermediate metabolite squalene toward β‐amyrin. Increasing squalene pool by overexpressing IPP isomerase, FPP and squalene synthase further enhanced β‐amyrin synthesis of 49 folds. Through reconstructing the promoters with the binding site of transcription factor UPC2, directed transcriptional regulation on engineered pathway was availably achieved, resulting in β‐amyrin titer increased by 65 folds. Using ethanol fed‐batch fermentation, β‐amyrin titer was finally improved up to 138.80 mg/L with a yield of 16.30 mg/g dry cell, almost 185 and 232 and folds of the initially engineered strain respectively. This article is protected by copyright. All rights reserved.
      PubDate: 2015-07-15T01:52:31.035708-05:
      DOI: 10.1002/aic.14950
  • Integrated production scheduling and model predictive control of
           continuous processes
    • Authors: Michael Baldea; Juan Du, Jungup Park, Iiro Harjunkoski
      Abstract: The integration of production management and process control decisions is critical for improving economic performance of the chemical supply chain. In this paper, we propose a novel framework for integrating production scheduling and model predictive control (MPC) for continuous processes. Our framework is predicated on using a low‐dimensional time scale‐bridging model (SBM) that captures the closed‐loop process dynamics over the longer time scales that are relevant to scheduling calculations. The SBM is used as a constraint in a mixed‐integer dynamic formulation of the scheduling problem. To synchronize the scheduling and MPC calculations, we propose a novel scheduling‐oriented MPC concept, whereby the SBM is incorporated in the expression of the controller as a (soft) dynamic constraint and allows for obtaining an explicit description of the closed‐loop process dynamics. Our framework scales favorably with system size and provides desirable closed‐loop stability and performance properties for the resulting integrated scheduling and control problem. This article is protected by copyright. All rights reserved.
      PubDate: 2015-07-15T01:51:41.366151-05:
      DOI: 10.1002/aic.14951
  • Determination and comparison of rotational velocity in a pseudo 2D
           fluidized bed using Magnetic Particle Tracking and Discrete Particle
    • Authors: K.A. Buist; T.W. van Erdewijk, N.G. Deen, J.A.M. Kuipers
      Abstract: Modelling of dense granular flow has been subject to a large amount of research. Particularly discrete particle modelling has been of great importance because of the ability to describe the strongly coupled dynamics of the fluid and the solids in dense suspensions. Many studies have been reported on the validation of the translational particle velocities predicted by employing these models. The rotational motion however has received far less attention, mainly because of the spherical nature of the particles under investigation and the lack of techniques with the capability to study the rotational behaviour of the solid phase. In this study we will for the first time present experimental data on the rotational behaviour of particles in a pseudo 2D fluidized bed setup using Magnetic Particle Tracking (MPT). In addition the experimental results are compared to data obtained from discrete particle simulations. This article is protected by copyright. All rights reserved.
      PubDate: 2015-07-14T08:28:17.538249-05:
      DOI: 10.1002/aic.14949
  • Morphology of polystyrene/poly(methyl methacrylate) blends: Effects of
           carbon nanotubes aspect ratio and surface modification
    • Authors: Jiaxi Guo; Nicholas Briggs, Steven Crossley, Brian P. Grady
      Abstract: MWCNTs with aspect ratios (ARs) ranging from 94 to 474 were incorporated into polystyrene (PS)/poly(methyl methacrylate) (PMMA) blends using solution mixing and melt mixing. Also, two functionalized MWCNTs were prepared from the nanotubes having AR 94: one was oxidized by nitric acid while the other was further modified with amine‐terminated PS attached to carboxyl groups to form amides. The two functionalized MWCNTs (1 wt.%) were used to show that which phase the CNTs were located in could be controlled with nanotube surface chemistry. When nanotubes were confined to the minor phase, the size of the minor domain first decreased with adding low aspect ratio CNT as expected due to the increased viscosity of the minor phase. However, at higher aspect ratios the size increased beyond the size for the minor domain with no nanotubes, and finally the shape of the minor domain changed from spherical to an elongated irregular shape. This article is protected by copyright. All rights reserved.
      PubDate: 2015-07-06T03:08:31.518384-05:
      DOI: 10.1002/aic.14943
  • On identification of well‐conditioned nonlinear systems: Application
           to economic model predictive control of nonlinear processes
    • Authors: Anas Alanqar; Helen Durand, Panagiotis D. Christofides
      Abstract: This work focuses on economic model predictive control (EMPC) that utilizes well‐conditioned polynomial nonlinear state‐space models for processes with nonlinear dynamics. Specifically, the article initially addresses the development of a nonlinear system identification technique for a broad class of nonlinear processes which leads to the construction of polynomial nonlinear state‐space dynamic models which are well‐conditioned over a broad region of process operation in the sense that they can be correctly integrated in real‐time using explicit numerical integration methods via time steps that are significantly larger than the ones required by nonlinear state‐space models identified via existing techniques. Working within the framework of polynomial nonlinear state‐space (PNLSS) models, additional constraints are imposed in the identification procedure to ensure well‐conditioning of the identified nonlinear dynamic models. This development is key because it enables the design of Lyapunov‐based EMPC (LEMPC) systems for nonlinear processes using the well‐conditioned nonlinear models that can be readily implemented in real‐time since the computational burden required to compute the control actions within the process sampling period is reduced. A stability analysis for this LEMPC design is provided that guarantees closed‐loop stability of a process under certain conditions when an LEMPC based on a nonlinear empirical model is used. Finally, a classical chemical engineering reactor example demonstrates both the system identification and LEMPC design techniques, and the significant advantages in terms of computation time reduction in LEMPC calculations when using the nonlinear empirical model. This article is protected by copyright. All rights reserved.
      PubDate: 2015-07-03T00:50:43.244084-05:
      DOI: 10.1002/aic.14942
  • Mass transfer rate enhancement for CO2 separation by ionic liquids:
           theoretical study on the mechanism
    • Authors: Wenlong Xie; Xiaoyan Ji, Xin Feng, Xiaohua Lu
      Abstract: To promote the development of ionic liquid (IL) immobilized sorbents and supported IL membranes (SILMs) for CO2 separation, in this work, the kinetics of CO2 absorption/desorption in IL immobilized sorbents was studied using a novel method based on non‐equilibrium thermodynamics. It shows that the apparent chemical‐potential‐based mass‐transfer coefficients of CO2 were in three regions with 3‐order difference in magnitude for the IL‐film thicknesses in micro‐scale, 100 nm‐scale and 10 nm‐scale. Using a diffusion‐reaction theory, it is found that by tailoring the IL‐film thickness from micro‐scale to nano‐scale, the process was altered from diffusion‐control to reaction‐control, revealing the inherent mechanism for the dramatic rate enhancement. The extension to SILMs shows that the significant improvement of CO2 flux can be obtained theoretically for the membranes with nano‐scale IL‐films, which makes it feasible to implement CO2 separation by ILs with low investment cost. This article is protected by copyright. All rights reserved.
      PubDate: 2015-06-30T17:58:22.166741-05:
      DOI: 10.1002/aic.14932
  • Process to Planet: A Multiscale Modeling Framework for Sustainable
    • Authors: Rebecca J. Hanes; Bhavik R. Bakshi
      Abstract: To prevent the chance of unintended environmental harm, engineering decisions need to consider an expanded boundary that captures all relevant connected systems. Comprehensive models for sustainable engineering may be developed by combining models at multiple scales. Models at the finest “equipment” scale are engineering models based on fundamental knowledge. At the intermediate “value chain” scale, empirical models represent average production technologies, and at the coarsest “economy” scale, models represent monetary and environmental exchanges for industrial sectors in a national or global economy. However, existing methods for sustainable engineering design ignore the economy scale, while existing methods for life cycle assessment do not consider the equipment scale. This work proposes an integrated, multi‐scale modeling framework for connecting models from process to planet (P2P) and using them for sustainable engineering applications. The proposed framework is demonstrated with a toy problem, and potential applications of the framework including current and future work are discussed. This article is protected by copyright. All rights reserved.
      PubDate: 2015-06-30T06:02:43.832912-05:
      DOI: 10.1002/aic.14919
  • Sustainable Process Design by the Process to Planet Framework
    • Authors: Rebecca J. Hanes; Bhavik R. Bakshi
      Abstract: Sustainable process design (SPD) problems combine a process design problem with life cycle assessment (LCA) to optimize process economics and life cycle environmental impacts. While SPD makes use of recent advances in process systems engineering and optimization, its use of LCA has stagnated. Currently, only process LCA is utilized in SPD, resulting in designs based on incomplete and potentially inaccurate life cycle information. To address these shortcomings, the multi‐scale process to planet (P2P) modeling framework is applied to formulate and solve the SPD problem. The P2P framework offers a more comprehensive analysis boundary than conventional SPD and greater modeling detail than advanced LCA methodologies. Benefits of applying this framework to SPD are demonstrated with an ethanol process design case study. Results show that current methods shift emissions outside the analysis boundary, while applying the P2P modeling framework results in environmentally superior process designs. Future extensions of the P2P framework are discussed. This article is protected by copyright. All rights reserved.
      PubDate: 2015-06-30T05:28:25.579045-05:
      DOI: 10.1002/aic.14918
  • Pure H2 production through hollow fiber hydrogen‐selective MFI
           zeolite membranes using steam as sweep gas
    • Authors: Yuting Zhang; Qi Sun, Xuehong Gu
      Abstract: Hollow fiber MFI zeolite membranes were modified by catalytic cracking deposition of methyldiethoxysilane (MDES) to enhance their H2/CO2 separation performance and further employed in high temperature water gas shift membrane reactor (MR). Steam was used as the sweep gas in the MR for the production of pure H2. Extensive investigations were conducted on MR performance by variations of temperature, feed pressure, sweep steam flow rate and steam‐to‐CO ratio. CO conversion was obviously enhanced in the MR as compared with conventional packed‐bed reactor (PBR) due to the coupled effects of H2 removal as well as counter‐diffusion of sweep steam. Significant increment in CO conversion for MR vs. PBR was obtained at relatively low temperature and steam‐to‐CO ratio. A high H2 permeate purity of 98.2% could be achieved in the MR swept by steam. Moreover, the MR exhibited an excellent long‐term operating stability for 100 h in despite of the membrane quality. This article is protected by copyright. All rights reserved.
      PubDate: 2015-06-27T10:34:08.318729-05:
      DOI: 10.1002/aic.14924
  • Radial pressure profiles in a cold‐flow Gas‐Solid Vortex
    • Authors: M.N. Pantzali; J.Z. Kovacevic, V.N. Shtern, G.J. Heynderickx, G.B. Marin
      Abstract: A unique normalized radial pressure profile characterizes the bed of a Gas‐Solid Vortex Reactor (GSVR) over a range of particle densities and sizes, solid capacities and gas flow rates: 950‐1240 kg/m3, 1‐2 mm, 2 kg to maximum solids capacity and 0.4‐0.8 Nm3/s (corresponding to gas injection velocities of 55‐110 m/s) respectively. The combined momentum conservation equations of both gas and solid phases predict this pressure profile when accounting for the corresponding measured particle velocities. The pressure profiles for a given type of particles and a given solids loading but for different gas injection velocities merge into a single curve when normalizing the pressures with the pressure value downstream of the bed. The normalized ‐with respect to the overall pressure drop‐ pressure profiles for different gas injection velocities in particle‐free flow merge in a unique profile. This article is protected by copyright. All rights reserved.
      PubDate: 2015-06-24T02:26:22.259474-05:
      DOI: 10.1002/aic.14912
  • An integrated Framework for Scheduling and Control Using Fast Model
           Predictive Control
    • Authors: Jinjun Zhuge; Marianthi G. Ierapetritou
      Abstract: Integration of scheduling and control involves extensive information exchange and simultaneous decision making in industrial practice 1,2. Modeling the integration of scheduling and dynamic optimization at control level using mathematical programming results in a Mixed Integer Dynamic Optimization (MIDO) which is computationally expensive 3. In this study, we propose a framework for the integration of scheduling and control to reduce the model complexity and computation time. We identify a piece‐wise affine (PWA) model from the first principle model and integrate it with the scheduling level leading to a new integration. At the control level we employ fast Model Predictive Control (fast MPC) to track a dynamic reference. Fast MPC also overcomes the increasing dimensionality of multi‐parametric MPC in our previous study.4 Results of CSTR case studies prove that the proposed approach reduces the computing time by at least two orders of magnitude compared to the integrated solution using mp‐MPC. This article is protected by copyright. All rights reserved.
      PubDate: 2015-06-24T02:25:42.950339-05:
      DOI: 10.1002/aic.14914
  • Nonlinear PI Controllers with Output Transformations
    • Authors: Jietae Lee; Thomas F. Edgar
      Abstract: Well‐designed nonlinear proportional‐integral (PI) controllers are successful for nonlinear dynamical processes like linear PI controllers are for linear processes. Two nonlinear blocks representing proportional and integral terms can be designed so that the linearized controllers perform the same as linear PI controllers for linearized processes at the given operating points. For some nonlinear processes, nonlinear blocks for nonlinear PI controllers can be singular at some operating points, and control performances can be poor for set points near those points. To mitigate such disadvantages, new nonlinear PI controllers that introduce output transformations are proposed. Several examples are given, showing the performance of the proposed nonlinear PI controllers. This article is protected by copyright. All rights reserved.
      PubDate: 2015-06-17T17:54:55.625143-05:
      DOI: 10.1002/aic.14907
  • Influence of impeller type on hydrodynamics and gas‐liquid
           mass‐transfer in stirred airlift bioreactor
    • Pages: 3159 - 3171
      Abstract: The influence of impeller type in a mechanically stirred airlift bioreactor was analyzed in relation to the non‐Newtonian viscous fluids. The agitation was carried out through a marine impeller (axial impeller) and a paddle impeller (radial impeller) located along with the gas sparger in the region comprised by the riser. The bioreactor was sparged with air under different velocities (0.036–0.060 m s−1). Carboxymethylcellulose 1.94% and xanthan 1.80% were used as a fluid model. The gas holdup and volumetric mass‐transfer coefficient increased in up to five and three times, respectively, when compared to a conventional airlift bioreactor; however, better results were obtained when the straight paddle impeller type was used. The results suggest that the studied bioreactor can be used successfully in viscous fluid, and it can be more efficient than conventional airlift bioreactors. The results obtained suggest the use of radial impellers. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3159–3171, 2015
      PubDate: 2015-05-25T15:52:47.951932-05:
      DOI: 10.1002/aic.14871
  • A numerical comparison of precipitating turbulent flows between
           large‐eddy simulation and one‐dimensional turbulence
    • Authors: Alex W. Abboud; Ben B. Schroeder, Tony Saad, Sean T. Smith, Derek D. Harris, David O. Lignell
      Pages: 3185 - 3197
      Abstract: This study presents the results of computational fluid dynamics simulations of a multiphase, reacting, turbulent mixing layer in an idealized geometry. The purpose is to compare large‐eddy simulation (LES) to one‐dimensional turbulence (ODT) and examine the trends of the flow under differing mixing conditions. Aqueous streams are mixed together to precipitate polymorphs of calcium carbonate. The polymorphs of calcium carbonate are tracked numerically using population balance equations (PBE). Each PBE contains all of the relevant physical models to track the particle evolution including nucleation, growth, and aggregation. A simple subgrid mixing model that is convenient for use with PBEs was implemented in the LES code. The higher spatial resolution achievable with ODT allowed an investigation on the effect of resolution on the mixing‐model error. The Reynolds number of the flow is varied and is shown to cause a decrease in average particle sizes with higher mixing rates. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3185–3197, 2015
      PubDate: 2015-05-19T14:48:19.720538-05:
      DOI: 10.1002/aic.14870
  • A multiobjective optimization framework for design of integrated
           biorefineries under uncertainty
    • Authors: Aryan Geraili; Jose A. Romagnoli
      Pages: 3208 - 3222
      Abstract: A systematic approach for development of a reliable optimization framework to address the optimal design of integrated biorefineries in the face of uncertainty is presented. In the current formulation, a distributed strategy which is composed of different layers including strategic optimization, risk management, detailed mechanistic modeling, and operational level optimization is applied. In the strategic model, a multiobjective stochastic optimization approach is utilized to incorporate the tradeoffs between the cost and the financial risk. Then, Aspen Plus models are built to provide detailed simulation of biorefineries. In the final layer, an evolutionary algorithm is employed to optimize the operating condition. To demonstrate the effectiveness of the framework, a hypothetical case study referring to a multiproduct lignocellulosic biorefinery is utilized. The numerical results reveal the efficacy of the proposed approach; it provides decision makers with a quantitative analysis to determine the optimum capacity plan and operating conditions of the biorefinery. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3208–3222, 2015
      PubDate: 2015-05-13T09:26:57.678589-05:
      DOI: 10.1002/aic.14849
  • A numerical‐indicator‐based method for design of distributed
           wastewater treatment systems with multiple contaminants
    • Pages: 3223 - 3231
      Abstract: In the design of distributed wastewater treatment systems with multiple contaminants, it is very important to minimize unnecessary stream mixing to reduce total treatment flow rate as much as possible. A new numerical indicator, total mixing influence potential (TMIP), to reflect the influence of the stream mixing caused by performing a process on the total treatment flow rate of a distributed wastewater system is introduced. In design procedure, the TMIP value is calculated based on pinch principle. The process with the smallest TMIP value will be performed first. The results of a few literature examples show that designs with very low (even minimum) total treatment flow rates can be obtained with the method proposed. In addition, the method proposed is simple and of clear engineering insight. The calculation effort does not increase significantly when the number of streams, contaminants, and/or treatment units increases. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3223–3231, 2015
      PubDate: 2015-05-15T10:31:48.820547-05:
      DOI: 10.1002/aic.14863
  • Bayesian method for simultaneous gross error detection and data
    • Authors: Yuan Yuan; Shima Khatibisepehr, Biao Huang, Zukui Li
      Pages: 3232 - 3248
      Abstract: Process measurements collected from daily industrial plant operations are essential for process monitoring, control, and optimization. However, those measurements are generally corrupted by errors, which include gross errors and random errors. Conventionally, those two types of errors were addressed separately by gross error detection and data reconciliation. Solving the simultaneous gross error detection and data reconciliation problem using the hierarchical Bayesian inference technique is focused. The proposed approach solves the following problems in a unified framework. First, it detects which measurements contain gross errors. Second, the magnitudes of the gross errors are estimated. Third, the covariance matrix of the random errors is estimated. Finally, data reconciliation is performed using the maximum a posteriori estimation. The proposed algorithm is applicable to both linear and nonlinear systems. For nonlinear case, the algorithm does not involve any linearization or approximation steps. Numerical case studies are provided to demonstrate the effectiveness of the proposed method. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3232–3248, 2015
      PubDate: 2015-05-23T22:23:17.683191-05:
      DOI: 10.1002/aic.14864
  • A hierarchical method to integrated solvent and process design of physical
           CO2 absorption using the SAFT‐γ Mie approach
    • Authors: Jakob Burger; Vasileios Papaioannou, Smitha Gopinath, George Jackson, Amparo Galindo, Claire S. Adjiman
      Pages: 3249 - 3269
      Abstract: Molecular‐level decisions are increasingly recognized as an integral part of process design. Finding the optimal process performance requires the integrated optimization of process and solvent chemical structure, leading to a challenging mixed‐integer nonlinear programming (MINLP) problem. The formulation of such problems when using a group contribution version of the statistical associating fluid theory, SAFT‐γ Mie, to predict the physical properties of the relevant mixtures reliably over process conditions is presented. To solve the challenging MINLP, a novel hierarchical methodology for integrated process and solvent design (hierarchical optimization) is presented. Reduced models of the process units are developed and used to generate a set of initial guesses for the MINLP solution. The methodology is applied to the design of a physical absorption process to separate carbon dioxide from methane, using a broad selection of ethers as the molecular design space. The solvents with best process performance are found to be poly(oxymethylene)dimethylethers. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3249–3269, 2015
      PubDate: 2015-05-28T08:47:30.137766-05:
      DOI: 10.1002/aic.14838
  • Nonlinear process identification in the presence of multiple correlated
           hidden scheduling variables with missing data
    • Authors: Lei Chen; Shima Khatibisepehr, Biao Huang, Fei Liu, Yongsheng Ding
      Pages: 3270 - 3287
      Abstract: Identification of nonlinear processes in the presence of noise corrupted and correlated multiple scheduling variables with missing data is concerned. The dynamics of the hidden scheduling variables are represented by a state‐space model with unknown parameters. To assure generality, it is assumed that the multiple correlated scheduling variables are corrupted with unknown disturbances and the identification dataset is incomplete with missing data. A multiple model approach is proposed to formulate the identification problem of nonlinear systems under the framework of the expectation‐maximization algorithm. The parameters of the local process models and scheduling variable models as well as the hyperparameters of the weighting function are simultaneously estimated. The particle smoothing technique is adopted to handle the computation of expectation functions. The efficiency of the proposed method is demonstrated through several simulated examples. Through an experimental study on a pilot‐scale multitank system, the practical advantages are further illustrated. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3270–3287, 2015
      PubDate: 2015-06-01T12:23:08.589162-05:
      DOI: 10.1002/aic.14866
  • Dissipativity‐based distributed model predictive control with low
           rate communication
    • Authors: Chaoxu Zheng; Michael James Tippett, Jie Bao, Jinfeng Liu
      Pages: 3288 - 3303
      Abstract: Distributed or networked model predictive control (MPC) can provide a computationally efficient approach that achieves high levels of performance for plantwide control, where the interactions between processes can be determined from the information exchanged among controllers. Distributed controllers may exchange information at a lower rate to reduce the communication burden. A dissipativity‐based analysis is developed to study the effects of low communication rates on plantwide control performance and stability. A distributed dissipativity‐based MPC design approach is also developed to guarantee the plantwide stability and minimum plantwide performance with low communication rates. These results are illustrated by a case study of a reactor‐distillation column network. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3288–3303, 2015
      PubDate: 2015-06-28T15:02:08.914535-05:
      DOI: 10.1002/aic.14899
  • Intensification and kinetics of methane hydrate formation under heat
           removal by phase change of n‐tetradecane
    • Authors: Xiaofei Song; Feng Xin, Hongchao Yan, Xingang Li, Hongri Jia
      Pages: 3441 - 3450
      Abstract: A method of direct heat removal resulting from the phase change of n‐tetradecane was used to intensify the heat transfer during hydrate formation. The growth rates of methane hydrate in aqueous slurries containing 25–45 wt % of solid n‐tetradecane were investigated at pressures between 4.70 and 6.46 MPa (gauge) and near the fusion point of solid n‐tetradecane. Methane hydrate growth started at a practically constant rate, which became variable after a sudden increase. Two rate laws were established to correlate with the experimental data for the constant and variable rate stages. The methane hydrate growth rates achieved with solid n‐tetradecane were significantly enhanced compared with those obtained under indirect heat removal. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3441–3450, 2015
      PubDate: 2015-05-19T11:22:01.666638-05:
      DOI: 10.1002/aic.14867
  • Micro‐structured Bi1.5Y0.3Sm0.2O3−δ catalysts for
           oxidative coupling of methane
    • Authors: Nur Hidayati Othman; Zhentao Wu, Kang Li
      Pages: 3451 - 3458
      Abstract: Bi1.5Y0.3Sm0.2O3−δ (BYS), a ceramic material showing great activity and selectivity to oxidative coupling of methane (OCM), has been fabricated into catalyst rings (i.e., capillary tubes) with a plurality of self‐organized radial microchannels. The unique microchannels inside such BYS catalyst rings allow easier access of reactants, as well as increased the surface area, which potentially contributes to higher reaction efficiencies due to improved mass transfer. The micro‐structured BYS catalyst rings were investigated systematically via two types of reactors; (1) randomly packed fixed bed reactor and (2) monolithic‐like structured reactor. These two reactor designs have different flow patterns of reactants, that is, non‐ideal and ideal flows, which can significantly affect the final OCM performance. A remarkable improvement in C2+ yield (YC2+ > 20%) was obtained in the monolith‐like structured reactor, in contrast to randomly packed powder and micro‐structured rings (YC2+ 
      PubDate: 2015-06-02T09:56:33.458398-05:
      DOI: 10.1002/aic.14883
  • Salting‐out of acetone, 1‐butanol, and ethanol from dilute
           aqueous solutions
    • Authors: Shaoqu Xie; Conghua Yi, Xueqing Qiu
      Pages: 3470 - 3478
      Abstract: The salting‐out phase equilibria for acetone, 1‐butanol, and ethanol (ABE) from dilute aqueous solutions using potassium carbonate (K2CO3) and dipotassium hydrogen phosphate trihydrate (K2HPO4⋅3H2O) as outstanding salting‐out agents were investigated. Increasing the salt concentration strengthened the salting‐out effects and improved the distribution coefficients of all three solvents (ABE) significantly. Temperature had a slight effect on the phase equilibria. The K2HPO4 solution (69 wt %) showed a stronger salting‐out effect than the K2CO3 solution (56 wt %) on recovering ABE from dilute aqueous solutions. Dilute aqueous solutions containing more solvents increased the recoveries of acetone and 1‐butanol, while the results showed a negligible effect on the solubility of ABE. The solubility of ABE was also correlated well with the molar number of salt per gram of water in the aqueous phase. A new equation demonstrated this satisfactorily. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3470–3478, 2015
      PubDate: 2015-05-20T11:03:11.764919-05:
      DOI: 10.1002/aic.14872
  • Higher energy saving with new heat integration arrangement in
           heat‐integrated distillation column
    • Authors: Toshihiro Wakabayashi; Shinji Hasebe
      Pages: 3479 - 3488
      Abstract: In conventional heat‐integrated distillation columns (HIDiCs), the internal heat exchange is executed between the pressurized rectifying section and the stripping section, which are located at the same elevation. In such a structure, the amount of heat exchanged between two sections depends on the temperature profile of both sections. The resulting enthalpy profile inside the column departs from that in reversible distillation, which is the ideal distillation operation in view of energy conservation. More energy saving may be achieved by providing appropriate arrangement of heat exchanges between sections. The interactive graphical design method to determine the appropriate heat exchange arrangement in a previous paper was developed for a binary system. The design method was extended and applied to a multicomponent system by adopting the idea of a quasi‐binary system. Also, a new HIDiC structure that can realize the outcomes of the proposed design method was developed. The economics of the proposed structure was precisely evaluated through a case study of a commercial scale column. It demonstrated that the proposed structure has attractive economics. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3479–3488, 2015
      PubDate: 2015-05-23T22:23:40.419535-05:
      DOI: 10.1002/aic.14865
  • Semianalytical solution for power‐law polymer solution flow in a
           converging annular spinneret
    • Pages: 3489 - 3499
      Abstract: A semianalytical solution for a power‐law fluid flowing through a conical annulus was derived to estimate the velocity profile in the axial direction, the shear rate and the elongation rate within a spinneret during the spinning of hollow fiber membranes. The angle coefficient was introduced as a new parameter to account for the effect of radial flow and to modify the governing equation, which initially neglected the effect of radial flow. The results estimated from this semianalytical solution agreed more closely with computational fluid dynamics simulation results than those obtained from the approximate analytical solution in our previous study. By accurately predicting the velocity profile in the axial direction and the shear and elongation rates in a conical annulus, the solution derived in this study is expected to provide a reliable criterion for spinneret design to achieve a specified membrane morphology with a desired performance. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3489–3499, 2015
      PubDate: 2015-05-25T15:53:10.684137-05:
      DOI: 10.1002/aic.14875
  • Determination of the trichloroethylene diffusion coefficient in water
    • Authors: Federico Rossi; Raffaele Cucciniello, Adriano Intiso, Antonio Proto, Oriana Motta, Nadia Marchettini
      Pages: 3511 - 3515
      Abstract: Trichloroethylene (TCE) is a halogenated aliphatic organic compound frequently detected as pollutant in soils and ground water. To study the fate of TCE in water and to devise effective remediation strategies, a series of advection‐diffusion (dispersion) models, where the diffusion coefficient of TCE (DTCE) is an important parameter, have been developed. However, DTCE in water has never been experimentally determined and only theoretical values ( ≃1×10−5 cm2 s−1 at 25°C) are present in the literature. A new method based on the Taylor dispersion technique, which allows to measure DTCE in a broad range of temperature and, in principle, in any solvent is presented. At 25°C DTCE =  8.16±0.06×10−6 cm2 s−1 and the value increases almost linearly with the temperature, while, in the limit of the experimental error, is independent from [TCE] for dilute solutions. From the temperature dependence of DTCE, it was possible to calculate the specific TCE fitting constant in the well‐known Wilke and Chang theoretical relation and the activation energy of the diffusion process through the Arrhenius plot. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3511–3515, 2015
      PubDate: 2015-05-15T10:29:17.431033-05:
      DOI: 10.1002/aic.14861
  • A probabilistic model for correcting the directional sensitivity of
           optical probe measurements
    • Authors: Boung Wook Lee; Milorad P. Dudukovic
      Pages: 3516 - 3527
      Abstract: A probabilistic model is introduced for correcting the directional sensitivity of the optical probe technique routinely used to determine gas holdup and bubble dynamics in gas‐liquid systems. Measurements from optical probes oriented at various angles were collected from the tapered end of optical probes in regions where approximately unidirectional and bubbly flow conditions were observed. Based on logical assumptions, constitutive equations for a probabilistic model were formulated, and contributions to the overall local gas phase holdup from bubbles traveling in two opposite directions were quantified. The results demonstrate a novel and useful way to interpret optical probe measurements. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3516–3527, 2015
      PubDate: 2015-05-27T10:12:49.831594-05:
      DOI: 10.1002/aic.14860
  • Three‐dimensional numerical simulation of coalescence and
           interactions of multiple horizontal bubbles rising in shear‐thinning
    • Authors: Jingru Liu; Chunying Zhu, Xiaoda Wang, Taotao Fu, Youguang Ma, Huaizhi Li
      Pages: 3528 - 3546
      Abstract: The dynamics of multiple horizontal bubbles rising from different orifice arrangements in shear‐thinning fluids was simulated numerically by three‐dimensional Volume of Fluid method. The effects of bubble size, rheological properties of shear‐thinning fluids, and orifice structure arrangements on multiple bubbles interaction and coalescence were analyzed, and the mechanisms of bubble coalescence and breakup were fully discussed and elucidated. The variation of bubble rising velocity during coalescence process and freely rising processes for different orifice arrangements was also deeply investigated. The critical initial horizontal intervals for coalescence of multiple horizontal bubbles with various orifice arrangements were attained by simulation, which could serve as the critical criterion of bubble coalescence or noncoalescence. Furthermore, the critical bubble interval was predicted based on the film drainage model, the prediction accords well with the simulation result and is quite conducive for the design and optimization of perforated gas–liquid contact equipment. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3528–3546, 2015
      PubDate: 2015-05-27T10:15:16.521545-05:
      DOI: 10.1002/aic.14874
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